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Sample records for alloy steel welds

  1. Friction Stir Welding of Steel Alloys

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey; Munafo, Paul M. (Technical Monitor)

    2001-01-01

    The friction stir welding process has been developed primarily for the welding of aluminum alloys. Other higher melting allows such, as steels are much more difficult to join. Special attention must be given to pin tool material selection and welding techniques. This paper addresses the joining of steels and other high melting point materials using the friction stir welding process. Pin tool material and welding parameters will be presented. Mechanical properties of weldments will also be presented. Significance: There are many applications for the friction stir welding process other than low melting aluminum alloys. The FSW process can be expanded for use with high melting alloys in the pressure vessel, railroad and ship building industries.

  2. Phase transformations and microstructure development in low alloy steel welds

    SciTech Connect

    Babu, S.S.; David, S.A.; Vitek, J.M.

    1995-07-01

    Microstructure development in low alloy steel welds depends on various phase transformations that are a function of weld heating and cooling. The phase changes include non-metallic oxide inclusion formation in the liquid state, weld pool solidification, and solid state transformations. In this paper the mechanism of inclusion formation during low alloy steel welding is considered and the model predictions are compared with published results. The effect of inclusions on the austenite to ferrite transformation kinetics is measured and the mechanisms of transformation are discussed. The austenite gain development is related to the driving force for transformation of {delta} ferrite to austenite.

  3. Interfacial characterization of joint between mild steel and aluminum alloy welded by resistance spot welding

    SciTech Connect

    Qiu Ranfeng; Shi Hongxin; Zhang Keke; Tu Yimin; Iwamoto, Chihiro; Satonaka, Shinobu

    2010-07-15

    The interfacial characteristics of resistance spot welded steel-aluminum alloy joint have been investigated using electron microscopy. The results reveal that reaction product FeAl{sub 3} is generated in the peripheral region of the weld while a reaction layer consisting of Fe{sub 2}Al{sub 5} adjacent to steel and FeAl{sub 3} adjacent to aluminum alloy forms in the central region of the weld, and that the morphology and thickness of the reaction layer vary with the position at the welding interface.

  4. Welding techniques for high alloy austenitic stainless steel

    SciTech Connect

    Gooch, T.G.; Woollin, P.

    1996-11-01

    Factors controlling corrosion resistance of weldments in high alloy austenitic stainless steel are described, with emphasis on microsegregation, intermetallic phase precipitation and nitrogen loss from the molten pool. The application is considered of a range of welding processes, both fusion and solid state. Autogenous fusion weldments have corrosion resistance below that of the parent, but low arc energy, high travel speed and use of N{sub 2}-bearing shielding gas are recommended for best properties. Conventional fusion welding practice is to use an overalloyed nickel-base filler metal to avoid preferential weld metal corrosion, and attention is given to the effects of consumable composition and level of weldpool dilution by base steel. With non-matching consumables, overall joint corrosion resistance may be limited by the presence of a fusion boundary unmixed zone: better performance may be obtained using solid state friction welding, given appropriate component geometry. Overall, the effects of welding on superaustenitic steels are understood, and the materials have given excellent service in welded fabrications. The paper summarizes recommendations on preferred welding procedure.

  5. Effect of welding process on the microstructure and properties of dissimilar weld joints between low alloy steel and duplex stainless steel

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Lu, Min-xu; Zhang, Lei; Chang, Wei; Xu, Li-ning; Hu, Li-hua

    2012-06-01

    To obtain high-quality dissimilar weld joints, the processes of metal inert gas (MIG) welding and tungsten inert gas (TIG) welding for duplex stainless steel (DSS) and low alloy steel were compared in this paper. The microstructure and corrosion morphology of dissimilar weld joints were observed by scanning electron microscopy (SEM); the chemical compositions in different zones were detected by energy-dispersive spectroscopy (EDS); the mechanical properties were measured by microhardness test, tensile test, and impact test; the corrosion behavior was evaluated by polarization curves. Obvious concentration gradients of Ni and Cr exist between the fusion boundary and the type II boundary, where the hardness is much higher. The impact toughness of weld metal by MIG welding is higher than that by TIG welding. The corrosion current density of TIG weld metal is higher than that of MIG weld metal in a 3.5wt% NaCl solution. Galvanic corrosion happens between low alloy steel and weld metal, revealing the weakness of low alloy steel in industrial service. The quality of joints produced by MIG welding is better than that by TIG welding in mechanical performance and corrosion resistance. MIG welding with the filler metal ER2009 is the suitable welding process for dissimilar metals jointing between UNS S31803 duplex stainless steel and low alloy steel in practical application.

  6. [Evaluation of exposure to fumes arising during welding of non-alloyed and low-alloyed steel by various methods].

    PubMed

    Matczak, W; Chmielnicka, J

    1988-01-01

    Evaluated in the paper is welders' exposure to fumes resulting from welding of nonalloyed and low-alloyed steel, whether pure or coated with protective layers, using two most popular welding techniques for those types of steel, i.e. metal active gas welding (MAG) and manual welding with covered electrode (MMA). Due to different chemical composition of fumes at particular workstations, the proper hygienic evaluation was based on measurements of individual concentrations of fumes in workers' breathing zone. A considerable contribution of the combined exposure was yielded by such fume constituents as manganese, ferrum and zinc (welding of steel coated with zinc protective layers), also chromium (welding of low- and -highalloyed steel), as well as copper (metal gas welding). The highest combined exposure (10-fold allowable value) was that of welders of steel coated with the zinc layer, using the metal active gas welding. PMID:3237059

  7. Laser Overlap Welding of Zinc-coated Steel on Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Kashani, Hamed Tasalloti; Kah, Paul; Martikainen, Jukka

    Local reinforcement of aluminum with laser welded patches of zinc-coated steel can effectively contribute to crashworthiness, durability and weight reduction of car body. However, the weld between Zn-coated steel and aluminum is commonly susceptible to defects such as spatter, cavity and crack. The vaporization of Zn is commonly known as the main source of instability in the weld pool and cavity formation, especially in a lap joint configuration. Cracks are mainly due to the brittle intermetallic compounds growing at the weld interface of aluminum and steel. This study provides a review on the main metallurgical and mechanical concerns regarding laser overlap welding of Zn-coated steel on Al-alloy and the methods used by researchers to avoid the weld defects related to the vaporization of Zn and the poor metallurgical compatibility between steel and aluminum.

  8. High Power Laser Welding. [of stainless steel and titanium alloy structures

    NASA Technical Reports Server (NTRS)

    Banas, C. M.

    1972-01-01

    A review of recent developments in high power, carbon dixoide laser welding is presented. Deep penetration welding in stainless steel to 0.5-in. thick, high speed welding in thin gage rimmed steel and gas shielded welding in Ti-6Al-4V alloy are described. The effects of laser power, power density, focusing optics, gas-shielding techniques, material properties and weld speed on weld quality and penetration are discussed. It is shown that laser welding performance in thin materials is comparable to that of electron beams. It is further shown that high quality welds, as evidenced by NDT, mechanical and metal-lographic tests, can be achieved. The potential of the laser for industrial welding applications is indicated.

  9. Factors affecting the strength of multipass low-alloy steel weld metal

    NASA Technical Reports Server (NTRS)

    Krantz, B. M.

    1972-01-01

    The mechanical properties of multipass high-strength steel weld metals depend upon several factors, among the most important being: (1) The interaction between the alloy composition and weld metal cooling rate which determines the as-deposited microstructure; and (2) the thermal effects of subsequent passes on each underlying pass which alter the original microstructure. The bulk properties of a multipass weld are therefore governed by both the initial microstructure of each weld pass and its subsequent thermal history. Data obtained for a high strength low alloy steel weld metal confirmed that a simple correlation exists between mechanical properties and welding conditions if the latter are in turn correlated as weld cooling rate.

  10. Microstructure and corrosion behavior of shielded metal arc-welded dissimilar joints comprising duplex stainless steel and low alloy steel

    NASA Astrophysics Data System (ADS)

    Srinivasan, P. Bala; Muthupandi, V.; Sivan, V.; Srinivasan, P. Bala; Dietzel, W.

    2006-12-01

    This work describes the results of an investigation on a dissimilar weld joint comprising a boiler-grade low alloy steel and duplex stainless steel (DSS). Welds produced by shielded metal arc-welding with two different electrodes (an austenitic and a duplex grade) were examined for their microstructural features and properties. The welds were found to have overmatching mechanical properties. Although the general corrosion resistance of the weld metals was good, their pitting resistance was found to be inferior when compared with the DSS base material.

  11. 76 FR 36086 - Certain Circular Welded Non-Alloy Steel Pipe From Mexico: Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-21

    ... Antidumping Duty Changed Circumstances Review: Certain Circular Welded Non-Alloy Steel Pipe from Mexico, 75 FR... Review: Certain Circular Welded Non-Alloy Steel Pipe and Tube from Mexico, 74 FR 41681 (August 18, 2009...-Rolled Carbon Quality Steel Products from Brazil, 70 FR 58683 (October 7, 2005); see also...

  12. Influence of zirconium on microstructure and toughness of low-alloy steel weld metals

    NASA Astrophysics Data System (ADS)

    Trindade, V. B.; Mello, R. S. T.; Payão, J. C.; Paranhos, R. P. R.

    2006-06-01

    The influence of zirconium on microstructure and toughness of low-alloy steel weld metal was studied. Weld metals with different zirconium contents were obtained adding iron-zirconium alloy in the welding flux formulation. Weld metal chemical composition proved that zirconium was able to be transferred from the flux to the weld metal. The addition of zirconium refined the weld metal microstructure, increasing the acicular ferrite content. Weld metal toughness, determined by means of impact Charpy-V tests, showed that the zirconium addition is beneficial up to a content of 0.005 wt.%. Above this level, zirconium was not able to produce further microstructure refinement, although the toughness was reduced, possibly due to the formation of microconstituent such as the martensite-austenite constituent (M-A), which is considered to be deleterious to the weld metal toughness.

  13. Microstructure evaluation in low alloy steel weld metal from convective heat transfer calculations in three dimensions

    SciTech Connect

    Mundra, K.; DebRoy, T.; Babu, S.S.; David, S.A.

    1995-12-31

    Heat transfer and fluid flow during manual metal arc welding of low alloy steels were investigated by solving the equations of conservation of mass, momentum, and energy in three dimensions. Cooling rates were calculated at various locations in the weldment. Calculated cooling rates were coupled with an existing phase transformation model to predict percentages of acicular, allotriomorphic, and Widmanstaetten ferrites in various low alloy steel welds containing different concentration of V and Mn. Computed microstructures were in good agreement with experiment, indicating promise for predicting weld metal microstructure from the fundamentals of transport phenomena.

  14. Friction Stir Lap Welding of Magnesium Alloy to Steel: A Preliminary Investigation

    NASA Astrophysics Data System (ADS)

    Jana, S.; Hovanski, Y.; Grant, G. J.

    2010-12-01

    An initial study was made to evaluate the feasibility of joining magnesium alloy AZ31 sheet to galvanized steel sheet in a lap configuration using friction stir welding (FSW). Two different automotive sheet steels were used for comparative evaluation of the dissimilar joining potential: a 0.8 mm thick, electrogalvanized (EG) mild steel, and a 1.5 mm thick hot-dipped galvanized (HDG) high-strength, low-alloy (HSLA) steel. These steels were joined to 2.33 mm thick AZ31B magnesium sheet. A single FSW tool design was used for both dissimilar welds, and the process parameters were kept the same. The average peak load for the AZ31-1.5 mm steel weld joint in lap shear mode was found to be 6.3 ± 1.0 kN. For the AZ31-0.8 mm steel weld, joint strength was 5.1 ± 1.5 kN. Microstructural investigation indicates melting of the Zn coating present on the steel sheets, and subsequent alloying with the Mg sheet resulted in the formation of a solidified Zn-Mg alloy layer.

  15. Friction Stir Lap Welding of Magnesium Alloy to Steel: A Preliminary Investigation

    SciTech Connect

    Jana, Saumyadeep; Hovanski, Yuri; Grant, Glenn J.

    2010-12-01

    An initial study was made to evaluate the feasibility of joining Magnesium alloy AZ31 sheet to galvanized steel sheet in lap configuration using friction stir welding (FSW). Two different automotive sheet steels were used for comparative evaluation of the dissimilar joining potential; a 0.8mm thick, electro galvanized (EG) mild steel, and a 1.5mm thick hot dipped galvanized (HDG) high-strength, low-alloy steel (HSLA). These steels were joined to 2.33mm thick AZ31B magnesium sheet. A single FSW tool design was used for both dissimilar welds, and process parameters were kept the same. Average peak load for the AZ31-1.5 mm steel weld joint in lap shear mode was found to be 6.3 ± 1.0 kN. For the AZ31-0.8 mm steel weld, joint strength was 5.1 ± 1.5 kN. Microstructural investigation indicates melting of the Zn coating at the interface and subsequent alloying with the Mg sheet resulting in formation of solidified Zn-Mg alloy layer at AZ31/steel interface.

  16. Effect of oxide inclusions on the solid state transformation in low-alloy steel fusion welds

    SciTech Connect

    Babu, S.S.; David, S.A.; Vitek, J.M.

    1995-12-31

    Non-metallic inclusions are known to influence the properties of low alloy steel weld metal by altering the microstructure development. Isothermal transformation kinetics of austenite to acicular ferrite and allotriomorphic ferrite were measured in reheated low alloy steel weld deposits with similar weld compositions and austenite grain size but different inclusion characteristics. Accelerated kinetics of the transformation to acicular ferrite were observed in the weld metal containing coarser titanium-rich inclusions. The results are also discussed in relation to the predictions of inclusion model. The kinetics of the transformation to allotriomorphic ferrite were not influenced by a change in the inclusion characteristics, but, rather, by a change in austenite grain size. A theoretical analysis of austenite grain development during weld cooling is considered in this work. The austenite grain size was found to depend on the driving force for transformation from 6 ferrite to austenite ({Delta}G{sup {sigma}->{gamma}}) calculated from ThermoCalc{trademark} software.

  17. 77 FR 8808 - Circular Welded Non-Alloy Steel Pipe From the Republic of Korea: Extension of the Final Results...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-15

    ... From the Republic of Korea: Preliminary Results of the Antidumping Duty Administrative Review, 76 FR... International Trade Administration Circular Welded Non-Alloy Steel Pipe From the Republic of Korea: Extension of... antidumping duty administrative review of circular welded non-alloy steel pipe from the Republic of...

  18. 78 FR 17637 - Certain Circular Welded Non-Alloy Steel Pipe from Mexico: Notice of Amended Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-22

    ... Antidumping Duty Administrative Review and Rescission of Administrative Review in Part, 75 FR 20342 (April 19... International Trade Administration Certain Circular Welded Non-Alloy Steel Pipe from Mexico: Notice of Amended... welded non-alloy steel pipe from Mexico. The period of review (POR) is November 1, 2007, through...

  19. 76 FR 40689 - Certain Circular Welded Non-Alloy Steel Pipe From the Republic of Korea: Extension of Time Limit...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-11

    ... Revocation in Part, 75 FR 81565 (December 28, 2010). The current deadline for the preliminary results of this... International Trade Administration Certain Circular Welded Non-Alloy Steel Pipe From the Republic of Korea... administrative review of the antidumping duty order on certain circular welded non- alloy steel pipe...

  20. 76 FR 14649 - Certain Circular Welded Non-Alloy Steel Pipe From Mexico: Extension of Time Limit for Final...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-17

    ... Antidumping Duty Administrative Review, 75 FR 78216 (December 15, 2010). The final results for this... International Trade Administration Certain Circular Welded Non-Alloy Steel Pipe From Mexico: Extension of Time... circular welded non-alloy steel pipe from Mexico for the November 1, 2008, through October 31, 2009,...

  1. 75 FR 44763 - Certain Circular Welded Non-Alloy Steel Pipe From Mexico; Extension of Time Limit for Preliminary...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-29

    ... and Request for Revocation in Part, 74 FR 68229 (December 23, 2009). The current deadline for the... International Trade Administration Certain Circular Welded Non-Alloy Steel Pipe From Mexico; Extension of Time... welded non- alloy steel pipe from Mexico. We also received review requests on November 30, 2009,...

  2. Effects of thermal aging on microstructures of low alloy steel-Ni base alloy dissimilar metal weld interfaces

    NASA Astrophysics Data System (ADS)

    Choi, Kyoung Joon; Kim, Jong Jin; Lee, Bong Ho; Bahn, Chi Bum; Kim, Ji Hyun

    2013-10-01

    In this study, the advanced instrumental analysis has been performed to investigate the effect of long-term thermal aging on the microstructural evolution in the fusion boundary region between weld metal and low alloy steel in dissimilar metal welds. A representative dissimilar weld mock-up made of Alloy 690-Alloy 152-A533 Gr. B was fabricated and aged at 450 °C for 2750 h. The micro- and nano-scale characterization were conducted mainly near in a weld root region by using optical microscopy, scanning electron microscopy, transmission electron microscopy, and three dimensional atom probe tomography. It was observed that the weld root was generally divided into several regions including dilution zone in the Ni-base alloy weld metal, fusion boundary, and heat-affected zone in the low alloy steel. A steep gradient was shown in the chemical composition profile across the interface between A533 Gr. B and Alloy 152. The precipitation of carbides was also observed along and near the fusion boundary of as-welded and aged dissimilar metal joints. It was also found that the precipitation of Cr carbides was enhanced by the thermal aging near the fusion boundary.

  3. Some microstructural characterisations in a friction stir welded oxide dispersion strengthened ferritic steel alloy

    NASA Astrophysics Data System (ADS)

    Legendre, F.; Poissonnet, S.; Bonnaillie, P.; Boulanger, L.; Forest, L.

    2009-04-01

    The goal of this study is to characterize microstructure of a friction stir welded oxide dispersion strengthened alloy. The welded material is constituted by two sheets of an yttria-dispersion-strengthened PM 2000 ferritic steel. Different areas of the friction stir welded product were analyzed using field emission gun secondary electron microscopy (FEG-SEM) and electron microprobe whereas nanoindentation was used to evaluate mechanical properties. The observed microstructural evolution, including distribution of the yttria dispersoids, after friction stir welding process is discussed and a correlation between the microstructure and the results of nanoindentation tests is established.

  4. Resistance Spot Welding of Aluminum Alloy to Steel with Transition Material - Part II: Finite Element Analyses of Nugget Growth

    SciTech Connect

    Sun, Xin; Khaleel, Mohammad A.

    2004-07-01

    This paper summarizes work on finite element modeling of nugget growth for resistance spot welding of aluminum alloy to steel. It is a sequel to a previous paper on experimental studies of resistance spot welding of aluminum to steel using a transition material. Since aluminum alloys and steel cannot be readily fusion welded together due to their drastically different thermal physical properties, a cold-rolled clad material was introduced as a transition to aid the resistance welding process. Coupled electrical-thermal-mechanical finite element analyses were performed to simulate the nugget growth and heat generation patterns during the welding process. The predicted nugget growth results were compared to the experimental weld cross sections. Reasonable comparisons of nugget size were achieved. The finite element simulation procedures were also used in the electrode selection state to help reduce weld expulsion and improve weld quality.

  5. Ultrasonic butt welding of aluminum, aluminum alloy and stainless steel plate specimens.

    PubMed

    Tsujino, Jiromaru; Hidai, Kazuaki; Hasegawa, Atsushi; Kanai, Ryoichi; Matsuura, Hisanori; Matsushima, Kaoru; Ueoka, Tetsugi

    2002-05-01

    Welding characteristics of aluminum, aluminum alloy and stainless steel plate specimens of 6.0 mm thickness by a 15 kHz ultrasonic butt welding system were studied. There are no detailed welding condition data of these specimens although the joining of these materials are required due to anticorrosive and high strength characteristics for not only large specimens but small electronic parts especially. These specimens of 6.0 mm thickness were welded end to end using a 15 kHz ultrasonic butt welding equipment with a vibration source using eight bolt-clamped Langevin type PZT transducers and a 50 kW static induction thyristor power amplifier. The stainless steel plate specimens electrolytically polished were joined with welding strength almost equal to the material strength under rather large vibration amplitude of 25 microm (peak-to-zero value), static pressure 70 MPa and welding time of 1.0-3.0 s. The hardness of stainless steel specimen adjacent to a welding surface increased about 20% by ultrasonic vibration. PMID:12159968

  6. Metallurgical and mechanical properties of laser welded high strength low alloy steel

    PubMed Central

    Oyyaravelu, Ramachandran; Kuppan, Palaniyandi; Arivazhagan, Natarajan

    2016-01-01

    The study aimed at investigating the microstructure and mechanical properties of Neodymium-Doped Yttrium Aluminum Garnet (Nd:YAG) laser welded high strength low alloy (HSLA) SA516 grade 70 boiler steel. The weld joint for a 4 mm thick plate was successfully produced using minimum laser power of 2 kW by employing a single pass without any weld preheat treatment. The micrographs revealed the presence of martensite phase in the weld fusion zone which could be due to faster cooling rate of the laser weldment. A good correlation was found between the microstructural features of the weld joints and their mechanical properties. The highest hardness was found to be in the fusion zone of cap region due to formation of martensite and also enrichment of carbon. The hardness results also showed a narrow soft zone at the heat affected zone (HAZ) adjacent to the weld interface, which has no effect on the weld tensile strength. The yield strength and ultimate tensile strength of the welded joints were 338 MPa and 549 MPa, respectively, which were higher than the candidate metal. These tensile results suggested that the laser welding process had improved the weld strength even without any weld preheat treatment and also the fractography of the tensile fractured samples showed the ductile mode of failure. PMID:27222751

  7. Metallurgical and mechanical properties of laser welded high strength low alloy steel.

    PubMed

    Oyyaravelu, Ramachandran; Kuppan, Palaniyandi; Arivazhagan, Natarajan

    2016-05-01

    The study aimed at investigating the microstructure and mechanical properties of Neodymium-Doped Yttrium Aluminum Garnet (Nd:YAG) laser welded high strength low alloy (HSLA) SA516 grade 70 boiler steel. The weld joint for a 4 mm thick plate was successfully produced using minimum laser power of 2 kW by employing a single pass without any weld preheat treatment. The micrographs revealed the presence of martensite phase in the weld fusion zone which could be due to faster cooling rate of the laser weldment. A good correlation was found between the microstructural features of the weld joints and their mechanical properties. The highest hardness was found to be in the fusion zone of cap region due to formation of martensite and also enrichment of carbon. The hardness results also showed a narrow soft zone at the heat affected zone (HAZ) adjacent to the weld interface, which has no effect on the weld tensile strength. The yield strength and ultimate tensile strength of the welded joints were 338 MPa and 549 MPa, respectively, which were higher than the candidate metal. These tensile results suggested that the laser welding process had improved the weld strength even without any weld preheat treatment and also the fractography of the tensile fractured samples showed the ductile mode of failure. PMID:27222751

  8. Microstructural characterization of dissimilar welds between alloy 800 and HP heat-resistant steel

    SciTech Connect

    Dehmolaei, R.; Shamanian, M. Kermanpur, A.

    2008-10-15

    In this study, dissimilar welds between HP heat-resistant steel and Incoloy 800 were made with four different filler materials including: 309 stainless steel and nickel-based Inconel 82, 182 and 617. The microstructure of the base metals, weld metals and their interfaces were characterized by utilizing optical and scanning electron microscopy. Grain boundaries migration in the weld metals was studied. It was found that the migration of grain boundaries in the Inconel 82 weld metal was very extensive. Precipitates of TiC and M{sub 23}C{sub 6} (M = Cr and Mo) in the Inconel 617 weld metal are identified. The necessary conditions for the formation of cracks close to the fusion line of the 309-HP joints are described. Furthermore unmixed zone near the fusion line between HP steel base metal and Inconel 82 weld metal is discussed. An epitaxial growth is characterized at the fusion line of the 309-Alloy 800 and Inconel 617-Alloy 800 joints.

  9. Diffusion-controlled wear of steel friction stir welding tools used on aluminum alloys

    NASA Astrophysics Data System (ADS)

    Tarasov, S. Yu.; Kalashnikova, T. A.; Kalashnikov, K. N.; Rubtsov, V. E.; Eliseev, A. A.; Kolubaev, E. A.

    2015-10-01

    The worn surfaces of steel instruments used for friction stir welding on AMg5M aluminum alloy have been examined. An adhesion transfer layer resulted on the steel tool surface from welding the aluminum-magnesium alloy. Diffusion between this layer and steel base metal resulted in formation of an intermetallic Fe-Al layer (IMC). The hardness of the IMC has been measured using a nanohardness tester. It was found that the IMC layers maximum hardness changed from 998 to 1698 HV. The continuous IMC layers may serve as a wear-resistant coating, however, the IMC were also found in the shape of spikes directed into the tool's body, which created conditions for wear particle formation by fracture.

  10. 75 FR 20342 - Certain Circular Welded Non-Alloy Steel Pipe From Mexico: Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-19

    ... Non-Alloy Steel Pipe and Tube from Mexico, 74 FR 41681 (August 18, 2009). DATES: Effective Date: April... Determination of Sales at Less Than Fair Value: Circular Welded Non- Alloy Steel Pipe From Mexico, 57 FR 42953..., 74 FR 64049 (December 7, 2009) (Preliminary Results). While the review originally covered...

  11. 75 FR 39917 - Circular Welded Non-Alloy Steel Pipe from the Republic of Korea: Extension of Time Limit for...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-13

    ... for Revocation in Part, 74 FR 68229 (December 23, 2009). The current deadline for the preliminary... International Trade Administration (A-580-809) Circular Welded Non-Alloy Steel Pipe from the Republic of Korea... non-alloy steel pipe from the Republic of Korea, covering the period November 1, 2008 through...

  12. Study of austenitic stainless steel welded with low alloy steel filler metal. [tensile and impact strength tests

    NASA Technical Reports Server (NTRS)

    Burns, F. A.; Dyke, R. A., Jr.

    1979-01-01

    The tensile and impact strength properties of 316L stainless steel plate welded with low alloy steel filler metal were determined. Tests were conducted at room temperature and -100 F on standard test specimens machined from as-welded panels of various chemical compositions. No significant differences were found as the result of variations in percentage chemical composition on the impact and tensile test results. The weldments containing lower chromium and nickel as the result of dilution of parent metal from the use of the low alloy steel filler metal corroded more severely in a marine environment. The use of a protective finish, i.e., a nitrile-based paint containing aluminum powder, prevented the corrosive attack.

  13. Friction Stir Welding of Stainless Steel to Al Alloy: Effect of Thermal Condition on Weld Nugget Microstructure

    NASA Astrophysics Data System (ADS)

    Ghosh, M.; Gupta, R. K.; Husain, M. M.

    2014-02-01

    Joining of dissimilar materials is always a global challenge. Sometimes it is unavoidable to execute multifarious activities by a single component. In the present investigation, 6061 aluminum alloy and 304 stainless steel were joined by friction stir welding (FSW) at different tool rotational rates. Welded joints were characterized in optical and scanning electron microscopes. Reaction products in the stirring zone (SZ) were confirmed through X-ray diffraction. Joint strength was evaluated by tensile testing. It was found that the increment in average heat input and temperature at the weld nugget (WN) facilitated iron enrichment near the interface. Enhancement in the concentration of iron shifted the nature of intermetallics from the Fe2Al5 to Fe-rich end of the Fe-Al binary phase diagram. The peak microhardness and ultimate tensile strength were found to be maxima at the intermediate tool rotational rate, where Fe3Al and FeAl2 appeared along with Fe2Al5.

  14. Gravitational effects on weld pool shape and microstructural evolution during gas tungsten arc and laser beam welding on 304 stainless steel, nickel, and aluminum-4 wt.% copper alloy

    NASA Astrophysics Data System (ADS)

    Kang, Namhyun

    The objective of the present work was to investigate effects of gravitational (acceleration) level and orientation on Ni 200 alloy (99.5% Ni purity), 304 stainless steel, and Al-4 wt.% Cu alloy during gas tungsten arc welding (GTAW) and laser beam welding (LBW). Main characterization was focused on the weld pool shape, microstructure, and solute distribution as a function of gravitational level and orientation. The welds were divided into two classes, i.e., 'stable' and 'unstable' welds, in view of the variation of weld pool shape as a function of gravitational level and orientation. In general, higher arc current and translational GTAW produced more significant effects of gravitational orientation on the weld pool shape than the case of lower arc current and spot welding. Cross-sectional area (CSA) was a secondary factor in determining the stability of weld pool shape. For the 'stable' weld of 304 stainless steel GTAW, the II-U weld showed less convexity in the pool bottom and more depression of the free surface, therefore producing deeper penetration (10--20%) than the case of II-D weld. The II-D weld of 304 stainless steel showed 31% deeper penetration, 28% narrower width, and more hemispherical shape of the weld pool than the case of II-U weld. For GTAW on 304 stainless steel, gravitational level variation from low gravity (LG ≈ 1.2 go) to high gravity (HG ≈ 1.8 go) caused 10% increase in width and 10% decrease in depth while maintaining the overall weld pool volume. Furthermore, LBW on 304 stainless steels showed mostly constant shape of weld pool as a function of gravitational orientation. GTAW on Ni showed similar trends of weld pool shape compared with GTAW on 304 stainless steel, i.e., the weld pool became unstable by showing more penetration in the II-D weld for slower arc translational velocity (V a) and larger weld pool size. However, the Ni weld pool shape had greater stability of the weld pool shape with respect to the gravitational orientation

  15. 76 FR 49437 - Certain Circular Welded Non-Alloy Steel Pipe From Mexico: Preliminary Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-10

    ... Circumstances Review: Certain Circular Welded Non-Alloy Steel Pipe From Mexico, 75 FR 82374 (December 30, 2010... Steel Pipe from Korea, 57 FR 49453 (November 2, 1992) (Antidumping Duty Order). On November 1, 2010, the... Administrative Review, 75 FR 67079 (November 1, 2010). On November 30, 2010, the Department received...

  16. Evaluation of pitting corrosion resistance of high-alloyed stainless steels welds for FGD plants in Korea

    SciTech Connect

    Baek, K.K.; Sung, H.J.; Im, C.S.; Hong, I.P.; Kim, D.K.

    1998-12-31

    For successful application of high-alloyed stainless steels for Flue Gas Desulfurization (FGD) plants, pitting corrosion resistance of arc welds of N-added 6%Mo austenitic stainless steels (UNS N 08367) and super duplex stainless steels (UNS S 32550) made with various filler metals were evaluated using the Green Death solution. For Gas Tungsten Arc (GTA) and Gas Metal Arc (GMA) welds of N 08367, Critical Pitting Temperature (CPT) of base metal was 65--70 C, whereas weld made by ERNiCrMo-3 filler metal yielded CPT of 50 C. Welds made by ERNiCrMo-10 or ERNiCrMo-4 filler metals showed CPT of 60--65 C and 65--70C, respectively. For GTA and GMA welds of S 32550, CPT of welds made by ERNiCrMo-3 was 45--50 C, indicating that the filler metal can provide pitting corrosion resistance matching the S 32550 alloy. Thus, a proper pitting corrosion resistance of weldments of high-alloy stainless steels can be achieved by selecting filler metals having at least +10 higher Pitting Resistance Equivalent Number (PRE{sub N}) value than the base metal regardless of the type of arc welding process. The over-alloyed filler metals would compensate preferential segregation of Cr, MO along the dendrite boundary, which made the dendrite core more susceptible to pitting. Nitrogen addition to the GTA welds of N 08367 made with ERNiCrMo-3 failed to improve pitting corrosion resistance, which was attributed to the precipitation of nitrogen in the weld metal in the form of Nb-nitride.

  17. YAG laser micro welding of stainless steel and shape memory alloy

    NASA Astrophysics Data System (ADS)

    Uenishi, Keisuke; Seki, Masanori; Kunimasa, Takeshi; Takatsugu, Masaya; Kobayashi, Kojiro F.; Ikeda, Takeshi; Tsuboi, Akihiro

    2003-02-01

    In order to investigate the applicability of laser micro welding to the fabrication of medical devices, SUS304 stainless steel and Ti-Ni based shape memory alloy biomaterials wires were micro spot melted by using YAG laser. By the optimization of laser conditions such as laser power or pulse duration, sound spot melted wires free from any defects were prepared and the width of the melted metal was reduced to about 0.3mm for the 0.35mm diameter wires. Compared with the SUS304 wires, melting of shape memory alloy wires needed more precise control of laser conditions although it needed smaller power input. Melted metal exhibited a rapidly quenched microstructure. The spot melted wires showed comparable tensile strength or super-elastic behavior with base materials. Besides, by the microstructural observation and corrosion test in a quasi biological environment, corrosion resistance was estimated to be hardly degraded by spot melting. Crosswise or parallel joints was also successfully prepared by laser spot welding of wires, suggesting the laser micro welding is applicable to the fabrication of biomedical devices.

  18. 76 FR 77770 - Certain Circular Welded Non-Alloy Steel Pipe From Mexico: Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-14

    ... Circumstances Review: Certain Circular Welded Non-Alloy Steel Pipe From Mexico, 75 FR 82374 (December 30, 2010... Administrative Review, 76 FR 49437 (August 10, 2011) (Preliminary Results). \\2\\ The Department determined that...; Countervailing Duties, 62 FR 27296, 27393 (May 19, 1997); see also Oil Country Tubular Goods From...

  19. 75 FR 77838 - Circular Welded Non-Alloy Steel Pipe From the Republic of Korea: Preliminary Results of the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-14

    ...: Final Results of Antidumping Duty Administrative Review, 75 FR 6627 (February 10, 2010) (``SSSS from...: Certain Circular Welded Non-Alloy Steel Pipe from Korea, 57 FR 49453 (November 2, 1992) (``CWP Order... Antidumping and Countervailing Duty Administrative Reviews and Request for Revocation in Part, 74 FR...

  20. 76 FR 36089 - Circular Welded Non-Alloy Steel Pipe From the Republic of Korea: Final Results of the Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-21

    ...On December 14, 2010, the Department of Commerce (the ``Department'') published the preliminary results of the administrative review of the antidumping duty order on circular welded non-alloy steel pipe (``CWP'') from the Republic of Korea (``Korea''), covering the period November 1, 2008, through October 31, 2009. This review covers six producers/exporters of the subject merchandise to the......

  1. 75 FR 34980 - Circular Welded Non-Alloy Steel Pipe from the Republic of Korea: Final Results of the Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-21

    ... Korea: Preliminary Results and Rescission in Part of the Antidumping Duty Administrative Review, 74 FR... Review, 75 FR 13729 (March 23, 2010). We invited parties to comment on the Preliminary Results. We... Welded Non-Alloy Steel Pipe and Tube From Brazil, the Republic of Korea, Mexico, and Venezuela, 61...

  2. 76 FR 15941 - Circular Welded Non-Alloy Steel Pipe From the Republic of Korea: Extension of the Final Results...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-22

    ... From the Republic of Korea: Preliminary Results of the Antidumping Duty Administrative Review, 75 FR... the Tariff Act of 1930, As Amended, 70 FR 24533 (May 10, 2005). Accordingly, the deadline for... International Trade Administration Circular Welded Non-Alloy Steel Pipe From the Republic of Korea: Extension...

  3. 76 FR 52636 - Circular Welded Non-Alloy Steel Pipe From the Republic of Korea: Partial Rescission of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-23

    ... Administrative Review, 75 FR 67079 (November 1, 2010). In accordance with 19 CFR 351.213(b), on November 30, 2010... Revocation in Part, 75 FR 81565 (December 28, 2010). Wheatland withdrew its request for a review of Husteel... International Trade Administration Circular Welded Non-Alloy Steel Pipe From the Republic of Korea:...

  4. 78 FR 34342 - Certain Circular Welded Non-Alloy Steel Pipe From Mexico: Final Results and Partial Rescission of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-07

    ... Rescission of Antidumping Duty Administrative Review; 2010-11, 77 FR 73617 (December 11, 2012) (Preliminary... Countervailing Duty Administrative Reviews and Request for Revocation in Part, 76 FR 82268 (December 30, 2011... Fair Value: Certain Welded Non-Alloy Steel Pipe from Korea, 57 FR 49453 (November 2, 1992)...

  5. 78 FR 79664 - Certain Circular Welded Non-Alloy Steel Pipe From Mexico: Final Results of the 2011-2012...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-31

    ..., 78 FR 48647 (August 9, 2013) (Preliminary Results). DATES: Effective Date: December 31, 2013. FOR... Less Than Fair Value: Certain Welded Non-Alloy Steel Pipe from Korea, 57 FR 49453 (November 2, 1992...: Assessment of Antidumping Duties, 68 FR 23954 (May 6, 2003) (reseller policy). For all entries by...

  6. 77 FR 73015 - Circular Welded Non-Alloy Steel Pipe From the Republic of Korea: Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-07

    ... Administrative Review, 63 FR 32833 (June 16, 1998), remains dispositive. Partial Rescission of Administrative...: Assessment of Antidumping Duties, 68 FR 23954 (May 6, 2003). For Husteel and HYSCO, we intend to issue...: Certain Circular Welded Non-Alloy Steel Pipe from Korea, 57 FR 49453 (November 2, 1992). Notification...

  7. 77 FR 73617 - Certain Circular Welded Non-Alloy Steel Pipe From Mexico: Preliminary Results and Partial...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-11

    ... Less Than Fair Value: Certain Welded Non-Alloy Steel Pipe from Korea, 57 FR 49453 (November 2, 1992... Countervailing Duty Administrative Reviews and Request for Revocation in Part, 76 FR 82268 (December 30, 2011...\\ See Antidumping Duties; Countervailing Duties, 62 FR 27296, 27393 (May 19, 1997); see also Oil...

  8. 76 FR 76369 - Circular Welded Non-Alloy Steel Pipe From the Republic of Korea: Preliminary Results of the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-07

    ... Less Than Fair Value: Certain Circular Welded Non-Alloy Steel Pipe from Korea, 57 FR 49453 (November 2... Duty Administrative Reviews and Request for Revocation in Part, 75 FR 81565 (December 28, 2010..., 75 FR at 81565. On January 10, 2011, we received comments on the issue of respondent selection...

  9. 75 FR 78216 - Certain Circular Welded Non-Alloy Steel Pipe From Mexico: Preliminary Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-15

    ... Mexico, 75 FR 67685 (November 3, 2010). Therefore, we are continuing to refer to this entity as TUNA for... Welded Non-Alloy Steel Pipe from Korea, 57 FR 49453 (November 2, 1992) (Antidumping Duty Order). On... Investigation; Opportunity to Request Administrative Review, 74 FR 56573 (November 2, 2009). On November...

  10. Study of mechanical joint strength of aluminum alloy 7075-T6 and dual phase steel 980 welded by friction bit joining and weld-bonding under corrosion medium

    SciTech Connect

    Lim, Yong Chae; Squires, Lile; Pan, Tsung-Yu; Miles, Michael; Song, Guang-Ling; Wang, Yanli; Feng, Zhili

    2014-12-30

    We have employed a unique solid-sate joining process, called friction bit joining (FBJ), to spot weld aluminum alloy (AA) 7075-T6 and dual phase (DP) 980 steel. Static joint strength was studied in the lap shear tension configuration. In addition, weld-bonding (adhesive + FBJ) joints were studied in order to evaluate the ability of adhesive to mitigate the impact of corrosion on joint properties. Accelerated laboratory cyclic corrosion tests were carried out for both FBJ only and weld-bonding joints. Furthermore, the FBJ only joints that emerged from corrosion testing had lap shear failure loads that were significantly lower than freshly prepared joints. However, weld-bonding specimens retained more than 80% of the lap shear failure load of the freshly prepared weld-bonding specimens. Moreover, examination of joint cross sections confirmed that the presence of adhesive in the weld-bonding joints mitigated the effect of the corrosion environment, compared to FBJ only joints.

  11. Laser-Arc Hybrid Welding of Dissimilar Titanium Alloy and Stainless Steel Using Copper Wire

    NASA Astrophysics Data System (ADS)

    Gao, Ming; Chen, Cong; Wang, Lei; Wang, Zemin; Zeng, Xiaoyan

    2015-05-01

    Laser-arc hybrid welding with Cu3Si filler wire was employed to join dissimilar Ti6Al4V titanium alloy and AISI316 stainless steel (316SS). The effects of welding parameters on bead shape, microstructure, mechanical properties, and fracture behavior were investigated in detail. The results show that cross-weld tensile strength of the joints is up to 212 MPa. In the joint, obvious nonuniformity of the microstructure is found in the fusion zone (FZ) and at the interfaces from the top to the bottom, which could be improved by increasing heat input. For the homogeneous joint, the FZ is characterized by Fe67- x Si x Ti33 dendrites spreading on α-Cu matrix, and the two interfaces of 316SS/FZ and FZ/Ti6Al4V are characterized by a bamboo-like 316SS layer and a CuTi2 layer, respectively. All the tensile samples fractured in the hardest CuTi2 layer at Ti6Al4V side of the joints. The fracture surface is characterized by river pattern revealing brittle cleavage fracture. The bead formation mechanisms were discussed according to the melt flow and the thermodynamic calculation.

  12. Effect of transcrystalline fusing during flash heat of alloyed steels and its application prospects in welding production

    SciTech Connect

    Kalinushkin, E.P.; Taran, J.N.; Cerednichenko, G.M.; Gutchenko, A.P.

    1996-12-31

    The fusing and crystallization of many industrial alloy (peritectic-type steels) steels are usually treated as complex process presupposing the successive implementation of the following transformations: L {Leftrightarrow} {delta}, crystallization (fusing) of {delta}-ferrite; (L + {delta} {Leftrightarrow} {gamma}), the peritectic reaction of forming austenite ({delta}-ferrite); L {Leftrightarrow} ({gamma} + k), the eutectic reaction. However, though the general form of this scheme does not evoke any doubts, the mechanism of some crystallization (fusing) processes on actual kinetic conditions of steel cooling (heating) was studied insufficiently. To the greatest extent this relates to welding processes, because structure formation in the weld at the final stages of solidification inherits all the features of the preceding phase transformations. Moreover, high heating and cooling rates during welding provide special effects. Some of them which may have practical application are reported in this paper.

  13. Nickel-based alloy/austenitic stainless steel dissimilar weld properties prediction on asymmetric distribution of laser energy

    NASA Astrophysics Data System (ADS)

    Zhou, Siyu; Ma, Guangyi; Chai, Dongsheng; Niu, Fangyong; Dong, Jinfei; Wu, Dongjiang; Zou, Helin

    2016-07-01

    A properties prediction method of Nickel-based alloy (C-276)/austenitic stainless steel (304) dissimilar weld was proposed and validated based on the asymmetric distribution of laser energy. Via the dilution level DC-276 (the ratio of the melted C-276 alloy), the relations between the weld properties and the energy offset ratio EC-276 (the ratio of the irradiated energy on the C-276 alloy) were built, and the effects of EC-276 on the microstructure, mechanical properties and corrosion resistance of dissimilar welds were analyzed. The element distribution Cweld and EC-276 accorded with the lever rule due to the strong convention of the molten pool. Based on the lever rule, it could be predicted that the microstructure mostly consists of γ phase in each weld, the δ-ferrite phase formation was inhibited and the intermetallic phase (P, μ) formation was promoted with the increase of EC-276. The ultimate tensile strength σb of the weld joint could be predicted by the monotonically increasing cubic polynomial model stemming from the strengthening of elements Mo and W. The corrosion potential U, corrosion current density I in the active region and EC-276 also met the cubic polynomial equations, and the corrosion resistance of the dissimilar weld was enhanced with the increasing EC-276, mainly because the element Mo could help form a steady passive film which will resist the Cl- ingress.

  14. Laser Welding Characterization of Kovar and Stainless Steel Alloys as Suitable Materials for Components of Photonic Devices Packaging

    SciTech Connect

    Fadhali, M. M. A.; Zainal, Saktioto J.; Munajat, Y.; Jalil, A.; Rahman, R.

    2010-03-11

    The weldability of Kovar and stainless steel alloys by Nd:YAG laser beam is studied through changing of some laser beam parameters. It has been found that there is a suitable interaction of the pulsed laser beam of low power laser pulse with both the two alloys. The change of thermophysical properties with absorbed energy from the laser pulse is discussed in this paper which reports the suitability of both Kovar and stainless steel 304 as the base materials for photonic devices packaging. We used laser weld system (LW4000S from Newport) which employs Nd:YAG laser system with two simultaneous beams output for packaging 980 nm high power laser module. Results of changing both laser spot weld width and penetration depth with changing both the pulse peak power density, pulse energy and pulse duration show that there are good linear relationships between laser pulse energy or peak power density and pulse duration with laser spot weld dimensions( both laser spot weld width and penetration depth). Therefore we concluded that there should be an optimization for both the pulse peak power and pulse duration to give a suitable aspect ratio (laser spot width to penetration depth) for achieving the desired welds with suitable penetration depth and small spot width. This is to reduce the heat affected zone (HAZ) which affects the sensitive optical components. An optimum value of the power density in the order of 10{sup 5} w/cm{sup 2} found to be suitable to induce melting in the welded joints without vaporization. The desired ratio can also be optimized by changing the focus position on the target material as illustrated from our measurements. A theoretical model is developed to simulate the temperature distribution during the laser pulse heating and predict the penetration depth inside the material. Samples have been investigated using SEM with EDS. The metallographic measurements on the weld spot show a suitable weld yield with reasonable weld width to depth ratio.

  15. Welding of high chromium steels

    NASA Technical Reports Server (NTRS)

    Miller, W B

    1928-01-01

    A brief description is given of different groups of high chromium steels (rustless iron and stainless steels) according to their composition and more generally accepted names. The welding procedure for a given group will be much the same regardless of the slight variations in chemical composition which may exist within a certain group. Information is given for the tensile properties (yield point and ultimate strength) of metal sheets and welds before and after annealing on coupons one and one-half inches wide. Since welds in rustless iron containing 16 to 18 percent chromium and 7 to 12 percent nickel show the best combination of strength and ductility in the 'as welded' or annealed condition, it is considered the best alloy to use for welded construction.

  16. 46 CFR 59.20-1 - Carbon-steel or alloy-steel castings.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Carbon-steel or alloy-steel castings. 59.20-1 Section 59... BOILERS, PRESSURE VESSELS AND APPURTENANCES Welding Repairs to Castings § 59.20-1 Carbon-steel or alloy-steel castings. Defects in carbon-steel or alloy-steel castings may be repaired by welding. The...

  17. 46 CFR 59.20-1 - Carbon-steel or alloy-steel castings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Carbon-steel or alloy-steel castings. 59.20-1 Section 59... BOILERS, PRESSURE VESSELS AND APPURTENANCES Welding Repairs to Castings § 59.20-1 Carbon-steel or alloy-steel castings. Defects in carbon-steel or alloy-steel castings may be repaired by welding. The...

  18. 46 CFR 59.20-1 - Carbon-steel or alloy-steel castings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Carbon-steel or alloy-steel castings. 59.20-1 Section 59... BOILERS, PRESSURE VESSELS AND APPURTENANCES Welding Repairs to Castings § 59.20-1 Carbon-steel or alloy-steel castings. Defects in carbon-steel or alloy-steel castings may be repaired by welding. The...

  19. 46 CFR 59.20-1 - Carbon-steel or alloy-steel castings.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Carbon-steel or alloy-steel castings. 59.20-1 Section 59... BOILERS, PRESSURE VESSELS AND APPURTENANCES Welding Repairs to Castings § 59.20-1 Carbon-steel or alloy-steel castings. Defects in carbon-steel or alloy-steel castings may be repaired by welding. The...

  20. 46 CFR 59.20-1 - Carbon-steel or alloy-steel castings.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Carbon-steel or alloy-steel castings. 59.20-1 Section 59... BOILERS, PRESSURE VESSELS AND APPURTENANCES Welding Repairs to Castings § 59.20-1 Carbon-steel or alloy-steel castings. Defects in carbon-steel or alloy-steel castings may be repaired by welding. The...

  1. Study of mechanical joint strength of aluminum alloy 7075-T6 and dual phase steel 980 welded by friction bit joining and weld-bonding under corrosion medium

    DOE PAGESBeta

    Lim, Yong Chae; Squires, Lile; Pan, Tsung-Yu; Miles, Michael; Song, Guang-Ling; Wang, Yanli; Feng, Zhili

    2014-12-30

    We have employed a unique solid-sate joining process, called friction bit joining (FBJ), to spot weld aluminum alloy (AA) 7075-T6 and dual phase (DP) 980 steel. Static joint strength was studied in the lap shear tension configuration. In addition, weld-bonding (adhesive + FBJ) joints were studied in order to evaluate the ability of adhesive to mitigate the impact of corrosion on joint properties. Accelerated laboratory cyclic corrosion tests were carried out for both FBJ only and weld-bonding joints. Furthermore, the FBJ only joints that emerged from corrosion testing had lap shear failure loads that were significantly lower than freshly preparedmore » joints. However, weld-bonding specimens retained more than 80% of the lap shear failure load of the freshly prepared weld-bonding specimens. Moreover, examination of joint cross sections confirmed that the presence of adhesive in the weld-bonding joints mitigated the effect of the corrosion environment, compared to FBJ only joints.« less

  2. Welding Rustproof Steels

    NASA Technical Reports Server (NTRS)

    Hoffmann, W

    1929-01-01

    The following experimental results will perhaps increase the knowledge of the process of welding rustproof steels. The experiments were made with two chrome-steel sheets and with two chrome-steel-nickel sheets having the composition shown in Table I.

  3. Influence of high-temperature exposure on the microstructure and mechanical properties of dissimilar metal welds between modified 9Cr-1Mo steel and alloy 800

    NASA Astrophysics Data System (ADS)

    Sireesha, M.; Albert, Shaju K.; Sundaresan, S.

    2005-06-01

    Transition joints between ferritic steel and austenitic stainless steel are commonly encountered in high-temperature components of power plants. Service failures in these are known to occur as a result, mainly, of thermal stresses due to expansion coefficient differentials. In order to mitigate the problem, a trimetallic configuration involving an intermediate piece of a material such as Alloy 800 between the ferritic and austenitic steels has been suggested. In our work, modified 9Cr-1Mo steel and 316LN stainless steel are used as the ferritic and austenitic components and the thermal behavior of the joints between modified 9Cr-1Mo steel and Alloy 800 is described in this article. The joints, made using the nickel-base filler material INCONEL 82/182 (INCONEL 82 for the root pass by gas-tungsten arc welding and INCONEL 182 for the filler passes by shielded-metal arc welding), were aged at 625 °C for periods up to 5000 hours. The microstructural changes occurring in the weld metal as well as at the interfaces with the two parent materials are characterized in detail. Results of across-the-weld hardness surveys and cross-weld tension tests and weld metal Charpy impact tests are correlated with the structural changes observed. Principally, the results show that (1) the tendency for carbon to diffuse from the ferritic steel into the weld metal is much less pronounced than when 2.25Cr-1Mo steel is used as the ferritic part; and (2) intermetallic precipitation occurs in the weld metal for aging durations longer than 2000 hours, but the weld metal toughness still remains adequate in terms of the relevant specification.

  4. Wear behavior of the surface alloyed AISI 1020 steel with Fe-Nb-B by TIG welding technique

    NASA Astrophysics Data System (ADS)

    Kilinc, B.; Durmaz, M.; Abakay, E.; Sen, U.; Sen, S.

    2015-03-01

    Weld overlay coatings also known as hardfacing is a method which involves melting of the alloys and solidification for applied coatings. Recently hardfacing by welding has become a commonly used technique for improvement of material performance in extreme (high temperature, impact/abrasion, erosion, etc.) conditions.In the present study, the coatings were produced from a mixture of ferrous niobium, ferrous boron and iron powders in the ranges of -45µm particle size with different ratio. Fe12Nb5B3 and Fe2NbBalloys were coated on the AISI 1020 steel surface by TIG welding. The phases formed in the coated layer are Fe2B, NbB2, NbFeB and Fe0,2 Nb0,8 phases. The hardness of the presence phases are changing between 1689±85 HV0.01, and 181±7 HV0.1. Microstructural examinations were realized by optical and scanning electron microscopy. The wear and friction behaviors of Fe12Nb5B3 and Fe2NbB realized on the AISI 1020 steel were investigated by the technique of TIG welding by using ball-on-disk arrangement against alumina ball.

  5. Wear behavior of the surface alloyed AISI 1020 steel with Fe-Nb-B by TIG welding technique

    SciTech Connect

    Kilinc, B. Durmaz, M.; Abakay, E.; Sen, U.; Sen, S.

    2015-03-30

    Weld overlay coatings also known as hardfacing is a method which involves melting of the alloys and solidification for applied coatings. Recently hardfacing by welding has become a commonly used technique for improvement of material performance in extreme (high temperature, impact/abrasion, erosion, etc.) conditions.In the present study, the coatings were produced from a mixture of ferrous niobium, ferrous boron and iron powders in the ranges of -45µm particle size with different ratio. Fe{sub 12}Nb{sub 5}B{sub 3} and Fe{sub 2}NbBalloys were coated on the AISI 1020 steel surface by TIG welding. The phases formed in the coated layer are Fe{sub 2}B, NbB{sub 2}, NbFeB and Fe0,2 Nb{sub 0,8} phases. The hardness of the presence phases are changing between 1689±85 HV{sub 0.01}, and 181±7 HV{sub 0.1}. Microstructural examinations were realized by optical and scanning electron microscopy. The wear and friction behaviors of Fe{sub 12}Nb{sub 5}B{sub 3} and Fe2NbB realized on the AISI 1020 steel were investigated by the technique of TIG welding by using ball-on-disk arrangement against alumina ball.

  6. Ultrasonic Spot Welding of Aluminum to High-Strength Low-Alloy Steel: Microstructure, Tensile and Fatigue Properties

    NASA Astrophysics Data System (ADS)

    Patel, V. K.; Bhole, S. D.; Chen, D. L.

    2014-04-01

    The structural applications of lightweight aluminum alloys inevitably involve dissimilar welding with steels and the related durability issues. This study was aimed at evaluating the microstructural change, lap shear tensile load, and fatigue resistance of dissimilar ultrasonic spot-welded joints of aluminum-to-galvanized high-strength low-alloy (HSLA) steel. Two non-uniform layers were identified in between Al and HSLA steel via SEM/EDS and XRD. One was an Al-Zn eutectic layer and the other was a thin (<2 μm) layer of intermetallic compound (IMC) of Al and Fe in the nugget zone. The lap shear tensile testing gave a maximum load of 3.7 kN and the sample failed initially in between the Al-Zn eutectic film and Al-Fe IMC, and afterward from the region containing Al on both matching fracture surfaces. The fatigue test results showed a fatigue limit of about 0.5 kN (at 1 × 107 cycles). The maximum cyclic stress at which transition of the fatigue fracture from transverse through-thickness crack growth mode to the interfacial failure mode occurs increases with increasing energy input.

  7. Changes in the Structure and Properties of Welded Joints of Low-Alloy Steels, Subjected to Cyclic Loads

    NASA Astrophysics Data System (ADS)

    Kuskov, V. N.; Kovenskiy, I. M.; Kuskov, K. V.

    2016-04-01

    Time-varying loads negatively affect the properties and structure of materials. Structural failures typically occur at loads below the yield point. In this work, fatigue tests of welded joints of low-alloy steels were carried out in an asymmetric cycle at loads of 60 and 80% of the yield strength. The stress ratio was 0.8-0.9. On the basis of the results of the tests, equations linking the number of cycles to failure with test parameters were obtained. Such equations can be used for estimating the residual life of elements both under construction and in operation. It has been found that the failure is not instantaneous. Specimens of steels continue to resist variable loads for 4000 - 26000 cycles to failure, depending on steel grade and the parameters of the test. Under operating conditions, it gives an opportunity to discover the onset of failure and dispose of the defective part or to replace the entire structure. A standard technique was used to measure the microhardness on the fractured specimens. The distance between the nearest indentations was 0.2 mm. The results of the measurements were plotted in graphs of ahardness change characteristic for all steels under study. A microhardness “step” has been discovered in areas with high dislocation density, as evidenced by x-ray diffraction and transmission electron microscopy. An intermediate stage of the investigation is the development of recommendations for determining the moment of failure of welded constructions with a probability of 95%.

  8. Nondestructive Evaluation of Friction Stir-Welded Aluminum Alloy to Coated Steel Sheet Lap Joint

    NASA Astrophysics Data System (ADS)

    Das, H.; Kumar, A.; Rajkumar, K. V.; Saravanan, T.; Jayakumar, T.; Pal, Tapan Kumar

    2015-11-01

    Dissimilar lap joints of aluminum sheet (AA 6061) of 2 mm thickness and zinc-coated steel sheet of 1 mm thickness were produced by friction stir welding with different combinations of rotational speed and travel speed. Ultrasonic C- and B-scanning, and radiography have been used in a complementary manner for detection of volumetric (cavity and flash) and planar (de bond) defects as the defects are in micron level. Advanced ultrasonic C-scanning did not provide any idea about the defects, whereas B-scanning cross-sectional image showed an exclusive overview of the micron-level defects. A digital x-ray radiography methodology is proposed for quality assessment of the dissimilar welds which provide three-fold increase in signal-to-noise ratio with improved defect detection sensitivity. The present study clearly shows that the weld tool rotational speed and travel speed have a decisive role on the quality of the joints obtained by the friction stir welding process. The suitability of the proposed NDE techniques to evaluate the joint integrity of dissimilar FSW joints is thus established.

  9. 75 FR 13729 - Circular Welded Non-Alloy Steel Pipe from the Republic of Korea: Extension of Time Limit for the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-23

    ... Results and Rescission in Part of the Antidumping Duty Administrative Review, 74 FR 64670 (December 8... of 1930, As Amended, 70 FR 24533 (May 10, 2005). Accordingly, the deadline for completion of the... International Trade Administration Circular Welded Non-Alloy Steel Pipe from the Republic of Korea: Extension...

  10. Dissimilar Laser Welding/Brazing of 5754 Aluminum Alloy to DP 980 Steel: Mechanical Properties and Interfacial Microstructure

    NASA Astrophysics Data System (ADS)

    Yang, Jin; Li, Yulong; Zhang, Hua; Guo, Wei; Weckman, David; Zhou, Norman

    2015-11-01

    A diode laser welding/brazing technique was used for lap joining of 5754 aluminum alloy to DP 980 steel with Al-Si filler metal. The correlation between joint interfacial microstructure, wettability of filler metal, and mechanical properties was systematically investigated. At low laser power (1.4 kW), a layer of intermetallic compounds, composed of θ-Fe(Al,Si)3 and τ 5 -Al7.2Fe1.8Si, was observed at the interface between fusion zone and steel. Because of the poor wettability of filler metal on the steel substrate, the joint strength was very low and the joint failed at the FZ/steel interface. When medium laser power (2.0 kW) was applied, the wettability of filler metal was enhanced, which improved the joint strength and led to FZ failure. With further increase of laser power to 2.6 kW, apart from θ and τ 5, a new hard and brittle η-Fe2(Al,Si)5 IMC with microcracks was generated at the FZ/steel interface. The formation of η significantly degraded the joint strength. The failure mode changed back to interfacial failure.

  11. Effects of zinc additions on the stress corrosion crack growth rate of sensitized stainless steel, Alloy 600 and Alloy 182 weld metal in 288 C water

    SciTech Connect

    Andresen, P.L.; Angeliu, T.M.

    1995-09-01

    ZnO additions to boiling water reactor (BWR) water have been the focus of recent interest, primarily because of their beneficial influence in reducing buildup of radioactive species such as Co{sup 60} in the oxide film of structural components, e.g., stainless steel piping. The effect of ZnO additions on stress corrosion crack growth rates were studied using 1T CT fracture mechanics specimens of sensitized type 304 stainless steel, sensitized Alloy 600, and Alloy 182 weld metal exposed to {approx}288 C water containing various levels of dissolved oxygen and impurities. Zn levels of 5 to 100 ppb Zn{sup 2+} were evaluated and found to reduce crack growth rates for all materials and in all water chemistries. Many Zn tests involved long term exposure and were performed at somewhat reduced corrosion potential (e.g., from {approx}+200 to 0 {minus}+50 mV{sub she}); variations in corrosion potential from +200, to +50, to {minus}50 mV{sub she} clearly had an important effect. The benefit of Zn appeared to be most pronounced when the growth rate was decreased (e.g., by corrosion potential). This was consistent with the findings of mechanistic studies, which showed that Zn decreased the repassivation response at times >10{sup 4} s, which is associated with low crack tip strain rates, i.e., low growth rates. Reduced corrosion potentials are also expected to directly effect Zn, since high (crack mouth) corrosion potentials inhibit the transport of Zn{sup 2+} into the crack. Zn also increased the fracture strain of the oxide on stainless steel, and may also reduce crack growth rates by increasing the pH in the crack. Similar benefits are expected for other structural materials, such as nonsensitized or irradiated stainless steel, carbon steel, low alloy steel, and other nickel alloys.

  12. Effect of cold-work on self-welding susceptibility of austenitic stainless steel (alloy D9) in high temperature flowing sodium

    NASA Astrophysics Data System (ADS)

    Meikandamurthy, C.; Kumar, Hemant; Chakraborty, Gopa; Albert, S. K.; Ramakrishnan, V.; Rajan, K. K.; Bhaduri, A. K.

    2010-12-01

    Self-welding susceptibility of alloy D9 (15Cr-15Ni-2Mo titanium-modified austenitic stainless steel), used as wrapper in the fuel subassemblies of sodium cooled fast reactor, was studied in flowing sodium. Specimens were tested at 823 K in annealed and in 20% cold-worked condition up to a maximum contact stress of 24.5 MPa and maximum duration of 9 months. The results showed that the annealed alloy D9 showed good resistance to self-welding in all the tests. But 20% cold-worked alloy D9 got self-welded in all the tests except in the test carried out for 3 months duration indicating that tests conducted at high contact stresses and long duration reduce the resistance of the steel to self-weld. Microstructural changes observed in the cold-worked alloy D9 at the location of contact between the mating surfaces indicate dynamic recovery resulting from high contact stress and temperature facilitating self-weld.

  13. Friction Stir Spot Welding of Advanced High Strength Steels

    SciTech Connect

    Hovanski, Yuri; Grant, Glenn J.; Santella, M. L.

    2009-11-13

    Friction stir spot welding techniques were developed to successfully join several advanced high strength steels. Two distinct tool materials were evaluated to determine the effect of tool materials on the process parameters and joint properties. Welds were characterized primarily via lap shear, microhardness, and optical microscopy. Friction stir spot welds were compared to the resistance spot welds in similar strength alloys by using the AWS standard for resistance spot welding high strength steels. As further comparison, a primitive cost comparison between the two joining processes was developed, which included an evaluation of the future cost prospects of friction stir spot welding in advanced high strength steels.

  14. Advanced characterization techniques in understanding the roles of nickel in enhancing strength and toughness of submerged arc welding high strength low alloy steel multiple pass welds in the as-welded condition

    NASA Astrophysics Data System (ADS)

    Sham, Kin-Ling

    Striving for higher strength along with higher toughness is a constant goal in material properties. Even though nickel is known as an effective alloying element in improving the resistance of a steel to impact fracture, it is not fully understood how nickel enhances toughness. It was the goal of this work to assist and further the understanding of how nickel enhanced toughness and maintained strength in particular for high strength low alloy (HSLA) steel submerged arc welding multiple pass welds in the as-welded condition. Using advanced analytical techniques such as electron backscatter diffraction, x-ray diffraction, electron microprobe, differential scanning calorimetry, and thermodynamic modeling software, the effect of nickel was studied with nickel varying from one to five wt. pct. in increments of one wt. pct. in a specific HSLA steel submerged arc welding multiple pass weldment. The test matrix of five different nickel compositions in the as-welded and stress-relieved condition was to meet the targeted mechanical properties with a yield strength greater than or equal to 85 ksi, a ultimate tensile strength greater than or equal to 105 ksi, and a nil ductility temperature less than or equal to -140 degrees F. Mechanical testing demonstrated that nickel content of three wt. pct and greater in the as-welded condition fulfilled the targeted mechanical properties. Therefore, one, three, and five wt. pct. nickel in the as-welded condition was further studied to determine the effect of nickel on primary solidification mode, nickel solute segregation, dendrite thickness, phase transformation temperatures, effective ferrite grain size, dislocation density and strain, grain misorientation distribution, and precipitates. From one to five wt. pct nickel content in the as-welded condition, the primary solidification was shown to change from primary delta-ferrite to primary austenite. The nickel partitioning coefficient increased and dendrite/cellular thickness was

  15. Simulation of the elastic deformation of laser-welded joints of an austenitic corrosion-resistant steel and a titanium alloy with an intermediate copper insert

    NASA Astrophysics Data System (ADS)

    Pugacheva, N. B.; Myasnikova, M. V.; Michurov, N. S.

    2016-02-01

    The macro- and microstructures and the distribution of elements and of the values of the microhardness and contact modulus of elasticity along the height and width of the weld metal and heat-affected zone of austenitic corrosion-resistant 12Kh18N10T steel (Russian analog of AISI 321) and titanium alloy VT1-0 (Grade 2) with an intermediate copper insert have been studied after laser welding under different conditions. The structural inhomogeneity of the joint obtained according to one of the regimes selected has been shown: the material of the welded joint represents a supersaturated solid solution of Fe, Ni, Cr, and Ti in the crystal lattice of copper with a uniformly distributed particles of intermetallic compounds Ti(Fe,Cr) and TiCu3. At the boundaries with steel and with the titanium alloy, diffusion zones with thicknesses of 0.1-0.2 mm are formed that represent supersaturated solid solutions based on iron and titanium. The strength of such a joint was 474 MPa, which corresponds to the level of strength of the titanium alloy. A numerical simulation of the mechanical behavior of welded joints upon the elastic tension-compression has been performed taking into account their structural state, which makes it possible to determine the amplitude values of the deformations of the material of the weld.

  16. The Effect of Nb and S Segregation on the Solidification Cracking of Alloy 52M Weld Overlay on CF8 Stainless Steel

    NASA Astrophysics Data System (ADS)

    Chu, H. A.; Young, M. C.; Chu, H. C.; Tsay, L. W.; Chen, C.

    2014-03-01

    The weld overlay of Alloy 52M (a nickel-based filler metal) on a cast 304 (CF8) stainless steel (SS) was made to simulate overlay welding of the safe end of reactor pressure vessels in nuclear power plants. The deteriorated effect of sulfur on solidification cracking of the Alloy 52M overlay was highlighted by using a CF8 substrate with 0.14 wt.% S. Severe solidification cracking was observed when Alloy 52M was directly overlaid on the CF8 substrate. To lower the cracking susceptibility, ER 308L was deposited on the CF8 SS as a buffer layer before the subsequent deposition of Alloy 52M. Under such circumstances, the region near the weld interface between the SS buffer layer and Alloy 52M overlay was susceptible to solidification cracking. The formation of γ-NbC(N), γ-Laves, and γ-(Fe-Ni-S) eutectic-type constituents at the solidification boundaries was responsible for cracking near the weld interface. Nevertheless, depositing two layers of 308L prior to applying Alloy 52M could effectively reduce the cracking susceptibility of the overlay.

  17. Pulsed Magnetic Welding for Advanced Core and Cladding Steel

    SciTech Connect

    Cao, Guoping; Yang, Yong

    2013-12-19

    To investigate a solid-state joining method, pulsed magnetic welding (PMW), for welding the advanced core and cladding steels to be used in Generation IV systems, with a specific application for fuel pin end-plug welding. As another alternative solid state welding technique, pulsed magnetic welding (PMW) has not been extensively explored on the advanced steels. The resultant weld can be free from microstructure defects (pores, non-metallic inclusions, segregation of alloying elements). More specifically, the following objectives are to be achieved: 1. To design a suitable welding apparatus fixture, and optimize welding parameters for repeatable and acceptable joining of the fuel pin end-plug. The welding will be evaluated using tensile tests for lap joint weldments and helium leak tests for the fuel pin end-plug; 2 Investigate the microstructural and mechanical properties changes in PMW weldments of proposed advanced core and cladding alloys; 3. Simulate the irradiation effects on the PWM weldments using ion irradiation.

  18. Underwater wet welding of steel

    SciTech Connect

    Ibarra, S.; Liu, S.; Olson, D.L.

    1995-05-01

    Underwater wet welding is conducted directly in water with the shielded metal arc (SMA) and flux cored arc (FCA) welding processes. Underwater wet welding has been demonstrated as an acceptable repair technique down to 100 meters (325 ft.) in depth, but wet welds have been attempted on carbon steel structures down to 200 meters (650 ft.). The primary purpose of this interpretive report is to document and evaluate current understanding of metallurgical behavior of underwater wet welds so that new welding consumables can be designed and new welding practices can be developed for fabrication and repair of high strength steel structures at greater depths. First the pyrometallurgical and physical metallurgy behaviors of underwater weldments are discussed. Second, modifications of the welding consumables and processes are suggested to enhance the ability to apply wet welding techniques.

  19. Forming Limits of Weld Metal in Aluminum Alloys and Advanced High-Strength Steels

    SciTech Connect

    Stephens, Elizabeth V.; Smith, Mark T.; Grant, Glenn J.; Davies, Richard W.

    2010-10-25

    This work characterizes the mechanical properties of DP600 laser welded TWBs (1 mm-1.5 mm) near and in the weld, as well as their limits of formability. The approach uses simple uniaxial experiments to measure the variability in the forming limits of the weld region, and uses a theoretical forming limit diagram calculation to establish a probabilistic distribution of weld region imperfection using an M-K method approach

  20. Hot Ductility Behaviors in the Weld Heat-Affected Zone of Nitrogen-Alloyed Fe-18Cr-10Mn Austenitic Stainless Steels

    NASA Astrophysics Data System (ADS)

    Moon, Joonoh; Lee, Tae-Ho; Hong, Hyun-Uk

    2015-04-01

    Hot ductility behaviors in the weld heat-affected zone (HAZ) of nitrogen-alloyed Fe-18Cr-10Mn austenitic stainless steels with different nitrogen contents were evaluated through hot tension tests using Gleeble simulator. The results of Gleeble simulations indicated that hot ductility in the HAZs deteriorated due to the formation of δ-ferrite and intergranular Cr2N particles. In addition, the amount of hot ductility degradation was strongly affected by the fraction of δ-ferrite.

  1. Variation in the Chemical Driving Force for Intragranular Nucleation in the Multi-pass Weld Metal of Ti-Containing High-Strength Low-Alloy Steel

    NASA Astrophysics Data System (ADS)

    Kang, Yongjoon; Han, Kyutae; Park, Joo Hyun; Lee, Changhee

    2015-08-01

    The variation of the Mn-depleted zone (MDZ) around the inclusion during multi-pass welding of Ti-containing high-strength low-alloy (HSLA) steel was investigated by taking the changes in the impact toughness and microstructure into account. As-deposited weld metal specimens were prepared by single-pass, bead-in-groove welding, and reheated weld metal specimens were obtained by a thermal simulation technique. Two types of chemical compositions were prepared, mainly by controlling the Ti content in order to form two types of phases at inclusion/matrix interface: spinel and ilmenite. When the reheating thermal cycle is applied to the as-deposited weld metal, the MDZ depth varied depending on the inclusion surface phase; this could be explained by the competition of the homogenization effect and the dissolution effect, which occurred near the inclusion/matrix interface. In order to enhance the chemical driving force for intragranular nucleation in both as-deposited weld metal and reheated weld metal, the formation of ilmenite phase is recommended.

  2. Laser welding of NiTi shape memory alloy: Comparison of the similar and dissimilar joints to AISI 304 stainless steel

    NASA Astrophysics Data System (ADS)

    Mirshekari, G. R.; Saatchi, A.; Kermanpur, A.; Sadrnezhaad, S. K.

    2013-12-01

    The unique properties of NiTi alloy, such as its shape memory effect, super-elasticity and biocompatibility, make it ideal material for various applications such as aerospace, micro-electronics and medical device. In order to meet the requirement of increasing applications, great attention has been given to joining of this material to itself and to other materials during past few years. Laser welding has been known as a suitable joining technique for NiTi shape memory alloy. Hence, in this work, a comparative study on laser welding of NiTi wire to itself and to AISI 304 austenitic stainless steel wire has been made. Microstructures, mechanical properties and fracture morphologies of the laser joints were investigated using optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD), Vickers microhardness (HV0.2) and tensile testing techniques. The results showed that the NiTi-NiTi laser joint reached about 63% of the ultimate tensile strength of the as-received NiTi wire (i.e. 835 MPa) with rupture strain of about 16%. This joint also enabled the possibility to benefit from the pseudo-elastic properties of the NiTi component. However, tensile strength and ductility decreased significantly after dissimilar laser welding of NiTi to stainless steel due to the formation of brittle intermetallic compounds in the weld zone during laser welding. Therefore, a suitable modification process is required for improvement of the joint properties of the dissimilar welded wires.

  3. Practical method of diffusion-welding steel plate in air

    NASA Technical Reports Server (NTRS)

    Holko, K. H.; Moore, T. J.

    1971-01-01

    Method is ideal for critical service requirements where parent metal properties are equaled in notch toughness, stress rupture and other characteristics. Welding technique variations may be used on a variety of materials, such as carbon steels, alloy steels, stainless steels, ceramics, and reactive and refractory materials.

  4. Welding tritium exposed stainless steel

    SciTech Connect

    Kanne, W.R. Jr.

    1994-11-01

    Stainless steels that are exposed to tritium become unweldable by conventional methods due to buildup of decay helium within the metal matrix. With longer service lives expected for tritium containment systems, methods for welding on tritium exposed material will become important for repair or modification of the systems. Solid-state resistance welding and low-penetration overlay welding have been shown to mitigate helium embrittlement cracking in tritium exposed 304 stainless steel. These processes can also be used on stainless steel containing helium from neutron irradiation, such as occurs in nuclear reactors.

  5. Method for welding chromium molybdenum steels

    DOEpatents

    Sikka, Vinod K.

    1986-01-01

    Chromium-molybdenum steels exhibit a weakening after welding in an area adjacent to the weld. This invention is an improved method for welding to eliminate the weakness by subjecting normalized steel to a partial temper prior to welding and subsequently fully tempering the welded article for optimum strength and ductility.

  6. Steel Collet For Welding Electrodes

    NASA Technical Reports Server (NTRS)

    Gilbert, Jeffrey L.; Gutow, David A.; Burley, Richard K.; Fogul, Irving

    1992-01-01

    Improved steel collet holds electrode for tungsten inert-gas welding but allows quick and easy replacement. Also ensures reliable arc starting. Slip-on compression ring compresses tapered section of body of collet around inner end of welding electrode. Collet mounted in receptacle below stack of lenses and filters in coaxial-vision welding torch. Blind hole in collet protects outermost lens from damage by electrode.

  7. Welding development for V-Cr-Ti alloys

    SciTech Connect

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

    1994-09-01

    Welds have been produced and characterized using the gas-tungsten arc (GTA) and electron beam (EB) welding processes. Thin sheet (0.75 mm) welds were made with three levels of interstitial contamination, and hardness and tensile properties were found to be strongly affected by oxygen pickup. Thick-section (6 mm) welds have been produced using both processes, and no embrittlement is experienced when high purity atmosphere is maintained. Metallographic examination shows a narrow, but coarse grained, heat affected zone for the GTA welds. Transition joint welding development between vanadium alloy and stainless steel has shown encouraging results.

  8. Multilayered titanium-steel composite produced by explosive welding

    NASA Astrophysics Data System (ADS)

    Malyutina, Yu. N.; Skorohod, K. A.; Shevtsova, K. E.; Chesnokova, A. V.

    2015-10-01

    Multilayered titanium-steel composite consisting of alternating high-strength and ductile metallic materials were produced by explosive welding. Different types of weld joints formed in the composite were recognized by methods of microstructural analysis. Wave-shaped and flat geometry of welds are typical of steel and titanium layers, respectively. Structural features such as lack of penetration, shear bands, recrystallized metals and martensitic structure were detected in the vortex and weld-adjacent zones of impacted materials. The impact strength of the layered composite was 65% higher as compared to that of VT23 titanium alloy. A favorable role of interlayers in the multilayered composite has been confirmed by toughness tests.

  9. 46 CFR 54.25-25 - Welding of quenched and tempered steels (modifies UHT-82).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... requirements of 46 CFR 57.03-1(d) apply to welded pressure vessels and non-pressure vessel type tanks of... 46 Shipping 2 2010-10-01 2010-10-01 false Welding of quenched and tempered steels (modifies UHT-82... ENGINEERING PRESSURE VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-25 Welding...

  10. 46 CFR 54.25-25 - Welding of quenched and tempered steels (modifies UHT-82).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... requirements of 46 CFR 57.03-1(d) apply to welded pressure vessels and non-pressure vessel type tanks of... 46 Shipping 2 2011-10-01 2011-10-01 false Welding of quenched and tempered steels (modifies UHT-82... ENGINEERING PRESSURE VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-25 Welding...

  11. 46 CFR 54.25-25 - Welding of quenched and tempered steels (modifies UHT-82).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... requirements of 46 CFR 57.03-1(d) apply to welded pressure vessels and non-pressure vessel type tanks of... 46 Shipping 2 2013-10-01 2013-10-01 false Welding of quenched and tempered steels (modifies UHT-82... ENGINEERING PRESSURE VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-25 Welding...

  12. 46 CFR 54.25-25 - Welding of quenched and tempered steels (modifies UHT-82).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... requirements of 46 CFR 57.03-1(d) apply to welded pressure vessels and non-pressure vessel type tanks of... 46 Shipping 2 2014-10-01 2014-10-01 false Welding of quenched and tempered steels (modifies UHT-82... ENGINEERING PRESSURE VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-25 Welding...

  13. 46 CFR 54.25-25 - Welding of quenched and tempered steels (modifies UHT-82).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... requirements of 46 CFR 57.03-1(d) apply to welded pressure vessels and non-pressure vessel type tanks of... 46 Shipping 2 2012-10-01 2012-10-01 false Welding of quenched and tempered steels (modifies UHT-82... ENGINEERING PRESSURE VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-25 Welding...

  14. Building A Simulation Model For The Prediction Of Temperature Distribution In Pulsed Laser Spot Welding Of Dissimilar Low Carbon Steel 1020 To Aluminum Alloy 6061

    SciTech Connect

    Yousef, Adel K. M.; Taha, Ziad A.; Shehab, Abeer A.

    2011-01-17

    This paper describes the development of a computer model used to analyze the heat flow during pulsed Nd: YAG laser spot welding of dissimilar metal; low carbon steel (1020) to aluminum alloy (6061). The model is built using ANSYS FLUENT 3.6 software where almost all the environments simulated to be similar to the experimental environments. A simulation analysis was implemented based on conduction heat transfer out of the key hole where no melting occurs. The effect of laser power and pulse duration was studied.Three peak powers 1, 1.66 and 2.5 kW were varied during pulsed laser spot welding (keeping the energy constant), also the effect of two pulse durations 4 and 8 ms (with constant peak power), on the transient temperature distribution and weld pool dimension were predicated using the present simulation. It was found that the present simulation model can give an indication for choosing the suitable laser parameters (i.e. pulse durations, peak power and interaction time required) during pulsed laser spot welding of dissimilar metals.

  15. 76 FR 66899 - Certain Circular Welded Non-Alloy Steel Pipe From Brazil, Mexico, the Republic of Korea, and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-28

    ... (``Sunset'') Review, 76 FR 38613 (July 1, 2011) (Notice of Initiation). The Department received a notice of...-Alloy Steel Pipe and Tube from Mexico, 74 FR 41681 (August 18, 2009). \\3\\ The Department found that Yieh... Circumstance Review, 70 FR 71802 (November 30, 2005). This notice also serves as the only reminder to...

  16. High-temperature creep rupture of low alloy ferritic steel butt-welded pipes subjected to combined internal pressure and end loadings.

    PubMed

    Vakili-Tahami, F; Hayhurst, D R; Wong, M T

    2005-11-15

    Constitutive equations are reviewed and presented for low alloy ferritic steels which undergo creep deformation and damage at high temperatures; and, a thermodynamic framework is provided for the deformation rate potentials used in the equations. Finite element continuum damage mechanics studies have been carried out using these constitutive equations on butt-welded low alloy ferritic steel pipes subjected to combined internal pressure and axial loads at 590 and 620 degrees C. Two dominant modes of failure have been identified: firstly, fusion boundary failure at high stresses; and, secondly, Type IV failure at low stresses. The stress level at which the switch in failure mechanism takes place has been found to be associated with the relative creep resistance and lifetimes, over a wide range of uniaxial stresses, for parent, heat affected zone, Type IV and weld materials. The equi-biaxial stress loading condition (mean diameter stress equal to the axial stress) has been confirmed to be the worst loading condition. For this condition, simple design formulae are proposed for both 590 and 620 degrees C. PMID:16243708

  17. Laser welding of aluminum alloys

    SciTech Connect

    Leong, K.H.; Sabo, K.R.; Sanders, P.G.; Spawr, W.J.

    1997-03-01

    Recent interest in reducing the weight of automobiles to increase fuel mileage has focused attention on the use of aluminum and associated joining technologies. Laser beam welding is one of the more promising methods for high speed welding of aluminum. Consequently, substantial effort has been expended in attempting to develop a robust laser beam welding process. Early results have not been very consistent in the process requirements but more definitive data has been produced recently. This paper reviews the process parameters needed to obtain consistent laser welds on 5,000 series aluminum alloys and discusses the research necessary to make laser processing of aluminum a reality for automotive applications.

  18. Laser Beam Welding of Nitride Steel Components

    NASA Astrophysics Data System (ADS)

    Gu, Hongping; Yin, Guobin; Shulkin, Boris

    Laser beam welding is a joining technique that has many advantages over conventional GMAW welding, such as low heat input, short cycle time as well as good cosmetic welds. Laser beam welding has been widely used for welding powertrain components in automotive industry. When welding nitride steel components, however, laser beam welding faces a great challenge. The difficulty lies in the fact that the nitride layer in the joint releases the nitrogen into the weld pool, resulting in a porous weld. This research presents an industrial ready solution to prevent the nitrogen from forming gas bubbles in the weld.

  19. Fusion welding of a modern borated stainless steel

    SciTech Connect

    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 interdendritic 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.

  20. Welding Behavior of Free Machining Stainless Steel

    SciTech Connect

    BROOKS,JOHN A.; ROBINO,CHARLES V.; HEADLEY,THOMAS J.; MICHAEL,JOSEPH R.

    2000-07-24

    The weld solidification and cracking behavior of sulfur bearing free machining austenitic stainless steel was investigated for both gas-tungsten arc (GTA) and pulsed laser beam weld processes. The GTA weld solidification was consistent with those predicted with existing solidification diagrams and the cracking response was controlled primarily by solidification mode. The solidification behavior of the pulsed laser welds was complex, and often contained regions of primary ferrite and primary austenite solidification, although in all cases the welds were found to be completely austenite at room temperature. Electron backscattered diffraction (EBSD) pattern analysis indicated that the nature of the base metal at the time of solidification plays a primary role in initial solidification. The solid state transformation of austenite to ferrite at the fusion zone boundary, and ferrite to austenite on cooling may both be massive in nature. A range of alloy compositions that exhibited good resistance to solidification cracking and was compatible with both welding processes was identified. The compositional range is bounded by laser weldability at lower Cr{sub eq}/Ni{sub eq} ratios and by the GTA weldability at higher ratios. It was found with both processes that the limiting ratios were somewhat dependent upon sulfur content.

  1. Laser assisted arc welding for aluminum alloys

    SciTech Connect

    Fuerschbach, P.W.

    2000-01-01

    Experiments have been performed using a coaxial end-effector to combine a focused laser beam and a plasma arc. The device employs a hollow tungsten electrode, a focusing lens, and conventional plasma arc torch nozzles to co-locate the focused beam and arc on the workpiece. Plasma arc nozzles were selected to protect the electrode from laser generated metal vapor. The project goal is to develop an improved fusion welding process that exhibits both absorption robustness and deep penetration for small scale (<1.5 mm thickness) applications. On aluminum alloys 6061 and 6111, the hybrid process has been shown to eliminate hot cracking in the fusion zone. Fusion zone dimensions for both stainless steel and aluminum were found to be wider than characteristic laser welds, and deeper than characteristic plasma arc welds.

  2. Probing Pulsed Current Gas Metal Arc Welding for Modified 9Cr-1Mo Steel

    NASA Astrophysics Data System (ADS)

    Krishnan, S.; Kulkarni, D. V.; De, A.

    2015-04-01

    Modified 9Cr-1Mo steels are commonly welded using gas tungsten arc welding process for its superior control over the rate of heat input and vaporization loss of the key alloying elements although the rate electrode deposition remains restricted. Recent developments in pulsed current gas metal arc welding have significantly improved its ability to enhance the rate of electrode deposition with a controlled heat input rate while its application for welding of modified 9Cr-1Mo steels is scarce. The present work reports a detailed experimental study on the pulsed current gas metal arc welding of modified 9Cr-1Mo steels. The effect of the shielding gas, welding current, and speed on the weld bead profile, microstructure and mechanical properties are examined. The results show that the pulsed current gas metal arc welding with appropriate welding conditions can provide acceptable bead profile and mechanical properties in welds of modified 9Cr-1Mo steels.

  3. The Effect of Alloying Elements on the Shear Strength of the Lap Joint of AZ31B Magnesium Alloy to Q235 Steel by Hybrid Laser-TIG Welding Technique

    NASA Astrophysics Data System (ADS)

    Liu, Liming; Qi, Xiaodong; Zhang, Zhaodong

    2012-06-01

    Welding between AZ31B Mg alloy and Q235 mild steel was examined in this study. The effects of welding parameters were first investigated on the penetration depth into the steel and the shear strength of the joints. The optimum parameters and the maximum shear strength were obtained. Based on these parameters, alloying elements in the form of interlayers were added into the joints, and the shear strength was improved as high as 98 pct of the AZ31B Mg alloy. Microstructures of the joints were inspected with a scanning electron microscope and an electron probe micro-analyzer. Two bonding modes were proposed, and their effects on the joint shear strength were discussed. It is suggested that the bonding changed from nonmetallurgical to "semimetallurgical" mode with the addition of the interlayers, which contributed to the enhancement of the shear strength. Micro-hardness profiles were measured in the fusion zone of the joints, and their influence on the joint strength was also discussed. Intermediate phases that distributed uniformly in the fusion zone strengthened the microstructures, and thus, the shear strength was elevated. An empirical trend for Cu and Ni interlayer selection was proposed.

  4. Effect of Structural Heterogeneity on In Situ Deformation of Dissimilar Weld Between Ferritic and Austenitic Steel

    NASA Astrophysics Data System (ADS)

    Ghosh, M.; Santosh, R.; Das, S. K.; Das, G.; Mahato, B.; Korody, J.; Kumar, S.; Singh, P. K.

    2015-08-01

    Low-alloy steel and 304LN austenitic stainless steel were welded using two types of buttering material, namely 309L stainless steel and IN 182. Weld metals were 308L stainless steel and IN 182, respectively, for two different joints. Cross-sectional microstructure of welded assemblies was investigated. Microhardness profile was determined perpendicular to fusion boundary. In situ tensile test was performed in scanning electron microscope keeping low-alloy steel-buttering material interface at the center of gage length. Adjacent to fusion boundary, low-alloy steel exhibited carbon-depleted region and coarsening of matrix grains. Between coarse grain and base material structure, low-alloy steel contained fine grain ferrite-pearlite aggregate. Adjacent to fusion boundary, buttering material consisted of Type-I and Type-II boundaries. Within buttering material close to fusion boundary, thin cluster of martensite was formed. Fusion boundary between buttering material-weld metal and weld metal-304LN stainless steel revealed unmixed zone. All joints failed within buttering material during in situ tensile testing. The fracture location was different for various joints with respect to fusion boundary, depending on variation in local microstructure. Highest bond strength with adequate ductility was obtained for the joint produced with 309L stainless steel-buttering material. High strength of this weld might be attributed to better extent of solid solution strengthening by alloying elements, diffused from low-alloy steel to buttering material.

  5. Thermal treatment of dissimilar steels' welded joints

    NASA Astrophysics Data System (ADS)

    Nikulina, A. A.; Denisova, A. S.; Gradusov, I. N.; Ryabinkina, P. A.; Rushkovets, M. V.

    2016-04-01

    In this paper combinations of chrome-nickel steel and high-carbon steel, produced by flash butt welding after heat treatment, are investigated. Light and electron microscopic studies show that the welded joints after heat treatment have a complex structure consisting of several phases as initial welded joints. A martensite structure in welded joints after thermal treatment at 300... 800 °C has been found.

  6. Repair welding on nitrided carbon steel pipe

    SciTech Connect

    Baumert, K.L.

    1994-12-31

    A carbon steel pipe containing primarily ammonia at 750--850 F developed a nitrided case 15--20 mils (0.4--0.5mm) deep. This did not affect the performance of the pipe during operation, however, repair welding was not possible because of cracking. A laboratory procedure was developed wherein nitrided pipe could be successfully welded. The technique consisted of stress relieving the pipe before welding. No post weld stress relief was necessary to effect a sound weld.

  7. Crack stability analysis of low alloy steel primary coolant pipe

    SciTech Connect

    Tanaka, T.; Kameyama, M.; Urabe, Y.

    1997-04-01

    At present, cast duplex stainless steel has been used for the primary coolant piping of PWRs in Japan and joints of dissimilar material have been applied for welding to reactor vessels and steam generators. For the primary coolant piping of the next APWR plants, application of low alloy steel that results in designing main loops with the same material is being studied. It means that there is no need to weld low alloy steel with stainless steel and that makes it possible to reduce the welding length. Attenuation of Ultra Sonic Wave Intensity is lower for low alloy steel than for stainless steel and they have advantageous inspection characteristics. In addition to that, the thermal expansion rate is smaller for low alloy steel than for stainless steel. In consideration of the above features of low alloy steel, the overall reliability of primary coolant piping is expected to be improved. Therefore, for the evaluation of crack stability of low alloy steel piping to be applied for primary loops, elastic-plastic future mechanics analysis was performed by means of a three-dimensioned FEM. The evaluation results for the low alloy steel pipings show that cracks will not grow into unstable fractures under maximum design load conditions, even when such a circumferential crack is assumed to be 6 times the size of the wall thickness.

  8. Automated GMA welding of austenitic stainless steel pipe

    SciTech Connect

    Tahash, G.J.

    1996-12-31

    The study focused on reducing weld cycle times of rotatable subassemblies (spools) using automated welding equipment. A unique automatic Gas Metal Arc Welding (GMAW) system was used to produce a series of pipe to pipe welds on 141 mm (5 in.) schedule 80 seamless stainless steel pipe. After manual tack welding, the adaptive control system welded the root pass of the argon gas backed open vee groove circumferential butt joints in the IG rotated position with short circuiting transfer GMAW. The fill and cover passes were welded automatically with spray transfer GMAW. Automatic welding cycle times were found to be 50--80 percent shorter than the current techniques of roll welding with Shielded Metal Arc Welding and manual Gas Tungsten Arc Welding. Weld costs ({Brit_pounds}/m), including amortization, for the various systems were compared. The cost of automated GMA welds was virtually equivalent to the most competitive methods while depositing 75% more filler metal per year. Also investigated were metallurgical effects generated by weld thermal cycling, and the associated effects on mechanical properties of the weld joint. Mechanical properties of the welds met or exceeded those of the base metal. Sensitization of the pipe did not occur in the heat affected zone (HAZ), based on the absence of evidence of intergranular attack in modified Strauss corrosion tests and despite the fact of interpass temperatures well above recommended maximums. Cooling rates of 3--5 C/s in the heat affected zone of the four pass welds were measured by thermocouple technique and found to be within the non-sensitizing range for this alloy.

  9. Microstructural Characterization of Friction Stir Welded Aluminum-Steel Joints

    NASA Astrophysics Data System (ADS)

    Patterson, Erin E.; Hovanski, Yuri; Field, David P.

    2016-06-01

    This work focuses on the microstructural characterization of aluminum to steel friction stir welded joints. Lap weld configuration coupled with scribe technology used for the weld tool have produced joints of adequate quality, despite the significant differences in hardness and melting temperatures of the alloys. Common to friction stir processes, especially those of dissimilar alloys, are microstructural gradients including grain size, crystallographic texture, and precipitation of intermetallic compounds. Because of the significant influence that intermetallic compound formation has on mechanical and ballistic behavior, the characterization of the specific intermetallic phases and the degree to which they are formed in the weld microstructure is critical to predicting weld performance. This study used electron backscatter diffraction, energy dispersive spectroscopy, scanning electron microscopy, and Vickers micro-hardness indentation to explore and characterize the microstructures of lap friction stir welds between an applique 6061-T6 aluminum armor plate alloy and a RHA homogeneous armor plate steel alloy. Macroscopic defects such as micro-cracks were observed in the cross-sectional samples, and binary intermetallic compound layers were found to exist at the aluminum-steel interfaces of the steel particles stirred into the aluminum weld matrix and across the interfaces of the weld joints. Energy dispersive spectroscopy chemical analysis identified the intermetallic layer as monoclinic Al3Fe. Dramatic decreases in grain size in the thermo-mechanically affected zones and weld zones that evidenced grain refinement through plastic deformation and recrystallization. Crystallographic grain orientation and texture were examined using electron backscatter diffraction. Striated regions in the orientations of the aluminum alloy were determined to be the result of the severe deformation induced by the complex weld tool geometry. Many of the textures observed in the weld

  10. Microstructural Characterization of Friction Stir Welded Aluminum-Steel Joints

    NASA Astrophysics Data System (ADS)

    Patterson, Erin E.; Hovanski, Yuri; Field, David P.

    2016-03-01

    This work focuses on the microstructural characterization of aluminum to steel friction stir welded joints. Lap weld configuration coupled with scribe technology used for the weld tool have produced joints of adequate quality, despite the significant differences in hardness and melting temperatures of the alloys. Common to friction stir processes, especially those of dissimilar alloys, are microstructural gradients including grain size, crystallographic texture, and precipitation of intermetallic compounds. Because of the significant influence that intermetallic compound formation has on mechanical and ballistic behavior, the characterization of the specific intermetallic phases and the degree to which they are formed in the weld microstructure is critical to predicting weld performance. This study used electron backscatter diffraction, energy dispersive spectroscopy, scanning electron microscopy, and Vickers micro-hardness indentation to explore and characterize the microstructures of lap friction stir welds between an applique 6061-T6 aluminum armor plate alloy and a RHA homogeneous armor plate steel alloy. Macroscopic defects such as micro-cracks were observed in the cross-sectional samples, and binary intermetallic compound layers were found to exist at the aluminum-steel interfaces of the steel particles stirred into the aluminum weld matrix and across the interfaces of the weld joints. Energy dispersive spectroscopy chemical analysis identified the intermetallic layer as monoclinic Al3Fe. Dramatic decreases in grain size in the thermo-mechanically affected zones and weld zones that evidenced grain refinement through plastic deformation and recrystallization. Crystallographic grain orientation and texture were examined using electron backscatter diffraction. Striated regions in the orientations of the aluminum alloy were determined to be the result of the severe deformation induced by the complex weld tool geometry. Many of the textures observed in the weld

  11. Solidification of an alloy 625 weld overlay

    SciTech Connect

    DuPont, J.N.

    1996-11-01

    The solidification behavior (microsegregation, secondary phase formation, and solidification temperature range) of an Alloy 625 weld overlay deposited on 2.25Cr-1Mo steel by gas metal arc welding was investigated by light and electron optical microscopy, electron microprobe, and differential thermal analysis techniques. The overlay deposit was found to terminate solidification at {approx}1,216 C by a {gamma}/Laves eutectic-type reaction. The Laves phase was highly enriched in Nb, Mo, and Si. The solidification reaction and microsegregation potential of major alloying elements in the overlay deposit are compared to other Nb-bearing Ni base alloys and found to be very similar to those for Alloy 718. Solidification cracks observed in the overlay were attributed to the wide solidification temperature range ({approx}170 C) and formation of interdendritic ({gamma} + Laves) constituent. Reasonable agreement is obtained between the calculated and measured volume percent ({gamma} + Laves) constituent with the Scheil equation by treating the overlay system as a simple {gamma}-Nb binary and using an experimentally determined k{sub Nb} value from electron microprobe data.

  12. Automatic welding of stainless steel tubing

    NASA Technical Reports Server (NTRS)

    Clautice, W. E.

    1978-01-01

    The use of automatic welding for making girth welds in stainless steel tubing was investigated as well as the reduction in fabrication costs resulting from the elimination of radiographic inspection. Test methodology, materials, and techniques are discussed, and data sheets for individual tests are included. Process variables studied include welding amperes, revolutions per minute, and shielding gas flow. Strip chart recordings, as a definitive method of insuring weld quality, are studied. Test results, determined by both radiographic and visual inspection, are presented and indicate that once optimum welding procedures for specific sizes of tubing are established, and the welding machine operations are certified, then the automatic tube welding process produces good quality welds repeatedly, with a high degree of reliability. Revised specifications for welding tubing using the automatic process and weld visual inspection requirements at the Kennedy Space Center are enumerated.

  13. Residual stress patterns in steel welds

    SciTech Connect

    Spooner, S.; Hubbard, C.R.; Wang, X.L.; David, S.A.; Holden, T.M.; Root, J.H.; Swainson, I.

    1994-12-31

    Neutron strain scanning of residual stress is a valuable nondestructive tool for evaluation of residual stress in welds. The penetrating characteristic of neutrons permits mapping of strain patterns with a spatial resolution approaching 1mm at depths of 20mm in steels. While the overall patterns of the residual stress tensor in a weld are understood, the detailed patterns depend on welding process parameters and the effects of solid state transformation. The residual strain profiles in two multi-pass austenitic welds and a ferritic steel weld are presented. The stress-free lattice parameters within the fusion zone and the adjacent heat affected zone in the two austenitic welds show that the interpretation of residual stress from strains are affected by welding parameters. An interpretation of the residual strain pattern in the ferritic steel plate can be made using the strain measurements of a Gleeble test bar which has undergone the solid state austenite decomposition.

  14. Weld Properties of a Free Machining Stainless Steel

    SciTech Connect

    J. A. Brooks; S. H. Goods; C. V. Robino

    2000-08-01

    The all weld metal tensile properties from gas tungsten arc and electron beam welds in free machining austenitic stainless steels have been determined. Ten heats with sulfur contents from 0.04 to 0.4 wt.% and a wide range in Creq/Nieq ratios were studied. Tensile properties of welds with both processes were related to alloy composition and solidification microstructure. The yield and ultimate tensile strengths increased with increasing Creq/Nieq ratios and ferrite content, whereas the ductility measured by RA at fracture decreased with sulfur content. Nevertheless, a range in alloy compositions was identified that provided a good combination of both strength and ductility. The solidification cracking response for the same large range of compositions are discussed, and compositions identified that would be expected to provide good performance in welded applications.

  15. Microstructures in laser welded high strength steels

    NASA Astrophysics Data System (ADS)

    Rizzi, P.; Bellingeri, S.; Massimino, F.; Baldissin, D.; Battezzati, L.

    2009-01-01

    In this work, the effect of laser welding on the microstructure was studied for three Advanced High Strength Steels: transformation induced plasticity steel (TRIP), dual phase steel (DP) and martensitic steel. Two sheets of the same steel were laser welded and a microstructural study was performed by optical microscopy, scanning electron microscopy and X-ray diffraction. For all samples the welded zone was constituted by martensite and the heat affected zone shows a continuous change in microstructure depending on temperatures reached and on the different cooling rates. The change in mechanical properties in the welded area was followed by Vickers micro-hardness measurements. Quasi binary phase diagrams were calculated and, according to position of T0 lines, it was deduced that austenite is the primary phase forming during rapid solidification for all steels.

  16. Modeling of the Thermal Field in Dissimilar Alloy Ultrasonic Welding

    NASA Astrophysics Data System (ADS)

    Jedrasiak, P.; Shercliff, H. R.; Chen, Y. C.; Wang, L.; Prangnell, P.; Robson, J.

    2015-02-01

    This paper describes a finite element model for predicting the temperature field in high power ultrasonic welding aluminum AA6111 to two dissimilar alloys, magnesium AZ31, and low carbon steel DC04. Experimental thermocouple and other evidence are used to infer the magnitude and distribution of the heat input to the workpiece, as a function of time, for each of the material combinations welded. The resulting temperature histories are used to predict the growth of intermetallic phases at the interface in Al-Mg welds. The microstructural model successfully predicts the thickness of the intermetallic layer, but the sensitivity of the results to temperature is demonstrated.

  17. Numerical simulation and experimental investigation of laser dissimilar welding of carbon steel and austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Nekouie Esfahani, M. R.; Coupland, J.; Marimuthu, S.

    2015-07-01

    This study reports an experimental and numerical investigation on controlling the microstructure and brittle phase formation during laser dissimilar welding of carbon steel to austenitic stainless steel. The significance of alloying composition and cooling rate were experimentally investigated. The investigation revealed that above a certain specific point energy the material within the melt pool is well mixed and the laser beam position can be used to control the mechanical properties of the joint. The heat-affected zone within the high-carbon steel has significantly higher hardness than the weld area, which severely undermines the weld quality. A sequentially coupled thermo-metallurgical model was developed to investigate various heat-treatment methodology and subsequently control the microstructure of the HAZ. Strategies to control the composition leading to dramatic changes in hardness, microstructure and service performance of the dissimilar laser welded fusion zone are discussed.

  18. Electroslag welding of titanium and its alloys

    SciTech Connect

    Malin, V.Y.

    1985-02-01

    The objective of this review is to examine the specific requirements of the electroslag welding process when applied to thick-wall components made from titanium or its various alloys. The review includes process variations, flux and equipment development requirements, specifics of the various techniques, wire and shielding gas supply problems, welding conditions, properties of the welds, quality control, and other topics.

  19. Weld pool oscillation during GTA welding of mild steel

    SciTech Connect

    Xiao, Y.H.; Ouden, G. den . Dept. of Materials Science and Engineering)

    1993-08-01

    In this paper the results are reported of a study dealing with the oscillation behavior of weld pools in the case of GTA bead-on-plate welding of mild steel, Fe 360. During welding, the weld pool was brought into oscillation by applying short current pulses, and the oscillation frequency and amplitude were measured by monitoring the arc voltage. It was found that the oscillation of the partially penetrated weld pool is dominated by one of two different oscillation modes (Mode 1 and Mode 2) depending on the welding conditions, whereas the oscillation of the fully penetrated weld pool is characterized by a third oscillation mode (Mode 3). It is possible to maintain partially penetrated weld pool oscillation in Mode 1 by choosing appropriate welding conditions. Under these conditions, an abrupt decrease in oscillation frequency occurs when the weld pool transfers from partial penetration to full penetration. Thus, weld penetration can be in-process controlled by monitoring the oscillation frequency during welding.

  20. Welding of gamma titanium aluminide alloys

    NASA Technical Reports Server (NTRS)

    Smashey, Russell W. (Inventor); Kelly, Thomas J. (Inventor); Snyder, John H. (Inventor); Sheranko, Ronald L. (Inventor)

    1998-01-01

    An article made of a gamma titanium aluminide alloy is welded, as for example in the weld repair of surface cracks, by removing foreign matter from the area to be welded, first stress relieving the article, cooling the entire article to a welding temperature of from about 1000.degree. F. to about 1400.degree. F., welding a preselected region in an inert atmosphere at the welding temperature, and second stress relieving the article. Welding is preferably accomplished by striking an arc in the preselected region so as to locally melt the alloy in the preselected region, providing a filler metal having the same composition as the gamma titanium aluminide alloy of the article, and feeding the filler metal into the arc so that the filler metal is melted and fused with the article to form a weldment upon solidification.

  1. Effect of Interfacial Reaction on the Mechanical Performance of Steel to Aluminum Dissimilar Ultrasonic Spot Welds

    NASA Astrophysics Data System (ADS)

    Xu, Lei; Wang, Li; Chen, Ying-Chun; Robson, Joe D.; Prangnell, Philip B.

    2016-01-01

    The early stages of formation of intermetallic compounds (IMC) have been investigated in dissimilar aluminum to steel welds, manufactured by high power (2.5 kW) ultrasonic spot welding (USW). To better understand the influence of alloy composition, welds were produced between a low-carbon steel (DC04) and two different aluminum alloys (6111 and 7055). The joint strengths were measured in lap shear tests and the formation and growth behavior of IMCs at the weld interface were characterized by electron microscopy, for welding times from 0.2 to 2.4 seconds. With the material combinations studied, the η (Fe2Al5) intermetallic phase was found to form first, very rapidly in the initial stage of welding, with a discontinuous island morphology. Continuous layers of η and then θ (FeAl3) phase were subsequently seen to develop on extending the welding time to greater than 0.7 second. The IMC layer formed in the DC04-AA7055 combination grew thicker than for the DC04-AA6111 welds, despite both weld sets having near identical thermal histories. Zinc was also found to be dissolved in the IMC phases when welding with the AA7055 alloy. After post-weld aging of the aluminum alloy, fracture in the lap shear tests always occurred along the joint interface; however, the DC04-AA6111 welds had higher fracture energy than the DC04-AA7055 combination.

  2. Effect of PTA Hardfaced Interlayer Thickness on Ballistic Performance of Shielded Metal Arc Welded Armor Steel Welds

    NASA Astrophysics Data System (ADS)

    Balakrishnan, M.; Balasubramanian, V.; Madhusudhan Reddy, G.

    2013-03-01

    Ballistic performance of armor steel welds is very poor due to the usage of low strength and low hardness austenitic stainless steel fillers, which are traditionally used to avoid hydrogen induced cracking. In the present investigation, an attempt has been made to study the effect of plasma transferred arc hardfaced interlayer thickness on ballistic performance of shielded metal arc welded armor steel weldments. The usefulness of austenitic stainless steel buttering layer on the armor grade quenched and tempered steel base metal was also considered in this study. Joints were fabricated using three different thickness (4, 5.5, and 7 mm) hardfaced middle layer by plasma transferred arc hardfacing process between the top and bottom layers of austenitic stainless steel using shielded metal arc welding process. Sandwiched joint, in addition with the buttering layer served the dual purpose of weld integrity and ballistic immunity due to the high hardness of hardfacing alloy and the energy absorbing capacity of soft backing weld deposits. This paper will provide some insight into the usefulness of austenitic stainless steel buttering layer on the weld integrity and plasma transferred arc hardfacing layer on ballistic performance enhancement of armor steel welds.

  3. Performance of high molybdenum superaustenitic stainless steel welds in harsh chloride environments

    SciTech Connect

    Stenvall, P.; Liljas, M.; Wallen, B.

    1996-11-01

    Superaustenitic steels are normally welded with nickel-based alloys as filler materials. To clarify the understanding of weld behavior in superaustenitic stainless steels this paper presents the development history of 6Mo and 7Mo steels, and results of laboratory tests and field tests on welds of UNS S31254 (6Mo) and UNS S32654 (7 Mo) in different types of chloride containing environments. The laboratory tests consisted of the well known ferric chloride test (ASTM G 48 Method A). Shielded metal arc welds, gas tungsten arc welds and submerged arc welds in both grades were tested. The critical pitting temperatures were determined and the locations of the attack were noted. Some specimens were sectioned at the position of the attack followed by studies using light optical microscopy. The critical pitting temperatures of the welds in S31254 and S32654 were at normal levels for both grades, i.e., 40--50 C for S31254 and 60--75 C for S32654. The locations of the attack differed depending on the welding process. In shielded metal arc welds the attack was mostly located in the weld metal. In gas tungsten arc welds the attack was predominantly located next to the fusion line. The field tests showed that the behavior of welds and parent metal of superaustenitic stainless steels, as well as of nickel-based alloys, is much dependent on the corrosive environment. In oxidizing chloride solutions, similar results to those of the ferric chloride test, are observed. However, crevice corrosion in the parent material is at a greater risk than pitting corrosion in the welds. In very oxidizing solutions of low chloride concentrations, welds made of nickel-based fillers may corrode faster than the stainless steel base metal due to transpassive uniform corrosion. The opposite situation exists when active uniform corrosion prevails, i.e., welds made of nickel-based fillers corrode less than the stainless steel parent material.

  4. Filler wire for aluminum alloys and method of welding

    NASA Technical Reports Server (NTRS)

    Bjorkman, Jr., Gerald W. O. (Inventor); Cho, Alex (Inventor); Russell, Carolyn K. (Inventor)

    2003-01-01

    A weld filler wire chemistry has been developed for fusion welding 2195 aluminum-lithium. The weld filler wire chemistry is an aluminum-copper based alloy containing high additions of titanium and zirconium. The additions of titanium and zirconium reduce the crack susceptibility of aluminum alloy welds while producing good weld mechanical properties. The addition of silver further improves the weld properties of the weld filler wire. The reduced weld crack susceptibility enhances the repair weldability, including when planishing is required.

  5. Hybrid Laser-Arc Welding Tanks Steels

    NASA Astrophysics Data System (ADS)

    Turichin, G.; Tsibulskiy, I.; Kuznetsov, M.; Akhmetov, A.; Klimova-Korsmik, O.

    2016-04-01

    The results investigate hybrid laser-arc welding of high strength steels using design responsible metallic construction and the highest strength body of vehicles. Welds from modern high strength steels grade Hardox 400, Hardox 450, Armox 600T and AB were created. High power fiber laser LS-15 with output 15 kW and arc rectifier VDU - 1500 DC were used in the experiment. Results of the metallographic research and mechanical tests are presented.

  6. Alloyed steel wastes utilization

    SciTech Connect

    Sokol, I.V.

    1995-12-31

    Alloyed steel chips and swarf formed during metal processing are looked upon as additional raw materials in metallurgical production. This paper presents some new methods for steel waste chips and swarf cleaning. One of them is swarf and steel chips cleaning in tetrachloroethylene with ultrasonic assistance and solvent regeneration. Thermal cleaning of waste chips and swarf provides off gas products utilization. The catalyst influence of the metal surface on the thermal decomposition of liquid hydrocarbons during the cleaning process has been studied. It has been determined that the efficiency of this metal waste cleaning technique depends on the storage time of the swarf. The waste chips and swarf cleaning procedures have been proven to be economically advantageous and environmentally appropriate.

  7. Ultrasonic inspection of austenitic stainless steel welds with artificially produced stress corrosion cracks

    SciTech Connect

    Dugan, Sandra; Wagner, Sabine

    2014-02-18

    Austenitic stainless steel welds and nickel alloy welds, which are widely used in nuclear power plants, present major challenges for ultrasonic inspection due to the grain structure in the weld. Large grains in combination with the elastic anisotropy of the material lead to increased scattering and affect sound wave propagation in the weld. This results in a reduced signal-to-noise ratio, and complicates the interpretation of signals and the localization of defects. Mechanized ultrasonic inspection was applied to study austenitic stainless steel test blocks with different types of flaws, including inter-granular stress corrosion cracks (IGSCC). The results show that cracks located in the heat affected zone of the weld are easily detected when inspection from both sides of the weld is possible. In cases of limited accessibility, when ultrasonic inspection can be carried out only from one side of a weld, it may be difficult to distinguish between signals from scattering in the weld and signals from cracks.

  8. Ultrasonic inspection of austenitic stainless steel welds with artificially produced stress corrosion cracks

    NASA Astrophysics Data System (ADS)

    Dugan, Sandra; Wagner, Sabine

    2014-02-01

    Austenitic stainless steel welds and nickel alloy welds, which are widely used in nuclear power plants, present major challenges for ultrasonic inspection due to the grain structure in the weld. Large grains in combination with the elastic anisotropy of the material lead to increased scattering and affect sound wave propagation in the weld. This results in a reduced signal-to-noise ratio, and complicates the interpretation of signals and the localization of defects. Mechanized ultrasonic inspection was applied to study austenitic stainless steel test blocks with different types of flaws, including inter-granular stress corrosion cracks (IGSCC). The results show that cracks located in the heat affected zone of the weld are easily detected when inspection from both sides of the weld is possible. In cases of limited accessibility, when ultrasonic inspection can be carried out only from one side of a weld, it may be difficult to distinguish between signals from scattering in the weld and signals from cracks.

  9. Polyimide weld bonding for titanium alloy joints

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Kurland, R. M.

    1974-01-01

    Two weld bonding processes were developed for joining titanium alloy; one process utilizes a weld-through technique and the other a capillary-flow technique. The adhesive used for the weld-through process is similar to the P4/A5F system. A new polyimide laminating resin, BFBI/BMPM, was used in the capillary-flow process. Static property information was generated for weld-bonded joints over the temperature range of 219 K (-65 F) to 561 K (+550 F) and fatigue strength information was generated at room temperature. Significant improvement in fatigue strength was demonstrated for weld-bonded joints over spot-welded joints. A demonstration was made of the applicability of the weld-through weld-bonding process for fabricating stringer stiffened skin panels.

  10. Embrittlement of austenitic stainless steel welds

    SciTech Connect

    David, S.A.; Vitek, J.M.; Alexander, D.J.

    1995-06-01

    To prevent hot-cracking, austenitic stainless steel welds generally contain a small percent of delta ferrite. Although ferrite has been found to effectively prevent hot-cracking, it can lead to embrittlement of welds when exposed to elevated temperatures. The aging behavior of type-308 stainless steel weld has been examined over a range of temperatures 475--850 C for times up to 10,000 hrs. Upon aging, and depending on the temperature range, the unstable ferrite may undergo a variety of solid state transformations. These phase changes creep-rupture and Charpy impact properties.

  11. 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

  12. Optimization of Fiber Laser Welding of DP980 Steels Using RSM to Improve Weld Properties for Formability

    NASA Astrophysics Data System (ADS)

    Bandyopadhyay, K.; Panda, S. K.; Saha, P.

    2016-06-01

    The effect of laser parameters on weld quality is a critical laboratory study before implementation of newly developed high-strength dual-phase steels in fabrication of auto-bodies. In present work, dual-phase steels having tensile strength of 980 MPa (DP980) were welded using different welding speeds by Yb-fiber laser source to fabricate similar material combinations laser-welded blanks (LWBs). The weld zone microhardness, microstructure, and formability of DP980 LWBs were compared with those of the DP600 and micro-alloyed interstitial free high-strength steel (IFHS) LWBs. It was found that the formation of soft zone at the outer side of the HAZ was responsible for significant reduction in formability of DP980 LWBs due to strain localization and premature failure. Hence, response surface methodology based on Box-Behnken design was implemented to establish a mathematical model which could correlate the influence of laser process parameters such as power, welding speed, and focal position on weld quality in terms of aspect ratio of fusion zone, width of the soft zone, and surface roughness of weld to improve formability. The model was successfully implemented to optimize the laser parameters, and approximately 13.58% improvement in Erichsen cup height was achieved due to complete weld penetration with simultaneous 67% reduction in soft zone width and 55% reduction in softening. However, the failure was still observed to occur in the soft zone propagating parallel to weld in radial direction.

  13. Delta ferrite in the weld metal of reduced activation ferritic martensitic steel

    NASA Astrophysics Data System (ADS)

    Sam, Shiju; Das, C. R.; Ramasubbu, V.; Albert, S. K.; Bhaduri, A. K.; Jayakumar, T.; Rajendra Kumar, E.

    2014-12-01

    Formation of delta(δ)-ferrite in the weld metal, during autogenous bead-on-plate welding of Reduced Activation Ferritic Martensitic (RAFM) steel using Gas Tungsten Arc Welding (GTAW) process, has been studied. Composition of the alloy is such that delta-ferrite is not expected in the alloy; but examination of the weld metal revealed presence of delta-ferrite in the weld metal. Volume fraction of delta-ferrite is found to be higher in the weld interface than in the rest of the fusion zone. Decrease in the volume fraction of delta-ferrite, with an increase in preheat temperature or with an increase in heat input, is observed. Results indicate that the cooling rate experienced during welding affects the volume fraction of delta-ferrite retained in the weld metal and variation in the delta-ferrite content with cooling rate is explained with variation in the time that the weld metal spends in various temperature regimes in which delta-ferrite is stable for the alloy during its cooling from the liquid metal to the ambient temperature. This manuscript will discuss the effect of welding parameters on formation of delta-ferrite and its retention in the weld metal of RAFM steel.

  14. Corrosion of nickel and Monel welds of steel in chlorine trifluoride

    SciTech Connect

    Fout, S.L.

    1988-07-25

    Failures in the weld areas of nickel-plated steel pipe carrying chlorine trifluoride, ClF/sub 3/, prompted this investigation to determine the effect of weld composition on corrosion by ClF/sub 3/. Monel/steel and nickel/steel alloys of composition to simulate weld overlays were tested to determine their corrosion rates in ClF/sub 3/ at 200/degree/F and 300/degree/F. For both nickel/steel and Monel/steel, the corrosion rate was higher at the higher temperature. For nickel/steel alloys at compositions up to 50% iron, which would cover a range considered normal for welding, the corrosion rate would be within acceptable limits. For Monel/steel alloys, compositions up to 35% iron have an acceptable corrosion rate. Above this, the corrosion would be greater than a tolerable amount. It should pose no problem to keep the heat input to the weld low enough to produce a Monel weld with an iron content below 35%. 2 refs., 5 figs., 2 tabs.

  15. Automatic Welding of Stainless Steel Tubing

    NASA Technical Reports Server (NTRS)

    Clautice, W. E.

    1978-01-01

    To determine if the use of automatic welding would allow reduction of the radiographic inspection requirement, and thereby reduce fabrication costs, a series of welding tests were performed. In these tests an automatic welder was used on stainless steel tubing of 1/2, 3/4, and 1/2 inch diameter size. The optimum parameters were investigated to determine how much variation from optimum in machine settings could be tolerate and still result in a good quality weld. The process variables studied were the welding amperes, the revolutions per minute as a function of the circumferential weld travel speed, and the shielding gas flow. The investigation showed that the close control of process variables in conjunction with a thorough visual inspection of welds can be relied upon as an acceptable quality assurance procedure, thus permitting the radiographic inspection to be reduced by a large percentage when using the automatic process.

  16. Cooling induced segregation of impurity elements to grain boundaries in Fe-3wt%Ni alloys, 2[1/4]wt%Cr-1wt%Mo steel and submerged arc weld metal

    SciTech Connect

    Vorlicek, V.; Flewitt, P.E.J. . Technology Div.)

    1994-10-01

    Previous theoretical and experimental studies demonstrate that small bulk concentrations of impurity and solute elements can segregate to grain boundaries in ferritic steels during cooling from high temperatures. This results from solute-vacancy pair formation and their subsequent diffusion to the grain boundary sinks. The grain boundary segregation which results from cooling at three different rates from fixed temperatures of 1,273 and 1,323 K respectively, have been measured on ferritic Fe-3 wt%Ni alloys and 2[1/4]wt%Cr-1wt%Mo steels containing additions of either P or Sn. In addition, a C-Mn submerged arc weld metal subject to a complex thermal cycle has been investigated. The composition of the grain boundaries have been measured on thin foil specimens using both conventional and high resolution STEM-EDS X-ray microanalysis techniques. Segregations of both P and Sn have been observed in the Fe-3 wt%Ni alloys and 2[1/4]wt%Cr-1wt%Mo steels and P segregations in the weld metal. The measured grain boundary segregations of both P and Sn are discussed with respect to previous theoretical predictions for the cooling rates investigated and the interactive role of other elements present.

  17. Laser Welding Dissimilar Reflective Alloys

    NASA Technical Reports Server (NTRS)

    Mccay, M. H.; Gopinathan, S.; Kahlen, F.; Speigel, L.

    1993-01-01

    This project, jointly sponsored by Rocketdyne and CSTAR, involves the development of laser joining of materials which have heretofore been impractical to bond. Of particular interest are joints between stainless steel and copper and also aluminum 6061 to aluminum 2219. CSTAR has a unique opportunity in this area since both the process and development and diagnostics are of interest to industry. Initial results using the pulse tailored laser welding technique developed in CLA for joining crack sensitive materials have proven promising for the aluminum joints based upon metallurgical and electronic microprobe analysis. A declaration of success requires additional mechanical testing. A CW technique has been applied to the stainless-copper joining with some preliminary success. These joints are of significant interest for aeronautics and rocket propulsion applications and the project is expected to continue.

  18. Laser welding dissimilar reflective alloys

    NASA Astrophysics Data System (ADS)

    McCay, M. H.; Gopinathan, S.; Kahlen, F.; Speigel, L.

    1993-01-01

    This project, jointly sponsored by Rocketdyne and CSTAR, involves the development of laser joining of materials which have heretofore been impractical to bond. Of particular interest are joints between stainless steel and copper and also aluminum 6061 to aluminum 2219. CSTAR has a unique opportunity in this area since both the process and development and diagnostics are of interest to industry. Initial results using the pulse tailored laser welding technique developed in CLA for joining crack sensitive materials have proven promising for the aluminum joints based upon metallurgical and electronic microprobe analysis. A declaration of success requires additional mechanical testing. A CW technique has been applied to the stainless-copper joining with some preliminary success. These joints are of significant interest for aeronautics and rocket propulsion applications and the project is expected to continue.

  19. High Strength Stainless Steel Properties that Affect Resistance Welding

    SciTech Connect

    Kanne, W.R.

    2001-08-01

    This report discusses results of a study on selected high strength stainless steel alloy properties that affect resistance welding. The austenitic alloys A-286, JBK-75 (Modified A-286), 21-6-9, 22-13-5, 316 and 304L were investigated and compared. The former two are age hardenable, and the latter four obtain their strength through work hardening. Properties investigated include corrosion and its relationship to chemical cleaning, the effects of heat treatment on strength and surface condition, and the effect of mechanical properties on strength and weldability.

  20. The Corrosion Resistance of Composite Arch Wire Laser-Welded By NiTi Shape Memory Alloy and Stainless Steel Wires with Cu Interlayer in Artificial Saliva with Protein

    PubMed Central

    Zhang, Chao; Sun, Xinhua; Hou, Xu; Li, Hongmei; Sun, Daqian

    2013-01-01

    In this paper, the corrosion resistance of laser-welded composite arch wire (CoAW) with Cu interlayer between NiTi shape memory alloy and stainless steel wire in artificial saliva with different concentrations of protein was studied. It was found that protein addition had a significant influence on the corrosion behavior of CoAW. Low concentration of protein caused the corrosion resistance of CoAW decrease in electrochemical corrosion and immersion corrosion tests. High concentration of protein could reduce this effect. PMID:23801895

  1. Investigation of underwater welding of steel

    SciTech Connect

    Shannon, G.J.; Watson, J.; Deans, W.F. . Dept. of Engineering)

    1994-12-01

    The preliminary underwater welding study described forms part of a European funded research program (EUREKA EU194) which involves a feasibility study into laser welding applications in the offshore oil industry. An investigation was undertaken using a 1.2 KW carbon dioxide laser for underwater butt welding of BS 4360 43A and 50D steel, in order to assess the quality of the welds and to achieve an understanding of the laser/water/material interaction. Using a high-speed camera, the temporal behavior of the melt pool and ''plasma'' dynamics surrounded by an aqueous environment were monitored. Experiments were undertaken to characterize the attenuation of the laser beam in the water as a function of various focal length optics and depth of water. The effect of energy input conditions on the weld bead appearance and mechanical properties were also examined. The interaction of the laser beam with water produced a wave-guiding mechanism in which the focused beam instantaneously vaporizes the water and directs the beam on to the workpiece. The underwater weld beads exhibited sound microstructures over a range of weld energy inputs, mainly due to the formation of a ''dry region'' during welding. Metallurgical analysis of the welds showed a slight increase in hardness, though other post-weld mechanical strengths were similar to in-air results.

  2. Self-Reacting Friction Stir Welding for Aluminum Alloy Circumferential Weld Applications

    NASA Technical Reports Server (NTRS)

    Bjorkman, Gerry; Cantrell, Mark; Carter, Robert

    2003-01-01

    Friction stir welding is an innovative weld process that continues to grow in use, in the commercial, defense, and space sectors. It produces high quality and high strength welds in aluminum alloys. The process consists of a rotating weld pin tool that plasticizes material through friction. The plasticized material is welded by applying a high weld forge force through the weld pin tool against the material during pin tool rotation. The high weld forge force is reacted against an anvil and a stout tool structure. A variation of friction stir welding currently being evaluated is self-reacting friction stir welding. Self-reacting friction stir welding incorporates two opposing shoulders on the crown and root sides of the weld joint. In self-reacting friction stir welding, the weld forge force is reacted against the crown shoulder portion of the weld pin tool by the root shoulder. This eliminates the need for a stout tooling structure to react the high weld forge force required in the typical friction stir weld process. Therefore, the self-reacting feature reduces tooling requirements and, therefore, process implementation costs. This makes the process attractive for aluminum alloy circumferential weld applications. To evaluate the application of self-reacting friction stir welding for aluminum alloy circumferential welding, a feasibility study was performed. The study consisted of performing a fourteen-foot diameter aluminum alloy circumferential demonstration weld using typical fusion weld tooling. To accomplish the demonstration weld, weld and tack weld development were performed and fourteen-foot diameter rings were fabricated. Weld development consisted of weld pin tool selection and the generation of a process map and envelope. Tack weld development evaluated gas tungsten arc welding and friction stir welding for tack welding rings together for circumferential welding. As a result of the study, a successful circumferential demonstration weld was produced leading

  3. Temporarily alloying titanium to facilitate friction stir welding

    SciTech Connect

    Hovanski, Yuri

    2009-05-01

    While historically hydrogen has been considered an impurity in titanium, when used as a temporary alloying agent it promotes beneficial changes to material properties that increase the hot-workability of the metal. This technique known as thermohydrogen processing was used to temporarily alloy hydrogen with commercially pure titanium sheet as a means of facilitating the friction stir welding process. Specific alloying parameters were developed to increase the overall hydrogen content of the titanium sheet ranging from commercially pure to 30 atomic percent. Each sheet was evaluated to determine the effect of the hydrogen content on process loads and tool deformation during the plunge phase of the friction stir welding process. Two materials, H-13 tool steel and pure tungsten, were used to fabricate friction stir welding tools that were plunged into each of the thermohydrogen processed titanium sheets. Tool wear was characterized and variations in machine loads were quantified for each tool material and weld metal combination. Thermohydrogen processing was shown to beneficially lower plunge forces and stabilize machine torques at specific hydrogen concentrations. The resulting effects of hydrogen addition to titanium metal undergoing the friction stir welding process are compared with modifications in titanium properties documented in modern literature. Such comparative analysis is used to explain the variance in resulting process loads as a function of the initial hydrogen concentration of the titanium.

  4. Dissimilar friction welding of titanium alloys to alloy 718

    SciTech Connect

    Kuo, M.; Albright, C.E.; Baeslack, W.A. III

    1994-12-31

    The design of advanced, high-performance gas-turbine engines will require the utilization of elevated-temperature titanium-based materials, including conventional alloys, titanium aluminides, and titanium metal-matrix composites. The most efficient utilization of these materials in the engine compressor section would be achieved by directly joining these materials to existing nickel-base superalloys, such as Alloy 718. To date, the dissimilar welding of titanium alloys to nickel-based alloys has not been common practice because intermetallic compounds form in the weld and cause embrittlement. Special welding techniques must be developed to inhibit this compound formation and to provide high strength welds. In this investigation, a friction welding process was developed for joining titanium alloys (Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V) to nickel-based superalloy Alloy 718. An interlayer system comprised of copper and niobium sheet layers was employed as a diffusion barrier and weld deformation enhancer. A postweld heat treatment (PWHT, 700{degrees}C for 20 min in vacuum) under axial pressure (Ksi) was used to improve the joint strength consistency. The following conclusions can be drawn from this investigation: (1) A friction welding technique has been developed for joining titanium alloys (Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V) to Alloy 718 using an interlayer system of niobium and copper. Joint strengths averaging approximately 50 Ksi were achieved. (2) Deformation was concentrated in the interlayers, especially the copper interlayer, during friction welding. Increased reduction in length (RIL) during friction welding resulted in a decrease in the interlayer thicknesses. (3) The EDS results showed that the niobium and copper interlayers prevent interdiffusion between the two parent metals, producing formation of detrimental phases.

  5. Alloying Elements Transition Into the Weld Metal When Using an Inventor Power Source

    NASA Astrophysics Data System (ADS)

    Mamadaliev, R. A.; Kuskov, V. N.; Popova, A. A.; Valuev, D. V.

    2016-04-01

    The temperature distribution over the surface of the welded 12Kh18N10T steel plates using the inventor power source ARC-200 has been calculated. In order to imitate multipass welding when conducting the thermal analysis the initial temperature was changed from 298K up to 798K in 100K increments. It has been determined that alloying elements transition into the weld metal depends on temperature. Using an inventor power source facilitates a uniform distribution of alloying elements along the length and height of the weld seam.

  6. Welding and performance of advanced high temperature alloys

    SciTech Connect

    Prager, M.; Masuyama, F.

    1995-12-31

    The last decade has witnessed the development of many new alloys for elevated temperature service and recognition of a large number of them in the form of allowable stresses by the ASME Boiler and Pressure Vessel Code. These alloys offer considerable advantages in terms of higher tensile and stress rupture strengths, lower thermal stresses, superior corrosion resistance and, in one case, weldability. The improvements are obtained through additions of tungsten, vanadium, columbium, copper, nitrogen and other elements which significantly affect microstructure and weldability. The paper will discuss where introduction of these advanced materials may be warranted, the properties to be expected in comparison to conventional alloys, PWHT requirements and concerns regarding weld failure modes. Higher performance in operation of power plants is achieved by use of tungsten alloyed advanced 9--12%Cr ferritic steels, NF616 (9Cr-0.5 Mo-1.8W-V-Nb) and HCM12A (12Cr-0.4Mo-2W-1 Cu-V-Nb), which exhibit over 30% higher creep strength than T91/P91 (Mod. 9Cr-1 Mo) at 600 C. Thick-walled and large-diameter pipes of NF616 and HCM12A were subjected to fabrication tests such as joint welding and induction bending, and it was shown that the properties of the fabricated parts were satisfactory for the practical application of those steels. HCM2S, a newly developed low alloy steel (0.06C-2.25Cr-1.6W-0.25V0.05Nb) is approximately 1.8 times stronger than conventional T22 (2.25Cr-1 Mo) at around 600 C. The weldability of this low carbon content steel is much improved, as it needs no pre-weld nor postweld heat treatment. HCM2S was installed in a large capacity utility boiler.

  7. The Structure and Mechanical Properties of Bridge Steel Weldings With Glass-Steel Liners

    NASA Astrophysics Data System (ADS)

    Muzalev, V. N.; Semukhin, B. S.; Danilov, V. I.

    2016-04-01

    A new technology is developed for welding multi-span bridge constructions. The mechanical properties and structure of the low-carbon bridge steel welds have been studied. The welding parameters and application of steel-glass liners provide for long-term service of steel constructions in conformity with the welding industry specifications.

  8. Friction Pull Plug Welding in Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Brooke, Shane A.; Bradford, Vann

    2012-01-01

    NASA's Marshall Space Flight Center (MSFC) has recently invested much time and effort into the process development of Friction Pull Plug Welding (FPPW). FPPW, is a welding process similar to Friction Push Plug Welding in that, there is a small rotating part (plug) being spun and simultaneously pulled (forged) into a larger part. These two processes differ, in that push plug welding requires an internal reaction support, while pull plug welding reacts to the load externally. FPPW was originally conceived as a post proof repair technique for the Space Shuttle fs External Tank. FPPW was easily selected as the primary weld process used to close out the termination hole on the Constellation Program's ARES I Upper Stage circumferential Self-Reacting Friction Stir Welds (SR-FSW). The versatility of FPPW allows it to also be used as a repair technique for both SR-FSW and Conventional Friction Stir Welds. To date, all MSFC led development has been concentrated on aluminum alloys (2195, 2219, and 2014). Much work has been done to fully understand and characterize the process's limitations. A heavy emphasis has been spent on plug design, to match the various weldland thicknesses and alloy combinations. This presentation will summarize these development efforts including weld parameter development, process control, parameter sensitivity studies, plug repair techniques, material properties including tensile, fracture and failure analysis.

  9. Laser Peening of Alloy 22 Welds

    SciTech Connect

    Stevens, D W; Hackel, L A; Lingenfelter, A C

    2002-10-03

    Stress corrosion cracking (SCC) of near-surface Alloy 22 metal can be propagated by yield-point levels (45 ksi) of residual weld tensile stresses. This is a serious concern for welds in the Alloy 22 canister employed in the Yucca Mountain Project (YMP) Waste Package, particularly in closure welds that cannot be stress relieved by conventional heat treating. This work shows that compressive shock waves, driven into a weldment by laser peening, replaces its detrimental tensile stresses of 30-80 ksi with compressive stresses of 2-25 ksi or better that retard SCC. This benefit occurs in the top 1.5 mm (or more) of the material without appreciable heating. It was also found that quenching after solution annealing and shot peening during production of Alloy 22 plate imparts compressive stresses of 35-105 ksi near the surface, a very large buffer against SCC. This means that if seam-welded hollow canisters likewise gain compressive stresses upon post-weld annealing and quenching, and if closure welds are laser peened, all surfaces of the canister would be under compression, thereby precluding SCC of the Alloy 22 canister. Laser peening may plastically deform as much as the top 10% of the metal (about 2 mm out of the 25-mm plate thickness), thereby changing the rate of general corrosion of waste package outer barrier. Long-term corrosion tests of laser peened Alloy 22 welds should be conducted. Present results show that laser peening, currently under development at LLNL using high-energy lasers, induces compressive residual stress on the near surface of the weld. This laser peening process is showing significant retardation of SCC and should be further characterized and assessed to preclude SCC in Alloy 22 canisters.

  10. Creep Strength of Dissimilar Welded Joints Using High B-9Cr Steel for Advanced USC Boiler

    NASA Astrophysics Data System (ADS)

    Tabuchi, Masaaki; Hongo, Hiromichi; Abe, Fujio

    2014-10-01

    The commercialization of a 973 K (700 °C) class pulverized coal power system, advanced ultra-supercritical (A-USC) pressure power generation, is the target of an ongoing research project initiated in Japan in 2008. In the A-USC boiler, Ni or Ni-Fe base alloys are used for high-temperature parts at 923 K to 973 K (650 °C to 700 °C), and advanced high-Cr ferritic steels are planned to be used at temperatures lower than 923 K (650 °C). In the dissimilar welds between Ni base alloys and high-Cr ferritic steels, Type IV failure in the heat-affected zone (HAZ) is a concern. Thus, the high B-9Cr steel developed at the National Institute for Materials Science, which has improved creep strength in weldments, is a candidate material for the Japanese A-USC boiler. In the present study, creep tests were conducted on the dissimilar welded joints between Ni base alloys and high B-9Cr steels. Microstructures and creep damage in the dissimilar welded joints were investigated. In the HAZ of the high B-9Cr steels, fine-grained microstructures were not formed and the grain size of the base metal was retained. Consequently, the creep rupture life of the dissimilar welded joints using high B-9Cr steel was 5 to 10 times longer than that of the conventional 9Cr steel welded joints at 923 K (650 °C).

  11. Embrittlement of austenitic stainless steel welds

    SciTech Connect

    David, S.A.; Vitek, J.M.

    1997-12-31

    The microstructure of type-308 austenitic stainless steel weld metal containing {gamma} and {delta} and ferrite is shown. Typical composition of the weld metal is Cr-20.2, Ni-9.4, Mn-1.7, Si-0.5, C-0.05, N-0.06 and balance Fe (in wt %). Exposure of austenitic stainless steel welds to elevated temperatures can lead to extensive changes in the microstructural features of the weld metal. On exposure to elevated temperatures over a long period of time, a continuous network of M{sub 23}C{sub 6} carbide forms at the austenite/ferrite interface. Upon aging at temperatures between 550--850 C, ferrite in the weld has been found to be unstable and transforms to sigma phase. These changes have been found to influence mechanical behavior of the weld metal, in particular the creep-rupture properties. For aging temperatures below 550 C the ferrite decomposes spinodally into {alpha} and {alpha}{prime} phases. In addition, precipitation of G-phase occurs within the decomposed ferrite. These transformations at temperatures below 550 C lead to embrittlement of the weld metal as revealed by the Charpy impact properties.

  12. High strength, tough alloy steel

    DOEpatents

    Thomas, Gareth; Rao, Bangaru V. N.

    1979-01-01

    A high strength, tough alloy steel is formed by heating the steel to a temperature in the austenite range (1000.degree.-1100.degree. C.) to form a homogeneous austenite phase and then cooling the steel to form a microstructure of uniformly dispersed dislocated martensite separated by continuous thin boundary films of stabilized retained austenite. The steel includes 0.2-0.35 weight % carbon, at least 1% and preferably 3-4.5% chromium, and at least one other substitutional alloying element, preferably manganese or nickel. The austenite film is stable to subsequent heat treatment as by tempering (below 300.degree. C.) and reforms to a stable film after austenite grain refinement.

  13. Friction Pull Plug Welding in Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Brooke, Shane A.; Bradford, Vann; Burkholder, Jonathon

    2011-01-01

    NASA fs Marshall Space Flight Center (MSFC) has recently invested much time and effort into the process development of Friction Pull Plug Welding (FPPW). FPPW, is a welding process similar to Friction Push Plug Welding in that, there is a small rotating part (plug) being spun and simultaneously pulled (forged) into a larger part. These two processes differ, in that push plug welding requires an internal reaction support, while pull plug welding reacts to the load externally. FPPW was originally conceived as a post proof repair technique for External Tank. FPPW was easily selected as the primary process used to close out the termination hole on the Constellation Program fs ARES I Upper Stage circumferential Self ] Reacting Friction Stir Welds (SR ]FSW). The versatility of FPPW allows it to also be used as a repair technique for both SR ]FSW and Conventional Friction Stir Welds. To date, all MSFC led development has been concentrated on aluminum alloys (2195, 2219, and 2014). Much work has been done to fully understand and characterize the process fs limitations. A heavy emphasis has been spent on plug design, to match the various weldland thicknesses and alloy combinations. This presentation will summarize these development efforts including weld parameter development, process control, parameter sensitivity studies, plug repair techniques, material properties including tensile, fracture and failure analysis.

  14. Qualification of welded super 13%Cr martensitic stainless steels for the Sgard field

    SciTech Connect

    Enerhaug, J.; Kvaale, P.E.; Bjordal, M.; Drugli, J.M.; Rogne, T.

    1999-11-01

    A test program was conducted to qualify welded super 13%Cr (S13%Cr) stainless steel for the Asgard Field, a mildly sour service. The test program involved girth welding, optimization of post weld heat treatment (PWHT) cycles, assessment of mechanical properties, examination of low cycle fatigue testing, and different corrosion testing and evaluation of S13%Cr steels from three different steel mills. The alloy with 0.015%C max, 11.9%Cr min, 2.4%Mo min and 6.O%Ni min, has been qualified for use as flowline material in the actual field. The results show acceptable weldability and corrosion properties. Post weld heat treatment (PWHT) of the welds improved the resistance against sulfide stress corrosion cracking.

  15. An Atom-Probe Tomographic Study of Arc Welds in a Multi-Component High-Strength Low-Alloy Steel

    NASA Astrophysics Data System (ADS)

    Hunter, Allen H.; Farren, Jeffrey D.; DuPont, John N.; Seidman, David N.

    2013-04-01

    An experimental plate steel with the composition Fe-1.39Cu-2.7Ni-0.58Al-0.48Mn-0.48Si-0.065Nb-0.05C (wt pct) or alternatively Fe-1.43Cu-2.61Ni-1.21Al-0.48Mn-0.98Si-0.039Nb-0.23C at. pct has been recently produced at Northwestern University for use in Naval hull and deck applications—it is designated NUCu-140. To understand the microstructural changes occurring in NUCu-140 steel after gas-metal arc welding (GMAW), a detailed study of the heat-affected and fusion zones was performed throughout the weld cross section using microhardness, metallographic, chemical, and atom-probe tomographic analyses. Local-electrode atom-probe (LEAP) tomography was employed to measure the morphology and compositions of Cu-rich precipitates from each region. The mean radius, number density, volume fraction, and compositions of the precipitates, as well as the interfacial concentration profiles, are measured. The Cu precipitates dissolve partially from the heat-affected zone (HAZ) thermal cycle, and freshly formed sub-nanometer radius Cu-rich precipitates nucleate in both the HAZ and fusion zone (FZ) during cooling; however, the precipitation of Cu during cooling in the HAZ and FZ is not sufficient to restore the lost strength. The precipitation in the FZ is reduced compared to the HAZ due to a mismatched Cu composition of the weld. Multi-pass welding is suggested to restore strength in the GMAW sample by promoting Cu precipitate nucleation and growth in the HAZ and FZ.

  16. Differences between Laser and Arc Welding of HSS Steels

    NASA Astrophysics Data System (ADS)

    Němeček, Stanislav; Mužík, Tomáš; Míšek, Michal

    Conventional welding processes often fail to provide adequate joints in high strength steels with multiphase microstructures. One of the promising techniques is laser beam welding: working without filler metal and with sufficient capacity for automotive and transportation industry (where the amount of AHSS steels increases each year, as well as the length of laser welds). The paper compares microstructures and properties of HSS (high strength steel) joints made by MAG (Metal Active Gas) and laser welding. The effects of main welding parameters (heat input, welding speed and others) are studied on multiphase TRIP 900 steel tubes and martensitic sheets DOCOL 1200, advanced materials for seat frames and other automotive components. Whereas the strength of conventional welds is significantly impaired, laser welding leaves strength of the base material nearly unaffected. As the nature of fracture changes during loading and depending on the welding method, failure mechanisms upon cross tension tests have been studied as well.

  17. Braze alloy spreading on steel

    NASA Technical Reports Server (NTRS)

    Siewert, T. A.; Heine, R. W.; Lagally, M. G.

    1978-01-01

    Scanning electron microscopy (SEM) and Auger electron microscopy (AEM) were employed to observe elemental surface decomposition resulting from the brazing of a copper-treated steel. Two types of steel were used for the study, stainless steel (treated with a eutectic silver-copper alloy), and low-carbon steel (treated with pure copper). Attention is given to oxygen partial pressure during the processes; a low enough pressure (8 x 10 to the -5th torr) was found to totally inhibit the spreading of the filler material at a fixed heating cycle. With both types of steel, copper treatment enhanced even spreading at a decreased temperature.

  18. Solidification and solid state transformations of austenitic stainless steel welds

    SciTech Connect

    Brooks, J A; Williams, J C; Thompson, A W

    1982-05-01

    The microstructure of austenitic stainless steel welds can contain a large variety of ferrite morphologies. It was originally thought that many of these morphologies were direct products of solidification. Subsequently, detailed work on castings suggested the structures can solidify either as ferrite or austenite. However, when solidification occurs by ferrite, a large fraction of the ferrite transforms to austenite during cooling via a diffusion controlled transformation. It was also shown by Arata et al that welds in a 304L alloy solidified 70-80% as primary ferrite, a large fraction of which also transformed to austenite upon cooling. More recently it was suggested that the cooling rates in welds were sufficiently high that diffusionless transformations were responsible for several commonly observed ferrite morphologies. However, other workers have suggested that even in welds, delta ..-->.. ..gamma.. transformations are diffusion controlled. A variety of ferrite morphologies have more recently been characterized by Moisio and coworkers and by David. The purpose of this paper is to provide further understanding of the evaluation of the various weld microstructures which are related to both the solidification behavior and the subsequent solid state transformations. To accomplish this, both TEM and STEM (Scanning Transmission Electron Microscopy) techniques were employed.

  19. Effects of superplastic deformation on the diffusion welding of SuperDux 65 stainless steel

    SciTech Connect

    Yeh, M.S.; Tseng, Y.H.; Chuang, T.H.

    1999-09-01

    The SuperDux 65 stainless steel diffusion welded in a nonsuperplastic state (880 C, 60 min) required greater pressure, compared to aluminum and titanium alloys, to create a contact area at the weld interface, which will increase the atomic diffusion paths. However, an unsatisfactory weld strength of 45.3 MPa was obtained under the applied pressure of 7 MPa. This alloy deformed easily at its superplastic temperature of 970 C, resulting in a tight contact surface. The higher welding temperature was also beneficial for atomic diffusion. Both effects were advantageous for diffusion welding, while the joined workpieces macroscopically deformed markedly. In this study, a two-stage diffusion welding method was proposed. The specimens were diffusion welded in a nonsuperplastic (or superplastic) state for a short time and then further diffusion welded at superplastic (or nonsuperplastic) temperatures for a longer heating period. It was found that the welding strength could be improved drastically using such a two-stage process. The contributions of superplastic deformation on the diffusion welding of this alloy during the two-stage process were clarified.

  20. Fusion welding of advanced borated stainless steels. Final report: CRADA No. CR1042

    SciTech Connect

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

    1994-02-01

    This work addressed two major areas concerning joining of advanced borated stainless steels. These areas included the development of a understanding of the physical metallurgy of borated stainless steels and the development of welding processes and post-weld heat treatments for these alloys. Differential thermal analysis experiments were conducted on ten heats of borated stainless steel to determine the transformation temperatures and melting behavior of the alloys. On-heating solidus temperatures were measured for all of the alloys and were used to define the temperatures associated with the fusion line during welding. Isothermal heat treatments designed to evaluate the effects of elevated temperature exposures on the toughness of the borated grades were conducted. These tests were used to determine if significant changes in the microstructure or mechanical properties of weld heat-affected zones (HAZ) occur. Specifically, the tests addressed the solid-state region of the HAZ. The test matrix included a variety of alloy compositions and thermal exposures at temperatures near the on-heating solidus (as determined by the DTA experiments). Welding experiments designed to assess the mechanical properties and microstructure of gas-tungsten arc and electron beam welds were conducted.

  1. Stress Engineering of Multi-pass Welds of Structural Steel to Enhance Structural Integrity

    NASA Astrophysics Data System (ADS)

    Ganguly, Supriyo; Sule, Jibrin; Yakubu, Mustapha Y.

    2016-05-01

    In multi-pass welding, the weld metal and the associated heat-affected zone are subjected to repeated thermal cycling from successive deposition of filler metals. The thermal straining results into multi-mode deformation of the weld metal which causes a variably distributed residual stress field through the thickness and across the weld of a multi-pass weldment. In addition to this, the as-welded fusion zone microstructure shows dendritic formation of grains and segregation of alloying element. This may result in formation of micro-corrosion cells and the problem would aggravate in case of highly alloyed materials. Local mechanical tensioning is an effective way of elimination of the weld tensile residual stress. It has been shown that application of cold rolling is capable not only of removing the residual stress, but depending on its magnitude it may also form beneficial compressive stress state. Multi-pass structural steel welds used as structural alloy in general engineering and structural applications. Such alloys are subjected to severe in-service degradation mechanisms e.g., corrosion and stress corrosion cracking. Welds and the locked-in residual stress in the welded area often initiate the defect which finally results in failure. In the present study, a multi-pass structural steel weld metal was first subjected to post-weld cold rolling which was followed by controlled heating by a fiber laser. Cold straining resulted in redistribution of the internal stress through the thickness and controlled laser processing helps in reforming of the grain structure. However, even with controlled laser, processing the residual stress is reinstated. Therefore, a strategy has been adopted to roll the metal post-laser processing so as to obtain a complete stress-free and recrystallized microstructure.

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

    SciTech Connect

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

    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. The 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.

  3. STRESS CORROSION CRACK GROWTH RESPONSE FOR ALLOY 152/52 DISSIMILAR METAL WELDS IN PWR PRIMARY WATER

    SciTech Connect

    Toloczko, Mychailo B.; Olszta, Matthew J.; Overman, Nicole R.; Bruemmer, Stephen M.

    2015-08-15

    As part of ongoing research into primary water stress corrosion cracking (PWSCC) susceptibility of alloy 690 and its welds, SCC tests have been conducted on alloy 152/52 dissimilar metal (DM) welds with cracks positioned with the goal to assess weld dilution and fusion line effects on SCC susceptibility. No increased crack growth rate was found when evaluating a 20% Cr dilution zone in alloy 152M joined to carbon steel (CS) that had not undergone a post-weld heat treatment (PWHT). However, high SCC crack growth rates were observed when the crack reached the fusion line of that material where it propagated both on the fusion line and in the heat affected zone (HAZ) of the carbon steel. Crack surface and crack profile examinations of the specimen revealed that cracking in the weld region was transgranular (TG) with weld grain boundaries not aligned with the geometric crack growth plane of the specimen. The application of a typical pressure vessel PWHT on a second set of alloy 152/52 – carbon steel DM weld specimens was found to eliminate the high SCC susceptibility in the fusion line and carbon steel HAZ regions. PWSCC tests were also performed on alloy 152-304SS DM weld specimens. Constant K crack growth rates did not exceed 5x10-9 mm/s in this material with post-test examinations revealing cracking primarily on the fusion line and slightly into the 304SS HAZ.

  4. Linear Anomaly in Welded 2219-T87 Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Jemian, Wartan A.

    1987-01-01

    Study of causes and significance of two types of linear anomalies sometimes appearing in radiographs of welds described in preliminary report. Manifested as light or dark linear features parallel to weld line in radiograph of weld. Contains diagrams and descriptions of phenomena occurring during welding process. Includes microdensitometer traces from x-radiographs of actual welds and from computer simulations based calculation of x-ray transmission through assumed weld structures. Concludes anomalies not unique to 2219-T87 aluminum alloy.

  5. Material Flow during Friction Stir Welding of HSLA 65 Steel

    NASA Astrophysics Data System (ADS)

    Young, John; Field, David; Nelson, Tracy

    2013-07-01

    Material flow during friction stir welding of HSLA-65 steel was investigated by crystallographic texture analysis. During the welding process, the steel deforms primarily by local shear deformation in the austenite phase and then transforms upon cooling. Texture data from three weld specimens were compared to theoretical textures calculated using ideal Euler angles for shear in face centered cubic (FCC) structures transformed by the Kurdjumov-Sacks (KS) relationship. These theoretical textures show similarities to the experimental textures. Texture data from the weld specimens revealed a rotation of the shear direction corresponding to the tangent of the weld tool on both the area directly under the weld tool shoulder and weld cross sections. In addition, texture data showed that while the shear plane of the area under the weld tool shoulder remained constant, the shear plane of the weld cross sections is influenced by the weld tool pin.

  6. Filler metal alloy for welding cast nickel aluminide alloys

    DOEpatents

    Santella, Michael L.; Sikka, Vinod K.

    1998-01-01

    A filler metal alloy used as a filler for welding east nickel aluminide alloys contains from about 15 to about 17 wt. % chromium, from about 4 to about 5 wt. % aluminum, equal to or less than about 1.5 wt. % molybdenum, from about 1 to about 4.5 wt. % zirconium, equal to or less than about 0.01 wt. % yttrium, equal to or less than about 0.01 wt. % boron and the balance nickel. The filler metal alloy is made by melting and casting techniques such as are melting the components of the filler metal alloy and east in copper chill molds.

  7. Filler metal alloy for welding cast nickel aluminide alloys

    DOEpatents

    Santella, M.L.; Sikka, V.K.

    1998-03-10

    A filler metal alloy used as a filler for welding cast nickel aluminide alloys contains from about 15 to about 17 wt. % chromium, from about 4 to about 5 wt. % aluminum, equal to or less than about 1.5 wt. % molybdenum, from about 1 to about 4.5 wt. % zirconium, equal to or less than about 0.01 wt. % yttrium, equal to or less than about 0.01 wt. % boron and the balance nickel. The filler metal alloy is made by melting and casting techniques such as are melting the components of the filler metal alloy and cast in copper chill molds. 3 figs.

  8. Intermetallic alloy welding wires and method for fabricating the same

    DOEpatents

    Santella, M.L.; Sikka, V.K.

    1996-06-11

    Welding wires for welding together intermetallic alloys of nickel aluminides, nickel-iron aluminides, iron aluminides, or titanium aluminides, and preferably including additional alloying constituents are fabricated as two-component, clad structures in which one component contains the primary alloying constituent(s) except for aluminum and the other component contains the aluminum constituent. This two-component approach for fabricating the welding wire overcomes the difficulties associated with mechanically forming welding wires from intermetallic alloys which possess high strength and limited ductilities at elevated temperatures normally employed in conventional metal working processes. The composition of the clad welding wires is readily tailored so that the welding wire composition when melted will form an alloy defined by the weld deposit which substantially corresponds to the composition of the intermetallic alloy being joined. 4 figs.

  9. Intermetallic alloy welding wires and method for fabricating the same

    DOEpatents

    Santella, Michael L.; Sikka, Vinod K.

    1996-01-01

    Welding wires for welding together intermetallic alloys of nickel aluminides, nickel-iron aluminides, iron aluminides, or titanium aluminides, and preferably including additional alloying constituents are fabricated as two-component, clad structures in which one component contains the primary alloying constituent(s) except for aluminum and the other component contains the aluminum constituent. This two-component approach for fabricating the welding wire overcomes the difficulties associated with mechanically forming welding wires from intermetallic alloys which possess high strength and limited ductilities at elevated temperatures normally employed in conventional metal working processes. The composition of the clad welding wires is readily tailored so that the welding wire composition when melted will form an alloy defined by the weld deposit which substantially corresponds to the composition of the intermetallic alloy being joined.

  10. The filler powders laser welding of ODS ferritic steels

    NASA Astrophysics Data System (ADS)

    Liang, Shenyong; Lei, Yucheng; Zhu, Qiang

    2015-01-01

    Laser welding was performed on Oxide Dispersion Strengthened (ODS) ferritic steel with the self-designed filler powders. The filler powders were added to weld metal to produce nano-particles (Y-M-O and TiC), submicron particles (Y-M-O) and dislocation rings. The generated particles were evenly distributed in the weld metal and their forming mechanism and behavior were analyzed. The results of the tests showed that the nano-particles, submicron particles and dislocation rings were able to improve the micro-hardness and tensile strength of welded joint, and the filler powders laser welding was an effective welding method of ODS ferritic steel.

  11. The effect of iron dilution on strength of nickel/steel and Monel/steel welds

    SciTech Connect

    Fout, S.L.; Wamsley, S.D.

    1983-03-28

    The weld strength, as a function of iron content, for nickel/steel and Monel/steel welds was determined. Samples were prepared using a Gas Metal Arc (GMAW) automatic process to weld steel plate together with nickel or Monel to produce a range of iron contents typical of weld compositions. Tensile specimens of each iron content were tested to obtain strength and ductility measurements for that weld composition. Data indicate that at iron contents of less than 20% iron in a nickel/steel weld, the weld fails at the weld interface, due to a lack of fusion. Between 20% and 35% iron, the highest iron dilution that could be achieved in a nickel weld, the welds were stronger than the steel base metal. This indicates that a minimum amount of iron dilution (20%) is necessary for good fusion and optimum strength. On the other hand for Monel/steel welds, test results showed that the welds had good strength and integrity between 10% and 27% iron in the weld. Above 35% iron, the welds have less strength and are more brittle. The 35% iron content also corresponds to the iron dilution in Monel welds that has been shown to produce an increase in corrosion rate. This indicates that the iron dilution in Monel welds should be kept below 35% iron to maximize both the strength and corrosion resistance. 2 refs., 6 figs., 3 tabs.

  12. Electron microscopy and microanalysis of steel weld joints after long time exposures at high temperatures

    NASA Astrophysics Data System (ADS)

    Jandová, D.; Kasl, J.; Rek, A.

    2010-02-01

    The structural changes of three trial weld joints of creep resistant modified 9Cr-1Mo steels and low alloyed chromium steel after post-weld heat treatment and long-term creep tests were investigated. Smooth cross-weld specimens ruptured in different zones of the weld joints as a result of different structural changes taking place during creep exposures. The microstructure of the weld joint is heterogeneous and consequently microstructural development can be different in the weld metal, the heat affected zone, and the base material. Precipitation reactions, nucleation and growth of some particles and dissolution of others, affect the strengthening of the matrix, recovery at high temperatures, and the resulting creep resistance. Therefore, a detailed study of secondary phase's development in individual zones of weld joints can elucidate mechanism of cracks propagation in specific regions and the causes of creep failure. Type I and II fractures in the weld metal and Type IV fractures in the fine prior austenite grain heat affected zones occurred after creep tests at temperatures ranging from 525 to 625 °C and under stresses from 40 to 240 MPa. An extended metallographic study of the weld joints was carried out using scanning and transmission electron microscopy, energy-dispersive and wave-dispersive X-ray microanalysis. Carbon extraction replicas and thin foils were prepared from individual weld joint regions and quantitative evaluation of dislocation substructure and particles of secondary phases has been performed.

  13. Corrosion fracture resistance of welded joints in 16GMYuCh steel

    SciTech Connect

    Steklov, O.I.; Efimenko, L.A.; Khakimov, A.M.; Paul', A.I.; Pushkina, O.A.

    1986-01-01

    This paper studies the effect of combined welding of thick-wall gas and oil chemical equipment consisting of welding the weld root by automatic submerged-arc welding and electrosag welding (ESW) with the control of thermal cycles (CWC) of the main joint, on the corrosion resistance of welded joints in low-alloy normalized 16GMYuCh steel 50 mm thick. The chemical composition of the steel, % 0.16 C; 1.05 Mn; 0.25 Si; 0.42 Mo; 0.14 Ni; 0.1 Cu; 0.11 Cr; 0.049 Al; 0.032 S; 0.019 P. The authors determined the effect of cooling rate in the temperature range of diffusion transformation of austenite on the corrosion resistance of the weld zone. Attention was then given to the corrosion resistance of the welded joints produced by conventional ESW welding and ESW with CWC. The investigations show that the corrosion resistance of the parent metal is lower than that of the welded joints.

  14. Friction Stir Welding of Steel: Heat Input, Microstructure, and Mechanical Property Co-relation

    NASA Astrophysics Data System (ADS)

    Husain, Md. M.; Sarkar, R.; Pal, T. K.; Prabhu, N.; Ghosh, M.

    2015-09-01

    Friction stir welding was performed to join carbon steel plates at tool rotational rate of 800-1400 rpm. Microstructure and microhardness of welded specimens were evaluated across weld centerline. Torque base index, peak temperature, cooling rate, strain, strain rate, volumetric material flow rate, and width of extruded zone at weld nugget were calculated. Peak temperature at weld nugget was ~1300-1360 K. At this temperature, ferrite transformed to austenite during welding. Austenite was decomposed in to ferrite and bainite at cooling rate of ~4-7.5 K/s. The presence of bainite was endorsed by increment in microhardness with respect to base material. Ferrite grain size at weld nugget was finer in comparison to as-received alloy. With the increment in tool rotational rate strain, strain rate, total heat input, and peak temperature at weld nugget were increased. High temperature at weld nugget promoted increment in ferrite grain size and reduction in area fraction of bainite. Heat-affected zone also experienced phase transformation and exhibited enhancement in ferrite grain size in comparison to base alloy at all welding parameters with marginal drop in microhardness. Maximum joint strength was obtained at the tool rotational rate of 1000 rpm. Increment in tool rational rate reduced the joint efficiency owing to increment in ferrite grain size and reduction in pearlite area fraction at heat-affected zone.

  15. Aluminum alloy welding and stress-corrosion testing. Final report

    SciTech Connect

    Gates, W.G.; Jimenez, E.

    1981-04-01

    The weldability, strength, and corrosion resistance of four 5XXX aluminum alloys electron beam welded to 6061-T6 aluminum alloy without a filler metal were evaluated. Adding filler metal raises weld energy requirements and makes the process more difficult to control. In this study, instead of using a filler metal, a high-magnesium 5XXX alloy was welded to the 6061 alloy. The four 5XXX alloys used (5456-H321, 5052-H34, 5086-H323, and 5083-H32) were selected for their high magnesium content which reduces weld crack sensitivity.

  16. Welding and Weldability of Thorium-Doped Iridium Alloys

    SciTech Connect

    David, S.A.; Ohriner, E.K.; King, J.F.

    2000-03-12

    Ir-0.3%W alloys doped with thorium are currently used as post-impact containment material for radioactive fuel in thermoelectric generators that provide stable electrical power for a variety of outer planetary space exploration missions. Welding and weldability of a series of alloys was investigated using arc and laser welding processes. Some of these alloys are prone to severe hot-cracking during welding. Weldability of these alloys was characterized using Sigmajig weldability test. Hot-cracking is influenced to a great extent by the fusion zone microstructure and composition. Thorium content and welding atmosphere were found to be very critical. The weld cracking behavior in these alloys can be controlled by modifying the fusion zone microstructure. Fusion zone microstructure was found to be controlled by welding process, process parameters, and the weld pool shape.

  17. Improvements of welding characteristics of aluminum alloys with YAG laser and TIG arc hybrid system

    NASA Astrophysics Data System (ADS)

    Fujinaga, Shigeki; Ohashi, Ryoji; Katayama, Seiji; Matsunawa, Akira

    2003-03-01

    In high power YAG laser welding of steels, a rectangularly modulated beam with high peak power is usually used to get deep penetration. On the other hand, many spatters and solidification cracks are generated when some aluminum alloys are welded with a rectangularly modulated beam because of its high heat conductivity, high reflectivity, low surface tension, large contraction, wide solidification temperature range, etc. Therefore, a properly modulated beam or a continuous beam is usually used in aluminum alloy welding, although the penetration depth is shallow. In this research, sinusoidal wave or rectangularly modulated wave of YAG laser combined with TIG arc was tried to improve the weldability of A6061 aluminum alloy. As a result, when TIG arc was superimposed behind the YAG laser beam, deeply penetrated weld beads with good surface appearances were produced without spatter losses and cracks.

  18. Ferrite morphology and variations in ferrite content in austenitic stainless steel welds

    SciTech Connect

    David, S.A.; Hanzelka, S.E.; Haltom, C.P.

    1981-07-01

    Four distinct ferrite morphologies have been identified in type 308 stainless steel multipass welds: vermicular, lacy, acicular, and globular. The first three ferrite types are related to transformations following solidification and the fourth is related to the shape instability of the residual ferrite. An earlier study showed that most of the ferrite observed in austenitic stainless steel welds contaning a duplex structure may be identified as residual primary ferrite resulting from incomplete delta ..-->.. ..gamma.. transformation during solidification and/or residual ferrite after Widmanstaetten austenite precipitation in primary ferrite. These modes of ferrite formation can be used to explain observed ferrite morphologies in austenitic stainless steel welds. Variations in ferrite content within the weld were related to weld metal composition, ferrite morphology, and dissolution of ferrite resulting from thermal cycles during subsequent weld passes. An investigation of the type 308 stainless steel filler metal solidified over cooling rates ranging from 7 to 1600/sup 0/C/s showed that the cooling rate of the weld metal within the freezing range of the alloy affects the amount of ferrite in the microstructure very litte. However, the scale of the solidification substructure associated with various solidification rates may influence the ferrite dissolution kinetics.

  19. Ferrite morphology and variations in ferrite content in austenitic stainless steel welds

    SciTech Connect

    David, S.A.

    1981-04-01

    Four distinct ferrite morphologies have been identified in Type 308 stainless steel multipass welds: vermicular, lacy, acicular, and globular. The first three ferrite types are related to transformations following solidfication and the fourth is related to the shape instability of the residual ferrite. An earlier study showed that most of the ferrite observed in austenitic stainless steel welds containing a duplex structure may be identified as residual primary ferrite resulting from incomplete delta ..-->.. ..gamma.. transformation during solidification and/or residual ferrite after Widmanstatten austenite precipitation in primary ferrite. These modes of ferrite formation can be used to explain observed ferrite morphologies in austenitic stainless steel welds. Variations in ferrite content within the weld were also related to weld metal composition, ferrite morphology, and dissolution of ferrite resulting from thermal cycles during subsequent weld passes. An investigation of the Type 308 stainless steel filler metal solidified over cooling rates ranging from 7 to 1600/sup 0/C/s (44.6 to 2912/sup 0/F/s) showed that the cooling rate of the weld metal within the freezing range of the alloy affects the amount of ferrite in the microstructure very little. However, the scale of the solidification substructure associated with various solidification rates may influence the ferrite dissolution kinetics.

  20. 49 CFR 178.61 - Specification 4BW welded steel cylinders with electric-arc welded longitudinal seam.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Specification 4BW welded steel cylinders with... steel cylinders with electric-arc welded longitudinal seam. (a) Type, size and service pressure. A DOT 4BW cylinder is a welded type steel cylinder with a longitudinal electric-arc welded seam, a...

  1. 49 CFR 178.61 - Specification 4BW welded steel cylinders with electric-arc welded longitudinal seam.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Specification 4BW welded steel cylinders with... steel cylinders with electric-arc welded longitudinal seam. (a) Type, size and service pressure. A DOT 4BW cylinder is a welded type steel cylinder with a longitudinal electric-arc welded seam, a...

  2. 49 CFR 178.61 - Specification 4BW welded steel cylinders with electric-arc welded longitudinal seam.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Specification 4BW welded steel cylinders with... steel cylinders with electric-arc welded longitudinal seam. (a) Type, size and service pressure. A DOT 4BW cylinder is a welded type steel cylinder with a longitudinal electric-arc welded seam, a...

  3. 49 CFR 178.61 - Specification 4BW welded steel cylinders with electric-arc welded longitudinal seam.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Specification 4BW welded steel cylinders with... steel cylinders with electric-arc welded longitudinal seam. (a) Type, size and service pressure. A DOT 4BW cylinder is a welded type steel cylinder with a longitudinal electric-arc welded seam, a...

  4. Fusion welding process

    DOEpatents

    Thomas, Kenneth C.; Jones, Eric D.; McBride, Marvin A.

    1983-01-01

    A process for the fusion welding of nickel alloy steel members wherein a ferrite containing pellet is inserted into a cavity in one member and melted by a welding torch. The resulting weld nugget, a fusion of the nickel containing alloy from the members to be welded and the pellet, has a composition which is sufficiently low in nickel content such that ferrite phases occur within the weld nugget, resulting in improved weld properties. The steel alloys encompassed also include alloys containing carbon and manganese, considered nickel equivalents.

  5. Laser welding and post weld treatment of modified 9Cr-1MoVNb steel.

    SciTech Connect

    Xu, Z.

    2012-04-03

    Laser welding and post weld laser treatment of modified 9Cr-1MoVNb steels (Grade P91) were performed in this preliminary study to investigate the feasibility of using laser welding process as a potential alternative to arc welding methods for solving the Type IV cracking problem in P91 steel welds. The mechanical and metallurgical testing of the pulsed Nd:YAG laser-welded samples shows the following conclusions: (1) both bead-on-plate and circumferential butt welds made by a pulsed Nd:YAG laser show good welds that are free of microcracks and porosity. The narrow heat affected zone has a homogeneous grain structure without conventional soft hardness zone where the Type IV cracking occurs in conventional arc welds. (2) The laser weld tests also show that the same laser welder has the potential to be used as a multi-function tool for weld surface remelting, glazing or post weld tempering to reduce the weld surface defects and to increase the cracking resistance and toughness of the welds. (3) The Vicker hardness of laser welds in the weld and heat affected zone was 420-500 HV with peak hardness in the HAZ compared to 240 HV of base metal. Post weld laser treatment was able to slightly reduce the peak hardness and smooth the hardness profile, but failed to bring the hardness down to below 300 HV due to insufficient time at temperature and too fast cooling rate after the time. Though optimal hardness of weld made by laser is to be determined for best weld strength, methods to achieve the post weld laser treatment temperature, time at the temperature and slow cooling rate need to be developed. (4) Mechanical testing of the laser weld and post weld laser treated samples need to be performed to evaluate the effects of laser post treatments such as surface remelting, glazing, re-hardening, or tempering on the strength of the welds.

  6. Particulate and gaseous emissions when welding aluminum alloys.

    PubMed

    Cole, Homer; Epstein, Seymour; Peace, Jon

    2007-09-01

    Fabrication and repair of aluminum components and structures commonly involves the use of electric arc welding. The interaction of the arc and the metal being welded generates ultraviolet radiation, metallic oxides, fumes, and gases. Aluminum is seldom used as the pure metal but is often alloyed with other metals to improve strength and other physical properties. Therefore, the exact composition of any emissions will depend on the welding process and the particular aluminum alloy being welded. To quantify such emissions, The Aluminum Association sponsored several studies to characterize arc welding emissions by the gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW) processes for various combinations of base and filler alloys. In all cases, the tests were conducted under conditions that could be found in a production weld shop without forced ventilation. The concentrations of each analyte that a welder could be exposed to were greatly affected by the welding process, the composition of the base and filler alloys, the position of the welder, and the welding helmet. The results obtained can be used by employers to identify and control potential hazards associated with the welding of aluminum alloys and can provide the basis for hazard communication to employees involved in the welding of these alloys. PMID:17620189

  7. Ultrasonic vibration aided laser welding of Al alloys: Improvement of laser-welding quality

    SciTech Connect

    Kim, J.S.; Watanabe, T.; Yoshida, Y.

    1995-03-01

    Using a pulsed YAG laser, meltability of Al-Mg and Al-Mg-Si alloys were investigated by a single-pass irradiation. In order to improve the quality in laser welding, the effectiveness of the Ultrasonic Vibration Laser Welding (UVLW) method proposed in this paper was investigated experimentally. The proposed method was also compared with the traditional welding methods of Normal Laser Welding (NLW) and preHeating Laser Welding (HLW). The welding methods were evaluated from the geometry in the melt zone generated by a single pulse of the laser beam. It was suggested that ultrasonic vibration suppressed welding defects and improved the melt characteristics due to cavitation effects and dispersion of particles in the molten pool during laser welding. The influence on melt characteristics of the melt zone by preheating was also investigated. In these experiments, UVLW was the most useful laser welding method from the point of view of improving the laser welding quality of Al alloys.

  8. Advanced Testing Techniques to Measure the PWSCC Resistance of Alloy 690 and its Weld Metals

    SciTech Connect

    P.Andreson

    2004-10-01

    Wrought Alloy 600 and its weld metals (Alloy 182 and Alloy 82) were originally used in pressurized water reactors (PWRs) due to the material's inherent resistance to general corrosion in a number of aggressive environments and because of a coefficient of thermal expansion that is very close to that of low alloy and carbon steel. Over the last thirty years, stress corrosion cracking in PWR primary water (PWSCC) has been observed in numerous Alloy 600 component items and associated welds, sometimes after relatively long incubation times. The occurrence of PWSCC has been responsible for significant downtime and replacement power costs. As part of an ongoing, comprehensive program involving utilities, reactor vendors and engineering/research organizations, this report will help to ensure that corrosion degradation of nickel-base alloys does not limit service life and that full benefit can be obtained from improved designs for both replacement components and new reactors.

  9. Technique to eliminate helium induced weld cracking in stainless steels

    SciTech Connect

    Chin-An Wang; Chin, B.A.; Grossbeck, M.L.

    1992-12-31

    Experiments have shown that Type 316 stainless steel is susceptible to heat-affected-zone (HAZ) cracking upon cooling when welded using the gas tungsten arc (GTA) process under lateral constraint. The cracking has been hypothesized to be caused by stress-assisted helium bubble growth and rupture at grain boundaries. This study utilized an experimental welding setup which enabled different compressive stresses to be applied to the plates during welding. Autogenous GTA welds were produced in Type 316 stainless steel doped with 256 appm helium. The application of a compressive stress, 55 Mpa, during welding suppressed the previously observed catastrophic cracking. Detailed examinations conducted after welding showed a dramatic change in helium bubble morphology. Grain boundary bubble growth along directions parallel to the weld was suppressed. Results suggest that stress-modified welding techniques may be used to suppress or eliminate helium-induced cracking during joining of irradiated materials.

  10. Prediction of Weld Penetration in FCAW of HSLA steel using Artificial Neural Networks

    NASA Astrophysics Data System (ADS)

    Asl, Y. Dadgar; Mostafa, N. B.; Panahizadeh R., V.; Seyedkashi, S. M. H.

    2011-01-01

    Flux-cored arc welding (FCAW) is a semiautomatic or automatic arc welding process that requires a continuously-fed consumable tubular electrode containing a flux. The main FCAW process parameters affecting the depth of penetration are welding current, arc voltage, nozzle-to-work distance, torch angle and welding speed. Shallow depth of penetration may contribute to failure of a welded structure since penetration determines the stress-carrying capacity of a welded joint. To avoid such occurrences; the welding process parameters influencing the weld penetration must be properly selected to obtain an acceptable weld penetration and hence a high quality joint. Artificial neural networks (ANN), also called neural networks (NN), are computational models used to express complex non-linear relationships between input and output data. In this paper, artificial neural network (ANN) method is used to predict the effects of welding current, arc voltage, nozzle-to-work distance, torch angle and welding speed on weld penetration depth in gas shielded FCAW of a grade of high strength low alloy steel. 32 experimental runs were carried out using the bead-on-plate welding technique. Weld penetrations were measured and on the basis of these 32 sets of experimental data, a feed-forward back-propagation neural network was created. 28 sets of the experiments were used as the training data and the remaining 4 sets were used for the testing phase of the network. The ANN has one hidden layer with eight neurons and is trained after 840 iterations. The comparison between the experimental results and ANN results showed that the trained network could predict the effects of the FCAW process parameters on weld penetration adequately.

  11. Prediction of Weld Penetration in FCAW of HSLA steel using Artificial Neural Networks

    SciTech Connect

    Asl, Y. Dadgar; Mostafa, N. B.; Panahizadeh, V. R.; Seyedkashi, S. M. H.

    2011-01-17

    Flux-cored arc welding (FCAW) is a semiautomatic or automatic arc welding process that requires a continuously-fed consumable tubular electrode containing a flux. The main FCAW process parameters affecting the depth of penetration are welding current, arc voltage, nozzle-to-work distance, torch angle and welding speed. Shallow depth of penetration may contribute to failure of a welded structure since penetration determines the stress-carrying capacity of a welded joint. To avoid such occurrences; the welding process parameters influencing the weld penetration must be properly selected to obtain an acceptable weld penetration and hence a high quality joint. Artificial neural networks (ANN), also called neural networks (NN), are computational models used to express complex non-linear relationships between input and output data. In this paper, artificial neural network (ANN) method is used to predict the effects of welding current, arc voltage, nozzle-to-work distance, torch angle and welding speed on weld penetration depth in gas shielded FCAW of a grade of high strength low alloy steel. 32 experimental runs were carried out using the bead-on-plate welding technique. Weld penetrations were measured and on the basis of these 32 sets of experimental data, a feed-forward back-propagation neural network was created. 28 sets of the experiments were used as the training data and the remaining 4 sets were used for the testing phase of the network. The ANN has one hidden layer with eight neurons and is trained after 840 iterations. The comparison between the experimental results and ANN results showed that the trained network could predict the effects of the FCAW process parameters on weld penetration adequately.

  12. A study of chromium carbide precipitation at interphase boundaries in stainless steel welds

    SciTech Connect

    Willis, C.F.

    1990-04-01

    Sensitization is a deleterious process which can occur in stainless steels. It is caused by grain boundary or phase boundary precipitation of chromium carbides and the resulting formation of a chromium depleted zone adjacent to these boundaries. The carbides in question actually have the composition (Cr,Fe){sub 23}C{sub 6} (usually written M{sub 23}C{sub 6}), and precipitate in the temperature range 450--900{degree}C. Since a minimum chromium content is required to maintain the passive film necessary for resistance to electrochemical attack, the result of chromium depletion is that the steel becomes sensitized'' to possible intergranular corrosion. Sensitization often occurs as a result of welding operations. The material close to the fusion line reaches temperatures within the sensitization range. This region is called the heat affected zone (HAZ). Since many welds are multi-pass welds, the actual weld bead of one pass may lie in the heat affected zone of the next pass. The weld bead of the first pass might therefore be sensitized. Furthermore there are applications where welds will be exposed to sensitizing temperatures for very long periods of time, such as welded labels on retrievable nuclear waste containers. For these reasons the sensitization behavior of the actual weld-bead microstructures must be understood. It has been known for many years that duplex stainless steels (steels with both ferrite and austenite phases present at room temperature) have superior resistance to intergranular corrosion. A model has been proposed to explain the sensitization behavior of these alloys. This work will be concerned with testing the validity of aspects of this model using transmission electron microscopy and further understanding of the sensitization process in duplex stainless steel welds. 52 refs., 23 figs.

  13. Arc Welding of Mg Alloys: Oxide Films, Irregular Weld Shape and Liquation Cracking

    NASA Astrophysics Data System (ADS)

    Chai, Xiao

    The use of Mg alloys for vehicle weight reduction has been increasing rapidly worldwide. Gas-metal arc welding (GMAW) has the potential for mass-production welding of Mg alloys. Recently, the University of Wisconsin demonstrated in bead-on-plate GMAW of Mg alloys that severe spatter can be eliminated by using controlled short circuiting (CSC), and severe hydrogen porosity can be eliminated by removing Mg(OH)2. The present study aimed at actual butt and lap welding of Mg alloys by CSC-GMAW and susceptibility of Mg alloys to weld-edge cracking using the circular-patch welding test. Sound welds were made without spatter and hydrogen porosity butt and lap welding of AZ 31 Mg using CSC-GMAW , with butt welds approaching 100% of the base-metal strength. However, three new significant issues were found to occur easily and degrade the weld quality significantly: 1. formation of oxide films inside butt welds, 2. formation of high crowns on butt welds, and 3. formation of fingers from lap welds. The mechanisms of their formation were established, and the methods for their elimination or reduction were demonstrated. Circular-patch welds were made on most widely used Mg casting alloy AZ91, the most widely used Mg wrought alloy AZ31 with three different Mg filler wires AZ31, AZ61 and AZ92. The susceptibility to cracking along the weld edge was predicted and compared against the experimental results. Such a prediction has not been made for welds of Mg alloys before.

  14. Recent progress on gas tungsten arc welding of vanadium alloys

    SciTech Connect

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

    1997-04-01

    This is a progress report on a continuing research project to acquire a fundamental understanding of the metallurgical processes in the welding of vanadium alloys. It also has the goal of developing techniques for welding structural vanadium alloys. The alloy V-4Cr-4Ti is used as a representative alloy of the group; it is also the prime candidate vanadium alloy for the U.S. Fusion Program at the present time. However, other alloys of this class were used in the research as necessary. The present work focuses on recent findings of hydrogen embrittlement found in vanadium alloy welds. It was concluded that the atmosphere in the inert gas glove box was insufficient for welding 6mm thick vanadium alloy plates.

  15. Characterization of welded HP 9-4-30 steel for the advanced solid rocket motor

    NASA Technical Reports Server (NTRS)

    Watt, George William

    1990-01-01

    Solid rocket motor case materials must be high-strength, high-toughness, weldable alloys. The Advanced Solid Rocket Motor (ASRM) cases currently being developed will be made from a 9Ni-4Co quench and temper steel called HP 9-4-30. These ultra high-strength steels must be carefully processed to give a very clean material and a fine grained microstructure, which insures excellent ductility and toughness. The HP 9-4-30 steels are vacuum arc remelted and carbon deoxidized to give the cleanliness required. The ASRM case material will be formed into rings and then welded together to form the case segments. Welding is the desired joining technique because it results in a lower weight than other joining techniques. The mechanical and corrosion properties of the weld region material were fully studied.

  16. Weld microstructure development and properties of precipitation-strengthened martensitic stainless steels

    SciTech Connect

    Brooks, J.

    1994-12-31

    Precipitation-strengthened martensitic stainless steels provide excellent strength (170--220 ksi Y.S.) with high corrosion resistance. However, upon aging, a large reduction in toughness may also occur. The gas tungsten arc (GTA) cold wire feed process was used to weld half inch thick plates of PH 13-8 Mo and Custom 450 from which both tensile and Charpy specimens were machined. A fundamental understanding of the details of weld microstructural evolution was developed by liquid tin quenching GTA welds in which the solidification behavior, primary phase of solidification, microsegregation, and solid-state transformations could be followed. For both alloys studied, the as-welded yield strengths were similar to those of the unaged base material, 130 ksi. Weld properties were very similar to those of the base materials for both alloy systems. Weld strength increases significantly upon aging and achieves a maximum at intermediate aging temperatures. The increase in strength is accompanied by a large decrease in Charpy impact energy; however, the minimum in toughness occurs at aging temperatures slightly less than those resulting in peak strengths. The evolution of the weld microstructure was found to support predictions of microstructural modeling. Although a high degree of alloying partitioning occurs during solidification, a large degree of homogenization occurs upon further solidification and cooling as a result of solid-state diffusion.

  17. The solidification and welding metallurgy of galling-resistant stainless steels

    SciTech Connect

    Robino, C.V.; Michael, J.R.; Maguire, M.C.

    1998-11-01

    The autogenous welding behavior of two commercial galling-resistant austenitic stainless steels, Nitronic 60 and Gall-Tough, was evaluated and compared. The solidification behavior and fusion zone hot-cracking tendency of the alloys was evaluated by using differential thermal analysis, Varestraint testing and laser spot-welding trials. Gleeble thermal cycle simulations were used to assess the hot ductility of the alloys during both on-heating and on-cooling portions of weld thermal cycles. Solidification microstructures were characterized by light optical and electron microscopy, and the solidification modes and phases were identified. Gas tungsten arc (GTA) welds in both alloys solidified by the ferritic-austenitic mode, and their behavior was best described using chromium and nickel equivalents developed specifically for the Nitronic series of alloys. Both alloys were found to be somewhat more susceptible to solidification hot cracking than conventional austenitic stainless steels, although the cracking resistance of Nitronic 60 was somewhat superior to Gall-Tough. Laser spot-welding trials resulted in both fusion and heat-affected zone cracking in the Nitronic 60, while Gall-Tough was resistant to cracking in these high-solidification-rate welds. Comparison of the laser weld microstructures indicated that Nitronic 60 shifts to fully austenitic solidification, while Gall-Tough shifts to an austenitic-ferritic solidification mode in high-energy-density processing. The hot ductility measurements indicated that Gall-Tough is generally superior to Nitronic 60 in both on-heating and on-cooling tests, apparently as a result of differences in grain size and the mechanism of ferrite formation at high temperatures.

  18. Carbide-Free Bainitic Weld Metal: A New Concept in Welding of Armor Steels

    NASA Astrophysics Data System (ADS)

    Krishna Murthy, N.; Janaki Ram, G. D.; Murty, B. S.; Reddy, G. M.; Rao, T. J. P.

    2014-12-01

    Carbide-free bainite, a fine mixture of bainitic ferrite and austenite, is a relatively recent development in steel microstructures. Apart from being very strong and tough, the microstructure is hydrogen-tolerant. These characteristics make it well-suited for weld metals. In the current work, an armor-grade quenched and tempered steel was welded such that the fusion zone developed a carbide-free bainitic microstructure. These welds showed very high joint efficiency and ballistic performance compared to those produced, as per the current industrial practice, using austenitic stainless steel fillers. Importantly, these welds showed no vulnerability to cold cracking, as verified using oblique Y-groove tests. The concept of carbide-free bainitic weld metal thus promises many useful new developments in welding of high-strength steels.

  19. Friction Stir Welding Of Ma957 Oxide Dispersion Strengthened Ferritic Steel

    SciTech Connect

    Howard, Stanley M.; Jasthi, Bharat K.; Arbegast, William J.; Grant, Glenn J.; Koduri, Santhosh K.; Herling, Darrell R.; Gelles, David S.

    2005-04-02

    A 1-in. (25.4 mm) diameter yttria-dispersion-strengthened MA957 ferritic steel alloy tube with a 0.125" (3.18 mm) wall thickness was successfully plasticized by friction stir welding. The pin tool was a W-Re tool with 0.125" (3.17 mm) diameter tip. It showed no discernable wear for the total 12" (305 mm) of weld. Weld conditions were 1000 and 1400 RPM, 4 in/min (101 mm/min), with and without preheating to 135ºC. Metallographic analysis of the post friction-stir welded material showed a decrease in material hardness to 225±22 HV compared to the parent material at 373±21 HV. All weld conditions produced plasticization; however, improved plasticization was observed for preheated samples

  20. Plating on stainless steel alloys

    SciTech Connect

    Dini, J.W.; Johnson, H.R.

    1981-09-11

    Quantitative adhesion data are presented for a variety of electroplated stainless steel type alloys. Results show that excellent adhesion can be obtained by using a Wood's nickel strike or a sulfamate nickel strike prior to final plating. Specimens plated after Wood's nickel striking failed in the deposit rather than at the interface between the substrate and the coating. Flyer plate quantitative tests showed that use of anodic treatment in sulfuric acid prior to Wood's nickel striking even further improved adhesion. In contrast activation of stainless steels by immersion or cathodic treatment in hydrochloric acid resulted in very reduced bond strengths with failure always occurring at the interface between the coating and substrate.

  1. Influence of nitrogen in the shielding gas on corrosion resistance of duplex stainless steel welds

    SciTech Connect

    Bhatt, R.B.; Kamat, H.S.; Ghosal, S.K.; De, P.K.

    1999-10-01

    The influence of nitrogen in shielding gas on the corrosion resistance of welds of a duplex stainless steel (grade U-50), obtained by gas tungsten arc (GTA) with filler wire, autogenous GTA (bead-on-plate), electron beam welding (EBW), and microplasma techniques, has been evaluated in chloride solutions at 30 C. Pitting attack has been observed in GTA, electron beam welding, and microplasma welds when welding has been carried out using pure argon as the shielding gas. Gas tungsten arc welding with 5 to 10% nitrogen and 90 to 95% argon, as the shielding gas, has been found to result in an improved pitting corrosion resistance of the weldments of this steel. However, the resistance of pitting of autogenous welds (bead-on-plate) obtained in pure argon as the shielding gas has been observed to remain unaffected. Microscopic examination, electron probe microanalysis (EPMA), and x-ray diffraction studies have revealed that the presence of nitrogen in the shielding gas in the GTA welds not only modifies the microstructure and the austenite to ferrite ratio but also results in a nearly uniform distribution of the various alloying elements, for example, chromium, nickel, and molybdenum among the constituent phases, which are responsible for improved resistance to pitting corrosion.

  2. Influence of nitrogen in the shielding gas on corrosion resistance of duplex stainless steel welds

    NASA Astrophysics Data System (ADS)

    Bhatt, R. B.; Kamat, H. S.; Ghosal, S. K.; de, P. K.

    1999-10-01

    The influence of nitrogen in shielding gas on the corrosion resistance of welds of a duplex stainless steel (grade U-50), obtained by gas tungsten arc (GTA) with filler wire, autogenous GTA (bead-on-plate), electron beam welding (EBW), and microplasma techniques, has been evaluated in chloride solutions at 30 °C. Pitting attack has been observed in GTA, electron beam welding, and microplasma welds when welding has been carried out using pure argon as the shielding gas. Gas tungsten arc welding with 5 to 10% nitrogen and 90 to 95% argon, as the shielding gas, has been found to result in an improved pitting corrosion resistance of the weldments of this steel. However, the resistance to pitting of autogenous welds (bead-on-plate) obtained in pure argon as the shielding gas has been observed to remain unaffected. Microscopic examination, electron probe microanalysis (EPMA), and x-ray diffraction studies have revealed that the presence of nitrogen in the shielding gas in the GTA welds not only modifies the microstructure and the austenite to ferrite ratio but also results in a nearly uniform distribution of the various alloying elements, for example, chromium, nickel, and molybdenum among the constitutent phases, which are responsible for improved resistance to pitting corrosion.

  3. MECHANICAL PROPERTIES AND MICROSTRUCTURAL CHARACTERIZATION OF A MULTILAYERED MULTIPASS FRICTION STIR WELD IN STEEL

    SciTech Connect

    Lim, Yong Chae; Sanderson, Samuel; Mahoney, Murray; Qiao, Dongxiao; Wang, Yanli; Zhang, Wei; Feng, Zhili

    2013-01-01

    Multilayered multipass friction stir welding (MM-FSW) makes it possible to use FSW to fabricate thick-section structures. In this work, MM-FSW was demonstrated on a high strength low alloy steel; ASTM A572 Grade 50. Three steel plates with thicknesses of 0.18", 0.18", 0.24" respectively were stacked and friction stir welded together to form a 0.6" thick welded structure. The welded plate was sectioned into rectangular bars transverse to the weld direction for tensile testing to evaluate mechanical properties. Digital image correlation (DIC) was employed to map the local strain fields during tensile testing. The initial failure was found to occur simultaneously at the bottom and middle layers away from the weld zone. The top layer failed last in the base metal. The failure locations were consistent among different samples tested. Also, Charpy V-notch impact tests were conducted for weld metal, heat affected zone, and the base metal at each layer as a function of temperature. The weld microstructures were characterized using optical and electron microscopy and micro-hardness mapping.

  4. Variable-Polarity Plasma Arc Welding Of Alloy 2219

    NASA Technical Reports Server (NTRS)

    Walsh, Daniel W.; Nunes, Arthur C., Jr.

    1989-01-01

    Report presents results of study of variable-polarity plasma arc (VPPA) welding of aluminum alloy 2219. Consists of two parts: Examination of effects of microsegregation and transient weld stress on macrosegregation in weld pool and, electrical characterization of straight- and reverse-polarity portions of arc cycle.

  5. Fracturing behavior of aluminum alloys with welded joints

    NASA Astrophysics Data System (ADS)

    Polyakov, V. V.; Kolubaev, E. A.; Salita, D. S.; Dmitriev, A. A.; Lependin, A. A.

    2015-10-01

    In this paper, properties of aluminum-magnesium alloys with welded joints are investigated. The joints are produced by the friction stir welding under various conditions. This fact is used for studying the principles and patterns of defect structure development. Mechanical properties are evaluated by static tension tests. The impact of welding process conditions on loading curves and strength properties is analysed. Fracture surface structures for samples with and without welded joints are studied, and results are compared. It is revealed, that differences in deformation behavior and mechanical properties of aluminum-magnesium alloys produced under different welding process conditions are caused by developing of structure defects in a welded joints, mostly, nonuniformities/discontinuities of various types. The obtained results can be used for improvement and development of new welding process conditions for aluminum-magnesium alloys.

  6. Laser beam welding of AZ31B-H24 magnesium alloy.

    SciTech Connect

    Leong, K. H.

    1998-09-29

    The laser beam weldability of AZ31B magnesium alloy was examined with high power CW CO{sub 2} and pulsed Nd:YAG lasers. The low viscosity and surface tension of the melt pool make magnesium more difficult to weld than steel. Welding parameters necessary to obtain good welds were determined for both CW CO{sub 2} and pulsed Nd:YAG lasers. The weldability of the magnesium alloy was significantly better with the Nd:YAG laser. The cause of this improvement was attributed to the higher absorption of the Nd:YAG beam. A lower threshold beam irradiance was required for welding, and a more stable weldpool was obtained.

  7. Investigation of aluminum-steel joint formed by explosion welding

    NASA Astrophysics Data System (ADS)

    Kovacs-Coskun, T.; Volgyi, B.; Sikari-Nagl, I.

    2015-04-01

    Explosion welding is a solid state welding process that is used for the metallurgical joining of metals. Explosion cladding can be used to join a wide variety of dissimilar or similar metals [1]. This process uses the controlled detonation of explosives to accelerate one or both of the constituent metals into each other in such a manner as to cause the collision to fuse them together [2]. In this study, bonding ability of aluminum and steel with explosion welding was investigated. Experimental studies, microscopy, microhardness, tensile and bend test showed out that, aluminum and steel could be bonded with a good quality of bonding properties with explosion welding.

  8. Pulsed-Current Welding Of Nickel-Based Alloy

    NASA Technical Reports Server (NTRS)

    Gamwell, W. R.; Kurgan, C.; Malone, T. W.

    1993-01-01

    Joints as strong (or stronger than) joints made with constant current. Report based on study of pulsed-current versus constant-current gas/tungsten arc welding of butt joints between panels of nickel-based alloy 718. In pulsed-current welding, arc current alternated between high and low value. Enables greater control of freezing and depth of penetration of weld puddle at given heat input. Thicker sections joined. Readily incorporated into automated welding system, with resultant greater uniformity and reproducibility of welds than attained in manual welding.

  9. Practical method for diffusion welding of steel plate in air.

    NASA Technical Reports Server (NTRS)

    Moore, T. J.; Holko, K. H.

    1972-01-01

    Description of a simple and easily applied method of diffusion welding steel plate in air which does not require a vacuum furnace or hot press. The novel feature of the proposed welding method is that diffusion welds are made in air with deadweight loading. In addition, the use of an autogenous (self-generated) surface-cleaning principle (termed 'auto-vac cleaning') to reduce the effects of surface oxides that normally hinder diffusion welding is examined. A series of nine butt joints were diffusion welded in thick sections of AISI 1020 steel plate. Diffusion welds were attempted at three welding temperatures (1200, 1090, and 980 C) using a deadweight pressure of 34,500 N/sq m (5 psi) and a two-hour hold time at temperature. Auto-vac cleaning operations prior to welding were also studied for the same three temperatures. Results indicate that sound welds were produced at the two higher temperatures when the joints were previously fusion seal welded completely around the periphery. Also, auto-vac cleaning at 1200 C for 2-1/2 hours prior to diffusion welding was highly beneficial, particularly when subsequent welding was accomplished at 1090 C.

  10. Surface preparation effects on GTA weld shape in JBK-75 stainless steel

    SciTech Connect

    Campbell, R.D.; Robertson, A.M. ); Heiple, C.R. ); Sturgill, P.L.; Jamsay, R.

    1993-02-01

    The results of a study are reported here on the effects of surface preparation on the shape of autogenous gas tungsten arc (GTA) welds in JBK-75, an austenitic precipitation hardenable stainless steel similar to A286. Minor changes in surface preparation produced substantial changes in the fusion zone shape and welding behavior of this alloy. Increased and more consistent depth of fusion (higher d/w ratios) along with improved arc stability and less arc wander resulted from wire brushing and other abrasive surface preparations, although chemical and machining methods did not produce any increase in depth of fusion. Abrasive treatments roughen the surface, increase the surface area, increase the surface oxide thickness, and entrap oxide. The increased weld d/w ratio is attributed to oxygen added to the weld pool from the surface oxide on the base metal. The added oxygen alters the surface-tension-driven fluid flow pattern in the weld pool. Increased depth of fusion in wire-fed U-groove weld joints also resulted when welding wire with a greater surface oxide thickness was used. Increasing the amount of wire brushing produced even deeper welds. However, a maximum in depth of fusion was observed with further wire brushing, beyond which weld fusion depth decreased.

  11. Laser Welding of Large Scale Stainless Steel Aircraft Structures

    NASA Astrophysics Data System (ADS)

    Reitemeyer, D.; Schultz, V.; Syassen, F.; Seefeld, T.; Vollertsen, F.

    In this paper a welding process for large scale stainless steel structures is presented. The process was developed according to the requirements of an aircraft application. Therefore, stringers are welded on a skin sheet in a t-joint configuration. The 0.6 mm thickness parts are welded with a thin disc laser, seam length up to 1920 mm are demonstrated. The welding process causes angular distortions of the skin sheet which are compensated by a subsequent laser straightening process. Based on a model straightening process parameters matching the induced welding distortion are predicted. The process combination is successfully applied to stringer stiffened specimens.

  12. Microstructure and mechanical properties of weld fusion zones in modified 9Cr-1Mo steel

    NASA Astrophysics Data System (ADS)

    Sireesha, M.; Sundaresan, S.; Albert, Shaju K.

    2001-06-01

    Modified 9Cr-1Mo steel finds increasing application in power plant construction because of its excellent high-temperature properties. While it has been shown to be weldable and resistant to all types of cracking in the weld metal and heat-affected zone (HAZ), the achievement of optimum weld metal properties has often caused concern. The design of appropriate welding consumables is important in this regard. In the present work, plates of modified 9Cr-1Mo steel were welded with three different filler materials: standard 9Cr-1Mo steel, modified 9Cr-1Mo, and nickel-base alloy Inconel 182. Post-weld heat treatment (PWHT) was carried out at 730 and 760 °C for periods of 2 and 6 h. The joints were characterized in detail by metallography. Hardness, tensile properties, and Charpy toughness were evaluated. Among the three filler materials used, although Inconel 182 resulted in high weld metal toughness, the strength properties were too low. Between modified and standard 9Cr-1Mo, the former led to superior hardness and strength in all conditions. However, with modified 9Cr-1Mo, fusion zone toughness was low and an acceptable value could be obtained only after PWHT for 6 h at 760 °C. The relatively poor toughness was correlated to the occurrence of local regions of untransformed ferrite in the microstructure.

  13. High temperature corrosion of welded ferritic stainless steel in flowing CO2 gas

    NASA Astrophysics Data System (ADS)

    Shariff, Nurul Atikah; Othman, Norinsan Kamil; Jalar, Azman; Hamid, Muhammad Azmi Abdul; Rahman, Irman Abdul

    2013-05-01

    The high temperature corrosion of welded structure of Ferritic Stainless Steel (FSS) in flowing Ar-75%CO2 gas at 700°C has been investigated. The welded structure of FSS joint using ER 308L filler metal by GTAW. The soundness of welded joint has been clarified by X-Ray CT Scan. Prior the high temperature exposure, the welded FSS compulsory passed the standard of ASME. The welded structure of FSS was heated in flowing CO2 gas for 50 h at 1 atm. The morphology and microstructure of oxide formation on welded FSS alloy was characterized by using SEM. The result shows that the different oxide morphologies were observed on parent and fusion metal. The formation of different oxide and element properties at the interface were revealed by X-Ray Diffraction. The differences of the physical condition and morphology microstructure of welded and parent metal were observed to respond to different exposure times. This phenomenon perhaps explained due to the differences of the minor alloying elements on both parent and filler metals. The high temperature corrosion behaviour was discussed in details in this paper regarding on the physical properties, morphology and the microstructure.

  14. Friction stir welding process to repair voids in aluminum alloys

    NASA Technical Reports Server (NTRS)

    Rosen, Charles D. (Inventor); Litwinski, Edward (Inventor); Valdez, Juan M. (Inventor)

    1999-01-01

    The present invention provides an in-process method to repair voids in an aluminum alloy, particularly a friction stir weld in an aluminum alloy. For repairing a circular void or an in-process exit hole in a weld, the method includes the steps of fabricating filler material of the same composition or compatible with the parent material into a plug form to be fitted into the void, positioning the plug in the void, and friction stir welding over and through the plug. For repairing a longitudinal void (30), the method includes machining the void area to provide a trough (34) that subsumes the void, fabricating filler metal into a strip form (36) to be fitted into the trough, positioning the strip in the trough, and rewelding the void area by traversing a friction stir welding tool longitudinally through the strip. The method is also applicable for repairing welds made by a fusing welding process or voids in aluminum alloy workpieces themselves.

  15. Tool For Friction Stir Tack Welding of Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Bjorkman, Gerald W.; Dingler, Johnny W.; Loftus, Zachary

    2003-01-01

    A small friction-stir-welding tool has been developed for use in tack welding of aluminum-alloy workpieces. It is necessary to tack-weld the workpieces in order to hold them together during friction stir welding because (1) in operation, a full-size friction-stir-welding tool exerts a large force that tends to separate the workpieces and (2) clamping the workpieces is not sufficient to resist this force. It is possible to tack the pieces together by gas tungsten arc welding, but the process can be awkward and time-consuming and can cause sufficient damage to necessitate rework. Friction stir tack welding does not entail these disadvantages. In addition, friction stir tack welding can be accomplished by use of the same automated equipment (except for the welding tool) used in subsequent full friction stir welding. The tool for friction stir tack welding resembles the tool for full friction stir welding, but has a narrower shoulder and a shorter pin. The shorter pin generates a smaller workpiece-separating force so that clamping suffices to keep the workpieces together. This tool produces a continuous or intermittent partial-penetration tack weld. The tack weld is subsequently consumed by action of the larger tool used in full friction stir welding tool.

  16. Diode laser welding of aluminum to steel

    SciTech Connect

    Santo, Loredana; Quadrini, Fabrizio; Trovalusci, Federica

    2011-05-04

    Laser welding of dissimilar materials was carried out by using a high power diode laser to join aluminum to steel in a butt-joint configuration. During testing, the laser scan rate was changed as well as the laser power: at low values of fluence (i.e. the ratio between laser power and scan rate), poor joining was observed; instead at high values of fluence, an excess in the material melting affected the joint integrity. Between these limiting values, a good aesthetics was obtained; further investigations were carried out by means of tensile tests and SEM analyses. Unfortunately, a brittle behavior was observed for all the joints and a maximum rupture stress about 40 MPa was measured. Apart from the formation of intermeltallic phases, poor mechanical performances also depended on the chosen joining configuration, particularly because of the thickness reduction of the seam in comparison with the base material.

  17. M551 metals melting experiment. [space manufacturing of aluminum alloys, tantalum alloys, stainless steels

    NASA Technical Reports Server (NTRS)

    Li, C. H.; Busch, G.; Creter, C.

    1976-01-01

    The Metals Melting Skylab Experiment consisted of selectively melting, in sequence, three rotating discs made of aluminum alloy, stainless steel, and tantalum alloy. For comparison, three other discs of the same three materials were similarly melted or welded on the ground. The power source of the melting was an electron beam unit. Results are presented which support the concept that the major difference between ground base and Skylab samples (i.e., large elongated grains in ground base samples versus nearly equiaxed and equal sized grains in Skylab samples) can be explained on the basis of constitutional supercooling, and not on the basis of surface phenomena. Microstructural observations on the weld samples and present explanations for some of these observations are examined. In particular, ripples and their implications to weld solidification were studied. Evidence of pronounced copper segregation in the Skylab A1 weld samples, and the tantalum samples studied, indicates a weld microhardness (and hence strength) that is uniformly higher than the ground base results, which is in agreement with previous predictions. Photographs are shown of the microstructure of the various alloys.

  18. Effect of Welding Heat Input on the Corrosion Resistance of Carbon Steel Weld Metal

    NASA Astrophysics Data System (ADS)

    Lu, Yongxin; Jing, Hongyang; Han, Yongdian; Xu, Lianyong

    2016-02-01

    The corrosion resistance of carbon steel weld metal with three different microstructures has been systematically evaluated using electrochemical techniques with the simulated produced water containing CO2 at 90 °C. Microstructures include acicular ferrite, polygonal ferrite, and a small amount of pearlite. With welding heat input increasing, weld metal microstructure becomes more uniform. Electrochemical techniques including potentiodynamic polarization curve, linear polarization resistance, and electrochemical impedance spectroscopy were utilized to characterize the corrosion properties on weld joint, indicating that the best corrosion resistance corresponded to the weld metal with a polygonal ferrite microstructure, whereas the weld metal with the acicular ferrite + polygonal ferrite microstructure showed the worst corrosion resistance. The samples with high welding heat input possessed better corrosion resistance. Results were discussed in terms of crystal plane orientation, grain size, and grain boundary type found in each weld metal by electron backscatter diffraction test.

  19. Parametric Studies Of Weld Quality Of Tungsten Inert Gas Arc Welding Of Stainless Steel

    SciTech Connect

    Kumar Pal, Pradip; Nandi, Goutam; Ghosh, Nabendu

    2011-01-17

    Effect of current and gas flow rate on quality of weld in tungsten inter gas arc welding of austenitic stainless steel has been studied in the present work through experiments and analyses. Butt welded joints have been made by using several levels of current and gas flow rate. The quality of the weld has been evaluated in terms of ultimate and breaking strengths of the welded specimens. The observed data have been interpreted, discussed and analyzed by using Grey--Taguchi methodology. Optimum parametric setting has been predicted and validated as well.

  20. Bond strength of gold alloys laser welded to cobalt-chromium alloy.

    PubMed

    Watanabe, Ikuya; Wallace, Cameron

    2008-01-01

    The objective of this study was to investigate the joint properties between cast gold alloys and Co-Cr alloy laser-welded by Nd:YAG laser. Cast plates were fabricated from three types of gold alloys (Type IV, Type II and low-gold) and a Co-Cr alloy. Each gold alloy was laser-welded to Co-Cr using a dental laser-welding machine. Homogeneously-welded and non-welded control specimens were also prepared. Tensile testing was conducted and data were statistically analyzed using ANOVA. The homogeneously-welded groups showed inferior fracture load compared to corresponding control groups, except for Co-Cr. In the specimens welded heterogeneously to Co-Cr, Type IV was the greatest, followed by low-gold and Type II. There was no statistical difference (P<0.05) in fracture load between Type II control and that welded to Co-Cr. Higher elongations were obtained for Type II in all conditions, whereas the lowest elongation occurred for low-gold welded to Co-Cr. This study indicated that, of the three gold alloys tested, the Type IV gold alloy was the most suitable alloy for laser-welding to Co-Cr. PMID:19088892

  1. Bond Strength of Gold Alloys Laser Welded to Cobalt-Chromium Alloy

    PubMed Central

    Watanabe, Ikuya; Wallace, Cameron

    2008-01-01

    The objective of this study was to investigate the joint properties between cast gold alloys and Co-Cr alloy laser-welded by Nd:YAG laser. Cast plates were fabricated from three types of gold alloys (Type IV, Type II and low-gold) and a Co-Cr alloy. Each gold alloy was laser-welded to Co-Cr using a dental laser-welding machine. Homogeneously-welded and non-welded control specimens were also prepared. Tensile testing was conducted and data were statistically analyzed using ANOVA. The homogeneously-welded groups showed inferior fracture load compared to corresponding control groups, except for Co-Cr. In the specimens welded heterogeneously to Co-Cr, Type IV was the greatest, followed by low-gold and Type II. There was no statistical difference (P<0.05) in fracture load between Type II control and that welded to Co-Cr. Higher elongations were obtained for Type II in all conditions, whereas the lowest elongation occurred for low-gold welded to Co-Cr. This study indicated that, of the three gold alloys tested, the Type IV gold alloy was the most suitable alloy for laser-welding to Co-Cr. PMID:19088892

  2. Tensile and Impact Toughness Properties of Gas Tungsten Arc Welded and Friction Stir Welded Interstitial Free Steel Joints

    NASA Astrophysics Data System (ADS)

    Lakshminarayanan, A. K.; Balasubramanian, V.

    2011-02-01

    Welded regions of interstitial free (IF) steel grades in the vicinity of weld center exhibits larger grains because of the prevailing thermal conditions during weld metal solidification. This often causes inferior weld mechanical properties. In the present study, tensile properties, charpy impact toughness, microhardness, microstructure, lowest hardness distribution profile, and fracture surface morphology of the gas tungsten arc welded (GTAW) and friction stir welded joints were evaluated, and the results are compared. From this investigation, it is found that friction stir welded joint of IF steel showed superior tensile and impact properties compared with GTAW joint, and this is mainly due to the formation of very fine, equiaxed microstructure in the weld zone.

  3. Improved diffusion welding and roll welding of titanium alloys

    NASA Technical Reports Server (NTRS)

    Holko, K. H.

    1973-01-01

    Auto-vacuum cleaning technique was applied to titanium parts prior to welding. This provides oxide-free welding surfaces. Diffusion welding can be accomplished in as little as five minutes of hot pressing. Roll welding can be accomplished with only ten percent deformation.

  4. The effects of sulfate reducing bacteria on stainless steel and Ni-Cr-Mo alloy weldments

    SciTech Connect

    Petersen, T.A.; Taylor, S.R.

    1995-10-01

    Previous research in this laboratory demonstrated a direct correlation between alloy composition and corrosion susceptibility of stainless steel and Ni-Cr-Mo alloy weldments exposed to lake water augmented with sulfate reducing bacteria (SRB). It was shown that lake water containing an active SRB population reduced the polarization resistance (R{sub p}) on all alloys studied including those with 9% Mo. In addition, preliminary evidence indicated that edge preparation and weld heat input were also important parameters in determining corrosion performance. This prior research, however, looked at ``doctored`` weldments in which the thermal oxide in the heat affected zone was removed. The objectives of the research presented here are to further confirm these observations using as-received welds. The materials examined (listed in increasing alloy content) are 1/4 inch thick plates of 316L, 317L, AL6XN (6% Mo), alloy 625 clad steel, alloy 625, and alloy 686. Materials were welded using the tungsten inert gas (TIG) process in an argon purged environment. In addition, 317L was welded in air to test oxide effects. All samples were prepared for welding by grinding to a V-edge, except the 625 clad steel samples which were prepared using a J-edge. Electrochemical performance of welded samples was monitored in four glass cells which could each allow exposure of 8 samples to the same environment. Two cells contained lake water inoculated with SRS, and two cells contained sterilized lake water. The open circuit potential (E{sub oc}) and R{sub p} was used to correlate corrosion susceptibility and bacterial activity with alloy composition and welding parameters.

  5. Building No. 392, interior overview with welding stalls and steel ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Building No. 392, interior overview with welding stalls and steel plate floor, view facing west-southwest - U.S. Naval Base, Pearl Harbor, Marine Railway No. 1 Accessories House & Apprentice Welding School, Additions, Intersection of Avenue B & Sixth Street, Pearl City, Honolulu County, HI

  6. Physical and welding metallurgy of Gd-enriched austenitic alloys for spent nuclear fuel applications. Part II, nickel base alloys.

    SciTech Connect

    Mizia, Ronald E.; Michael, Joseph Richard; Williams, David Brian; Dupont, John Neuman; Robino, Charles Victor

    2004-06-01

    The physical and welding a metallurgy of gadolinium- (Gd-) enriched Ni-based alloys has been examined using a combination of differential thermal analysis, hot ductility testing. Varestraint testing, and various microstructural characterization techniques. Three different matrix compositions were chosen that were similar to commercial Ni-Cr-Mo base alloys (UNS N06455, N06022, and N06059). A ternary Ni-Cr-Gd alloy was also examined. The Gd level of each alloy was {approx}2 wt-%. All the alloys initiated solidification by formation of primary austenite and terminated solidification by a Liquid {gamma} + Ni{sub 5}Gd eutectic-type reaction at {approx}1270 C. The solidification temperature ranges of the alloys varied from {approx}100 to 130 C (depending on alloy composition). This is a substantial reduction compared to the solidification temperature range to Gd-enriched stainless steels (360 to 400 C) that terminate solidification by a peritectic reaction at {approx}1060 C. The higher-temperature eutectic reaction that occurs in the Ni-based alloys is accompanied by significant improvements in hot ductility and solidification cracking resistance. The results of this research demonstrate that Gd-enriched Ni-based alloys are excellent candidate materials for nuclear criticality control in spent nuclear fuel storage applications that require production and fabrication of large amounts of material through conventional ingot metallurgy and fusion welding techniques.

  7. Microstructural characterization in dissimilar friction stir welding between 304 stainless steel and st37 steel

    SciTech Connect

    Jafarzadegan, M.; Feng, A.H.; Abdollah-zadeh, A.; Saeid, T.; Shen, J.; Assadi, H.

    2012-12-15

    In the present study, 3 mm-thick plates of 304 stainless steel and st37 steel were welded together by friction stir welding at a welding speed of 50 mm/min and tool rotational speed of 400 and 800 rpm. X-ray diffraction test was carried out to study the phases which might be formed in the welds. Metallographic examinations, and tensile and microhardness tests were used to analyze the microstructure and mechanical properties of the joint. Four different zones were found in the weld area except the base metals. In the stir zone of the 304 stainless steel, a refined grain structure with some features of dynamic recrystallization was evidenced. A thermomechanically-affected zone was characterized on the 304 steel side with features of dynamic recovery. In the other side of the stir zone, the hot deformation of the st37 steel in the austenite region produced small austenite grains and these grains transformed to fine ferrite and pearlite and some products of displacive transformations such as Widmanstatten ferrite and martensite by cooling the material after friction stir welding. The heat-affected zone in the st37 steel side showed partially and fully refined microstructures like fusion welding processes. The recrystallization in the 304 steel and the transformations in the st37 steel enhanced the hardness of the weld area and therefore, improved the tensile properties of the joint. - Highlights: Black-Right-Pointing-Pointer FSW produced sound welds between st37 low carbon steel and 304 stainless steel. Black-Right-Pointing-Pointer The SZ of the st37 steel contained some products of allotropic transformation. Black-Right-Pointing-Pointer The material in the SZ of the 304 steel showed features of dynamic recrystallization. Black-Right-Pointing-Pointer The finer microstructure in the SZ increased the hardness and tensile strength.

  8. Localized weld metal corrosion in stainless steel water tanks

    SciTech Connect

    Strum, M.J.

    1995-05-25

    The rapidly developed leaks within the TFC and TFD tanks (LLNL groundwater treatment facilities) were caused by localized corrosion within the resolidified weld metal. The corrosion was initiated by the severe oxidation of the backsides of the welds which left the exposed surfaces in a condition highly susceptible to aqueous corrosion. The propagation of surface corrosion through the thickness of the welds occurred by localized corrosive attack. This localized attack was promoted by the presence of shielded aqueous environments provided by crevices at the root of the partial penetration welds. In addition to rapid corrosion of oxidized surfaces, calcium carbonate precipitation provided an additional source of physical shielding from the bulk tank environment. Qualification testing of alternate weld procedures showed that corrosion damage can be prevented in 304L stainless steel GTA welds by welding from both sides while preventing oxidation of the tank interior through the use of an inert backing gas such as argon. Corrosion resistance was also satisfactory in GMA welds in which oxidized surfaces were postweld cleaned by wire brushing and chemically passivated in nitric acid. Further improvements in corrosion resistance are expected from a Mo-containing grade of stainless steel such as type 316L, although test results were similar for type 304L sheet welded with type 308L filler metal and type 316L sheet welded with type 316L filler metal.

  9. Experimental study and finite element analyses of electrode wear mechanisms during the resistance spot welding of galvannealed steel

    NASA Astrophysics Data System (ADS)

    Lu, Feng

    The wear mechanisms of electrodes used on resistance spot welding of galvannealed steels were studied. The study focused on the inter-relationship among the steel properties, welding parameters and electrode wear. Six different galvannealed steels were studied using a standard constant current welding test. With the same kind of Cu-Zr electrode, the tests were performed with the electrode force fixed at 600 lbs and the welding time fixed at 12 cycles for all the steels studied. The welding current is set at just below the expulsion limit for each of the steels. The microstructure and mechanical properties of these steels were examined by SEM and microhardness tests. The face profiles for electrodes subjected to various numbers of welds were examined using carbon imprint tests and low magnification optical microscopy. The alloys formed on the electrode face were studied by the EDS and WDS quantitative analyses and linescans. Changes in the microhardness of the electrode material near the electrode face during the electrode wear process were also studied. Combined with the experimental examination, a sequentially coupled finite element analysis procedure was used to analyze the detailed distribution and evolution of the electrical current, temperature and stress throughout the process of making a weld. These analyses have greatly enhanced the understanding of the experimental observations. The results of this study indicate that the welding current is the dominant factor influencing electrode life. When the electrode force and the welding time are fixed, the welding current is determined by the steel properties. Thicker steel sheets and higher steel sheet surface hardnesses will result in smaller welding current. When the electrode force and welding time are fixed, steels requiring higher welding currents will yield shorter electrode lives. With increasing welding current, the top and bottom electrodes in this study showed increasingly different wear behaviors

  10. Finite Element Simulation of Plastic Joining Processes of Steel and Aluminum Alloy Sheets

    SciTech Connect

    Mori, K.; Abe, Y.; Kato, T.

    2007-05-17

    Various high tensile strength steel sheets and an aluminum alloy sheet were joined with a self-piercing rivet. It is not easy to weld the aluminum alloy sheet and high tensile strength sheets by means of conventional resistance welding because of very different melting points. To obtain optimum joining conditions, joining defects were categorized into separation of the sheets and an inner fracture. The joining range of ultra high tensile strength steel and aluminum alloy sheets was extended by means of dies optimized by finite element simulation. The joint strength is greatly influenced by not only the strength of the sheets and rivets but also the ratio of the thickness of the lower sheet to the total thickness. In addition, mechanical clinching of high strength steel and aluminum alloy sheets was simulated.

  11. Finite Element Simulation of Plastic Joining Processes of Steel and Aluminum Alloy Sheets

    NASA Astrophysics Data System (ADS)

    Mori, K.; Abe, Y.; Kato, T.

    2007-05-01

    Various high tensile strength steel sheets and an aluminum alloy sheet were joined with a self-piercing rivet. It is not easy to weld the aluminum alloy sheet and high tensile strength sheets by means of conventional resistance welding because of very different melting points. To obtain optimum joining conditions, joining defects were categorized into separation of the sheets and an inner fracture. The joining range of ultra high tensile strength steel and aluminum alloy sheets was extended by means of dies optimized by finite element simulation. The joint strength is greatly influenced by not only the strength of the sheets and rivets but also the ratio of the thickness of the lower sheet to the total thickness. In addition, mechanical clinching of high strength steel and aluminum alloy sheets was simulated.

  12. Friction Stir Spot Welding of Advanced High Strength Steels

    SciTech Connect

    Santella, Michael L; Hovanski, Yuri; Grant, Glenn J; Frederick, D Alan; Dahl, Michael E

    2009-02-01

    Friction stir spot welding was used to join two advanced high-strength steels using polycrystalline cubic boron nitride tooling. Numerous tool designs were employed to study the influence of tool geometry on weld joints produced in both DP780 and a hot-stamp boron steel. Tool designs included conventional, concave shouldered pin tools with several pin configurations; a number of shoulderless designs; and a convex, scrolled shoulder tool. Weld quality was assessed based on lap shear strength, microstructure, microhardness, and bonded area. Mechanical properties were functionally related to bonded area and joint microstructure, demonstrating the necessity to characterize processing windows based on tool geometry.

  13. Friction Stir Spot Welding of Advanced High Strength Steels

    SciTech Connect

    Hovanski, Yuri; Santella, M. L.; Grant, Glenn J.

    2009-12-28

    Friction stir spot welding was used to join two advanced high-strength steels using polycrystalline cubic boron nitride tooling. Numerous tool designs were employed to study the influence of tool geometry on weld joints produced in both DP780 and a hot-stamp boron steel. Tool designs included conventional, concave shouldered pin tools with several pin configurations; a number of shoulderless designs; and a convex, scrolled shoulder tool. Weld quality was assessed based on lap shear strength, microstructure, microhardness, and bonded area. Mechanical properties were functionally related to bonded area and joint microstructure, demonstrating the necessity to characterize processing windows based on tool geometry.

  14. Corrosion evaluation of stainless steel root weld shielding

    SciTech Connect

    Gorog, M.; Sawyer, L.A.

    1999-07-01

    The effect of five shielding methods for gas tungsten arc root pass welds, on the corrosion resistance of stainless steel was evaluated in two laboratory solutions. The first experiment was performed in 6% ferric chloride solution, a test designed to corrode stainless steel. The second experiment was performed in a simulated paper machine white water solution that contained hydrogen peroxide. Argon shielding produced excellent results by maintaining corrosion resistance in both solutions. Nitrogen purging and flux coated TIG rod techniques produced variable results. Paste fluxes and welding without shielding are not recommended for root protection. They performed very poorly with the welds corroding in both tests.

  15. Analysis and Comparison of Aluminum Alloy Welded Joints Between Metal Inert Gas Welding and Tungsten Inert Gas Welding

    NASA Astrophysics Data System (ADS)

    Zhao, Lei; Guan, Yingchun; Wang, Qiang; Cong, Baoqiang; Qi, Bojin

    2015-09-01

    Surface contamination usually occurs during welding processing and it affects the welds quality largely. However, the formation of such contaminants has seldom been studied. Effort was made to study the contaminants caused by metal inert gas (MIG) welding and tungsten inert gas (TIG) welding processes of aluminum alloy, respectively. SEM, FTIR and XPS analysis was carried out to investigate the microstructure as well as surface chemistry. These contaminants were found to be mainly consisting of Al2O3, MgO, carbide and chromium complexes. The difference of contaminants between MIG and TIG welds was further examined. In addition, method to minimize these contaminants was proposed.

  16. Stress corrosion cracking resistance of alloys 600 and 690 and compatible weld metals in BWRs: Final report

    SciTech Connect

    Page, R. A.; McMinn, A.

    1988-07-01

    The relative susceptibilities of alloy 600 and 690 base metals and I-82, I-182, R-127 and R-135 weld metals to intergranular stress corrosion cracking (IGSCC) in either pure water or a simulated resin intrusion environment at 288/degree/C were evaluated. Alloy 600, I-182, and I-82 weld metals were susceptible to various degrees of IGSCC in oxygen containing pure water when creviced, and immune to IGSCC when uncreviced. Alloy 690 was immune to IGSCC under all pure water conditions. Alloy 500, alloy 690, I-182, and I-82 were all susceptible to cracking in the simulated resin intrusion environment, although alloy 690 exhibited the greatest resistance to SCC. The high chromium experimental weld alloy were immune to cracking under all conditions examined. The IGSCC susceptibility of seven different weld metals used to weld alloy 600 and A508 were also evaluated in the resin intrusion environment at 288/degree/C. Weldments made with I-625, I-182, and I-82 (GTAW) were the most susceptible, whereas welds made with I-132 were the least susceptible. Most of the weldments failed at the fusion line between the weld metal and the A508 steel, and the SCC susceptibility increased with increasing hardness measured at the fusion line. There was no effect of crevice condition or heat treatment on SCC susceptibility. The SCC susceptibility of Type 316 NG stainless steel welded with R-127, R-135, I-72 and Type 308L weld metals was evaluated in pure water and resin intrusion environments at 288/degree/C. All of the materials were immune to SCC in the pure water environment. In the resin intrusion environment, both the I-72 and R-135 weld metals were immune to SACC, but the R-127 and Type 308L weld metals exhibited SCC. The Type 316 NG stainless steel was susceptible to transgranular SCC in the resin intrusion environment, except when welded with I-72, in which case it was immune. 36 refs., 4 tabs.

  17. Laser welding of low carbon steel and thermal stress analysis

    NASA Astrophysics Data System (ADS)

    Yilbas, B. S.; Arif, A. F. M.; Abdul Aleem, B. J.

    2010-07-01

    Laser welding of mild steel sheets is carried out under nitrogen assisting gas ambient. Temperature and stress fields are computed in the welding region through the finite element method. The residual stress developed in the welding region is measured using the XRD technique and the results are compared with the predictions. Optical microscopy and the SEM are used for the metallurgical examination of the welding sites. It is found that von Mises stress attains high values in the cooling cycle after the solidification of the molten regions. The residual stress predicted agreed well with the XRD results.

  18. Microstructure of heat resistant chromium steel weld metals

    NASA Astrophysics Data System (ADS)

    Andrén, Hans-Olof; Cai, Guangjun; Svensson, Lars-Erik

    1995-03-01

    The microstructure of weld metals of 2.25Cr-1Mo, 5Cr-0.5Mo, 9Cr-1Mo and 12Cr-1Mo type steels was studied with electron microscopy and atom probe field ion microscopy. Many different types of carbides and nitrides precipitated during welding and post-weld heat treatment (MC, M 2C, M 3C, M 7C 3, M 23C 6, MN, M 2N). The eutectoid decomposition of retained austenite gave large aggregates of carbides which were found to be detrimental to the impact toughness of the weld metal.

  19. Characterization of ferritic G. M. A. weld deposits in 9% Ni steel for cryogenic applications

    SciTech Connect

    Mahin, K.W.

    1980-04-01

    Low temperature containment vessels of 9% Ni are normally fabricated using the shielded metal arc (S.M.A.W.) or the gas metal arc (G.M.A.W.) welding processes. Available filler metals compatible with these processes are highly alloyed austenitics, whose strength levels undermatch those of the base plate. A more efficient weld joint would be a low alloy ferritic deposit. Although acceptable matching ferritic gas tungsten arc weld (G.T.A.W.) wires have been developed, similar progress has not been made in the area of ferritic G.M.A. weld wires. Most of the prior work in this area has focused on correlating composition with mechanical properties, without a corresponding evaluation of resultant microstructure. The study presented focused on establishing correlations between chemistry, microstructure and mechanical properties for four different ferritic G.M.A. weld deposits in 9% Ni steel, with the purpose of developing a better understanding of the factors controlling the 77K (-196/sup 0/C) toughness behavior of these weld metals. Microstructural characterization was carried out using standard optical and scanning electron microscopes, as well as a variety of advanced analytical techniques, including transmission electron microscopy (T.E.M.), scanning T.E.M., Moessbauer spectroscopy and Auger electron spectroscopy.

  20. Study of Mechanical Properties and Characterization of Pipe Steel welded by Hybrid (Friction Stir Weld + Root Arc Weld) Approach

    SciTech Connect

    Lim, Yong Chae; Sanderson, Samuel; Mahoney, Murray; Wasson, Andrew J; Fairchild, Doug P; Wang, Yanli; Feng, Zhili

    2015-01-01

    Friction stir welding (FSW) has recently attracted attention as an alternative construction process for gas/oil transportation applications due to advantages compared to fusion welding techniques. A significant advantage is the ability of FSW to weld the entire or nearly the entire wall thickness in a single pass, while fusion welding requires multiple passes. However, when FSW is applied to a pipe or tube geometry, an internal back support anvil is required to resist the plunging forces exerted during FSW. Unfortunately, it may not be convenient or economical to use internal backing support due to limited access for some applications. To overcome this issue, ExxonMobil recently developed a new concept, combining root arc welding and FSW. That is, a root arc weld is made prior to FSW that supports the normal loads associated with FSW. In the present work, mechanical properties of a FSW + root arc welded pipe steel are reported including microstructure and microhardness.

  1. Laser welding of aeronautical and automobile aluminum alloys

    NASA Astrophysics Data System (ADS)

    Boukha, Z.; Sánchez-Amaya, J. M.; Amaya-Vázquez, M. R.; González-Rovira, L.; Botana, F. J.

    2012-04-01

    Laser beam welding (LBW) show clear advantages compared with other techniques, as the low heat input, the high localization ability, the high welding speed, the high flexibility, the high weld quality and the high production rate. However, its applicability to aluminum alloys is limited, as they generally have high reflectivity, high thermal conductivity and low viscosity. In the present study, it is analyzed the laser weldability of four aluminum alloys (2024, 5083, 6082 and 7075). High penetration butt welds could be obtained with a high power diode laser under conduction regime. The properties of the weld beads such as the microstructure and microhardness were analyzed. A linear function between the input laser fluence and the volume of melted material was obtained for the four alloys.

  2. Development of laser welding techniques for vanadium alloys

    SciTech Connect

    Strain, R.V.; Leong, K.H.; Smith, D.L.

    1996-04-01

    Laser welding is potentially advantageous because of its flexibility and the reduced amount of material affected by the weld. Lasers do not require a vacuum (as do electron beam welders) and the welds they produce high depth-to-width ratios. Scoping with a small pulsed 50 J YAG laser indicated that lasers could produce successful welds in vanadium alloy (V-5%Cr-5%Ti) sheet (1 mm thick) when the fusion zone was isolated from air. The pulsed laser required an isolating chamber filled with inert gas to produce welds that did not contain cracks and showed only minor hardness increases. Following the initial scoping tests, a series of tests were preformed with a 6 kW continuous CO{sub 2} laser. Successful bead-on-plate welds were made on V-4%Cr-4%Ti and V-5%Cr-5%Ti alloys to depths of about 4 mm with this laser.

  3. Friction Stir Welding of ODS and RAFM Steels

    NASA Astrophysics Data System (ADS)

    Yu, Zhenzhen; Feng, Zhili; Hoelzer, David; Tan, Lizhen; Sokolov, Mikhail A.

    2015-09-01

    Advanced structural materials such as oxide dispersion strengthened steels and reduced-activation ferritic/martensitic steels are desired in fusion reactors as primary candidate materials for first wall and blanket structures, due to their excellent radiation and high-temperature creep resistance. However, their poor fusion weldability has been the major technical challenge limiting practical applications. For this reason, solid-state friction stir welding (FSW) has been considered for such applications. In this work, the effect of FSW parameters on joining similar and dissimilar advanced structural steels was investigated. Scanning electron microscopy and electron backscatter diffraction methods were used to reveal the effects of FSW on grain size, micro-texture distribution, and phase stability. Hardness mapping was performed to evaluate mechanical properties. Post weld heat treatment was also performed to tailor the microstructure in the welds in order to match the weld zone mechanical properties to the base material.

  4. Friction Stir Welding of ODS and RAFM Steels

    DOE PAGESBeta

    Yu, Zhenzhen; Feng, Zhili; Hoelzer, David; Tan, Lizhen; Sokolov, Mikhail A.

    2015-09-14

    Advanced structural materials such as oxide dispersion strengthened steels and reduced-activation ferritic/martensitic steels are desired in fusion reactors as primary candidate materials for first wall and blanket structures, due to their excellent radiation and high-temperature creep resistance. However, their poor fusion weldability has been the major technical challenge limiting practical applications. For this reason, solid-state friction stir welding (FSW) has been considered for such applications. In this paper, the effect of FSW parameters on joining similar and dissimilar advanced structural steels was investigated. Scanning electron microscopy and electron backscatter diffraction methods were used to reveal the effects of FSW onmore » grain size, micro-texture distribution, and phase stability. Hardness mapping was performed to evaluate mechanical properties. Finally, post weld heat treatment was also performed to tailor the microstructure in the welds in order to match the weld zone mechanical properties to the base material.« less

  5. Friction Stir Welding of ODS and RAFM Steels

    SciTech Connect

    Yu, Zhenzhen; Feng, Zhili; Hoelzer, David; Tan, Lizhen; Sokolov, Mikhail A.

    2015-09-14

    Advanced structural materials such as oxide dispersion strengthened steels and reduced-activation ferritic/martensitic steels are desired in fusion reactors as primary candidate materials for first wall and blanket structures, due to their excellent radiation and high-temperature creep resistance. However, their poor fusion weldability has been the major technical challenge limiting practical applications. For this reason, solid-state friction stir welding (FSW) has been considered for such applications. In this paper, the effect of FSW parameters on joining similar and dissimilar advanced structural steels was investigated. Scanning electron microscopy and electron backscatter diffraction methods were used to reveal the effects of FSW on grain size, micro-texture distribution, and phase stability. Hardness mapping was performed to evaluate mechanical properties. Finally, post weld heat treatment was also performed to tailor the microstructure in the welds in order to match the weld zone mechanical properties to the base material.

  6. Effects of Flux Precoating and Process Parameter on Welding Performance of Inconel 718 Alloy TIG Welds

    NASA Astrophysics Data System (ADS)

    Lin, Hsuan-Liang; Wu, Tong-Min; Cheng, Ching-Min

    2014-01-01

    The purpose of this study is to investigate the effect of activating flux on the depth-to-width ratio (DWR) and hot cracking susceptibility of Inconel 718 alloy tungsten inert gas (TIG) welds. The Taguchi method is employed to investigate the welding parameters that affect the DWR of weld bead and to achieve optimal conditions in the TIG welds that are coated with activating flux in TIG (A-TIG) process. There are eight single-component fluxes used in the initial experiment to evaluate the penetration capability of A-TIG welds. The experimental results show that the Inconel 718 alloy welds precoated with 50% SiO2 and 50% MoO3 flux were provided with better welding performance such as DWR and hot cracking susceptibility. The experimental procedure of TIG welding process using mixed-component flux and optimal conditions not only produces a significant increase in DWR of weld bead, but also decreases the hot cracking susceptibility of Inconel 718 alloy welds.

  7. Formability Analysis of Diode-Laser-Welded Tailored Blanks of Advanced High-Strength Steel Sheets

    NASA Astrophysics Data System (ADS)

    Panda, S. K.; Baltazar Hernandez, V. H.; Kuntz, M. L.; Zhou, Y.

    2009-08-01

    Currently, advances due to tailored blanking can be enhanced by the development of new grades of advanced high-strength steels (HSSs), for the further weight reduction and structural improvement of automotive components. In the present work, diode laser welds of three different grades of advanced high-strength dual-phase (DP) steel sheets (with tensile strengths of 980, 800, and 450 MPa) to high-strength low-alloy (HSLA) material were fabricated by applying the proper welding parameters. Formability in terms of Hecker’s limiting dome height (LDH), the strain distribution on the hemispherical dome surface, the weld line movement during deformation, and the load-bearing capacity during the stretch forming of these different laser-welded blanks were compared. Finite element (FE) analysis of the LDH tests of both the parent metals and laser-welded blanks was done using the commercially available software package LS-DYNA (Livermore Software Technology Corporation, Livermore, CA); the results compared well with the experimental data. It was also found that the LDH was not affected by the soft zone or weld zone properties; it decreased, however, with an increase in a nondimensional parameter, the “strength ratio” (SR). The weld line movement during stretch forming is an indication of nonuniform deformation resulting in a decrease in the LDH. In all the dissimilar weldments, fracture took place on the HSLA side, but the fracture location shifted to near the weld line (at the pole) in tailor-welded blanks (TWBs) of a higher strength ratio.

  8. Friction stir spot welding of hot-stamped boron steel

    SciTech Connect

    Hovanski, Yuri; Santella, M. L.; Grant, Glenn J.

    2007-11-01

    Hot-stamped, boron steel was successfully joined via friction stir spot welding using polycrystalline cubic boron nitride tooling. The resulting microstructure, microhardness and mechanical properties are reported, including a brief look into failure mechanisms. Relationships between the unique mechanical mixing, phase transformations and failure initiation sites associated with joining martensitic steels are characterized.

  9. Corrosion behavior of a welded stainless-steel orthopedic implant.

    PubMed

    Reclaru, L; Lerf, R; Eschler, P Y; Meyer, J M

    2001-02-01

    The corrosion behavior of combinations of materials used in an orthopedic implant: the spherical part (forged or forged and annealed) constituting the head, the weld (tungsten inert gas (TIG) or electron beam (EB) techniques), and the cylindrical part (annealed) constituting the shaft of a femoral prosthesis - has been investigated. Open-circuit potentials, potentiodynamic curves, Tafel slope, mixed potential theory and susceptibility to intergranular attack are electrochemical and chemical procedures selected for this work. Electrochemical measurements using a microelectrode have been made in the following zones: spherical part, cylindrical part, weld, and weld/sphere, and weld/shaft interfaces. To detect intergranular attack, the Strauss test has been used. At the interfaces, corrosion currents, measured (Icorr) and predicted (Icouple) are low, in the order of the pico- to nanoampere. The electrochemical behavior of the electron beam (EB) weld is better than that of the tungsten inert gas (TIG). Welds at interfaces can behave either anodically or cathodically. It is better if welds, which are sensitive parts of the femoral prosthesis, behave cathodically. In this way, the risk of starting localized corrosion (pitting, crevice or intergranular corrosion) from a galvanic couple, remains low. From this point of view, the sample with the EB weld offers the best behavior. All the other samples containing a TIG type of weld exhibit a less favorable behavior. The mechanical treatments (forged, and forged and annealed) of the steel sphere did not show any difference in the corrosion behavior. No intergranular corrosion has been observed at the weld/steel interface for unsensitized samples. With sensitized samples, however, a TIG sample has exhibited some localized intergranular corrosion at a distance of 500 microm along the weld/stainless steel (sphere) interface. PMID:11197502

  10. Surface preparation effects on GTA (gas tungsten arc) weld penetration in JBK-75 stainless steel

    SciTech Connect

    Campbell, R.D.; Heiple, C.R.; Sturgill, P.L.; Robertson, A.M.; Jamsay, R.

    1989-01-01

    The results of a study are reported here on the effects of surface preparation on the shape of GTA welds on JBK-75, an austenitic precipitation hardenable stainless steel similar to A286. Minor changes in surface (weld groove) preparation produced substantial changes in the penetration characteristics and welding behavior of this alloy. Increased and more consistent weld penetration (higher d/w ratios) along with improved arc stability and less arc wander result from wire brushing and other abrasive surface preparations, although chemical and machining methods did not produce any improvement in penetration. Abrasive treatments roughen the surface, increase the surface area, and increase the surface oxide thickness. The increased weld d/w ratio is attributed to oxygen added to the weld pool from the surface oxide on the base metal. The added oxygen alters the surface-tension driven fluid flow pattern in the weld pool. Similar results were observed with changes in filler wire surface oxide thickness, caused by changes in wire production conditions. 15 refs., 14 figs., 4 tabs.

  11. Thermal-microstructural analysis of multipass welding of Cr/Mo steels

    SciTech Connect

    Oddy, A.S.; McDill, J.M.J.; Braid, J.E.M.

    1996-12-31

    Full weave repair techniques for Cr/Mo steels without post-weld heat treatment are the subject of many research programs. Coupled thermal-microstructural analyses could preselect candidate welding parameters and reduce the cost and time required. In multipass welds, microstructural simulations require transient reaustenization, austenite decomposition for arbitrary thermal cycles including reheating and tempering. Finite element thermal analysis of a three-layer, weaved weld and the microstructural analysis of the heat-affected zone (HAZ) are described. Significant variation is found in properties governing reaustenization, austenite grain growth, austenite decomposition and hardness. Hardness measurements vary by up to {+-}30 HV on the same sample. Alloy differences within the allowable range lead to HAZ hardness variations of 30 HV in multipass welds. Predicted HAZ hardnesses of the three-layer weld were in good agreement with measurements. The final microstructure was also in good agreement with experiment. The predicted HAZ width was slightly wider than was measured. This difference is easily accounted for by the variation reported in weld parameters.

  12. High-strength, low-alloy steels.

    PubMed

    Rashid, M S

    1980-05-23

    High-strength, low-alloy (HSLA) steels have nearly the same composition as plain carbon steels. However, they are up to twice as strong and their greater load-bearing capacity allows engineering use in lighter sections. Their high strength is derived from a combination of grain refinement; precipitation strengthening due to minor additions of vanadium, niobium, or titanium; and modifications of manufacturing processes, such as controlled rolling and controlled cooling of otherwise essentially plain carbon steel. HSLA steels are less formable than lower strength steels, but dualphase steels, which evolved from HSLA steels, have ferrite-martensite microstructures and better formability than HSLA steels of similar strength. This improved formability has substantially increased the utilization potential of high-strength steels in the manufacture of complex components. This article reviews the development of HSLA and dual-phase steels and discusses the effects of variations in microstructure and chemistry on their mechanical properties. PMID:17772810

  13. Nd:YAG laser welding of coated sheet steel

    SciTech Connect

    Graham, M.P.; Kerr, H.W.; Weckman, D.C.

    1994-12-31

    Coated sheet steels are used extensively in the automotive industry for the fabrication of automobile body components; however, their reduced weldability by the traditional welding processes has led to numerous studies into the use of alternate process such as laser welding. In this paper, we present a modified joint geometry which allows high quality lap welds of coated sheet steels to be made by laser welding processes. Hot-dipped galvanized sheet (16 gauge), with a 60 g/m zinc coating was used in this study. A groove was created in the top sheet of a specimen pair by pressing piano wires of various diameters into the sheet. The specimens were clamped together in a lag-joint configuration such that they were in contacted only along the grove projection. A parametric study was conducted using the variables of welding speed, laser mean power (685 W, 1000 W and 1350 W), and grove size. Weld quality and weld pool dimensions were assessed using metallurgical cross-sections and image analysis techniques. Acceptable quality seam welds were produced in the galvanized sheet steel with both grove sizes when using 1000 W and 1350 W laser mean powers and a range of welding speeds. Results of the shear-tensile tests showed that high loads to failure, with failure occurring in the parent material, were predominately found in welds produced at speeds over 1.2 m/min and when using the high mean laser powers: 1000 W and 1350 W. A modified lap joint geometry, in which a groove is pre-placed in the top sheet of the lap-joint configuration, has been developed which permits laser welding of coated sheet steels. Good quality seam welds have been produced in 16 gauge galvanized sheet steels at speeds up to 2.7 m/min using a 2 kW CW Nd:YAG laser operating at 1350 W laser mean power. Weld quality was not affected by changes in groove size.

  14. Electron Beam Welding of Duplex Steels with using Heat Treatment

    NASA Astrophysics Data System (ADS)

    Schwarz, Ladislav; Vrtochová, Tatiana; Ulrich, Koloman

    2010-01-01

    This contribution presents characteristics, metallurgy and weldability of duplex steels with using concentrated energy source. The first part of the article describes metallurgy of duplex steels and the influence of nitrogen on their solidification. The second part focuses on weldability of duplex steels with using electron beam aimed on acceptable structure and corrosion resistance performed by multiple runs of defocused beam over the penetration weld.

  15. Fusion Welding of AerMet 100 Alloy

    SciTech Connect

    ENGLEHART, DAVID A.; MICHAEL, JOSEPH R.; NOVOTNY, PAUL M.; ROBINO, CHARLES V.

    1999-08-01

    A database of mechanical properties for weldment fusion and heat-affected zones was established for AerMet{reg_sign}100 alloy, and a study of the welding metallurgy of the alloy was conducted. The properties database was developed for a matrix of weld processes (electron beam and gas-tungsten arc) welding parameters (heat inputs) and post-weld heat treatment (PWHT) conditions. In order to insure commercial utility and acceptance, the matrix was commensurate with commercial welding technology and practice. Second, the mechanical properties were correlated with fundamental understanding of microstructure and microstructural evolution in this alloy. Finally, assessments of optimal weld process/PWHT combinations for cotildent application of the alloy in probable service conditions were made. The database of weldment mechanical properties demonstrated that a wide range of properties can be obtained in welds in this alloy. In addition, it was demonstrated that acceptable welds, some with near base metal properties, could be produced from several different initial heat treatments. This capability provides a means for defining process parameters and PWHT's to achieve appropriate properties for different applications, and provides useful flexibility in design and manufacturing. The database also indicated that an important region in welds is the softened region which develops in the heat-affected zone (HAZ) and analysis within the welding metallurgy studies indicated that the development of this region is governed by a complex interaction of precipitate overaging and austenite formation. Models and experimental data were therefore developed to describe overaging and austenite formation during thermal cycling. These models and experimental data can be applied to essentially any thermal cycle, and provide a basis for predicting the evolution of microstructure and properties during thermal processing.

  16. Mechanical Properties and Microstructural Evolution of Welded Eglin Steel

    NASA Astrophysics Data System (ADS)

    Leister, Brett M.

    affected zone in the as-simulated condition is lower than that of the base metal. Post-weld heat treatments (PWHT) have been shown to increase the toughness of the HAZ, but at the expense of strength. In addition, certain combinations of PWHTs within specific HAZ regions have exhibited low toughness caused by tempered martensite embrittlement or intergranular failure. Synchrotron X-ray diffraction data has shown that Eglin steel has retained austenite in the fine-grain HAZ in the as-simulated condition. In addition, alloy carbides (M23C 6, M2C, M7C3) have been observed in the diffraction spectra for the fine-grain and coarse-grain HAZ following a PWHT of 700 °C / 4 hours. A first attempt at thermodynamic modeling has been undertaken using MatCalc to try to predict the evolution of carbides in the HAZ following thermal cycling and PWHT.

  17. Welding of Vanadium, Tantalum, 304L and 21-6-9 Stainless Steels, and Titanium Alloys at Lawrence Livermore National Laboratory using a Fiber Delivered 2.2 kW Diode Pumped CW Nd:YAG Laser

    SciTech Connect

    Palmer, T; Elmer, J; Pong, R; Gauthier, M

    2006-06-16

    This report summarizes the results of a series of laser welds made between 2003 and 2005 at Lawrence Livermore National Laboratory (LLNL). The results are a compilation of several, previously unpublished, internal LLNL reports covering the laser welding of vanadium, tantalum, 304L stainless steel, 21-6-9 (Nitronic 40) steel, and Ti-6Al-4V. All the welds were made using a Rofin Sinar DY-022 diode pumped continuous wave Nd:YAG laser. Welds are made at sharp focus on each material at various power levels and travel speeds in order to provide a baseline characterization of the performance of the laser welder. These power levels are based on measurements of the output power of the laser system, as measured by a power meter placed at the end of the optics train. Based on these measurements, it appears that the system displays a loss of approximately 10% as the beam passes through the fiber optic cable and laser optics. Since the beam is delivered to the fixed laser optics through a fiber optic cable, the effects of fiber diameter are also briefly investigated. Because the system utilizes 1:1 focusing optics, the laser spot size at sharp focus generally corresponds to the diameter of the fiber with which the laser is delivered. Differences in the resulting weld penetration in the different materials system are prevalent, with the welds produced on the Nitronic 40 material displaying the highest depths (> 5 mm) and minimal porosity. A Primes focusing diagnostic has also been installed on this laser system and used to characterize the size and power density distribution of the beams as a function of both power and focus position. Further work is planned in which this focusing diagnostic will be used to better understand the effects of changes in beam properties on the resulting weld dimensions in these and other materials systems.

  18. Ultrasonic Butt Welding of Aluminum, Copper and Steel Plate Specimens

    NASA Astrophysics Data System (ADS)

    Tsujino, Jiromaru; Ueoka, Tetsugi; Fujita, Yuki; Watanabe, Ichiro

    1994-05-01

    Characteristics of ultrasonic butt welding of the same and of different metal plates are studied. The ultrasonic vibration source used has eight 15-kHz bolt-clamped Langevin-type lead-zircon-titanate (PZT) transducers of 60 mm diameter and is driven by a 50-kW static induction thyristor power amplifier. Welding specimens of aluminum, copper and steel plates of 6 mm thickness are successfully joined end-to-end with weld strength almost equal to that of an aluminum specimen. The input power required for aluminum, aluminum and copper, and aluminum and steel plates are about 5 kW/cm2, 5.5 kW/cm2 and 3.5 kW/cm2, respectively. The measured temperature rise at the specimen side surface and elongation of the welded specimen during a tensile test correspond to weld strength. The hardness distributions along the weldment of welded specimens are measured and the maximum temperature rise in an aluminum welding specimen is estimated to be over 480°C from the reduction of hardness at a welding specimen surface.

  19. Residual stresses in a multi-pass weld in an austenitic stainless steel plate before and after thermal stress relief

    SciTech Connect

    Spooner, S.; Wang, X.L.; Hubbard, C.R.; David, S.A.

    1994-06-01

    Changes in residual stresses due to thermal stress relief were determined in a welded 1/2 in. thick 304 stainless steel plate from two residual stress maps determined with the neutron diffraction technique. The 304 stainless plate was made from two 6 {times} 12 {times} 1/2 in. pieces joined along the length by a gas tungsten arc welding process. Multi-pass welds were made with a semiautomatic welding machine employing cold-wire feed of type 308 stainless steel filler alloy. The thermal stress relief treatment consisted of heating to 1150 F, holding for one hour at temperature and then air cooling. Strain components were measured along the weld direction (longitudinal), perpendicular to the weld line in the plate (transverse), and normal to the plate. Measurements were confined to the plane bisecting the weld at the center of the plate. The strain components were converted to stresses assuming that the measured strains were along the principal axes of the strain tensor. Parameters used in the calculation were E=224 GPa and v=0.25. As-welded longitudinal stresses are compressive in the base metal and become strongly tensile through the heat affected zone and into the fusion zone. The transverse stresses follow the longitudinal trend but with a lower magnitude while the normal stresses are small throughout. The stress relief treatment reduced the magnitudes of all the stresses. In the weld zone the longitudinal stress was lowered by 30% and the spatial range of residual stresses was reduced as well.

  20. Production, fabrication, and performance of alloy 625 clad steel for aggressive corrosive environments

    SciTech Connect

    Stevens, C.E.; Ross, R.W. Jr.

    1986-06-01

    INCONEL/sup */ alloy 625 is a nickel-chromium-molybdenum-columbium alloy used in aggressive corrosive applications where high strength, fabricability, and outstanding corrosion resistance are required. Because of these properties, the alloy is used by the power and chemical industries in a variety of components in coal-fired, nuclear, and chemical process plants. However, widespread use of INCONEL alloy 625 is limited due to its cost. There is a need, notably in utility flue gas desulfurization systems (scrubbers) for an economical, highly corrosive-resistant material. To satisfy this need, INCONEL alloy 625 thin-gauge clad steel plate was developed by Lukens Steel Company. The corrosion resistance of INCONEL alloy 625 in several aggressive corrosive environments will be reviewed. Additionally, this paper will describe methods used to manufacture, fabricate, and weld INCONEL alloy 625 clad plate. Field test evaluation programs conducted at six power plant scrubber systems will also be reported.

  1. Solidification behavior and structure of Al-Cu alloy welds

    SciTech Connect

    Brooks, J.A.; Li, M.; Yang, N.C.Y.

    1997-09-01

    The microsegregation behavior of electron beam (EB) and gas tungsten arc (GTA) welds of Al-Cu alloys covering a range from 0.19 to 7.74 wt% Cu were characterized for dendrite core concentrations and fraction eutectic solidification. Although a single weld speed of 12.7 mm/sec was used, some differences were observed in the segregation behavior of the two weld types. The microsegregation behavior was also modeled using a finite differences technique considering dendrite tip and eutectic undercooling and solid state diffusion. Fairly good agreement was observed between measured and calculated segregation behavior although differences between the two weld types could not be completely accounted for. The concept of dendrite tip undercooling was used to explain the formation of a single through thickness centerline grain in the higher alloy content GTA welds.

  2. Liquid Metal Embrittlement in Resistance Spot Welding and Hot Tensile Tests of Surface-refined TWIP Steels

    NASA Astrophysics Data System (ADS)

    Barthelmie, J.; Schram, A.; Wesling, V.

    2016-03-01

    Automotive industry strives to reduce vehicle weight and therefore fuel consumption and carbon dioxide emissions. Especially in the auto body, material light weight construction is practiced, but the occupant safety must be ensured. These requirements demand high-strength steels with good forming and crash characteristics. Such an approach is the use of high- manganese-content TWIP steels, which achieve strengths of around 1,000 MPa and fracture strains of more than 60%. Welding surface-refined TWIP steels reduces their elongation at break and produces cracks due to the contact with liquid metal and the subsequent liquid metal embrittlement (LME). The results of resistance spot welds of mixed joints of high-manganese- content steel in combination with micro-alloyed ferritic steel and hot tensile tests are presented. The influence of different welding parameters on the sensitivity to liquid metal embrittlement is investigated by means of spot welding. In a high temperature tensile testing machine, the influence of different parameters is determined regardless of the welding process. Defined strains just below or above the yield point, and at 25% of elongation at break, show the correlation between the applied strain and liquid metal crack initiation. Due to the possibility to carry out tensile tests on a wide range of temperatures, dependencies of different temperatures of the zinc coating to the steel can be identified. Furthermore, the attack time of the zinc on the base material is investigated by defined heating periods.

  3. 49 CFR 178.53 - Specification 4D welded steel cylinders for aircraft use.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Specification 4D welded steel cylinders for...) SPECIFICATIONS FOR PACKAGINGS Specifications for Cylinders § 178.53 Specification 4D welded steel cylinders for aircraft use. (a) Type, size, and service pressure. A DOT 4D cylinder is a welded steel sphere...

  4. 49 CFR 178.56 - Specification 4AA480 welded steel cylinders.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Specification 4AA480 welded steel cylinders. 178... FOR PACKAGINGS Specifications for Cylinders § 178.56 Specification 4AA480 welded steel cylinders. (a) Type, size, and service pressure. A DOT 4AA480 cylinder is a welded steel cylinder having a...

  5. 49 CFR 178.50 - Specification 4B welded or brazed steel cylinders.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Specification 4B welded or brazed steel cylinders... FOR PACKAGINGS Specifications for Cylinders § 178.50 Specification 4B welded or brazed steel cylinders. (a) Type, size, and service pressure. A DOT 4B is a welded or brazed steel cylinder with...

  6. 49 CFR 178.53 - Specification 4D welded steel cylinders for aircraft use.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Specification 4D welded steel cylinders for...) SPECIFICATIONS FOR PACKAGINGS Specifications for Cylinders § 178.53 Specification 4D welded steel cylinders for aircraft use. (a) Type, size, and service pressure. A DOT 4D cylinder is a welded steel sphere...

  7. 49 CFR 178.50 - Specification 4B welded or brazed steel cylinders.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Specification 4B welded or brazed steel cylinders... FOR PACKAGINGS Specifications for Cylinders § 178.50 Specification 4B welded or brazed steel cylinders. (a) Type, size, and service pressure. A DOT 4B is a welded or brazed steel cylinder with...

  8. 49 CFR 178.56 - Specification 4AA480 welded steel cylinders.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Specification 4AA480 welded steel cylinders. 178... FOR PACKAGINGS Specifications for Cylinders § 178.56 Specification 4AA480 welded steel cylinders. (a) Type, size, and service pressure. A DOT 4AA480 cylinder is a welded steel cylinder having a...

  9. 49 CFR 178.53 - Specification 4D welded steel cylinders for aircraft use.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Specification 4D welded steel cylinders for...) SPECIFICATIONS FOR PACKAGINGS Specifications for Cylinders § 178.53 Specification 4D welded steel cylinders for aircraft use. (a) Type, size, and service pressure. A DOT 4D cylinder is a welded steel sphere...

  10. 49 CFR 178.58 - Specification 4DA welded steel cylinders for aircraft use.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Specification 4DA welded steel cylinders for...) SPECIFICATIONS FOR PACKAGINGS Specifications for Cylinders § 178.58 Specification 4DA welded steel cylinders for aircraft use. (a) Type, size, and service pressure. A DOT 4DA is a welded steel sphere (two...

  11. 49 CFR 178.56 - Specification 4AA480 welded steel cylinders.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Specification 4AA480 welded steel cylinders. 178... FOR PACKAGINGS Specifications for Cylinders § 178.56 Specification 4AA480 welded steel cylinders. (a) Type, size, and service pressure. A DOT 4AA480 cylinder is a welded steel cylinder having a...

  12. 49 CFR 178.47 - Specification 4DS welded stainless steel cylinders for aircraft use.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Specification 4DS welded stainless steel cylinders...) SPECIFICATIONS FOR PACKAGINGS Specifications for Cylinders § 178.47 Specification 4DS welded stainless steel... stainless steel sphere (two seamless hemispheres) or circumferentially welded cylinder both with a...

  13. 49 CFR 178.58 - Specification 4DA welded steel cylinders for aircraft use.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Specification 4DA welded steel cylinders for...) SPECIFICATIONS FOR PACKAGINGS Specifications for Cylinders § 178.58 Specification 4DA welded steel cylinders for aircraft use. (a) Type, size, and service pressure. A DOT 4DA is a welded steel sphere (two...

  14. 49 CFR 178.47 - Specification 4DS welded stainless steel cylinders for aircraft use.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Specification 4DS welded stainless steel cylinders...) SPECIFICATIONS FOR PACKAGINGS Specifications for Cylinders § 178.47 Specification 4DS welded stainless steel... stainless steel sphere (two seamless hemispheres) or circumferentially welded cylinder both with a...

  15. 49 CFR 178.56 - Specification 4AA480 welded steel cylinders.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Specification 4AA480 welded steel cylinders. 178... FOR PACKAGINGS Specifications for Cylinders § 178.56 Specification 4AA480 welded steel cylinders. (a) Type, size, and service pressure. A DOT 4AA480 cylinder is a welded steel cylinder having a...

  16. 49 CFR 178.50 - Specification 4B welded or brazed steel cylinders.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Specification 4B welded or brazed steel cylinders... FOR PACKAGINGS Specifications for Cylinders § 178.50 Specification 4B welded or brazed steel cylinders. (a) Type, size, and service pressure. A DOT 4B is a welded or brazed steel cylinder with...

  17. 77 FR 60478 - Control of Ferrite Content in Stainless Steel Weld Metal

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-03

    ... COMMISSION Control of Ferrite Content in Stainless Steel Weld Metal AGENCY: Nuclear Regulatory Commission... Ferrite Content in Stainless Steel Weld Metal.'' This guide describes a method that the NRC staff considers acceptable for controlling ferrite content in stainless steel weld metal. Revision 4 updates...

  18. 78 FR 21105 - Circular Welded Carbon Steel Pipes and Tubes From Thailand: Preliminary Results of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-09

    ..., available in Antidumping Duty Order: Circular Welded Carbon Steel Pipes and Tubes from Thailand, 51 FR 8341... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes From Thailand: Preliminary... conducting an administrative review of the antidumping duty order on circular welded carbon steel pipes...

  19. Effects of welding on weldment mechanical performance in two austenitic steels

    SciTech Connect

    Strum, M.J.

    1982-06-01

    The effect of autogenous gas-tungsten arc-welding on the mechanical performance of two austenitic steels has been evaluated for cable jackets of force-cooled superconductor coils. The original candidate material was Nitronic 40, a nitrogen-strengthened stainless steel. The in-situ reaction heat treatment at 700/sup 0/C necessary for the formation of the superconducting A15 phase results in severe degradation of the cryogenic tensile ductility in the weld metal. The search for an alternate material led to JBK-75, a modified A-286 type ..gamma..' precipitation hardening iron-based superalloy. Observations of a tensile strength mismatch between base metal and the weaker weld metal in JBK-75 prompted a study into the aging response in weldments of this alloy. Localized strain through slip step traces show an easy path of deformation within the solidification structure. Weldment strength varies with grain size. It was found that through post-weld annealing treatments at 950/sup 0/C, prior to aging, weldment hardness levels can be matched. However, although increased strength levels are obtained in the weld metal, concomitant decreases in base metal strengths are suffered, presumably due to observed grain growth. 24 figures, 9 tables.

  20. Study on In-Situ Diffusible Hydrogen Sensor for Welded Hsla Steel

    NASA Astrophysics Data System (ADS)

    Park, Yeong-Do; Kim, Yang-Do; Kim, Young-Seok; Olson, David L.

    2008-02-01

    Diffusible hydrogen contents of welds need to be measured to avoid hydrogen cracking in weldment of high strength steels. Unlike other elements in weld metal, hydrogen diffuses very quickly at normal room temperature, and hence, difficulties occur in accurate measurement. Several methods are currently being used, which are the Japanese method (JIS Z 313-1975), the International Institute of Welding (IIW) method (ISO 3690-1977), and the AWS standard (ANSI/AWS A4.3-93). However, these methods do not give identical results when applied to identical conditions. Therefore, this investigation was attempting to correlate the measured TEP (Thermo Electric Power) coefficient values with diffusible hydrogen content measured by AWS standard method. TEP measurement was studied for application as in-situ diffusible hydrogen sensor for welded HSLA (High Strength Low alloy) steel. The results of TEP measurement are shown to be sensitive to the weld diffusible hydrogen content in low temperature (-80 °C) measurement and almost thirty times faster than standard diffusible hydrogen test.

  1. Welding procedures to mitigate reheat-PWHT cracking in A710/A736 type steels

    SciTech Connect

    Lundin, C.D.; Upitis, E.

    1996-06-01

    In the mid 1980s research on the behavior of the HAZ of A710/A736 type materials, at The University of Tennessee, revealed that a distinct sensitivity to reheat/PWHT cracking in the weld HAZ was in evidence. Subsequent work, sponsored by the Pressure Vessel Research Council (PVRC) of the Welding Research Council (WRC), more clearly documented the reheat/PWHT cracking potential in terms of the weld HAZ thermal history and contrasted the behavior to other HSLA steels. Additional research was undertaken by PVRC/WRC and the Materials Properties Council (MPC) on the Cu precipitation-strengthened A710/A736 materials, and the work was extended to similar HSLA 80/100 alloys developed for US Navy applications. The follow-on PVRC/WRC work was conducted at The University of Tennessee and also at Lehigh University. This research resulted in fabrication controls, detailed here, which are considered effective in mitigating reheat/PWHT cracking.

  2. Mechanical properties of Cu sbnd Cr sbnd Zr alloy and SS316 joints fabricated by friction welding method

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Kunihiko; Kawamura, Hiroshi

    1996-10-01

    Copper alloys with high-strength and high-conductivity are being considered for several magnetic fusion energy applications such as the first wall in high power-density devices, resistive magnetic coils, and high-heat flux components. For example, the stainless steel is a structural material while Cu-alloy acts as a heat sink material for the surface heat flux in the first wall. Therefore, development of reliable joints between Cu-alloys and stainless steel (SS316) is required. In the present work, joining tests on Cu—1%Cr—1%Zr/SS316 by friction welding were performed, and optimum fabricating conditions of the Cu-alloy/SS316 joint were determined. Additionally, the characteristics of tensile strength, hardness, metallographical observation and SEM/EPMA analyses on Cu—1%Cr—1%Zr/SS316 fabricated by friction welding were evaluated.

  3. FE Simulation Models for Hot Stamping an Automobile Component with Tailor-Welded High-Strength Steels

    NASA Astrophysics Data System (ADS)

    Tang, Bingtao; Wang, Qiaoling; Wei, Zhaohui; Meng, Xianju; Yuan, Zhengjun

    2016-05-01

    Ultra-high-strength in sheet metal parts can be achieved with hot stamping process. To improve the crash performance and save vehicle weight, it is necessary to produce components with tailored properties. The use of tailor-welded high-strength steel is a relatively new hot stamping process for saving weight and obtaining desired local stiffness and crash performance. The simulation of hot stamping boron steel, especially tailor-welded blanks (TWBs) stamping, is more complex and challenging. Information about thermal/mechanical properties of tools and sheet materials, heat transfer, and friction between the deforming material and the tools is required in detail. In this study, the boron-manganese steel B1500HS and high-strength low-alloy steel B340LA are tailor welded and hot stamped. In order to precisely simulate the hot stamping process, modeling and simulation of hot stamping tailor-welded high-strength steels, including phase transformation modeling, thermal modeling, and thermal-mechanical modeling, is investigated. Meanwhile, the welding zone of tailor-welded blanks should be sufficiently accurate to describe thermal, mechanical, and metallurgical parameters. FE simulation model using TWBs with the thickness combination of 1.6 mm boron steel and 1.2 mm low-alloy steel is established. In order to evaluate the mechanical properties of the hot stamped automotive component (mini b-pillar), hardness and microstructure at each region are investigated. The comparisons between simulated results and experimental observations show the reliability of thermo-mechanical and metallurgical modeling strategies of TWBs hot stamping process.

  4. Transition material improves spot welding of aluminum to steel

    SciTech Connect

    Not Available

    1994-06-01

    Weight is one of the primary enemies of improved fuel economy in automobiles. To help address this problem, a simple yet highly effective clad metal transition material has been developed. It allows automotive engineers to spot weld aluminum to steel using existing conventional production equipment and practices, thereby enabling them to use aluminum in place of heavier steel without expensive changes in production methods. The idea of the new materials technology is to permit the joining of aluminum to steel using conventional spot welding techniques. Numerous welding and corrosion studies have been conducted on the clad transition material approach by auto manufacturers, industry suppliers and various independent organizations. The success of these tests has prompted manufacturers in the US, Europe and Japan to accelerate production and field testing of clad transition materials on cars with an eye toward volume application.

  5. Accurate modelling of anisotropic effects in austenitic stainless steel welds

    SciTech Connect

    Nowers, O. D.; Duxbury, D. J.; Drinkwater, B. W.

    2014-02-18

    The ultrasonic inspection of austenitic steel welds is challenging due to the formation of highly anisotropic and heterogeneous structures post-welding. This is due to the intrinsic crystallographic structure of austenitic steel, driving the formation of dendritic grain structures on cooling. The anisotropy is manifested as both a ‘steering’ of the ultrasonic beam and the back-scatter of energy due to the macroscopic granular structure of the weld. However, the quantitative effects and relative impacts of these phenomena are not well-understood. A semi-analytical simulation framework has been developed to allow the study of anisotropic effects in austenitic stainless steel welds. Frequency-dependent scatterers are allocated to a weld-region to approximate the coarse grain-structures observed within austenitic welds and imaged using a simulated array. The simulated A-scans are compared against an equivalent experimental setup demonstrating excellent agreement of the Signal to Noise (S/N) ratio. Comparison of images of the simulated and experimental data generated using the Total Focusing Method (TFM) indicate a prominent layered effect in the simulated data. A superior grain allocation routine is required to improve upon this.

  6. Accurate modelling of anisotropic effects in austenitic stainless steel welds

    NASA Astrophysics Data System (ADS)

    Nowers, O. D.; Duxbury, D. J.; Drinkwater, B. W.

    2014-02-01

    The ultrasonic inspection of austenitic steel welds is challenging due to the formation of highly anisotropic and heterogeneous structures post-welding. This is due to the intrinsic crystallographic structure of austenitic steel, driving the formation of dendritic grain structures on cooling. The anisotropy is manifested as both a `steering' of the ultrasonic beam and the back-scatter of energy due to the macroscopic granular structure of the weld. However, the quantitative effects and relative impacts of these phenomena are not well-understood. A semi-analytical simulation framework has been developed to allow the study of anisotropic effects in austenitic stainless steel welds. Frequency-dependent scatterers are allocated to a weld-region to approximate the coarse grain-structures observed within austenitic welds and imaged using a simulated array. The simulated A-scans are compared against an equivalent experimental setup demonstrating excellent agreement of the Signal to Noise (S/N) ratio. Comparison of images of the simulated and experimental data generated using the Total Focusing Method (TFM) indicate a prominent layered effect in the simulated data. A superior grain allocation routine is required to improve upon this.

  7. Weld-brazing - a new joining process. [combination resistance spot welding and brazing of titanium alloys

    NASA Technical Reports Server (NTRS)

    Bales, T. T.; Royster, D. M.; Arnold, W. E., Jr.

    1972-01-01

    A joining process designated weld brazing which combines resistance spot welding and brazing has been developed. Resistance spot welding is used to position and align the parts as well as to establish a suitable faying surface gap for brazing. Fabrication is then completed by capillary flow of the braze alloy into the joint. The process has been used successfully to fabricate Ti-6Al-4V titanium alloy joints using 3003 aluminum braze alloy. Test results obtained on single overlap and hat-stiffened structural specimens show that weld brazed joints are superior in tensile shear, stress rupture, fatigue, and buckling than joint fabricated by spotwelding or brazing. Another attractive feature of the process is that the brazed joints is hermetically sealed by the braze material.

  8. The cause of welding cracks in aircraft steels

    NASA Technical Reports Server (NTRS)

    Muller, J

    1940-01-01

    The discussion in this article refers to gas welding of thin-walled parts of up to about 3 mm thickness. It was proven that by restricting the sulphur, carbon, and phosphorous content, and by electric-furnace production of the steel, it was possible in a short time to remove this defect. Weld hardness - i.e., martensite formation and hardness of the overheated zone - has no connection with the tendency to weld-crack development. Si, Cr, Mo, or V content has no appreciable effect, while increased manganese content tends to reduce the crack susceptibility.

  9. Gas-tungsten arc welding of aluminum alloys

    DOEpatents

    Frye, Lowell D.

    1984-01-01

    A gas-tungsten arc welding method for joining together structures formed of aluminum alloy with these structures disposed contiguously to a heat-damagable substrate of a metal dissimilar to the aluminum alloy. The method of the present invention is practiced by diamond machining the fay surfaces of the aluminum alloy structures to provide a mirror finish thereon having a surface roughness in the order of about one microinch. The fay surfaces are aligned and heated sufficiently by the tungsten electrode to fuse the aluminum alloy contiguous to the fay surfaces to effect the weld joint. The heat input used to provide an oxide-free weld is significantly less than that required if the fay surfaces were prepared by using conventional chemical and mechanical practices.

  10. Gas-tungsten arc welding of aluminum alloys

    DOEpatents

    Frye, L.D.

    1982-03-25

    The present invention is directed to a gas-tungsten arc welding method for joining together structures formed of aluminum alloy with these structures disposed contiguously to a heat-damagable substrate of a metal dissimilar to the aluminum alloy. The method of the present invention is practiced by diamond machining the fay surfaces of the aluminum alloy structures to profice a mirror finish thereon having a surface roughness in the order of about one microinch. The fay surface are aligned and heated sufficiently by the tungsten electrode to fuse the aluminum alloy continguous to the fay surfaces to effect the weld joint. The heat input used to provide an oxide-free weld is significantly less than that required if the fay surfaces were prepared by using conventional chemical and mechanical practices.

  11. Stress corrosion cracking of austenitic stainless steel core internal welds.

    SciTech Connect

    Chung, H. M.; Park, J.-H.; Ruther, W. E.; Sanecki, J. E.; Strain, R. V.; Zaluzec, N. J.

    1999-04-14

    Microstructural analyses by several advanced metallographic techniques were conducted on austenitic stainless steel mockup and core shroud welds that had cracked in boiling water reactors. Contrary to previous beliefs, heat-affected zones of the cracked Type 304L, as well as 304 SS core shroud welds and mockup shielded-metal-arc welds, were free of grain-boundary carbides, which shows that core shroud failure cannot be explained by classical intergranular stress corrosion cracking. Neither martensite nor delta-ferrite films were present on the grain boundaries. However, as a result of exposure to welding fumes, the heat-affected zones of the core shroud welds were significantly contaminated by oxygen and fluorine, which migrate to grain boundaries. Significant oxygen contamination seems to promote fluorine contamination and suppress thermal sensitization. Results of slow-strain-rate tensile tests also indicate that fluorine exacerbates the susceptibility of irradiated steels to intergranular stress corrosion cracking. These observations, combined with previous reports on the strong influence of weld flux, indicate that oxygen and fluorine contamination and fluorine-catalyzed stress corrosion play a major role in cracking of core shroud welds.

  12. Feasibility of correlating V-Cr-Ti alloy weld strength with weld chemistry. CRADA final report

    SciTech Connect

    Grossbeck, M.L.; Odom, R.W.

    1998-06-01

    The mechanical properties of refractory metals such as vanadium are determined to a large extent by the interstitial impurities in the alloy. In the case of welding, interstitial impurities are introduced in the welding process from the atmosphere and by dissolution of existing precipitates in the alloy itself. Because of the necessity of having an ultra-pure atmosphere, a vacuum chamber or a glove box is necessary. In the V-Cr-Ti system, the titanium serves as a getter to control the concentration of oxygen and nitrogen in solid solution in the alloy. In this project the secondary ion mass spectrometry (SIMS) technique was used to detect, measure, and map the spacial distribution of impurity elements in welds in the alloy V-4Cr-4Ti. An attempt was then made to correlate the concentrations and distributions of the impurities with mechanical properties of the welds. Mechanical integrity of the welds was determined by Charpy V-notch testing. Welds were prepared by the gas-tungsten-arc (GTA) method. Charpy testing established a correlation between weld impurity concentration and the ductile to brittle transition temperature (DBTT). Higher concentrations of oxygen resulted in a higher DBTT. An exception was noted in the case of a low-oxygen weld which had a high hydrogen concentration resulting in a brittle weld. The concentrations and distributions of the impurities determined by SIMS could not be correlated with the mechanical properties of the welds. This research supports efforts to develop fusion reactor first wall and blanket structural materials.

  13. Residual Stresses in Inertia-Friction-Welded Dissimilar High-Strength Steels

    NASA Astrophysics Data System (ADS)

    Moat, R. J.; Hughes, D. J.; Steuwer, A.; Iqbal, N.; Preuss, M.; Bray, S. E.; Rawson, M.

    2009-09-01

    The welding of dissimilar alloys is seen increasingly as a way forward to improve efficiencies in modern aeroengines, because it allows one to tailor varying material property demands across a component. Dissimilar inertia friction welding (IFW) of two high-strength steels, Aermet 100 and S/CMV, has been identified as a possible joint for rotating gas turbine components and the resulting welds are investigated in this article. In order to understand the impact of the welding process and predict the life expectancy of such structures, a detailed understanding of the residual stress fields present in the welded component is needed. By combining energy-dispersive synchrotron X-ray diffraction (EDSXRD) and neutron diffraction, it has been possible to map the variations in lattice spacing of the ferritic phase on both sides of two tubular Aermet 100-S/CMV inertia friction welds (as-welded and postweld heat-treated condition) with a wall thickness of 37 mm. Laboratory-based XRD measurements were required to take into account the variation in the strain-free d-spacing across the weld region. It was found that, in the heat-affected zone (HAZ) slightly away from the weld line, residual stress fields showed tensile stresses increasing most dramatically in the hoop direction toward the weld line. Closer to the weld line, in the plastically affected zone, a sharp drop in the residual stresses was observed on both sides, although more dramatically in the S/CMV. In addition to residual stress mapping, synchrotron XRD measurements were carried out to map microstructural changes in thin slices cut from the welds. By studying the diffraction peak asymmetry of the 200- α diffraction peak, it was possible to demonstrate that a martensitic phase transformation in the S/CMV is responsible for the significant stress reduction close to the weld line. The postweld heat treatment (PWHT) chosen to avoid any overaging of the Aermet 100 and to temper the S/CMV martensite resulted in little

  14. Interpretation of aluminum-alloy weld radiography

    NASA Technical Reports Server (NTRS)

    Duren, P. C.; Risch, E. R.

    1971-01-01

    Report proposes radiographic terminology standardization which allows scientific interpretation of radiographic films to replace dependence on individual judgement and experience. Report includes over 50 photographic pages where radiographs of aluminum welds with defects are compared with prepared weld sections photomacrographs.

  15. Optimization of Weld Conditions and Alloy Composition for Welding of Single-Crystal Nickel-Based Superalloys

    SciTech Connect

    Vitek, John Michael; David, Stan A; Babu, Sudarsanam S

    2007-01-01

    Calculations were carried out to identify optimum welding conditions and weld alloy compositions to avoid stray grain formation during welding of single-crystal nickel-based superalloys. The calculations were performed using a combination of three models: a thermal model to describe the weld pool shape and the local thermal gradient and solidification front velocity; a geometric model to identify the local active dendrite growth variant, and a nucleation and growth model to describe the extent of stray grain formation ahead of the advancing solidification front. Optimum welding conditions (low weld power, high weld speed) were identified from the model calculations. Additional calculations were made to determine potential alloy modifications that reduce the solidification temperature range while maintaining high gamma prime content. The combination of optimum weld conditions and alloy compositions should allow for weld repair of single-crystal nickel-based superalloys without sacrificing properties or performance.

  16. Development of laser welding techniques for vanadium alloys

    SciTech Connect

    Strain, R.V.; Leong, K.H.; Smith, D.L.

    1996-10-01

    Laser welding is potentially advantageous because of its flexibility and the reduced amount of material affected by the weld. Bead-on-plate and butt welds were previously performed to depths of about 4 mm with a 6-kW CO{sub 2} laser on V-4%Cr-4%Ti and V-5%Cr-5%Ti alloys. These welds were made at a speed of 0.042 m/s using argon purging at a flow rate of 2.8 m{sup 3}/s. The purge was distributed with a diffuser nozzle aimed just behind the laser beam during the welding operation. The fusion zones of welds made under these conditions consisted of very fine, needle-shaped grains and were also harder than the bulk metal (230-270 dph, compared to {approx}180 dph for the bulk metal). A limited number of impact tests showed that the as-welded ductile-brittle transition temperatures (DBTT) was above room temperature, but heat treatment at 1000{degrees}C for 1 h in vacuum reduced the DBTT to <{minus}25{degrees}C. Activities during this reporting period focused on improvements in the purging system and determination of the effect of welding speed on welds. A 2-kW continuous YAG laser at Lumonics Corp. in Livonia, MI, was used to make 34 test welds for this study.

  17. Recent Developments in Friction Stir Welding of Al-alloys

    NASA Astrophysics Data System (ADS)

    Çam, Gürel; Mistikoglu, Selcuk

    2014-06-01

    The diversity and never-ending desire for a better life standard result in a continuous development of the existing manufacturing technologies. In line with these developments in the existing production technologies the demand for more complex products increases, which also stimulates new approaches in production routes of such products, e.g., novel welding procedures. For instance, the friction stir welding (FSW) technology, developed for joining difficult-to-weld Al-alloys, has been implemented by industry in manufacturing of several products. There are also numerous attempts to apply this method to other materials beyond Al-alloys. However, the process has not yet been implemented by industry for joining these materials with the exception of some limited applications. The microstructures and mechanical properties of friction stir welded Al-alloys existing in the open literature will be discussed in detail in this review. The correlations between weld parameters used during FSW and the microstructures evolved in the weld region and thus mechanical properties of the joints produced will be highlighted. However, the modeling studies, material flow, texture formation and developments in tool design are out of the scope of this work as well as the other variants of this technology, such as friction stir spot welding (FSSW).

  18. Metallurgy and deformation of electron beam welded similar titanium alloys

    NASA Astrophysics Data System (ADS)

    Pasang, T.; Sabol, J. C.; Misiolek, W. Z.; Mitchell, R.; Short, A. B.; Littlefair, G.

    2012-04-01

    Butt welded joins were produced between commercially pure titanium and various titanium alloys using an electron beam welding technique. The materials used represent commercially pure grade, α-β alloy and β alloy. They were CP Ti, Ti-6Al-4V (Ti64) and Ti-5Al-5V-5Mo-3Cr (Ti5553), respectively. Grains were largest in the FZs of the different weldments, decreasing in size towards the heat affected zones (HAZs) and base metals. Hardness measurements taken across the traverse cross-sections of the weldments were constant from base metal-to-weld-to-base metal for CP Ti/CP Ti and Ti64/Ti64 welds, while the FZ of Ti5553/Ti5553 had a lower hardness compared with the base metal. During tensile testing the CP Ti/CP Ti weldments fractured at the base metal, whereas both the Ti64/Ti64 and Ti5553/Ti5553 broke at the weld zones. Fracture surface analysis suggested microvoid coalescence as the failure mechanism. The compositional analysis showed a relatively uniform distribution of solute elements from base metal-to-weld-to-base metal. CP Ti has always been known for its excellent weldability, Ti64 has good weldability and, preliminary results indicated that Ti5553 alloy is also weldable.

  19. Neutron diffraction studies of welds of aerospace aluminum alloys

    SciTech Connect

    Martukanitz, R.P.; Howell, P.R.; Payzant, E.A.; Spooner, S.; Hubbard, C.R.

    1996-10-01

    Neutron diffraction and electron microscopy were done on residual stress in various regions comprising variable polarity plasma arc welds of alloys 2219 (Al-6.3Cu) and 2195 (Al-4.0Cu-1.0Li-0.5Mg-0.5Ag). Results indicate that lattice parameter changes in the various weld regions may be attributed to residual stresses generated during welding, as well as local changes in microstructure. Distribution of longitudinal and transverse stress of welded panels shows peaks of tension and compression, respectively, within the HAZ and corroborate earlier theoretical results. Position of these peaks are related to position of minimum strength within the HAZ, and the magnitude of these peaks are a fraction of the local yield strength in this region. Weldments of alloy 2195-T8 exhibited higher peak residual stress than alloy 2219-T87. Comparison of neutron diffraction and microstructural analysis indicate decreased lattice parameters associated with the solid solution of the near HAZ; this results in decreased apparent tensile residual stress within this region and may significantly alter interpretation of residual stress measurements of these alloys. Considerable relaxation of residual stress occurs during removal of specimens from welded panels and was used to aid in differentiating changes in lattice parameters attributed to residual stress from welding and modifications in microstructure.

  20. Mechanical strength of laser-welded cobalt-chromium alloy.

    PubMed

    Baba, N; Watanabe, I; Liu, J; Atsuta, M

    2004-05-15

    The purpose of this study was to investigate the effect of the output energy of laser welding and welding methods on the joint strength of cobalt-chromium (Co-Cr) alloy. Two types of cast Co-Cr plates were prepared, and transverse sections were made at the center of the plate. The cut surfaces were butted against one another, and the joints welded with a laser-welding machine at several levels of output energy with the use of two methods. The fracture force required to break specimens was determined by means of tensile testing. For the 0.5-mm-thick specimens, the force required to break the 0.5-mm laser-welded specimens at currents of 270 and 300 A was not statistically different (p > 0.05) from the results for the nonwelded control specimens. The force required to break the 1.0-mm specimens double-welded at a current of 270 A was the highest value among the 1.0-mm laser-welded specimens. The results suggested that laser welding under the appropriate conditions improved the joint strength of cobalt- chromium alloy. PMID:15116400

  1. Characteristics comparison of weld metal zones welded to cast and forged steels for piston crown material

    NASA Astrophysics Data System (ADS)

    Moon, Kyung-Man; Kim, Yun-Hae; Lee, Myeong-Hoon; Baek, Tae-Sil

    2015-03-01

    An optimum repair welding for the piston crown which is one of the engine parts exposed to the combustion chamber is considered to be very important to prolong the engine lifetime from an economical point of view. In this study, two types of filler metals such as 1.25Cr-0.5Mo, 0.5Mo were welded with SMAW method and the other two types of filler metals such as Inconel 625 and 718 were welded with GTAW method, respectively, and the used base metals were the cast and forged steels of the piston crown material. The weld metal zones welded with Inconel 625 and 718 filler metals exhibited higher corrosion resistance compared to 1.25Cr-0.5Mo and 0.5Mo filler metals. In particular, the weld metal zone welded with Inconel 718 and 0.5Mo, filler metals indicated the best and worst corrosion resistance, respectively. Consequently, it is suggested that the corrosion resistance of the weld metal zone surely depends on the chemical components of each filler metal and welding method irrespective of the types of piston crown material.

  2. The influence of oxygen on the impact toughness and microstructure of steel weld metal

    SciTech Connect

    Sato, Yoshihiro; Kuwana, Takeshi; Maie, Tsuyoshi

    1995-12-31

    A steel plate was welded in a low oxygen potential welding atmosphere. The weld metal obtained is classified in two groups on the oxygen content, very low oxygen content (less than 0.002 mass %) weld metal and relatively high oxygen content (over 0.015 mass%) weld metal. The effect of oxygen in steel weld metal on the Charpy v-notch impact values and the microstructure is investigated and discussed. Very low oxygen content steel weld metal shows superior impact toughness at 273 K as well as the well-known ``optimum oxygen`` containing steel weld metal. The very low oxygen weld metal has relatively large amounts of grain boundary ferrite and side plate ferrite microstructure, instead of upper bainite compared with the relatively high oxygen content weld metal.

  3. Fatigue crack propagation behavior of stainless steel welds

    NASA Astrophysics Data System (ADS)

    Kusko, Chad S.

    The fatigue crack propagation behavior of austenitic and duplex stainless steel base and weld metals has been investigated using various fatigue crack growth test procedures, ferrite measurement techniques, light optical microscopy, stereomicroscopy, scanning electron microscopy, and optical profilometry. The compliance offset method has been incorporated to measure crack closure during testing in order to determine a stress ratio at which such closure is overcome. Based on this method, an empirically determined stress ratio of 0.60 has been shown to be very successful in overcoming crack closure for all da/dN for gas metal arc and laser welds. This empirically-determined stress ratio of 0.60 has been applied to testing of stainless steel base metal and weld metal to understand the influence of microstructure. Regarding the base metal investigation, for 316L and AL6XN base metals, grain size and grain plus twin size have been shown to influence resulting crack growth behavior. The cyclic plastic zone size model has been applied to accurately model crack growth behavior for austenitic stainless steels when the average grain plus twin size is considered. Additionally, the effect of the tortuous crack paths observed for the larger grain size base metals can be explained by a literature model for crack deflection. Constant Delta K testing has been used to characterize the crack growth behavior across various regions of the gas metal arc and laser welds at the empirically determined stress ratio of 0.60. Despite an extensive range of stainless steel weld metal FN and delta-ferrite morphologies, neither delta-ferrite morphology significantly influence the room temperature crack growth behavior. However, variations in weld metal da/dN can be explained by local surface roughness resulting from large columnar grains and tortuous crack paths in the weld metal.

  4. Development of a carburizing stainless steel alloy

    SciTech Connect

    Wert, D.E. )

    1994-06-01

    A new carburizing stainless steel alloy that resists corrosion, heat, and fatigue has been developed for bearing and gear applications. Pyrowear 675 Stainless alloy is vacuum induction melted and vacuum arc remelted (VIM/VAR) for aircraft-quality cleanliness. Test results show that it has corrosion resistance similar to that of AISI Type 440-C stainless, and its rolling fatigue resistance is superior to that of AISI M50 (UNS K88165). In contrast to alloy gear steels and Type 440C, Pyrowear 675 maintains case hardness of HRC 60 at operating temperatures up to 200 C (400 F). Impact and fracture toughness are superior to that of other stainless bearing steels, which typically are relatively brittle and can break under severe service. Toughness is also comparable or superior to conventional noncorrosion-resistant carburizing bearing steels, such as SAE Types 8620 and 9310.

  5. A Comparison of Creep Rupture Strength of Ferritic/Austenitic Dissimilar Weld Joints of Different Grades of Cr-Mo Ferritic Steels

    NASA Astrophysics Data System (ADS)

    Laha, K.; Chandravathi, K. S.; Parameswaran, P.; Goyal, Sunil; Mathew, M. D.

    2012-04-01

    Evaluations of creep rupture properties of dissimilar weld joints of 2.25Cr-1Mo, 9Cr-1Mo, and 9Cr-1MoVNb steels with Alloy 800 at 823 K were carried out. The joints were fabricated by a fusion welding process employing an INCONEL 182 weld electrode. All the joints displayed lower creep rupture strength than their respective ferritic steel base metals, and the strength reduction was greater in the 2.25Cr-1Mo steel joint and less in the 9Cr-1Mo steel joint. Failure location in the joints was found to shift from the ferritic steel base metal to the intercritical region of the heat-affected zone (HAZ) of the ferritic steel (type IV cracking) with the decrease in stress. At still lower stresses, the failure in the joints occurred at the ferritic/austenitic weld interface. The stress-life variation of the joints showed two-slope behavior and the slope change coincided with the occurrence of ferritic/austenitic weld interface cracking. Preferential creep cavitation in the soft intercritical HAZ induced type IV failure, whereas creep cavitation at the interfacial particles induced ferritic/austenitic weld interface cracking. Micromechanisms of the type IV failure and the ferritic/austenitic interface cracking in the dissimilar weld joint of the ferritic steels and relative cracking susceptibility of the joints are discussed based on microstructural investigation, mechanical testing, and finite element analysis (FEA) of the stress state across the joint.

  6. Butt Welding Joint of Aluminum Alloy by Space GHTA Welding Process in Vacuum

    NASA Astrophysics Data System (ADS)

    Suita, Yoshikazu; Shinike, Shuhei; Ekuni, Tomohide; Terajima, Noboru; Tsukuda, Yoshiyuki; Imagawa, Kichiro

    Aluminum alloys have been used widely in constructing various space structures including the International Space Station (ISS) and launch vehicles. For space applications, welding experiments on aluminum alloy were performed using the GHTA (Gas Hollow Tungsten Arc) welding process using a filler wire feeder in a vacuum. We investigated the melting phenomenon of the base metal and filler wire, bead formation, and the effects of wire feed speed on melting characteristics. The melting mechanism in the base metal during the bead on a plate with wire feed was similar to that for the melt run without wire feed. We clarified the effects of wire feed speed on bead sizes and configurations. Furthermore, the butt welded joint welded using the optimum wire feed speed, and the joint tensile strengths were evaluated. The tensile strength of the square butt joint welded by the pulsed DC GHTA welding with wire feed in a vacuum is nearly equal to that of the same joint welded by conventional GTA (Gas Tungsten Arc) welding in air.

  7. Sensitization of Laser-beam Welded Martensitic Stainless Steels

    NASA Astrophysics Data System (ADS)

    Dahmen, Martin; Rajendran, Kousika Dhasanur; Lindner, Stefan

    Ferritic and martensitic stainless steels are an attractive alternative in vehicle production due to their inherent corrosion resistance. By the opportunity of press hardening, their strength can be increased to up to 2000 MPa, making them competitors for unalloyed ultra-high strength steels. Welding, nevertheless, requires special care, especially when it comes to joining of high strength heat treated materials. With an adopted in-line heat treatment of the welds in as-rolled as well as press hardened condition, materials with sufficient fatigue strength and acceptable structural behavior can be produced. Because of microstructural transformations in the base material such as grain coarsening and forced carbide precipitation, the corrosion resistance of the weld zone may be locally impaired. Typically the material in the heat-affected zone becomes sensitive to intergranular cracking in the form of knife-edge corrosion besides the fusion line. The current study comprises of two text scenarios. By an alternating climate test, general response in a corroding environment is screened. In order to understand the corrosion mechanisms and to localize the sensitive zones, sensitisation tests were undertaken. Furthermore, the applicability of a standard test according to ASTM 763-83 was examined. It was found that the alternative climate test does not reveal any corrosion effects. Testing by the oxalic acid test revealed clearly the effect of welding, weld heat treatment and state of thermal processing. Also application of the standard which originally suited for testing ferritic stainless steels could have been justified.

  8. Solidification behavior and microstructural analysis of austenitic stainless steel laser welds

    SciTech Connect

    David, S.A.; Vitek, J.M.

    1981-01-01

    Solidification behavior of austenitic stainless steel laser welds has been investigated with a high-power laser system. The welds were made at speeds ranging from 13 to 60 mm/s. The welds sowed a wide variety of microstructural features. The ferrite content in the 13-mm/s weld varied from less than 1% at the root of the weld to about 10% at the crown. The duplex structure at the crown of the weld was much finer than the one observed in conventional weld metal. However, the welds made at 25 and 60 mm/s contained an austenitic structure with less than 1% ferrite throughout the weld. Microstructural analysis of these welds used optical microscopy, transmission electron microscopy, and analytical electron microscopy. The austenitic stainless steel welds were free of any cracking, and the results are explained in terms of the rapid solidification conditions during laser welding.

  9. Tensile Strength of Welded Steel Tubes : First Series of Experiments

    NASA Technical Reports Server (NTRS)

    Rechtlich, A

    1928-01-01

    The purpose of the experiments was to determine the difference in the strength of steel tubes welded by different methods, as compared with one another and also with unwelded, unannealed tubes, including; moreover, a comparison of the results obtained by experienced and inexperienced welders.

  10. Reliability of Radiographic Inspection of Steel Pipeline Girth Welds

    NASA Astrophysics Data System (ADS)

    Almeida, R. M.; Rebello, J. M. A.; Carvalho, A. A.; Smid, J.

    2008-02-01

    In this work, the radiographic NDT technique was employed for the detection of defects in girth welds of steel pipelines used by the offshore oil industry. Simulation was used to calculate the size of the smallest detectable defect and the corresponding radiographic parameters. The method developed showed good reliability.

  11. Laser beam welding of new ultra-high strength and supra-ductile steels

    NASA Astrophysics Data System (ADS)

    Dahmen, Martin

    2015-03-01

    Ultra-high strength and supra-ductile are entering fields of new applications. Those materials are excellent candidates for modern light-weight construction and functional integration. As ultra-high strength steels the stainless martensitic grade 1.4034 and the bainitic steel UNS 53835 are investigated. For the supra-ductile steels stand two high austenitic steels with 18 and 28 % manganese. As there are no processing windows an approach from the metallurgical base on is required. Adjusting the weld microstructure the Q+P and the QT steels require weld heat treatment. The HSD steel is weldable without. Due to their applications the ultra-high strength steels are welded in as-rolled and strengthened condition. Also the reaction of the weld on hot stamping is reflected for the martensitic grades. The supra-ductile steels are welded as solution annealed and work hardened by 50%. The results show the general suitability for laser beam welding.

  12. Welding development for V-Cr-Ti alloys

    SciTech Connect

    King, J.F.; Goodwin, G.M.; Alexander, D.J.

    1995-04-01

    A vanadium structure, cooled with helium, is a favored concept for an advanced breeding blanket for fusion systems. The objective of this task is to develop the metallurgical and technological base for the welding of thick sections of V-Cr-Ti. The subsize Charpy test results for electron beam weld metal from the V-5Cr-5Ti alloy has shown significant improvement in Charpy fracture energy compared to both gas tungsten arc weld metal and the base metal itself. These results are preliminary, however, and additional confirmation testing and analysis will be required to explain this improvement in properties.

  13. Hydrogen effects in duplex stainless steel welded joints - electrochemical studies

    NASA Astrophysics Data System (ADS)

    Michalska, J.; Łabanowski, J.; Ćwiek, J.

    2012-05-01

    In this work results on the influence of hydrogen on passivity and corrosion resistance of 2205 duplex stainless steel (DSS) welded joints are described. The results were discussed by taking into account three different areas on the welded joint: weld metal (WM), heat-affected zone (HAZ) and parent metal. The corrosion resistance was qualified with the polarization curves registered in a synthetic sea water. The conclusion is that, hydrogen may seriously deteriorate the passive film stability and corrosion resistance to pitting of 2205 DSS welded joints. The presence of hydrogen in passive films increases corrosion current density and decreases the potential of the film breakdown. It was also found that degree of susceptibility to hydrogen degradation was dependent on the hydrogen charging conditions. WM region has been revealed as the most sensitive to hydrogen action.

  14. Residual stresses and plastic deformation in GTA-welded steel

    SciTech Connect

    Brand, P.C. ); Keijser, T.H. de; Ouden, G. den )

    1993-03-01

    Residual stresses and plastic deformation in single pass GTA welded low-carbon steel were studied by means of x-ray diffraction in combination with optical microscopy and hardness measurements. The residual stresses and the amount of plastic deformation (microstrain) were obtained from x-ray diffraction line positions and line broading. Since the plates were polished before welding, it was possible to observe in the optical microscope two types of Lueders bands. During heating curved Lueders bands and during cooling straight Lueders bands perpendicular to the weld are formed. The curved Lueders bands extend over a larger distance from the weld than the straight Lueders bands. The amount of plastic deformation as obtained from the x-ray diffraction analysis is in agreement with these observations. An explanation is offered for the stresses measured in combination with plastic deformations observed. It is concluded that in the present experiments plastic deformation is the main cause of the residual stresses.

  15. Microstructural analysis of the 2195 aluminum-lithium alloy welds

    NASA Technical Reports Server (NTRS)

    Talia, George E.

    1993-01-01

    The principal objective of this research was to explain a tendency of 2195 Al-Li alloy to crack at elevated temperature during welding. Therefore, a study was made on the effect of welding and thermal treatment on the microstructure of Al-Li Alloy 2195. The critical roles of precipitates, boundaries, phases, and other features of the microstructure were inferred from the crack propagation paths and the morphology of fracture surface of the alloy with different microstructures. Particular emphasis was placed on the microstructures generated by the welding process and the mechanisms of crack propagation in such structures. Variation of the welding parameters and thermal treatments were used to alter the micro/macro structures, and they were characterized by optical and scanning electron microscopy. A theoretical model is proposed to explain changes in the microstructure of welded material. This model proposes a chemical reaction in which gases from the air (i.e., nitrogen) release hydrogen inside the alloy. Such a reaction could generate large internal stresses capable to induce porosity and crack-like delamination in the material.

  16. Effect of Pulsed Nd: YAG Laser Powers On 304 Stainless Steel Welding

    SciTech Connect

    Candan, L.; Demir, A.; Akman, E.

    2007-04-23

    In this study, optimum welding parameters are obtained for 1mm thickness type 304 stainless steel welding using the Lumonics JK760TR pulsed Nd:YAG laser. The influences of laser welding parameters such as pulse duration, focal position, frequency, laser power, welding speed, and shielding gas (N2) pressure on penetration defining welding quality are investigated. Also comparisons of overlap ratios are presented between theory and experiment for pulse duration, frequency and welding speed.

  17. Welding stainless steels for structures operating at liquid helium temperature

    SciTech Connect

    Witherell, C.E.

    1980-04-18

    Superconducting magnets for fusion energy reactors require massive monolithic stainless steel weldments which must operate at extremely low temperatures under stresses approaching 100 ksi (700 MPa). A three-year study was conducted to determine the feasibility of producing heavy-section welds having usable levels of strength and toughness at 4.2/sup 0/K for fabrication of these structures in Type 304LN plate. Seven welding processes were evaluated. Test weldments in full-thickness plate were made under severe restraint to simulate that of actual structures. Type 316L filler metal was used for most welds. Welds deposited under some conditions and which solidify as primary austenite have exhibited intergranular embrittlement at 4.2/sup 0/K. This is believed to be associated with grain boundary metal carbides or carbonitrides precipitated during reheating of already deposited beads by subsequent passes. Weld deposits which solidify as primary delta ferrite appear immune. Through use of fully austenitic filler metals of low nitrogen content under controlled shielded metal arc welding conditions, and through use of filler metals solidifying as primary delta ferrite where only minimum residuals remain to room temperature, welds of Type 316L composition have been made with 4.2K yield strength matching that of Type 304LN plate and acceptable levels of soundness, ductility and toughness.

  18. Diffusion welding. [heat treatment of nickel alloys following single step vacuum welding process

    NASA Technical Reports Server (NTRS)

    Holko, K. H. (Inventor)

    1974-01-01

    Dispersion-strengthened nickel alloys are sanded on one side and chemically polished. This is followed by a single-step welding process wherein the polished surfaces are forced into intimate contact at 1,400 F for one hour in a vacuum. Diffusion, recrystallization, and grain growth across the original weld interface are obtained during postheating at 2,150 F for two hours in hydrogen.

  19. Simulating weld-fusion boundary microstructures in aluminum alloys

    NASA Astrophysics Data System (ADS)

    Kostrivas, Anastasios D.; Lippold, John C.

    2004-02-01

    A fundamental study of weld-fusion boundary microstructure evolution in aluminum alloys was conducted in an effort to understand equiaxed grain zone formation and fusion boundary nucleation and growth phenomena. In addition to commercial aluminum alloys, experimental Mg-bearing alloys with Zr and Sc additions were studied along with the widely used Cu- and Licontaining alloy 2195-T8. This article describes work conducted to clarify the interrelation among composition, base metal substrate, and temperature as they relate to nucleation and growth phenomena at the fusion boundary.

  20. Crack propagation in stainless steels and nickel base alloys in a commercial operating BWR

    SciTech Connect

    Jenssen, A.; Morin, U.; Bengtsson, B.; Jansson, C.

    1995-12-31

    Crack propagation was investigated to study critical stress intensity factors for intergranular stress corrosion cracking (IGSCC), and crack growth rates in various materials. Modified bolt loaded compact tension (CT) specimens were exposed to BWR normal water chemistry (NWC) in a commercially operating BWR. The test facility was a pressure vessel, originally designed for high temperature magnetite filters. Stainless steels (SS) of Types 304 SS and 316 SS were included in the test matrix, as well as the Ni base weld materials alloys 82 and 182. The SS were investigated both in sensitized and in cold worked condition. For alloy 182 various parameters were studied, such as the effect of the carbon stabilization parameter, and the as-welded condition versus a post weld heat treatment (PWHT). Crack growth was measured annually, during the normal outages, by an optical microscope. The results were evaluated as crack growth rate as a function of stress intensity. A few specimens have been removed from testing for fractographic examination. Most of the specimens were exposed to NWC for more than 30,000 hours. Alloy 82 in as welded condition was found to be susceptible to IGSCC, at least at stress intensities above 30 MPa{radical}m. For alloy 182, in as welded condition, significant crack growth was detected in all specimens. No beneficial effect of the carbon stabilization parameter could be found. PWHT had a beneficial effect on the IGSCC susceptibility of alloy 182, and at stress intensities below 30 MPa{radical}m the crack growth rates were one to two orders of magnitude lower, compared to alloy 182 in as welded condition. As expected, an increasing susceptibility to IGSCC with increasing degree of cold work was found for stainless steel. At 5% cold work Type 304 SS cracked at a higher rate than Type 316NG with the same degree of cold work. At 20% cold work Type 304 SS and Type 316NG cracked at essentially the same rate.

  1. Electrochemical Testing of Gas Tungsten Arc Welded and Reduced Pressure Electron Beam Welded Alloy 22

    SciTech Connect

    Day, S D; Wong, F M G; Gordon, S R; Wong, L L; Rebak, R B

    2003-09-07

    Alloy 22 (N06022) is the material selected for the fabrication of the outer shell of the nuclear waste containers for the Yucca Mountain high-level nuclear waste repository site. A key technical issue in the Yucca Mountain waste package program has been the integrity of container weld joints. The currently selected welding process for fabricating and sealing the containers is the traditional gas tungsten arc welding (GTAW) or TIG method. An appealing faster alternative technique is reduced pressure electron beam (RPEB) welding. Standard electrochemical tests were carried on GTAW and RPEB welds as well as on base metal to determine their relative corrosion behavior in SCW at 90 C (alkaline), 1 M HCl at 60 C (acidic) and 1 M NaCl at 90 C (neutral) solutions. Results show that for all practical purposes, the three tested materials had the electrochemical behavior in the three tested solutions.

  2. Laser Welded Corrugated Steel Panels in Industrial Applications

    NASA Astrophysics Data System (ADS)

    Kananen, M.; Mäntyjärvi, K.; Keskitalo, M.; Hietala, M.; Järvenpää, A.; Holappa, K.; Saine, K.; Teiskonen, J.

    Corrugated core steel panels are an effective way to reduce weight and increase stiffness of steel structures. In numerous applications, these panels have shown very promising commercial possibilities. This study presents the design, manufacturing and commercializing process for two practical examples: Case 1) a fly wheel cover for a diesel engine and Case 2) rotationally symmetrical panel for an electric motor. Test materials of various kinds were used for corrugated cores and skin plates: conventional low-carbon steel grade EN 10130 and ferritic stainless steel grade 1.4509 with plate the thicknesses of 0.5, 0.6 and 0.75 mm. To manufacture different kinds of corrugated core steel panels, flexible manufacturing tools and cost-effective processes are needed. The most important criterion for laser welding panels was the capability of forming tools for producing high quality geometry for the core. Laser welding assembly showed that the quality of the core in both studied cases was good enough for welding the lap joints properly. Developed panels have been tested in industrial applications with excellent feedback. If thickness of a corrugated panel structure is not a limiting issue, these panels are good solution on application where stiffness and lighter weight are required as well as vibrational aspect considered.

  3. 78 FR 49255 - Certain Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Partial Rescission of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-13

    ... International Trade Administration Certain Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Partial... certain circular welded carbon steel pipes and tubes from Taiwan. The period of review (POR) is May 1... initiation of an antidumping duty administrative review of the order on certain circular welded carbon...

  4. Microstructural issues in a friction-stir-welded aluminum alloy

    SciTech Connect

    Flores, O.V.; Kennedy, C.; Murr, L.E.; Brown, D.; Pappu, S.; Nowak, B.M.; McClure, J.C.

    1998-02-03

    Recent observations of microstructures associated with friction-stir welding (FSW) in a number of aluminum alloys have consistently demonstrated the actual weld zone to consist of a (dynamically) recrystallized grain structure resulting from the extreme, solid-state, plastic deformation characterizing the process. Because of solubilities associated with the various precipitates in 7075 and 6061 aluminum alloys, and the fact that the precipitates were either homogeneously distributed throughout both the original (unwelded) work-piece plates and the well zones (or formed varying densities of Widmanstaetten patterns within the original and recrystallized grains), it has been difficult to follow the stirring of stable, second-phase particles from the base metal (work-piece) into the weld zone. In the present investigation, a compositionally modified 1100 aluminum alloy (nominally 99.2% Al, 0.5% Fe, 0.15% Cu, 0.12% Si, 0.05 Mn, 0.04 Ti, balance in weight percent of Be and Mg), forming a stable microdendritic (second-phase), equiaxed, cell structure was friction-stir welded. These thermally stable, geometrically specific, precipitates in the base metal were compared with their disposition within the friction-stir-weld zone. In addition, as-cast plates of this alloy were cold-rolled 50% and friction-stir-welded in order to compare these two schedules (as-cast and 50% cold-rolled) in terms of residual hardness variations and related microstructural issues as well as the effect of prior deformation on the friction-stir welding process.

  5. Microstructure of welded and weld-simulated modified 9Cr-1Mo (P 91) ferritic steel

    SciTech Connect

    Prader, R.; Cerjak, H.; David, S.A.

    1996-12-31

    Within the last 30 years significant advances in materials development have been made which have enhanced the operation temperature of thermal power plants led to an improvement in efficiency. Currently, a great deal of work relating to the modified 9% Cr-1/5 Mo steel (P 91) is in progress. This type of steel was originally considered to be an appropriate candidate for Fast Breeder Applications, and it was designed by Oak Ridge National Laboratory. Up to the present, several modifications of 9% chromium steels have been developed in several labs all over the globe containing different portions of tungsten and molybdenum. This report focuses on the microstructural characterization of a heavy section multi pass weld done on a tube composed of P 91 steel. Weld simulations, using the Gleeble 1500 technology, were successfully applied to aid the microstructural study of the heat affected zone (HAZ). As revealed by the investigations, post weld heat treatment (PWHT) results in a softening of the heat affected zone in an area close to the uninfluenced base metal. According to the observed microstructure and Gleeble simulations, the peak temperature of the soft zone during welding falls within a temperature range between A{sub C1} (= 810 C) and slightly above A{sub C3} typically 900--930 C which was discovered for the first time in a previous investigation.

  6. Effect of Seam Welding on Forming Limits of IF-Steel Sheet

    NASA Astrophysics Data System (ADS)

    Sutariya, D.; Raval, H.; Kalaivani, K.; Hariharan, K.; Prabhu, A.; Narasimhan, K.

    2011-08-01

    Laser welding is the most commonly used process for producing Tailor Welded Blanks (TWB). Although laser welding is best suited for TWB applications, it is an expensive process. In this work an alternate cheap process, seam welding, is used to produce welded sheets of IF-steel of same grade and thickness. The effect of this welding on forming limit strains is explored in this work. Forming behavior is characterized by Forming Limit Diagram (FLD). The FLDs of welded blanks are compared with that of un-welded blanks. The effect of longitudinal, transverse and 450 weld orientation on formability is studied. Weld location includes both centered and offset weld location in the transverse weld orientation. Numerical simulations are carried out by considering weld as a zone. Experimental results are compared with the predictions carried out by FE method.

  7. Microstructural design in low alloy steels

    NASA Technical Reports Server (NTRS)

    Honeycombe, R. W. K.

    1982-01-01

    The evolution of microalloyed steels from plain carbon steels is examined with emphasis on grain size control by use of Nb, Ti and V additions and by the application of controlled rolling. The structural changes during controlled rolling are described as well as the influence of alloying elements on these changes, and on the final microstructure. The achievement of high strength and toughness is discussed including the role of inclusions.

  8. Microhardness Testing of Aluminum Alloy Welds

    NASA Technical Reports Server (NTRS)

    Bohanon, Catherine

    2009-01-01

    A weld is made when two pieces of metal are united or fused together using heat or pressure, and sometimes both. There are several different types of welds, each having their own unique properties and microstructure. Strength is a property normally used in deciding which kind of weld is suitable for a certain metal or joint. Depending on the weld process used and the heat required for that process, the weld and the heat-affected zone undergo microstructural changes resulting in stronger or weaker areas. The heat-affected zone (HAZ) is the region that has experienced enough heat to cause solid-state microstructural changes, but not enough to melt the material. This area is located between the parent material and the weld, with the grain structure growing as it progresses respectively. The optimal weld would have a short HAZ and a small fluctuation in strength from parent metal to weld. To determine the strength of the weld and decide whether it is suitable for the specific joint certain properties are looked at, among these are ultimate tensile strength, 0.2% offset yield strength and hardness. Ultimate tensile strength gives the maximum load the metal can stand while the offset yield strength gives the amount of stress the metal can take before it is 0.2% longer than it was originally. Both of these are good tests, but they both require breaking or deforming the sample in some way. Hardness testing, however, provides an objective evaluation of weld strengths, and also the difference or variation in strength across the weld and HAZ which is difficult to do with tensile testing. Hardness is the resistance to permanent or plastic deformation and can be taken at any desired point on the specimen. With hardness testing, it is possible to test from parent metal to weld and see the difference in strength as you progress from parent material to weld. Hardness around grain boundaries and flaws in the material will show how these affect the strength of the metal while still

  9. High strength and corrosion resistant alloys weld overlays for oil patch applications

    SciTech Connect

    Hibner, E.L.; Maligas, M.N.; Vicic, J.C.

    1995-10-01

    Corrosion resistant alloys (CRAs) are specified for oilfield applications where severe environments cause general corrosion, pitting, crevice corrosion, chloride stress corrosion cracking and more importantly sulfide stress cracking. Historically, alloy 625 (UNS N06625) weld overlay has successfully been used in severely corrosive environments. Alloy 686 (UNS N06686) and alloy 725 (UNS N07725) have recently been evaluated as replacement materials for alloy 625. Alloy 686, because of it`s high alloying content, exhibits superior corrosion resistance to alloy 625. And, alloy 725 is a highly corrosion resistant alloy capable of being age hardened to 0.2% yield strengths of above 827 MPa (120 ksi) Mechanical properties and Slow Strain Rate test results for the alloy 686 and alloy 725 weld overlays are discussed relative to alloy 625, alloy C-22 (UNS N06622) and alloy 59 (UNS N06059) weld overlays.

  10. Microstructure and Strength Characteristics of Alloy 617 Welds

    SciTech Connect

    T.C. Totemeier; H. Tian; D.E. Clark; J.A. Simpson

    2005-06-01

    Three types of high-temperature joints were created from alloy 617 base metal: fusion welds, braze joints, and diffusion bonds. The microstructures of all joint types and tensile properties of fusion welds and braze joints were characterized. Sound fusion welds were created by the GTAW process with alloy 617 filler wire. Cross-weld tensile strengths were equal to the parent metal at temperatures of 25, 800, and 1000°C; ductilities of the joints were only slightly lower than that of the parent metal. Failure occurred in the weld fusion zone at room temperature and in the parent metal at elevated temperatures. Incomplete wetting occurred in joints produced by vacuum brazing using AWS BNi-1 braze alloy, believed to be due to tenacious Al and Ti oxide formation. Incompletely bonded butt joints showed relatively poor tensile properties. A second set of braze joints has been created with faying surfaces electroplated with pure Ni prior to brazing; characterization of these joints is in progress. Conditions resulting in good diffusion bonds characterized by grain growth across the bondline and no porosity were determined: vacuum bonding at 1150°C for 3 hours with an initial uniaxial stress of 20 MPa (constant ram displacement). A 15 µm thick pure Ni interlayer was needed to achieve grain growth across the bondline. Tensile testing of diffusion bonds is in progress

  11. Characteristics of laser welded wrought Mg-Al-Mn alloy

    SciTech Connect

    Quan Yajie Chen Zhenhua; Yu Zhaohui; Gong Xiaosan; Li Mei

    2008-12-15

    Magnesium alloys have gained increased attention in recent years as a structural metal because of their property merits, which necessitates the development of welding techniques qualified for applications in the aeronautic and automotive industries. Laser welding is known to be an excellent method for joining metals. In this paper, a 3 kW CO{sub 2} laser beam was used to weld the wrought Mg-Al-Mn alloy. The characteristics of the microstructure and the mechanical properties of the joints were analyzed by optical microscopy (OM), energy dispersive spectrometry (EDS), scanning electron microscopy (SEM), tensile testing and hardness testing. The experimental results show that the wrought Mg-Al-Mn alloy can be joined successfully using optimized welding conditions. The results of tensile testing show that the highest ultimate tensile strength (UTS) of the joints is up to 94% of that of the base metal. The base metal consists of a typical rolled structure, the narrow heat affected zone (HAZ) has no obvious grain coarsening, and the fusion zone consists of fine grains with a high density of {gamma}-Mg{sub 17}Al{sub 12} precipitates. The hardness test results indicate that the microhardness in the fusion zone is higher than that of the base metal. The elemental analysis reveals that the Mg content in the weld is lower than that of the base metal, but the Al content is slightly higher.

  12. Apparatus and process for ultrasonic seam welding stainless steel foils

    DOEpatents

    Leigh, Richard W.

    1992-01-01

    An ultrasonic seam welding apparatus having a head which is rotated to form contact, preferably rolling contact, between a metallurgically inert coated surface of the head and an outside foil of a plurality of layered foils or work materials. The head is vibrated at an ultrasonic frequency, preferably along a longitudinal axis of the head. The head is constructed to transmit vibration through a contacting surface of the head into each of the layered foils. The contacting surface of the head is preferably coated with aluminum oxide to prevent the head from becoming welded to layered stainless steel foils.

  13. Modeling of Linear Gas Tungsten Arc Welding of Stainless Steel

    NASA Astrophysics Data System (ADS)

    Maran, P.; Sornakumar, T.; Sundararajan, T.

    2008-08-01

    A heat and fluid flow model has been developed to solve the gas tungsten arc (GTA) linear welding problem for austenitic stainless steel. The moving heat source problem associated with the electrode traverse has been simplified into an equivalent two-dimensional (2-D) transient problem. The torch residence time has been calculated from the arc diameter and torch speed. The mathematical formulation considers buoyancy, electromagnetic induction, and surface tension forces. The governing equations have been solved by the finite volume method. The temperature and velocity fields have been determined. The theoretical predictions for weld bead geometry are in good agreement with experimental measurements.

  14. 49 CFR 230.33 - Welded repairs and alterations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... containing alloy steel or carbon steel with a carbon content over 0.25 percent. Prior to welding on unstayed... requirements in § 230.20 at this time. (b) Unstayed portions of the boiler containing carbon steel...

  15. 49 CFR 230.33 - Welded repairs and alterations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... containing alloy steel or carbon steel with a carbon content over 0.25 percent. Prior to welding on unstayed... requirements in § 230.20 at this time. (b) Unstayed portions of the boiler containing carbon steel...

  16. 49 CFR 230.33 - Welded repairs and alterations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... containing alloy steel or carbon steel with a carbon content over 0.25 percent. Prior to welding on unstayed... requirements in § 230.20 at this time. (b) Unstayed portions of the boiler containing carbon steel...

  17. Understanding the solidification and microstructure evolution during CSC-MIG welding of Fe–Cr–B-based alloy

    SciTech Connect

    Sorour, A.A. Chromik, R.R. Gauvin, R. Jung, I.-H. Brochu, M.

    2013-12-15

    The present is a study of the solidification and microstructure of Fe–28.2%Cr–3.8%B–1.5%Si–1.5%Mn (wt.%) alloy deposited onto a 1020 plain carbon steel substrate using the controlled short-circuit metal inert gas welding process. The as-solidified alloy was a metal matrix composite with a hypereutectic microstructure. Thermodynamic calculation based on the Scheil–Gulliver model showed that a primary (Cr,Fe){sub 2}B phase formed first during solidification, followed by an eutectic formation of the (Cr,Fe){sub 2}B phase and a body-centered cubic Fe-based solid solution matrix, which contained Cr, Mn and Si. Microstructure analysis confirmed the formation of these phases and showed that the shape of the (Cr,Fe){sub 2}B phase was irregular plate. As the welding heat input increased, the weld dilution increased and thus the volume fraction of the (Cr,Fe){sub 2}B plates decreased while other microstructural characteristics were similar. - Highlights: • We deposit Fe–Cr–B-based alloy onto plain carbon steel using the CSC-MIG process. • We model the solidification behavior using thermodynamic calculation. • As deposited alloy consists of (Cr,Fe){sub 2}B plates embedded in Fe-based matrix. • We study the effect of the welding heat input on the microstructure.

  18. A method for studying weld fusion boundary microstructure evolution in aluminum alloys

    SciTech Connect

    Kostrivas, A.; Lippold, J.C.

    2000-01-01

    Aluminum alloys may exhibit a variety of microstructures within the fusion zone adjacent to the fusion boundary. Under conventional weld solidification conditions, epitaxial nucleation occurs off grains in the heat-affected zone (HAZ) and solidification proceeds along preferred growth directions. In some aluminum alloys, such as those containing Li and Zr, a nondendritic equiaxed grain zone (EQZ) has been observed along the fusion boundary that does not nucleate epitaxially from the HAZ substrate. The EQZ has been the subject of considerable study because of its susceptibility to cracking during initial fabrication and repair. The motivation of this investigation was to develop a technique that would allow the nature and evolution of the fusion boundary to be studied under controlled thermal conditions. A melting technique was developed to simulate the fusion boundary of aluminum alloys using the Gleeble{reg{underscore}sign} thermal simulator. Using a steel sleeve to contain the aluminum, samples wee heated to incremental temperatures above the solidus temperature of a number of alloys. In Alloy 2195, a 4Cu-1Li alloy, an EQZ could be formed by heating in the temperature range approximately from 630--640 C. At temperatures above 640 C, solidification occurred by the normal epitaxial nucleation and growth mechanism. Fusion boundary behavior was also studied in Alloys 5454-H34, 6061-T6 and 2219-T8. Nucleation in these alloys was observed to be epitaxial. Details of the technique and its effectiveness for performing controlled melting experiments at incremental temperatures above the solidus are described.

  19. Studies on A-TIG welding of Low Activation Ferritic/Martensitic (LAFM) steel

    NASA Astrophysics Data System (ADS)

    Vasantharaja, P.; Vasudevan, M.

    2012-02-01

    Low Activation Ferritic-Martensitic steels (LAFM) are chosen as the candidate material for structural components in fusion reactors. The structural components are generally fabricated by welding processes. Activated Tungsten Inert Gas (A-TIG) welding is an emerging process for welding of thicker components. In the present work, attempt was made to develop A-TIG welding technology for LAFM steel plates of 10 mm thick. Activated flux was developed for LAFM steel by carrying out various bead-on-plate TIG welds without flux and with flux. The optimum flux was identified as one which gave maximum depth of penetration at minimum heat input values. With the optimized flux composition, LAFM steel plate of 10 mm thickness was welded in square butt weld joint configuration using double side welding technique. Optical and Scanning Electron Microscopy was used for characterizing the microstructures. Microhardness measurements were made across the weld cross section for as welded and post weld heat treated samples. Tensile and impact toughness properties were determined. The mechanical properties values obtained in A-TIG weld joint were comparable to that obtained in weld joints of LAFM steel made by Electron beam welding process.

  20. Corrosion Behavior of Aluminum-Steel Weld-Brazing Joint

    NASA Astrophysics Data System (ADS)

    Shi, Yu; Li, Jie; Zhang, Gang; Huang, Jiankang; Gu, Yufen

    2016-05-01

    Dissimilar metals of 1060 aluminum and galvanized steel were joined with a lap joint by pulsed double-electrode gas metal arc weld brazing with aluminum-magnesium and aluminum-silicon filler metals. The corrosion behavior of the weld joints was investigated with immersion corrosion and electrochemical corrosion tests, and the corrosion morphology of the joints was analyzed with scanning electron microscopy (SEM). Galvanic corrosion was found to occur when the samples were immersed in corrosive media, and the corrosion rate of joints was increased with increased heat input of the workpiece. Comparison of the corrosion properties of weld joints with different filler wires indicated that the corrosion rate of weld joints with aluminum-silicon filler wire was larger than that of weld joints with aluminum-magnesium filler wire. Results also showed that the zinc-rich zone of weld joints was prone to corrosion. The corrosion behavior of zinc-rich zone was analyzed with SEM equipped with an energy-dispersive x-ray spectroscopy analysis system based on the test results.

  1. Modeling aluminum-lithium alloy welding characteristics

    NASA Technical Reports Server (NTRS)

    Bernstein, Edward L.

    1996-01-01

    The purpose of this project was to develop a finite element model of the heat-affected zone in the vicinity of a weld line on a plate in order to determine an accurate plastic strain history. The resulting plastic strain increments calculated by the finite element program were then to be used to calculate the measure of damage D. It was hoped to determine the effects of varying welding parameters, such as beam power, efficiency, and weld speed, and the effect of different material properties on the occurrence of microfissuring. The results were to be compared first to the previous analysis of Inconel 718, and then extended to aluminum 2195.

  2. Effects of high frequency current in welding aluminum alloy 6061

    NASA Technical Reports Server (NTRS)

    Fish, R. E.

    1968-01-01

    Uncontrolled high frequency current causes cracking in the heat-affected zone of aluminum alloy 6061 weldments during tungsten inert gas ac welding. Cracking developed when an improperly adjusted superimposed high frequency current was agitating the semimolten metal in the areas of grain boundary.

  3. Numerical Microstructural Analysis of Automotive-Grade Steels when Joined with an Array of Welding Processes

    NASA Astrophysics Data System (ADS)

    Gould, J. E.; Khurana, S. P.; Li, T.

    2004-06-01

    Weld strength, formability, and impact resistance for joints on automotive steels is dependent on the underlying microstructure. A martensitic weld area is often a precursor to reduced mechanical performance. In this paper, efforts are made to predict underlying joint microstructures for a range of processing approaches, steel types, and gauges. This was done first by calculating cooling rates for some typical automotive processes [resistance spot welding (RSW), resistance mash seam welding (RMSEW), laser beam welding (LBW), and gas metal arc welding (GMAW)]. Then, critical cooling rates for martensite formation were calculated for a range of automotive steels using an available thermodynamically based phase transformation model. These were then used to define combinations of process type, steel type, and gauge where welds could be formed avoiding martensite in the weld area microstructure.

  4. Stress corrosion cracking of type 304L stainless steel core shroud welds.

    SciTech Connect

    Chung, H. M.; Park, J.-H.; Sanecki, J. E.; Zaluzec, N. J.; Yu, M. S.; Yang, T. T.

    1999-10-26

    Microstructural analyses by advanced metallographic techniques were conducted on mockup welds and a cracked BWR core shroud weld fabricated from Type 304L stainless steel. heat-affected zones of the shroud weld and mockup shielded-metal-arc welds were free of grain-boundary carbide, martensite, delta ferrite, or Cr depletion near grain boundaries. However, as a result of exposure to welding fumes, the heat-affected zones of the welds were significantly contaminated by fluorine and oxygen which migrate to grain boundaries. Significant oxygen contamination promotes fluorine contamination and suppresses classical thermal sensitization, even in Type 304 steels. Results of slow-strain-rate tensile tests indicate that fluorine exacerbates the susceptibility of irradiated steels to intergranular stress corrosion cracking. These observations, combined with previous reports on the strong influence of weld flux, indicate that oxygen and fluorine contamination and fluorine-catalyzed stress corrosion play a major role in cracking of Type 304L stainless steel core shroud welds.

  5. Effects of conventional welding and laser welding on the tensile strength, ultimate tensile strength and surface characteristics of two cobalt-chromium alloys: a comparative study.

    PubMed

    Madhan Kumar, Seenivasan; Sethumadhava, Jayesh Raghavendra; Anand Kumar, Vaidyanathan; Manita, Grover

    2012-06-01

    The purpose of this study was to evaluate the efficacy of laser welding and conventional welding on the tensile strength and ultimate tensile strength of the cobalt-chromium alloy. Samples were prepared with two commercially available cobalt-chromium alloys (Wironium plus and Diadur alloy). The samples were sectioned and the broken fragments were joined using Conventional and Laser welding techniques. The welded joints were subjected to tensile and ultimate tensile strength testing; and scanning electron microscope to evaluate the surface characteristics at the welded site. Both on laser welding as well as on conventional welding technique, Diadur alloy samples showed lesser values when tested for tensile and ultimate tensile strength when compared to Wironium alloy samples. Under the scanning electron microscope, the laser welded joints show uniform welding and continuous molt pool all over the surface with less porosity than the conventionally welded joints. Laser welding is an advantageous method of connecting or repairing cast metal prosthetic frameworks. PMID:23858281

  6. Remote Laser Welding of Zinc Coated Steel Sheets in an Edge Lap Configuration with Zero Gap

    NASA Astrophysics Data System (ADS)

    Roos, Christian; Schmidt, Michael

    Remote Laser Welding (RLW) of zinc-coated steel sheets is a great challenge for the automotive industry but offers high potentials with respect to flexibility and costs. In state of the art applications, sheets are joined in overlap configuration with a preset gap for a stable zinc degassing. This paper investigates RLW of fillets without a preset gap and conditions for a stable process. The influence of process parameters on weld quality and process stability is shown. Experimental data give evidence, that the degassing of zinc through the capillary and the rear melt pool are the major degassing mechanisms. Furthermore the paper gives experimental validation of the zinc degassing in advance of the process zone to the open side of the fillet. Chemical analysis of the hot-dip galvanized zinc coating proof the iron-zinc-alloys to be the reason for a limited effectiveness of this mechanism in comparison to pure zinc as intermediate.

  7. Laser welding of an advanced rapidly-solidified titanium alloy

    NASA Astrophysics Data System (ADS)

    Baeslack, W. A., III; Chiang, S.; Albright, C. A.

    1990-06-01

    The laser weldability of a complex RS titanium alloy containing yttrium is investigated by evaluating comparatively the microstructures, mechanical properties, and fracture characteristics of the base metal and the rapidly solidified weld fusion zone. To prevent atmospheric contamination the specimen was enclosed in a helium-purged plastic bag during the welding process. After welding, the coupons were sectioned transverse to the laser beam direction of traverse, epoxy mounted, polished down to 0.05 micron SiO2 and etched with Kroll's reagent for examination utilizing light and SEM and energy-dispersive X-ray analysis. Results indicate that laser welding is effective in producing a fine fusion zone dispersoid structure in the RS Ti composite.

  8. 75 FR 16439 - Certain Welded Carbon Steel Standard Pipe From Turkey: Preliminary Results of Countervailing Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-01

    ... Steel Pipe and Tube Products from Turkey, 51 FR 7984 (March 7, 1986). On March 2, 2009, the Department... products covered by this order are certain welded carbon steel pipe and tube with an outside diameter of 0... Administrative Review: Certain Welded Carbon Steel Standard Pipe from Turkey, 72 FR 62837, 62838 (November...

  9. Influence of rapid thermal cycles in multipass welding on heat-affected-zone properties in ferritic cryogenic steels

    SciTech Connect

    Kim, H.J.; Shin, H.K.; Morris, J.W. Jr.

    1982-05-01

    The results of both welding and weld simulation studies on 2BT-treated 9Ni steel show that multiple rapid thermal cycles have a very beneficial effect on heat-affected zone toughness at cryogenic temperatures. The metallurgical sources of toughness are, however, different from those in the furnace-treated base plate. The rapidly cycled material contains no detectable austenite phase. The alloy is grain-refined by the rapid thermal cycle, and the matrix carbon content is relieved by the formation of interlathcementite precipitates which do not destroy toughness.

  10. Selecting Processes to Minimize Hexavalent Chromium from Stainless Steel Welding

    PubMed Central

    KEANE, M.; SIERT, A.; STONE, S.; CHEN, B.; SLAVEN, J.; CUMPSTON, A.; ANTONINI, J.

    2015-01-01

    Eight welding processes/shielding gas combinations were assessed for generation of hexavalent chromium (Cr6+) in stainless steel welding fumes. The processes examined were gas metal arc welding (GMAW) (axial spray, short circuit, and pulsed spray modes), flux cored arc welding (FCAW), and shielded metal arc welding (SMAW). The Cr6+ fractions were measured in the fumes; fume generation rates, Cr6+ generation rates, and Cr6+ generation rates per unit mass of welding wire were determined. A limited controlled comparison study was done in a welding shop including SMAW, FCAW, and three GMAW methods. The processes studied were compared for costs, including relative labor costs. Results indicate the Cr6+ in the fume varied widely, from a low of 2800 to a high of 34,000 ppm. Generation rates of Cr6+ ranged from 69 to 7800 μg/min, and Cr6+ generation rates per unit of wire ranged from 1 to 270 μg/g. The results of field study were similar to the findings in the laboratory. The Cr6+ (ppm) in the fume did not necessarily correlate with the Cr6+ generation rate. Physical properties were similar for the processes, with mass median aerodynamic diameters ranging from 250 to 336 nm, while the FCAW and SMAW fumes were larger (360 and 670 nm, respectively). Conclusion: The pulsed axial spray method was the best choice of the processes studied based on minimal fume generation, minimal Cr6+ generation, and cost per weld. This method is usable in any position, has a high metal deposition rate, and is relatively simple to learn and use. PMID:26690276

  11. Weld solidification cracking in 304 to 204L stainless steel

    SciTech Connect

    Hochanadel, Patrick W; Lienert, Thomas J; Martinez, Jesse N; Johnson, Matthew Q

    2010-09-15

    A series of annulus welds were made between 304 and 304L stainless steel coaxial tubes using both pulsed laser beam welding (LBW) and pulsed gas tungsten arc welding (GTAW). In this application, a change in process from pulsed LBW to pulsed gas tungsten arc welding was proposed to limit the possibility of weld solidification cracking since weldability diagrams developed for GTAW display a greater range of compositions that are not crack susceptible relative to those developed for pulsed LBW. Contrary to the predictions of the GTAW weldability diagram, cracking was found.This result was rationalized in terms of the more rapid solidification rate of the pulsed gas tungsten arc welds. In addition, for the pulsed LBW conditions, the material compositions were predicted to be, by themselves, 'weldable' according to the pulsed LBW weldability diagram. However, the composition range along the tie line connecting the two compositions passed through the crack susceptible range. Microstructurally, the primary solidification mode (PSM) of the material processed with higher power LBW was determined to be austenite (A), while solidification mode of the materials processed with lower power LBW apparently exhibited a dual PSM of both austenite (A) and ferrite-austenite (FA) within the same weld. The materials processed by pulsed GTAW showed mostly primary austenite solidification, with some regions of either primary austenite-second phase ferrite (AF) solidification or primary ferrite-second phase austenite (FA) solidification. This work demonstrates that variations in crack susceptibility may be realized when welding different heats of 'weldable' materials together, and that slight variations in processing can also contribute to crack susceptibility.

  12. Weld solidification cracking in 304 to 304L stainless steel

    SciTech Connect

    Hochanadel, Patrick W; Lienert, Thomas J; Martinez, Jesse N; Martinez, Raymond J; Johnson, Matthew Q

    2010-01-01

    A series of annulus welds were made between 304 and 304L stainless steel coaxial tubes using both pulsed laser beam welding (LBW) and pulsed gas tungsten arc welding (GTAW). In this application, a change in process from pulsed LBW to pulsed gas tungsten arc welding was proposed to limit the possibility of weld solidification cracking since weldability diagrams developed for GTAW display a greater range of compositions that are not crack susceptible relative to those developed for pulsed LBW. Contrary to the predictions of the GTAW weldability diagram, cracking was found. This result was rationalized in terms of the more rapid solidification rate of the pulsed gas tungsten arc welds. In addition, for the pulsed LBW conditions, the material compositions were predicted to be, by themselves, 'weldable' according to the pulsed LBW weldability diagram. However, the composition range along the tie line connecting the two compositions passed through the crack susceptible range. Microstructurally, the primary solidification mode (PSM) of the material processed with higher power LBW was determined to be austenite (A), while solidification mode of the materials processed with lower power LBW apparently exhibited a dual PSM of both austenite (A) and ferrite-austenite (FA) within the same weld. The materials processed by pulsed GT A W showed mostly primary austenite solidification, with some regions of either primary austenite-second phase ferrite (AF) solidification or primary ferrite-second phase austenite (FA) solidification. This work demonstrates that variations in crack susceptibility may be realized when welding different heats of 'weldable' materials together, and that slight variations in processing can also contribute to crack susceptibility.

  13. Initial Development in Joining of ODS Alloys Using Friction Stir Welding

    SciTech Connect

    Ren, Weiju; Feng, Zhili

    2007-08-01

    Solid-state welding of oxide-dispersion-strengthened (ODS) alloy MA956 sheets using friction stir welding (FSW) was investigated. Butt weld was successfully produced. The weld and base metals were characterized using optical microscopy, scanning electronic microscopy, transmission electronic microscopy, and energy dispersion x-ray spectrum. Microhardness mapping was also conducted over the weld region. Analyses indicate that the distribution of the strengthening oxides was preserved in the weld. Decrease in microhardness of the weld was observed but was insignificant. The preliminary results seem to confirm the envisioned feasibility of FSW application to ODS alloy joining. For application to Gen IV nuclear reactor heat exchanger, further investigation is suggested.

  14. Resistance spot welding of Ti-6A1-4V alloy

    SciTech Connect

    Jarboe, D.M.

    1980-06-01

    The effects of weld power, electrode force, electrode tip radius, and elapsed time between cleaning and welding on resistance spot welds in Ti-6Al-4V alloy were evaluated. The alloy is weldable by this technique, and a wide latitude can be taken in processing variables.

  15. HEAT INPUT AND POST WELD HEAT TREATMENT EFFECTS ON REDUCED-ACTIVATION FERRITIC/MARTENSITIC STEEL FRICTION STIR WELDS

    SciTech Connect

    Tang, Wei; Chen, Gaoqiang; Chen, Jian; Yu, Xinghua; Frederick, David Alan; Feng, Zhili

    2015-01-01

    Reduced-activation ferritic/martensitic (RAFM) steels are an important class of structural materials for fusion reactor internals developed in recent years because of their improved irradiation resistance. However, they can suffer from welding induced property degradations. In this paper, a solid phase joining technology friction stir welding (FSW) was adopted to join a RAFM steel Eurofer 97 and different FSW parameters/heat input were chosen to produce welds. FSW response parameters, joint microstructures and microhardness were investigated to reveal relationships among welding heat input, weld structure characterization and mechanical properties. In general, FSW heat input results in high hardness inside the stir zone mostly due to a martensitic transformation. It is possible to produce friction stir welds similar to but not with exactly the same base metal hardness when using low power input because of other hardening mechanisms. Further, post weld heat treatment (PWHT) is a very effective way to reduce FSW stir zone hardness values.

  16. CHARACTERIZATION OF DEFECTS IN ALLOY 152, 52 AND 52M WELDS

    SciTech Connect

    Bruemmer, Stephen M.; Toloczko, Mychailo B.; Olszta, Matthew J.; Seffens, Rob J.; Efsing, Pal G.

    2009-08-27

    Defect distributions have been documented by optical metallography, scanning electron microscopy and electron backscatter diffraction in alloy 152 and 52 mockups welds, alloy 52 and 52M overlay mockups and an alloy 52M inlay. Primary defects were small cracks at grain boundaries except for more extensive cracking in the dilution zone of an alloy 52 overlay on 304SS. Detailed characterizations of the dilution zone cracks were performed by analytical transmission electron microscopy identifying grain boundary titanium-nitride precipitation associated with the intergranular separations. I. INTRODUCTION Weldments continue to be a primary location of stress-corrosion cracking (SCC) in light-water reactor systems. While problems related to heat-affected-zone (HAZ) sensitization and intergranular (IG) SCC of austenitic stainless alloys in boiling-water reactors (BWRs) have been significantly reduced, SCC has now been observed in HAZs of non-sensitized materials and in dissimilar metal welds where Ni-base alloy weld metals are used. IGSCC in weld metals has been observed in both BWRs and pressurized water reactors (PWRs) with recent examples for PWR pressure vessel penetrations producing the most concern. This has led to the replacement of alloy 600/182/82 welds with higher Cr, more corrosion-resistant replacement materials (alloy 690/152/52/52M). Complicating this issue has been a known susceptibility to cracking during welding [1-7] of these weld metals. There is a critical need for an improved understanding of the weld metal metallurgy and defect formation in Ni-base alloy welds to effectively assess long-term performance. A series of macroscopic to microscopic examinations were performed on available mockup welds made with alloy 52 or alloy 152 plus selected overlay and inlay mockups. The intent was to expand our understanding of weld metal structures in simulated LWR service components with a focus on as-welded defects. Microstructural features, defect distributions

  17. Weld Bead Size, Microstructure and Corrosion Behavior of Zirconium Alloys Joints Welded by Pulsed Laser Spot Welding

    NASA Astrophysics Data System (ADS)

    Cai, Chuang; Li, Liqun; Tao, Wang; Peng, Genchen; Wang, Xian

    2016-07-01

    Pulsed laser spot welding of intersection points of zirconium alloys straps was performed. Weld bead size, microstructure and the corrosion behavior of weld bead were investigated. With the increasing laser peak power or number of shots, the weld width of the beads increased, the protrusion decreased and the dimple increased with further increase in heat input. The fusion zone consisted of a mixture of αZr and residual βZr phases. After annealing treatment, βNb and Zr(Fe, Nb)2 second phase particles were precipitated inter- and intragranular of αZr grains adequately. The oxide thickness of annealed weld bead was about 3.90 μm, decreased by about 18.1% relative to the 4.76 μm of as-welded specimen corroded at 400 °C and 10.3 MPa for 20 days. The corrosion resistance of annealed specimen was better than that of as-welded specimen, since the second phase particles exerted better corrosion resistance, and the content of Nb in βZr and the fraction of βZr decreased after the annealing treatment.

  18. Fracture assessment for electron beam welded damage tolerant Ti-6Al-4V alloy by the FITNET procedure

    NASA Astrophysics Data System (ADS)

    Lu, Wei; Shi, Yaowu; Li, Xiaoyan; Lei, Yongping

    2013-09-01

    Fracture assessment of the cracked structures is essential to avoiding fracture failure. A number of fracture assessment procedures have been proposed for various steel structures. However, the studies about the application of available procedures for titanium alloy structures are scarcely reported. Fracture assessment for the electron beam(EB) welded thick-walled damage tolerant Ti-6Al-4V(TC4-DT) alloy is performed by the fitness-for-service(FFS) FITNET procedure. Uniaxial tensile tests and fracture assessment tests of the base metal and weld metal are carried out to obtain the input information of assessment. The standard options and advanced options of FITNET FFS procedure are used to the fracture assessment of the present material. Moreover, the predicted maximum loads of compact tensile specimen using FITNET FFS procedure are verified with the experimental data of fracture assessment tests. As a result, it is shown that the mechanical properties of weld metal are inhomogeneous along the weld depth. The mismatch ratio M is less than 10% at the weld top and middle, whereas more than 10% at the weld bottom. Failure assessment lines of standard options are close to that of advanced option, which means that the standard options are suitable for fracture assessment of the present welds. The accurate estimation of the maximum loads has been obtained by fracture assessment of standard options with error less than 6%. Furthermore, there are no potential advantages of applying higher options or mismatch options. Thus, the present welded joints can be treated as homogeneous material during the fracture assessment, and standard option 1 can be used to achieve accurate enough results. This research provides the engineering treatment methods for the fracture assessment of titanium alloy and its EB welds.

  19. Investigation of Strength Recovery in Welds of NUCu-140 Steel Through Multipass Welding and Isothermal Post-Weld Heat Treatments

    NASA Astrophysics Data System (ADS)

    Bono, Jason T.; DuPont, John N.; Jain, Divya; Baik, Sung-Il; Seidman, David N.

    2015-11-01

    NUCu-140 is a ferritic copper precipitation-strengthened steel that is a candidate material for use in many naval and structural applications. Previous work has shown that the heat-affected zone (HAZ) and fusion zone (FZ) of NUCu-140 exhibit softening that is due to dissolution of the copper-rich precipitates. This study aims to recover the FZ and HAZ strength by re-precipitation of the copper-rich precipitates through either multiple weld passes or an isothermal post-weld heat treatment (PWHT). The potential use of multiple thermal cycles was investigated with HAZ simulations using a Gleeble thermo-mechanical simulator. The HAZ simulations represented two weld thermal cycles with different combinations of peak temperatures during the initial and secondary weld passes. To investigate the potential for a PWHT for strength recovery, gas tungsten arc weld samples were isothermally heated for various times and temperatures. Microhardness measurements revealed no strength recovery in the multipass HAZ samples. The time-dependent precipitate characteristics were modeled under the HAZ thermal cycle conditions, and the results showed that the lack of strength recovery could be attributed to insufficient time for re-precipitation during the secondary weld pass. Conversely, full strength recovery in the HAZ was observed in the isothermally heat treated samples. Atom probe tomography analysis correlated this strength recovery to re-precipitation of the copper-rich precipitates during the isothermal PWHT.

  20. Microstructural development of diffusion-brazed austenitic stainless steel to magnesium alloy using a nickel interlayer

    SciTech Connect

    Elthalabawy, Waled M.; Khan, Tahir I.

    2010-07-15

    The differences in physical and metallurgical properties of stainless steels and magnesium alloys make them difficult to join using conventional fusion welding processes. Therefore, the diffusion brazing of 316L steel to magnesium alloy (AZ31) was performed using a double stage bonding process. To join these dissimilar alloys, the solid-state diffusion bonding of 316L steel to a Ni interlayer was carried out at 900 deg. C followed by diffusion brazing to AZ31 at 510 deg. C. Metallographic and compositional analyses show that a metallurgical bond was achieved with a shear strength of 54 MPa. However, during the diffusion brazing stage B{sub 2} intermetallic compounds form within the joint and these intermetallics are pushed ahead of the solid/liquid interface during isothermal solidification of the joint. These intermetallics had a detrimental effect on joint strengths when the joint was held at the diffusion brazing temperature for longer than 20 min.

  1. Welding of Mo-Based Alloy Using Electron Beam and Laser-GTAW Hybrid Welding Techniques

    NASA Astrophysics Data System (ADS)

    Chatterjee, Anjan; Kumar, Santosh; Tewari, Raghvendra; Dey, Gautam Kumar

    2016-03-01

    In the current study, welding of TZM (molybdenum-based alloy) plates in square-butt configuration was carried out using electron beam and laser-GTAW hybrid power sources. Microstructures of weld joint containing three zones—parent metal, heat-affected zone, and fusion zone—were clearly identified when examined through optical and scanning electron microscopy. The weld joints were found to be sound with very wide fusion and heat-affected zones. The microstructure of the fusion zone was coarse-grained. as-solidified microstructure, while the microstructure of heat-affected zone was the recrystallized microstructure with reduction in grain size as distance from the fusion line increased. Microhardness profile using Vickers hardness tester was obtained across the weld region, and the tensile properties of the weld joints were evaluated by performing room temperature tensile test and fracture was examined using scanning electron microscope. Joint coefficient of the weld joints were ~40 to 45 pct of that of the parent metals with nonmeasurable tensile ductility with predominantly transgranular mode of fracture indicating weakness along the grain boundary. Detailed orientation imaging and transmission electron microscopy were carried out to understand the most dominating factor in introducing weld joint brittleness.

  2. Electrochemical Testing of Gas Tungsten Arc Welded and Reduced Pressure Electron Beam Welded Alloy 22

    SciTech Connect

    Day, S D; Wong, F G; Gordon, S R; Wong, L L; Rebak, R B

    2006-02-05

    Alloy 22 (N06022) is the material selected for the fabrication of the outer shell of the nuclear waste containers for the Yucca Mountain high-level nuclear waste repository site. A key technical issue in the waste package program has been the integrity of the container weld joints. The currently selected welding process for fabricating and sealing the containers is the traditional gas tungsten arc welding (GTAW) or TIG method. An appealing faster alternative technique is reduced pressure electron beam (RPEB) welding. It was of interest to compare the corrosion properties of specimens prepared using both types of welding techniques. Standard electrochemical tests were carried on GTAW and RPEB welds as well as on base metal (non-welded) to determine their relative corrosion behavior in simulated concentrated water (SCW) at 90 C (alkaline), 1 M HCl at 60 C (acidic) and 1 M NaCl at 90 C (neutral) solutions. Results show that for all practical purposes, the three tested materials had the same electrochemical behavior in the three tested electrolytes.

  3. Electrochemical Testing of Gas Tungsten ARC Welded and Reduced Pressure Electron Beam Welded Alloy 22

    SciTech Connect

    S. Daniel Day; Frank M.G. Wong; Steven R. Gordon; Lana L. Wong; Raul B. Rebak

    2006-05-08

    Alloy 22 (N06022) is the material selected for the fabrication of the outer shell of the nuclear waste containers for the Yucca Mountain high-level nuclear waste repository site. A key technical issue in the waste package program has been the integrity of the container weld joints. The currently selected welding process for fabricating and sealing the containers is the traditional gas tungsten arc welding (GTAW) or TIC method. An appealing faster alternative technique is reduced pressure electron beam (RPEB) welding. It was of interest to compare the corrosion properties of specimens prepared using both types of welding techniques. Standard electrochemical tests were carried on GTAW and RPEB welds as well as on base metal (non-welded) to determine their relative corrosion behavior in simulated concentrated water (SCW) at 90 C (alkaline), 1 M HCI at 60 C (acidic) and 1 M NaCl at 90 C (neutral) solutions. Results show that for all practical purposes, the three tested materials had the same electrochemical behavior in the three tested electrolytes.

  4. Crack growth rates of irradiated austenitic stainless steel weld heat affected zone in BWR environments.

    SciTech Connect

    Chopra, O. K.; Alexandreanu, B.; Gruber, E. E.; Daum, R. S.; Shack, W. J.; Energy Technology

    2006-01-31

    Austenitic stainless steels (SSs) are used extensively as structural alloys in the internal components of reactor pressure vessels because of their superior fracture toughness. However, exposure to high levels of neutron irradiation for extended periods can exacerbate the corrosion fatigue and stress corrosion cracking (SCC) behavior of these steels by affecting the material microchemistry, material microstructure, and water chemistry. Experimental data are presented on crack growth rates of the heat affected zone (HAZ) in Types 304L and 304 SS weld specimens before and after they were irradiated to a fluence of 5.0 x 10{sup 20} n/cm{sup 2} (E > 1 MeV) ({approx} 0.75 dpa) at {approx}288 C. Crack growth tests were conducted under cycling loading and long hold time trapezoidal loading in simulated boiling water reactor environments on Type 304L SS HAZ of the H5 weld from the Grand Gulf reactor core shroud and on Type 304 SS HAZ of a laboratory-prepared weld. The effects of material composition, irradiation, and water chemistry on growth rates are discussed.

  5. Welding low thermal expansion alloys for aircraft composite tooling

    SciTech Connect

    Otte, W.H.; O`Donnell, D.B.; Kiser, S.D.; Cox, C.W.

    1996-07-01

    To save weight in commercial aircraft and help military jets evade radar detection, aircraft designers specify the use of composite materials. These new designs have resulted in the use of low-expansion materials for aircraft composite tooling because they keep their dimensions during curing. However, the Fe-Ni low-expansion alloys have long presented problems during welding. When matching composition filler metals were used to match the coefficient of thermal expansion (CTE), cracking problems occurred. Filler metal compositional changes to eliminate cracking disturbed the CTE match of the weld with the base metal. A recently developed welding consumable appears to eliminate those problems. With the development of this new filler metal, high-quality crack-free welds can now be obtained with high deposition rates. Since there is a more closely-matched CTE, weldments and tools should provide longer service because of minimal effects from thermal fatigue. There have been reports of vacuum leaks in tools using the Mn-Ti filler metal, which could be directly attributable to the mismatching CTE. Using Nilo filler metal CF36 eliminates weld hot-cracking problems and provides good thermal fatigue resistance due to its excellent CTE match with the base metal, Nilo alloy 36.

  6. Effects of Welding Processes and Post-Weld Aging Treatment on Fatigue Behavior of AA2219 Aluminium Alloy Joints

    NASA Astrophysics Data System (ADS)

    Malarvizhi, S.; Balasubramanian, V.

    2011-04-01

    AA2219 aluminium alloy square butt joints without filler metal addition were fabricated using gas tungsten arc welding (GTAW), electron beam welding (EBW), and friction stir welding (FSW) processes. The fabricated joints were post-weld aged at 175 °C for 12 h. The effect of three welding processes and post-weld aging (PWA) treatment on the fatigue properties is reported. Transverse tensile properties of the welded joints were evaluated. Microstructure analysis was also carried out using optical and electron microscopes. It was found that the post-weld aged FSW joints showed superior fatigue performance compared to EBW and GTAW joints. This was mainly due to the formation of very fine, dynamically recrystallized grains and uniform distribution of fine precipitates in the weld region.

  7. Qualification of welded super 13%Cr martensitic stainless steels for sour service applications

    SciTech Connect

    Enerhaug, J.; Eliassen, S.L.; Kvaale, P.E.

    1997-08-01

    A test program has been carried out to qualify welded super 13%Cr stainless steels for sour service applications. The test program included weldability trials, weld simulations, mechanical testing and corrosion testing of 13%Cr steels from five different steel mills. Two of the tested steels have been qualified for use as flowline materials in some parts of new sour service fields. The result shows excellent weldability properties and acceptable corrosion properties. Post weld heat treatment (PWHT) of the welds improved the resistance towards sulfide stress corrosion cracking significantly.

  8. Influence of Welding With Two-Jet Gas Shielding On the Shaping of a Welding Joint

    NASA Astrophysics Data System (ADS)

    Chinakhov, D. A.; Chinakhova, E. D.; Grichin, S. V.; Gotovschik, Y. M.

    2016-04-01

    The author considers gas-dynamic influence upon microhardness and weld configuration of single-pass welds from steel 30HGSA when welding with consumable electrode under double-jet shielding. The relations to the chosen controlled welding parameters (Q, L, I) are developed and the controlling influence of the gas-dynamic affect of dynamic shield gas jet over formation of welds from alloy-treated steel 30HGSA is determined.

  9. Corrosion resistance of the welded joints of a number of structural alloys in a NaOH melt

    NASA Astrophysics Data System (ADS)

    Yurkinskii, V. P.; Firsova, E. G.; Baturova, L. P.

    2015-02-01

    The results of studying the corrosion resistance of the homogenous and heterogeneous welded joints of nickel alloys (Monel 500, Inconel) and stainless steel in a deaerated NaOH melt at a temperature of 500°C are presented. The effect of homogenizing annealing of the welded joints on their corrosion behavior is investigated. The microstructure and the phase composition of the surface layers formed on these materials in the NaOH melt during corrosion tests are studied by X-ray diffraction and electron microscopy.

  10. FRICTION STIR SPOT WELDING OF 6016 ALUMINUM ALLOY

    SciTech Connect

    Mishra, Rajiv S.; Webb, S.; Freeney, T. A.; Chen, Y. L.; Gayden, X.; Grant, Glenn J.; Herling, Darrell R.

    2007-01-08

    Friction stir spot welding (FSSW) of 6016 aluminum alloy was evaluated with conventional pin tool and new off-center feature tools. The off-center feature tool provides significant control over the joint area. The tool rotation rate was varied between 1000 and 2500 rpm. Maximum failure strength was observed in the tool rotation range of 1200-1500 rpm. The results are interpreted in the context of material flow in the joint and influence of thermal input on microstructural changes. The off-center feature tool concept opens up new possibilities for plunge-type friction stir spot welding.

  11. Friction Stir Welding of a Thick Al-Zn-Mg Alloy Plate

    NASA Astrophysics Data System (ADS)

    Buchibabu, V.; Reddy, G. M.; Kulkarni, D.; De, A.

    2016-03-01

    Al-Zn-Mg alloys are widely used as structural materials due to high strength-to-weight ratio and impact toughness. As fusion welds in these alloys commonly face hot cracking and macro porosity, friction stir welding is increasingly becoming the preferred recourse. We report here a detailed experimental study on friction stir welding of a specific Al-Zn-Mg alloy with its chemical compositions close to AA7039. The effect of tool rotational speed and welding speed on the weld profile, joint microstructure, and mechanical properties is studied extensively. The results show sound weld profiles and joint properties within the selected range of process conditions. Within the selected range of welding conditions, the welds made at a tool rotational speed of 350 rpm and welding speed of 3 mm/s have showed joint structure, tensile, and impact toughness properties fairly close to that of the base material.

  12. Impact of tool wear on joint strength in friction stir spot welding of DP 980 steel

    SciTech Connect

    Miles, Michael; Ridges, Chris; Hovanski, Yuri; Peterson, Jeremy; Santella, M. L.; Steel, Russel

    2011-09-14

    Friction stir spot welding has been shown to be a viable method of joining ultra high strength steel (UHSS), both in terms of joint strength and process cycle time. However, the cost of tooling must be reasonable in order for this method to be adopted as an industrial process. Recently a new tool alloy has been developed, using a blend of PCBN and tungsten rhenium (W-Re) in order to improve the toughness of the tool. Wear testing results are presented for two of these alloys: one with a composition of 60% PCBN and 40% W-Re, and one with 70% PCBN and 30% W-Re. The sheet material used for all wear testing was 1.4 mm DP 980. Lap shear testing was used to show the relationship between tool wear and joint strength. The Q70 tool provided the best combination of wear resistance and joint strength.

  13. Strength analysis of laser welded lap joint for ultra high strength steel

    NASA Astrophysics Data System (ADS)

    Jeong, Young Cheol; Kim, Cheol Hee; Cho, Young Tae; Jung, Yoon Gyo

    2013-12-01

    Several industries including the automotive industry have recently applied the process of welding high strength steel. High strength steel is steel that is harder than normal high strength steel, making it much stronger and stiffer. HSS can be formed in pieces that can be up to 10 to 15 percent thinner than normal steel without sacrificing strength, which enables weight reduction and improved fuel economy. Furthermore, HSS can be formed into complex shapes that can be welded into structural areas. This study is based on previous experiments and is aimed at establishing the stress distribution for laser welded high strength steel. Research on the stress distribution for laser welded high strength steel is conducted by using Solid Works, a program that analyzes the stress of a virtual model. In conclusion, we found that the stress distribution is changed depending on the shape of welded lap joint. In addition, the Influence of the stress distribution on welded high strength steel can be used to standard for high energy welding of high strength steel, and we can also predict the region in welded high strength steel that may cracked.

  14. Creep rupture strength of activated-TIG welded 316L(N) stainless steel

    NASA Astrophysics Data System (ADS)

    Sakthivel, T.; Vasudevan, M.; Laha, K.; Parameswaran, P.; Chandravathi, K. S.; Mathew, M. D.; Bhaduri, A. K.

    2011-06-01

    316L(N) stainless steel plates were joined using activated-tungsten inert gas (A-TIG) welding and conventional TIG welding process. Creep rupture behavior of 316L(N) base metal, and weld joints made by A-TIG and conventional TIG welding process were investigated at 923 K over a stress range of 160-280 MPa. Creep test results showed that the enhancement in creep rupture strength of weld joint fabricated by A-TIG welding process over conventional TIG welding process. Both the weld joints fractured in the weld metal. Microstructural observation showed lower δ-ferrite content, alignment of columnar grain with δ-ferrite along applied stress direction and less strength disparity between columnar and equiaxed grains of weld metal in A-TIG joint than in MP-TIG joint. These had been attributed to initiate less creep cavitation in weld metal of A-TIG joint leading to improvement in creep rupture strength.

  15. Corrosion fatigue crack growth in clad low-alloy steels: Part 1, medium-sulfur forging steel

    SciTech Connect

    James, L.A.; Poskie, T.J.; Auten, T.A; Cullen, W.H.

    1996-04-01

    Corrosion fatigue crack propagation tests were conducted on a medium- sulfur ASTM A508-2 forging steel overlaid with weld-deposited Alloy EN82H cladding. The specimens featured semi-elliptical surface cracks penetrating approximately 6.3 mm of cladding into the underlying steel. The initial crack sizes were relatively large with surface lengths of 30.3--38.3 mm, and depths of 13.1--16.8 mm. The experiments were conducted in a quasi-stagnant low-oxygen (O{sub 2} < 10 ppb) aqueous environment at 243{degrees}C, under loading conditions ({Delta}K, R, and cyclic frequency) conductive to environmentally-assisted cracking (EAC) in higher-sulfur steels under quasi-stagnant conditions. Earlier experiments on unclad compact tension specimens of this heat of steel did not exhibit EAC, and the present experiments on semi-elliptical surface cracks penetrating cladding also did not exhibit EAC.

  16. Corrosion of alloy steels in oil field fluids

    SciTech Connect

    Martin, R.L.

    1987-01-01

    Laboratory and field tests have been conducted on two low alloy and two higher alloy steels at a range of brine salinities and sulfide contents typical of oil well production fluids. AISI types 4130 and 4340 show the same behavior in these fluids as mild steel. AISI type 410 stainless steel and 9% chromium - 1% molybdenum steel corrode at rates as great as that of mild steel at higher chloride or sulfide concentrations. Special corrosion inhibitors are required for higher alloy steels when they are exposed to these conditions.

  17. Effect of rhenium on the structure and properties of the weld metal of a molybdenum alloy

    NASA Technical Reports Server (NTRS)

    Dyachenko, V. V.; Morozov, B. P.; Tylkina, M. A.; Savitskiy, Y. M.; Nikishanov, V. V.

    1984-01-01

    The structure and properties of welds made in molybdenum alloy VM-1 as a function of rhenium concentrations in the weld metal were studied. Rhenium was introduced into the weld using rhenium wire and tape or wires of Mo-47Re and Mo-52Re alloys. The properties of the weld metal were studied by means of metallographic techniques, electron microscopy, X-ray analysis, and autoradiography. The plasticity of the weld metal sharply was found to increase with increasing concentration of rhenium up to 50%. During welding, a decarburization process was observed which was more pronounced at higher concentrations of rhenium.

  18. Application of YAG Laser TIG Arc Hybrid Welding to Thin AZ31B Magnesium Alloy Sheet

    NASA Astrophysics Data System (ADS)

    Kim, Taewon; Kim, Jongcheol; Hasegawa, Yu; Suga, Yasuo

    A magnesium alloy is said to be an ecological material with high ability of recycling and lightweight property. Especially, magnesium alloys are in great demand on account of outstanding material property as a structural material. Under these circumstances, research and development of welding process to join magnesium alloy plates are of great significance for wide industrial application of magnesium. In order to use it as a structure material, the welding technology is very important. TIG arc welding process is the most ordinary process to weld magnesium alloy plates. However, since the heat source by the arc welding process affects the magnesium alloy plates, HAZ of welded joint becomes wide and large distortion often occurs. On the other hand, a laser welding process that has small diameter of heat source seems to be one of the possible means to weld magnesium alloy in view of the qualitative improvement. However, the low boiling point of magnesium generates some weld defects, including porosity and solidification cracking. Furthermore, precise edge preparation is very important in butt-welding by the laser welding process, due to the small laser beam diameter. Laser/arc hybrid welding process that combines the laser beam and the arc is an effective welding process in which these two heat sources influence and assist each other. Using the hybrid welding, a synegistic effect is achievable and the disadvantages of the respective processes can be compensated. In this study, YAG laser/TIG arc hybrid welding of thin magnesium alloy (AZ31B) sheets was investigated. First of all, the effect of the irradiation point and the focal position of laser beam on the quality of a weld were discussed in hybrid welding. Then, it was confirmed that a sound weld bead with sufficient penetration is obtained using appropriate welding conditions. Furthermore, it was made clear that the heat absorption efficiency is improved with the hybrid welding process. Finally, the tensile tests

  19. Stainless steel welding and semen quality

    SciTech Connect

    Jelnes, J.E.; Knudsen, L.E. )

    1988-01-01

    Questionnaire studies of patients from fertility clinics suggest that welders may have an increased risk of reduced semen quality. In this study, welders and nonwelders from the same plants were asked to provide blood, urine, and semen samples. Urine was analyzed for chromium and nickel, and for mutagenic activity and metal concentration; blood for metal concentrations, immunoglobulin G, total protein, and measures of genotoxicity in lymphocytes; and semen was evaluated by standard semen analysis. Results of the semen evaluation, presented here, showed no difference in semen quality between welders and nonwelders. Because the metal dust exposure of nonwelders in the plant may be higher than that in the general population, welders were also compared to referents not working in the metal industry. Again, no decrease in semen quality associated with welding was demonstrated.

  20. Laser beam surface melting of high alloy austenitic stainless steel

    SciTech Connect

    Woollin, P.

    1996-12-31

    The welding of high alloy austenitic stainless steels is generally accompanied by a substantial reduction in pitting corrosion resistance relative to the parent, due to microsegregation of Mo and Cr. This prevents the exploitation of the full potential of these steels. Processing to achieve remelting and rapid solidification offers a means of reducing microsegregation levels and improving corrosion resistance. Surface melting of parent UNS S31254 steel by laser beam has been demonstrated as a successful means of producing fine, as-solidified structures with pitting resistance similar to that of the parent, provided that an appropriate minimum beam travel speed is exceeded. The use of N{sub 2} laser trail gas increased the pitting resistance of the surface melted layer. Application of the technique to gas tungsten arc (GTA) melt runs has shown the ability to raise the pitting resistance significantly. Indeed, the use of optimized beam conditions, N{sub 2} trail gas and appropriate surface preparation prior to laser treatment increased the pitting resistance of GTA melt runs to a level approaching that of the parent material.

  1. Microstructure and Properties of Lap Joint Between Aluminum Alloy and Galvanized Steel by CMT

    NASA Astrophysics Data System (ADS)

    Niu, Song; Chen, Su; Dong, Honggang; Zhao, Dongsheng; Zhang, Xiaosheng; Guo, Xin; Wang, Guoqiang

    2016-05-01

    Lap joining of 1-mm-thick Novelist AC 170 PX aluminum alloy to 1.2-mm-thick ST06 Z galvanized steel sheets for automotive applications was conducted by cold metal transfer advanced welding process with ER4043 and ER4047 filler wires. Under the optimized welding parameters with ER4043 filler wire, the tensile shear strength of joint was 189 MPa, reaching 89% of the aluminum alloy base metal. Microstructure and elemental distribution were characterized by optical metalloscope and electron probe microanalysis. The lap joints with ER4043 filler wire had smaller wetting angle and longer bonded line length with better wettability than with ER4047 filler wire during welding with same parameters. The needle-like Al-Fe-Si intermetallic compounds (IMCs) were spalled into the weld and brought negative effect to the tensile strength of joints. With increasing welding current, the needle-like IMCs grew longer and spread further into the weld, which would deteriorate the tensile shear strength.

  2. Microstructure and Properties of Lap Joint Between Aluminum Alloy and Galvanized Steel by CMT

    NASA Astrophysics Data System (ADS)

    Niu, Song; Chen, Su; Dong, Honggang; Zhao, Dongsheng; Zhang, Xiaosheng; Guo, Xin; Wang, Guoqiang

    2016-04-01

    Lap joining of 1-mm-thick Novelist AC 170 PX aluminum alloy to 1.2-mm-thick ST06 Z galvanized steel sheets for automotive applications was conducted by cold metal transfer advanced welding process with ER4043 and ER4047 filler wires. Under the optimized welding parameters with ER4043 filler wire, the tensile shear strength of joint was 189 MPa, reaching 89% of the aluminum alloy base metal. Microstructure and elemental distribution were characterized by optical metalloscope and electron probe microanalysis. The lap joints with ER4043 filler wire had smaller wetting angle and longer bonded line length with better wettability than with ER4047 filler wire during welding with same parameters. The needle-like Al-Fe-Si intermetallic compounds (IMCs) were spalled into the weld and brought negative effect to the tensile strength of joints. With increasing welding current, the needle-like IMCs grew longer and spread further into the weld, which would deteriorate the tensile shear strength.

  3. Investigation on the Explosive Welding of 1100 Aluminum Alloy and AZ31 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Chen, Pengwan; Feng, Jianrui; Zhou, Qiang; An, Erfeng; Li, Jingbo; Yuan, Yuan; Ou, Sanli

    2016-07-01

    The undesirable properties of magnesium alloys include easy embrittlement, low oxidation resistance, and difficulty in welding with other materials. Their application in industry is, therefore, restricted. In this paper, plates of 1100 aluminum alloy and AZ31 magnesium alloy were successfully welded together using the explosive welding technique. The influences of the welding parameters on the weld quality were investigated. The surface morphology and microstructure near the weld interface were examined by optical microscopy, scanning electron microscopy (equipped with energy-dispersive x-ray spectroscopy), and transmission electron microscopy. The experimental results demonstrated the typical wavy bonding interface. In addition, elemental diffusion with a thickness of approximately 3 μm occurred near the bonding interface. The two plates were joined together well at the atomic scale. Nanograins with a size of approximately 5 nm were observed in the diffusion layer. The microhardness and shear strength were measured to evaluate the mechanical properties, which confirmed that a high quality of bonding was acquired.

  4. Investigation on the Explosive Welding of 1100 Aluminum Alloy and AZ31 Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Chen, Pengwan; Feng, Jianrui; Zhou, Qiang; An, Erfeng; Li, Jingbo; Yuan, Yuan; Ou, Sanli

    2016-06-01

    The undesirable properties of magnesium alloys include easy embrittlement, low oxidation resistance, and difficulty in welding with other materials. Their application in industry is, therefore, restricted. In this paper, plates of 1100 aluminum alloy and AZ31 magnesium alloy were successfully welded together using the explosive welding technique. The influences of the welding parameters on the weld quality were investigated. The surface morphology and microstructure near the weld interface were examined by optical microscopy, scanning electron microscopy (equipped with energy-dispersive x-ray spectroscopy), and transmission electron microscopy. The experimental results demonstrated the typical wavy bonding interface. In addition, elemental diffusion with a thickness of approximately 3 μm occurred near the bonding interface. The two plates were joined together well at the atomic scale. Nanograins with a size of approximately 5 nm were observed in the diffusion layer. The microhardness and shear strength were measured to evaluate the mechanical properties, which confirmed that a high quality of bonding was acquired.

  5. Mechanical Properties and Microstructure of Dissimilar Friction Stir Welds of 11Cr-Ferritic/Martensitic Steel to 316 Stainless Steel

    NASA Astrophysics Data System (ADS)

    Sato, Yutaka S.; Kokawa, Hiroyuki; Fujii, Hiromichi T.; Yano, Yasuhide; Sekio, Yoshihiro

    2015-12-01

    Dissimilar joints between ferritic and austenitic steels are of interest for selected applications in next generation fast reactors. In this study, dissimilar friction-stir welding of an 11 pct Cr ferritic/martensitic steel to a 316 austenitic stainless steel was attempted and the mechanical properties and microstructure of the resulting welds were examined. Friction-stir welding produces a stir zone without macroscopic weld-defects, but the two dissimilar steels are not intermixed. The two dissimilar steels are interleaved along a sharp zigzagging interface in the stir zone. During small-sized tensile testing of the stir zone, this sharp interface did not act as a fracture site. Furthermore, the microstructure of the stir zone was refined in both the ferritic/martensitic steel and the 316 stainless steel resulting in improved mechanical properties over the adjacent base material regions. This study demonstrates that friction-stir welding can produce welds between dissimilar steels that contain no macroscopic weld-defects and display suitable mechanical properties.

  6. Highly corrosion resistant weld overlay for oil patch applications

    SciTech Connect

    Hibner, E.L.; Maligas, M.N.; Vicic, J.C.

    1994-12-31

    Petroleum equipment companies currently sell 4130 and 4140 steel pipe with alloy 625 (UNS N06625) weld overlay for Oil Patch applications. Alloy 686 (UNS N06686), because of it`s superior corrosion resistance, is currently being evaluated as a replacement material for alloy 625. Mechanical properties and Slow Strain Rate test results for the alloy 686 weld overlay are discussed relative to the alloy 625 weld overlay.

  7. Impact Welding of Aluminum to Copper and Stainless Steel by Vaporizing Foil Actuator: Effect of Heat Treatment Cycles on Mechanical Properties and Microstructure

    NASA Astrophysics Data System (ADS)

    Vivek, Anupam; Hansen, Steven; Benzing, Jake; He, Mei; Daehn, Glenn

    2015-10-01

    This work studies the mechanical property effect of microstructure on impact welds of aluminum alloy AA6061 with both copper alloy Cu 110 and stainless steel AISI 304. AA6061-T6 and T4 temper aluminum sheets of 1 mm thickness were launched toward copper and stainless steel targets using the vaporizing foil actuator technique. Flyer plate velocities, measured via photonic Doppler velocimetry, were observed to be approximately 800 m/s. The welded aluminum-copper samples were subjected to instrumented peel testing, microhardness testing, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. The welded joints exhibited cracks through their continuous intermetallic layers. The cracks were impeded upon encountering a ductile metallic wave. The welds created with T6 temper flyer sheets were found to have smaller intermetallic-free and wavy interface regions as compared to those created with T4 temper flyer sheets. Peel strength tests of the two weld combinations resulted in failure along the interface in the case of the T6 flyer welds, while the failure generally occurred in the parent aluminum for the T4 temper flyer welds. Half of the T4 flyer welds were subjected to aging for 18 h at 433 K (160 °C) to convert the aluminum sheet to the T6 condition. Although the aged flyer material did not attain the hardness of the as-received T6 material, it was found to be significantly stronger than the T4 material. These welds retained their strength after the aging process, and diffusion across the interface was minimal. The welded aluminum-stainless steel samples were analyzed on a more basic level than aluminum-copper samples, but were found to exhibit similar results.

  8. Joint properties of cast Fe-Pt magnetic alloy laser-welded to Co-Cr alloy.

    PubMed

    Baba, Naoki; Watanabe, Ikuya; Tanaka, Yasuhiro; Hisatsune, Kunihiro; Atsuta, Mitsuru

    2005-12-01

    This study investigated the joint properties of Fe-Pt alloy laser-welded to Co-Cr alloy. Cast plates (0.5 x 3.0 x 10 mm) were prepared with Fe-Pt and Co-Cr alloys. Fe-Pt plates were butted against Co-Cr plates and laser-welded using Nd:YAG laser. Control and homogeneously welded specimens were also prepared. Laser welding was performed with and without argon shielding. Tensile testing was conducted, and both fracture force (Ff: N) and elongation (El: %) were recorded. There were no differences in the Ff value between the specimens with and without argon shielding for the welded Fe-Pt/Co-Cr. Lower Ff value of the welded specimen was obtained in the order of Fe-Pt alloy < Fe-Pt/Co-Cr < Co-Cr alloy. The results indicated that Fe-Pt welded to Co-Cr had Ff values between the values of homogeneously welded Fe-Pt and Co-Cr alloys. Argon shielding, on the other hand, had no effect on the weld strength between Fe-Pt and Co-Cr alloys. PMID:16445017

  9. Integrated thermal-microstructure model to predict the property gradients in resistance spot steel welds

    SciTech Connect

    Babu, S.S.; Riemer, B.W.; Santella, M.L.; Feng, Z.

    1998-11-01

    An integrated model approach was proposed for relating resistance welding parameters to weldment properties. An existing microstructure model was used to determine the microstructural and property gradients in resistance spot welds of plain carbon steel. The effect of these gradients on the weld integrity was evaluated with finite element analysis. Further modifications to this integrated thermal-microstructure model are discussed.

  10. 49 CFR 178.47 - Specification 4DS welded stainless steel cylinders for aircraft use.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...-3 (IBR, see § 171.7 of this subchapter). All seams of the sphere or cylinder must be fusion welded... joint. (e) Attachments. Attachments to the container are authorized by fusion welding provided that such... stainless steel securely attached to the container by fusion welding. (2) Attachments to a fitting, boss,...

  11. Weldability of A7075-T651 and AZ31B dissimilar alloys by MIG welding method based on welding appearances

    NASA Astrophysics Data System (ADS)

    Ishak, M.; Islam, M. R.

    2014-04-01

    It is not recommended to weld aluminium and magnesium dissimilar alloys using fusion welding method because of the formation of AlmMgn type intermetallic brittle compounds like Mg2Al3, Mg17Al12 etc. in the welding joint. These brittle compounds deteriorate the mechanical properties of the joint. But so far, insufficient researches have been attempted to stop the formation of AlmMgn type intermetallic brittle compounds in fusion welding method. The aim of this research work was to investigate on the weldability between A7075-T651 and AZ31B dissimilar alloys based on welding appearances and study the formation of intermetallic brittle compounds at the joint. In this research, A7075-T651 and AZ31B alloys were welded using ER5356 filler wire in MIG welding method in butt configuration. 100% argon was used as shielding gas. The results showed that, most of the welding appearances were moderate. The macroscopic investigation at all welding cross section showed that a lot of AlmMgn intermetallic brittle compounds were formed at the interface between weld seam and AZ31B parent metal side which caused macro cracks. A good number of macro pores were also observed at AZ31B parent metal side. These cracks and pores could easily cause the failure of the joint at very low stress.

  12. Shielding gas effect on weld characteristics in arc-augmented laser welding process of super austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Sathiya, P.; Kumar Mishra, Mahendra; Soundararajan, R.; Shanmugarajan, B.

    2013-02-01

    A series of hybrid welding (gas metal arc welding-CO2 laser beam welding) experiments were conducted on AISI 904L super austenitic stainless steel sheet of 5 mm thickness. A detailed study of CO2 Laser-GMAW hybrid welding experiments with different shielding gas mixtures (100% He, 50% He+50% Ar, 50%He+45% Ar+5% O2, and 45% He+45% Ar+10% N2) were carried out and the results are presented. The resultant welds were subjected to detailed mechanical and microstructural characterization. Hardness testing revealed that the hardness values in the fusion zone were higher than the base material irrespective of the parameters. Transverse tensile testing showed that the joint efficiency is 100% with all the shielding gas experimented. Impact energy values of the welds were also found to be higher than the base material and the fractrograph taken in scanning electron microscope (SEM) has shown that the welds exhibited dimple fracture similar to the base material.

  13. Stainless steel manual metal arc welding fumes in rats.

    PubMed Central

    Kalliomäki, P L; Lakomaa, E; Kalliomäki, K; Kiilunen, M; Kivelä, R; Vaaranen, V

    1983-01-01

    Forty two male Wistar rats were exposed to manual metal arc (MMA) stainless steel (SS) welding fumes generated by an automatic welding device for "nose-only" exposure. The exposure simulated an actual MMA/SS welding environment as closely as possible. For the retention study, the duration of exposure was one hour per workday for one, two, three, of four weeks and for the clearance study four weeks. The retention and clearance of the chromium, nickel, and iron found in MMA/SS welding fumes in the rats' lungs were studied as was the distribution of the metals to other organs. Instrumental neutron activation analysis (INAA) was used for the multi-element chemical activation analyses. The concentrations of chromium and nickel in the blood and the urine were determined by atomic absorption method (AAS). The retention of exogenous iron was determined by a magnetic measuring method. The results indicated that the lungs were the target organs of soluble hexavalent chromates. The half times of lung clearance for Cr, Ni, and Fe were 40 +/- 4 d, 20 +/- d, and 50 +/- 10 d. When the lung clearance curves are compared, the half times of Cr and Fe lung clearance are similar but nickel disappears faster. The distribution and clearance patterns of chromium to other organs differ from those obtained after single intravenous or intratracheal injections of alkaline chromates. PMID:6830723

  14. Creep deformation and fracture behavior of types 316 and 316L(N) stainless steels and their weld metals

    SciTech Connect

    Sasikala, G.; Mathew, M.D.; Bhanu Sankara Rao, K.; Mannan, S.L.

    2000-04-01

    The creep properties of a nuclear-grade type 316(L) stainless steel (SS) alloyed with nitrogen (316L(N)SS) and its weld metal were studied at 873 and 923 K in the range of applied stresses from 100 to 335 MPa. The results were compared with those obtained on a nuclear-grade type 316 SS, which is lean in nitrogen. The creep rupture lives of the weld metals were found to be lower than those of the respective base metals by a factor of 5 to 10. Both the base and weld metals of 314L(N)SS exhibited better resistance to creep deformation compared to their 316SS counterparts at identical test conditions. A power-law relationship between the minimum creep rate and applied stress was found to be obeyed for both the base and weld metals. Both the weld metals generally exhibited lower rupture elongation than the respective base metals; however, at 873 K, the 316 SS base and weld metals had similar rupture elongation at identical applied stresses. Comparison of the rupture lives of the two steels to the ASME curves for the expected minimum stress to rupture for 316 Ss base and weld metals showed that, for 316L(N) SS, the specifications for maximum allowable stresses based on data for 316 SS could prove overconservative. The influence of nitrogen on the creep deformation and fracture behavior, especially in terms of its modifying the precipitation kinetics, is discussed in light of the microstructural observations. In welds containing {delta} ferrite, the kinetics of its transformation and the nature of the transformation products control the deformation and fracture behavior. The influence of nitrogen on the {delta} ferrite transformation behavior and coarsening kinetics is also discussed, on the basis of extensive characterization by metallographic techniques.

  15. Creep deformation and fracture behavior of types 316 and 316L(N) stainless steels and their weld metals

    NASA Astrophysics Data System (ADS)

    Sasikala, G.; Mannan, S. L.; Mathew, M. D.; Rao, K. Bhanu

    2000-04-01

    The creep properties of a nuclear-grade type 316(L) stainless steel (SS) alloyed with nitrogen (316L(N) SS) and its weld metal were studied at 873 and 923 K in the range of applied stresses from 100 to 335 MPa. The results were compared with those obtained on a nuclear-grade type 316 SS, which is lean in nitrogen. The creep rupture lives of the weld metals were found to be lower than those of the respective base metals by a factor of 5 to 10. Both the base and weld metals of 316L(N) SS exhibited better resistance to creep deformation compared to their 316 SS counterparts at identical test conditions. A power-law relationship between the minimum creep rate and applied stress was found to be obeyed for both the base and weld metals. Both the weld metals generally exhibited lower rupture elongation than the respective base metals; however, at 873 K, the 316 SS base and weld metals had similar rupture elongation at identical applied stresses. Comparison of the rupture lives of the two steels to the ASME curves for the expected minimum stress to rupture for 316 SS base and weld metals showed that, for 316L(N) SS, the specifications for maximum allowable stresses based on data for 316 SS could prove overconservative. The influence of nitrogen on the creep deformation and fracture behavior, especially in terms of its modifying the precipitation kinetics, is discussed in light of the microstructural observations. In welds containing δ ferrite, the kinetics of its transformation and the nature of the transformation products control the deformation and fracture behavior. The influence of nitrogen on the δ ferrite transformation behavior and coarsening kinetics is also discussed, on the basis of extensive characterization by metallographic techniques.

  16. Heat-affected zone liquation crack on resistance spot welded TWIP steels

    SciTech Connect

    Saha, Dulal Chandra; Chang, InSung; Park, Yeong-Do

    2014-07-01

    In this study, the heat affected zone (HAZ) liquation crack and segregation behavior of the resistance spot welded twinning induced plasticity (TWIP) steel have been reported. Cracks appeared in the post-welded joints that originated at the partially melted zone (PMZ) and propagated from the PMZ through the heat affected zone (HAZ) to the base metal (BM). The crack length and crack opening widths were observed increasing with heat input; and the welding current was identified to be the most influencing parameter for crack formation. Cracks appeared at the PMZ when nugget diameter reached at 4.50 mm or above; and the liquation cracks were found to occur along two sides of the notch tip in the sheet direction rather than in the electrode direction. Cracks were backfilled with the liquid films which has lamellar structure and supposed to be the eutectic constituent. Co-segregation of alloy elements such as, C and Mn were detected on the liquid films by electron-probe microanalysis (EPMA) line scanning and element map which suggests that the liquid film was enrich of Mn and C. The eutectic constituent was identified by analyzing the calculated phase diagram along with thermal temperature history of finite element simulation. Preliminary experimental results showed that cracks have less/no significant effect on the static cross-tensile strength (CTS) and the tensile-shear strength (TSS). In addition, possible ways to avoid cracking were discussed. - Highlights: • The HAZ liquation crack during resistance spot welding of TWIP steel was examined. • Cracks were completely backfilled and healed with divorced eutectic secondary phase. • Co-segregation of C and Mn was detected in the cracked zone. • Heat input was the most influencing factor to initiate liquation crack. • Cracks have less/no significant effect on static tensile properties.

  17. Micromechanism of Decrease of Impact Toughness in Coarse-Grain Heat-Affected Zone of HSLA Steel with Increasing Welding Heat Input

    NASA Astrophysics Data System (ADS)

    Cao, R.; Li, J.; Liu, D. S.; Ma, J. Y.; Chen, J. H.

    2015-07-01

    This paper analyzes the micromechanism of decrease of impact toughness with increasing the welding heat input in coarse-grain heat-affected zone (CGHAZ) of a low-alloy high-strength ship-building steel plate. By comparing the microstructures, measuring the extending length of the fibrous crack, identifying the critical event of cleavage fracture, measuring the critical length, and calculating the local cleavage fracture stress σ f, and then using the basic principles of the micromechanism of cleavage fracture, this work reveals the essential causes of deteriorated toughness in the CGHAZ of high-strength steel welded joints.

  18. Effect of cooling after welding on microstructure and mechanical properties of 12 pct Cr steel weld metals

    SciTech Connect

    Cai, G.J.; Andren, H.O.; Svensson, L.E.

    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 M{sub 23}C{sub 6} aggregates around retained {delta}-ferrite. Two morphologies of M{sub 2}N and MN precipitates were found in a low-dislocation {alpha}-ferrite. It was concluded that these phases were also transformed from austenite. In weld metals heat treated with intercooling, M{sub 23}C{sub 6} 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 {alpha}-ferrite grains, nonmetallic inclusions, and M{sub 23}C{sub 6} 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.

  19. The Effect of Solution Annealing on Alloy 22 Weld Properties

    SciTech Connect

    El-Dasher, B S; Torres, S G

    2005-11-08

    The effect of solution annealing temperature on the microstructure and observed corrosion attack mode in Alloy 22 welds was assessed. Specimens were examined in the as-welded state as well as solution annealed for 20 minutes at temperatures ranging from 1075 C to 1300 C. The microstructures of the specimens were first mapped using electron backscatter diffraction to determine the grain structure evolution due to solution annealing. Full recrystallization of the fusion zone was only observed in the 1200 C and 1300 C specimens, although the 1300 C specimen showed abnormal grain growth. As-welded, 1121 C and 1200 C specimens were also subjected to electrochemical testing in a 6 molal NaCl + 0.9 molal KNO{sub 3} environment to initiate crevice corrosion. Examination of the specimen surfaces after corrosion testing showed that in the as-welded specimen, corrosion was present in both the weld dendrites as well as around the secondary phases. However, the specimen solution annealed at 1121 C showed corrosion only at secondary phases and the specimen annealed at 1200 C showed pitting corrosion only in a handful of grains.

  20. Structural strength of welded shells made of corrosion-resistant maraging steels

    SciTech Connect

    Raimond, E.D.; Lapin, P.G.; Pautkin, U.S.; Shiganov, N.V.; Tashchikov, V.S.

    1986-03-01

    The authors devise special measures to increase the resistance of welded shells made of corrosion-resistant maraging steels. High structural strenght is ensured for shells loaded by internal pressure when ait (impact toughness) greater than or equal to10 J/cm/sup 2/. For welds of corrosion-resistant maraging steels of the O3Kh11N10M2T type, this condition is satisfied when the weld strength does not exceed 1400-1450 MPa. A structural strength of 15001750 MPa in welds of corrosion-resistant maraging steels can be obtained by means of mechanicothermal treatment.

  1. Double-Sided Single-Pass Submerged Arc Welding for 2205 Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Luo, Jian; Yuan, Yi; Wang, Xiaoming; Yao, Zongxiang

    2013-09-01

    The duplex stainless steel (DSS), which combines the characteristics of ferritic steel and austenitic steel, is used widely. The submerged arc welding (SAW) method is usually applied to join thick plates of DSS. However, an effective welding procedure is needed in order to obtain ideal DSS welds with an appropriate proportion of ferrite (δ) and austenite (γ) in the weld zone, particularly in the melted zone and heat-affected zone. This study evaluated the effectiveness of a high efficiency double-sided single-pass (DSSP) SAW joining method for thick DSS plates. The effectiveness of the converse welding procedure, characterizations of weld zone, and mechanical properties of welded joint are analyzed. The results show an increasing appearance and continuous distribution feature of the σ phase in the fusion zone of the leading welded seam. The converse welding procedure promotes the σ phase to precipitate in the fusion zone of leading welded side. The microhardness appears to significantly increase in the center of leading welded side. Ductile fracture mode is observed in the weld zone. A mixture fracture feature appears with a shear lip and tears in the fusion zone near the fusion line. The ductility, plasticity, and microhardness of the joints have a significant relationship with σ phase and heat treatment effect influenced by the converse welding step. An available heat input controlling technology of the DSSP formation method is discussed for SAW of thick DSS plates.

  2. 76 FR 64106 - Certain Welded Stainless Steel Pipe From Korea and Taiwan; Scheduling of Expedited Five-Year...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-17

    ... COMMISSION Certain Welded Stainless Steel Pipe From Korea and Taiwan; Scheduling of Expedited Five-Year Reviews Concerning the Antidumping Duty Orders on Certain Welded Stainless Steel Pipe From Korea and... duty orders on certain welded stainless steel pipe (specifically ASTM A-312 pipe) from Korea and...

  3. 75 FR 27987 - Certain Welded Stainless Steel Pipes From the Republic of Korea: Final Results of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

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    ... Antidumping Duty Order: Certain Welded Stainless Steel Pipe From the Republic of Korea, 60 FR 10064, 10065... International Trade Administration Certain Welded Stainless Steel Pipes From the Republic of Korea: Final... welded stainless steel pipes (WSSP) from the Republic of Korea (Korea). This review covers one...

  4. 77 FR 24459 - Stainless Steel Butt-Weld Pipe Fittings From Italy: Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

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    ... International Trade Administration Stainless Steel Butt-Weld Pipe Fittings From Italy: Final Results of... stainless steel butt-weld pipe fittings (SSBW pipe fittings) from Italy.\\1\\ This review covers two... results remain unchanged from the preliminary results of review. \\1\\ See Stainless Steel Butt-Weld...

  5. 76 FR 78313 - Circular Welded Carbon-Quality Steel Pipe From India, Oman, the United Arab Emirates, and Vietnam

    Federal Register 2010, 2011, 2012, 2013, 2014

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    ... COMMISSION Circular Welded Carbon-Quality Steel Pipe From India, Oman, the United Arab Emirates, and Vietnam... United Arab Emirates, and Vietnam of circular welded carbon- quality steel pipe, provided for in... material injury by reason of LTFV and subsidized imports of circular welded carbon-quality steel pipe...

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    Federal Register 2010, 2011, 2012, 2013, 2014

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    ... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Notice of Partial... circular welded carbon steel pipes and tubes from Taiwan. The review covers two firms: Yieh Phui Enterprise... the antidumping duty order on circular welded carbon steel pipes and tubes from Taiwan covering...

  7. 75 FR 63439 - Certain Welded Carbon Steel Standard Pipes and Tubes From India: Extension of the Final Results...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-15

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    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-11

    ... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Notice of Partial... welded carbon steel pipes and tubes from Taiwan. The review covers four respondents. Based on a... welded carbon steel pipes and tubes from Taiwan covering the period May 1, 2011, through April 30,...

  9. 75 FR 28557 - Circular Welded Carbon Steel Pipes and Tubes From Thailand: Extension of Time Limit for Final...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-21

    ... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes From Thailand: Extension of Time... antidumping duty order on circular welded carbon steel pipes and tubes from Thailand. See Circular Welded Carbon Steel Pipes and Tubes from Thailand: Preliminary Results and Rescission, in Part, of...

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    Federal Register 2010, 2011, 2012, 2013, 2014

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  11. 78 FR 45271 - Welded Stainless Steel Pressure Pipe From Malaysia, Thailand, and Vietnam

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-26

    ... Commission, Washington, DC, and by publishing the notice in the Federal Register of May 24, 2013 (78 FR 31574... COMMISSION Welded Stainless Steel Pressure Pipe From Malaysia, Thailand, and Vietnam Determination On the... injured by reason of imports from Malaysia, Thailand, and Vietnam of welded stainless steel pressure...

  12. 75 FR 53714 - Stainless Steel Butt-Weld Pipe Fittings From Japan, Korea, and Taiwan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-01

    ... imports of stainless steel butt-weld pipe fittings from Japan (53 FR 9787). On February 23, 1993, Commerce... on imports of stainless steel butt-weld pipe fittings from Japan, Korea, and Taiwan (65 FR 11766... Japan, Korea, and Taiwan (70 FR 61119). The Commission is now conducting third reviews to...

  13. 75 FR 76025 - Stainless Steel Butt-Weld Pipe Fittings From Japan, Korea, and Taiwan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-07

    ... party responded to the sunset review notice of initiation by the applicable deadline * * *'' (75 FR... COMMISSION Stainless Steel Butt-Weld Pipe Fittings From Japan, Korea, and Taiwan AGENCY: United States... stainless steel butt-weld pipe fittings from Japan, Korea, and Taiwan would be likely to lead...

  14. 77 FR 19623 - Certain Welded Carbon Steel Standard Pipe from Turkey: Preliminary Results of Countervailing Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-02

    ... Pipe and Tube Products from Turkey, 51 FR 7984 (March 7, 1986). \\2\\ See Antidumping or Countervailing... certain welded carbon steel pipe and tube with an outside diameter of 0.375 inch or more, but not over 16...: Certain Welded Carbon Steel Standard Pipe from Turkey, 72 FR 62837, 62838 (November 7, 2007) (Turkey...

  15. 78 FR 63517 - Control of Ferrite Content in Stainless Steel Weld Metal

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-24

    ... Information The NRC published DG-1279 in the Federal Register on October 3, 2012 (77 FR 60479), for a 60-day... COMMISSION Control of Ferrite Content in Stainless Steel Weld Metal AGENCY: Nuclear Regulatory Commission... revision to Regulatory Guide (RG) 1.31, ``Control of Ferrite Content in Stainless Steel Weld Metal.''...

  16. 78 FR 34335 - Certain Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-07

    ... Steel Pipes and Tubes From Taiwan: Antidumping Duty Order, 49 FR 19369 (May 7, 1984). These cash deposit... International Trade Administration Certain Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Preliminary... conducting an administrative review of the antidumping duty order on certain circular welded carbon...

  17. Influences of post-weld heat treatment on tensile properties of friction stir-welded AA6061 aluminum alloy joints

    SciTech Connect

    Elangovan, K.; Balasubramanian, V.

    2008-09-15

    This paper reports on studies of the influences of various post-weld heat treatment procedures on tensile properties of friction stir-welded AA6061 aluminum alloy joints. Rolled plates of 6-mm thick AA6061 aluminum alloy were used to fabricate the joints. Solution treatment, an artificial aging treatment and a combination of both were given to the welded joints. Tensile properties such as yield strength, tensile strength, elongation and joint efficiency were evaluated. Microstructures of the welded joints were analyzed using optical microscopy and transmission electron microscopy. A simple artificial aging treatment was found to be more beneficial than other treatment methods to enhance the tensile properties of the friction stir-welded AA6061 aluminum alloy joints.

  18. Influences of post weld heat treatment on tensile properties of friction stir welded AA2519-T87 aluminium alloy joints

    NASA Astrophysics Data System (ADS)

    Sabari, S. Sree; Balasubramanian, V.; Malarvizhi, S.; Reddy, G. Madusudhan

    2015-12-01

    AA 2519-T87 is an aluminium alloy that principally contains Cu as an alloying element and is a new grade of Al-Cu alloy system. This material is a potential candidate for light combat military vehicles. Fusion welding of this alloy leads to hot cracking, porosity and alloy segregation in the weld metal region. Friction stir welding (FSW) is a solid state joining process which can overcome the above mentioned problems. However, the FSW of age hardenable aluminium alloys results in poor tensile properties in the as-welded condition (AW). Hence, post weld heat treatment (PWHT) is used to enhance deteriorated tensile properties of FSW joints. In this work, the effect of PWHT, namely artificial ageing (AA) and solution treatment (ST) followed by ageing (STA) on the microstructure, tensile properties and microhardness were systematically investigated. The microstructural features of the weld joints were characterised using an optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The tensile strength and microhardness of the joints were correlated with the grain size, precipitate size, shape and its distribution. From the investigation, it was found that STA treatment is beneficial in enhancing the tensile strength of the FSW joints of AA2519-T87 alloy and this is mainly due to the presence of fine and densely distributed precipitates in the stir zone.

  19. Welding of titanium and nickel alloy by combination of explosive welding and spark plasma sintering technologies

    NASA Astrophysics Data System (ADS)

    Malyutina, Yu. N.; Bataev, A. A.; Mali, V. I.; Anisimov, A. G.; Shevtsova, L. I.

    2015-10-01

    A possibility of titanium and nickel-based alloys composite materials formation using combination of explosive welding and spark plasma sintering technologies was demonstrated in the current research. An employment of interlayer consisting of copper and tantalum thin plates makes possible to eliminate a contact between metallurgical incompatible titanium and nickel that are susceptible to intermetallic compounds formation during their interaction. By the following spark plasma sintering process the bonding has been received between titanium and titanium alloy VT20 through the thin powder layer of pure titanium that is distinguished by low defectiveness and fine dispersive structure.

  20. Welding of titanium and nickel alloy by combination of explosive welding and spark plasma sintering technologies

    SciTech Connect

    Malyutina, Yu. N. Bataev, A. A. Shevtsova, L. I.; Mali, V. I. Anisimov, A. G.

    2015-10-27

    A possibility of titanium and nickel-based alloys composite materials formation using combination of explosive welding and spark plasma sintering technologies was demonstrated in the current research. An employment of interlayer consisting of copper and tantalum thin plates makes possible to eliminate a contact between metallurgical incompatible titanium and nickel that are susceptible to intermetallic compounds formation during their interaction. By the following spark plasma sintering process the bonding has been received between titanium and titanium alloy VT20 through the thin powder layer of pure titanium that is distinguished by low defectiveness and fine dispersive structure.

  1. The Influence of Shielding Gas and Heat Input on the Mechanical Properties of Laser Welds in Ferritic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Keskitalo, M.; Sundqvist, J.; Mäntyjärvi, K.; Powell, J.; Kaplan, A. F. H.

    Laser welding of ferritic steel in normal atmosphere gives rise to weld embrittlement and poor formability. This paper demonstrates that the addition of an argon gas shield to the welding process results in tough, formable welds. Post weld heat treatment and microscopic analysis has suggested that the poor ductility of welds produced without a gas shield is, to some extent, the result of the presence of oxides in the weld metal.

  2. B218 Weld Filler Wire Characterization for Al-Li Alloy 2195

    NASA Technical Reports Server (NTRS)

    Bjorkman, Gerry; Russell, Carolyn

    2000-01-01

    NASA Marshall Space Flight Center, Lockheed Martin Space Systems- Michoud Operations, and McCook Metals have developed an aluminum-copper weld filler wire for fusion welding aluminum lithium alloy 2195. The aluminum-copper based weld filler wire has been identified as B218, a McCook Metals designation. B218 is the result of six years of weld filler wire development funded by NASA, Lockheed Martin, and McCook Metals. The filler wire chemistry was developed to produce enhanced 2195 weld and repair weld mechanical properties over the 4043 aluminum-silicon weld filler wire, which is currently used to weld 2195 on the Super Lightweight External Tank for the NASA Space Shuttle Program. An initial characterization was performed consisting of a repair weld evaluation using B218 and 4043 weld filler wires. The testing involved room temperature and cryogenic repair weld tensile testing along with fracture toughness testing. From the testing, B218 weld filler wire produce enhanced repair weld tensile strength, ductility, and fracture properties over 4043. B218 weld filler wire has proved to be a superior weld filler wire for welding aluminum lithium alloy 2195 over 4043.

  3. Interfacial microstructure and properties of copper clad steel produced using friction stir welding versus gas metal arc welding

    SciTech Connect

    Shen, Z.; Chen, Y.; Haghshenas, M.; Nguyen, T.; Galloway, J.; Gerlich, A.P.

    2015-06-15

    A preliminary study compares the feasibility and microstructures of pure copper claddings produced on a pressure vessel A516 Gr. 70 steel plate, using friction stir welding versus gas metal arc welding. A combination of optical and scanning electron microscopy is used to characterize the grain structures in both the copper cladding and heat affected zone in the steel near the fusion line. The friction stir welding technique produces copper cladding with a grain size of around 25 μm, and no evidence of liquid copper penetration into the steel. The gas metal arc welding of copper cladding exhibits grain sizes over 1 mm, and with surface microcracks as well as penetration of liquid copper up to 50 μm into the steel substrate. Transmission electron microscopy reveals that metallurgical bonding is produced in both processes. Increased diffusion of Mn and Si into the copper cladding occurs when using gas metal arc welding, although some nano-pores were detected in the FSW joint interface. - Highlights: • Cladding of steel with pure copper is possible using either FSW or GMAW. • The FSW yielded a finer grain structure in the copper, with no evidence of cracking. • The FSW joint contains some evidence of nano-pores at the interface of the steel/copper. • Copper cladding by GMAW contained surface cracks attributed to high thermal stresses. • The steel adjacent to the fusion line maintained a hardness value below 248 HV.

  4. Influence of Weld Cooling Rate on Microstructure and Mechanical Properties of Alloy 718 Weldments

    NASA Astrophysics Data System (ADS)

    Sivaprasad, K.; Ganesh Sundara Raman, S.

    2008-09-01

    Even though alloy 718 is the best for welding among all nickel-base superalloys, the formation of the Laves phase in welds is a major concern. The presence of this phase drastically degrades mechanical properties of the welds. To study the influence of weld cooling rate on microstructure and mechanical properties of alloy 718 weldments, two distinct welding processes were adopted—gas tungsten arc (GTA) and electron beam (EB) welding. The EB welding resulted in finer and relatively discrete Laves phase in lower quantity due to higher cooling rates prevailing in this process. On the other hand, due to lower cooling rates, GTA weld fusion zones exhibited coarse Laves with higher niobium. Depletion of the primary strengthening element niobium in the surrounding regions of Laves promoted crack propagation. Because EB welds had finer and lower amount of Laves, EB weldments exhibited superior mechanical properties compared with GTA weldments.

  5. Nine percent nickel steel heavy forging weld repair study. [National Transonic Wind Tunnel fan components

    NASA Technical Reports Server (NTRS)

    Young, C. P., Jr.; Gerringer, A. H.; Brooks, T. G.; Berry, R. F., Jr.

    1978-01-01

    The feasibility of making weld repairs on heavy section 9% nickel steel forgings such as those being manufactured for the National Transonic Facility fan disk and fan drive shaft components was evaluated. Results indicate that 9% nickel steel in heavy forgings has very good weldability characteristics for the particular weld rod and weld procedures used. A comparison of data for known similar work is included.

  6. Mechanical Properties of Friction Stir Welded Aluminum Alloys 5083 and 5383

    NASA Astrophysics Data System (ADS)

    Paik, Jeoom Kee

    2009-09-01

    The use of high-strength aluminum alloys is increasing in shipbuilding industry, particularly for the design and construction of war ships, littoral surface craft and combat ships, and fast passenger ships. While various welding methods are used today to fabricate aluminum ship structures, namely gas metallic arc welding (GMAW), laser welding and friction stir welding (FSW), FSW technology has been recognized to have many advantages for the construction of aluminum structures, as it is a low-cost welding process. In the present study, mechanical properties of friction stir welded aluminum alloys are examined experimentally. Tensile testing is undertaken on dog-bone type test specimen for aluminum alloys 5083 and 5383. The test specimen includes friction stir welded material between identical alloys and also dissimilar alloys, as well as unwelded (base) alloys. Mechanical properties of fusion welded aluminum alloys are also tested and compared with those of friction stir welded alloys. The insights developed from the present study are documented together with details of the test database. Part of the present study was obtained from the Ship Structure Committee project SR-1454 (Paik, 2009), jointly funded by its member agencies

  7. Development of a technology for laser welding of the 1424 aluminum alloy with a high strength of the welded joint

    NASA Astrophysics Data System (ADS)

    Annin, B. D.; Fomin, V. M.; Karpov, E. V.; Malikov, A. G.; Orishich, A. M.; Cherepanov, A. N.

    2015-11-01

    Results of an experimental study of properties of joints obtained by using different regimes of laser welding of the 1424 alloy (Al-Mg-Li) are reported. The strength and structure of the welded joints are determined. The influence of various types of welded joint straining on its strength is studied. It is demonstrated that the joint strength increases in the case of plastic straining.

  8. Influence of PWHT on Toughness of High Chromium and Nickel Containing Martensitic Stainless Steel Weld Metals

    NASA Astrophysics Data System (ADS)

    Divya, M.; Das, Chitta Ranjan; Mahadevan, S.; Albert, S. K.; Pandian, R.; Kar, Sujoy Kumar; Bhaduri, A. K.; Jayakumar, T.

    2015-06-01

    Commonly used 12.5Cr-5Ni consumable specified for welding of martensitic stainless steels is compared with newly designed 14.5Cr-5Ni consumable in terms of their suitability for repair welding of 410 and 414 stainless steels by gas tungsten arc welding process. Changes in microstructure and austenite evolution were investigated using optical, scanning electron microscopy, X-ray diffraction techniques and Thermo-Calc studies. Microstructure of as-welded 12.5Cr-5Ni weld metal revealed only lath martensite, whereas as-welded 14.5Cr-5Ni weld metal revealed delta-ferrite, retained austenite, and lath martensite. Toughness value of as-welded 12.5Cr-5Ni weld metal is found to be significantly higher (216 J) than that of the 14.5Cr-5Ni weld metal (15 J). The welds were subjected to different PWHTs: one at 923 K (650 °C) for 1, 2, 4 hours (single-stage PWHT) and another one at 923 K (650 °C)/4 h followed by 873 K (600 °C)/2 h or 873 K (600 °C)/4 h (two-stage heat treatment). Hardness and impact toughness of the weld metals were measured for these weld metals and correlated with the microstructure. The study demonstrates the importance of avoiding formation of delta-ferrite in the weld metal.

  9. Effect of friction stir welding and post-weld heat treatment on a nanostructured ferritic alloy

    NASA Astrophysics Data System (ADS)

    Mazumder, B.; Yu, X.; Edmondson, P. D.; Parish, C. M.; Miller, M. K.; Meyer, H. M.; Feng, Z.

    2016-02-01

    Nanostructured ferritic alloys (NFAs) are new generation materials for use in high temperature energy systems, such as nuclear fission or fusion reactors. However, joining these materials is a concern, as their unique microstructure is destroyed by traditional liquid-state welding methods. The microstructural evolution of a friction stir welded 14YWT NFA was investigated by atom probe tomography, before and after a post-weld heat treatment (PWHT) at 1123K. The particle size, number density, elemental composition, and morphology of the titanium-yttrium-oxygen-enriched nanoclusters (NCs) in the stir and thermally-affected zones were studied and compared with the base metal. No statistical difference in the size of the NCs was observed in any of these conditions. After the PWHT, increases in the number density and the oxygen enrichment in the NCs were observed. Therefore, these new results provide additional supporting evidence that friction stir welding appears to be a viable joining technique for NFAs, as the microstructural parameters of the NCs are not strongly affected, in contrast to traditional welding techniques.

  10. Effect of friction stir welding and post-weld heat treatment on a nanostructured ferritic alloy

    DOE PAGESBeta

    Mazumder, Baishakhi; Yu, Xinghua; Edmondson, Philip D.; Parish, Chad M.; Miller, Michael K; Meyer, H. M.; Feng, Zhili

    2015-12-08

    Nanostructured ferritic alloys (NFAs) are new generation materials for use in high temperature energy systems, such as nuclear fission or fusion reactors. However, joining these materials is a concern, as their unique microstructure is destroyed by traditional liquid-state welding methods. The microstructural evolution of a friction stir welded 14YWT NFA was investigated by atom probe tomography, before and after a post-weld heat treatment (PWHT) at 1123K. The particle size, number density, elemental composition, and morphology of the titanium-yttrium-oxygenenriched nanoclusters (NCs) in the stir and thermally-affected zones were studied and compared with the base metal. No statistical difference in the sizemore » of the NCs was observed in any of these conditions. After the PWHT, increases in the number density and the oxygen enrichment in the NCs were observed. Therefore, these new results provide additional supporting evidence that friction stir welding appears to be a viable joining technique for NFAs, as the microstructural parameters of the NCs are not strongly affected, in contrast to traditional welding techniques.« less

  11. Effect of friction stir welding and post-weld heat treatment on a nanostructured ferritic alloy

    SciTech Connect

    Mazumder, Baishakhi; Yu, Xinghua; Edmondson, Philip D.; Parish, Chad M.; Miller, Michael K; Meyer, H. M.; Feng, Zhili

    2015-12-08

    Nanostructured ferritic alloys (NFAs) are new generation materials for use in high temperature energy systems, such as nuclear fission or fusion reactors. However, joining these materials is a concern, as their unique microstructure is destroyed by traditional liquid-state welding methods. The microstructural evolution of a friction stir welded 14YWT NFA was investigated by atom probe tomography, before and after a post-weld heat treatment (PWHT) at 1123K. The particle size, number density, elemental composition, and morphology of the titanium-yttrium-oxygenenriched nanoclusters (NCs) in the stir and thermally-affected zones were studied and compared with the base metal. No statistical difference in the size of the NCs was observed in any of these conditions. After the PWHT, increases in the number density and the oxygen enrichment in the NCs were observed. Therefore, these new results provide additional supporting evidence that friction stir welding appears to be a viable joining technique for NFAs, as the microstructural parameters of the NCs are not strongly affected, in contrast to traditional welding techniques.

  12. Eddy-Current Testing of Welded Stainless Steel Storage Containers to Verify Integrity and Identity

    SciTech Connect

    Tolk, Keith M.; Stoker, Gerald C.

    1999-07-20

    An eddy-current scanning system is being developed to allow the International Atomic Energy Agency (IAEA) to verify the integrity of nuclear material storage containers. Such a system is necessary to detect attempts to remove material from the containers in facilities where continuous surveillance of the containers is not practical. Initial tests have shown that the eddy-current system is also capable of verifying the identity of each container using the electromagnetic signature of its welds. The DOE-3013 containers proposed for use in some US facilities are made of an austenitic stainless steel alloy, which is nonmagnetic in its normal condition. When the material is cold worked by forming or by local stresses experienced in welding, it loses its austenitic grain structure and its magnetic permeability increases. This change in magnetic permeability can be measured using an eddy-current probe specifically designed for this purpose. Initial tests have shown that variations of magnetic permeability and material conductivity in and around welds can be detected, and form a pattern unique to the container. The changes in conductivity that are present around a mechanically inserted plug can also be detected. Further development of the system is currently underway to adapt the system to verifying the integrity and identity of sealable, tamper-indicating enclosures designed to prevent unauthorized access to measurement equipment used to verify international agreements.

  13. Effect of Alloy 625 Buffer Layer on Hardfacing of Modified 9Cr-1Mo Steel Using Nickel Base Hardfacing Alloy

    NASA Astrophysics Data System (ADS)

    Chakraborty, Gopa; Das, C. R.; Albert, S. K.; Bhaduri, A. K.; Murugesan, S.; Dasgupta, Arup

    2016-04-01

    Dashpot piston, made up of modified 9Cr-1Mo steel, is a part of diverse safety rod used for safe shutdown of a nuclear reactor. This component was hardfaced using nickel base AWS ER NiCr-B alloy and extensive cracking was experienced during direct deposition of this alloy on dashpot piston. Cracking reduced considerably and the component was successfully hardfaced by application of Inconel 625 as buffer layer prior to hardface deposition. Hence, a separate study was undertaken to investigate the role of buffer layer in reducing the cracking and on the microstructure of the hardfaced deposit. Results indicate that in the direct deposition of hardfacing alloy on modified 9Cr-1Mo steel, both heat-affected zone (HAZ) formed and the deposit layer are hard making the thickness of the hard layer formed equal to combined thickness of both HAZ and deposit. This hard layer is unable to absorb thermal stresses resulting in the cracking of the deposit. By providing a buffer layer of Alloy 625 followed by a post-weld heat treatment, HAZ formed in the modified 9Cr-1Mo steel is effectively tempered, and HAZ formed during the subsequent deposition of the hardfacing alloy over the Alloy 625 buffer layer is almost completely confined to Alloy 625, which does not harden. This reduces the cracking susceptibility of the deposit. Further, unlike in the case of direct deposition on modified 9Cr-1Mo steel, dilution of the deposit by Ni-base buffer layer does not alter the hardness of the deposit and desired hardness on the deposit surface could be achieved even with lower thickness of the deposit. This gives an option for reducing the recommended thickness of the deposit, which can also reduce the risk of cracking.

  14. Amorphous Alloy Surpasses Steel and Titanium

    NASA Technical Reports Server (NTRS)

    2004-01-01

    In the same way that the inventions of steel in the 1800s and plastic in the 1900s sparked revolutions for industry, a new class of amorphous alloys is poised to redefine materials science as we know it in the 21st century. Welcome to the 3rd Revolution, otherwise known as the era of Liquidmetal(R) alloys, where metals behave similar to plastics but possess more than twice the strength of high performance titanium. Liquidmetal alloys were conceived in 1992, as a result of a project funded by the California Institute of Technology (CalTech), NASA, and the U.S. Department of Energy, to study the fundamentals of metallic alloys in an undercooled liquid state, for the development of new aerospace materials. Furthermore, NASA's Marshall Space Flight Center contributed to the development of the alloys by subjecting the materials to testing in its Electrostatic Levitator, a special instrument that is capable of suspending an object in midair so that researchers can heat and cool it in a containerless environment free from contaminants that could otherwise spoil the experiment.

  15. Effect of notch location on fatigue crack growth behavior of strength-mismatched high-strength low-alloy steel weldments

    NASA Astrophysics Data System (ADS)

    Ravi, S.; Balasubramanian, V.; Nasser, S. Nemat

    2004-12-01

    Welding of high-strength low-alloy (HSLA) steels involves the use of low-strength, equal-strength, and high-strength filler materials (electrodes) compared with the parent material, depending on the application of the welded structures and the availability of filler material. In the present investigation, the fatigue crack growth behavior of weld metal (WM) and the heat-affected zone (HAZ) of undermatched (UM), equally matched (EM), and overmatched (OM) joints has been studied. The base material used in this investigation is HSLA-80 steel of weldable grade. Shielded metal arc welding (SMAW) has been used to fabricate the butt joints. A center-cracked tension (CCT) specimen has been used to evaluate the fatigue crack growth behavior of welded joints, utilizing a servo-hydraulic-controlled fatigue-testing machine at constant amplitude loading (R=0). The effect of notch location on the fatigue crack growth behavior of strength mismatched HSLA steel weldments also has been analyzed.

  16. Wear testing of friction stir spot welding tools for joining of DP 980 Steel

    SciTech Connect

    Ridges, Chris; Miles, Michael; Hovanski, Yuri; Peterson, Jeremy; Steel, Russell

    2011-06-06

    Friction stir spot welding has been shown to be a viable method of joining ultra high strength steel (UHSS), both in terms of joint strength and process cycle time. However, the cost of tooling must be reasonable in order for this method to be adopted as an industrial process. Several tooling materials have been evaluated in prior studies, including silicon nitride and polycrystalline cubic boron nitride (PCBN). Recently a new tool alloy has been developed, where a blend of PCBN and tungsten rhenium (W-Re) was used in order to improve the toughness of the tool. Wear testing results are presented for two of these alloys: one with a composition of 60% PCBN and 40% W-Re (designated as Q60), and one with 70% PCBN and 30% W-Re (designated at Q70). The sheet material used for all wear testing was DP 980. Tool profiles were measured periodically during the testing process in order to show the progression of wear as a function of the number of spots produced. Lap shear testing was done each time a tool profile was taken in order to show the relationship between tool wear and joint strength. For the welding parameters chosen for this study the Q70 tool provided the best combination of wear resistance and joint strength.

  17. Joining precipitation-hardened nickel-base alloys by friction welding

    NASA Technical Reports Server (NTRS)

    Moore, T. J.

    1972-01-01

    Solid state deformation welding process, friction welding, has been developed for joining precipitation hardened nickel-base alloys and other gamma prime-strengthened materials which heretofore have been virtually unweldable. Method requires rotation of one of the parts to be welded, but where applicable, it is an ideal process for high volume production jobs.

  18. An Investigation of the Massive Transformation from Ferrite to Austenite in Laser-Welded Mo-Bearing Stainless Steels

    NASA Astrophysics Data System (ADS)

    Perricone, M. J.; Dupont, J. N.; Anderson, T. D.; Robino, C. V.; Michael, J. R.

    2011-03-01

    A series of 31 Mo-bearing stainless steel compositions with Mo contents ranging from 0 to 10 wt pct and exhibiting primary δ-ferrite solidification were analyzed over a range of laser welding conditions to evaluate the effect of composition and cooling rate on the solid-state transformation to γ-austenite. Alloys exhibiting this microstructural development sequence are of particular interest to the welding community because of their reduced susceptibility to solidification cracking and the potential reduction of microsegregation (which can affect corrosion resistance), all while harnessing the high toughness of γ-austenite. Alloys were created using the arc button melting process, and laser welds were prepared on each alloy at constant power and travel speeds ranging from 4.2 to 42 mm/s. The cooling rates of these processes were estimated to range from 10 K (°C)/s for arc buttons to 105 K (°C)/s for the fastest laser welds. No shift in solidification mode from primary δ-ferrite to primary γ-austenite was observed in the range of compositions or welding conditions studied. Metastable microstructural features were observed in many laser weld fusion zones, as well as a massive transformation from δ-ferrite to γ-austenite. Evidence of epitaxial massive growth without nucleation was also found when intercellular γ-austenite was already present from a solidification reaction. The resulting single-phase γ-austenite in both cases exhibited a homogenous distribution of Mo, Cr, Ni, and Fe at nominal levels.

  19. Weld Growth Mechanisms and Failure Behavior of Three-Sheet Resistance Spot Welds Made of 5052 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Li, Yang; Yan, Fuyu; Luo, Zhen; Chao, Y. J.; Ao, Sansan; Cui, Xuetuan

    2015-06-01

    This paper investigates the weld nugget formation in three-sheet aluminum alloy resistance spot welding. The nugget formation process in three equal thickness sheets and three unequal thickness sheets of 5052 aluminum alloy were studied. The results showed that the nugget was initially formed at the workpiece/workpiece interfaces (i.e., both upper interface and lower interface). The two small nuggets then grew along the radial direction and axial direction (welding direction) as the welding time increased. Eventually, the two nuggets fused into one large nugget. During the welding process, the Peltier effect between the Cu-Al caused the shift of the nugget in the welding direction. In addition, the mechanical strength and fracture mode of the weld nuggets at the upper and lower interfaces were also studied using tensile shear specimen configuration. Three failure modes were identified, namely interfacial, mixed, and pullout. The critical welding time and critical nugget diameter corresponding to the transitions of these modes were investigated. Finally, an empirical failure load formula for three-sheet weld similar to two-sheet spot weld was developed.

  20. Corrosion of Welded X100 Pipeline Steel in a Near-Neutral pH Solution

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Cheng, Y. F.

    2010-08-01

    In this work, electrochemical corrosion behavior of a welded X100 pipeline steel was studied in a near-neutral pH solution by electrochemical scanning vibrating electrode technique combined with metallographic and scanning electron microscopy/energy dispersive x-ray analysis. Results demonstrated that a softening phenomenon occurs around the weld, and there is the high micro-hardness in base steel adjacent to weld. In particular, there is the highest micro-hardness in base steel containing acicular ferrite and bainite. Therefore, welding and the associated post-treatment on X100 steel alter dramatically the microstructure and mechanical property around weld, resulting in an enhanced micro-hardness in base steel. There are high and low local dissolution current densities at base steel and the welded zones, respectively. The difference between the maximum and minimum dissolution current densities decreases with time, and the distribution of dissolution current density tends to be uniform. Hydrogen-charging changes the local dissolution activity of the welded steel. Different from the hydrogen-free steel, there is the highest dissolution current density at heat-affected zone. It is reasonable to assume that the charged hydrogen would accumulate at heat-affected zone, and the synergism of hydrogen and local stress results in a high anodic dissolution rate.

  1. Microstructure of welded and thermal-aged low activation steel F82H IEA heat

    NASA Astrophysics Data System (ADS)

    Sawai, T.; Shiba, K.; Hishinuma, A.

    2000-12-01

    F82H(8Cr-2WVTa steel) IEA heat was used to prepare tungsten-inert-gas (TIG) and electron-beam (EB) weld joints, followed by heat treatment at 720°C for 1 h. Hardening in the weld metal and softening in the heat-affected zone (HAZ) were detected in TIG weld joints. In EB weld joints, hardening in the weld metal was more clearly observed but HAZ softening was hardly observed. Hardness of TIG weld metal was reduced after 550°C thermal-aging, but softening of the base metal was only observed after 650°C thermal-aging. M23C6 phase was the major precipitate in aged base metal and weld joints. The amount of precipitates in aged weld metal was lower than that of normalized and tempered base metal. W-rich Laves phase was also detected in aged weld metal, HAZ and base metal.

  2. The Mechanical Behavior of Friction-Stir Spot Welded Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Güler, Hande

    2014-09-01

    Aluminum and alloys are widely used in the automotive industry due to the light weight, good formability, and malleability. Spot welding is the most commonly used joining method of these materials, but the high current requirements and the inconsistent quality of the final welds make this process unsuitable. An alternative welding technique, the friction-stir spot welding process, can also be successfully used in joining of aluminum and alloys. In this study, 1-mm-thick AA5754 Al-alloy plates in the H-111 temper conditions were joined by friction-stir spot welding using two different weld parameters such as tool rotational speed and dwell time. Mechanical properties of the joints were obtained with extensive hardness measurements and tensile shear tests. The effect of these parameters on the failure modes of welded joints was also determined.

  3. The Mechanical Behavior of Friction-Stir Spot Welded Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Güler, Hande

    2014-10-01

    Aluminum and alloys are widely used in the automotive industry due to the light weight, good formability, and malleability. Spot welding is the most commonly used joining method of these materials, but the high current requirements and the inconsistent quality of the final welds make this process unsuitable. An alternative welding technique, the friction-stir spot welding process, can also be successfully used in joining of aluminum and alloys. In this study, 1-mm-thick AA5754 Al-alloy plates in the H-111 temper conditions were joined by friction-stir spot welding using two different weld parameters such as tool rotational speed and dwell time. Mechanical properties of the joints were obtained with extensive hardness measurements and tensile shear tests. The effect of these parameters on the failure modes of welded joints was also determined.

  4. A study on friction stir welding of 12mm thick aluminum alloy plates

    NASA Astrophysics Data System (ADS)

    Kumar, Deepati Anil; Biswas, Pankaj; Tikader, Sujoy; Mahapatra, M. M.; Mandal, N. R.

    2013-12-01

    Most of the investigations regarding friction stir welding (FSW) of aluminum alloy plates have been limited to about 5 to 6 mm thick plates. In prior work conducted the various aspects concerning the process parameters and the FSW tool geometry were studied utilizing friction stir welding of 12 mm thick commercial grade aluminum alloy. Two different simple-to-manufacture tool geometries were used. The effect of varying welding parameters and dwell time of FSW tool on mechanical properties and weld quality was examined. It was observed that in order to achieve a defect free welding on such thick aluminum alloy plates, tool having trapezoidal pin geometry was suitable. Adequate tensile strength and ductility can be achieved utilizing a combination of high tool rotational speed of about 2000 r/min and low speed of welding around 28 mm/min. At very low and high dwell time the ductility of welded joints are reduced significantly.

  5. A hot-cracking mitigation technique for welding high-strength aluminum alloy

    SciTech Connect

    Yang, Y.P.; Dong, P.; Zhang, J.; Tian, X.

    2000-01-01

    A hot-cracking mitigation technique for gas tungsten arc welding (GTAW) of high-strength aluminum alloy 2024 is presented. The proposed welding technique incorporates a trailing heat sink (an intense cooling source) with respect to the welding torch. The development of the mitigation technique was based on both detailed welding process simulation using advanced finite element techniques and systematic laboratory experiments. The finite element methods were used to investigate the detailed thermomechanical behavior of the weld metal that undergoes the brittle temperature range (BTR) during welding. As expected, a tensile deformation zone within the material BTR region was identified behind the weld pool under conventional GTA welding process conventional GTA welding process conditions for the aluminum alloy studied. To mitigate hot cracking, the tensile zone behind the weld pool must be eliminated or reduce to a satisfactory level if the weld metal hot ductility cannot be further improved. With detailed computational modeling, it was found that by the introduction of a trailing heat sink at some distance behind the welding arc, the tensile strain rate with respect to temperature in the zone encompassing the BTR region can be significantly reduced. A series of parametric studies were also conducted to derive optimal process parameters for the trailing heat sink. The experimental results confirmed the effectiveness of the trailing heat sink technique. With a proper implementation of the trailing heat sink method, hot cracking can be completely eliminated in welding aluminum alloy 2024 (AA 2024).

  6. Analysis of experiments on stainless steel flux welds

    SciTech Connect

    Wilkowski, G.; Ahmad, J.; Brust, F.; Guerrieri, D.; Kramer, G.; Kulhowvick, G.; Landow, M.; Marschall, C.; Nakagaki, M.; Papaspyropoulos, V.

    1987-04-01

    This report describes experimental and analytical efforts to evaluate fracture of stainless steel flux-welded pipe. Seven pipe fracture experiments (four with through-wall circumferential cracks and three with circumferential internal surface cracks) were conducted at 550/sup 0/F (288/sup 0/C). Material characterization efforts involved laboratory specimen tests to assess specimen size effects, effects of solution-annealing, and crack-growth behavior in the HAZ, along the fusion line, and in the weld metal. Efforts involved assessing the net-section-collapse analysis, the plastic-zone screening criterion, inherent safety margins in the IWB-3640 flux weld analysis, through-wall-cracked pipe predictive J-estimation schemes for LBB analyses, eta-factor J-R curves calculated from the pipe experiments for comparison to C(T) specimen results, and finite element analysis of C(T) specimens and one pipe experiment. This report also evaluates the technical significance of these results and their significance relative to licensing decisions.

  7. Acceptance criteria for corroded carbon steel piping containing weld defects

    SciTech Connect

    Mertz, G.E.; Lam, P.S.; Awadalla, N.G.

    1993-04-01

    Acceptance criteria for corroded low temperature, low pressure carbon steel piping containing weld defects is presented along with a typical application of these criteria. They are intended to preclude gross rupture or rapidly propagating failure due to uniform wall thinning, local wall thinning, pitting corrosion and weld defects. The minimum allowable uniform wail thickness is based on the code-of-record allowable stress and fracture criteria. Weld defects are postulated as potential sites for fracture initiation. CEGB/R6 failure assessment diagram is used as the fracture criteria to determine the minimum allowable wall thickness. Design of a large portion of the low temperature, low pressure piping is dominated by axial stresses. Existing local wall thinning acceptance criteria address high pressure piping where hoop stress dominates the design. The existing criteria is over conservative, in some cases, when used on low pressure piping. Local wall thinning criteria is developed to limit the axial stress on the locally thinned section, based on a reduced average thickness. Limits on pit density are also developed to provide acceptance criteria for pitted piping.

  8. Acceptance criteria for corroded carbon steel piping containing weld defects

    SciTech Connect

    Mertz, G.E.; Lam, P.S.; Awadalla, N.G.

    1993-01-01

    Acceptance criteria for corroded low temperature, low pressure carbon steel piping containing weld defects is presented along with a typical application of these criteria. They are intended to preclude gross rupture or rapidly propagating failure due to uniform wall thinning, local wall thinning, pitting corrosion and weld defects. The minimum allowable uniform wail thickness is based on the code-of-record allowable stress and fracture criteria. Weld defects are postulated as potential sites for fracture initiation. CEGB/R6 failure assessment diagram is used as the fracture criteria to determine the minimum allowable wall thickness. Design of a large portion of the low temperature, low pressure piping is dominated by axial stresses. Existing local wall thinning acceptance criteria address high pressure piping where hoop stress dominates the design. The existing criteria is over conservative, in some cases, when used on low pressure piping. Local wall thinning criteria is developed to limit the axial stress on the locally thinned section, based on a reduced average thickness. Limits on pit density are also developed to provide acceptance criteria for pitted piping.

  9. Examination of the 1970 National Bureau of Standards Underground Corrosion Test Welded Stainless STeel Coupons from Site D

    SciTech Connect

    L. R. Zirker; M. K. Adler Flitton; T. S. Yoder; T. L. Trowbridge

    2008-01-01

    A 1970 study initiated by the National Bureau of Standards (NBS), now known as the National Institute of Standards and Technology (NIST), buried over 6000 corrosion coupons or specimens of stainless steel Types 201, 202, 301, 304, 316, 409, 410, 430, and 434. The coupons were configured as sheet metal plates, coated plates, cross-welded plates, U-bend samples, sandwiched materials, and welded tubes. All coupons were of various heat-treatments and cold worked conditions and were buried at six distinctive soil-type sites throughout the United States. The NBS scientists dug five sets of two trenches at each of the six sites. In each pair of trenches, they buried duplicate sets of stainless steel coupons. The NBS study was designed to retrieve coupons after one year, two years, four years, eight years, and x years in the soil. During the first eight years of the study, four of five planned removals were completed. After the fourth retrieval, the NBS study was abandoned, and the fifth and final set of specimens remained undisturbed for over 33 years. In 2003, an interdisciplinary research team of industrial, university, and national laboratory investigators were funded under the United States Department of Energy’s Environmental Management Science Program (EMSP; Project Number 86803) to extract part of the remaining set of coupons at one of the test sites, characterize the stainless steel underground corrosion rates, and examine the fate and transport of metal ions into the soil. Extraction of one trench at one of the test sites occurred in April 2004. This report details only the characterization of corrosion found on the 14 welded coupons–two cross welded plates, six U-bends, and six welded tubes–that were retrieved from Site D, located near Wildwood, NJ. The welded coupons included Type 301, 304, 316, and 409 stainless steels. After 33 years in the soil, corrosion on the coupons varied according to alloy. This report discusses the stress corrosion cracking and

  10. Crack growth rates of nickel alloy welds in a PWR environment.

    SciTech Connect

    Alexandreanu, B.; Chopra, O. K.; Shack, W. J.; Energy Technology

    2006-05-31

    In light water reactors (LWRs), vessel internal components made of nickel-base alloys are susceptible to environmentally assisted cracking. A better understanding of the causes and mechanisms of this cracking may permit less conservative estimates of damage accumulation and requirements on inspection intervals. A program is being conducted at Argonne National Laboratory to evaluate the resistance of Ni alloys and their welds to environmentally assisted cracking in simulated LWR coolant environments. This report presents crack growth rate (CGR) results for Alloy 182 shielded-metal-arc weld metal in a simulated pressurized water reactor (PWR) environment at 320 C. Crack growth tests were conducted on 1-T compact tension specimens with different weld orientations from both double-J and deep-groove welds. The results indicate little or no environmental enhancement of fatigue CGRs of Alloy 182 weld metal in the PWR environment. The CGRs of Alloy 182 in the PWR environment are a factor of {approx}5 higher than those of Alloy 600 in air under the same loading conditions. The stress corrosion cracking for the Alloy 182 weld is close to the average behavior of Alloy 600 in the PWR environment. The weld orientation was found to have a profound effect on the magnitude of crack growth: cracking was found to propagate faster along the dendrites than across them. The existing CGR data for Ni-alloy weld metals have been compiled and evaluated to establish the effects of key material, loading, and environmental parameters on CGRs in PWR environments. The results from the present study are compared with the existing CGR data for Ni-alloy welds to determine the relative susceptibility of the specific Ni-alloy weld to environmentally enhanced cracking.

  11. Residual stress in laser welded dissimilar steel tube-to-tube joints

    SciTech Connect

    Sun, Zheng . Lab. of Production Engineering)

    1993-09-01

    Austenitic-ferritic dissimilar steel joints are widely used in power generation systems. Their utilization has proved to be efficient in terms of satisfactory properties and the economics. These types of joints have usually been produced using conventional welding processes, such as tungsten inert gas (TIG) welding. With the rapid development of high power lasers, laser welding has received considerable attention. Laser welding offers many advantages over conventional welding processes, e.g. low heat input, small heat-affected zone (HAZ), small distortion, and welding in an exact and reproducible manner. Residual stress distribution in laser welds may also differ from those made by conventional welding processes due to its special features. Residual stress, particularly tensile residual stress in the weld, can be very important factor in controlling the quality and service life of the welded structure. The formation of tensile residual stress in the weld may result in the initiation of fatigue cracking, stress corrosion cracking or other types of fractures. It is useful, therefore, to understand the distribution of residual stress in austenitic-ferritic laser welds, and thus evaluate the quality of the joints. Although residual stress distribution in the welded joints has been extensively investigated, little data are available for the residual stress distribution in laser welds. The aim of the work was to examine residual stress distribution along laser welds of dissimilar steel tube-to-tube joints, which were made by both autogeneous welding and welding with filler wire. The results were also compared with the joints made by plasma arc and TIG welding.

  12. Diffusion Welding of Alloys for Molten Salt Service - Status Report

    SciTech Connect

    Denis Clark; Ronald Mizia

    2012-05-01

    The present work is concerned with heat exchanger development for molten salt service, including the proposed molten salt reactor (MSR), a homogeneous reactor in which the fuel is dissolved in a circulating fluid of molten salt. It is an outgrowth of recent work done under the Next Generation Nuclear Plant (NGNP) program; what the two reactor systems have in common is an inherently safe nuclear plant with a high outlet temperature that is useful for process heat as well as more conventional generation The NGNP program was tasked with investigating the application of a new generation of nuclear power plants to a variety of energy needs. One baseline reactor design for this program is a high temperature, gas-cooled reactor (HTGR), which provides many options for energy use. These might include the conventional Rankine cycle (steam turbine) generation of electricity, but also other methods: for example, Brayton cycle (gas turbine) electrical generation, and the direct use of the high temperatures characteristic of HTGR output for process heat in the chemical industry. Such process heat is currently generated by burning fossil fuels, and is a major contributor to the carbon footprint of the chemical and petrochemical industries. The HTGR, based on graphite fuel elements, can produce very high output temperatures; ideally, temperatures of 900 C or even greater, which has significant energy advantages. Such temperatures are, of course, at the frontiers of materials limitations, at the upper end of the performance envelope of the metallic materials for which robust construction codes exist, and within the realm of ceramic materials, the fabrication and joining of which, on the scale of large energy systems, are at an earlier stage of development. A considerable amount of work was done in the diffusion welding of materials of interest for HTGR service with alloys such as 617 and 800H. The MSR output temperature is also materials limited, and is projected at about 700 C

  13. Diffusion Welding of Alloys for Molten Salt Service - Status Report

    SciTech Connect

    Denis Clark; Ronald Mizia; Piyush Sabharwall

    2012-09-01

    The present work is concerned with heat exchanger development for molten salt service, including the proposed molten salt reactor (MSR), a homogeneous reactor in which the fuel is dissolved in a circulating fluid of molten salt. It is an outgrowth of recent work done under the Next Generation Nuclear Plant (NGNP) program; what the two reactor systems have in common is an inherently safe nuclear plant with a high outlet temperature that is useful for process heat as well as more conventional generation The NGNP program was tasked with investigating the application of a new generation of nuclear power plants to a variety of energy needs. One baseline reactor design for this program is a high temperature, gas-cooled reactor (HTGR), which provides many options for energy use. These might include the conventional Rankine cycle (steam turbine) generation of electricity, but also other methods: for example, Brayton cycle (gas turbine) electrical generation, and the direct use of the high temperatures characteristic of HTGR output for process heat in the chemical industry. Such process heat is currently generated by burning fossil fuels, and is a major contributor to the carbon footprint of the chemical and petrochemical industries. The HTGR, based on graphite fuel elements, can produce very high output temperatures; ideally, temperatures of 900 °C or even greater, which has significant energy advantages. Such temperatures are, of course, at the frontiers of materials limitations, at the upper end of the performance envelope of the metallic materials for which robust construction codes exist, and within the realm of ceramic materials, the fabrication and joining of which, on the scale of large energy systems, are at an earlier stage of development. A considerable amount of work was done in the diffusion welding of materials of interest for HTGR service with alloys such as 617 and 800H. The MSR output temperature is also materials limited, and is projected at about 700

  14. Laser Beam Welding of Ultra-high Strength Chromium Steel with Martensitic Microstructure

    NASA Astrophysics Data System (ADS)

    Dahmen, Martin; Janzen, Vitalij; Lindner, Stefan; Wagener, Rainer

    A new class of steels is going to be introduced into sheet manufacturing. Stainless ferritic and martensitic steels open up opportunities for sheet metal fabrication including hot stamping. Strengths of up to 2 GPa at fracture elongations of 15% can be attained through this. Welding of these materials, as a result, became a challenge. Energy-reduced welding methods with in-situ heat treatment are required in order to ensure the delicate and complex heat control. Laser beam welding is the joining technique of choice to supply minimum heat input to the fusion process and to apply efficient heat control. For two application cases, tailored blank production in as-rolled condition and welding during assembly in hot stamped condition, welding processes have been developed. The welding suitability is shown through metallurgical investigations of the welds. Crash tests based on the KS-II concept as well as fatigue tests prove the applicability of the joining method.

  15. Simulation and Technology of Hybrid Welding of Thick Steel Parts with High Power Fiber Laser

    NASA Astrophysics Data System (ADS)

    Turichin, Gleb; Valdaytseva, Ekaterina; Tzibulsky, Igor; Lopota, Alexander; Velichko, Olga

    The article devoted to steady state and dynamic simulation of melt pool behavior during hybrid laser-arc welding of pipes and shipbuilding sections. The quasi-stationary process-model was used to determine an appropriate welding mode. The dynamical model of laser welding was used for investigation of keyhole depth and width oscillations. The experiments of pipe steel and stainless steel hybrid laser-MAG welding have been made with 15-kW fiber laser in wide range of welding mode parameters. Comparison of experimentally measured and simulated behavior of penetration depth as well as their oscillation spectra approved the self-oscillation nature of melt pool behavior. The welding mode influence of melt pool stability has also been observed. The technological peculiarities, which allow provide high quality weld seam, has been discussed also.

  16. Friction Stir Welding in HSLA-65 Steel: Part I. Influence of Weld Speed and Tool Material on Microstructural Development

    NASA Astrophysics Data System (ADS)

    Barnes, S. J.; Bhatti, A. R.; Steuwer, A.; Johnson, R.; Altenkirch, J.; Withers, P. J.

    2012-07-01

    A systematic set of single-pass full penetration friction stir bead-on-plate and butt-welds in HSLA-65 steel were produced using a range of different traverse speeds (50 to 500 mm/min) and two tool materials (W-Re and PCBN). Microstructural analysis of the welds was carried out using optical microscopy, and hardness variations were also mapped across the weld-plate cross sections. The maximum and minimum hardnesses were found to be dependent upon both welding traverse speed and tool material. A maximum hardness of 323 Hv(10) was observed in the mixed martensite/bainite/ferrite microstructure of the weld nugget for a welding traverse speed of 200 mm/min using a PCBN tool. A minimum hardness of 179 Hv(10) was found in the outer heat-affected zone (OHAZ) for welding traverse speed of 50 mm/min using a PCBN tool. The distance from the weld centerline to the OHAZ increased with decreasing weld speed due to the greater heat input into the weld. Likewise for similar energy inputs, the size of the transformed zone and the OHAZ increased on moving from a W-Re tool to a PCBN tool probably due to the poorer thermal conductivity of the PCBN tool. The associated residual stresses are reported in Part II of this series of articles.

  17. FRACTURE BEHAVIOR OF ALLOY 600, ALLOY 690, EN82H WELDS AND EN52 WELDS IN WATER

    SciTech Connect

    Mills, W.J., Brown, C.M. and Burke, M.G.

    2000-01-11

    The cracking resistance of Alloy 600, Alloy 690 and their welds, EN82H and EN52, was characterized by conducting J{sub IC} rising load tests in air and hydrogenated water and cooldown testing in water under constant-displacement conditions. All test materials displayed excellent toughness in air and high temperature water, but Alloy 690 and the two welds were severely embrittled in low temperature water. In 54 C water with 150 cc H{sub 2}/kg H{sub 2}O, J{sub IC} values were reduced by 70% to 95%, relative to their air counterpart. The toughness degradation was associated with a fracture mechanism transition from microvoid coalescence to intergranular fracture. Comparison of the cracking response in water with that for hydrogen-precharged specimens tested in air demonstrated that susceptibility to low temperature crack propagation (LTCP) is due to hydrogen embrittlement of grain boundaries. The effects of water temperature, hydrogen content and loading rate on LTCP were studied. In addition, testing of specimens containing natural weld defects and as-machined notches was performed to determine if low temperature cracking can initiate at these features. Unlike the other materials, Alloy 600 is not susceptible to LTCP as the toughness in 54 C water remained high and a microvoid coalescence mechanism was operative in both air and water. Cooldown testing of EN82H welds under constant-displacement conditions was performed to determine if LTCP data from rising load J{sub IC}/K{sub Pmax} tests predict the onset of LTCP for other load paths. In these tests, bolt-loaded CT specimens were subjected to 288 C water for up to 1 week, cooled to 54 C and held in 54 C hydrogenated water for 1 week. This cycle was repeated up to 6 times. For two of the three welds tested, critical K{sub I} levels for LTCP under constant-displacement conditions were much higher than rising load K{sub Pmax} values. Bolt-loaded specimens from a third weld were found to exhibit LTCP at K{sub I} levels

  18. Hybrid Laser-arc Welding of 17-4 PH Martensitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Ma, Junjie; Atabaki, Mehdi Mazar; Pillai, Raju; Kumar, Biju; Vasudevan, Unnikrishnan; Sreshta, Harold; Kovacevic, Radovan

    2015-06-01

    17-4 PH stainless steel has wide applications in severe working conditions due to its combination of good corrosion resistance and high strength. The weldability of 17-4 PH stainless steel is challenging. In this work, hybrid laser-arc welding was developed to weld 17-4 PH stainless steel. This method was chosen based on its advantages, such as deep weld penetration, less filler materials, and high welding speed. The 17-4 PH stainless steel plates with a thickness of 19 mm were successfully welded in a single pass. During the hybrid welding, the 17-4 PH stainless steel was immensely susceptible to porosity and solidification cracking. The porosity was avoided by using nitrogen as the shielding gas. The nitrogen stabilized the keyhole and inhibited the formation of bubbles during welding. Solidification cracking easily occurred along the weld centerline at the root of the hybrid laser-arc welds. The microstructural evolution and the cracking susceptibility of 17-4 PH stainless steel were investigated to remove these centerline cracks. The results showed that the solidification mode of the material changed due to high cooling rate at the root of the weld. The rapid cooling rate caused the transformation from ferrite to austenite during the solidification stage. The solidification cracking was likely formed as a result of this cracking-susceptible microstructure and a high depth/width ratio that led to a high tensile stress concentration. Furthermore, the solidification cracking was prevented by preheating the base metal. It was found that the preheating slowed the cooling rate at the root of the weld, and the ferrite-to-austenite transformation during the solidification stage was suppressed. Delta ferrite formation was observed in the weld bead as well no solidification cracking occurred by optimizing the preheating temperature.

  19. Welding Stainless Steels and Refractory Metals Using Diode-Pumped Continuous Wave Nd:YAG Lasers

    SciTech Connect

    Palmer, T A; Elmer, J W; Pong, R; Gauthier, M D

    2004-09-27

    This report provides an overview of a series of developmental welding studies performed on a 2.2 kW Rofin Sinar DY-022 Diode Pumped Continuous Wave (CW) Nd:YAG welder at Lawrence Livermore National Laboratory (LLNL). Several materials systems, ranging from refractory metals, such as commercially pure tantalum and vanadium, to austenitic stainless steels, including both 304L and 21-6-9 grades, are examined. Power input and travel speed are systematically varied during the welding of each materials system, and the width, depth, and cross sectional area of the resulting weld fusion zones are measured. These individual studies are undertaken in order to characterize the response of the welder to changes in these welding parameters for a range of materials and to determine the maximum depth of penetration of which this welder is capable in each materials system. The maximum weld depths, which are on the order of 5.4 mm, are observed in the 21-6-9 austenitic stainless steel at the maximum laser power setting (2200 W) and a slow travel speed (6.4 mm/sec). The next highest weld depth is observed in the 304L stainless steel, followed by that observed in the vanadium and, finally, in the tantalum. Porosity, which is attributed to the collapse of the keyhole during welding, is also observed in the welds produced in tantalum, vanadium, and 304L stainless steel. Only the 21-6-9 austenitic stainless steel welds displayed little or no porosity over the range of welding parameters. Comparisons with similar laser welding systems are also made for several of these same materials systems. When compared with the welds produced by these other systems, the LLNL system typically produces welds of an equivalent or slightly higher depth.

  20. Radiation resistant austenitic stainless steel alloys

    DOEpatents

    Maziasz, Philip J.; Braski, David N.; Rowcliffe, Arthur F.

    1989-01-01

    An austenitic stainless steel alloy, with improved resistance to radiation-induced swelling and helium embrittlement, and improved resistance to thermal creep at high temperatures, consisting essentially of, by weight percent: from 16 to 18% nickel; from 13 to 17% chromium; from 2 to 3% molybdenum; from 1.5 to 2.5% manganese; from 0.01 to 0.5% silicon; from 0.2 to 0.4% titanium; from 0.1 to 0.2% niobium; from 0.1 to 0.6% vanadium; from 0.06 to 0.12% carbon; from 0.01% to 0.03% nitrogen; from 0.03 to 0.08% phosphorus; from 0.005 to 0.01% boron; and the balance iron, and wherein the alloy may be thermomechanically treated to enhance physical and mechanical properties.

  1. Radiation resistant austenitic stainless steel alloys

    DOEpatents

    Maziasz, P.J.; Braski, D.N.; Rowcliffe, A.F.

    1987-02-11

    An austenitic stainless steel alloy, with improved resistance to radiation-induced swelling and helium embrittlement, and improved resistance to thermal creep at high temperatures, consisting essentially of, by weight percent: from 16 to 18% nickel; from 13 to 17% chromium; from 2 to 3% molybdenum; from 1.5 to 2.5% manganese; from 0.01 to 0.5% silicon; from 0.2 to 0.4% titanium; from 0.1 to 0.2% niobium; from 0.1 to 0.6% vanadium; from 0.06 to 0.12% carbon; from 0.01 to 0.03% nitrogen; from 0.03 to 0.08% phosphorus; from 0.005 to 0.01% boron; and the balance iron, and wherein the alloy may be thermomechanically treated to enhance physical and mechanical properties. 4 figs.

  2. Mechanical Properties, Microstructure and Crystallographic Texture of Magnesium AZ91-D Alloy Welded by Friction Stir Welding (FSW)

    NASA Astrophysics Data System (ADS)

    Kouadri-Henni, A.; Barrallier, L.

    2014-10-01

    The objective of the study was to characterize the properties of a magnesium alloy welded by friction stir welding. The results led to a better understanding of the relationship between this process and the microstructure and anisotropic properties of alloy materials. Welding principally leads to a large reduction in grain size in welded zones due to the phenomenon of dynamic recrystallization. The most remarkable observation was that crystallographic textures appeared from a base metal without texture in two zones: the thermo-mechanically affected and stir-welded zones. The latter zone has the peculiarity of possessing a marked texture with two components on the basal plane and the pyramidal plane. These characteristics disappeared in the thermo-mechanically affected zone (TMAZ), which had only one component following the basal plane. These modifications have been explained by the nature of the plastic deformation in these zones, which occurs at a moderate temperature in the TMAZ and high temperature in the SWZ.

  3. Welding metallurgy of nickel alloys in gas turbine components

    SciTech Connect

    Lingenfelter, A. C., LLNL

    1997-05-21

    Materials for gas turbine engines are required to meet a wide range of temperature and stress application requirements. These alloys exhibit a combination of creep resistance, creep rupture strength, yield and tensile strength over a wide temperature range, resistance to environmental attack (including oxidation, nitridation, sulphidation and carburization), fatigue and thermal fatigue resistance, metallurgical stability and useful thermal expansion characteristics. These properties are exhibited by a series of solid-solution-strengthened and precipitation-hardened nickel, iron and cobalt alloys. The properties needed to meet the turbine engine requirements have been achieved by specific alloy additions, by heat treatment and by thermal mechanical processing. A thorough understanding of the metallurgy and metallurgical processing of these materials is imperative in order to successfully fusion weld them. This same basic understanding is required for repair of a component with the added dimension of the potential effects of thermal cycling and environmental exposure the component will have endured in service. This article will explore the potential problems in joining and repair welding these materials.

  4. Alloying elemental change of SS-316 and Al-5754 during laser welding using real time laser induced breakdown spectroscopy (LIBS) accompanied by EDX and PIXE microanalysis

    NASA Astrophysics Data System (ADS)

    Jandaghi, M.; Parvin, P.; Torkamany, M. J.; Sabbaghzadeh, J.

    Experimental studies of pulsed laser welding of stainless steel 316 in keyhole mode was done to examine a vaporization model based on the kinetic theory of gases and the thermodynamic laws. A long pulsed Nd:YAG laser with variable duration of 1-12 ms and 9-17 Gw/cm2 was employed. The undesirable loss of volatile elements affects on the weld metal compositions and the alloy properties. The model predicts that the loss of alloying elements strongly takes place at higher peak powers and longer pulse durations. On the other hand, the model shows the rapid migration of Mn and Cr based on the pressure and concentration gradients from the molten pool. Accordingly, the concentrations of iron, chromium, nickel and manganese were determined in the weld pool by means of the energy dispersive x-ray analysis (EDX) and proton induced X ray characteristics (PIXE) microanalysis. The change of weld metal composition of aluminium alloy 5754 in keyhole mode laser welding, was investigated using the model and was supported by the successive measurements. The model predicts that the concentration of magnesium in the weld metal decreases, while the aluminium concentration increases. Moreover, the real time concentrations of aluminium and magnesium elements in the weld metal were determined by laser induced breakdown spectroscopy (LIBS) at different conditions. We conclude that variation of the Al to Mg concentration ratio is negligible with various laser power densities while it is strongly correlated to the pulse duration.

  5. CO2 laser beam welding of 6061-T6 aluminum alloy thin plate

    NASA Astrophysics Data System (ADS)

    Hirose, Akio; Kobayashi, Kojiro F.; Todaka, Hirotaka

    1997-12-01

    Laser beam welding is an attractive welding process for age-hardened aluminum alloys, because its low heat input minimizes the width of weld fusion and heat-affected zones (HAZs). In the present work, 1-mm-thick age-hardened Al-Mg-Si alloy, 6061-T6, plates were welded with full penetration using a 2.5-kW CO2 laser. Fractions of porosity in the fusion zones were less than 0.05 pct in bead-on-plate welding and less than 0.2 pct in butt welding with polishing the groove surface before welding. The width of a softened region in the-laser beam welds was less than 1/4 times that of a tungsten inert gas (TIG) weld. The softened region is caused by reversion of strengthening β″ (Mg2Si) precipitates due to weld heat input. The hardness values of the softened region in the laser beam welds were almost fully recovered to that of the base metal after an artificial aging treatment at 448 K for 28.8 ks without solution annealing, whereas those in the TIG weld were not recovered in a partly reverted region. Both the bead-on-plate weld and the butt weld after the postweld artificial aging treatment had almost equivalent tensile strengths to that of the base plate.

  6. Investigation of the Microstructure of Joints of Aluminum Alloys Produced by Friction Stir Welding

    NASA Astrophysics Data System (ADS)

    Kolubaev, E. A.

    2015-02-01

    Special features of the microstructure of joints of aluminum-magnesium and aluminum-copper alloys produced by friction stir welding are analyzed. It is demonstrated that a layered structure with ultradisperse grains is produced by friction stir welding at the center of the weld joint. An analogy is drawn between the microstructures of joints produced by friction stir welding and surface layer produced by sliding friction.

  7. Corrosion testing of welds in austenitic stainless steel tubing using ASTM A 249 boiling HCl weld decay test (Supplementary requirement S7)

    SciTech Connect

    Pepin, J.J.; Blessman, E.R.; Lovejoy, P.T.

    1997-06-01

    Welded stainless steel tubing manufactured to ASTM A 249 specification, Welded Austenitic Steel Boiler, Superheater, Heat-Exchanger, and Condenser Tubes, can exhibit substantial differences in its S7 Weld Decay Test performance. Manufacturing conditions are the major contributors to the variation in S7 results. The method of measuring the S7 samples can also contribute to nonrepresentative results. The S7 boiling HCl test is a good indication of weld homogenization. To ensure that the tubing will have no tendency toward selective or accelerated weld corrosion, a maximum corrosion ratio of 1.0 must be achieved across the entire weld.

  8. Bobbin-Tool Friction-Stir Welding of Thick-Walled Aluminum Alloy Pressure Vessels

    SciTech Connect

    Dalder, E C; Pastrnak, J W; Engel, J; Forrest, R S; Kokko, E; Ternan, K M; Waldron, D

    2007-06-06

    It was desired to assemble thick-walled Al alloy 2219 pressure vessels by bobbin-tool friction-stir welding. To develop the welding-process, mechanical-property, and fitness-for-service information to support this effort, extensive friction-stir welding-parameter studies were conducted on 2.5 cm. and 3.8 cm. thick 2219 Al alloy plate. Starting conditions of the plate were the fully-heat-treated (-T62) and in the annealed (-O) conditions. The former condition was chosen with the intent of using the welds in either the 'as welded' condition or after a simple low-temperature aging treatment. Since preliminary stress-analyses showed that stresses in and near the welds would probably exceed the yield-strength of both 'as welded' and welded and aged weld-joints, a post-weld solution-treatment, quenching, and aging treatment was also examined. Once a suitable set of welding and post-weld heat-treatment parameters was established, the project divided into two parts. The first part concentrated on developing the necessary process information to be able to make defect-free friction-stir welds in 3.8 cm. thick Al alloy 2219 in the form of circumferential welds that would join two hemispherical forgings with a 102 cm. inside diameter. This necessitated going to a bobbin-tool welding-technique to simplify the tooling needed to react the large forces generated in friction-stir welding. The bobbin-tool technique was demonstrated on both flat-plates and plates that were bent to the curvature of the actual vessel. An additional issue was termination of the weld, i.e. closing out the hole left at the end of the weld by withdrawal of the friction-stir welding tool. This was accomplished by friction-plug welding a slightly-oversized Al alloy 2219 plug into the termination-hole, followed by machining the plug flush with both the inside and outside surfaces of the vessel. The second part of the project involved demonstrating that the welds were fit for the intended service. This

  9. Radiographic detection of defects in friction stir welding on aluminum alloy AMg5M

    SciTech Connect

    Tarasov, Sergei Yu. Kolubaev, Evgeny A.; Rubtsov, Valery E.

    2014-11-14

    In order to reveal weld defects specific to friction stir welding we undertook radiographic inspection of AMg5M aluminum alloy welded joints. Weld defects in the form of voids have been revealed in the weld obtained under the non-optimal rotation and feed rate. Both shape and size of these defects have been confirmed by examining metallographically successive sections prepared in the weld plane as well as in the plane transversal to the tool feed direction. Linear defects have been also found in the sections that are not seen in the radiographic images. Both the preferable localization and origination of the defects have been analyzed.

  10. Computational Analysis of Material Flow During Friction Stir Welding of AA5059 Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Arakere, G.; Pandurangan, B.; Ochterbeck, J. M.; Yen, C.-F.; Cheeseman, B. A.; Reynolds, A. P.; Sutton, M. A.

    2012-09-01

    Workpiece material flow and stirring/mixing during the friction stir welding (FSW) process are investigated computationally. Within the numerical model of the FSW process, the FSW tool is treated as a Lagrangian component while the workpiece material is treated as an Eulerian component. The employed coupled Eulerian/Lagrangian computational analysis of the welding process was of a two-way thermo-mechanical character (i.e., frictional-sliding/plastic-work dissipation is taken to act as a heat source in the thermal-energy balance equation) while temperature is allowed to affect mechanical aspects of the model through temperature-dependent material properties. The workpiece material (AA5059, solid-solution strengthened and strain-hardened aluminum alloy) is represented using a modified version of the classical Johnson-Cook model (within which the strain-hardening term is augmented to take into account for the effect of dynamic recrystallization) while the FSW tool material (AISI H13 tool steel) is modeled as an isotropic linear-elastic material. Within the analysis, the effects of some of the FSW key process parameters are investigated (e.g., weld pitch, tool tilt-angle, and the tool pin-size). The results pertaining to the material flow during FSW are compared with their experimental counterparts. It is found that, for the most part, experimentally observed material-flow characteristics are reproduced within the current FSW-process model.

  11. Fatigue Crack Growth Behavior of Gas Metal Arc Welded AISI 409 Grade Ferritic Stainless Steel Joints

    NASA Astrophysics Data System (ADS)

    Lakshminarayanan, A. K.; Shanmugam, K.; Balasubramanian, V.

    2009-10-01

    The effect of filler metals such as austenitic stainless steel, ferritic stainless steel, and duplex stainless steel on fatigue crack growth behavior of the gas metal arc welded ferritic stainless steel joints was investigated. Rolled plates of 4 mm thickness were used as the base material for preparing single ‘V’ butt welded joints. Center cracked tensile specimens were prepared to evaluate fatigue crack growth behavior. Servo hydraulic controlled fatigue testing machine with a capacity of 100 kN was used to evaluate the fatigue crack growth behavior of the welded joints. From this investigation, it was found that the joints fabricated by duplex stainless steel filler metal showed superior fatigue crack growth resistance compared to the joints fabricated by austenitic and ferritic stainless steel filler metals. Higher yield strength and relatively higher toughness may be the reasons for superior fatigue performance of the joints fabricated by duplex stainless steel filler metal.

  12. Aluminum Lithium Alloy 2195 Fusion Welding Improvements with New Filler Wire

    NASA Technical Reports Server (NTRS)

    Russell, Carolyn; Bjorkman, Gerry; McCool, Carolyn (Technical Monitor)

    2000-01-01

    A viewgraph presentation outlines NASA Marshall Space Flight Center, Lockheed Martin Michoud Space Systems, and McCook Metals' development an aluminum-copper weld filler wire for fusion welding 2195 aluminum lithium. The aluminum-copper based weld filler wire has been identified as B218, which is the result of six years of weld filler wire development funded by NASA, Lockheed Martin, and McCook Metals. The Super Lightweight External Tank for the NASA Space Shuttle Program consists of 2195 welded with 4043 aluminum-silicon weld filler wire. The B218 filler wire chemistry was developed to produce enhanced 2195 weld and repair weld mechanical properties. An initial characterization of the B218 weld filler wire was performed consisting of initial weld and repair weld evaluation comparing B218 and 4043. The testing involved room temperature and cryogenic tensile testing along with fracture toughness testing. B218 weld filler wire proved to produce enhanced initial and repair weld tensile and fracture properties over 4043. B218 weld filler wire has proved to be a superior weld filler wire for welding 2195 and other aluminum lithium alloys over 4043.

  13. Characteristics of laser beam welds of age-hardenable 6061-T6 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Hirose, Akio; Kobayashi, Kojiro F.

    2003-03-01

    Laser beam welding is attractive for joining age-hardenable aluminum alloys, because its low over-all heat input results in a narrow weld heat affected zone (HAZ), where softening caused by dissolution of age precipitates occurs. In the present work, 1mm-thick 6061-T6 aluminum alloy plates were welded using a 2.5 kW CO2 laser and it was experimentally proved that the width of the softened region in the laser beam weld was less than 1/7 that of a TIG weld. Moreover the hardness in the softened region of the laser beam weld was found to be almost fully recovered to the base metal hardness by applying a post-weld aging treatment at 443 K for 28.8 ks without solution annealing unlike the TIG weld. These results characterize the advantage of laser beam welding in joining of the age-hardenable aluminum alloy as compared with the conventional arc welding. The hardness distributions in the HAZ were theoretically evaluated based on kinetic equations describing the dissolution of hardening β' (Mg2Si) precipitates and the precipitation of non-hardening β' (Mg2Si) precipitates during the weld thermal cycles to quantitatively prove above mentioned advantageous characteristics of laser beam welding.

  14. Thermomechanical history measurements on Type 304L stainless steel pipe girth welds

    SciTech Connect

    Li, Ming; Atteridge, D.G.; Anderson, W.E.; Turpin, R.; West, S.L.

    1993-12-31

    Thermal and strain histories were recorded for three 40-cm-diameter (16 inch), Type 304L stainless steel (SS), schedule 40 (1.27 cm thickness) pipe girth welds. Two weld groove preparations were standard V grooves while the third was a narrow groove configuration. The welding parameters for the three pipe welds simulated expected field practice as closely as possible. The narrow gap weld was completed in four continuous passes while the other two welds required six and nine (discontinuous) passes, due to the use of different weld wire diameters. Thermomechanical history measurements were taken on the inner counterbore surface, encompassing the weld centerline and heat-affected zone (HAZ), as well as 10 cm of inner counterbore surface on either side of the weld centerline; a total of 47 data acquisition instruments were used for each weld. These instruments monitored: (1) weld shrinkages parallel to the pipe axis; (2) surface temperatures; (3) surface strains parallel to weld centerline; and (4) radial deformations. Results show that the weld and HAZ experienced cyclic deformation in the radial direction during welding, indicating that the final residual stress distribution in multi-pass pipe weldments is not axisymmetric. Measured radial and axial deformations were smaller for the narrow gap groove than for the standard V grooves, suggesting that the narrow gap groove weldment may have lower residual stress levels than the standard V groove weldments. This study provides the experimental database and a guideline for further computational modeling work.

  15. Effect of Welding Speeds on Mechanical Properties of Level Compensation Friction Stir Welded 6061-T6 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Wen, Quan; Yue, Yumei; Ji, Shude; Li, Zhengwei; Gao, Shuangsheng

    2016-04-01

    In order to eliminate the flash, arc corrugation and concave in weld zone, level compensation friction stir welding (LCFSW) was put forward and successfully applied to weld 6061-T6 aluminum alloy with varied welding speed at a constant tool rotational speed of 1,800 rpm in the present study. The glossy joint with equal thickness of base material can be attained, and the shoulder affected zone (SAZ) was obviously reduced. The results of transverse tensile test indicate that the tensile strength and elongation reach the maximum values of 248 MPa and 7.1% when the welding speed is 600 mm/min. The microhardness of weld nugget (WN) is lower than that of base material. The tensile fracture position locates at the heat affected zone (HAZ) of the advancing side (AS), where the microhardness is the minimum. The fracture surface morphology represents the typical ductile fracture.

  16. Thermal Modeling of Al-Al and Al-Steel Friction Stir Spot Welding

    NASA Astrophysics Data System (ADS)

    Jedrasiak, P.; Shercliff, H. R.; Reilly, A.; McShane, G. J.; Chen, Y. C.; Wang, L.; Robson, J.; Prangnell, P.

    2016-07-01

    This paper presents a finite element thermal model for similar and dissimilar alloy friction stir spot welding (FSSW). The model is calibrated and validated using instrumented lap joints in Al-Al and Al-Fe automotive sheet alloys. The model successfully predicts the thermal histories for a range of process conditions. The resulting temperature histories are used to predict the growth of intermetallic phases at the interface in Al-Fe welds. Temperature predictions were used to study the evolution of hardness of a precipitation-hardened aluminum alloy during post-weld aging after FSSW.

  17. 75 FR 60814 - Carbon Steel Butt-Weld Pipe Fittings From Brazil, China, Japan, Taiwan, and Thailand

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-01

    ... Investigation No. F.R. cite 12/17/86 Carbon steel butt- 731-TA-308 51 FR 45152. weld pipe fittings/ Brazil. 12/17/86 Carbon steel butt- 731-TA-310 51 FR 45152. weld pipe fittings/ Taiwan. 2/10/87 Carbon steel butt- 731-TA-309 52 FR 4167. weld pipe fittings/ Japan. 7/6/92 Carbon steel butt- 731-TA-520 57...

  18. 49 CFR 230.33 - Welded repairs and alterations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... containing alloy steel or carbon steel with a carbon content over 0.25 percent. Prior to welding on unstayed... requirements in § 230.20 at this time. (b) Unstayed portions of the boiler containing carbon steel not exceeding 0.25 percent carbon. The steam locomotive owner and/or operator shall perform any welding...

  19. An evaluation of GTAW-P versus GTA welding of alloy 718

    NASA Technical Reports Server (NTRS)

    Gamwell, W. R.; Kurgan, C.; Malone, T. W.

    1991-01-01

    Mechanical properties were evaluated to determine statistically whether the pulsed current gas tungsten arc welding (GTAW-P) process produces welds in alloy 718 with room temperature structural performance equivalent to current Space Shuttle Main Engine (SSME) welds manufactured by the constant current GTAW-P process. Evaluations were conducted on two base metal lots, two filler metal lots, two heat input levels, and two welding processes. The material form was 0.125-inch (3.175-mm) alloy 718 sheet. Prior to welding, sheets were treated to either the ST or STA-1 condition. After welding, panels were left as welded or heat treated to the STA-1 condition, and weld beads were left intact or machined flush. Statistical analyses were performed on yield strength, ultimate tensile strength (UTS), and high cycle fatigue (HCF) properties for all the post welded material conditions. Analyses of variance were performed on the data to determine if there were any significant effects on UTS or HCF life due to variations in base metal, filler metal, heat input level, or welding process. Statistical analyses showed that the GTAW-P process does produce welds with room temperature structural performance equivalent to current SSME welds manufactured by the GTAW process, regardless of prior material condition or post welding condition.

  20. Qualification of electron-beam welded joints between copper and stainless steel for cryogenic application

    NASA Astrophysics Data System (ADS)

    Lusch, C.; Borsch, M.; Heidt, C.; Magginetti, N.; Sas, J.; Weiss, K.-P.; Grohmann, S.

    2015-12-01

    Joints between copper and stainless steel are commonly applied in cryogenic systems. A relatively new and increasingly important method to combine these materials is electron-beam (EB) welding. Typically, welds in cryogenic applications need to withstand a temperature range from 300K down to 4K, and pressures of several MPa. However, few data are available for classifying EB welds between OFHC copper and 316L stainless steel. A broad test program was conducted in order to qualify this kind of weld. The experiments started with the measurement of the hardness in the weld area. To verify the leak-tightness of the joints, integral helium leak tests at operating pressures of 16 MPa were carried out at room- and at liquid nitrogen temperature. The tests were followed by destructive tensile tests at room temperature, at liquid nitrogen and at liquid helium temperatures, yielding information on the yield strength and the ultimate tensile strength of the welds at these temperatures. Moreover, nondestructive tensile tests up to the yield strength, i.e. the range in which the weld can be stressed during operation, were performed. Also, the behavior of the weld upon temperature fluctuations between room- and liquid nitrogen temperature was tested. The results of the qualification indicate that EB welded joints between OFHC copper and 316L stainless steel are reliable and present an interesting alternative to other technologies such as vacuum brazing or friction welding.

  1. Friction Stir Spot Welding (FSSW) of Advanced High Strength Steel (AHSS)

    SciTech Connect

    Santella, M. L.; Hovanski, Yuri; Pan, Tsung-Yu

    2012-04-16

    Friction stir spot welding (FSSW) is applied to join advanced high strength steels (AHSS): galvannealed dual phase 780 MPa steel (DP780GA), transformation induced plasticity 780 MPa steel (TRIP780), and hot-stamped boron steel (HSBS). A low-cost Si3N4 ceramic tool was developed and used for making welds in this study instead of polycrystalline cubic boron nitride (PCBN) material used in earlier studies. FSSW has the advantages of solid-state, low-temperature process, and the ability of joining dissimilar grade of steels and thicknesses. Two different tool shoulder geometries, concave with smooth surface and convex with spiral pattern, were used in the study. Welds were made by a 2-step displacement control process with weld time of 4, 6, and 10 seconds. Static tensile lap-shear strength achieved 16.4 kN for DP780GA-HSBS and 13.2kN for TRIP780-HSBS, above the spot weld strength requirements by AWS. Nugget pull-out was the failure mode of the joint. The joining mechanism was illustrated from the cross-section micrographs. Microhardness measurement showed hardening in the upper sheet steel (DP780GA or TRIP780) in the weld, but softening of HSBS in the heat-affect zone (HAZ). The study demonstrated the feasibility of making high-strength AHSS spot welds with low-cost tools.

  2. Mathematical modeling and experimental validation of gas metal arc welding of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Guo, Hao

    2004-11-01

    Both mathematical modeling and experiments have been conducted on the GMAW of aluminum alloys. Transient weld shapes and distributions of temperature and velocity were calculated by a three-dimensional numerical model. The final weld bead shape and dimensions and peak temperature in the heat-affected zone (HAZ) were obtained. Metallurgical characterizations including microscopy and Knoop micro-hardness measurements were performed on experimental samples. The experimental weld bead shape and dimensions were in agreement with modeling predictions. It was found that a crater-shaped weld pool was formed as a result of weld pool dynamics. The combined effect of a series of droplet impingements and hydrostatic force caused the fluid level at the rear end of weld pool to vary periodically to form ripples on the weld bead. Also, the high peak temperature near the fusion line caused the HAZ softening. The lack of penetration in the cold weld is due to the lack of pre-heating by the welding arc. Three techniques were then proposed to increase the energy input at the initial stage of welding and improve cold weld penetration. The crater formation at the end of the welding process is due to the rapid solidification of the weld pool. The crater was filled and crater cracking was reduced by reducing welding current and reversing the welding direction at the same time before terminating the arc.

  3. A fundamental study on the structural integrity of magnesium alloys joined by friction stir welding

    NASA Astrophysics Data System (ADS)

    Rao, Harish Mangebettu

    The goal of this research is to study the factors that influence the physical and mechanical properties of lap-shear joints produced using friction stir welding. This study focuses on understanding the effect of tool geometry and weld process parameters including the tool rotation rate, tool plunge depth and dwell time on the mechanical performance of similar magnesium alloy and dissimilar magnesium to aluminum alloy weld joints. A variety of experimental activities were conducted including tensile and fatigue testing, fracture surface and failure analysis, microstructure characterization, hardness measurements and chemical composition analysis. An investigation on the effect of weld process conditions in friction stir spot welding of magnesium to magnesium produced in a manner that had a large effective sheet thickness and smaller interfacial hook height exhibited superior weld strength. Furthermore, in fatigue testing of friction stir spot welded of magnesium to magnesium alloy, lap-shear welds produced using a triangular tool pin profile exhibited better fatigue life properties compared to lap-shear welds produced using a cylindrical tool pin profile. In friction stir spot welding of dissimilar magnesium to aluminum, formation of intermetallic compounds in the stir zone of the weld had a dominant effect on the weld strength. Lap-shear dissimilar welds with good material mixture and discontinues intermetallic compounds in the stir zone exhibited superior weld strength compared to lap-shear dissimilar welds with continuous formation of intermetallic compounds in the stir zone. The weld structural geometry like the interfacial hook, hook orientation and bond width also played a major role in influencing the weld strength of the dissimilar lap-shear friction stir spot welds. A wide scatter in fatigue test results was observed in friction stir linear welds of aluminum to magnesium alloys. Different modes of failure were observed under fatigue loading including crack

  4. Stainless steel-zirconium alloy waste forms

    SciTech Connect

    McDeavitt, S.M.; Abraham, D.P.; Keiser, D.D. Jr.; Park, J.Y.

    1996-07-01

    An electrometallurgical treatment process has been developed by Argonne National Laboratory to convert various types of spent nuclear fuels into stable storage forms and waste forms for repository disposal. The first application of this process will be to treat spent fuel alloys from the Experimental Breeder Reactor-II. Three distinct product streams emanate from the electrorefining process: (1) refined uranium; (2) fission products and actinides extracted from the electrolyte salt that are processed into a mineral waste form; and (3) metallic wastes left behind at the completion of the electrorefining step. The third product stream (i.e., the metal waste stream) is the subject of this paper. The metal waste stream contains components of the chopped spent fuel that are unaffected by the electrorefining process because of their electrochemically ``noble`` nature; this includes the cladding hulls, noble metal fission products (NMFP), and, in specific cases, zirconium from metal fuel alloys. The selected method for the consolidation and stabilization of the metal waste stream is melting and casting into a uniform, corrosion-resistant alloy. The waste form casting process will be carried out in a controlled-atmosphere furnace at high temperatures with a molten salt flux. Spent fuels with both stainless steel and Zircaloy cladding are being evaluated for treatment; thus, stainless steel-rich and Zircaloy-rich waste forms are being developed. Although the primary disposition option for the actinides is the mineral waste form, the concept of incorporating the TRU-bearing product into the metal waste form has enough potential to warrant investigation.

  5. Tensile properties of vanadium-base alloys with a tungsten/inert-gas weld zone

    SciTech Connect

    Loomis, B.A.; Konicek, C.F.; Nowicki, L.J.; Smith, D.L.

    1992-12-31

    The tensile properties of V-(0-20)Ti and V-(O-15)Cr-5Ti alloys after butt-joining by tungsten/inert-gas (TIG) welding were determined from tests at 25{degrees}C. Tensile tests were conducted on both annealed and cold-worked materials with a TIG weld zone. The tensile properties of these materials were strongly influenced by the microstructure in the heat-affected zone adjacent to the weld zone and by the intrinsic fracture toughness of the alloys. TIG weld zones in these vanadium-base alloys had tensile properties comparable to those of recrystallized alloys without a weld zone. Least affected by the TIG welding were tensile properties of the V-5Ti and V-5Cr-5Ti alloys. Although the tensile properties of the V-5Ti and V- 5Cr-5Ti alloys with a TIG weld zone were acceptable for structural material, these properties would be improved by optimization of the welding parameters for minimum grain size in the heat-affected zone.

  6. Effect of preheat on residual stress distributions in arc-welded mild steel plates

    SciTech Connect

    Adedayo, S.M.; Adeyemi, M.B.

    2000-02-01

    Residual stress distribution in the longitudinal and transverse directions on a 6-mm-thick arc-welded mild steel plate was experimentally examined with and without initial preheat. Stress measurements were completed by monitoring strain changes on mounted strain gauges resulting from successive milling of the welded plate specimens. Machining stresses were also compensated for by carrying out measurements of strain changes due to milling operation of a stress-free unwelded annealed mild steel plate. High tensile residual stresses exist close to the weld line in both longitudinal and transverse stresses. Maximum longitudinal residual stress values existing close to the weld line are reduced (between 50 and 75%) due to the effect of initial metal preheat of 200 C of the welded steel plate.

  7. Adhesion of Salmonella Enteritidis and Listeria monocytogenes on stainless steel welds.

    PubMed

    Casarin, Letícia Sopeña; Brandelli, Adriano; de Oliveira Casarin, Fabrício; Soave, Paulo Azevedo; Wanke, Cesar Henrique; Tondo, Eduardo Cesar

    2014-11-17

    Pathogenic microorganisms are able to adhere on equipment surfaces, being possible to contaminate food during processing. Salmonella spp. and Listeria monocytogenes are important pathogens that can be transmitted by food, causing severe foodborne diseases. Most surfaces of food processing industry are made of stainless steel joined by welds. However currently, there are few studies evaluating the influence of welds in the microorganism's adhesion. Therefore the purpose of the present study was to investigate the adhesion of Salmonella Enteritidis and L. monocytogenes on surface of metal inert gas (MIG), and tungsten inert gas (TIG) welding, as well as to evaluate the cell and surface hydrophobicities. Results demonstrated that both bacteria adhered to the surface of welds and stainless steel at same levels. Despite this, bacteria and surfaces demonstrated different levels of hydrophobicity/hydrophilicity, results indicated that there was no correlation between adhesion to welds and stainless steel and the hydrophobicity. PMID:25261827

  8. Welding of 316L Austenitic Stainless Steel with Activated Tungsten Inert Gas Process

    NASA Astrophysics Data System (ADS)

    Ahmadi, E.; Ebrahimi, A. R.

    2015-02-01

    The use of activating flux in TIG welding process is one of the most notable techniques which are developed recently. This technique, known as A-TIG welding, increases the penetration depth and improves the productivity of the TIG welding. In the present study, four oxide fluxes (SiO2, TiO2, Cr2O3, and CaO) were used to investigate the effect of activating flux on the depth/width ratio and mechanical property of 316L austenitic stainless steel. The effect of coating density of activating flux on the weld pool shape and oxygen content in the weld after the welding process was studied systematically. Experimental results indicated that the maximum depth/width ratio of stainless steel activated TIG weld was obtained when the coating density was 2.6, 1.3, 2, and 7.8 mg/cm2 for SiO2, TiO2, Cr2O3, and CaO, respectively. The certain range of oxygen content dissolved in the weld, led to a significant increase in the penetration capability of TIG welds. TIG welding with active fluxes can increase the delta-ferrite content and improves the mechanical strength of the welded joint.

  9. Microsegregation in high-molybdenum austenitic stainless steel laser beam and gas tungsten arc welds

    SciTech Connect

    Kujanpaeae, V.P.; David, S.A.

    1986-01-01

    An austenitic stainless steel with 6% molybdenum (thickness 6 mm) was welded using laser beam (LB) and gas tungsten arc (GTA) processes at various welding speeds. Depending on the welding speed the primary dendrite spacing ranged from 12 to 17 ..mu..m and from 2 to 7 ..mu..m for the GTA and LB welds, respectively. Extensive segregation of molybdenum was observed in the GTA welds. The segregation ratio for molybdenum, C/sub ID//C/sub D/, was found to be 1.9 in the GTA weld, and 1.2 in the LB weld. Distribution of iron, chromium and nickel was found nearly uniform in both welds. A recovered microstructure was observed after a post-weld annealing heat treatment. Annealing had a profound effect on the molybdenum segregation ratio in the laser weld. The critical pitting temperature (CPT) determined by a standard test was 55/sup 0/C for welds made using both processes, whereas it was 75/sup 0/C for the base metal. Upon homogenization the CPT of the laser beam weld increased to the base metal value, while that of the gas tungsten arc weld remained at 60/sup 0/C.

  10. Investigation of defect rate of lap laser welding of stainless steel railway vehicles car body

    NASA Astrophysics Data System (ADS)

    Wang, Hongxiao

    2015-02-01

    In order to resolve the disadvantages such as poor appearance quality, poor tightness, low efficiency of resistance spot welding of stainless steel rail vehicles, partial penetration lap laser welding process was investigated widely. But due to the limitation of processing technology, there will be local incomplete fusion in the lap laser welding seam. Defect rate is the ratio of the local incomplete fusion length to the weld seam length. The tensile shear strength under different defect rate and its effect on the car body static strength are not clear. It is necessary to find the biggest defect rate by numerical analysis of effects of different defect rates on the laser welding stainless steel rail vehicle body structure strength ,and tests of laser welding shear tensile strength.

  11. Implications of changes in the post-weld heat treatment requirements on properties of steels and welds for offshore structures

    SciTech Connect

    Pisarski, H.G.

    1996-12-01

    The reductions in the post-weld heat treatment temperatures and hold times proposed in revisions to pressure vessel (BS5500) and offshore steel (EN 10225) codes are considered in relation to their effects on resistance to fracture initiation. A review of the effects of the proposed changes on the mechanical properties and residual stresses in medium strength C-Mn steels and welds is described. It is concluded that the proposed reductions in temperature and hold time will, in general, minimize the changes in mechanical properties which would occur under current PWHT procedures. However, the levels of residual stresses will be significantly higher, and this will reduce the margin against fracture initiation.

  12. Evaluation of weld crack susceptibility for neutron irradiated stainless steels

    NASA Astrophysics Data System (ADS)

    Suzuki, T.; Kohyama, A.; Hirose, T.; Narui, M.

    In order to clarify the mechanisms of weld cracking, especially for heat affected zone cracking in heavily neutron irradiated stainless steels and to establish a measure to evaluate crack susceptibility, a mini-sized Varestraint (variable restraint) test machine for hot laboratory operation was designed and fabricated. This unique PIE facility was successfully applied in the hot laboratory of IMR Oarai Branch of Tohoku University. The maximum restraint applied was 4% at the surface of the specimen. Specimen surface morphology and specimen microstructures were inspected by video microscope, SEM and TEM. Under the 2% surface restraint condition, clear formation of heat affected zone (HAZ) crack was observed for the case of neutron irradiation to produce 0.5 appm He and of 2.4 kJ heat input by TIG.

  13. Stainless steel submerged arc weld fusion line toughness

    SciTech Connect

    Rosenfield, A.R.; Held, P.R.; Wilkowski, G.M.

    1995-04-01

    This effort evaluated the fracture toughness of austenitic steel submerged-arc weld (SAW) fusion lines. The incentive was to explain why cracks grow into the fusion line in many pipe tests conducted with cracks initially centered in SAWS. The concern was that the fusion line may have a lower toughness than the SAW. It was found that the fusion line, Ji. was greater than the SAW toughness but much less than the base metal. Of greater importance may be that the crack growth resistance (JD-R) of the fusion line appeared to reach a steady-state value, while the SAW had a continually increasing JD-R curve. This explains why the cracks eventually turn to the fusion line in the pipe experiments. A method of incorporating these results would be to use the weld metal J-R curve up to the fusion-line steady-state J value. These results may be more important to LBB analyses than the ASME flaw evaluation procedures, since there is more crack growth with through-wall cracks in LBB analyses than for surface cracks in pipe flaw evaluations.

  14. A process model for the heat-affected zone microstructure evolution in duplex stainless steel weldments: Part II. Application to electron beam welding

    NASA Astrophysics Data System (ADS)

    Hemmer, H.; Grong, Ø.; Klokkehaug, S.

    2000-03-01

    In the present investigation, a process model for electron beam (EB) welding of different grades of duplex stainless steels (i.e. SAF 2205 and 2507) has been developed. A number of attractive features are built into the original finite element code, including (1) a separate module for prediction of the penetration depth and distribution of the heat source into the plate, (2) adaptive refinement of the three-dimensional (3-D) element mesh for quick and reliable solution of the differential heat flow equation, and (3) special subroutines for calculation of the heat-affected zone (HAZ) microstructure evolution. The process model has been validated by comparison with experimental data obtained from in situ thermocouple measurements and optical microscope examinations. Subsequently, its aptness to alloy design and optimization of welding conditions for duplex stainless steels is illustrated in different numerical examples and case studies pertaining to EB welding of tubular joints.

  15. Ultrasonic Spot Welding of a Rare-Earth Containing ZEK100 Magnesium Alloy: Effect of Welding Energy

    NASA Astrophysics Data System (ADS)

    Macwan, A.; Chen, D. L.

    2016-04-01

    Ultrasonic spot welding was used to join a low rare-earth containing ZEK100 Mg alloy at different levels of welding energy, and tensile lap shear tests were conducted to evaluate the failure strength in relation to the microstructural changes. It was observed that dynamic recrystallization occurred in the nugget zone; the grain size increased and microhardness decreased with increasing welding energy arising from the increasing interface temperature and strain rate. The weld interface experienced severe plastic deformation at a high strain rate from ~500 to ~2100 s-1 with increasing welding energy from 500 to 2000 J. A relationship between grain size and Zener-Hollomon parameter, and a Hall-Petch-type relationship between microhardness and grain size were established. The tensile lap shear strength and failure energy were observed to first increase with increasing welding energy, reach the maximum values at 1500 J, and then decrease with a further increase in the welding energy. The samples welded at a welding energy ≤1500 J exhibited an interfacial failure mode, while nugget pull-out occurred in the samples welded at a welding energy above 1500 J. The fracture surfaces showed typical shear failure. Low-temperature tests at 233 K (-40 °C) showed no significant effect on the strength and failure mode of joints welded at the optimal welding energy of 1500 J. Elevated temperature tests at 453 K (180 °C) revealed a lower failure load but a higher failure energy due to the increased deformability, and showed a mixed mode of partial interfacial failure and partial nugget pull-out.

  16. 49 CFR 178.51 - Specification 4BA welded or brazed steel cylinders.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... weldable steel securely attached to the container by fusion welding. (3) Each opening in a cylindrical type... flattened cold, by pressure only, not by blows. When specimens are so taken and prepared, the...

  17. 49 CFR 178.51 - Specification 4BA welded or brazed steel cylinders.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... weldable steel securely attached to the container by fusion welding. (3) Each opening in a cylindrical type... flattened cold, by pressure only, not by blows. When specimens are so taken and prepared, the...

  18. 49 CFR 178.51 - Specification 4BA welded or brazed steel cylinders.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... weldable steel securely attached to the container by fusion welding. (3) Each opening in a cylindrical type... flattened cold, by pressure only, not by blows. When specimens are so taken and prepared, the...

  19. Microstructural characterization of the HAZ in AISI 444 ferritic stainless steel welds

    SciTech Connect

    Silva, Cleiton C. Farias, Jesualdo P.; Miranda, Helio C.; Guimaraes, Rodrigo F.; Menezes, John W.A.; Neto, Moises A.M.

    2008-05-15

    Ferritic stainless steel is used as a coating for equipment in the petroleum refining industry. Welding is the main manufacturing and maintenance process used. However, little information on the metallurgical alterations caused by welding of these steels is found in the literature, prompting this study. In this study the authors evaluated the HAZ microstructure of AISI 444 ferritic stainless steel welded plates, by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results indicated that a weld thermal cycle caused microphase precipitation in the HAZ of the ferritic stainless steel. Also needle-like Laves phase precipitation occurred in the HAZ, near the partially-melted zone. Other secondary phases such as chi and sigma were observed, as well as nitride, carbide and carbonitride precipitates.

  20. 49 CFR 178.47 - Specification 4DS welded stainless steel cylinders for aircraft use.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... must be fusion welded. Seams must be of the butt type and means must be provided for accomplishing complete penetration of the joint. (e) Attachments. Attachments to the container are authorized by fusion... of weldable stainless steel securely attached to the container by fusion welding. (2) Attachments...