Evaluation of hydrogen embrittlement and temper embrittlement by key curve method in instrumented Charpy test

NASA Astrophysics Data System (ADS)

Ohtsuka, N.; Shindo, Y.; Makita, A.

2010-06-01

Instrumented Charpy test was conducted on small sized specimen of 21/4Cr-1Mo steel. In the test the single specimen key curve method was applied to determine the value of fracture toughness for the initiation of crack extension with hydrogen free, KIC, and for hydrogen embrittlement cracking, KIH. Also the tearing modulus as a parameter for resistance to crack extension was determined. The role of these parameters was discussed at an upper shelf temperature and at a transition temperature. Then the key curve method combined with instrumented Charpy test was proven to be used to evaluate not only temper embrittlement but also hydrogen embrittlement.

46 CFR 154.610 - Design temperature not colder than 0 °C (32 °F).

Code of Federal Regulations, 2011 CFR

2011-10-01

... Charpy V-notch impact energy must be determined for: (1) Each plate as rolled; and (2) Each five short... orientation and required impact energy of a 10 mm × 10 mm (0.394 in. × 0.394 in.) Charpy V-notch specimen must... temperature of the Charpy V-notch specimens is as follows: Material Thickness Test Temperature t≤20 mm (0.788...

Modeling and simulation of Charpy impact test of maraging steel 300 using Abaqus

NASA Astrophysics Data System (ADS)

Madhusudhan, D.; Chand, Suresh; Ganesh, S.; Saibhargavi, U.

2018-03-01

This work emphasizes the modeling and simulation of Charpy impact test to evaluate fracture energy at different pendulum velocities of armor maraging steel 300 using ABAQUS. To evaluate the fracture energy, V-notch specimen is fractured using the Johnson and Cook Damage model. The Charpy impact tests are of great importance related to fracture properties of steels. The objective of this work is to present absorbed energy variation at pendulum velocities of 5 m/sec, 6 m/sec, 7 m/sec and 9 m/sec in addition to stress distribution at v-notch. Finite Element Method of modeling for three dimensional specimens is used for simulation in commercial software of ABAQUS.

Evaluation of Amorphous Ribbon Reinforced Resin Matrix Composites.

DTIC Science & Technology

1980-04-30

standard E-23 for impact testing of subsize Charpy specimens. To insure uniform impact loading for specimens of different depth, shims were fabricated to...KID Values for Charpy V-Notch Specimens Table 43 Room Temperature Stress-Rupture Data-Transverse Ribbon Orientation Table 44 Material Property Summary...standard size notched Charpy specimens (b - W - 10 am), the composite impact energy was 10 joules while impact energies of 18 joules and 23 joules are

Heat Treatment Investigation of 4330 Vanadium-Modified Steel

DTIC Science & Technology

1989-08-01

the desired properties, using the results from the tensile and subsized Charpy impact tests on the 1 2-inch-diameter stock our further investigations...for the subsized Charpy specimens is shown graphically in Appendix C as a function of tempering temperature. This data gave a good indication that the... Charpy energy for full-sized specimens (0.394-inch-square cross section) would be near our expected values. Due to the dimensions of the subsized

A modified correlation between KJIC and Charpy V-notch impact energy of Chinese SA508-III steel at the upper shelf

NASA Astrophysics Data System (ADS)

Li, Xiangqing; Song, Yuxuan; Ding, Zhenyu; Bao, Shiyi; Gao, Zengliang

2018-07-01

The fracture toughness plays a significant role in the structural integrity assessment of reactor pressure vessels (RPVs) in service temperature. The Charpy V-notch (CVN) impact test is used to estimate fracture toughness (KIC or KJIC) indirectly since universal fracture toughness tests are costly, sophisticated and frequently invalid. In this study, a modified correlation which based on the typical model of KJIC-CVN at the upper shelf was established for Chinese SA508-III steel. Thereinto, the effect of test temperature (T) was directly considered in the correlation. To assess the accuracy of fracture toughness when calculating from the value of Charpy-V notch impact energy by using the modified correlation, both the Charpy-V notch impact tests and fracture toughness tests for Chinese SA508-III steel were conducted at different temperatures (100 °C, 150 °C, 200 °C, 250 °C and 320 °C). The results showed that the modified correlation exhibited the high precision for estimating fracture toughness of Chinese SA508-III steel and the relative error for tested and estimated results is within 8%, which is lower than that of other correlations.

Metallurgical Examination of Failed T-158 Cast Austempered Ductile Iron (CADI) Track Shoes

DTIC Science & Technology

1994-06-01

hardness testing, fracture toughness testing and Charpy impact testing were performed. In each case, the largest possible specimens were fabricated...However, due to geometrical restrictions, the tensile, fracture toughness and impact specimens were subsized . Tensile Testing Tensile coupons were...at 5OOoF for 4 hours. Mag. 1000x. 36 ‘_ Fracture Face A bolt holes Fracture Face C T = Tensile FT = Fracture Toughness NC =Notched Charpy Impact UN

Fracture toughness testing of Linde 1092 reactor vessel welds in the transition range using Charpy-sized specimens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pavinich, W.A.; Yoon, K.K.; Hour, K.Y.

1999-10-01

The present reference toughness method for predicting the change in fracture toughness can provide over estimates of these values because of uncertainties in initial RT{sub NDT} and shift correlations. It would be preferable to directly measure fracture toughness. However, until recently, no standard method was available to characterize fracture toughness in the transition range. ASTM E08 has developed a draft standard that shows promise for providing lower bound transition range fracture toughness using the master curve approach. This method has been successfully implemented using 1T compact fracture specimens. Combustion Engineering reactor vessel surveillance programs do not have compact fracture specimens.more » Therefore, the CE Owners Group developed a program to validate the master curve method for Charpy-sized and reconstituted Charpy-sized specimens for future application on irradiated specimens. This method was validated for Linde 1092 welds using unirradiated Charpy-sized and reconstituted Charpy-sized specimens by comparison of results with those from compact fracture specimens.« less

Influence of specimen dimensions on ductile-to-brittle transition temperature in Charpy impact test

NASA Astrophysics Data System (ADS)

Rzepa, S.; Bucki, T.; Konopík, P.; Džugan, J.; Rund, M.; Procházka, R.

2017-02-01

This paper discusses the correlation between specimen dimensions and transition temperature. Notch toughness properties of Standard Charpy-V specimens are compared to samples with lower width (7.5 mm, 5 mm, 2.5 mm) and sub-size Charpy specimens with cross section 3×4. In this study transition curves are correlated with lateral ductile part of fracture related ones for 5 considered geometries. Based on the results obtained, correlation procedure for transition temperature determination of full size specimens defined by fracture appearance of sub-sized specimens is proposed.

A simple procedure for synthesizing Charpy impact energy transition curves from limited test data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosenfeld, M.J.

1996-12-31

The importance of Charpy V-notch testing of pipe has been well established in the pipeline industry. Until now, it has been necessary to perform a number of tests in order to develop the toughness transition curve. A method is described which makes possible forecasting the full-scale toughness transition from a single subsize test datum to an acceptable degree of accuracy. This is potentially useful where historical test results or material samples available for testing are limited in quantity. Worked examples illustrating the use of the relationships are given.

Validation Study of Unnotched Charpy and Taylor-Anvil Impact Experiments using Kayenta

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamojjala, Krishna; Lacy, Jeffrey; Chu, Henry S.

2015-03-01

Validation of a single computational model with multiple available strain-to-failure fracture theories is presented through experimental tests and numerical simulations of the standardized unnotched Charpy and Taylor-anvil impact tests, both run using the same material model (Kayenta). Unnotched Charpy tests are performed on rolled homogeneous armor steel. The fracture patterns using Kayenta’s various failure options that include aleatory uncertainty and scale effects are compared against the experiments. Other quantities of interest include the average value of the absorbed energy and bend angle of the specimen. Taylor-anvil impact tests are performed on Ti6Al4V titanium alloy. The impact speeds of the specimenmore » are 321 m/s and 393 m/s. The goal of the numerical work is to reproduce the damage patterns observed in the laboratory. For the numerical study, the Johnson-Cook failure model is used as the ductile fracture criterion, and aleatory uncertainty is applied to rate-dependence parameters to explore its effect on the fracture patterns.« less

Preparation of reconstituted Charpy V-notch impact specimens for generating pressure vessel steel fracture toughness data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perrin, J.S.; Fromm, E.O.; Server, W.L.

1982-01-01

The arc stud welding process has been adapted for use in producing reconstituted Charpy V-notch impact specimens. In this process, each half of a tested and fractured Charpy specimen is used as the central region of a reconstituted specimen. End tabs are joined to one half of a fractured specimen by a specially designed stud welding apparatus. SA533B-1 and SA508-2 unirradiated and irradiated pressure vessel steel specimens have been produced. Both conventional and precracked reconstituted specimen data have been produced. Both types of data have been shown to be in excellent agreement with original specimen data. The arc stud weldingmore » process can therefore be used to increase the amount of data obtainable from a limited number of specimens or to obtain Charpy data when full size specimens cannot otherwise be obtained.« less

A new tensile impact test for the toughness characterization of sheet material

NASA Astrophysics Data System (ADS)

Könemann, Markus; Lenz, David; Brinnel, Victoria; Münstermann, Sebastian

2018-05-01

In the past, the selection of suitable steels has been carried out primarily based on the mechanical properties of different steels. One of these properties is the resistance against crack propagation. For many constructions, this value plays an important role, because it can compare the impact toughness of different steel grades easily and gives information about the loading capacity of the specific materials. For thin sheets, impact toughness properties were usually not considered. One of the reasons for this is that the Charpy-impact test is not applicable for sheets with thicknesses below 2 mm. For a long time, this was not relevant because conventional steels had a sufficient impact toughness in a wide temperature range. However, since new multiphase steel grades with improved mechanical property exploitations are available, it turned out that impact toughness properties need to be considered during the component design phase, as the activation of the cleavage fracture mechanism is observed under challenging loading conditions. Therefore, this work aims to provide a new and practical testing procedure for sheet material or thin walled structures. The new testing procedure is based on tensile tests conducted in an impact pendulum similar to the Charpy impact hammer. A new standard geometry is provided, which enables a comparison between different steels or steel grades. A connection to the conventional Charpy test is presented using a damage mechanics model, which predicts material failure with consideration of to the stress state at various temperatures. Different specimen geometries are analysed to cover manifold stress states. A special advantage of the damage mechanics model is also the possibility to predict the materials behaviour in the transition area. To verify the method a conventional steel was tested in Charpy tests as well as in the new tensile impact test.

Dynamic J sub I-R Curve Testing of HY-130 Steel.

DTIC Science & Technology

1981-10-01

Society for Testing and Materials 0C Degrees Celsius COD Crack-opening displacement CT Compact tension CVN Charpy V-notch dia Diameter in-lb/in 2 Inch...inches per second. A key curve for HY-130 plate was developed under dynamic loading conditions using subsized compact specimens and was applied to...face grooves were machined along the crack line to a total section reduction of 20% with a standard Charpy V-notch (CVN) cutter (450 included angle

Nuclear power plant life extension using subsize surveillance specimens. Performance report (4/15/92 - 4/14/98)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, Arvind S.

2001-03-05

A new methodology to predict the Upper Shelf Energy (USE) of standard Charpy specimens (Full size) based on subsize specimens has been developed. The prediction methodology uses Finite Element Modeling (FEM) to model the fracture behavior. The inputs to FEM are the tensile properties of material and subsize Charpy specimen test data.

The Charpy impact properties of martensitic 10.6% Cr steel (MANET-1) before and after neutron exposure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rieth, M.; Dafferner, B.; Rohrig, H.D.

1994-12-31

The MANET-I martensitic 10.6% Cr type of steel was developed as a potential structural material for the first wall and the blanket of a fusion device within the framework of the Nuclear Fusion Project. An extensive irradiation program (FRUST/SIENA) was elaborated to study the influence of radiation upon the Charpy impact characteristics. In addition to unirradiated reference specimens, 87 irradiated subsize Charpy specimens (3 x 4 x 27 mm{sup 3}) were examined under eight different heat treatments at irradiation temperatures between 287{degrees}C and 475{degrees}C and exposure doses of 5 dpa to 15 dpa. On the basis of the numerous testmore » results and their interpretation it is possible to describe radiation induced material embrittlement, and, consequently, the deterioration of the Charpy impact properties. The description is limited, on the one hand, by the variations in the test results and, on the other hand, by the gaps in the test matrix. Therefore, additional investigations, especially in the low irradiation temperature and low dose regimes will be the subject of further ongoing work.« less

Microstructural characterization of Charpy-impact-tested nanostructured bainite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsai, Y.T.; Chang, H.T.; Huang, B.M.

2015-09-15

In this work, a possible cause of the extraordinary low impact toughness of nanostructured bainite has been investigated. The microstructure of nanostructured bainite consisted chiefly of carbide-free bainitic ferrite with retained austenite films. X-ray diffractometry (XRD) measurement indicated that no retained austenite existed in the fractured surface of the Charpy-impact-tested specimens. Fractographs showed that cracks propagated mainly along bainitic ferrite platelet boundaries. The change in microstructure after impact loading was verified by transmission electron microscopy (TEM) observations, confirming that retained austenite was completely transformed to strain-induced martensite during the Charpy impact test. However, the zone affected by strained-induced martensite wasmore » found to be extremely shallow, only to a depth of several micrometers from the fracture surface. It is appropriately concluded that upon impact, as the crack forms and propagates, strain-induced martensitic transformation immediately occurs ahead of the advancing crack tip. The successive martensitic transformation profoundly facilitates the crack propagation, resulting in the extremely low impact toughness of nanostructured bainite. Retained austenite, in contrast to its well-known beneficial role, has a deteriorating effect on toughness during the course of Charpy impact. - Highlights: • The microstructure of nanostructured bainite consisted of nano-sized bainitic ferrite subunits with retained austenite films. • Special sample preparations for SEM, XRD and TEM were made, and the strain-affected structures have been explored. • Retained austenite films were found to transform into martensite after impact loading, as evidenced by XRD and TEM results. • The zone of strain-induced martensite was found to extend to only several micrometers from the fracture surface. • The poor Charpy impact toughness is associated with the fracture of martensite at a high strain rate during impact loading.« less

Charpy impact toughness of martensitic steels irradiated in FFTF: Effect of heat treatment

NASA Astrophysics Data System (ADS)

Klueh, R. L.; Alexander, D. J.

Charpy tests were made on plates of 9Cr-1MoVNb and 12Cr-1MoVW steels given four different normalizing-and-tempering treatments. One-third-size Charpy specimens from each steel were irradiated to 7.4 - 8 (times) 10(sup 26) n/m(sup 2) (about 34 - 37 dpa) at 420 C in the Materials Open Test Assembly of the Fast Flux Test Facility. Specimens were also thermally aged to 20000 h at 400 C to determine the effect of aging during irradiation. Previous work on these steels irradiated to 4 - 5 dpa at 365 C in MOTA were reexamined in light of the new results. The tests indicated that prior austenite grain size, which was varied by different normalizing treatments, had an effect on impact behavior of the 9Cr-1MoVNb but not on the 12Cr-1MoVW. Tempering treatment had relatively little effect on the shift in DBTT for both steels. Conclusions are presented on how heat treatment can be used to optimize properties.

Ares I-X USS Material Testing

NASA Technical Reports Server (NTRS)

Dawicke, David S.; Smith, Stephen W.; Raju, Ivatury S.

2008-01-01

An independent assessment was conducted to determine the critical initial flaw size (CIFS) for the flange-to-skin weld in the Ares I-X Upper Stage Simulator (USS). Material characterization tests were conducted to quantify the material behavior for use in the CIFS analyses. Fatigue crack growth rate, Charpy impact, and fracture tests were conducted on the parent and welded A516 Grade 70 steel. The crack growth rate tests confirmed that the material behaved in agreement with literature data and that a salt water environment would not significantly degrade the fatigue resistance. The Charpy impact tests confirmed that the fracture resistance of the material did not have a significant reduction for the expected operational temperatures of the vehicle.

Certification of NIST Room Temperature Low-Energy and High-Energy Charpy Verification Specimens

PubMed Central

Lucon, Enrico; McCowan, Chris N.; Santoyo, Ray L.

2015-01-01

The possibility for NIST to certify Charpy reference specimens for testing at room temperature (21 °C ± 1 °C) instead of −40 °C was investigated by performing 130 room-temperature tests from five low-energy and four high-energy lots of steel on the three master Charpy machines located in Boulder, CO. The statistical analyses performed show that in most cases the variability of results (i.e., the experimental scatter) is reduced when testing at room temperature. For eight out of the nine lots considered, the observed variability was lower at 21 °C than at −40 °C. The results of this study will allow NIST to satisfy requests for room-temperature Charpy verification specimens that have been received from customers for several years: testing at 21 °C removes from the verification process the operator’s skill in transferring the specimen in a timely fashion from the cooling bath to the impact position, and puts the focus back on the machine performance. For NIST, it also reduces the time and cost for certifying new verification lots. For one of the low-energy lots tested with a C-shaped hammer, we experienced two specimens jamming, which yielded unusually high values of absorbed energy. For both specimens, the signs of jamming were clearly visible. For all the low-energy lots investigated, jamming is slightly more likely to occur at 21 °C than at −40 °C, since at room temperature low-energy samples tend to remain in the test area after impact rather than exiting in the opposite direction of the pendulum swing. In the evaluation of a verification set, any jammed specimen should be removed from the analyses. PMID:26958453

Certification of NIST Room Temperature Low-Energy and High-Energy Charpy Verification Specimens.

PubMed

Lucon, Enrico; McCowan, Chris N; Santoyo, Ray L

2015-01-01

The possibility for NIST to certify Charpy reference specimens for testing at room temperature (21 °C ± 1 °C) instead of -40 °C was investigated by performing 130 room-temperature tests from five low-energy and four high-energy lots of steel on the three master Charpy machines located in Boulder, CO. The statistical analyses performed show that in most cases the variability of results (i.e., the experimental scatter) is reduced when testing at room temperature. For eight out of the nine lots considered, the observed variability was lower at 21 °C than at -40 °C. The results of this study will allow NIST to satisfy requests for room-temperature Charpy verification specimens that have been received from customers for several years: testing at 21 °C removes from the verification process the operator's skill in transferring the specimen in a timely fashion from the cooling bath to the impact position, and puts the focus back on the machine performance. For NIST, it also reduces the time and cost for certifying new verification lots. For one of the low-energy lots tested with a C-shaped hammer, we experienced two specimens jamming, which yielded unusually high values of absorbed energy. For both specimens, the signs of jamming were clearly visible. For all the low-energy lots investigated, jamming is slightly more likely to occur at 21 °C than at -40 °C, since at room temperature low-energy samples tend to remain in the test area after impact rather than exiting in the opposite direction of the pendulum swing. In the evaluation of a verification set, any jammed specimen should be removed from the analyses.

Estimation of Ksub Ic from slow bend precracked Charpy specimen strength ratios

NASA Technical Reports Server (NTRS)

Succop, G.; Brown, W. F., Jr.

1976-01-01

Strength ratios are reported which were derived from slow bend tests on 0.25 inch thick precracked Charpy specimens of steels, aluminum alloys, and a titanium alloy for which valid K sub Ic values were established. The strength ratios were used to develop calibration curves typical of those that could be useful in estimating K sub Ic for the purposes of alloy development of quality control.

Correlation of Selected Subsize Charpy Bars versus the Standard Charpy Bar

DTIC Science & Technology

1958-05-01

WAL TR 112/91 TECIINICAL REPORT r- i -I WATERTOWN ARSENAL LABORATORI ES CORRELATION OF SELECTED SUBSIZE CHARPY BARS VERSUS THE STANDARD CHARPY BAR...DTIC BY fitELECTED CHARLES Ht. CURIL MAY 8 19813 GEORGE M. OR14ER 0.0. PROJECT: INDUSTRIAL PREPAREDNESS MEASURE, ,... DEVELOPMENT OF SUBSIZE CHARPY ...STANDARD P.E.S.D. NO.: 60302l281-16-65003 REPORT NO.: WAL TR 112191 FILING SUBJECT: SUBSIZE CHARPY IThis documnt~ has mo f1 P~ub1c teT -rie and mczlelIN

Fracture-Toughness Analysis in Transition-Temperature Region of Three American Petroleum Institute X70 and X80 Pipeline Steels

NASA Astrophysics Data System (ADS)

Shin, Sang Yong; Woo, Kuk Je; Hwang, Byoungchul; Kim, Sangho; Lee, Sunghak

2009-04-01

The fracture toughness in the transition-temperature region of three American Petroleum Institute (API) X70 and X80 pipeline steels was analyzed in accordance with the American Society for Testing and Materials (ASTM) E1921-05 standard test method. The elastic-plastic cleavage fracture toughness ( K Jc ) was determined by three-point bend tests, using precracked Charpy V-notch (PCVN) specimens; the measured K Jc values were then interpreted by the three-parameter Weibull distribution. The fracture-toughness test results indicated that the master curve and the 98 pct confidence curves explained the variation in the measured fracture toughness well. The reference temperatures obtained from the fracture-toughness test and index temperatures obtained from the Charpy impact test were lowest in the X70 steel rolled in the two-phase region, because this steel had smaller effective grains and the lowest volume fraction of hard phases. In this steel, few hard phases led to a higher resistance to cleavage crack initiation, and the smaller effective grain size led to a higher possibility of crack arrest, thereby resulting in the best overall fracture properties. Measured reference temperatures were then comparatively analyzed with the index temperatures obtained from the Charpy impact test, and the effects of microstructures on these temperatures were discussed.

Charpy V-notch properties and microstructures of narrow gap ferritic welds of a quenched and tempered steel plate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Powell, G.L.F.; Herfurth, G.

1998-11-01

Multipass welds of quenched and tempered 50-mm-thick steel plate have been deposited by a single wire narrow gap process using both gas metal arc welding (GMAW) and submerged arc welding (SAW). Of the five welds, two reported much lower Charpy V-notch (CVN) values when tested at {minus} 20 C. The CVN toughness did not correlate with either the welding process or whether the power source was pulsed or nonpulsed. The only difference in the ferritic microstructure between the two welds of low Charpy values and the three of high values was the percentage of acicular ferrite. There was no effectmore » of the percentage of as-deposited reheated zones intersected by the Charpy notch or the microhardness of the intercellular-dendritic regions. In all welds, austenite was the microconstituent between the ferrite laths. The percentage of acicular ferrite correlated with the presence of MnO, TiO{sub 2}, {gamma} Al{sub 2}O{sub 3}, or MnO. Al{sub 2}O{sub 3} as the predominant crystalline compound in the oxide inclusions. In turn, the crystalline compound depended on the aluminum-to-titanium ratio in both the weld deposits and the oxide inclusions. In addition to the presence of less acicular ferrite, the two welds that showed lower Charpy values also reported more oxide inclusions greater than 1 {micro}m in diameter. The combination of more oxide inclusions greater than 1 {micro}m and less acicular ferrite is considered to be the explanation for the lower Charpy values.« less

Influence of Stacking Sequence and Notch Angle on the Charpy Impact Behavior of Hybrid Composites

NASA Astrophysics Data System (ADS)

Behnia, S.; Daghigh, V.; Nikbin, K.; Fereidoon, A.; Ghorbani, J.

2016-09-01

The low-velocity impact behavior of hybrid composite laminates was investigated. The epoxy matrix was reinforced with aramid, glass, basalt, and carbon fabrics using the hand lay-up technique. Different stacking sequences and notch angles were and notch angles considered and tested using a Charpy impact testing machine to study the hybridization and notch angle effects on the impact response of the hybrid composites. The energy absorption capability of specimens with different stacking sequences and notch angles is compared and discussed. It is shown that the hybridization can enhance the mechanical performance of composite materials.

Effects of radiation on crack-initiation and crack-arrest toughness for SA508 Cl. 3 steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Milella, P.P.; Pini, A.; Iskander, S.K.

1995-11-01

An investigation was carried out to determine the effects of neutron irradiation, conducted in several different test-reactors at approximately 280 C, on the mechanical properties of an SA508 Class 3 carbon steel ring forging produced in Italy as a prototype of a pressurized water reactor vessel. The research had two primary objectives: (1) to investigate the effect of a various levels of neutron irradiation (fluences from 1 to 5.5 10{sup 19} n/cm{sup 2} [E>1 MeV]) on the strength, initiation and arrest toughness and ductile-to-brittle transition temperature, and (2) to determine if Charpy data and empirical prediction equations provide conservative estimatesmore » of irradiation effects on the K{sub Ic} and K{sub Ia} transition curves. The paper reports results from tension, Charpy V-notch (CVN) fracture toughness, and crack-arrest tests performed on both unirradiated and irradiated material. It was found that both Charpy V-notch transition temperature shifts and two prediction equations provided conservative estimates of shifts in fracture initiation and fracture arrest transition temperatures for the steel investigated. The 54 C shift of the Charpy V-notch transition curves at a fluence level of 5.5 10{sup 19} n/cm{sup 2} suggests the possibility of extending the component life beyond the common 40 year design life.« less

Grain refinement of high strength steels to improve cryogenic toughness

NASA Technical Reports Server (NTRS)

Rush, H. F.

1985-01-01

Grain-refining techniques using multistep heat treatments to reduce the grain size of five commercial high-strength steels were investigated. The goal of this investigation was to improve the low-temperature toughness as measured by Charpy V-notch impact test without a significant loss in tensile strength. The grain size of four of five alloys investigated was successfully reduced up to 1/10 of original size or smaller with increases in Charpy impact energy of 50 to 180 percent at -320 F. Tensile properties were reduced from 0 to 25 percent for the various alloys tested. An unexpected but highly beneficial side effect from grain refining was improved machinability.

Low temperature impact toughness of the main gas pipeline steel after long-term degradation

NASA Astrophysics Data System (ADS)

Maruschak, Pavlo O.; Danyliuk, Iryna M.; Bishchak, Roman T.; Vuherer, Tomaž

2014-12-01

The correlation of microstructure, temperature and Charpy V-notch impact properties of a steel 17G1S pipeline steel was investigated in this study. Within the concept of physical mesomechanics, the dynamic failure of specimens is represented as a successive process of the loss of shear stability, which takes place at different structural/scale levels of the material. Characteristic stages are analyzed for various modes of failure, moreover, typical levels of loading and oscillation periods, etc. are determined. Relations between low temperature derived through this test, microstructures and Charpy (V-notch) toughness test results are also discussed in this paper.

A mechanical property and stress corrosion evaluation of VIM-ESR-VAR work strengthened and direct double aged Inconel 718 bar material

NASA Technical Reports Server (NTRS)

Montano, J. W.

1986-01-01

Presented are the mechanical properties and the stress corrosion resistance of triple melted vacuum induction melted (VIM), electro-slag remelted (ESR), and vacuum arc remelted (VAR), solution treated, work strengthened and direct double aged Inconel 718 alloy bars 4.00 in. (10.16) and 5.75 in. (14.60 cm) diameter. Tensile, charpy v-notched impact, and compact tension specimens were tested at ambient temperature in both the longitudinal and transverse directions. Longitudinal tensile and yield strengths in excess of 220 ksi (1516.85 MPa) and 200 ksi (1378.00 MPa) respectively, were realized at ambient temperature. Additional charpy impact and compact tension tests were performed at -100 F (-73 C). Longitudinal charpy impact strength equalled or exceeded 12.0 ft-lbs (16.3 Joules) at ambient and at -100 F(-73 C) while longitudinal compact (LC) tension fracture toughness strength remained above 79 ksi (86.80 MPa) at ambient and at -100 F(-73 C) temperatures. No failures occurred in the longitudinal or transverse tensile specimens stressed to 75 and 100 percent of their respective yield strengths and exposed to a salt fog environment for 180 days. Tensile tests performed after the stress corrosion test indicated no mechanical property degradation.

Room-Temperature Charpy Impact Property of 3D-Printed 15-5 Stainless Steel

NASA Astrophysics Data System (ADS)

Sagar, Sugrim; Zhang, Yi; Wu, Linmin; Park, Hye-Young; Lee, Je-Hyun; Jung, Yeon-Gil; Zhang, Jing

2018-01-01

In this study, the room-temperature Charpy impact property of 3D-printed 15-5 stainless steel was investigated by a combined experimental and finite element modeling approach. The experimentally measured impact energy is 10.85 ± 1.20 J/cm2, which is comparable to the conventionally wrought and non-heat treated 15-5 stainless steel. In parallel to the impact test experiment, a finite element model using the Johnson-Cook material model with damage parameters was developed to simulate the impact test. The simulated impact energy is 10.46 J/cm2, which is in good agreement with the experimental data. The fracture surface from the experimentally tested specimen suggests that the 3D-printed specimens undergo predominately brittle fracture.

Mechanical properties and fracture toughness of rail steels and thermite welds at low temperature

NASA Astrophysics Data System (ADS)

Wang, Yuan-qing; Zhou, Hui; Shi, Yong-jiu; Feng, Bao-rui

2012-05-01

Brittle fracture occurs frequently in rails and thermite welded joints, which intimidates the security and reliability of railway service. Railways in cold regions, such as Qinghai-Tibet Railway, make the problem of brittle fracture in rails even worse. A series of tests such as uniaxial tensile tests, Charpy impact tests, and three-point bending tests were carried out at low temperature to investigate the mechanical properties and fracture toughness of U71Mn and U75V rail steels and their thermite welds. Fracture micromechanisms were analyzed by scanning electron microscopy (SEM) on the fracture surfaces of the tested specimens. The ductility indices (percentage elongation after fracture and percentage reduction of area) and the toughness indices (Charpy impact energy A k and plane-strain fracture toughness K IC) of the two kinds of rail steels and the corresponding thermite welds all decrease as the temperature decreases. The thermite welds are more critical to fracture than the rail steel base metals, as indicated by a higher yield-to-ultimate ratio and a much lower Charpy impact energy. U71Mn rail steel is relatively higher in toughness than U75V, as demonstrated by larger A k and K IC values. Therefore, U71Mn rail steel and the corresponding thermite weld are recommended in railway construction and maintenance in cold regions.

Ductile to Brittle Transition Behaviour of HSLA-65 Steel Welds: Dynamic Tear Testing

DTIC Science & Technology

2011-01-01

soumises aux essais ne s’est avérée apte au service dans des conditions arctiques. DRDC Atlantic TM 2010-220 iii Executive summary...de transition obtenues antérieurement à l’aide de l’essai de choc Charpy. Un objectif secondaire de la présente étude consistait à comparer la méthode...dynamique de résistance à l’arrachement sont beaucoup plus élevées que celles obtenues à l’aide de l’essai de choc Charpy, ce qui appuie l’exigence

46 CFR 54.05-5 - Toughness test specimens.

Code of Federal Regulations, 2010 CFR

2010-10-01

... shown in Figure 4 of the specification. Special attention is drawn to the fact that the Charpy Keyhole....090-inch. In preparing weld specimens for dropweight testing, weld reinforcement shall be ground flush...

Mechanical properties and eddy current testing of thermally aged Z3CN20.09M cast duplex stainless steel

NASA Astrophysics Data System (ADS)

Liu, Tonghua; Wang, Wei; Qiang, Wenjiang; Shu, Guogang

2018-04-01

To study the thermal aging embrittlement of Z3CN20.09M duplex stainless steel produced in China, accelerated thermal aging experiments were carried out at 380 °C up to 9000 h. Microhardness measurements, Charpy impact and eddy current tests were performed on aged samples to characterize their thermal aging embrittlement. The results showed that the signal amplitude of eddy current decreased with the increase in aging time. Two quantitative correlations of the eddy current signal amplitude with both the Charpy impact energy, and the Vickers microhardness of the ferrite phase are obtained. The study showed that eddy current testing could be used to non-destructively evaluate the thermal aging embrittlement of cast duplex stainless steels.

Design, Fabrication and Test of Multi-Fiber Laminates

NASA Technical Reports Server (NTRS)

Pike, R. A.; Novak, R. C.

1975-01-01

Unidirectional and angleply multifiber laminates were tested for improved impact strength and other mechanical properties. The effects of several variables on the mechanical properties of epoxy matrix materials were described. These include fiber type (HMS and AS graphites, glass, and Kevlar 49), ratio of primary to hybridizing fiber and hybrid configuration. It is demonstrated that AS graphite/S glass in an intraply configuration results in the best combination of static and Charpy impact properties as well as superior ballistic impact resistance. Pendulum impact tests which were conducted on thin specimens are shown to produce different ranking of materials than tests conducted on standard thickness Charpy specimens. It is shown that the thin specimen results are in better agreement with the ballistic impact data. Additional static test data are reported as a function of temperature for the seven best hybrid configurations having epoxy, polyimide (PMR-15) and polyphenylquinoxaline resins as the matrix.

Fracture toughness and Charpy impact properties of several RAFMS before and after irradiation in HFIR

NASA Astrophysics Data System (ADS)

Sokolov, M. A.; Tanigawa, H.; Odette, G. R.; Shiba, K.; Klueh, R. L.

2007-08-01

As part of the development of candidate reduced-activation ferritic steels for fusion applications, several steels, namely F82H, 9Cr-2WVTa steels and F82H weld metal, are being investigated in the joint DOE-JAEA collaboration program. Within this program, three capsules containing a variety of specimen designs were irradiated at two design temperatures in the ORNL High Flux Isotope Reactor (HFIR). Two capsules, RB-11J and RB-12J, were irradiated in the HFIR removable beryllium positions with europium oxide (Eu 2O 3) thermal neutron shields in place. Specimens were irradiated up to 5 dpa. Capsule JP25 was irradiated in the HFIR target position to 20 dpa. The design temperatures were 300 °C and 500 °C. Precracked third-sized V-notch Charpy (3.3 × 3.3 × 25.4 mm) and 0.18 T DC(T) specimens were tested to determine transition and ductile shelf fracture toughness before and after irradiation. The master curve methodology was applied to evaluate the fracture toughness transition temperature, T0. Irradiation induced shifts of T0 and reductions of JQ were compared with Charpy V-notch impact properties. Fracture toughness and Charpy shifts were also compared to hardening results.

The production of calibration specimens for impact testing of subsize Charpy specimens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alexander, D.J.; Corwin, W.R.; Owings, T.D.

1994-09-01

Calibration specimens have been manufactured for checking the performance of a pendulum impact testing machine that has been configured for testing subsize specimens, both half-size (5.0 {times} 5.0 {times} 25.4 mm) and third-size (3.33 {times} 3.33 {times} 25.4 mm). Specimens were fabricated from quenched-and-tempered 4340 steel heat treated to produce different microstructures that would result in either high or low absorbed energy levels on testing. A large group of both half- and third-size specimens were tested at {minus}40{degrees}C. The results of the tests were analyzed for average value and standard deviation, and these values were used to establish calibration limitsmore » for the Charpy impact machine when testing subsize specimens. These average values plus or minus two standard deviations were set as the acceptable limits for the average of five tests for calibration of the impact testing machine.« less

Analysis of impact energy to fracture un-notched charpy specimens made from railroad tank car steel

DOT National Transportation Integrated Search

2007-09-11

This paper describes a nonlinear finite element analysis : (FEA) framework that examines the impact energy to fracture : unnotched Charpy specimens by an oversized, nonstandard : pendulum impactor called the Bulk Fracture Charpy Machine : (BFCM). The...

Investigation of Sub-Sized Charpy Specimens

DTIC Science & Technology

1945-08-06

requested the Physical Metallurgy Section to perform a few experiments with sub-sized Charpy spec- imens, so as to indicate whether they could be used to...SAZ 3130 No. 1033 Since the 1020 bpr stock was 2 inches in diameter, four longitu- dinal Charpy speciniens were machined from the cross section as...ihown in Pig- ure 1. In all cases, regardless of the size of the specimen, the center of the height of the Charpy specimen was 5/8 of an inch

Neural network analysis of Charpy transition temperature of irradiated low-activation martensitic steels

NASA Astrophysics Data System (ADS)

Cottrell, G. A.; Kemp, R.; Bhadeshia, H. K. D. H.; Odette, G. R.; Yamamoto, T.

2007-08-01

We have constructed a Bayesian neural network model that predicts the change, due to neutron irradiation, of the Charpy ductile-brittle transition temperature (ΔDBTT) of low-activation martensitic steels given a set of multi-dimensional published data with doses <100 displacements per atom (dpa). Results show the high significance of irradiation temperature and (dpa) 1/2 in determining ΔDBTT. Sparse data regions were identified by the size of the modelling uncertainties, indicating areas where further experimental data are needed. The method has promise for selecting and ranking experiments on future irradiation materials test facilities.

Procedure improves line pipe Charpy test interpretation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosenfeld, M.J.

1997-04-14

The Charpy V-notch (CVN) impact test is a method of characterizing a line-pipe material`s notch toughness and resistance to fracture growth. Although CVN testing of line pipe material is routine, test results are sometimes misinterpreted because of specimen size and load rate on actual toughness transition behavior. These effects are readily accounted for by a simple mathematical procedure, offered here, which enables extrapolation of the full-scale transition curve from as little as a single subsize specimen test. This procedure is useful when the toughness transition curve is incomplete or nonexistent. Toughness data may be incomplete because the API 5L toughnessmore » test establishes minimum performance at a single temperature, which does not reveal the full transition curve. Toughness data may be nonexistent because the first requirements for toughness testing of line pipe appeared in the 16th Edition of API 5LX in 1969, and those requirements remain at the option of the purchaser today.« less

46 CFR 154.605 - Toughness test.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Toughness test. 154.605 Section 154.605 Shipping COAST....605 Toughness test. (a) Each toughness test under §§ 154.610 through 154.625 must meet Subpart 54.05 of this chapter. (b) If subsize test specimens are used for the Charpy V-notch toughness test, the...

49 CFR 178.337-2 - Material.

Code of Federal Regulations, 2014 CFR

2014-10-01

...-pounds in the longitudinal direction at −30 °F., Charpy V-Notch and 15 foot-pounds in the transverse direction at −30 °F., Charpy V-Notch. The required values for subsize specimens must be reduced in direct... shall record the heat, and slab numbers, and the certified Charpy impact values, where required, of each...

49 CFR 178.337-2 - Material.

Code of Federal Regulations, 2011 CFR

2011-10-01

...-pounds in the longitudinal direction at −30 °F., Charpy V-Notch and 15 foot-pounds in the transverse direction at −30 °F., Charpy V-Notch. The required values for subsize specimens must be reduced in direct... shall record the heat, and slab numbers, and the certified Charpy impact values, where required, of each...

49 CFR 178.337-2 - Material.

Code of Federal Regulations, 2012 CFR

2012-10-01

...-pounds in the longitudinal direction at −30 °F., Charpy V-Notch and 15 foot-pounds in the transverse direction at −30 °F., Charpy V-Notch. The required values for subsize specimens must be reduced in direct... shall record the heat, and slab numbers, and the certified Charpy impact values, where required, of each...

49 CFR 178.337-2 - Material.

Code of Federal Regulations, 2013 CFR

2013-10-01

...-pounds in the longitudinal direction at −30 °F., Charpy V-Notch and 15 foot-pounds in the transverse direction at −30 °F., Charpy V-Notch. The required values for subsize specimens must be reduced in direct... shall record the heat, and slab numbers, and the certified Charpy impact values, where required, of each...

Metal-Matrix Composites: Status and Prospects

DTIC Science & Technology

1974-12-01

increased to meet or exceed even the most severe engine requirements. This optimism is based largely on an order-of-magnitude improvement in Charpy test...relationships between coupon tests, subsize structural components, and structural component evaluations 4. The development of su-table design

Effect of fiber diameter and matrix alloys on impact-resistant boron/aluminum composites

NASA Technical Reports Server (NTRS)

Mcdanels, D. L.; Signorelli, R. A.

1976-01-01

Efforts to improve the impact resistance of B/Al are reviewed and analyzed. Nonstandard thin-sheet charpy and Izod impact tests and standard full-size Charpy impact tests were conducted on composites containing unidirectional 0.10mm, 0.14mm, and 0.20mm diameter boron fibers in 1100, 2024, 5052, and 6061 Al matrices. Impact failure modes of B/Al are proposed in an attempt to describe the mechanisms involved and to provide insight for maximizing impact resistance. The impact strength of B/Al was significantly increased by proper selection of materials and processing. The use of a ductile matrix and large diameter boron fibers gave the highest impact strengths. This combination resulted in improved energy absorption through matrix shear deformation and multiple fiber breakage.

Neutron Irradiation Effects on the Mechanical Properties of HY-80 Steel

DTIC Science & Technology

1986-12-01

compared to trends established by NRL and by Carpenter (Ref. (18]) ....................... 57 Figure 27 Charpy V-notch ductility characteristics of...59 Figure 28 Charpy V-notch ductility characteristics of three steels of different strength levels after simultaneous irradiations at 550-F...as determined by Charpy V (30 Ft.Lb.) (Ref. [14]) ....... 49 Table 4 Tensile properties of HY-80 steel (Ref. [3,17) .............................. 51

Master Curve and Conventional Fracture Toughness of Modified 9Cr-1Mo Steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ji-Hyun, Yoon; Sung-Ho, Kim; Bong-Sang, Lee

2006-07-01

Modified 9Cr-1Mo steel is a primary candidate material for reactor pressure vessel of Very High Temperature Gas-Cooled Reactor (VHTR) in Korean Nuclear Hydrogen Development and Demonstration (NHDD) program. In this study, T0 reference temperature, J-R fracture resistance and Charpy impact properties were evaluated for commercial Grade 91 steel as preliminary tests for the selection of the RPV material for VHTR. The fracture toughness of the modified 9Cr-1Mo steel was compared with those of SA508-Gr.3. The objective of this study was to obtain pre-irradiation fracture toughness properties of modified 9Cr-1Mo steel as reference data for the radiation effects investigation. The resultsmore » are as follows. Charpy impact properties of the modified 9Cr-1Mo steel were similar to those of SA508-Gr.3. T0 reference temperatures were measured as -67.7 deg C and -72.4 deg C from the tests with standard PCVN (pre-cracked Charpy V-notch) and half sized PCVN specimens respectively, which were similar to results for SA508-Gr.3. The K{sub Jc} values of modified 9Cr-1Mo with test temperatures are successfully expressed with the Master Curve. The J-R fracture resistance of modified 9Cr-1Mo steel at room temperature was almost the same as that of SA508-Gr.3. On the other hand it was a little bit higher at an elevated temperature. (authors)« less

Fracture toughness and the master curve for modified 9Cr-1Mo steel

NASA Astrophysics Data System (ADS)

Yoon, Ji-Hyun; Yoon, Eui-Pak

2006-12-01

Modified 9Cr-1Mo steel is a primary candidate material for the reactor pressure vessel of a Very High Temperature Gas-Cooled Reactor (VHTR) in the Korean Nuclear Hydrogen Development and Demonstration (NHDD) program. In this study, the T0 reference temperature, J-R fracture resistance and Charpy impact properties were evaluated for commercial Grade 91 steel as part of the preliminary testing for a selection of the RPV material for the VHTR. The fracture toughness of the modified 9Cr-1Mo steel was compared with that of SA508-Gr.3. The objective of this study was to obtain the pre-irradiation fracture toughness properties of the modified 9Cr-1Mo steel as reference data for an investigation of radiation effects. Charpy impact properties of the modified 9Cr-1Mo steel were similar to those of SA508-Gr.3. T0 reference temperatures were measured as -67.7 and -72.4°C from the tests with standard PCVN (pre-cracked Charpy V-notch) and half-sized PCVN specimens respectively, which were similar to the results for SA508-Gr.3. The KJc values of the modified 9Cr-1Mo steel with the test temperatures are successfully expressed by the Master Curve. The J-R fracture resistance of the modified 9Cr-1Mo steel at room temperature was nearly identical to that of SA508-Gr.3; in contrast, it was slightly higher at an elevated temperature.

A Physical Metallurgical Basis for Heat-Affected Zone and Base-Plate Properties of a Microalloyed HSLA Steel.

DTIC Science & Technology

1986-12-01

system.(a) Schematic diagram.(b) Equipment ...... 64 x * T-3136 FIGURE PAGE 13 Details of subsize charpy specimen and Gleeble HAZ microstructural...simulation specimen ......................................... 71 14 Macrograph profile of subsize charpy specimen illustrating notch location. (a) Specimen...shelf impact energy for subsize charpy specimens as a function of distance from the fusion zone boundary for various nominal heat inputs of both

Northwest Manufacturing Initiative

DTIC Science & Technology

2013-03-26

Testing of Metallic Materials] specifications. For high temperature tests, a heated water bath was use while for low temperature testing down to...Weld metal and heat affected zones were evaluated using Charpy and E399 fracture toughness methods. The influence of temperature , loading rate, CVN...determine the influence of fracture test methods and welding procedures on toughness. Room temperature E399 tests, (CTS) were carried out under

46 CFR 54.05-5 - Toughness test specimens.

Code of Federal Regulations, 2011 CFR

2011-10-01

... V-notch tests shall be conducted in accordance with ASTM Specification E 23 (incorporated by... for that thickness shall be cut centered at the material's mid-thickness. For materials thicker than 1/2-inch, full size Charpy specimens shall be cut centered at a location as near as practicable to a...

Development of Low-Carbon, Copper-Strengthened HSLA Steel Plate for Naval Ship Construction

DTIC Science & Technology

1990-06-01

steel plate microstructures, 2% nital etch . ...................................................... 13 2. Charpy V-notch impact energy transition for...met a minimum yield strength requirement of 80 ksi yield strength through 3/4 inch gage, had high Charpy V-notch impact energy at low tempera- tures...tempered HSLA line-pipe steels, which typically could not meet the minimum Charpy V-notch impact toughness requirement of 35 ft-lb at -1 200 F. In 1984

Over-Aging Effect on Fracture Toughness of Beryllium Copper Alloy C17200

NASA Astrophysics Data System (ADS)

Jen, Kei-Peng; Xu, Liqun; Hylinski, Steven; Gildersleeve, Nate

2008-10-01

This study experimentally increased the fracture toughness of Beryllium Copper (CuBe) UNS C17200 alloy using three different age hardening processes. At the same time, the micro- and macro-fracture behavior of this alloy were comprehensively studied. ASTM E399 fracture toughness, tensile, and Charpy impact tests were conducted for all three heat-treated rods. The fracture surfaces were examined under both an optical microscope and a scanning electron microscope to investigate the failure mechanisms. Multiple test orientations were considered to explore isotropy. Increasing the temperature and duration at which age hardening was performed increased fracture toughness while decreasing ultimate tensile strength. The maximum fracture toughness was reached on the most overaged specimen, while retaining a serviceable tensile strength. The specimen test data allowed a relationship to be established among Charpy impact toughness, fracture toughness, and yield strength. Analysis of fracture behavior revealed an interesting relationship between fracture toughness and pre-cracking fatigue propagation rate.

Mechanical Properties and Seawater Behavior of Nitronic 50 (22Cr-13Ni- 5Mn) Plate

DTIC Science & Technology

1976-01-01

Bal - balance misc - miscellaneous cfh - cubic feet per hour mpy - mils per year c/m - cycles per minute my - millivolts CVN - Charpy V-notch No...High-Cycle Fatigue Specimens F_gure 6 - Drawings; Low-Cycle Fatigue Specimens Figure 7 - Curve; Charpy V-Notch Impact Toughness Versus Temperature...for Nitronic 50 Base Plate FiGure 8 - Curve; Charpy V-Notch Toughness Versus Tempera- ture for Nitrcnic 50 Weldments Figure 9 - Photographs; Fracture

An improved correlation procedure for subsize and full-size Charpy impact specimen data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sokolov, M.A.; Alexander, D.J.

1997-03-01

The possibility of using subsize specimens to monitor the properties of reactor pressure vessel steels is receiving increasing attention for light-water reactor plant life extension. This potential results from the possibility of cutting samples of small volume form the internal surface of the pressure vessel for determination of the actual properties of the operating pressure vessel. In addition, plant life extension will require supplemental data that cannot be provided by existing surveillance programs. Testing of subsize specimens manufactured from broken halves of previously tested surveillance Charpy specimens offers an attractive means of extending existing surveillance programs. Using subsize Charpy V-notch-typemore » specimens requires the establishment of a specimen geometry that is adequate to obtain a ductile-to-brittle transition curve similar to that obtained from full-size specimens, and the development of correlations for transition temperature and upper-shelf energy (USE) level between subsize and full-size specimens. Five different geometries of subsize specimens were selected for testing and evaluation. The specimens were made from several types of pressure vessel steels with a wide range of yield strengths, transition temperatures, and USEs. The effects of specimen dimensions, including notch depth, angle, and radius, have been studied. The correlations of transition temperatures determined from different types of subsize specimens and the full-size specimens are presented. A new procedure for transforming data from subsize specimens is developed. The transformed data are in good agreement with data from full-size specimens for materials that have USE levels less than 200 J.« less

Mechanical Properties and Fracture Toughness Assessment of M795 and M549 155 mm Artillery Projectile Bodies Manufactured from HF-1 Steel

DTIC Science & Technology

1986-07-01

body, fracture toughness values determined using A(T) specimens agreed well with values reported elsewhere determined using Charpy - sized three point...values reported elsewhere determined using Charpy - sized three point bend (3PB) specimens. For the M795 body, however, good agreement was obtained for...the projectile wall, viz. the transverse and the longitudinal directions. Arc- tension, A(T), and pre-cracked Charpy three point bend, 3PB, specimens

Evaluation of AISI 4140 Steel Repair Without Post-Weld Heat Treatment

NASA Astrophysics Data System (ADS)

Silva, Cleiton C.; de Albuquerque, Victor H. C.; Moura, Cícero R. O.; Aguiar, Willys M.; Farias, Jesualdo P.

2009-04-01

The present work evaluates the two-layer technique on the heat affected zone (HAZ) of AISI 4140 steel welded with different heat input levels between the first and second layer. The weld heat input levels selected by the Higuchi test were 5/5, 5/10, and 15/5 kJ/cm. The evaluation of the refining and/or tempering of the coarsened grain HAZ of the first layer was carried out using metallographic tests, microhardness measurements, and the Charpy-V impact test. The tempering of the first layer was only reached when the weld heat input ratio was 5/5 kJ/cm. The results of the Charpy-V impact test showed that the two-layer technique was efficient, from the point of view of toughness, since the toughness values reached were greater than the base metal for all weld heat input ratios applied. The results obtained indicate that the best performance of the two-layer deposition technique was for the weld heat input ratio 5/5 kJ/cm employing low heat input.

Analysis of the irradiation data for A302B and A533B correlation monitor materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, J.A.

1996-04-01

The results of Charpy V-notch impact tests for A302B and A533B-1 Correlation Monitor Materials (CMM) listed in the surveillance power reactor data base (PR-EDB) and material test reactor data base (TR-EDB) are analyzed. The shift of the transition temperature at 30 ft-lb (T{sub 30}) is considered as the primary measure of radiation embrittlement in this report. The hyperbolic tangent fitting model and uncertainty of the fitting parameters for Charpy impact tests are presented in this report. For the surveillance CMM data, the transition temperature shifts at 30 ft-lb ({Delta}T{sub 30}) generally follow the predictions provided by Revision 2 of Regulatorymore » Guide 1.99 (R.G. 1.99). Difference in capsule temperatures is a likely explanation for large deviations from R.G. 1.99 predictions. Deviations from the R.G. 1.99 predictions are correlated to similar deviations for the accompanying materials in the same capsules, but large random fluctuations prevent precise quantitative determination. Significant scatter is noted in the surveillance data, some of which may be attributed to variations from one specimen set to another, or inherent in Charpy V-notch testing. The major contributions to the uncertainty of the R.G. 1.99 prediction model, and the overall data scatter are from mechanical test results, chemical analysis, irradiation environments, fluence evaluation, and inhomogeneous material properties. Thus in order to improve the prediction model, control of the above-mentioned error sources needs to be improved. In general the embrittlement behavior of both the A302B and A533B-1 plate materials is similar. There is evidence for a fluence-rate effect in the CMM data irradiated in test reactors; thus its implication on power reactor surveillance programs deserves special attention.« less

Comparison of irradiation-induced shifts of K{sub Jc} and Charpy impact toughness for reactor pressure vessel steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sokolov, M.A.; Nanstad, R.K.

1999-10-01

The current provisions for determination of the upward temperature shift of the lower-bound static fracture toughness curve due to irradiation of reactor pressure vessel steels are based on the assumption that they are the same as the Charpy 41-J shifts as a consequence of irradiation. The objective of this paper is to evaluate this assumption relative to data reported in open publications. Depending on the specific source, different sizes of fracture toughness specimens, procedures of the K{sub Jc} determination, and fitting functions were used. It was anticipated that the scatter might be reduced by using a consistent approach to analyzemore » the published data. A method employing Weibull statistics is applied to analyze original fracture toughness data of unirradiated and irradiated pressure vessel steels. Application of the master curve concept is used to determine shifts of fracture toughness transition curves. A hyperbolic tangent function is used to fit charpy absorbed energy data. The fracture toughness shifts are compared to Charpy impact shifts evaluated with various criteria. Linear regression analysis showed that for weld metals, on average, the fracture toughness shift is the same as the Charpy 41-J temperature shift, while for base metals, on average, the fracture toughness shift at 41 J is 16% greater than the shift of the Charpy 41-J transition temperature, with both correlations having relatively large 95% confidence intervals.« less

Ductile Fracture Behaviour of Hot Isostatically Pressed Inconel 690 Superalloy

NASA Astrophysics Data System (ADS)

Cooper, A. J.; Brayshaw, W. J.; Sherry, A. H.

2018-04-01

Herein we assess the differences in Charpy impact behavior between Hot Isostatically Pressed and forged Inconel 690 alloy over the temperature range of 300 °C to - 196 °C. The impact toughness of forged 690 exhibited a relatively small temperature dependence, with a maximum difference of ca. 40 J measured between 300 °C and - 196 °C, whereas the HIP'd alloy exhibited a difference of approximately double that of the forged alloy over the same temperature range. We have conducted Charpy impact testing, tensile testing, and metallographic analyses on the as-received materials as well as fractography of the failed Charpy specimens in order to understand the mechanisms that cause the observed differences in material fracture properties. The work supports a recent series of studies which assess differences in fundamental fracture behavior between Hot Isostatically Pressed and forged austenitic stainless steel materials of equivalent grades, and the results obtained in this study are compared to those of the previous stainless steel investigations to paint a more general picture of the comparisons between HIP vs forged material fracture behavior. Inconel 690 was selected in this study since previous studies were unable to completely omit the effects of strain-induced martensitic transformation at the tip of the Chary V-notch from the fracture mechanism; Inconel 690 is unable to undergo strain-induced martensitic transformation due to the alloy's high nickel content, thereby providing a sister study with the omission of any martensitic transformation effects on ductile fracture behavior.

Microstructure and Charpy impact properties of 12 14Cr oxide dispersion-strengthened ferritic steels

NASA Astrophysics Data System (ADS)

Oksiuta, Z.; Baluc, N.

2008-02-01

This paper describes the microstructure and Charpy impact properties of 12-14 Cr ODS ferritic steels fabricated by mechanical alloying of pure Fe, Cr, W, Ti and Y 2O 3 powders in a Retsch ball mill in argon atmosphere, followed by hot isostatic pressing at 1100 °C under 200 MPa for 4 h and heat treatment at 850 °C for 1 h. Weak Charpy impact properties were obtained in the case of both types of as-hipped materials. In the case of 14Cr materials, the weak Charpy properties appeared related to a bimodal grain size distribution and a heterogeneous dislocation density between the coarse and fine grains. No changes in microstructure were evidenced after heat treatment at 850 °C. Significant improvement in the transition temperature and upper shelf energy of 12Cr materials was obtained by heat treatment at 850 °C for 1 h, which was attributed to the formation of smaller grains, homogenous in size and containing fewer dislocations, with respect to the as-hipped microstructure. This modified microstructure results in a good compromise between strength and Charpy impact properties.

Impact fracture toughness evaluation for high-density polyethylene materials

NASA Astrophysics Data System (ADS)

Cherief, M. N. D.; Elmeguenni, M.; Benguediab, M.

2017-03-01

The impact fracture behavior of a high-density polyethylene (HDPE) material is investigated experimentally and theoretically. Single-edge notched bending (SENB) specimens are tested in experiments with three-point bending and in the Charpy impact tests. An energy model is proposed for evaluating the HDPE impact toughness, which provides a description of both brittle and ductile fracture.

Subsize specimen testing of nuclear reactor pressure vessel material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, A.S.; Rosinski, S.T.; Cannon, N.S.

1991-01-01

A new methodology is proposed to correlate the upper shelf energy (USE) of full size and subsize Charpy specimens of a nuclear reactor pressure vessel plate material, A533B. The methodology appears to be more satisfactory than the methodologies proposed earlier. USE of a notched-only specimen is partitioned into macro-crack initiation and crack propagation energies. USE of a notched and precracked specimen provides the crack propagation energy. [Delta]USE, the difference between the USE's of notched-only and precracked specimens, is an estimate of the crack initiation energy. [Delta]USE was normalized by a factor involving the dimensions of the Charpy specimen and themore » stress concentration factor at the notch root. The normalized values of the [Delta]USE were found to be invariant with specimen size.« less

Fracture Toughness of Z3CN20.09M Cast Stainless Steel with Long-Term Thermal Aging

NASA Astrophysics Data System (ADS)

Yu, Weiwei; Yu, Dunji; Gao, Hongbo; Xue, Fei; Chen, Xu

2017-09-01

Accelerated thermal aging tests were performed at 400 °C for nearly 18,000 h on Z3CN20.09M cast stainless steel which was used for primary coolant pipes of nuclear power plants. A series of Charpy impact tests were conducted on Z3CN20.09M after different long-term thermal aging time. The test results indicated that the Charpy impact energy of Z3CN20.09M cast stainless steel decreased rapidly at an early stage and then almost saturated after thermal aging of 10,000 h. Furthermore, J-resistance curves were measured for CT specimens of longitudinal and circumferential pipe orientations. It showed that there was no obvious difference in the fracture characteristics of Z3CN20.09M in different sampling directions. In addition, the observed stretch zone width (SZW) revealed that the value of initiation fracture toughness J SZW was significantly lower than that of fracture toughness J IC, indicating a low actual crack initiation energy due to long-term thermal aging.

Correlation of rolling condition, microstructure, and low-temperature toughness of X70 pipeline steels

NASA Astrophysics Data System (ADS)

Hwang, Byoungchul; Kim, Young Min; Lee, Sunghak; Kim, Nack J.; Yoo, Jang Yong

2005-07-01

Correlation of rolling conditions, microstructure, and low-temperature toughness of high-toughness X70 pipeline steels was investigated in this study. Twelve kinds of steel specimens were fabricated by vacuum-induction melting and hot rolling, and their microstructures were varied by rolling conditions. Charpy V-notch (CVN) impact test and drop-weight tear test (DWTT) were conducted on the rolled steel specimens in order to analyze low-temperature fracture properties. Charpy impact test results indicated that the energy transition temperature (ETT) was below -100 °C when the finish cooling temperature range was 350 °C to 500 °C, showing excellent low-temperature toughness. The ETT increased because of the formation of bainitic ferrite and martensite at low finish cooling temperatures and because of the increase in effective grain size due to the formation of coarse ferrites at high finish cooling temperatures. Most of the specimens also showed excellent DWTT properties as the percent shear area well exceeded 85 pct, irrespective of finish rolling temperatures or finish cooling temperatures, although a large amount of inverse fracture occurred at some finish cooling temperatures.

Subtask 12B1: Welding development for V-Cr-Ti alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

King, J.F.; Goodwin, G.M.; Grossbeck, M.L.

1995-03-01

Development of the metallurgical and technological basis for the welding of thick sections of V-Cr-Ti alloys. The weldability and weldment properties of the V-5Cr-5Ti alloy have been evaluated. Results for the Sigmajig test of the vanadium alloy were similar to the cracking resistance of stainless steels, and indicates hot-cracking is unlikely to be a problem. Subsize Charpy test results for GTA weld metal in the as-welded condition have shown a significant reduction in toughness compared to the base metal. The weld metal toughness properties were restored to approximately that of the base metal after exposure to a PWHT 950{degrees}C. Themore » subsize Charpy toughness results for the EB weld metal from this same heat of vanadium alloy has shown significant improvement in properties compared to the GTA weld metal and the base metal. Further testing and analysis will be conducted to more fully characterize the properties of weld metal for each welding process and develop a basic understanding of the cause of the toughness decrease in the GTA welds. 5 figs., 1 tab.« less

FE Modelling of Tensile and Impact Behaviours of Squeeze Cast Magnesium Alloy AM60

NASA Astrophysics Data System (ADS)

DiCecco, Sante; Altenhof, William; Hu, Henry

In response to the need for reduced global emissions, the transportation industry has been steadily increasing the magnesium content in vehicles. This trend has resulted in experimental documentation of numerous alloy and casting combinations, while comparatively little work has been done regarding the development of numerical material models for vehicle crashworthiness simulations. In this study, material mechanical behaviour was implemented into an existing material model within the nonlinear FEA code LS-DYNA to emulate the mechanical behaviour of squeeze cast magnesium alloy AM60 with a relatively thick section of 10 mm thickness. Model validation was achieved by comparing the numerical and experimental results of a tensile test and Charpy impact event. Validation found an average absolute error of 5.44% between numerical and experimental tensile test data, whereas a relatively large discrepancy was found during Charpy evaluation. This discrepancy has been attributed to the presence of microstructure inhomogeneity in the squeeze cast magnesium alloy AM60.

Effect of Heat Treatment Process on Mechanical Properties and Microstructure of a 9% Ni Steel for Large LNG Storage Tanks

NASA Astrophysics Data System (ADS)

Zhang, J. M.; Li, H.; Yang, F.; Chi, Q.; Ji, L. K.; Feng, Y. R.

2013-12-01

In this paper, two different heat treatment processes of a 9% Ni steel for large liquefied natural gas storage tanks were performed in an industrial heating furnace. The former was a special heat treatment process consisting of quenching and intercritical quenching and tempering (Q-IQ-T). The latter was a heat treatment process only consisting of quenching and tempering. Mechanical properties were measured by tensile testing and charpy impact testing, and the microstructure was analyzed by optical microscopy, transmission electron microscopy, and x-ray diffraction. The results showed that outstanding mechanical properties were obtained from the Q-IQ-T process in comparison with the Q-T process, and a cryogenic toughness with charpy impact energy value of 201 J was achieved at 77 K. Microstructure analysis revealed that samples of the Q-IQ-T process had about 9.8% of austenite in needle-like martensite, while samples of the Q-T process only had about 0.9% of austenite retained in tempered martensite.

The Effect of Filler Wire and Flux Compositions on the Microstructure and Properties of Microalloyed Steel Weld Metal.

DTIC Science & Technology

1984-08-01

obtained from subsize (5.0 x 10.0 x 55.0 mm) Charpy V-Notch specimens, subsize (7.6 x 7.6 x 55.0 mm)-Izod specimens, and subsize (5.0 x 9.5 x 101.6 mm...47 15. Schematic of a submerged arc weld showing the dimensions and orientation of subsize Charpy V-Notch specimens... Subsize (5.0 x 10.0 x 55.0 mm) Charpy impact values P of two submerged arc welds performed on quenched and tempered C-Mn-Mo-Nb plate as a function of

Comparison between instrumented precracked Charpy and compact specimen tests of carbon steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nanstad, R.K.

1980-01-01

The General Atomic Company High Temperature Gas-Cooled Reactor (HTGR) is housed within a prestressed concrete reactor vessel (PCRV). Various carbon steel structural members serve as closures at penetrations in the vessel. A program of testing and evaluation is underway to determine the need for reference fracture toughness (K/sub IR/) and indexing procedures for these materials as described in Appendix G to Section III, ASME Code for light water reactor steels. The materials of interest are carbon steel forgings (SA508, Class 1) and plates (SA537, Classes 1 and 2) as well as weldments of these steels. The fracture toughness behavior ismore » characterized with instrumented precracked Charpy V-votch specimens (PCVN) - slow-bend and dynamic - and compact specimens (10-mm and 25-mm thicknesses) using both linear elastic (ASTM E399) and elastic-plastic (equivalent Energy and J-Integral) analytical procedures. For the dynamic PCVN tests, force-time traces are analyzed according to the procedures of the Pressure Vessel Research Council (PVRC)/Metal Properties Council (MPC). Testing and analytical procedures are discussed and PCVN results are compared to those obtained with compact specimens.« less

EXPERIMENTAL EVALUATION OF DEFORMATION AND CONSTRAINT CHARACTERISTICS IN PRECRACKED CHARPY AND OTHER THREE-POINT BEND SPECIMENS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nanstad, Randy K; Sokolov, Mikhail A; Merkle, John Graham

2007-01-01

To enable determination of the fracture toughness reference temperature, T0, with reactor pressure vessel surveillance specimens, the precracked Charpy (PCVN) three-point bend, SE(B), specimen is of interest. Compared with the 25-mm (1 in.) thick compact, 1TC(T), specimen, tests with the PCVN specimen (10x10x55 mm) have resulted in T0 temperatures as much as 40 XC lower (a so-called specimen bias effect). The Heavy-Section Steel Irradiation (HSSI) Program at Oak Ridge National Laboratory developed a two-part project to evaluate the C(T) versus PCVN differences, (1) calibration experiments concentrating on test practices, and (2) a matrix of transition range tests with various specimenmore » geometries and sizes, including 1T SE(B) and 1TC(T). The test material selected was a plate of A533 grade B class 1 steel. The calibration experiments included assessment of the computational validity of J-integral determinations, while the constraint characteristics of various specimen types and sizes were evaluated using key curves and notch strength determinations. The results indicate that J-integral solutions for the small PCVN specimen are comparable in terms of J-integral validity with 1T bend specimens. Regarding constraint evaluations, Phase I deformation is defined where plastic deformation is confined to crack tip plastic zone development, whereas Phase II deformation is defined where plastic hinging deformation develops. In Phase II deformation, the 0.5T SE(B) B B specimen (slightly larger than the PCVN specimen) consistently showed the highest constraint of all SE(B) specimens evaluated for constraint comparisons. The PCVN specimen begins the Phase II type of deformation at relatively low KR levels, with the result that KJc values above about 70 MPa m from precracked Charpy specimens are under extensive plastic hinging deformation.« less

Charpy Impact Energy and Microindentation Hardness of 60-NITINOL

NASA Technical Reports Server (NTRS)

Stanford, Malcolm K.

2012-01-01

60-NITINOL (60 wt.% Ni 40 wt.% Ti) is being studied as a material for advanced aerospace components. The Charpy impact energy and microindentation hardness has been studied for this material, fabricated by vacuum induction skull melting (casting) and by hot isostatic pressing. Test specimens were prepared in various hardened and annealed heat treatment conditions. The average impact energy ranged from 0.33 to 0.49J for the hardened specimens while the annealed specimens had impact energies ranging from 0.89 to 1.18J. The average hardness values of the hardened specimens ranged from 590 to 676 HV while that of the annealed specimens ranged from 298 to 366 HV, suggesting an inverse relationship between impact energy and hardness. These results are expected to provide guidance in the selection of heat treatment processes for the design of mechanical components.

Subsize specimen testing of nuclear reactor pressure vessel material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, A.S.; Rosinski, S.T.; Cannon, N.S.

1991-12-31

A new methodology is proposed to correlate the upper shelf energy (USE) of full size and subsize Charpy specimens of a nuclear reactor pressure vessel plate material, A533B. The methodology appears to be more satisfactory than the methodologies proposed earlier. USE of a notched-only specimen is partitioned into macro-crack initiation and crack propagation energies. USE of a notched and precracked specimen provides the crack propagation energy. {Delta}USE, the difference between the USE`s of notched-only and precracked specimens, is an estimate of the crack initiation energy. {Delta}USE was normalized by a factor involving the dimensions of the Charpy specimen and themore » stress concentration factor at the notch root. The normalized values of the {Delta}USE were found to be invariant with specimen size.« less

Microstructures and Mechanical Properties of Friction Tapered Stud Overlap Welding for X65 Pipeline Steel Under Wet Conditions

NASA Astrophysics Data System (ADS)

Xu, Y. C.; Jing, H. Y.; Han, Y. D.; Xu, L. Y.

2017-08-01

This paper exhibits a novel in situ remediation technique named friction tapered stud overlap welding (FTSOW) to repair a through crack in structures and components in extremely harsh environments. Furthermore, this paper presents variations in process data, including rotational speed, stud displacement, welding force, and torque for a typical FTSOW weld. In the present study, the effects of welding parameters on the microstructures and mechanical properties of the welding joints were investigated. Inapposite welding parameters consisted of low rotational speeds and welding forces, and when utilized, they increased the occurrence of a lack of bonding and unfilled defects within the weld. The microstructures with a welding zone and heat-affected zone mainly consisted of upper bainite. The hardness value was highest in the welding zone and lowest in the base material. During the pull-out tests, all the welds failed in the stud. Moreover, the defect-free welds broke at the interface of the lap plate and substrate during the cruciform uniaxial tensile test. The best tensile test results at different depths and shear tests were 721.6 MPa and 581.9 MPa, respectively. The favorable Charpy impact-absorbed energy was 68.64 J at 0 °C. The Charpy impact tests revealed a brittle fracture characteristic with a large area of cleavage.

46 CFR 54.05-20 - Impact test properties for service of 0 °F and below.

Code of Federal Regulations, 2014 CFR

2014-10-01

.... 54.05-20 Section 54.05-20 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE.... (a) Test energy. The impact energies of each set of transverse Charpy specimens may not be less than... reference, see § 54.01-1) nickel steels must exhibit energies not less than the values shown in § 54.05-20...

46 CFR 54.05-20 - Impact test properties for service of 0 °F and below.

Code of Federal Regulations, 2010 CFR

2010-10-01

.... 54.05-20 Section 54.05-20 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE.... (a) Test energy. The impact energies of each set of transverse Charpy specimens may not be less than... reference, see § 54.01-1) nickel steels must exhibit energies not less than the values shown in § 54.05-20...

The Influence of Notch Root Radius and Austenitizing Temperature on Fracture Appearance of As-Quenched Charpy-V Type AISI4340 Steel Specimens

NASA Astrophysics Data System (ADS)

Firrao, D.; Begley, J. A.; Silva, G.; Roberti, R.; de Benedetti, B.

1982-06-01

Charpy-V type samples either step-quenched from 1200 °C or directly quenched from the usual 870 °C temperature, fractured by a slow bend test procedure, have been fractographically examined. Their notch root radius, ρ, ranged from almost zero (fatigue precrack) up to 2.0 mm. The fracture initiation process at the notch differs according to root radius and heat treatment. Conventionally austenitized samples with ρ values larger than 0.07 mm approximately ( ρ eff) always display a continuous shear lip formation along the notch surface, whereas specimens with smaller notches do not exhibit a similar feature. Moreover, shear lip width in specimens with ρ > ρ eff is linearly related to the applied J-integral at fracture. In high temperature austenitized samples similar shear lips are almost nonexistent. The above findings, as well as overall fractographic features, are combined to explain why blunt notch AISI 4340 steel specimens display a better fracture resistance if they are conventionally heat treated, whereas fatigue precracked samples show a superior fracture toughness when they are step-quenched from 1200 °C. Variations of fracture morphologies with the notch root radius and heat treating procedures are associated with a shift toward higher Charpy transition temperatures under the combined influence of decreasing root radii and coarsening of the prior austenitic grain size at high austenitizing temperatures.

Effect of Bimodal Grain Size Distribution on Scatter in Toughness

NASA Astrophysics Data System (ADS)

Chakrabarti, Debalay; Strangwood, Martin; Davis, Claire

2009-04-01

Blunt-notch tests were performed at -160 °C to investigate the effect of a bimodal ferrite grain size distribution in steel on cleavage fracture toughness, by comparing local fracture stress values for heat-treated microstructures with uniformly fine, uniformly coarse, and bimodal grain structures. An analysis of fracture stress values indicates that bimodality can have a significant effect on toughness by generating high scatter in the fracture test results. Local cleavage fracture values were related to grain size distributions and it was shown that the largest grains in the microstructure, with an area percent greater than approximately 4 pct, gave rise to cleavage initiation. In the case of the bimodal grain size distribution, the large grains from both the “fine grain” and “coarse grain” population initiate cleavage; this spread in grain size values resulted in higher scatter in the fracture stress than in the unimodal distributions. The notch-bend test results have been used to explain the difference in scatter in the Charpy energies for the unimodal and bimodal ferrite grain size distributions of thermomechanically controlled rolled (TMCR) steel, in which the bimodal distribution showed higher scatter in the Charpy impact transition (IT) region.

Radiation and annealing response of WWER 440 beltline welding seams

NASA Astrophysics Data System (ADS)

Viehrig, Hans-Werner; Houska, Mario; Altstadt, Eberhard

2015-01-01

The focus of this paper is on the irradiation response and the effect of thermal annealing in weld materials extracted from decommissioned WWER 440 reactor pressure vessels of the nuclear power plant Greifswald. The characterisation is based on the measurement of the hardness, the yield stress, the Master Curve reference temperature, T0, and the Charpy-V transition temperature through the thickness of multi-layer beltline welding seams in the irradiated and the thermally annealed condition. Additionally, the weld bead structure was characterised by light microscopic studies. We observed a large variation in the through thickness T0 values in the irradiated as well as in thermally annealed condition. The T0 values measured with the T-S-oriented Charpy size SE(B) specimens cut from different thickness locations of the multilayer welding seams strongly depend on the intrinsic weld bead structure along the crack tip. The Master Curve, T0, and Charpy-V, TT47J, based ductile-to-brittle transition temperature progressions through the thickness of the multi-layer welding seam do not correspond to the forecast according to the Russian code. In general, the fracture toughness values at cleavage failure, KJc, measured on SE(B) specimens from the irradiated and large-scale thermally annealed beltline welding seams follow the Master Curve description, but more than the expected number lie outside the curves for 2% and 98% fracture probability. In this case the test standard ASTM E1921 indicates the investigated multi-layer weld metal as not uniform. The multi modal Master Curve based approach describes the temperature dependence of the specimen size adjusted KJc-1T values well. Thermal annealing at 475 °C for 152 h results in the expected decrease of the hardness and tensile strength and the shift of Master Curve and Charpy-V based ductile-to-brittle transition temperatures to lower values.

Microstructure characterization and charpy toughness of P91 weldment for as-welded, post-weld heat treatment and normalizing & tempering heat treatment

NASA Astrophysics Data System (ADS)

Pandey, Chandan; Mahapatra, M. M.; Kumar, Pradeep; Giri, A.

2017-09-01

The effect of weld groove design and heat treatment on microstructure evolution and Charpy toughness of P91 pipe weldments was studied. The P91 pipe weldments were subjected to subcritical post weld heat treatment (760 °C-2 h) and normalizing/tempering conditions (normalized-1040 °C/40 min, air cooled; tempered 760 °C/2 h, air cooled) were employed. The influence of subsequent PWHT and N&T treatment on the microstructure of various zone of P91 pipe weldments were also investigated. The present investigation also described the effect of PWHT and N&T treatment on hardness, grain size, precipitate size, inter-particle spacing and fraction area of precipitates present in each zone of P91 pipe weldments. The result indicated great impact of heat treatment on the Charpy toughness and microstructure evolution of P91 weldments. The N&T treatment was found to be more effective heat treatment compared to subsequent PWHT. Charpy toughness value was found to be higher for narrow-groove design as compared to conventional V-groove design.

Statistical evaluation of the metallurgical test data in the ORR-PSF-PVS irradiation experiment. [PWR; BWR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stallmann, F.W.

1984-08-01

A statistical analysis of Charpy test results of the two-year Pressure Vessel Simulation metallurgical irradiation experiment was performed. Determination of transition temperature and upper shelf energy derived from computer fits compare well with eyeball fits. Uncertainties for all results can be obtained with computer fits. The results were compared with predictions in Regulatory Guide 1.99 and other irradiation damage models.

Impact Tests of Welded Joints

DTIC Science & Technology

1936-04-01

indicate that good welds by these two last named processes give excellent impact results. Welds subjected to extremely low or high temperature merit...variation with temperature of the ratio of shear to tensile stress developed in the Izod or Charpy test, falls from a high to an exceedingly low value...and Larsen also showed that high nitrogen or oxygen content shifted the "zone of transition" to higher temperatures , and that normalizing shifted the

Marine Structural Steel Toughness Data Bank (Abridged Edition)

DTIC Science & Technology

1990-08-31

for Table Column Headings: Break? Did specimen fracture completely? CODIc Critical COD CODi Initial COD CVN Energy Charpy V Energy Crack lgth Crack...Standard Y ear ........ .................. * Onen Test Temp KQ CODi CODIc Curve 3l degF ksi*in**0.5 mils mils in-lb/in2 L-T -166...Standard Method .... BS5762 -Standard Year . Test Temp CODIc degC mm -30 0.57 -30 0.68 -30 11.26 (continued) -not reported

The Effect of Dimensional Changes on Square V-Notched Charpy Bars (Sixth Partial Report on Temper Brittleness)

DTIC Science & Technology

1949-01-13

Charpy specimens. These data are for one steel which has been given a single heat treatment. The effects of a reduction in cross-sectional area and of...air cooled. After this they were tempered at 650oC (1200*?) for 1 hour and water quenched. This treatment produced a structure of tempered bainite

An automated data collection system for a Charpy impact tester

NASA Technical Reports Server (NTRS)

Weigman, Bernard J.; Spiegel, F. Xavier

1993-01-01

A method for automated data collection has been developed for a Charpy impact tester. A potentiometer is connected to the pivot point of the hammer and measures the angular displacement of the hammer. This data is collected with a computer and, through appropriate software, accurately records the energy absorbed by the specimen. The device can be easily calibrated with minimal effort.

Influence of M-TIG and A-TIG Welding Process on Microstructure and Mechanical Behavior of 409 Ferritic Stainless Steel

NASA Astrophysics Data System (ADS)

Vidyarthy, R. S.; Dwivedi, D. K.; Vasudevan, M.

2017-03-01

The current study investigates the effects of activating flux tungsten inert gas welding (A-TIG) and multipass tungsten inert gas welding (M-TIG) on the weld morphology, angular distortion, microstructures and mechanical properties when welding 8-mm-thick 409 ferritic stainless steel (FSS). SiO2 was used as activating flux for A-TIG welding, while SUPERTIG ER309L was used as filler for M-TIG welding. Bead-on-plate weld trials were carried out to obtain the full penetration by using different combinations of flux coating density, welding speed and welding current. An optical microscope, field emission scanning microscope (FESEM), and x-ray diffractometer were used for the metallurgical characterizations. Vickers hardness, tensile test, Charpy toughness test, and creep behavior test were carried out to evaluate the mechanical properties of the base and weld metals. Experimental results indicate that the A-TIG process can increase the joint penetration and tends to reduce the angular distortion of the 409 FSS weldment. The A-TIG welded joint also exhibited greater mechanical strength. However, a critically low Charpy toughness was measured for the A-TIG weld fusion zone, which was later sufficiently improved after post weld heat treatment (PWHT). It was concluded that PWHT is mandatory for A-TIG welded 409 FSS.

Assessment of Ductile-to-Brittle Transition Behavior of Localized Microstructural Regions in a Friction-Stir Welded X80 Pipeline Steel with Miniaturized Charpy V-Notch Testing

NASA Astrophysics Data System (ADS)

Avila, Julian A.; Lucon, Enrico; Sowards, Jeffrey; Mei, Paulo Roberto; Ramirez, Antonio J.

2016-06-01

Friction-stir welding (FSW) is an alternative welding process for pipelines. This technology offers sound welds, good repeatability, and excellent mechanical properties. However, it is of paramount importance to determine the toughness of the welds at low temperatures in order to establish the limits of this technology. Ductile-to-brittle transition curves were generated in the present study by using a small-scale instrumented Charpy machine and miniaturized V-notch specimens (Kleinstprobe, KLST); notches were located in base metal, heat-affected, stirred, and hard zones within a FSW joint of API-5L X80 Pipeline Steel. Specimens were tested at temperatures between 77 K (-196 °C) and 298 K (25 °C). Based on the results obtained, the transition temperatures for the base material and heat-affected zone were below 173 K (-100 °C); conversely, for the stirred and hard zones, it was located around 213 K (-60 °C). Fracture surfaces were characterized and showed a ductile fracture mechanism at high impact energies and a mixture of ductile and brittle mechanisms at low impact energies.

Marine Structural Steel Toughness Data Bank. Volume 3

DTIC Science & Technology

1991-08-28

Headings: Break? Did specimen fracture completely? CODIc Critical COD CODi Initial COD CVN Energy Charpy V Energy Crack lgth Crack Length Curve Curve...BS5762 -Standard Year Test Temp CODIc degC mm -30 0.57 -30 0.68 -30 . 1.26 not rporw(continued) Main Stutua To n ssDta:an Material BS4360 Gr50D Page...Initial JI. . . .. ._I. . . Maximum 1, ]max * Tearing Modulus ......... Standard Method ~P S5762 -Standard Year_______________ Test Tcmp CODIc degC mm

Effect of Tempering and Baking on the Charpy Impact Energy of Hydrogen-Charged 4340 Steel

NASA Astrophysics Data System (ADS)

Mori, K.; Lee, E. W.; Frazier, W. E.; Niji, K.; Battel, G.; Tran, A.; Iriarte, E.; Perez, O.; Ruiz, H.; Choi, T.; Stoyanov, P.; Ogren, J.; Alrashaid, J.; Es-Said, O. S.

2015-01-01

Tempered AISI 4340 steel was hydrogen charged and tested for impact energy. It was found that samples tempered above 468 °C (875 °F) and subjected to hydrogen charging exhibited lower impact energy values when compared to uncharged samples. No significant difference between charged and uncharged samples tempered below 468 °C (875 °F) was observed. Neither exposure nor bake time had any significant effect on impact energy within the tested ranges.

Marine Structural Steel Toughness Data Bank. Volume 4

DTIC Science & Technology

1990-08-31

Break? Did specimen fracture completely? CODIc Critical COD CODi Initial COD CVN Energy Charpy V Energy Crack lgth Crack Length Curve Curve Shape DT...Onien Test Temp COIi CODIc i1 imax Tear Mod degF in In in-lb/in**2 in-lb/in**2 in-lb/in**2 L-T 72 0.0236 0.0380 4346 4315 260.2 L-T 72

Development of Mini-Compact Tension Test Method for Determining Fracture Toughness Master Curves for Reactor Pressure Vessel Steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sokolov, Mikhail A.

Small specimens are playing the key role in evaluating properties of irradiated materials. The use of small specimens provides several advantages. Typically, only a small volume of material can be irradiated in a reactor at desirable conditions in terms of temperature, neutron flux, and neutron dose. A small volume of irradiated material may also allow for easier handling of specimens. Smaller specimens reduce the amount of radioactive material, minimizing personnel exposures and waste disposal. However, use of small specimens imposes a variety of challenges as well. These challenges are associated with proper accounting for size effects and transferability of smallmore » specimen data to the real structures of interest. Any fracture toughness specimen that can be made out of the broken halves of standard Charpy specimens may have exceptional utility for evaluation of reactor pressure vessels (RPVs) since it would allow one to determine and monitor directly actual fracture toughness instead of requiring indirect predictions using correlations established with impact data. The Charpy V-notch specimen is the most commonly used specimen geometry in surveillance programs. Validation of the mini compact tension specimen (mini-CT) geometry has been performed on previously well characterized Midland beltline Linde 80 (WF-70) weld in the unirradiated condition. It was shown that the fracture toughness transition temperature, To, measured by these Mini-CT specimens is almost the same as To value that was derived from various larger fracture toughness specimens. Moreover, an International collaborative program has been established to extend the assessment and validation efforts to irradiated Linde 80 weld metal. The program is underway and involves the Oak Ridge National Laboratory (ORNL), Central Research Institute for Electrical Power Industry (CRIEPI), and Electric Power Research Institute (EPRI). The irradiated Mini-CT specimens from broken halves of previously tested Charpy specimens of Midland beltline weld have been machined and just arrived to ORNL as part of this international collaboration. The ORNL will initiate tests of the irradiated Linde 80 weld in FY2017 and results of this international program will be reported in FY2018.« less

Low blow Charpy impact of silicon carbides

NASA Technical Reports Server (NTRS)

Abe, H.; Chandan, H. C.; Bradt, R. C.

1978-01-01

The room-temperature impact resistance of several commercial silicon carbides was examined using an instrumented pendulum-type machine and Charpy-type specimens. Energy balance compliance methods and fracture toughness approaches, both applicable to other ceramics, were used for analysis. The results illustrate the importance of separating the machine and the specimen energy contributions and confirm the equivalence of KIc and KId. The material's impact energy was simply the specimen's stored elastic strain energy at fracture.

Effect of microstructural evolution by isothermal aging on the mechanical properties of 9Cr-1WVTa reduced activation ferritic/martensitic steels

NASA Astrophysics Data System (ADS)

Park, Min-Gu; Lee, Chang-Hoon; Moon, Joonoh; Park, Jun Young; Lee, Tae-Ho; Kang, Namhyun; Chan Kim, Hyoung

2017-03-01

The influence of microstructural changes caused by aging condition on tensile and Charpy impact properties was investigated for reduced activation ferritic-martensitic (RAFM) 9Cr-1WVTa steels having single martensite and a mixed microstructure of martensite and ferrite. For the mixed microstructure of martensite and ferrite, the Charpy impact properties deteriorated in both as-normalized and tempered conditions due to the ferrite and the accompanying M23C6 carbides at the ferrite grain boundaries which act as path and initiation sites for cleavage cracks, respectively. However, aging at 550 °C for 20-100 h recovered gradually the Charpy impact toughness without any distinct drop in strength, as a result of the spheroidization of the coarse M23C6 carbides at the ferrite grain boundaries, which makes crack initiation more difficult.

Impact Properties of Irradiated HT9 from the Fuel Duct of FFTF

DOE Office of Scientific and Technical Information (OSTI.GOV)

Byun, Thak Sang; Maloy, S; Toloczko, M

2012-01-01

This paper reports Charpy impact test data for the ACO-3 duct material (HT9) from the Fast Flux Test Facility (FFTF) and its archive material. Irradiation doses for the specimens were in the range of 3 148 dpa and irradiation temperatures in the range of 378 504 oC. The impact tests were performed for the small V-notched Charpy specimens with dimensions of 3 4 27 mm at an impact speed of 3.2 m/s in a 25J capacity machine. Irradiation lowered the upper-shelf energy (USE) and increased the transition temperatures significantly. The shift of transition temperatures was greater after relatively low temperaturemore » irradiation. The USE values were in the range of 5.5 6.7 J before irradiation and decreased to the range of 2 5 J after irradiation. Lower USEs were measured for lower irradiation temperatures and specimens with T-L orientation. For the irradiated specimens, the dose dependences of transition temperature and USE were not significant because of the radiation effect on impact behavior nearly saturated at the lowest dose of about 3 dpa. A comparison showed that the lateral expansion of specimens showed a linear correlation with absorbed impact energy, but with large scatter in the results. The size effect was also discussed to clarify the differences in the impact data of subsize and standard specimens.« less

An automated digital data collection and analysis system for the Charpy Impact Tester

NASA Technical Reports Server (NTRS)

Kohne, Glenn S.; Spiegel, F. Xavier

1994-01-01

The standard Charpy Impact Tester has been modified by the addition of a system of hardware and software to improve the accuracy and consistency of measurements made during specimen fracturing experiments. An optical disc, light source, and detector generate signals that indicate the pendulum position as a function of time. These signals are used by a computer to calculate the velocity and kinetic energy of the pendulum as a function of its position.

49 CFR 179.102-1 - Carbon dioxide, refrigerated liquid.

Code of Federal Regulations, 2010 CFR

2010-10-01

... and anchorage of tanks must be made of carbon steel conforming to ASTM A 516/A 516M (IBR, see § 171.7 of this subchapter), Grades 55, 60, 65, or 70, or AAR Specification TC 128-78, Grade B. The ASTM A 516/A 516M plate must also meet the Charpy V-Notch test requirements of ASTM A 20/A 20M (see table 16...

Effect of Local Crystallographic Texture on the Fissure Formation During Charpy Impact Testing of Low-Carbon Steel

NASA Astrophysics Data System (ADS)

Ghosh, Abhijit; Patra, Sudipta; Chatterjee, Arya; Chakrabarti, Debalay

2016-06-01

The severity of the formation of fissures (also known as splitting or delamination) on the fracture surface of Charpy impact-tested samples of a low-carbon steel has been found to increase with the decrease in finish rolling temperature [1093 K to 923 K (820 °C to 650 °C)]. Combined scanning electron microscopy and electron back-scattered diffraction study revealed that crystallographic texture was the prime factor responsible for the fissure formation. Through-thickness texture band composed of cube [Normal Direction (ND)║<001>] and gamma [ND║<111>] orientations developed during the inter-critical rolling treatment. Strain incompatibility between these two texture bands causes fissure cracking on the main fracture plane. A new approach based on the angle between {001} planes of neighboring crystals has been employed in order to estimate the `effective grain size,' which is used to determine the cleavage fracture stress on different planes of a sample. The severity of fissure formation was found to be directly related to the difference in cleavage fracture stress between the `main fracture plane' and `fissure plane.' Clustering of ferrite grains having cube texture promoted the fissure crack propagation along the transverse `fissure plane,' by increasing the `effective grain size' and decreasing the cleavage fracture stress on that plane.

Heavy-section steel irradiation program. Progress report, April 1996--September 1996

DOE Office of Scientific and Technical Information (OSTI.GOV)

Corwin, W.R.

1997-09-01

The Heavy-Section Steel Irradiation Program was established to quantitatively assess the effects of neutron irradiation on the material behavior of typical reactor pressure vessel (RPV) steels. During this period, fracture mechanics testing of specimens of the irradiated low upper shelf (LUS) weld were completed and analyses performed. Heat treatment of five RPV plate materials was initiated to examine phosphorus segregation effects on the fracture toughness of the heat affected zone of welds. Initial results show that all five materials exhibited very large prior austenite grain sizes as a consequence of the initial heat treatment. Irradiated and annealed specimens of LUSmore » weld material were tested and analyzed. Four sets of Charpy V-notch (CVN) specimens were aged at various temperatures and tested to examine the reason for overrecovery of upper shelf energy that has been observed. Molecular dynamics cascade simulations were extended to 40 keV and have provided information representative of most of the fast neutron spectrum. Investigations of the correlation between microstructural changes and hardness changes in irradiated model alloys was also completed. Preliminary planning for test specimen machining for the Japan Power Development Reactor was completed. A database of Charpy impact and fracture toughness data for RPV materials that have been tested in the unirradiated and irradiated conditions is being assembled and analyzed. Weld metal appears to have similar CVN and fracture toughness transition temperature shifts, whereas the fracture toughness shifts are greater than CVN shifts for base metals. Draft subcontractor reports on precracked cylindrical tensile specimens were completed, reviewed, and are being revised. Testing on precracked CVN specimens, both quasi-static and dynamic, was evaluated. Additionally, testing of compact specimens was initiated as an experimental comparison of constraint limitations. 16 figs., 2 tabs.« less

Effect on fast neutron irradiation to 4 dpa at 400{degrees}C on the properties of V-(4-5)Cr-(4-5)Ti alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zinkle, S.J.; Alexander, D.J.; Robertson, J.P.

1997-04-01

Tensile, Charpy impact and electrical resistivity measurements have been performed at ORNL on V-4Cr-4Ti and V-5Cr-5Ti specimens that were prepared at ANL and irradiated in the lithium-bonded X530 experiment in the EBR-II fast reactor. All of the specimens were irradiated to a damage level of about 4 dpa at a temperature of {approximately}400{degrees}C. A significant amount of radiation hardening was evident in both the tensile and Charpy impact tests. The irradiated V-4Cr-4Ti yield strength measured at {approximately}390{degrees}C was >800 MPa, which is more than three times as high as the unirradiated value. The uniform elongations of the irradiated tensile specimensmore » were typically {approximately}1%, with corresponding total elongations of 4-6%. The ductile to brittle transition temperature of the irradiated specimens was less than the unirradiated resistivity, which suggests that hardening associated with interstitial solute pickup was minimal.« less

Effective grain size and charpy impact properties of high-toughness X70 pipeline steels

NASA Astrophysics Data System (ADS)

Hwang, Byoungchul; Kim, Yang Gon; Lee, Sunghak; Kim, Young Min; Kim, Nack J.; Yoo, Jang Yong

2005-08-01

The correlation of microstructure and Charpy V-notch (CVN) impact properties of a high-toughness API X70 pipeline steel was investigated in this study. Six kinds of steel were fabricated by varying the hot-rolling conditions, and their microstructures, effective grain sizes, and CVN impact properties were analyzed. The CVN impact test results indicated that the steels rolled in the single-phase region had higher upper-shelf energies (USEs) and lower energy-transition temperatures (ETTs) than the steels rolled in the two-phase region because their microstructures were composed of acicular ferrite (AF) and fine polygonal ferrite (PF). The decreased ETT in the steels rolled in the single-phase region could be explained by the decrease in the overall effective grain size due to the presence of AF having a smaller effective grain size. On the other hand, the absorbed energy of the steels rolled in the two-phase region was considerably lower because a large amount of dislocations were generated inside PFs during rolling. It was further decreased when coarse martensite or cementite was formed during the cooling process.

Fracture toughness of irradiated modified 9Cr-1Mo steel

NASA Astrophysics Data System (ADS)

Kim, Sung Ho; Yoon, Ji-Hyun; Ryu, Woo Seog; Lee, Chan Bock; Hong, Jun Hwa

2009-04-01

The effects of irradiation on fracture toughness of modified 9Cr-1Mo steel in the transition region were investigated. Half size precracked Charpy specimens were irradiated up to 1.2 × 10 21n/cm 2 ( E > 0.1 MeV) at 340 °C and 400 °C in the Korean research reactor. The irradiation induced transition temperature shift for a modified 9Cr-1Mo was evaluated by using the Master Curve methodology. The T0 temperature for the unirradiated specimens were measured as -67.7 °C and -72.4 °C from the tests with standard PCVN (precracked charpy V-notch) and half sized PCVN specimens, respectively. The T0 shifts of specimens after irradiation at 340 °C and 400 °C were 70.7 °C and 66.1 °C, respectively. The Weibull slopes for the fracture toughness data obtained from the unirradiated and irradiated modified 9Cr-1Mo steels were determined to confirm the applicability of master curve methodology to modified 9Cr-1Mo steel.

Subject Categorization Guide for Defense Science and Technology

DTIC Science & Technology

1986-10-01

transfer 06/08 Cherries 20/05 Charged particles 08/06 Chesapeake Bay 20/11 Charpy impact tests 12/03 Chi square test 21/02 Charring 06/03 Chickens 14/05... Mexico 11/06 Metal films 08/06 Mexico Gulf 13/09 Metal forming brakes 08/07 Mica 13/09 Metal forming presses 09/01 Mirl capacitors 13/05 Metal joints 06...Nobolium COMPouO~S 08/06 Now Mexico 06/13 Nocardia 08/06 New York 04101 Noctllu(cent clouds 08/06 New York City(New York) 04/02 08/06 New Zealand 06/03

Mechanical, Thermal and Dynamic Mechanical Properties of PP/GF/xGnP Nanocomposites

NASA Astrophysics Data System (ADS)

Ashenai Ghasemi, F.; Ghorbani, A.; Ghasemi, I.

2017-03-01

The mechanical, thermal, and dynamic mechanical properties of ternary nanocomposites based on polypropylene, short glass fibers, and exfoliated graphene nanoplatelets were studied. To investigate the mechanical properties, uniaxial tensile and Charpy impact tests were carried out. To study the crystallinity of the compositions, a DSC test was performed. A dynamic mechanical analysis was used to characterize the storage modulus and loss factor (tan δ). The morphology of the composites was studied by a scanning electron microscope (SEM). The results obtained are presented in tables and graphics.

Experimental Investigation of Fibre Reinforced Composite Materials Under Impact Load

NASA Astrophysics Data System (ADS)

Koppula, Sravani; Kaviti, Ajay kumar; Namala, Kiran kumar

2018-03-01

Composite materials are extensively used in various engineering applications. They have very high flexibility design which allows prescribe tailoring of material properties by lamination of composite fibres with reinforcement of resin to it. Complex failure condition prevail in the composite materials under the action of impact loads, major modes of failure in composite may include matrix cracking, fibre matrix, fibre breakage, de-bonding or de- lamination between composite plies. This paper describes the mechanical properties of glass fibre reinforced composite material under impact loading conditions through experimental setup. Experimental tests are performed according to ASTM standards using impact testing machines like Charpy test, computerized universal testing machine.

Effects of microstructural variation on Charpy impact properties in heavy-section Mn-Mo-Ni low alloy steel for reactor pressure vessel

NASA Astrophysics Data System (ADS)

Hong, Seokmin; Song, Jaemin; Kim, Min-Chul; Choi, Kwon-Jae; Lee, Bong-Sang

2016-03-01

The effects of microstructural changes in heavy-section Mn-Mo-Ni low alloy steel on Charpy impact properties were investigated using a 210 mm thick reactor pressure vessel. Specimens were sampled from 5 different positions at intervals of 1/4 thickness from the inner surface to the outer surface. A detailed microstructural analysis of impact-fractured specimens showed that coarse carbides along the lath boundaries acted as fracture initiation sites, and cleavage cracks deviated at prior-austenite grain boundaries and bainite lath boundaries. Upper shelf energy was higher and energy transition temperature was lower at the surface positon, where fine bainitic microstructure with homogeneously distributed fine carbides were present. Toward the center, coarse upper bainite and precipitation of coarse inter-lath carbides were observed, which deteriorated impact properties. At the 1/4T position, the Charpy impact properties were worse than those at other positions owing to the combination of elongated-coarse inter-lath carbides and large effective grain size.

Correlation of Toughness between H-Plate and Charpy Impact Tests

DTIC Science & Technology

1959-09-01

thermal cycles having peak temperatures in or near the range of critical transformation temperatures. Notch sensitivity in these regions has been...21- In their recent work the transition temperatures of heat-affected-zone struc- tures produced by thermal cycles having peak temperatures in the...gradient of thermal cycles associated with welding is too complex to have been included in the scope of this report. The superior toughness of the Ni

The Shock and Vibration Digest. Volume 15, Number 10

DTIC Science & Technology

1983-10-01

tendency to increase. The SMDE spectrum guarantees that the simply supported beam model provides a APLICATIONS OF SRS IN DESIGN conservative design for...Effects on Boron-Aluminum Composites," "The Charpy Impact Test as a Method for --- Masters Thesis (Mar 1974). Evaluating Impact Resistance of Composite...peon rings in responsq to the Impacts received Ph.D. Thesis , Georgia Inst. of Tech., 462 pp (1982) . - from the tool hammer and the workplace. A

Thermal annealing recovery of fracture toughness in HT9 steel after irradation to high doses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Byun, Thak Sang; Baek, Jong-Hyuk; Anderoglu, Osman

2013-08-03

The HT9 ferritic/martensitic steel with a nominal chemistry of Fe(bal.)–12%Cr–1%MoVW has been used as a primary core material for fast fission reactors such as FFTF because of its high resistance to radiationinduced swelling and embrittlement. Both static and dynamic fracture test results have shown that the HT9 steel can become brittle when it is exposed to high dose irradiation at a relatively low temperature 430 °C). This article aims at a comprehensive discussion on the thermal annealing recovery of fracture toughness in the HT9 steel after irradiation up to 3–148 dpa at 378–504 °C. A specimen reuse technique has beenmore » established and applied to this study: the fracture specimens were tested Charpy specimens or broken halves of Charpy bars (13 3 4 mm). The post-anneal fracture test results indicated that much of the radiation-induced damage can be recovered by a simple thermal annealing schedule: the fracture toughness was incompletely recovered by 550 °C annealing, while nearly complete or complete recovery occurred after 650 °C annealing. This indicates that thermal annealing is a feasible damage mitigation technique for the reactor components made of HT9 steel. The partial recovery is probably due to the non-removable microstructural damages such as void or gas bubble formation, elemental segregation and precipitation.« less

Evaluation of material homogeniety as a function of thickness of low-alloy ferritic steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, T.L.; Lambert, M.A.

1989-11-01

A series of Charpy and nil-ductility transition temperature (NDTT) tests were performed on 8 in. and 12 in. thick forgings of A508-4A, A508-4B, and A350-LF3 steels. Three different positions in thickness were tested in the 12 in. forgings, while two locations in the forging were analyzed. Chemical analysis and metallographic examination were also performed on each material and in each thickness location. The material toughness tended to be lower in the thicker forgings and in the center of a given forging. Low relative toughness coincided with well tempered microstructures, where equiaxed ferrite grains had begun to form. These grains aremore » coarser than the packet structure that existed at earlier stages of tempering. Low quench rates (associated with thick sections and central regions of a given thickness) apparently accelerated the structural changes during tempering, which led to microstructures with low toughness. The NDTT results were suspect because most arrests occurred in the heat affected zones (HAZs) of the welds rather than in the parent metal. The measured NDTT values were lower than expected, based on published empirical correlations with Charpy energy. This was particularly true for the A508-4A steel. This provided further evidence that the drop weight tests were actually measuring the arrest properties of the HAZ in most cases. The fact that NDTT values were lower than expected is particularly surprising since the anvil test fixture was machined with a deflection stop 25 percent higher than the standard value.« less

Study on the Toughness of X100 Pipeline Steel Heat Affected Zone

NASA Astrophysics Data System (ADS)

Li, Xueda; Shang, Chengjia; Ma, Xiaoping; Subramanian, S. V.

Microstructure-property correlation of heat affected zone (HAZ) in X100 longitudinal submerged arc welding (LSAW) real weld joint was studied in this paper. Coarse grained (CG) HAZ and intercritically reheated coarse grained (ICCG) HAZ were characterized by optical microscope (OM), electron backscattered diffraction (EBSD). The microstructure of CGHAZ is mostly composed of granular bainite with low density of high angle boundaries (HAB). Prior austenite grain size is 80μm. In ICCGHAZ, coarse prior austenite grains were decorated by coarse necklacing martensite-austenite (M-A) constituents. Different layers were observed within M-A constituent, which may be martensite and austenite layers. Charpy absorbed energy of two different HAZ regions (ICCGHAZ containing and non-containing regions) was recorded using instrumental Charpy impact test machine. The results showed that the existence of ICCGHAZ resulted in the sharp drop of Charpy absorbed energy from 180J to 50J, while the existence of only CGHAZ could still lead to good toughness. The fracture surface was 60% brittle in the absence of ICCGHAZ, and 100% brittle in the presence of ICCGHAZ in the impact tested samples. The underlying reason is the microstructure of ICCGHAZ consisted of granular bainite and upper bainite with necklace-type M-A constituent along the grain boundaries. Cleavage fracture initiated from M-A constituent, either through cracking of M-A or debonding from the matrix, was observed at the fracture surface of ICCGHAZ. The presence of necklace type M-A constituent in ICCGHAZ notably increases the susceptibility of cleavage microcrack nucleation. Furthermore, the study of secondary microcracks beneath the CGHAZ and the ICCGHAZ through EBSD suggested that the fracture mechanism changes from nucleation-controlled in the CGHAZ to propagation-controlled in the ICCGHAZ because of the presence of necklace-type M-A constituent in the ICCGHAZ region. Both fracture mechanism contribute to the poor toughness of the sample contained ICCGHAZ. In conclusion, big prior austenite grains with low density of HAB plus coarse necklacing M-A products along grain boundary is the dominant factor resulting in low toughness.

Final Report, Volume 2, The Development of Qualification Standards for Cast Duplex Stainless Steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russell, Steven, W.; Lundin, Carl, W.

2005-09-30

The scope of testing cast Duplex Stainless Steel (DSS) required testing to several ASTM specifications, while formulating and conducting industry round robin tests to verify and study the reproducibility of the results. ASTM E562 (Standard Test Method for Determining Volume Fraction by Systematic manual Point Count) and ASTM A923 (Standard Test Methods for Detecting Detrimental Intermetallic Phase in Wrought Duplex Austenitic/Ferritic Stainless Steels) were the specifications utilized in conducting this work. An ASTM E562 industry round robin, ASTM A923 applicability study, ASTM A923 industry round robin, and an ASTM A923 study of the effectiveness of existing foundry solution annealing proceduresmore » for producing cast DSS without intermetallic phases were implemented. In the ASTM E562 study, 5 samples were extracted from various cast austenitic and DSS in order to have varying amounts of ferrite. Each sample was metallographically prepared by UT and sent to each of 8 participants for volume fraction of ferrite measurements. Volume fraction of ferrite was measured using manual point count per ASTM E562. FN was measured from the Feritescope® and converted to volume fraction of ferrite. Results indicate that ASTM E562 is applicable to DSS and the results have excellent lab-to-lab reproducibility. Also, volume fraction of ferrite conversions from the FN measured by the Feritescope® were similar to volume fraction of ferrite measured per ASTM E562. In the ASTM A923 applicability to cast DSS study, 8 different heat treatments were performed on 3 lots of ASTM A890-4A (CD3MN) castings and 1 lot of 2205 wrought DSS. The heat treatments were selected to produce a wide range of cooling rates and hold times in order to study the suitability of ASTM A923 to the response of varying amounts on intermetallic phases [117]. The test parameters were identical to those used to develop ASTM A923 for wrought DSS. Charpy V-notch impact samples were extracted from the castings and wrought DSS and tested per ASTM A923 method B (Charpy impact test). Method A (sodium hydroxide etch test) was performed on one half of a fractured Charpy V-notch impact sample and Method C (ferric chloride corrosion weight loss test) was performed on another half. Test results for the three cast lots and one wrought lot indicate that ASTM A923 is relevant for detecting intermetallic phases in cast DSS. In the ASTM A923 round robin study, five laboratories conducted ASTM A923 Methods A & C on cast DSS material and the lab-to-lab reproducibility of the data was determined. Two groups of samples were sent to the participants. Group 1 samples were tested per ASTM A923 Method A, group 2 samples were tested by ASTM A923 Method C. Testing procedures for this round robin study were identical to those used in the ASTM A923 applicability study. Results from this round robin indicate that there is excellent lab-to-lab reproducibility of ASTM A923 with respect to cast DSS and that ASTM A923 could be expanded to cover both wrought and cast DSS. In the ASTM A923 study of the effectiveness of existing foundry solution annealing procedures for producing cast DSS without intermetallic phases, Ten heats of ASTM A890-4A (CD3MN) in the foundry solution annealed condition were tested per ASTM A923 Methods A, B, & C. Testing of these materials per ASTM A923 was used to determine if the foundry solution anneal procedures were adequate to completely eliminate any intermetallic phases, which may have precipitated during the casting and subsequent heat treatment processes. All heats showed no sign of intermetallic phase per Method A, passed minimum Charpy impact energy requirements per Method B (> 40 ft-lbs @ -40°C (-40°F)), and showed negligible weight loss per Method C (< 10 mdd). These results indicate that the solution annealing procedure used by foundries is adequate to produce a product free from intermetallic phases.« less

Final Report, Volume 2, The Development of Qualification Standards for Cast Duplex Stainless Steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russell, Steven, W.; Lundin, Carl, D.

2005-09-30

The scope of testing cast Duplex Stainless Steel (DSS) required testing to several ASTM specifications, while formulating and conducting industry round robin tests to verify and study the reproducibility of the results. ASTM E562 (Standard Test Method for Determining Volume Fraction by Systematic manual Point Count) and ASTM A923 (Standard Test Methods for Detecting Detrimental Intermetallic Phase in Wrought Duplex Austenitic/Ferritic Stainless Steels) were the specifications utilized in conducting this work. An ASTM E562 industry round robin, ASTM A923 applicability study, ASTM A923 industry round robin, and an ASTM A923 study of the effectiveness of existing foundry solution annealing proceduresmore » for producing cast DSS without intermetallic phases were implemented. In the ASTM E562 study, 5 samples were extracted from various cast austenitic and DSS in order to have varying amounts of ferrite. Each sample was metallographically prepared by UT and sent to each of 8 participants for volume fraction of ferrite measurements. Volume fraction of ferrite was measured using manual point count per ASTM E562. FN was measured from the Feritescope{reg_sign} and converted to volume fraction of ferrite. Results indicate that ASTM E562 is applicable to DSS and the results have excellent lab-to-lab reproducibility. Also, volume fraction of ferrite conversions from the FN measured by the Feritescope{reg_sign} were similar to volume fraction of ferrite measured per ASTM E562. In the ASTM A923 applicability to cast DSS study, 8 different heat treatments were performed on 3 lots of ASTM A890-4A (CD3MN) castings and 1 lot of 2205 wrought DSS. The heat treatments were selected to produce a wide range of cooling rates and hold times in order to study the suitability of ASTM A923 to the response of varying amounts on intermetallic phases [117]. The test parameters were identical to those used to develop ASTM A923 for wrought DSS. Charpy V-notch impact samples were extracted from the castings and wrought DSS and tested per ASTM A923 method B (Charpy impact test). Method A (sodium hydroxide etch test) was performed on one half of a fractured Charpy V-notch impact sample and Method C (ferric chloride corrosion weight loss test) was performed on another half. Test results for the three cast lots and one wrought lot indicate that ASTM A923 is relevant for detecting intermetallic phases in cast DSS. In the ASTM A923 round robin study, five laboratories conducted ASTM A923 Methods A & C on cast DSS material and the lab-to-lab reproducibility of the data was determined. Two groups of samples were sent to the participants. Group 1 samples were tested per ASTM A923 Method A, group 2 samples were tested by ASTM A923 Method C. Testing procedures for this round robin study were identical to those used in the ASTM A923 applicability study. Results from this round robin indicate that there is excellent lab-to-lab reproducibility of ASTM A923 with respect to cast DSS and that ASTM A923 could be expanded to cover both wrought and cast DSS. In the ASTM A923 study of the effectiveness of existing foundry solution annealing procedures for producing cast DSS without intermetallic phases, Ten heats of ASTM A890-4A (CD3MN) in the foundry solution annealed condition were tested per ASTM A923 Methods A, B, & C. Testing of these materials per ASTM A923 was used to determine if the foundry solution anneal procedures were adequate to completely eliminate any intermetallic phases, which may have precipitated during the casting and subsequent heat treatment processes. All heats showed no sign of intermetallic phase per Method A, passed minimum Charpy impact energy requirements per Method B (> 40 ft-lbs {at} -40 C (-40 F)), and showed negligible weight loss per Method C (< 10 mdd). These results indicate that the solution annealing procedure used by foundries is adequate to produce a product free from intermetallic phases.« less

The impact resistance of SiC and other mechanical properties of SiC and Si3N4

NASA Technical Reports Server (NTRS)

Bradt, R. C.

1984-01-01

Studies focused on the impact and mechanical behavior of SiC and Si3N4 at high temperatures are summarized. Instrumented Charpy impact testing is analyzed by a compliance method and related to strength; slow crack growth is related to processing, and creep is discussed. The transient nature of flaw populations during oxidation under load is emphasized for both SiC and Si3N4.

Effects of Cooling Conditions on Tensile and Charpy Impact Properties of API X80 Linepipe Steels

NASA Astrophysics Data System (ADS)

Han, Seung Youb; Shin, Sang Yong; Lee, Sunghak; Kim, Nack J.; Bae, Jin-Ho; Kim, Kisoo

2010-02-01

In this study, four API X80 linepipe steel specimens were fabricated by varying the cooling rate and finish cooling temperature, and their microstructures and crystallographic orientations were analyzed to investigate the effects of the cooling conditions on the tensile and Charpy impact properties. All the specimens consisted of acicular ferrite (AF), granular bainite (GB), and martensite-austenite (MA) constituents. The volume fraction of MA increased with an increasing cooling rate, and the volume fraction and size of MA tended to decrease with an increasing finish cooling temperature. According to the crystallographic orientation analysis data, the effective grain size and unit crack path decreased as fine ACs having a large amount of high-angle grain boundaries were homogeneously formed, thereby leading to the improvement in the Charpy impact properties. The specimen fabricated with the higher cooling rate and lower finish cooling temperature had the highest upper-shelf energy (USE) and the lowest energy transition temperature (ETT), because it contained a large amount of MA homogeneously distributed inside fine AFs, while its tensile properties remained excellent.

Correlation of microstructure and tempered martensite embrittlement in two 4340 steels

NASA Astrophysics Data System (ADS)

Lee, S.; Lee, D. Y.; Asaro, R. J.

1989-06-01

This study is concerned with a correlation between the microstructure and fracture behavior of two AISI 4340 steels which were vacuum induction melted and then deoxidized with aluminum and titanium additions. This allowed a comparison between microstructures that underwent large increases in grain size and those that did not. When the steels were tempered at 350°C, K Ic and Charpy impact energy plots showed troughs which indicated tempered martensite embrittlement (TME). The TME results of plane strain fracture toughness are interpreted using a simple ductile fracture initiation model based on large strain deformation fields ahead of cracks, suggesting that K Icscales roughly with the square root of the spacing of cementite particles precipitated during the tempering treatment. The trough in Charpy impact energy is found to coincide well with the amount of intergranular fracture and the effect of segregation of phosphorus on the austenite grain boundaries. In addition, cementite particles are of primary importance in initiating the intergranular cracks and, consequently, reducing the Charpy energy. These findings suggest that TME in the two 4340 steels studied can be explained quantitatively using different fracture models.

The Structure and Properties of Diffusion Assisted Bonded Joints in 17-4 PH, Type 347, 15-5 PH and Nitronic 40 Stainless Steels

NASA Technical Reports Server (NTRS)

Wigley, D. A.

1981-01-01

Diffusion assisted bonds are formed in 17-4 PH, 15-5 PH, type 347 and Nitronic 40 stainless steels using electrodeposited copper as the bonding agent. The bonds are analyzed by conventional metallographic, electron microprobe analysis, and scanning electron microscopic techniques as well as Charpy V-notch impact tests at temperatures of 77 and 300 K. Results are discussed in terms of a postulated model for the bonding process.

Fatigue and Fracture-Toughness Characterization of SAW and SMA A537 Class I Ship-Steel Weldments.

DTIC Science & Technology

1981-12-01

Charpy criterion and proposed NDT-DT criterion of Rolfe . Recommendations are made and further research is suggested to help clarify the assessment of...acceptable performance at -60aF. Likewise, at -60OF the NDT and DT data for these weldments marginally exceed the criteria proposed by Rolfe when the...exceed the CVN values equivalent to the 5/8 DT values required by Rolfe . The 5/8-inch dynamic-tear specimen is not recommended as a quality-control test

Impact resistance of fiber composites - Energy-absorbing mechanisms and environmental effects

NASA Technical Reports Server (NTRS)

Chamis, C. C.; Sinclair, J. H.

1985-01-01

Energy absorbing mechanisms were identified by several approaches. The energy absorbing mechanisms considered are those in unidirectional composite beams subjected to impact. The approaches used include: mechanic models, statistical models, transient finite element analysis, and simple beam theory. Predicted results are correlated with experimental data from Charpy impact tests. The environmental effects on impact resistance are evaluated. Working definitions for energy absorbing and energy releasing mechanisms are proposed and a dynamic fracture progression is outlined. Possible generalizations to angle-plied laminates are described.

Impact resistance of fiber composites: Energy absorbing mechanisms and environmental effects

NASA Technical Reports Server (NTRS)

Chamis, C. C.; Sinclair, J. H.

1983-01-01

Energy absorbing mechanisms were identified by several approaches. The energy absorbing mechanisms considered are those in unidirectional composite beams subjected to impact. The approaches used include: mechanic models, statistical models, transient finite element analysis, and simple beam theory. Predicted results are correlated with experimental data from Charpy impact tests. The environmental effects on impact resistance are evaluated. Working definitions for energy absorbing and energy releasing mechanisms are proposed and a dynamic fracture progression is outlined. Possible generalizations to angle-plied laminates are described.

Index to the Shock and Vibration Bulletins

DTIC Science & Technology

1968-02-01

125 modulus of elasticity vs tempera- ture for, 26-2-120 and nickel-chromium alloy, rupture life and creep rate, 26-2-288 Nike -Tomahawk missiles...measurement, 29-1-65 of missiles on wing of B-52, 28-1-187 of Nike -Zeus missiles, 31-1-21 prediction for large missiles, 28-4-28 on RB-66 and A3D...related to, 35-6-99 Charge weight vs crater radius, 32-2-38 Charpy tests of steel bars, 28-4-273 Chemical explosions nuclear detonation

Impact properties of irradiated HT9 from the fuel duct of FFTF

DOE Office of Scientific and Technical Information (OSTI.GOV)

Byun, Thak Sang; Lewis, W. Daniel; Toloczko, Mychailo B.

2012-02-01

This paper reports Charpy impact test data for the ACO-3 duct material (HT9) from the Fast Flux Test Facility (FFTF) and its archive material. Irradiation doses for the specimens were in the range of 3– 148 dpa and irradiation temperatures in the range of 378–504 *C. The impact tests were performed for the small V-notched Charpy specimens with dimensions of 3 * 4 * 27 mm at an impact speed of 3.2 m/s in a 25 J capacity machine. Irradiation lowered the upper-shelf energy (USE) and increased the transition temperatures significantly. The shift of ductile–brittle transition temperatures (DDBTT) was greatermore » after relatively low temperature irradiation. The USE values were in the range of 5.5–6.7 J before irradiation and decreased to the range of 2–5 J after irradiation. Lower USEs were measured for lower irradiation temperatures and specimens with T-L orientation. The dose dependences of transition temperature and USE were not significant because of the radiation effect on impact behavior nearly saturated at the lowest dose of about 3 dpa. A comparison showed that the lateral expansion of specimens showed a linear correlation with absorbed impact energy, but with large scatter in the results. Size effect was also discussed to clarify the differences in the impact property data from subsize and standard specimens as well as to provide a basis for comparison of data from different specimens. The USE and DDBTT data from different studies were compared.« less

Impact properties of irradiated HT9 from the fuel duct of FFTF

NASA Astrophysics Data System (ADS)

Byun, Thak Sang; Daniel Lewis, W.; Toloczko, Mychailo B.; Maloy, Stuart A.

2012-02-01

This paper reports Charpy impact test data for the ACO-3 duct material (HT9) from the Fast Flux Test Facility (FFTF) and its archive material. Irradiation doses for the specimens were in the range of 3-148 dpa and irradiation temperatures in the range of 378-504 °C. The impact tests were performed for the small V-notched Charpy specimens with dimensions of 3 × 4 × 27 mm at an impact speed of 3.2 m/s in a 25 J capacity machine. Irradiation lowered the upper-shelf energy (USE) and increased the transition temperatures significantly. The shift of ductile-brittle transition temperatures (ΔDBTT) was greater after relatively low temperature irradiation. The USE values were in the range of 5.5-6.7 J before irradiation and decreased to the range of 2-5 J after irradiation. Lower USEs were measured for lower irradiation temperatures and specimens with T-L orientation. The dose dependences of transition temperature and USE were not significant because of the radiation effect on impact behavior nearly saturated at the lowest dose of about 3 dpa. A comparison showed that the lateral expansion of specimens showed a linear correlation with absorbed impact energy, but with large scatter in the results. Size effect was also discussed to clarify the differences in the impact property data from subsize and standard specimens as well as to provide a basis for comparison of data from different specimens. The USE and ΔDBTT data from different studies were compared.

On impact testing of subsize Charpy V-notch type specimens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mikhail, A.S.; Nanstad, R.K.

1994-12-31

The potential for using subsize specimens to determine the actual properties of reactor pressure vessel steels is receiving increasing attention for improved vessel condition monitoring that could be beneficial for light-water reactor plant-life extension. This potential is made conditional upon, on the one hand, by the possibility of cutting samples of small volume from the internal surface of the pressure vessel for determination of actual properties of the operating pressure vessel. The plant-life extension will require supplemental surveillance data that cannot be provided by the existing surveillance programs. Testing of subsize specimens manufactured from broken halves of previously tested surveillancemore » Charpy V-notch (CVN) specimens offers an attractive means of extending existing surveillance programs. Using subsize CVN type specimens requires the establishment of a specimen geometry that is adequate to obtain a ductile-to-brittle transition curve similar to that obtained from full-size specimens. This requires the development of a correlation of transition temperature and upper-shelf toughness between subsize and full-size specimens. The present study was conducted under the Heavy-Section Steel Irradiation Program. Different published approaches to the use of subsize specimens were analyzed and five different geometries of subsize specimens were selected for testing and evaluation. The specimens were made from several types of pressure vessel steels with a wide range of yield strengths, transition temperatures, and upper-shelf energies (USEs). Effects of specimen dimensions, including depth, angle, and radius of notch have been studied. The correlation of transition temperature determined from different types of subsize specimens and the full-size specimen is presented. A new procedure for transforming data from subsize specimens was developed and is presented.« less

Effect of He implantation on fracture behavior and microstructural evolution in F82H

NASA Astrophysics Data System (ADS)

Yabuuchi, Kiyohiro; Sato, Kiminori; Nogami, Shuhei; Hasegawa, Akira; Ando, Masami; Tanigawa, Hiroyasu

2014-12-01

Reduced-activation ferritic/martensitic steels (RAFMs) are the primary candidate structural materials for fusion reactor blanket components. He bubbles, which formed under 14 MeV neutron irradiation, is considered to cause some mechanical property changes. In a previous study, Hasegawa et al. investigated the fracture behavior using Charpy impact test of He implanted F82H by 50 MeV α-particles with cyclotron accelerator, and the ductile brittle transition temperature (DBTT) was increased and intergranular fracture (IGF) was observed. However, the cause of the IGF was not shown in the previous study. To clarify the cause of the IGF of the He implanted F82H by 50 MeV α-particles with cyclotron accelerator, the microstructure of the He implanted F82H was investigated. After Charpy impact test at 233 K, the brittle fracture surface of the He implanted specimen was observed by SEM and TEM. By SEM observation, grain boundary surface was clearly observed from the bottom of the notch to a depth of about 400 μm. This area correspond to the He implanted region. On the other hand, at unimplanted region, river pattern was observed and transgranular fracture occurred. TEM observation revealed the He bubbles agglomeration at dislocations, lath boundaries, and grain boundaries, and the coarsening of precipitates on grain boundaries. IGF of the He implanted F82H was caused by both He bubbles and coarsening precipitates.

Effects of Cooling Conditions on Microstructure, Tensile Properties, and Charpy Impact Toughness of Low-Carbon High-Strength Bainitic Steels

NASA Astrophysics Data System (ADS)

Sung, Hyo Kyung; Shin, Sang Yong; Hwang, Byoungchul; Lee, Chang Gil; Lee, Sunghak

2013-01-01

In this study, four low-carbon high-strength bainitic steel specimens were fabricated by varying finish cooling temperatures and cooling rates, and their tensile and Charpy impact properties were investigated. All the bainitic steel specimens consisted of acicular ferrite, granular bainite, bainitic ferrite, and martensite-austenite constituents. The specimens fabricated with higher finish cooling temperature had a lower volume fraction of martensite-austenite constituent than the specimens fabricated with lower finish cooling temperature. The fast-cooled specimens had twice the volume fraction of bainitic ferrite and consequently higher yield and tensile strengths than the slow-cooled specimens. The energy transition temperature tended to increase with increasing effective grain size or with increasing volume fraction of granular bainite. The fast-cooled specimen fabricated with high finish cooling temperature and fast cooling rate showed the lowest energy transition temperature among the four specimens because of the lowest content of coarse granular bainite. These findings indicated that Charpy impact properties as well as strength could be improved by suppressing the formation of granular bainite, despite the presence of some hard microstructural constituents such as bainitic ferrite and martensite-austenite.

Development of a High-Strength Ultrafine-Grained Ferritic Steel Nanocomposite

NASA Astrophysics Data System (ADS)

Rahmanifard, Roohollah; Farhangi, Hasan; Novinrooz, Abdul Javad; Moniri, Samira

2013-02-01

This article describes the microstructural and mechanical properties of 12YWT oxide-dispersion-strengthened (ODS)-ferritic steel nanocomposite. According to the annealing results obtained from X-ray diffraction line profile analysis on mechanically alloyed powders milled for 80 hours, the hot extrusion at 1123 K (850 °C) resulted in a nearly equiaxed ultrafine structure with an ultimate tensile strength of 1470 MPa, yield strength of 1390 MPa, and total elongation of 13 pct at room temperature comparable with high-strength 14YWT ODS steel. Maximum total elongation was found at 973 K (600 °C) where fractography of the tensile specimen showed a fully ductile dimple feature compared with the splitting cracks and very fine dimpled structure observed at room temperature. The presence of very small particles on the wall of dimples at 1073 K (800 °C) with nearly chemical composition of the matrix alloy was attributed to the activation of the boundaries decohesion mechanism as a result of diffusion of solute atoms. The results of Charpy impact test also indicated significant improvement of transition temperature with respect to predecessor 12YWT because of the decreased grain size and more homogeneity of grain size distribution. Hence, this alloy represented a good compromise between the strength and Charpy impact properties.

Characterization of the Microstructures and the Cryogenic Mechanical Properties of Electron Beam Welded Inconel 718

NASA Astrophysics Data System (ADS)

Kwon, Soon Il; Bae, Sang Hyun; Do, Jeong Hyeon; Jo, Chang Yong; Hong, Hyun Uk

2016-02-01

The microstructures and the cryogenic mechanical properties of electron beam (EB) welds between cast and forged Inconel 718 superalloys with a thickness of 10 mm were investigated in comparison with gas tungsten arc (GTA) welds. EB welding with a heat input lower than 250 J/mm caused the formation of liquation microfissuring in the cast-side heat-affected-zone (HAZ) of the EB welds. HAZ liquation microfissuring appeared to be associated with the constitutional liquation of primary NbC carbides at the grain boundaries. Compared with the GTA welding process, the EB welding produced welds with superior microstructure, exhibiting fine dendritic structure associated with the reduction in size and fraction of the Laves phase due to the rapid cooling rate. This result was responsible for the superior mechanical properties of the EB welds at 77 K (-196 °C). Laves particles in both welds were found to provide the preferential site for the crack initiation and propagation, leading to a significant decrease in the Charpy impact toughness at 77 K (-196 °C). Crack initiation and propagation induced by Charpy impact testing were discussed in terms of the dendrite arm spacing, the Laves size and the dislocation structure ahead of the crack arisen from the fractured Laves phase in the two welds.

Effects of Ce on Inclusions, Microstructure, Mechanical Properties, and Corrosion Behavior of AISI 202 Stainless Steel

NASA Astrophysics Data System (ADS)

Cai, Guojun; Li, Changsheng

2015-10-01

The sizes and morphologies of nonmetallic inclusions, microhardness, tensile strength, and Charpy impact toughness in AISI 202 stainless steel with different Ce contents were synthetically analyzed by means of SEM, TEM, microhardness tester, and tensile and Charpy impact tests. Effects of Ce addition on the corrosion behavior were investigated in 5 wt.% H2SO4 solution for different periods of time through measuring AC impedance. The EIS measurements indicate that the steels with Ce addition exhibit higher R p values than those without Ce, which illustrates the relative resistance to uniform corrosion is accompanied by an increasing Ce addition. Ce addition to AISI 202 stainless steel improves its uniform corrosion resistance owing to metamorphic inclusions and the improvement of electrode potential in matrix. Upon increasing Ce addition, the indentation morphology of samples transfers from sink-in types to pile-up types, explaining good machinability of steels containing Ce. It is witnessed from the fracture mode that Ce refines the grain size of steels, significantly increasing the strength; in the meantime, its plasticity is improved, thereby solving the contradiction between the strength and the plasticity of steels. It is concluded that AISI 202 stainless steel with 0.016 wt.% Ce addition in the mass fraction has the best mechanical properties and the uniform corrosion resistance.

Development of impact resistant boron/aluminum composites for turbojet engine fan blades

NASA Technical Reports Server (NTRS)

Melnyk, P.; Toth, I. J.

1975-01-01

Composite fabrication was performed by vacuum press diffusion bonding by both the foil-filament array and preconsolidated monotape methods. The effect of matrix material, fiber diameter, matrix enhancement, fiber volume reinforcement, test temperature, angle-plying, notch, impact orientation, processing variables and fabrication methods on tensile strength and Charpy impact resistance are evaluated. Root attachment concepts, were evaluated by room and elevated temperature tensile testing, as well as by pendulum-Izod and ballistic impact testing. Composite resistance to foreign object damage was also evaluated by ballistic impacting of panels using projectiles of gelatin, RTV rubber and steel at various velocities, and impingement angles. A significant improvement in the pendulum impact resistance of B-Al composites was achieved.

The effect of microstructure and strength on the fracture toughness of an 18 ni, 300 grade maraging steel

NASA Technical Reports Server (NTRS)

Psioda, J. A.; Low, J. R., Jr.

1974-01-01

Methods for increasing the strength of maraging steels are discussed. An investigation was conducted to systematically vary the strength of 18 weight percent nickel, 300 grade maraging steel, to isolate any attending microstructural changes, and to study the effects of these changes on the fracture toughness of the alloy. A study aimed at determining the aging behavior of the program alloy was carried out to provide data by which to estimate yield strength. The effects of various alloying materials on the strength of the maraging steel are examined. The mechanical properties of the 300 grade maraging steel were determined by tension tests, fatigue precracked Charpy impact tests, and plane strain fracture toughness tests.

Toughness testing and high-temperature oxidation evaluations of advanced alloys for core internals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Lizhen; Pint, Bruce A.; Chen, Xiang

2016-09-16

Alloy X-750 was procured from Carpenter Technology and Bodycote in this year. An appropriate TMT was developed on Alloy 439 to obtain materials with refined grain size for property screening tests. Charpy V-notch impact tests were completed for the three ferritic steels Grade 92, Alloy 439, and 14YWT. Fracture toughness tests at elevated temperatures were completed for 14YWT. The tests will be completed for the other alloys in next fiscal year. Steam oxidation tests of the three ferritic steels, 316L, and Zr–2.5Nb have been completed. The steam tests of the Ni-based superalloys and the other austenitic stainless steels will bemore » continued and finished in next fiscal year. Performance ranking in terms of steam oxidation resistance and impact/fracture toughness of the alloys will be deduced.« less

Mechanical properties of 8Cr-2WVTa steel aged for 30 000 h

NASA Astrophysics Data System (ADS)

Tamura, M.; Shinozuka, K.; Esaka, H.; Sugimoto, S.; Ishizawa, K.; Masamura, K.

2000-12-01

A mill production plate of a reduced activation ferritic steel was thermally aged for up to 30 000 h at 400-650°C. Charpy impact tests, creep rupture tests and hardness tests were conducted. Both Vickers hardness number and creep strength decrease with aging at 650°C. The ductile-brittle transition temperature (DBTT) increases with both aging time and aging temperature. However, the DBTT does not exceed +20°C even after aging at 650°C for 30 000 h. Extracted residues and extraction replicas were analyzed metallurgically. The increase in DBTT is related mainly to the precipitation of Laves phase on the prior austenite grain boundaries. The rather low DBTT after aging is caused by the fine prior austenitic grain size.

Factors affecting miniature Izod impact strength of tungsten-fiber-metal-matrix

NASA Technical Reports Server (NTRS)

Winsa, E. A.; Petrasek, D. W.

1973-01-01

The miniature Izod and Charpy impact strengths of copper, copper-nickel, and nickel-base superalloy uniaxially reinforced with continuous tungsten fibers were studied. In most cases, impact strength was increased by increasing fiber or matrix toughness, decreasing fibermatrix reaction, increasing test temperature, hot working, or heat treating. Notch sensitivity was reduced by increasing fiber content or matrix toughness. An equation relating impact strength to fiber and matrix properties and fiber content was developed. Program results imply that tungsten alloy-fiber/superalloy matrix composites can be made with adequate impact resistance for turbine blade or vane applications.

Effect of a high helium content on the flow and fracture properties of a 9Cr martensitic steel

NASA Astrophysics Data System (ADS)

Henry, J.; Vincent, L.; Averty, X.; Marini, B.; Jung, P.

2007-08-01

An experimental characterization was conducted of helium effects on the mechanical properties of a 9Cr martensitic steel. Six sub-size Charpy samples were implanted in the notch region at 250 °C with 0.25 at.% helium and subsequently tested in 3-point bending at room temperature. Brittle fracture mode (cleavage and intergranular fracture) was systematically observed in the implanted zones of the samples. Finite element calculations of the tests, using as input the tensile properties measured on a helium loaded sample, were performed in order to determine the fracture stress at the onset of brittle crack propagation. Preliminary TEM investigations of the implantation-induced microstructure revealed a high density of small helium bubbles.

Dynamic finite element method modeling of the upper shelf energy of precracked Charpy specimens of neutron irradiated weld metal 72W

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumar, A.S.; Sidener, S.E.; Hamilton, M.L.

1999-10-01

Dynamic finite element modeling of the fracture behavior of fatigue-precracked Charpy specimens in both unirradiated and irradiated conditions was performed using a computer code, ABAQUS Explicit, to predict the upper shelf energy of precracked specimens of a given size from experimental data obtained for a different size. A tensile fracture-strain based method for modeling crack extension and propagation was used. It was found that the predicted upper shelf energies of full and half size precracked specimens based on third size data were in reasonable agreement with their respective experimental values. Similar success was achieved for predicting the upper shelf energymore » of subsize precracked specimens based on full size data.« less

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A modified split Hopkinson pressure bar for toughness tests

NASA Astrophysics Data System (ADS)

Granier, N.; Grunenwald, T.

2006-08-01

In order to characterize material toughness or to study crack arrest under dynamic loading conditions, a new testing device has been developed at CEA/Valduc. A new Split Hopkinson Pressure Bar (SHPB) has been modified: it is now composed of a single incident bar and a double transmitter bar. With this facility, a notched specimen can be loaded under three points bending conditions. Qualification tests with titanium and steel notched samples are presented. Data treatment software has been adapted to estimate the sample deflection as a function of time and treat the energy balance. These results are compared with classical Charpy experiments. Effect of various contact areas between specimen and bars are studied to point out their influence on obtained measurements. The advantage of a “knife” contact compared to a plane one is then clearly demonstrated. All results obtained with this new testing device are in good agreement and show a reduced scattering.

Evaluation of the mechanical properties of electroslag refined iron alloys

NASA Technical Reports Server (NTRS)

Bhat, G. K.

1976-01-01

Nitronic 40 (21Cr-6N-9Mn), HY-130, 9Ni-4Co, and D-6 alloys were prepared and evaluated in the form of 15.2 mm thick plates. Smooth bar tensile tests, double-edge sharp notch fracture toughness tests Charpy V-notch impact tests were conducted on appropriate heat treated specimens of the four steel plates at 22 C, -50 C, -100 C, -150 C, and -196 C. Similar material characterization, including metallographic evaluation studies on air melt and vacuum arc melt grades of same four alloy steels were conducted for comparative purposes. A cost analysis of manufacturing plates of air melt, electroslag remelt and vacuum arc remelt grades was performed. The results of both material characterization and cost analyses pointed out certain special benefits of electroslag processing iron base alloys.

Methodology for Estimating Thermal and Neutron Embrittlement of Cast Austenitic Stainless Steels During Service in Light Water Reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chopra, O. K.; Rao, A. S.

2016-04-28

Cast austenitic stainless steel (CASS) materials, which have a duplex structure consisting of austenite and ferrite phases, are susceptible to thermal embrittlement during reactor service. In addition, the prolonged exposure of these materials, which are used in reactor core internals, to neutron irradiation changes their microstructure and microchemistry, and these changes degrade their fracture properties even further. This paper presents a revision of the procedure and correlations presented in NUREG/CR-4513, Rev. 1 (Aug. 1994) for predicting the change in fracture toughness and tensile properties of CASS components due to thermal aging during service in light water reactors (LWRs) at 280–330more » °C (535–625 °F). The methodology is applicable to CF-3, CF-3M, CF-8, and CF-8M materials with a ferrite content of up to 40%. The fracture toughness, tensile strength, and Charpy-impact energy of aged CASS materials are estimated from known material information. Embrittlement is characterized in terms of room-temperature (RT) Charpy-impact energy. The extent or degree of thermal embrittlement at “saturation” (i.e., the minimum impact energy that can be achieved for a material after long-term aging) is determined from the chemical composition of the material. Charpy-impact energy as a function of the time and temperature of reactor service is estimated from the kinetics of thermal embrittlement, which are also determined from the chemical composition. The fracture toughness J-R curve for the aged material is then obtained by correlating RT Charpy-impact energy with fracture toughness parameters. A common “predicted lower-bound” J-R curve for CASS materials of unknown chemical composition is also defined for a given grade of material, range of ferrite content, and temperature. In addition, guidance is provided for evaluating the combined effects of thermal and neutron embrittlement of CASS materials used in the reactor core internal components. The correlations for estimating the change in tensile strength, including the Ramberg/Osgood parameters for strain hardening, are also described.« less

Correlation of Microstructure and Mechanical Properties of Thermomechanically Processed Low-Carbon Steels Containing Boron and Copper

NASA Astrophysics Data System (ADS)

Hwang, Byoungchul; Lee, Chang Gil; Lee, Tae-Ho

2010-01-01

The correlation of the microstructure and mechanical properties of thermomechanically processed low-carbon steels containing B and Cu was investigated in this study. Eighteen kinds of steel specimens were fabricated by varying B and Cu contents and finish cooling temperatures (FCTs) after controlled rolling, and then tensile and Charpy impact tests were conducted on them. Continuous cooling transformation (CCT) diagrams of the B-free and B-added steel specimens under nondeformed and deformed conditions were constructed by a combination of deformation dilatometry and metallographic methods. The addition of a very small amount of B remarkably decreased the transformation start temperatures near a bainite start temperature (Bs) and thus expanded the formation region of low-temperature transformation phases such as degenerate upper bainite (DUB) and lower bainite (LB) to slower cooling rates. On the other hand, a deformation in the austenite region promoted the formation of quasipolygonal ferrite (QPF) and granular bainite (GB) with an increase in transformation start temperatures. The tensile test results indicated that tensile strength primarily increased with decreasing FCT, while the yield strength did not vary much, except in some specimens. The addition of B and Cu, however, increased the tensile and yield strengths simultaneously because of the significant microstructural change occasionally affected by the FCT. The Charpy impact test results indicated that the steel specimens predominantly composed of LB and lath martensite (LM) had lower upper-shelf energy (USE) than those consisting of GB or DUB, but had nearly equivalent or rather lower ductile-to-brittle transition temperature (DBTT) in spite of the increased strength. According to the electron backscatter diffraction (EBSD) analysis data, it was confirmed that LB and LM microstructures had a relatively smaller effective grain size than GB or DUB microstructures, which enhanced the tortuosity of cleavage crack propagation, thereby resulting in a decrease in DBTT.

Metal-Arc Welded Ti-6Al-4V, Ti-4Al-4V, and Ti-5Al-2 and 1/2 SN Titanium Alloys

DTIC Science & Technology

1959-05-01

x . 7 8 8 - x 2 . 1 2 i n c h ) V n o t c h Charpy i m p a c t spec imen . MATERIALS COHN* .25 . 2 3 The m a t e r i a l s u s e d d...i e d V n o t c h Charpy i m p a c t spec imen i n a s t a n d a r d i m p a c t machine w i th anvi l s modified so t h a t the center...of percussion of the pendulum coincided with the center of the impact specimen, This FIGURE 3: SUBSIZE T E N S I L E SPECIMEN FIGURE 4

Microstructure examination of Fe-14Cr ODS ferritic steels produced through different processing routes

NASA Astrophysics Data System (ADS)

Oksiuta, Z.; Hosemann, P.; Vogel, S. C.; Baluc, N.

2014-08-01

Various thermo-mechanical treatments were applied to refine and homogenise grain size and improve mechanical properties of hot-isostatically pressed (HIP) 14%Cr ODS ferritic steel. The grain size was reduced, improving mechanical properties, tensile strength and Charpy impact, however bimodal-like distribution was also observed. As a result, larger, frequently elongated grains with size above 1 μm and refined, equiaxed grains with a diameter ranging from 250 to 500 nm. Neutron diffraction measurements revealed that for HIP followed by hydrostatic extrusion material the strongest fiber texture was observed oriented parallel to the extrusion direction. In comparison with hot rolling and hot pressing methods, this material exhibited promising mechanical properties: the ultimate tensile strength of 1350 MPa, yield strength of 1280 MPa, total elongation of 21.7% and Charpy impact energy of 5.8 J. Inferior Charpy impact energy of ∼3.0 J was measured for HIP and hot rolled material, emphasising that parameters of this manufacturing process still have to be optimised. As an alternative manufacturing route, due to the uniform microstructure and simplicity of the process, hot pressing might be a promising method for production of smaller parts of ODS ferritic steels. Besides, the ductile-to-brittle transition temperature of all thermo-mechanically treated materials, in comparison with as-HIPped ODS steel, was improved by more than 50%, the transition temperature ranging from 50 to 70 °C (323 and 343 K) remains still unsatisfactory.

Improvement of Anisotropic Mechanical Behavior by Sulfide Control in Quenched and Tempered 4340 Steel

NASA Astrophysics Data System (ADS)

Jung, Jae-Hoon; Shin, Jung-Ho; Lee, Seok-Jae

2015-07-01

The anisotropic mechanical behavior of quenched and tempered 4340 steel with different Ca contents was investigated by means of a macro/micrograph analysis, Charpy impact test, and rotating bending fatigue test. The 4340 steel with Ca added formed small spherical (Ca,Mn)S inclusions and effectively decreased both the inclusion size and the aspect ratio (length to width) of the MnS inclusions as compared to the Ca-free 4340 steel. The anisotropic impact value and fatigue strength were effectively improved due to the Ca addition that prevented the growth of MnS inclusions, which provided increased resistance against deformation to maintain a spherical shape because the elongated MnS inclusions acted as a crack propagation path and promoted the crack propagation due to higher stress concentrations.

High temperature compounds for turbine vanes

NASA Technical Reports Server (NTRS)

Rhodes, W. H.; Cannon, R. M., Jr.

1972-01-01

Fabrication and microstructure control studies were conducted on SiC, Si3N4, and composites based on these compounds. Charpy mode impact testing to 2400 F established that beta-spodumene, lithium aluminum silicate, coated Si3N4, Si3N4 derived from alpha-Si3N4 powder, and SiC containing 5-25 v/o chopped C fibers had the most promising strengths. Several other composite systems had excellent microstructures and could prove interesting materials in the future. Stress-rupture testing on Si3N4 established that increasing 2000 F - 100 hour strengths were obtained for increasing grain size to at least 5 micrometers, increasing density and possibly increasing phase purity. These parameters became less important at 2400 F where it is thought a grain boundary phase controls strength.

Influence of Texture on Impact Toughness of Ferritic Fe-20Cr-5Al Oxide Dispersion Strengthened Steel

PubMed Central

Sánchez-Gutiérrez, Javier; Chao, Jesus; Vivas, Javier; Galvez, Francisco; Capdevila, Carlos

2017-01-01

Fe-based oxide dispersion strengthened (ODS) steels are oriented to applications where high operating temperatures and good corrosion resistance is paramount. However, their use is compromised by their fracture toughness, which is lower than other competing ferritic-martenstic steels. In addition, the route required in manufacturing these alloys generates texture in the material, which induces a strong anisotropy in properties. The V-notched Charpy tests carried out on these alloys, to evaluate their impact toughness, reveal that delaminations do not follow the path that would be expected. There are many hypotheses about what triggers these delaminations, but the most accepted is that the joint action of particles in the grain boundaries, texture induced in the manufacturing process, and the actual microstructure of these alloys are responsible. In this paper we focused on the actual role of crystallographic texture on impact toughness in these materials. A finite elements simulation is carried out to solely analyze the role of texture and eliminate other factors, such as grain boundaries and the dispersed particles. The work allows us to conclude that crystallographic texture plays an important role in the distribution of stresses in the Charpy specimens. The observed delaminations might be explained on the basis that the crack in the grain, causing the delamination, is directly related to the shear stresses τ12 on both sides of the grain boundary, while the main crack propagation is a consequence of the normal stress to the crack. PMID:28773104

Process optimization for diffusion bonding of tungsten with EUROFER97 using a vanadium interlayer

NASA Astrophysics Data System (ADS)

Basuki, Widodo Widjaja; Aktaa, Jarir

2015-04-01

Solid-state diffusion bonding is a selected joining technology to bond divertor components consisting of tungsten and EUROFER97 for application in fusion power plants. Due to the large mismatch in their coefficient of thermal expansions, which leads to serious thermally induced residual stresses after bonding, a thin vanadium plate is introduced as an interlayer. However, the diffusion of carbon originated from EUROFER97 in the vanadium interlayer during the bonding process can form a vanadium carbide layer, which has detrimental influences on the mechanical properties of the joint. For optimal bonding results, the thickness of this layer and the residual stresses has to be decreased sufficiently without a significant reduction of material transport especially at the vanadium/tungsten interface, which can be achieved by varying the diffusion bonding temperature and duration. The investigation results show that at a sufficiently low bonding temperature of 700 °C and a bonding duration of 4 h, the joint reaches a reasonable high ductility and toughness especially at elevated test temperature of 550 °C with elongation to fracture of 20% and mean absorbed Charpy impact energy of 2 J (using miniaturized Charpy impact specimens). The strength of the bonded materials is about 332 MPa at RT and 291 MPa at 550 °C. Furthermore, a low bonding temperature of 700 °C can also help to avoid the grain coarsening and the alteration of the grain structure especially of the EUROFER97 close to the bond interface.

On the effects of irradiation and helium on the yield stress changes and hardening and non-hardening embrittlement of ˜8Cr tempered martensitic steels: Compilation and analysis of existing data

NASA Astrophysics Data System (ADS)

Yamamoto, Takuya; Odette, G. Robert; Kishimoto, Hirotatsu; Rensman, Jan-Willem; Miao, Pifeng

2006-09-01

Data on irradiation hardening and embrittlement of 8-10Cr normalized and tempered martensitic steel (TMS) alloys has been compiled from the literature, including results from neutron, spallation proton (SP) and He-ion (HI) irradiations. Limitations of this database are briefly described. Simple, phenomenological-empirical fitting models were used to assess the dose (displacement-per-atom, dpa), irradiation temperature ( Ti) and test temperature ( Tt) dependence of yield stress changes (Δ σy), as well as the corresponding dependence of sub-sized Charpy V-notch impact test transition temperature shifts (Δ Tc). The Δ σy are generally similar for SP and neutron irradiations, with very high and low helium to dpa ratios, respectively. Further, the Δ σy trends were found to be remarkably consistent with the Ti and dpa hardening-dependence of low alloy steels irradiated at much lower doses. The similar Ti and (low) dose dependence of Δ σy and Δ Tc, as well as an analysis of paired Δ Tc-Δ σy datasets, show that embrittlement is typically dominated by a hardening mechanism below about 400 °C. However, the corresponding hardening-Charpy shift coefficient, Cc = Δ Tc/Δ σy ≈ 0.38 ± 0.18 °C/MPa is lower than that for the fracture toughness reference temperature, T0, with Δ T0/Δ σy ≈ 0.58 ± 0.1 °C/MPa, indicating that sub-sized Charpy tests provide non-conservative estimates of embrittlement. The Cc increases at Ti > 400 °C, and Δ Tc > 0 are sometimes observed in association with Δ σy ⩽ 0, indicative of a non-hardening embrittlement (NHE) contribution. Analysis of limited data on embrittlement due to thermal aging supports this conclusion, and we hypothesize that the NHE regime may be shifted to lower temperatures by radiation enhanced diffusion. Possible effects of helium on embrittlement for Ti between 300 and 400 °C are also assessed based on observed trends in Cc. The available data is limited, scattered, and potentially confounded. However, collectively the database suggests that there is a minimal NHE due to helium up to several hundred appm. However, a contribution of helium to NHE appears to emerge at higher helium concentrations, estimated to be more than 400-600 appm. This is accompanied by a transition from transgranular cleavage (TGC) to intergranular fracture (IGF). IGF generally occurs only at high Δ σy. Synergistic combinations of large Δ σy and severe NHE, due to helium weakening of grain boundaries, could lead to very large transition temperature shifts in first wall and blanket structures at fusion spectrum dose levels above 50-75 dpa and in SP irradiations at much lower doses.

Further Charpy impact test results of low activation ferritic alloys, irradiated at 430{degrees}C to 67 dpa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schubert, L.E.; Hamilton, M.L.; Gelles, D.S.

1997-04-01

Miniature CVN specimens of four ferritic alloys, GA3X, F82H, GA4X and HT9, have been impact tested following irradiation at 430{degrees}C to 67 dpa. Comparison of the results with those of the previously tested lower dose irradiation condition indicates that the GA3X and F82H alloys, two primary candidate low activation alloys, exhibit virtually identical behavior following irradiation at 430{degrees}C to {approximately}67 dpa and at 370{degrees}C to {approximately}15 dpa. Very little shift is observed in either DBTT or USE relative to the unirradiated condition. The shifts in DBTT and USE observed in both GA4X and HT9 were smaller after irradiation at 430{degrees}Cmore » to {approximately}67 dpa than after irradiation at 370{degrees}C to {approximately}15 dpa.« less

Influence of Chemical Composition and Heat Treatment Condition on Impact Toughness of 15Cr Ferritic Creep Resistant Steel

NASA Astrophysics Data System (ADS)

Toda, Yoshiaki; Tohyama, Hideaki; Kushima, Hideaki; Kimura, Kazuhiro; Abe, Fujio

Influences of chemical compositions, heat treatment and microstructure on impact toughness of 15Cr ferritic steel have been investigated. Charpy impact values of the furnace cooled steels were lower than 15J/cm2 at room temperature independent of chemical compositions. Drastic improvement in impact toughness has been attained by controlling the carbon and nitrogen contents, by the addition of nickel and by the increase in cooling rate after annealing. However, the effect of nickel on impact toughness strongly depends on carbon and nitrogen contents. Improvement in impact toughness of the 15Cr ferritic steel has not been explained by individual microstructural factors of grain size, distribution of precipitates, volume fraction of martensitic phase. It has been supposed that the increase in Charpy impact toughness of the 15Cr ferritic steel was attained by improvement in toughness of ferrite matrix itself.

Fracture toughness measurements of three titanium alloy extrusions

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeSisto, T.S.

1973-07-01

Plane strain static K/sub Ic/ and dynamic Kid measurements were obtained on 3-in. dia. titanium alloy extrusions which received a 5.9: 1 reduction followed by air cooling. The alloys investigated were Ti-6Al--6V--2Sn, Ti--8Mo-- 8V--2Fe--3Al, and Ti-- 11.5Mo-6Zr-4.5Sn (Beta III). Compact tension specimens were used to obtain K/sub Ic/ measurements and precracked standard Charpy V- notched specimens were used to obtain Kid measurements. The highest K/sub Ic/ and K /sub Id/ values were obtained from the Beta III extrusion while the lowest K/sub Ic/ and K/sub Id/ values were obtained for the Ti-8Mo--8V--2Fe -- 3Al extrusion. Good agreement was found tomore » exist between K/sub Ic/ values obtained from precracked Charpy V-notch specimens and compact tension specimens. (auth)« less

Clean Cast Steel Technology: Effect of Micro-porosity on Tensile and Charpy Properties of Four Cast Steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Griffin, John, A.; Bates, Charles, E.

2005-09-19

The effect of these large shrink cavities on mechanical properties could be easily calculated using well established engineering formulas. Over the years, increases in computational and metallurgical resources have allowed the modeler to improve accuracy and increase the complexity of numerical predictors. An accurate prediction of micro-porosity, not observable using conventional radiographic techniques, and an engineering understanding of the effect on mechanical properties would give a designer confidence in using a more efficient casting design and a lower safety factor. This will give castings an additional design advantage. The goal of this project is to provide current and future modelers/designersmore » with a tensile and Charpy property dataset for validation of micro-porosity predictors. The response of ultimate strength, elongation, and reduction in area to micro-porosity was very similar in all four alloys. Ultimate strength was largely unaffected by tensile fracture surface porosity until values of about 25% were reached and decreased linearly with increasing values. Elongation and reduction in area decreased sharply after less than 5% fracture surface porosity. Niyama values of about 0.7 were produced sound material and acceptable tensile properties. Ultrasonic velocities of 0.233 in/usec and higher produced acceptable tensile properties. Metallographic examination revealed a ratio of 4-6 to 1 in fracture surface porosity to metallographic porosity. Charpy impact properties were largely unaffected by the microporosity concentrations examined in this study and did not correlate to either Niyama values, fracture surface porosity, or metallographic porosity.« less

Low temperature mechanical properties, fractographic and metallographic evaluation of several alloy steels

NASA Technical Reports Server (NTRS)

Montano, J. W.

1973-01-01

The mechanical properties are presented of alloy steels, 4130, 4140, 4340, 6150, and 8740. Test specimens were manufactured from approximately 1.00 inch (2.54 cm) diameter bar stock which had been heat treated to two different hardness levels. The following mechanical tests were performed at temperatures of 80 F (+26.7 C), 0 F (-17.8 C), -100 F (-73 C), and -200 F (-129 C): (1) tensile test (Ultimate, yield, modulus, elongation, and reduction of area), (2) notched tensile test, (3) charpy V-notched impact test (impact energy), and (4) double shear strength test (ultimate and yield). The test data indicate excellent tensile strength, notched/unnotched tensile ratios, ductility, impact, and shear properties at all test temperatures, except at -200 F (-129 C) where the impact strength of the higher strength group of alloy steels, 4130 (Rc-37) and 4140 (Rc-44) decreased to approximately 9 ft. lbs. (12 joules) and 6 ft. lbs. (8 joules), respectively. Chemical, metallographic, and fractographic analyses were also performed to evaluate microstructure, microhardness and the effect of decrease in temperature on the ductile to brittle failure transition.

Magnetic-Force-Assisted Straightening of Bent Mild Steel Strip by Laser Irradiation

NASA Astrophysics Data System (ADS)

Dutta, Polash P.; Kalita, Karuna; Dixit, Uday S.; Liao, Hengcheng

2017-12-01

This study proposes a technique to straighten bent metallic strips with magnetic-force-assisted laser irradiation. Experiments were conducted for three different types of mechanically-bent mild strips. The first type was bent strips without any heat treatment. The second type was stress-relieved and third type was subcritical-annealed bent strips. These strips were straightened following different schemes of laser irradiation sequence to understand the performance of straightening. A parametric study was conducted by varying laser power and scanning speed. Micro-hardness, tensile test, Charpy impact test and microstructure after straightening were also studied. Different scanning schemes provided different microstructures and mechanical properties. Any serious deterioration in the quality of straightened strips was not noticed. Overall, subcritical-annealed bent strips provided the best performance in straightening. The proposed straightening scheme has potential of becoming an industrial practice.

Influence of structural parameters on the tendency of VVER-1000 reactor pressure vessel steel to temper embrittlement

NASA Astrophysics Data System (ADS)

Gurovich, B.; Kuleshova, E.; Zabusov, O.; Fedotova, S.; Frolov, A.; Saltykov, M.; Maltsev, D.

2013-04-01

In this paper the influence of structural parameters on the tendency of steels to reversible temper embrittlement was studied for assessment of performance properties of reactor pressure vessel steels with extended service life. It is shown that the growth of prior austenite grain size leads to an increase of the critical embrittlement temperature in the initial state. An embrittlement heat treatment at the temperature of maximum manifestation of temper embrittlement (480 °C) shifts critical embrittlement temperature to higher values due to the increase of the phosphorus concentration on grain boundaries. There is a correlation between phosphorus concentration on boundaries of primary austenite grains and the share of brittle intergranular fracture (that, in turn, depends on impact test temperature) in the fracture surfaces of the tested Charpy specimens.

Loss of Ductility Caused by AlN Precipitation in Hadfield Steel

NASA Astrophysics Data System (ADS)

Radis, Rene; Schlacher, Christian; Kozeschnik, Ernst; Mayr, Peter; Enzinger, Norbert; Schröttner, Hartmuth; Sommitsch, Christof

2012-04-01

Two modified X120Mn12 Hadfield steels, differing in the amount of the alloying elements Al and N, are analyzed with respect to AlN precipitation and its effects on ductility. Charpy impact tests are performed, demonstrating the loss of ductility in the one grade containing a high density of AlN precipitates. The characterization of the precipitates is carried out by high-resolution scanning electron microscopy (HRSEM). Depending on chemical composition, primary and secondary AlN precipitates are detected on prior austenite grain boundaries and within the bulk volume. The experimental observations are confirmed by thermokinetic simulations, using the software package MatCalc (Vienna University of Technology, Vienna, Austria).

Microstructure evolution and mechanical properties degradation of HPNb alloy after a five-year service

NASA Astrophysics Data System (ADS)

Guo, Jingfeng; Cao, Tieshan; Cheng, Congqian; Meng, Xianming; Zhao, Jie

2018-04-01

The microstructure and mechanical properties of ethylene cracking furnace tube (HPNb alloy) are investigated by scanning electronic microscopy (SEM), tensile tests and Charpy impact tests at room temperature, tensile tests and creep tests at high temperature in this paper. The primary carbides of HPNb alloy coarsened and formed a continuous network after a five-year service. Furthermore, a lot of fine secondary carbides precipitated in the dendrite interior. The primary carbides M7C3 and NbC transformed into M23C6 and G phase after service, respectively. The furnace tube after service exhibits higher yield strength, lower tensile strength, worse ductility and toughness than as-cast tube at room temperature. At high temperature, the tensile strength and yield strength of service tube are higher than as-cast tube, but its tensile elongation is lower. The creep strength of HPNb alloy at high temperature decreases after a five-year service. Both microstructure and mechanical properties of ethylene cracking furnace tube have deteriorated after a five-year service.

Mechanical and Microstructural Characterization of a New Corrosion Resistant Stainless Steel

NASA Astrophysics Data System (ADS)

Voiculescu, I.; Geantă, V.; Stefănoiu, R.; Cotruţ, C.; Ciocoiu, R.; Ionescu, M.

2018-06-01

The paper investigates the manner in which the chemical composition and delivery status of a new type of stainless steel, highly alloyed with Ni and Cr, affect mechanical properties, microstructure and corrosion resistance. The results obtained during the mechanical test (tensile, compression, Charpy test and micro-hardness) have revealed promising values. During the corrosion test, the preferential attack of the reagent (Aqua regia) located on the grain boundaries, inclusions or polyhedral precipitates have been observed. On the corroded surfaces, some localized pitting effects on grain boundaries have been revealed. The analyses of the parameter values recorded during the corrosion test revealed that the corrosion current density had a low value, comparable to that of other specific types of stainless steels. The actual Icorr (1.089 µA/cm2) value measured for the experimental alloy proves good resistance to corrosion in 3% NaCl saline solution. The estimated rate of corrosion presented acceptable values (0.011 mm/year).

30 CFR 77.403-1 - Mobile equipment; rollover protective structures (ROPS).

Code of Federal Regulations, 2013 CFR

2013-07-01

... professional engineer that: (1) The ROPS complies with the Society of Automotive Engineers (SAE) Standard J 397.... Steel used in the ROPS must have capability to perform at 0 °F., or exhibit Charpy V-notch impact...

30 CFR 77.403-1 - Mobile equipment; rollover protective structures (ROPS).

Code of Federal Regulations, 2014 CFR

2014-07-01

... professional engineer that: (1) The ROPS complies with the Society of Automotive Engineers (SAE) Standard J 397.... Steel used in the ROPS must have capability to perform at 0 °F., or exhibit Charpy V-notch impact...

30 CFR 77.403-1 - Mobile equipment; rollover protective structures (ROPS).

Code of Federal Regulations, 2012 CFR

2012-07-01

... professional engineer that: (1) The ROPS complies with the Society of Automotive Engineers (SAE) Standard J 397.... Steel used in the ROPS must have capability to perform at 0 °F., or exhibit Charpy V-notch impact...

A New Paradigm for Designing High-Fracture-Energy Steels

NASA Astrophysics Data System (ADS)

Fine, M. E.; Vaynman, S.; Isheim, D.; Chung, Y.-W.; Bhat, S. P.; Hahin, C. H.

2010-12-01

The steels used for structural and other applications ideally should have both high strength and high toughness. Most high-strength steels contain substantial carbon content that gives poor weldability and toughness. A theoretical study is presented that was inspired by the early work of Weertman on the effect that single or clusters of solute atoms with slightly different atom sizes have on dislocation configurations in metals. This is of particular interest for metals with high Peierls stress. Misfit centers that are coherent and coplanar in body-centered cubic (bcc) metals can provide sufficient twisting of nearby screw dislocations to reduce the Peierls stress locally and to give improved dislocation mobility and hence better toughness at low temperatures. Therefore, the theory predicts that such nanoscale misfit centers in low-carbon steels can give both precipitation hardening and improved ductility and fracture toughness. To explore the validity of this theory, we measured the Charpy impact fracture energy as a function of temperature for a series of low-carbon Cu-precipitation-strengthened steels. Results show that an addition of 0.94 to 1.49 wt pct Cu and other accompanying elements results in steels with high Charpy impact energies down to cryogenic temperatures (198 K [-75 °C]) with no distinct ductile-to-brittle transition. The addition of 0.1 wt pct Ti results in an additional increase in impact toughness, with Charpy impact fracture energies ranging from 358 J (machine limit) at 248 K (-25 °C) to almost 200 J at 198 K (-75 °C). Extending this concept of using coherent and coplanar misfit centers to decrease the Peierls stress locally to other than bcc iron-based systems suggests an intriguing possibility of developing ductile hexagonal close-packed alloys and intermetallics.

Ultrahigh Charpy impact toughness (~450J) achieved in high strength ferrite/martensite laminated steels

PubMed Central

Cao, Wenquan; Zhang, Mingda; Huang, Chongxiang; Xiao, Shuyang; Dong, Han; Weng, Yuqing

2017-01-01

Strength and toughness are a couple of paradox as similar as strength-ductility trade-off in homogenous materials, body-centered-cubic steels in particular. Here we report a simple way to get ultrahigh toughness without sacrificing strength. By simple alloying design and hot rolling the 5Mn3Al steels in ferrite/austenite dual phase temperature region, we obtain a series of ferrite/martensite laminated steels that show up-to 400–450J Charpy V-notch impact energy combined with a tensile strength as high as 1.0–1.2 GPa at room temperature, which is nearly 3–5 times higher than that of conventional low alloy steels at similar strength level. This remarkably enhanced toughness is mainly attributed to the delamination between ferrite and martensite lamellae. The current finding gives us a promising way to produce high strength steel with ultrahigh impact toughness by simple alloying design and hot rolling in industry. PMID:28150692

Ultrahigh Charpy impact toughness (~450J) achieved in high strength ferrite/martensite laminated steels

NASA Astrophysics Data System (ADS)

Cao, Wenquan; Zhang, Mingda; Huang, Chongxiang; Xiao, Shuyang; Dong, Han; Weng, Yuqing

2017-02-01

Strength and toughness are a couple of paradox as similar as strength-ductility trade-off in homogenous materials, body-centered-cubic steels in particular. Here we report a simple way to get ultrahigh toughness without sacrificing strength. By simple alloying design and hot rolling the 5Mn3Al steels in ferrite/austenite dual phase temperature region, we obtain a series of ferrite/martensite laminated steels that show up-to 400-450J Charpy V-notch impact energy combined with a tensile strength as high as 1.0-1.2 GPa at room temperature, which is nearly 3-5 times higher than that of conventional low alloy steels at similar strength level. This remarkably enhanced toughness is mainly attributed to the delamination between ferrite and martensite lamellae. The current finding gives us a promising way to produce high strength steel with ultrahigh impact toughness by simple alloying design and hot rolling in industry.

Study of the Effects of High Temperatures on the Engineering Properties of Steel 42CrMo4

NASA Astrophysics Data System (ADS)

Brnic, Josip; Turkalj, Goran; Canadija, Marko; Lanc, Domagoj; Brcic, Marino

2015-02-01

The paper presents and analyzes the experimental results of the effect of elevated temperatures on the engineering properties of steel 42CrMo4. Experimental data relating to the mechanical properties of the material, the creep resistance as well as Charpy impact energy. Temperature dependence of the mentioned properties is also shown. Some of creep curves were simulated using rheological models and an analytical equation. Finally, an assessment of fracture toughness was made that was based on experimentally determined Charpy impact energy. Based on the obtained results it is visible that the tensile strength (617 MPa) and yield strength (415 MPa) have the highest value at the room temperature while at the temperature of 700 °C (973 K) these values significantly decrease. This steel can be considered resistant to creep at 400 °C (673 K), but at higher temperatures this steel can be subjected to low levels of stress in a shorter time.

Low temperature embrittlement behaviour of different ferritic-martensitic alloys for fusion applications

NASA Astrophysics Data System (ADS)

Rieth, M.; Dafferner, B.

1996-10-01

In the last few years a lot of different low activation CrWVTa steels have been developed world-wide. Without irradiation some of these alloys show clearly a better low temperature embrittlement behaviour than commercial CrNiMoV(Nb) alloys. Within the MANITU project a study was carried out to compare, prior to the irradiation program, the embrittlement behaviour of different alloys in the unirradiated condition performing instrumented Charpy impact bending tests with sub-size specimens. The low activation materials (LAM) considered were different OPTIFER alloys (Forschungszentrum Karlsruhe), F82H (JAERI), 9Cr2WVTa (ORNL), and GA3X (PNL). The modified commercial 10-11% CrNiMoVNb steels were MANET and OPTIMAR. A meaningful comparison between these alloys could be drawn, since the specimens of all materials were manufactured and tested under the same conditions.

Mechanical and Microstructural Effects of Thermal Aging on Cast Duplex Stainless Steels by Experiment and Finite Element Method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwarm, Samuel C.; Mburu, Sarah N.; Kolli, Ratna P.

Cast duplex stainless steel piping in light water nuclear reactors expe- rience thermal aging embrittlement during operational service. Interest in extending the operational life to 80 years requires an increased understanding of the microstructural evolution and corresponding changes in mechanical behavior. We analyze the evolution of the microstructure during thermal aging of cast CF-3 and CF-8 stainless steels using electron microscopy and atom probe tomography. The evolution of the mechanical properties is measured concurrently by mechanical methods such as tensile tests, Charpy V-notch tests, and instrumented nanoinden- tation. A microstructure-based finite element method model is developed and uti- lized inmore » conjunction with the characterization results in order to correlate the local stress-strain effects in the microstructure with the bulk measurements. This work is supported by the DOE Nuclear Energy University Programs (NEUP), contract number DE-NE0000724.« less

Dynamic Mechanical Properties and Fracture Surface Morphologies of Core-Shell Rubber (CSR) Toughened Epoxy at Liquid Nitrogen (Ln2) Temperatures

NASA Technical Reports Server (NTRS)

Wang, J.; Magee, D.; Schneider, J. A.

2009-01-01

The dynamic mechanical properties and fracture surface morphologies were evaluated for a commercial epoxy resin toughened with two types of core-shell rubber (CSR) toughening agents (Kane Ace(Registered TradeMark) MX130 and MX960). The impact resistance (R) was evaluated by the resulting breaking energy measured in Charpy impact tests conducted on an instrumented drop tower. The resulting fracture surface morphologies were examined using Scanning Electron Microscopy (SEM). Fractographic observations of the CSR toughened epoxy tested at ambient temperature, showed a fracture as characterized by slender dendrite textures with large voids. The increasing number of dendrites and decreasing size of scale-like texture with more CSR particles corresponded with increased R. As the temperature decreased to Liquid Nitrogen (LN 2), the fracture surfaces showed a fracture characterized by a rough, torn texture containing many river markings and deep furrows.

Mechanical properties of nanocrystalline cobalt

NASA Astrophysics Data System (ADS)

Karimpoor, Amir A.; Erb, Uwe

2006-05-01

Due to their excellent wear and corrosion properties, nanocrystalline cobalt and several cobalt alloys made by electrodeposition are currently being developed as environmentally benign replacement coatings for hard chromium electrodeposits. The focus of this study is on the mechanical properties of nanocrystalline cobalt, which are currently not well understood. A comparison is presented for hardness, tensile properties, Charpy impact properties and fracture surface analysis of both nanocrystalline (grain size: 12 nm) and conventional polycrystalline (grain size: 4.8 m) cobalt. It is shown that the hardness and tensile strength of nanocrystalline cobalt is 2-3 times higher than for polycrystalline cobalt. However, in contrast to other nanocrystalline materials tested previously, nanocrystalline cobalt retains considerable ductility with elongation to fracture values up to 7%.

Tensile and impact properties of General Atomics 832864 heat of V-4Cr-4Ti alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsai, H.; Nowicki, L.J.; Gazda, J.

A 1300-kg heat of V-4Cr-4Ti alloy was procured by General Atomics (GA) for the DIII-D radiative divertor program. To determine the mechanical properties of this alloy, tensile and Charpy tests were conducted on specimens prepared from pieces of 4.8-mm-thick as-rolled plates, a major product form for the DIII-D application. The tensile tests were conducted at three temperatures, 26, 280 and 380 C, the last two being the anticipated peak temperatures during DIII-D boronization and postvent bake-out, respectively. Results from these tests show that the tensile and impact properties of the 832864 heat are comparable to those of the other smallermore » V-(4-5)Cr-(4-5)Ti alloy heats previously developed by the US Fusion Materials Program and that scale-up of vanadium alloy production can be successfully achieved as long as reasonable process control is implemented.« less

Influence of long-time stress relief treatments on the dynamic fracture toughness properties of ASME SA508 C1 2a and ASME SA533 GR B C12 pressure vessel steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Logsdon, W.A.

1982-03-01

Dynamic fracture toughness tests were performed on materials which had been subjected to one of three long-time post weld type stress relief heat treatments: 48 hours at 1000/degree/F (538/degree/C), 24 hours at 1125/degree/F (607/degree/C), and 48 hours at 1125/degree/F (607/degree/C). Linear elastic K/sub Id/ results were obtained at low temperatures while J-integral techniques were utilized to evaluate dynamic fracture toughness over the transition and upper shelf temperature ranges. Tensile, Charpy impact, and drop weight nil-ductility transition tests as well as room temperature, air environment fatigue crack growth rate tests (SA508 Cl 2a only) were also performed. The fracture toughness ofmore » both materials exceeded the ASME specified minimum reference toughness K/sub IR/ curve. 17 refs.« less

Delamination Fracture Related to Tempering in a High-Strength Low-Alloy Steel

NASA Astrophysics Data System (ADS)

Yan, Wei; Sha, Wei; Zhu, Lin; Wang, Wei; Shan, Yi-Yin; Yang, Ke

2010-01-01

The delamination or splitting of mechanical test specimens of rolled steel plate is a phenomenon that has been studied for many years. In the present study, splitting during fracture of tensile and Charpy V-notch (CVN) test specimens is examined in a high-strength low-alloy plate steel. It is shown that delamination did not occur in test specimens from plate in the as-rolled condition, but was severe in material tempered in the temperature range 500 °C to 650 °C. Minor splitting was seen after heating to 200 °C, 400 °C, and 700 °C. Samples that had been triple quenched and tempered to produce a fine equiaxed grain size also did not exhibit splitting. Microstructural and preferred orientation studies are presented and are discussed as they relate to the splitting phenomenon. It is concluded that the elongated as-rolled grains and grain boundary embrittlement resulting from precipitates (carbides and nitrides) formed during reheating were responsible for the delamination.

The Effect of Tempering Process on Microstructural Characteristics and Mechanical Properties of Induction Bend Pipe

NASA Astrophysics Data System (ADS)

Yu, Hao; Zhou, Tao

The heat treatment during manufacturing process of induction bend pipe had been simulated. The evolutions of ferrite, M/A island and substructure after tempering at 500 700 °C were characterized by means of optical microscopy, positron annihilation technique, SEM, TEM, XRD and EBSD. The mechanical performance was evaluated by tensile test, Charpy V-notch impact test (-20 °C) and Vickers hardness test (10 kgf). Microstructure observations showed that fine and homogenous M/A islands as well as dislocation packages in quasi-polygonal ferrite matrix after tempering at 600 650 °C generated optimal combination of strength and toughness. After tempering at 700 °C, the yield strength decreased dramatically. EBSD analysis indicated that the effective grain size diminished with the tempering temperature increasing. It could cause more energy cost during microcrack propagation process with subsequent improvement in impact toughness. Dislocation analysis suggested that the decrease and pile-up of dislocation benefited the combination of strength and toughness.

Effects of aluminum and copper chill on mechanical properties and microstructures of Cu-Zn-Al alloys with sand casting

NASA Astrophysics Data System (ADS)

Ardhyananta, Hosta; Wibisono, Alvian Toto; Ramadhani, Mavindra; Widyastuti, Farid, Muhammad; Gumilang, Muhammad Shena

2018-04-01

Cu-Zn-Al alloy is one type of brass, which has high strength and high corrosion resistant. It has been applied on ship propellers and marine equipment. In this research, the addition of aluminum (Al) with variation of 1, 2, 3, 4% aluminum to know the effect on mechanical properties and micro structure at casting process using a copper chill and without copper chill. This alloy is melted using furnace in 1100°C without holding. Then, the molten metal is poured into the mold with copper chill and without copper chill. The speciment of Cu-Zn-Al alloy were chracterized by using Optical Emission Spectroscopy (OES), Metallography Test, X-Ray Diffraction (XRD), Hardness Test of Rockwell B and Charpy Impact Test. The result is the addition of aluminum and the use of copper chill on the molds can reduce the grain size, increases the value of hardness and impact.

Mechanical Characteristics of Submerged Arc Weldment in API Gas Pipeline Steel of Grade X65

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hashemi, S. H.; Mohammadyani, D.

The mechanical properties of submerged arc weldment (SAW) in gas transportation pipeline steel of grade API X65 (65 ksi yield strength) were investigated. This steel is produced by thermo mechanical control rolled (TMC), and is largely used in Iran gas piping systems and networks. The results from laboratory study on three different regions; i.e. base metal (BM), fusion zone (FZ) and heat affected zone (HAZ) were used to compare weldment mechanical characteristics with those specified by API 5L (revision 2004) standard code. Different laboratory experiments were conducted on test specimens taken from 48 inch outside diameter and 14.3 mm wallmore » thickness gas pipeline. The test results showed a gradient of microstructure and Vickers hardness data from the centerline of FZ towards the unaffected MB. Similarly, lower Charpy absorbed energy (compared to BM) was observed in the FZ impact specimens. Despite this, the API specifications were fulfilled in three tested zones, ensuring pipeline structural integrity under working conditions.« less

Atom probe tomography characterizations of high nickel, low copper surveillance RPV welds irradiated to high fluences

NASA Astrophysics Data System (ADS)

Miller, M. K.; Powers, K. A.; Nanstad, R. K.; Efsing, P.

2013-06-01

The Ringhals Units 3 and 4 reactors in Sweden are pressurized water reactors (PWRs) designed and supplied by Westinghouse Electric Company, with commercial operation in 1981 and 1983, respectively. The reactor pressure vessels (RPVs) for both reactors were fabricated with ring forgings of SA 508 class 2 steel. Surveillance blocks for both units were fabricated using the same weld wire heat, welding procedures, and base metals used for the RPVs. The primary interest in these weld metals is because they have very high nickel contents, with 1.58 and 1.66 wt.% for Unit 3 and Unit 4, respectively. The nickel content in Unit 4 is the highest reported nickel content for any Westinghouse PWR. Although both welds contain less than 0.10 wt.% copper, the weld metals have exhibited high irradiation-induced Charpy 41-J transition temperature shifts in surveillance testing. The Charpy impact 41-J shifts and corresponding fluences are 192 °C at 5.0 × 1023 n/m2 (>1 MeV) for Unit 3 and 162 °C at 6.0 × 1023 n/m2 (>1 MeV) for Unit 4. These relatively low-copper, high-nickel, radiation-sensitive welds relate to the issue of so-called late-blooming nickel-manganese-silicon phases. Atom probe tomography measurements have revealed ˜2 nm-diameter irradiation-induced precipitates containing manganese, nickel, and silicon, with phosphorus evident in some of the precipitates. However, only a relatively few number of copper atoms are contained within the precipitates. The larger increase in the transition temperature shift in the higher copper weld metal from the Ringhals R3 Unit is associated with copper-enriched regions within the manganese-nickel-silicon-enriched precipitates rather than changes in their size or number density.

Fabrication of thick multilayered steel structure using A516 Grade 70 by multipass friction stir welding †

DOE PAGES

Lim, Y. C.; Sanderson, S.; Mahoney, M.; ...

2016-04-06

Here, we fabricated a thick-sectioned multilayered steel structure by multipass friction stir welding on A516 Grade 70 steel. Tensile strength of the multilayered samples was comparable to that of the base metal. Failure was located in the base metal when a defect-free sample was tested. Charpy impact toughness was higher in the stir zone and heat affected zone than in the base metal. For higher microhardness values were found in the stir zone and heat affected zone than the base metal due to grain refinement and modification of the microstructures. As a result, improved mechanical properties compared to the basemore » metal were found in the weld zones of friction stir welded A516 Grade 70 steel.« less

Role of Different Kinds of Boundaries Against Cleavage Crack Propagation in Low-Temperature Embrittlement of Low-Carbon Martensitic Steel

NASA Astrophysics Data System (ADS)

Tsuboi, Mizuki; Shibata, Akinobu; Terada, Daisuke; Tsuji, Nobuhiro

2017-07-01

The present paper investigated the relationship between low-temperature embrittlement and microstructure of lath martensite in a low-carbon steel from both microstructural and crystallographic points of view. The fracture surface of the specimen after the miniaturized Charpy impact test at 98 K (-175 °C) mainly consisted of cleavage fracture facets parallel to crystallographic {001} planes of martensite. Through the crystallographic orientation analysis of micro-crack propagation, we found that the boundaries which separated different martensite variants having large misorientation angles of {001} cleavage planes could inhibit crack propagation. It was then concluded that the size of the aggregations of martensite variants belonging to the same Bain deformation group could control the low-temperature embrittlement of martensitic steels.

Effect of thermo-mechanical treatments on the microstructure and mechanical properties of an ODS ferritic steel

NASA Astrophysics Data System (ADS)

Oksiuta, Z.; Mueller, P.; Spätig, P.; Baluc, N.

2011-05-01

The Fe-14Cr-2W-0.3Ti-0.3Y 2O 3 oxide dispersion strengthened (ODS) reduced activation ferritic (RAF) steel was fabricated by mechanical alloying of a pre-alloyed, gas atomised powder with yttria nano-particles, followed by hot isostatic pressing and thermo-mechanical treatments (TMTs). Two kinds of TMT were applied: (i) hot pressing, or (ii) hot rolling, both followed by annealing in vacuum at 850 °C. The use of a thermo-mechanical treatment was found to yield strong improvement in the microstructure and mechanical properties of the ODS RAF steel. In particular, hot pressing leads to microstructure refinement, equiaxed grains without texture, and an improvement in Charpy impact properties, especially in terms of the upper shelf energy (about 4.5 J). Hot rolling leads to elongated grains in the rolling direction, with a grain size ratio of 6:1, higher tensile strength and reasonable ductility up to 750 °C, and better Charpy impact properties, especially in terms of the ductile-to-brittle transition temperature (about 55 °C).

Grain refinement to improve impact toughness in 9Cr-1Mo steel through a double austenitization treatment

NASA Astrophysics Data System (ADS)

Karthikeyan, T.; Thomas Paul, V.; Saroja, S.; Moitra, A.; Sasikala, G.; Vijayalakshmi, M.

2011-12-01

This paper presents the results of an experimental investigation where an enhancement in Charpy impact toughness and decrease in DBTT was obtained through grain refinement in 9Cr-1Mo steel. The steel in the normalized and tempered condition (1323 K/air cool + 1023 K/2 h/air cool) had an average prior-austenite grain size of 26 μm. By designing a two-stage normalizing (1323 K/2 h/water quench + 1223 K/2 h/air cool) and tempering treatment (1023 K/2 h/air cool), a homogeneous tempered martensite microstructure with a lesser prior-austenite grain size of 12 μm could be obtained. An improvement trend in impact properties of standard sized Charpy specimens was obtained in fine-grained steel: upper shelf energy increased from 175 J to 210 J, and DBTT reduced from 243 K to 228 K. This heat treatment is unique since an attempt to carry out a single-stage low temperature normalizing treatment (1223 K/2 h/air cool) did not give a complete martensite structure, due to the incomplete dissolution of carbides during austenitization.

How severe plastic deformation at cryogenic temperature affects strength, fatigue, and impact behaviour of grade 2 titanium

NASA Astrophysics Data System (ADS)

Mendes, Anibal; Kliauga, Andrea M.; Ferrante, Maurizio; Sordi, Vitor L.

2014-08-01

Samples of grade 2 Ti were processed by Equal Channel Angular Pressing (ECAP), either isolated or followed by further deformation by rolling at room temperature and at 170 K. The main interest of the present work was the evaluation of the effect of cryogenic rolling on tensile strength, fatigue limit and Charpy impact absorbed energy. Results show a progressive improvement of strength and endurance limit in the following order: ECAP; ECAP followed by room temperature rolling and ECAP followed by cryogenic rolling. From the examination of the fatigued samples a ductile fracture mode was inferred in all cases; also, the sample processed by cryogenic rolling showed very small and shallow dimples and a small fracture zone, confirming the agency of strength on the fatigue behaviour. The Charpy impact energy followed a similar pattern, with the exception that ECAP produced only a small improvement over the coarse-grained material. Motives for the efficiency of cryogenic deformation by rolling are the reduced grain size and the association of strength and ductility. The production of favourable deformation textures must also be considered.

The stress corrosion resistance and the cryogenic temperature mechanical properties of annealed Nitronic 60 bar material

NASA Technical Reports Server (NTRS)

Montano, J. W. L.

1977-01-01

Ambient and cryogenic temperature mechanical properties and the ambient temperature stress corrosion properties of annealed, straightened, and centerless ground Nitronic 60 stainless steel alloy bar material are presented. The mechanical properties of longitudinal specimens were evaluated at test temperatures from ambient to liquid hydrogen. The tensile test data indicated increasing strength with decreasing temperature to -196 C. Below liquid nitrogen temperature the smooth tensile and notched tensile strengths decreased slightly while the elongation and reduction of area decreased drastically. The Charpy V-notched impact energy decreased steadily with decreasing test temperature. Stress corrosion tests were performed on longitudinal tensile specimens and transverse C-ring specimens exposed to: alternate immersion in a 3.5% NaCl bath; humidity cabinet; and a 5% salt spray atmosphere. The longitudinal tensile specimens experienced no corrosive attack. Approximately 3/4 of the transverse C-rings exposed to alternate immersion and to salt spray experienced a pitting attack on the top and bottom ends. Additional stress corrosion tests were performed on transverse tensile specimens. No failures occurred in the 90% stressed specimens exposed for 90 days in the alternate immersion and salt spray environments

Effects of microstructure on inverse fracture occurring during drop-weight tear testing of high-toughness X70 pipeline steels

NASA Astrophysics Data System (ADS)

Hwang, Byoungchul; Kim, Yang Gon; Lee, Sunghak; Kim, Nack J.; Yoo, Jang Yong

2005-02-01

The effects of microstructure on inverse fracture occurring in the hammer-impacted region were analyzed after conducting a drop-weight tear test (DWTT) on high-toughness pipeline steels. Three kinds of steels were fabricated by varying the alloying elements, and their microstructures were varied by the rolling conditions. The pressed-notch (PN) or chevron-notch (CN) DWTT and Charpy V-notch (CVN) impact tests were conducted on the rolled steel specimens, and the results were discussed in comparison with the data obtained from CVN tests of prestrained specimens. In the hammer-impacted region of the DWTT specimens, abnormal inverse fracture having a cleavage fracture mode appeared, and the inverse fracture area correlated well with the upper-shelf energy (USE) obtained from the CVN test and with the grain size. The steel specimens having a higher USE or having coarse polygonal ferrite tended to have a larger inverse fracture area than those having a lower USE or having fine acicular ferrite. This was because steels having a higher impact absorption energy required higher energy for fracture initiation and propagation during the DWTT. These results were confirmed by the CVN data of prestrained steel specimens.

A mechanical property and stress corrosion evaluation of Custom 455 stainless steel alloy

NASA Technical Reports Server (NTRS)

Montano, J. W.

1972-01-01

The mechanical and stress corrosion properties are presented of vacuum melted Custom 455 stainless steel alloy bar (1.0-inch diameter) and sheet (0.083-inch thick) material aged at 950 F, 1000 F, and 1050 F. Low temperature mechanical properties were determined at temperatures of 80 F, 0 F, -100 F, and -200 F. For all three aging treatments, the ultimate tensile and 0.2 percent offset yield strengths increased with decreasing test temperatures while the elongation held fairly constant down to -100 F and decreased at -200 F. Reduction in Area decreased moderately with decreasing temperature for the longitudinal round (0.250-inch diameter) specimens. Notched tensile strength and charpy V-notched impact strength decreased with decreasing test temperature. For all three aging treatments, no failures were observed in the unstressed specimens or the specimens stressed to 50, 75, and 100 percent of their yield strengths for 180 days of alternate immersion testing in a 3.5 percent NaCl solution. As indicated by the results of tensile tests performed after alternate immersion testing, the mechanical properties of Custom 455 alloy were not affected by stress or exposure under the conditions of the evaluation.

The Effect of Constant and Pulsed Current Gas Tungsten Arc Welding on Joint Properties of 2205 Duplex Stainless Steel to 316L Austenitic Stainless Steel

NASA Astrophysics Data System (ADS)

Neissi, R.; Shamanian, M.; Hajihashemi, M.

2016-05-01

In this study, dissimilar 316L austenitic stainless steel/2205 duplex stainless steel (DSS) joints were fabricated by constant and pulsed current gas tungsten arc welding process using ER2209 DSS as a filler metal. Microstructures and joint properties were characterized using optical and electron scanning microscopy, tensile, Charpy V-notch impact and micro-hardness tests, and cyclic polarization measurements. Microstructural observations confirmed the presence of chromium nitride and delta ferrite in the heat-affected zone of DSS and 316L, respectively. In addition, there was some deviation in the austenite/ferrite ratio of the surface welding pass in comparison to the root welding pass. Besides having lower pitting potential, welded joints produced by constant current gas tungsten arc welding process, consisted of some brittle sigma phase precipitates, which resulted in some impact energy reduction. The tensile tests showed high tensile strength for the weld joints in which all the specimens were broken in 316L base metal.

Properties of Free-Machining Aluminum Alloys at Elevated Temperatures

NASA Astrophysics Data System (ADS)

Faltus, Jiří; Karlík, Miroslav; Haušild, Petr

In areas close to the cutting tool the workpieces being dry machined could be heated up to 350°C and they may be impact loaded. Therefore it is of interest to study mechanical properties of corresponding materials at elevated temperatures. Free-machining alloys of Al-Cu and Al-Mg-Si systems containing Pb, Bi and Sn additions (AA2011, AA2111B, AA6262, and AA6023) were subjected to Charpy U notch impact test at the temperatures ranging from 20 to 350°C. The tested alloys show a sharp drop in notch impact strength KU at different temperatures. This drop of KU is caused by liquid metal embrittlement due to the melting of low-melting point dispersed phases which is documented by differential scanning calorimetry. Fracture surfaces of the specimens were observed using a scanning electron microscope. At room temperature, the fractures of all studied alloys exhibited similar ductile dimple fracture micromorphology, at elevated temperatures, numerous secondary intergranular cracks were observed.

On the toughness scatter in low alloy C-Mn steel samples fabricated using wire arc additive manufacturing

DOE PAGES

Sridharan, Niyanth S.; Noakes, Mark W.; Nycz, Andrzej; ...

2017-12-06

Low alloy carbon manganese (C-Mn) steel builds were fabricated using a wire based additive manufacturing system developed at Oak Ridge National Laboratory. Specimens were fabricated in the X,Y and Z direction and detailed mechanical testing was performed. The mechanical testing results showed a significant scatter in tensile ductility and significant variation in Charpy toughness. Further detailed microstructure characterization showed significant microstructural heterogeneity in builds fabricated in each direction. The scatter in mechanical properties was then rationalized based on the microstructural observations and the underlying changes in the local heat transfer conditions. Lastly, the results indicate that when fabricating parts usingmore » C-Mn low alloy steel welds the process parameters and tool path should be chosen such that the cooling rate from 800 °C to 500 °C is greater than 30 s to avoid formation of martensite austenite (MA) phases, which leads to toughness reductions.« less

The effect of hot isostatic pressing parameters on microstructure and mechanical properties of Eurofer powder HIPed material

NASA Astrophysics Data System (ADS)

Gentzbittel, J. M.; Chu, I.; Burlet, H.

2002-12-01

The production of reduced activation ferritic/martensitic (RAFM) steel by powder metallurgy and high isostatic pressing (HIP) offers numerous advantages for different nuclear applications. The objective of this work is to optimise the Eurofer powder HIP process in order to obtain RAFM solid HIPed steel with similar mechanical properties to those of a forged material. Starting from the forged solid Eurofer steel batch, the material is atomized and the Eurofer powder is characterized in terms of granulometry, chemical composition, surface oxides, etc. Different compaction HIP cycle parameters in the temperature range (950-1100 °C) are tested. The chemical composition of the HIPed material is comparable to the initial forged Eurofer. All the obtained materials are fully dense and the microstructure of the compacted material is well martensitic. The prior austenite grain size seems to be constant in this temperature range. The mechanical tests performed at room temperature reveal acceptable hardness, tensile and Charpy impact properties regarding the ITER specification.

Heat treatment effects on impact toughness of 9Cr 1MoVNb and 12Cr 1MoVW steels irradiated to 100 dpa

NASA Astrophysics Data System (ADS)

Klueh, R. L.; Alexander, D. J.

1998-10-01

Plates of 9Cr-1MoVNb and 12Cr-1MoVW steels were given four different heat treatments: two normalizing treatments were used and for each normalizing treatment two tempers were used. Miniature Charpy specimens from each heat treatment were irradiated to ≈20 dpa at 365°C and to ≈100 dpa at 420°C in the Fast Flux Test Facility (FFTF). In previous work, the same steels were irradiated in FFTF to 4-5 dpa at 365°C and 35-36 dpa at 420°C. The tests indicated that prior austenite grain size, which was varied by the different normalizing treatments, affected the impact behavior of the 9Cr-1MoVNb but not the 12Cr-1MoVW. Tempering had relatively little effect on the impact behavior of both steels. Conclusions are presented on how heat treatment can be used to optimize impact properties.

On the toughness scatter in low alloy C-Mn steel samples fabricated using wire arc additive manufacturing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sridharan, Niyanth S.; Noakes, Mark W.; Nycz, Andrzej

Low alloy carbon manganese (C-Mn) steel builds were fabricated using a wire based additive manufacturing system developed at Oak Ridge National Laboratory. Specimens were fabricated in the X,Y and Z direction and detailed mechanical testing was performed. The mechanical testing results showed a significant scatter in tensile ductility and significant variation in Charpy toughness. Further detailed microstructure characterization showed significant microstructural heterogeneity in builds fabricated in each direction. The scatter in mechanical properties was then rationalized based on the microstructural observations and the underlying changes in the local heat transfer conditions. Lastly, the results indicate that when fabricating parts usingmore » C-Mn low alloy steel welds the process parameters and tool path should be chosen such that the cooling rate from 800 °C to 500 °C is greater than 30 s to avoid formation of martensite austenite (MA) phases, which leads to toughness reductions.« less

Effect of the Combined Addition of Y and Ti on the Second Phase and Mechanical Properties of China Low-Activation Martensitic Steel

NASA Astrophysics Data System (ADS)

Zhang, Yangpeng; Zhan, Dongping; Qi, Xiwei; Jiang, Zhouhua; Zhang, Huishu

2018-05-01

In this study, approximately 0.35% Ti and two different Y contents were added to China low-activation martensitic (CLAM) steel during melting in a vacuum induction melting furnace. Scanning electron microscopy, transmission electron microscopy, x-ray diffraction, tensile tests, and Charpy impact tests were used to investigate the effects of the combined addition of Y and Ti on the second phase and mechanical properties. The results indicated that Y and Fe formed the large intermetallic compound Fe-Y; the compound easily aggregated in the grain boundaries and exhibited the strength of CLAM steel. Ti did not combine with Y to form the Y-Ti-O phase; however, it could combine with Ta and W to form MC precipitates, which were generally in the 20-50 nm size range. The CLAM steel with a higher Y content exhibited lower yield and tensile strengths at room temperature, with both steels yielding almost identical strengths at 600 °C.

Effect of the Combined Addition of Y and Ti on the Second Phase and Mechanical Properties of China Low-Activation Martensitic Steel

NASA Astrophysics Data System (ADS)

Zhang, Yangpeng; Zhan, Dongping; Qi, Xiwei; Jiang, Zhouhua; Zhang, Huishu

2018-04-01

In this study, approximately 0.35% Ti and two different Y contents were added to China low-activation martensitic (CLAM) steel during melting in a vacuum induction melting furnace. Scanning electron microscopy, transmission electron microscopy, x-ray diffraction, tensile tests, and Charpy impact tests were used to investigate the effects of the combined addition of Y and Ti on the second phase and mechanical properties. The results indicated that Y and Fe formed the large intermetallic compound Fe-Y; the compound easily aggregated in the grain boundaries and exhibited the strength of CLAM steel. Ti did not combine with Y to form the Y-Ti-O phase; however, it could combine with Ta and W to form MC precipitates, which were generally in the 20-50 nm size range. The CLAM steel with a higher Y content exhibited lower yield and tensile strengths at room temperature, with both steels yielding almost identical strengths at 600 °C.

Effect of HIP temperature on microstructure and low cycle fatigue strength of CuCrZr alloy

NASA Astrophysics Data System (ADS)

Nishi, Hiroshi; Enoeda, Mikio

2011-10-01

In order to investigate the effect of the HIP cycle temperatures on the metallurgic degradation and the mechanical properties of CuCrZr alloy, assessments of the microstructure, tensile test, Charpy impact test and low cycle fatigue test are performed for various heat treated CuCrZr alloys, which were solution-annealed followed by water-quenched and aged state of CuCrZr with simulated HIP cycle at temperatures of 980 and 1045 °C. Grain growth occurred on 1045 °C HIP CuCrZr, though slightly on 980 °C HIP CuCrZr. Metallurgic degradation such as voids was not found by optical and SEM observations. There were coarse precipitates in all the CuCrZr and the precipitates did not easily dissolve at 980 °C. The low cycle fatigue strength of 1045 °C HIP CuCrZr was lower than that of other CuCrZr because of the metallurgic degradation caused by the heat cycle, while that of other CuCrZr was corresponding to the best fit curve of ITER MPH.

10 CFR 50.61 - Fracture toughness requirements for protection against pressurized thermal shock events.

Code of Federal Regulations, 2012 CFR

2012-01-01

... (b)(6) of this section, with RTPTS accounting for the effects of annealing and subsequent irradiation...) ΔRTNDT is the mean value of the transition temperature shift, or change in RTNDT, due to irradiation, and... may not exceed twice those values. (D) The irradiation temperature of the Charpy specimens in the...

10 CFR 50.61 - Fracture toughness requirements for protection against pressurized thermal shock events.

Code of Federal Regulations, 2014 CFR

2014-01-01

... (b)(6) of this section, with RTPTS accounting for the effects of annealing and subsequent irradiation...) ΔRTNDT is the mean value of the transition temperature shift, or change in RTNDT, due to irradiation, and... may not exceed twice those values. (D) The irradiation temperature of the Charpy specimens in the...

10 CFR 50.61 - Fracture toughness requirements for protection against pressurized thermal shock events.

Code of Federal Regulations, 2013 CFR

2013-01-01

... (b)(6) of this section, with RTPTS accounting for the effects of annealing and subsequent irradiation...) ΔRTNDT is the mean value of the transition temperature shift, or change in RTNDT, due to irradiation, and... may not exceed twice those values. (D) The irradiation temperature of the Charpy specimens in the...

10 CFR 50.61 - Fracture toughness requirements for protection against pressurized thermal shock events.

Code of Federal Regulations, 2010 CFR

2010-01-01

... accounting for the effects of annealing and subsequent irradiation. (c) Calculation of RT PTS. RTPTS must be... shift, or change in RTNDT, due to irradiation, and must be calculated using Equation 3. Equation 3... irradiation temperature of the Charpy specimens in the capsule must equal the vessel wall temperature at the...

10 CFR 50.61 - Fracture toughness requirements for protection against pressurized thermal shock events.

Code of Federal Regulations, 2011 CFR

2011-01-01

... (b)(6) of this section, with RTPTS accounting for the effects of annealing and subsequent irradiation...) ΔRTNDT is the mean value of the transition temperature shift, or change in RTNDT, due to irradiation, and... may not exceed twice those values. (D) The irradiation temperature of the Charpy specimens in the...

Effects of Core-Shell Rubber (CSR) Nanoparticles on the Fracture Toughness of an Epoxy Resin at Cryogenic Temperatures

NASA Technical Reports Server (NTRS)

Wang, J.; Cannon, S. A.; Schneider, J. A.

2008-01-01

This study investigates the effects of core-shell rubber (CSR) nanoparticles on the fracture toughness of an epoxy resin at liquid nitrogen (LN2) temperatures. Varying amounts of Kane Ace (Registered TradeMark) MX130 toughening agent were added to a commercially available EPON 862/W epoxy resin. Resulting fracture toughness was evaluated by the use of Charpy impact tests conducted on an instrumented drop tower. The size and distribution of the CSR nanoparticles were characterized using Transmission Electric Microscopy (TEM) and Small Angle X-ray Scattering (SAXS). Up to nominal 4.6% addition of the CSR nanoparticles, resulted in a nearly 5 times increase in the measured breaking energy. However, further increases in the amount of CSR nanoparticles had no appreciable affect on the breaking energy.

Analysis of the Mechanical Behavior, Creep Resistance and Uniaxial Fatigue Strength of Martensitic Steel X46Cr13

PubMed Central

Brnic, Josip; Krscanski, Sanjin; Lanc, Domagoj; Brcic, Marino; Turkalj, Goran; Canadija, Marko; Niu, Jitai

2017-01-01

The article deals with the analysis of the mechanical behavior at different temperatures, uniaxial creep and uniaxial fatigue of martensitic steel X46Cr13 (1.4034, AISI 420). For the purpose of considering the aforementioned mechanical behavior, as well as determining the appropriate resistance to creep and fatigue strength levels, numerous uniaxial tests were carried out. Tests related to mechanical properties performed at different temperatures are presented in the form of engineering stress-strain diagrams. Short-time creep tests performed at different temperatures and different stress levels are presented in the form of creep curves. Fatigue tests carried out at stress ratios R=0.25 and R=−1 are shown in the form of S–N (fatigue) diagrams. The finite fatigue regime for each of the mentioned stress ratios is modeled by an inclined log line, while the infinite fatigue regime is modeled by a horizontal line, which represents the fatigue limit of the material and previously was calculated by the modified staircase method. Finally, the fracture toughness has been calculated based on the Charpy V-notch impact energy. PMID:28772749

USE OF SMALL SPECIMENS FOR FRACTURE TOUGHNESS EVALUATION OF RPV STEELS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sokolov, Mikhail A; Nanstad, Randy K

2016-01-01

Small specimens are playing the key role in evaluating properties of irradiated materials. The use of small specimens provides several advantages. Typically, only a small volume of material can be irradiated in a reactor at desirable conditions in terms of temperature, neutron flux, and neutron dose. A small volume of irradiated material may also allow for easier handling of specimens. Smaller specimens reduce the amount of radioactive material, minimizing personnel exposures and waste disposal. However, use of small specimens imposes a variety of challenges as well. These challenges are associated with proper accounting for size effects and transferability of smallmore » specimen data to the real structures of interest. Any fracture toughness specimen that can be made out of standard Charpy specimen or its broken half may have exceptional utility for evaluation of reactor pressure vessels (RPVs) since it would allow one to determine and monitor directly actual fracture toughness instead of requiring indirect predictions using correlations established with impact data. The Charpy V-notch specimen is the most commonly used specimen geometry in surveillance programs and most likely to be used in advanced reactors as per ASME code.« less

Effects of Mo, Cr, and V Additions on Tensile and Charpy Impact Properties of API X80 Pipeline Steels

NASA Astrophysics Data System (ADS)

Han, Seung Youb; Shin, Sang Yong; Seo, Chang-Hyo; Lee, Hakcheol; Bae, Jin-Ho; Kim, Kisoo; Lee, Sunghak; Kim, Nack J.

2009-08-01

In this study, four API X80 pipeline steels were fabricated by varying Mo, Cr, and V additions, and their microstructures and crystallographic orientations were analyzed to investigate the effects of their alloying compositions on tensile properties and Charpy impact properties. Because additions of Mo and V promoted the formation of fine acicular ferrite (AF) and granular bainite (GB) while prohibiting the formation of coarse GB, they increased the strength and upper-shelf energy (USE) and decreased the energy transition temperature (ETT). The addition of Cr promoted the formation of coarse GB and hard secondary phases, thereby leading to an increased effective grain size, ETT, and strength, and a decreased USE. The addition of V resulted in a higher strength, a higher USE, a smaller effective grain size, and a lower ETT, because it promoted the formation of fine and homogeneous of AF and GB. The steel that contains 0.3 wt pct Mo and 0.06 wt pct V without Cr had the highest USE and the lowest ETT, because its microstructure was composed of fine AF and GB while its maintained excellent tensile properties.

The effect of cobalt and carbon the microstructure and mechanical properties of martensitic precipitation strengthened stainless steels

NASA Astrophysics Data System (ADS)

Komolwit, Piyamanee

The effects of cobalt additions on the mechanical properties and strengthening mechanisms of a martensitic precipitation strengthening stainless steel whose composition is (in wt. %) 0.005C/12Cr/5Mo/1.5Ni has been investigated for cobalt levels of 9, 12, 15, 18, and 21 wt. %. Hardness, yield strength and ultimate tensile strength increase as the cobalt content increases, while the Charpy impact energy decreases as tempering temperature increases. At the peak strength of the 21 wt. % cobalt alloy, which is after tempering at 550°C, the yield strength is 1772 MPa, the ultimate tensile strength is 1916 MPa, and the hardness is 55 HRC. The martensite start temperature decreases as cobalt content increases. In this alloys there is no retained austenite after austenitizing, oil quenching and then refrigerating in liquid nitrogen prior to tempering. These alloys contain no reverted austenite except for the 21 wt. % cobalt alloy after tempering at 600°C. Optical micrographs show lath martensite as the matrix for all alloys. Increasing cobalt content has little effect on prior austenite grain size. Transmission electron micrographs show a substructure of lath martensite and a b.c.c. matrix for all alloys after tempering at 525°C. Precipitates were observed in dark field images at all cobalt levels and were seen in bright field images of 21 wt. % cobalt alloy. One of the precipitates was identified as omega phase with a trigonal structure with lattice parameter of a = b = 4.1 A, c = 2.51 A with c/a = 0.612. The particle size appears to be 17 nanometers in diameter and they were found only in the foils of 21 wt. % cobalt alloy. The second precipitate type was identified as a monoclinic phase with a monoclinic structure with lattice parameters of a = 5.464 A, b = 2.843 A, c = 3.178 A, and alpha = gamma = 90° and beta = 63.4°. The monoclinic phase particles appear to significantly contribute to the strength of these alloys, with particles size and volume fraction increasing with increasing cobalt content for the same condition. Limited observation on the effects of carbon additions to a 12Cr/12Co/5Mo/4.5Ni martensitic precipitation strengthening stainless steel has been made for carbon levels of 0.005 wt. %, 0.025 wt. % and 0.05 wt. %. A small addition of chromium, one weight percent, to a 0.005C/12Co/5Mo/5Ni martensitic precipitation strengthening stainless steel was found to increase hardness, strength, Charpy impact energy, and ductility. Results on the effects of cobalt, carbon and chromium additions helped in the selection of modified alloys which were used to investigate the effects of composition and heat treatment on strength and toughness. The first set of modified alloys are referred to as the low carbon modified alloys. These alloys have a better Charpy impact energy than the alloys used to investigate the effect of cobalt on strength and the hardness and strength of these alloys are similar to those of alloys used to investigate the effects of cobalt on strength. Fractographs of these alloys show quasi-cleavage fracture, the presence of ductile fracture increases with increasing cobalt content. The martensite start temperature is lowered by the chromium additions and results in the existence of retained austenite even after refrigeration after austenitizing. Refrigeration prior to tempering is not necessary for these alloys to achieve a high yield strength and good Charpy impact energy. The second set of modified alloys are referred to as the carbon-titanium modified alloys. These alloys differ from the first set of modified alloys in that these alloys contain small additions of carbon and titanium and have lower cobalt levels. Lower cobalt levels were required because carbon lowers the martensite start temperature. These alloys have improved Charpy impact energy and ductility. The carbon addition lowers the martensite start temperature and the martensite start temperature of these alloys is sufficiently low that they contain retain austenite even after refrigeration after austenitizing. Refrigeration prior to tempering is necessity for the alloys to maintain their yield strength and hardness. The effects of austenitizing temperature, cooling rate after austenitization, refrigeration and double austenitization on the mechanical properties of the modified alloys were investigated. Lowering the austenitization temperature decreases the Charpy impact energy and hardness of these alloys. (Abstract shortened by UMI.)

Effects of Molybdenum and Vanadium Addition on Tensile and Charpy Impact Properties of API X70 Linepipe Steels

NASA Astrophysics Data System (ADS)

Kim, Young Min; Shin, Sang Yong; Lee, Hakcheol; Hwang, Byoungchul; Lee, Sunghak; Kim, Nack J.

2007-08-01

This study is concerned with the effects of V and Mo addition on tensile and Charpy impact properties of API X70 linepipe steels. Twelve kinds of steel specimens were produced by varying V and Mo additions and rolling conditions. The addition of V and Mo promoted the formation of acicular ferrite (AF), banitic ferrite (BF), and martensite-austenite (MA) constituents, while suppressing the formation of polygonal ferrite (PF) or pearlite (P). The tensile test results indicated that the tensile strength of the specimens rolled in the two-phase region increased with the addition of V and Mo, while the yield strength did not vary much in these specimens except the water-cooled specimens, which showed the increased yield strength with addition of Mo. The tensile strength of specimens rolled in the single-phase region followed by water cooling increased with increasing V and Mo contents. The yield strength, however, did not vary much with increasing V content or with addition of Mo to the low-V alloy. In these specimens, a substantial increase in the strengths was achieved only when Mo was added to the high-V alloy. The specimens rolled in the single-phase region had higher upper-shelf energy (USE) and lower ductile-brittle transition temperature (DBTT) than the specimens rolled in the two-phase region, because their microstructures were composed of AF and fine PF. According to the electron backscatter diffraction (EBSD) analysis data, the effective grain size in AF was determined by crystallographic packets composed of a few fine grains having similar orientations. Thus, the decreased DBTT in the specimens rolled in the single-phase region could be explained by the decrease in the overall effective grain size due to the presence of AF having smaller effective grain size.

The Assessment and Validation of Mini-Compact Tension Test Specimen Geometry and Progress in Establishing Technique for Fracture Toughness Master Curves for Reactor Pressure Vessel Steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sokolov, Mikhail A.; Nanstad, Randy K.

Small specimens are playing the key role in evaluating properties of irradiated materials. The use of small specimens provides several advantages. Typically, only a small volume of material can be irradiated in a reactor at desirable conditions in terms of temperature, neutron flux, and neutron dose. A small volume of irradiated material may also allow for easier handling of specimens. Smaller specimens reduce the amount of radioactive material, minimizing personnel exposures and waste disposal. However, use of small specimens imposes a variety of challenges as well. These challenges are associated with proper accounting for size effects and transferability of smallmore » specimen data to the real structures of interest. Any fracture toughness specimen that can be made out of the broken halves of standard Charpy specimens may have exceptional utility for evaluation of reactor pressure vessels (RPVs) since it would allow one to determine and monitor directly actual fracture toughness instead of requiring indirect predictions using correlations established with impact data. The Charpy V-notch specimen is the most commonly used specimen geometry in surveillance programs. Assessment and validation of mini-CT specimen geometry has been performed on previously well characterized HSST Plate 13B, an A533B class 1 steel. It was shown that the fracture toughness transition temperature measured by these Mini-CT specimens is within the range of To values that were derived from various large fracture toughness specimens. Moreover, the scatter of the fracture toughness values measured by Mini-CT specimens perfectly follows the Weibull distribution function providing additional proof for validation of this geometry for the Master Curve evaluation of rector pressure vessel steels. Moreover, the International collaborative program has been developed to extend the assessment and validation efforts to irradiated weld metal. The program is underway and involves ORNL, CRIEPI, and EPRI.« less

Methodology for Estimating Thermal and Neutron Embrittlement of Austenitic Stainless Steel Welds During Service in Light Water Reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chopra, O. K.; Rao, A. S.

The effect of thermal aging on the degradation of fracture toughness and Charpy-impact properties of austenitic stainless steel (SS) welds has been characterized at reactor temperatures. The solidification behavior and the distribution and morphology of the ferrite phase in SS welds are described. Thermal aging of the welds results in moderate decreases in Charpy-impact strength and fracture toughness. The upper-shelf Charpy-impact energy of aged welds decreases by 50–80 J/cm2. The decrease in fracture toughness J-R curve, or JIc is relatively small. Thermal aging has minimal effect on the tensile strength. The fracture properties of SS welds are insensitive to fillermore » metal; the welding process has a significant effect. The large variability in the data makes it difficult to establish the effect of the welding process on fracture properties of SS welds. Consequently, the approach used for evaluating thermal and neutron embrittlement of austenitic SS welds relies on establishing a lower-bound fracture toughness J-R curve for unaged and aged, and non-irradiated and irradiated, SS welds. The existing fracture toughness J-R curve data for SS welds have been reviewed and evaluated to define lower-bound J-R curve for submerged arc (SA)/shielded metal arc (SMA)/manual metal arc (MMA) welds and gas tungsten arc (GTA)/tungsten inert gas (TIG) welds in the unaged and aged conditions. At reactor temperatures, the fracture toughness of GTA/TIG welds is a factor of about 2.3 higher than that of SA/SMA/MMA welds. Thermal aging decreases the fracture toughness by about 20%. The potential combined effects of thermal and neutron embrittlement of austenitic SS welds are also described. Lower-bound curves are presented that define the change in coefficient C and exponent n of the power-law J-R curve and the JIc value for SS welds as a function of neutron dose. The potential effects of reactor coolant environment on the fracture toughness of austenitic SS welds are also discussed.« less

Embrittlement behavior of neutron irradiated RAFM steels

NASA Astrophysics Data System (ADS)

Gaganidze, E.; Schneider, H.-C.; Dafferner, B.; Aktaa, J.

2007-08-01

The effects of neutron irradiation on the embrittlement behavior of reduced activation ferritic/martensitic (RAFM) steel EUROFER97 for different heat treatment conditions have been investigated. The irradiation to 16.3 dpa at different irradiation temperatures (250-450 °C) was carried out in the Petten High Flux Reactor in the framework of the HFR Phase-IIb (SPICE) irradiation project. Several reference RAFM steels (F82H-mod, OPTIFER-Ia, GA3X) and MANET-I were also irradiated at selected temperatures. The embrittlement behavior and hardening were investigated by instrumented Charpy-V tests with subsize specimens. The neutron irradiation induced embrittlement and hardening of as-delivered EUROFER97 are comparable to those of investigated reference steels, being mostly pronounced for 250 °C and 300 °C irradiation temperatures. Heat treatment of EUROFER97 at higher austenization temperature substantially improves the embrittlement behavior at irradiation temperatures of 250 °C and 350 °C.

Mechanical properties and microstructures of China low activation martensitic steel compared with JLF-1

NASA Astrophysics Data System (ADS)

Li, Y.; Huang, Q.; Wu, Y.; Nagasaka, T.; Muroga, T.

2007-08-01

The tensile and impact properties of CLAM steel are compared to those of JLF-1 steel. Tensile testing revealed that the ultimate and yield strengths of the CLAM steel are 670 MPa and 512 MPa at room temperature, and 373 MPa and 327 MPa at 873 K, respectively. These values are higher than those measured for JLF-1. The ductile-to-brittle transition temperature (DBTT) of CLAM was found to be 171 K using one-third size Charpy V-notch specimens, which is 16 K lower than that of JLF-1. Microstructural analysis by SEM and TEM indicated that the prior austenite grain size and lath width for CLAM are smaller than those for JLF-1. The finer grain and lath structure is considered to be one of the main reasons for the higher strength and lower DBTT of the CLAM steel.

Deformation behavior and spall fracture of the Hadfield steel under shock-wave loading

NASA Astrophysics Data System (ADS)

Gnyusov, S. F.; Rotshtein, V. P.; Polevin, S. D.; Kitsanov, S. A.

2011-03-01

Comparative studies of regularities in plastic deformation and fracture of the Hadfield polycrystalline steel upon quasi-static tension, impact failure, and shock-wave loading with rear spall are performed. The SINUS-7 accelerator was used as a shock-wave generator. The electron beam parameters of the accelerator were the following: maximum electron energy was 1.35 MeV, pulse duration at half-maximum was 45 ns, maximum energy density on a target was 3.4·1010 W/cm2, shock-wave amplitude was ~20 GPa, and strain rate was ~106 s-1. It is established that the failure mechanism changes from ductile transgranular to mixed ductile-brittle intergranular one when going from quasi-static tensile and Charpy impact tests to shock-wave loading. It is demonstrated that a reason for the intergranular spallation is the strain localization near the grain boundaries containing a carbide interlayer.

A comparative study on the tensile and impact properties of Kevlar, carbon, and S-glass/epoxy composites reinforced with SiC particles

NASA Astrophysics Data System (ADS)

Bulut, Mehmet; Alsaadi, Mohamad; Erkliğ, Ahmet

2018-02-01

Present study compares the tensile and impact characteristics of Kevlar, carbon and glass fiber reinforced composites with addition of microscale silicon carbide (SiC) within the common matrix of epoxy. The variation of tensile and impact strength values was explored for different content of SiC in the epoxy resin by weight (0, 5, 10, 15 and 20 wt%). Resulting failure characteristics were identified by assisting Charpy impact tests. The influence of interfacial adhesion between particle and fiber/matrix on failure and tensile properties was discussed from obtained results and scanning electron microscopy (SEM) figures. It is concluded from results that the content of SiC particles, and fiber types used as reinforcement are major parameters those effecting on tensile and impact resistance of composites as a result of different interface strength properties between particle-matrix and particle-fiber.

Comparison of microstructure and mechanical properties of ultra-narrow gap laser and gas-metal-arc welded S960 high strength steel

NASA Astrophysics Data System (ADS)

Guo, Wei; Li, Lin; Dong, Shiyun; Crowther, Dave; Thompson, Alan

2017-04-01

The microstructural characteristics and mechanical properties, including micro-hardness, tensile properties, three-point bending properties and Charpy impact toughness at different test temperatures of 8 mm thick S960 high strength steel plates were investigated following their joining by multi-pass ultra-narrow gap laser welding (NGLW) and gas metal arc welding (GMAW) techniques. It was found that the microstructure in the fusion zone (FZ) for the ultra-NGLW joint was predominantly martensite mixed with some tempered martensite, while the FZ for the GMAW joint was mainly consisted of ferrite with some martensite. The strength of the ultra-NGLW specimens was comparable to that of the base material (BM), with all welded specimens failed in the BM in the tensile tests. The tensile strength of the GMAW specimens was reduced approximately by 100 MPa when compared with the base material by a broad and soft heat affected zone (HAZ) with failure located in the soft HAZ. Both the ultra-NGLW and GMAW specimens performed well in three-point bending tests. The GMAW joints exhibited better impact toughness than the ultra-NGLW joints.

Investigation of the fracture mechanics of boride composites

NASA Technical Reports Server (NTRS)

Kaufman, L.; Clougherty, E. V.; Nesor, H.

1971-01-01

Fracture energies of WC-6Co, Boride 5 (ZrB2+SiC), Boride 8(ZrB2+SiC+C) and Boride 8-M2(ZrB2+SiC+C) were measured by slow bend and impact tests of notched charpy bars. Cobalt bonded tungsten carbide exhibited impact energies of 0.76 ft-lb or 73.9 in-lb/square inch. Boride 5 and the Boride 8 exhibit impact energies one third and one quarter of that observed for WC-6Co comparing favorably with measurements for SiC and Si3N4. Slow bend-notched bar-fracture energies for WC-6Co were near 2.6 in-lb/square inch or 1/20 the impact energies. Slow bend energies for Boride 8-M2, Boride 8 and Boride 5 were 58%, 42% and 25% of the value observed for WC-6Co. Fractograph showed differences for WC-6Co where slow bend testing resulted in smooth transgranular cleavage while samples broken by impact exhibited intergranular failures. By contrast the boride fractures showed no distinction based on testing method. Fabrication studies were conducted to effect alteration of the boride composites by alloying and introduction of graphite cloth.

Large-scale production of PMMA/SWCNT composites based on SWCNT modified with PMMA.

PubMed

Fraser, Robin Anderson; Stoeffler, Karen; Ashrafi, Behnam; Zhang, Yunfa; Simard, Benoit

2012-04-01

In this work, a two-step method consisting of in situ polymerization of polymethyl methacrylate (PMMA) in the presence of single-walled carbon nanotubes (SWCNT), followed by the redispersion of the resulting compound in dimethylformamide (DMF), was used to fabricate SWCNT modified with PMMA (SWCNT-PMMA). Raman spectroscopy revealed that PMMA was merely wrapped around the SWCNT when raw SWCNT or purified SWCNT were used as the starting material. However, PMMA was covalently bonded to SWCNT when acid treated SWCNT (SWCNT-COOH) was used as the starting material. SWCNT-PMMA compounds were further diluted in pure PMMA by conventional melt compounding at large scale (several kilograms) to obtain transparent composites containing 0.09 wt % SWCNT. The micro- and nano-dispersion of the SWCNT in the composites were analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The thermal and mechanical properties of the composites were determined by thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), tensile testing, and Charpy impact testing. At the the low SWCNT loading studied, the tensile properties remain unchanged, whereas the impact strength improves by 20%.

Microstructure, Composition, and Impact Toughness Across the Fusion Line of High-Strength Bainitic Steel Weldments

NASA Astrophysics Data System (ADS)

Lan, Liangyun; Kong, Xiangwei; Chang, Zhiyuan; Qiu, Chunlin; Zhao, Dewen

2017-09-01

This paper analyzed the evolution of microstructure, composition, and impact toughness across the fusion line of high-strength bainitic steel weldments with different heat inputs. The main purpose was to develop a convenient method to evaluate the HAZ toughness quickly. The compositions of HAZ were insensitive to higher contents of alloy elements ( e.g., Ni, Mo) in the weld metal because their diffusion distance is very short into the HAZ. The weld metal contained predominantly acicular ferrite at any a heat input, whereas the main microstructures in the HAZ changed from lath martensite/bainite to upper bainite with the increasing heat input. The evolution of HAZ toughness in relation to microstructural changes can be revealed clearly combined with the impact load curve and fracture morphology, although the results of impact tests do not show an obvious change with heat input because the position of Charpy V notch contains the weld metal, HAZ as well as a part of base metal. As a result, based on the bead-on-plate welding tests, the welding parameter affecting the HAZ toughness can be evaluated rapidly.

Impact and hardness optimisation of composite materials inspired by the babassu nut (Orbignya speciosa).

PubMed

Staufenberg, Gerrit; Graupner, Nina; Müssig, Jörg

2015-08-20

The babassu nut is the fruit of the babassu palm Orbignya speciosa. The combination of hardness and impact strength is difficult to acquire for artificial materials, making the babassu nut a promising source for biomimetic inspiration. Unnotched Charpy impact tests, Shore D hardness tests and scanning electron microscopy were used for mechanical and microscopical analysis of the pericarp. Four major principles were found for a biomimetic approach: a hard core ((1); endocarp) is embedded in a soft outer layer of high impact strength ((2); epicarp) and is reinforced with fibres of variable fineness (3), some of which are oriented radial to the core (4). Biomimetic fibre-reinforced composites were produced using abstracted mechanisms of the babassu nut based on regenerated cellulose fibres (lyocell, L) with two different fineness values as reinforcement embedded in a polylactide (PLA) core matrix and polypropylene (PP) based outer layers. The biomimetic fibre composite reaches a significantly higher impact strength that is 1.6 times higher than the reference sample produced from a PLA/PP/L-blend. At the same time the hardness is slightly increased compared to PP/L.

Fractographic study of a thick wall pressure vessel failure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Canonico, D.A.; Crouse, R.S.; Henson, T.J.

1979-01-01

The pressure vessel described in this paper is identified as Intermediate Test Vessel 1 (ITV-1) and was fabricated of SA508, Class 2 Steel. It was tested to failure at 54/sup 0/C (130/sup 0/F). The gross failure appeared to be a brittle fracture although accompanied by a measured strain of 0.9%. Seven regions of the fracture were examined in detail and the observed surfaces were compared to Charpy V-notch (C/sub v/) specimens of SA508, Class 2 steel broken at temperatures above and below the ductile to brittle transition temperature. Three samples from the vessel were taken in the region around themore » fatigue notch and four from areas well removed from the notch. All these were carefully examined both optically and by scanning electron microscopy (SEM). It was established that early crack extension was by ductile mode until a large flaw approximately 500 mm long 83 mm wide was developed. At this point the vessel could no longer contain the internal pressure and final rupture was by brittle fracture.« less

Fracture behavior of neutron-irradiated high-manganese austenitic steels

NASA Astrophysics Data System (ADS)

Yoshida, H.; Miyata, K.; Narui, M.; Kayano, H.

1991-03-01

The instrumented Charpy impact test was applied to study the fracture behavior of high-manganese austenitic steels before and after neutron irradiations. Quarter-size specimens of a commercial high-manganese steel (18% Mn-5% Ni-16% Cr), three reference steels (21% Mn-1% Ni-9% Cr, 20% Mn-1% Ni-11% Cr, 15% Mn-1% Ni-13% Cr) and two model steels (17% Mn-4.5% Si-6.5% Cr, 22% Mn-4.5% Si-6.5% Cr-0.2% N) were used for the impact tests at temperatures between 77 and 523 K. The load-deflection curves showed typical features corresponding to characteristics of the fracture properties. The temperature dependences of fracture energy and failure deflection obtained from the curves clearly demonstrate only small effects up to 2 × 10 23 n/m 2 ( E > 0.1 MeV) and brittleness at room temperature in 17% Mn-Si-Cr steel at 1.6 × 10 25 n/m 2 ( E > 0.1 MeV), while ductility still remains in 22%Mn-Si-Cr steel.

Development of low-cost welding procedures for thick sections of HY-150 steel

NASA Technical Reports Server (NTRS)

Schmidt, P. M.; Snow, R. S.

1972-01-01

Low cost welding procedures were developed for welding 6-inch thick HY-150 steel to be used in the manufacture of large diameter motor case Y rings and nozzle attachment flanges. An extensive investigation was made of the mechanical and metallurgical properties and fracture toughness of HY-150 base plate and welds made with manual shielded metal arc process and semi-automatic gas metal arc process in the flat position. Transverse tensiles, all-weld metal tensiles, Charpy V-notch specimens and edge notched bend specimens were tested in the course of the program. In addition metallographic studies and hardness tests were performed on the weld, weld HAZ and base metal. The results of the work performed indicate that both the shielded metal arc and gas metal arc processes are capable of producing consistently sound welds as determined by radiographic and ultrasonic inspection. In addition, the weld metal, deposited by each process was found to exhibit a good combination of strength and toughness such that the selection of a rolled and welded procedure for fabricating rocket motor case components would appear to be technically feasible.

Effect of Reheating Temperature and Cooling Treatment on the Microstructure, Texture, and Impact Transition Behavior of Heat-Treated Naval Grade HSLA Steel

NASA Astrophysics Data System (ADS)

Sk, Md. Basiruddin; Ghosh, A.; Rarhi, N.; Balamuralikrishnan, R.; Chakrabarti, D.

2017-07-01

In order to achieve the desired mechanical properties [YS > 390 MPa, total elongation >16 pct and Charpy impact toughness of 78 J at 213 K (-60 °C)] for naval application, samples from a low-carbon microalloyed steel have been subjected to different austenitization (1223 K to 1523 K) (950 °C to 1250 °C) and cooling treatments (furnace, air, or water cooling). The as-rolled steel and the sample air cooled from 1223 K (950 °C) could only achieve the required tensile properties, while the sample furnace cooled from 1223 K (950 °C) showed the best Charpy impact properties. Water quenching from 1223 K (950 °C) certainly contributed to the strength but affected the impact toughness. Overall, predominantly ferrite matrix with fine effective grain size and intense gamma-fiber texture was found to be beneficial for impact toughness as well as impact transition behavior. Small size and fraction of precipitates (like TiN, Nb, and V carbonitrides) eliminated the possibility of particle-controlled crack propagation and grain size-controlled crack propagation led to cleavage fracture. A simplified analytical approach has been used to explain the difference in impact transition behavior of the investigated samples.

Influence of Mode of Metal Transfer on Microstructure and Mechanical Properties of Gas Metal Arc-Welded Modified Ferritic Stainless Steel

NASA Astrophysics Data System (ADS)

Mukherjee, Manidipto; Pal, Tapan Kumar

2012-06-01

This article describes in detail the effect of the modes of metal transfer on the microstructure and mechanical properties of gas metal arc-welded modified ferritic stainless steel (SSP 409M) sheets (as received) of 4 mm thickness. The welded joints were prepared under three modes of metal transfer, i.e., short-circuit (SC), spray (S), transfer, and mix (M) mode transfer using two different austenitic filler wires (308L and 316L) and shielding gas composition of Ar + 5 pct CO2. The welded joints were evaluated by means of microstructural, hardness, notched tensile strength, Charpy impact toughness, and high cycle fatigue. The dependence of weld metal microstructure on modes of metal transfer and filler wires has been determined by dilution calculation, WRC-1992 diagram, Creq/Nieq ratio, stacking fault energy (SFE), optical microscopy (OM), and transmission electron microscopy (TEM). It was observed that the microstructure as well as the tensile, Charpy impact, and high cycle fatigue of weld metal is significantly affected by the mode of metal transfer and filler wire used. However, the heat-affected zone (HAZ) is affected only by the modes of metal transfer. The results have been correlated with the microstructures of weld and HAZ developed under different modes of metal transfer.

Mechanical properties of injection-molded thermoplastic denture base resins.

PubMed

Hamanaka, Ippei; Takahashi, Yutaka; Shimizu, Hiroshi

2011-03-01

To investigate the mechanical properties of injection-molded thermoplastic denture base resins. Four injection-molded thermoplastic resins (two polyamides, one polyethylene terephthalate, one polycarbonate) and, as a control, a conventional heat-polymerized polymethyl methacrylate (PMMA), were used in this study. The flexural strength at the proportional limit (FS-PL), the elastic modulus, and the Charpy impact strength of the denture base resins were measured according to International Organization for Standardization (ISO) 1567 and ISO 1567:1999/Amd 1:2003. The descending order of the FS-PL was: conventional PMMA > polyethylene terephthalate, polycarbonate > two polyamides. The descending order of the elastic moduli was: conventional PMMA > polycarbonate > polyethylene terephthalate > two polyamides. The descending order of the Charpy impact strength was: polyamide (Nylon PACM12) > polycarbonate > polyamide (Nylon 12), polyethylene terephthalate > conventional PMMA. All of the injection-molded thermoplastic resins had significantly lower FS-PL, lower elastic moduli, and higher or similar impact strength compared to the conventional PMMA. The polyamide denture base resins had low FS-PL and low elastic moduli; one of them possessed very high impact strength, and the other had low impact strength. The polyethylene terephthalate denture base resin showed a moderately high FS-PL, moderate elastic modulus, and low impact strength. The polycarbonate denture base resin had a moderately high FS-PL, moderately high elastic modulus, and moderate impact strength.

Systems design of transformation toughened blast-resistant naval hull steels

NASA Astrophysics Data System (ADS)

Saha, Arup

A systems approach to computational materials design has demonstrated a new class of ultratough, weldable secondary hardened plate steels combining new levels of strength and toughness while meeting processability requirements. A first prototype alloy has achieved property goals motivated by projected naval hull applications requiring extreme fracture toughness (Cv > 85 ft-lbs (115 J) corresponding to KId > 200 ksi.in1/2 (220 MPa.m1/2)) at strength levels of 150--180 ksi (1034--1241 MPa) yield strength in weldable, formable plate steels. A theoretical design concept was explored integrating the mechanism of precipitated nickel-stabilized dispersed austenite for transformation toughening in an alloy strengthened by combined precipitation of M2C carbides and BCC copper both at an optimal ˜3nm particle size for efficient strengthening. This concept was adapted to plate steel design by employing a mixed bainitic/martensitic matrix microstructure produced by air-cooling after solution-treatment and constraining the composition to low carbon content for weldability. With optimized levels of copper and M2C carbide formers based on a quantitative strength model, a required alloy nickel content of 6.5 wt% was predicted for optimal austenite stability for transformation toughening at the desired strength level of 160 ksi (1100 MPa) yield strength. A relatively high Cu level of 3.65 wt% was employed to allow a carbon limit of 0.05 wt% for good weldability. Hardness and tensile tests conducted on the designed prototype confirmed predicted precipitation strengthening behavior in quench and tempered material. Multi-step tempering conditions were employed to achieve the optimal austenite stability resulting in significant increase of impact toughness to 130 ft-lb (176 J) at a strength level of 160 ksi (1100 MPa). Comparison with the baseline toughness-strength combination determined by isochronal tempering studies indicates a transformation toughening increment of 60% in Charpy energy. Predicted Cu particle number densities and the heterogeneous nucleation of optimal stability high Ni 5 nm austenite on nanometer-scale copper precipitates in the multi-step tempered samples was confirmed using three-dimensional atom probe microscopy. Charpy impact tests and fractography demonstrate ductile fracture with C v > 90 ft-lbs (122 J) down to -40°C, with a substantial toughness peak at 25°C consistent with designed transformation toughening behavior. The properties demonstrated in this first prototype represent a substantial advance over existing naval hull steels.

Advanced Rotorcraft Transmission (ART) program

NASA Technical Reports Server (NTRS)

Heath, Gregory F.; Bossler, Robert B., Jr.

1993-01-01

Work performed by the McDonnell Douglas Helicopter Company and Lucas Western, Inc. within the U.S. Army/NASA Advanced Rotorcraft Transmission (ART) Program is summarized. The design of a 5000 horsepower transmission for a next generation advanced attack helicopter is described. Government goals for the program were to define technology and detail design the ART to meet, as a minimum, a weight reduction of 25 percent, an internal noise reduction of 10 dB plus a mean-time-between-removal (MTBR) of 5000 hours compared to a state-of-the-art baseline transmission. The split-torque transmission developed using face gears achieved a 40 percent weight reduction, a 9.6 dB noise reduction and a 5270 hour MTBR in meeting or exceeding the above goals. Aircraft mission performance and cost improvements resulting from installation of the ART would include a 17 to 22 percent improvement in loss-exchange ratio during combat, a 22 percent improvement in mean-time-between-failure, a transmission acquisition cost savings of 23 percent of $165K, per unit, and an average transmission direct operating cost savings of 33 percent, or $24K per flight hour. Face gear tests performed successfully at NASA Lewis are summarized. Also, program results of advanced material tooth scoring tests, single tooth bending tests, Charpy impact energy tests, compact tension fracture toughness tests and tensile strength tests are summarized.

Toughness characterization by small specimen test technique for HIPed joints of F82H steel aiming at first wall fabrication in fusion

NASA Astrophysics Data System (ADS)

Kishimoto, H.; Ono, T.; Sakasegawa, H.; Tanigawa, H.; Kohno, Y.; Kohyama, A.

2013-09-01

Reduced activation ferritic/martensitic steels (RAFMs), such as F82H steels, have been developed as candidates of structural materials for fusion. In the design of a fusion reactor, cooling channels are built in the first wall of the blanket. One large issue is to determine how to join rectangular tubes to thin panels to fabricate the first wall. Hot Isostatic Pressing (HIPing) is a solution to solve the issue. Because of the thin HIPed walls of the channels, the specimen size for inspection of HIPed interface is limited. In the present research, Small Specimen Test Techniques (SSTT) are screened for the destructive toughness investigation technique of HIPed F82H joints. 1/3 size Charpy V-notch impact (1/3 CVN) and small punch (SP) tests are employed for the present research. The toughness of the HIPed joints is strongly affected by various surface finishing of specimens treated previous to the HIPing. In the present research, several kinds of HIPed joints were surface finished by different methods and investigated by 1/3 CVN impact test. The HIPed F82H joints had different toughness ranging from 20% to 70% of the toughness of the F82H base metal. The SP test is also available for the investigation of toughness change by the HIPing. The sensitivity of 1/3 CVN impact test against toughness change was better than the SP test, it revealed that the SP test has some limitations.

A Metallurgical Evaluation of the Powder-Bed Laser Additive Manufactured 4140 Steel Material

NASA Astrophysics Data System (ADS)

Wang, Wesley; Kelly, Shawn

2016-03-01

Using laser powder bed fusion (PBF-L) additive manufacturing (AM) process for steel or iron powder has been attempted for decades. This work used a medium carbon steel (AISI 4140) powder to explore the feasibility of AM. The high carbon equivalent of 4140 steel (CEIIW ≈ 0.83) has a strong tendency toward cold cracking. As such, the process parameters must be carefully controlled to ensure the AM build quality. Through an orthogonally designed experimental matrix, a laser-welding procedure was successfully developed to produce 4140 steel AM builds with no welding defects. In addition, the microstructure and micro-cleanliness of the as-welded PBF-L AM builds were also examined. The results showed an ultra-fine martensite lath structure and an ultra-clean internal quality with minimal oxide inclusion distribution. After optimizing the PBF-L AM process parameters, including the laser power and scan speed, the as-welded AM builds yielded an average tensile strength higher than 1482 MPa and an average 33 J Charpy V-notch impact toughness at -18°C. The surface quality, tensile strength, and Charpy V-notch impact toughness of AM builds were comparable to the wrought 4140 steel. The excellent mechanical properties of 4140 steel builds created by the PBF-L AM AM process make industrial production more feasible, which shows great potential for application in the aerospace, automobile, and machinery industries.

Improvement of Strength-Toughness-Hardness Balance in Large Cross-Section 718H Pre-Hardened Mold Steel

PubMed Central

Liu, Hanghang; Fu, Paixian; Liu, Hongwei; Li, Dianzhong

2018-01-01

The strength-toughness combination and hardness uniformity in large cross-section 718H pre-hardened mold steel from a 20 ton ingot were investigated with three different heat treatments for industrial applications. The different microstructures, including tempered martensite, lower bainite, and retained austenite, were obtained at equivalent hardness. The microstructures were characterized by using metallographic observations, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and electron back-scattered diffraction (EBSD). The mechanical properties were compared by tensile, Charpy U-notch impact and hardness uniformity tests at room temperature. The results showed that the test steels after normalizing-quenching-tempering (N-QT) possessed the best strength-toughness combination and hardness uniformity compared with the conventional quenched-tempered (QT) steel. In addition, the test steel after austempering-tempering (A-T) demonstrated the worse hardness uniformity and lower yield strength while possessing relatively higher elongation (17%) compared with the samples after N-QT (14.5%) treatments. The better ductility of A-T steel mainly depended on the amount and morphology of retained austenite and thermal/deformation-induced twined martensite. This work elucidates the mechanisms of microstructure evolution during heat treatments and will highly improve the strength-toughness-hardness trade-off in large cross-section steels. PMID:29642642

Microstructure and mechanical properties of China low activation martensitic steel joint by TIG multi-pass welding with a new filler wire

NASA Astrophysics Data System (ADS)

Huang, Bo; Zhang, Junyu; Wu, Qingsheng

2017-07-01

Tungsten Inner Gas (TIG) welding is employed for joining of China low activation martensitic (CLAM) steel. A new filler wire was proposed, and the investigation on welding with various heat input and welding passes were conducted to lower the tendency towards the residual of δ ferrite in the joint. With the optimized welding parameters, a butt joint by multi-pass welding with the new filler wire was prepared to investigate the microstructure and mechanical properties. The microstructure of the joint was observed by optical microscope (OM) and scanning electron microscope (SEM). The hardness, Charpy impact and tensile tests of the joint were implemented at room temperature (25 °C). The results revealed that almost full martensite free from ferrite in the joints were obtained by multipass welding with the heat input of 2.26 kJ/mm. A certain degree of softening occurred at the heat affected zone of the joint according to the results of tensile and hardness tests. The as welded joints showed brittle fracture in the impact tests. However, the joints showed toughness fracture after tempering and relatively better comprehensive performance were achieved when the joints were tempered at 740 °C for 2 h.

Correlations of microstructure with dynamic and quasi-static fracture in a plain carbon steel

NASA Astrophysics Data System (ADS)

Couque, H.; Asaro, R. J.; Duffy, J.; Lee, S. H.

1988-09-01

An investigation was conducted into the effects of temperature, loading rate, and various micro-structural parameters on the initiation of plane strain fracture of a plain carbon AISI 1020 steel. Ferrite and prior austenite grain sizes were chosen as the principal microstructural features to be in-vestigated. The microstructural variations were accomplished by changing the austenitizing tempera-ture and by altering the cooling rate during normalization. Fracture toughness tests were conducted using precracked notched round bars loaded in tension to produce two stress intensity rates, viz., K 1 = 1 MPa √m s-1 and K 1 = 2 × 106 MPa √m s-1. In addition, Charpy impact tests along with quasistatic and high rate plasticity tests were conducted. The plasticity tests were done in torsion at shear strain rates ofoverline γ = 5.0 × 10^{ - 4} s^{ - 1 } and overline γ = 1.5 × 10^{3 } s^{ - 1} . Testing temperatures covered the range from -150 °C to 150 °C which encompassed fracture initiation modes involving transgranular cleavage to fully ductile fracture. Micromechanical processes involved in void and cleavage micro-crack formation were identified and quantified. For these purposes notched round tensile tests and subsequent metallographic observations along with TEM and SEM observations of the plane strain fracture toughness specimens were performed. The experimental results and quantitative micro-modeling using simple fracture models provide a means of correlating both quasistatic and dynamic fracture toughness with microstructures.

The effect of microstructure and strength on the fracture toughness of an 18 Ni, 300 grade maraging steel

NASA Technical Reports Server (NTRS)

Psioda, J. A.; Low, J. R., Jr.

1975-01-01

A 300 grade maraging steel was chosen as a vehicle by which to understand the inverse relationship between strength and toughness in high strength alloys such as the 18 Ni maraging steels. The 18 Ni, 300 grade maraging material was a commercial grade consumable-electrode, vacuum arc remelted heat obtained in the form of forged and annealed plate. The matrix contained a population of second-phase impurity inclusions which was a product of the casting and hot working processes. These inclusions did not change with subsequent precipitation hardening. Changes in microstructure resulting in strength increases were brought about by variations in aging temperature and time. Maximum strength was attained in the 300 grade maraging steel by aging at 427 C (800 F) for 100 hours. Tensile, fatigue precracked Charpy impact, and plane-strain fracture toughness tests were performed at room temperature, 20 C (68 F). With increasing strength the fracture toughness decreases as smaller and smaller inclusions act as sites for void initiation.

Development of martensitic steels for high neutron damage applications

NASA Astrophysics Data System (ADS)

Gelles, D. S.

1996-12-01

Martensitic stainless steels have been developed for both in-core applications in advanced liquid metal fast breeder reactors (LMFBR) and for first wall and structural materials applications for commercial fusion reactors. It can now be shown that these steels can be expected to maintain properties to levels as high as 175 or 200 dpa, respectively. The 12Cr1Mo0.5W0.2C alloy HT-9 has been extensively tested for LMFBR applications and shown to resist radiation damage, providing a creep and swelling resistant alternative to austenitic steels. Degradation of fracture toughness and Charpy impact properties have been observed, but properties are sufficient to provide reliable service. In comparison, alloys with lower chromium contents are found to decarburize in contact with liquid sodium and are therefore not recommended. Tungsten stabilized martensitic stainless steels have appropriate properties for fusion applications. Radioactivity levels are benign less than 500 years after service, radiation damage resistance is excellent, including impact properties, and swelling is modest. This report describes the history of the development effort.

Ductile Crack Initiation Criterion with Mismatched Weld Joints Under Dynamic Loading Conditions.

PubMed

An, Gyubaek; Jeong, Se-Min; Park, Jeongung

2018-03-01

Brittle failure of high toughness steel structures tends to occur after ductile crack initiation/propagation. Damages to steel structures were reported in the Hanshin Great Earthquake. Several brittle failures were observed in beam-to-column connection zones with geometrical discontinuity. It is widely known that triaxial stresses accelerate the ductile fracture of steels. The study examined the effects of geometrical heterogeneity and strength mismatches (both of which elevate plastic constraints due to heterogeneous plastic straining) and loading rate on critical conditions initiating ductile fracture. This involved applying the two-parameter criterion (involving equivalent plastic strain and stress triaxiality) to estimate ductile cracking for strength mismatched specimens under static and dynamic tensile loading conditions. Ductile crack initiation testing was conducted under static and dynamic loading conditions using circumferentially notched specimens (Charpy type) with/without strength mismatches. The results indicated that the condition for ductile crack initiation using the two parameter criterion was a transferable criterion to evaluate ductile crack initiation independent of the existence of strength mismatches and loading rates.

High-dose neutron irradiation embrittlement of RAFM steels

NASA Astrophysics Data System (ADS)

Gaganidze, E.; Schneider, H.-C.; Dafferner, B.; Aktaa, J.

2006-09-01

Neutron irradiation-induced embrittlement of the reduced-activation ferritic/martensitic (RAFM) steel EUROFER97 was studied under different heat treatment conditions. Irradiation was performed in the Petten High Flux Reactor within the HFR Phase-IIb (SPICE) irradiation project up to 16.3 dpa and at different irradiation temperatures (250-450 °C). Several reference RAFM steels (F82H-mod, OPTIFER-Ia, GA3X and MANET-I) were also irradiated at selected temperatures. The impact properties were investigated by instrumented Charpy-V tests with subsize specimens. Embrittlement and hardening of as-delivered EUROFER97 steel are comparable to those of reference steels. Heat treatment of EUROFER97 at a higher austenitizing temperature substantially improves the embrittlement behaviour at low irradiation temperatures. Analysis of embrittlement in terms of the parameter C = ΔDBTT/Δ σ indicates hardening-dominated embrittlement at irradiation temperatures below 350 °C with 0.17 ⩽ C ⩽ 0.53 °C/MPa. Scattering of C at irradiation temperatures above 400 °C indicates no hardening embrittlement.

Effects of welding heat and travel speed on the impact property and microstructure of FC welds

NASA Astrophysics Data System (ADS)

Lee, Jeong Soo; Jeong, Sang Hoon; Lim, Dong Yong; Yun, Jin Oh; Kim, Myung Hyun

2010-10-01

This paper is concerned with the effects of welding heat (current x voltage = W) and travel speed (v) on the impact property and microstructure of FC (flux cored) welds. Two sets of plate were welded under different welding conditions such as higher W, v and lower W, v, while maintaining identical heat input. We evaluated the effects of each factor by Charpy impact test and observation of the microstructure, and then compared these data with the results of the numerical temperature analysis. The size of the re-heated zone was increased as the v value decreased, and the results of numerical analysis also revealed the same tendency. Cooling rate of welds (both of as-welded and re-heated zones) decreased as the W value increased. Despite identical heat input conditions, the use of lower W and v made the microstructure finer and increased the volume fraction of AF, thereby leading to a substantial improvement of the impact property.

Flux effect analysis in WWER-440 reactor pressure vessel steels

NASA Astrophysics Data System (ADS)

Kryukov, A.; Blagoeva, D.; Debarberis, L.

2013-11-01

The results of long term research programme concerning the determination of irradiation embrittlement dependence on fast neutron flux for WWER-440 reactor pressure vessel steels before and after annealing are presented in this paper. The study of flux effect was carried out on commercial WWER-440 steels which differ significantly in phosphorous (0.013-0.036 wt%) and copper (0.08-0.20 wt%) contents. All specimens were irradiated in surveillance channel positions under similar conditions at high ˜4 × 1012 сm-2 s-1 and low ˜6 × 1011 сm-2 s-1 fluxes (E > 0.5 MeV) at a temperature of 270 °С. The radiation embrittlement was evaluated by transition temperature shift on the basis of Charpy specimens test results. In case of low flux, the measured Tk shifts could be 25-50 °C bigger than the Tk shifts obtained from high flux data. A significant flux effect is observed in WWER-440 reactor pressure vessel steels with higher copper content (>0.13 wt%).

The stress corrosion resistance and the cryogenic temperature mechanical properties of hot rolled Nitronic 32 bar material

NASA Technical Reports Server (NTRS)

Montano, J. W. L.

1977-01-01

The ambient and cryogenic temperature mechanical properties and the ambient temperature stress corrosion properties of hot rolled and centerless ground Nitronic 32 stainless steel bar material are presented. The mechanical properties of longitudinal specimens were evaluated at test temperatures from ambient to liquid hydrogen. The tensile test data indicated increasing smooth tensile strength with decreasing temperature to liquid hydrogen temperature. However, below -200 F (-129.0 C) the notched tensile strength decreased slightly and below -320 F (-196.0 C) the decrease was significant. The elongation and reduction of area decreased drastically at temperatures below -200 F (-129.0 C). The Charpy V-notched impact energy decreased steadily with decreasing test temperature. Stress corrosion tests were performed on longitudinal tensile specimens stressed to 0, 75, and 90 percent of the 0.2 percent yield strength and on transverse 'C'-ring specimens stressed to 75 and 90 percent of the yield strength and exposed to: alternate immersion in a 3.5 percent NaCl bath, humidity cabinet environment, and a 5 percent salt spray atmosphere. The longitudinal tensile specimens experienced no corrosive attack; however, the 'C'-rings exposed to the alternate immersion and to the salt spray experienced some shallow etching and pitting, respectively. Small cracks appeared in two of the 'C'-rings after one month exposure to the salt spray.

Welding consumable selection for cryogenic (4{degrees}K) application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kane, S.F.; Siewert, T.A.

1994-12-31

Brookhaven National Laboratory (BNL) has begun construction of a large (3.8 kilometer circumference) heavy ion collider for the Department of Energy. The collider uses superconducting magnets, operating at 4{degrees}K in supercritical helium, which meets the definition of a pressure vessel. The ASME Boiler & Pressure Vessel Code grants an exemption from impact testing to certain metals, but only for operating temperatures down to 20{degrees}K. Research and the latest change to ASTM Standard E23 have invalidated Charpy testing at 4{degrees}K, thus compliance with the Code is not possible. This effort was undertaken to identify the weld process and weld material necessarymore » to comply with the intent of the Code (impact test) requirements, that is, to design a weld joint that will assure adequate fracture toughness. We will report the results of this development and testing, and conclude that nitrogen and maganese enhanced 385L provides a superior weld metal for 4{degrees}K cryogenic applications without the exaggerated purity concerns normally associated with superaustenitic weld materials. This development has been so successful that BNL has procured 15,000 pounds of this material for magnet production. Oxygen content, manifested as inclusion density, has the single most significant effect upon fracture toughness and impact strength. Finally, we report that GMAW is a viable welding process, using off-the-shelf equipment, for 4{degrees}K cryogenic applications.« less

Repeated Impact Method and Devices to Simulate the Impact Fatigue Property of Drillstring

NASA Astrophysics Data System (ADS)

Lin, Y. H.; Li, B.; Pan, J.; Li, Q.; Liu, W. Y.; Pan, Y.

2017-05-01

It is well known that drillstring failures are a pendent problem in drilling engineering, because of the fatigue accumulation caused by the low amplitude-repeated impact. In order to reveal the effect of low amplitude-repeated impact on the failure mechanism of the drillstring, a repeated impact method and instrument have been developed based on the Charpy impact method, by which a series of tests have been performed in the condition of non-corrosive medium and with H2S environment respective. Test results of non-corrosive medium environment indicates that, with the increase of single impact energy, the low amplitude-repeated impact resistance of drillstring decreases significantly; For H2S corrosion environment, the low amplitude-repeated impact resistances with H2S is much lower than that without H2S corrosion, and high strength material such as V-150 drillstring is more sensitive to H2S corrosion media. Furthermore, based on the experiment data, the accumulation fatigue model to predict the service life of the drillstring is developed, which could be used to predict the fatigue life. Research fruits are very vital to select a suitable rotational speed for drilling job and drillstring design.

Effect of microstructure on the susceptibility of a 533 steel to temper embrittlement

NASA Astrophysics Data System (ADS)

Raoul, S.; Marini, B.; Pineau, A.

1998-11-01

In ferritic steels, brittle fracture usually occurs at low temperature by cleavage. However the segregation of impurities (P, As, Sn etc...) along prior γ grain boundaries can change the brittle fracture mode from transgranular to intergranular. In quenched and tempered steels, this segregation is associated with what is called the temper-embrittlement phenomenon. The main objective of the present study is to investigate the influence of the as-quenched microstructure (lower bainite or martensite) on the susceptibility of a low alloy steel (A533 cl.1) to temper-embrittlement. Dilatometric tests were performed to determine the continous-cooling-transformation (CCT) diagram of the material and to measure the critical cooling rate ( Vc) for a martensitic quench. Then subsized Charpy V-notched specimens were given various cooling rates from the austenitization temperature to obtain a wide range of as-quenched microstructures, including martensite and bainite. These specimens were subsequently given a heat treatment to develop temper embrittlement and tested to measure the V-notch fracture toughness at -50°C. The fracture surfaces were examined by SEM. It is shown that martensitic microstructures are more susceptible to intergranular embrittlement than bainitic microstructures. These observed microstructural influences are briefly discussed.

The influence of copper precipitation and plastic deformation hardening on the impact-transition temperature of rolled structural steels

NASA Astrophysics Data System (ADS)

Aróztegui, Juan J.; Urcola, José J.; Fuentes, Manuel

1989-09-01

Commercial electric arc melted low-carbon steels, provided as I beams, were characterized both microstructurally and mechanically in the as-rolled, copper precipitation, and plastically pre-deformed conditions. Inclusion size distribution, ferrite grain size, pearlite volume fraction, precipitated volume fraction of copper, and size distribution of these precipitates were deter-mined by conventional quantitative optical and electron metallographic techniques. From the tensile tests conducted at a strain rate of 10-3 s-1 and impact Charpy V-notched tests carried out, stress/strain curves, yield stress, and impact-transition temperature were obtained. The spe-cific fractographic features of the fracture surfaces also were quantitatively characterized. The increases in yield stress and transition temperature experienced upon either aging or work hard-ening were related through empirical relationships. These dependences were analyzed semi-quantitatively by combining microscopic and macroscopic fracture criteria based on measured fundamental properties (fracture stress and yield stress) and observed fractographic parameters (crack nucleation distance and nuclei size). The rationale developed from these fracture criteria allows the semiquantitative prediction of the temperature transition shifts produced upon aging and work hardening. The values obtained are of the right order of magnitude.

Effect of Ultra-Fast Cooling on Microstructure and Properties of High Strength Steel for Shipbuilding

NASA Astrophysics Data System (ADS)

Zhou, Cheng; Ye, Qibin; Yan, Ling

The effect of ultra-fast cooling(UFC) and conventional accelerated cooling(AcC) on the mechanical properties and microstructure of controlled rolled AH32 grade steel plates on industrial scale were compared using tensile test, Charpy impact test, welding thermal simulation, and microscopic analysis. The results show that the properties of the plate produced by UFC are improved considerably comparing to that by AcC. The yield strength is increased with 54 MPa without deterioration in the ductility and the impact energy is improved to more than 260 J at -60 °C with much lower ductile-to-brittle transition temperature(DBTT). The ferrite grain size is refined to ASTM No. 11.5 in the UFC steel with uniform microstructure throughout the thickness direction, while that of the AcC steel is ASTM No. 9.5. The analysis of nucleation kinetics of α-ferrite indicates that the microstructure is refined due to the increased nucleation rate of α-ferrite by much lower γ→α transition temperature through the UFC process. The Hall-Petch effect is quantified for the improvement of the strength and toughness of the UFC steel attributed to the grain refinement.

Microstructure anisotropy and its effect on mechanical properties of reduced activation ferritic/martensitic steel fabricated by selective laser melting

NASA Astrophysics Data System (ADS)

Huang, Bo; Zhai, Yutao; Liu, Shaojun; Mao, Xiaodong

2018-03-01

Selective laser melting (SLM) is a promising way for the fabrication of complex reduced activation ferritic/martensitic steel components. The microstructure of the SLM built China low activation martensitic (CLAM) steel plates was observed and analyzed. The hardness, Charpy impact and tensile testing of the specimens in different orientations were performed at room temperature. The results showed that the difference in the mechanical properties was related to the anisotropy in microstructure. The planer unmelted porosity in the interface of the adjacent layers induced opening/tensile mode when the tensile samples parallel to the build direction were tested whereas the samples vertical to the build direction fractured in the shear mode with the grains being sheared in a slant angle. Moreover, the impact absorbed energy (IAE) of all impact specimens was significantly lower than that of the wrought CLAM steel, and the IAE of the samples vertical to the build direction was higher than that of the samples parallel to the build direction. The impact fracture surfaces revealed that the load parallel to the build layers caused laminated tearing among the layers, and the load vertical to the layers induced intergranular fracture across the layers.

Master curve characterization of the fracture toughness behavior in SA508 Gr.4N low alloy steels

NASA Astrophysics Data System (ADS)

Lee, Ki-Hyoung; Kim, Min-Chul; Lee, Bong-Sang; Wee, Dang-Moon

2010-08-01

The fracture toughness properties of the tempered martensitic SA508 Gr.4N Ni-Mo-Cr low alloy steel for reactor pressure vessels were investigated by using the master curve concept. These results were compared to those of the bainitic SA508 Gr.3 Mn-Mo-Ni low alloy steel, which is a commercial RPV material. The fracture toughness tests were conducted by 3-point bending with pre-cracked charpy (PCVN) specimens according to the ASTM E1921-09c standard method. The temperature dependency of the fracture toughness was steeper than those predicted by the standard master curve, while the bainitic SA508 Gr.3 steel fitted well with the standard prediction. In order to properly evaluate the fracture toughness of the Gr.4N steels, the exponential coefficient of the master curve equation was changed and the modified curve was applied to the fracture toughness test results of model alloys that have various chemical compositions. It was found that the modified curve provided a better description for the overall fracture toughness behavior and adequate T0 determination for the tempered martensitic SA508 Gr.4N steels.

Study of Inclusion Bands in Continuously Cast Steel Billets for Rolling Thermomechanically Treated Rebars

NASA Astrophysics Data System (ADS)

Pandey, J. C.; Choubey, P. N.; Raj, Manish

2008-07-01

The article presents the investigation results of inclusion bands generally formed toward the loose end/inner radius of continuously cast (CC) strands of thermomechanically treated (TMT) rebar grade cast through curved molds. The main analytical tool used for this purpose was an ultrasonic C-scan image analysis system to reveal this band, and the defects detected in this band using the preceding technique were further measured and analyzed in an optical microscope and a scanning electron microscope (SEM) using energy-dispersive system (EDS). The investigation results revealed the presence of macrolevel globular macroinclusions in the size range 50 to 711 μm. The main constituents of the globular inclusions were found to be SiO2 and MnO. Impact test results revealed reduction in ductility in these bands when compared with the billet material without inclusion band toward the opposite face from the inner radius face. In Charpy testing, reduction in the impact energy in these bands was found to be 0.2 kg m. It is important to monitor the severity of macroinclusions present in these bands to avoid the cracking of TMT rebars during hot rolling.

MACHINING TEST SPECIMENS FROM HARVESTED ZION RPV SEGMENTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nanstad, Randy K; Rosseel, Thomas M; Sokolov, Mikhail A

2015-01-01

The decommissioning of the Zion Nuclear Generating Station (NGS) in Zion, Illinois, presents a special and timely opportunity for developing a better understanding of materials degradation and other issues associated with extending the lifetime of existing nuclear power plants (NPPs) beyond 60 years of service. In support of extended service and current operations of the US nuclear reactor fleet, the Oak Ridge National Laboratory (ORNL), through the Department of Energy (DOE), Light Water Reactor Sustainability (LWRS) Program, is coordinating and contracting with Zion Solutions, LLC, a subsidiary of Energy Solutions, an international nuclear services company, the selective procurement of materials,more » structures, components, and other items of interest from the decommissioned reactors. In this paper, we will discuss the acquisition of segments of the Zion Unit 2 Reactor Pressure Vessel (RPV), cutting these segments into blocks from the beltline and upper vertical welds and plate material and machining those blocks into mechanical (Charpy, compact tension, and tensile) test specimens and coupons for microstructural (TEM, SEM, APT, SANS and nano indention) characterization. Access to service-irradiated RPV welds and plate sections will allow through wall attenuation studies to be performed, which will be used to assess current radiation damage models [1].« less

Microstructures and Mechanical Properties of Weld Metal and Heat-Affected Zone of Electron Beam-Welded Joints of HG785D Steel

NASA Astrophysics Data System (ADS)

Zhang, Qiang; Han, Jianmin; Tan, Caiwang; Yang, Zhiyong; Wang, Junqiang

2016-12-01

Vacuum electron beam welding (EBW) process was employed to butt weld 10-mm-thick HG785D high-strength steels. The penetration into the steel was adjusted by beam current. Microstructures at weld metal and heat-affected zone (HAZ) regions were comparatively observed. Mechanical properties of the EBWed joints including Vickers hardness, tensile and Charpy impact tests were evaluated. The results indicated that microstructures at the weld metal consisted of coarse lath martensite and a small amount of acicular martensite, while that in the HAZ was tempered sorbite and martensite. The grain size in the weld metal was found to be larger than that in the HAZ, and its proportion in weld metal was higher. The hardness in the weld metal was higher than the HAZ and base metal. The tensile strength and impact toughness in the HAZ was higher than that in the weld metal. All the behaviors were related to microstructure evolution caused by higher cooling rates and state of base metal. The fracture surfaces of tensile and impact tests on the optimized joint were characterized by uniform and ductile dimples. The results differed significantly from that obtained using arc welding process.

Embrittlement in CN3MN Grade Superaustenitic Stainless Steels

NASA Astrophysics Data System (ADS)

Başkan, Mertcan; Chumbley, Scott L.; Kalay, Yunus Eren

2014-05-01

Superaustenitic stainless steels (SSS) are widely used in extreme environments such as off-shore oil wells, chemical and food processing equipment, and seawater systems due to their excellent corrosion resistance and superior toughness. The design of the corresponding heat treatment process is crucial to create better mechanical properties. In this respect, the short-term annealing behavior of CN3MN grade SSS was investigated by a combined study of Charpy impact tests, hardness measurements, scanning and transmission electron microscopy. Specimens were heat treated at 1200 K (927 °C) for up to 16 minutes annealing time and their impact strengths and hardnesses were tested. The impact toughness was found to decrease to less than the half of the initial values while hardness stayed the same. Detailed fracture surface analyses revealed a ductile to brittle failure transition for relatively short annealing times. Brittle fracture occurred in both intergranular and transgranular modes. SEM and TEM indicated precipitation of nano-sized intermetallics, accounting for the intergranular embrittlement, along the grain boundaries with respect to annealing time. The transgranular fracture originated from linear defects seen to exist within the grains. Close observation of such defects revealed stacking-fault type imperfections, which lead to step-like cracking observed in microlength scales.

Microstructure and Mechanical Properties of a Low Alloyed MnB Cast Steel

NASA Astrophysics Data System (ADS)

Luo, Kaishuang; Bai, Bingzhe

2010-08-01

The microstructure and mechanical properties of a low alloyed MnB cast steel designed for coupler castings of trucks were studied. The results show that the microstructure of the MnB cast steel after water quenching is lath martensite and a small amount of massive islands in the matrix of lath martensite. The average size of the martensite packets is about 10 μm in length. Carbides precipitated dispersively at the tempering temperature of 450 °C. The carbides are slender and fibrous, of which the microstructure was θ-phase (Fe, Mn)3C characterized by TEM. The MnB cast steel has good hardenability and tempering stability. Excellent combination of strength, ductility and low-temperature toughness were obtained after water-quenching and 450 °C tempering: Rm = 960-1040 MPa, ReL = 880-900 MPa, A = 19-21%, Z = 56-58%. Especially, the impact energy of the Charpy V-Notch (CVN) specimens reached 70-88 J at -40 °C. The fracture mechanism is transcrystalline fracture both for ambient temperature uniaxial tensile test specimens and for CVN impact test specimens broken at -40 °C, where the whole surfaces were manifested as voids and dimples.

Analysis of Fracture Mechanism for Al-Mg/SiCp Composite Materials

NASA Astrophysics Data System (ADS)

Maleque, M. A.; Adebisi, A. A.; Izzati, N.

2017-03-01

The present study aims to examine the fracture mechnism of silicon carbide particle (SiCp) reinforced aluminium matrix composite (AMC) material with 1 wt% addition of magnesium is fabricated using the stir casting process. The aluminium composite (Al-Mg/SiCp) is investigated for fatigue life and impact strength considering reinforcement weight fraction and influence of temperature on fracture toughness. The fabricated composite was tested using fatigue testing machine and charpy impact tester. Fractographic observations were evaluated with the scanning electron microscopy (SEM) on the fracture surface. It was found that increasing the SiCp weight fraction increased the fatigue life of the composite. Moreover, the 20 wt% SiCp Al-Mg composite attained the highest number of cycle and fatigue life compared to other variations. The mechanism responsible for the phenomena includes load transfer from the Al matrix alloy phase to the high strength and stiffness of the incorporated SiCp. The temperature variation influenced the impact strength of the composite and improved fracture toughness is achieved at 150 °C. It can be concluded from this study that reinforcement weight fraction and temperature affects the fracture behavior of the composites.

Investigation of temperature dependence of fracture toughness in high-dose HT9 steel using small-specimen reuse technique

NASA Astrophysics Data System (ADS)

Baek, Jong-Hyuk; Byun, Thak Sang; Maloy, Start A.; Toloczko, Mychailo B.

2014-01-01

The temperature dependence of fracture toughness in HT9 steel irradiated to 3-145 dpa at 380-503 °C was investigated using miniature three-point bend (TPB) fracture specimens. A miniature-specimen reuse technique has been established: the tested halves of subsize Charpy impact specimens with dimensions of 27 mm × 3 mm × 4 mm were reused for this fracture test campaign by cutting a notch with a diamond-saw in the middle of each half, and by fatigue-precracking to generate a sharp crack tip. It was confirmed that the fracture toughness of HT9 steel in the dose range depends more strongly on the irradiation temperature than the irradiation dose. At an irradiation temperature <430 °C, the fracture toughness of irradiated HT9 increased with the test temperature, reached an upper shelf of 180-200 MPa √{m} at 350-450 °C, and then decreased with the test temperature. At an irradiation temperature ⩾430 °C, the fracture toughness was nearly unchanged up to about 450 °C and decreased slowly with test temperatures in a higher temperature range. Such a rather monotonic test temperature dependence after high-temperature irradiation is similar to that observed for an archive material generally showing a higher degree of toughness. A brittle fracture without stable crack growth occurred in only a few specimens with relatively lower irradiation and test temperatures. In this discussion, these TPB fracture toughness data are compared with previously published data from 12.7 mm diameter disc compact tension (DCT) specimens.

Investigation of temperature dependence of fracture toughness in high-dose HT9 steel using small-specimen reuse technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baek, Jong-Hyuk; Byun, Thak Sang; Maloy, S

2014-01-01

The temperature dependence of fracture toughness in HT9 steel irradiated to 3 145 dpa at 380 503 C was investigated using miniature three-point bend (TPB) fracture specimens. A miniature-specimen reuse technique has been established: the tested halves of subsize Charpy impact specimens with dimensions of 27 mm 3mm 4 mm were reused for this fracture test campaign by cutting a notch with a diamond-saw in the middle of each half, and by fatigue-precracking to generate a sharp crack tip. It was confirmed that the fracture toughness of HT9 steel in the dose range depends more strongly on the irradiation temperaturemore » than the irradiation dose. At an irradiation temperature <430 C, the fracture toughness of irradiated HT9 increased with the test temperature, reached an upper shelf of 180 200 MPa ffiffiffiffiffi m p at 350 450 C, and then decreased with the test temperature. At an irradiation temperatureP430 C, the fracture toughness was nearly unchanged up to about 450 C and decreased slowly with test temperatures in a higher temperature range. Such a rather monotonic test temperature dependence after high-temperature irradiation is similar to that observed for an archive material generally showing a higher degree of toughness. A brittle fracture without stable crack growth occurred in only a few specimens with relatively lower irradiation and test temperatures. In this discussion, these TPB fracture toughness data are compared with previously published data from 12.7 mm diameter disc compact tension (DCT) specimens.« less

Particles and Zinc on the Absorbed Impact Energy of Gravity Cast Aluminum Matrix Composites

NASA Astrophysics Data System (ADS)

Corchado, Marcos; Reyes, Fernando; Suárez, Oscar Marcelo

2014-06-01

The effect of different amounts of boron, in the form of AlB2 particles, as well as zinc concentration in a gravity cast Al-B-Zn composite, was studied and related to the absorbed energy upon fracture during Charpy impact experiments. In addition, the authors correlated the composite Brinell hardness with the quantitative assessment of brittle and ductile fracture areas of the Charpy fractured specimens and found that increasing AlB2 particle concentration resulted in a reduction of absorbed impact energy. Although larger zinc levels produced somewhat similar results, the AlB2 effect was prevalent. The energy absorption upon impact reached a maximum when no particles were present; conversely, the lowest amount of absorbed energy corresponded to a composite with a composition of 15 wt.% Zn and 8% in volume of AlB2, i.e., the highest concentration of AlB2 and zinc studied. Raising the amount of AlB2 as well as zinc, as expected, resulted in higher Brinell hardness. A statistical analysis allowed studying of the particle size distribution, whereas values for crack tip opening displacement were subsequently calculated for the range of particle sizes found and the corresponding AlB2 particle volume percent. Higher porosity values were measured for larger AlB2 volume percent. Finally, analyses of fracture surfaces corroborated that brittle fracture was favored in composites with higher amounts of AlB2 and zinc.

Machining Test Specimens from Harvested Zion RPV Segments for Through Wall Attenuation Studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosseel, Thomas M; Sokolov, Mikhail A; Nanstad, Randy K

2015-01-01

The decommissioning of the Zion Units 1 and 2 Nuclear Generating Station (NGS) in Zion, Illinois presents a special opportunity for developing a better understanding of materials degradation and other issues associated with extending the lifetime of existing Nuclear Power Plants (NPPs) beyond 60 years of service. In support of extended service and current operations of the US nuclear reactor fleet, the Oak Ridge National Laboratory (ORNL), through the Department of Energy (DOE), Light Water Reactor Sustainability (LWRS) Program, is coordinating and contracting with Zion Solutions, LLC, a subsidiary of Energy Solutions, the selective procurement of materials, structures, and componentsmore » from the decommissioned reactors. In this paper, we will discuss the acquisition of segments of the Zion Unit 2 Reactor Pressure Vessel (RPV), the cutting of these segments into sections and blocks from the beltline and upper vertical welds and plate material, the current status of machining those blocks into mechanical (Charpy, compact tension, and tensile) test specimens and coupons for chemical and microstructural (TEM, APT, SANS, and nano indention) characterization, as well as the current test plans and possible collaborative projects. Access to service-irradiated RPV welds and plate sections will allow through wall attenuation studies to be performed, which will be used to assess current radiation damage models (Rosseel et al. (2012) and Rosseel et al. (2015)).« less

Direction of R&D and Current Status of Understanding of Advanced Gear Steels

DTIC Science & Technology

1986-02-01

our laboratory. A-Z 9-4 CBS600 was developed by Timken as a carburizing grade bearing steel for service above 150C. The philosophy used in designing...melted (VIM-VAR) steels . The effect of long time aging at 230C on the Charpy energy for CBS600 is currently underway at AMMRC. M50 NIL General Electric, in...contact fatigue life and hot hardness as high as for P50 (the high hot hardness bearing steel widely used in aircraft gas turbine engines in the USA) the

Evaluating the Properties of Dissimilar Metal Welding Between Inconel 625 and 316L Stainless Steel by Applying Different Welding Methods and Consumables

NASA Astrophysics Data System (ADS)

Kourdani, Ahmad; Derakhshandeh-Haghighi, Reza

2018-04-01

The current work was carried out to characterize welding of Inconel 625 superalloy and 316L stainless steel. In the present study, shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW) with two types of filler metals (ERNiCrMo-3 and ERSS316L) and an electrode (ENiCrMo-3) were utilized. This paper describes the selection of the proper welding method and welding consumables in dissimilar metal joining. During solidification of ERNiCrMo-3 filler metal, Nb and Mo leave dendritic cores and are rejected to inter-dendritic regions. However, ERSS316L filler metal has small amounts of elements with a high tendency for segregation. So, occurrence of constitutional super-cooling for changing the solidification mode from cellular to dendritic or equiaxed is less probable. Using GTAW with lower heat input results in higher cooling rate and finer microstructure and less Nb segregation. The interface between weld metal and base metal and also unmixed zones was evaluated by scanning electron microscopy and energy dispersive X-ray (EDX) analysis. Microhardness measurements, tensile test, and Charpy impact test were performed to see the effect of these parameters on mechanical properties of the joints.

Effect of W and N on mechanical properties of reduced activation ferritic/martensitic EUROFER-based steel grades

NASA Astrophysics Data System (ADS)

Puype, A.; Malerba, L.; De Wispelaere, N.; Petrov, R.; Sietsma, J.

2018-04-01

The C, N, and W content in EUROFER97, a 9CrWVTa reduced-activation ferritic/martensitic (RAFM) steel, was varied to obtain an experimental assessment of the main effects of the compositional variation on the mechanical properties and microstructural characteristics of six different experimental grades. Light optical microscopy (LOM) and electron back-scattered diffraction (EBSD) revealed in almost all cases a fine tempered lath martensite structure. Analyses of transmission electron micrographs, together with inductively coupled plasma mass spectrometry (ICPMS) and energy-dispersive x-ray spectroscopy (EDS) data, shows the precipitation state and spatial distribution of MxCy (M = Cr, W and Fe) and MX (M = V and/or Ta, X = C or N) carbonitrides within the matrix. The mechanical characterization of the six different steel grades was carried out by means of A50 tensile testing and Charpy tests on standard specimens (55 × 10 × 10 mm3). Lowering the carbon content and keeping the nitrogen content higher than 0.02 wt%, leads to a reduction of the ductile-to-brittle-transition-temperature (DBTT) in comparison with EUROFER97-2. The addition of tungsten further reduces the DBTT to - 94 °C, while maintaining good tensile strength and elongation.

The effect of weld metal matching on girth weld performance: Volume III - an ECA analysis. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Denys, R.M.; Martin, J.T.

1995-02-01

Modern pipeline standards contain alternative methodologies for determining the acceptable defect size in pipeline welds. Through the use of fracture mechanics and plastic collapse assessments, the mechanical and toughness properties of the defective region relate to the applied stress at the defect and defect geometry. The assumptions made in these methodologies are not always representative of the situation accurring in pipeline girth welds. To determine the effect of the various input parameters on acceptable defect size, The Welding Supervisory Committee of the American Gas Association commenced in 1990, in collaboration with the Laboratorium Soete of the University Gent, Belgium, amore » series of small scale (Charpy V impact and CTOD) and large scale (fatigue pre-cracked wide plate) tests. All the experimental investigations were intended to evaluate the effects of weld metal mis-match, temperature, defect size, defect type, defect interaction, pipe wall thickness and yield to tensile ratio on girth weld fracture behaviour. The aim of this report was to determine how weld metal yield strength overmatching or undermatching influences girth weld defect size prediction. A further analysis was conducted using the newly revised PD6493:1991 to provide a critical analysis with the objective of explaining the behaviour of the wide plate tests.« less

Effect of decreased hot-rolling reduction treatment on fracture toughness of low-alloy structural steels

NASA Astrophysics Data System (ADS)

Tomita, Yoshiyuki

1990-09-01

Commercial low-alloy structural steels, 0.45 pct C (AISI 1045 grade), 0.40 pct C-Cr-Mo (AISI 4140 grade), and 0.40 pct C-Ni-Cr-Mo (AISI 4340 grade), have been studied to determine the effect of the decreased hot-rolling reduction treatment (DHRRT) from 98 to 80 pct on fracture toughness of quenched and highly tempered low-alloy structural steels. The significant conclusions are as follows: (1) the sulfide inclusions were modified through the DHRRT from a stringer (mean aspect ratio: 16.5 to 17.6) to an ellipse (mean aspect ratio: 3.8 to 4.5), independent of the steels studied; (2) the DHRRT significantly improved J Ic in the long-transverse and shorttransverse orientations, independent of the steels studied; and (3) the shelf energy in the Charpy V-notch impact test is also greatly improved by the DHRRT, independent of testing orientation and steels studied; however, (4) the ductile-to-brittle transition temperature was only slightly affected by the DHRRT. The beneficial effect on the J Ic is briefly discussed in terms of a crack extension model involving the formation of voids at the inclusion sites and their growth and eventual linking up through the rupture of the intervening ligaments by local shear.

Effects of deformation-induced martensite and grain size on ductile-to-brittle transition behavior of austenitic 18Cr-10Mn-N stainless steels

NASA Astrophysics Data System (ADS)

Hwang, Byoungchul; Lee, Tae-Ho; Kim, Sung-Joon

2010-12-01

Effects of deformation-induced martensite and grain size on ductile-to-brittle transition behavior of austenitic 18Cr-10Mn-(0.3˜0.6)N stainless steels with different alloying elements were investigated by means of Charpy impact tests and microstructural analyses. The steels all exhibited ductile-to-brittle transition behavior due to unusual brittle fracture at low temperatures despite having a face-centered cubic structure. The ductileto-brittle transition temperature (DBTT) obtained from Chapry impact tests did not coincide with that predicted by an empirical equation depending on N content in austenitic Cr-Mn-N stainless steels. Furthermore, a decrease of grain size was not effective in terms of lowering DBTT. Electron back-scattered diffraction and transmission electron microscopy analyses of the cross-sectional area of the fracture surface showed that some austenites with lower stability could be transformed to α'-martensite by localized plastic deformation near the fracture surface. Based on these results, it was suggested that when austenitic 18Cr-10Mn-N stainless steels have limited Ni, Mo, and N content, the deterioration of austenite stability promotes the formation of deformation-induced martensite and thus increases DBTT by substantially decreasing low-temperature toughness.

Evaluation of fracture toughness master curve shifts for JMTR irradiated F82H using small specimens

NASA Astrophysics Data System (ADS)

Yamamoto, T.; Odette, G. R.; Gragg, D.; Kurishita, H.; Matsui, H.; Yang, W. J.; Narui, M.; Yamazaki, M.

2007-08-01

Small to ultra-small 1/3 size pre-cracked Charpy and 1.65 × 1.65 × 9 mm deformation and fracture minibeam (DFMB) specimens of the F82H IEA heat were irradiated to 0.02 and 0.12 dpa at 290 °C in the Japanese Materials Test Reactor. Nominal cleavage transition temperature shifts, based on the measured toughness, KJm( T), data (Δ Tm) as well as reference temperature shifts (Δ T0) found after size-adjusting the KJm( T) data yielded Δ Tm/0 ≈ 27 ± 10 and 44 ± 10 at the two doses, respectively. Using measured yield stress changes (Δ σy), the C0 = Δ T0/Δ σy = 0.58 ± 0.14 at 0.12 dpa, is in good agreement with data in the literature. The dynamic transition temperature shift, Δ Td, derived from DFMB tests, was ≈30 ± 20 °C at 0.1 dpa, also in good agreement with the estimated Δ T0 shifts. The Δ Td and Δ T0 are also in excellent agreement with a Δ T0 = C 0Δ σy (dpa, Ti) hardening-shift model, where the Δ σy (dpa, Ti) was found by fitting a large database of tensile properties.

Evaluation of flow properties in the weldments of vanadium alloys using a novel indentation technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gubbi, A.N.; Rowcliffe, A.F.; Lee, E.H.

1996-10-01

Automated Ball Indentation (ABI) testing, was successfully employed to determine the flow properties of the fusion zone, heat affected zone (HAZ), and base metal of the gas tungsten arc (GTA) and electron beam (EB) welds of the V-4Cr-4Ti (large heat no. 832665) and the V-5Cr-5Ti (heat 832394) alloys. ABI test results showed a clear distinction among the properties of the fusion zone, HAZ, and base metal in both GTA and EB welds of the two alloys. GTA and EB welds of both V-4Cr-4Ti and V-5Cr-5Ti alloys show strengthening of both the fusion zone and the HAZ (compared to base metal)more » with the fusion zone having higher strength than the HAZ. These data correlate well with the Brinell hardness. On the other hand, GTA welds of both alloys, after a post-weld heat treatment of 950{degrees}C for 2 h, show a recovery of the properties to base metal values with V-5Cr-5Ti showing a higher degree of recovery compared to V-4Cr-4Ti. These measurements correlate with the reported recovery of the Charpy impact properties.« less

Impact energy absorption by specimens from the upper end of the human femur.

PubMed

Panagiotopoulos, E; Kostopoulos, V; Tsantzalis, S; Fortis, A P; Doulalas, A

2005-05-01

A cadaveric biomechanical study was performed to investigate the fracture energy absorbed by strips of bone from the proximal femur in relation to age and gender, under impact loading conditions. Four groups (young male, young female, old male, old female) of four cadaveric proximal femurs were used in each case. Four bone strips were taken from the neck and four from the subtrochanteric area and these were tested under dynamic-impact conditions using the Charpy impact test. The fracture energy was calculated as the energy needed to achieve fracture per unit area, and expressed in J/m2. Bone specimens from young males are significantly tougher under impact conditions to those of females (p = 0.001), whereas between the old male and female groups, fracture energy does not significantly differ (p = 0.165). There was also significant difference (p < 0.0005) between the young and the old groups in both genders. The fracture energy absorption of the subtrochanteric area compared to that of the femoral neck for the same group of age and gender is in general slightly higher for all groups. In conclusion, gender in the young age group played a significant role in bone resistance in breaking whereas in the older age group it played a less important role.

Alternative acceptance criteria of girth weld defects in cross country pipelines. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Denys, R.M.; Lefevre, T.

1997-06-01

The failure behaviour of defective girth welds in large diameter pipe lines was assessed using radiographic and mechanised ultrasonic inspection, small scale (tensile, hardness, Charpy and CTOD) and wide plate tests. The specimens were taken from girth welds in API 5LX70 pipe of 1219 mm (48 inches) in diameter by 8,0 mm (0,323 inch) and 13,3 mm (0,524 inch) wall. The test welds were made with the SMAW (8 welds) and GMAW (9 welds) welding processes. Upon completion of the non-destructive tests, 96 curved wide plate specimens were tested to destruction under tensile load. Testing was performed at low temperaturemore » (-50{degrees}C/-58{degrees}F). Defect type, defect position and size were determined from photographs of the fracture face and macro sections (defect characterisation and sizing). In total, 290 typical surface breaking and embedded defects in SMAW or GMAW girth welds have been evaluated. The vast majority of these defects were grossly out of tolerance with respect to current weld quality (workmanship) acceptance levels. To allow the defect tolerance to be determined, the failure strains and stresses were correlated with a defect length determined for an equivalent 3 mm (0, 118 inch) deep defect. This target depth was chosen to represent the average height of one weld pass. The results of this approach have been compared to wall thickness, current workmanship and the EPRG Tier 2 defect limit for planar defects. The defect lengths were derived for rectangular, parabolic and elliptical defect representations.« less

Evaluation and comparison of transverse and impact strength of different high strength denture base resins.

PubMed

Gupta, Abhinav; Tewari, R K

2016-01-01

The present study was undertaken to evaluate and compare the impact strength and transverse strength of the high-impact denture base materials. A conventional heat polymerized acrylic resin was used as a control. The entire experiment was divided into four main groups with twenty specimens each according to denture base material selected Trevalon, Trevalon Hi, DPI Tuff and Metrocryl Hi. These groups were further subgrouped into the two parameters selected, impact strength and flexural strength with ten specimens each. These specimens were then subjected to transverse bend tests with the help of Lloyds instrument using a three point bend principle. Impact tests were undertaken using an Izod-Charpy digital impact tester. This study was analyzed with one-way analysis of variance using Fisher f-test and Bonferroni t-test. There was a significant improvement in the impact strength of high-impact denture base resins as compared to control (Trevalon). However, in terms of transverse bend tests, only DPI Tuff showed higher transverse strength in comparison to control. Trevalon Hi and Metrocryl Hi showed a decrease in transverse strength. Within the limits of this in vitro study, (1) There is a definite increase in impact strength due to the incorporation of butadiene styrene rubber in this high strength denture base materials as compared to Trevalon used as a control. (2) Further investigations are required to prevent the unduly decrease of transverse strength. (3) It was the limitation of the study that the exact composition of the high-impact resins was not disclosed by the manufacturer that would have helped in better understanding of their behavior.

The Effect of Weld Reinforcement and Post-Welding Cooling Cycles on Fatigue Strength of Butt-Welded Joints under Cyclic Tensile Loading.

PubMed

Araque, Oscar; Arzola, Nelson; Hernández, Edgar

2018-04-12

This research deals with the fatigue behavior of butt-welded joints, by considering the geometry and post-welding cooling cycles, as a result of cooling in quiet air and immersed in water. ASTM A-36 HR structural steel was used as the base metal for the shielded metal arc welding (SMAW) process with welding electrode E6013. The welding reinforcement was 1 mm and 3 mm, respectively; axial fatigue tests were carried out to determine the life and behavior in cracks propagation of the tested welded joints, mechanical characterization tests of properties in welded joints such as microhardness, Charpy impact test and metallographic analysis were carried out. The latter were used as input for the analysis by finite elements which influence the initiation and propagation of cracks and the evaluation of stress intensity factors (SIF). The latter led to obtaining the crack propagation rate and the geometric factor. The tested specimens were analyzed, by taking photographs of the cracks at its beginning in order to make a count of the marks at the origin of the crack. From the results obtained and the marks count, the fatigue crack growth rate and the influence of the cooling media on the life of the welded joint are validated, according to the experimental results. It can be concluded that the welded joints with a higher weld reinforcement have a shorter fatigue life. This is due to the stress concentration that occurs in the vicinity of the weld toe.

The Effect of Weld Reinforcement and Post-Welding Cooling Cycles on Fatigue Strength of Butt-Welded Joints under Cyclic Tensile Loading

PubMed Central

Arzola, Nelson; Hernández, Edgar

2018-01-01

This research deals with the fatigue behavior of butt-welded joints, by considering the geometry and post-welding cooling cycles, as a result of cooling in quiet air and immersed in water. ASTM A-36 HR structural steel was used as the base metal for the shielded metal arc welding (SMAW) process with welding electrode E6013. The welding reinforcement was 1 mm and 3 mm, respectively; axial fatigue tests were carried out to determine the life and behavior in cracks propagation of the tested welded joints, mechanical characterization tests of properties in welded joints such as microhardness, Charpy impact test and metallographic analysis were carried out. The latter were used as input for the analysis by finite elements which influence the initiation and propagation of cracks and the evaluation of stress intensity factors (SIF). The latter led to obtaining the crack propagation rate and the geometric factor. The tested specimens were analyzed, by taking photographs of the cracks at its beginning in order to make a count of the marks at the origin of the crack. From the results obtained and the marks count, the fatigue crack growth rate and the influence of the cooling media on the life of the welded joint are validated, according to the experimental results. It can be concluded that the welded joints with a higher weld reinforcement have a shorter fatigue life. This is due to the stress concentration that occurs in the vicinity of the weld toe. PMID:29649117

Effect of thermal shock on mechanical properties of injection-molded thermoplastic denture base resins.

PubMed

Takahashi, Yutaka; Hamanaka, Ippei; Shimizu, Hiroshi

2012-07-01

This study investigated the effect of thermal shock on the mechanical properties of injection-molded thermoplastic denture base resins. Four thermoplastic resins (two polyamides, one polyethylene terephthalate, one polycarbonate) and, as a control, a conventional heat-polymerized polymethyl methacrylate (PMMA), were tested. Specimens of each denture base material were fabricated according to ISO 1567 and were either thermocycled or not thermocycled (n = 10). The flexural strength at the proportional limit (FS-PL), the elastic modulus and the Charpy impact strength of the denture base materials were estimated. Thermocycling significantly decreased the FS-PL of one of the polyamides and the PMMA and it significantly increased the FS-PL of one of the polyamides. In addition, thermocycling significantly decreased the elastic modulus of one of the polyamides and significantly increased the elastic moduli of one of the polyamides, the polyethylene terephthalate, polycarbonate and PMMA. Thermocycling significantly decreased the impact strength of one of the polyamides and the polycarbonate. The mechanical properties of injection-molded thermoplastic denture base resins changed after themocycling.

Effects of Cryogenic Temperature on Fracture Toughness of Core-Shell Rubber (CSR) Toughened Epoxy Nanocomposites

NASA Technical Reports Server (NTRS)

Wang, J.; Cannon, S. A.; Magee, D.; Schneider, J. A.

2008-01-01

This study investigated the effects of core-shell rubber (CSR) nanoparticles on the mechanical properties and fracture toughness of an epoxy resin at ambient and liquid nitrogen (LN2) temperatures. Varying amounts of Kane Ace MX130 toughening agent were added to a commercially available EPON 862/Epikure W epoxy resin. Elastic modulus was calculated using quasi-static tensile data. Fracture toughness was evaluated by the resulting breaking energy measured in Charpy impact tests conducted on an instrumented drop tower. The size and distribution of the CSR nanoparticles were characterized using Transmission Electron Microscopy (TEM) and Small Angle X-ray Scattering (SAXS). Scanning Electron Microscopy (SEM) was used to study the fracture surface morphology. The addition of the CSR nanoparticles increased the breaking energy with negligible change in elastic modulus and ultimate tensile stress (UTS). At ambient temperature the breaking energy increased with increasing additions of the CSR nanoparticles, while at LN2 temperatures, it reached a maximum at 5 wt% CSR concentration. KEY WORDS: liquid nitrogen (LN2) properties, fracture toughness, core-shell rubber (CSR).

Effects of Core-Shell Rubber (CSR) Nanoparticles on the Cryogenic Fracture Toughness of CSR Modified Epoxy

NASA Technical Reports Server (NTRS)

Wang, Jun; Magee, Daniel; Schneider, Judy; Cannon, Seth

2009-01-01

This study investigated the effects of core-shell rubber (CSR) nanoparticles on the mechanical properties and fracture toughness of an epoxy resin at ambient and liquid nitrogen (LN2) temperatures. Varying amounts of Kane Ace(Registered TradeMark) MX130 and Kane Ace(Registered TradeMark) MX960 toughening agent were added to a commercially available EPON 862/Epikure W epoxy resin. Elastic modulus was calculated using quasi-static tensile data. Fracture toughness was evaluated by the resulting breaking energy measured in Charpy impact tests conducted on an instrumented drop tower. The size and distribution of the CSR nanoparticles were characterized using Transmission Electron Microscopy (TEM) and Small Angle X-ray Scattering (SAXS). Scanning Electron Microscopy (SEM) was used to study the fracture surface morphology. The addition of the CSR nanoparticles increased the breaking energy with negligible change in elastic modulus and ultimate tensile stress (UTS). At ambient temperature the breaking energy increased with increasing additions of the CSR nanoparticles up to 13.8wt%, while at LN2 temperatures, it reached a plateau at much lower CSR concentration.

Characteristic of retained austenite decomposition during tempering and its effect on impact toughness in SA508 Gr.3 steel

NASA Astrophysics Data System (ADS)

Yan, Guanghua; Han, Lizhan; Li, Chuanwei; Luo, Xiaomeng; Gu, Jianfeng

2017-01-01

Retained austenite(RA) usually presents in the quenched Nuclear Pressure-Vessel SA508 Gr.3 steel. In the present work, the characteristic of RA decomposition and its effect on the impact toughness were investigated by microstructure observation, dilatometric experiments and Charpy impact tests. The results show that the RA transformed into martensite and bainite during tempering at 230 °C and 400 °C respectively, while mixture of long rod carbides and ferrite formed at 650 °C. The long rod carbides formed from RA decomposition decrease the critical cleavage stress for initiation of micro-cracks, and deteriorate the impact toughness of the steel. Pre-tempering at a low temperature such as 230 °C or 400 °C leading to the decomposition of RA into martensite or baintie can eliminate the deterioration of the toughness caused by direct decomposition into long rod carbides. The absorbed energy indicate that pre-tempering at 400 °C can drive dramatically improvement in the toughness of the steel.

Influence of Powder Outgassing Conditions on the Chemical, Microstructural, and Mechanical Properties of a 14 wt% Cr Ferritic ODS Steel

NASA Astrophysics Data System (ADS)

Sornin, D.; Giroux, P.-F.; Rigal, E.; Fabregue, D.; Soulas, R.; Hamon, D.

2017-11-01

Oxide dispersion-strengthened ferritic stainless steels are foreseen as fuel cladding tube materials for the new generation of sodium fast nuclear reactors. Those materials, which exhibit remarkable creep properties at high temperature, are reinforced by a dense precipitation of nanometric oxides. This precipitation is obtained by mechanical alloying of a powder and subsequent consolidation. Before consolidation, to obtain a fully dense material, the powder is vacuumed to outgas trapped gases and species adsorbed at the surface of the powder particles. This operation is commonly done at moderate to high temperature to evacuate as much as possible volatile species. This paper focuses on the influence of outgassing conditions on some properties of the further consolidated materials. Chemical composition and microstructural characterization of different materials obtained from various outgassing cycles are compared. Finally, impact toughness of those materials is evaluated by using Charpy testing. This study shows a significant influence of the outgassing conditions on the mechanical properties of the consolidated material. However, microstructure and oxygen contents seem poorly impacted by the various outgassing conditions.

Determination of dynamic fracture toughness using a new experimental technique

NASA Astrophysics Data System (ADS)

Cady, Carl M.; Liu, Cheng; Lovato, Manuel L.

2015-09-01

In other studies dynamic fracture toughness has been measured using Charpy impact and modified Hopkinson Bar techniques. In this paper results will be shown for the measurement of fracture toughness using a new test geometry. The crack propagation velocities range from ˜0.15 mm/s to 2.5 m/s. Digital image correlation (DIC) will be the technique used to measure both the strain and the crack growth rates. The boundary of the crack is determined using the correlation coefficient generated during image analysis and with interframe timing the crack growth rate and crack opening can be determined. A comparison of static and dynamic loading experiments will be made for brittle polymeric materials. The analysis technique presented by Sammis et al. [1] is a semi-empirical solution, however, additional Linear Elastic Fracture Mechanics analysis of the strain fields generated as part of the DIC analysis allow for the more commonly used method resembling the crack tip opening displacement (CTOD) experiment. It should be noted that this technique was developed because limited amounts of material were available and crack growth rates were to fast for a standard CTOD method.

Factors Affecting Impact Toughness in Stabilized Intermediate Purity 21Cr Ferritic Stainless Steels and Their Simulated Heat-Affected Zones

NASA Astrophysics Data System (ADS)

Anttila, Severi; Alatarvas, Tuomas; Porter, David A.

2017-12-01

The correlation between simulated weld heat-affected zone microstructures and toughness parameters has been investigated in four intermediate purity 21Cr ferritic stainless steels stabilized with titanium and niobium either separately or in combination. Extensive Charpy V impact toughness testing was carried out followed by metallography including particle analysis using electron microscopy. The results confirmed that the grain size and the number density of particle clusters rich in titanium nitride and carbide with an equivalent circular diameter of 2 µm or more are statistically the most critical factors influencing the ductile-to-brittle transition temperature. Other inclusions and particle clusters, as well as grain boundary precipitates, are shown to be relatively harmless. Stabilization with niobium avoids large titanium-rich inclusions and also suppresses excessive grain growth in the heat-affected zone when reasonable heat inputs are used. Thus, in order to maximize the limited heat-affected zone impact toughness of 21Cr ferritic stainless steels containing 380 to 450 mass ppm of interstitials, the stabilization should be either titanium free or the levels of titanium and nitrogen should be moderated.

Investigation of temperature dependence of fracture toughness in high-dose HT9 steel using small-specimen reuse technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baek, Jong-Hyuk; Byun, Thak Sang; Maloy, Stuart A.

2014-01-01

The temperature dependence of fracture toughness in HT9 steel irradiated to 3–145 dpa at 380–503 degrees*C was investigated using miniature three-point bend (TPB) fracture specimens. A miniature-specimen reuse technique has been established: the tested halves of subsize Charpy impact specimens with dimensions of 27 mm *3mm* 4 mm were reused for this fracture test campaign by cutting a notch with a diamond-saw in the middle of each half, and by fatigue-precracking to generate a sharp crack tip. It was confirmed that the fracture toughness of HT9 steel in the dose range depends more strongly on the irradiation temperature than themore » irradiation dose. At an irradiation temperature <430 *degreesC, the fracture toughness of irradiated HT9 increased with the test temperature, reached an upper shelf of 180—200 MPa*m^.5 at 350–450 degrees*C, and then decreased with the test temperature. At an irradiation temperature >430 degrees*C, the fracture toughness was nearly unchanged up to about 450 *degreesC and decreased slowly with test temperatures in a higher temperature range. Such a rather monotonic test temperature dependence after high-temperature irradiation is similar to that observed for an archive material generally showing a higher degree of toughness. A brittle fracture without stable crack growth occurred in only a few specimens with relatively lower irradiation and test temperatures. In this discussion, these TPB fracture toughness data are compared with previously published data from 12.7 mm diameter disc compact tension (DCT) specimens.« less

High-impact strength acrylic denture base material processed by autoclave.

PubMed

Abdulwahhab, Salwan Sami

2013-10-01

To investigate the effect of two different cycles of autoclave processing on the transverse strength, impact strength, surface hardness and the porosity of high-impact strength acrylic denture base material. High Impact Acryl was the heat-cured acrylic denture base material included in the study. A total of 120 specimens were prepared, the specimens were grouped into: control groups in which high-impact strength acrylic resins processed by conventional water-bath processing technique (74°C for 1.5 h then boil for 30 min) and experimental groups in which high-impact strength acrylic resins processed by autoclave at 121°C, 210 kPa .The experimental groups were divided into (fast) groups for 15 min, and (slow) groups for 30 min. To study the effect of the autoclave processing (Tuttnauer 2540EA), four tests were conducted transverse strength (Instron universal testing machine), impact strength (Charpy tester), surface hardness (shore D), and porosity test. The results were analyzed to ANOVA and LSD test. In ANOVA test, there were highly significant differences between the results of the processing techniques in transverse, impact, hardness, and porosity test. The LSD test showed a significant difference between control and fast groups in transverse and hardness tests and a non-significant difference in impact test and a highly significant difference in porosity test; while, there were a highly significant differences between control and slow groups in all examined tests; finally, there were a non-significant difference between fast and slow groups in transverse and porosity tests and a highly significant difference in impact and hardness tests. In the autoclave processing technique, the slow (long) curing cycle improved the tested physical and mechanical properties as compared with the fast (short) curing cycle. The autoclave processing technique improved the tested physical and mechanical properties of High Impact Acryl. Copyright © 2013 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

Spatial Control of Crystal Texture by Laser DMD Process

DTIC Science & Technology

2009-02-01

Parallel to rolling direction 1120 827 31 205 24 Matweb In718 filler material 1140 414 Charpy Impact Energy (J) Hardness (HRC) Tensile strength (Mpa...J. Choi, K. Nagarathnam, J. Koch, and D. Hetzner, “The direct metal deposition of H13 tool steel for 3-D components,” JOM, 49(5), 1997, 55-60. 4. M...Transactions A, 36A, 2005, 3397-3406. 6. Y. Hua and J. Choi, “Feedback control effects on dimensions and defects of H13 tool steel by DMD process,” J. of Laser Applications, 17(2), 2005, 117-125. 412

Flow and fracture behavior of aluminum alloy 6082-T6 at different tensile strain rates and triaxialities.

PubMed

Chen, Xuanzhen; Peng, Yong; Peng, Shan; Yao, Song; Chen, Chao; Xu, Ping

2017-01-01

This study aims to investigate the flow and fracture behavior of aluminum alloy 6082-T6 (AA6082-T6) at different strain rates and triaxialities. Two groups of Charpy impact tests were carried out to further investigate its dynamic impact fracture property. A series of tensile tests and numerical simulations based on finite element analysis (FEA) were performed. Experimental data on smooth specimens under various strain rates ranging from 0.0001~3400 s-1 shows that AA6082-T6 is rather insensitive to strain rates in general. However, clear rate sensitivity was observed in the range of 0.001~1 s-1 while such a characteristic is counteracted by the adiabatic heating of specimens under high strain rates. A Johnson-Cook constitutive model was proposed based on tensile tests at different strain rates. In this study, the average stress triaxiality and equivalent plastic strain at facture obtained from numerical simulations were used for the calibration of J-C fracture model. Both of the J-C constitutive model and fracture model were employed in numerical simulations and the results was compared with experimental results. The calibrated J-C fracture model exhibits higher accuracy than the J-C fracture model obtained by the common method in predicting the fracture behavior of AA6082-T6. Finally, the Scanning Electron Microscope (SEM) of fractured specimens with different initial stress triaxialities were analyzed. The magnified fractographs indicate that high initial stress triaxiality likely results in dimple fracture.

Influence of Heat Input on Microstructure and Toughness Properties in Simulated CGHAZ of X80 Steel Manufactured Using High-Temperature Processing

NASA Astrophysics Data System (ADS)

Zhu, Zhixiong; Han, Jian; Li, Huijun

2015-11-01

To determine and demonstrate the weldability of high-Nb high-temperature processed (HTP) steels and provide extremely valuable information for future line pipe steel design and general steel manufacture, in the current study the toughness in simulated coarse-grained heat-affected zone (CGHAZ) of an X80 grade steel manufactured using HTP was evaluated. The simulated CGHAZs subjected to thermal cycles with various heat inputs (HIs) (0.8 to 5.0 kJ/mm) were produced using a Gleeble 3500 simulator. The microstructures and corresponding mechanical properties were investigated by means of optical microscopy, scanning electron microscopy, electron backscatter diffraction, hardness testing, and Charpy V-notch (CVN) testing. The microstructural examination shows that the simulated CGHAZs consisted of a bainite-dominant microstructure and relatively low amount (<2 pct) of martensite-austenite (M-A) constituent. The prior austenite grain size was controlled to be 45 to 55 µm at HIs of 0.8 to 3.5 kJ/mm, and remarkably increased to 85 µm at an HI of 5 kJ/mm. The results of CVN testing suggest that superior toughness can be achieved in the studied range of HIs (0.8 to 5 kJ/mm). This is thought to be associated with the combined effects of bainitic microstructure and low M-A fraction as well as comparatively fine austenite grain size in the studied CGHAZs.

Effect of Heat Treatment on Microstructure and Mechanical Properties of Laser Additively Manufactured AISI H13 Tool Steel

NASA Astrophysics Data System (ADS)

Chen, ChangJun; Yan, Kai; Qin, Lanlan; Zhang, Min; Wang, Xiaonan; Zou, Tao; Hu, Zengrong

2017-11-01

The effect of heat treatment on microstructure and mechanical properties (microhardness, wear resistance and impact toughness) of laser additively manufactured AISI H13 tool steel was systemically investigated. To understand the variation of microstructure and mechanical properties under different heat treatments, the as-deposited samples were treated at 350, 450, 550, 600 and 650 °C/2 h, respectively. Microstructure and phase transformation were investigated through optical microscopy, scanning electron microscope and transmission electron microscope. The mechanical properties were characterized by nanoindentation tests, Charpy tests and high-temperature wear tests. The microstructure of as-deposited samples consisted of martensite, ultrafine carbides and retained austenite. After the tempering treatment, the martensite was converted into tempered martensite and some fine alloy carbides which precipitated in the matrix. When treated at 550 °C, the greatest hardness and nanohardness were 600 HV0.3 and 6119.4 MPa due to many needle-like carbides precipitation. The value of hardness increased firstly and then decreased when increasing the temperature. When tempered temperatures exceeded 550 °C, the carbides became coarse, and martensitic matrix recrystallized at the temperature of 650 °C. The least impact energy was 6.0 J at a temperature of 550 °C. Samples tempered at 550 °C had larger wear volume loss than that of others. Wear resistances of all samples under atmospheric condition at 400 °C showed an oxidation mechanism.

Evaluation of Surlyn 8920 as PHE Visor Material and Evaluations of New Adhesives for Improving Bonding Between Teflon and Stainless Steel at Cryogenic Temperature

NASA Technical Reports Server (NTRS)

Ray, Asit K.

1991-01-01

Two studies are presented, and in the first study, Surlyn 8920 (an ionic and amorphous low density polyethylene made by Dupont) was evaluated as a possible replacement of Plexyglass G as PHE visor material. Four formulations of the polymer were made by adding different amounts of UV stabilizer, energy quencher, and antioxident in a Brabender Plasticorder. The formulated polymers were molded in the form of sheets in a compression molder. Cut samples from the molded sheets were exposed in a weatherometer and tested on Instron Tensile Tester for strength and elongation. Specially molded samples of the formulated polymers were subjected to Charpy Impact Tests. In the second study, preliminary evaluations of adhesives for improvement of bonding between Teflon and stainless steel (SS) were performed. Kapton, a high temperature polyimide made by Dupont, and a rubber based adhesive made by Potter Paint Co., were evaluated against industrial quality epoxy, the current material used to bond Teflon and SS. The degreased surfaces of the SS discs were etched mechanically, with a few of these etched chemically. The surfaces of the SS discs were etched mechanically, with a few of these etched chemically. Bonding strengths were evaluated using lap shear tests on the Instron Tensile Tester for the samples bonded by Kapton and industrial quality epoxy. Bond strengths were also evaluated using a pull test on the Instron for the samples bonded by Potter adhesive (CWL-152) and industrial quality epoxy. Based on limited lap shear data, Kapton gave bond strength favorable compared to that of industrial epoxy. Based on limited pull test data, Kapton bonded and CWL-152 bonded samples showed poor strength compared to epoxy bonded sample.

Effects of Microstructure on Tensile, Charpy Impact, and Crack Tip Opening Displacement Properties of Two API X80 Pipeline Steels

NASA Astrophysics Data System (ADS)

Shin, Sang Yong

2013-06-01

The effects of microstructure on tensile, Charpy impact, and crack tip opening displacement (CTOD) properties of two API X80 pipeline steels were investigated in this study. Two API X80 pipeline steels consisting of acicular ferrite and granular bainite, and a small amount of hard phases such as martensite and secondary phases have elongated grains along the rolling direction, so that they show different mechanical properties as the specimens' directions change. The 90 deg specimens have high tensile strength due to the low stress concentration on the fine hard phases and the high loads for the deformation of the elongated grains. In contrast, the 30 deg specimens have less elongated grains and larger hard phases such as martensite, with the size of about 3 μm, than the 90 deg specimens. Hence, the 30 deg specimens have low tensile strength because of the high stress concentration on the large hard phases and the low loads to deform grains. In the 90 deg specimen, brittle crack propagation surfaces are even since cracks propagate in a straight line along the elongated grain structure. In the 30 deg specimen, however, brittle crack propagation surfaces are uneven, and secondary cracks are observed, because of the zigzag brittle crack propagation path. In the CTOD properties, the 90 deg specimens have maximum forces of higher magnitude than the 30 deg specimens, because of the elongated grain structure. However, CTODs of the 90 deg specimens are lower than those of the 30 deg specimens because of the low plastic deformation areas by the elongated grains in the 90 deg specimens.

Effects of Rolling and Cooling Conditions on Microstructure and Tensile and Charpy Impact Properties of Ultra-Low-Carbon High-Strength Bainitic Steels

NASA Astrophysics Data System (ADS)

Sung, Hyo Kyung; Shin, Sang Yong; Hwang, Byoungchul; Lee, Chang Gil; Kim, Nack J.; Lee, Sunghak

2011-07-01

Six ultra-low-carbon high-strength bainitic steel plates were fabricated by controlling rolling and cooling conditions, and effects of bainitic microstructure on tensile and Charpy impact properties were investigated. The microstructural evolution was more critically affected by start cooling temperature and cooling rate than by finish rolling temperature. Bainitic microstructures such as granular bainites (GBs) and bainitic ferrites (BFs) were well developed as the start cooling temperature decreased or the cooling rate increased. When the steels cooled from 973 K or 873 K (700 °C or 600 °C) were compared under the same cooling rate of 10 K/s (10 °C/s), the steels cooled from 973 K (700 °C) consisted mainly of coarse GBs, while the steels cooled from 873 K (600 °C) contained a considerable amount of BFs having high strength, thereby resulting in the higher strength but the lower ductility and upper shelf energy (USE). When the steels cooled from 673 K (400 °C) at a cooling rate of 10 K/s (10 °C/s) or 0.1 K/s (0.1 °C/s) were compared under the same start cooling temperature of 873 K (600 °C), the fast cooled specimens were composed mainly of coarse GBs or BFs, while the slowly cooled specimens were composed mainly of acicular ferrites (AFs). Since AFs had small effective grain size and contained secondary phases finely distributed at grain boundaries, the slowly cooled specimens had a good combination of strength, ductility, and USE, together with very low energy transition temperature (ETT).

Mechanical properties of low-alloy-steels with bainitic microstructures and varying carbon content

NASA Astrophysics Data System (ADS)

Weber, A.; Klarner, J.; Vogl, T.; Schöngrundner, R.; Sam, G.; Buchmayr, B.

2016-03-01

Materials used in the oilfield industry are subjected to special conditions. These requirements for seamless steel tubes are between the priorities of strength, toughness and sour gas resistance. Steels with bainitic microstructure provide a great opportunity for those harsh environmental conditions. With different morphologies of bainite, like carbide free, upper or lower bainite, the interaction of high tensile strength and elongation is assumed to be better than with tempered martensite. To form carbide free bainite two ways of processing are proposed, isothermal holding with accurate time control or controlled continuous cooling. Both require knowledge of time-temperature transformation behaviour, which can be reached through a detailed alloying concept, focused on the influence of silicon to supress the carbide nucleation and chromium to stabilize the austenite fraction. The present work is based on three alloys with varying silicon and chromium contents. The carbide free microstructure is obtained by a continuous cooling path. Additionally different heat treatments were done to compare the inherent performance of the bainitic morphologies. The bainitic structures were characterized metallographically for their microstructure and the primary phase by means of transmission electron microscopy. The mechanical properties of carbide-free structures were analysed with quasi-static tensile tests and Charpy impact tests. Moreover, investigations about hydrogen embrittlement were done with focus on the effect of retained austenite. The results were ranked and compared qualitatively.

Mechanical Properties and Microstructural Characterization of Aged Nickel-based Alloy 625 Weld Metal

NASA Astrophysics Data System (ADS)

Silva, Cleiton Carvalho; de Albuquerque, Victor Hugo C.; Miná, Emerson Mendonça; Moura, Elineudo P.; Tavares, João Manuel R. S.

2018-03-01

The aim of this work was to evaluate the different phases formed during solidification and after thermal aging of the as-welded 625 nickel-based alloy, as well as the influence of microstructural changes on the mechanical properties. The experiments addressed aging temperatures of 650 and 950 °C for 10, 100, and 200 hours. The samples were analyzed by electron microscopy, microanalysis, and X-ray diffraction in order to identify the secondary phases. Mechanical tests such as hardness, microhardness, and Charpy-V impact test were performed. Nondestructive ultrasonic inspection was also conducted to correlate the acquired signals with mechanical and microstructural properties. The results show that the alloy under study experienced microstructural changes when aged at 650 °C. The aging was responsible by the dissolution of the Laves phase formed during the solidification and the appearance of γ″ phase within interdendritic region and fine carbides along the solidification grain boundaries. However, when it was aged at 950 °C, the Laves phase was continuously dissolved and the excess Nb caused the precipitation of the δ-phase (Ni3Nb), which was intensified at 10 hours of aging, with subsequent dissolution for longer periods such as 200 hours. Even when subjected to significant microstructural changes, the mechanical properties, especially toughness, were not sensitive to the dissolution and/or precipitation of the secondary phases.

A comparison of impact force reduction by polymer materials used for mouthguard fabrication.

PubMed

Gawlak, Dominika; Mańka-Malara, Katarzyna; Mierzwińska-Nastalska, Elżbieta; Gieleta, Roman; Kamiński, Tomasz; Łuniewska, Magdalena

2017-01-01

The essential function of mouthguards is protection against the effects of injuries sustained during sports activities. This purpose will be successfully achieved if appropriate materials ensuring sufficient reduction of the injury force are used for mouthguard fabrication. The objective of the study was to investigate the force reduction capability of selected materials as well as to identify which material reduces the impact force to the highest degree. The material for the study were samples of polymers (6 samples in total), obtained during the process of deep pressing (2 samples), flasking (3 samples) and thermal injection (1 sample), which were tested for impact force damping using an impact device - Charpy impact hammer. The control group comprised of the ceramic material samples subjected to the hammer impact. The statistical analysis applied in this study were one-way Welch ANOVA with post-hoc Games-Howell pairwise comparisons. The test materials reduced the impact force of the impact hammer to varying degrees. The greatest damping capability was demonstrated for the following materials: Impak with 1:1 powder-to-liquid weight ratio polymerized with the conventional flasking technique, and Corflex Orthodontic used in the thermal injection technique of mouthguard fabrication. Impak with 1:1 weight ratio and Corflex Orthodontic should be recommended for the fabrication of mouthguards since they demonstrated the most advantageous damping properties.

Intragranular cellular segregation network structure strengthening 316L stainless steel prepared by selective laser melting

NASA Astrophysics Data System (ADS)

Zhong, Yuan; Liu, Leifeng; Wikman, Stefan; Cui, Daqing; Shen, Zhijian

2016-03-01

A feasibility study was performed to fabricate ITER In-Vessel components by Selective Laser Melting (SLM) supported by Fusion for Energy (F4E). Almost fully dense 316L stainless steel (SS316L) components were prepared from gas-atomized powder and with optimized SLM processing parameters. Tensile tests and Charpy-V tests were carried out at 22 °C and 250 °C and the results showed that SLM SS316L fulfill the RCC-MR code. Microstructure characterization reveals the presence of hierarchical macro-, micro- and nano-structures in as-built samples that were very different from SS316L microstructures prepared by other established methods. The formation of a characteristic intragranular cellular segregation network microstructure appears to contribute to the increase of yield strength without losing ductility. Silicon oxide nano-inclusions were formed during the SLM process that generated a micro-hardness fluctuation in the building direction. The combined influence of a cellular microstructure and the nano-inclusions constraints the size of ductile dimples to nano-scale. The crack propagation is hindered by a pinning effect that improves the defect-tolerance of the SLM SS316L. This work proves that it was possible to manufacture SS316L with properties suitable for ITER First Wall panels. Further studies on irradiation properties of SLM SS316L and manufacturing of larger real-size components are needed.

Effect of twice quenching and tempering on the mechanical properties and microstructures of SCRAM steel for fusion application

NASA Astrophysics Data System (ADS)

Xiong, Xuesong; Yang, Feng; Zou, Xingrong; Suo, Jinping

2012-11-01

The effect of twice quenching and tempering on the mechanical properties and microstructures of SCRAM steel was investigated. The results from tensile tests showed that whether twice quenching and tempering processes(1253 K/0.5 h/W.C(water cool) + 1033 K/2 h/A.C(air cool) + 1233 K/0.5 h/W.C + 1033 K/2 h/A.C named after 2Q&2TI, and 1253 K/0.5 h/W.C + 1033 K/2 h/A.C + 1233 K/0.5 h/W.C + 1013 K/2 h/A.C named after 2Q&2TII)increased strength of steel or not depended largely on the second tempering temperature compared to quenching and tempering process(1253 K/0.5 h/W.C + 1033 K/2 h/A.C named after 1Q&1T). Charpy V-notch impact tests indicated that twice quenching and tempering processes reduced the ductile brittle transition temperature (DBTT). Microstructure inspection revealed that the prior austenitic grain size and martensite lath width were refined after twice quenching and tempering treatments. Precipitate growth was inhibited by a slight decrease of the second tempering temperature from 1033 to 1013 K. The finer average size of precipitates is considered to be the main possible reason for the higher strength and lower DBTT of 2Q&2TII compared with 2Q&2TI.

Tensile Fracture Behavior of 316L Austenitic Stainless Steel Manufactured by Hot Isostatic Pressing

NASA Astrophysics Data System (ADS)

Cooper, A. J.; Brayshaw, W. J.; Sherry, A. H.

2018-02-01

Herein we investigate how the oxygen content in hot isostatically pressed (HIP'd) 316L stainless steel affects the mechanical properties and tensile fracture behavior. This work follows on from previous studies, which aimed to understand the effect of oxygen content on the Charpy impact toughness of HIP'd steel. We expand on the work by performing room-temperature tensile testing on different heats of 316L stainless steel, which contain different levels of interstitial elements (carbon and nitrogen) as well as oxygen in the bulk material. Throughout the work we repeat the experiments on conventionally forged 316L steel as a reference material. The analysis of the work indicates that oxygen does not contribute to a measureable solution strengthening mechanism, as is the case with carbon and nitrogen in austenitic stainless steels (Werner in Mater Sci Eng A 101:93-98, 1988). Neither does oxygen, in the form of oxide inclusions, contribute to precipitation hardening due to the size and spacing of particles. However, the oxide particles do influence fracture behavior; fractography of the failed tension test specimens indicates that the average ductile dimple size is related to the oxygen content in the bulk material, the results of which support an on-going hypothesis relating oxygen content in HIP'd steels to their fracture mechanisms by providing additional sites for the initiation of ductile damage in the form of voids.

Effects of Range of Stress and of Special Notches on Fatigue Properties of Aluminum Alloys Suitable for Airplane Propellers

NASA Technical Reports Server (NTRS)

Dolan, Thomas J

1942-01-01

Laboratory tests were made to obtain information on the load-resisting properties of X76S-T aluminum alloy when subjected to static, impact, and repeated loads. Results are presented from static-load test of unnotched specimens in tension and in torsion and of notched specimens in tension. Charpy impact values obtained from bend tests on notched specimens and tension impact values for both notched and unnotched specimens tested at several different temperatures are included. The endurance limits obtained from repeated bending fatigue tests made on three different types of testing machine are given for unnotched polished specimens, and the endurance limits of notched specimens subjected to six different ranges of bending stress are also reported. The results indicated that: (a) polished rectangular specimens had an endurance limit about 30 percent less than that obtained for round specimens; (b) a comparison of endurance limits obtained from tests on three different types of machine indicated that there was no apparent effect of speed of testing on the endurance limit for the range of speeds used (1,750 to 13,000 rpm). (c) the fatigue strength (endurance limit) of the X76S-T alloy was greatly decreased by the presence of a notch in the specimens; (d) no complete fractures of the entire specimens occurred in notched fatigue specimens when subjected to stress cycles for which the mean stress at the notch during the cycle was a compressive stress; for this test condition a microscopic cracking occurred near the root of the notch and was used as a criterion of failure of the specimen. (e) as the mean stress at the notch was decreased from a tensile (+) stress to a compressive (-) stress, it was found that the alternating stress that could be superimposed on the mean stress in the cycle without causing failure of the specimens was increased.

Evolution of microstructure in stainless martensitic steel for seamless tubing

NASA Astrophysics Data System (ADS)

Pyshmintsev, I. Yu.; Bityukov, S. M.; Pastukhov, V. I.; Danilov, S. V.; Vedernikova, L. O.; Lobanov, M. L.

2017-12-01

Scanning electron microscopy with orientation analysis by the electron backscatter diffraction (EBSD) method is used to study microstructures and textures formed in the 0.08C-13Cr-3Ni-Mo-V-Nb steel through seamless tube production route: after hot deformation by extrusion; after quenching from various temperatures and subsequent high tempering. It is shown that the martensitic microstructure formed both after hot deformation and after quenching is characterized by the presence of deformation crystallographic texture, which is predetermined by the texture of austenite. The effect of heat treatment on texture, packet refinement, lath width, precipitation of carbides and Charpy impact energy is analyzed.

Characterization of Multilayered Multipass Friction Stir Weld on ASTM A572 G50 Steel

DOE PAGES

Lim, Yong Chae; Sanderson, Samuel; Mahoney, Murray; ...

2014-01-01

A multilayered multipass friction stir weld (MM-FSW) on ASTM A572 Grade 50 steel was characterized to understand its potential application for thick-section structures. The 15-mm-thick section was fabricated by stacking up three steel plates and then friction stir welding the plates together in a total of 5 passes. The unique butt/lap joint configuration encountered in the multilayer weld was examined to understand the effect of tool rotation direction on the joint quality especially the formation of hooking defect. Charpy V-notch impact toughness tests showed generally higher impact toughness energy for the stir zone than the base metal with a ductilemore » fracture mode. The microhardness value was measured from 195 to 220 HV in the stir zone, while the base metal showed an average value of 170 HV. The microstructure in the stir zone and the adjacent heat affected zone was quantified using Optical and Scanning Electron Microscopy (SEM) including Electron Backscatter Diffraction (EBSD). The increased toughness and hardness were correlated with the refined microstructure in stir zone, resulting from severe plastic deformation and subsequent dynamic recrystallization during friction stir welding.« less

Performance of repair welds on aged Cr-Mo piping girth welds

NASA Astrophysics Data System (ADS)

Viswanathan, R.; Gandy, D. W.

1999-10-01

This article documents the results of an industry survey of weld repair practices and describes the results of experimental evaluations performed on service-aged 21/4 Cr-1Mo steel piping using SMAW with both conventional postweld heat treatments and temper bead repair techniques. The overall results of this program provide substantial evidence that service-aged piping systems can be successfully weld repaired with and without postweld heat treatments and that life extension by several decades is achievable under the right design and repair conditions. Weld repairs performed on degraded exservice welds resulted in restoration or improvement of tensile and creep properties. Microhardness test results within the heat-affected zone of each weldment indicated that the temper bead weld repairs produced only slightly higher peak hardness values than those measured for the fully postweld heat treated repairs. Finally, in terms of toughness, temper bead weld repairs consistently produced higher impact properties than those measured for the postweld heat treated weldments. Gas tungsten arc weld repairs with postweld heat treatment resulted in the best combination of tensile strength, uniform microhardness distribution across the weld, Charpy toughness, and creep rupture life.

A Comparison of Mechanical Properties and Hydrogen Embrittlement Resistance of Austempered vs Quenched and Tempered 4340 Steel

NASA Astrophysics Data System (ADS)

Tartaglia, John M.; Lazzari, Kristen A.; Hui, Grace P.; Hayrynen, Kathy L.

2008-03-01

This study was conducted to compare the hydrogen embrittlement (HE) resistance of austempered 4340 steel with quenched and tempered (Q&T) 4340 steel with an identical yield strength (YS) of 1340 MPa (194 ksi). A baseline comparison showed that the austempered steel with a lower bainite microstructure exhibited higher hardness, tensile strengths, Charpy V-notch (CVN) impact toughness, and ductility at both low 233 K (-40 F) and ambient temperatures, as compared to the Q&T steel with a martensite microstructure. After machining and just prior to testing, subsized CVN specimens and notched bend specimens were immersed in hydrochloric acid-water baths. The HE resistance was higher for the austempered steel than the Q&T steel. No differences in room-temperature CVN energy resulted from hydrogen charging of the austempered and Q&T steels vs their unexposed counterparts. However, in the notched bend specimens, the hydrogen charging caused significant peak load decreases (40 pct) for the Q&T steel, while the austempered steel exhibited only small (6 pct) decreases in peak load. Intergranular (IG) fracture occurred solely in the charged Q&T bend samples, which is further evidence of their embrittlement.

High temperature compounds for turbine vanes. [of SiC, Si3N4, and Si composites

NASA Technical Reports Server (NTRS)

Rhodes, W. H.; Cannon, R. M., Jr.

1974-01-01

Fabrication and microstructure control studies were conducted on SiC, Si3N and composites based on Si3N. Charpy mode impact testing to 2400 F established that Si3N4/Mo composites have excellent potential. Attempts to fabricate composites of Si3N4 with superalloys, both by hot pressing and infiltration were largely unsuccessful in comparison to using Mo, Re, and Ta which are less reactive. Modest improvements in impact strength were realized for monolithic Si3N4; however, SiC strengths increased by a factor of six and now equal values achieved for Si3N4. Correlations of impact strength with material properties are discussed. Reduced MgO densification aid additions to Si3N4 were found to decrease densification kinetics, increase final porosity, decrease room temperature bend strength, increase high temperature bend strength, and decrease bend stress rupture properties. The decrease in bend strength at high temperature for fine grain size SiC suggested that a slightly larger grain size material with a nearly constant strength-temperature relation may prove desirable in the creep and stress rupture mode.

The effect of welding parameters on high-strength SMAW all-weld-metal. Part 1: AWS E11018-M

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vercesi, J.; Surian, E.

Three AWS A5.5-81 all-weld-metal test assemblies were welded with an E110180-M electrode from a standard production batch, varying the welding parameters in such a way as to obtain three energy inputs: high heat input and high interpass temperature (hot), medium heat input and medium interpass temperature (medium) and low heat input and low interpass temperature (cold). Mechanical properties and metallographic studies were performed in the as-welded condition, and it was found that only the tensile properties obtained with the test specimen made with the intermediate energy input satisfied the AWS E11018-M requirements. With the cold specimen, the maximal yield strengthmore » was exceeded, and with the hot one, neither the yield nor the tensile minimum strengths were achieved. The elongation and the impact properties were high enough to fulfill the minimal requirements, but the best Charpy-V notch values were obtained with the intermediate energy input. Metallographic studies showed that as the energy input increased the percentage of the columnar zones decreased, the grain size became larger, and in the as-welded zone, there was a little increment of both acicular ferrite and ferrite with second phase, with a consequent decrease of primary ferrite. These results showed that this type of alloy is very sensitive to the welding parameters and that very precise instructions must be given to secure the desired tensile properties in the all-weld-metal test specimens and under actual working conditions.« less

Flow and fracture behavior of aluminum alloy 6082-T6 at different tensile strain rates and triaxialities

PubMed Central

Chen, Xuanzhen; Peng, Shan; Yao, Song; Chen, Chao; Xu, Ping

2017-01-01

This study aims to investigate the flow and fracture behavior of aluminum alloy 6082-T6 (AA6082-T6) at different strain rates and triaxialities. Two groups of Charpy impact tests were carried out to further investigate its dynamic impact fracture property. A series of tensile tests and numerical simulations based on finite element analysis (FEA) were performed. Experimental data on smooth specimens under various strain rates ranging from 0.0001~3400 s-1 shows that AA6082-T6 is rather insensitive to strain rates in general. However, clear rate sensitivity was observed in the range of 0.001~1 s-1 while such a characteristic is counteracted by the adiabatic heating of specimens under high strain rates. A Johnson-Cook constitutive model was proposed based on tensile tests at different strain rates. In this study, the average stress triaxiality and equivalent plastic strain at facture obtained from numerical simulations were used for the calibration of J-C fracture model. Both of the J-C constitutive model and fracture model were employed in numerical simulations and the results was compared with experimental results. The calibrated J-C fracture model exhibits higher accuracy than the J-C fracture model obtained by the common method in predicting the fracture behavior of AA6082-T6. Finally, the Scanning Electron Microscope (SEM) of fractured specimens with different initial stress triaxialities were analyzed. The magnified fractographs indicate that high initial stress triaxiality likely results in dimple fracture. PMID:28759617

Effect of minor reactive metal additions on fracture toughness of iron: 12-percent nickel alloy at-196 deg and 25 deg C

NASA Technical Reports Server (NTRS)

Witzke, W. R.; Stephens, J. R.

1976-01-01

The slow bend precracked Charpy fracture toughness and tensile behavior of arc-melted and hot-rolled Fe-12Ni alloys containing up to 4 atomic percent reactive metal additions were determined at -196 C and 25 C after water quenching from three annealing temperatures. The fracture toughness of Fe-12Ni at -196 C was improved by small amounts of Al, Ce, Hf, La, Nb, Ta, Ti, V, Y, and Zr, but not by Si. Cryogenic toughness was improved up to 7.5 times that of binary Fe-12Ni and varied with the reactive metal, its concentration, and the annealing temperature.

PWHT effect on the mechanical properties of borated stainless steel GTA weldments for nuclear shield

NASA Astrophysics Data System (ADS)

Park, T.-D.; Baek, K.-K.; Kim, D.-S.

1997-02-01

To improve ductility of the welded joint of B-added austenitic stainless steels, postweld annealing effect has been studied. Gas Tungsten Arc (GTA) welds of AlSI 304-B3 stainless steel plates were annealed either at 700 1100°C for 1 hour or at 1100°C and 1200°C, for 1 7 hours. Bending test of the welds in as-welded and annealed conditions resulted in cracks propagated along the welds' fusion line except the one annealed at 1200°C, which revealed no cracks. Tensile elongations of the as-welded and annealed welds at the temperature up to 1000°C were only a half value of the base metal, whereas the welds annealed at 1200°C had fully recovered the original elongation of the base metal. Charpy impact test result exhibited the same tendency with annealing temperature. Elongated and accicular morphology of Y-(Cr, Fe)2B eutectic phase at the Partially Melted Heat Affected Zone (P.M.HAZ) of welds seemed to be responsible for the poor ductility of the welds. The welds annealed at 1200°C for various durations, on the other hand, showed fully spheroidized eutectic phases at the P.M.HAZ with its size increased with annealing durations, suggesting that postweld annealing at the temperature as high as 1200°C is required for the welds to have ductility matching that of base metal.

Fusion welding of a modern borated stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robino, C.V.; Cieslak, M.J.

1997-01-01

Experiments designed to assess the fabrication and service weldability of 304B4A borated stainless steel were conducted. Welding procedures and parameters for manual gas tungsten arc (GTA) welding, autogenous electron beam (EB) welding and filler-added EB welding were developed and found to be similar to those for austenitic stainless steels. Following the procedure development, four test welds were produced and evaluated by microstructural analysis and Charpy impact testing. Further samples were used for determination of the postweld heat treatment (PWHT) response of the welds. The fusion zone structure of welds in this alloy consists of primary austenite dendrites with an interdendriticmore » eutectic-like austenite/boride constituent. Welds also show an appreciable partially molten zone that consists of the austenite/boride eutectic surrounding unmelted austenite islands. The microstructure of the EB welds was substantially finer than that of the GTA welds, and boride coarsening was not observed in the solid state heat-affected zone (HAZ) of either weld type. The impact toughness of as-welded samples was found to be relatively poor, averaging less than 10 J for both GTA and EB welds. For fusion zone notched GTA and EB samples and centerline notched EB samples, fracture generally occurred along the boundary between the partially molten and solid-state regions of the HAZ. The results of the PWHT study were very encouraging, with typical values of the impact energy for HAZ notched samples approaching 40 J, or twice the minimum code-acceptable value.« less

Mehanical Properties of Electron Beam Welded Joints in Thick Gage CA6NM Stainless Steel

NASA Astrophysics Data System (ADS)

Sarafan, Sheida; Wanjara, Priti; Gholipour, Javad; Champliaud, Henri; Mathieu, Louis

2017-10-01

Design of hydroelectric turbine components requires high integrity welds (without detectable volumetric defects) in heavy gage sections of stainless steel materials, such as ASTM A743 grade CA6NM—a low carbon 13% Cr-4% Ni martensitic stainless steel that is manufactured in cast form. In this work, 90-mm-thick plates of CA6NM were joined using a single-pass autogenous electron beam (EB) welding process and the mechanical properties were evaluated in the as-welded condition to characterize the performance of the joints. The static tensile properties that were evaluated in two directions—transverse and longitudinal to the EB weld seam—demonstrated conformance of the joints with the requirements of the ASME Section IX standard. The Charpy impact energies of the EB welds—measured at -18 °C on samples with V-notch roots located in the fusion and heat-affected zones—met the minimum requirements of 27 J specified in ASME Section VIII standard. In addition, bend tests that were conducted on the entire weld cross section displayed no discontinuities on the tension side of the bent joints. Hence, the developed EB welding process was demonstrated to render high-performance joints and promises key advantages for industrialization, such as cost savings through reductions in consumable material, production time and labor intensity.

Phenolic Molding Compounds

NASA Astrophysics Data System (ADS)

Koizumi, Koji; Charles, Ted; de Keyser, Hendrik

Phenolic Molding Compounds continue to exhibit well balanced properties such as heat resistance, chemical resistance, dimensional stability, and creep resistance. They are widely applied in electrical, appliance, small engine, commutator, and automotive applications. As the focus of the automotive industry is weight reduction for greater fuel efficiency, phenolic molding compounds become appealing alternatives to metals. Current market volumes and trends, formulation components and its impact on properties, and a review of common manufacturing methods are presented. Molding processes as well as unique advanced techniques such as high temperature molding, live sprue, and injection/compression technique provide additional benefits in improving the performance characterisitics of phenolic molding compounds. Of special interest are descriptions of some of the latest innovations in automotive components, such as the phenolic intake manifold and valve block for dual clutch transmissions. The chapter also characterizes the most recent developments in new materials, including long glass phenolic molding compounds and carbon fiber reinforced phenolic molding compounds exhibiting a 10-20-fold increase in Charpy impact strength when compared to short fiber filled materials. The role of fatigue testing and fatigue fracture behavior presents some insight into long-term reliability and durability of glass-filled phenolic molding compounds. A section on new technology outlines the important factors to consider in modeling phenolic parts by finite element analysis and flow simulation.

Weld repair of carbon-moly coke drums without postweld heat treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, D.E.

1996-06-01

Investigations to evaluate weld repair of C-{1/2}Mo coke drums without postweld heat treatment (PWHT) are discussed in this paper. These investigations showed that shielded metal-arc welding (SMAW) without PWHT produced heat-affected zones (HAZ) and weld deposits with Charpy V-notch (CVN) impact toughness that exceeded the toughness of ex-service plate material. PWHT de-embrittles strain age-embrittled ex-service plate material. However, warming of drums to 200 F before putting in feed compensates for the omission of the de-embrittling PWHT. Additional testing showed that the de-embrittling PWHT did not significantly improve the fatigue properties of the ex-service plate material. As-welded SMAW repairs were foundmore » to be feasible for coke drums, and repairs have now been in service successfully for up to 2 years. The as-welded SMAW repairs were qualified on the basis of a 300 F preheat using small diameter electrodes for the first pass followed by larger diameter electrodes to temper the HAZ of the first pass. A half-bead technique was not used. Heat input is not precisely controlled as would be required for controlled deposition welding. Following the implementation of SMAW repairs without PWHT, the author extended the work to include as-welded repairs with automatic gas metal-arc welding (GMAW).« less

Use of Almond Shells and Rice Husk as Fillers of Poly(Methyl Methacrylate) (PMMA) Composites.

PubMed

Sabbatini, Alessandra; Lanari, Silvia; Santulli, Carlo; Pettinari, Claudio

2017-07-28

In recent years, wood fibres have often been applied as the reinforcement of thermoplastic materials, such as polypropylene, whereas their use in combination with thermosetting resin has been less widespread. This study concerns the production of PMMA-based composites by partly replacing alumina trihydrate (ATH) with wood waste fillers, namely rice husks and almond shells, which would otherwise be disposed by incineration. The amount of filler introduced was limited to 10% as regards rice husks and 10 or 15% almond shells, since indications provided by reactivity tests and viscosity measurements did not suggest the feasibility of total replacement of ATH. As a matter of fact, the introduction of these contents of wood waste filler in PMMA-based composite did not result in any significant deterioration of its mechanical properties (Charpy impact, Rockwell M hardness and flexural performance). Some reduction of these properties was only observed in the case of introduction of 15% almond shells. A further issue concerned the yellowing of the organic filler under exposure to UV light. On the other hand, a very limited amount of water was absorbed, never exceeding values around 0.6%, despite the significant porosity revealed by the filler's microscopic evaluation. These results are particularly interesting in view of the application envisaged for these composites, i.e., wood replacement boards.

Effect of Heat Input on Microstructure Evolution and Mechanical Properties in the Weld Heat-Affected Zone of 9Cr-2W-VTa Reduced Activation Ferritic-Martensitic Steel for Fusion Reactor

NASA Astrophysics Data System (ADS)

Moon, Joonoh; Lee, Chang-Hoon; Lee, Tae-Ho; Kim, Hyoung Chan

2015-01-01

The phase transformation and mechanical properties in the weld heat-affected zone (HAZ) of a reduced activation ferritic/martensitic steel were explored. The samples for HAZs were prepared using a Gleeble simulator at different heat inputs. The base steel consisted of tempered martensite and carbides through quenching and tempering treatment, whereas the HAZs consisted of martensite, δ-ferrite, and a small volume of autotempered martensite. The prior austenite grain size, lath width of martensite, and δ-ferrite fraction in the HAZs increased with increase in the heat input. The mechanical properties were evaluated using Vickers hardness and Charpy V-notch impact test. The Vickers hardness in the HAZs was higher than that in the base steel but did not change noticeably with increase in the heat input. The HAZs showed poor impact property due to the formation of martensite and δ-ferrite as compared to the base steel. In addition, the impact property of the HAZs deteriorated more with the increase in the heat input. Post weld heat treatment contributed to improve the impact property of the HAZs through the formation of tempered martensite, but the impact property of the HAZs remained lower than that of base steel.

Microstructures and impact toughness behavior of Al 5083 alloy processed by cryorolling and afterwards annealing

NASA Astrophysics Data System (ADS)

Singh, Dharmendra; Rao, P. Nageswara; Jayaganthan, R.

2013-08-01

The influence of rolling at liquid nitrogen temperature and annealing on the microstructure and mechanical properties of Al 5083 alloy was studied in this paper. Cryorolled samples of Al 5083 show significant improvements in strength and hardness. The ultimate tensile strength increases up to 340 MPa and 390 MPa for the 30% and 50% cryorolled samples, respectively. The cryorolled samples, with 30% and 50% reduction, were subjected to Charpy impact testing at various temperatures from -190°C to 100°C. It is observed that increasing the percentage of reduction of samples during cryorolling has significant effect on decreasing impact toughness at all temperatures by increasing yield strength and decreasing ductility. Annealing of samples after cryorolling shows remarkable increment in impact toughness through recovery and recrystallization. The average grain size of the 50% cryorolled sample (14 μm) after annealing at 350°C for 1 h is found to be finer than that of the 30% cryorolled sample (25 μm). The scanning electron microscopy (SEM) analysis of fractured surfaces shows a large-size dimpled morphology, resembling the ductile fracture mechanism in the starting material and fibrous structure with very fine dimples in cryorolled samples corresponding to the brittle fracture mechanism.

An Assessment of the Ductile Fracture Behavior of Hot Isostatically Pressed and Forged 304L Stainless Steel

NASA Astrophysics Data System (ADS)

Cooper, A. J.; Smith, R. J.; Sherry, A. H.

2017-05-01

Type 300 austenitic stainless steel manufactured by hot isostatic pressing (HIP) has recently been shown to exhibit subtly different fracture behavior from that of equivalent graded forged steel, whereby the oxygen remaining in the component after HIP manifests itself in the austenite matrix as nonmetallic oxide inclusions. These inclusions facilitate fracture by acting as nucleation sites for the initiation, growth, and coalescence of microvoids in the plastically deforming austenite matrix. Here, we perform analyses based on the Rice-Tracey (RT) void growth model, supported by instrumented Charpy and J-integral fracture toughness testing at ambient temperature, to characterize the degree of void growth ahead of both a V-notch and crack in 304L stainless steel. We show that the hot isostatically pressed (HIP'd) 304L steel exhibits a lower critical void growth at the onset of fracture than that observed in forged 304L steel, which ultimately results in HIP'd steel exhibiting lower fracture toughness at initiation and impact toughness. Although the reduction in toughness of HIP'd steel is not detrimental to its use, due to the steel's sufficiently high toughness, the study does indicate that HIP'd and forged 304L steel behave as subtly different materials at a microstructural level with respect to their fracture behavior.

Additive manufacturing of 316L stainless steel by electron beam melting for nuclear fusion applications

NASA Astrophysics Data System (ADS)

Zhong, Yuan; Rännar, Lars-Erik; Liu, Leifeng; Koptyug, Andrey; Wikman, Stefan; Olsen, Jon; Cui, Daqing; Shen, Zhijian

2017-04-01

A feasibility study was performed to fabricate ITER In-Vessel components by one of the metal additive manufacturing methods, Electron Beam Melting® (EBM®). Solid specimens of SS316L with 99.8% relative density were prepared from gas atomized precursor powder granules. After the EBM® process the phase remains as austenite and the composition has practically not been changed. The RCC-MR code used for nuclear pressure vessels provides guidelines for this study and tensile tests and Charpy-V tests were carried out at 22 °C (RT) and 250 °C (ET). This work provides the first set of mechanical and microstructure data of EBM® SS316L for nuclear fusion applications. The mechanical testing shows that the yield strength, ductility and toughness are well above the acceptance criteria and only the ultimate tensile strength of EBM® SS316L is below the RCC-MR code. Microstructure characterizations reveal the presence of hierarchical structures consisting of solidified melt pools, columnar grains and irregular shaped sub-grains. Lots of precipitates enriched in Cr and Mo are observed at columnar grain boundaries while no sign of element segregation is shown at the sub-grain boundaries. Such a unique microstructure forms during a non-equilibrium process, comprising rapid solidification and a gradient 'annealing' process due to anisotropic thermal flow of accumulated heat inside the powder granule matrix. Relations between process parameters, specimen geometry (total building time) and sub-grain structure are discussed. Defects are formed mainly due to the large layer thickness (100 μm) which generates insufficient bonding between a few of the adjacently formed melt pools during the process. Further studies should focus on adjusting layer thickness to improve the strength of EBM® SS316L and optimizing total building time.

Microstructural Modification of Sn-0.7Cu Solder Alloys by Fe/Bi-Addition for Achieving High Mechanical Performance

NASA Astrophysics Data System (ADS)

Ali, Bakhtiar; Sabri, Mohd Faizul Mohd; Said, Suhana Mohd; Mahdavifard, Mohammad Hossein; Sukiman, Nazatul Liana; Jauhari, Iswadi

2017-08-01

In this work, we studied the Fe/Bi-bearing tin-copper (Sn-0.7Cu) solders for their microstructural and mechanical properties. The microstructure was studied using field emission scanning electron microscopy (FESEM) with a backscattered electron (BSE) detector, x-ray diffraction (XRD) analysis, and energy-dispersive x-ray spectroscopy (EDX). The microstructure study showed that Fe forms very few FeSn2 intermetallic compounds (IMCs) and does not significantly alter the microstructure of Sn-0.7Cu, whereas Bi controls the size of inter-dendritic regions containing Cu6Sn5 and Ag3Sn IMCs of the alloy, as well as significantly refines its primary β-Sn dendrites. Moreover, Bi atoms dissolve in β-Sn matrix, which in turn strengthen the solder by the Bi solid solution strengthening mechanism. Such microstructural modification leads to significant improvements in various mechanical properties of the alloy, including shear strength, impact toughness, and hardness values. Shear tests were performed with a 0.25 mm/min shear speed. The results showed that shear strength improves from 16.57 MPa to 38.36 MPa with the addition of Fe/Bi to Sn-0.7Cu, raising by about 130%. The energy absorbed during impact tests was measured for samples with the help of a Charpy impact testing machine with a 5.4 m/s impact speed. The results revealed that the addition of Fe/Bi to Sn-0.7Cu improves its impact absorbed energy by over 35%, increasing it from 7.5 J to 10.3 J. Vickers hardness tests were carried out for the test samples with a 245.2 mN applied load and 10 s dwell time. The results showed that the hardness number improves from 9.89 to 24.13 with Fe/Bi to Sn-0.7Cu, increasing by about 140%.

Permanent effect of a cryogenic spill on fracture properties of structural steels

NASA Astrophysics Data System (ADS)

Keseler, H.; Westermann, I.; Kandukuri, S. Y.; Nøkleby, J. O.; Holmedal, B.

2015-12-01

Fracture analysis of a standard construction steel platform deck, which had been exposed to a liquid nitrogen spill, showed that the brittle fracture started at a flaw in the weld as a consequence of low-temperature embrittlement and thermal stresses experienced by the material. In the present study, the permanent effect of a cryogenic spill on the fracture properties of carbon steels has been investigated. Charpy V-notch impact testing was carried out at 0 °C using specimens, from the platform deck material. The average impact energy appeared to be below requirements only for transverse specimens. No pre-existing damage was found when examining the fracture surfaces and cross sections in the scanning electron microscope. Specimens of the platform deck material and a DOMEX S355 MCD carbon steel were tensile tested immersed in liquid nitrogen. Both steels showed a considerable increase in yield- and fracture strength and a large increase in the Lüders strain compared to the room temperature behavior. A cryogenic spill was simulated by applying a constant tensile force to the specimens for 10 min, at -196 C. Subsequent tensile tests at room temperature showed no significant influence on the stress-strain curve of the specimens. A small amount of microcracks were found after holding a DOMEX S355 MCD specimen at a constant force below the yield point. In a platform deck material tensile tested to fracture in liquid nitrogen, cracks associated with elongated MnS inclusions were found through the whole test region. These cracks probably formed as a result of the inclusions having a higher thermal contraction rate than the steel, causing decohesion at the inclusion-matrix interface on cooling. Simultaneous deformation may have caused formation of cracks. Both the microcracks and sulphide related damage may give permanently reduced impact energy after a cryogenic exposure.

An investigation of fracture toughness, fatigue-crack growth, sustained-load flaw growth, and impact properties of three pressure vessel steels

NASA Technical Reports Server (NTRS)

Hudson, C. M.; Newman, J. C., Jr.; Lewis, P. E.

1975-01-01

The elastic fracture toughness of the three steels is shown to not decrease significantly with decreasing temperature from room temperature to about 244 K (-20 F.). The elastic fracture toughness of the three steels increased with increasing specimen width and thickness. The fatigue-crack-growth data for all three steels fall into relatively narrow scatter bands on plots of rate against stress-intensity range. An equation is shown to predict the upper bounds of the scatter bands reasonably well. Charpy impact energies decreased with decreasing temperature in the nominal temperature range from room temperature to 244 K (-20 F). The nil-ductility temperatures of the steels are discussed.

Correlation of mechanical properties with metallurgical structure for 18Ni 200 grade maraging steel at room and cryogenic temperatures

NASA Technical Reports Server (NTRS)

Wagner, J. A.

1991-01-01

An extensive metallurgical study is presented which is intended to explain variations in the mechanical properties of Ni18 200 grade maraging steel in various product forms and orientations. Fracture toughness and Charpy impact values are found to decrease with decreasing temperature and be dependent on product form, specimen orientation, and metallurgical condition. Fatigue crack growth rates are dependent on temperature only. Fractographic analysis reveals that the decrease in toughness at -170 C is not associated with cleavage-type fracture morphology. Those specimens exhibiting low fracture toughness at room temperature or -170 C are found to have a significantly larger number of titanium-rich particles associated with dimple formation on the fracture surface.

Synthesis of Composit From Bamboo Fiber, Zeolite and Epoxy for Room Separation

NASA Astrophysics Data System (ADS)

Raihan Muhammad, Dhany; Basuki, Kris Tri; Wasito, Bangun; Suroso

2018-01-01

This research aims is to search a subtitute of the asbestos for the separator rontgen room using bamboo fiber filled with zeolite; which harden using epoxy it is all caused because the hazard of the asbestos to the human body. Bamboo stem degenerated using NaOH (20%) to get the bamboo fiber. Bamboo fiber added with CS2 (10 mL) to form xanthate cellulose. Xanthate Cellulose mixed with filler zeolite and harden of epoxy, layer by layer until getting the right width. The variant of the mass composition is 3: 0:1; 3: 0.25:0.75; 3 :0.5:0.5; 3: 0.75:0.25; 3: 1:0, and the variant of the temperature 28 °C 40 °C 60 °C 80 °C and 100 °C. The sample tested using microscopic method, impact test with Charpy method, corrosivity method, Electricity conduct method, thermal conduct method, and radiation resistance or attenuation method. The result shown the optimum composition of the composite it is at the variant 3 :0.5:0.5, with the optimum temperature is 40°C with the density of the sample is 1.5789 g/cm3. Impact resistance of the sample is 44 Joule. The Radiation resistance is 0.46, with the thermal conductivity of the sample is 0.016 Kkal/m.s.c. it shown that the sample is isolator. From the result is shown that the sample is can be a substitute for asbestos as material of the separator in the Rontgen room.

Experimental characterization of fatigue strength in butt welded joint considering the geometry and the effect of cooling rate of the weld

NASA Astrophysics Data System (ADS)

Arzola, Nelson; Hernández, Edgar

2017-05-01

In this work the experimental characterization of fatigue strength in butt welded joints considering the geometry and the post-weld cooling cycle was performed. ASTM A-36 structural steel was used as the base metal for the shielded metal arc welding process, with welding electrode E6013. Two experimental factors were established: weld bead geometry and the post-weld cooling rate. Two levels for each factor, the welding reinforcement (1 and 3 mm), and the rate of cooling, slow (quiet air) and fast (immersion in water) are evaluated respectively. For the uniaxial fatigue tests, 8 samples were selected for each treatment for a total of 32 specimens. The mechanical and fractomechanical properties of fusion zone, heat affected zone and base metal in relation to the analysis of failure mechanisms were analysed. The fatigue crack growth rates were estimated based on the counting of microstrations. Furthermore, experimental tests, such as uniaxial tension, microindentation hardness, Charpy impact and metallographic analysis, were made to know the influence of the experimental factors in the fatigue strength. On this research, about the 78.13% of the samples obtained a resistance higher than the recommended one by class FAT 100. The results showed that the geometry of the joint is the factor of greatest influence on fatigue strength for butt welded joints; the greater the weld reinforcement the lower the fatigue strength of the joint. Although it is also important to consider other geometric factors of less impact as it is the weld toe radius and the welding chord width.

Tensile properties and impact toughness of S30408 stainless steel and its welded joints at cryogenic temperatures

NASA Astrophysics Data System (ADS)

Ding, Huiming; Wu, Yingzhe; Lu, Qunjie; Xu, Ping; Zheng, Jinyang; Wei, Lijun

2018-06-01

Designing a cryogenic pressure vessel based on the mechanical properties of the austenitic stainless steel (ASS) at its cryogenic operating temperature fully utilizes the potential of the material at low temperatures, resulting in lightweight and compact products. A series of tensile tests and impact tests were carried out in a wide range of 77-293 K, to investigate the mechanical properties of S30408 base metal (BM) and welded joints (WJ) at cryogenic temperatures. As the temperature decreases, yield stress (Rp0.2) and ultimate tensile stress (Rm) increase significantly thanks to the low-temperature strengthening effects. To estimate strengths at cryogenic temperatures, quadratic polynomial model was used to accurately predict the variations of Rp0.2 and Rm from 77 K to 293 K. As an important phase in the WJ, ferrite presents a radial pattern and an inhomogeneity in the WJ's cross-section. Due to the formation of ferrite in the WJ, the WJ has higher Rp0.2 and lower Rm , Charpy absorbed energy and lateral expansion compared with the BM. Strain-induced martensite transformation is an important role influencing the deformation of ASS at low temperatures. In this study, less martensite amount was measured in the weldment zone with higher Nickel equivalents which stabilize the austenite phase at cryogenic temperatures. Additionally, due to higher ferrite content and more precipitates forming, the SAW joints has lower Rm and impact toughness than PAW + GTAW joints. To ensure the structural integrity and safety, the PAW + GTAW method should be chosen and ferrite content be controlled.

Effect of Post-weld Heat Treatment on the Mechanical Properties of Supermartensitic Stainless Steel Deposit

NASA Astrophysics Data System (ADS)

Zappa, Sebastián; Svoboda, Hernán; Surian, Estela

2017-02-01

Supermartensitic stainless steels have good weldability and adequate tensile property, toughness and corrosion resistance. They have been developed as an alternative technology, mainly for oil and gas industries. The final properties of a supermartensitic stainless steel deposit depend on its chemical composition and microstructure: martensite, tempered martensite, ferrite, retained austenite and carbides and/or nitrides. In these steels, the post-weld heat treatments (PWHTs) are usually double tempering ones, to ensure both complete tempering of martensite and high austenite content, to increase toughness and decrease hardness. The aim of this work was to study the effect of post-weld heat treatments (solution treatment with single and double tempering) on the mechanical properties of a supermartensitic stainless steel deposit. An all-weld metal test coupon was welded according to standard ANSI/AWS A5.22-95 using a GMAW supermartensitic stainless steel metal cored wire, under gas shielding. PWHTs were carried out varying the temperature of the first tempering treatment with and without a second tempering one, after solution treatment. All-weld metal chemical composition analysis, metallurgical characterization, hardness and tensile property measurements and Charpy-V tests were carried out. There are several factors which can be affected by the PWHTs, among them austenite content is a significant one. Different austenite contents (0-42%) were found. Microhardness, tensile property and toughness were affected with up to 15% of austenite content, by martensite tempering and carbide precipitation. The second tempering treatment seemed not to have had an important effect on the mechanical properties measured in this work.

Processing Issues for Preliminary Melts of the Intermetallic Compound 60-NITINOL

NASA Technical Reports Server (NTRS)

Stanford, Malcolm K.; Thomas, Fransua; DellaCorte, Christopher

2012-01-01

The effect of various high temperature heat treatments and cooling rates on the hardness of cast 60-NITINOL (60wt%Ni- 40wt%Ti) was studied. The hardness ranged from approximately 33 HRC for annealed specimens to 63 HRC for water quenched specimens. Aging did not have a further effect on the hardness of the heat-treated and quenched material. The issue of material contamination and its possible effect on quench cracking during heat treatment above 1000 C was explored. The Charpy impact energy of the material was found to be relatively low (ranging from 0.4 to 1.0 J) and comparable to that of cast magnesium. Selection of service environments and applications for this material based on these findings should consider the processing route by which it was produced.

Epoxy Resin Composite Based on Functional Hybrid Fillers

PubMed Central

Oleksy, Mariusz; Szwarc-Rzepka, Karolina; Heneczkowski, Maciej; Oliwa, Rafał; Jesionowski, Teofil

2014-01-01

A study was carried out involving the filling of epoxy resin (EP) with bentonites and silica modified with polyhedral oligomeric silsesquioxane (POSS). The method of homogenization and the type of filler affect the functional and canceling properties of the composites was determined. The filler content ranged from 1.5% to 4.5% by mass. The basic mechanical properties of the hybrid composites were found to improve, and, in particular, there was an increase in tensile strength by 44%, and in Charpy impact strength by 93%. The developed hybrid composites had characteristics typical of polymer nanocomposites modified by clays, with a fine plate morphology of brittle fractures observed by SEM, absence of a plate separation peak in Wide Angles X-ray Scattering (WAXS) curves, and an exfoliated structure observed by TEM. PMID:28788177

Partial-Isothermally-Treated Low Alloy Ultrahigh Strength Steel with Martensitic/Bainitic Microstructure

NASA Astrophysics Data System (ADS)

Luo, Quanshun; Kitchen, Matthew; Patel, Vinay; Filleul, Martin; Owens, Dave

We introduce a new strengthening heat treatment of a Ni-Cr-Mo-V alloyed spring steel by partial isothermal salt-bath and subsequent air-cooling and tempering. Detailed isothermal treatments were made at temperatures below or above the Ms point (230°C). The salt bath time was controlled between 10 and 80 minutes. Through the new treatment, the candidate steel developed ultrahigh tensile strength 2,100 MPa, yield strength 1,800 MPa, elongation 8-10 %, hardness 580-710 HV, and V-notch Charpy toughness 10-12 J. Optical and electron microscopic observations and X-ray diffraction revealed multi-phase microstructures of bainitic/martensitic ferrites, fine carbide precipitates and retained austenite. Carbon partitioning during the bainitic/martensitic transformation was investigated for its remarkable influence on the strengthening mechanism.

Results of crack-arrest tests on irradiated a 508 class 3 steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iskander, S.K.; Milella, P.P.; Pini, M.A.

1998-02-01

Ten crack-arrest toughness values for irradiated specimens of A 508 class 3 forging steel have been obtained. The tests were performed according to the American Society for Testing and Materials (ASTM) Standard Test Method for Determining Plane-Strain Crack-Arrest Fracture Toughness, K{sub la} of Ferritic Steels, E 1221-88. None of these values are strictly valid in all five ASTM E 1221-88 validity criteria. However, they are useful when compared to unirradiated crack-arrest specimen toughness values since they show the small (averaging approximately 10{degrees}C) shifts in the mean and lower-bound crack-arrest toughness curves. This confirms that a low copper content in ASTMmore » A 508 class 3 forging material can be expected to result in small shifts of the transition toughness curve. The shifts due to neutron irradiation of the lower bound and mean toughness curves are approximately the same as the Charpy V-notch (CVN) 41-J temperature shift. The nine crack-arrest specimens were irradiated at temperatures varying from 243 to 280{degrees}C, and to a fluence varying from 1.7 to 2.7 x 10{sup 19} neutrons/cm{sup 2} (> 1 MeV). The test results were normalized to reference values that correspond to those of CVN specimens irradiated at 284{degrees}C to a fluence of 3.2 x 10{sup 19} neutrons/cm{sup 2} (> 1 MeV) in the same capsule as the crack-arrest specimens. This adjustment resulted in a shift to lower temperatures of all the data, and in particular moved two data points that appeared to lie close to or lower than the American Society of Mechanical Engineers K{sub la} curve to positions that seemed more reasonable with respect to the remaining data. A special fixture was designed, fabricated, and successfully used in the testing. For reasons explained in the text, special blocks to receive the Oak Ridge National Laboratory clip gage were designed, and greater-than-standard crack-mouth opening displacements measured were accounted for. 24 refs., 13 figs., 12 tabs.« less

Control of Microstructures and the Practical Properties of API X80 Grade Heavy-Wall High-Frequency Electric Resistance-Welded Pipe with Excellent Low-Temperature Toughness

NASA Astrophysics Data System (ADS)

Goto, Sota; Nakata, Hiroshi; Toyoda, Shunsuke; Okabe, Takatoshi; Inoue, Tomohiro

2017-10-01

This paper describes development of heavy-walled API X80 grade high-frequency electric resistance-welded (HFW) line pipes and conductor-casing pipes with wall thicknesses up to 20.6 mm. A fine bainitic-ferrite microstructure, which is preferable for low-temperature toughness, was obtained by optimizing the carbon content and applying the thermomechanical controlled hot-rolling process. As a result, the Charpy ductile-brittle transition temperature (DBTT) was well below 227 K (-46 °C) in the base metal of the HFW line pipe. When the controlled hot-rolling ratio (CR) was increased from 23 to 48 pct, the area average grain size decreased from 15 to 8 μm. The dependence of CTOD properties on CR was caused by the largest grain which is represented by the area average grain size. No texture development due to the increase of CR from 23 to 48 pct was observed. In addition, because controlled in-line heat treatment of the longitudinal weld seam also produced the fine bainitic-ferrite microstructure at the weld seam, DBTT was lower than 227 K (-46 °C) at the weld portion. The developed pipes showed good girth weldability without preheat treatment, and fracture in the tensile test initiated from the base metal in all cases.

Hybrid Laser-Arc Welding of 10-mm-Thick Cast Martensitic Stainless Steel CA6NM: As-Welded Microstructure and Mechanical Properties

NASA Astrophysics Data System (ADS)

Mirakhorli, Fatemeh; Cao, Xinjin; Pham, Xuan-Tan; Wanjara, Priti; Fihey, Jean-Luc

2016-07-01

Cast CA6NM martensitic stainless steel plates, 10 mm in thickness, were welded using hybrid laser-arc welding. The effect of different welding speeds on the as-welded joint integrity was characterized in terms of the weld bead geometry, defects, microstructure, hardness, ultimate tensile strength, and impact energy. Significant defects such as porosity, root humping, underfill, and excessive penetration were observed at a low welding speed (0.5 m/min). However, the underfill depth and excessive penetration in the joints manufactured at welding speeds above 0.75 m/min met the specifications of ISO 12932. Characterization of the as-welded microstructure revealed untempered martensite and residual delta ferrite dispersed at prior-austenite grain boundaries in the fusion zone. In addition, four different heat-affected zones in the weldments were differentiated through hardness mapping and inference from the Fe-Cr-Ni ternary phase diagram. The tensile fracture occurred in the base metal for all the samples and fractographic analysis showed that the crack path is within the martensite matrix, along primary delta ferrite-martensite interfaces and within the primary delta ferrite. Additionally, Charpy impact testing demonstrated slightly higher fracture energy values and deeper dimples on the fracture surface of the welds manufactured at higher welding speeds due to grain refinement and/or lower porosity.

Enhancement of Impact Toughness by Delamination Fracture in a Low-Alloy High-Strength Steel with Al Alloying

NASA Astrophysics Data System (ADS)

Sun, Junjie; Jiang, Tao; Liu, Hongji; Guo, Shengwu; Liu, Yongning

2016-12-01

The effect of delamination toughening of martensitic steel was investigated both at room and low temperatures [253 K and 233 K (-20 °C and -40 °C)]. Two low-alloy martensitic steels with and without Al alloying were both prepared. Layered structure with white band and black matrix was observed in Al alloyed steel, while a homogeneous microstructure was displayed in the steel without Al. Both steels achieved high strength (tensile strength over 1600 MPa) and good ductility (elongation over 11 pct), but they displayed stark contrasts on impact fracture mode and Charpy impact energy. Delamination fracture occurred in Al alloyed steel and the impact energies were significantly increased both at room temperature (from 75 to 138 J, i.e., nearly improved up to 2 times) and low temperatures [from 47.9 to 71.3 J at 233 K (-40 °C)] compared with the one without Al. Alloying with Al promotes the segregation of Cr, Mn, Si and C elements to form a network structure, which is martensite with higher carbon content and higher hardness than that of the matrix. And this network structure evolved into a band structure during the hot rolling process. The difference of yield stress between the band structure and the matrix gives rise to a delamination fracture during the impact test, which increases the toughness greatly.

Use of Almond Shells and Rice Husk as Fillers of Poly(Methyl Methacrylate) (PMMA) Composites

PubMed Central

Sabbatini, Alessandra; Lanari, Silvia; Santulli, Carlo

2017-01-01

In recent years, wood fibres have often been applied as the reinforcement of thermoplastic materials, such as polypropylene, whereas their use in combination with thermosetting resin has been less widespread. This study concerns the production of PMMA-based composites by partly replacing alumina trihydrate (ATH) with wood waste fillers, namely rice husks and almond shells, which would otherwise be disposed by incineration. The amount of filler introduced was limited to 10% as regards rice husks and 10 or 15% almond shells, since indications provided by reactivity tests and viscosity measurements did not suggest the feasibility of total replacement of ATH. As a matter of fact, the introduction of these contents of wood waste filler in PMMA-based composite did not result in any significant deterioration of its mechanical properties (Charpy impact, Rockwell M hardness and flexural performance). Some reduction of these properties was only observed in the case of introduction of 15% almond shells. A further issue concerned the yellowing of the organic filler under exposure to UV light. On the other hand, a very limited amount of water was absorbed, never exceeding values around 0.6%, despite the significant porosity revealed by the filler’s microscopic evaluation. These results are particularly interesting in view of the application envisaged for these composites, i.e., wood replacement boards. PMID:28773234

Study of helium embrittlement in boron doped EUROFER97 steels

NASA Astrophysics Data System (ADS)

Gaganidze, E.; Petersen, C.; Aktaa, J.

2009-04-01

To simulate helium effects in Reduced Activation Ferritic/Martensitic steels, experimental heats ADS2, ADS3 and ADS4 with the basic composition of EUROFER97 (9%Cr-WVTa) were doped with different contents of natural boron and separated 10B-isotope (0.008-0.112 wt.%) and irradiated in High Flux Reactor (HFR) Petten up to 16.3 dpa at 250-450 °C and in Bor-60 fast reactor in Dimitrovgrad up to 31.8 dpa at 332-338 °C. The embrittlement and hardening are investigated by instrumented Charpy-V tests with subsize specimens. Complete burn-up of 10B isotope under neutron irradiation in HFR Petten led to generation of 84, 432 and 5580 appm He and partial boron-to-helium transformation in Bor-60 led to generation of 9, 46, 880 appm He in ADS2, ADS3 and ADS4 heats, respectively. At low irradiation temperatures Tirr ⩽ 340 °C the boron doped steels show progressive embrittlement with increasing helium amount. Irradiation induced DBTT shift of EUROFER97 based heat doped with 1120 wppm separated 10B isotope could not be quantified due to large embrittlement found in the investigated temperature range. At Tirr ⩽ 340 °C helium induced extra embrittlement is attributed to material hardening induced by helium bubbles and described in terms of phenomenological model.

Correlation of the thermodynamic calculation and the experimental observation of Ni-Mo-Cr low alloy steel changing Ni, Mo, and Cr contents

NASA Astrophysics Data System (ADS)

Park, Sang-Gyu; Kim, Min-Chul; Lee, Bong-Sang; Wee, Dang-Moon

2010-12-01

SA508 Gr.4N Ni-Mo-Cr low alloy steel has improved fracture toughness and strength compared to commercial low alloy steels such as SA508 Gr.3 Mn-Mo-Ni low alloy steel, which has less than 1% Ni. Higher strength and fracture toughness of low alloy steels can be achieved by increasing the Ni and Cr contents. In this study, the effects of the alloying elements of Ni and Cr on the microstructural characteristics and mechanical properties of SA508 Gr.4N Ni-Mo-Cr low alloy steel are evaluated. Changes in the stable phases of SA508 Gr.4N low alloy steel with these alloying elements were evaluated using thermodynamic calculation software. These values were then compared with the observed microstructural results. Additionally, tensile tests and Charpy impact test were carried out to evaluate the mechanical properties. The thermodynamic calculations show that Ni mainly affects the change of the matrix phase of γ and α rather than the carbide phase. Contrary to the Ni effect, Cr and Mo primarily affect the precipitation behavior of the carbide phases of Cr 23C 6, Cr 7C 3 and Mo 2C. In the microscopic observations, the lath martensitic structure becomes finer as the Ni content increases without affecting the carbides. When the Cr content decreases, the Cr carbide becomes unstable and carbide coarsening occurs. Carbide Mo 2C in the form of fine needles were observed in the high-Mo alloy. Greater strength was obtained after additions of Ni and Mo and the transition properties were improved as the Ni and Cr contents increased. These results were correlated with the thermodynamic calculation results.

Advances in cleavage fracture modelling in steels: Micromechanical, numerical and multiscale aspects

NASA Astrophysics Data System (ADS)

Pineau, André; Tanguy, Benoît

2010-04-01

Brittle cleavage fracture remains one of the major concerns for structural integrity assessment. The main characteristics of this mode of failure in relation to the stress field ahead of a crack, tip are described in the introduction. The emphasis is laid on the physical origins of scatter and the size effect observed in ferritic steels. It is shown that cleavage fracture is controlled by physical events occurring at different scales: initiation at (sub)micrometric particles, propagation across grain boundaries (10-50 microns) and final fracture at centimetric scale. The two first scales are detailed in this paper. The statistical origin of cleavage is described quantitatively from both microstructural defects and stress-strain heterogeneities due to crystalline plasticity at the grain scale. Existing models are applied to the prediction of the variation of Charpy fracture toughness with temperature.

Radiation Embrittlement Archive Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Klasky, Hilda B; Bass, Bennett Richard; Williams, Paul T

2013-01-01

The Radiation Embrittlement Archive Project (REAP), which is being conducted by the Probabilistic Integrity Safety Assessment (PISA) Program at Oak Ridge National Laboratory under funding from the U.S. Nuclear Regulatory Commission s (NRC) Office of Nuclear Regulatory Research, aims to provide an archival source of information about the effect of neutron radiation on the properties of reactor pressure vessel (RPV) steels. Specifically, this project is an effort to create an Internet-accessible RPV steel embrittlement database. The project s website, https://reap.ornl.gov, provides information in two forms: (1) a document archive with surveillance capsule(s) reports and related technical reports, in PDF format,more » for the 104 commercial nuclear power plants (NPPs) in the United States, with similar reports from other countries; and (2) a relational database archive with detailed information extracted from the reports. The REAP project focuses on data collected from surveillance capsule programs for light-water moderated, nuclear power reactor vessels operated in the United States, including data on Charpy V-notch energy testing results, tensile properties, composition, exposure temperatures, neutron flux (rate of irradiation damage), and fluence, (Fast Neutron Fluence a cumulative measure of irradiation for E>1 MeV). Additionally, REAP contains data from surveillance programs conducted in other countries. REAP is presently being extended to focus on embrittlement data analysis, as well. This paper summarizes the current status of the REAP database and highlights opportunities to access the data and to participate in the project.« less

Effects of Zr, Ti, and Al Additions on Nonmetallic Inclusions and Impact Toughness of Cast Low-Alloy Steel

NASA Astrophysics Data System (ADS)

Bizyukov, Pavel V.; Giese, Scott R.

2017-04-01

A microalloying of the low-carbon and low-alloy cast steel was conducted with Zr, Ti, and Al that were added to the steel in four combinations. After heat treatment, the samples were tested for impact toughness at room temperature using the Charpy method. The highest values of impact toughness were obtained in the group treated with Zr, while Zr-Ti and Zr-Ti-Al groups showed moderate toughness values; the lowest values were observed in the Zr-Al group. Difference among the treatment groups was observed in the fracture mechanisms, morphology, and area distribution of the inclusions. High toughness values achieved in the trials treated with zirconium corresponded with smooth ductile fracture. The metal treated with a combination of zirconium and titanium had a relatively small area occupied by inclusions, but its toughness was also moderate. Lowest impact toughness values corresponded with the larger area occupied by the inclusions in the trials treated with aluminum. Also, a connection between the solubility product [Al][N] and impact toughness was established. The study also provides a qualitative description and quantitative analysis of the nonmetallic inclusions formation as a result of microalloying treatment. The precipitation sequence of the inclusions was described based on the thermochemical calculations for the nonmetallic compounds discovered in the experimental steel. A description of the size distribution, morphology, and composition was conducted for the oxides, nitrides, sulfides, and multiphase particles.

Self-healing of damage in fibre-reinforced polymer-matrix composites.

PubMed

Hayes, S A; Zhang, W; Branthwaite, M; Jones, F R

2007-04-22

Self-healing resin systems have been discussed for over a decade and four different technologies had been proposed. However, little work on their application as composite matrices has been published although this was one of the stated aims of the earliest work in the field. This paper reports on the optimization of a solid-state self-healing resin system and its subsequent use as a matrix for high volume fraction glass fibre-reinforced composites. The resin system was optimized using Charpy impact testing and repeated healing, while the efficiency of healing in composites was determined by analysing the growth of delaminations following repeated impacts with or without a healing cycle. To act as a reference, a non-healing resin system was subjected to the same treatments and the results are compared with the healable system. The optimized resin system displays a healing efficiency of 65% after the first healing cycle, dropping to 35 and 30% after the second and third healing cycles, respectively. Correction for any healability due to further curing showed that approximately 50% healing efficiency could be achieved with the bisphenol A-based epoxy resin containing 7.5% of polybisphenol-A-co-epichlorohydrin. The composite, on the other hand, displays a healing efficiency of approximately 30%. It is therefore clear that the solid-state self-healing system is capable of healing transverse cracks and delaminations in a composite, but that more work is needed to optimize matrix healing within a composite and to develop a methodology for assessing recovery in performance.

Vanadium and columbium additions in pressure vessel steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, P.; Somers, B.R.; Pense, A.W.

1994-09-01

A statistically designed series of vanadium and columbium microalloyed C-Mn HSLA steels was used for an investigation of heat-affected zone (HAZ) toughness in post weld heat treated (PWHT) multi-pass welds. The vanadium additions were in the range 0.005 to 0.097 Wt.% and the columbium additions were in the range 0.004 to 0.06 Wt.% GMAW processes with welding heat inputs of 3kJ/mm and 5kJ/mm and post-weld heat treatments at 620 C for 2 10 hours were employed. A degradation of the HAZ toughness with additions of microalloy elements V and Cb in the as-welded and PWHT conditions was revealed. The 50more » Joule (37 ft-lb) transition temperature (TT50J) for HAZs in all weld conditions correlated with maximum HAZ hardness. Increases in HAZ hardness and TT50J caused by PWHT were observed. Hence PWHT in some situations may not beneficial for V/Cb microalloyed HLSA steels. The randomly distributed precipitation of V and Cb carbides (V, Cb)C, including dislocation precipitation and matrix precipitation with particle sizes of 5--15 nm, is the predominant alloy carbide precipitate morphology in these steels. The crack initiation sites in Charpy specimens of HAZs tested at the approximate transition temperature are shifted from the highest stress triaxiality, mid-specimen location to an off center higher hardness location. This is found to be characteristic of fracture in the multipass HAZ of the microalloyed steel.« less

Study of Aging-Induced Degradation of Fracture Resistance of Alloy 617 Toward High-Temperature Applications

NASA Astrophysics Data System (ADS)

Singh, Aditya Narayan; Moitra, A.; Bhaskar, Pragna; Sasikala, G.; Dasgupta, Arup; Bhaduri, A. K.

2017-07-01

For the Alloy 617, the effect of aging on the fracture energy degradation has been investigated after aging for different time periods at 1023 K (750 °C). A sharp reduction in impact energy (by 55 pct vis-à-vis the as-received material) after 1000 hours of aging, as evaluated from room-temperature Charpy impact tests, has been observed. Further aging up to 10,000 hours has led to a degradation of fracture energy up to 78 pct. Fractographic examinations using scanning electron microscopy (SEM) have revealed a change in fracture mode from fibrous-ductile for the un-aged material to intergranular mode for the aged one. The extent of intergranular fracture increases with the increasing aging time, indicating a tendency of the material to undergo grain boundary embrittlement over long-term aging. Analysis of the transmission electron microscopy (TEM) micrographs along with selected area diffraction (SAD) patterns for the samples aged at 10,000 hours revealed finely dispersed γ' precipitates of size 30 to 40 nm, rich in Al and Ti, along with extensive precipitation of M23C6 at the grain boundaries. In addition, the presence of Ni3Si of size in the range of 110 to 120 nm also has been noticed. The extensive precipitation of M23C6 at the grain boundaries have been considered as a major reason for aging-induced embrittlement of this material.

Welding-Induced Microstructure Evolution of a Cu-Bearing High-Strength Blast-Resistant Steel

NASA Astrophysics Data System (ADS)

Caron, Jeremy L.; Babu, Sudarsanam Suresh; Lippold, John C.

2011-12-01

A new high strength, high toughness steel containing Cu for precipitation strengthening was recently developed for naval, blast-resistant structural applications. This steel, known as BlastAlloy160 (BA-160), is of nominal composition Fe-0.05C-3.65Cu-6.5Ni-1.84Cr-0.6Mo-0.1V (wt pct). The evident solidification substructure of an autogenous gas tungsten arc (GTA) weld suggested fcc austenite as the primary solidification phase. The heat-affected zone (HAZ) hardness ranged from a minimum of 353 HV in the coarse-grained HAZ (CGHAZ) to a maximum of 448 HV in the intercritical HAZ (ICHAZ). After postweld heat treatment (PWHT) of the spot weld, hardness increases were observed in the fusion zone (FZ), CGHAZ, and fine-grained HAZ (FGHAZ) regions. Phase transformation and metallographic analyses of simulated single-pass HAZ regions revealed lath martensite to be the only austenitic transformation product in the HAZ. Single-pass HAZ simulations revealed a similar hardness profile for low heat-input (LHI) and high heat-input (HHI) conditions, with higher hardness values being measured for the LHI samples. The measured hardness values were in good agreement with those from the GTA weld. Single-pass HAZ regions exhibited higher Charpy V-notch impact toughness than the BM at both test temperatures of 293 K and 223 K (20 °C and -50 °C). Hardness increases were observed for multipass HAZ simulations employing an initial CGHAZ simulation.

Environmentally Friendly Compatibilizers from Soybean Oil for Ternary Blends of Poly(lactic acid)-PLA, Poly(ε-caprolactone)-PCL and Poly(3-hydroxybutyrate)-PHB.

PubMed

Garcia-Campo, María Jesús; Quiles-Carrillo, Luis; Masia, Jaime; Reig-Pérez, Miguel Jorge; Montanes, Nestor; Balart, Rafael

2017-11-22

Ternary blends of poly(lactic acid) (PLA), poly(3-hydroxybutyrate) (PHB) and poly(ε-caprolactone) (PCL) with a constant weight percentage of 60%, 10% and 30% respectively were compatibilized with soybean oil derivatives epoxidized soybean oil (ESO), maleinized soybean oil (MSO) and acrylated epoxidized soybean oil (AESO). The potential compatibilization effects of the soybean oil-derivatives was characterized in terms of mechanical, thermal and thermomechanical properties. The effects on morphology were studied by field emission scanning electron microscopy (FESEM). All three soybean oil-based compatibilizers led to a noticeable increase in toughness with a remarkable improvement in elongation at break. On the other hand, both the tensile modulus and strength decreased, but in a lower extent to a typical plasticization effect. Although phase separation occurred, all three soybean oil derivatives led somewhat to compatibilization through reaction between terminal hydroxyl groups in all three biopolyesters (PLA, PHB and PCL) and the readily reactive groups in the soybean oil derivatives, that is, epoxy, maleic anhydride and acrylic/epoxy functionalities. In particular, the addition of 5 parts per hundred parts of the blend (phr) of ESO gave the maximum elongation at break while the same amount of MSO and AESO gave the maximum toughness, measured through Charpy's impact tests. In general, the herein-developed materials widen the potential of ternary PLA formulations by a cost effective blending method with PHB and PCL and compatibilization with vegetable oil-based additives.

Dynamic stress analysis of smooth and notched fiber composite flexural specimens

NASA Technical Reports Server (NTRS)

Murthy, P. L. N.; Chamis, C. C.

1984-01-01

A detailed analysis of the dynamic stress field in smooth and notched fiber composite (Charpy-type) specimens is reported in this paper. The analysis is performed with the aid of the direct transient response analysis solution sequence of MSC/NASTRAN. Three unidirectional composites were chosen for the study. They are S-Glass/Epoxy, Kevlar/Epoxy and T-300/Epoxy composite systems. The specimens are subjected to an impact load which is modeled as a triangular impulse with a maximum of 2000 lb and a duration of 1 ms. The results are compared with those of static analysis of the specimens subjected to a peak load of 2000 lb. For the geometry and type of materials studied, the static analysis results gave close conservative estimates for the dynamic stresses. Another interesting inference from the study is that the impact induced effects are felt by S-Glass/Epoxy specimens sooner than Kevlar/Epoxy or T-300/Epoxy specimens.

Current understanding of the effects of enviromental and irradiation variables on RPV embrittlement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Odette, G.R.; Lucas, G.E.; Wirth, B.

1997-02-01

Radiation enhanced diffusion at RPV operating temperatures around 290{degrees}C leads to the formation of various ultrafine scale hardening phases, including copper-rich and copper-catalyzed manganese-nickel rich precipitates. In addition, defect cluster or cluster-solute complexes, manifesting a range of thermal stability, develop under irradiation. These features contribute directly to hardening which in turn is related to embrittlement, manifested as shifts in Charpy V-notch transition temperature. Models based on the thermodynamics, kinetics and micromechanics of the embrittlement processes have been developed; these are broadly consistent with experiment and rationalize the highly synergistic effects of most important irradiation (temperature, flux, fluence) and metallurgical (copper,more » nickel, manganese, phosphorous and heat treatment) variables on both irradiation hardening and recovery during post-irradiation annealing. A number of open questions remain which can be addressed with a hierarchy of new theoretical and experimental tools.« less

Weldability evaluation of high tensile plates using GMAW process

NASA Astrophysics Data System (ADS)

Datta, R.; Mukerjee, D.; Rohira, K. L.; Veeraraghavan, R.

1999-08-01

High tensile plates, SAILMA-450 high impact (HI) (yield strength, 45 kg/mm2 minimum; ultimate tensile strength, 57 kg/mm2 minimum; elongation, 19% minimum; Charpy impact energy 2.0 kg.m at -20 °C minimum) were successfully developed at the Steel Authority of India Ltd., up to 32 mm plate thickness. Since then the steel has been extensively used for the fabrication of impellers, bridges, excavators, and mining machineries, where welding is an important processing step. The present study deals with the weldability properties of SAILMA-450 HI plates employing the gas metal arc welding process and carbon dioxide gas. Implant and elastic restraint cracking tests were conducted to assess the cold cracking resistance of the weld joint under different welding conditions. The static fatigue limit values were found to be in excess of minimum specified yield strength at higher heat input levels (9.4 and 13.0 kJ/cm), indicating adequate cold cracking resistance. The critical restraint intensities, K cr, were found to vary between 720 and 1280 kg/mm2, indicating that the process can be utilized for fabrication of structures involving moderate to low restraint intensities (200 to 1000 kg/mm2). Lamellar tear tests conducted using full thickness plates at heat input levels ranging from 10 to 27 kJ/cm showed no incidence of lamellar tear upon visual, ultrasonic, and four-section macroexamination. These tests were repeated using machined plates, such that the midthickness of the plates (segregated zone) corresponded to the heat affected zone of the weld. No cracks were observed, indicating good lamellar tear resistance of the weld joint. Optimized welding conditions were formulated based on these tests. The weld joint was subjected to extensive tests to assess the physical properties and soundness of the weld joint. The weld joint exhibited good strength (64.7 kg/mm2) and impact toughness (5.7 and 3.5 kg.m at -20 °C for weld metal and heat affected zone properties. Crack tip opening displacement (CTOD) tests carried out for parent metal, heat-affected zone, and weld metal resulted in δm values of 0.41, 0.40, and 0.34 mm, respectively, which indicates adequate resistance to cleavage fracture. It was concluded that the weld joint conforms to the requirements of SAILMA-450 HI specification and ensures a high integrity of the fabricated products.

Influence of incorporation of ZrO2 nanoparticles on the repair strength of polymethyl methacrylate denture bases

PubMed Central

Gad, Mohammed M; Rahoma, Ahmed; Al-Thobity, Ahmad M; ArRejaie, Aws S

2016-01-01

Background Repeated fracture of the denture base is a common problem in prosthodontics, and it represents a nuisance and a time sink for the clinician. Therefore, the possibility of increasing repair strength using new reinforcement materials is of great interest to prosthodontists. Aim of the study This study aimed to evaluate the effects of incorporation of zirconia nanoparticles (nano-ZrO2) on the flexural strength and impact strength of repaired polymethyl methacrylate (PMMA) denture bases. Materials and methods One hundred eighty specimens of heat-polymerized acrylic resin were fabricated (90 for each test) and divided into three main groups: one control group (intact specimens) and two groups divided according to surface design (45° bevels and butt joints), in which specimens were prepared in pairs to create 2.5 mm gaps. Nano-ZrO2 was added to repair resin in 2.5 wt%, 5 wt%, and 7.5 wt% concentrations of acrylic powder. A three-point bending test was used to measure flexural strength, and a Charpy-type test was used to measure impact strength. Scanning electron microscopy was used to analyze the fracture surfaces and nano-ZrO2 distribution. The results were analyzed with a paired sample t-test and an unpaired t-test, with a P-value of ≤0.05 being significant. Results Incorporation of nano-ZrO2 into the repair resin significantly increased flexural strength (P<0.05). The highest value was found in the bevel group reinforced with 7.5% nano-ZrO2, whereas the lowest value was found in the butt group reinforced with 2.5% nano-ZrO2. The impact strength values of all repaired groups were significantly lower than those of the control group (P<0.05). Among repaired groups, the higher impact strength value was seen in the butt group reinforced with 2.5% nano-ZrO2. The bevel joint demonstrated mainly cohesive failure, whereas the butt joint demonstrated mainly adhesive failure. Conclusion Incorporation of nano-ZrO2 into the repair resin improved the flexural strength of repaired denture bases, whereas it decreased impact strength, especially with high nano-ZrO2 concentrations. PMID:27822041

Influence of TiN Inclusions on the Cleavage Fracture Behavior of Low-Carbon Microalloyed Steels

NASA Astrophysics Data System (ADS)

Yan, W.; Shan, Y. Y.; Yang, K.

2007-06-01

Toughness is a major concern for low-carbon microalloyed steels. In this work, the impact fracture behavior of two low-carbon Ti-V microalloyed steels was investigated in order to better understand the role of TiN inclusions in the toughness of the steels. The steels had similar chemical compositions and were manufactured by the same rolling process. However, there was an obvious difference in the ductile brittle transition temperature (DBTT) in the Charpy V-notch (CVN) impact tests of the two steels; one (steel 1) possessing a DBTT below -20 °C, while the DBTT of the other (steel 2) was above 15 °C. Scanning electron microscopy (SEM) fractography revealed that there were TiN inclusions at the cleavage fracture initiation sites on the fracture surfaces of steel 2 at both low and room temperatures. It is shown that the TiN inclusions had nucleated on Al2O3 particles and that they had pre-existing interior flaws. A high density of TiN inclusions was found in steel 2, but there was a much lower density in steel 1. Analysis indicates that these inclusions were responsible for the shift of DBTT to a higher temperature in steel 2. A mechanism is proposed for understanding the effect of the size and density of TiN inclusions on the fracture behavior, and the cleavage fracture initiation process is analyzed in terms of the distribution and development of stresses ahead of the notch tip during fracture at both low and room temperatures.

Effect of prior-austenite grain refinement on microstructure, mechanical properties and thermal embrittlement of 9Cr-1Mo-0.1C steel

NASA Astrophysics Data System (ADS)

Karthikeyan, T.; Dash, Manmath Kumar; Ravikirana; Mythili, R.; Panneer Selvi, S.; Moitra, A.; Saroja, S.

2017-10-01

The effect of 'conventional normalizing and tempering' (CNT) and 'double austenitization based normalizing and tempering' (DNT) heat treatments on the microstructure, tensile, creep and impact toughness properties of 9Cr-1Mo steel has been studied. The tempered martensite microstructure obtained through DNT treatment exhibited smaller sizes of prior-austenite grains/martensite packets (28 μm/11 μm) compared to the CNT treatment (44 μm/14 μm). The tempered martensite morphology was largely retained after long-term thermal aging at 550 °C/5000 h, while the M23C6 and M2(C,N) type of precipitates were found to act as nucleation sites for precipitation of brittle Fe2Mo Laves phase. The grain refinement by DNT was found to be beneficial for minimizing the ductile-to-brittle transition characteristics (25 °C lower ductile-to-brittle transition temperature and 70 J higher upper shelf energy) over the CNT. Thermal embrittlement occurred in both heated treated steels, but the transition temperature of aged DNT steel remained below room temperature. Fractured Charpy specimens revealed ductile failure by void coalescence for high temperature tests, and a quasi-cleavage fracture at low temperatures with few isolated occurrence of intergranular crack in thermal embrittled steel. The DNT treated steel resulted in similar or better tensile and creep properties, when compared to the CNT treatment. The homogeneous fine grained tempered martensite microstructure obtained by DNT treatment resulted in improved embrittlement resistance and mechanical properties over the conventional treatment.

The effect of alloying elements and microstructure on the strength and fracture resistance of pearlitic steel

NASA Astrophysics Data System (ADS)

Nakase, K.; Bernstein, I. M.

1988-11-01

The processes of ductile and brittle fracture in fully pearlitic steel and their relation to both the scale of the microstructure and the presence of substitutional alloy elements have been investigated at room temperature using smooth tensile and over a range of temperatures using V-notched Charpy impact specimens. The results show that the early stages of cracking, revealed in both types of specimen, are largely the result of shear cracking of the pearlite lamellae. These cracks grow and can reach a size when they impinge upon the prior austenite boundary; afterward the character of fracture can be either microvoid coalescence or cleavage, depending on test conditions and metallurgical variables. Further, the carbide plates of the pearlite lamellae can act as barriers to the movement of dislocations as is the case normally with grain boundaries. For pearlite an optimum spacing of approximately 0.2 μm resulting from a balance between carbide plate thickness and interlamellar spacing was found to enhance toughness, although such changes are much smaller than corresponding changes due to varying alloy elements. Specific alloy elements used herein strengthened the lamellar ferrite in pearlite, inhibiting the movement of dislocations while also usually decreasing the lamellar cementite plate thickness for the same spacing. This dual behavior results in enhanced resistance to the initiation and propagation of microcracks leading to an improvement in strength, ductility, and toughness. The most effective alloy elements for the composition ranges studied in fully pearlitic steels are Si and Ni for strength improvement, and Ni and Mn for toughness.

Nanocrystalline-grained tungsten prepared by surface mechanical attrition treatment: Microstructure and mechanical properties

NASA Astrophysics Data System (ADS)

Guo, Hong-Yan; Xia, Min; Wu, Zheng-Tao; Chan, Lap-Chung; Dai, Yong; Wang, Kun; Yan, Qing-Zhi; He, Man-Chao; Ge, Chang-Chun; Lu, Jian

2016-11-01

A nanostructured surface layer was fabricated on commercial pure tungsten using the method of surface mechanical attrition treatment (SMAT). The microstructure evolution of the surface layer was characterized by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and its formation mechanism was discussed as well. Both refinement and elongation of the brittle W grains were confirmed. The elongated SMATed W was heavily strained, the maximum value of the strain at the grain boundaries reaches as high as 3-5%. Dislocation density in the SMATed W nanograins was found to be 5 × 1012 cm-2. The formation of the nanograins in the top surface layer of the W was ascribed to the extremely high strain and strain rate, as well as the multidirectional repetitive loading. Bending strength of commercial W could be improved from 825 MPa to 1850 MPa by SMAT process. Microhardness results indicated the strain range in SMATed W can reach up to 220 μm beneath the top surface. The notched Charpy testing results demonstrated that SMATed W possess higher ductility than that of commercial W. The top surface of the W plates with and without SMATe processing possesses residual compressive stress of about -881 MPa and -234 MPa in y direction, and -872 MPa and -879 MPa in x direction respectively. The improvement of toughness (DBTT shift) of SMATed W may be the synergistic effect of residual compressive stress, dislocation density improvement and microstructure refinement induced by SMAT processing. SMAT processing could be a complementary method to further decrease the DBTT value of tungsten based materials.

Effects of Thermal Aging on Material Properties, Stress Corrosion Cracking, and Fracture Toughness of AISI 316L Weld Metal

NASA Astrophysics Data System (ADS)

Lucas, Timothy; Forsström, Antti; Saukkonen, Tapio; Ballinger, Ronald; Hänninen, Hannu

2016-08-01

Thermal aging and consequent embrittlement of materials are ongoing issues in cast stainless steels, as well as duplex, and high-Cr ferritic stainless steels. Spinodal decomposition is largely responsible for the well-known "748 K (475 °C) embrittlement" that results in drastic reductions in ductility and toughness in these materials. This process is also operative in welds of either cast or wrought stainless steels where δ-ferrite is present. While the embrittlement can occur after several hundred hours of aging at 748 K (475 °C), the process is also operative at lower temperatures, at the 561 K (288 °C) operating temperature of a boiling water reactor (BWR), for example, where ductility reductions have been observed after several tens of thousands of hours of exposure. An experimental program was carried out in order to understand how spinodal decomposition may affect changes in material properties in Type 316L BWR piping weld metals. The study included material characterization, nanoindentation hardness, double-loop electrochemical potentiokinetic reactivation (DL-EPR), Charpy-V, tensile, SCC crack growth, and in situ fracture toughness testing as a function of δ-ferrite content, aging time, and temperature. SCC crack growth rates of Type 316L stainless steel weld metal under simulated BWR conditions showed an approximate 2 times increase in crack growth rate over that of the unaged as-welded material. In situ fracture toughness measurements indicate that environmental exposure can result in a reduction of toughness by up to 40 pct over the corresponding at-temperature air-tested values. Material characterization results suggest that spinodal decomposition is responsible for the degradation of material properties measured in air, and that degradation of the in situ properties may be a result of hydrogen absorbed during exposure to the high-temperature water environment.

Mechanical properties of PP/PA blends in addition with PP-g-MAH with different PP molecular weight and MAH content

NASA Astrophysics Data System (ADS)

Tokumitsu, Katuhisa; Nakajima, Yuki; Aoki, Kenji

2016-03-01

The mechanical properties and morphological changes of PP/PA6/PP-g-MAH blends were investigated. In particular, various kinds of PP-g-MAH, which have a series of different Mw of PP and MAH content, were investigated. From the tensile test results of PP/PA6 blends, although the elongation at break and yield stress can be improved by adding PP-g-MAH, modulus slightly decreased. In particular, elongation at break of PP/PA in addition with PP-g-MAH increased twentyfold from 27.0% (without PP-g-MAH) to 570%. On the basis of Charpy impact test results, the impact strength can also be improved by adding PP-g-MAH. From SEM observation, it was found that the diameter of the dispersed PA6 phase in PP matrix was getting much smaller with PP-g-MAH content. From the TEM observation, the boundary of the PA phase in PP/PA blends without PP-g-MAH compatibilizer can be observed clearly, but it becomes hard to see the boundary part of the PA phase in PP/PA blend with compatibilizer. Furthermore, when comparing the inside of the PA phase, small amount of PP phase can be observed in the PA phase of PP/PA blend with compatibilizer. Here, we defined a parameter, Comprehensive Mechanical Property Factor (CMPF), which can be calculated by multiple each mechanical property (elongation at break, yield stress, modulus and impact strength) against each maximum value, and it was found that CMPF has a good correlation with the diameter of PA6 phase. In conclusion, an optimum mechanical property of PP/PA6 can be obtained by using PP-g-MAH with Mw around 35,000 ˜ 50,000 g mol-1 and MAH content around 2.0 ˜ 3.5 %.

Effect of irradiation-induced plastic flow localization on ductile crack resistance behavior of a 9%Cr tempered martensitic steel

NASA Astrophysics Data System (ADS)

Chaouadi, R.

2008-01-01

This paper examines the effect of irradiation-induced plastic flow localization on the crack resistance behavior. Tensile and crack resistance measurements were performed on Eurofer-97 that was irradiated at 300 °C to neutron doses ranging between 0.3 and 2.1 dpa. A severe degradation of crack resistance behavior is experimentally established at quasi-static loading, in contradiction with the Charpy impact data and the dynamic crack resistance measurements. This degradation is attributed to the dislocation channel deformation phenomenon. At quasi-static loading rate, scanning electron microscopy observations of the fracture surfaces revealed a significant change of fracture topography, mainly from equiaxed dimples (mode I) to shear dimples (mode I + II). With increasing loading rate, the high peak stresses that develop inside the process zone activate much more dislocation sources resulting in a higher density of cross cutting dislocation channels and therefore an almost unaffected crack resistance. These explanations provide a rational to all experimental observations.

Effects of post-weld heat treatment on microstructure and mechanical properties of laser welds in GH3535 superalloy

NASA Astrophysics Data System (ADS)

Yu, Kun; Jiang, Zhenguo; Leng, Bin; Li, Chaowen; Chen, Shuangjian; Tao, Wang; Zhou, Xingtai; Li, Zhijun

2016-07-01

In this study, the microstructure and mechanical properties of laser welds before and after post-weld heat treatment processes were studied. The results show that the tensile strength of the joints can be increased by 90 MPa by a post-weld heat treatment process at 871 °C for 6 h, exceeding the strength of the original state of the base metal. Besides, elongation of the joints are also increased to 43% by the process, whereas the elongation of as-welded joints are only 22%. In addition, the Charpy impact properties of laser welds almost do not change. Second phase precipitates, which were identified as Mo-Si rich M6C-type carbides by transmission electron diffraction and scanning electron microscope, were observed at solidification grain boundaries and solidification subgrain boundaries. These carbides can pin dislocations during the following tensile deformation, hence are responsible for the strengthening of tensile properties of the joints.

Grain-refining heat treatments to improve cryogenic toughness of high-strength steels

NASA Technical Reports Server (NTRS)

Rush, H. F.

1984-01-01

The development of two high Reynolds number wind tunnels at NASA Langley Research Center which operate at cryogenic temperatures with high dynamic pressures has imposed severe requirements on materials for model construction. Existing commercial high strength steels lack sufficient toughness to permit their safe use at temperatures approaching that of liquid nitrogen (-320 F). Therefore, a program to improve the cryogenic toughness of commercial high strength steels was conducted. Significant improvement in the cryogenic toughness of commercial high strength martensitic and maraging steels was demonstrated through the use of grain refining heat treatments. Charpy impact strength at -320 F was increased by 50 to 180 percent for the various alloys without significant loss in tensile strength. The grain sizes of the 9 percent Ni-Co alloys and 200 grade maraging steels were reduced to 1/10 of the original size or smaller, with the added benefit of improved machinability. This grain refining technique should permit these alloys with ultimate strengths of 220 to 270 ksi to receive consideration for cryogenic service.

Effects of thermal annealing and reirradiation on toughness of reactor pressure vessel steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nanstad, R.K.; Iskander, S.K.; Sokolov, M.A.

1997-02-01

One of the options to mitigate the effects of irradiation on reactor pressure vessels (RPV) is to thermally anneal them to restore the toughness properties that have been degraded by neutron irradiation. This paper summarizes recent experimental results from work performed at the Oak Ridge National Laboratory (ORNL) to study the annealing response, or {open_quotes}recovery,{close_quotes} of several irradiated RPV steels; it also includes recent results from both ORNL and the Russian Research Center-Kurchatov Institute (RRC-KI) on a cooperative program of irradiation, annealing and reirradiation of both U.S. and Russian RPV steels. The cooperative program was conducted under the auspices ofmore » Working Group 3, U.S./Russia Joint Coordinating Committee for Civilian Nuclear Reactor Safety (JCCCNRS). The materials investigated are an RPV plate and various submerged-arc welds, with tensile, Charpy impact toughness, and fracture toughness results variously determined. Experimental results are compared with applicable prediction guidelines, while observed differences in annealing responses and reirradiation rates are discussed.« less

Investigation of Microstructural Features Determining the Toughness of 980 MPa Bainitic Weld Metal

NASA Astrophysics Data System (ADS)

Cao, R.; Zhang, X. B.; Wang, Z.; Peng, Y.; Du, W. S.; Tian, Z. L.; Chen, J. H.

2014-02-01

The microstructural features that control the impact toughness of weld metals of a 980 MPa 8 pct Ni high-strength steel are investigated using instrumented Charpy V tester, optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), electron back-scattered diffraction (EBSD), and finite-element method (FEM) calculation. The results show that the critical event for cleavage fracture in this high-strength steel and weld metals is the propagation of a bainite packet-sized crack across the packet boundary into contiguous packets, and the bainitic packet sizes control the impact toughness. The high-angle misorientation boundaries detected in a bainite packet by EBSD form fine tear ridges on fracture surfaces. However, they are not the decisive factors controlling the cleavage fracture. The effects of Ni content are essential factors for improving the toughness. The extra large cleavage facets seriously deteriorate the toughness, which are formed on the interfaces of large columnar crystals growing in welding pools with high heat input.

Fracture Behavior of Zr-BASED Bulk Metallic Glass Under Impact Loading

NASA Astrophysics Data System (ADS)

Shin, Hyung-Seop; Kim, Ki-Hyun; Oh, Sang-Yeob

The fracture behavior of a Zr-based bulk amorphous metal under impact loading using subsize V-shaped Charpy specimens was investigated. Influences of loading rate on the fracture behavior of amorphous Zr-Al-Ni-Cu alloy were examined. As a result, the maximum load and absorbed fracture energy under impact loading were lower than those under quasi-static loading. A large part of the absorbed fracture energy in the Zr-based BMG was consumed in the process for crack initiation and not for crack propagation. In addition, fractographic characteristics of BMGs, especially the initiation and development of shear bands at the notch tip were investigated. Fractured surfaces under impact loading are smoother than those under quasi-static loading. The absorbed fracture energy appeared differently depending on the appearance of the shear bands developed. It can be found that the fracture energy and fracture toughness of Zr-based BMG are closely related with the extent of shear bands developed during fracture.

Influence of long-term thermal aging on the microstructural evolution of nuclear reactor pressure vessel materials: An atom probe study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pareige, P.; Russell, K.F.; Stoller, R.E.

1998-03-01

Atom probe field ion microscopy (APFIM) investigations of the microstructure of unaged (as-fabricated) and long-term thermally aged ({approximately} 100,000 h at 280 C) surveillance materials from commercial reactor pressure vessel steels were performed. This combination of materials and conditions permitted the investigation of potential thermal-aging effects. This microstructural study focused on the quantification of the compositions of the matrix and carbides. The APFIM results indicate that there was no significant microstructural evolution after a long-term thermal exposure in weld, plate, or forging materials. The matrix depletion of copper that was observed in weld materials was consistent with the copper concentrationmore » in the matrix after the stress-relief heat treatment. The compositions of cementite carbides aged for 100,000 h were compared with the Thermocalc{trademark} prediction. The APFIM comparisons of materials under these conditions are consistent with the measured change in mechanical properties such as the Charpy transition temperature.« less

Development of new generation reduced activation ferritic-martenstic steels for advanced fusion reactors

DOE PAGES

Tan, Lizhen; Snead, Lance Lewis; Katoh, Yutai

2016-05-26

International development of reduced activation ferritic-martensitic (RAFM) steels has focused on 9 wt percentage Cr, which primarily contain M 23C 6 (M = Cr-rich) and small amounts of MX (M = Ta/V, X = C/N) precipitates, not adequate to maintain strength and creep resistance above ~500 °C. To enable applications at higher temperatures for better thermal efficiency of fusion reactors, computational alloy thermodynamics coupled with strength modeling have been employed to explore a new generation RAFM steels. The new alloys are designed to significantly increase the amount of MX nanoprecipitates, which are manufacturable through standard and scalable industrial steelmaking methods.more » Preliminary experimental results of the developed new alloys demonstrated noticeably increased amount of MX, favoring significantly improved strength, creep resistance, and Charpy impact toughness as compared to current RAFM steels. Furthermore, the strength and creep resistance were comparable or approaching to the lower bound of, but impact toughness was noticeably superior to 9–20Cr oxide dispersion-strengthened ferritic alloys.« less

Microstructural Evolution of Inconel 625 and Inconel 686CPT Weld Metal for Clad Carbon Steel Linepipe Joints: A Comparator Study

NASA Astrophysics Data System (ADS)

Maltin, Charles A.; Galloway, Alexander M.; Mweemba, Martin

2014-07-01

Microstructural evolution of Inconel 625 and Inconel 686CPT filler metals, used for the fusion welding of clad carbon steel linepipe, has been investigated and compared. The effects of iron dilution from the linepipe parent material on the elemental segregation potential of the filler metal chemistry have been considered. The results obtained provide significant evidence to support the view that, in Inconel 686CPT weld metal, the segregation of tungsten is a function of the level of iron dilution from the parent material. The data presented indicate that the incoherent phase precipitated in the Inconel 686CPT weld metal has a morphology that is dependent on tungsten enrichment and, therefore, iron dilution. Furthermore, in the same weld metal, a continuous network of finer precipitates was observed. The Charpy impact toughness of each filler metal was evaluated, and the results highlighted the superior impact toughness of the Inconel 625 weld metal over that of Inconel 686CPT.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, L.; Katoh, Y.; Tavassoli, A. -A. F.

Reduced-activation ferritic-martensitic (RAFM) steels, candidate structural materials for fusion reactors, have achieved technological maturity after about three decades of research and development. The recent status of a few developmental aspects of current RAFM steels, such as aging resistance, plate thickness effects, fracture toughness, and fatigue, is updated in this paper, together with ongoing efforts to develop next-generation RAFM steels for superior high-temperature performance. Additionally, to thermomechanical treatments, including nonstandard heat treatment, alloy chemistry refinements and modifications have demonstrated some improvements in high-temperature performance. Castable nanostructured alloys (CNAs) were developed by significantly increasing the amount of nanoscale MX (M = V/Ta/Ti,more » X = C/N) precipitates and reducing coarse M 23C 6 (M = Cr). Preliminary results showed promising improvement in creep resistance and Charpy impact toughness. We present and compare limited low-dose neutron irradiation results for one of the CNAs and China low activation martensitic with data for F82H and Eurofer97 irradiated up to ~70 displacements per atom at ~300–325 °C.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Lizhen; Snead, Lance Lewis; Katoh, Yutai

International development of reduced activation ferritic-martensitic (RAFM) steels has focused on 9 wt percentage Cr, which primarily contain M 23C 6 (M = Cr-rich) and small amounts of MX (M = Ta/V, X = C/N) precipitates, not adequate to maintain strength and creep resistance above ~500 °C. To enable applications at higher temperatures for better thermal efficiency of fusion reactors, computational alloy thermodynamics coupled with strength modeling have been employed to explore a new generation RAFM steels. The new alloys are designed to significantly increase the amount of MX nanoprecipitates, which are manufacturable through standard and scalable industrial steelmaking methods.more » Preliminary experimental results of the developed new alloys demonstrated noticeably increased amount of MX, favoring significantly improved strength, creep resistance, and Charpy impact toughness as compared to current RAFM steels. Furthermore, the strength and creep resistance were comparable or approaching to the lower bound of, but impact toughness was noticeably superior to 9–20Cr oxide dispersion-strengthened ferritic alloys.« less

Effect of iron-intermetallics and porosity on tensile and impact properties of aluminum-silicon-copper and aluminum-silicon-magnesium cast alloys

NASA Astrophysics Data System (ADS)

Ma, Zheyuan

Aluminum-silicon (Al-Si) alloys are an important class of materials that constitute the majority of aluminum cast parts produced, due to their superior properties and excellent casting characteristics. Within this family of alloys, Al-Si-Cu and Al-Si-Mg cast alloys are frequently employed in automotive applications. The commercially popular 319 and 356 alloys, representing these two alloy systems, were selected for study in the present work, with the aim of investigating the effect of iron intermetallics and porosity on the alloy performance. This was carried out through a study of the tensile and impact properties, these being two of the important mechanical properties used in design calculations. Iron, through the precipitation of second phase intermetallic constituents, in particular the platelike beta-Al5FeSi phase, is harmful to the alloy properties. Likewise, gas- or shrinkage porosity in castings is also detrimental to the mechanical properties. By determining the optimum alloying, melt processing and solidification parameters (viz., Fe content, Sr modification and cooling rate) required to minimize the harmful effects of porosity and iron intermetallics, and studying their role on the fracture behavior, the fracture mechanism in the alloys could be determined. Castings were prepared from both industrial and experimental 319.2, B319.2 and A356.2 alloy melts, containing Fe levels of 0.2--1.0 wt%. Sr-modified (˜200 ppm) melts were also prepared for each alloy Fe level. The end-chilled refractory mold used provided directional solidification and a range of cooling rates (or dendrite arm spacings, DAS) within the same casting. Tensile and impact test samples machined from specimen blanks sectioned from the castings at various heights above the chill end provided DASs of 23--85mum. All samples were T6-heat-treated before testing. Tests were carried out employing Instron Universal and Instrumented Charpy testing machines. Optical microscopy, image analysis, SEM and EPMA techniques were used for microstructural and fracture analysis. The results show that the highest cooling rate (23 mum DAS) is the most significant parameter controlling the size and distribution of the beta-Al 5FeSi phase and porosity in the unmodified 319.2 and A356.2 alloys. (Abstract shortened by UMI.)

Evaluation of weldments in type 21-6-9 stainless steel for compact ignition tokamak structural applications, phase 1

NASA Astrophysics Data System (ADS)

Alexander, D. J.; Goodwin, G. M.; Bloom, E. E.

1991-06-01

Primary design considerations for the Compact Ignition Tokamak toroidal field-coil cases are yield strength and toughness in the temperature range from 77 to 300 K. Type 21-6-9 stainless steel, also still known by its original Armco Steel Company trade name Nitronic 40, is the proposed alloy for this application. It has high yield strength and usually adequate base metal toughness, but weldments in thick sections have not been adequately characterized in terms of mechanical properties or hot-cracking propensity. In this study, weldability of the alloy in heavy sections and the mechanical properties of the resultant welds were investigated including tensile yield strength and Charpy V-notch toughness at 77 K and room temperature. Weldments were made in four different base metals using seven different filler metals. None of the weldments showed any indication of hot-cracking problems. All base metals, including weldment heat-affected zones, were found to have adequate strength and impact toughness at both test temperatures. Weld metals, on the other hand, except ERNiCr-3 and ENiCrFe-3, had impact toughnesses of less than 67 J at 77 K. Inconel 82 had an average weld metal impact toughness of over 135 J at 77 K, and although its strength at 77 K is less than that of type 21-6-9 base metal, at this point it is considered to be the first-choice filler metal. Phase 2 of this program will concentrate on composition refinement and process/procedure optimization for the generic ERNiCr-3 composition and will generate a design data base for base and weld metal, including tensile, fracture toughness, and crack growth rate data.

Effect of thermal exposure on mechanical properties hypo eutectic aerospace grade aluminium-silicon alloy

NASA Astrophysics Data System (ADS)

Nagesh Kumar, R.; Ram Prabhu, T.; Siddaraju, C.

2016-09-01

The effect of thermal exposure on the mechanical properties of a C355.0 aerospace grade aluminum-silicon alloy (5% Si - 1.2% Cu - 0.5% Mg) was investigated in the present study. The alloy specimens were subjected to T6 (solution treatment and artificial ageing treatment) temper treatment to enhance the strength properties through precipitation hardening. The T6 temper treatment involved solution heat treatment at 520oC for 6h, followed by water quenching and ageing at 150oC. After the heat treatment, the specimens were exposed to various temperatures (50oC, 100oC, 150oC, 200oC and 250oC) for 5 and 10 h to study the structural applications of this alloy to the various Mach number military aircrafts. After the thermal exposure, specimens were tested for tensile, hardness and impact properties (Charpy). The microstructure of the thermal exposed specimens was examined in the optical microscopes and correlated with the mechanical properties results. In summary, an increase of exposure time has a different effect on the tensile and hardness properties of the alloy. For the exposure time 5h, the tensile and hardness properties increase upto 100oC and later decrease with an increase of temperature. In contrast, the tensile and hardness properties linearly decrease with an increase of temperature. Several factors such as matrix grain growth, diffusion rate, Si particles size and distribution, precipitate stability play a key role on deciding the tensile properties of the alloy. Comparing the relative effects of temperature and time, the temperature effects dominate more in deteriorating tensile properties of the alloy. There are no effects of exposure temperature and/or time on the impact properties of the alloy.

Novel water-air circulation quenching process for AISI 4140 steel

NASA Astrophysics Data System (ADS)

Zheng, Liyun; Zheng, Dawei; Zhao, Lixin; Wang, Lihui; Zhang, Kai

2013-11-01

AISI 4140 steel is usually used after quenching and tempering. During the heat treatment process in industry production, there are some problems, such as quenching cracks, related to water-cooling and low hardness due to oil quenching. A water-air circulation quenching process can solve the problems of quenching cracks with water and the high cost quenching with oil, which is flammable, unsafe and not enough to obtain the required hardness. The control of the water-cooling and air-cooling time is a key factor in the process. This paper focuses on the quenching temperature, water-air cycle time and cycle index to prevent cracking for AISI 4140 steel. The optimum heat treatment parameters to achieve a good match of the strength and toughness of AISI 4140 steel were obtained by repeated adjustment of the water-air circulation quenching process parameters. The tensile strength, Charpy impact energy at -10 °C and hardness of the heat treated AISI 4140 steel after quenching and tempering were approximately 1098 MPa, 67.5 J and 316 HB, respectively.

The analysis of composite properties reinforced with particles from palm oil industry waste produced by casting methods

NASA Astrophysics Data System (ADS)

Tugiman; Ariani, F.; Taher, F.; Hasibuan, M. S.; Suprianto

2017-12-01

Palm oil processing industries are very attractive because they offer plenty products with high economic value. The CPO factory processes not only produces crude palm oil but also generates fly ash (FA) particles waste in its final process. The purpose of this investigation to analyze and increase the benefits of particles as reinforcement materials for fabricating aluminum matrix composites (AMC’s) by different casting route. Stirring, centrifugal and squeeze casting method was conducted in this study. Further, the chemical composition of FA particles, densities and mechanical properties have been analyzed. The characteristics of composite material were investigated using an Optical microscope, scanning electron microscope (SEM), hardness (Brinell), impact strength (Charpy). The pin on disc method was used to measure the wear rate. The results show that SiO2, Fe2O3, and Al2O3 are the main compounds of fly ash particles. These particles enhanced the hardness and reduce wear resistance of aluminum matrix composites. The squeeze method gives better results than stir and centrifugal casting.

The effect of fibre content, fibre size and alkali treatment to Charpy impact resistance of Oil Palm fibre reinforced composite material

NASA Astrophysics Data System (ADS)

Fitri, Muhamad; Mahzan, Shahruddin

2016-11-01

In this research, the effect of fibre content, fibre size and alkali treatment to the impact resistance of the composite material have been investigated, The composite material employs oil palm fibre as the reinforcement material whereas the matrix used for the composite materials are polypropylene. The Oil Palm fibres are prepared for two conditions: alkali treated fibres and untreated fibres. The fibre sizes are varied in three sizes: 5mm, 7mm and 10mm. During the composite material preparation, the fibre contents also have been varied into 3 different percentages: 5%, 7% and 10%. The statistical approach is used to optimise the variation of specimen determined by using Taguchi method. The results were analyzed also by the Taguchi method and shows that the Oil Palm fibre content is significantly affect the impact resistance of the polymer matrix composite. However, the fibre size is moderately affecting the impact resistance, whereas the fibre treatment is insignificant to the impact resistance of the oil palm fibre reinforced polymer matrix composite.

Effects of Ultra-Fast Cooling After Hot Rolling and Intercritical Treatment on Microstructure and Cryogenic Toughness of 3.5%Ni Steel

NASA Astrophysics Data System (ADS)

Wang, Meng; Liu, Zhenyu

2017-07-01

A novel process comprised of ultra-fast cooling after control rolling, intercritical quenching and tempering (UFC-LT) was applied to 3.5%Ni steel. In addition, quenching and tempering (QT) treatment was conducted in comparison. The present study focuses on the relationship between the microstructure and cryogenic toughness of 3.5%Ni steel. Results show that the microstructure of steel treated by UFC-LT consisted of tempered martensite, intercritical ferrite and two types of reversed austenite (RA) (needle shape and blocky). Compared to the QT sample, the UFC-LT sample's ultimate tensile strength decreased slightly, while its elongation increased from 32.3 to 35.7%, and its Charpy absorption energy at -135 °C increased from 112 to 237 J. The ductile-brittle transition temperature of UFC-LT sample was lower than that of the QT sample by 18 °C. The superior cryogenic toughness after UFC-LT compared to QT treatment can be attributed to the dissolution of cementite, approximately 3.0% increase in RA and the decrease in effective grain size.

Recent status and improvement of reduced-activation ferritic-martensitic steels for high-temperature service

DOE PAGES

Tan, L.; Katoh, Y.; Tavassoli, A. -A. F.; ...

2016-07-26

Reduced-activation ferritic-martensitic (RAFM) steels, candidate structural materials for fusion reactors, have achieved technological maturity after about three decades of research and development. The recent status of a few developmental aspects of current RAFM steels, such as aging resistance, plate thickness effects, fracture toughness, and fatigue, is updated in this paper, together with ongoing efforts to develop next-generation RAFM steels for superior high-temperature performance. Additionally, to thermomechanical treatments, including nonstandard heat treatment, alloy chemistry refinements and modifications have demonstrated some improvements in high-temperature performance. Castable nanostructured alloys (CNAs) were developed by significantly increasing the amount of nanoscale MX (M = V/Ta/Ti,more » X = C/N) precipitates and reducing coarse M 23C 6 (M = Cr). Preliminary results showed promising improvement in creep resistance and Charpy impact toughness. We present and compare limited low-dose neutron irradiation results for one of the CNAs and China low activation martensitic with data for F82H and Eurofer97 irradiated up to ~70 displacements per atom at ~300–325 °C.« less

A Comparison of the Flexural and Impact Strengths and Flexural Modulus of CAD/CAM and Conventional Heat-Cured Polymethyl Methacrylate (PMMA).

PubMed

Al-Dwairi, Ziad N; Tahboub, Kawkab Y; Baba, Nadim Z; Goodacre, Charles J

2018-06-13

The introduction of computer-aided design/computer-aided manufacturing (CAD/CAM) technology to the field of removable prosthodontics has recently made it possible to fabricate complete dentures of prepolymerized polymethyl methacrylate (PMMA) blocks, which are claimed to be of better mechanical properties; however, no published reports that have evaluated mechanical properties of CAD/CAM PMMA. The purpose of this study was to compare flexural strength, impact strength, and flexural modulus of two brands of CAD/CAM PMMA and a conventional heat-cured PMMA. 45 rectangular specimens (65 mm × 10 mm × 3 mm) were fabricated (15 CAD/CAM AvaDent PMMA specimens from AvaDent, 15 CAD/CAM Tizian PMMA specimens from Shütz Dental, 15 conventional Meliodent PMMA specimens from Heraeus Kulzer) and stored in distilled water at (37  ± 1°C) for 7 days. Specimens (N = 15) in each group were subjected to the three-point bending test and impact strength test, employing the Charpy configuration on unnotched specimens. The morphology of the fractured specimens was studied under a scanning electron microscope (SEM). Statistical analysis was performed using one-way ANOVA and Tukey pairwise multiple comparisons with 95% confidence interval. The Schütz Dental specimens showed the highest mean flexural strength (130.67 MPa) and impact strength (29.56 kg/m 2 ). The highest mean flexural modulus was recorded in the AvaDent group (2519.6 MPa). The conventional heat-cured group showed the lowest mean flexural strength (93.33 MPa), impact strength (14.756 kg/m 2 ), and flexural modulus (2117.2 MPa). Differences in means of flexural properties between AvaDent and Schütz Dental specimens were not statistically significant (p > 0.05). As CAD/CAM PMMA specimens exhibited improved flexural strength, flexural modulus, and impact strength in comparison to the conventional heat-cured groups, CAD/CAM dentures are expected to be more durable. Different brands of CAD/CAM PMMA may have inherent variations in mechanical properties. © 2018 by the American College of Prosthodontists.

The Role of Retained Austenite on the Mechanical Properties of a Low Carbon 3Mn-1.5Ni Steel

NASA Astrophysics Data System (ADS)

Chen, Jun; Zhang, Wei-na; Liu, Zhen-yu; Wang, Guo-dong

2017-12-01

The present studies focus on the correlation between retained austenite characteristics and the cryogenic temperature Charpy impact toughness, strength, and plasticity. The steels with different volume fractions and stabilities of retained austenite were prepared by quenching followed by intercritical heat treatment, and the microstructure was characterized using scanning electron microscope, electron back-scattered diffraction, and X-ray diffraction. The grain size, dislocation density, crack initiation energy, and crack propagation energy were quantified. It has been demonstrated that the volume fraction of retained austenite plays a significant role in the reduction of the measured yield strength and the effect of tempered martensite/ferrite matrix on cryogenic temperature impact toughness can be assumed to be similar due to the similar grain size, dislocation density and element content in solution for different heat treatments. It was found that the stability of retained austenite plays a determining role in the increase of cryogenic temperature impact toughness. Furthermore, the dependence of the crack propagation energy on retained austenite is much greater than that of the crack initiation energy. Generally, an excellent UTS × TEL does not produce good cryogenic temperature impact toughness.

Effect of 0.1 wt.% Co on the Hot Deformation and Toughness of Fine-Grained Low-Carbon Steel at Sub-zero Temperatures

NASA Astrophysics Data System (ADS)

Liu, Xiqin; Zhou, Shuangshuang; Liu, Zili; Hou, Zhiguo; Tian, Qingchao

2017-12-01

The effect of 0.1 wt.% Co on the hot deformation behavior of fine-grained low-carbon microalloyed steel was investigated at temperatures of 850-1200 °C and a strain rate of 5 s-1. Furthermore, the toughness of the steel with and without Co at sub-zero temperatures was evaluated. The results suggest that the addition of 0.1 wt.% Co increases the flow stress and delays the occurrence of dynamic recrystallization (DRX) at the same deformation temperature and strain. The DRX fraction of steel specimens without and with 0.1 wt.% Co was about 67.4 and 43.9% at 850 °C, respectively. Then, it increased to 100% at 1100 °C. Compared with steel without Co, cementite particles in the tempered sorbite of steel with 0.1 wt.% Co decreased in size but increased in quantity, yield strength increased from 756 to 787 MPa, and Charpy V-notch energy at - 20 and - 50 °C improved from 69 and 41 to 102 and 65 J, respectively. The fracture morphology and crack propagation characteristics were consistent with the variation in impact energy.

Effect of 0.1 wt.% Co on the Hot Deformation and Toughness of Fine-Grained Low-Carbon Steel at Sub-zero Temperatures

NASA Astrophysics Data System (ADS)

Liu, Xiqin; Zhou, Shuangshuang; Liu, Zili; Hou, Zhiguo; Tian, Qingchao

2018-01-01

The effect of 0.1 wt.% Co on the hot deformation behavior of fine-grained low-carbon microalloyed steel was investigated at temperatures of 850-1200 °C and a strain rate of 5 s-1. Furthermore, the toughness of the steel with and without Co at sub-zero temperatures was evaluated. The results suggest that the addition of 0.1 wt.% Co increases the flow stress and delays the occurrence of dynamic recrystallization (DRX) at the same deformation temperature and strain. The DRX fraction of steel specimens without and with 0.1 wt.% Co was about 67.4 and 43.9% at 850 °C, respectively. Then, it increased to 100% at 1100 °C. Compared with steel without Co, cementite particles in the tempered sorbite of steel with 0.1 wt.% Co decreased in size but increased in quantity, yield strength increased from 756 to 787 MPa, and Charpy V-notch energy at - 20 and - 50 °C improved from 69 and 41 to 102 and 65 J, respectively. The fracture morphology and crack propagation characteristics were consistent with the variation in impact energy.

Heat treatment effects on toughness of 9Cr-1MoVNb and 12Cr-1MoVW steels irradiated at 365°C

NASA Astrophysics Data System (ADS)

Klueh, R. L.; Alexander, D. J.

1992-09-01

The 9Cr-1MoVNb and 12Cr-1MoVW steels were austenitized at 1040 and 1100°C to produce different prior austenite grain sizes, after which they were given different tempering treatments (1 h at 760°C or 2.5 h at 780°C). Subsize Charpy impact specimens from these materials were irradiated at 365°C up to 5 dpa. For 9Cr-1MoVNb steel in the unirradiated condition, the smaller the prior austenite grain size and the higher the tempering temperature, the lower the ductile-brittle transition temperature (DBTT). Regardless of the DBTT in the unirradiated condition, however, the DBTT shift for 9Cr-1MoVNb steel due to irradiation was the same for all heat treatments. This means heat treatment can be used to ensure a lower DBTT before and after irradiation. The 12Cr-1MoVW steel showed little effect of heat treatment on DBTT in the unirradiated condition, and the shift in DBTT was relatively constant. Thus, it appears that heat treatment cannot be used to reduce the effect of irradiation on DBTT for this steel.

Tensile and fracture properties of type 316 stainless steel after creep

NASA Astrophysics Data System (ADS)

Gan, D.

1982-12-01

The effects of creep on the mechanical properties of type 316 stainless steel were studied. Tensile and Charpy specimens were machined from the oversize specimens crept at 750 °C and 103 MPa. The ambient fracture energy was found to deteriorate rapidly after creep. The ambient yield stress was increased moderately, but the tensile ductility was severely reduced. The effects of intergranular carbides alone on mechanical properties were studied with specimens thermal aged without load. These carbides were shown to cause a moderate reduction in fracture energy and tensile ductility but had little effect on yield stress. Extensive grain boundary separations were observed on the fracture surfaces. SEM studies showed that these grain boundaries were covered with micro voids initiated by the dense intergranular carbides. Frequently, large dimples on grain boundary joined up and initiated shear fracture into the grain. In the crept specimens additional microstructural changes in the form of intragranular carbides and subgrain boundaries were observed. Both are responsible for the increase in yield stress and the further reduction in tensile ductility and fracture energy. The intragranular carbides also modified the size and density of the dimples on the fracture surfaces.

Influence of brazing conditions on the strength of brazed joints of alumina dispersion-strengthened copper to 316 stainless steel

NASA Astrophysics Data System (ADS)

Nishi, H.; Kikuchi, K.

1998-10-01

Brazing of alumina dispersion-strengthened copper (DS Cu) to 316 stainless steel were conducted in order to investigate the influence of filler metals and brazing conditions on the joint strength. The brazing were performed with a silver-base (BAg-8) and three kinds of gold-base (BAu-2,4,11) filler metals with varying brazing joint clearance and brazing time. The filler metal had a greater effect on the joint strength than the brazing joint clearance and brazing time. The joint with BAu-2 was superior to the joint with other filler metals. The tensile strength of the joint with BAu-2 was as large as that of DS Cu, however, the Charpy and low cycle fatigue strength were lower than those of DS Cu. The DS Cu melted near the brazed zone, consequently recrystallization and agglomeration of alumina occurred in the diffusion layer for all filler metals. The grain size after the recrystallization was small in order of BAu-2, BAu-4 and BAu-11, that was in accordance with the order of the brazing temperature. The excellent fracture strength for the joint with BAu-2 was attributed to the smallest grain size.

Development of Fine-Grained, Low-Carbon Bainitic Steels with High Strength and Toughness Produced Through the Conventional Hot-Rolling and Air-Cooling

NASA Astrophysics Data System (ADS)

Dhua, Sanjay Kumar; Sarkar, Partha Pratim; Saxena, Atul; Jha, Bimal Kumar

2016-12-01

Low-carbon bainitic steels have created enormous interest among scientists across the world in the past few decades because of their high strength, toughness, and weldability replacing the conventional quenched and tempered medium-carbon steels. Three experimental steels with varying alloy additions were made in a 100-kg laboratory induction furnace and cast into 100-mm-diameter cylindrical ingots. These ingots were hot-rolled and air-cooled to 6-mm plates in an experimental rolling mill with selected thermomechanical parameters. Steels processed through this process provided an ultrafine low-carbon bainitic microstructure with maximum yield strength (YS) and ultimate tensile strength (UTS) 575 and 705 MPa, respectively. The Charpy impact toughness of the experimental steels was excellent, and at 253 K (-20 °C), it varied from 114 to 170 Joules. Cu-B-added steel was found to give an optimum combination of strength, YS-575 MPa, and toughness, 114 J at 253 K (-20 °C). Thus, fine-grained, low-carbon bainitic steels could be developed with a proper combination of alloying elements and thermomechanical parameters even by air-cooling.

A Physically Based Correlation of Irradiation-Induced Transition Temperature Shifts for RPV Steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eason, Ernest D.; Odette, George Robert; Nanstad, Randy K

2007-11-01

The reactor pressure vessels (RPVs) of commercial nuclear power plants are subject to embrittlement due to exposure to high-energy neutrons from the core, which causes changes in material toughness properties that increase with radiation exposure and are affected by many variables. Irradiation embrittlement of RPV beltline materials is currently evaluated using Regulatory Guide 1.99 Revision 2 (RG1.99/2), which presents methods for estimating the shift in Charpy transition temperature at 30 ft-lb (TTS) and the drop in Charpy upper shelf energy (ΔUSE). The purpose of the work reported here is to improve on the TTS correlation model in RG1.99/2 using themore » broader database now available and current understanding of embrittlement mechanisms. The USE database and models have not been updated since the publication of NUREG/CR-6551 and, therefore, are not discussed in this report. The revised embrittlement shift model is calibrated and validated on a substantially larger, better-balanced database compared to prior models, including over five times the amount of data used to develop RG1.99/2. It also contains about 27% more data than the most recent update to the surveillance shift database, in 2000. The key areas expanded in the current database relative to the database available in 2000 are low-flux, low-copper, and long-time, high-fluence exposures, all areas that were previously relatively sparse. All old and new surveillance data were reviewed for completeness, duplicates, and discrepancies in cooperation with the American Society for Testing and Materials (ASTM) Subcommittee E10.02 on Radiation Effects in Structural Materials. In the present modeling effort, a 10% random sample of data was reserved from the fitting process, and most aspects of the model were validated with that sample as well as other data not used in calibration. The model is a hybrid, incorporating both physically motivated features and empirical calibration to the U.S. power reactor surveillance data. It contains two terms, corresponding to the best-understood radiation damage features, matrix damage and copper-rich precipitates, although the empirical calibration will ensure that all other damage processes that are occurring are also reflected in those terms. Effects of material chemical composition, product form, and radiation exposure are incorporated, such that all effects are supported by findings of statistical significance, physical understanding, or comparison with independent data from controlled experiments, such as the Irradiation Variable (IVAR) Program. In most variable effects, the model is supported by two or three of these different forms of evidence. The key variable trends, such as the neutron fluence dependence and copper-nickel dependence in the new TTS model, are much improved over RG1.99/2 and are well supported by independent data and the current understanding of embrittlement mechanisms. The new model includes the variables copper, nickel, and fluence that are in RG1.99/2, but also includes effects of irradiation temperature, neutron flux, phosphorus, and manganese. The calibrated model is a good fit, with no significant residual error trends in any of the variables used in the model or several additional variables and variable interactions that were investigated. The report includes a chapter summarizing the current understanding of embrittlement mechanisms and one comparing the IVAR database with the TTS model predictions. Generally good agreement is found in that quantitative comparison, providing independent confirmation of the predictive capability of the TTS model. The key new insight in the TTS modeling effort, that flux effects are evident in both low (or no) copper and higher copper materials, is supported by the IVAR data. The slightly simplified version of the TTS model presented in Section 7.3 of this report is recommended for applications.« less

Welding High Strength Modern Line Pipe Steel

NASA Astrophysics Data System (ADS)

Goodall, Graeme Robertson

The effect of modern mechanized girth welding on high strength line pipe has been investigated. The single cycle grain coarsened heat affected zone in three grade 690 line pipe steels and a grade 550 steel has been simulated using a Gleeble thermo-mechanical simulator. The continuous cooling transformation diagrams applicable to the grain coarsened heat affected zone resulting from a range of heat inputs applicable to modern mechanized welding have been established by dilatometry and metallography. The coarse grained heat affected zone was found to transform to lath martensite, bainite, and granular bainite depending on the cooling rate. The impact toughness of the steels was measured using Charpy impact toughness and compared to the toughness of the grain coarsened heat affected zone corresponding to a welding thermal cycle. The ductile to brittle transition temperature was found to be lowest for the steel with the highest hardenability. The toughness resulting from three different thermal cycles including a novel interrupted intercritically reheated grain coarsened (NTR ICR GC HAZ) that can result from dual torch welding at fast travel speed and close torch spacing have been investigated. All of the thermally HAZ regions showed reduced toughness that was attributed to bainitic microstructure and large effective grain sizes. Continuous cooling transformation diagrams for five weld metal chemistries applicable to mechanized pulsed gas metal arc welding of modern high strength pipe steel (SMYS>550 MPa) have been constructed. Welds at heat inputs of 1.5 kJmm-1 and 0.5 kJmm-1 have been created for simulation and analysis. Dilatometric analysis was performed on weld metal specimens cut from single pass 1.5 kJmm-1 as deposited beads. The resulting microstructures were found to range from martensite to polygonal ferrite. There is excellent agreement between the simulated and as deposited weld metal regions. Toughness testing indicates improved energy absorption at -20 °C with increased cooling time.

MoSi2-Base Hybrid Composite Passed Engine Test

NASA Technical Reports Server (NTRS)

Keith, Theo G., Jr.; Hebsur, Mohan

1998-01-01

The intermetallics compound molybdenum disilicide (MoSi2) is an attractive high-temperature structural material for advanced engine applications. It has excellent oxidation resistance, a high melting point, relatively low density, and high thermal conductivity, and it is easily machined. Past research'at the NASA Lewis Research Center has resulted in the development of a hybrid composite consisting of a MoSi2 matrix reinforced with silicon nitride (Si3N4) Particulate and silicon carbide (SiC) fibers. This composite has demonstrated attractive strength, toughness, thermal fatigue, and oxidation resistance, including resistance to "pest" oxidation. These properties attracted the interest of the Office of Naval Research and Pratt & Whitney, and a joint NASA/Navy/Pratt & Whitney effort was developed to continue to mature the MoSi2 Composite technology. A turbine blade outer air seal, which was part of the Integrated High Performance Turbine Engine Technology (IHPTET) program, was chosen as a first component on which to focus. The first tasks of the materials development effort were to develop improved processing methods to reduce costs and to use fine-diameter fibers that enable the manufacturing of complex shapes. Tape-casting methods were developed to fully infiltrate the fine SiC fibers with matrix powders. The resulting composites were hot pressed to 100-percent density. Composites with cross-plied fiber architectures with 30 vol. % hi-nicalon SiC fibers and 30 vol. % nitride particles are now made routinely and demonstrate a good balance of properties. The next task entailed the measurement of a wide variety of mechanical properties to confirm the suitability of this composite in engines. In particular, participants in this effort demonstrated that composites made with Hi-Nicalon fibers had strength and toughness properties equal to or better than those of the composites made with the large-diameter fibers that had been used previously. Another critically important property measured was impact resistance. Aircraft engine components require sufficient toughness to resist manufacturing defects, assembly damage, stress concentrations at notches, and foreign object damage. Engine company designers indicated that impact resistance would have to be measured before they would seriously consider these types of composites. The Charpy V-notch test was chosen to assess impact resistance, and both monolithic and composite versions Of MOSi2 were tested from -300 to 1400 C. The results (see the following graphs) show that nitride-particulate-reinforced MoSi2 exhibited impact resistance higher than that of many monolithic ceramics and intermetallics, and that the fiber-reinforced composites had even higher values, approaching that of cast superalloys.

Impact Toughness of 0.2 Pct C-1.5 Pct Si-(1.5 to 5) Pct Mn Transformation-Induced Plasticity-Aided Steels with an Annealed Martensite Matrix

NASA Astrophysics Data System (ADS)

Tanino, Hikaru; Horita, Masaomi; Sugimoto, Koh-Ichi

2016-05-01

The impact properties of 0.2 pct C-1.5 pct Si-(1.5 to 5) pct Mn transformation-induced plasticity (TRIP)-aided steels with an annealed martensite matrix which had been subjected to isothermal transformation after inter-critical annealing were investigated for potential automotive applications. The impact properties are related to the retained austenite characteristics of the steels. The products of tensile strength (TS) and Charpy impact absorbed value (CIAV) were the same for the 1.5 and 5 pct Mn steels, although the ductile-brittle transition temperature was higher for the latter. The impact properties of the 3 pct Mn steel were worse than these two steels. The high TS × CIAV value for the 5 pct Mn steel at 293 K (25 °C) was mainly caused by the TRIP effect of a larger amount of retained austenite (36 vol pct) and the hardened matrix structure; low retained austenite stability and/or a hard martensite-austenite phase reduced this value. The higher ductile-brittle transition temperature of the 5 pct Mn steel was associated with Mn segregation, a large amount of unstable retained austenite on prior austenitic grain boundaries, and decreased cleavage fracture stress owing to the high Mn content.

Effects of particle size of fiberglass-resin powder from PCBs on the properties and volatile behavior of phenolic molding compound.

PubMed

Guo, Jie; Rao, Qunli; Xu, Zhenming

2010-03-15

Fiberglass-resin powder (FR powder), a mixture of resin powder and glass fibers reclaimed from pulverized waste printed circuit boards (PCBs), is used as a partial substitute of wood flour in the production of modified phenolic molding compound (MPMC). The results show that incorporation of FR powder into MPMC as a filler enhances the thermal stability represented by heat deflection temperature (HDT). MPMC with FR powder smaller than 0.07 mm shows better properties, with a flexural strength of 73 MPa, a charpy notched impact strength of 3.0 kJ/m(2), a HDT of 167 degrees C, and a dielectric strength of 3.7 MV/m, all of which meet the standard data. Thermogravimetric analysis shows that thermal degradation of MPMC mainly includes three steps, and over 55% weight loss of MPMC occurs between temperatures of 370 degrees C and 575 degrees C. Phenol is the main volatile compound released from molding powder during the production of molding product. After molding powder cures to molding product, low level of residual phenol is detected. All the results indicate that the MPMC can be used as a new type of molding compound. (c) 2009 Elsevier B.V. All rights reserved.

Development of Si3N4 and SiC of improved toughness. [for gas turbine engines

NASA Technical Reports Server (NTRS)

Brennan, J. J.; Hulse, C. O.

1977-01-01

The application of energy absorbing surface layers to Si3N4 and SiC was investigated. Among the layers studied were microcracked materials such as iron titanate and a silica-zircon mixture and porous materials such as reaction sintered Si3N4. Energy absorption due to microcrack extension upon impact was found not to be an important mechanism. Instead, the fivefold improvement in Charpy and ballistic impact at elevated temperature (1250 C and 1370 C) found for Fe2TiO5 was due to plastic deformation while similar improvement found for silica-zircon mixtures at RT was due to crushing of the porous material. Due to thermal expansion mismatch, these two materials could not withstand thermal cycling when used as energy absorbing surface layers on Si3N4. Reaction sintered Si3N4 layers on dense Si3N4 were found to give up to a sevenfold increase in ballistic impact resistance due to crushing of the layer upon impact. High porosity (45%), large particle size R.S. Si3N4 layers fabricated from -100, +200 mesh Si powder gave better impact improvement than less porous (30%), small particle size layers fabricated from -325 mesh Si powder.

A discrete element modelling approach for block impacts on trees

NASA Astrophysics Data System (ADS)

Toe, David; Bourrier, Franck; Olmedo, Ignatio; Berger, Frederic

2015-04-01

These past few year rockfall models explicitly accounting for block shape, especially those using the Discrete Element Method (DEM), have shown a good ability to predict rockfall trajectories. Integrating forest effects into those models still remain challenging. This study aims at using a DEM approach to model impacts of blocks on trees and identify the key parameters controlling the block kinematics after the impact on a tree. A DEM impact model of a block on a tree was developed and validated using laboratory experiments. Then, key parameters were assessed using a global sensitivity analyse. Modelling the impact of a block on a tree using DEM allows taking into account large displacements, material non-linearities and contacts between the block and the tree. Tree stems are represented by flexible cylinders model as plastic beams sustaining normal, shearing, bending, and twisting loading. Root soil interactions are modelled using a rotation stiffness acting on the bending moment at the bottom of the tree and a limit bending moment to account for tree overturning. The crown is taken into account using an additional mass distribute uniformly on the upper part of the tree. The block is represented by a sphere. The contact model between the block and the stem consists of an elastic frictional model. The DEM model was validated using laboratory impact tests carried out on 41 fresh beech (Fagus Sylvatica) stems. Each stem was 1,3 m long with a diameter between 3 to 7 cm. Wood stems were clamped on a rigid structure and impacted by a 149 kg charpy pendulum. Finally an intensive simulation campaign of blocks impacting trees was done to identify the input parameters controlling the block kinematics after the impact on a tree. 20 input parameters were considered in the DEM simulation model : 12 parameters were related to the tree and 8 parameters to the block. The results highlight that the impact velocity, the stem diameter, and the block volume are the three input parameters that control the block kinematics after impact.

Microstructural development under irradiation in European ODS ferritic/martensitic steels

NASA Astrophysics Data System (ADS)

Schäublin, R.; Ramar, A.; Baluc, N.; de Castro, V.; Monge, M. A.; Leguey, T.; Schmid, N.; Bonjour, C.

2006-06-01

Oxide dispersion strengthened steels based on the ferritic/martensitic steel EUROFER97 are promising candidates for a fusion reactor because of their improved high temperature mechanical properties and their potential higher radiation resistance relative to the base material. Several EUROFER97 based ODS F/M steels are investigated in this study. There are the Plansee ODS steels containing 0.3 wt% yttria, and the CRPP ODS steels, whose production route is described in detail. The reinforcing particles represent 0.3-0.5% weight and are composed of yttria. The effect of 0.3 wt% Ti addition is studied. ODS steel samples have been irradiated with 590 MeV protons to 0.3 and 1.0 dpa at room temperature and 350 °C. Microstructure is investigated by transmission electron microscopy and mechanical properties are assessed by tensile and Charpy tests. While the Plansee ODS presents a ferritic structure, the CRPP ODS material presents a tempered martensitic microstructure and a uniform distribution of the yttria particles. Both materials provide a yield stress higher than the base material, but with reduced elongation and brittle behaviour. Ti additions improve elongation at high temperatures. After irradiation, mechanical properties of the material are only slightly altered with an increase in the yield strength, but without significant decrease in the total elongation, relative to the base material. Samples irradiated at room temperature present radiation induced defects in the form of blacks dots with a size range from 2 to 3 nm, while after irradiation at 350 °C irradiation induced a0<1 0 0>{1 0 0} dislocation loops are clearly visible along with nanocavities. The dispersed yttria particles with an average size of 6-8 nm are found to be stable for all irradiation conditions. The density of the defects and the dispersoid are measured and found to be about 2.3 × 10 22 m -3 and 6.2 × 10 22 m -3, respectively. The weak impact of irradiation on mechanical properties of ODS F/M steel is thus explained by a lower density of irradiation induced defects relative to the density of reinforcing particles.

Mechanical properties of 0.40 pct C-Ni-Cr-Mo high strength steel having a mixed structure of martensite and bainite

NASA Astrophysics Data System (ADS)

Tomita, Yoshiyuki; Okabayashi, Kunio

1985-01-01

A study has been systematically made of the effect of bainite on the mechanical properties of a commercial Japanese 0.40 pct C-Ni-Cr-Mo high strength steel (AISI 4340 type) having a mixed structure of martensite and bainite. Isothermal transformation of lower bainite at 593 K, which appeared in acicular form and partitioned prior austenite grains, in association with tempered marprovided provided a better combination of strength and fracture ductility, improving true notch tensile strength (TNTS) and fracture appearance transition temperature (FATT) in Charpy impact tests. This occurred regardless of the volume fraction of lower bainite present and/or the tempering conditions employed to create a difference in strength between the two phases. Upper bainite which was isothermally transformed at 673 K appeared as masses that filled prior austenite grains and had a very detrimental effect on the strength and fracture ductility of the steel. Significant damage occurred to TNTS and FATT, irrespective of the volume fraction of upper bainite present and/or the tempering conditions employed when the upper bainite was associated with tempered martensite. However, when the above two types of bainite appeared in the same size, shape, and distribution within tempered martensite approximately equalized to the strength of the bainite, a similar trend or a marked similarity was observed between the tensile properties of the mixed structures and the volume fraction of bainite. From the above results, it is assumed that the mechanical properties of high strength steels having a mixed structure of martensite and bainite are affected more strongly by the size, shape, and distribution of bainite within martensite than by the difference in strength between martensite and bainite or by the type of mixed bainite present. The remarkable effects of the size, shape, and distribution of bainite within martensite on the mechanical properties of the steel are briefly discussed in terms of the modified law of mixtures, metallographic examinations, and the analyses of stress-strain diagrams.

Improving the toughness of ultrahigh strength steel

NASA Astrophysics Data System (ADS)

Sato, Koji

2002-01-01

The ideal structural steel combines high strength with high fracture toughness. This dissertation discusses the toughening mechanism of the Fe/Co/Ni/Cr/Mo/C steel, AerMet 100, which has the highest toughness/strength combination among all commercial ultrahigh strength steels. The possibility of improving the toughness of this steel was examined by considering several relevant factors. Chapter 1 reviews the mechanical properties of ultrahigh strength steels and the physical metallurgy of AerMet 100. It also describes the fracture mechanisms of steel, i.e. ductile microvoid coalescence, brittle transgranular cleavage, and intergranular separation. Chapter 2 examines the strength-toughness relationship for three heats of AerMet 100. A wide variation of toughness is obtained at the same strength level. The toughness varies despite the fact that all heat fracture in the ductile fracture mode. The difference originates from the inclusion content. Lower inclusion volume fraction and larger inclusion spacing gives rise to a greater void growth factor and subsequently a higher fracture toughness. The fracture toughness value, JIc, is proportional to the particle spacing of the large non-metallic inclusions. Chapter 3 examines the ductile-brittle transition of AerMet 100 and the effect of a higher austenitization temperature, using the Charpy V-notch test. The standard heat treatment condition of AerMet 100 shows a gradual ductile-brittle transition due to its fine effective grain size. Austenitization at higher temperature increases the prior austenite grain size and packet size, leading to a steeper transition at a higher temperature. Both transgranular cleavage and intergranular separation are observed in the brittle fracture mode. Chapter 4 examines the effect of inclusion content, prior austenite grain size, and the amount of austenite on the strength-toughness relationship. The highest toughness is achieved by low inclusion content, small prior austenite grain size, and a small content of stable austenite. The low inclusion content increases the strain at the fracture. The reduction in prior austenite grain size prevents the fast unstable crack propagation by cleavage. And the stable austenite decreases the strength of the intergranular separation at the prior austenite grain boundary, which provides the stress relief at the crack tip.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakraborty, Gopa, E-mail: gopa_mjs@igcar.gov.in; Das, C.R.; Albert, S.K.

Martensitic stainless steels find extensive applications due to their optimum combination of strength, hardness and wear-resistance in tempered condition. However, this class of steels is susceptible to embrittlement during tempering if it is carried out in a specific temperature range resulting in significant reduction in toughness. Embrittlement of as-normalised AISI 410 martensitic stainless steel, subjected to tempering treatment in the temperature range of 673–923 K was studied using Charpy impact tests followed by metallurgical investigations using field emission scanning electron and transmission electron microscopes. Carbides precipitated during tempering were extracted by electrochemical dissolution of the matrix and identified by X-raymore » diffraction. Studies indicated that temper embrittlement is highest when the steel is tempered at 823 K. Mostly iron rich carbides are present in the steel subjected to tempering at low temperatures of around 723 K, whereas chromium rich carbides (M{sub 23}C{sub 6}) dominate precipitation at high temperature tempering. The range 773–823 K is the transition temperature range for the precipitates, with both Fe{sub 2}C and M{sub 23}C{sub 6} types of carbides coexisting in the material. The nucleation of Fe{sub 2}C within the martensite lath, during low temperature tempering, has a definite role in the embrittlement of this steel. Embrittlement is not observed at high temperature tempering because of precipitation of M{sub 23}C{sub 6} carbides, instead of Fe{sub 2}C, preferentially along the lath and prior austenite boundaries. Segregation of S and P, which is widely reported as one of the causes for temper embrittlement, could not be detected in the material even through Auger electron spectroscopy studies. - Highlights: • Tempering behaviour of AISI 410 steel is studied within 673–923 K temperature range. • Temperature regime of maximum embrittlement is identified as 773–848 K. • Results show that type of carbide precipitation varies with temperature of tempering. • Mostly iron rich Fe{sub 2}C carbides are present in the embrittlement temperature range. • With the precipitation of M{sub 23}C{sub 6} carbides, recovery from the embrittlement begins.« less

PR-EDB: Power Reactor Embrittlement Database - Version 3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Jy-An John; Subramani, Ranjit

2008-03-01

The aging and degradation of light-water reactor pressure vessels is of particular concern because of their relevance to plant integrity and the magnitude of the expected irradiation embrittlement. The radiation embrittlement of reactor pressure vessel materials depends on many factors, such as neutron fluence, flux, and energy spectrum, irradiation temperature, and preirradiation material history and chemical compositions. These factors must be considered to reliably predict pressure vessel embrittlement and to ensure the safe operation of the reactor. Large amounts of data from surveillance capsules are needed to develop a generally applicable damage prediction model that can be used for industrymore » standards and regulatory guides. Furthermore, the investigations of regulatory issues such as vessel integrity over plant life, vessel failure, and sufficiency of current codes, Standard Review Plans (SRPs), and Guides for license renewal can be greatly expedited by the use of a well-designed computerized database. The Power Reactor Embrittlement Database (PR-EDB) is such a comprehensive collection of data for U.S. designed commercial nuclear reactors. The current version of the PR-EDB lists the test results of 104 heat-affected-zone (HAZ) materials, 115 weld materials, and 141 base materials, including 103 plates, 35 forgings, and 3 correlation monitor materials that were irradiated in 321 capsules from 106 commercial power reactors. The data files are given in dBASE format and can be accessed with any personal computer using the Windows operating system. "User-friendly" utility programs have been written to investigate radiation embrittlement using this database. Utility programs allow the user to retrieve, select and manipulate specific data, display data to the screen or printer, and fit and plot Charpy impact data. The PR-EDB Version 3.0 upgrades Version 2.0. The package was developed based on the Microsoft .NET framework technology and uses Microsoft Access for backend data storage, and Microsoft Excel for plotting graphs. This software package is compatible with Windows (98 or higher) and has been built with a highly versatile user interface. PR-EDB Version 3.0 also contains an "Evaluated Residual File" utility for generating the evaluated processed files used for radiation embrittlement study.« less

Development of next generation tempered and ODS reduced activation ferritic/martensitic steels for fusion energy applications

DOE PAGES

Zinkle, S. J.; Boutard, J. L.; Hoelzer, D. T.; ...

2017-06-09

Reduced activation ferritic/martensitic steels are currently the most technologically mature option for the structural material of proposed fusion energy reactors. Advanced next-generation higher performance steels offer the opportunity for improvements in fusion reactor operational lifetime and reliability, superior neutron radiation damage resistance, higher thermodynamic efficiency, and reduced construction costs. The two main strategies for developing improved steels for fusion energy applications are based on (1) an evolutionary pathway using computational thermodynamics modelling and modified thermomechanical treatments (TMT) to produce higher performance reduced activation ferritic/martensitic (RAFM) steels and (2) a higher risk, potentially higher payoff approach based on powder metallurgy techniquesmore » to produce very high strength oxide dispersion strengthened (ODS) steels capable of operation to very high temperatures and with potentially very high resistance to fusion neutron-induced property degradation. The current development status of these next-generation high performance steels is summarized, and research and development challenges for the successful development of these materials are outlined. In conclusion, material properties including temperature-dependent uniaxial yield strengths, tensile elongations, high-temperature thermal creep, Charpy impact ductile to brittle transient temperature (DBTT) and fracture toughness behaviour, and neutron irradiation-induced low-temperature hardening and embrittlement and intermediate-temperature volumetric void swelling (including effects associated with fusion-relevant helium and hydrogen generation) are described for research heats of the new steels.« less

Post-weld Tempered Microstructure and Mechanical Properties of Hybrid Laser-Arc Welded Cast Martensitic Stainless Steel CA6NM

NASA Astrophysics Data System (ADS)

Mirakhorli, Fatemeh; Cao, Xinjin; Pham, Xuan-Tan; Wanjara, Priti; Fihey, Jean-Luc

2016-12-01

Manufacturing of hydroelectric turbine components involves the assembly of thick-walled stainless steels using conventional multi-pass arc welding processes. By contrast, hybrid laser-arc welding may be an attractive process for assembly of such materials to realize deeper penetration depths, higher production rates, narrower fusion, and heat-affected zones, and lower distortion. In the present work, single-pass hybrid laser-arc welding of 10-mm thick CA6NM, a low carbon martensitic stainless steel, was carried out in the butt joint configuration using a continuous wave fiber laser at its maximum power of 5.2 kW over welding speeds ranging from 0.75 to 1.2 m/minute. The microstructures across the weldment were characterized after post-weld tempering at 873 K (600 °C) for 1 hour. From microscopic examinations, the fusion zone was observed to mainly consist of tempered lath martensite and some residual delta-ferrite. The mechanical properties were evaluated in the post-weld tempered condition and correlated to the microstructures and defects. The ultimate tensile strength and Charpy impact energy values of the fully penetrated welds in the tempered condition were acceptable according to ASTM, ASME, and industrial specifications, which bodes well for the introduction of hybrid laser-arc welding technology for the manufacturing of next generation hydroelectric turbine components.

Development of next generation tempered and ODS reduced activation ferritic/martensitic steels for fusion energy applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zinkle, S. J.; Boutard, J. L.; Hoelzer, D. T.

Reduced activation ferritic/martensitic steels are currently the most technologically mature option for the structural material of proposed fusion energy reactors. Advanced next-generation higher performance steels offer the opportunity for improvements in fusion reactor operational lifetime and reliability, superior neutron radiation damage resistance, higher thermodynamic efficiency, and reduced construction costs. The two main strategies for developing improved steels for fusion energy applications are based on (1) an evolutionary pathway using computational thermodynamics modelling and modified thermomechanical treatments (TMT) to produce higher performance reduced activation ferritic/martensitic (RAFM) steels and (2) a higher risk, potentially higher payoff approach based on powder metallurgy techniquesmore » to produce very high strength oxide dispersion strengthened (ODS) steels capable of operation to very high temperatures and with potentially very high resistance to fusion neutron-induced property degradation. The current development status of these next-generation high performance steels is summarized, and research and development challenges for the successful development of these materials are outlined. In conclusion, material properties including temperature-dependent uniaxial yield strengths, tensile elongations, high-temperature thermal creep, Charpy impact ductile to brittle transient temperature (DBTT) and fracture toughness behaviour, and neutron irradiation-induced low-temperature hardening and embrittlement and intermediate-temperature volumetric void swelling (including effects associated with fusion-relevant helium and hydrogen generation) are described for research heats of the new steels.« less

Effect of Quenching Process on Microstructures and Mechanical Properties of Fe-0.9Mn-0.5Cr-2.4Ni-0.5Mo-C Steel

NASA Astrophysics Data System (ADS)

Chen, Jie; Li, Changsheng; Jin, Xin; Chen, Liqing; Fang, Lei

2018-03-01

To develop an appropriate quenching process to produce Fe-0.9Mn-0.5Cr-2.4Ni-0.5Mo-C steel, the microstructures and mechanical properties of this steel were investigated under the direct quenching and tempering (DQT) and the direct quenching, reheated quenching and tempering (DQQT) heat treatment processes. The microstructure of the DQQT specimen was basically tempered sorbite with spherical precipitates, while quite a bit of tempered martensite was in the DQT specimen with dispersive nanoscaled precipitates. The yield strengths of the DQT and DQQT specimens were 1154 and 955 MPa, respectively. The yield strength of the DQT specimen was higher than that of the DQQT specimen because of its finer grain size, higher density of dislocations and dispersed precipitates. The DQQT specimen had spherical precipitates, which hindered the propagation of the crack. Moreover, the high-angle grain boundaries in the DQQT specimen took a higher proportion. Therefore, the Charpy impact values of DQT and DQQT specimens at - 60 °C were 38 and 75 J, respectively. Consequently, the mechanical properties of the Fe-0.9Mn-0.5Cr-2.4Ni-0.5Mo-C steel, which met the standard of 1000 MPa grade steel plate for hydropower station, were acquired by the DQQT process.

Development of low-chromium, chromium-tungsten steels for fusion

NASA Astrophysics Data System (ADS)

Klueh, R. L.; Alexander, D. J.; Kenik, E. A.

1995-12-01

High-chromium (9-12% Cr) CrMo and CrW ferritic steels are favored as candidates for fusion applications. In early work to develop reduced-activation steels, an Fe2.25Cr2W-0.25V-O.1C steel (designated 2.25Cr-2WV) had better strength than an Fe9Cr2W-0.25V-0.07Tra-0.1C (9Cr-2WVTa) steel (compositions are in weight percent). However, the 2.25Cr-2WV had poor impact properties, as determined by the ductile-brittle transition temperature and upper-shelf energy of subsize Charpy impact specimens. Because low-chromium steels have some advantages over high-chromium steels, a program to develop low-chromium steels is in progress. Microstructural analysis indicated that the reason for the inferior impact toughness of the 2.25Cr-2WV was the granular bainite obtained when the steel was normalized. Properties can be improved by developing an acicular bainite microstructure by increasing the cooling rate after austenitization. Alternatively, acicular bainite can be promoted by increasing the hardenability. Hardenability was changed by adding small amounts of boron and additional chromium to the 2.250-2WV composition. A combination of B, Cr, and Ta additions resulted in low-chromium reduced-activation steels with mechanical properties comparable to those of 9Cr-2WVTa.

Effect of cooling after welding on microstructure and mechanical properties of 12 Pct Cr steel weld metals

NASA Astrophysics Data System (ADS)

Cai, Guang-Jun; Andrén, Hans-Olof; Svensson, Lars-Erik

1997-07-01

The microstructure of three 12 pct cr steel weld metals with different nickel and nitrogen contents was studied in as-welded condition and after postweld heat treatment with and without intercooling. Tensile strength and impact toughness of the weld metals were investigated in different postweld heat treatment conditions. In weld metals heat treated without intercooling, austenite decomposed by a eutectoid reaction that resulted in M23C6 aggregates around retained δ-ferrite. Two morphologies of M2N and MN precipitates were found in a low-dislocation α-ferrite. It was concluded that these phases were also transformed from austenite. In weld metals heat treated with intercooling, M23C6 precipitates were smaller and more homogeneously distributed. Different MN precipitates were found in the tempered martensite. The fracture mode of the weld metals at room temperature was mainly transgranular cleavage with some fibrous fracture. Intercooling treatment improved Charpy impact toughness of the 12 pct Cr steel weld metals substantially. It was found that the important microstructural factors affecting the impact toughness of the weld metals which were heat treated without intercooling were the sizes of the α-ferrite grains, nonmetallic inclusions, and M23C6 aggregates. For the weld metals heat treated with intercooling, the factors which affect the toughness of the weld metals were the sizes of martensite packets and nonmetallic inclusions.

Development of next generation tempered and ODS reduced activation ferritic/martensitic steels for fusion energy applications

NASA Astrophysics Data System (ADS)

Zinkle, S. J.; Boutard, J. L.; Hoelzer, D. T.; Kimura, A.; Lindau, R.; Odette, G. R.; Rieth, M.; Tan, L.; Tanigawa, H.

2017-09-01

Reduced activation ferritic/martensitic steels are currently the most technologically mature option for the structural material of proposed fusion energy reactors. Advanced next-generation higher performance steels offer the opportunity for improvements in fusion reactor operational lifetime and reliability, superior neutron radiation damage resistance, higher thermodynamic efficiency, and reduced construction costs. The two main strategies for developing improved steels for fusion energy applications are based on (1) an evolutionary pathway using computational thermodynamics modelling and modified thermomechanical treatments (TMT) to produce higher performance reduced activation ferritic/martensitic (RAFM) steels and (2) a higher risk, potentially higher payoff approach based on powder metallurgy techniques to produce very high strength oxide dispersion strengthened (ODS) steels capable of operation to very high temperatures and with potentially very high resistance to fusion neutron-induced property degradation. The current development status of these next-generation high performance steels is summarized, and research and development challenges for the successful development of these materials are outlined. Material properties including temperature-dependent uniaxial yield strengths, tensile elongations, high-temperature thermal creep, Charpy impact ductile to brittle transient temperature (DBTT) and fracture toughness behaviour, and neutron irradiation-induced low-temperature hardening and embrittlement and intermediate-temperature volumetric void swelling (including effects associated with fusion-relevant helium and hydrogen generation) are described for research heats of the new steels.

Accelerated development of Zr-containing new generation ferritic steels for advanced nuclear reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Lizhen; Yang, Ying; Sridharan, K.

2015-12-01

The mission of the Nuclear Energy Enabling Technologies (NEET) program is to develop crosscutting technologies for nuclear energy applications. Advanced structural materials with superior performance at elevated temperatures are always desired for nuclear reactors, which can improve reactor economics, safety margins, and design flexibility. They benefit not only new reactors, including advanced light water reactors (LWRs) and fast reactors such as the sodium-cooled fast reactor (SFR) that is primarily designed for management of high-level wastes, but also life extension of the existing fleet when component exchange is needed. Developing and utilizing the modern materials science tools (experimental, theoretical, and computationalmore » tools) is an important path to more efficient alloy development and process optimization. The ultimate goal of this project is, with the aid of computational modeling tools, to accelerate the development of Zr-bearing ferritic alloys that can be fabricated using conventional steelmaking methods. The new alloys are expected to have superior high-temperature creep performance and excellent radiation resistance as compared to Grade 91. The designed alloys were fabricated using arc-melting and drop-casting, followed by hot rolling and conventional heat treatments. Comprehensive experimental studies have been conducted on the developed alloys to evaluate their hardness, tensile properties, creep resistance, Charpy impact toughness, and aging resistance, as well as resistance to proton and heavy ion (Fe 2+) irradiation.« less

Digital image analysis to quantify carbide networks in ultrahigh carbon steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hecht, Matthew D.; Webler, Bryan A.; Picard, Yoosuf N., E-mail: ypicard@cmu.edu

A method has been developed and demonstrated to quantify the degree of carbide network connectivity in ultrahigh carbon steels through digital image processing and analysis of experimental micrographs. It was shown that the network connectivity and carbon content can be correlated to toughness for various ultrahigh carbon steel specimens. The image analysis approach first involved segmenting the carbide network and pearlite matrix into binary contrast representations via a grayscale intensity thresholding operation. Next, the carbide network pixels were skeletonized and parceled into braches and nodes, allowing the determination of a connectivity index for the carbide network. Intermediate image processing stepsmore » to remove noise and fill voids in the network are also detailed. The connectivity indexes of scanning electron micrographs were consistent in both secondary and backscattered electron imaging modes, as well as across two different (50 × and 100 ×) magnifications. Results from ultrahigh carbon steels reported here along with other results from the literature generally showed lower connectivity indexes correlated with higher Charpy impact energy (toughness). A deviation from this trend was observed at higher connectivity indexes, consistent with a percolation threshold for crack propagation across the carbide network. - Highlights: • A method for carbide network analysis in steels is proposed and demonstrated. • ImageJ method extracts a network connectivity index from micrographs. • Connectivity index consistent in different imaging conditions and magnifications. • Impact energy may plateau when a critical network connectivity is exceeded.« less

Effect of Aging Isothermal Time on the Microstructure and Room-Temperature Impact Toughness of Fe-24.8Mn-7.3Al-1.2C Austenitic Steel with κ-Carbides Precipitation

NASA Astrophysics Data System (ADS)

Feng, Yifan; Song, Renbo; Pei, Zhongzheng; Song, Renfeng; Dou, Guoyu

2018-03-01

The microstructure and impact toughness of the as-cast Fe-24.8Mn-7.3Al-1.2C austenitic steel after solution treatment and subsequent aging treatment were investigated in the present work. Research on the κ-carbides precipitation behavior was carried out by transmission electron microscope. The results show that nano-sized coherent κ-carbides were obtained in the as-solutionized steel after aging treatment, which produced precipitation hardening. After being aging treated at 550 °C for 1 h, the steel with regular hexagonal grain structure exhibited a good combination of yield strength ( 574 MPa) and room-temperature impact toughness ( 168 J). In the present steel, the typical cube-on-cube orientation relationship between austenite and κ-carbides was observed. However, due to the long aging isothermal time and high C content, the coarse intergranular κ'-carbide was formed and grew along the austenite grain boundary, which caused this orientation relationship to be destroyed and a dramatical increase of the coherency strain energy at grain boundary. Furthermore, serious embrittlement of grain boundaries caused that cleavage cracks trend to propagate along the grain boundaries. Accordingly, the room-temperature impact toughness decreased sharply. After aging isothermal time prolonging to 13 h, the Charpy V-notch impact toughness was only 5 J and fracture mode turned to fully brittle fracture accompanied with flat facets, shear cracks and well-developed secondary crack.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tucker, J. D.; Miller, M. K.; Young, G. A.

Duplex stainless steels are desirable for use in power generation systems due to their attractive combination of strength, corrosion resistance, and cost. However, thermal embrittlement at intermediate homologous temperatures of ~887°F (475°C) and below, via spinodal decomposition, limits upper service temperatures for many applications. New lean grade duplex alloys have improved thermal stability over standard grades and potentially increase the upper service temperature or the lifetime at a given temperature for this class of material. The present work compares the thermal stability of lean grade, alloy 2003 to standard grade, alloy 2205, through a series of isothermal agings between 500°Fmore » (260°C) and 900°F (482°C) for times between 1 and 10,000 hours. Aged samples were characterized by changes in microhardness and impact toughness. Additionally, atom probe tomography was performed to illustrate the evolution of the α-α' phase separation in both alloys at select conditions. Atom probe tomography confirmed that phase separation occurs via spinodal decomposition for both alloys and identified the formation of Ni-Cu-Si-Mn-P clusters in alloy 2205 that may contribute to embrittlement of this alloy. The impact toughness model predictions for upper service temperature show that alloy 2003 can be considered for use in 550°F applications for 80 year service lifetimes based on a Charpy V-notch criteria of 35 ft-lbs at 70°F. Alloy 2205 should be limited to 500°F applications.« less

Structure property relationships in various filled polymers

NASA Astrophysics Data System (ADS)

Yu, Jiong

The toughness of impact modified poly(vinyl chloride) (PVC) compounds was examined using a modified Charpy test. Increasing impact speed resulted in a quasi-brittle to ductile transition in all PVC compounds. In the quasi-brittle region, a PVC of 56,000 Mw fractured through a craze-like damage zone that could be described by a modified Dugdale model. Furthermore, the same molecular weight PVC modified with either 10 pph chlorinated polyethylene (CPE) or 10 pph methylmethacrylate-butadiene-styrene (MBS) impact modifier also conformed to the Dugdale model with the craze-like damage zone. It was found that CPE effectively improved the impact performance of PVC by shifting the quasi-brittle to ductile transition to a higher loading rate. Compared to CPE, MBS was found to be a better impact modifier and resulted in a higher quasi-brittle to ductile transition loading rate in the same PVC matrix. Fracture initiation toughness of all the materials was described by the Hayes-Williams modification of the Dugdale model. The intrinsic brittle fracture energy obtained by extrapolation to zero craze length was determined only by the PVC matrix and was independent of the impact modifier. However, the kinetics of craze growth, and hence the response to rapid loading, depended on the impact modifier. Increasing molecular weight of the PVC resin resulted in a more complex damage zone that was not amendable to the Dugdale analysis. A new in-situ infusion method was used to incorporate small amounts (ca. 1wt%) of metal and metal oxide particles into a polymer matrix. Nano-sized particles were observed by both transmission electron microscopy (TEM) and atomic force microscopy (AFM). Oxygen (O2) and carbon dioxide (CO2) transport properties of the infused materials were investigated using a dynamic diffusion approach in which both testing and purge gases can be controlled. It was discovered that trace amounts (ca. 2%) of hydrogen (H2) in the purge gas was sufficient to considerably reduce the O2 flux of FEP films infused with Palladium (Pd) nano-particles, up to two hundred fold decrease. In contrast, H2 has essentially no effect on the transport of CO2. The generality of the remarkable reduction in oxygen flux was also demonstrated with films of PP, LLDPE, PET, Nylon 6,6 infused with Pd nano-particles. This oxygen scavenging effect became more pronounced at lower oxygen concentrations. The catalytic role of Pd in the reaction of O2 and H2, and the enormous surface area provided by the dispersed nano-particles were responsible for this highly efficient oxygen scavenging effect. (Abstract shortened by UMI.)

Friction Stir Welding of Low-Carbon AISI 1006 Steel: Room and High-Temperature Mechanical Properties

NASA Astrophysics Data System (ADS)

Shunmugasamy, Vasanth C.; Mansoor, Bilal; Ayoub, Georges; Hamade, Ramsey

2018-03-01

Friction stir welding (FSW) is an ecologically benign solid-state joining process. In this work, FSW of low-carbon AISI 1006 steel was carried out to study the microstructure and mechanical properties of the resulting joints at both room temperature (RT) and 200 °C. In the parameter space investigated here, a rotational tool speed and translation feed combination of 1200 rpm and 60 mm/min produced a defect-free weld with balanced mechanical properties and a superior Vickers microhardness profile compared to all other conditions and to base metal (BM). At faster translation feeds (100 and 150 mm/min), wormhole defects were observed in the weld microstructure and were attributed to higher strain rate experienced by the weld zone. Under tensile loading, welded material exhibited yield strength that was up to 86 and 91% of the BM at RT and 200 °C, respectively. On the other hand, tensile strength of welded material was nearly similar to that of the base metal at both RT and 200 °C. However, at both temperatures the tensile ductility of the welded joints was observed to be significantly lower than the BM. Annealing of the 1200 rpm and 60 mm/min FSW specimen resulted in tensile strength of 102% compared to base material and 47% increase in the strain at failure compared to the as-welded specimen. The Charpy impact values revealed up to 62 and 53% increase in the specific impact energy for the 1200 rpm and 60 mm/min welded joints as compared with the BM.

Assessment of thermal embrittlement in duplex stainless steels 2003 and 2205 for nuclear power applications

DOE PAGES

Tucker, J. D.; Miller, M. K.; Young, G. A.

2015-04-01

Duplex stainless steels are desirable for use in power generation systems due to their attractive combination of strength, corrosion resistance, and cost. However, thermal embrittlement at intermediate homologous temperatures of ~887°F (475°C) and below, via spinodal decomposition, limits upper service temperatures for many applications. New lean grade duplex alloys have improved thermal stability over standard grades and potentially increase the upper service temperature or the lifetime at a given temperature for this class of material. The present work compares the thermal stability of lean grade, alloy 2003 to standard grade, alloy 2205, through a series of isothermal agings between 500°Fmore » (260°C) and 900°F (482°C) for times between 1 and 10,000 hours. Aged samples were characterized by changes in microhardness and impact toughness. Additionally, atom probe tomography was performed to illustrate the evolution of the α-α' phase separation in both alloys at select conditions. Atom probe tomography confirmed that phase separation occurs via spinodal decomposition for both alloys and identified the formation of Ni-Cu-Si-Mn-P clusters in alloy 2205 that may contribute to embrittlement of this alloy. The impact toughness model predictions for upper service temperature show that alloy 2003 can be considered for use in 550°F applications for 80 year service lifetimes based on a Charpy V-notch criteria of 35 ft-lbs at 70°F. Alloy 2205 should be limited to 500°F applications.« less

Influence of crystallographic texture in X70 pipeline steels on toughness anisotropy and delamination

NASA Astrophysics Data System (ADS)

Al-Jabr, Haytham M.

The effects of microstructure and crystallographic texture in four commercially-produced API X70 pipeline steels and their relation to planar anisotropy of toughness and delamination were evaluated. The experimental steels were processed through either a hot strip mill, a Steckel mill, or a compact strip mill. Different processing routes were selected to obtain plates with potential variations in the microstructure and anisotropic characteristics. Tensile and Charpy impact testing were used to evaluate the mechanical properties in three orientations: longitudinal (L), transverse (T) and diagonal (D) with respect to the rolling direction to evaluate mechanical property anisotropy. The yield and tensile strengths were higher in the T orientation and toughness was lower in the D orientation for all plates. Delamination was observed in some of the ductile fracture surfaces of the impact samples. To further study the splitting behavior and effects on impact toughness, a modified impact test (MCVN) specimen with side grooves was designed to intensify induced stresses parallel to the notch root and thus facilitate evaluation of delamination. Scanning electron microscopy combined with electron backscattered diffraction (EBSD) were used to evaluate the grain size, microstructural constituents, and crystallographic texture to determine the factors leading to delamination and the anisotropy in toughness. The ferrite grain size is mainly responsible for the differences in DBTTs between the L and T orientations. The higher DBTT in the D orientation observed in pipeline steels is attributed to crystallographic texture. The higher DBTT in the D direction is due to the higher volume fraction of grains having their {100} planes parallel or close to the primary fracture plane for the D orientation. An equation based on a new "brittleness parameter," based on an assessment of grain orientations based on EBSD data, was developed to predict the changes in DBTTs with respect to sample orientation based on grain size and texture. The calculated DBTTs correlated well with the experimental values. The {001} and {113} components are the main preferred orientations that cause brittleness in the D direction, since their {001} planes make an angle less than 20° with the primary fracture plane of the samples oriented in the D direction. It was also concluded that delamination occurs due to banded bainite regions that were oriented such that their {001} planes make a small angle with the rolling plane leading to degradation in crack arrestability. The texture of the banded regions consisted of {001}, {113} or {111} orientations. It was concluded that the {001} and {113} orientations promote splitting because their fracture strengths in the normal direction are low. The {111} orientation has a calculated fracture strength more than twice the {001} and {113} orientations and therefore banded regions with the {111} texture are more susceptible to cleavage fracture perpendicular to the normal direction.

Embrittlement of Intercritically Reheated Coarse Grain Heat-Affected Zone of ASTM4130 Steel

NASA Astrophysics Data System (ADS)

Li, Liying; Han, Tao; Han, Bin

2018-04-01

In this investigation, a thermal welding simulation technique was used to investigate the microstructures and mechanical properties of the intercritically reheated coarse grain heat-affected zone (IR CGHAZ) of ASTM4130 steel. The effect of post weld heat treatment (PWHT) on the toughness of IR CGHAZ was also analyzed. The toughness of IR CGHAZ was measured by means of Charpy impact, and it is found that IR CGHAZ has the lowest toughness which is much lower than that of the base metal regardless of whether PWHT is applied or not. The as-welded IR CGHAZ is mainly composed of ferrite, martensite, and many blocky M-A constituents distributing along grain boundaries and subgrain boundaries in a near-connected network. Also, the prior austenite grains are still as coarse as those in the coarse grain heat-affected zone (CGHAZ). The presence of the blocky M-A constituents and the coarsened austenite grains result in the toughness deterioration of the as-welded IR CGHAZ. Most of the blocky M-A constituents are decomposed to granular bainite due to the effect of the PWHT. However, PWHT cannot refine the prior austenite grains. Thus, the low toughness of IR CGHAZ after PWHT can be attributed to two factors, i.e., the coarsened austenite grains, and the presence of the remaining M-A constituents and granular bainite, which are located at grain boundaries and subgrain boundaries in a near-connected network. The absorbed energy of the IR CGHAZ was increased by about 3.75 times, which means that the PWHT can effectively improve the toughness but it cannot be recovered to the level of base metal.

Effect of Boron on the Strength and Toughness of Direct-Quenched Low-Carbon Niobium Bearing Ultra-High-Strength Martensitic Steel

NASA Astrophysics Data System (ADS)

Hannula, Jaakko; Kömi, Jukka; Porter, David A.; Somani, Mahesh C.; Kaijalainen, Antti; Suikkanen, Pasi; Yang, Jer-Ren; Tsai, Shao-Pu

2017-11-01

The effect of boron on the microstructures and mechanical properties of laboratory-control-rolled and direct-quenched 6-mm-thick steels containing 0.08 wt pct C and 0.02 wt pct Nb were studied. The boron contents were 24 ppm and a residual amount of 4 ppm. Two different finish rolling temperatures (FRTs) of 1093 K and 1193 K (820 °C and 920 °C) were used in the hot rolling trials to obtain different levels of pancaked austenite prior to DQ. Continuous cooling transformation (CCT) diagrams were constructed to reveal the effect of boron on the transformation behavior of these steels. Microstructural characterization was carried out using various microscopy techniques, such as light optical microscopy (LOM) and scanning electron microscopy-electron backscatter diffraction (SEM-EBSD). The resultant microstructures after hot rolling were mixtures of autotempered martensite and lower bainite (LB), having yield strengths in the range 918 to 1067 MPa with total elongations to fracture higher than 10 pct. The lower FRT of 1093 K (820 °C) produced better combinations of strength and toughness as a consequence of a higher degree of pancaking in the austenite. Removal of boron lowered the 34 J/cm2 Charpy-V impact toughness transition temperature from 206 K to 158 K (-67 °C to -115 °C) when the finishing rolling temperature of 1093 K (820 °C) was used without any loss in the strength values compared to the boron-bearing steel. This was due to the finer and more uniform grain structure in the boron-free steel. Contrary to expectations, the difference was not caused by the formation of borocarbide precipitates, as verified by transmission electron microscopy (TEM) investigations, but through the grain coarsening effect of boron.

Strengthening and Toughening of a Heavy Plate Steel for Shipbuilding with Yield Strength of Approximately 690 MPa

NASA Astrophysics Data System (ADS)

Liu, Dongsheng; Cheng, Binggui; Chen, Yuanyuan

2013-01-01

HSLA-100 steel with high content of alloying elements (nominally in wt pct, 3.5 Ni, 1.6 Cu, and 0.6Mo) is now used to produce heavy plates for constructing a hull and drilling platform. We proposed here a substantially leaner steel composition (containing 1.7 Ni, 1.1 Cu, and 0.5Mo) to produce a heavy plate to 80 mm thickness with mechanical properties comparable with those of the HSLA-100 grade. A continuous cooling transformation (CCT) diagram of the steel was constructed. Key parameters of thermal treatment and revealing mechanisms of strengthening and toughening were derived based on industrial production trials. The microstructures of the 80-mm-thick plate were lath-like bainite (LB) at near surface of the quarter thickness ( t/4), and granular bainite (GB)+LB at center thickness ( t/2) after solutionizing and water quenching (Q). The effect of tempering (T) on the microstructures and properties of the plate was investigated. Excellent combination of room temperature strength and low-temperature Charpy V-notch (CVN) toughness approximately equivalent to that of the HSLA 100 grade (YS > 690 MPa, CVN energy >100 J even at 193 K [-80 °C]) was achieved in the plate treated by the QT process with tempering temperature of 898 K (625 °C). The combination of strength and toughness at t/4 is superior to that at t/2 of the plate under both as-quenched and QT conditions. This result is attributed to that the fraction of high-angle grain boundaries (HAGBs) at t/4 is higher than that at t/2.

Evaluation of Crack Arrest Toughness ( K IA) of P91 Steel in Various Cold Worked and Thermally Aged Conditions

NASA Astrophysics Data System (ADS)

Sathyanarayanan, S.; Moitra, A.; Sasikala, G.; Bhaduri, A. K.

2015-02-01

K IA is increasingly being regarded as a characteristic fracture toughness below which cleavage fracture does not occur. Its evaluation from small-sized Charpy specimens would be advantageous for applications in power plant industries. In this study, K IA has been evaluated for P91 steel in various cold worked and thermally aged conditions. Evaluation of K IA requires determination of crack arrest load( P arrest) and crack arrest length( a arrest). The main challenge is in the determination of a arrest due to the non-availability of standard methodologies and the absence of unequivocal microstructural signatures on the fracture surface in this steel to identify crack arrest. a arrest has been determined using the analytical Key- Curve methodology which has proven successful for this steel in unaged condition. The applicability of the Key- Curve method is validated by the good agreement of the determined final crack length with that measured optically on unbroken specimens of N&T and subsequently 15% cold-worked P91 steel which had been previously aged at 650 °C for 5000 h. Mean K IA varies from 47.46 MPa√m (NT steel aged at 600 °C for 5000 h) to 69.85 MPa√m(NT + 15% cw steel aged at 650 °C for 10000 h) for the various cold worked and aged datasets. K IA is found to be an average property unlike initiation toughness ( K Jd) which shows statistical scatter. Mean K IA is found to be in reasonable agreement with the lower bound values of cleavage initiation toughness ( K Jd) for the datasets in this study.

Development and evaluation of P/M processing techniques to improve and control the mechanical properties of metal injection molded parts

NASA Astrophysics Data System (ADS)

Sago, James Alan

Metal Injection Molding (MIM) is one of the most rapidly growing areas of powder metallurgy (P/M) but the growth of MIM into new markets and more demanding applications is limited by two fundamental barriers, the availability of low cost metal powders and a lack of knowledge and understanding of how mechanical properties, especially toughness, are affected by the many parameters in the MIM process. The goals of this study were to investigate solutions to these challenges for MIM. Mechanical alloying (MA) is a technique which can produce a wide variety of powder compositions in a size range suited to MIM and in smaller batches. However MA typically suffers from low production volumes and long milling times. This study will show that a saucer mill can produce sizable volumes of MA powders in times typically less than an hour. The MA process was also used to produce powders of 17-4PH stainless steel and the NiTi shape memory alloy for a MIM feedstock. This study shows that the MA powder characteristics led to successful MIM processing of parts. Previous studies have shown that the toughness of individual MIM parts can vary widely within a single production run and from one producer to another. In the last part of the study a Design of Experiments (DOE) approach was used to evaluate the effects of MIM processing parameters on the mechanical properties. Analysis of Variance produced mathematical models for Charpy impact toughness, hardness, density, and carbon content. Tensile properties did not produce a good model due to processing problems. The models and recommendations for improving both toughness and reproducibility of toughness are presented.

Seam-weld quality of modern ERW/HFI line pipe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Groeneveld, T.P.; Barnes, C.R.

1991-09-01

This study was undertaken to determine whether the seam-weld quality of modern ERW (electric resistance-welded)/HFI (high-frequency induction) welded pipe has been improved and justifies more widespread use of this type of pipe in critical applications. Wider use of ERW/HFI line pipe in gas-transmission lines would be expected to reduce construction costs. Five recently produced, heavy wall pipes fabricated using high-frequency electric-resistance welding (ERW) processes to make the seam weld and one pipe fabricated using the high-frequency induction (HFI) welding process to make the seam weld were studied. Four of the pipes were Grade X-60, one was Grade X-65, and onemore » was Grade X-70. All of the pipes were produced from microalloyed, controlled-rolled steels, and the weld zones were post-weld normalized. Ultrasonic inspection of the seam welds in the six pipe sections evaluated revealed no indications of defects. The tensile properties of all of the weld zones exceeded the minimum specified yield strengths for the respective grades of pipe and all of the pipes exhibited ductile failures either in the weld zone or in the base metal. Five of the six pipes exhibited ductile failures either in the weld zone or in the base metal. Five of the six pipes exhibited relatively low 85% shear area transition temperatures and relatively high upper-shelf energy absorptions as determined with Charpy V-notch specimens. In addition, for two of the three joints of pipe for which the properties were determined at both ends of the pipe, the tensile and impact properties showed little variation from end-to-end. However, for the other joint of pipe, the impact properties varied substantially from one end to the other.« less

ADVANCED INTEGRATION OF MULTI-SCALE MECHANICS AND WELDING PROCESS SIMULATION IN WELD INTEGRITY ASSESSMENT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilkowski, Gery M.; Rudland, David L.; Shim, Do-Jun

2008-06-30

The potential to save trillions of BTU’s in energy usage and billions of dollars in cost on an annual basis based on use of higher strength steel in major oil and gas transmission pipeline construction is a compelling opportunity recognized by both the US Department of Energy (DOE). The use of high-strength steels (X100) is expected to result in energy savings across the spectrum, from manufacturing the pipe to transportation and fabrication, including welding of line pipe. Elementary examples of energy savings include more the 25 trillion BTUs saved annually based on lower energy costs to produce the thinner-walled high-strengthmore » steel pipe, with the potential for the US part of the Alaskan pipeline alone saving more than 7 trillion BTU in production and much more in transportation and assembling. Annual production, maintenance and installation of just US domestic transmission pipeline is likely to save 5 to 10 times this amount based on current planned and anticipated expansions of oil and gas lines in North America. Among the most important conclusions from these studies were: • While computational weld models to predict residual stress and distortions are well-established and accurate, related microstructure models need improvement. • Fracture Initiation Transition Temperature (FITT) Master Curve properly predicts surface-cracked pipe brittle-to-ductile initiation temperature. It has value in developing Codes and Standards to better correlate full-scale behavior from either CTOD or Charpy test results with the proper temperature shifts from the FITT master curve method. • For stress-based flaw evaluation criteria, the new circumferentially cracked pipe limit-load solution in the 2007 API 1104 Appendix A approach is overly conservative by a factor of 4/π, which has additional implications. . • For strain-based design of girth weld defects, the hoop stress effect is the most significant parameter impacting CTOD-driving force and can increase the crack-driving force by a factor of 2 depending on strain-hardening, pressure level as a % of SMYS, and flaw size. • From years of experience in circumferential fracture analyses and experimentation, there has not been sufficient integration of work performed for other industries into analogous problems facing the oil and gas pipeline markets. Some very basic concepts and problems solved previously in these fields could have circumvented inconsistencies seen in the stress-based and strain-based analysis efforts. For example, in nuclear utility piping work, more detailed elastic-plastic fracture analyses were always validated in their ability to predict loads and displacements (stresses and strains). The eventual implementation of these methodologies will result in acceleration of the industry adoption of higher-strength line-pipe steels.« less

Role of alloy additions on strengthening in 17-4 PH stainless steel

NASA Astrophysics Data System (ADS)

Murthy, Arpana Sudershan

Alloy modifications by addition of niobium (Nb), vanadium (V), nitrogen (N) and cobalt (Co) to cast 17-4 PH steel were investigated to determine the effect on mechanical properties. Additions of Nb, V, and N increased the yield strength from 1120 MPa to 1310 MPa while decreased the room temperature charpy V notch (CVN) toughness from 20 J to four Joules. The addition of Co to cast 17-4 PH steel enhanced the yield strength and CVN toughness from 1140 MPa to 1290 MPa and from 3.7 J to 5.5 J, respectively. In the base 17-4 PH steel, an increase in block width from 2.27 ± 0.10 μm in the solution treated condition to 3.06 ± 0.17 μm upon aging at 755 K was measured using orientation image microscopy. Cobalt inhibited recrystallization and block boundary migration during aging resulting in a finer martensitic block structure. The influence of Co on copper (Cu) precipitation in steels was studied using atom probe tomography. A narrower precipitate size distribution was observed in the steels with Co addition. The concentration profile across the matrix / precipitate interface indicated rejection of Co atoms from the copper precipitates. This behavior was observed to be energetically favorable using first principle calculations. The activation energies for Cu precipitation increased from 205 kJ/ mol in the non-cobalt containing alloy, to 243 kJ/ mol, and 272 kJ/ mol in alloys with 3 wt. %Co, and 7 wt. % Co, respectively. The role of Co on Cu precipitation in cast 17-4 PH steel is proposed as follows: (i) Co is rejected out of the Cu precipitate and sets up a barrier to the growth of the Cu precipitate; (ii) results in Cu precipitates of smaller size and narrower distribution; (iii) the coarsening of Cu precipitates is inhibited; and (iv) the activation energy for Cu precipitation increases.

Materials for Advanced Ultrasupercritical Steam Turbines Task 4: Cast Superalloy Development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thangirala, Mani

The Steam Turbine critical stationary structural components are high integrity Large Shell and Valve Casing heavy section Castings, containing high temperature steam under high pressures. Hence to support the development of advanced materials technology for use in an AUSC steam turbine capable of operating with steam conditions of 760°C (1400°F) and 35 Mpa (5000 psia), Casting alloy selection and evaluation of mechanical, metallurgical properties and castability with robust manufacturing methods are mandated. Alloy down select from Phase 1 based on producability criteria and creep rupture properties tested by NETL-Albany and ORNL directed the consortium to investigate cast properties of Haynesmore » 282 and Haynes 263. The goals of Task 4 in Phase 2 are to understand a broader range of mechanical properties, the impact of manufacturing variables on those properties. Scale up the size of heats to production levels to facilitate the understanding of the impact of heat and component weight, on metallurgical and mechanical behavior. GE Power & Water Materials and Processes Engineering for the Phase 2, Task 4.0 Castings work, systematically designed and executed casting material property evaluation, multiple test programs. Starting from 15 lbs. cylinder castings to world’s first 17,000 lbs. poured weight, heavy section large steam turbine partial valve Haynes 282 super alloy casting. This has demonstrated scalability of the material for steam Turbine applications. Activities under Task 4.0, Investigated and characterized various mechanical properties of Cast Haynes 282 and Cast Nimonic 263. The development stages involved were: 1) Small Cast Evaluation: 4 inch diam. Haynes 282 and Nimonic 263 Cylinders. This provided effects of liquidus super heat range and first baseline mechanical data on cast versions of conventional vacuum re-melted and forged Ni based super alloys. 2) Step block castings of 300 lbs. and 600 lbs. Haynes 282 from 2 foundry heats were evaluated which demonstrated the importance of proper heat treat cycles for Homogenization, and Solutionizing parameters selection and implementation. 3) Step blocks casting of Nimonic 263: Carried out casting solidification simulation analysis, NDT inspection methods evaluation, detailed test matrix for Chemical, Tensile, LCF, stress rupture, CVN impact, hardness and J1C Fracture toughness section sensitivity data and were reported. 4) Centrifugal Casting of Haynes 282, weighing 1400 lbs. with hybrid mold (half Graphite and half Chromite sand) mold assembly was cast using compressor casing production tooling. This test provided Mold cooling rates influence on centrifugally cast microstructure and mechanical properties. Graphite mold section out performs sand mold across all temperatures for 0.2% YS; %Elongation, %RA, UTS at 1400°F. Both Stress-LMP and conditional Fracture toughness plots data were in the scatter band of the wrought alloy. 5) Fundamental Studies on Cooling rates and SDAS test program. Evaluated the influence of 6 mold materials Silica, Chromite, Alumina, Silica with Indirect Chills, Zircon and Graphite on casting solidification cooling rates. Actual Casting cooling rates through Liquidus to Solidus phase transition were measured with 3 different locations based thermocouples placed in each mold. Compared with solidification simulation cooling rates and measurement of SDAS, microstructure features were reported. The test results provided engineered casting potential methods, applicable for heavy section Haynes 282 castings for optimal properties, with foundry process methods and tools. 6) Large casting of Haynes 282 Drawings and Engineering FEM models and supplemental requirements with applicable specifications were provided to suppliers for the steam turbine proto type feature valve casing casting. Molding, melting and casting pouring completed per approved Manufacturing Process Plan during 2014 Q4. The partial valve casing was successfully cast after casting methods were validated with solidification simulation analysis and the casting met NDT inspection and acceptance criteria. Heat treated and sectioned to extract trepan samples at different locations comparing with cast on coupons test data. Material properties requisite for design, such as tensile, creep/rupture, LCF, Fracture Toughness, Charpy V-notch chemical analysis testing were carried out. The test results will be presented in the final report. The typical Haynes 282 large size Steam Turbine production casting from Order to Delivery foundry schedule with the activity break up is shown in Figures 107 and 108. • From Purchase Order placement to Casting pouring ~ 26 weeks. 1. Sales and commercial review 3 2. Engineering Drawings/models review 4 3. Pattern and core box manufacturing 6 4. Casting process engineering review 4 5. FEM and solidification simulation analysis 4 6. Gating & Feeder Attachments, Ceramic tiling 2 7. Molding and coremaking production scheduling 6 8. Melting planning and schedule 3 9. Pouring, cooling and shake out 2 • From Pouring to casting Delivery ~ 29 weeks 10. Shot blast and riser cutting, gates removal 3 11. Homogenizing , solutionizing HT furnace prep 4 12. Grinding, Fettling 2 13. Aging HT Cycle, cooling 2 14. VT and LPT NDT inspections 2 15. Radiographic inspection 4 16. Mechanical testing, Chemical analysis test certs 4 17. Casting weld repair upgrades and Aging PWHT 4 18. NDT after weld repairs and casting upgrades 3 19. Casting Final Inspection and test certifications 3 20. Package and delivery 2 Hence the Total Lead time from P.O to Casting delivery is approximately 55 weeks. The Task 4.2 and Task 4.3 activities and reporting completed.« less

Developing and Characterizing Bulk Metallic Glasses for Extreme Applications

NASA Astrophysics Data System (ADS)

Roberts, Scott Nolan

Metallic glasses have typically been treated as a "one size fits all" type of material. Every alloy is considered to have high strength, high hardness, large elastic limits, corrosion resistance, etc. However, similar to traditional crystalline materials, properties are strongly dependent upon the constituent elements, how it was processed, and the conditions under which it will be used. An important distinction which can be made is between metallic glasses and their composites. Charpy impact toughness measurements are performed to determine the effect processing and microstructure have on bulk metallic glass matrix composites (BMGMCs). Samples are suction cast, machined from commercial plates, and semi-solidly forged (SSF). The SSF specimens have been found to have the highest impact toughness due to the coarsening of the dendrites, which occurs during the semi-solid processing stages. Ductile to brittle transition (DTBT) temperatures are measured for a BMGMC. While at room temperature the BMGMC is highly toughened compared to a fully glassy alloy, it undergoes a DTBT by 250 K. At this point, its impact toughness mirrors that of the constituent glassy matrix. In the following chapter, BMGMCs are shown to have the capability of being capacitively welded to form single, monolithic structures. Shear measurements are performed across welded samples, and, at sufficient weld energies, are found to retain the strength of the parent alloy. Cross-sections are inspected via SEM and no visible crystallization of the matrix occurs. Next, metallic glasses and BMGMCs are formed into sheets and eggbox structures are tested in hypervelocity impacts. Metallic glasses are ideal candidates for protection against micrometeorite orbital debris due to their high hardness and relatively low density. A flat single layer, flat BMG is compared to a BMGMC eggbox and the latter creates a more diffuse projectile cloud after penetration. A three tiered eggbox structure is also tested by firing a 3.17 mm aluminum sphere at 2.7 km/s at it. The projectile penetrates the first two layers, but is successfully contained by the third. A large series of metallic glass alloys are created and their wear loss is measured in a pin on disk test. Wear is found to vary dramatically among different metallic glasses, with some considerably outperforming the current state-of-the-art crystalline material (most notably Cu43Zr 43Al7Be7). Others, on the other hand, suffered extensive wear loss. Commercially available Vitreloy 1 lost nearly three times as much mass in wear as alloy prepared in a laboratory setting. No conclusive correlations can be found between any set of mechanical properties (hardness, density, elastic, bulk, or shear modulus, Poisson's ratio, frictional force, and run in time) and wear loss. Heat treatments are performed on Vitreloy 1 and Cu43Zr43Al7Be7. Anneals near the glass transition temperature are found to increase hardness slightly, but decrease wear loss significantly. Crystallization of both alloys leads to dramatic increases in wear resistance. Finally, wear tests under vacuum are performed on the two alloys above. Vitreloy 1 experiences a dramatic decrease in wear loss, while Cu43Zr43Al7Be7 has a moderate increase. Meanwhile, gears are fabricated through three techniques: electrical discharge machining of 1 cm by 3 mm cylinders, semisolid forging, and copper mold suction casting. Initial testing finds the pin on disk test to be an accurate predictor of wear performance in gears. The final chapter explores an exciting technique in the field of additive manufacturing. Laser engineered net shaping (LENS) is a method whereby small amounts of metallic powders are melted by a laser such that shapes and designs can be built layer by layer into a final part. The technique is extended to mixing different powders during melting, so that compositional gradients can be created across a manufactured part. Two compositional gradients are fabricated and characterized. Ti 6Al-4V to pure vanadium was chosen for its combination of high strength and light weight on one end, and high melting point on the other. It was inspected by cross-sectional x-ray diffraction, and only the anticipated phases were present. 304L stainless steel to Invar 36 was created in both pillar and as a radial gradient. It combines strength and weldability along with a zero coefficient of thermal expansion material. Only the austenite phase is found to be present via x-ray diffraction. Coefficient of thermal expansion is measured for four compositions, and it is found to be tunable depending on composition.

The effect of segregation on the austemper transformation and toughness of ductile irons

NASA Astrophysics Data System (ADS)

Lin, B. Y.; Chen, E. T.; Lei, T. S.

1998-06-01

The effect of segregation of alloying elements on the phase transformation of ductile iron during austempering was investigated. Four heats, each containing 0.4%Mn, 1% Cu, 1.5% Ni, or 0.4% Mo (wt%) separately, were melted; then three different sizes of casting bars (3,15, and 75 mm diameter) were poured from each heat. The distribution and the degree of segregation of certain elements were quantitatively analyzed using an electron microprobe. A personal computer (PC)-controlled heat treating system was used to measure electrical resistivity, and the information on resistivity variations was used to analyze the effect of segregation on phase transformations during austempering. Also, Charpy impact and Rockwell hardness tests were performed to determine the effect of segregation on properties. Results of the electron microprobe analysis showed that the degree of segregation of alloy elements increases with an increase in diameter of the casting bars (i.e., an increase of solidification time of castings). The degree of segregation of alloy elements, represented by segregation ratio (SR) (the maximum concentration of element in cell divided by the minimum concentration of element in cell), varied linearly with the casting modulus (M) (volume of casting divided by surface area of casting). Regarding the segregating tendency among alloy elements, positive segregating elements Mn and Mo showed more segregation than the negative segregating elements Si, Cu, and Ni. In addition, segregation of Mo was more significant than Mn, and that for Cu was greater than Ni and Si. Between the time of finishing the first stage and beginning the second stage of bainite reaction in ductile irons, there is a significant “processing window,” At;, for austempering to obtain optimum mechanical properties. From the electrical resistivity data, it was observed that the austempering temperature plays a major role in the processing window. There was a narrow window at 400 ‡C but a larger one at 350 ‡C. Additionally, the microsegregation of alloying elements led to variation of the time of phase transformation for various regions in the grain cells of ductile iron which caused the processing window to decrease. The span of the processing window decreased with an increase in degree of segregation. There was no significant difference in the hardness of the alloys in various diameter specimens. However, the impact toughness was significantly affected by the segregation. The impact values in 15 mm specimens with less degree of segregation were greater than those in 75 mm specimens with significant segregation. The Ni, Cu, and Mn alloys that were austempered to complete the first stage of bainite formation had approximately the same impact values for all diameter samples. The Mo alloy upon austempering produced no bainite, but it had much untransformed retained austenite in the intercellular regions and, therefore, had lower impact values.

DE-NE0000724 - Research Performance Final Report - Investigation of Thermal Aging Effects on the Evolution of Microstructure and Mechanical Properties of Cast Duplex Stainless Steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ankem, Sreeramamurthy; Perea, Daniel E.; Kolli, R. Prakash

This report details the research activities carried out under DOE-NEUP award number DE-NE0000724 concerning the evolution of structural and mechanical properties during thermal aging of CF–3 and CF–8 cast duplex stainless steels (CDSS). The overall objective of this project was to use state-of-the-art characterization techniques to elucidate trends and phenomena in the mechanical and structural evolution of cast duplex stainless steels (CDSS) during thermal aging. These steels are commonly used as structural materials in commercial light water nuclear power plants, undergoing aging for decades in operation as cooling water pipes, pump casings, valve bodies, etc. During extended exposure to thesemore » conditions, CDSS are known to undergo a change in mechanical properties resulting in a loss of ductility, i.e. embrittlement. While it is generally accepted that structural changes within the ferrite phase, such as decomposition into iron (Fe)-rich and chromium (Cr)-rich domains, lead to the bulk embrittlement of the steels, many questions remain as to the mechanisms of embrittlement at multiple length scales. This work is intended to shed insight into the atomic level composition changes, associated kinetic mechanisms, and effects of changing phase structure on micro- and nano-scale deformation that lead to loss of impact toughness and tensile ductility in these steels. In general, this project provides a route to answer some of these major questions using techniques such as 3-dimensional (3-D) atom probe tomography (APT) and real-microstructure finite element method (FEM) modeling, which were not readily available when these steels were originally selected for service in light water reactors. Mechanical properties evaluated by Charpy V-notch impact testing (CVN), tensile testing, and microhardness and nanohardness measurements were obtained for each condition and compared with the initial baseline properties to view trends in deformation behavior during aging. Concurrent analysis of the microstructure and nanostructure by atom probe tomography (APT) and transmission electron microscopy (TEM) provide mechanistic insight into the kinetic and mechanical behavior occurring on the nano-scale. The presence and morphology of the ferrite, austenite, and carbide phases have been characterized, and formation of new phases during aging, including spinodal decomposition products (α- and α'-ferrite) and G-phase, have been observed. The mechanical and structural characterization have been used to create accurate FEM models based on the real micro- and nano-structures of the systems. These models provide new insight into the local deformation behavior of these steels and the effects of each individual phase (including ferrite, austenite, carbides, and spinodal decomposition products) on the evolving bulk mechanical behavior of the system. The project was divided into three major tasks: 1. Initial Microstructure and Mechanical Property Survey and Initiate Heat Treatment; 2. Microstructural Characterization and Mechanical Property Testing During Aging; and 3. Microstructure-based Finite Element Modeling. Each of these tasks was successfully executed, resulting in reliable data and analysis that add to the overall body of work on the CDSS materials. Baseline properties and aging trends in mechanical data confirm prior observations and add new insights into the mechanical behavior of the steels. Structural characterization on multiple length scales provides new information on phase changes occurring during aging and sheds light on the kinetic processes occurring at the atomic scale. Furthermore, a combination of mechanical testing and microstructural characterization techniques was utilized to design FEM models of local deformation behavior of the ferrite and austenite phases, providing valuable new information regarding the effects of each of the microstructural components on the hardening and embrittlement processes. The data and analysis presented in this report and the publication associated with this project (§V) increase the understanding of aging and deformation in CF–3 and CF–8 steels. These results provide valuable information that can be utilized to aid in making informed decisions regarding the ongoing use of these steels in commercial nuclear infrastructure.« less

Novel Sustainable Composites Based on Poly(hydroxybutyrate-co-hydroxyvalerate) and Seagrass Beach-CAST Fibers: Performance and Degradability in Marine Environments.

PubMed

Seggiani, Maurizia; Cinelli, Patrizia; Balestri, Elena; Mallegni, Norma; Stefanelli, Eleonora; Rossi, Alessia; Lardicci, Claudio; Lazzeri, Andrea

2018-05-11

In order to produce sustainable, bio-based and highly biodegradable materials, composites based on poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) and fibers of Posidonia oceanica (PO), a dominant Mediterranean seagrass, were produced by simple melt mixing and characterized in terms of thermal stability, morphology and rheological/mechanical properties. In view of their potential application in marine environments, degradation of the developed composites was evaluated under simulated and real marine environmental conditions for 1 year. Using 10 wt % of acetyl tributyl citrate (ATBC) as a plasticizer, smooth processing was achieved for up to 30 wt % of PO fibers, despite the reduction of the melt fluidity observed with increasing fiber loading. The tensile modulus slightly increased (from 2 to 2.4 GPa) while the tensile strength and the elongation decreased (from 23.6 to 21.5 MPa and from 3.2 to 1.9%, respectively) by increasing the PO fiber content from 0 to 30 wt %. Interestingly, the impact resistance of the composites increased with the increasing of the PO content: the Charpy’s impact energy increased from 3.6 (without fiber) to 4.4 kJ/m² for the composite with 30 wt %. The results of the aerobic biodegradation under simulated marine conditions showed that the presence of PO fibers favored the physical disintegration of the composite increasing the biodegradation rate of the polymeric matrix: after 216 days, the composite with 20 wt % PO fibers showed a biodegradability of about 30% compared to 20% of the composite without fibers. Under real marine conditions, the specimens containing PO fibers showed higher weight losses and deterioration of tensile properties compared to those without fibers. Presumably, biodegradation occurred after colonization of the specimen, and the specimens with 20 wt % PO fibers showed well-developed biofilm consisting of bacteria and fungi on the surface after only 3 months of incubation in marine sediments, unlike the no-fiber specimens. Consequently, the persistence of an adequate mechanical performance for a relatively long period (1 year), due to a moderate rate of biodegradation in the marine environment, make the developed PHBV/PO composites particularly suitable for the production of relatively low-cost and biodegradable items which are usable in the sea and/or sand dunes, increasing the market opportunities for biopolymers such as PHBV and, at the same time, finding an eco-sustainable valorization for the PO fibrous residues accumulated in large quantities on Mediterranean beaches, which represents a problem for coastal municipalities.

Strengthening and toughening mechanisms in low-c microalloyed martensitic steel as influenced by austenite conditioning

NASA Astrophysics Data System (ADS)

Kennett, Shane C.

Three low-carbon ASTM A514 microalloyed steels were used to assess the effects of austenite conditioning on the microstructure and mechanical properties of martensite. A range of prior austenite grain sizes with and without thermomechanical processing were produced in a Gleeble RTM 3500 and direct-quenched. Samples in the as-quenched, low temperature tempered, and high temperature tempered conditions were studied. The microstructure was characterized with scanning electron microscopy, electron backscattered diffraction, transmission electron microscopy, and x-ray diffraction. The uniaxial tensile properties and Charpy V-notch properties were measured and compared with the microstructural features (prior austenite grain size, packet size, block size, lath boundaries, and dislocation density). For the equiaxed prior austenite grain conditions, prior austenite grain size refinement decreases the packet size, decreases the block size, and increases the dislocation density of as-quenched martensite. However, after high temperature tempering the dislocation density decreases with prior austenite grain size refinement. Thermomechanical processing increases the low angle substructure, increases the dislocation density, and decreases the block size of as-quenched martensite. The dislocation density increase and block size refinement is sensitive to the austenite grain size before ausforming. The larger prior austenite grain size conditions have a larger increase in dislocation density, but the small prior austenite grain size conditions have the largest refinement in block size. Additionally, for the large prior austenite grain size conditions, the packet size increases with thermomechanical processing. The strength of martensite is often related to an effective grain size or carbon concentration. For the current work, it was concluded that the strength of martensite is primarily controlled by the dislocation density and dislocation substructure; which is related to a grain size and carbon concentration. In the microyielding regime, the strength and work hardening is related to the motion of unpinned dislocation segments. However, with tensile strain, a dislocation cell structure is developed and the flow strength (greater than 1% offset) is controlled by the dislocation density following a Taylor hardening model, thereby ruling out any grain size effects on the flow strength. Additionally, it is proposed that lath boundaries contribute to strength. It is shown that the strength differences associated with thermomechanically processed steels can be fully accounted for by dislocation density differences and the effect of lath boundaries. The low temperature ductile to brittle transition of martensite is controlled by the martensite block size, packet size, and prior austenite grain size. However, the effect of block size is likely small in comparison. The ductile to brittle transition temperature is best correlated to the inverse square root of the martensite packet size because large crack deflections are typical at packet boundaries.

The development of ultrahigh strength low alloy cast steels with increased toughness

NASA Astrophysics Data System (ADS)

Lynch, Paul C.

This work describes the initial work on the development of the next generation of ultrahigh strength low alloy (UHSLA) cast steels. These UHSLA cast steels have both ultrahigh strength levels and good impact toughness. The influence of heat treatment, secondary processing using hot isostatic processing (HIP), and chemical composition on the microstructure and properties of UHSLA cast steels have been evaluated. The extent of microsegregation reduction expected during the heat treatment of UHSLA cast steels has also been estimated by diffusion modeling. This new family of UHSLA cast steels is similar in composition and properties to UHSLA wrought steels. However, the heat treatment and secondary processing of the UHSLA cast steels is used to develop microstructures and properties typically developed through thermomechanical processing and heat treatment for wrought UHSLA steels. Two martensitic UHSLA steels, 4340+ (silicon modified 4340) and ES-1 were investigated for this study. For the 4340+ alloy, heat treatment variables evaluated include homogenization temperature and time, tempering temperature, and austempering temperature and time. For the ES-1 alloy, heat treatment variables evaluated include homogenization temperature and time, austenization temperature, cryogenic treatment, and tempering temperature. The effect of high temperature hot isostatic processing (HIP) on the 4340+ and ES- 1 alloys was also investigated. Tensile properties, charpy v-notch impact toughness (CVN), microstructures, and fractographs have all been characterized after heat treatment. The effects of HIP on microporosity reduction in the ES-1 alloy were also investigated. The experiments carried out on the investment cast 4340+ alloy have shown that increasing the homogenization temperature can increase CVN without changing the ultimate tensile strength (UTS) or yield strength (YS) of the cast material. By replacing the homogenization step in the conventional heat treatment process with a high temperature HIP treatment, both the CVN and ductility of the alloy was found to increase while maintaining comparable ultimate tensile strength (UTS) and yield strength (YS) levels as compared to the original homogenization treatment. Austempering the (IC) 4340+ material led to a significant increase in CVN and ductility at the expense of UTS and yield strength as the primarily martensitic microstructure was converted to a mixed martensitic-bainitic structure. An initial heat of induction melted, aluminum deoxidized investment cast ES-1 with 0.06 wt % of aluminum showed that the average -40°F and +72°F impact toughness, % elongation, and UTS and YS of the fully heat treated investment cast + HIP ES-1 material lagged significantly behind that of the vacuum degassed cast + HIP ES-1 ingot material. Even though the % elongation and impact toughness of the investment cast ES-1 material changed between heat treatment conditions, the average UTS and YS values remained relatively unchanged throughout the heat treatments for the investment cast study. Etched micrographs of the investment cast ES-1 material showed evidence of significant differences in microsegregation reduction between the samples homogenized at 2125°F for 4 hours and those not homogenized at 2125°F for 4 hours. SEM fracture surface work performed on the investment cast material clearly showed that the induction melted investment and aluminum killed cast material contained significant amounts of MnS and Al2O3 inclusions that were not discovered in the vacuum degassed cast ingot material. Lastly, the results of a third heat of induction melted, aluminum deoxidized investment cast ES-1 material possessing just 0.01wt% of aluminum showed that the decrease in aluminum content from the first experimental heat did not improve the mechanical properties of the investment cast material. (Abstract shortened by UMI.)

Annual progress report on the NSRR experiments, (21)

NASA Astrophysics Data System (ADS)

1992-05-01

Fuel behavior studies under simulated reactivity-initiated accident (RIA) conditions have been performed in the Nuclear Safety Research Reactor (NSRR) since 1975. This report gives the results of experiments performed from April, 1989 through March, 1990 and discussions of them. A total of 41 tests were carried out during this period. The tests are distinguished into pre-irradiated fuel tests and fresh fuel tests; the former includes 2 JMTR pre-irradiated fuel tests, 2 PWR pre-irradiated fuel tests, and 2 BWR pre-irradiated fuel tests, and the latter includes 6 standard fuel tests (6 SP(center dot)CP scoping tests), 7 power and cooling condition parameter tests (4 flow shrouded fuel tests, 1 bundle simulation test, 1 fully water-filled vessel test, 1 high pressure/high temperature loop test), 12 special fuel tests (3 stainless steel clad fuel tests, 3 improved PWR fuel tests, 6 improved BWR fuel tests), 3 severe fuel damage tests (1 high temperature flooding test, 1 flooding behavior observation test, 1 debris coolability test), 3 fast breeder reactor fuel tests (2 moderator material characteristic measurement tests, 1 fuel behavior observation test), and 2 miscellaneous tests (2 preliminary tests for pre-irradiated fuel tests).

Electrical Arc Ignition Testing of Spacesuit Materials

NASA Technical Reports Server (NTRS)

Smith, Sarah; Gallus, Tim; Tapia, Susana; Ball, Elizabeth; Beeson, Harold

2006-01-01

A viewgraph presentation on electrical arc ignition testing of spacesuit materials is shown. The topics include: 1) Background; 2) Test Objectives; 3) Test Sample Materials; 4) Test Methods; 5) Scratch Test Objectives; 6) Cotton Scratch Test Video; 7) Scratch Test Results; 8) Entire Date Plot; 9) Closeup Data Plot; 10) Scratch Test Problems; 11) Poke Test Objectives; 12) Poke Test Results; 13) Poke Test Problems; 14) Wire-break Test Objectives; 15) Cotton Wire-Break Test Video; 16) High Speed Cotton Wire-break Test Video; 17) Typical Data Plot; 18) Closeup Data Plot; 19) Wire-break Test Results; 20) Wire-break Tests vs. Scratch Tests; 21) Urethane-coated Nylon; and 22) Moleskin.

SWI 1.10 Testing Process

NASA Technical Reports Server (NTRS)

Stokes, LeBarian

2009-01-01

This procedure establishes a system for performing testing in the Six-Degree-Of-Freedom Dynamic Test System (SDTS). Testing includes development and verification testing of customer supplied Test Articles (TAs) and other testing requirements, as requested. This procedure applies to all SDTS testing operations and equipment. The procedure provides an overview of testing performed in the SDTS including test identification requirements, test planning and procedure development, test and performance inspection, test data analysis, and test report generation.

Track/train dynamics test report transfer function test. Volume 1: Test

NASA Technical Reports Server (NTRS)

Vigil, R. A.

1975-01-01

A description is presented of the transfer function test performed on an open hopper freight car loaded with 80 tons of coal. Test data and a post-test update of the requirements document and test procedure are presented. Included are a statement of the test objective, a description of the test configurations, test facilities, test methods, data acquisition/reduction operations, and a chronological test summary. An index to the data for the three test configurations (X, Y, and Z-axis tests) is presented along with test sequence, run number, test reference, and input parameters.

21 CFR 660.54 - Potency tests, specificity tests, tests for heterospecific antibodies, and additional tests for...

Code of Federal Regulations, 2010 CFR

2010-04-01

... heterospecific antibodies, and additional tests for nonspecific properties. 660.54 Section 660.54 Food and Drugs..., specificity tests, tests for heterospecific antibodies, and additional tests for nonspecific properties. The...) Specificity tests, tests for heterospecific antibodies, and additional tests for nonspecific properties. [50...

Tests of measurement invariance failed to support the application of the "then-test".

PubMed

Nolte, Sandra; Elsworth, Gerald R; Sinclair, Andrew J; Osborne, Richard H

2009-11-01

The use of then-test (retrospective pre-test) scores has frequently been proposed as a solution to potential confounding of change scores because of response shift, as it is assumed that then-test and post-test responses are provided from the same perspective. However, this assumption has not been formally tested using robust quantitative methods. The aim of this study was to compare the psychometric performance of then-test/post-test with traditional pre-test/post-test data and assessing whether the resulting data structures support the application of the then-test for evaluations of chronic disease self-management interventions. Pre-test, post-test, and then-test data were collected from 314 participants of self-management courses using the Health Education Impact Questionnaire (heiQ). The derived change scores (pre-test/post-test; then-test/post-test) were examined for their psychometric performance using tests of measurement invariance. Few questionnaire items were noninvariant across pre-test/post-test, with four items identified and requiring removal to enable an unbiased comparison of factor means. In contrast, 12 items were identified and required removal in then-test/post-test data to avoid biased change score estimates. Traditional pre-test/post-test data appear to be robust with little indication of response shift. In contrast, the weaker psychometric performance of then-test/post-test data suggests psychometric flaws that may be the result of implicit theory of change, social desirability, and recall bias.

System Testing of Ground Cooling System Components

NASA Technical Reports Server (NTRS)

Ensey, Tyler Steven

2014-01-01

This internship focused primarily upon software unit testing of Ground Cooling System (GCS) components, one of the three types of tests (unit, integrated, and COTS/regression) utilized in software verification. Unit tests are used to test the software of necessary components before it is implemented into the hardware. A unit test determines that the control data, usage procedures, and operating procedures of a particular component are tested to determine if the program is fit for use. Three different files are used to make and complete an efficient unit test. These files include the following: Model Test file (.mdl), Simulink SystemTest (.test), and autotest (.m). The Model Test file includes the component that is being tested with the appropriate Discrete Physical Interface (DPI) for testing. The Simulink SystemTest is a program used to test all of the requirements of the component. The autotest tests that the component passes Model Advisor and System Testing, and puts the results into proper files. Once unit testing is completed on the GCS components they can then be implemented into the GCS Schematic and the software of the GCS model as a whole can be tested using integrated testing. Unit testing is a critical part of software verification; it allows for the testing of more basic components before a model of higher fidelity is tested, making the process of testing flow in an orderly manner.

Fitness for duty in the nuclear power industry: Annual summary of program performance reports CY 1994. Volume 5

DOE Office of Scientific and Technical Information (OSTI.GOV)

Westra, C.; Durbin, N.; Field, I.

This report summarizes the data from the semiannual reports on fitness-for-duty programs submitted to the NRC by utilities for two reporting periods: January 1 through June 30, 1994, and July I through December 31, 1994. During 1994, licensees reported that they had conducted 163,241 tests for the presence of illegal drugs and alcohol. Of these tests, 1,372 (.84%) were confirmed positive. Positive test results varied by category of test and category of worker. The majority of positive test results (977) were obtained through pre-access testing. Of tests conducted on workers having access to the protected area, there were 223 positivemore » tests from random testing and 122 positive tests from for-cause testing. Follow-up testing of workers who had previously tested positive resulted in 50 positive tests. For-cause testing resulted in the highest percentage of positive tests; about 16 percent of for-cause tests were positive. This compares with a positive test rate of 1.22 percent of pre-access tests and .28 percent of random tests. The positive test rate for badged workers (including only random, for-cause, and follow-up test results) was .48 percent. Positive test rates also varied by category of worker. When all types of tests are combined (pre-access, random, for-cause, and follow-up testing), short-term contractor personnel had the highest positive test rate at 1.22 percent. Licensee employees and long-term contractors had lower combined positive test rates (.33% and .49%, respectively). Of the substances tested, marijuana was responsible for the highest percentage of positive test results (52.07%), followed by cocaine (24.25%) and alcohol (17.45%).« less

Initial evaluation tests of General Electric Company 12.0 ampere hour nickel cadmium spacecraft cells with design variables

NASA Technical Reports Server (NTRS)

Harkness, J. D.

1979-01-01

All evaluation tests were performed at room ambient pressure and temperature, with discharges at a 2 hour rate. Tests consisted of phenolphthalein leak tests, three capacity tests, an auxiliary electrode test, a charge retention test, an internal short test, a charge efficiency test, overcharge tests, and a pressure versus capacity test. Results of the tests and recommendations for improvements in manufacturing are presented.

Expectancy of an open-book test decreases performance on a delayed closed-book test.

PubMed

Agarwal, Pooja K; Roediger, Henry L

2011-11-01

Two experiments examined the influence of practice with, and the expectancy of, open-book tests (students viewed studied material while taking the test) versus closed-book tests (students completed the test without viewing the studied material) on delayed retention and transfer. Using GRE materials specifically designed for open-book testing, participants studied passages and then took initial open- or closed-book tests. Open-book testing led to better initial performance than closed-book testing, but on a delayed criterial (closed-book) test both types of testing produced similar retention after a two-day delay in Experiment 1. In Experiment 2 participants were informed in advance about the type of delayed criterial test to expect (open- or closed-book). Expecting an open-book test (relative to a closed-book test) decreased participants' time spent studying and their delayed test performance on closed-book comprehension and transfer tests, demonstrating that test expectancy can influence long-term learning. Expectancy of open-book tests may impair long-term retention and transfer compared to closed-book tests, despite superior initial performance on open-book tests and students' preference for open-book tests.

The inclusion of 'then-test' questions in post-test questionnaires alters post-test responses: a randomized study of bias in health program evaluation.

PubMed

Nolte, Sandra; Elsworth, Gerald R; Sinclair, Andrew J; Osborne, Richard H

2012-04-01

Program evaluations are frequently based on 'then-test' data, i.e., pre-test collected in retrospect. While the application of the then-test has practical advantages, little is known about the validity of then-test data. Because of the collection of then-test in close proximity to post-test questions, this study was aimed at exploring whether the presence of then-test questions in post-test questionnaires influenced subjects' responses to post-test. To test the influence of then-test questions, we designed a randomized three-group study in the context of chronic disease self-management programs. Interventions had comparable goals and philosophies, and all 949 study participants filled out identical Health Education Impact Questionnaires (heiQ) at pre-test. At post-test, participants were then randomized to one of the following three groups: Group A responded to post-test questions only (n = 331); Group B filled out transition questions in addition to post-test (n = 304); and Group C filled out then-test questions in addition to post-test (n = 314). Significant post-test differences were found in six of eight heiQ scales, with respondents who filled out then-test questions reporting significantly higher post-test scores than respondents of the other groups. This study provides evidence that the inclusion of then-test questions alters post-test responses, suggesting that change scores based on then-test data be interpreted with care.

Fitness for duty in the Nuclear Power Industry. Annual summary of program performance reports CY 1993

DOE Office of Scientific and Technical Information (OSTI.GOV)

Westra, C.; Forslund, C.; Field, I.

This report summarizes the data from the semiannual reports on fitness-for-duty programs submitted to the NRC by utilities for two reporting periods: January 1 through June 30, 1993, and July 1 through December 31, 1993. During 1993, licensees reported that they had conducted 242,966 tests for the presence of illegal drugs and alcohol. Of these tests, 1,512 (.62%) were confirmed positive. Positive test results varied by category of test and category of worker. The majority of positive test results (952) were obtained through pre-access testing. Of tests conducted on workers having access to the protected area, there were 341 positivemore » tests from random testing and 163 positive tests from for-cause testing. Follow-up testing of workers who had previously tested positive resulted in 56 positive tests. For-cause testing resulted in the highest percentage of positive tests; about 22 percent of for-cause tests were positive. This compares with a positive test rate of 1.04 percent of pre-access tests and .23 percent of random tests. Positive test rates also varied by category of worker. When all types of tests are combined (pre-access, random, for-cause, and follow-up testing), short-term contractor personnel had the highest positive test rate at.97 percent. Licensee employees and long-term contractors had lower combined positive test rates (.25% and .21%, respectively). Of the substances tested, marijuana was responsible for the highest percentage of positive test results (49.56%), followed by cocaine (23.41 %) and alcohol (22.65%).« less

Test Report of Special Form Qualification Testing for the ORNL U ZipCan

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martinez, Oscar A.

This test report describes the special form testing activities performed on the two ZiPCans. One prototype test unit was subjected to the tests stipulated by 10 CFR 71.75 (d)(1)(i), ISO 2919:1999(E) Class 4 impact test, along with the leak rate test specified in 49 CFR 173.469(a)(4)(i). The other test unit was subjected to a leak rate test as specified in 173.469(a)(4)(i) and a heat test as specified in 49 CFR 173.469 (b)(4). Each test unit was leak tested before and after these respective tests. The leak rate tests performed were helium back-pressure tests and bubble tests, as specified in ANSImore » N14.5-2014.The measured leak rates were converted to standard condition leak rates as specified in ASTM E 493. The determined standardized leak rates from the test and calculation for both test units met the requirements for special form certification.« less

Error response test system and method using test mask variable

NASA Technical Reports Server (NTRS)

Gender, Thomas K. (Inventor)

2006-01-01

An error response test system and method with increased functionality and improved performance is provided. The error response test system provides the ability to inject errors into the application under test to test the error response of the application under test in an automated and efficient manner. The error response system injects errors into the application through a test mask variable. The test mask variable is added to the application under test. During normal operation, the test mask variable is set to allow the application under test to operate normally. During testing, the error response test system can change the test mask variable to introduce an error into the application under test. The error response system can then monitor the application under test to determine whether the application has the correct response to the error.

Understanding pretest and posttest reactions to cognitive ability and personality tests.

PubMed

Chan, D; Schmitt, N; Sacco, J M; DeShon, R P

1998-06-01

To understand the nature of test reactions and their relationship to test performance, the relationships among belief in tests, pretest reactions, test performance, and posttest reactions were modeled for cognitive ability and personality tests. Results from structural equation models that were fitted to responses from 197 undergraduate examinees supported the hypothesized relationships. On the cognitive ability test, pretest reactions affected test performance and mediated the relationship between belief in tests and test performance. Test performance affected posttest reactions even after taking into account the effect of pretest reactions. On the personality test, belief in tests affected pretest and posttest reactions, but the three variables were unrelated to test performance (Conscientiousness scores). Conceptual, methodological, and practical implications of the findings are discussed in the context of research on test reactions and test performance.

What Is Stress Testing?

MedlinePlus

... Research Home / < Back To Health Topics / Stress Testing Stress Testing Also known as What Is Stress Testing? ... test and an imaging stress test. Standard Exercise Stress Test A standard exercise stress test uses an ...

Fitness for duty in the nuclear power industry. Annual summary of program performance reports

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silbernagel, M.; Brichoux, J.; Durbin, N.

This report summarizes the data from the semiannual reports on fitness-for-duty programs submitted to the NRC by utilities for two reporting periods: January 1-June 30, 1995, and July 1 -December 31, 1995. During 1995, licensees reported that they had conducted 150,121 tests for the presence of illegal drugs and alcohol. Of these tests, 1,476 (.98%) were confirmed positive. The majority of positive test results (1, 122) were obtained through pre-access testing. Of tests conducted on workers having access to the protected area, there were 180 positive tests from random testing and 139 positive tests from for-cause testing. Follow-up testing ofmore » workers who had previously tested positive resulted in 35 positive tests. For-cause testing resulted in the highest percentage of positive tests; about 18 percent of for-cause tests were positive. This compares with a positive test rate of 1.41 percent of pre-access tests and .27 percent of random tests. The positive test rate for workers with unescorted access was .50 percent. Positive test rates also varied by category of worker. When all types of tests are combined, short-term contractor personnel had the highest positive test rate at 1.44 percent. Licensee employees and long-term contractors had lower combined positive test rates (.34% and .40%, respectively). Of the substances tested, marijuana was responsible for the highest percentage of positive test results (53.08%), followed by cocaine (24.24%) and alcohol (17.17%). The overall positive test rate for 1995 (.98%) was higher than in 1994 (.84%). Several factors had an impact on the positive test rate across test categories for 1994 and 1995 compared to previous years. These factors include the NRC`s reduction in the mandatory random testing rate from 100 percent to 50 percent, effective in 1994, and initiatives by licensees such as lowered marijuana screening cutoff levels and reported improvements in licensees ability to detect subversion of the process.« less

Fitness for duty in the nuclear power industry. Volume 2, Annual summary of program performance reports, CY 1991

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murphy, S.; Fleming, T.; Westra, C.

This report summarizes the data from the semi-annual reports on fitness-for-duty programs submitted to the NRC by 52 utilities for two reporting periods: January 1, 1991 to June 30,1991, and from July 1, 1991, to December 31, 1991. During 1991, licensees reported that they had conducted 262,597 tests for the presence of illegal drugs and alcohol. Of these tests, 1,722 (.66%) were confirmed positive. Positive test results varied by category of test and category of worker. The majority of positive test results (983) were obtained through pre-access testing. Of tests conducted on workers having access to the protected area, theremore » were 510 positive tests from random testing and 167 positive tests from forcause testing. Follow-up testing of workers who had previously tested positive resulted in 62 positive tests. Forcause testing resulted in the highest percentage of positive tests; about 23 percent of forcause tests were positive. This compares to a positive test rate of .94 percent of preaccess tests and .33 percent of random tests. Positive test rates also varied by category of worker. Overall, short-term contractor personnel had the highest positive test rate at .98 percent. licensee employees and long-term contractors had lower positive test rates (33% and .56%, respectively). Of the substances tested, marijuana was responsible for the highest percentage (42.3%) of positive test results, followed by cocaine (31.2%) and alcohol (22.8%). Positive test results are also reported for NRC administrative regions, for plants experiencing or not experiencing an outage during a six-month period; and for plants located in areas with different rates of population density, crime, and drug and alcohol use. A comparison of positive test results in 1991 with those found in 1990 found a decrease in the positive test rate for each category of test and worker.« less

Fitness for duty in the nuclear power industry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murphy, S.; Fleming, T.; Westra, C.

This report summarizes the data from the semi-annual reports on fitness-for-duty programs submitted to the NRC by 52 utilities for two reporting periods: January 1, 1991 to June 30,1991, and from July 1, 1991, to December 31, 1991. During 1991, licensees reported that they had conducted 262,597 tests for the presence of illegal drugs and alcohol. Of these tests, 1,722 (.66%) were confirmed positive. Positive test results varied by category of test and category of worker. The majority of positive test results (983) were obtained through pre-access testing. Of tests conducted on workers having access to the protected area, theremore » were 510 positive tests from random testing and 167 positive tests from forcause testing. Follow-up testing of workers who had previously tested positive resulted in 62 positive tests. Forcause testing resulted in the highest percentage of positive tests; about 23 percent of forcause tests were positive. This compares to a positive test rate of .94 percent of preaccess tests and .33 percent of random tests. Positive test rates also varied by category of worker. Overall, short-term contractor personnel had the highest positive test rate at .98 percent. licensee employees and long-term contractors had lower positive test rates (33% and .56%, respectively). Of the substances tested, marijuana was responsible for the highest percentage (42.3%) of positive test results, followed by cocaine (31.2%) and alcohol (22.8%). Positive test results are also reported for NRC administrative regions, for plants experiencing or not experiencing an outage during a six-month period; and for plants located in areas with different rates of population density, crime, and drug and alcohol use. A comparison of positive test results in 1991 with those found in 1990 found a decrease in the positive test rate for each category of test and worker.« less

Modification of the Rappaport rapid test in large-scale testing for syphilis. Evaluation of the rapid plate and rapid card tests.

PubMed

Ghinsberg, R; Meir, E; Blumstein, G; Kafeman, R

1975-11-01

The Rappaport rapid (RR) plate and card tests were developed as modifications of the RR tube test to permit rapid and inexpensive screening of large numbers of subjects for the diagnosis of syphilis. More than 2,000 sera were examined in parallel by the Venereal Disease Research Laboratory (VDRL) slide test, the rapid plasma reagin (RPR) card test and the RR plate and card tests. There was complete agreement between the RR plate and card tests and the VDRL slide and RPR card tests in 96.6% of sera. In a selected group of 1,530 sera examined, in addition, by the fluorescent treponemal antibody absorption (FTA-ABS) test, there was agreement between the RR plate and card tests and the FTA-ABS test in 74.3% of sera and between the VDRL and RPR tests and the FTA-ABS test in 73.7% of sera. The RR plate test was found to be sufficiently sensitive and specific for the diagnosis of syphilis, although the VDRL slide test is perhaps more sensitive in primary and late latent syphilis. Since the antigen used in the RR tests is colored and stable and the sera do not require inactivation before the test, the tests are easier to perform than the VDRL slide test: the RR plate and card tests could therefore replace the VDRL test as a screening test, with hardly any loss of accuracy.

A comparison of paper-and-pencil and computerized forms of Line Orientation and Enhanced Cued Recall Tests.

PubMed

Aşkar, Petek; Altun, Arif; Cangöz, Banu; Cevik, Vildan; Kaya, Galip; Türksoy, Hasan

2012-04-01

The purpose of this study was to assess whether a computerized battery of neuropsychological tests could produce similar results as the conventional forms. Comparisons on 77 volunteer undergraduates were carried out with two neuropsychological tests: Line Orientation Test and Enhanced Cued Recall Test. Firstly, students were assigned randomly across the test medium (paper-and-pencil versus computerized). Secondly, the groups were given the same test in the other medium after a 30-day interval between tests. Results showed that the Enhanced Cued Recall Test-Computer-based did not correlate with the Enhanced Cued Recall Test-Paper-and-pencil results. Line Orientation Test-Computer-based scores, on the other hand, did correlate significantly with the Line Orientation Test-Paper-and-pencil version. In both tests, scores were higher on paper-and-pencil tests compared to computer-based tests. Total score difference between modalities was statistically significant for both Enhanced Cued Recall Tests and for the Line Orientation Test. In both computer-based tests, it took less time for participants to complete the tests.

Uptake of Home-Based Syphilis and Human Immunodeficiency Virus Testing Among Male Partners of Pregnant Women in Western Kenya.

PubMed

Mark, Jennifer; Kinuthia, John; Roxby, Alison C; Krakowiak, Daisy; Osoti, Alfred; Richardson, Barbra A; Gone, Molly Ann; Asila, Victor; Parikh, Saloni; Farquhar, Carey

2017-09-01

Few men are tested for syphilis or human immunodeficiency virus (HIV) during their partner's pregnancy, a high-risk period for HIV and syphilis transmission. Offering home-based rapid testing of syphilis to couples during pregnancy can support prevention efforts to reduce transmission of sexually transmitted diseases and adverse pregnancy outcomes. We assessed men's uptake of paired (separate tests, single blood draw) point-of-care syphilis and HIV tests within a randomized controlled trial of pregnant women who received clinic or home partner HIV testing. We evaluated acceptance of paired HIV-syphilis testing during pregnancy or at 6 months postpartum, and evaluated whether addition of syphilis testing affected the uptake of HIV testing among men. Of 601 women, we were unable to meet 101 male partners, and 180 tested before syphilis tests were available. Paired syphilis and HIV testing was offered at home to 80 men during pregnancy and to 230 men postpartum. For syphilis, 93% of men agreed to test during pregnancy and 98% agreed postpartum. For paired syphilis and HIV testing, 91% of men tested for both during pregnancy and 96% tested postpartum. Before syphilis test introduction, 96% of men accepted HIV testing, compared with 95% of men who accepted HIV testing when paired testing was offered. Uptake of syphilis and HIV testing was high among male partners offered couple testing at home. Introducing syphilis testing did not adversely affect HIV testing among men. Point-of-care diagnostics outside facilities can increase testing of male partners who rarely accompany women to antenatal clinics.

Determining predictability and accuracy of thermal and electrical dental pulp tests: An in vivo study.

PubMed

Salgar, Avinash Ramchandra; Singh, Shishir H; Podar, Rajesh S; Kulkarni, Gaurav P; Babel, Shashank N

2017-01-01

Pulp sensitivity testing, even with its limitations and shortcomings, has been and still remains a very helpful aid in endodontic diagnosis. Pulp sensitivity tests extrapolate pulpal health from the sensory response. The aim of the present study was to identify the sensitivity, specificity, positive and negative predictive values (NPVs) of thermal and electrical tests of pulp sensitivity. Pulp tests studied were two cold and heat tests respectively and electrical test. A total of 330 teeth were tested: 198 teeth with vital pulp and 132 teeth with necrotic pulps (disease prevalence of 40%). The ideal standard was established by observing bleeding within the pulp chamber. Sensitivity values of the diagnostic tests were 0.89 and 0.94 for cold test, 0.84 and 0.87 for the heat tests, and 0.75 for electrical pulp test and the specificity values of the diagnostic tests were 0.91 and 0.93 for the cold tests, 0.86 and 0.84 for the heat tests, and 0.90 for electrical pulp test. The NPVs were 0.91 and 0.96 for the cold tests, 0.89 and 0.91 for the heat tests, and 0.84 for electrical pulp test. The positive predictive values were 0.89 and 0.90 for the cold tests, 0.80 and 0.79 for the heat tests and 0.88 for electrical pulp test. The highest accuracy (0.9393) was observed with cold test (icy spray). The cold test done with icy spray was the most accurate method for sensitivity testing.

Fitness for duty in the nuclear power industry. Volume 3, Annual summary of program performance reports, CY 1992

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fleming, T.; Westra, C.; Field, I.

This report summarizes the data from the semi-annual reports on fitness-for-duty programs submitted to the NRC by 52 utilities for two reporting periods: January 1 through June 30, 1992, and July 1 through December 31, 1992. During 1992, licensees reported that they had conducted 266,551 tests for the presence of illegal drugs and alcohol. Of these test, 1,818 (.68%) were confirmed positive. Positive test results varied by category of test and category of worker. The majority of positive test results (1,110) were obtained through pre-access testing. Of tests conducted on workers having access to the protected area, there were 461more » positive tests from random testing and 178 positive tests from for-cause testing. Follow-up testing of workers who had previously tested positive resulted in 69 positive tests. For-cause testing resulted in the highest percentage of positive-tests; about 26% of for-cause tests were positive. This compares to a positive test rate of 1.06 percent of pre-access tests and .29 percent of random tests. Positive test rates also varied by category of worker. Overall, short-term contractor personnel had the highest positive test rate at 1.00 percent. Licensee employees and long-term contractors had lower positive test rates (.29% and .63%, respectively). Of the substances tested, marijuana was responsible for the highest percentage of positive test results (50.3%), followed by cocaine (24.8%) and alcohol (22.6%). Positive test results are also reported for NRC administrative regions and for plants located in areas with different rates of population density.« less

Parent's Guide to Understanding Tests.

ERIC Educational Resources Information Center

CTB / McGraw-Hill, Monterey, CA.

This brief introduction to testing is geared to parents. Types of tests are defined, such as standardized tests, achievement tests, norm referenced tests, criterion referenced tests, and aptitude tests. Various types of scores (grade equivalent, percentile rank, and stanine are also defined, and the uses made of tests by administrators, teachers,…

Fingerprint test data report: FM 5834 test lots No. 1, 3, 4, and 5. [resin matrix composites

NASA Technical Reports Server (NTRS)

1986-01-01

Quality control testing is presented for various lots of resin matrix composites. The tests conducted were filler test, resin test, fabric test, and prepreg test for lots 1, 3, 4, and 5. The results of the tests are presented in chart forms.

Following international trends while subject to past traditions: neuropsychological test use in the Nordic countries.

PubMed

Egeland, Jens; Løvstad, Marianne; Norup, Anne; Nybo, Taina; Persson, Bengt A; Rivera, Diego Fernando; Schanke, Anne-Kristine; Sigurdardottir, Solrun; Arango-Lasprilla, Juan Carlos

2016-01-01

Historically, the neuropsychological test traditions of the four Nordic countries have spanned from the flexible and qualitative tradition of Luria-Christensen to the quantitative large battery approach of Halstead and Kløve-Matthews. This study reports current test use and discusses whether these traditions still influence attitudes toward test use and choice of tests. The study is based on survey data from 702 Nordic neuropsychologists. The average participant used 9 tests in a standard assessment, and 25 tests overall in their practice. Test use was moderated by nationality, competence level, practice profile, and by attitude toward test selection. Participants who chose their tests flexibly used fewer tests than those adhering to the flexible battery approach, but had fewer tests from which to choose. Testing patients with psychiatric disorders was associated with using more tests. IQ, memory, attention, and executive function were the domains with the largest utilization rate, while tests of motor, visual/spatial, and language were used by few. There is a lack of academic achievement tests. Screening tests played a minor role in specialized assessments, and symptom validity tests were seldom applied on a standard basis. Most tests were of Anglo-American origin. New test methods are implemented rapidly in the Nordic countries, but test selection is also characterized by the dominating position of established and much researched tests. The Halstead-Reitan and Luria traditions are currently weak, but national differences in size of test batteries seem to be influenced by these longstanding traditions.

Test Analysis Guidelines

NASA Technical Reports Server (NTRS)

Jeng, Frank F.

2007-01-01

Development of analysis guidelines for Exploration Life Support (ELS) technology tests was completed. The guidelines were developed based on analysis experiences gained from supporting Environmental Control and Life Support System (ECLSS) technology development in air revitalization systems and water recovery systems. Analyses are vital during all three phases of the ELS technology test: pre-test, during test and post test. Pre-test analyses of a test system help define hardware components, predict system and component performances, required test duration, sampling frequencies of operation parameters, etc. Analyses conducted during tests could verify the consistency of all the measurements and the performance of the test system. Post test analyses are an essential part of the test task. Results of post test analyses are an important factor in judging whether the technology development is a successful one. In addition, development of a rigorous model for a test system is an important objective of any new technology development. Test data analyses, especially post test data analyses, serve to verify the model. Test analyses have supported development of many ECLSS technologies. Some test analysis tasks in ECLSS technology development are listed in the Appendix. To have effective analysis support for ECLSS technology tests, analysis guidelines would be a useful tool. These test guidelines were developed based on experiences gained through previous analysis support of various ECLSS technology tests. A comment on analysis from an experienced NASA ECLSS manager (1) follows: "Bad analysis was one that bent the test to prove that the analysis was right to begin with. Good analysis was one that directed where the testing should go and also bridged the gap between the reality of the test facility and what was expected on orbit."

Socio-economic determinants of HIV testing and counselling: a comparative study in four African countries.

PubMed

Obermeyer, Carla Makhlouf; Neuman, Melissa; Hardon, Anita; Desclaux, Alice; Wanyenze, Rhoda; Ky-Zerbo, Odette; Cherutich, Peter; Namakhoma, Ireen

2013-09-01

Research indicates that individuals tested for HIV have higher socio-economic status than those not tested, but less is known about how socio-economic status is associated with modes of testing. We compared individuals tested through provider-initiated testing and counselling (PITC), those tested through voluntary counselling and testing (VCT) and those never tested. Cross-sectional surveys were conducted at health facilities in Burkina Faso, Kenya, Malawi and Uganda, as part of the Multi-country African Testing and Counselling for HIV (MATCH) study. A total of 3659 clients were asked about testing status, type of facility of most recent test and socio-economic status. Two outcome measures were analysed: ever tested for HIV and mode of testing. We compared VCT at stand-alone facilities and PITC, which includes integrated facilities where testing is provided with medical care, and prevention of mother-to-child transmission (PMTCT) facilities. The determinants of ever testing and of using a particular mode of testing were analysed using modified Poisson regression and multinomial logistic analyses. Higher socio-economic status was associated with the likelihood of testing at VCT rather than other facilities or not testing. There were no significant differences in socio-economic characteristics between those tested through PITC (integrated and PMTCT facilities) and those not tested. Provider-initiated modes of testing make testing accessible to individuals from lower socio-economic groups to a greater extent than traditional VCT. Expanding testing through PMTCT reduces socio-economic obstacles, especially for women. Continued efforts are needed to encourage testing and counselling among men and the less affluent. © 2013 John Wiley & Sons Ltd.

Environmental Assessment for Explosives Ordnance Disposal Proficiency Training Range at Wright-Patterson Air Force Base, Ohio

DTIC Science & Technology

2010-06-01

s) __ Test Plt(s) __ Test Trench(es) __ Deep Test(s) __ PZ or Humus Removal __ Testing/Excav. (strategy unknown) __ Mitigation/Block Excavation...Collection __ Surface Collection _Auger/Soil Corer _Shovel Test (s) .lL... Test Pit (s) _Test Trench (es) __ Deep Test (s) _ PZ or Humus Removal

True or False? Tests Stink!

ERIC Educational Resources Information Center

Romain, Trevor; Verdick, Elizabeth

This book is designed to help students become better test takers. It helps them feel more confident and less stressed before, during, and after the test. Section 1, "Tests? Blech!" discusses why it is necessary to test students. Section 2, "Test SOS," presents test-taking hints; top secret information about tests and student behavior during tests;…

GOES Type III Loop Heat Pipe Life Test Results

NASA Technical Reports Server (NTRS)

Ottenstein, Laura

2011-01-01

The GOES Type III Loop Heat Pipe (LHP) was built as a life test unit for the loop heat pipes on the GOES N-Q series satellites. This propylene LHP was built by Dynatherm Corporation in 2000 and tested continuously for approximately 14 months. It was then put into storage for 3 years. Following the storage period, the LHP was tested at Swales Aerospace to verify that the loop performance hadn t changed. Most test results were consistent with earlier results. At the conclusion of testing at Swales, the LHP was transferred to NASA/GSFC for continued periodic testing. The LHP has been set up for testing in the Thermal Lab at GSFC since 2006. A group of tests consisting of start-ups, power cycles, and a heat transport limit test have been performed every six to nine months since March 2006. Tests results have shown no change in the loop performance over the five years of testing. This presentation will discuss the test hardware, test set-up, and tests performed. Test results to be presented include sample plots from individual tests, along with conductance measurements for all tests performed.

Propulsion Test Handbook: MSFC and SSC. Draft 01

NASA Technical Reports Server (NTRS)

Hammond, John M.

2010-01-01

This Handbook was prepared to provide Propulsion Test Personnel a central source of fundamental reference material. The Testing Process, which is a three-part process of pre-test activities, testing, and post-test activities, involves a collaborative effort from the mechanical, electrical, safety, and environmental disciplines in the test environment. Pre-test activities, testing, and post-test activities processes will vary, per test requirements; however, the content of this Handbook should cover basic procedures and standards that are shared across Centers.

Validation of NHB 8060.1C, Test 18 Arc Tracking, September 30, 1991

NASA Technical Reports Server (NTRS)

Linley, Larry

2005-01-01

A test project was conducted to validate Test 18 of NASA Handbook (NHB) 8060.1C and, if necessary, identify and recommend improvements in the procedures or criteria of the test. The NHB 8060.1C, Test 18 test system was modified to produce better discrimination of test results. Changes, and their effects on test results, in the graphite immersion-depth, test timing sequence, and atmospheric conditions were investigated for the wire-insulation constructions tested. Based on the test results, the graphite immersion-depths (between 0.8 mm and 1.6 mm), the timing sequence, and the change in the test conditions from ambient to three environments common in manned spaceflight did not significantly affect test results. The criteria used in Test 18 of NHB 8060.1C was found to be appropriate for qualifying arc-tracking and arc-propagation characteristics of wire-insulation materials, Using the Test 18 criteria, Kapton and ETFE were considered inappropriate for use, while PTFE was considered appropriate. Recommendations from this test project for Test 18 of NHB 8060.1C include changing the experimental setup and configurational tests and performing qualification testing in air rather than in the three environments common in manned spaceflight.

Laboratory Diagnostics Market in East Africa: A Survey of Test Types, Test Availability, and Test Prices in Kampala, Uganda.

PubMed

Schroeder, Lee F; Elbireer, Ali; Jackson, J Brooks; Amukele, Timothy K

2015-01-01

Diagnostic laboratory tests are routinely defined in terms of their sensitivity, specificity, and ease of use. But the actual clinical impact of a diagnostic test also depends on its availability and price. This is especially true in resource-limited settings such as sub-Saharan Africa. We present a first-of-its-kind report of diagnostic test types, availability, and prices in Kampala, Uganda. Test types (identity) and availability were based on menus and volumes obtained from clinical laboratories in late 2011 in Kampala using a standard questionnaire. As a measure of test availability, we used the Availability Index (AI). AI is the combined daily testing volumes of laboratories offering a given test, divided by the combined daily testing volumes of all laboratories in Kampala. Test prices were based on a sampling of prices collected in person and via telephone surveys in 2015. Test volumes and menus were obtained for 95% (907/954) of laboratories in Kampala city. These 907 laboratories offered 100 different test types. The ten most commonly offered tests in decreasing order were Malaria, HCG, HIV serology, Syphilis, Typhoid, Urinalysis, Brucellosis, Stool Analysis, Glucose, and ABO/Rh. In terms of AI, the 100 tests clustered into three groups: high (12 tests), moderate (33 tests), and minimal (55 tests) availability. 50% and 36% of overall availability was provided through private and public laboratories, respectively. Point-of-care laboratories contributed 35% to the AI of high availability tests, but only 6% to the AI of the other tests. The mean price of the most commonly offered test types was $2.62 (range $1.83-$3.46). One hundred different laboratory test types were in use in Kampala in late 2011. Both public and private laboratories were critical to test availability. The tests offered in point-of-care laboratories tended to be the most available tests. Prices of the most common tests ranged from $1.83-$3.46.

Correlation between skin-prick testing, individual specific IgE tests, and a multiallergen IgE assay for allergy detection in patients with chronic rhinitis.

PubMed

Cho, Jae Hoon; Suh, Jeffrey D; Kim, Jin Kook; Hong, Seok-Chan; Park, Il-Ho; Lee, Heung-Man

2014-01-01

Allergy test results can differ based on the method used. The most common tests include skin-prick testing (SPT) and in vitro tests to detect allergen-specific IgE. This study was designed to assess allergy test results using SPT, individual specific IgE tests, and a multiallergen IgE assay (multiple allergen simultaneous test) in patients with chronic rhinitis and controls. One hundred forty total patients were prospectively enrolled in the study, including 100 patients with chronic rhinitis and 40 control patients without atopy. All eligible patients underwent SPT, serum analysis using individual specific IgE test, and multiple allergen simultaneous test against 10 common allergens. Allergy test results were then compared to identify correlation and interest agreement. There was an 81-97% agreement between SPT and individual specific IgE test in allergen detection and an 80-98% agreement between SPT and multiple allergen simultaneous test. Individual specific IgE test and multiple allergen simultaneous test allergy detection prevalence was generally similar to SPT in patients with chronic rhinitis. All control patients had negative SPT (0/40), but low positive results were found with both individual specific IgE test (5-12.5%) and multiple allergen simultaneous test (2.5-7.5%) to some allergens, especially cockroach, Dermatophagoides farina, and ragweed. Agreement and correlation between individual specific IgE test and multiple allergen simultaneous test were good to excellent for a majority of tested allergens. This study shows good agreement and correlation between SPT with individual specific IgE test and multiple allergen simultaneous test on a majority of the tested allergens for patients with chronic rhinitis. Comparing the two in vitro tests, individual specific IgE test agrees with SPT better than multiple allergen simultaneous test.

VIEW OF EAST TEST SITE FROM TOP OF STATIC TEST ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF EAST TEST SITE FROM TOP OF STATIC TEST TOWER VIEW INCLUDES STRUCTURAL DYNAMICS TEST STAND COLD CALIBRATION TEST STAND AND COMPONENTS TEST LAB. - Marshall Space Flight Center, East Test Area, Dodd Road, Huntsville, Madison County, AL

Shuttle payload vibroacoustic test plan evaluation

NASA Technical Reports Server (NTRS)

Stahle, C. V.; Gongloff, H. R.; Young, J. P.; Keegan, W. B.

1977-01-01

Statistical decision theory is used to evaluate seven alternate vibro-acoustic test plans for Space Shuttle payloads; test plans include component, subassembly and payload testing and combinations of component and assembly testing. The optimum test levels and the expected cost are determined for each test plan. By including all of the direct cost associated with each test plan and the probabilistic costs due to ground test and flight failures, the test plans which minimize project cost are determined. The lowest cost approach eliminates component testing and maintains flight vibration reliability by performing subassembly tests at a relatively high acoustic level.

Anonymous HIV testing: the impact of availability on demand in Arizona.

PubMed Central

Hirano, D; Gellert, G A; Fleming, K; Boyd, D; Englender, S J; Hawks, H

1994-01-01

The purpose of this study was to evaluate the impact of anonymous testing availability on human immunodeficiency virus (HIV) test demand in Arizona. Testing patterns before and after the introduction of anonymous testing were compared. Client knowledge of new test policy and delay in testing until an anonymous option was available were assessed. Test numbers among men who have sex with men showed a statistically significant increase after introduction of an anonymous testing option. Arizona continues to maintain anonymous testing availability. Public health agencies should consider how test policy may influence people's HIV test decisions. PMID:7998649

Performance on a work-simulating firefighter test versus approved laboratory tests for firefighters and applicants.

PubMed

von Heimburg, Erna; Medbø, Jon Ingulf; Sandsund, Mariann; Reinertsen, Randi Eidsmo

2013-01-01

Firefighters must meet minimum physical demands. The Norwegian Labour Inspection Authority (NLIA) has approved a standardised treadmill walking test and 3 simple strength tests for smoke divers. The results of the Trondheim test were compared with those of the NLIA tests taking into account possible effects of age, experience level and gender. Four groups of participants took part in the tests: 19 young experienced firefighters, 24 senior male firefighters and inexperienced applicants, 12 male and 8 female. Oxygen uptake (VO2) at exhaustion rose linearly by the duration of the treadmill test. Time spent on the Trondheim test was closely related to performance time and peak VO2 on the treadmill test. Senior experienced firefighters did not perform better than equally fit young applicants. However, female applicants performed poorer on the Trondheim test than on the treadmill test. Performance on the Trondheim test was not closely related to muscle strength beyond a minimum. CONCLUSION. Firefighters completing the Trondheim test in under 19 min fit the requirements of the NLIA treadmill test. The Trondheim test can be used as an alternative to the NLIA tests for testing aerobic fitness but not for muscular strength. Women's result of the Trondheim test were poorer than the results of the NLIA treadmill test, probably because of their lower body mass.

Preferences for HIV test characteristics among young, Black Men Who Have Sex With Men (MSM) and transgender women: Implications for consistent HIV testing.

PubMed

Frye, Victoria; Wilton, Leo; Hirshfield, Sabina; Chiasson, Mary Ann; Lucy, Debbie; Usher, DaShawn; McCrossin, Jermaine; Greene, Emily; Koblin, Beryl

2018-01-01

Promoting consistent HIV testing is critical among young, Black Men Who Have Sex With Men (MSM) and transgender women who are overrepresented among new HIV cases in the United States. New HIV test options are available, including mobile unit testing, one-minute testing, at home or self-testing and couples HIV testing and counseling (CHTC). In the context of these newer options, the objective of this study was to explore whether and how preferences for specific characteristics of the tests acted as barriers to and/or facilitators of testing in general and consistent testing specifically among young Black MSM and transgender women aged 16 to 29. We conducted 30 qualitative, semi-structured, in-depth interviews with young, Black, gay, bisexual or MSM and transgender women in the New York City metropolitan area to identify preferences for specific HIV tests and aspects of HIV testing options. Participants were primarily recruited from online and mobile sites, followed by community-based, face-to-face recruitment strategies to specifically reach younger participants. Thematic coding was utilized to analyze the qualitative data based on a grounded theoretical approach. We identified how past experiences, perceived test characteristics (e.g., accuracy, cost, etc.) and beliefs about the "fit" between the individual, and the test relate to preferred testing methods and consistent testing. Three major themes emerged as important to preferences for HIV testing methods: the perceived accuracy of the test method, venue characteristics, and lack of knowledge or experience with the newer testing options, including self-testing and CHTC. These findings suggest that increasing awareness of and access to newer HIV testing options (e.g., free or reduced price on home or self-tests or CHTC available at all testing venues) is critical if these new options are to facilitate increased levels of consistent testing among young, Black MSM and transgender women. Addressing perceptions of test accuracy and supporting front line staff in creating welcoming and safe testing environments may be key intervention targets. Connecting young Black MSM and transgender women to the best test option, given preferences for specific characteristics, may support more and more consistent HIV testing.

Choosing HIV Counseling and Testing Strategies for Outreach Settings: A Randomized Trial.

PubMed

Spielberg, Freya; Branson, Bernard M; Goldbaum, Gary M; Lockhart, David; Kurth, Ann; Rossini, Anthony; Wood, Robert W

2005-03-01

In surveys, clients have expressed preferences for alternatives to traditional HIV counseling and testing. Few data exist to document how offering such alternatives affects acceptance of HIV testing and receipt of test results. This randomized controlled trial compared types of HIV tests and counseling at a needle exchange and 2 bathhouses to determine which types most effectively ensured that clients received test results. Four alternatives were offered on randomly determined days: (1) traditional test with standard counseling, (2) rapid test with standard counseling, (3) oral fluid test with standard counseling, and (4) traditional test with choice of written pretest materials or standard counseling. Of 17,010 clients offered testing, 7014 (41%) were eligible; of those eligible, 761 (11%) were tested: 324 at the needle exchange and 437 at the bathhouses. At the needle exchange, more clients accepted testing (odds ratio [OR] = 2.3; P < 0.001) and received results (OR = 2.6; P < 0.001) on days when the oral fluid test was offered compared with the traditional test. At the bathhouses, more clients accepted oral fluid testing (OR = 1.6; P < 0.001), but more clients overall received results on days when the rapid test was offered (OR = 1.9; P = 0.01). Oral fluid testing and rapid blood testing at both outreach venues resulted in significantly more people receiving test results compared with traditional HIV testing. Making counseling optional increased testing at the needle exchange but not at the bathhouses.

NASA Wiring for Space Applications Program: Fiscal year 1994 - 1995 testing activities

NASA Technical Reports Server (NTRS)

Johnson, Harry T.; Hirsch, David

1995-01-01

The results of the testing of wire insulation materials for space applications is presented in this report. The wire insulations tested were partially fluorinated polyimide, extruded ETFE, extruded PTFE, PTFE tape, and PTFE/Kapton. The tests performed were flammability tests, odor tests, compatibility tests with aerospace fluids, offgassing tests, and thermal vacuum stability tests.

40 CFR 86.163-00 - Spot check correlation procedures for vehicles tested using a simulation of the environmental...

Code of Federal Regulations, 2010 CFR

2010-07-01

... vehicles tested using a simulation of the environmental test cell for air conditioning emission testing. 86... tested using a simulation of the environmental test cell for air conditioning emission testing. This section is applicable for vehicles which are tested using a simulation of the environmental test cell...

40 CFR 86.163-00 - Spot check correlation procedures for vehicles tested using a simulation of the environmental...

Code of Federal Regulations, 2013 CFR

2013-07-01

... vehicles tested using a simulation of the environmental test cell for air conditioning emission testing. 86... tested using a simulation of the environmental test cell for air conditioning emission testing. This section is applicable for vehicles which are tested using a simulation of the environmental test cell...

40 CFR 86.163-00 - Spot check correlation procedures for vehicles tested using a simulation of the environmental...

Code of Federal Regulations, 2012 CFR

2012-07-01

... vehicles tested using a simulation of the environmental test cell for air conditioning emission testing. 86... tested using a simulation of the environmental test cell for air conditioning emission testing. This section is applicable for vehicles which are tested using a simulation of the environmental test cell...

40 CFR 86.163-00 - Spot check correlation procedures for vehicles tested using a simulation of the environmental...

Code of Federal Regulations, 2011 CFR

2011-07-01

... vehicles tested using a simulation of the environmental test cell for air conditioning emission testing. 86... tested using a simulation of the environmental test cell for air conditioning emission testing. This section is applicable for vehicles which are tested using a simulation of the environmental test cell...

40 CFR 86.163-00 - Spot check correlation procedures for vehicles tested using a simulation of the environmental...

Code of Federal Regulations, 2014 CFR

2014-07-01

... vehicles tested using a simulation of the environmental test cell for air conditioning emission testing. 86... tested using a simulation of the environmental test cell for air conditioning emission testing. This section is applicable for vehicles which are tested using a simulation of the environmental test cell...

NASA Wiring for Space Applications Program: Fiscal year 1994 - 1995 testing activities

NASA Astrophysics Data System (ADS)

Johnson, Harry T.; Hirsch, David

1995-11-01

The results of the testing of wire insulation materials for space applications is presented in this report. The wire insulations tested were partially fluorinated polyimide, extruded ETFE, extruded PTFE, PTFE tape, and PTFE/Kapton. The tests performed were flammability tests, odor tests, compatibility tests with aerospace fluids, offgassing tests, and thermal vacuum stability tests.

Fingerprint test data report: FM 5064J (Kaiser) lots No. 1 (K) - No. 4 (K). [resin matrix composites

NASA Technical Reports Server (NTRS)

1986-01-01

Quality control tests are presented for resin matrix and carbon-carbon composites. Tests performed are filler test, resin test, prepregs test, and fabric test. The test results are presented in chart form.

Effect of test concentration in the ready biodegradability test for chemical substances: Improvement of OECD test guideline 301C.

PubMed

Nabeoka, Ryosuke; Taruki, Masanori; Kayashima, Takakazu; Yoshida, Tomohiko; Kameya, Takashi

2016-01-01

In Japan, understanding the environmental persistence of chemicals is very important for risk assessment, and ready biodegradability tests are mainly conducted according to the Organisation for Economic Co-operation and Development test guideline 301C. However, the highest test concentration specified in test guideline 301C, 100 mg/L, may cause microbial toxicity and incomplete biodegradation. The authors performed test guideline 301C tests at test concentrations of 30 mg/L for 13 substances that were readily biodegradable in ready biodegradability tests but not in test guideline 301C tests. Of the 5 substances with potential to cause microbial toxicity at 100 mg/L, the percentage of biodegradation of sodium dimethyldithiocarbamate, 4-chloro-3-cresol (CC), thymol (THY), and p-tert-butyl-α-methylbenzenepropionaldehyde measured by biochemical oxygen demand (BOD) increased in the test guideline 301C test at 30 mg/L, suggesting a reduction in toxicity effects. Furthermore, CC and THY met the criteria for ready biodegradability, which are more than 60% of biodegradation by BOD and a 10-d window. Of the 8 substances with a low potential for causing microbial toxicity at 100 mg/L, the percentage of biodegradation of only 2-(diethylamino)ethanol increased in the test guideline 301C test at 30 mg/L. Employing a lower test concentration in the standard test guideline 301C test will contribute to improvement of consistency between results of a test guideline 301C test and other ready biodegradability tests. © 2015 SETAC.

A Framework for Testing Scientific Software: A Case Study of Testing Amsterdam Discrete Dipole Approximation Software

NASA Astrophysics Data System (ADS)

Shao, Hongbing

Software testing with scientific software systems often suffers from test oracle problem, i.e., lack of test oracles. Amsterdam discrete dipole approximation code (ADDA) is a scientific software system that can be used to simulate light scattering of scatterers of various types. Testing of ADDA suffers from "test oracle problem". In this thesis work, I established a testing framework to test scientific software systems and evaluated this framework using ADDA as a case study. To test ADDA, I first used CMMIE code as the pseudo oracle to test ADDA in simulating light scattering of a homogeneous sphere scatterer. Comparable results were obtained between ADDA and CMMIE code. This validated ADDA for use with homogeneous sphere scatterers. Then I used experimental result obtained for light scattering of a homogeneous sphere to validate use of ADDA with sphere scatterers. ADDA produced light scattering simulation comparable to the experimentally measured result. This further validated the use of ADDA for simulating light scattering of sphere scatterers. Then I used metamorphic testing to generate test cases covering scatterers of various geometries, orientations, homogeneity or non-homogeneity. ADDA was tested under each of these test cases and all tests passed. The use of statistical analysis together with metamorphic testing is discussed as a future direction. In short, using ADDA as a case study, I established a testing framework, including use of pseudo oracles, experimental results and the metamorphic testing techniques to test scientific software systems that suffer from test oracle problems. Each of these techniques is necessary and contributes to the testing of the software under test.

Mononucleosis spot test

MedlinePlus

Monospot test; Heterophile antibody test; Heterophile agglutination test; Paul-Bunnell test; Forssman antibody test ... The mononucleosis spot test is done when symptoms of mononucleosis are ... Fatigue Fever Large spleen (possibly) Sore throat Tender ...

Investigating Barriers in HIV-Testing Oncology Patients: The IBITOP Study, Phase I.

PubMed

Merz, Laurent; Zimmermann, Stefan; Peters, Solange; Cavassini, Matthias; Darling, Katharine E A

2016-10-01

Although the prevalence of non-AIDS-defining cancers (non-ADCs) among people living with HIV is rising, we observed HIV testing rates below 5% at our oncology center, against a regional HIV prevalence of 0.2%-0.4%. We performed the Investigating Barriers in HIV-Testing Oncology Patients (IBITOP) study among oncology physicians and patients. Between July 1 and October 31, 2013, patients of unknown HIV status newly diagnosed with solid-organ non-ADCs referred to Lausanne University Hospital Oncology Service, Switzerland, were offered free HIV testing as part of their oncology work-up. The primary endpoints were (a) physician willingness to offer and patient acceptance of HIV testing and (b) physicians' reasons for not offering testing. Of 239 patients of unknown HIV status with a new non-ADC diagnosis, 43 (18%) were offered HIV testing, of whom 4 declined (acceptance rate: 39 of 43; 91%). Except for 21 patients tested prior to oncology consultation, 175 patients (of 239; 73%) were not offered testing. Testing rate declined among patients who were >70 years old (12% versus 30%; p = .04); no non-European patients were tested. Physicians gave reasons for not testing in 16% of cases, the main reason being patient follow-up elsewhere (10 patients; 5.7%). HIV testing during the IBITOP study increased the HIV testing rate to 18%. Although the IBITOP study increased HIV testing rates, most patients were not tested. Testing was low or nonexistent among individuals at risk of late HIV presentation (older patients and migrants). Barriers to testing appear to be physician-led, because patient acceptance of testing offered was very high (91%). In November 2013, the Swiss HIV testing recommendations were updated to propose testing in cancer patients. Phase II of the IBITOP study is examining the effect of these recommendations on HIV testing rates and focusing on physician-led testing barriers. Patients of unknown HIV status newly diagnosed with solid-organ non-AIDS-defining cancers were offered free HIV testing. Physician and patient barriers to HIV testing were examined. Most patients (82%) were not offered testing, and testing of individuals at risk of late HIV presentation (older patients and migrants) was low or nonexistent. Conversely, patient acceptance of testing offered was very high (91%), suggesting that testing barriers in this setting are physician-led. Since this study, the Swiss HIV testing recommendations now advise testing cancer patients before chemotherapy. Phase II of the Investigating Barriers in HIV-Testing Oncology Patients study is examining the effect of these recommendations on testing rates and physician barriers. ©AlphaMed Press.

Terrestrial photovoltaic cell process testing

NASA Technical Reports Server (NTRS)

Burger, D. R.

1985-01-01

The paper examines critical test parameters, criteria for selecting appropriate tests, and the use of statistical controls and test patterns to enhance PV-cell process test results. The coverage of critical test parameters is evaluated by examining available test methods and then screening these methods by considering the ability to measure those critical parameters which are most affected by the generic process, the cost of the test equipment and test performance, and the feasibility for process testing.

Terrestrial photovoltaic cell process testing

NASA Astrophysics Data System (ADS)

Burger, D. R.

The paper examines critical test parameters, criteria for selecting appropriate tests, and the use of statistical controls and test patterns to enhance PV-cell process test results. The coverage of critical test parameters is evaluated by examining available test methods and then screening these methods by considering the ability to measure those critical parameters which are most affected by the generic process, the cost of the test equipment and test performance, and the feasibility for process testing.

Society of Flight Test Engineers, Annual Symposium, 21st, Garden Grove, CA, Aug. 6-10, 1990, Proceedings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1990-01-01

The present conference on flight testing encompasses avionics, flight-testing programs, technologies for flight-test predictions and measurements, testing tools, analysis methods, targeting techniques, and flightline testing. Specific issues addressed include flight testing of a digital terrain-following system, a digital Doppler rate-of-descent indicator, a high-technology testbed, a low-altitude air-refueling flight-test program, techniques for in-flight frequency-response testing for helicopters, limit-cycle oscillation and flight-flutter testing, and the research flight test of a scaled unmanned air vehicle. Also addressed are AV-8B V/STOL performance analysis, incorporating pilot-response time in failure-case testing, the development of pitot static flightline testing, targeting techniques for ground-based hover testing, a low-profilemore » microsensor for aerodynamic pressure measurement, and the use of a variable-capacitance accelerometer for flight-test measurements.« less

Guidelines for testing and release procedures

NASA Technical Reports Server (NTRS)

Molari, R.; Conway, M.

1984-01-01

Guidelines and procedures are recommended for the testing and release of the types of computer software efforts commonly performed at NASA/Ames Research Center. All recommendations are based on the premise that testing and release activities must be specifically selected for the environment, size, and purpose of each individual software project. Guidelines are presented for building a Test Plan and using formal Test Plan and Test Care Inspections on it. Frequent references are made to NASA/Ames Guidelines for Software Inspections. Guidelines are presented for selecting an Overall Test Approach and for each of the four main phases of testing: (1) Unit Testing of Components, (2) Integration Testing of Components, (3) System Integration Testing, and (4) Acceptance Testing. Tools used for testing are listed, including those available from operating systems used at Ames, specialized tools which can be developed, unit test drivers, stub module generators, and the use of format test reporting schemes.

Locating hardware faults in a parallel computer

DOEpatents

Archer, Charles J.; Megerian, Mark G.; Ratterman, Joseph D.; Smith, Brian E.

2010-04-13

Locating hardware faults in a parallel computer, including defining within a tree network of the parallel computer two or more sets of non-overlapping test levels of compute nodes of the network that together include all the data communications links of the network, each non-overlapping test level comprising two or more adjacent tiers of the tree; defining test cells within each non-overlapping test level, each test cell comprising a subtree of the tree including a subtree root compute node and all descendant compute nodes of the subtree root compute node within a non-overlapping test level; performing, separately on each set of non-overlapping test levels, an uplink test on all test cells in a set of non-overlapping test levels; and performing, separately from the uplink tests and separately on each set of non-overlapping test levels, a downlink test on all test cells in a set of non-overlapping test levels.

The validity of three tests of temperament in guppies (Poecilia reticulata).

PubMed

Burns, James G

2008-11-01

Differences in temperament (consistent differences among individuals in behavior) can have important effects on fitness-related activities such as dispersal and competition. However, evolutionary ecologists have put limited effort into validating their tests of temperament. This article attempts to validate three standard tests of temperament in guppies: the open-field test, emergence test, and novel-object test. Through multiple reliability trials, and comparison of results between different types of test, this study establishes the confidence that can be placed in these temperament tests. The open-field test is shown to be a good test of boldness and exploratory behavior; the open-field test was reliable when tested in multiple ways. There were problems with the emergence test and novel-object test, which leads one to conclude that the protocols used in this study should not be considered valid tests for this species. (PsycINFO Database Record (c) 2008 APA, all rights reserved).

Correlation Results for a Mass Loaded Vehicle Panel Test Article Finite Element Models and Modal Survey Tests

NASA Technical Reports Server (NTRS)

Maasha, Rumaasha; Towner, Robert L.

2012-01-01

High-fidelity Finite Element Models (FEMs) were developed to support a recent test program at Marshall Space Flight Center (MSFC). The FEMs correspond to test articles used for a series of acoustic tests. Modal survey tests were used to validate the FEMs for five acoustic tests (a bare panel and four different mass-loaded panel configurations). An additional modal survey test was performed on the empty test fixture (orthogrid panel mounting fixture, between the reverb and anechoic chambers). Modal survey tests were used to test-validate the dynamic characteristics of FEMs used for acoustic test excitation. Modal survey testing and subsequent model correlation has validated the natural frequencies and mode shapes of the FEMs. The modal survey test results provide a basis for the analysis models used for acoustic loading response test and analysis comparisons

The General Mission Analysis Tool (GMAT) System Test Plan

NASA Technical Reports Server (NTRS)

Conway, Darrel J.; Hughes, Steven P.

2007-01-01

This document serves as the System Test Approach for the GMAT Project. Preparation for system testing consists of three major stages: 1) The Test Approach sets the scope of system testing, the overall strategy to be adopted, the activities to be completed, the general resources required and the methods and processes to be used to test the release. It also details the activities, dependencies and effort required to conduct the System Test. 2) Test Planning details the activities, dependencies and effort required to conduct the System Test. 3) Test Cases documents the tests to be applied, the data to be processed, the automated testing coverage and the expected results. This document covers the first two of these items, and established the framework used for the GMAT test case development. The test cases themselves exist as separate components, and are managed outside of and concurrently with this System Test Plan.

VIEW OF EAST TEST SITE FROM TOP OF STATIC TEST ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

VIEW OF EAST TEST SITE FROM TOP OF STATIC TEST TOWER VIEW INCLUDES POWER PLANT TEST STAND AND SATURN V TEST STAND IN THE WEST TEST AREA (FAR BACKGROUND). - Marshall Space Flight Center, East Test Area, Dodd Road, Huntsville, Madison County, AL

9 CFR 145.14 - Testing.

Code of Federal Regulations, 2011 CFR

2011-01-01

... microagglutination test, the enzyme-linked immunosorbent assay test (ELISA), or the rapid serum test for all poultry... react on rapid serum test or enzyme-labeled immunosorbent assay test (ELISA), or blood from birds that... inhibition (HI) test, the microhemagglutination inhibition test, the enzyme-linked immunosorbent assay (ELISA...

Energy Systems Test Area (ESTA). Power Systems Test Facilities

NASA Technical Reports Server (NTRS)

Situ, Cindy H.

2010-01-01

This viewgraph presentation provides a detailed description of the Johnson Space Center's Power Systems Facility located in the Energy Systems Test Area (ESTA). Facilities and the resources used to support power and battery systems testing are also shown. The contents include: 1) Power Testing; 2) Power Test Equipment Capabilities Summary; 3) Source/Load; 4) Battery Facilities; 5) Battery Test Equipment Capabilities Summary; 6) Battery Testing; 7) Performance Test Equipment; 8) Battery Test Environments; 9) Battery Abuse Chambers; 10) Battery Abuse Capabilities; and 11) Battery Test Area Resources.

Lab Test Information

MedlinePlus

... Mumps Tests MPV Blood Test Mucus in Urine N Nitrites in Urine P Pap Smear Porphyrin Test ... V Vitamin D Test Vitamin E (tocopherol) Test Y Yeast Infection Test Related MedlinePlus Health Topics Laboratory ...