Science.gov

Sample records for dissimilar metal welding

  1. Hybrid welding of dissimilar metals

    NASA Astrophysics Data System (ADS)

    Samigullin, A. D.; Bashmakov, D. A.; Israphilov, I. Kh; Turichin, G. A.

    2017-01-01

    The article addresses issues laser - plasma welding (LPW) dissimilar metals and the results of metallographic studies of the microstructure of welds ferrite - 40 steel and molybdenum - steel 40. Increasing potential opportunities the high-energy processing is carried out by integration the laser radiation (LR) and plasma, which allows you to create the desired spatial distribution of the energy flow for technological processes (TP) of laser-plasma heat treatment (LPT) of metals. The distribution of the thermal field is determined by the density distribution of energy flow LR and plasma exposure time, and the thermal characteristics of the treated metal. The most interesting is the treatment of details with ring flow of plasma and LR axial impact.

  2. Welding dissimilar metal microwires by Joule heating

    NASA Astrophysics Data System (ADS)

    Sunagawa, Takuya; Tohmyoh, Hironori

    2015-06-01

    In this paper we report on the Joule heat welding of dissimilar metal microwires. The current required for successful welding was investigated. Various combinations of 25 µm diameter Cu, Au and Al microwires were welded together using this technique. The welded dissimilar metal wire systems were then cut by supplying a higher current, and it was found that the position at which the wires cut was not at the midpoint, i.e., the position of the weld, of the wire system. This is because the temperature distributions formed in the dissimilar metal systems were asymmetrical. The positions at which the wires cut were in good agreement with those predicted by a heat conduction model. The lower limit for successful welding of the dissimilar metal microwire system was found to be determined by the lower of the two currents required to cut microwires of the individual materials.

  3. Femtosecond fiber laser welding of dissimilar metals.

    PubMed

    Huang, Huan; Yang, Lih-Mei; Bai, Shuang; Liu, Jian

    2014-10-01

    In this paper, welding of dissimilar metals was demonstrated for the first time, to the best of our knowledge, by using a high-energy high-repetition-rate femtosecond fiber laser. Metallurgical and mechanical properties were investigated and analyzed under various processing parameters (pulse energy, repetition rate, and welding speed). Results showed that the formation of intermetallic brittle phases and welding defects could be effectively reduced. Strong welding quality with more than 210 MPa tensile strength for stainless steel-aluminum and 175 MPa tensile strength for stainless steel-magnesium has been demonstrated. A minimal heat affected zone and uniform and homogenous phase transformation in the welding region have been demonstrated. This laser-welding technique can be extended for various applications in semiconductor, automobile, aerospace, and biomedical industries.

  4. Joining of Dissimilar Metals By Friction Stir Welding

    NASA Astrophysics Data System (ADS)

    Firouzdor, Vahid

    The use of friction stir welding (FSW) as a new process for joining dissimilar metals has been studied frequently recently. The present study investigated dissimilar-metal FSW between Al and Mg alloys using the widely used alloys 6061 Al and AZ31B Mg. It focused on the issue of how the joint strength is affected by the welding conditions, including the positions of Al and Mg with respect to the welding tool, the tool travel speed and the tool rotation speed. In spite of studies conducted by many other investigators, understanding of this fundamental issue is still rather limited. Unlike those studies, the present study: (1) determined the heat input by torque and temperature measurements during welding and used it to explain the effect of the welding conditions on the joint strength, (2) used color metallography with Al, Mg, Al3Mg2 and Al12Mg17 shown in different colors to clearly revealed the effect of the welding conditions on the formation of intermetallic compounds and material flow, which are affected by the heat input and which in turn affect the joint strength, and (3) determined the windows for selecting the travel and rotation speeds to optimize the joint strength for various material positions. Furthermore, conventional lap FSW was modified and the joint strength and ductility of the resultant welds were both increased significantly. The modified lap FSW was applied subsequently to Al-to-Cu FSW. The intermetallic compounds in Al-Mg and Al-Cu welds were identified.

  5. A study of weld quality in ultrasonic spot welding of similar and dissimilar metals

    NASA Astrophysics Data System (ADS)

    Al-Sarraf, Z.; Lucas, M.

    2012-08-01

    Several difficulties are faced in joining thinner sheets of similar and dissimilar materials from fusion welding processes such as resistance welding and laser welding. Ultrasonic metal welding overcomes many of these difficulties by using high frequency vibration and applied pressure to create a solid-state weld. Ultrasonic metal welding is an effective technique in joining small components, such as in wire bonding, but is also capable of joining thicker sheet, depending on the control of welding conditions. This study presents the design, characterisation and test of a lateral-drive ultrasonic metal welding device. The ultrasonic welding horn is modelled using finite element analysis and its vibration behaviour is characterised experimentally to ensure ultrasonic energy is delivered to the weld coupon. The welding stack and fixtures are then designed and mounted on a test machine to allow a series of experiments to be conducted for various welding and ultrasonic parameters. Weld strength is subsequently analysed using tensile-shear tests. Control of the vibration amplitude profile through the weld cycle is used to enhance weld strength and quality, providing an opportunity to reduce part marking. Optical microscopic examination and scanning electron microscopy (SEM) were employed to investigate the weld quality. The results show how the weld quality is particularly sensitive to the combination of clamping force and vibration amplitude of the welding tip.

  6. Numerical investigation of electromagnetic pulse welded interfaces between dissimilar metals

    SciTech Connect

    Xu, Wei; Sun, Xin

    2016-05-11

    Electromagnetic pulse welding (EMPW), an innovative high-speed joining technique, is a potential method for the automotive industry in joining and assembly of dissimilar lightweight metals with drastically different melting temperatures and other thermal physical properties, such as thermal conductivity and thermal expansion coefficients. The weld quality of EMPW is significantly affected by a variety of interacting physical phenomena including large plastic deformation, materials mixing, localized heating and rapid cooling, possible localized melting and subsequent diffusion and solidification, micro-cracking and void, etc. In the present study, a thermo-mechanically coupled dynamic model has been developed to quantitatively resolve the high-speed impact joining interface characteristics as well as the process-induced interface temperature evolution, defect formation and possible microstructural composition variation. Reasonably good agreement has been obtained between the predicted results and experimental measurements in terms of interfacial morphology characteristics. The modeling framework is expected to provide further understanding of the hierarchical interfacial features of the non-equilibrium material joining process and weld formation mechanisms involved in the EMPW operation, thus accelerating future development and deployment of this advanced joining technology.

  7. Ultrasonic Evaluation of Two Dissimilar Metal Weld Overlay Specimens

    SciTech Connect

    Crawford, Susan L.; Cinson, Anthony D.; Prowant, Matthew S.; Moran, Traci L.; Anderson, Michael T.

    2012-06-30

    Two dissimilar metal weld (DMW) pipe-to-nozzle specimens were implanted with thermal fatigue cracks in the 13% to 90% through-wall depth range. The specimens were ultrasonically evaluated with phased-array probes having center frequencies of 0.8, 1.0, 1.5, and 2.0 megahertz (MHz). An Alloy 82/182 weld overlay (WOL) was applied and the specimens were ultrasonically re-evaluated for flaw detection and characterization. The Post-WOL flaw depths were approximately 10% to 56% through-wall. This study has shown the effectiveness of ultrasonic examinations of Alloy 82/182 overlaid DMW specimens. Phased-array probes with center frequency in the 0.8- to 1.0-MHz range provide a strong coherent signal but the greater ultrasonic wavelength and larger beam spot size prevent the reliable detection of small flaws. These small flaws had nominal through-wall depths of less than 15% and length in the 50-60 mm (2-2.4 in.) range. Flaws in the 19% and greater through-wall depth range were readily detected with all four probes. At the higher frequencies, the reflected signals are less coherent but still provide adequate signal for flaw detection and characterization. A single inspection at 2.0 MHz could provide adequate detection and sizing information but a supplemental inspection at 1.0 or 1.5 MHz is recommended.

  8. Numerical modeling of electron-beam welding of dissimilar metals

    NASA Astrophysics Data System (ADS)

    Krektuleva, R. A.; Cherepanov, O. I.; Cherepanov, R. O.

    2016-11-01

    This paper is devoted to numerical modeling of heat transfer processes and estimation of thermal stresses in weld seams created by electron beam welding of heterogeneous metals. The mathematical model is based on a system of equations that includes the Lagrange's variational equation of theory of plasticity and variational equation of M. Biot's principle to simulate the heat transfer processes. The two-dimensional problems (plane strain and plane stress) are considered for estimation of thermal stresses in welds considering differences of mechanical properties of welded materials. The model is developed for simulation of temperature fields and stresses during electron beam welding.

  9. Hydrogen-induced cracking along the fusion boundary of dissimilar metal welds

    SciTech Connect

    Rowe, M.D.; Nelson, T.W.; Lippold, J.C.

    1999-02-01

    Presented here are the results from a series of experiments in which dissimilar metals welds were made using the gas tungsten arc welding process with pure argon or argon-6% hydrogen shielding gas. The objective was to determine if cracking near the fusion boundary of dissimilar metal welds could be caused by hydrogen absorbed during welding and to characterize the microstructures in which cracking occurred. Welds consisted of ER308 and ER309LSi austenitic stainless steel and ERNiCr-3-nickel-based filler metals deposited on A36 steel base metal. Cracking was observed in welds made with all three filler metals. A ferrofluid color metallography technique revealed that cracking was confined to regions in the weld metal containing martensite. Microhardness indentations indicated that martensitic regions in which cracking occurred had hardness values from 400 to 550 HV. Cracks did not extend into bulk weld metal with hardness less than 350 HV. Martensite formed near the fusion boundary in all three filler metals due to regions of locally increased base metal dilution.

  10. Optimization of Laser Keyhole Welding Strategies of Dissimilar Metals by FEM Simulation

    NASA Astrophysics Data System (ADS)

    Garcia Navas, Virginia; Leunda, Josu; Lambarri, Jon; Sanz, Carmen

    2015-07-01

    Laser keyhole welding of dissimilar metals has been simulated to study the effect of welding strategies (laser beam displacements and tilts) and combination of metals to be welded on final quality of the joints. Molten pool geometry and welding penetration have been studied but special attention has been paid to final joint material properties, such as microstructure/phases and hardness, and especially to the residual stress state because it greatly conditions the service life of laser-welded components. For a fixed strategy (laser beam perpendicular to the joint) austenitic to carbon steel laser welding leads to residual stresses at the joint area very similar to those obtained in austenitic to martensitic steel welding, but welding of steel to Inconel 718 results in steeper residual stress gradients and higher area at the joint with detrimental tensile stresses. Therefore, when the difference in thermo-mechanical properties of the metals to be welded is higher, the stress state generated is more detrimental for the service life of the component, and consequently more relevant is the optimization of welding strategy. In laser keyhole welding of austenitic to martensitic stainless steel and austenitic to carbon steel, the optimum welding strategy is displacing the laser beam 1 mm toward the austenitic steel. In the case of austenitic steel to Inconel welding, the optimum welding strategy consists in setting the heat source tilted 45 deg and moved 2 mm toward the austenitic steel.

  11. Precipitation of Niobium Boride Phases at the Base Metal/Weld Metal Interface in Dissimilar Weld Joints

    NASA Astrophysics Data System (ADS)

    Výrostková, Anna; Kepič, Ján; Homolová, Viera; Falat, Ladislav

    2015-07-01

    In this work, the analysis of failure mechanism in the heat affected zone is described in dissimilar weld joints between advanced martensitic steel T92 and Ni-base weld metal. The joints were treated with two different post-weld heat treatments and tested. For the creep, tensile, and Charpy impact tests, the samples with interfacially located notch were used. Moreover long term aging at 625 °C was applied before the tensile and notch toughness tests. Decohesion fractures ran along carbides at the T92 BM/WM interfaces in case of the modified PWHT, whereas type IV cracking was the prevailing failure mechanism after the classical PWHT in the creep test. In the notch tensile and Charpy impact tests, with the notch at T92 base metal/weld metal interface, fractures ran along the interface with a hard phase on the fracture surface along with the ductile dimple and brittle quasi-cleavage fracture. The phase identified as niobium boride (either NbB and/or Nb3B2) was produced during welding at the end of the solidification process. It was found in the welds regardless of the post-weld heat treatment and long-term aging.

  12. Hydrogen Assisted Crack in Dissimilar Metal Welds for Subsea Service under Cathodic Protection

    NASA Astrophysics Data System (ADS)

    Bourgeois, Desmond

    Dissimilar metal welds (DMWs) are routinely used in the oil and gas industries for structural joining of high strength steels in order to eliminate the need for post weld heat treatment (PWHT) after field welding. There have been reported catastrophic failures in these DMWs, particularly the AISI 8630 steel - Alloy 625 DMW combination, during subsea service while under cathodic protection (CP). This is due to local embrittlement that occurs in susceptible microstructures that are present at the weld fusion boundary region. This type of cracking is known as hydrogen assisted cracking (HAC) and it is influenced by base/filler metal combination, and welding and PWHT procedures. DMWs of two material combinations (8630 steel -- Alloy 625 and F22 steel -- Alloy 625), produced with two welding procedures (BS1 and BS3) in as welded and PWHT conditions were investigated in this study. The main objectives included: 1) evaluation of the effect of materials composition, welding and PWHT procedures on the gradients of composition, microstructure, and properties in the dissimilar transition region and on the susceptibility to HAC; 2) investigation of the influence of microstructure on the HAC failure mechanism and identification of microstructural constituents acting as crack nucleation and propagation sites; 3) assessment of the applicability of two-step PWHT to improve the resistance to HAC in DMWs; 4) establishment of non-failure criterion for the delayed hydrogen cracking test (DHCT) that is applicable for qualification of DMWs for subsea service under cathodic protection (CP).

  13. Investigation of dissimilar metal welds by energy-resolved neutron imaging.

    PubMed

    Tremsin, Anton S; Ganguly, Supriyo; Meco, Sonia M; Pardal, Goncalo R; Shinohara, Takenao; Feller, W Bruce

    2016-08-01

    A nondestructive study of the internal structure and compositional gradient of dissimilar metal-alloy welds through energy-resolved neutron imaging is described in this paper. The ability of neutrons to penetrate thick metal objects (up to several cm) provides a unique possibility to examine samples which are opaque to other conventional techniques. The presence of Bragg edges in the measured neutron transmission spectra can be used to characterize the internal residual strain within the samples and some microstructural features, e.g. texture within the grains, while neutron resonance absorption provides the possibility to map the degree of uniformity in mixing of the participating alloys and intermetallic formation within the welds. In addition, voids and other defects can be revealed by the variation of neutron attenuation across the samples. This paper demonstrates the potential of neutron energy-resolved imaging to measure all these characteristics simultaneously in a single experiment with sub-mm spatial resolution. Two dissimilar alloy welds are used in this study: Al autogenously laser welded to steel, and Ti gas metal arc welded (GMAW) to stainless steel using Cu as a filler alloy. The cold metal transfer variant of the GMAW process was used in joining the Ti to the stainless steel in order to minimize the heat input. The distributions of the lattice parameter and texture variation in these welds as well as the presence of voids and defects in the melt region are mapped across the welds. The depth of the thermal front in the Al-steel weld is clearly resolved and could be used to optimize the welding process. A highly textured structure is revealed in the Ti to stainless steel joint where copper was used as a filler wire. The limited diffusion of Ti into the weld region is also verified by the resonance absorption.

  14. Investigation of dissimilar metal welds by energy-resolved neutron imaging

    PubMed Central

    Tremsin, Anton S.; Ganguly, Supriyo; Meco, Sonia M.; Pardal, Goncalo R.; Shinohara, Takenao; Feller, W. Bruce

    2016-01-01

    A nondestructive study of the internal structure and compositional gradient of dissimilar metal-alloy welds through energy-resolved neutron imaging is described in this paper. The ability of neutrons to penetrate thick metal objects (up to several cm) provides a unique possibility to examine samples which are opaque to other conventional techniques. The presence of Bragg edges in the measured neutron transmission spectra can be used to characterize the internal residual strain within the samples and some microstructural features, e.g. texture within the grains, while neutron resonance absorption provides the possibility to map the degree of uniformity in mixing of the participating alloys and intermetallic formation within the welds. In addition, voids and other defects can be revealed by the variation of neutron attenuation across the samples. This paper demonstrates the potential of neutron energy-resolved imaging to measure all these characteristics simultaneously in a single experiment with sub-mm spatial resolution. Two dissimilar alloy welds are used in this study: Al autogenously laser welded to steel, and Ti gas metal arc welded (GMAW) to stainless steel using Cu as a filler alloy. The cold metal transfer variant of the GMAW process was used in joining the Ti to the stainless steel in order to minimize the heat input. The distributions of the lattice parameter and texture variation in these welds as well as the presence of voids and defects in the melt region are mapped across the welds. The depth of the thermal front in the Al–steel weld is clearly resolved and could be used to optimize the welding process. A highly textured structure is revealed in the Ti to stainless steel joint where copper was used as a filler wire. The limited diffusion of Ti into the weld region is also verified by the resonance absorption. PMID:27504075

  15. Effect of Shoulder Size on Weld Properties of Dissimilar Metal Friction Stir Welds

    NASA Astrophysics Data System (ADS)

    Akinlabi, E. T.

    2012-07-01

    This article reports a research study that shows the effect of shoulder diameter size on the resulting weld properties of dissimilar friction stir welds between 5754 aluminum alloy (AA) and C11000 copper (Cu). Welds were produced using three different shoulder diameter tools: 15, 18, and 25 mm by varying the rotational speed between 600 and 1200 rpm and the traverse speed between 50 and 300 mm/min to achieve the best result. Each parameter combination was chosen to represent different heat input conditions (low, intermediates and high). The welds were characterized through microstructural evaluation, tensile testing, microhardness measurements, x-ray diffraction analysis, and electrical resistivity. Microstructural evaluation of the welds revealed that the welds produced consisted of all the friction stir welding (FSW) microstructure zones with organized flow lines comprising mixture layers of aluminum (Al) and copper (Cu) at the Stir Zones. The average Ultimate Tensile Strength (UTS) of the welds considered ranged from 178 to 208 MPa. Higher Vickers microhardness values were measured at the joint interfaces of all the welds because of the presence of intermetallic compounds in these regions. The x-ray diffraction analysis revealed the presence of Al4Cu9 and Al2Cu intermetallics at the interfacial regions, and low electrical resistivities were obtained at the joint interfaces. An optimized parameter setting for FSW of Al and Cu was obtained at the weld produced at 950 rpm and 50 mm/min with the 18-mm shoulder diameter tool.

  16. Ultrasonic Phased Array Technique for Accurate Flaw Sizing in Dissimilar Metal Welds

    SciTech Connect

    Jonathan D Buttram

    2005-03-11

    Described is a manual,portable non-destructive technique to determine the through wall height of cracks present in dissimilar metal welds used in the primary coolling systems of pressure water and boiler light water reactors. Current manual methods found in industry have proven not to exhibit the sizing accuracy required by ASME inspection requirement. The technique described demonstrated an accuracy approximately three times that required to ASME Section XI, Appendix 8 qualification.

  17. Resistance Spot Welding of AA5052 Sheet Metal of Dissimilar Thickness

    NASA Astrophysics Data System (ADS)

    Mat Din, N. A.; Zuhailawati, H.; Anasyida, A. S.

    2016-02-01

    Resistance spot welding of dissimilar thickness of AA5052 aluminum alloy was performed in order to investigate the effect of metal thickness on the weldment strength. Resistance spot welding was done using a spot welder machine available in Coraza Systems Sdn Bhd using a hemispherical of chromium copper electrode tip with radius of 6.00 mm under 14 kA of current and 0.02 bar of pressure for all thickness combinations. Lap joint configuration was produced between 2.0 mm thick sheet and 1.2 - 3.2 mm thick sheet, respectively. Microstructure of joint showed asymmetrical nugget shape that was larger on the thicker side indicating larger molten metal volume. Joint 2.0 mm x 3.2 mm sheets has the lowest hardness in both transverse direction and through thickness direction because less heat left in the weld nugget. The microstructure shows that this joint has coarse grains of HAZ. As thickness of sheet metal increased, the failure load of the joints increased. However, there was no linear correlation established between joint strength and metal thickness due to different shape of fusion zone in dissimilar thickness sheet metal.

  18. Phased array ultrasonic testing of dissimilar metal welds using geometric based referencing delay law technique

    NASA Astrophysics Data System (ADS)

    Han, Taeyoung; Schubert, Frank; Hillmann, Susanne; Meyendorf, Norbert

    2015-03-01

    Phased array ultrasonic testing (PAUT) techniques are widely used for the non-destructive testing (NDT) of austenitic welds to find defects like cracks. However, the propagation of ultrasound waves through the austenitic material is intricate due to its inhomogeneous and anisotropic nature. Such a characteristic leads beam path distorted which causes the signal to be misinterpreted. By employing a reference block which is cutout from the mockup of which the structure is a dissimilar metal weld (DMW), a new method of PAUT named as Referencing Delay Law Technique (RDLT) is introduced. With the RDLT, full matrix capture (FMC) was used for data acquisition. To reconstruct the images, total focusing method (TFM) was used. After the focal laws were calculated, PAUT was then performed. As a result, the flaws are more precisely positioned with significantly increased signal-to-noise ratio (SNR).

  19. Influence of tool speeds on dissimilar friction stir spot welding characteristics of bulk metallic glass/Mg alloy

    NASA Astrophysics Data System (ADS)

    Shin, Hyung-Seop; Jung, Yoon-Chul; Lee, Jin-Kyu

    2012-08-01

    A small-scale joining technique of dissimilar friction stir spot welding (FSSW) between bulk metallic glass and Mg alloy sheet has been tried using an apparatus which was devised with a CNC milling machine to give a precise control of tool speeds. The influence of tool speeds on the joining characteristics during FSSW was investigated. As a result, it was found that the rotation speed and plunge speed of a tool during FSSW significantly influenced the welding performance of dissimilar FSSW between bulk metallic glasses and Mg alloy.

  20. Evaluation of joint interface of friction stir welding between dissimilar metals using HTS-SQUID gradiometer

    NASA Astrophysics Data System (ADS)

    Mashiko, Y.; Hatsukade, Y.; Yasui, T.; Takenaka, H.; Todaka, Y.; Fukumoto, M.; Tanaka, S.

    2010-11-01

    In this study, we investigated conductive properties of joint interfaces of friction stir welding (FSW) between dissimilar metals, stainless steel SUS304 and aluminum A6063, using a SQUID nondestructive evaluation (NDE) system. With current injection method, the current maps above the FSW specimens jointed under various conditions were measured by a HTS-SQUID gradiometer. The conductivities of the joint interfaces, which were estimated from the current maps, differed between the joint conditions. By destructive tests using optical microscope, large voids were observed on the joint interfaces with low welding speed that generated excess heating. In case of one specimen, which was welded with welding speed of 500 and 200 mm/min, the conductivity of the former was higher than that of the latter, although the inside voids in the respective regions were not much different. From these results, it is suggested that the current maps were influenced not only by the conductivity of the joint interface but also by inside voids. By hardness test on the SUS boards near the interfaces, only the SUS jointed with 200 mm/min was about half softer than its matrix.

  1. Friction Buttering: A New Technique for Dissimilar Welding

    NASA Astrophysics Data System (ADS)

    Karthik, G. M.; Mastanaiah, P.; Janaki Ram, G. D.; Kottada, Ravi Sankar

    2017-02-01

    This work offers a fresh perspective on buttering, a technique often considered for fusion welding of dissimilar metals. For the first time, buttering was attempted in solid state using friction deposition. Using this new "friction buttering" technique, fusion welding of two different dissimilar metal pairs (austenitic stainless steel/borated stainless steel and Al-Cu-Mg/Al-Zn-Mg-Cu) was successfully demonstrated. The results show that friction buttering can simplify a tough dissimilar welding problem into a routine fusion welding task.

  2. Review on electromagnetic welding of dissimilar materials

    NASA Astrophysics Data System (ADS)

    Shanthala, K.; Sreenivasa, T. N.

    2016-12-01

    Electromagnetic welding (EMW) is a highspeed joining technique that is used to join similar or dissimilar metals, as well as metals to non-metals. This technique uses electromagnetic force to mainly join conductive materials. Unlike conventional joining processes, the weld interface does not melt, thus keeping the material properties intact. Extremely high velocity and strain rate involved in the process facilitate extending the EMW technique for joining several materials. In this paper, the research and progress in electromagnetic welding are reviewed from various perspectives to provide a basis for further research.

  3. Review of Dissimilar Metal Welding for the NGNP Helical-Coil Steam Generator

    SciTech Connect

    John N. DuPont

    2010-03-01

    The U.S. Department of Energy (DOE) is currently funding research and development of a new high temperature gas cooled reactor (HTGR) that is capable of providing high temperature process heat for industry. The steam generator of the HTGR will consist of an evaporator economizer section in the lower portion and a finishing superheater section in the upper portion. Alloy 800H is expected to be used for the superheater section, and 2.25Cr 1Mo steel is expected to be used for the evaporator economizer section. Dissimilar metal welds (DMW) will be needed to join these two materials. It is well known that failure of DMWs can occur well below the expected creep life of either base metal and well below the design life of the plant. The failure time depends on a wide range of factors related to service conditions, welding parameters, and alloys involved in the DMW. The overall objective of this report is to review factors associated with premature failure of DMWs operating at elevated temperatures and identify methods for extending the life of the 2.25Cr 1Mo steel to alloy 800H welds required in the new HTGR. Information is provided on a variety of topics pertinent to DMW failures, including microstructural evolution, failure mechanisms, creep rupture properties, aging behavior, remaining life estimation techniques, effect of environment on creep rupture properties, best practices, and research in progress to improve DMW performance. The microstructure of DMWs in the as welded condition consists of a sharp chemical concentration gradient across the fusion line that separates the ferritic and austenitic alloys. Upon cooling from the weld thermal cycle, a band of martensite forms within this concentration gradient due to high hardenability and the relatively rapid cooling rates associated with welding. Upon aging, during post weld heat treatment (PWHT), and/or during high temperature service, C diffuses down the chemical potential gradient from the ferritic 2.25Cr 1Mo steel

  4. 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.

  5. Dissimilar metals joint evaluation

    NASA Technical Reports Server (NTRS)

    Wakefield, M. E.; Apodaca, L. E.

    1974-01-01

    Dissimilar metals tubular joints between 2219-T851 aluminum alloy and 304L stainless steel were fabricated and tested to evaluate bonding processes. Joints were fabricated by four processes: (1) inertia (friction) weldings, where the metals are spun and forced together to create the weld; (2) explosive welding, where the metals are impacted together at high velocity; (3) co-extrusion, where the metals are extruded in contact at high temperature to promote diffusion; and (4) swaging, where residual stresses in the metals after a stretching operation maintain forced contact in mutual shear areas. Fifteen joints of each type were prepared and evaluated in a 6.35 cm (2.50 in.) O.D. size, with 0.32 cm (0.13 in.) wall thickness, and 7.6 cm (3.0 in) total length. The joints were tested to evaluate their ability to withstand pressure cycle, thermal cycle, galvanic corrosion and burst tests. Leakage tests and other non-destructive test techniques were used to evaluate the behavior of the joints, and the microstructure of the bond areas was analyzed.

  6. A residual stress study in similar and dissimilar welds

    SciTech Connect

    Eisazadeh, Hamid; Goldak, John A.; Aidun, Daryush K.; Coules, Harry E.; Bunn, Jeffrey R; Achuthan, A.

    2016-04-01

    Residual strain distributions in similar and dissimilar welds were measured using neutron diffraction (ND) method. Then, using three strain components, three-dimensional stress states were calculated. The results were used to determine the effect of the martensitic phase transformation and material properties on residual stress (RS) distribution. It was observed that smaller longitudinal RS was induced in the low carbon steel side of dissimilar weld when compared to its similar weld. Also, it was found that the transverse RS near and within the weld zone (WZ) in dissimilar weld exhibited a distinctive trend, with tensile mode reaching the yield strength of the base metal (BM). In order to characterize the WZ in dissimilar weld, we deployed optical microscopy, hardness, and energy dispersive X-ray spectroscopy (EDAX). This study not only provides further insight into the RS state in similar and dissimilar welds; it also delivers important consequences of phase transformation in the latter case.

  7. A residual stress study in similar and dissimilar welds

    DOE PAGES

    Eisazadeh, Hamid; Goldak, John A.; Aidun, Daryush K.; ...

    2016-04-01

    Residual strain distributions in similar and dissimilar welds were measured using neutron diffraction (ND) method. Then, using three strain components, three-dimensional stress states were calculated. The results were used to determine the effect of the martensitic phase transformation and material properties on residual stress (RS) distribution. It was observed that smaller longitudinal RS was induced in the low carbon steel side of dissimilar weld when compared to its similar weld. Also, it was found that the transverse RS near and within the weld zone (WZ) in dissimilar weld exhibited a distinctive trend, with tensile mode reaching the yield strength ofmore » the base metal (BM). In order to characterize the WZ in dissimilar weld, we deployed optical microscopy, hardness, and energy dispersive X-ray spectroscopy (EDAX). This study not only provides further insight into the RS state in similar and dissimilar welds; it also delivers important consequences of phase transformation in the latter case.« less

  8. Welding for testability: An approach aimed at improving the ultrasonic testing of thick-walled austenitic and dissimilar metal welds

    SciTech Connect

    Wagner, Sabine; Dugan, Sandra; Barth, Martin; Schubert, Frank; Köhler, Bernd

    2014-02-18

    Austenitic and dissimilar welds in thick walled components show a coarse grained, dendritic microstructure. Therefore, ultrasonic testing has to deal with beam refraction, scattering and mode conversion effects. As a result, the testing techniques typically applied for isotropic materials yield dissatisfying results. Most approaches for improvement of ultrasonic testing have been based on modeling and improved knowledge of the complex wave propagation phenomena. In this paper, we discuss an alternative approach: is it possible to use a modified welding technology which eliminates the cause of the UT complications, i.e. the large-grained structure of the weld seams? Various modification parameters were tested, including: TIG current pulsing, additional DC and AC magnetic fields, and also additional external vibrations during welding. For all welds produced under different conditions, the grain structure of the weld seam was characterized by optical and GIUM microstructure visualizations on cross sections, wave field propagation measurements, and ultrasonic tests of correct detectability of flaws. The mechanical properties of the welds were also tested.

  9. Evaluation of Manual Ultrasonic Examinations Applied to Detect Flaws in Primary System Dissimilar Metal Welds at North Anna Power Station

    SciTech Connect

    Anderson, Michael T.; Diaz, Aaron A.; Doctor, Steven R.

    2012-06-01

    During a recent inservice inspection (ISI) of a dissimilar metal weld (DMW) in an inlet (hot leg) steam generator nozzle at North Anna Power Station Unit 1, several axially oriented flaws went undetected by the licensee's manual ultrasonic testing (UT) technique. The flaws were subsequently detected as a result of outside diameter (OD) surface machining in preparation for a full structural weld overlay. The machining operation uncovered the existence of two through-wall flaws, based on the observance of primary water leaking from the DMW. Further ultrasonic tests were then performed, and a total of five axially oriented flaws, classified as primary water stress corrosion cracking (PWSCC), were detected in varied locations around the weld circumference.

  10. Nature and evolution of the fusion boundary in ferritic-austenitic dissimilar weld metals. Part 1 -- Nucleation and growth

    SciTech Connect

    Nelson, T.W.; Lippold, J.C.; Mills, M.J.

    1999-10-01

    A fundamental investigation of fusion boundary microstructure evolution in dissimilar-metal welds (DMWs) between ferritic base metals and a face-centered-cubic (FCC) filler metal was conducted. The objective of the work presented here was to characterize the nature and character of the elevated-temperature fusion boundary to determine the nucleation and growth characteristics of DMWs. Type 409 ferritic stainless steel and 1080 pearlitic steel were utilized as base metal substrates, and Monel (70Ni-30Cu) was used as the filler metal. The Type 409 base metal provided a fully ferritic or body-centered-cubic (BCC) substrate at elevated temperatures and exhibited no on-cooling phase transformations to mask or disguise the original character of the fusion boundary. The 1080 pearlitic steel was selected because it is austenitic at the solidus temperature, providing an austenite substrate at the fusion boundary. The weld microstructure generated with each of the base metals in combination with Monel was fully austenitic. In the Type 409/Monel system, there was no evidence of epitaxial nucleation and growth as normally observed in homogeneous weld metal combinations. The fusion boundary in this system exhibited random grain boundary misorientations between the heat-affected zone (HAZ) and weld metal grains. In the 1080/Monel system, evidence of normal epitaxial growth was observed at the fusion boundary, where solidification and HAZ grain boundaries converged. The fusion boundary morphologies are a result of the crystal structure present along the fusion boundary during the initial stages of solidification. Based on the results of this investigation, a model for heterogeneous nucleation along the fusion boundary is proposed when the base and weld metals exhibit ferritic (BCC) and FCC crystal structures, respectively.

  11. Analysis of a Defected Dissimilar Metal Weld in a PWR Power Plant

    SciTech Connect

    Efsing, P.; Lagerstrom, J.

    2002-07-01

    During the refueling outage 2000, inspections of the RC-loops of one of the Ringhals PWR-units, Ringhals 4, indicated surface breaking defects in the axial direction of the piping in a dissimilar weld between the Low alloy steel nozzle and the stainless safe end in the hot leg. In addition some indications were found that there were embedded defects in the weld material. These defects were judged as being insignificant to the structural integrity. The welds were inspected in 1993 with the result that no significant indications were found. The weld it self is a double U weld, where the thickness of the material is ideally 79,5 mm. Its is constructed by Inconel 182 weld material. At the nozzle a buttering was applied, also by Inconel 182. The In-service inspection, ISI, of the object indicated four axial defects, 9-16 mm deep. During fabrication, the areas where the defects are found were repaired at least three times, onto a maximum depth of 32 mm. To evaluate the defects, 6 boat samples from the four axial defects were cut from the perimeter and shipped to the hot-cell laboratory for further examination. This examination revealed that the two deep defects had been under sized by the ISI outside the requirement set by the inspection tolerances, while the two shallow defects were over sized, but within the tolerances of the detection system. When studying the safety case it became evident that there were several missing elements in the way this problems is handled with respect to the Swedish safety evaluation code. Among these the most notable at the beginning was the absence of reliable fracture mechanical data such as crack growth laws and fracture toughness at elevated temperature. Both these questions were handled by the project. The fracture mechanical evaluation has focused on a fit for service principal. Thus defects both in the unaffected zones and the disturbed zones, boat sample cutouts, of the weld have been analyzed. With reference to the Swedish safety

  12. Stress Corrosion Cracking and Non-Destructive Examination of Dissimilar Metal Welds and Alloy 600

    SciTech Connect

    Jackson, Deborah A.

    2002-07-01

    The United States Nuclear Regulatory Commission (USNRC) has conducted research since 1977 in the areas of environmentally assisted cracking and assessment and reliability of non-destructive examination (NDE). Recent occurrences of cracking in Alloy 82/182 welds and Alloy 600 base metal at several domestic and overseas plants have raised several issues relating to both of these areas of NRC research. The occurrences of cracking were identified by the discovery of boric acid deposits resulting from through-wall cracking in the primary system pressure boundary. Analyses indicate that the cracking has occurred due to primary water stress corrosion cracking (PWSCC) in Alloy 82/182 welds. This cracking has occurred in two different locations: in hot leg nozzle-to-safe end welds and in control rod drive mechanism (CRDM) nozzle welds. The cracking associated with safe-end welds is important due to the potential for a large loss of reactor coolant inventory, and the cracking of CRDM nozzle base metal and welds, particularly circumferential cracking of CRDM nozzle base metal, is important due to the potential for a control rod to eject resulting in a loss of coolant accident. The industry response in the U.S. to this cracking is being coordinated through the Electric Power Research Institute's Materials Reliability Project (EPRI-MRP) in a comprehensive, multifaceted effort. Although the industry program is addressing many of the issues raised by these cracking occurrences, confirmatory research is necessary for the staff to evaluate the work conducted by industry groups. Several issues requiring additional consideration regarding the generic implications of these isolated events have been identified. This paper will discuss the recent events of significant cracking in domestic and foreign plants, discuss the limitations of NDE in detecting SCC, identify deficiencies in information available in this area, discuss the USNRC approach to address these issues, and discuss the

  13. The electron beam welding of dissimilar materials - case study

    NASA Astrophysics Data System (ADS)

    Munteanu, A.

    2016-11-01

    The modalities to realize the welding workpieces are multiple. The electron beam welding is one of them. One can weld two different types of materials that give the possibility to reduce the cost of workpiece, if the active part is realised of rich materials welded on components with inferior phisico-mecanical characteristics. The procedure provides great flexibility to the product designs through efficient use of each type of material. So this aspects lead to the necessity to join dissimilar metals. Different tables are given in the specific literature regarding the possible combination. Conflicts may arise by the compromises required for to the optimum heat control of the two dissimilar materials used. But nowadays, more and more frequently are meet the welding of dissimilar metals, thus, the objective of this article is to provide information regarding the particular case of welding between stainless steel and copper without the filler material use.

  14. Summary of Dissimilar Metal Joining Trials Conducted by Edison Welding Institute

    SciTech Connect

    MJ Lambert

    2005-11-18

    Under the direction of the NASA-Glenn Research Center, the Edison Welding Institute (EWI) in Columbus, OH performed a series of non-fusion joining experiments to determine the feasibility of joining refractory metals or refractory metal alloys to Ni-based superalloys. Results, as reported by EWI, can be found in the project report for EWI Project 48819GTH (Attachment A, at the end of this document), dated October 10, 2005. The three joining methods used in this investigation were inertia welding, magnetic pulse welding, and electro-spark deposition joining. Five materials were used in these experiments: Mo-47Re, T-111, Hastelloy X, Mar M-247 (coarse-grained, 0.5 mm to several millimeter average grain size), and Mar M-247 (fine-grained, approximately 50 {micro}m average grain size). Several iterative trials of each material combination with each joining method were performed to determine the best practice joining method. Mo-47Re was found to be joined easily to Hastelloy X via inertia welding, but inertia welding of the Mo-alloy to both Mar M-247 alloys resulted in inconsistent joint strength and large reaction layers between the two metals. T-111 was found to join well to Hastelloy X and coarse-grained Mar M-247 via inertia welding, but joining to fine-grained Mar M-247 resulted in low joint strength. Magnetic pulse welding (MPW) was only successful in joining T-111 tubing to Hastelloy X bar stock. The joint integrity and reaction layer between the metals were found to be acceptable. This single joining trial, however, caused damage to the electromagnetic concentrators used in this process. Subsequent design efforts to eliminate the problem resulted in a loss of power imparted to the accelerating work piece, and results could not be reproduced. Welding trials of Mar M-247 to T-111 resulted in catastrophic failure of the bar stock, even at lower power. Electro-spark deposition joining of Mo-47Re, in which the deposited material was Hastelloy X, did not have a

  15. Phased Array Ultrasonic Examination of Reactor Coolant System (Carbon Steel-to-CASS) Dissimilar Metal Weld Mockup Specimen

    SciTech Connect

    Crawford, S. L.; Cinson, A. D.; Diaz, A. A.; Anderson, M. T.

    2015-11-23

    In the summer of 2009, Pacific Northwest National Laboratory (PNNL) staff traveled to the Electric Power Research Institute (EPRI) NDE Center in Charlotte, North Carolina, to conduct phased-array ultrasonic testing on a large bore, reactor coolant pump nozzle-to-safe-end mockup. This mockup was fabricated by FlawTech, Inc. and the configuration originated from the Port St. Lucie nuclear power plant. These plants are Combustion Engineering-designed reactors. This mockup consists of a carbon steel elbow with stainless steel cladding joined to a cast austenitic stainless steel (CASS) safe-end with a dissimilar metal weld and is owned by Florida Power & Light. The objective of this study, and the data acquisition exercise held at the EPRI NDE Center, were focused on evaluating the capabilities of advanced, low-frequency phased-array ultrasonic testing (PA-UT) examination techniques for detection and characterization of implanted circumferential flaws and machined reflectors in a thick-section CASS dissimilar metal weld component. This work was limited to PA-UT assessments using 500 kHz and 800 kHz probes on circumferential flaws only, and evaluated detection and characterization of these flaws and machined reflectors from the CASS safe-end side only. All data were obtained using spatially encoded, manual scanning techniques. The effects of such factors as line-scan versus raster-scan examination approaches were evaluated, and PA-UT detection and characterization performance as a function of inspection frequency/wavelength, were also assessed. A comparative assessment of the data is provided, using length-sizing root-mean-square-error and position/localization results (flaw start/stop information) as the key criteria for flaw characterization performance. In addition, flaw signal-to-noise ratio was identified as the key criterion for detection performance.

  16. Effects of aging temperature on microstructural evolution at dissimilar metal weld interfaces

    NASA Astrophysics Data System (ADS)

    Choi, Kyoung Joon; Yoo, Seung Chang; Kim, Taeho; Bahn, Chi Bum; Kim, Ji Hyun

    2015-07-01

    From the earlier study which characterized the region of a fusion boundary between a low-alloy steel (LAS) and a Ni-based weld metal of as-welded and aged samples at 450 °C for a 30-y-equivalent time, it was observed in the microstructure that the aging treatment induced the formation and growth of Cr precipitates in the fusion boundary region because of the thermodynamic driving force. Now, this research extends the text matrix and continues the previous study by compiling all the test data, with an additional aging heat treatment conducted at 400 °C for 15- and 30-y-equivalent times (6450 and 12,911 h, respectively). The results for the extended test matrix primarily represent the common features of and disparities in the effects of thermal aging on the aged samples at two different heat-treatment temperatures (400 and 450 °C). Although no difference was expected between the samples, because the heat treatment conditions simulate thermal aging effects during the same service time of 30 y, the sample aged at 450 °C exhibited slightly more severe effects of thermal aging than the sample aged at 400 °C. Nevertheless, the trends for these effects are similar and the simulation of thermal aging effects for a light-water reactor appears to be reliable. However, according to a simulation of the same degree of thermal aging effects, it appears that the activation energy for Cr diffusion should be larger than the numerical value used in this study.

  17. Developing a dissimilar metal foil-to-substrate resistance welding process.

    SciTech Connect

    Knorovsky, Gerald Albert

    2010-10-01

    Materials changes occurring upon redesign caused redevelopment of the multiple spot resistance weld procedure employed to join a 23 micrometer thick foil of 15-7PH to a thick substrate and (at a separate location) a second, smaller thermal mass substrate. Both substrates were 304L. To avoid foil wrinkling, minimal heat input was used. The foil/thick substrate weld was solid-state, though the foil/small substrate weld was not. Metallographic evidence indicated occasional separation of the solid-state weld, hence a fusion weld was desired at both locations. In the redesign, a Co-Cr-Fe-Ni alloy was substituted for the foil, and a Ni-Cr-Mo alloy was evaluated for the small substrate. Both materials are substantially more resistive than their predecessors. This study reports development of weld schedules to accommodate the changes, yet achieve the fusion weld goal. Thermal analysis was employed to understand the effects caused by the various weld schedule parameters, and guide their optimization.

  18. Friction stir welding tool and process for welding dissimilar materials

    DOEpatents

    Hovanski, Yuri; Grant, Glenn J; Jana, Saumyadeep; Mattlin, Karl F

    2013-05-07

    A friction stir welding tool and process for lap welding dissimilar materials are detailed. The invention includes a cutter scribe that penetrates and extrudes a first material of a lap weld stack to a preselected depth and further cuts a second material to provide a beneficial geometry defined by a plurality of mechanically interlocking features. The tool backfills the interlocking features generating a lap weld across the length of the interface between the dissimilar materials that enhances the shear strength of the lap weld.

  19. Effect of Welding Current on the Structure and Properties of Resistance Spot Welded Dissimilar (Austenitic Stainless Steel and Low Carbon Steel) Metal Joints

    NASA Astrophysics Data System (ADS)

    Shawon, M. R. A.; Gulshan, F.; Kurny, A. S. W.

    2015-04-01

    1.5 mm thick sheet metal coupons of austenitic stainless steel and plain low carbon steel were welded by resistance spot welding technique. The effects of welding current in the range 3-9 kA on the structure and mechanical properties of welded joint were investigated. The structure was studied by macroscopic, microscopic and scanning electron microscopy techniques. Mechanical properties were determined by tensile testing and microhardness measurements. Asymmetrical shape weld nugget was found to have formed in the welded joint which increased in size with an increase in welding current. The fusion zone showed cast structure with coarse columnar grain and dendritic with excess delta ferrite in austenitic matrix. Microhardness of the weld nugget was maximum because of martensite formation. An increase in welding current also increased tensile strength of the weld coupon. An attempt has also been made to relate the mode of fracture with the welding current.

  20. Dynamic Strength Evaluations for Self-Piercing Rivets and Resistance Spot Welds Joining Similar and Dissimilar Metals

    SciTech Connect

    Sun, Xin; Khaleel, Mohammad A.

    2007-10-01

    This paper summarizes the dynamic joint strength evaluation procedures and the measured dynamic strength data for thirteen joint populations of self-piercing rivets (SPR) and resistance spot welds (RSW) joining similar and dissimilar metals. A state-of-the-art review of the current practice for conducting dynamic tensile/compressive strength tests in different strain rate regimes is first presented, and the generic issues associated with dynamic strength test are addressed. Then, the joint strength testing procedures and fixture designs used in the current study are described, and the typical load versus displacement curves under different loading configurations are presented. Uniqueness of the current data compared with data in the open literature is discussed. The experimental results for all the joint populations indicate that joint strength increases with increasing loading rate. However, the strength increase from 4.47m/s (10mph) to 8.94m/s (20mph) is not as significant as the strength increase from static to 4.47m/s. It is also found that with increasing loading velocity, displacement to failure decreases for all the joint samples. Therefore, “brittleness” of the joint sample increases with impact velocity. Detailed static and dynamic strength data and the associated energy absorption levels for all the samples in the thirteen joint populations are also included.

  1. Study on nondestructive inspection using HTS-SQUID for friction stir welding between dissimilar metals

    NASA Astrophysics Data System (ADS)

    Hatsukade, Y.; Takahashi, T.; Yasui, T.; Tsubaki, M.; Fukumono, M.; Tanaka, S.

    2007-10-01

    We have developed an SQUID-NDI technique for evaluation of friction stir welding (FSW) between aluminum alloy A6063 and stainless steel SUS304 from the electric conductivities in board specimens bonded by FSW. A SQUID-NDI system employing an HTS-SQUID gradiometer was constructed to measure current distribution in the FSW specimens by applying voltage to the specimen. By measuring field gradients dBz/dy and dBz/dx above the FSW specimens made with various FSW conditions and then converting them to current vector Jx and Jy, conductivities of FSW areas were estimated. Due to the difference in the FSW conditions, the conductivity distributions varied dramatically. From these results, it was suggested that the conductivities in FSW areas should be varied due to the temperature heated by the friction between the milling tool and the materials.

  2. Final Assessment of Manual Ultrasonic Examinations Applied to Detect Flaws in Primary System Dissimilar Metal Welds at North Anna Power Station

    SciTech Connect

    Anderson, Michael T.; Diaz, Aaron A.; Cinson, Anthony D.; Crawford, Susan L.; Prowant, Matthew S.; Doctor, Steven R.

    2014-03-24

    PNNL conducted a technical assessment of the NDE issues and protocols that led to missed detections of several axially oriented flaws in a steam generator primary inlet dissimilar metal weld at North Anna Power Station, Unit 1 (NAPS-1). This particular component design exhibits a significant outside-diameter (OD) taper that is not included as a blind performance demonstration mock-up within the industry’s Performance Demonstration Initiative, administered by EPRI. For this reason, the licensee engaged EPRI to assist in the development of a technical justification to support the basis for a site-specific qualification. The service-induced flaws at NAPS-1 were eventually detected as a result of OD surface machining in preparation for a full structural weld overlay. The machining operation uncovered the existence of two through-wall flaws, based on the observance of primary water leaking from the dissimilar metal weld. A total of five axially oriented flaws were detected in varied locations around the weld circumference. The field volumetric examination that was conducted at NAPS-1 was a non-encoded, real-time manual ultrasonic examination. PNNL conducted both an initial assessment, and subsequently, a more rigorous technical evaluation (reported here), which has identified an array of NDE issues that may have led to the subject missed detections. These evaluations were performed through technical reviews and discussions with NRC staff, EPRI NDE Center personnel, industry and ISI vendor personnel, and ultrasonic transducer manufacturers, and laboratory tests, to better understand the underlying issues at North Anna.

  3. Microstructural characterization of an SA508–309L/308L–316L domestic dissimilar metal welded safe-end joint

    SciTech Connect

    Ming, Hongliang; Zhang, Zhiming; Wang, Jianqiu Han, En-Hou; Ke, Wei

    2014-11-15

    The microstructure of an SA508–309L/308L–316L domestic dissimilar metal welded safe-end joint was characterized in this work by optical microscopy, scanning electron microscopy (with electron back scattering diffraction) and micro-hardness testing. Epitaxial growth and competitive growth are evident in the 308L–316L fusion boundary regions. A martensite layer, carbon-depleted zones, and type-II and type-I boundaries are found in the SA508–309L fusion boundary regions, while only martensite and austenite mixed zones are observed in the SA508–308L fusion boundary regions. The microstructure near the fusion boundary and the microstructure transition in the SA508 heat affected zone are quite complex. Both for SA508–309L/308L and 308L–316L, the highest residual strain is located on the outside of the weldment. The residual strain and the grain boundary character distribution change with increasing distance from the fusion boundary in the heat affected zone of 316L. Micro-hardness measurements also reveal non-uniform mechanical properties across the weldment. - Highlights: • The microstructure of SA508 HAZ, especially near the FB, is very complex. • The outside of the dissimilar metal welded joint has the highest residual. • The micro-hardness distributions along the DMWJ are non-uniform.

  4. 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.

  5. 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.

  6. Environmentally-assisted cracking behaviour in the transition region of an Alloy182/SA 508 Cl.2 dissimilar metal weld joint in simulated boiling water reactor normal water chemistry environment

    NASA Astrophysics Data System (ADS)

    Seifert, H. P.; Ritter, S.; Shoji, T.; Peng, Q. J.; Takeda, Y.; Lu, Z. P.

    2008-08-01

    The stress corrosion cracking (SCC) and corrosion fatigue behaviour perpendicular and parallel to the fusion line in the transition region between the Alloy 182 Nickel-base weld metal and the adjacent SA 508 Cl.2 low-alloy reactor pressure vessel (RPV) steel of a simulated dissimilar metal weld joint was investigated under boiling water reactor normal water chemistry conditions. A special emphasis was placed to the question whether a fast growing interdendritic SCC crack in the highly susceptible Alloy 182 weld metal can easily cross the fusion line and significantly propagate into the adjacent low-alloy RPV steel. Cessation of interdendritic SCC crack growth was observed in high-purity or sulphate-containing oxygenated water under constant or periodical partial unloading conditions for those parts of the crack front, which reached the fusion line. In chloride containing water, on the other hand, the interdendritic SCC crack in the Alloy 182 weld metal very easily crossed the fusion line and further propagated with a very high rate as a transgranular crack into the heat-affected zone and base metal of the adjacent low-alloy steel. The observed SCC cracking behaviour at the interface correlates excellently with the field experience of such dissimilar metal weld joints, where SCC cracking was usually confined to the Alloy 182 weld metal.

  7. Primary Water Stress Corrosion Cracks in Nickel Alloy Dissimilar Metal Welds: Detection and Sizing Using Established and Emerging Nondestructive Examination Techniques

    SciTech Connect

    Braatz, Brett G.; Cumblidge, Stephen E.; Doctor, Steven R.; Prokofiev, Iouri

    2012-12-31

    The U.S. Nuclear Regulatory Commission has established the Program to Assess the Reliability of Emerging Nondestructive Techniques (PARENT) as a follow-on to the international cooperative Program for the Inspection of Nickel Alloy Components (PINC). The goal of PINC was to evaluate the capabilities of various nondestructive evaluation (NDE) techniques to detect and characterize surface-breaking primary water stress corrosion cracks in dissimilar-metal welds (DMW) in bottom-mounted instrumentation (BMI) penetrations and small-bore (≈400-mm diameter) piping components. A series of international blind round-robin tests were conducted by commercial and university inspection teams. Results from these tests showed that a combination of conventional and phased-array ultrasound techniques provided the highest performance for flaw detection and depth sizing in dissimilar metal piping welds. The effective detection of flaws in BMIs by eddy current and ultrasound shows that it may be possible to reliably inspect these components in the field. The goal of PARENT is to continue the work begun in PINC and apply the lessons learned to a series of open and blind international round-robin tests that will be conducted on a new set of piping components including large-bore (≈900-mm diameter) DMWs, small-bore DMWs, and BMIs. Open round-robin testing will engage universities and industry worldwide to investigate the reliability of emerging NDE techniques to detect and accurately size flaws having a wide range of lengths, depths, orientations, and locations. Blind round-robin testing will invite testing organizations worldwide, whose inspectors and procedures are certified by the standards for the nuclear industry in their respective countries, to investigate the ability of established NDE techniques to detect and size flaws whose characteristics range from easy to very difficult to detect and size. This paper presents highlights of PINC and reports on the plans and progress for

  8. Field Evaluations of Low-Frequency SAFT-UT on Cast Stainless Steel and Dissimilar Metal Weld Components

    SciTech Connect

    Diaz, Aaron A.; Harris, R. V.; Doctor, Steven R.

    2008-11-01

    This report documents work performed at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington, and at the Electric Power Research Institute's (EPRI) Nondestructive Examination (NDE) Center in Charlotte, North Carolina, on evalutating a low frequency ultrasonic inspection technique used for examination of cast stainless steel (CSS) and dissimilar metal (DMW) reactor piping components. The technique uses a zone-focused, multi-incident angle, low frequency (250-450 kHz) inspection protocol coupled with the synthetic aperture focusing technique (SAFT). The primary focus of this work is to provide information to the United States Nuclear Regulatory Commission on the utility, effectiveness and reliability of ultrasonic testing (UT) inspection techniques as related to the inservice ultrasonic inspection of coarse grained primary piping components in pressurized water reactors (PWRs).

  9. Technical Letter Report, An Evaluation of Ultrasonic Phased Array Testing for Reactor Piping System Components Containing Dissimilar Metal Welds, JCN N6398, Task 2A

    SciTech Connect

    Diaz, Aaron A.; Cinson, Anthony D.; Crawford, Susan L.; Anderson, Michael T.

    2009-11-30

    Research is being conducted for the U.S. Nuclear Regulatory Commission at the Pacific Northwest National Laboratory to assess the effectiveness and reliability of advanced nondestructive examination (NDE) methods for the inspection of light-water reactor components. The scope of this research encom¬passes primary system pressure boundary materials including dissimilar metal welds (DMWs), cast austenitic stainless steels (CASS), piping with corrosion-resistant cladding, weld overlays, inlays and onlays, and far-side examinations of austenitic piping welds. A primary objective of this work is to evaluate various NDE methods to assess their ability to detect, localize, and size cracks in steel components that challenge standard and/or conventional inspection methodologies. This interim technical letter report provides a summary of a technical evaluation aimed at assessing the capabilities of phased-array (PA) ultrasonic testing (UT) methods as applied to the inspection of small-bore DMW components that exist in the reactor coolant systems (RCS) of pressurized water reactors (PWRs). Operating experience and events such as the circumferential cracking in the reactor vessel nozzle-to-RCS hot leg pipe at V.C. Summer nuclear power station, identified in 2000, show that in PWRs where primary coolant water (or steam) are present under normal operation, Alloy 82/182 materials are susceptible to pressurized water stress corrosion cracking. The extent and number of occurrences of DMW cracking in nuclear power plants (domestically and internationally) indicate the necessity for reliable and effective inspection techniques. The work described herein was performed to provide insights for evaluating the utility of advanced NDE approaches for the inspection of DMW components such as a pressurizer surge nozzle DMW, a shutdown cooling pipe DMW, and a ferritic (low-alloy carbon steel)-to-CASS pipe DMW configuration.

  10. Ultrasonic spot welding of dissimilar materials: characterization of welded joints and parametric optimization

    NASA Astrophysics Data System (ADS)

    Satpathy, M. P.; Sahoo, S. K.

    2016-02-01

    Material joining is one of the key manufacturing processes used to assemble metallic and non-metallic parts for several applications. But the industries are facing many difficulties in joining of thin sheets of dissimilar metals by the conventional welding process because of their differences in chemical composition, physical and mechanical properties. Thus, ultrasonic welding is a solid state joining process used for joining of small elements in microelectronics industries. In this process, acoustic horn and booster are the important assets. The accuracy and strength of the welding depend mainly on their geometry. This proposed work deals with the design and modelling of an acoustic stepped sonotrode with booster using finite element analysis (FEA). From this analysis, the actual length of the horn is obtained by gradually decreasing its theoretical length. The quality of the weld is reckoned by its weld strength and the combinations of different process parameters. These are examined using the principal components coupled with grey relational analysis approach which is showing good agreement between the predicted values with experimental results. Fractographic examination of weld zone and hardness are also used to explore the weld quality.

  11. Brazing Dissimilar Metals

    NASA Technical Reports Server (NTRS)

    Krotz, Phillip D.; Davis, William M.; Wisner, Daniel L.

    1996-01-01

    Brazing effective technique for joining ordinary structural metals to brittle, low-thermal-expansion refractory metals. Specifically, brazing process established for joining copper or nickel flanges to ends of vacuum-plasma-sprayed tungsten tubes and for joining stainless-steel flanges to ends of tubes made of alloy of molybdenum with 40 percent of rhenium.

  12. 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.

  13. Dissimilar Al/steel friction stir welding lap joints for automotive applications

    NASA Astrophysics Data System (ADS)

    Campanella, D.; Spena, P. Russo; Buffa, G.; Fratini, L.

    2016-10-01

    A widespread usage of aluminum alloys for the fabrication of car-body parts is conditional on the employment of appropriate welding methods, especially if dissimilar welding must be performed with automotive steel grades. Dissimilar welding of aluminum alloys and steel grades poses some issues concerning the formation of brittle intermetallic compounds, difference in physical and chemical properties of the parent metals, and poor wetting behavior of aluminum. Friction stir welding is considered to be a reasonable solution to obtain sound aluminum/steel joints. A study on the join quality of dissimilar lap joints of steel and aluminum alloy sheets after friction stir welding is proposed here. A low carbon steel is joined with AA6016 aluminum alloy to study preliminarily the feasibility to assembly car-body parts. The joints, welded with tool rotation and feed rate varying in a wide range, have been studied from a visual examination and microstructural point of view. Optical microscopy has been used to characterize the microstructure of the examined sheets in as-received and welded conditions. Micro-hardness measurements have been carried out to quantitatively analyze the local hardness of the welded joints. Set welding process parameters are identified to assemble without the presence of macroscopic defects the examined steel and aluminum welded parts.

  14. Procedure for Computing Residual Stresses from Neutron Diffraction Data and its Application to Multi-Pass Dissimilar Weld

    SciTech Connect

    Zhang, Wei; Feng, Zhili; Crooker, Paul

    2011-01-01

    Neutron diffraction is a powerful tool for non-destructive measurement of internal residual stresses of welded structures. The conventional approach for determination of residual stresses requires the knowledge of stress-free lattice spacing a priori. For multiple-pass dissimilar metal welds common to nuclear reactor pipeline systems, the stress-free lattice parameter is a complex function of position due to the chemistry inhomogeneity in the weld region and can be challenging to determine experimentally. This paper presents a new approach to calculate the residual stress field in dissimilar welds without the use of stress-free lattice parameter. The theoretical basis takes advantage of the fact that the normal component of welding residual stresses is typically small for thin plate or pipe welds. The applicability of the new approach is examined and justified in a multi-pass dissimilar metal weld consisting of a stainless steel plate and a nickel alloy filler metal. The level of uncertainties associated with this new approach is assessed. Neutron diffraction experiment is carried out to measure the lattice spacing at various locations in the dissimilar weld. A comb-shaped specimen, electro-discharge machined from a companion weld, is used to determine the stress-free lattice spacing. The calculated results from the new approach are consistent with those from the conventional approach. The new approach is found to be a practical method for determining the two in-plane residual stress components in thin plate or pipe dissimilar metal welds.

  15. Picosecond laser welding of similar and dissimilar materials.

    PubMed

    Carter, Richard M; Chen, Jianyong; Shephard, Jonathan D; Thomson, Robert R; Hand, Duncan P

    2014-07-01

    We report picosecond laser welding of similar and dissimilar materials based on plasma formation induced by a tightly focused beam from a 1030 nm, 10 ps, 400 kHz laser system. Specifically, we demonstrate the welding of fused silica, borosilicate, and sapphire to a range of materials including borosilicate, fused silica, silicon, copper, aluminum, and stainless steel. Dissimilar material welding of glass to aluminum and stainless steel has not been previously reported. Analysis of the borosilicate-to-borosilicate weld strength compares well to those obtained using similar welding systems based on femtosecond lasers. There is, however, a strong requirement to prepare surfaces to a high (10-60 nm Ra) flatness to ensure a successful weld.

  16. Hot-cracking mechanism in CO/sub 2/ laser beam welds of dissimilar metals involving PH martensitic stainless steels

    SciTech Connect

    Cieslak, M.J.

    1987-02-01

    Autogenous CO/sub 2/ laser beam welds were made between Alloy HP 9-4-20 and both 15-5 PH and PH 13-8 Mo stainless steel. Small scale circular-patch test specimens revealed that the combination involving the Nb-bearing alloy, 15-5 PH, was far more crack susceptible than the combination involving the Nb-free alloy, PH 13-8 Mo. Analytical electron microscopy was used to identify an NbC/austenite eutectic-like constituent as being responsible for the cracking phenomenon.

  17. 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.

  18. 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.

  19. Explosively Joining Dissimilar Metal Tubes.

    DTIC Science & Technology

    1979-11-01

    both steel, photograph (7), and the Ni-Cu specimen, photograph (8) , showed considerable pitting corrosion in the aluminum . 4. The paint was then...for 6061 -T6 aluminum and are: collision angle 5 - 200, collision velocity 270 - 350 m/sec, with an impact pressure of at least 27 Kbar (391 Kpsi...Welded Aluminum Alloy 1 .. 5 rn-i (P0 -I Op. 2si 11 6W TABLE I Explosive2 Cladder Metal Base Metal Explosive Loading (gins/in2 6061 -T6 Al 304 SS TSE- 1004

  20. Microstructural Characterizations with EDAX Analysis of Dissimilar Friction Stir Welds

    NASA Astrophysics Data System (ADS)

    Ravikumar, S.; Rao, V. S.

    2013-10-01

    This paper reports the microstructural characteristics of dissimilar friction stir welds with AA7075T651 and AA6061T651. Dissimilar friction stir welds between AA7075T651 and AA6061T651 were produced by varying the rotational speeds between 800 and 1,000 rpm and the welding speeds between 90 and 110 mm/min. The welds were characterized through optical microscope and scanning electron microscope (SEM). Three different tool profiles (taper cylindrical threaded, taper square threaded and simple square) were used for this investigation and in that taper cylindrical threaded tool with process parameters 900 rpm and 100 mm/min were found to have maximum tensile strength of 205 MPa for the dissimilar butt joints. The SEM with energy-dispersive X-ray spectroscopy analysis reveals the metallurgical bonding achieved at the joint interfaces of the welds produced. The good mixing of both the materials joined was obtained at lower welding and higher rotational speed while the tunnel defect was found to be common in the welds produced irrespective of the tool pin profiles and process parameters due to insufficient axial load with 0° tilt angle.

  1. Welded joints integrity analysis and optimization for fiber laser welding of dissimilar materials

    NASA Astrophysics Data System (ADS)

    Ai, Yuewei; Shao, Xinyu; Jiang, Ping; Li, Peigen; Liu, Yang; Liu, Wei

    2016-11-01

    Dissimilar materials welded joints provide many advantages in power, automotive, chemical, and spacecraft industries. The weld bead integrity which is determined by process parameters plays a significant role in the welding quality during the fiber laser welding (FLW) of dissimilar materials. In this paper, an optimization method by taking the integrity of the weld bead and weld area into consideration is proposed for FLW of dissimilar materials, the low carbon steel and stainless steel. The relationships between the weld bead integrity and process parameters are developed by the genetic algorithm optimized back propagation neural network (GA-BPNN). The particle swarm optimization (PSO) algorithm is taken for optimizing the predicted outputs from GA-BPNN for the objective. Through the optimization process, the desired weld bead with good integrity and minimum weld area are obtained and the corresponding microstructure and microhardness are excellent. The mechanical properties of the optimized joints are greatly improved compared with that of the un-optimized welded joints. Moreover, the effects of significant factors are analyzed based on the statistical approach and the laser power (LP) is identified as the most significant factor on the weld bead integrity and weld area. The results indicate that the proposed method is effective for improving the reliability and stability of welded joints in the practical production.

  2. The use of dissimilar metals in surgery.

    PubMed

    Mears, D C

    1975-07-01

    Previously, the use of dissimilar metals for the construction of surgical implants has been strongly discouraged because the combination of metals was likely to provoke more rapid corrosion of one metal. With the passive alloys that are in present and future application, however, a reconsideration of the use of dissimilar metals is required. Presently available electrochemical tests allow accurate prediction of safe and unsafe combinations of metals. The use of dissimilar metals would permit selection of the alloy of appropriate mechanical properties for each part of an implant and would allow improved corrosion resistance that certain alloys can convey to other alloys with which they are in contact.

  3. Investigation on Mechanical Properties of 9%Cr/CrMoV Dissimilar Steels Welded Joint

    NASA Astrophysics Data System (ADS)

    Liu, Xia; Lu, Fenggui; Yang, Renjie; Wang, Peng; Xu, Xiaojin; Huo, Xin

    2015-04-01

    Advanced 9%Cr steel with good heat resistance and CrMoV with good toughness were chosen as candidate materials to fabricate combined rotor for steam turbine operating at over 620 °C. But the great difference in base metals properties presents a challenge in achieving sound defect-free joint with optimal properties in dissimilar welded rotor. In this paper, appropriate selection of filler metal, welding parameters, and post-weld heat treatment was combined to successfully weld 1100-mm-diameter 9%Cr/CrMoV dissimilar experimental rotor through ultra-narrow gap submerge arc welding. Some properties such as hardness, low-cycle fatigue (LCF), and high-cycle fatigue (HCF) combined with microstructural characterization qualify the integrity of the weld. Microstructural analysis indicated the presence of high-temperature tempered martensite as the phase responsible for the improved properties obtained in the weld. The Coffin-Manson parameters were obtained by fitting the data in LCF test, while the conditional fatigue strength was derived from the HCF test based on S-N curve. Analysis of hardness profile showed that the lowest value occurred at heat-affected zone adjacent to base metal which represents the appropriate location of fracture for the samples after LCF and HCF tests.

  4. Microstructural characterization of dissimilar welds between Incoloy 800H and 321 Austenitic Stainless Steel

    SciTech Connect

    Sayiram, G. Arivazhagan, N.

    2015-04-15

    In this work, the microstructural character of dissimilar welds between Incoloy 800H and 321 Stainless Steel has been discussed. The microscopic examination of the base metals, fusion zones and interfaces was characterized using an optical microscope and scanning electron microscopy. The results revealed precipitates of Ti (C, N) in the austenitic matrix along the grain boundaries of the base metals. Migration of grain boundaries in the Inconel 82 weld metal was very extensive when compared to Inconel 617 weldment. Epitaxial growth was observed in the 617 weldment which increases the strength and ductility of the weld metal. Unmixed zone near the fusion line between 321 Stainless Steel and Inconel 82 weld metal was identified. From the results, it has been concluded that Inconel 617 filler metal is a preferable choice for the joint between Incoloy 800H and 321 Stainless Steel. - Highlights: • Failure mechanisms produced by dissimilar welding of Incoloy 800H to AISI 321SS • Influence of filler wire on microstructure properties • Contemplative comparisons of metallurgical aspects of these weldments • Microstructure and chemical studies including metallography, SEM–EDS • EDS-line scan study at interface.

  5. Evaluation of near-surface stress distributions in dissimilar welded joint by scanning acoustic microscopy.

    PubMed

    Kwak, Dong Ryul; Yoshida, Sanichiro; Sasaki, Tomohiro; Todd, Judith A; Park, Ik Keun

    2016-04-01

    This paper presents the results from a set of experiments designed to ultrasonically measure the near surface stresses distributed within a dissimilar metal welded plate. A scanning acoustic microscope (SAM), with a tone-burst ultrasonic wave frequency of 200 MHz, was used for the measurement of near surface stresses in the dissimilar welded plate between 304 stainless steel and low carbon steel. For quantitative data acquisition such as leaky surface acoustic wave (leaky SAW) velocity measurement, a point focus acoustic lens of frequency 200 MHz was used and the leaky SAW velocities within the specimen were precisely measured. The distributions of the surface acoustic wave velocities change according to the near-surface stresses within the joint. A three dimensional (3D) finite element simulation was carried out to predict numerically the stress distributions and compare with the experimental results. The experiment and FE simulation results for the dissimilar welded plate showed good agreement. This research demonstrates that a combination of FE simulation and ultrasonic stress measurements using SAW velocity distributions appear promising for determining welding residual stresses in dissimilar material joints.

  6. Evaluation of Laser Braze-welded Dissimilar Al-Cu Joints

    NASA Astrophysics Data System (ADS)

    Schmalen, Pascal; Plapper, Peter

    The thermal joining of Aluminum and Copper is a promising technology towards automotive battery manufacturing. The dissimilar metals Al-Cu are difficult to weld due to their different physicochemical characteristics and the formation of intermetallic compounds (IMC), which have reduced mechanical and electric properties. There is a critical thickness of the IMCs where the favored mechanical properties of the base material can be preserved. The laser braze welding principle uses a position and power oscillated laser-beam to reduce the energy input and the intermixture of both materials and therefore achieves minimized IMCs thickness. The evaluation of the weld seam is important to improve the joint performance and enhance the welding process. This paper is focused on the characterization and quantification of the IMCs. Mechanical, electrical and metallurgical methods are presented and performed on Al1050 and SF-Cu joints and precise weld criteria are developed.

  7. Some recent studies on laser cladding and dissimilar welding

    NASA Astrophysics Data System (ADS)

    Kaul, Rakesh; Ganesh, P.; Paul, C. P.; Albert, S. K.; Mudali, U. Kamachi; Nath, A. K.

    2006-01-01

    Indigenous development of high power CO II laser technology and industrial application of lasers represent two important mandates of the laser program, being pursued at Centre for Advanced Technology (CAT), India. The present paper describes some of the important laser material processing studies, involving cladding and dissimilar welding, performed in authors' laboratory. The first case study describes how low heat input characteristics of laser cladding process has been successfully exploited for suppressing dilution in "Colmonoy6" (a nickel-base hardfacing alloy) deposits on austenitic stainless steel components. Crack free hardfaced deposits were obtained by controlling heating and cooling rates associated with laser treatment. The results show significant advantage over Colmonoy 6 deposits made by GTAW, where a 2.5 mm thick region of dilution (with reduced hardness) develops next to substrateiclad interface. The next work involves laser-assisted deposition of graded "Stellite6" (a Co-base hardfacing alloy) with smooth transition in chemical composition and hardness for enhanced resistance against cracking, esp. under thermal cycling conditions. The following two case studies demonstrate significant improvement in corrosion properties of type 304L stainless steel by laser surface alloying, achieved through cladding route. The following case study demonstrates engineering of fusion zone microstructure of end plug dissimilar weld (between alloy D9 and type 3 16M stainless steel) by controlled preferential displacement of focused laser beam, which, in-turn, enhanced its resistance against solidification cracking. Crater appearing at the termination point of laser weld is also eliminated by ramping of laser power towards the end of laser welding. The last case study involves engineering of fusion zone microstructure of dissimilar laser weld between type 304 austenitic stainless steel and stabilized 17%Cr ferritic stainless steel by controlling welding parameters.

  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. Simulation model of Al-Ti dissimilar laser welding-brazing and its experimental verification

    NASA Astrophysics Data System (ADS)

    Behúlová, M.; Babalová, E.; Nagy, M.

    2017-02-01

    Formation of dissimilar weld joints of light metals and alloys including Al-Ti joints is interesting mainly due to demands on the weight reduction and corrosion resistance of components and structures in automotive, aircraft, aeronautic and other industries. Joining of Al-Ti alloys represents quite difficult problem. Generally, the fusion welding of these materials can lead to the development of different metastable phases and formation of brittle intermetallic compounds. The paper deals with numerical simulation of the laser welding-brazing process of titanium Grade 2 and EN AW 5083 aluminum alloy sheets using the 5087 aluminum filler wire. Simulation model for welding-brazing of testing samples with the dimensions of 50 × 100 × 2 mm was developed in order to perform numerical experiments applying variable welding parameters and to design proper combination of these parameters for formation of sound Al-Ti welded-brazed joints. Thermal properties of welded materials in the dependence on temperature were computed using JMatPro software. The conical model of the heat source was exploited for description of the heat input to the weld due to the moving laser beam source. The sample cooling by convection and radiation to the surrounding air and shielding argon gas was taken into account. Developed simulation model was verified by comparison of obtained results of numerical simulation with the temperatures measured during real experiments of laser welding-brazing by the TruDisk 4002 disk laser.

  10. Dissimilar Arc Welding of Advanced High-Strength Car-Body Steel Sheets

    NASA Astrophysics Data System (ADS)

    Russo Spena, P.; D'Aiuto, F.; Matteis, P.; Scavino, G.

    2014-11-01

    A widespread usage of new advanced TWIP steel grades for the fabrication of car-body parts is conditional on the employment of appropriate welding methods, especially if dissimilar welding must be performed with other automotive steel grades. Therefore, the microstructural features and the mechanical response of dissimilar butt weld seams of TWIP and 22MnB5 steel sheets after metal-active-gas arc welding are examined. The microstructural and mechanical characterization of the welded joints was carried out by optical metallography, microhardness and tensile testing, and fractographic examination. The heat-affected zone on the TWIP side was fully austenitic and the only detectable effect was grain coarsening, while on the 22MnB5 side it exhibited newly formed martensite and tempered martensite. The welded tensile specimens exhibited a much larger deformation on the TWIP steel side than on the 22MnB5. The fracture generally occurred at the interface between the fusion zone and the heat-affected zones, with the fractures surfaces being predominantly ductile. The ultimate tensile strength of the butt joints was about 25% lower than that of the TWIP steel.

  11. Characterization of microstructures and mechanical properties of Inconel 617/310 stainless steel dissimilar welds

    SciTech Connect

    Shah Hosseini, H. Shamanian, M.; Kermanpur, A.

    2011-04-15

    The microstructure and mechanical properties of Inconel 617/310 austenitic stainless steel dissimilar welds were investigated in this work. Three types of filler materials, Inconel 617, Inconel 82 and 310 austenitic stainless steels were used to obtain dissimilar joint using the gas tungsten arc welding process. Microstructural observations showed that there was no evidence of any possible cracking in the weldments achieved by the nickel-base filler materials. The welds produced by 617 and 310 filler materials displayed the highest and the lowest ultimate tensile strength and total elongation, respectively. The impact test results indicated that all specimens exhibited ductile fracture. Among the fillers, Inconel 617 exhibited superlative fracture toughness (205 J). The mechanical properties of the Inconel 617 filler material were much better than those of other fillers. - Research Highlights: {yields} A fine dendritic structure was seen for the Inconel 617 weld metal. {yields} A number of cracks were initiated when the 310 SS filler metal was used. {yields} All welded samples showed ductile fracture. {yields} The Inconel 617 filler material presents the optimum mechanical properties.

  12. Low Cycle and Thermo-Mechanical Fatigue of Friction Welded Dissimilar Superalloys Joint

    NASA Astrophysics Data System (ADS)

    Sakaguchi, Motoki; Sano, Atsushi; Tran, Tra Hung; Okazaki, Masakazu; Sekihara, Masaru

    The high temperature strengths of the dissimilar friction welded superalloys joint between the cast polycrystalline Mar-M247 and the forged IN718 alloys have been investigated under low cycle and thermo-mechanical fatigue loadings, in comparison with those of the base metals. The experiments showed that the lives of the dissimilar joints were significantly influenced by the test conditions and loading modes. Not only the lives themselves but also the failure positions and mechanisms were sensitive to the loading mode. The fracture behaviors depending on the loading modes and test conditions were discussed, based on the macroscopic elastic follow-up mechanism and the microstructural inhomogeneity in the friction weld joint.

  13. Combining dissimilar metals in orthopaedic implants: revisited.

    PubMed

    Zartman, Kevin C; Berlet, Gregory C; Hyer, Christopher F; Woodard, Joseph R

    2011-10-01

    The use of metals as implant materials has become common practice in the field of orthopaedics. A wide variety of conditions are treated with metallic implants, and designers have used an assortment of materials to meet the unique mechanical demands of each application. The majority of implants used today, whether pins, plates, screws, or total joints, are made of cobalt-chrome alloy, stainless steel, or titanium. Common metallurgic wisdom cautions against bonding dissimilar metals in a biologically active environment. Surgeons have therefore shied away from combining dissimilar metal implants because of the fear of inciting corrosion that could potentially compromise the implants and lead to aseptic loosening, implant failure, or adverse biological reaction in host tissue. As surgical reconstruction and arthroplasty options expand with the advent of newer implants and expanded operative techniques, the orthopaedic surgeon will increasingly be faced with weighing the risks and benefits of combining implants made of dissimilar metals in a patient. Here, the authors examine the origins of the concern over using mixed metals, discuss mechanisms of corrosion as they relate to surgical implants, and review both in vitro and in vivo studies concerning the most common combinations of dissimilar metals in order to guide the surgeon in choosing implants.

  14. Microstructural, mechanical and weldability assessments of the dissimilar welds between γ′- and γ″-strengthened nickel-base superalloys

    SciTech Connect

    Naffakh Moosavy, Homam; Aboutalebi, Mohammad-Reza; Seyedein, Seyed Hossein; Mapelli, Carlo

    2013-08-15

    Dissimilar welding of γ′- and γ″-strengthened nickel-base superalloys has been investigated to identify the relationship between the microstructure of the welds and the resultant mechanical and weldability characteristics. γ′-Strengthened nickel-base Alloy 500 and γ″-strengthened nickel-base Alloy 718 were used for dissimilar welding. Gas tungsten arc welding operations were utilized for performing the autogenous dissimilar welding. Alloy 500 and Alloy 718 base metals showed various types of phases, carbides, intermetallics and eutectics in their microstructure. The results for Alloy 500 weld metal showed severe segregation of titanium to the interdendritic regions. The Alloy 718 weld metal compositional analysis confirmed the substantial role of Nb in the formation of low-melting eutectic-type morphologies which can reduce the weldability. The microstructure of dissimilar weld metal with dilution level of 65% wt.% displayed semi-developed dendritic structure. The less segregation and less formation of low-melting eutectic structures caused to less susceptibility of the dissimilar weld metal to the solidification cracking. This result was confirmed by analytic modeling achievements. Dissolution of γ″-Ni{sub 3}Nb precipitations took place in the Alloy 718 heat-affected zone leading to sharp decline of the microhardness in this region. Remelted and resolidified regions were observed in the partially-melted zone of Alloy 500 and Alloy 718. Nevertheless, no solidification and liquation cracking happened in the dissimilar welds. Finally, this was concluded that dissimilar welding of γ′- and γ″-strengthened nickel-base superalloys can successfully be performed. - Highlights: • Dissimilar welding of γ′- and γ″-strengthened nickel-base superalloys is studied. • Microstructural, mechanical and weldability aspects of the welds are assessed. • Microstructure of welds, bases and heat-affected zones is characterized in detail. • The type

  15. Microstructures and electrochemical behaviors of the friction stir welding dissimilar weld.

    PubMed

    Shen, Changbin; Zhang, Jiayan; Ge, Jiping

    2011-06-01

    By using optical microscope, the microstructures of 5083/6082 friction stir welding (FSW) weld and parent materials were analyzed. Meanwhile, at ambient temperature and in 0.2 mol/L NaHS03 and 0.6 mol/L NaCl solutionby gravimetric test, potentiodynamic polarization curve test, electrochemical impedance spectra (EIS) and scanning electron microscope (SEM) observation, the electrochemical behavior of 5083/6082 friction stir welding weld and parent materials were comparatively investigated by gravimetric test, potentiodynamic polarization curve test, electrochemical impedance spectra (EIS) and scanning electron microscope (SEM) observation. The results indicated that at given processing parameters, the anti-corrosion property of the dissimilar weld was superior to those of the 5083 and 6082 parent materials.

  16. Weld Metallurgy and Mechanical Properties of High Manganese Ultra-high Strength Steel Dissimilar Welds

    NASA Astrophysics Data System (ADS)

    Dahmen, Martin; Lindner, Stefan; Monfort, Damien; Petring, Dirk

    The increasing demand for ultra-high strength steels in vehicle manufacturing leads to the application of new alloys. This poses a challenge on joining especially by fusion welding. A stainless high manganese steel sheet with excellent strength and deformation properties stands in the centre of the development. Similar and dissimilar welds with a metastable austenitic steel and a hot formed martensitic stainless steel were performed. An investigation of the mixing effects on the local microstructure and the hardness delivers the metallurgical features of the welds. Despite of carbon contents above 0.4 wt.% none of the welds have shown cracks. Mechanical properties drawn from tensile tests deliver high breaking forces enabling a high stiffness of the joints. The results show the potential for the application of laser beam welding for joining in assembly of structural parts.

  17. Development of temper-bead technique applied to dissimilar welded joints of nuclear pressure vessels

    SciTech Connect

    Higuchi, Makoto; Umemoto, Tadahiro; Matsusita, Akitake; Shiraiwa, Takanori

    1996-06-01

    When nuclear pressure vessels made of low-alloy steel (P-3 Group 3) need repair or modification, technical standards for welding of electrical structures should be applied, and then postweld heat treatment (PWHT) should be done. However, cases in which PWHT is impractical are theoretically possible due to a variety of restrictions. To deal with such a problem, there is a regulation for repair weld technique, without PWHT, in accordance with ASME B and PV Code. This method is called temper-bead technique, which gives the weldments sufficient toughness by tempering the hardened zone of the heat-affected zone on the first layer of the base metal using the heat of the following weld beads. Because there is no regulation in Japan covering this method, a procedure is required to perform it under a special license, after a verification test has been passed. An attempt has been made to develop a method, on the supposition that the temper-bead technique is adopted for replacement of what is called dissimilar welded joints, so that a nickel base alloy is buildup welded at the tip of the nozzle of the low-alloy steel pressure vessel, and a stainless steel pipe is butt welded.

  18. Inertia Friction Welding of Dissimilar Superalloys Mar-M247 and LSHR

    NASA Astrophysics Data System (ADS)

    Senkov, Oleg N.; Mahaffey, David W.; Semiatin, S. Lee; Woodward, Christopher

    2014-11-01

    The solid state inertia friction welding (IFW) process was used for the first time to join two dissimilar Ni-based superalloys, LSHR, a powder metallurgy alloy, and Mar-M247, a directionally solidified alloy. Extensive studies of the microstructure, phase composition, re-distribution of the alloying elements between the welded alloys, microhardness, and welding defects were conducted at different distances from the weld interface, and the results were correlated with the loading and friction conditions during IFW. Possible reasons leading to the formation of the welding defects were discussed and directions for the further improvement of the quality of the IFW of these two dissimilar alloys were outlined.

  19. Fusion welding studies using laser on Ti-SS dissimilar combination

    NASA Astrophysics Data System (ADS)

    Shanmugarajan, B.; Padmanabham, G.

    2012-11-01

    Laser welding investigations were carried out on dissimilar Ti-SS combination. The study is aimed to improve the weld strength and ductility by minimizing harmful intermetallics and taking advantage of high cooling rates in laser welding. Results of continuous wave 3.5 kW CO2 laser welding of totally dissimilar combination of Titanium and stainless steel (304) have been discussed. Bead on plate welding experiments were conducted to identify the laser welding parameters using depth of penetration as criteria. The welding of dissimilar combination has been attempted both autogenously and with interlayers such as Vanadium (V) and Tantalum (Ta) in the form of laser cladding as well as strip. Autogenous welds were carried out by varying the laser power, welding speed and position of the laser beam with respect to the joint centre. The resultant welds are characterized by macrostructure analysis, SEM/EDAX and XRD and as welded tensile test in UTM. The autogenous welds have exhibited extensive cracking even when welded at high speeds or by manipulating the beam position with respect to the joint. Similarly Vandaium as interlayer could not achieve crack free joint. A joint with 40 MPa strength could be made with Ta as interlayer. Results and analysis of these variants of laser welded joints are reported and discussed.

  20. Grain boundary defects initiation at the outer surface of dissimilar welds: Corrosion mechanism studies

    SciTech Connect

    Bouvier, O. De; Yrieix, B.

    1995-12-31

    Dissimilar welds located on the primary coolant system of the French PWR plants exhibit grain boundary defects in the true austenitic zones of the first buttering layer. If grain boundaries reach the interface, they can extend to the martensitic band. Those defects are filled with compact oxides. In addition, the ferritic base metal presents some pits along the interface. Nowadays, three mechanisms are proposed to explain the initiation of those defects: stress corrosion cracking, intergranular corrosion and high temperature intergranular oxidation. This paper is dealing with the study of the mechanisms involved in the corrosion phenomenon. Intergranular corrosion tests performed on different materials show that only the first buttering layer, even with some {delta} ferrite, is sensitized. The results of stress corrosion cracking tests in water solutions show that intergranular cracking is possible on a bulk material representative of the first buttering layer. It is unlikely on actual dissimilar welds where the ferritic base metal protects the first austenitic layer by galvanic coupling. Therefore, the stress corrosion cracking assumption cannot explain the initiation of the defects in aqueous environment. The results of the investigations and of the corrosion studies led to the conclusion that the atmosphere could be the only possible aggressive environment. This conclusion is based on natural atmospheric exposure and accelerated corrosion tests carried out with SO{sub 2} additions in controlled atmosphere. They both induce a severe intergranular corrosion on true sensitized austenitic materials.

  1. Finite Element Based Thermal Modeling of Friction Welding of Dissimilar Materials

    NASA Astrophysics Data System (ADS)

    Hynes, N. Rajesh Jesudoss; Nagaraj, P.; Selvaraj, R. Meby

    Friction welding is a solid state joining process of joining either similar or dissimilar materials. Joining of ceramic/metal joints by friction welding has opened up new possibilities in many engineering applications. In the present work, thermal modeling of friction welding process has been carried out. Using Finite Element Approach (FEA), analytical solutions were arrived for different ceramic/metal combinations. The temperature distributions of cylindrical surfaces of the alumina and the metals are found by means of 1D heat transfer assumption considering the effect of convection. In the thermal analysis, interfacial temperature and thermal conductivity of the material play a significant role. Based on the obtained temperature distribution the graphs are plotted between the length of the joint and the temperatures. Thus the knowledge of the temperature joint distribution could be helpful in predicting the thermal cycle of the process, microstructure evolution and residual stress formation. Thus the obtained graph helps to study and predict the temperature distribution of both the materials.

  2. Microstructural Variations Across a Dissimilar 316L Austenitic: 9Cr Reduced Activation Ferritic Martensitic Steel Weld Joint

    NASA Astrophysics Data System (ADS)

    Thomas Paul, V.; Karthikeyan, T.; Dasgupta, Arup; Sudha, C.; Hajra, R. N.; Albert, S. K.; Saroja, S.; Jayakumar, T.

    2016-03-01

    This paper discuss the microstructural variations across a dissimilar weld joint between SS316 and 9Cr-RAFM steel and its modifications on post weld heat treatments (PWHT). Detailed characterization showed a mixed microstructure of austenite and martensite in the weld which is in agreement with the phases predicted using Schaeffler diagram based on composition measurements. The presence of very low volume fraction of δ-ferrite in SS316L has been identified employing state of the art electron back-scattered diffraction technique. PWHT of the ferritic steel did not reduce the hardness in the weld metal. Thermal exposure at 973 K (700 °C) showed a progressive reduction in hardness of weld joint with duration of treatment except in austenitic base metal. However, diffusion annealing at 1073 K (800 °C) for 100 hours resulted in an unexpected increase in hardness of weld metal, which is a manifestation of the dilution effects and enrichment of Ni on the transformation characteristics of the weld zone. Migration of carbon from ferritic steel aided the precipitation of fine carbides in the austenitic base metal on annealing at 973 K (700 °C); but enhanced diffusion at 1073 K (880 °C) resulted in coarsening of carbides and thereby reduction of hardness.

  3. Effect of Austenitic and Austeno-Ferritic Electrodes on 2205 Duplex and 316L Austenitic Stainless Steel Dissimilar Welds

    NASA Astrophysics Data System (ADS)

    Verma, Jagesvar; Taiwade, Ravindra V.

    2016-11-01

    This study addresses the effect of different types of austenitic and austeno-ferritic electrodes (E309L, E309LMo and E2209) on the relationship between weldability, microstructure, mechanical properties and corrosion resistance of shielded metal arc welded duplex/austenitic (2205/316L) stainless steel dissimilar joints using the combined techniques of optical, scanning electron microscope, energy-dispersive spectrometer and electrochemical. The results indicated that the change in electrode composition led to microstructural variations in the welds with the development of different complex phases such as vermicular ferrite, lathy ferrite, widmanstatten and intragranular austenite. Mechanical properties of welded joints were diverged based on compositions and solidification modes; it was observed that ferritic mode solidified weld dominated property wise. However, the pitting corrosion resistance of all welds showed different behavior in chloride solution; moreover, weld with E2209 was superior, whereas E309L exhibited lower resistance. Higher degree of sensitization was observed in E2209 weld, while lesser in E309L weld. Optimum ferrite content was achieved in all welds.

  4. Characterization of disk-laser dissimilar welding of titanium alloy Ti-6Al-4V to aluminum alloy 2024

    NASA Astrophysics Data System (ADS)

    Caiazzo, Fabrizia; Alfieri, Vittorio; Cardaropoli, Francesco; Corrado, Gaetano; Sergi, Vincenzo

    2013-02-01

    Both technical and economic reasons suggest to join dissimilar metals, benefiting from the specific properties of each material in order to perform flexible design. Adhesive bonding and mechanical joining have been traditionally used although adhesives fail to be effective in high-temperature environments and mechanical joining are not adequate for leak-tight joints. Friction stir welding is a valid alternative, even being difficult to perform for specific joint geometries and thin plates. The attention has therefore been shifted to laser welding. Interest has been shown in welding titanium to aluminum, especially in the aviation industry, in order to benefit from both corrosive resistance and strength properties of the former, and low weight and cost of the latter. Titanium alloy Ti-6Al-4V and aluminum alloy 2024 are considered in this work, being them among the most common ones in aerospace and automotive industries. Laser welding is thought to be particularly useful in reducing the heat affected zones and providing deep penetrative beads. Nevertheless, many challenges arise in welding dissimilar metals and the aim is further complicated considering the specific features of the alloys in exam, being them susceptible to oxidation on the upper surface and porosity formation in the fused zone. As many variables are involved, a systematic approach is used to perform the process and to characterize the beads referring to their shape and mechanical features, since a mixture of phases and structures is formed in the fused zone after recrystallization.

  5. Characterization of low alloy ferritic steel–Ni base alloy dissimilar metal weld interface by SPM techniques, SEM/EDS, TEM/EDS and SVET

    SciTech Connect

    Wang, Siyan; Ding, Jie; Ming, Hongliang; Zhang, Zhiming; Wang, Jianqiu

    2015-02-15

    The interface region of welded A508–Alloy 52 M is characterized by scanning probe microscope (SPM) techniques, scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM)/Energy Dispersive Spectroscopy (EDS) and scanning vibrate electrode technique (SVET). The regions along the welded A508–Alloy 52 M interface can be categorized into two types according to their different microstructures. In the type-I interface region, A508 and Alloy 52 M are separated by the fusion boundary, while in the type-II interface region, A508 and Alloy 52 M are separated by a martensite zone. A508, martensite zone and grain boundaries in Alloy 52 M are ferromagnetic while the Alloy 52 M matrix is paramagnetic. The Volta potentials measured by scanning Kelvin probe force microscopy (SKPFM) of A508, martensite zone and Alloy 52 M follow the order: V{sub 52} {sub M} > V{sub A508} > V{sub martensite}. The corrosion behavior of A508–Alloy 52 M interface region is galvanic corrosion, in which Alloy 52 M is cathode while A508 is anode. The martensite dissolves faster than Alloy 52 M, but slower than A508 in the test solution. - Highlights: • The A508–Alloy 52 M interface regions can be categorized into two types. • The chromium depleted region is observed along the Alloy 52 M grain boundary. • The Alloy 52 M grain boundaries which are close to the interface are ferromagnetic. • Martensite zone has lower Volta potential but higher corrosion resistance than A508.

  6. Integrity assessment of the ferritic / austenitic dissimilar weld joint between intermediate heat exchanger and steam generator in fast reactor

    SciTech Connect

    Jayakumar, T.; Laha, K.; Chandravathi, K. S.; Parameswaran, P.; Goyal, S.; Kumar, J. G.; Mathew, M. D.

    2012-07-01

    Integrity of the modified 9Cr-1Mo / alloy 800 dissimilar joint welded with Inconel 182 electrodes has been assessed under creep condition based on the detailed analysis of microstructure and stress distribution across the joint by finite element analysis. A hardness peak at the ferritic / austenitic weld interface and a hardness trough at the inter-critical heat affected zone (HAZ) in ferritic base metal developed. Un-tempered martensite was found at the ferritic / austenitic weld interface to impart high hardness in it; whereas annealing of martensitic structure of modified 9Cr-1Mo steel by inter-critical heating during welding thermal cycle resulted in hardness tough in the inter-critical HAZ. Creep tests were carried out on the joint and ferritic steel base metal at 823 K over a stress range of 160-320 MPa. The joint possessed lower creep rupture strength than its ferritic steel base metal. Failure of the joint at relatively lower stresses occurred at the ferritic / austenitic weld interface; whereas it occurred at inter-critical region of HAZ at moderate stresses. Cavity nucleation associated with the weld interface particles led to premature failure of the joint. Finite element analysis of stress distribution across the weld joint considering the micro-mechanical strength inhomogeneity across it revealed higher von-Mises and principal stresses at the weld interface. These stresses induced preferential creep cavitation at the weld interface. Role of precipitate in enhancing creep cavitation at the weld interface has been elucidated based on the FE analysis of stress distribution across it. (authors)

  7. Microstructures and microhardness at fusion boundary of 316 stainless steel/Inconel 182 dissimilar welding

    SciTech Connect

    Wang, Wei; Lu, Yonghao; Ding, Xianfei; Shoji, Tetsuo

    2015-09-15

    Microstructures and microhardness at fusion boundary of a weld joint were investigated in a 316 stainless steel/Inconel 182 dissimilar weldment. The results showed that there were two alternately distributed typical fusion boundaries, a narrow random boundary (possessed 15% in length) with a clear sharp interface and an epitaxial fusion one with (100){sub BM}//(100){sub WM} at the joint interface. The composition transition, microstructure and hardness across the fusion boundary strongly depended on the type of the fusion boundary. For the random boundary, there was a clear sharp interface and the composition transition with a width of 100 μm took place symmetrically across the grain boundary. For the epitaxial fusion one, however, there were Type-I and Type-II grain boundaries perpendicular and parallel to the epitaxial fusion boundary, respectively. The composition transition took place in the Inconel 182 weld side. Σ3 boundaries in the HAZ of 316SS side and Σ5 grain boundaries in weld metal were usually observed, despite the type of fusion boundary, however the former was much more in epitaxial fusion boundary. Microhardness was continuously decreased across the random fusion boundary from the side of Inconel 182 to 316SS, but a hardening phenomenon appeared in the epitaxial fusion boundary zone because of its fine cellular microstructure. - Highlights: • Two typical fusion boundaries alternately distributed in the fusion interface • The microstructure, composition and hardness across fusion boundary depended on its type. • Different regions in welded joint have different special CSL value boundaries. • Hardening phenomenon only appeared in the epitaxial fusion boundary.

  8. Multiphysical Modeling of Transport Phenomena During Laser Welding of Dissimilar Steels

    NASA Astrophysics Data System (ADS)

    Métais, A.; Matteï, S.; Tomashchuk, I.; Gaied, S.

    The success of new high-strength steels allows attaining equivalent performances with lower thicknesses and significant weight reduction. The welding of new couples of steel grades requires development and control of joining processes. Thanks to high precision and good flexibility, laser welding became one of the most used processes for joining of dissimilar welded blanks. The prediction of the local chemical composition in the weld formed between dissimilar steels in function of the welding parameters is essential because the dilution rate and the distribution of alloying elements in the melted zone determines the final tensile strength of the weld. The goal of the present study is to create and to validate a multiphysical numerical model studying the mixing of dissimilar steels in laser weld pool. A 3D modelling of heat transfer, turbulent flow and transport of species provides a better understanding of diffusion and convective mixing in laser weld pool. The present model allows predicting the weld geometry and element distribution. The model has been developed based on steady keyhole approximation and solved in quasi-stationary form in order to reduce the computation time. Turbulent flow formulation was applied to calculate velocity field. Fick law for diluted species was used to simulate the transport of alloying elements in the weld pool. To validate the model, a number of experiments have been performed: tests using pure 100 μm thick Ni foils like tracer and weld between a rich and poor manganese steels. SEM-EDX analysis of chemical composition has been carried out to obtain quantitative mapping of Ni and Mn distributions in the melted zone. The results of simulations have been found in good agreement with experimental data.

  9. Environmentally assisted cracking behavior of dissimilar metal weldments in simulated BWR coolant environments

    NASA Astrophysics Data System (ADS)

    Huang, J. Y.; Chiang, M. F.; Jeng, S. L.; Huang, J. S.; Kuo, R. C.

    2013-01-01

    The environmentally assisted cracking behavior of dissimilar metal (DM) welds, including Alloy 52-A 508 and Alloy 82-A508, under simulated BWR coolant conditions was studied. Effects of postweld heat treatment and sulfur content of the base metal on the corrosion fatigue and SCC growth rates of DM welds were evaluated. The crack growth rates for the DM weld heat-treated at 621 °C for 24 h were observed to be faster than those for the as-welded. But the DM weld heat-treated at 621 °C for 8 h + 400 °C for 200 h showed better SCC resistance than the as-welded. The longer the heat treatment at 621 °C, the higher the chromium carbides density along the grain boundary was observed. Sulfur could diffuse out of the base metal and segregate along the grain boundaries of the dilution zone, leading to weakening the grain boundary strength and the SCC resistance of the Alloy 52-A508 weld.

  10. Improvement of bonding properties of laser transmission welded, dissimilar thermoplastics by plasma surface treatment

    SciTech Connect

    Hopmann, Ch.; Weber, M.; Schöngart, M.; Sooriyapiragasam, S.; Behm, H.; Dahlmann, R.

    2015-05-22

    Compared to different welding methods such as ultrasonic welding, laser transmission welding is a relatively new technology to join thermoplastic parts. The most significant advantages over other methods are the contactless energy input which can be controlled very precisely and the low mechanical loads on the welded parts. Therefore, laser transmission welding is used in various areas of application, for example in medical technology or for assembling headlights in the automotive sector. However, there are several challenges in welding dissimilar thermoplastics. This may be due to different melting points on the one hand and different polarities on the other hand. So far these problems are faced with the intermediate layer technique. In this process a layer bonding together the two components is placed between the components. This means that an additional step in the production is needed to apply the extra layer. To avoid this additional step, different ways of joining dissimilar thermoplastics are investigated. In this regard, the improvement in the weldability of the dissimilar thermoplastics polyamide 6 (PA 6) and polypropylene (PP) by means of plasma surface modification and contour welding is examined. To evaluate the influence of the plasma surface modification process on the subsequent welding process of the two dissimilar materials, the treatment time as well as the storage time between treatment and welding are varied. The treatment time in pulsed micro wave excited oxygen plasmas with an electron density of about 1x10{sup 17} m{sup −3} is varied from 0.5 s to 120 s and the time between treatment and welding is varied from a few minutes up to a week. As reference, parts being made of the same polymer (PP and PA 6) are welded and tested. For the evaluation of the results of the welding experiments, short-time tensile tests are used to determine the bond strength. Without plasma treatment the described combination of PA 6/PP cannot be welded with

  11. Improvement of bonding properties of laser transmission welded, dissimilar thermoplastics by plasma surface treatment

    NASA Astrophysics Data System (ADS)

    Hopmann, Ch.; Weber, M.; Schöngart, M.; Sooriyapiragasam, S.; Behm, H.; Dahlmann, R.

    2015-05-01

    Compared to different welding methods such as ultrasonic welding, laser transmission welding is a relatively new technology to join thermoplastic parts. The most significant advantages over other methods are the contactless energy input which can be controlled very precisely and the low mechanical loads on the welded parts. Therefore, laser transmission welding is used in various areas of application, for example in medical technology or for assembling headlights in the automotive sector. However, there are several challenges in welding dissimilar thermoplastics. This may be due to different melting points on the one hand and different polarities on the other hand. So far these problems are faced with the intermediate layer technique. In this process a layer bonding together the two components is placed between the components. This means that an additional step in the production is needed to apply the extra layer. To avoid this additional step, different ways of joining dissimilar thermoplastics are investigated. In this regard, the improvement in the weldability of the dissimilar thermoplastics polyamide 6 (PA 6) and polypropylene (PP) by means of plasma surface modification and contour welding is examined. To evaluate the influence of the plasma surface modification process on the subsequent welding process of the two dissimilar materials, the treatment time as well as the storage time between treatment and welding are varied. The treatment time in pulsed micro wave excited oxygen plasmas with an electron density of about 1x1017 m-3 is varied from 0.5 s to 120 s and the time between treatment and welding is varied from a few minutes up to a week. As reference, parts being made of the same polymer (PP and PA 6) are welded and tested. For the evaluation of the results of the welding experiments, short-time tensile tests are used to determine the bond strength. Without plasma treatment the described combination of PA 6/PP cannot be welded with sufficient bond

  12. Microstructural Characteristics of a Stainless Steel/Copper Dissimilar Joint Made by Laser Welding

    NASA Astrophysics Data System (ADS)

    Chen, Shuhai; Huang, Jihua; Xia, Jun; Zhang, Hua; Zhao, Xingke

    2013-08-01

    The microstructures and its formation mechanism of a stainless steel/copper dissimilar joint by laser welding were investigated. It was found that the two modes of joining, i.e., welding-brazing and fusion welding, depend on different processing parameters. In the welding-brazing mode, the interface between copper and the fusion zone has scraggy morphology because the molten pool is frozen by solid copper with high thermal conductivity. The interdiffusion of elements occurs in the neighborhood of the interface, which leads to the metallurgy bond of the mode. In the fusion welding mode, the liquid phase in the fusion zone undergoes not only primary but also secondary liquid separation due to the high cooling rate and high supercooling level of laser welding. Some microcracks generated in the fusion zone by thermal stress mismatch are healed by liquid copper filling.

  13. Growth of lamellar pearlite in the weld zone between dissimilar steels

    NASA Astrophysics Data System (ADS)

    Nikulina, A. A.; Smirnov, A. I.; Bataev, I. A.; Bataev, A. A.; Popelyukh, A. I.

    2016-01-01

    Transmission electron microscopy is used to study the welds between high-carbon pearlitic and chromium-nickel austenitic steel workpieces performed by flash butt welding. It has been established that lamellar pearlite colonies alloyed with chromium and nickel are formed in the weld zones between dissimilar steels. Thin austenite interlayers have been detected in the center of ferrite plates. The structure formed presents the C-F-A-F-C-F-A-F (and so on) sequence of three plate-shaped phases. The ferrite-cementite structure in alloyed-pearlite colonies is finer than that in unalloyed pearlite.

  14. A numerical and experimental study of ultrasonic metal welding

    NASA Astrophysics Data System (ADS)

    Al-Sarraf, Z.; Lucas, M.; Harkness, P.

    2012-12-01

    Ultrasonic metal welding has been the subject of ongoing research and development, most recently concentrating on metal joining in miniature devices, for example to allow solder-free wire bonding. As well as at the small scale, there are also opportunities to research the joining of thicker sheet metals and to widen the range of similar and dissimilar materials that can be successfully joined using this technology. This study presents the design, characterisation and test of a lateral-drive ultrasonic metal spot welding device. The ultrasonic metal spot welding horn is modelled using finite element analysis (FEA) and its vibration behaviour is characterised experimentally to ensure ultrasonic energy is delivered effectively to the weld coupon. The welding stack and fixtures are then designed and mounted on a test machine to allow a series of experiments to be conducted for various welding and ultrasonic parameters. Weld strength is subsequently analysed using tensile-shear tests. The results show how the weld strength is particularly sensitive to the combination of clamping force and ultrasonic vibration amplitude of the welding tip, but there are optimal combinations of these and also limits that must be clearly identified.

  15. Metal Working and Welding Operations.

    ERIC Educational Resources Information Center

    Marine Corps Inst., Washington, DC.

    This student guide, one of a series of correspondence training courses designed to improve the job performance of members of the Marine Corps, deals with the skills needed by metal workers and welders. Addressed in the six individual units of the course are the following topics: weldable metals and their alloys, arc welding, gas welding,…

  16. Tensile and Fatigue Properties of Single and Multiple Dissimilar Welded Joints of DP980 and HSLA

    NASA Astrophysics Data System (ADS)

    Cui, Q. L.; Parkes, D.; Westerbaan, D.; Nayak, S. S.; Zhou, Y.; Saha, D. C.; Liu, D.; Goodwin, F.; Bhole, S.; Chen, D. L.

    2017-01-01

    The present study focused on single and multiple dissimilar joints between DP980 and high-strength low-alloy (HSLA) galvanized steels. The tensile properties of the dissimilar joint between the strong DP980 and the relatively soft HSLA reflected only the properties of HSLA with plastic deformation, and final fracture took place entirely in HSLA. The fatigue properties of the dissimilar joints were more intriguing, with the strong DP980 outperforming at high stress amplitude and the ductile HSLA outperforming at low stress amplitude. For different load amplitudes, fatigue failure occurred in different materials and at different locations. The fatigue strength of DP980 was more negatively impaired by weld defects than that of HSLA.

  17. Tensile and Fatigue Properties of Single and Multiple Dissimilar Welded Joints of DP980 and HSLA

    NASA Astrophysics Data System (ADS)

    Cui, Q. L.; Parkes, D.; Westerbaan, D.; Nayak, S. S.; Zhou, Y.; Saha, D. C.; Liu, D.; Goodwin, F.; Bhole, S.; Chen, D. L.

    2017-02-01

    The present study focused on single and multiple dissimilar joints between DP980 and high-strength low-alloy (HSLA) galvanized steels. The tensile properties of the dissimilar joint between the strong DP980 and the relatively soft HSLA reflected only the properties of HSLA with plastic deformation, and final fracture took place entirely in HSLA. The fatigue properties of the dissimilar joints were more intriguing, with the strong DP980 outperforming at high stress amplitude and the ductile HSLA outperforming at low stress amplitude. For different load amplitudes, fatigue failure occurred in different materials and at different locations. The fatigue strength of DP980 was more negatively impaired by weld defects than that of HSLA.

  18. Dissimilar Friction Stir Welding Between UNS S31603 Austenitic Stainless Steel and UNS S32750 Superduplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Theodoro, Maria Claudia; Pereira, Victor Ferrinho; Mei, Paulo Roberto; Ramirez, Antonio Jose

    2015-02-01

    In order to verify the viability of dissimilar UNS S31603 austenitic and UNS S32750 superduplex stainless steels joined by friction stir welding, 6-mm-thick plates were welded using a PCBN-WRe tool. The welded joints were performed in position control mode at rotational speeds of 100 to 300 rpm and a feed rate of 100 mm/min. The joints performed with 150 and 200 rpm showed good appearance and no defects. The metallographic analysis of both joints showed no internal defects and that the material flow pattern is visible only in the stirred zone (SZ) of the superduplex steel. On the SZ top, these patterns are made of regions of different phases (ferrite and austenite), and on the bottom and central part of the SZ, these patterns are formed by alternated regions of different grain sizes. The ferrite grains in the superduplex steel are larger than those in the austenitic ones along the SZ and thermo-mechanically affected zone, explained by the difference between austenite and ferrite recrystallization kinetics. The amount of ferrite islands present on the austenitic steel base metal decreased near the SZ interface, caused by the dissolving of the ferrite in austenitic matrix. No other phases were found in both joints. The best weld parameters were found to be 200 rpm rotation speed, 100 mm/min feed rate, and tool position control.

  19. Microstructure and Mechanical Properties of Laser-Welded Joints of Ti-22Al-25Nb/TA15 Dissimilar Titanium Alloys

    NASA Astrophysics Data System (ADS)

    Li, Dalong; Hu, Shengsun; Shen, Junqi; Zhang, Hao; Bu, Xianzheng

    2016-05-01

    Laser beam welding (LBW) was applied to join 1-mm-thick dissimilar titanium alloys, Ti-22Al-25Nb (at.%) and TA15, and the microstructure and mechanical properties of the welded joints were systematically analyzed. Defect-free joints were obtained, and the fusion zone mainly consisted of B2 and martensitic α' phases because of the uneven distribution of the β phase stabilizer and rapid cooling rate of LBW. The phase compositions of the heat-affected zone varied with the different thermal cycles during the welding process. The different microstructures of the dissimilar titanium alloys led to an unsymmetrical hardness profile, with the welded seam exhibiting the lowest value of 271 HV. In room-temperature tensile tests, the fractures all occurred preferentially in the fusion zone. The strengths of the joints were close to those of the base metal but with prominently decreasing ductility. In tensile tests performed at 550 °C, all the joints fractured in the TA15 base metal, and the strength and plasticity of the welds were equivalent to those of the TA15 base metal.

  20. Joining of dissimilar AZ31B magnesium alloy and SS400 mild steel by hybrid gas tungsten arc friction stir welding

    NASA Astrophysics Data System (ADS)

    Joo, SungMin

    2013-11-01

    The joining of dissimilar materials, magnesium alloy (AZ31B) and mild steel (SS400), was performed using a hybrid gas tungsten arc-friction stir welding (HGTAFSW) method that applied a preceding gas tungsten arc welding (GTAW) preheating heat source to a mild steel plate surface during friction stir welding (FSW). The mechanical and microstructural characteristics of the HGTAFS welds were evaluated and compared to those of FS welds to confirm the effect of the additional GTAW preheating heat source. The tensile strength of the HGTAFS welds was approximately 91% of that of the magnesium alloy base metal but higher than that of the FS welds. This was attributed to the enhanced material plastic flow and partial annealing effect in the magnesium alloy and mild steel materials by GTAW reheating of the mild steel side, which induced a significant increase in the elongation of the welds. The concentration profiles indicated that no intermetallic FeAl and FeAl3 compounds had formed according to the phase diagram, which led to a decrease in joint strength. Overall, the use of HGTAFSW by applying a GTAW preheating heat source to a mild steelplate surface resulted in a mechanically sounder and metallurgically defect-free welds compared to FSW.

  1. Laser beam welding of any metal.

    SciTech Connect

    Leong, K. H.

    1998-10-01

    The effect of a metal's thermophysical properties on its weldability are examined. The thermal conductivity, melting point, absorptivity and thermal diffusivity of the metal and the laser beam focused diameter and welding speed influence the minimum beam irradiance required for melting and welding. Beam diameter, surface tension and viscosity of the molten metal affect weld pool stability and weld quality. Lower surface tension and viscosity increases weld pool instability. With larger beam diameters causing wider welds, dropout also increases. Effects of focused beam diameter and joint fitup on weldability are also examined. Small beam diameters are sensitive to beam coupling problems in relation to fitup precision in addition to beam alignment to the seam. Welding parameters for mitigating weld pool instability and increasing weld quality are derived from the above considerations. Guidelines are presented for the tailoring of welding parameters to achieve good welds. Weldability problems can also be anticipated from the properties of a metal.

  2. Microstructural and Mechanical Characterization of a Dissimilar Friction Stir-Welded AA5083-AA7B04 Butt Joint

    NASA Astrophysics Data System (ADS)

    Chen, Yu; Ding, Hua; Cai, Zhihui; Zhao, Jingwei; Li, Jizhong

    2016-12-01

    Friction stir welding (FSW) has been used for joining AA5083 and AA7B04 alloy sheets with the aim of studying the microstructure and the mechanical properties of dissimilar FSW joints obtained by varying the initial base metal state of AA7B04 alloy. The results show that the initial base metal state has a significant impact on the material flow during dissimilar FSW. As compared with the joints placing hard alloy (artificially aged AA7B04-AA or naturally aged AA7B04-NA) on the retreating side, it becomes easier transporting AA5083 from advancing side to retreating side when soft alloy (annealed AA7B04-O) is placed on the retreating side. The atomic diffusion does not occur at the interface between AA5083 and AA7B04, indicating that the mixing of the two materials is merely mechanical. Grain refinement is observed in the stir zone. The failure location during tensile tests is different depending on the initial base metal state. The joints (AA5083/AA7B04-AA and AA5083/AA7B04-O) fail in the base metal on the soft material side which corresponds to the minimum values in hardness profiles. Differently, the joints (AA5083/AA5083 and AA5083/AA7B04-O) fail in the stir zone due to the presence of defects including "zigzag line," kissing bond and discontinuous voids.

  3. Microstructural and Mechanical Characterization of a Dissimilar Friction Stir-Welded AA5083-AA7B04 Butt Joint

    NASA Astrophysics Data System (ADS)

    Chen, Yu; Ding, Hua; Cai, Zhihui; Zhao, Jingwei; Li, Jizhong

    2017-02-01

    Friction stir welding (FSW) has been used for joining AA5083 and AA7B04 alloy sheets with the aim of studying the microstructure and the mechanical properties of dissimilar FSW joints obtained by varying the initial base metal state of AA7B04 alloy. The results show that the initial base metal state has a significant impact on the material flow during dissimilar FSW. As compared with the joints placing hard alloy (artificially aged AA7B04-AA or naturally aged AA7B04-NA) on the retreating side, it becomes easier transporting AA5083 from advancing side to retreating side when soft alloy (annealed AA7B04-O) is placed on the retreating side. The atomic diffusion does not occur at the interface between AA5083 and AA7B04, indicating that the mixing of the two materials is merely mechanical. Grain refinement is observed in the stir zone. The failure location during tensile tests is different depending on the initial base metal state. The joints (AA5083/AA7B04-AA and AA5083/AA7B04-O) fail in the base metal on the soft material side which corresponds to the minimum values in hardness profiles. Differently, the joints (AA5083/AA5083 and AA5083/AA7B04-O) fail in the stir zone due to the presence of defects including "zigzag line," kissing bond and discontinuous voids.

  4. Three-Dimensional Thermomechanical Simulation and Experimental Validation on Failure of Dissimilar Material Welds

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    Dissimilar material weld joints, consisting of low-alloy steel and 304LN austenitic stainless steel (SS), have critical application in boiling water reactors in the nuclear industry. It was predicted that phase transformation adjacent to the fusion boundary and stress distribution across the transition joint play a key role in the structural degeneration of these welds. Quantitatively, to evaluate their contribution, two different joints were considered. One was fabricated with buttering material 309L SS (M/S Mishra Dhatu Nigam Limited, Hyderabad, India), and the other was produced with buttering material IN182 (M/S Mishra Dhatu Nigam Limited, Hyderabad, India). Base materials remained the same for both. Thermomechanical simulation on dissimilar material welds was performed using finite-element modeling to predict the thermal effect and stress prone area. Temperature-dependent thermal and structural properties were considered for simulation. Simulation results were compared with microstructural characteristics, and data were obtained from the in-situ tensile test. Simulation results exhibited that stress was at maximum in the buttering material and made the zone weaker with respect to adjacent areas. During the validation of results, it was observed that failure occurred through buttering material and endorsed the inference. The variation in mechanical properties of the two welds was explained considering the effect of thermal state and stress distribution.

  5. Effect of Peculiarities of Heat Transfer, Diffusion and Phase Transformation on Joint Formation During Welding of Dissimilar Materials by High Power Fiber Laser

    NASA Astrophysics Data System (ADS)

    Turichin, Gleb; Klimova, Olga; Valdaytseva, Ekaterina

    The article describes mathematical models of diffusion and thermal processes for welding of dissimilar materials and kinetic model of diffusion-controlled deposition and growth of intermetallic inclusions in the weld. Developed models were combined and implemented in the model of weld joint formation for dissimilar materials. To verify a model the microstructure analysis of weld joints and elemental analysis in the diffusion zone by SEM has been made for welding of systems Fe-Cu, Al-Ti, Fe-Al. The good agreement between calculated and experimental data has been obtained. Examples of developed technologies of welding of dissimilar materials using high-power fiber lasers were discussed also.

  6. Silver plating ensures reliable diffusion bonding of dissimilar metals

    NASA Technical Reports Server (NTRS)

    1967-01-01

    Dissimilar metals are reliably joined by diffusion bonding when the surfaces are electroplated with silver. The process involves cleaning and etching, anodization, silver striking, and silver plating with a conventional plating bath. It minimizes the formation of detrimental intermetallic phases and provides greater tolerance of processing parameters.

  7. Formation of a diffusion-based intermetallic interface layer in friction stir welded dissimilar Al-Cu lap joints

    NASA Astrophysics Data System (ADS)

    Marstatt, R.; Krutzlinger, M.; Luderschmid, J.; Zaeh, M. F.; Haider, F.

    2017-03-01

    The joining of dissimilar metals is an important issue in modern lightweight design. Friction Stir Welding (FSW) is suitable for this task since the solidus temperature is usually not exceeded during the process. As a consequence, dissimilar joints can be produced with a minimum of deteriorating intermetallic phases. The latest studies showed the formation of intermetallic layers at the bonding interface with no significant negative influence on the seam quality. In this study, those intermetallic nanolayers at the interface of aluminium / copper lap joints were analysed. For the experiments, the commercially pure alloys EN AW-1050 and CW008A were chosen. The process temperature changed with respect to the parameter setup and was measured at different locations of the seam. The intermetallic layers at the interface were analysed by scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM). The experiments show that the thickness of the interlayer clearly correlates with the process temperature using an Arrhenius equation. It is supposed, that the rotating probe removes the oxide layers of the metal surfaces and a metallic bonding between the Al- and the Cu-phase is formed. Due to the elevated temperature after the probe has passed, the intermetallic layer has emerged by interdiffusion.

  8. Intermediate temperature joining of dissimilar metals

    SciTech Connect

    Hosking, F.M.; Stephens, J.J.; Rejent, J.A.

    1999-04-01

    Duplex stainless steel and silver-nickel-silver laminate were jointed to copper with a gold-germanium filler metal. Test joints were processed at, or below, 450 C (842 F) to assure meeting minimum base metal yield strength requirements. Creep and tensile properties of the bulk filler metal candidates, including a gold-indium alloy, were measured. A constitutive model, based on the Garofalo sinh equation, was developed from the creep data for use in predicting residual stresses in actual joints. Wetting behavior, interfacial reactions and joint microstructures were investigated, with samples processed in a vacuum between 400 to 550 C. Prototype joints were tested in shear. The Au-12 Ge filler metal offered the best alternative to the higher melting braze alloys. The alloy exhibited excellent wetting and creep behavior, with low contact angles, generally less than 20 deg, and good creep relaxation under typical loading conditions. As-fabricated shear test specimens yielded average joint strengths of 160 MPa (23 ksi).

  9. A parameter governing the melting induced at the micrometer level in a dissimilar metal wire system by Joule heating

    NASA Astrophysics Data System (ADS)

    Tohmyoh, Hironori; Sunagawa, Takuya

    2015-06-01

    In this paper, we deal with the phenomenon of melting at the point of contact between dissimilar metals by Joule heating. A heat conduction model for this dissimilar metal wire system is considered and the current required to sever the wire system by Joule heating is determined. The position at which the wire system severs depends on the ratio of the lengths of the two wires. Whereas this dependency is discontinuous, the current required to sever the wire is found to be continuous with respect to the ratio of the wire lengths, and the behaviors of the position and the current for severing the wire system are found to be classified into three regions. Based on these findings, a parameter that governs the melting phenomenon at the micrometer level for different ratios of wire lengths is proposed. Attempts were made to weld 25 μm thick Cu and Al wires of various lengths together by Joule heating. Moreover, the conditions for stably welding dissimilar metal wires together can be found quantitatively using the parameter proposed in this paper. It is noted that the welding condition described by the proposed parameter is independent with respect to the ratio of the lengths of the two wires in the respective regions.

  10. 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.

  11. Numerical Simulation of the Inertia Friction Welding Process of Dissimilar Materials

    NASA Astrophysics Data System (ADS)

    El-Hadek, Medhat A.

    2014-12-01

    Three-dimensional axisymmetric finite element analyses have been performed to analyze the coupled thermo-mechanical oscillatory transient problem of friction welding of two dissimilar hollow cylinders. The analysis included the effect of conduction and convection heat transfer implementing three independent variables specifically the welding time, the rotational velocity, and the thrust pressure. Experimental evaluation of the non-linear copper and Aluminum 6061 stress-strain responses, the thermal conductivities, and the specific heat coefficients were conducted using an environmental-controlled compartment for at least four different temperatures. These results were incorporated in the finite element model calculating a real joint transient temperature distribution and a full field view of the residual stresses in weldment. Variables of angular rotational velocity of (200, 400, and 600 rpm), thrust pressure of (10E5, 10E6, and 10E7 Pa), and total welding time of (1, 2, and 4 seconds) were used in the model simulation. The optimum welding conditions were selected using Taguchi method. Finally, the deformation shape predicted by the finite element simulations was compared to the deformations obtained by the experimental results.

  12. A Numerical Simulation for Dissimilar Aluminum Alloys Joined by Friction Stir Welding

    NASA Astrophysics Data System (ADS)

    Hamilton, Carter; Kopyściański, Mateusz; Węglowska, Aleksandra; Dymek, Stanisław; Pietras, Adam

    2016-09-01

    Dissimilar aluminum alloy sheets of 2017A-T451 and 7075-T651 (6 mm thickness) were friction stir welded in a butt weld configuration. A numerical simulation of the joining process was developed to visualize the material flow patterns and temperature distribution and to correlate the microstructure to the hardness behavior. Due to the complementary downward flow of surface material into the workpiece thickness and upward flow of mid-plane and bottom-plane material, the weld nugget is composed of alternating layers of 7075 and 2017A. These layers have unique temperature histories depending on the material's initial location within the cross section; therefore, they also have distinctive precipitate distributions. Supersaturated surface material flows into the process zone and forms a core in which GP zones reprecipitate upon cooling. Mid-plane and bottom-plane material flow toward the workpiece surface and encompass the surface material core. Within this region, the weld temperatures overage the equilibrium θ phase in 2017A, decreasing the hardness, and at the same time, dissolve the equilibrium η/ T phase in the 7075, leading to reprecipitation of GP zones upon cooling and a hardness recovery.

  13. Mechanics and mechanisms of ultrasonic metal welding

    NASA Astrophysics Data System (ADS)

    de Vries, Edgar

    During ultrasonic welding of sheet metal, normal and shear forces act on the parts to be welded and the weld interface. These forces are a result of the ultrasonic vibrations of the tool, pressed onto the parts to be welded. Furthermore they determine the weld quality and the power that is needed to produce the weld. The main goal in this study is to measure and calculate the tangential forces during ultrasonic metal welding that act on the parts and the weld interface and correlate them to weld quality. In this study a mechanics based model was developed which included a model for the temperature generation during welding and its effect on the mechanical material properties. This model was then used to calculate the interface forces during welding. The model results were in good agreement with the experimental results, which included the measured shear force during welding. With the knowledge of the forces that act at the interface it might be possible to control weld quality (strength) and avoid sonotrode welding (sticking of the sonotrode to the parts). Without a solution to these two problems USMW will never be applicable to large scale automated production use, despite its advantages. In the experiments the influence of part dimensions, friction coefficient, normal force and vibration amplitude on weld quality and sonotrode adhesion were examined. The presented model is capable of predicting and explaining unfavorable welding conditions, therefore making it possible to predetermine weld locations on larger parts or what surface preparation of the parts to be welded would lead to an improved welding result. Furthermore shear force at the anvil measured during welding could be correlated to changing welding conditions. This is a new approach of explaining the process of USMW, because it is based on mechanical considerations. The use of a shear force measuring anvil has the potential to be implemented into welding systems and the shear force would provide an

  14. Characterization of microstructure and texture across dissimilar super duplex/austenitic stainless steel weldment joint by super duplex filler metal

    SciTech Connect

    Eghlimi, Abbas; Shamanian, Morteza; Eskandarian, Masoomeh; Zabolian, Azam; Szpunar, Jerzy A.

    2015-08-15

    In the present paper, microstructural changes across an as-welded dissimilar austenitic/duplex stainless steel couple welded by a super duplex stainless steel filler metal using gas tungsten arc welding process is characterized with optical microscopy and electron back-scattered diffraction techniques. Accordingly, variations of microstructure, texture, and grain boundary character distribution of base metals, heat affected zones, and weld metal were investigated. The results showed that the weld metal, which was composed of Widmanstätten austenite side-plates and allotriomorphic grain boundary austenite morphologies, had the weakest texture and was dominated by low angle boundaries. The welding process increased the ferrite content but decreased the texture intensity at the heat affected zone of the super duplex stainless steel base metal. In addition, through partial ferritization, it changed the morphology of elongated grains of the rolled microstructure to twinned partially transformed austenite plateaus scattered between ferrite textured colonies. However, the texture of the austenitic stainless steel heat affected zone was strengthened via encouraging recrystallization and formation of annealing twins. At both interfaces, an increase in the special character coincident site lattice boundaries of the primary phase as well as a strong texture with <100> orientation, mainly of Goss component, was observed. - Graphical abstract: Display Omitted - Highlights: • Weld metal showed local orientation at microscale but random texture at macroscale. • Intensification of <100> orientated grains was observed adjacent to the fusion lines. • The austenite texture was weaker than that of the ferrite in all duplex regions. • Welding caused twinned partially transformed austenites to form at SDSS HAZ. • At both interfaces, the ratio of special CSL boundaries of the primary phase increased.

  15. 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.

  16. Gas Metal Arc Welding. Welding Module 5. Instructor's Guide.

    ERIC Educational Resources Information Center

    Missouri Univ., Columbia. Instructional Materials Lab.

    This guide is intended to assist vocational educators in teaching an eight-unit module in gas metal arc welding. The module is part of a welding curriculum that has been designed to be totally integrated with Missouri's Vocational Instruction Management System. The following topics are covered in the module: safety and testing, gas metal arc…

  17. Method for controlling gas metal arc welding

    DOEpatents

    Smartt, Herschel B.; Einerson, Carolyn J.; Watkins, Arthur D.

    1989-01-01

    The heat input and mass input in a Gas Metal Arc welding process are controlled by a method that comprises calculating appropriate values for weld speed, filler wire feed rate and an expected value for the welding current by algorithmic function means, applying such values for weld speed and filler wire feed rate to the welding process, measuring the welding current, comparing the measured current to the calculated current, using said comparison to calculate corrections for the weld speed and filler wire feed rate, and applying corrections.

  18. Method for controlling gas metal arc welding

    DOEpatents

    Smartt, H.B.; Einerson, C.J.; Watkins, A.D.

    1987-08-10

    The heat input and mass input in a Gas Metal Arc welding process are controlled by a method that comprises calculating appropriate values for weld speed, filler wire feed rate and an expected value for the welding current by algorithmic function means, applying such values for weld speed and filler wire feed rate to the welding process, measuring the welding current, comparing the measured current to the calculated current, using said comparison to calculate corrections for the weld speed and filler wire feed rate, and applying corrections. 3 figs., 1 tab.

  19. Simulation on friction taper plug welding of AA6063-20Gr metal matrix composite

    NASA Astrophysics Data System (ADS)

    Hynes, N. Rajesh Jesudoss; Nithin, Abeyram M.

    2016-05-01

    Friction taper plug welding a variant of friction welding is useful in welding of similar and dissimilar materials. It could be used for joining of composites to metals in sophisticated aerospace applications. In the present work numerical simulation of friction taper plug welding process is carried out using finite element based software. Graphite reinforced AA6063 is modelled using the software ANSYS 15.0 and temperature distribution is predicted. Effect of friction time on temperature distribution is numerically investigated. When the friction time is increased to 30 seconds, the tapered part of plug gets detached and fills the hole in the AA6063 plate perfectly.

  20. 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.

  1. 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.

  2. Effect of Intermetallic Compound Phases on the Mechanical Properties of the Dissimilar Al/Cu Friction Stir Welded Joints

    NASA Astrophysics Data System (ADS)

    Khodir, S. A.; Ahmed, M. M. Z.; Ahmed, Essam; Mohamed, Shaymaa M. R.; Abdel-Aleem, H.

    2016-11-01

    Types and distribution of intermetallic compound phases and their effects on the mechanical properties of dissimilar Al/Cu friction stir welded joints were investigated. Three different rotation speeds of 1000, 1200 and 1400 rpm were used with two welding speeds of 20 and 50 mm/min. The results show that the microstructures inside the stir zone were greatly affected by the rotation speed. Complex layered structures that containing intermetallic compound phases such as CuAl2, Al4Cu9 were formed in the stir zone. Their amount found to be increased with increasing rotation speed. However, the increasing of the rotation speed slightly lowered the hardness of the stir zone. Many sharp hardness peaks in the stir zones were found as a result of the intermetallic compounds formed, and the highest peaks of 420 Hv were observed at a rotation speed of 1400 rpm. The joints ultimate tensile strength reached a maximum value of 105 MPa at the rotation speed of 1200 rpm and travel speed of 20 mm/min with the joint efficiency ranged between 88 and 96% of the aluminum base metal. At the travel speed of 50 mm/min, the maximum value of the ultimate tensile strength was 96 MPa at rotation speed of 1400 rpm with the joint efficiency ranged between 79 and 90%. The fracture surfaces of tensile test specimens showed no evidence for the effect of the brittle intermetallic compounds in the stir zones on the tensile strength of the joints.

  3. 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.

  4. Shielded Metal Arc Welding. Welding Module 4. Instructor's Guide.

    ERIC Educational Resources Information Center

    Missouri Univ., Columbia. Instructional Materials Lab.

    This guide is intended to assist vocational educators in teaching an eight-unit module in shielded metal arc welding. The module is part of a welding curriculum that has been designed to be totally integrated with Missouri's Vocational Instruction Management System. The following topics are covered in the module: safety; theory, power sources, and…

  5. Site-Dependent Tension Properties of Inertia Friction-Welded Joints Made From Dissimilar Ni-based Superalloys

    NASA Astrophysics Data System (ADS)

    Senkov, O. N.; Mahaffey, D. W.; Semiatin, S. L.; Woodward, C.

    2015-03-01

    Microstructure, tensile properties, and fracture behavior of the inertia friction weld joints of dissimilar superalloys, cast Mar-M247 and wrought LSHR, were studied to assess the weld quality. Tensile tests were conducted at 23 and 704 °C on the samples containing different areas of the weld interface of the same welded material. The stress-strain curves were registered at different axial distances from the weld interface. In all tested samples, plastic deformation was localized on Mar-M247 side, outside the heat-affected zone (HAZ), and the resistance to plastic deformation of Mar-M247 increased with a decrease in the distance from the weld interface inside HAZ. Only elastic deformation occurred on the LSHR side. Fracture occurred on the Mar-M247 side, outside HAZ, or at the weld interface. In the latter case, welding defects in the form of clusters of nanometer-sized oxide and carbide particles were observed at the fracture surfaces. These results revealed that the IFW process is capable of producing the weld joints between Mar-M247 and LSHR with the fracture strength higher than that of Mar-M247. However, optimization of the IFW processing parameters is required to minimize clustering of oxide/carbide particles at the weld interface in this alloy pair.

  6. Local mechanical properties of Alloy 82/182 dissimilar weld joint between SA508 Gr.1a and F316 SS at RT and 320C

    SciTech Connect

    Byun, Thak Sang; Kim, Jin Weon

    2009-01-01

    This paper presents the variations of local mechanical and microstructural properties in dissimilar metal weld joints consisting of the SA508 Gr.1a ferritic steel, Alloy 82/182 filler metal, and F316 austenitic stainless steel. Flat or round tensile specimens and transmission electron microscopy disks were taken from the base metals, welds, and heat-affected zones (HAZ) of the joints and tested at room temperature (RT) and/or at 320 C. The tensile test results indicated that the mechanical property was relatively uniform within each material zone, but varied considerably between different zones. Further, significant variations were observed both in the austenitic HAZ of F316 SS and in the ferritic HAZ of SA508 Gr.1a. The yield stress (YS) of the weld metal was under-matched with respect to the HAZs of SA508 Gr.1a and F316 SS by 0.78 to 0.92, although the YS was over-matched with respect to both base metals. The minimum ductility occurred in the HAZ of SA508 Gr.1 at both test temperatures. The plastic instability stress also varied considerably in the weld joints, with minimum values occurring in the SA508 Gr.1a base metal at RT and in the HAZ of F316 SS at 320 C, suggesting that the probability of ductile failure caused by a unstable deformation at the Alloy 82/182 buttering layer is low. Within the HAZ of SA508 Gr.1a, the gradient of the YS and ultimate tensile strength (UTS) was significant, primarily because of the different microstructures produced by the phase transformation during the welding process. The increment of YS was unexpectedly high in the HAZ of F316 SS, which was explained by the strain hardening induced by a strain mismatch between the weldment and the base metal. This was confirmed by the transmission electron micrographs showing high dislocation density in the HAZ.

  7. Characterization of microstructure and texture across dissimilar super duplex/austenitic stainless steel weldment joint by austenitic filler metal

    SciTech Connect

    Eghlimi, Abbas; Shamanian, Morteza; Eskandarian, Masoomeh; Zabolian, Azam; Szpunar, Jerzy A.

    2015-08-15

    The evolution of microstructure and texture across an as-welded dissimilar UNS S32750 super duplex/UNS S30403 austenitic stainless steel joint welded by UNS S30986 (AWS A5.9 ER309LMo) austenitic stainless steel filler metal using gas tungsten arc welding process was evaluated by optical micrography and EBSD techniques. Due to their fabrication through rolling process, both parent metals had texture components resulted from deformation and recrystallization. The weld metal showed the highest amount of residual strain and had large austenite grain colonies of similar orientations with little amounts of skeletal ferrite, both oriented preferentially in the < 001 > direction with cub-on-cube orientation relationship. While the super duplex stainless steel's heat affected zone contained higher ferrite than its parent metal, an excessive grain growth was observed at the austenitic stainless steel's counterpart. At both heat affected zones, austenite underwent some recrystallization and formed twin boundaries which led to an increase in the fraction of high angle boundaries as compared with the respective base metals. These regions showed the least amount of residual strain and highest amount of recrystallized austenite grains. Due to the static recrystallization, the fraction of low degree of fit (Σ) coincident site lattice boundaries, especially Σ3 boundaries, was increased in the austenitic stainless steel heat affected zone, while the formation of subgrains in the ferrite phase increased the content of < 5° low angle boundaries at that of the super duplex stainless steel. - Graphical abstract: Display Omitted - Highlights: • Extensive grain growth in the HAZ of austenitic stainless steel was observed. • Intensification of < 100 > orientated grains was observed adjacent to both fusion lines. • Annealing twins with Σ3 CSL boundaries were formed in the austenite of both HAZ. • Cub-on-cube OR was observed between austenite and ferrite in the weld metal.

  8. Fatigue Behaviors of Self-Piercing Rivets Joining Similar and Dissimilar Sheet Metals

    SciTech Connect

    Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2007-01-01

    This paper summarizes the fatigue test results of self-piercing rivet (SPR) joints between similar and dissimilar sheet metals. The influences of material grades, material thickness, piercing direction and the use of structural adhesive on the rivet samples’ fatigue behaviors were investigated. Fatigue test results indicate that SPR joints have superior fatigue strength than resistance spot weld (RSW) joints for the same material combinations. The application of structure adhesive also significantly enhances the fatigue strength of the joint samples; this is particularly true for the lap shear loading configuration. In addition, different piercing directions for SPR joints have a noticeable effect on the static and fatigue strength of the joints. The joint fatigue results presented in this paper can offer design engineers with the durability data for SPR joints with these material combinations. Moreover, it will provide manufacturing engineers with some insights on the effects of different manufacturing parameters on the strength and durability of these joints.

  9. Measurement of the Casimir force between dissimilar metals.

    PubMed

    Decca, R S; López, D; Fischbach, E; Krause, D E

    2003-08-01

    The first precise measurement of the Casimir force between dissimilar metals is reported. The attractive force, between a Cu layer evaporated on a microelectromechanical torsional oscillator and an Au layer deposited on an Al2O3 sphere, was measured dynamically with a noise level of 6 fN/sqrt[Hz]. Measurements were performed for separations in the 0.2-2 micro m range. The results agree to better than 1% in the 0.2-0.5 micro m range with a theoretical model that takes into account the finite conductivity and roughness of the two metals. The observed discrepancies, which are much larger than the experimental precision, can be attributed to a lack of a complete characterization of the optical properties of the specific samples used in the experiment.

  10. Wiping Metal Transfer in Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur C., Jr.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Much evidence suggests that as the friction stir pin-tool moves along a weld seam the displacement of metal takes place by a wiping action at the surface of a plug of metal that rotates with the tool. The wiping model is explained and some consequences for the friction stir welding process are drawn.

  11. Investigations on Laser Beam Welding of Different Dissimilar Joints of Steel and Aluminum Alloys for Automotive Lightweight Construction

    NASA Astrophysics Data System (ADS)

    Seffer, Oliver; Pfeifer, Ronny; Springer, André; Kaierle, Stefan

    Due to the enormous potential of weight saving, and the consequential reduction of pollutant emissions, the use of hybrid components made of steel and aluminum alloys is increasing steadily, especially concerning automotive lightweight construction. However, thermal joining of steel and aluminum is still being researched, due to a limited solubility of the binary system of iron and aluminum causing the formation of hard and brittle intermetallic phases, which decrease the strength and the formability of the dissimilar seam. The presented results show the investigation of laser beam welding for joining different dissimilar hybrid components of the steel materials HX220LAD+Z100, 22MnB5+AS150 and 1.4301, as well as the aluminum alloy AA6016-T4 as a lap joint. Among other things, the influences of the energy per unit length, the material grade, the sheet thickness t, the weld type (lap weld, fillet weld) and the arrangement of the base materials in a lap joint (aluminum-sided irradiation, steel-sided irradiation) on the achievable strengths are analyzed. The characterization of the dissimilar joints includes tensile shear tests and metallographic analyses, depending on the energy per unit length.

  12. Effect of tool pin features on process response variables during friction stir welding of dissimilar aluminum alloys

    SciTech Connect

    Rabby, Reza; Tang, Wei; Reynolds, A. P.

    2015-05-13

    In this article, the effect of pin features and orientation/placement of the materials on advancing side were investigated for friction stir welding (FSW) of dissimilar aluminum alloys AA2050 and AA6061. Pins for FSW were produced with a 2.12 mm pitch thread having three flats/flutes. Three sets of rotational speed/welding speed were used to perform a series of welds in a butt joint arrangement. The results show that, joint quality, process response variables and welding temperature are highly affected by pin features and material orientation in FSW. Defect free joints with effective material transportation in the weld nugget zone were obtained when welding was performed with AA2050 on the advancing side. The tool also encounters less in-plane reaction force for welding with 2050 on the advancing side. Pin with thread+3 flats produces quality welds at low rotational and travel speed regardless of the location of alloys on advancing or retreating side.

  13. Effect of tool pin features on process response variables during friction stir welding of dissimilar aluminum alloys

    DOE PAGES

    Rabby, Reza; Tang, Wei; Reynolds, A. P.

    2015-05-13

    In this article, the effect of pin features and orientation/placement of the materials on advancing side were investigated for friction stir welding (FSW) of dissimilar aluminum alloys AA2050 and AA6061. Pins for FSW were produced with a 2.12 mm pitch thread having three flats/flutes. Three sets of rotational speed/welding speed were used to perform a series of welds in a butt joint arrangement. The results show that, joint quality, process response variables and welding temperature are highly affected by pin features and material orientation in FSW. Defect free joints with effective material transportation in the weld nugget zone were obtainedmore » when welding was performed with AA2050 on the advancing side. The tool also encounters less in-plane reaction force for welding with 2050 on the advancing side. Pin with thread+3 flats produces quality welds at low rotational and travel speed regardless of the location of alloys on advancing or retreating side.« less

  14. Evaluation of weld metal 82 and weld metal 152 stress corrosion cracking susceptibility

    SciTech Connect

    Psaila-Dombrowski, M.J.; Sarver, J.M.; Doherty, P.E.; Schneider, W.G.

    1995-12-31

    Welds are often an area of concern in steam generators (SG) because of the different materials in the welds, the residual stresses which result from the welding process and subsequent operational stresses. In general a weld is composed of a base metal, weld metal and the heat affected zone (HAZ). This study investigated the corrosion performance of welds connecting the divider plate to the weld buildup in a welded-in divider plate (WIDP) design. The materials of interest were Alloy 690 plate, Weld Metals (WM) 82 and WM 152. Weld test samples were fabricated in a manner that is consistent with SG fabrication practices in which WM 152 is used to attach the Alloy 690 plate to the WM 82 weld buildup. Round tensile specimens were used to evaluate WIDP welds. Specimens were manufactured parallel to the weld fusion lines, hence, the gauge length of each specimen contained either the base metal or a metal and a HAZ. Use of specimens of this orientation permitted evaluation of all the materials contained in the specimen for stress corrosion cracking (SCC) susceptibility, not just the weakest materials. Constant extension rate tests were performed in Pressurized Water Reactor (PWR) primary water chemistry and faulted primary water chemistry at 343 C and a strain rate of 1 {times} 10{sup {minus}6} sec{sup {minus}1}. No SCC was found in any specimen in either environment.

  15. Sensors control gas metal arc welding

    SciTech Connect

    Siewert, T.A.; Madigan, R.B.; Quinn, T.P.

    1997-04-01

    The response time of a trained welder from the time a weld problem is identified to the time action is taken is about one second--especially after a long, uneventful period of welding. This is acceptable for manual welding because it is close to the time it takes for the weld pool to solidify. If human response time were any slower, manual welding would not be possible. However, human response time is too slow to respond to some weld events, such as melting of the contact tube in gas metal arc welding (GMAW), and only automated intelligent control systems can react fast enough to correct or avoid these problems. Control systems incorporate welding knowledge that enables intelligent decisions to be made about weld quality and, ultimately, to keep welding parameters in the range where only high-quality welds are produced. This article discusses the correlation of electrical signals with contact-tube wear, changes in shielding gas, changes in arc length, and other weld process data.

  16. Sensing the gas metal arc welding process

    NASA Technical Reports Server (NTRS)

    Carlson, N. M.; Johnson, J. A.; Smartt, H. B.; Watkins, A. D.; Larsen, E. D.; Taylor, P. L.; Waddoups, M. A.

    1994-01-01

    Control of gas metal arc welding (GMAW) requires real-time sensing of the process. Three sensing techniques for GMAW are being developed at the Idaho National Engineering Laboratory (INEL). These are (1) noncontacting ultrasonic sensing using a laser/EMAT (electromagnetic acoustic transducer) to detect defects in the solidified weld on a pass-by-pass basis, (2) integrated optical sensing using a CCD camera and a laser stripe to obtain cooling rate and weld bead geometry information, and (3) monitoring fluctuations in digitized welding voltage data to detect the mode of metal droplet transfer and assure that the desired mass input is achieved.

  17. Sensing the gas metal arc welding process

    SciTech Connect

    Carlson, N.M.; Johnson, J.A.; Smartt, H.B.; Watkins, A.D.; Larsen, E.D.; Taylor, P.L. ); Waddoups, M.A. )

    1992-01-01

    Control of gas metal arc welding (GMAW) requires real-time sensing of the process. Three sensing techniques for GMAW are being developed at the Idaho National Engineering Laboratory (INEL). These are (1) noncontacting ultrasonic sensing using a laser/EMAT (electromagnetic acoustic transducer) to detect defects in the solidified weld on a pass-bypass basis, (2) integrated optical sensing using a CCD camera and a laser stripe to obtain cooling rate and weld bead geometry information, and (3) monitoring fluctuations in digitized welding voltage data to detect the mode of metal droplet transfer and assure that the desired mass input is achieved.

  18. Sensing the gas metal arc welding process

    SciTech Connect

    Carlson, N.M.; Johnson, J.A.; Smartt, H.B.; Watkins, A.D.; Larsen, E.D.; Taylor, P.L.; Waddoups, M.A.

    1992-10-01

    Control of gas metal arc welding (GMAW) requires real-time sensing of the process. Three sensing techniques for GMAW are being developed at the Idaho National Engineering Laboratory (INEL). These are (1) noncontacting ultrasonic sensing using a laser/EMAT (electromagnetic acoustic transducer) to detect defects in the solidified weld on a pass-bypass basis, (2) integrated optical sensing using a CCD camera and a laser stripe to obtain cooling rate and weld bead geometry information, and (3) monitoring fluctuations in digitized welding voltage data to detect the mode of metal droplet transfer and assure that the desired mass input is achieved.

  19. Tungsten Carbide Grain Size Computation for WC-Co Dissimilar Welds

    NASA Astrophysics Data System (ADS)

    Zhou, Dongran; Cui, Haichao; Xu, Peiquan; Lu, Fenggui

    2016-06-01

    A "two-step" image processing method based on electron backscatter diffraction in scanning electron microscopy was used to compute the tungsten carbide (WC) grain size distribution for tungsten inert gas (TIG) welds and laser welds. Twenty-four images were collected on randomly set fields per sample located at the top, middle, and bottom of a cross-sectional micrograph. Each field contained 500 to 1500 WC grains. The images were recognized through clustering-based image segmentation and WC grain growth recognition. According to the WC grain size computation and experiments, a simple WC-WC interaction model was developed to explain the WC dissolution, grain growth, and aggregation in welded joints. The WC-WC interaction and blunt corners were characterized using scanning and transmission electron microscopy. The WC grain size distribution and the effects of heat input E on grain size distribution for the laser samples were discussed. The results indicate that (1) the grain size distribution follows a Gaussian distribution. Grain sizes at the top of the weld were larger than those near the middle and weld root because of power attenuation. (2) Significant WC grain growth occurred during welding as observed in the as-welded micrographs. The average grain size was 11.47 μm in the TIG samples, which was much larger than that in base metal 1 (BM1 2.13 μm). The grain size distribution curves for the TIG samples revealed a broad particle size distribution without fine grains. The average grain size (1.59 μm) in laser samples was larger than that in base metal 2 (BM2 1.01 μm). (3) WC-WC interaction exhibited complex plane, edge, and blunt corner characteristics during grain growth. A WC ( { 1 {bar{{1}}}00} ) to WC ( {0 1 1 {bar{{0}}}} ) edge disappeared and became a blunt plane WC ( { 10 1 {bar{{0}}}} ) , several grains with two- or three-sided planes and edges disappeared into a multi-edge, and a WC-WC merged.

  20. Welding.

    ERIC Educational Resources Information Center

    South Carolina State Dept. of Education, Columbia. Office of Vocational Education.

    This curriculum guide is designed for use by South Carolina vocational education teachers as a continuing set of lesson plans for a two-year course on welding. Covered in the individual sections of the guide are the following topics: an orientation to welding, oxyacetylene welding, advanced oxyacetylene welding, shielded metal arc welding, TIG…

  1. Life Assessment for Cr-Mo Steel Dissimilar Joints by Various Filler Metals Using Accelerated Creep Testing

    NASA Astrophysics Data System (ADS)

    Petchsang, S.; Phung-on, I.; Poopat, B.

    2016-12-01

    Accelerated creep rupture tests were performed on T22/T91 dissimilar metal joints to determine the fracture location and rupture time of different weldments. Four configurations of deposited filler metal were tested using gas tungsten arc welding to estimate the service life for Cr-Mo steel dissimilar joints at elevated temperatures in power plants. Results indicated that failure in all configurations occurred in the tempered original microstructure and tempered austenite transformation products (martensite or bainite structure) as type IV cracking at the intercritical area of the heat-affected zone (ICHAZ) for both T22 and T91 sides rather than as a consequence of the different filler metals. Creep damage occurred with the formation of precipitations and microvoids. The correlation between applied stress and the Larson-Miller parameter (PLM) was determined to predict the service life of each material configuration. Calculated time-to-failure based on the PLM and test results for both temperature and applied stress parameters gave a reasonable fit. The dissimilar joints exhibited lower creep rupture compared to the base material indicating creep degradation of the weldment.

  2. Microstructure characteristics and mechanical properties of laser-TIG hybrid welded dissimilar joints of Ti-22Al-27Nb and TA15

    NASA Astrophysics Data System (ADS)

    Zhang, Kezhao; Lei, Zhenglong; Chen, Yanbin; Liu, Ming; Liu, Yang

    2015-10-01

    Laser-TIG-hybrid-welding (TIG - tungsten inert gas) process was successfully applied to investigate the microstructure and tensile properties of Ti-22Al-27Nb/TA15 dissimilar joints. The HAZ of the arc zone in Ti-22Al-27Nb was characterized by three different regions: single B2, B2+α2 and B2+α2+O, while the single B2 phase region was absent in the HAZ of the laser zone. As for the HAZ in TA15 alloy, the microstructure mainly contained acicular α‧ martensites near the fusion line and partially remained the lamellar structure near the base metal. The fusion zone consisted of B2 phase due to the relatively high content of β phase stabilizing elements and fast cooling rate during the welding process. The tensile strength of the welds was higher than that of TA15 alloy because of the fully B2 microstructure in the fusion zone, and the fracture preferentially occurred on the base metal of TA15 alloy during the tensile tests at room temperature and 650 °C.

  3. Interfacial and Mechanical Behavior of AA5456 Filling Friction-Stir-Welded Lap Joints Using Similar and Dissimilar Pins

    NASA Astrophysics Data System (ADS)

    Behmand, Saleh Alaei; Mirsalehi, Seyyed Ehsan; Omidvar, Hamid; Safarkhanian, Mohammad Ali

    2016-10-01

    In this article, filling friction stir welding (FFSW) of the remaining exit holes of AA5456 alloy friction-stir-welded lap joints was studied. For this purpose, the influences of different rotating speeds, holding times, and pin materials, AA5456 and AA2024, on the metallurgical structure and joint strength were investigated. The observations showed that defect-free lap joints are successfully obtainable by this method using similar and dissimilar consumable pins. The results indicated that the higher rotating speed and holding time adversely affect the weld performance. The best result was achieved for 30 seconds holding time, 500 rpm rotating speed, and AA2024 consumable pin. In this condition, a lap shear strength of 10 pct higher than that of the nonfilled joint, equivalent to about 94 pct of the original defect-free FSW joint, was obtained, whereas the GTAW filled joint showed only approximately 87 pct of the continuous FSW joint strength.

  4. Metal Flow in Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur C., Jr.

    2006-01-01

    The plastic deformation field in Friction Stir Welding (FSW) is compared to that in metal cutting. A shear surface around the FSW tool analogous to the metal cutting shear plane is identified and comprises the basis of the "rotating plug" flow field model and the "wiping" model of tool interaction with weld metal. Within the context of these models: The FSW shear rate is estimated to be comparable to metal cutting shear rates. The effect of tool geometry on the FSW shear surface is discussed and related to published torque measurements. Various FS W structural features are explained, including a difference in structure of bimetallic welds when alloys on the advancing and retreating sides of the weld seam are exchanged. The joining mechanism and critical parameters of the FSW process are made clear.

  5. Direct welding of glass and metal by 1  kHz femtosecond laser pulses.

    PubMed

    Zhang, Guodong; Cheng, Guanghua

    2015-10-20

    In the welding process between similar or dissimilar materials, inserting an intermediate layer and pressure assistance are usually thought to be necessary. In this paper, the direct welding between alumina-silicate glass and metal (aluminum, copper, and steel), under exposure from 1 kHz femtosecond laser pulses without any auxiliary processes, is demonstrated. The micron/nanometer-sized metal particles induced by laser ablation were considered to act as the adhesive in the welding process. The welding parameters were optimized by varying the pulse energy and the translation velocity of the sample. The shear joining strength characterized by a shear force testing equipment was as high as 2.34 MPa. This direct bonding technology has potential for applications in medical devices, sensors, and photovoltaic devices.

  6. Microstructural characterization and mechanical properties of high power ultrasonic spot welded aluminum alloy AA6111–TiAl6V4 dissimilar joints

    SciTech Connect

    Zhang, C.Q. Robson, J.D.; Ciuca, O.; Prangnell, P.B.

    2014-11-15

    Aluminum alloy AA6111 and TiAl6V4 dissimilar alloys were successfully welded by high power ultrasonic spot welding. No visible intermetallic reaction layer was detected in as-welded AA6111/TiAl6V4 welds, even when transmission electron microscopy was used. The effects of welding time and natural aging on peak load and fracture energy were investigated. The peak load and fracture energy of welds increased with an increase in welding time and then reached a plateau. The lap shear strength (peak load) can reach the same level as that of similar Al–Al joints. After natural aging, the fracture mode of welds transferred from ductile fracture of the softened aluminum to interfacial failure due to the strength recovery of AA6111. - Highlights: • Dissimilar Al/Ti welds were produced by high power ultrasonic spot welding. • No visible intermetallic reaction layer was detected on weld interface. • The lap shear strength can reach the same level as that of similar Al–Al joints. • The fracture mode becomes interfacial failure after natural aging.

  7. Understanding metal vaporizaiton from laser welding.

    SciTech Connect

    DebRoy, Tarasankar; Fuerschbach, Phillip William; He, Xiuli; Norris, Jerome T.

    2003-09-01

    The production of metal vapor as a consequence of high intensity laser irradiation is a serious concern in laser welding. Despite the widespread use of lasers in manufacturing, little fundamental understanding of laser/material interaction in the weld pool exists. Laser welding experiments on 304 stainless steel have been completed which have advanced our fundamental understanding of the magnitude and the parameter dependence of metal vaporization in laser spot welding. Calculations using a three-dimensional, transient, numerical model were used to compare with the experimental results. Convection played a very important role in the heat transfer especially towards the end of the laser pulse. The peak temperatures and velocities increased significantly with the laser power density. The liquid flow is mainly driven by the surface tension and to a much less extent, by the buoyancy force. Heat transfer by conduction is important when the liquid velocity is small at the beginning of the pulse and during weld pool solidification. The effective temperature determined from the vapor composition was found to be close to the numerically computed peak temperature at the weld pool surface. At very high power densities, the computed temperatures at the weld pool surface were found to be higher than the boiling point of 304 stainless steel. As a result, vaporization of alloying elements resulted from both total pressure and concentration gradients. The calculations showed that the vaporization was concentrated in a small region under the laser beam where the temperature was very high.

  8. Forming Weld Lands On Metal Plates

    NASA Technical Reports Server (NTRS)

    Weddendorf, Bruce

    1994-01-01

    Forming shoe pounds edge of newly inserted plate workpiece. After many passes of shoe and advances of plate, thick land builds up at edge. Workpiece heated to enable metal to flow without strain hardening. Proposed upset-forming process replaces relatively expensive, time-consuming, and wasteful process in which integral weld lands created by machining metal away from plates everywhere except at lands.

  9. Refractory metals welded or brazed with tungsten inert gas equipment

    NASA Technical Reports Server (NTRS)

    Wisner, J. P.

    1965-01-01

    Appropriate brazing metals and temperatures facilitate the welding or brazing of base metals with tungsten inert gas equipment. The highest quality bond is obtained when TIG welding is performed in an inert atmosphere.

  10. Extended electrode technique. [gas metal arc welding of metal plates

    NASA Technical Reports Server (NTRS)

    Schaper, V. D.; Pollack, A.

    1972-01-01

    The extended electrode technique is a unique welding process which utilizes manual gas-metal-arc (GMAW) semi-automatic equipment and close, square butt joints to effectively produce a weld. The technique takes advantage of the resistance heating of the electode extension to effect the root pass. Weldments as large as 72-X30-X2-inch have been fabricated with this technique under normal shipyard welding conditions. Mechanical properties and explosion bulge tests indicate that satisfactory results are obtained with this process. Potential savings of approximately 50 percent can be achieved in flat welding and repair of heavy structural steel members.

  11. High Strength Steel Weldment Reliability: Weld Metal Hydrogen Trapping.

    DTIC Science & Technology

    1998-02-01

    additions to welding consumables to control weld metal hydrogen and thus reduce susceptibility to cold cracking in high strength steel weldments. 14...applying weld metal hydrogen trapping to improve the resistance to hydrogen cracking in welding of high strength steels . Hydrogen cracking in high...requirements which are necessary to prevent hydrogen cracking in high strength steel welding. Common practices to prevent hydrogen cracking in steel

  12. Influence of Filler Metals in Welding Wires on the Phase and Chemical Composition of Weld Metal

    NASA Astrophysics Data System (ADS)

    Kozyrev, N. A.; Osetkovskiy, I. V.; Kozyreva, O. A.; Zernin, E. A.; Kartsev, D. S.

    2016-04-01

    The influence of filler metals used in welding wires on the phase and chemical composition of the metal, which is surfaced to mining equipment exposed to abrasive wear, has been investigated. Under a laboratory environment, samples of Mo-V-B and Cr-Mn-Mo-V wires were made. The performed experiments have revealed that fillers of the Cr-Mn-Mo-V system used in powder wire show better wear resistance of the weld metal than that of the Mn-Mo-V-B system; the absence of boron, which promotes grain refinement in the Mn-Mo-V-B system, significantly reduces wear resistance; the Mn-Mo-V-B weld metal has a finer structure than the Cr-Mn-Mo-V weld metal.

  13. Automatic laser welding of metal bellows with precision seam tracker

    SciTech Connect

    Chang, D.U.

    1996-12-31

    Metal bellows were laser edge-welded satisfactorily with the aid of a precision seam tracking system. The welding speed was five to ten times faster than conventional arc welding. The weld quality was excellent and the cost savings are expected to be substantial.

  14. 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.

  15. Wet underwater welding trials with commercial manual metal arc electrodes

    SciTech Connect

    Abson, D.J.; Cooper, M.J.

    1996-12-01

    Six commercial wet underwater welding manual metal arc electrodes were evaluated in trials which simulated repairs to structures in shallow water. Welding was carried out both vertically down and overhead, at a depth of approximately 5 meters. One of the electrodes was an austenitic stainless steel, and the remainder were ferritic steel, containing low levels of carbon and manganese. Two weld configurations were employed in 8 mm thick C-Mn steel plate. Each weld was radiographed, sectioned, and examined metallographically. Tensile, Charpy and hardness testing were carried out. The trials revealed significant differences in the handleability of the six commercial electrodes. Handleability was better when welding vertically than when welding overhead, and was also better for fillet welds than for butt welds. Worm-holes and porosity were common in the latter. Extensive cracking occurred in the panels welded with the stainless steel electrode, preventing the extraction of mechanical test specimens from them. For the weld metal of the ferritic steel butt welds, strength and hardness increased with increasing alloying. Weld metal Charpy toughness varied widely between the different deposits. HAZ toughness was higher than that of the weld metal, but followed the trend of the weld metal data. On the patch plates, failure occurred in the parent steel on cross weld tensile specimens for the ferritic consumables, and in weld metal for the panels welded with the stainless steel electrodes. Viewed overall, two of the ferritic electrodes gave the best handleability and mechanical properties. However, fine-scale cracking was observed in the vertical butt weld deposited with one of them, and thus the other ferritic electrode gave the best all-round behavior. The remaining electrodes showed poorer handleability and a higher incidence of weld defects, including the extensive cracking observed in the butt welds produced with the stainless steel electrode.

  16. Effect of Traverse and Rotational Speeds on the Tensile Behavior of the Underwater Dissimilar Friction Stir Welded Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Bijanrostami, Kh.; Barenji, R. Vatankhah; Hashemipour, M.

    2017-01-01

    The tensile behavior of the underwater dissimilar friction stir welded AA6061 and AA7075 aluminum alloy joints was investigated for the first time. For this aim, the joints were welded at different conditions and tensile test was conducted for measuring the strength and elongation of them. In addition, the microstructure of the joints was characterized by means of optical and transmission electron microscopes. Scanning electron microscope was used for fractography of the joints. Furthermore, the process parameters and tensile properties of the joints were correlated and optimized. The results revealed that the maximum tensile strength of 237.3 MPa and elongation of 41.2% could be obtained at a rotational speed 1853 rpm and a traverse speed of 50 mm/min. In comparison with the optimum condition, higher heat inputs caused grain growth and reduction in dislocation density and hence led to lower strength. The higher elongations for the joints welded at higher heat inputs were due to lower dislocation density inside the grains, which was consistent with a more ductile fracture of them.

  17. Effect of Traverse and Rotational Speeds on the Tensile Behavior of the Underwater Dissimilar Friction Stir Welded Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Bijanrostami, Kh.; Barenji, R. Vatankhah; Hashemipour, M.

    2017-02-01

    The tensile behavior of the underwater dissimilar friction stir welded AA6061 and AA7075 aluminum alloy joints was investigated for the first time. For this aim, the joints were welded at different conditions and tensile test was conducted for measuring the strength and elongation of them. In addition, the microstructure of the joints was characterized by means of optical and transmission electron microscopes. Scanning electron microscope was used for fractography of the joints. Furthermore, the process parameters and tensile properties of the joints were correlated and optimized. The results revealed that the maximum tensile strength of 237.3 MPa and elongation of 41.2% could be obtained at a rotational speed 1853 rpm and a traverse speed of 50 mm/min. In comparison with the optimum condition, higher heat inputs caused grain growth and reduction in dislocation density and hence led to lower strength. The higher elongations for the joints welded at higher heat inputs were due to lower dislocation density inside the grains, which was consistent with a more ductile fracture of them.

  18. Experimental Investigation of Three-Dimensional (3-D) Material Flow Pattern in Thick Dissimilar 2050 Friction-Stir Welds

    NASA Astrophysics Data System (ADS)

    Avettand-Fènoël, Marie-Noëlle; Taillard, Roland; Laye, Julien; Odièvre, Thierry

    2014-02-01

    The current microstructural investigation performed at various scales deals with the three-dimensional (3-D) material flow in thick dissimilar Airware™ 2050 friction-stir butt welds (Airware, Newport Beach, CA) because of the scarcity of the results obtained with thicker than 8 mm joints and the lack of detailed interpretation of features in the longitudinal direction. An additional originality consists in the study of material flow under the probe tip. In the current case of thick plates, the variation of local temperature along the weld depth is of key importance for the material flow. Indeed, it governs the slight difference of local mechanical behavior between both materials and therefore the shift of the interface, which was clearly put into evidence by means of a difference of Mn content as small as 0.3 pct between both alloys. This importance of temperature for the malleability also entails the pear shape of the nugget as well as a change of grains orientation along the depth in the thermomechanically affected zone. Due to the modification of tool-material adhesion with temperature, a new phenomenological model of material flow for thick friction-stir welds is proposed. In accordance with their difference of origin, the coexistence of onion rings and serrated interface is also highlighted.

  19. Apparatus For Metal/Inert-Gas Welding In Vacuum

    NASA Technical Reports Server (NTRS)

    Stocks, C. O.

    1994-01-01

    Metal/inert-gas welding-torch assembly operates in vacuum. Plasma generated in interior chamber and focused onto workpiece in vacuum. Pinch rollers feed wire to weld puddle. Controlled flow of plasma reduces dispersal in vacuum, preventing extinction.

  20. Thermal insulation of wet shielded metal arc welds

    NASA Astrophysics Data System (ADS)

    Keenan, Patrick J.

    1993-06-01

    Computational and experimental studies were performed to determine the effect of static thermal insulation on the quality of wet shielded metal arc welds (SMAW). A commercially available heat flow and fluid dynamics spectral-element computer program was used to model a wet SMAW and to determine the potential effect on the weld cooling rate of placing thermal insulation adjacent to the weld line. Experimental manual welds were made on a low carbon equivalent (0.285) mild steel and on a higher carbon equivalent (0.410) high tensile strength steel, using woven fabrics of alumina-boria-silica fibers to insulate the surface of the plate being welded. The effect of the insulation on weld quality was evaluated through the use of post-weld Rockwell Scale hardness measurements on the surface of the weld heat affected zones (HAZ's) and by visual inspection of sectioned welds at 10 X magnification. The computational simulation demonstrated a 150% increase in surface HAZ peak temperature and a significant decrease in weld cooling rate with respect to uninsulated welds, for welds in which ideal insulation had been placed on the base plate surface adjacent to the weld line. Experimental mild steel welds showed a reduction in surface HAZ hardness attributable to insulation at a 77% significance level. A visual comparison of the cross-sections of two welds made in 0.410 carbon equivalent steel-with approximately equivalent heat input-revealed underbead cracking in the uninsulated weld but not in the insulated weld.

  1. Microstructure and Mechanical Properties of Dissimilar Welded Ti3Al/Ni-Based Superalloy Joint Using a Ni-Cu Filler Alloy

    NASA Astrophysics Data System (ADS)

    Chen, Bing-Qing; Xiong, Hua-Ping; Guo, Shao-Qing; Sun, Bing-Bing; Chen, Bo; Tang, Si-Yi

    2015-02-01

    Dissimilar welding of a Ti3Al-based alloy and a Ni-based superalloy (Inconel 718) was successfully carried out using gas tungsten arc welding technology in this study. With a Ni-Cu alloy as filler material, sound joints have been obtained. The microstructure evolution along the cross section of the dissimilar joint has been revealed based on the results of scanning electron microscopy and X-ray energy dispersive spectroscopy as well as X-ray diffractometer. It is found that the weld/Ti3Al interface is composed of Ti2AlNb matrix dissolved with Ni and Cu, Al(Cu, Ni)2Ti, (Cu, Ni)2Ti, (Nb, Ti) solid solution, and so on. The weld and In718/weld interface mainly consist of (Cu, Ni) solid solutions. The weld exhibits higher microhardness than the two base materials. The average room-temperature tensile strength of the joints reaches 242 MPa and up to 73.6 pct of the value can be maintained at 873 K (600 °C). The brittle intermetallic phase of Ti2AlNb matrix dissolved with Ni and Cu at the weld/Ti3Al interface is the weak link of the joint.

  2. Electrode formulation to reduce weld metal hydrogen and porosity

    SciTech Connect

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

    1994-12-31

    Residual weld metal hydrogen is a major concern in high strength steel welding, especially when the weld is performed under high cooling rate conditions. In the case of underwater wet welding, weld metal porosity is also of importance because of the water environment. The control of both problems can be achieved by means of pyrochemical reactions in the weld pool. The hydrogen-oxygen reaction and carbon-oxygen reaction are fundamental in the control of residual hydrogen in the weld metal and the amount of gas pores entrapped. A simple model was proposed to estimate weld metal residual hydrogen content by monitoring the weld pool deoxidation reactions. Potent deoxidizers such as aluminum will first react with oxygen in the liquid weld pool, followed by other elements present such as silicon and manganese. Carbon and hydrogen will be the last ones to react with oxygen prior to the iron atoms. The Ellingham-Richardson diagram frequently applied in describing steel and iron making processes was used in the modeling. Following the sequence of deoxidation, the chemical make-up of the gas pores and the amount of each chemical species in the pores could be estimated. Carbon monoxide and hydrogen were determined to be the major components in the weld pores. To minimize the amount of weld metal porosity and residual hydrogen content, specially designed consumables that will control the oxygen potential of the weld pool must be developed.

  3. Plutonium metal and oxide container weld development and qualification

    SciTech Connect

    Fernandez, R.; Horrell, D.R.; Hoth, C.W.; Pierce, S.W.; Rink, N.A.; Rivera, Y.M.; Sandoval, V.D.

    1996-01-01

    Welds were qualified for a container system to be used for long-term storage of plutonium metal and oxide. Inner and outer containers are formed of standard tubing with stamped end pieces gas-tungsten-arc (GTA) welded onto both ends. The weld qualification identified GTA parameters to produce a robust weld that meets the requirements of the Department of Energy standard DOE-STD-3013-94, ``Criteria for the Safe Storage of Plutonium Metals and Oxides.``

  4. Development of plasma MIG brazing process for dissimilar metal joining of aluminum to steel

    NASA Astrophysics Data System (ADS)

    Tashiro, Shinichi; Tanaka, Manabu

    2014-08-01

    This study aims to develop a new brazing process employing plasma MIG. Because the energy density of the plasma produced by the plasma electrode is low, the base metal can be heated extensively without melting of the base metal, consequently improving the wettability of bead. This paper discussed the dissimilar metal joining of aluminum to steel by plasma MIG brazing process. Fracture occurred at the HAZ in the aluminum plate at 80 MPa.

  5. Metal Transfer in Gas Metal Arc Welding

    DTIC Science & Technology

    1988-03-17

    their measurements. Predictions can also be compared to integral measurements as by Halmoy [1980] for melting rate and by Ueguri, Hara and Komura ...10 No. 3. Ue-,uri, S., K. Hara and H. Komura , 1985. Welding J., 64 pp. 242s-250s. van Doormaal, J.P. and G.D. Raithby, 1985. ASME paper 85-HT-9

  6. 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.

  7. Parametric studies on tensile strength in joining AA6061- T6 and AA7075-T6 by gas metal arc welding process

    NASA Astrophysics Data System (ADS)

    Ishak, M.; Noordin, N. F. M.; Shah, L. H.

    2015-12-01

    Proper selection of the welding parameters can result in better joining. In this study, the effects of various welding parameters on tensile strength in joining dissimilar aluminum alloys AA6061-T6 and AA7075-T6 were investigated. 2 mm thick samples of both base metals were welded by semi-automatic gas metal arc welding (GMAW) using filler wire ER5356. The welding current, arc voltage and welding speed were chosen as variables parameters. The strength of each specimen after the welding operations were tested and the effects of these parameters on tensile strength were identified by using Taguchi method. The range of parameter for welding current were chosen from 100 to 115 A, arc voltage from 17 to 20 V and welding speed from 2 to 5 mm/s. L16 orthogonal array was used to obtained 16 runs of experiments. It was found that the highest tensile strength (194.34 MPa) was obtained with the combination of a welding current of 115 A, welding voltage of 18 V and welding speed of 4 mm/s. Through analysis of variance (ANOVA), the welding voltage was the most effected parameter on tensile strength with percentage of contribution at 41.30%.

  8. Microstructure Improvement in Weld Metal under the Ultrasonic Application

    SciTech Connect

    Cui, Yan; Xu, Cailu; Han, Qingyou

    2007-01-01

    When considering the operational performance of weldments in the engineering projects, the most important issues to be considered are weld metal mechanical properties, integrity of the welded joint, and weldability 1 . These issues are closely related to the microstructure of the weld metal. A significant amount of research has been carried out to alter the process variables and to use external devices to obtain microstructure control of the weldments. It has been reported that grain refined microstructure not only reduces cracking behavior of alloys including solidification cracking, cold cracking and reheat cracking, 2 - 5 but also improves the mechanical properties of the weld metal, such as toughness, ductility, strength, and fatigue life. 6, 7 Weld pool stirring, 8 arc oscillation, 9, 10 arc pulsation, 11 , and magnetic arc oscillator 12, 13 have been applied to fusion welding to refine the microstructures. This article describes initial experimental results on the use of power ultrasonic vibration to refine the microstructure of weld metals.

  9. Analysis of thermal stresses and metal movement during welding

    NASA Technical Reports Server (NTRS)

    Muraki, T.; Pattee, F. M.; Masubuchi, K.

    1974-01-01

    Finite element computer programs were developed to determine thermal stresses and metal movement during butt welding of flat plates and bead-on-plate welding along the girth of a cylindrical shell. Circular cylindrical shells of 6061 aluminum alloy were used for the tests. Measurements were made of changes in temperature and thermal strains during the welding process.

  10. Shielded Metal Arc Pipe Welding. Teacher Edition. Second Edition.

    ERIC Educational Resources Information Center

    Fortney, Clarence; And Others

    This second edition of the shielded metal arc pipe welding curriculum guide presents both basic and advanced pipe welding skills. All specifications for procedure and welder qualification are presented according to national standards. The standards also include the test position for both groove and fillet pipe welding. The guide contains three…

  11. Friction stir welding joint of dissimilar materials between AZ31B magnesium and 6061 aluminum alloys: Microstructure studies and mechanical characterizations

    SciTech Connect

    Mohammadi, J.; Behnamian, Y.; Mostafaei, A.; Izadi, H.; Saeid, T.; Kokabi, A.H.; Gerlich, A.P.

    2015-03-15

    Friction stir welding is an efficient manufacturing method for joining dissimilar alloys, which can dramatically reduce grain sizes and offer high mechanical joint efficiency. Lap FSW joints between dissimilar AZ31B and Al 6061 alloy sheets were made at various tool rotation and travel speeds. Rotation and travel speeds varied between 560–1400 r/min and 16–40 mm/min respectively, where the ratio between these parameters was such that nearly constant pitch distances were applied during welding. X-ray diffraction pattern (XRD), optical microscopy images (OM), electron probe microanalysis (EPMA) and scanning electron microscopy equipped with an energy-dispersive X-ray spectroscopy (SEM-EDS) were used to investigate the microstructures of the joints welded. Intermetallic phases including Al{sub 12}Mg{sub 17} (γ) and Al{sub 3}Mg{sub 2} (β) were detected in the weld zone (WZ). For different tool rotation speeds, the morphology of the microstructure in the stir zone changed significantly with travel speed. Lap shear tensile test results indicated that by simultaneously increasing the tool rotation and travel speeds to 1400 r/min and 40 mm/min, the joint tensile strength and ductility reached a maximum. Microhardness measurements and tensile stress–strain curves indicated that mechanical properties were affected by FSW parameters and mainly depended on the formation of intermetallic compounds in the weld zone. In addition, a debonding failure mode in the Al/Mg dissimilar weld nugget was investigated by SEM and surface fracture studies indicated that the presence of intermetallic compounds in the weld zone controlled the failure mode. XRD analysis of the fracture surface indicated the presence of brittle intermetallic compounds including Al{sub 12}Mg{sub 17} (γ) and Al{sub 3}Mg{sub 2} (β). - Highlights: • Dissimilar Al/Mg joint was obtained by lap friction stir welding technique. • Effect of rotation and travel speeds on the formation of intermetallic

  12. Effect of Pulse Parameters on Weld Quality in Pulsed Gas Metal Arc Welding: A Review

    NASA Astrophysics Data System (ADS)

    Pal, Kamal; Pal, Surjya K.

    2011-08-01

    The weld quality comprises bead geometry and its microstructure, which influence the mechanical properties of the weld. The coarse-grained weld microstructure, higher heat-affected zone, and lower penetration together with higher reinforcement reduce the weld service life in continuous mode gas metal arc welding (GMAW). Pulsed GMAW (P-GMAW) is an alternative method providing a better way for overcoming these afore mentioned problems. It uses a higher peak current to allow one molten droplet per pulse, and a lower background current to maintain the arc stability. Current pulsing refines the grains in weld fusion zone with increasing depth of penetration due to arc oscillations. Optimum weld joint characteristics can be achieved by controlling the pulse parameters. The process is versatile and easily automated. This brief review illustrates the effect of pulse parameters on weld quality.

  13. Welding, bonding, and sealing of refractory metals by vapor deposition

    NASA Technical Reports Server (NTRS)

    1967-01-01

    Plating process welds, bonds, and seals refractory metals without weakening or changing the structure of the base metals. A metal halide compound in the vapor phase is decomposed to deposit filler metal on the base metal. The resulting bond is a true metal-to-metal bond.

  14. Solidification Behavior and Weldability of Dissimilar Welds Between a Cr-Free, Ni-Cu Welding Consumable and Type 304L Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Sowards, Jeffrey W.; Liang, Dong; Alexandrov, Boian T.; Frankel, Gerald S.; Lippold, John C.

    2012-04-01

    The solidification behavior of a Cr-free welding consumable based on the Ni-Cu system was evaluated in conjunction with Type 304L stainless steel. The weld metal microstructure evolution was evaluated with optical and secondary electron microscopy, energy dispersive spectroscopy, X-ray diffraction, button melting, and thermodynamic (CALPHAD-based) modeling. Solidification partitioning patterns showed that higher dilutions of the filler metal by Type 304L increased segregation of Ti, Cu, and Si to interdendritic regions. Button melting experiments showed a widening of the solidification temperature range with increasing dilution because of the expansion of the austenite solidification range and formation of Ti(C,N) via a eutectic reaction. The model predictions showed good correlation with button melting experiments and were used to evaluate the nature of the Ti(C,N) precipitation reaction. Solidification cracking susceptibility of the weld metal was shown to increase with dilution of 304L stainless steel based on testing conducted with the cast pin tear test. The increase in cracking susceptibility is associated with expansion of the solidification temperature range and the presence of eutectic liquid at the end of solidification that wets solidification grain boundaries.

  15. Ultrasonic Welding of Hybrid Joints

    NASA Astrophysics Data System (ADS)

    Wagner, Guntram; Balle, Frank; Eifler, Dietmar

    2012-03-01

    A central research field of the Institute of Materials Science and Engineering at the University of Kaiserslautern (WKK), Germany, is the realization of innovative hybrid joints by ultrasonic metal welding. This article gives an overview of suitable ultrasonic welding systems as well as of essential machine and material parameters, which influence the quality of the welds. Besides the ultrasonic welding of dissimilar metals such as Al to Cu or Al to steels, the welds between newly developed materials like aluminum foam sandwiches or flat flexible cables also can be realized. Moreover, the joining of glass and ceramic to sheet metals is a point of interest at the WKK. By using the ultrasonic metal welding process, it is possible to realize metal/glass welds with tensile shear strengths of 50 MPa. For metal/ceramic joints, the shear strengths values up to 150 MPa were measured. Finally, selected results about the occurring bonding mechanisms will be discussed.

  16. Effects of Initial Temper Condition and Postweld Heat Treatment on the Properties of Dissimilar Friction-Stir-Welded Joints between AA7075 and AA6061 Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    İpekoğlu, Güven; Çam, Gürel

    2014-06-01

    In this study, dissimilar AA7075-O/6061-O and AA7075-T6/6061-T6 butt joints were produced by friction stir welding (FSW), and postweld heat treatment (PWHT) was applied to the joints obtained. The effects of initial temper condition and PWHT on the microstructure and mechanical properties of the dissimilar joints were thus investigated. It was demonstrated that sound dissimilar joints can be produced for both temper conditions. A hardness increase in the joint area ( i.e., strength overmatching) was obtained in the joints produced in the O-temper condition, whereas a hardness loss was observed in the joint area of the joints obtained in the T6 temper condition. It was also well demonstrated that PWHT could be used in order to improve the joint properties for both O and T6 joints provided that the joint is defect-free prior to subsequent heat treatment.

  17. Dissimilar laser welding of NiTi shape memory alloy and copper

    NASA Astrophysics Data System (ADS)

    Zeng, Z.; Panton, B.; Oliveira, J. P.; Han, A.; Zhou, Y. N.

    2015-12-01

    This work is the first investigation of joining NiTi and copper. The successful Nd:YAG laser welding of NiTi to copper achieved in this work enables new methods of connecting shape memory alloys to electro-mechanical systems. Joints made with an optimum peak power of 2.2 kW accommodated pseudoelastic deformation of NiTi, proving their use with high strength actuators. Fracture occurred through the cross section of these defect-free joints. A lower peak power of 1.8 kW created weak joints with limited weld penetration of the copper sheet. This lack of bonding resulted in fracture occurring across the small disconnected joint areas. Joints made with a higher peak power of 2.6 kW had significant cracking in the fusion zone. Two regions of distinct Cu composition were found in the fusion zone, and cracking occurred at the interface between these regions because of their different physical properties. Failure initiated at this cracking and propagated through the fusion zone that had been embrittled by mixing with over 20 at.% Cu.

  18. Metal Flow During Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Guerra, M.; Schmidt, C.; McClure, J. C.; Murr, L. E.; Nunes, A. C.; Munafo, Paul M. (Technical Monitor)

    2001-01-01

    The flow of metal during Friction Stir Welding is clarified using a faying surface tracer and a nib frozen in place during welding. It is shown that material is transported by two processes. The first is a wiping of material from the advancing front side of the nib onto a plug of material that rotates and advances with the nib. The material undergoes a helical motion within the plug that both rotates and advances with the plug and descends in the wash of the threads on the nib and rises on the outer part of the plug. After one or more rotations, this material is sloughed off the plug in its wake, primarily on the advancing side. The second process is an entrainment of material from the front retreating side of the nib that fills in between the sloughed off pieces from the advancing side. These two processes produce material with different mechanical properties and the strength of a weld should depend on the relative importance of the processes.

  19. Pressure Resistance Welding of High Temperature Metallic Materials

    SciTech Connect

    N. Jerred; L. Zirker; I. Charit; J. Cole; M. Frary; D. Butt; M. Meyer; K. L. Murty

    2010-10-01

    Pressure Resistance Welding (PRW) is a solid state joining process used for various high temperature metallic materials (Oxide dispersion strengthened alloys of MA957, MA754; martensitic alloy HT-9, tungsten etc.) for advanced nuclear reactor applications. A new PRW machine has been installed at the Center for Advanced Energy Studies (CAES) in Idaho Falls for conducting joining research for nuclear applications. The key emphasis has been on understanding processing-microstructure-property relationships. Initial studies have shown that sound joints can be made between dissimilar materials such as MA957 alloy cladding tubes and HT-9 end plugs, and MA754 and HT-9 coupons. Limited burst testing of MA957/HT-9 joints carried out at various pressures up to 400oC has shown encouraging results in that the joint regions do not develop any cracking. Similar joint strength observations have also been made by performing simple bend tests. Detailed microstructural studies using SEM/EBSD tools and fatigue crack growth studies of MA754/HT-9 joints are ongoing.

  20. 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.

  1. 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.

  2. Effect of Continuous and Pulsed Current Gas Tungsten Arc Welding on Dissimilar Weldments Between Hastelloy C-276/AISI 321 Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Sharma, Sumitra; Taiwade, Ravindra V.; Vashishtha, Himanshu

    2017-03-01

    In the present investigation, an attempt has been made to join Hastelloy C-276 nickel-based superalloy and AISI 321 austenitic stainless steel using ERNiCrMo-4 filler. The joints were fabricated by continuous and pulsed current gas tungsten arc welding processes. Experimental studies to ascertain the structure-property co-relationship with or without pulsed current mode were carried out using an optical microscope and scanning electron microscope. Further, the energy-dispersive spectroscope was used to evaluate the extent of microsegregation. The microstructure of fusion zone was obtained as finer cellular dendritic structure for pulsed current mode, whereas columnar structure was formed with small amount of cellular structure for continuous current mode. The scanning electron microscope examination witnessed the existence of migrated grain boundaries at the weld interfaces. Moreover, the presence of secondary phases such as P and μ was observed in continuous current weld joints, whereas they were absent in pulsed current weld joints, which needs to be further characterized. Moreover, pulsed current joints resulted in narrower weld bead, refined morphology, reduced elemental segregation and improved strength of the welded joints. The outcomes of the present investigation would help in obtaining good quality dissimilar joints for industrial applications and AISI 321 ASS being cheaper consequently led to cost-effective design also.

  3. Effect of Continuous and Pulsed Current Gas Tungsten Arc Welding on Dissimilar Weldments Between Hastelloy C-276/AISI 321 Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Sharma, Sumitra; Taiwade, Ravindra V.; Vashishtha, Himanshu

    2017-02-01

    In the present investigation, an attempt has been made to join Hastelloy C-276 nickel-based superalloy and AISI 321 austenitic stainless steel using ERNiCrMo-4 filler. The joints were fabricated by continuous and pulsed current gas tungsten arc welding processes. Experimental studies to ascertain the structure-property co-relationship with or without pulsed current mode were carried out using an optical microscope and scanning electron microscope. Further, the energy-dispersive spectroscope was used to evaluate the extent of microsegregation. The microstructure of fusion zone was obtained as finer cellular dendritic structure for pulsed current mode, whereas columnar structure was formed with small amount of cellular structure for continuous current mode. The scanning electron microscope examination witnessed the existence of migrated grain boundaries at the weld interfaces. Moreover, the presence of secondary phases such as P and μ was observed in continuous current weld joints, whereas they were absent in pulsed current weld joints, which needs to be further characterized. Moreover, pulsed current joints resulted in narrower weld bead, refined morphology, reduced elemental segregation and improved strength of the welded joints. The outcomes of the present investigation would help in obtaining good quality dissimilar joints for industrial applications and AISI 321 ASS being cheaper consequently led to cost-effective design also.

  4. Interdiffusion behavior of tungsten or rhenium and group 5 and 6 elements and alloys of the periodic table, part 1. [at dissimilar metal joints

    NASA Technical Reports Server (NTRS)

    Arcella, F. G.

    1974-01-01

    Arc cast W, CVD W, CVD Re, and powder metallurgy Re materials were hot isostatically pressure welded to ten different refractory metals and alloys (Cb, Cb-1Zr, Ta, Ta-10W, T-111, ASTAR-811C, W-25Re, Mo-50Re, W-30Re-20Mo, ect.) and thermally aged at 10 to the minus 8th power torr at 1200, 1500, 1630, 1800, and 2000 C for 100 to 2000 hours. Electron beam microprobe analysis was used to characterize the interdiffusion zone width of each couple system as a function of age time and temperature. Extrapolations of interdiffusion zone thickness to 10,000 hours were made. Classic interdiffusion analysis was performed for several of the systems by Boltzmann-Matano analysis. A method of inhibiting Kirkendall voids from forming during thermal ageing of dissimilar metal junctions was devised and experimentally demonstrated. An electron beam weld study of Cb-1Zr to Re and W-25Re demonstrated the limited acceptability of these welds.

  5. Weld Metal Cooling Rate Indicator System.

    DTIC Science & Technology

    rate of change of weld temperature at the predetermined weld temperature. A range of...provided so that the rate of change of weld temperatures at the predetermined weld temperature can be compared with this range. A device is then provided...which is responsive to the comparing information for indicating whether the rate of change of weld temperature is within, above, or below the range

  6. Influence of Aluminum Content on Grain Refinement and Strength of AZ31 Magnesium GTA Weld Metal

    SciTech Connect

    Babu, N. Kishore; Cross, Carl E.

    2012-06-28

    The goal is to characterize the effect of Al content on AZ31 weld metal, the grain size and strength, and examine role of Al on grain refinement. The approach is to systematically vary the aluminum content of AZ31 weld metal, Measure average grain size in weld metal, and Measure cross-weld tensile properties and hardness. Conclusions are that: (1) increased Al content in AZ31 weld metal results in grain refinement Reason: higher undercooling during solidification; (2) weld metal grain refinement resulted in increased strength & hardness Reason: grain boundary strengthening; and (3) weld metal strength can be raised to wrought base metal levels.

  7. Gas Metal Arc Welding Process Modeling and Prediction of Weld Microstructure in MIL A46100 Armor-Grade Martensitic Steel

    DTIC Science & Technology

    2013-06-01

    most of the commercially available metallic materials, in particular steels (including stainless steels ), super alloys, aluminum alloys, etc., can...REPORT Gas Metal Arc Welding Process Modeling and Prediction of Weld Microstructure in MIL A46100 Armor-Grade Martensitic Steel 14. ABSTRACT 16...Welding Process Modeling and Prediction of Weld Microstructure in MIL A46100 Armor-Grade Martensitic Steel Report Title ABSTRACT A conventional gas metal

  8. Weld seam tracking and lap weld penetration monitoring using the optical spectrum of the weld plume

    SciTech Connect

    Mueller, R.E.; Hopkins, J.A.; Semak, V.V.; McCay, M.H.

    1996-12-31

    Joining of dissimilar materials is a long standing problem in manufacturing, with many tricks and special techniques developed to successfully join specific pairs of materials. Often, these special techniques impose stringent requirements on the process such as precise control of process parameters to achieve the desired joint characteristics. Laser welding is one of the techniques which has had some success in welding dissimilar metal alloys, and appears to be a viable process for these materials. Minimal heat input limits differential thermal expansion, and the small weld pool allows precise control of alloy mixing in the fusion zone. Obtaining optimal weld performance requires accurate monitoring and control of absorbed laser power and weld focus position. In order to monitor the laser welding process, the authors have used a small computer controlled optical spectrometer to observe the emission from the weld plume. Absorbed laser power can be related to the temperature of the weld pool surface and the plume above the weld. Focus position relative to the joint can easily be seen by the proportion of elements from each material existing in the plume. This monitor has been used to observe and optimize the performance of butt and lap welds between dissimilar alloys, where each alloy contains at least one element not found in the other alloy. Results will be presented for a copper-steel butt joint and a lap weld between stainless and low alloy steels.

  9. Microstructural Development in HSLA-100 Steel Weld Metals

    DTIC Science & Technology

    1991-01-01

    AD-A2 3 7 931 MICROSTRUCTURAL DEVELOPMENT IN HSLA-100 STEEL WELD METALS A*.t - AI* Final Report Grant No. N00014-89-J-1958 -. .o, Submitted by j Paul...on pages 30-32. The microstructures that develop in the coarse-grained heat affected zone (CG- HAZ) of the welds are discussed on page 21 and figures...stringent welding procedures as well as reduce the mechanical property deterioration from welding operations. The development of the ultra low carbon

  10. The importance of spatter formed in shielded metal arc welding

    SciTech Connect

    Molleda, F. Mora, J.; Molleda, J.R.; Mora, E.; Mellor, B.G.

    2007-10-15

    Spatter results when droplets of liquid metal that have been ejected from the weld pool by the impact of small droplets from the covered electrode solidify and weld to the surface of the base material. The present paper studies spatter and reveals why these small droplets do not oxidise during their short trajectory and accounts for why they arrive with sufficient heat to weld to the adjacent base material. Welds were thus performed on mild steel using covered electrodes (rutile type) to obtain spatter on the adjacent base material. Scanning electron microscopy and X-ray mapping were used to study the above mentioned phenomena.

  11. Control of arc length during gas metal arc welding

    SciTech Connect

    Madigan, R.B.; Quinn, T.P.

    1994-12-31

    An arc-length control system has been developed for gas metal arc welding (GMAW) under spray transfer welding conditions. The ability to monitor and control arc length during arc welding allows consistent weld characteristics to be maintained and therefore improves weld quality. Arc length control has only been implemented for gas tungsten arc welding (GTAW), where an automatic voltage control (AVC) unit adjusts torch-to-work distance. The system developed here compliments the voltage- and current-sensing techniques commonly used for control of GMAW. The system consists of an arc light intensity sensor (photodiode), a Hall-effect current sensor, a personal computer and software implementing a data interpretation and control algorithms. Arc length was measured using both arc light and arc current signals. Welding current was adjusted to maintain constant arc length. A proportional-integral-derivative (PID) controller was used. Gains were automatically selected based on the desired welding conditions. In performance evaluation welds, arc length varied from 2.5 to 6.5 mm while welding up a sloped workpiece (ramp in CTWD) without the control. Arc length was maintained within 1 mm of the desired (5 mm ) with the control.

  12. 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.

  13. 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.

  14. Application of welding science to welding engineering: A lumped parameter gas metal arc welding dynamic process model

    SciTech Connect

    Murray, P.E.; Smartt, H.B.; Johnson, J.A.

    1997-12-31

    We develop a model of the depth of penetration of the weld pool in gas metal arc welding (GMAW) which demonstrates interaction between the arc, filler wire and weld pool. This model is motivated by the observations of Essers and Walter which suggest a relationship between droplet momentum and penetration depth. A model of gas metal arc welding was augmented to include an improved model of mass transfer and a simple model of accelerating droplets in a plasma jet to obtain the mass and momentum of impinging droplets. The force of the droplets and depth of penetration is correlated by a dimensionless linear relation used to predict weld pool depth for a range of values of arc power and contact tip to workpiece distance. Model accuracy is examined by comparing theoretical predictions and experimental measurements of the pool depth obtained from bead on plate welds of carbon steel in an argon rich shielding gas. Moreover, theoretical predictions of pool depth are compared to the results obtained from the heat conduction model due to Christensen et al. which suggest that in some cases the momentum of impinging droplets is a better indicator of the depth of the weld pool and the presence of a deep, narrow penetration.

  15. Recommend design of filler metal to minimize carbon steel weld metal preferential corrosion in CO2-saturated oilfield produced water

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    The paper proposes a recommend design for the alloying elements in the filler metal to minimize preferential weld corrosion of carbon steel. The tensile and corrosion resistance properties of the weld metal are considerably improved by using a filler metal containing alloying elements according to the recommended design. Analysis of the morphology and composition of corrosion products on weld metals showed that the common weld metal suffered severe localized corrosion, whereas the weld metal with the alloying elements exhibited uniform corrosion. Based on these results, a tentative mechanism of CO2 corrosion resistance for both weld metals has been proposed.

  16. Mechanical Behavior of Lithium-Ion Batteries and Fatigue Behavior of Ultrasonic Weld-Bonded Lap-Shear Specimens of Dissimilar Magnesium and Steel Sheets

    NASA Astrophysics Data System (ADS)

    Lai, Wei-Jen

    The mechanical behaviors of LiFePO4 battery cell and module specimens under in-plane constrained compression were investigated for simulations of battery cells, modules and packs under crush conditions. The experimental stress-strain curves were correlated to the deformation patterns of battery cell and module specimens. Analytical solutions were developed to estimate the buckling stresses and to provide a theoretical basis for future design of representative volume element cell and module specimens. A physical kinematics model for formation of kinks and shear bands in battery cells was developed to explain the deformation mechanism for layered battery cells under in-plane constrained compression. A small-scale module constrained punch indentation test was also conducted to benchmark the computational results. The computational results indicate that macro homogenized material models can be used to simulate battery modules under crush conditions. Fatigue behavior and failure modes of ultrasonic spot welds in lap-shear specimens of magnesium and steel sheets with and without adhesive were investigated. For ultrasonic spot welded lap-shear specimens, the failure mode changes from the partial nugget pullout mode under low-cycle loading conditions to the kinked crack failure mode under high-cycle loading conditions. For adhesive-bonded and weld-bonded lap-shear specimens, the test results show the near interface cohesive failure mode and the kinked crack failure mode under low-cycle and high-cycle loading conditions, respectively. Next, the analytical effective stress intensity factor solutions for main cracks in lap-shear specimens of three dissimilar sheets under plane strain conditions were developed and the solutions agreed well with the computational results. The analytical effective stress intensity factor solutions for kinked cracks were compared with the computational results at small kink lengths. The results indicate that the computational results approach to

  17. Effect of Dwell Time on Joint Interface Microstructure and Strength of Dissimilar Friction Stir Spot-Welded Al-5083 and St-12 Alloy Sheets

    NASA Astrophysics Data System (ADS)

    Fereiduni, Eskandar; Movahedi, Mojtaba; Kokabi, Amir Hossein; Najafi, Hossein

    2017-04-01

    Joining of Al-5083 alloy sheet to St-12 steel sheet was performed using a new friction stir spot welding (FSSW) technique in which the tool pin tip did not enter lower steel sheet. Effect of dwell time on the microstructure and mechanical properties of the joints was studied by various methods including microhardness measurements, shear test, stereo and light microscopy as well as scanning and transmission electron microscopy (SEM and TEM). Results indicated that compared to the conventional FSSW process, stronger joints can be achieved by this FSSW technique. Cross-sectional observation of the failed specimens indicated the occurrence of final fracture from the circumference of the tool pin where the Al sheet thickness was decreased as a result of the tool pin penetration. However, microhardness measurements introduced these fracture locations as the hardest regions of the Al part of welds. In addition to the Al3Fe and Al5Fe2 intermetallic compounds reported in the literature to form at the interface of dissimilar Al/steel joints, a third layer of AlFe intermetallic compound was also identified adjacent to the steel side of welds. Enhancement of the dwell time from 5 to 15 seconds increased the intermetallic layer thickness from 1.7 to 3 µm and resulted in the formation of harder stirred zone. This consequently increased the strength of the weld.

  18. Effect of Dwell Time on Joint Interface Microstructure and Strength of Dissimilar Friction Stir Spot-Welded Al-5083 and St-12 Alloy Sheets

    NASA Astrophysics Data System (ADS)

    Fereiduni, Eskandar; Movahedi, Mojtaba; Kokabi, Amir Hossein; Najafi, Hossein

    2017-01-01

    Joining of Al-5083 alloy sheet to St-12 steel sheet was performed using a new friction stir spot welding (FSSW) technique in which the tool pin tip did not enter lower steel sheet. Effect of dwell time on the microstructure and mechanical properties of the joints was studied by various methods including microhardness measurements, shear test, stereo and light microscopy as well as scanning and transmission electron microscopy (SEM and TEM). Results indicated that compared to the conventional FSSW process, stronger joints can be achieved by this FSSW technique. Cross-sectional observation of the failed specimens indicated the occurrence of final fracture from the circumference of the tool pin where the Al sheet thickness was decreased as a result of the tool pin penetration. However, microhardness measurements introduced these fracture locations as the hardest regions of the Al part of welds. In addition to the Al3Fe and Al5Fe2 intermetallic compounds reported in the literature to form at the interface of dissimilar Al/steel joints, a third layer of AlFe intermetallic compound was also identified adjacent to the steel side of welds. Enhancement of the dwell time from 5 to 15 seconds increased the intermetallic layer thickness from 1.7 to 3 µm and resulted in the formation of harder stirred zone. This consequently increased the strength of the weld.

  19. Effects of Post-Weld Heat Treatment on the Mechanical Properties of Similar- and Dissimilar-Alloy Friction Stir Welded Blanks

    SciTech Connect

    Zadpoor, Amir Abbas; Sinke, Jos

    2011-01-17

    Friction stir welding is a solid state joining process with relatively low welding temperatures. Nevertheless, the mechanical properties of friction stir welded blanks are degraded after welding. Indeed, both strength and ductility of the welds are decreased after welding. Often, the resulting friction stir welded blanks need to be formed to their final structural shape. Therefore, the formability of friction stir welded blanks is of primary importance in the manufacturing of structural parts. This paper studies how the mechanical properties and particularly formability of friction stir welded blanks can be improved by applying a post weld heat treatment. Two aluminum alloys from 2000 and 7000 series, namely 2024-T3 and 7075-T6, are selected for the study. The sheet thickness of both materials is 2,0 mm. The selected alloys are welded in three configurations: 2024-T3 and 2024-T3, 7075-T6 and 7075-T6, and 2024-T3 and 7075-T6. The resulting welds are naturally aged for a few months. Three sets of standard dog bone shape tensile test specimens are then machined from the welds. The first set of the specimens is tested without any heat treatment. The second set of the specimens is solution heat treated and quenched before testing. The third set of the specimens is solution heat treated, quenched, and naturally aged for a week before testing. The mechanical properties of the three different sets of specimens are compared with each other. It is shown that careful selection of post weld heat-treatment can greatly improve the formability of friction stir welded blanks.

  20. Electrical upsetting of metal sheet forms weld edge

    NASA Technical Reports Server (NTRS)

    Scherba, E. S.

    1966-01-01

    Electric gathering of sheet stock edges forms metal sheets in the shape of gore sections with heavier edge areas that can be welded without loss of strength. The edges are gathered by progressive resistance heating and upsetting, and are formed automatically. This process avoids disturbance of the metals internal structure.

  1. Effect of Individual Layer Shape on the Mechanical Properties of Dissimilar Al Alloys Laminated Metal Composite Sheets

    NASA Astrophysics Data System (ADS)

    Chen, Zejun; Wu, Xia; Hu, Hongbo; Chen, Quanzhong; Liu, Qing

    2014-03-01

    For the dissimilar laminated metal composite sheets (LMCS) fabricated by roll bonding technology, the great differences of mechanical properties between the constituent metals lead to the non-uniform deformation and individual layer necking. The individual layer shape affects the mechanical properties and microstructure of dissimilar LMCS. The Al/Al alloy (1100/7075) LMCS with the same thickness and ratio of dissimilar metals, but different individual layer shapes, have been successfully fabricated by hot accumulative roll bonding in conjunction with cold rolling technology. Some effective methods (such as sheet crown, warp degree, and slant angle) were presented to quantitatively evaluate the individual layer shape and necking of constituent metals. The microstructure and mechanical properties of 1100/7075 LMCS with different individual layer shapes were investigated. The effects of bonding interface on the mechanical properties were obtained based on the assessment of individual layer shapes and necking. The strength and elongation of LMCS decrease with the increase of variation of individual layer shapes and necking when the number of layers keeps constant. The research results offer some theoretical guides and references for adjusting the control measures of compatibility deformation, optimizing the hot roll bonding technologies, and designing the novel high-performance dissimilar LMCS.

  2. Optimization of Gas Metal Arc Welding Process Parameters

    NASA Astrophysics Data System (ADS)

    Kumar, Amit; Khurana, M. K.; Yadav, Pradeep K.

    2016-09-01

    This study presents the application of Taguchi method combined with grey relational analysis to optimize the process parameters of gas metal arc welding (GMAW) of AISI 1020 carbon steels for multiple quality characteristics (bead width, bead height, weld penetration and heat affected zone). An orthogonal array of L9 has been implemented to fabrication of joints. The experiments have been conducted according to the combination of voltage (V), current (A) and welding speed (Ws). The results revealed that the welding speed is most significant process parameter. By analyzing the grey relational grades, optimal parameters are obtained and significant factors are known using ANOVA analysis. The welding parameters such as speed, welding current and voltage have been optimized for material AISI 1020 using GMAW process. To fortify the robustness of experimental design, a confirmation test was performed at selected optimal process parameter setting. Observations from this method may be useful for automotive sub-assemblies, shipbuilding and vessel fabricators and operators to obtain optimal welding conditions.

  3. Dissimilar Friction Stir Welds in Al5186-Al2024: The Effect of Process Parameters on Microstructures and Mechanical Properties

    SciTech Connect

    Mousavi, S. A. A. Akbari; ShamAbadi, S. H.

    2011-01-17

    The effect of tool traverse and rotation speeds on the microstructures and mechanical properties are quantified for welds between non-age-hardening Al5083 and age hardening Al2024 and compared to single alloy joints made from each of the two constituents. In this paper, we report the results of microstructural, mechanical property investigations of Al5186-Al2024 friction stir welds produced using various rotations and traveling speeds of the tool to investigate the effects of the welding parameters on the joint strength. Metallographic studies by optical microscopy, electron probe microscopy, and the utilization of the X-ray diffraction technique have been conducted. It was found that the weld properties were dominated by the thermal input rather than the mechanical deformation by the tool. In particular the larger stresses under the weld tool on the AA5186 side compared to the AA2024 side are related to a transient reduction in yield stress due to dissolution of the hardening precipitates during welding prior to natural aging after welding.

  4. 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...

  5. Fabrication of a single metal nanowire connected with dissimilar metal electrodes and its application to chemical sensing.

    PubMed

    Lin, Hsin-Yu; Chen, Hsiang-An; Lin, Heh-Nan

    2008-03-15

    We report a convenient method for the fabrication of a single metal nanowire connected with dissimilar metal electrodes and its application to chemical sensing. The method is based on a combination of atomic force microscopy nanomachining and conventional photolithography. The success of this integrated approach is confirmed by the linear current-voltage behavior of the created nanowires and comparable resistivities with those reported previously. The chemical sensing capability is demonstrated by the selective binding of a self-assembled monolayer onto a single Au nanowire connected with Ti electrodes and the subsequent resistance increase due to increased surface scattering effects after adsorption. It is found that the resistance increases by around 9% after the complete coverage of either octadecanethiol or dodecanethiol molecules onto a 20 nm thick Au nanowire. A theoretical explanation for the relationship between the resistance increase and the alkanethiol concentration is also given.

  6. Assessment of safety and availability of dissimilar weldments in the water-steam circuit of HTR plants

    NASA Astrophysics Data System (ADS)

    Schneider, Klaus; Gnirss, Günther; Grünling, Hermann

    1990-04-01

    A concept for the assessment of dissimilar weldments in HTR steam piping is described. A combination of experiments and calculation shows that dissimilar metal welds between the ferritic steel X 20 CrMoV 21 1 and the austenitic alloy X 10 NiCrAlTi 32 20 can be operated for the design life of the component. The combination of reliable manufacturing and nondestructive testing assures that defects in weld joints will show only negligible crack growth. The leak before break criterion is fulfilled. The concept of assessment of dissimilar weldments is verified by the component test MINERVA.

  7. Characteristics of Dissimilar FSW Welds of Aluminum Alloys 2017A and 7075 on the Basis of Multiple Layer Research

    NASA Astrophysics Data System (ADS)

    Mroczka, Krzysztof; Wójcicka, Anna; Pietras, Adam

    2013-09-01

    This work is concerned with the structure of the FSW joint of 2017A/7075 aluminum alloys, which was analyzed on the basis of a number of longitudinal and cross-sectional sections. Various ways and degrees of alloy stirring were identified, depending on the distance from the face of the weld. Furthermore, considerable variation in the length of the weld microstructures was demonstrated, reflecting the variability of the welding process. Studies of mechanical properties are also presented—the distributions of hardness on individual layers. A significant effect of plastic deformation on the hardness of the alloy 7075, which strengthened in deformed areas and shows weakness in the heat-affected zone, was noticed. The influence of the weld structure on the fracture of the sample, which was broken in the static tensile test, was analyzed applying scanning electron microscopy. The presence of non-deformed areas was revealed within the ductile fracture of the sample.

  8. Microhardness and Strain Field Characterization of Self-Reacting Friction Stir and Plug Welds of Dissimilar Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Horton, Karla Renee

    2011-01-01

    Friction stir welding (FSW) is a solid state welding process with potential advantages for aerospace and automotive industries dealing with light alloys. Self-reacting friction stir welding (SR-FSW) is one variation of the FSW process being developed at the National Aeronautics and Space Administration (NASA) for use in the fabrication of propellant tanks. Friction plug welding is used to seal the exit hole that remains in a circumferential SR-FSW. This work reports on material properties and strain patterns developed in a SR-FSW with a friction plug weld. Specifically, this study examines the behavior of a SR-FSW formed between an AA 2014-T6 plate on the advancing side and an AA 2219-T87 plate on the retreating side and a SR-FSW (AA 2014-T6 to AA 2219-T87) with a 2219-T87 plug weld. This study presents the results of a characterization of the micro-hardness, joint strength, and strain field characterization of SR-FSW and FPW joints tested at room temperature and cryogenic temperatures.

  9. Effect of Preheating on the Inertia Friction Welding of the Dissimilar Superalloys Mar-M247 and LSHR

    NASA Astrophysics Data System (ADS)

    Senkov, O. N.; Mahaffey, D. W.; Semiatin, S. L.

    2016-12-01

    Differences in the elevated temperature mechanical properties of cast Mar-M247 and forged LSHR make it difficult to produce sound joints of these alloys by inertia friction welding (IFW). While extensive plastic upset occurs on the LSHR side, only a small upset is typically developed on the Mar-M247 side. The limited plastic flow of Mar-M247 thus restricts the extent of "self-cleaning" and mechanical mixing of the mating surfaces, so that defects remain at the bond line after welding. In the present work, the effect of local preheating of Mar-M247 immediately prior to IFW on the welding behavior of Mar-M247/LSHR couples was determined. An increase in the preheat temperature enhanced the plastic flow of Mar-M247 during IFW, which resulted in extensive mechanical mixing with LSHR at the weld interface, the formation of extensive flash on both the Mar-M247 and LSHR sides, and a sound bond. Performed in parallel with the experimental work, finite-element-method (FEM) simulations showed that higher temperatures are achieved within the preheated sample during IFW relative to its non-preheated counterpart, and plastic flow is thus facilitated within it. Microstructure and post-weld mechanical properties of the welded samples were also established.

  10. 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.

  11. Gas metal arc welding in refurbishment of cobalt base superalloys

    NASA Astrophysics Data System (ADS)

    Shahriary, M. S.; Miladi Gorji, Y.; Kolagar, A. M.

    2017-01-01

    Refurbishments of superalloys which are used in manufacturing gas turbine hot components usually consists of removing cracks and other defects by blending and then repair welding in order to reconstruct damaged area. In this study, the effects of welding parameters on repair of FSX-414 superalloy, as the most applicable cobalt base superalloy in order to manufacture gas turbine nozzles, by use of Gas Metal Arc Welding (GMAW) technic were investigated. Results then were compared by Gas Tungsten Arc Welding (GTAW). Metallographic and SEM studies of the microstructure of the weld and HAZ showed that there are no noticeable defects in the microstructure by use of GMAW. Also, chemical analysis and morphologies of carbide in both methods are similar. Hardness profile of the GM AW structure then also compared with GTAW and no noticeable difference was observed between the profiles. Also, proper tensile properties, compared with GTAW, can be achieved by use of optimum parameters that can be obtained by examining the current and welding speed. Tensile properties of optimized condition of the GMAW then were compared with GTAW. It was seen that the room and high temperature tensile properties of the GMAW structure is very similar and results confirmed that changing the technic did not have any significant influence on the properties.

  12. Microhardness, strength and strain field characterization of self-reacting friction stir and plug welds of dissimilar aluminum alloys

    NASA Astrophysics Data System (ADS)

    Horton, Karla Renee

    Friction stir welding (FSW) is a solid state welding process with potential advantages for aerospace and automotive industries dealing with light alloys. Self-reacting friction stir welding (SR-FSW) is one variation of the FSW process being developed at the National Aeronautics and Space Administration (NASA) for use in the fabrication of propellant tanks. Friction plug welding is used to seal the exit hole that remains in a circumferential SR-FSW. This work reports on material properties and strain patterns developed in a SR-FSW with a friction plug weld. Specifically, this study examines the behavior of a SR-FSW formed between an AA2014-T6 plate on the advancing side and an AA2219-T87 plate on the retreating side and a SR-FSW (AA2014-T6 to AA2219-T87) with a 2219-T87 plug weld. This study presents the results of a characterization of the micro-hardness, joint strength, and strain field characterization of SR-FSW and FPW joints tested at room temperature and cryogenic temperatures. The initial weld microstructure analysis showed a nugget region with fine grains and a displaced weld seam from the advancing side past the thermo-mechanical affected zone (TMAZ) into the nugget region. The displaced material shared the same hardness as the parent material. Dynamic recrystallization was observed in the SR-FSW zone and the displaced weld seam region. The welds revealed a fine grain structure in the SR-FSW zone with a sharp demarcation seen on the advancing side and fairly diffuse flow observed on the retreating side. The parent material hardness is 145 HV700g with a drop in hardness starting at the HAZ to 130 HV700g. The hardness further drops in the TMAZ to118 HV700g with an increase representing a dispersed interface of AA2014-T6 material to 135 HV700g. The hardness then drops significantly within the nugget region to 85 HV700g followed by an increase through the retreating side TMAZ into the HAZ to 135 HV 700g. There was a sharp increase in the hardness value within

  13. Career Preparation Program Curriculum Guide for: Metal Fabrication, Welding.

    ERIC Educational Resources Information Center

    British Columbia Dept. of Education, Victoria. Curriculum Development Branch.

    This curriculum outline provides secondary and postsecondary instructors with detailed information on student learning outcomes for completion of the welding/metal fabrication program requirements. A program overview discusses the aims of education; secondary school philosophy; and career preparation programs and their goals, organization, and…

  14. Analysis of thermal stresses and metal movement during welding

    NASA Technical Reports Server (NTRS)

    Muraki, T.; Masubuchi, K.

    1973-01-01

    The research is reported concerning the development of a system of mathematical solutions and computer programs for one- and two-dimensional analyses for thermal stresses. Reports presented include: the investigation of thermal stress and buckling of tantalum and columbium sheet; and analysis of two dimensional thermal strains and metal movement during welding.

  15. The effect of weld stresses on weld quality. [stress fields and metal cracking

    NASA Technical Reports Server (NTRS)

    Chihoski, R. A.

    1972-01-01

    A narrow heat source raises the temperature of a spot on a solid piece of material like metal. The high temperature of the spot decreases with distance from the spot. This is true whether the heat source is an arc, a flame, an electron beam, a plasma jet, a laser beam, or any other source of intense, narrowly defined heat. Stress and strain fields around a moving heat source are organized into a coherent visible system. It is shown that five stresses act across the weld line in turn as an arc passes. Their proportions and positions are considerably altered by weld parameters or condition changes. These pushes and pulls affect the metallurgical character and integrity of the weld area even when there is no apparent difference between after-the-fact examples.

  16. High Temperature Stability of Dissimilar Metal Joints in Fission Surface Power Systems

    SciTech Connect

    Locci, Ivan E.; Nesbitt, James A.; Ritzert, Frank J.; Bowman, Cheryl L.

    2007-01-30

    Future generations of power systems for spacecraft and lunar surface systems will likely require a strong dependence on nuclear power. The design of a space nuclear power plant involves integrating together major subsystems with varying material requirements. Refractory alloys are repeatedly considered for major structural components in space power reactor designs because refractory alloys retain their strength at higher temperatures than other classes of metals. The relatively higher mass and lower ductility of the refractory alloys make them less attractive for lower temperature subsystems in the power plant such as the power conversion system. The power conversion system would consist more likely of intermediate temperature Ni-based superalloys. One of many unanswered questions about the use of refractory alloys in a space power plant is how to transition from the use of the structural refractory alloy to more traditional structural alloys. Because deleterious phases can form when complex alloys are joined and operated at elevated temperatures, dissimilar material diffusion analyses of refractory alloys and superalloys are needed to inform designers about options of joint temperature and operational lifetime. Combinations of four superalloys and six refractory alloys were bonded and annealed at 1150 K and 1300 K to examine diffusional interactions in this study. Joints formed through hot pressing and hot isostatic pressing were compared. Results on newer alloys compared favorably to historical data. Diffusional stability is promising for some combinations of Mo-Re alloys and superalloys at 1150 K, but it appears that lower joint temperatures would be required for other refractory alloy couples.

  17. Shielded Metal Arc Welding Consumables for Advanced High Strength Steels

    DTIC Science & Technology

    1992-02-01

    100 ksi) depends on the availability of adequate welding consumables. In the case of shielded metal arc welding, the electrodes must provide...associated with the potassium silicate binder (K2 SiO3 .nH2 0). The fluxes were then crushed and sized to 14# Tyler mesh (1.7 mm screen aperture) to...determined that the hydrated potassium silicate binder (K2 SiO3 .nH20) used in this investi- gation was 50 wt. pct. potassium silicate (K 2SiO 3 ) and

  18. Effect of Melt-to-Solid Insert Volume Ratio on Mg/Al Dissimilar Metals Bonding

    NASA Astrophysics Data System (ADS)

    Emami, S. M.; Divandari, M.; Arabi, H.; Hajjari, E.

    2013-01-01

    Compound casting is used as a process to join various similar and dissimilar metallic couples. The ratio of melt-to-solid volume is one of the main factors that can affect the contact time between melt and the solid insert. In this investigation, magnesium and aluminum metals (magnesium as the cast metal and aluminum as the solid insert) having melt-to-solid volume ratios ( V m/ V s) of 1.25, 3, and 5.25 were successfully bonded via compound casting. Results demonstrated that by increasing the ratio of V m/ V s from 1.25 to 5.25, the thickness of the reaction interface between Al and Mg varies within the range of 200 to 1800 μm. X-ray diffraction, scanning electron microscopy, and Vickers microhardness study of the bonding of these two metals showed that the interface consisted of three separate sub-layers within reaction layer. These sub-layers had higher hardness than those of the Al and Mg bulk metals. In all specimens, composition of the sub-layer adjacent to Al (layer I) was Al3Mg2 and that adjacent to Mg (layer III) was Al12Mg17/(Mg) eutectic structure. The intermediate layer composition (layer II) in specimens with volume ratio of 1.25 and 3 was a single-phase Al12Mg17, while for the case of volume ratio 5.25 this sub-layer consisted of Al12Mg17/(Mg) eutectic dispersed in Al12Mg17 intermetallic. The results of this research showed that in low melt/solid volume ratios, diffusion-reaction was the dominant mechanism for formation of Al-Mg intermetallic. However, when V m/ V s and the melt/solid insert contact time increased, the dominant mechanism of Al-Mg intermetallics changed to fusion-solidification due to increase in surface melting of the solid insert. Also the results of push-out tests showed that shear strengths of the interface decrease from 27.1 to 15.1 and 8.3 MPa for the Al/Mg couples prepared at 1.25, 3, and 5.25 V m/ V s respectively.

  19. Stability of a pendant droplet in gas metal arc welding

    SciTech Connect

    Murray, P.E.

    1998-07-01

    The authors develop a model of metal transfer in gas metal arc welding and compute the critical mass of a pendant droplet in order to ascertain the size and frequency of droplets detaching from the consumable metal electrode. These results are used to predict the mode of metal transfer for a range of voltage and current encompassing free flight transfer, and the transition between globular and spray transfer. This model includes an efficient method to compute the stability of a pendant droplet and the location of the liquid bridge connecting the primary droplet and the residual liquid remaining after detachment of the primary droplet.

  20. Characterization of Steel-Ta Dissimilar Metal Builds Made Using Very High Power Ultrasonic Additive Manufacturing (VHP-UAM)

    NASA Astrophysics Data System (ADS)

    Sridharan, Niyanth; Norfolk, Mark; Babu, Sudarsanam Suresh

    2016-05-01

    Ultrasonic additive manufacturing is a solid-state additive manufacturing technique that utilizes ultrasonic vibrations to bond metal tapes into near net-shaped components. The major advantage of this process is the ability to manufacture layered structures with dissimilar materials without any intermetallic formation. Majority of the published literature had focused only on the bond formation mechanism in Aluminum alloys. The current work pertains to explain the microstructure evolution during dissimilar joining of iron and tantalum using very high power ultrasonic additive manufacturing and characterization of the interfaces using electron back-scattered diffraction and Nano-indentation measurement. The results showed extensive grain refinement at the bonded interfaces of these metals. This phenomenon was attributed to continuous dynamic recrystallization process driven by the high strain rate plastic deformation and associated adiabatic heating that is well below 50 pct of melting point of both iron and Ta.

  1. Characterization of Mg/Al butt joints welded by gas tungsten arc filling with Zn–29.5Al–0.5Ti filler metal

    SciTech Connect

    Liu, Fei; Wang, Hongyang; Liu, Liming

    2014-04-01

    The multivariate alloying design of a welding joint is used in the Mg to Al welding process. A Zn–29.5Al–0.5Ti alloy is added as filler metal in gas tungsten arc welding of Mg and Al alloy joint based on the analysis of Al and Mg alloy characteristics. The tensile strength, microstructure, and phase constitution of the weld seam are analyzed. The formation of brittle and hard Mg–Al intermetallic compounds is avoided because of the effects of Zn, Al, and Ti. The average tensile strength of the joint is 148 MPa. Al{sub 3}Ti is first precipitated and functions as the nucleus of heterogeneous nucleation during solidification. Moreover, the precipitated Al–MgZn{sub 2} hypoeutectic phase exhibited a feather-like structure, which enhances the property of the Mg–Al dissimilar joint. - Highlights: • Mg alloy AZ31B and Al alloy 6061 are butt welded by fusion welding. • The effect of Ti in filler metal is investigated. • The formation of Mg–Al intermetallic compounds is avoided.

  2. Control of Structure in Conventional Friction Stir Welds Through a Kinematic Theory of Metal Flow

    DTIC Science & Technology

    2009-02-01

    suggested a “chaotic-dynamic mixing” in the material [2]. Later tracer studies, using steel shot [3], aluminum shims [4], copper foil [5], bi-metallic...35812 Keywords: friction stir welding, AA2219, material flow Abstract In friction stir welding ( FSW ), a rotating pin is translated along a...welding, by a shoulder on the pin. In conventional FSW , the weld metal rests on an “anvil”, which supports the heavy “plunge” load on the tool. In

  3. Multiple exposure to metals in eight types of welding.

    PubMed

    Apostoli, P; Porru, S; Brunelli, E; Alessio, L

    1997-01-01

    This article evaluates multiple exposures to metals in different types of metal welding such as manual metal arc for mild and stainless steel, continuous wire, submerged arc, laser and brazing. Environmental monitoring was carried out in eight different occupational situations and the inductively coupled plasma mass spectrometry technique was adopted in order to characterize exposure to several elements simultaneously and with high accuracy. The results showed that up to 23 elements could be measured. The highest concentrations were found for Al, Mn, Fr, Ni, Cr, Cu and Zn. For some elements such as In, Nd, I, Rb the concentrations were very low. A qualitative and quantitative variation in fume composition was observed at a certain distance from the welding point, which should be to taken into account when evaluating indirect exposures. It would also be possible, with this technique, to identify specific elements in the mixture which could also be measured in biological fluids.

  4. Quantitative metal magnetic memory reliability modeling for welded joints

    NASA Astrophysics Data System (ADS)

    Xing, Haiyan; Dang, Yongbin; Wang, Ben; Leng, Jiancheng

    2016-03-01

    Metal magnetic memory(MMM) testing has been widely used to detect welded joints. However, load levels, environmental magnetic field, and measurement noises make the MMM data dispersive and bring difficulty to quantitative evaluation. In order to promote the development of quantitative MMM reliability assessment, a new MMM model is presented for welded joints. Steel Q235 welded specimens are tested along the longitudinal and horizontal lines by TSC-2M-8 instrument in the tensile fatigue experiments. The X-ray testing is carried out synchronously to verify the MMM results. It is found that MMM testing can detect the hidden crack earlier than X-ray testing. Moreover, the MMM gradient vector sum K vs is sensitive to the damage degree, especially at early and hidden damage stages. Considering the dispersion of MMM data, the K vs statistical law is investigated, which shows that K vs obeys Gaussian distribution. So K vs is the suitable MMM parameter to establish reliability model of welded joints. At last, the original quantitative MMM reliability model is first presented based on the improved stress strength interference theory. It is shown that the reliability degree R gradually decreases with the decreasing of the residual life ratio T, and the maximal error between prediction reliability degree R 1 and verification reliability degree R 2 is 9.15%. This presented method provides a novel tool of reliability testing and evaluating in practical engineering for welded joints.

  5. Microstructure, Texture, and Mechanical Property Analysis of Gas Metal Arc Welded AISI 304 Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Saha, Saptarshi; Mukherjee, Manidipto; Pal, Tapan Kumar

    2015-03-01

    The present study elaborately explains the effect of welding parameters on the microstructure, texture, and mechanical properties of gas metal arc welded AISI 304 austenitic stainless steel sheet (as received) of 4 mm thickness. The welded joints were prepared by varying welding speed (WS) and current simultaneously at a fixed heat input level using a 1.2-mm-diameter austenitic filler metal (AISI 316L). The overall purpose of this study is to investigate the effect of the variation of welding conditions on: (i) Microstructural constituents using optical microscope and transmission electron microscope; (ii) Micro-texture evolution, misorientation distributions, and grain boundaries at welded regions by measuring the orientation data from electron back scattered diffraction; and (iii) Mechanical properties such as hardness and tensile strength, and their correlation with the microstructure and texture. It has been observed that the higher WS along with the higher welding current (weld metal W1) can enhance weld metal mechanical properties through alternation in microstructure and texture of the weld metal. Higher δ-ferrite formation and high-angle boundaries along with the <101> + <001> grain growth direction of the weld metal W1 were responsible for dislocation pile-ups, SFs, deformation twinning, and the induced martensite with consequent strain hardening during tensile deformation. Also, fusion boundary being the weakest link in the welded structure, failure took place mainly at this region.

  6. 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.

  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. 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.

  9. High Temperature Stability of Dissimilar Metal Joints in Fission Surface Power Systems

    NASA Technical Reports Server (NTRS)

    Locci, Ivan E.; Nesbitt, James A.; Ritzert, Frank J.; Bowman, Cheryl L.

    2007-01-01

    Future generations of power systems for spacecraft and lunar surface systems will likely require a strong dependence on nuclear power. The design of a space nuclear power plant involves integrating together major subsystems with varying materia1 requirements. Refractory alloys are repeatedly considered for major structural components in space power reactor designs because refractory alloys retain their strength at higher temperatures than other classes of metals. The relatively higher mass and lower ductility of the refractory alloys make them less attractive for lower temperature subsystems in the power plant such as the power conversion system. The power conversion system would consist more likely of intermediate temperature Ni-based superalloys. One of many unanswered questions about the use of refractory alloys in a space power plant is how to transition from the use of the structural refractory alloy to more traditional structural alloys. Because deleterious phases can form when complex alloys are joined and operated at elevated temperatures, dissimilar material diffusion analyses of refractory alloys and superalloys are needed to inform designers about options of joint temperature and operational lifetime. Combinations of four superalloys and six refractory alloys were bonded and annealed at 1150 K and 1300 K to examine diffusional interactions in this study. Joints formed through hot pressing and hot isostatic pressing were compared. Results on newer alloys compared favorably to historical data. Diffusional stability is promising for some combinations of Mo-Re alloys and superalloys at 1150 K, but it appears that lower joint temperatures would be required for other refractory alloy couples.

  10. Fractal Analysis of Metal Transfer in Mig/mag Welding

    NASA Astrophysics Data System (ADS)

    Vieira, A. P.; Vasconcelos, H. H. M.; Gonçalves, L. L.; de Miranda, H. C.

    2009-03-01

    We apply techniques of fractal analysis in order to classify metal-transfer mode in MIG/MAG (metal inert/active gas) welding, which are among the most commonly employed arc-fusion processes for industrial applications. We work with voltage and current time series obtained during welding, and evaluate statistical fluctuations present in those series by Hurst, detrended-fluctuation, and detrended-cross-correlation analyses, for each of three different metal-transfer modes: short-circuiting, globular, and spray. For a given total timespan of each series, curves of fluctuation as a funtion of the time-window size are processed by using pattern-classification techniques, such as principal-component analysis and Karhunen-Loève expansions. We obtain near 100% success rate for the classification, with timespans as small as 100 miliseconds, with a processing time of the same order. This suggests that our set of tools can be incorporated into an industrial welding apparatus in order to guarantee automatic correction of a process requiring a single metal-transfer mode.

  11. Control of Structure in Conventional Friction Stir Welds through a Kinematic Theory of Metal Flow

    NASA Technical Reports Server (NTRS)

    Rubisoff, H.A.; Schneider, J.A.; Nunes, A.C.

    2009-01-01

    In friction stir welding (FSW), a rotating pin is translated along a weld seam so as to stir the sides of the seam together. Metal is prevented from flowing up the pin, which would result in plowing/cutting instead of welding, by a shoulder on the pin. In conventional FSW, the weld metal rests on an "anvil", which supports the heavy "plunge" load on the tool. In this study, both embedded tungsten wires along and copper plating on the faying surfaces were used to trace the flow of AA2219 weld metal around the C-FSW tool. The effect of tool rotational speed, travel speed, plunge load, and pin thread pitch on the resulting weld metal flow was evaluated. Plan, longitudinal, and transverse section x-ray radiographs were examined to trace the metal flow paths. The results are interpreted in terms of a kinematic theory of metal flow in FSW.

  12. The temporal nature of forces acting on metal drops in gas metal arc welding

    SciTech Connect

    Jones, L.A.; Eagar, T.W.; Lang, J.H.

    1996-12-31

    At moderate and high welding currents, the most important forces in gas metal arc welding acting on the molten electrode are magnetic forces arising from the interaction between the welding current and its own magnetic field. These forces drive the dynamic evolution of the drop and also depend on the instantaneous shape of the drop. In this paper, experimentally observed manifestations of magnetic forces are shown, and a technique for approximating the temporal evolution of these forces from experimentally measured drop shapes is reported. The technique provides quantitative data illustrating the large increase in the magnetic forces as a drop detaches from the electrode.

  13. Optical emission spectroscopy of metal vapor dominated laser-arc hybrid welding plasma

    SciTech Connect

    Ribic, B.; DebRoy, T.; Burgardt, P.

    2011-04-15

    During laser-arc hybrid welding, plasma properties affect the welding process and the weld quality. However, hybrid welding plasmas have not been systematically studied. Here we examine electron temperatures, species densities, and electrical conductivity for laser, arc, and laser-arc hybrid welding using optical emission spectroscopy. The effects of arc currents and heat source separation distances were examined because these parameters significantly affect weld quality. Time-average plasma electron temperatures, electron and ion densities, electrical conductivity, and arc stability decrease with increasing heat source separation distance during hybrid welding. Heat source separation distance affects these properties more significantly than the arc current within the range of currents considered. Improved arc stability and higher electrical conductivity of the hybrid welding plasma result from increased heat flux, electron temperatures, electron density, and metal vapor concentrations relative to arc or laser welding.

  14. Computational Modeling of Microstructural-Evolution in AISI 1005 Steel During Gas Metal Arc Butt Welding

    DTIC Science & Technology

    2013-05-01

    of the commercially available metallic materials, in particular, steels (including stainless steels ), super alloys, aluminum alloys, etc.; (b) welding...REPORT Computational Modeling of Microstructural-Evolution in AISI 1005 Steel During Gas Metal Arc Butt Welding 14. ABSTRACT 16. SECURITY...Computational Modeling of Microstructural-Evolution in AISI 1005 Steel During Gas Metal Arc Butt Welding Report Title ABSTRACT A fully coupled (two-way

  15. Friction welded nonconsumable electrode assembly and use thereof for electrolytic production of metals and silicon

    DOEpatents

    Byrne, Stephen C.; Ray, Siba P.; Rapp, Robert A.

    1984-01-01

    A nonconsumable electrode assembly suitable for use in the production of metal by electrolytic reduction of a metal compound dissolved in a molten salt, the assembly comprising a metal conductor and a ceramic electrode body connected by a friction weld between a portion of the body having a level of free metal or metal alloy sufficient to effect such a friction weld and a portion of the metal conductor.

  16. Elements of arc welding

    SciTech Connect

    Not Available

    1993-07-01

    This paper looks at the following arc welding techniques: (1) shielded metal-arc welding; (2) submerged-arc welding; (3) gas metal-arc welding; (4) flux-cored arc welding; (5) electrogas welding; (6) gas tungsten-arc welding; and (7) plasma-arc welding.

  17. 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.

  18. Metal flow of a tailor-welded blank in deep drawing process

    NASA Astrophysics Data System (ADS)

    Yan, Qi; Guo, Ruiquan

    2005-01-01

    Tailor welded blanks were used in the automotive industry to consolidate parts, reduce weight, and increase safety. In recent years, this technology was developing rapidly in China. In Chinese car models, tailor welded blanks had been applied in a lot of automobile parts such as rail, door inner, bumper, floor panel, etc. Concerns on the properties of tailor welded blanks had become more and more important for automobile industry. A lot of research had shown that the strength of the welded seam was higher than that of the base metal, such that the weld failure in the aspect of strength was not a critical issue. However, formability of tailor welded blanks in the stamping process was complex. Among them, the metal flow of tailor welded blanks in the stamping process must be investigated thoroughly in order to reduce the scrap rate during the stamping process in automobile factories. In this paper, the behavior of metal flow for tailor welded blanks made by the laser welding process with two types of different thickness combinations were studied in the deep drawing process. Simulations and experiment verification of the movement of weld line for tailor welded blanks were discussed in detail. Results showed that the control on the movement of welded seam during stamping process by taking some measures in the aspect of blank holder was effective.

  19. 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.

  20. A comparative evaluation of welding consumables for dissimilar weids between 316LN austenitic stainless steel and Alloy 800

    NASA Astrophysics Data System (ADS)

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

    2000-03-01

    Transition joints in power plants between ferritic steels and austenitic stainless steels suffer from a mismatch in coefficients of thermal expansion (CTE) and the migration of carbon during service from the ferritic to the austenitic steel. To overcome these, nickel-based consumables are commonly used. The use of a trimetallic combination with an insert piece of intermediate CTE provides for a more effective lowering of thermal stresses. The current work envisages a trimetallic joint involving modified 9Cr-1Mo steel and 316LN austenitic stainless steel as the base materials and Alloy 800 as the intermediate piece. Of the two joints involved, this paper describes the choice of welding consumables for the joint between Alloy 800 and 316LN. Four consumables were examined: 316, 16-8-2, Inconel 82 and Inconel 182. The comparative evaluation was based on hot cracking tests and estimation of mechanical properties and coefficient of thermal expansion. While 16-8-2 exhibited highest resistance to solidification cracking, the Inconel filler materials also showed adequate resistance; additionally, the latter were superior from the mechanical property and coefficient of thermal expansion view-points. It is therefore concluded that for the joint between Alloy 800 and 316LN the Inconel filler materials offer the best compromise.

  1. Automatic Submerged ARC Welding With Metal Power Additions to Increase Productivity and Maintain Quality

    DTIC Science & Technology

    1986-06-01

    Manager of Welding Engineering PROPOSAL WELDING OF CARBON STEEL AND HY80 UTILIZING THE BULK WELDING PROCESS May 9, 1983 PREPARED BY: NEWPORT NEwS...12 joints with carbon steel and 12 with HY80 , utilizing three The joints will requirements of Benefits 1. Deposition times that different size double...of Joint Variations and Deposition Rates Filler Metal/Base Material Chemical Analyses; Carbon Steel /HIS Filler Metal/Base Material Chemical Analyses

  2. Study of issues in difficult-to-weld thick materials by hybrid laser arc welding

    NASA Astrophysics Data System (ADS)

    Mazar Atabaki, Mehdi

    There is a high interest for the high strength-to-weight ratio with good ductility for the welds of advanced alloys. The concern about the welding of thick materials (Advanced high strength steels (AHSS) and 5xxx and 6xxx series of aluminum alloys) has stimulated the development of manufacturing processes to overcome the associated issues. The need to weld the dissimilar materials (AHSS and aluminum alloys) is also required for some specific applications in different industries. Hence, the requirement in the development of a state-of-the-art welding procedure can be helpful to fulfill the constraints. Among the welding methods hybrid laser/arc welding (HLAW) has shown to be an effective method to join thick and difficult-to-weld materials. This process benefits from both advantages of the gas metal arc welding (GMAW) and laser welding processes. The interaction of the arc and laser can help to have enough penetration of weld in thick plates. However, as the welding of dissimilar aluminum alloys and steels is very difficult because of the formation of brittle intermetallics the present work proposed a procedure to effectively join the alloys. The reports showed that the explosively welded aluminum alloys to steels have the highest toughness, and that could be used as an "insert" (TRICLAD) for welding the thick plates of AHSS to aluminum alloys. Therefore, the HLAW of the TRICLAD-Flange side (Aluminum alloy (AA 5456)) to the Web side (Aluminum alloys (AA 6061 and AA 5456)) and the TRICLAD-Flange side (ASTM A516) to the Web side (AHSS) was studied in the present work. However, there are many issues related to HLAW of the dissimilar steels as well as dissimilar aluminum alloys that have to be resolved in order to obtain sound welds. To address the challenges, the most recent welding methods for joining aluminum alloys to steels were studied and the microstructural development, mechanical properties, and on-line monitoring of the welding processes were discussed as well

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

    SciTech Connect

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

    1995-02-01

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

  4. Sheet metal welding using a pulsed Nd: YAG laser-robot

    NASA Astrophysics Data System (ADS)

    Huang, Qi; Kullberg, Gunnar; Skoog, Hans

    This paper presents a pulsed Nd: YAG laser-robot system for spot and seam welding of mild steel sheets. The study evaluates the laser beams behaviour for welding, and then investigates pulsed Nd: YAG laser spot and seam welding processes. High pulse power intensity is needed to initiate the key-hole welding process and a threshold pulse energy to reach full penetration. In seam welding, a weld consists of successive overlapping spots. Both high pulse energy and high average power are needed to keep the key-hole welding going. A 70% overlap is used to define overlapping spot welding as seam welding and to optimize process parameters because a high tensile strength joint compatible with the strength of the base material can be obtained when the overlap is ≥ 70%; at the same time a smooth seam with full penetration is obtained. In these cases, the joints in pulsed Nd: YAG laser welding are comparable in strength to those obtained with CO 2 laser welding. Robot positioning and motion accuracies can meet the demands of Nd: YAG laser sheet metal welding, but its cornering accuracy affects the welding processes. The purpose of the study is to evaluate the YAG laser-robot system for production in the automotive industry.

  5. Finite element based simulation on friction stud welding of metal matrix composites to steel

    NASA Astrophysics Data System (ADS)

    Hynes, N. Rajesh Jesudoss; Tharmaraj, R.; Velu, P. Shenbaga; Kumar, R.

    2016-05-01

    Friction welding is a solid state joining technique used for joining similar and dissimilar materials with high integrity. This new technique is being successfully applied to the aerospace, automobile, and ship building industries, and is attracting more and more research interest. The quality of Friction Stud Welded joints depends on the frictional heat generated at the interface. Hence, thermal analysis on friction stud welding of stainless steel (AISI 304) and aluminium silicon carbide (AlSiC) combination is carried out in the present work. In this study, numerical simulation is carried out using ANSYS software and the temperature profiles are predicted at various increments of time. The developed numerical model is found to be adequate to predict temperature distribution of friction stud weld aluminium silicon carbide/stainless steel joints.

  6. Diffusion welded nonconsumable electrode assembly and use thereof for electrolytic production of metals and silicon

    DOEpatents

    Byrne, Stephen C.; Vasudevan, Asuri K.

    1984-01-01

    A nonconsumable electrode assembly suitable for use in the production of metal by electrolytic reduction of a metal compound dissolved in a molten salt, the assembly comprising a metal conductor diffusion welded to a portion of a ceramic electrode body having a level of free metal or metal alloy sufficient to effect a metal bond.

  7. 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.''...

  8. Occupational asthma due to gas metal arc welding on mild steel.

    PubMed Central

    Vandenplas, O.; Dargent, F.; Auverdin, J. J.; Boulanger, J.; Bossiroy, J. M.; Roosels, D.; Vande Weyer, R.

    1995-01-01

    Occupational asthma has been documented in electric arc welders exposed to manual metal arc welding on stainless steel. A subject is described who developed late and dual asthmatic reactions after occupational-type challenge exposure to gas metal arc welding on uncoated mild steel. PMID:7597679

  9. Metal cutting analogy for establishing Friction Stir Welding process parameters

    NASA Astrophysics Data System (ADS)

    Stafford, Sylvester Allen

    A friction stir weld (FSW) is a solid state joining operation whose processing parameters are currently determined by lengthy trial and error methods. To implement FSWing rapidly in various applications will require an approach for predicting process parameters based on the physics of the process. Based on hot working conditions for metals, a kinematic model has been proposed for calculating the shear strain and shear strain rates during the FSW process, validation of the proposed model with direct measuring is difficult however. Since the shear strain and shear strain rates predicted for the FSW process, are similar to those predicted in metal cutting, validation of the FSW algorithms with microstructural studies of metal chips may be possible leading to the ability to predict FSW processing parameters.

  10. Designing shielded metal arc consumables for underwater wet welding in offshore applications

    SciTech Connect

    Sanchez-Osio, A.; Liu, S.; Olson, D.L.; Ibarra, S.

    1995-08-01

    The use of underwater wet welding for offshore repairs has been limited mainly because of porosity and low toughness in the resulting welds. With appropriate consumable design, however, it is possible to reduce porosity and to enhance weld metal toughness through microstructural refinement. New titanium and boron-based consumables have been developed with which high toughness acicular ferrite (AF) can be produced in underwater wet welds. Titanium, by means of oxide formation, promoted an increase in the amount of acicular ferrite in the weld metal, while boron additions decreased the amount of grain boundary ferrite (GBF), further improving the microstructure. Porosity reduction was possible through the addition of calcium carbonate at approximately 13 wt percent in the electrode coating. However, weld metal decarbonization also resulted with the addition of carbonate.

  11. Fracture toughness of austenitic stainless steel weld metal at 4 K

    SciTech Connect

    Goodwin, G.M.

    1984-08-01

    Selection of the welding processess and weld filler metals for fabrication of a large toroidal superconducting magnet is described. Data available in the literature are collected and compared with data generated in this study for three welding processes, shielded metal arc (SMA), gas tungsten arc (GTA), and flux cored arc (FCA) welds had the highest fracture toughness as measured by K/sub Ic/ estimated from J/sub Ic/. The SMA and FCA welds had about the same toughness, below the GTA values but above the average from the literature. The fracture mode for all three processes was typified by ductile dimples. The fracture morphology of the FCA weld specimens was influenced by the solidification substructure, and small particles were found to be nucleation sites for void formation, especially for the GTA welds. All three welding processes were deemed adequate for the intended service and were used to fabricate the large magnet. A trunnion-type turning fixture eliminated the need for welding in the vertical and overhead positions. The GTA process was used for all root passes, and the horizontal welds were filled by the SMA process. Over 80% of the welds were done in the flat position with the FCA process, and its high deposition rate and ease of operation are credited with contributing greatly to the success of the effort.

  12. Welding.

    ERIC Educational Resources Information Center

    Lehigh County Area Vocational-Technical School, Schnecksville, PA.

    This curriculum guide provides materials for a 12-unit secondary course in welding. Purpose stated for the flexible entry and exit course is to help students master manipulative skills to develop successful welding techniques and to gain an understanding of the specialized tools and equipment used in the welding field. Units cover oxyacetylene…

  13. Effect of Boric Acid Concentration on Viscosity of Slag and Property of Weld Metal Obtained from Underwater Wet Welding

    NASA Astrophysics Data System (ADS)

    Guo, Ning; Guo, Wei; Xu, Changsheng; Du, Yongpeng; Feng, Jicai

    2015-06-01

    Underwater wet welding is a crucial repair and maintenance technology for nuclear plant. A boric acid environment raises a new challenge for the underwater welding maintenance of nuclear plant. This paper places emphasis on studying the influence of a boric acid environment in nuclear plant on the underwater welding process. Several groups of underwater wet welding experiments have been conducted in boric acid aqueous solution with different concentration (0-35000 ppm). The viscosity of the welding slag and the mechanical properties of welds, such as the hardness, strength, and elongation, have been studied. The results show that with increasing boric acid concentration, the viscosity of the slag decreases first and then increases at a lower temperature (less than 1441 °C). However, when the temperature is above 1480 °C, the differences between the viscosity measurements become less pronounced, and the viscosity tends to a constant value. The hardness and ductility of the joints can be enhanced significantly, and the maximum strength of the weld metal can be reached at 2300 ppm.

  14. Mechanical properties of dissimilar metal joints composed of DP 980 steel and AA 7075-T6

    DOE PAGES

    Squires, Lile; Lim, Yong Chae; Miles, Michael; ...

    2015-03-18

    In this study, a solid state joining process, called friction bit joining, was used to spot weld aluminium alloy 7075-T6 to dual phase 980 steel. Lap shear failure loads for specimens without adhesive averaged ~10kN, while cross-tension specimens averaged 2·8 kN. Addition of adhesive with a thickness up to 500 μm provided a gain of ~50% to lap shear failure loads, while a much thinner layer of adhesive increased cross-tension failure loads by 20%. Microstructures of the welds were martensitic, but the hardness of the joining bit portion was greater than that of the DP 980, owing to its highermore » alloy content. Softening in the heat affected zone of a welded joint appeared to be relatively small, though it was enough to cause nugget pullout failures in some lap shear tension specimens. Finally, other failures in lap shear tension were interfacial, while all of the failures in cross-tension were interfacial.« less

  15. Mechanical properties of dissimilar metal joints composed of DP 980 steel and AA 7075-T6

    SciTech Connect

    Squires, Lile; Lim, Yong Chae; Miles, Michael; Feng, Zhili

    2015-03-18

    In this study, a solid state joining process, called friction bit joining, was used to spot weld aluminium alloy 7075-T6 to dual phase 980 steel. Lap shear failure loads for specimens without adhesive averaged ~10kN, while cross-tension specimens averaged 2·8 kN. Addition of adhesive with a thickness up to 500 μm provided a gain of ~50% to lap shear failure loads, while a much thinner layer of adhesive increased cross-tension failure loads by 20%. Microstructures of the welds were martensitic, but the hardness of the joining bit portion was greater than that of the DP 980, owing to its higher alloy content. Softening in the heat affected zone of a welded joint appeared to be relatively small, though it was enough to cause nugget pullout failures in some lap shear tension specimens. Finally, other failures in lap shear tension were interfacial, while all of the failures in cross-tension were interfacial.

  16. Optimization of Gas Metal Arc Welding (GMAW) Process for Maximum Ballistic Limit in MIL A46100 Steel Welded All-Metal Armor

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Ramaswami, S.; Snipes, J. S.; Yavari, R.; Yen, C.-F.; Cheeseman, B. A.

    2015-01-01

    Our recently developed multi-physics computational model for the conventional gas metal arc welding (GMAW) joining process has been upgraded with respect to its predictive capabilities regarding the process optimization for the attainment of maximum ballistic limit within the weld. The original model consists of six modules, each dedicated to handling a specific aspect of the GMAW process, i.e., (a) electro-dynamics of the welding gun; (b) radiation-/convection-controlled heat transfer from the electric arc to the workpiece and mass transfer from the filler metal consumable electrode to the weld; (c) prediction of the temporal evolution and the spatial distribution of thermal and mechanical fields within the weld region during the GMAW joining process; (d) the resulting temporal evolution and spatial distribution of the material microstructure throughout the weld region; (e) spatial distribution of the as-welded material mechanical properties; and (f) spatial distribution of the material ballistic limit. In the present work, the model is upgraded through the introduction of the seventh module in recognition of the fact that identification of the optimum GMAW process parameters relative to the attainment of the maximum ballistic limit within the weld region entails the use of advanced optimization and statistical sensitivity analysis methods and tools. The upgraded GMAW process model is next applied to the case of butt welding of MIL A46100 (a prototypical high-hardness armor-grade martensitic steel) workpieces using filler metal electrodes made of the same material. The predictions of the upgraded GMAW process model pertaining to the spatial distribution of the material microstructure and ballistic limit-controlling mechanical properties within the MIL A46100 butt weld are found to be consistent with general expectations and prior observations.

  17. ARc Welding (Industrial Processing Series).

    DTIC Science & Technology

    ARC WELDING , *BIBLIOGRAPHIES), (*ARC WELDS, BIBLIOGRAPHIES), ALUMINUM ALLOYS, TITANIUM ALLOYS, CHROMIUM ALLOYS, METAL PLATES, SPOT WELDING , STEEL...INERT GAS WELDING , MARAGING STEELS, MICROSTRUCTURE, HEAT RESISTANT ALLOYS, HEAT RESISTANT METALS, WELDABILITY, MECHANICAL PROPERTIES, MOLYBDENUM ALLOYS, NICKEL ALLOYS, RESISTANCE WELDING

  18. Fracture mechanics characterization of welds: Fatigue life analysis of notches at welds: J(sub Ic) fracture toughness tests for weld metal

    NASA Astrophysics Data System (ADS)

    Underwood, John H.

    1995-03-01

    In this report two methods of fracture analysis of welds will be emphasized, one addressing fatigue life testing and analysis of notches at welds, and the other addressing the final fracture of the welded component and the fracture toughness tests used to characterize final fracture. These fatigue and fracture methods will be described by referring to recent work from the technical literature and from the U.S. Army Armament Research, Development, and Engineering Center, primarily fracture case study and fracture test method development investigations. A brief general summary will be given of fatigue and fracture methods and concepts that have application to welded structures. Specific fatigue crack initiation tests and analysis methods will be presented, using example results from a welded stainless steel box beam of a cannon carriage. Recent improvements and simplifications in J.integral fracture toughness tests will be described, particularly those related to welds. Fracture toughness measurements for various stainless steel weld metals and heat treatments will also be described.

  19. Diffusion welding of a directionally solidified gamma/gamma prime - delta eutectic alloy

    NASA Technical Reports Server (NTRS)

    Moore, T. J.

    1977-01-01

    Hot-press diffusion welding parameters were developed for a directionally solidified, gamma/gamma prime-delta eutectic alloy. Based on metallography, a good diffusion weld was achieved at 1100 C under 34.5 MPa (5 ksi) pressure for 1 hour. In addition, a dissimilar metal weld between gamma/gamma prime-delta and IN-100 was successfully made at 1100 C under 20.7 MPa (3 ksi) pressure for 1 hour.

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

  1. 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.

  2. The Concept of Electrically Assisted Friction Stir Welding (EAFSW) and Application to the Processing of Various Metals

    DTIC Science & Technology

    2008-09-01

    TZM) 2617 5.2 Good for Al, some success with mild steel , bronze & Ti- 6-4 Steel (SS, tool, mild) -1540 10-70 Good for aluminum alloys Tantalum 2996...lbs. This compares with forces of about 1000 lbs or so for conventional FSW welds in aluminum . With optimization of parameters, a higher weld speed...welding ( FSW ). Since 1991, friction stir welding provides an alternative to arc welding as a metal joining method in numerous applications. In FSW

  3. 30 CFR 57.15007 - Protective equipment or clothing for welding, cutting, or working with molten metal.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Protective equipment or clothing for welding... equipment or clothing for welding, cutting, or working with molten metal. Protective clothing or equipment and face shields or goggles shall be worn when welding, cutting, or working with molten metal....

  4. 30 CFR 56.15007 - Protective equipment or clothing for welding, cutting, or working with molten metal.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Protective equipment or clothing for welding... METAL AND NONMETAL MINES Personal Protection § 56.15007 Protective equipment or clothing for welding... be worn when welding, cutting, or working with molten metal....

  5. 30 CFR 56.15007 - Protective equipment or clothing for welding, cutting, or working with molten metal.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Protective equipment or clothing for welding... METAL AND NONMETAL MINES Personal Protection § 56.15007 Protective equipment or clothing for welding... be worn when welding, cutting, or working with molten metal....

  6. 30 CFR 57.15007 - Protective equipment or clothing for welding, cutting, or working with molten metal.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Protective equipment or clothing for welding... equipment or clothing for welding, cutting, or working with molten metal. Protective clothing or equipment and face shields or goggles shall be worn when welding, cutting, or working with molten metal....

  7. 30 CFR 56.15007 - Protective equipment or clothing for welding, cutting, or working with molten metal.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Protective equipment or clothing for welding... METAL AND NONMETAL MINES Personal Protection § 56.15007 Protective equipment or clothing for welding... be worn when welding, cutting, or working with molten metal....

  8. 30 CFR 57.15007 - Protective equipment or clothing for welding, cutting, or working with molten metal.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Protective equipment or clothing for welding... equipment or clothing for welding, cutting, or working with molten metal. Protective clothing or equipment and face shields or goggles shall be worn when welding, cutting, or working with molten metal....

  9. 30 CFR 57.15007 - Protective equipment or clothing for welding, cutting, or working with molten metal.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Protective equipment or clothing for welding... equipment or clothing for welding, cutting, or working with molten metal. Protective clothing or equipment and face shields or goggles shall be worn when welding, cutting, or working with molten metal....

  10. 30 CFR 56.15007 - Protective equipment or clothing for welding, cutting, or working with molten metal.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Protective equipment or clothing for welding... METAL AND NONMETAL MINES Personal Protection § 56.15007 Protective equipment or clothing for welding... be worn when welding, cutting, or working with molten metal....

  11. Determinants of occupational exposure to metals by gas metal arc welding and risk management measures: a biomonitoring study.

    PubMed

    Persoons, Renaud; Arnoux, Damien; Monssu, Théodora; Culié, Olivier; Roche, Gaëlle; Duffaud, Béatrice; Chalaye, Denis; Maitre, Anne

    2014-12-01

    Welding fumes contain various toxic metals including chromium (Cr), nickel (Ni) and manganese (Mn). An assessment of the risk to health of local and systemic exposure to welding fumes requires the assessment of both external and internal doses. The aims of this study were to test the relevance in small and medium sized enterprises of a biomonitoring strategy based on urine spot-samples, to characterize the factors influencing the internal doses of metals in gas metal arc welders and to recommend effective risk management measures. 137 welders were recruited and urinary levels of metals were measured by ICP-MS on post-shift samples collected at the end of the working week. Cr, Ni and Mn mean concentrations (respectively 0.43, 1.69 and 0.27 μg/g creatinine) were well below occupational health guidance values, but still higher than background levels observed in the general population, confirming the absorption of metals generated in welding fumes. Both welding parameters (nature of base metal, welding technique) and working conditions (confinement, welding and grinding durations, mechanical ventilation and welding experience) were predictive of occupational exposure. Our results confirm the interest of biomonitoring for assessing health risks and recommending risk management measures for welders.

  12. The Application of Stress-Relaxation Test to Life Assessment of T911/T22 Weld Metal

    NASA Astrophysics Data System (ADS)

    Cao, Tieshan; Zhao, Jie; Cheng, Congqian; Li, Huifang

    2016-03-01

    A dissimilar weld metal was obtained through submerged arc welding of a T911 steel to a T22 steel, and its creep property was explored by stress-relaxation test assisted by some conventional creep tests. The creep rate information of the stress-relaxation test was compared to the minimum and the average creep rates of the conventional creep test. Log-log graph showed that the creep rate of the stress-relaxation test was in a linear relationship with the minimum creep rate of the conventional creep test. Thus, the creep rate of stress-relaxation test could be used in the Monkman-Grant relation to calculate the rupture life. The creep rate of the stress-relaxation test was similar to the average creep rate, and thereby the rupture life could be evaluated by a method of "time to rupture strain." The results also showed that rupture life which was assessed by the Monkman-Grant relation was more accurate than that obtained through the method of "time to rupture strain."

  13. Modeling of Fume Formation from Shielded Metal Arc Welding Process

    NASA Astrophysics Data System (ADS)

    Sivapirakasam, S. P.; Mohan, Sreejith; Santhosh Kumar, M. C.; Surianarayanan, M.

    2017-01-01

    In this study, a semi-empirical model of fume formation rate (FFR) from a shielded metal arc welding (SMAW) process has been developed. The model was developed for a DC electrode positive (DCEP) operation and involves the calculations of droplet temperature, surface area of the droplet, and partial vapor pressures of the constituents of the droplet to predict the FFR. The model was further extended for predicting FFR from nano-coated electrodes. The model estimates the FFR for Fe and Mn assuming constant proportion of other elements in the electrode. Fe FFR was overestimated, while Mn FFR was underestimated. The contribution of spatters and other mechanism in the arc responsible for fume formation were neglected. A good positive correlation was obtained between the predicted and experimental FFR values which highlighted the usefulness of the model.

  14. Modeling of Fume Formation from Shielded Metal Arc Welding Process

    NASA Astrophysics Data System (ADS)

    Sivapirakasam, S. P.; Mohan, Sreejith; Santhosh Kumar, M. C.; Surianarayanan, M.

    2017-04-01

    In this study, a semi-empirical model of fume formation rate (FFR) from a shielded metal arc welding (SMAW) process has been developed. The model was developed for a DC electrode positive (DCEP) operation and involves the calculations of droplet temperature, surface area of the droplet, and partial vapor pressures of the constituents of the droplet to predict the FFR. The model was further extended for predicting FFR from nano-coated electrodes. The model estimates the FFR for Fe and Mn assuming constant proportion of other elements in the electrode. Fe FFR was overestimated, while Mn FFR was underestimated. The contribution of spatters and other mechanism in the arc responsible for fume formation were neglected. A good positive correlation was obtained between the predicted and experimental FFR values which highlighted the usefulness of the model.

  15. Development of welded metal bellows having minimum effective diameter change

    NASA Technical Reports Server (NTRS)

    Henschel, J. K.; Stevens, J. B.; Harvey, A. C.; Howland, J. S.; Rhee, S. S.

    1972-01-01

    A program of analysis, design, and fabrication was conducted to develop welded metal bellows having a minimum change in effective diameter for cryogenic turbomachinery face seal applications. Linear analysis of the principle types of bellows provided identification of concepts capable of meeting basic operation requirements. For the 6-inch (.152 m) mean diameter, 1.5-inch free length bellows studied, nonlinear analysis showed that opposed and nested toroidal bellows plates stiffened by means of alternating stiffener rings were capable of maintaining constant effective diameter within 0.3% and 0.1% respectively under the operating conditions of interest. Changes in effective diameter were due principally to bellows axial deflection with pressure differential having a lesser influence. Fabrication problems associated with joining the thin bellows plates to the relatively heavy stiffener rings were encountered and precluded assembly and testing of a bellows core. Fabrication problems are summarized and recommended fabrication methods for future effort are presented.

  16. High power X-ray welding of metal-matrix composites

    SciTech Connect

    Rosenberg, Richard A.; Goeppner, George A.; Noonan, John R.; Farrell, William J.; Ma, Qing

    1997-12-01

    A method for joining metal-matrix composites (MMCs) by using high power x-rays as a volumetric heat source is provided. The method involves directing an x-ray to the weld line between two adjacent MMCs materials to create an irradiated region or melt zone. The x-rays have a power density greater than about 10{sup 4} watts/cm{sup 2} and provide the volumetric heat required to join the MMC materials. Importantly, the reinforcing material of the metal-matrix composites remains uniformly distributed in the melt zone, and the strength of the MMCs are not diminished. In an alternate embodiment, high power x-rays are used to provide the volumetric heat required to weld metal elements, including metal elements comprised of metal alloys. In an alternate embodiment, high power x-rays are used to provide the volumetric heat required to weld metal elements, including metal elements comprised of metal alloys.

  17. High power x-ray welding of metal-matrix composites

    DOEpatents

    Rosenberg, Richard A.; Goeppner, George A.; Noonan, John R.; Farrell, William J.; Ma, Qing

    1999-01-01

    A method for joining metal-matrix composites (MMCs) by using high power x-rays as a volumetric heat source is provided. The method involves directing an x-ray to the weld line between two adjacent MMCs materials to create an irradiated region or melt zone. The x-rays have a power density greater than about 10.sup.4 watts/cm.sup.2 and provide the volumetric heat required to join the MMC materials. Importantly, the reinforcing material of the metal-matrix composites remains uniformly distributed in the melt zone, and the strength of the MMCs are not diminished. In an alternate embodiment, high power x-rays are used to provide the volumetric heat required to weld metal elements, including metal elements comprised of metal alloys. In an alternate embodiment, high power x-rays are used to provide the volumetric heat required to weld metal elements, including metal elements comprised of metal alloys.

  18. Novel concepts in weld metal science: Role of gradients and composite structure

    SciTech Connect

    Matlock, D.K.; Olson, D.L.

    1991-12-01

    The effects of compositional and microstructural gradients on weld metal properties are being investigated. Crack propagation is solidified alloy structures is being characterized as to solidification orientation and the profile of the compositional variations. The effects of compositional gradients, are considered based on a thermodynamic analysis, referred to as the Cahn-Hillard analysis, which describes the degree to which a local surface energy is modified by the presence of a compositional gradient. The analysis predicts that both ductile and brittle fracture mechanisms are enhanced by the presence of a composition gradient. Special techniques to produce laboratory samples with microstructures which simulate the composition and microstructure gradients in solidified weld metal are used, along with appropriate mathematical models, to evaluate the properties of the composite weld metals. The composite modeling techniques are being applied to describe the effects of compositional and microstructural gradients on weld metal properties in Ni-Cu alloys. The development of metal matrix composition weld deposits on austenitic stainless steels has been studied. The particulate metal matrix composites were produced with ceramic or refractory metal powder filled cored wire, which was gas tungsten arc and gas metal arc welded.

  19. An Assessment of Molten Metal Detachment Hazards During Electron Beam Welding in Space

    NASA Technical Reports Server (NTRS)

    Fragomeni, James M.; Nunes, Arthur C., Jr.

    1998-01-01

    The safety issue has been raised with regards to potential molten metal detachments from the weld pool and cold filler wire during electron beam welding in space. This investigation was undertaken to evaluate if molten metal could detach and come in contact with astronauts and burn through the fabric of the astronauts' Extravehicular Mobility Unit (EMU) during electron beam welding in space. Molten metal detachments from either the weld/cut substrate or weld wire could present harm to a astronaut if the detachment was to burn through the fabric of the EMU. Theoretical models were developed to predict the possibility and size of the molten metal detachment hazards during the electron beam welding exercises at Low Earth Orbit (LEO). The primary molten metal detachment concerns were those cases of molten metal separation from the metal surface due to metal cutting, weld pool splashing, entrainment and release of molten metal due to filler wire snap-out from the weld puddle, and molten metal accumulation and release from the end of the weld wire. Some possible ways of obtaining molten metal drop detachments would include an impulse force, or bump, to the weld sample, cut surface, or filler wire. Theoretical models were developed for these detachment concerns from principles of impact and kinetic energies, surface tension, drop geometry, surface energies, and particle dynamics. The surface tension represents the force opposing the liquid metal drop from detaching whereas the weight of the liquid metal droplet represents a force that is tending to detach the molten metal drop. Theoretical calculations have indicated that only a small amount of energy is required to detach a liquid metal drop; however, much of the energy of an impact is absorbed in the sample or weld plate before it reaches the metal drop on the cut edge or surface. The tendency for detachment is directly proportional to the weld pool radius and metal density and inversely proportional to the surface

  20. 3D display and image processing system for metal bellows welding

    NASA Astrophysics Data System (ADS)

    Park, Min-Chul; Son, Jung-Young

    2010-04-01

    Industrial welded metal Bellows is in shape of flexible pipeline. The most common form of bellows is as pairs of washer-shaped discs of thin sheet metal stamped from strip stock. Performing arc welding operation may cause dangerous accidents and bad smells. Furthermore, in the process of welding operation, workers have to observe the object directly through microscope adjusting the vertical and horizontal positions of welding rod tip and the bellows fixed on the jig, respectively. Welding looking through microscope makes workers feel tired. To improve working environment that workers sit in an uncomfortable position and productivity we introduced 3D display and image processing. Main purpose of the system is not only to maximize the efficiency of industrial productivity with accuracy but also to keep the safety standards with the full automation of work by distant remote controlling.

  1. Real-time sensing and monitoring in robotic gas metal arc welding

    NASA Astrophysics Data System (ADS)

    Wu, C. S.; Gao, J. Q.; Hu, J. K.

    2007-01-01

    A real-time monitoring system is developed for detecting abnormal conditions in robotic gas metal arc welding. The butt-joint test pieces with simulated large gaps are used to intentionally introduce step disturbance of welding conditions. During the welding process, the welding voltage and current signals are sampled and processed on-line to extract the characteristic information reflecting the process quality. After the first statistical processing, it is found that seven statistical parameters (the mean, standard deviation, coefficient of variance and kurtosis of welding voltage; the mean, coefficient of variance and kurtosis of welding current) show variations during the step disturbance. Through the second statistical processing of the means of the welding voltage for subgroups of continuous measurement, the statistical control chart is obtained, and an SPC (statistical process control)-based on-line identifying method is developed. Ten robotic welding experiments are conducted to verify the real-time monitoring system. It is found that the correct identification rates for normal and abnormal welding conditions are 100% and 95%, respectively.

  2. Picosecond laser welding of optical to metal components

    NASA Astrophysics Data System (ADS)

    Carter, Richard M.; Troughton, Michael; Chen, Jinanyong; Elder, Ian; Thomson, Robert R.; Lamb, Robert A.; Esser, M. J. Daniel; Hand, Duncan P.

    2016-03-01

    We report on practical, industrially relevant, welding of optical components to themselves and aluminum alloy components. Weld formation is achieved through the tight focusing of a 5.9ps, 400kHz Trumpf laser operating at 1030nm. By selecting suitable surface preparation, clamping and laser parameters, the plasma can be confined, even with comparatively rough surfaces, by exploiting the melt properties of the glass. The short interaction time allows for a permanent weld to form between the two materials with heating limited to a region ~300 µm across. Practical application of these weld structures is typically limited due to the induced stress within the glass and, critically, the issues surrounding post-weld thermal expansion. We report on the measured strength of the weld, with a particular emphasis on laser parameters and surface preparation.

  3. A new technique for the strengthening of aluminum tungsten inert gas weld metals: using carbon nanotube/aluminum composite as a filler metal.

    PubMed

    Fattahi, M; Nabhani, N; Rashidkhani, E; Fattahi, Y; Akhavan, S; Arabian, N

    2013-01-01

    The effect of multi-walled carbon nanotube (MWCNT) on the mechanical properties of aluminum multipass weld metal prepared by the tungsten inert gas (TIG) welding process was investigated. High energy ball milling was used to disperse MWCNT in the aluminum powder. Carbon nanotube/aluminum composite filler metal was fabricated for the first time by hot extrusion of ball-milled powders. After welding, the tensile strength, microhardness and MWCNT distribution in the weld metal were investigated. The test results showed that the tensile strength and microhardness of weld metal was greatly increased when using the filler metal containing 1.5 wt.% MWCNT. Therefore, according to the results presented in this paper, it can be concluded that the filler metal containing MWCNT can serve as a super filler metal to improve the mechanical properties of TIG welds of Al and its alloys.

  4. The ways of reliability enhancement of welded metal structures for critical applications in the conditions of low climatic temperatures

    NASA Astrophysics Data System (ADS)

    Saraev, Yu. N.; Bezborodov, V. P.; Gladkovsky, S. V.; Golikov, N. I.

    2016-11-01

    The paper studies how the energy parameters of an effective welding technology based on adaptive pulse-arc welding method influence the microstructure, mechanical characteristics and fatigue strength of low carbon steel 09G2S welded joint. It is established that the application of the adaptive pulse-arc welding method with modulated current (CMW) as compared to the welding method with direct current (DCW) allows one to obtain a welded joint of this steel with high reserve impact strength, dynamic fracture toughness and fatigue strength of metallic structures at operation temperatures up to -60°C.

  5. Characterization of tool wear and weld optimization in the friction-stir welding of cast aluminum 359+20% SiC metal-matrix composite

    SciTech Connect

    Fernandez, G.J.; Murr, L.E

    2004-03-15

    Tool wear for threaded steel pin tools declines with decreasing rotation speed and increasing traverse or weld speeds for the friction-stir welding (FSW) of Al 359+20% SiC metal-matrix composite (MMC). Less than 10% tool wear occurs when the threaded tool erodes to a self-optimized shape resembling a pseudo-hour glass at weld traverse distances in excess of 3 m. There is only a 7% reduction in the SiC mean particle size in the weld zone for self-optimized pin tools with no threads as compared with a 25% variation for threaded tools wearing significantly at the start of welding. The weld zone becomes more homogeneous for efficient welding with self-optimized tools, and there is a reduction in the weld zone grain size due to dynamic recrystallization, which facilitates the solid-state flow. Transmission electron microscopy shows little difference in the dislocation density from the base material to the weld zone, but there is a propensity of dislocation loops in the weld zone. The weld zone is observed to harden by as much as 30%, in contrast to the base material, as a consequence of the recrystallized grain size reduction and the SiC particles distributed therein.

  6. Possibility of Underwater Explosive Welding for Making Large-Sized Thin Metal Plate Clad by Overlapping Plates

    NASA Astrophysics Data System (ADS)

    Hokamoto, Kazuyuki; Mori, Akihisa; Fujita, Masahiro

    The authors have developed a new method of explosive welding using underwater shock wave for the welding of thin plate on a substrate. Considering the size limitation of the welding area in using the technique, the possibility of overlapping thin plates to make large-sized welding area is investigated. In general, the results for the welding of Inconel 600 on 304 stainless steel show a macroscopically successful weld, but the microstructure shows some melting spots caused due to the trapping of metal jet during the welding process when the welding condition is changed. The welding process is discussed based on the experimental results in comparison with some numerically simulated results obtained by AUTODYN-2D code.

  7. Manipulating the Interfacial Electrical and Optical Properties of Dissimilar Materials with Metallic Nanostructures

    DTIC Science & Technology

    2016-07-30

    optical, structural , and chemically-sensitive techniques. We also examined the optical quality of III-V layers grown above ErAs nanostructures, which... structures . These findings led us to invent a technique to grow GaAs that is free of planar 15. SUBJECT TERMS Molecular Beam Epitaxy, Nanostructures...heterogeneous semiconductor device structure . Metal/semiconductor interfaces are, perhaps, the most fundamental building block of solid-state devices

  8. Inspection of Nickel Alloy Welds: Results from Five-Year International Program

    NASA Astrophysics Data System (ADS)

    Prokofiev, Iouri; Cumblidge, Stephen E.; Doctor, Steven R.

    2011-06-01

    The U.S. Nuclear Regulatory Commission established and coordinated the international Program for the Inspection of Nickel alloy Components (PINC). The goal of PINC was to evaluate the capabilities of various nondestructive examination (NDE) techniques to detect and characterize primary water stress corrosion cracking (PWSCC) in dissimilar metal welds. Round-robin results showed that a combination of conventional and phased-array ultrasound provide the highest performance for flaw detection and depth sizing in dissimilar metal piping welds. The effective detection of flaws in bottom-mounted instrumentation penetrations by eddy current and ultrasound shows that it may be possible to reliably inspect these components in the field.

  9. Inspection of Nickel Alloy Welds: Results from Five Year International Program

    SciTech Connect

    Prokofiev, Iouri; Cumblidge, Stephen E.; Doctor, Steven R.

    2011-06-23

    The U.S. Nuclear Regulatory Commission established and coordinated the international Program for the Inspection of Nickel alloy Components (PINC). The goal of PINC was to evaluate the capabilities of various nondestructive examination (NDE) techniques to detect and characterize primary water stress corrosion cracking (PWSCC) in dissimilar metal welds. Round-robin results showed that a combination of conventional and phased-array ultrasound provide the highest performance for flaw detection and depth sizing in dissimilar metal piping welds. The effective detection of flaws in bottom-mounted instrumentation penetrations by eddy current and ultrasound shows that it may be possible to reliably inspect these components in the field.

  10. 30 CFR 57.15007 - Protective equipment or clothing for welding, cutting, or working with molten metal.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., cutting, or working with molten metal. 57.15007 Section 57.15007 Mineral Resources MINE SAFETY AND HEALTH... equipment or clothing for welding, cutting, or working with molten metal. Protective clothing or equipment and face shields or goggles shall be worn when welding, cutting, or working with molten metal....

  11. Development of an intelligent system for cooling rate and fill control in GMAW. [Gas Metal Arc Welding (GMAW)

    SciTech Connect

    Einerson, C.J.; Smartt, H.B.; Johnson, J.A.; Taylor, P.L. ); Moore, K.L. )

    1992-01-01

    A control strategy for gas metal arc welding (GMAW) is developed in which the welding system detects certain existing conditions and adjusts the process in accordance to pre-specified rules. This strategy is used to control the reinforcement and weld bead centerline cooling rate during welding. Relationships between heat and mass transfer rates to the base metal and the required electrode speed and welding speed for specific open circuit voltages are taught to a artificial neural network. Control rules are programmed into a fuzzy logic system. TRADITOINAL CONTROL OF THE GMAW PROCESS is based on the use of explicit welding procedures detailing allowable parameter ranges on a pass by pass basis for a given weld. The present work is an exploration of a completely different approach to welding control. In this work the objectives are to produce welds having desired weld bead reinforcements while maintaining the weld bead centerline cooling rate at preselected values. The need for this specific control is related to fabrication requirements for specific types of pressure vessels. The control strategy involves measuring weld joint transverse cross-sectional area ahead of the welding torch and the weld bead centerline cooling rate behind the weld pool, both by means of video (2), calculating the required process parameters necessary to obtain the needed heat and mass transfer rates (in appropriate dimensions) by means of an artificial neural network, and controlling the heat transfer rate by means of a fuzzy logic controller (3). The result is a welding machine that senses the welding conditions and responds to those conditions on the basis of logical rules, as opposed to producing a weld based on a specific procedure.

  12. A Comparison of Weld-Repaired and Base Metal for Inconel 718 and CRES 321 at Cryogenic and Room Temperatures

    NASA Technical Reports Server (NTRS)

    Newman, John A.; Smith, Stephen W.; Willard, Scott A.; Piascik, Robert S.

    2004-01-01

    Fatigue crack growth tests were conducted to characterize the performance of Inconel 718 and CRES 321 welds, weld heat-affect-zone and parent metal at room temperature laboratory air and liquid nitrogen (-196oC) environments. The results of this study were required to predict the damage tolerance behavior of proposed orbiter main engine hydrogen fuel liner weld repairs. Experimental results show that the room and cryogenic temperature fatigue crack growth characteristics of both alloys are not significantly degraded by the weld repair process. However, both Inconel 718 and CRES 321 exhibited lower apparent toughness within the weld repair region compared to the parent metal.

  13. Nuclear Technology. Course 28: Welding Inspection. Module 28-3, Tungsten Inert Gas (TIG), Metal Inert Gas (MIG) and Submerged Arc Welding.

    ERIC Educational Resources Information Center

    Espy, John

    This third in a series of ten modules for a course titled Welding Inspection presents the apparatus, process techniques, procedures, applications, associated defects, and inspection for the tungsten inert gas, metal inert gas, and submerged arc welding processes. The module follows a typical format that includes the following sections: (1)…

  14. Hazard of ultraviolet radiation emitted in gas metal arc welding of mild steel

    PubMed Central

    Nakashima, Hitoshi; Utsunomiya, Akihiro; Takahashi, Jyunya; Fujii, Nobuyuki; Okuno, Tsutomu

    2016-01-01

    Objectives: Ultraviolet radiation (UVR) emitted during arc welding frequently causes keratoconjunctivitis and erythema in the workplace. The degree of hazard from UVR exposure depends on the welding method and conditions. Therefore, it is important to identify the UVR levels present under various conditions. Methods: We experimentally evaluated the UVR levels emitted in gas metal arc welding (GMAW) of mild steel. We used both a pulsed welding current and a non-pulsed welding current. The shielding gases were 80% Ar + 20% CO2 and 100% CO2. The effective irradiance defined in the American Conference of Governmental Industrial Hygienists guidelines was used to quantify the UVR hazard. Results: The effective irradiance measured in this study was in the range of 0.51-12.9 mW/cm2 at a distance of 500 mm from the arc. The maximum allowable exposure times at these levels are only 0.23-5.9 s/day. Conclusions: The following conclusions were made regarding the degree of hazard from UVR exposure during the GMAW of mild steel: (1) It is more hazardous at higher welding currents than at lower welding currents. (2) At higher welding currents, it is more hazardous when 80% Ar + 20% CO2 is used as a shielding gas than when 100% CO2 is used. (3) It is more hazardous for pulsed welding currents than for non-pulsed welding currents. (4) It appears to be very hazardous when metal transfer is the spray type. This study demonstrates that unprotected exposure to UVR emitted by the GMAW of mild steel is quite hazardous. PMID:27488036

  15. Chemical composition effect on VVER-1000 RPV weld metal thermal aging

    NASA Astrophysics Data System (ADS)

    Gurovich, B. A.; Chernobaeva, A. A.; Erak, D. Yu; Kuleshova, E. A.; Zhurko, D. A.; Papina, V. B.; Skundin, M. A.; Maltsev, D. A.

    2015-10-01

    Temperature and fast neutron flux simultaneously affect the material of welded joints of reactor pressure vessels under irradiation. Understanding thermal aging effects on the weld metal allows for an explanation of the mechanisms that govern an increase in the ductile-to-brittle transition temperature of the reactor pressure vessel materials under long term irradiation at operation temperature. This paper reports on new results and reassessment of the VVER-1000 weld metal surveillance specimen database performed at the National Research Center "Kurchatov Institute". The current database of VVER-1000 weld metal thermal aging at 310-320 °C includes 50 transition temperature values with the maximum holding time of 208,896 h. The updated database completed with the information on intergranular fracture shear and phosphorous content in the grain boundaries has allowed us to propose a new mechanism of VVER-1000 weld materials thermal aging at 310-320 °C and develop models of ductile-to-brittle transition temperature shift for VVER-1000 weld metal during a long-term exposure at 310-320 °C.

  16. Fatigue crack growth properties of the base metal and weld metal of a 9% Ni steel for LNG storage tank

    NASA Astrophysics Data System (ADS)

    Kim, Young-Kyun; Shim, Kyu-Taek; Kim, Jae-Hoon

    2009-07-01

    Newly developed heavy thick plates of 9% Ni steel for large capacity of LNG tank were fabricated to conduct a fatigue crack growth test. The weld metal specimens were also fabricated by taking the same weld procedures which are applied to actual LNG storage tank inner shell. The effect of changes in load ratio, R, and test temperature on the fatigue crack growth rate has been investigated. Separate fatigue crack growth experiments were performed at load ratio of 0.1 and 0.5 at -162°C and compared to the behavior at room temperature. The fatigue crack growth rates of weld metal were nearly the same as those of the base metal irrespective of load ratio change at room temperature. A decrease in temperature decreased the fatigue crack growth rates of base metal but in the case of weld metal only small scatters appeared in the fatigue crack growth rate compared with those of base metals. The fatigue crack growth rates were dominated by residual stress due to welding processes rather than temperature effects.

  17. Pressure Resistance Welding of High Temperature Metallic Materials

    SciTech Connect

    Larry Zirker; Craig Tyler

    2010-08-01

    Engineers from the Idaho National Laboratory (INL) have demonstrated an innovative method for seal or pinch welding stainless steel tubing. Sometimes a tube has fuel or contamination that must be contained, or the tube needs to be shortened or cut for handling, and the tube needs to have a guaranteed sealed weld that is both quick and easy. This technique was demonstrated in a laboratory using a resistance welding system with specially designed electrodes to ensure a tube end is seal welded or if a long tube is to be shortened, the severed ends are seal welded. The unique electrodes design is integral to achieving the sealed ends. This process could readily be adapted for robotic--remote handling or for contact handling in a glovebox or hood.

  18. Achieving High Strength Joint of Pure Copper Via Laser-Cold Metal Transfer Arc Hybrid Welding

    NASA Astrophysics Data System (ADS)

    Chen, Yulong; Chen, Cong; Gao, Ming; Zeng, Xiaoyan

    2016-06-01

    Fiber laser-cold metal transfer arc hybrid welding of pure copper was studied. Weld porosity was tested by X-ray nondestructive testing. Microstructure and fracture features were observed by scanning electron microscopy. Mechanical properties were evaluated by cross weld tensile test. Full penetrated and continuous welds were obtained by hybrid welding once the laser power reached 2 kW, while they could not be obtained by laser welding alone, even though the laser power reached 5 kW. The ultimate tensile strength (UTS), the yield strength (YS), and the elongation of the best hybrid weld material were up to 227, 201 MPa, and 21.5 pct, respectively. The joint efficiencies in UTS and YS of hybrid weld were up to 84 and 80 pct of the BM, respectively. The fracture location changes from the fusion zone to the heat-affected zone with the increase of laser power. Besides, the mechanisms of process stability and porosity suppression were clarified by laser-arc interaction and pool behavior. The strengthening mechanism was discussed by microstructure characteristics.

  19. Rapid Detection of Transition Metals in Welding Fumes Using Paper-Based Analytical Devices

    PubMed Central

    Volckens, John

    2014-01-01

    Metals in particulate matter (PM) are considered a driving factor for many pathologies. Despite the hazards associated with particulate metals, personal exposures for at-risk workers are rarely assessed due to the cost and effort associated with monitoring. As a result, routine exposure assessments are performed for only a small fraction of the exposed workforce. The objective of this research was to evaluate a relatively new technology, microfluidic paper-based analytical devices (µPADs), for measuring the metals content in welding fumes. Fumes from three common welding techniques (shielded metal arc, metal inert gas, and tungsten inert gas welding) were sampled in two welding shops. Concentrations of acid-extractable Fe, Cu, Ni, and Cr were measured and independently verified using inductively coupled plasma-optical emission spectroscopy (ICP-OES). Results from the µPAD sensors agreed well with ICP-OES analysis; the two methods gave statistically similar results in >80% of the samples analyzed. Analytical costs for the µPAD technique were ~50 times lower than market-rate costs with ICP-OES. Further, the µPAD method was capable of providing same-day results (as opposed several weeks for ICP laboratory analysis). Results of this work suggest that µPAD sensors are a viable, yet inexpensive alternative to traditional analytic methods for transition metals in welding fume PM. These sensors have potential to enable substantially higher levels of hazard surveillance for a given resource cost, especially in resource-limited environments. PMID:24515892

  20. Rapid detection of transition metals in welding fumes using paper-based analytical devices.

    PubMed

    Cate, David M; Nanthasurasak, Pavisara; Riwkulkajorn, Pornpak; L'Orange, Christian; Henry, Charles S; Volckens, John

    2014-05-01

    Metals in particulate matter (PM) are considered a driving factor for many pathologies. Despite the hazards associated with particulate metals, personal exposures for at-risk workers are rarely assessed due to the cost and effort associated with monitoring. As a result, routine exposure assessments are performed for only a small fraction of the exposed workforce. The objective of this research was to evaluate a relatively new technology, microfluidic paper-based analytical devices (µPADs), for measuring the metals content in welding fumes. Fumes from three common welding techniques (shielded metal arc, metal inert gas, and tungsten inert gas welding) were sampled in two welding shops. Concentrations of acid-extractable Fe, Cu, Ni, and Cr were measured and independently verified using inductively coupled plasma-optical emission spectroscopy (ICP-OES). Results from the µPAD sensors agreed well with ICP-OES analysis; the two methods gave statistically similar results in >80% of the samples analyzed. Analytical costs for the µPAD technique were ~50 times lower than market-rate costs with ICP-OES. Further, the µPAD method was capable of providing same-day results (as opposed several weeks for ICP laboratory analysis). Results of this work suggest that µPAD sensors are a viable, yet inexpensive alternative to traditional analytic methods for transition metals in welding fume PM. These sensors have potential to enable substantially higher levels of hazard surveillance for a given resource cost, especially in resource-limited environments.

  1. Study on impact toughness of C-Mn multilayer weld metal at [minus]60 degrees

    SciTech Connect

    Chen, J.H.; Xia, T.D.; Yan, C. )

    1993-01-01

    A comparative study has been carried out on the toughness of specimens of the C-Mn multilayer weld steel and that of the specimens simulated with the various reheating cycles by using the weld thermal-restraint stress and strain cycle simulator. It proved that the region initiating the cleavage crack, i.e., the weakest fractured at [minus]60 C([minus]76 F), is just the region having the lowest toughness among various reheated zones. The toughness of weld metal depends upon the toughness value of this weakest region. Heat input and alloying elements, such as manganese, titanium and boron, affected the toughness of weld metal by changing the toughness of the weakest region in the multilayer weldment.

  2. Joining of dissimilar materials

    DOEpatents

    Tucker, Michael C; Lau, Grace Y; Jacobson, Craig P

    2012-10-16

    A method of joining dissimilar materials having different ductility, involves two principal steps: Decoration of the more ductile material's surface with particles of a less ductile material to produce a composite; and, sinter-bonding the composite produced to a joining member of a less ductile material. The joining method is suitable for joining dissimilar materials that are chemically inert towards each other (e.g., metal and ceramic), while resulting in a strong bond with a sharp interface between the two materials. The joining materials may differ greatly in form or particle size. The method is applicable to various types of materials including ceramic, metal, glass, glass-ceramic, polymer, cermet, semiconductor, etc., and the materials can be in various geometrical forms, such as powders, fibers, or bulk bodies (foil, wire, plate, etc.). Composites and devices with a decorated/sintered interface are also provided.

  3. Microstructural Evolution of Inconel 625 and Inconel 686CPT Weld Metal for Clad Carbon Steel Linepipe Joints: A Comparator Study

    NASA Astrophysics Data System (ADS)

    Maltin, Charles A.; Galloway, Alexander M.; Mweemba, Martin

    2014-07-01

    Microstructural evolution of Inconel 625 and Inconel 686CPT filler metals, used for the fusion welding of clad carbon steel linepipe, has been investigated and compared. The effects of iron dilution from the linepipe parent material on the elemental segregation potential of the filler metal chemistry have been considered. The results obtained provide significant evidence to support the view that, in Inconel 686CPT weld metal, the segregation of tungsten is a function of the level of iron dilution from the parent material. The data presented indicate that the incoherent phase precipitated in the Inconel 686CPT weld metal has a morphology that is dependent on tungsten enrichment and, therefore, iron dilution. Furthermore, in the same weld metal, a continuous network of finer precipitates was observed. The Charpy impact toughness of each filler metal was evaluated, and the results highlighted the superior impact toughness of the Inconel 625 weld metal over that of Inconel 686CPT.

  4. Study of the possibility of using solar radiant energy for welding and brazing metals

    NASA Technical Reports Server (NTRS)

    Dvernyakov, V. S.; Frantsevich, I. N.; Pasichnyy, V. V.; Shiganov, N. A.; Korunov, Y. I.; Kasich-Pilipenko, I. Y.

    1974-01-01

    The solar spectrum at the surface of the earth is analyzed. A facility for creating concentrated solar radiant energy flux is described, and data on its energetic capabilities are presented. The technology of solar welding by the fusion technique and joining by high-temperature brazing is examined. The use of concentrated solar radiant energy for welding and brazing metals and alloys is shown. The results of mechanical tests and microscopic and macroscopic studies are presented.

  5. Laser welding of selected aerospace alloys

    NASA Astrophysics Data System (ADS)

    Ebadan, Gracie E.

    The study was aimed at developing an understanding of the microstructural effects of the laser welding process on the alloys, and assessing the structural integrity of the resultant welds. The effect of laser processing parameters such as laser power, laser beam traverse speed, lens focal length, and the manipulation of these parameters on the welding efficiency and weld area integrity was also investigated. Other tasks within the project included a study on the possibility of using an anodic film to enhance the laser weld ability of Al 6061. Finally, attempts were made to identify phases observed in the weld area of the composite materials. Nimonics C263 and PE11 exhibited laser welds free of cracks and porosity. The difference in composition between the two alloys did not result in any significant dissimilarities in their response to the laser welding process. The welds in both alloys exhibited a fine columnar dendritic microstructure, and while carbides were observed in the interdendritic regions of the welds, electron optical analysis did not reveal any gamma' precipitates in this region. It was concluded that for the welding of thin gage materials above a threshold laser power the resultant welding efficiency shows a greater dependence on laser beam mode, and laser spot size, than on laser power, and beam traverse speed. Aluminum 6061 was not easily welded with a laser in its as received form, and the welds showed some degree of porosity. Anodizing was found to improve the welding efficiency in this material. While the presence of an anodic film on the metal surface increased the welding efficiency of the alloy, no relationship was found between the thickness of the anodic film and welding efficiency in the range of film thicknesses investigated. Weld regions were observed to be cellular dendritic in structure, with narrow heat affected zones. No precipitates or low melting point phases could be identified in the weld region. Melt zones were successfully

  6. Latent Cracking of Tantalum-Titanium Welds Due to Hydrogen Embrittlement

    NASA Astrophysics Data System (ADS)

    Hossick-Schott, Joachim; Reiterer, Markus; Heffelfinger, Jason; Hintz, Mike; Ringle, Mike; Levina, Iryna; Gaffney, Kevin

    2013-05-01

    Establishing electrical interconnects in implantable electronic medical devices frequently requires joining of dissimilar materials. A weld between a tantalum wire and titanium sheet metal on a contact module is presented as an example for dissimilar joining. Latent, brittle cracking was observed in the proximity of the weld upon pull testing. The weld cracking occurs by the mechanism known as hydrogen stress cracking (HSC) and is due to titanium hydride formation. Diffusion facilitated hydrogen transport into the weld area. Diffusing hydrogen accumulates preferably in regions of high stress, causing latent titanium hydride formation and embrittlement of the weld. A broad array of analytical tools such as scanning electron microscopy (SEM), transmission electron microscopy, electron backscattered diffraction, dynamic secondary ion mass spectroscopy, and nanoindentation were utilized to identify the root cause for HSC.

  7. An Assessment of Molten Metal Detachment Hazards During Electron Beam Welding in the Space Shuttle Bay at LEO for the International Space Welding Experiment

    NASA Technical Reports Server (NTRS)

    Fragomeni, James M.

    1996-01-01

    In 1997, the United States [NASA] and the Paton Electric Welding Institute are scheduled to cooperate in a flight demonstration on the U.S. Space Shuttle to demonstrate the feasibility of welding in space for a possible repair option for the International Space Station Alpha. This endeavor, known as the International Space Welding Experiment (ISWE), will involve astronauts performing various welding exercises such as brazing, cutting, welding, and coating using an electron beam space welding system that was developed by the E.O. Paton Electric Welding Institute (PWI), Kiev Ukraine. This electron beam welding system known as the "Universal Weld System" consists of hand tools capable of brazing, cutting, autogeneous welding, and coating using an 8 kV (8000 volts) electron beam. The electron beam hand tools have also been developed by the Paton Welding Institute with greater capabilities than the original hand tool, including filler wire feeding, to be used with the Universal Weld System on the U.S. Space Shuttle Bay as part of ISWE. The hand tool(s) known as the Ukrainian Universal Hand [Electron Beam Welding] Tool (UHT) will be utilized for the ISWE Space Shuttle flight welding exercises to perform welding on various metal alloy samples. A total of 61 metal alloy samples, which include 304 stainless steel, Ti-6AI-4V, 2219 aluminum, and 5456 aluminum alloys, have been provided by NASA for the ISWE electron beam welding exercises using the UHT. These samples were chosen to replicate both the U.S. and Russian module materials. The ISWE requires extravehicular activity (EVA) of two astronauts to perform the space shuttle electron beam welding operations of the 61 alloy samples. This study was undertaken to determine if a hazard could exist with ISWE during the electron beam welding exercises in the Space Shuttle Bay using the Ukrainian Universal Weld System with the UHT. The safety issue has been raised with regard to molten metal detachments as a result of several

  8. Metal Cutting Theory and Friction Stir Welding Tool Design

    NASA Technical Reports Server (NTRS)

    Payton, Lewis N.

    2003-01-01

    Friction Stir Welding (FSW) is a relatively new industrial process that was invented at The Weld Institute (TWI, United Kingdom) and patented in 1992 under research funded by in part by the National Aeronautics and Space Administration (NASA). Often quoted advantages of the process include good strength and ductility along with minimization of residual stress and distortion. Less well advertised are the beneficial effects of this solid state welding process in the field of occupational and environmental safety. It produces superior weld products in difficult to weld materials without producing any toxic fumes or solid waste that must be controlled as hazardous waste. In fact, it reduces noise pollution in the workspace as well. In the early days of FSW, most welding was performed on modified machine tools, in particular on milling machines with modified milling cutters. In spite of the obvious milling heritage of the process, the techniques and lessons learned from almost 250 years of successful metalworking with milling machines have not been applied in the field of modern Friction Stir Welding. The goal of the current research was to study currently successful FSW tools and parameterize the process in such a way that the design of new tools for new materials could be accelerated. Along the way, several successful new tooling designs were developed for current issues at the Marshall Space Flight Center with accompanying patent disclosures

  9. Computed Tomography 3-D Imaging of the Metal Deformation Flow Path in Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Schneider, Judy; Beshears, Ronald; Nunes, Arthur C., Jr.

    2005-01-01

    In friction stir welding (FSW), a rotating threaded pin tool is inserted into a weld seam and literally stirs the edges of the seam together. To determine optimal processing parameters for producing a defect free weld, a better understanding of the resulting metal deformation flow path is required. Marker studies are the principal method of studying the metal deformation flow path around the FSW pin tool. In our study, we have used computed tomography (CT) scans to reveal the flow pattern of a lead wire embedded in a FSW weld seam. At the welding temperature of aluminum, the lead becomes molten and is carried with the macro-flow of the weld metal. By using CT images, a 3-dimensional (3D) image of the lead flow pattern can be reconstructed. CT imaging was found to be a convenient and comprehensive way of collecting and displaying tracer data. It marks an advance over previous more tedious and ambiguous radiographic/metallographic data collection methods.

  10. Evolution of weld metal microstructure in shielded metal arc welding of X70 HSLA steel with cellulosic electrodes: A case study

    SciTech Connect

    Ghomashchi, Reza Costin, Walter; Kurji, Rahim

    2015-09-15

    The microstructure of weld joint in X70 line pipe steel resulted from shielded metal arc welding with E6010 cellulosic electrodes is characterized using optical and electron microscopy. A range of ferritic morphologies have been identified ranging from polygonal inter- and intra-prior austenite grains allotriomorphic, idiomorphic ferrites to Widmanstätten, acicular and bainitic ferrites. Electron Backscatter Diffraction (EBSD) analysis using Image Quality (IQ) and Inverse Pole Figure (IPF) maps through superimposition of IQ and IPF maps and measurement of percentages of high and low angle grain boundaries was identified to assist in differentiation of acicular ferrite from Widmanstätten and bainitic ferrite morphologies. In addition two types of pearlitic structures were identified. There was no martensite detected in this weld structure. The morphology, size and chemistry of non-metallic inclusions are also discussed briefly. - Highlights: • Application of EBSD reveals orientation relationships in a range of phases for shielded metal arc welding of HSLA steel. • Nucleation sites of various ferrite morphologies identified • Formation of upper and lower bainite and their morphologies.

  11. Welding.

    ERIC Educational Resources Information Center

    Cowan, Earl; And Others

    The curriculum guide for welding instruction contains 16 units presented in six sections. Each unit is divided into the following areas, each of which is color coded: terminal objectives, specific objectives, suggested activities, and instructional materials; information sheet; transparency masters; assignment sheet; test; and test answers. The…

  12. Welding.

    ERIC Educational Resources Information Center

    Baldwin, Harold; Whitney, Gregory

    This curriculum guide is intended to assist vocational instructors in preparing students for entry-level employment as welders and preparing them for advanced training in the workplace. The package contains an overview of new and emerging welding technologies, a competency/skill and task list, an instructor's guide, and an annotated bibliography.…

  13. Room-Temperature Chemical Welding and Sintering of Metallic Nanostructures by Capillary Condensation.

    PubMed

    Yoon, Sung-Soo; Khang, Dahl-Young

    2016-06-08

    Room-temperature welding and sintering of metal nanostructures, nanoparticles and nanowires, by capillary condensation of chemical vapors have successfully been demonstrated. Nanoscale gaps or capillaries that are abundant in layers of metal nanostructures have been found to be the preferred sites for the condensation of chemically oxidizing vapor, H2O2 in this work. The partial dissolution and resolidification at such nanogaps completes the welding/sintering of metal nanostructures within ∼10 min at room-temperature, while other parts of nanostructures remain almost intact due to negligible amount of condensation on there. The welded networks of Ag nanowires have shown much improved performances, such as high electrical conductivity, mechanical flexibility, optical transparency, and chemical stability. Chemically sintered layers of metal nanoparticles, such as Ag, Cu, Fe, Ni, and Co, have also shown orders of magnitude increase in electrical conductivity and improved environmental stability, compared to nontreated ones. Pertinent mechanisms involved in the chemical welding/sintering process have been discussed. Room-temperature welding and sintering of metal nanostructures demonstrated here may find widespread application in diverse fields, such as displays, deformable electronics, wearable heaters, and so forth.

  14. Method for laser welding ultra-thin metal foils

    DOEpatents

    Pernicka, J.C.; Benson, D.K.; Tracy, C.E.

    1996-03-26

    A method for simultaneously cutting and welding ultra-thin foils having a thickness of less than 0.002 inches wherein two ultra-thin films are stacked and clamped together. A pulsed laser such as of the Neodymium: YAG type is provided and the beam of the laser is directed onto the stacked films to cut a channel through the films. The laser is moved relative to the stacked foils to cut the stacked foils at successive locations and to form a plurality of connected weld beads to form a continuous weld. 5 figs.

  15. Method for laser welding ultra-thin metal foils

    DOEpatents

    Pernicka, John C.; Benson, David K.; Tracy, C. Edwin

    1996-01-01

    A method for simultaneously cutting and welding ultra-thin foils having a thickness of less than 0.002 inches wherein two ultra-thin films are stacked and clamped together. A pulsed laser such as of the Neodymium: YAG type is provided and the beam of the laser is directed onto the stacked films to cut a channel through the films. The laser is moved relative to the stacked foils to cut the stacked foils at successive locations and to form a plurality of connected weld beads to form a continuous weld.

  16. Influencing the arc and the mechanical properties of the weld metal in GMA-welding processes by additive elements on the wire electrode surface

    NASA Astrophysics Data System (ADS)

    Wesling, V.; Schram, A.; Müller, T.; Treutler, K.

    2016-03-01

    Under the premise of an increasing scarcity of raw materials and increasing demands on construction materials, the mechanical properties of steels and its joints are gaining highly important. In particular high- and highest-strength steels are getting in the focus of the research and the manufacturing industry. To the same extent, the requirements for filler metals are increasing as well. At present, these low-alloy materials are protected by a copper coating (<1μm) against corrosion. In addition, the coating realizes a good ohmic contact and good sliding properties between the welding machine and the wire during the welding process. By exchanging the copper with other elements it should be possible to change the mechanical properties of the weld metal and the arc stability during gas metal arc welding processes and keep the basic functions of the coating nearly untouched. On a laboratory scale solid wire electrodes with coatings of various elements and compounds such as titanium oxide were made and processed with a Gas Metal Arc Welding process. During the processing a different process behavior between the wire electrodes, coated and original, could be observed. The influences ranges from greater/shorter arc-length over increasing/decreasing droplets to larger/smaller arc foot point. Furthermore, the weld metal of the coated electrodes has significantly different mechanical and technological characteristics as the weld metal from the copper coated ground wire. The yield strength and tensile strength can be increased by up to 50%. In addition, the chemical composition of the weld metal was influenced by the application of coatings with layer thicknesses to 15 microns in the lower percentage range (up to about 3%). Another effect of the coating is a modified penetration. The normally occurring “argon finger” can be suppressed or enhanced by the choice of the coating. With the help of the presented studies it will be shown that Gas Metal Arc Welding processes

  17. Effects of the laser beam superficial heat treatment on the gas Tungsten arc Ti-6al-4v welded metal microstructure

    NASA Astrophysics Data System (ADS)

    Voiculescu, I.; Dontu, Octavian; Geanta, V.; Ganatsios, S.

    2008-03-01

    The microstructure of the weld and the extent to which it is different from the thermo-mechanically processed base material is strongly influenced by the thermal cycle of welding. The mechanical properties of composite weld structures in titanium alloys depend on structural characteristics of each region (weld, base material and heat affected area), influenced by the specific thermal cycle imposed during welding and the subsequent post-weld heat treatment. In order to improve the as-welded metal toughness and ductility, the welded metal was subjected to various post weld laser heat treatments, above and below beta transus temperature in a shielding atmosphere of pure argon. Standard micro-hardness measurements and tensile strength techniques showed higher mechanical properties of the heat treated samples in different conditions with respect to the base metal. Metallographic investigations attribute this to the formation of α'phases in heat treated material, especially in the weld metal.

  18. Inverse Thermal Analysis of Refractory Metal Laser Welds

    NASA Astrophysics Data System (ADS)

    Lambrakos, S. G.

    2013-09-01

    Case study inverse thermal analyses of Vanadium and Tantalum laser welds are presented. These analyses employ a methodology that is in terms of analytic basis functions for inverse thermal analysis of steady-state energy deposition in plate structures. The results of the case studies presented provide parametric representations of weld temperature histories that can be adopted as input data to various types of computational procedures, such as those for prediction of solid-state phase transformations. In addition, these temperature histories can be used to construct parametric-function representations for inverse thermal analysis of welds corresponding to other process parameters or welding processes process conditions of which fall within similar regimes. This study also discusses specific aspects the inverse-analysis methodology relevant to further development of algorithms for its application in practice.

  19. Picosecond laser bonding of highly dissimilar materials

    NASA Astrophysics Data System (ADS)

    Carter, Richard M.; Troughton, Michael; Chen, Jianyong; Elder, Ian; Thomson, Robert R.; Lamb, Robert A.; Esser, M. J. Daniel; Hand, Duncan P.

    2016-10-01

    We report on recent progress in developing an industrially relevant, robust technique to bond dissimilar materials through ultra-fast microwelding. This technique is based on the use of a 5.9ps, 400kHz Trumpf laser operating at 1030nm. Tight focusing of the laser radiation at, or around, the interface between two materials allows for simultaneous absorption in both. This absorption rapidly, and locally, heats the material forming plasma from both materials. With suitable surface preparation this plasma can be confined to the interface region where it mixes, cools and forms a weld between the two materials. The use of ps pulses results in a short interaction time. This enables a bond to form whilst limiting the heat affected zone (HAZ) to a region of only a few hundred micrometres across. This small scale allows for the bonding of materials with highly dissimilar thermal properties, and in particular coefficients of thermal expansion e.g. glass-metal bonding. We report on our results for a range of material combinations including, Al-Bk7, Al-SiO2 and Nd:YAG-AlSi. Emphasis will be laid on the technical requirements for bonding including the required surface preparation of the two materials and on the laser parameters required. The quality of the resultant bonds are characterized through shear force measurements (where strengths equal to and exceeding equivalent adhesives will be presented). The lifetime of the welds is also discussed, paying particular attention to the results of thermal cycling tests.

  20. Tensile and Fatigue Testing and Material Hardening Model Development for 508 LAS Base Metal and 316 SS Similar Metal Weld under In-air and PWR Primary Loop Water Conditions

    SciTech Connect

    Mohanty, Subhasish; Soppet, William; Majumdar, Saurin; Natesan, Ken

    2015-09-01

    This report provides an update on an assessment of environmentally assisted fatigue for light water reactor components under extended service conditions. This report is a deliverable in September 2015 under the work package for environmentally assisted fatigue under DOE’s Light Water Reactor Sustainability program. In an April 2015 report we presented a baseline mechanistic finite element model of a two-loop pressurized water reactor (PWR) for systemlevel heat transfer analysis and subsequent thermal-mechanical stress analysis and fatigue life estimation under reactor thermal-mechanical cycles. In the present report, we provide tensile and fatigue test data for 508 low-alloy steel (LAS) base metal, 508 LAS heat-affected zone metal in 508 LAS–316 stainless steel (SS) dissimilar metal welds, and 316 SS-316 SS similar metal welds. The test was conducted under different conditions such as in air at room temperature, in air at 300 oC, and under PWR primary loop water conditions. Data are provided on materials properties related to time-independent tensile tests and time-dependent cyclic tests, such as elastic modulus, elastic and offset strain yield limit stress, and linear and nonlinear kinematic hardening model parameters. The overall objective of this report is to provide guidance to estimate tensile/fatigue hardening parameters from test data. Also, the material models and parameters reported here can directly be used in commercially available finite element codes for fatigue and ratcheting evaluation of reactor components under in-air and PWR water conditions.

  1. Toenail metal concentration as a biomarker of occupational welding fume exposure

    PubMed Central

    Grashow, Rachel; Zhang, Jinming; Fang, Shona C.; Weisskopf, Marc G.; Christiani, David C.; Cavallari, Jennifer M.

    2014-01-01

    In populations exposed to heavy metals, there are few biomarkers that capture intermediate exposure windows. We sought to determine the correlation between toenail metal concentrations and prior 12 month work activity in welders with variable, metal-rich, welding fume exposures. Forty-eight participants, recruited through a local union, provided 69 sets of toenail clippings. Union-supplied and worker verified personal work histories were used to quantify hours welded and respirator use. Toenail samples were digested and analyzed for lead (Pb), manganese (Mn), cadmium (Cd), nickel (Ni) and arsenic (As) using ICP-MS. Spearman correlation coefficients were used to examine the correlation between toenail metal concentrations. Using mixed models to account for multiple participation times, we divided hours welded into three-month intervals and examined how weld hours correlated with log-transformed toenail Pb, Mn, Cd, Ni and As concentrations. Highest concentrations were found for Ni, followed by Mn, Pb and As, and Cd. All of the metals were significantly correlated with one another (rho range=0.28–0.51), with the exception of Ni and As (rho=0.20, p=0.17). Using mixed models adjusted for age, respirator use, smoking status and BMI, we found that Mn was associated with weld hours 7–9 months prior to clipping (p = 0.003), Pb was associated with weld hours 10–12 months prior to clipping (p=0.03) and over the entire year (p=0.04). Cd was associated with weld hours 10–12 months prior to clipping (p=0.05), and also with the previous year’s total hours welded (p=0.02). The association between Ni and weld hours 7–9 months prior to clipping approached significance (p=0.06). Toenail metal concentrations were not associated with the long-term exposure metric, years as a welder. Results suggest Mn, Pb, and Cd may have particular windows of relevant exposure that reflect work activity. In a population with variable exposure, toenails may serve as useful biomarkers for

  2. Microstructure evolution of Al/Mg butt joints welded by gas tungsten arc with Zn filler metal

    SciTech Connect

    Liu Fei; Zhang Zhaodong; Liu Liming

    2012-07-15

    Based on the idea of alloying welding seam, Gas tungsten arc welding method with pure Zn filler metal was chosen to join Mg alloy and Al alloy. The microstructures, phases, element distribution and fracture morphology of welding seams were examined. The results indicate that there was a transitional zone in the width of 80-100 {mu}m between the Mg alloy substrate and fusion zone. The fusion zone was mainly composed of MgZn{sub 2}, Zn-based solid solution and Al-based solid solution. The welding seam presented distinct morphology in different location owning to the quite high cooling rate of the molten pool. The addition of Zn metal could prevent the formation of Mg-Al intermetallics and form the alloyed welding seam during welding. Therefore, the tensile strengths of joints have been significantly improved compared with those of gas tungsten arc welded joints without Zn metal added. Highlights: Black-Right-Pointing-Pointer Mg alloy AZ31B and Al alloy 6061 are welded successfully. Black-Right-Pointing-Pointer Zinc wire is employed as a filler metal to form the alloyed welding seam. Black-Right-Pointing-Pointer An alloyed welding seam is benefit for improving of the joint tensile strength.

  3. Optimization and Prediction of Ultimate Tensile Strength in Metal Active Gas Welding

    PubMed Central

    Ampaiboon, Anusit; Lasunon, On-Uma; Bubphachot, Bopit

    2015-01-01

    We investigated the effect of welding parameters on ultimate tensile strength of structural steel, ST37-2, welded by Metal Active Gas welding. A fractional factorial design was used for determining the significance of six parameters: wire feed rate, welding voltage, welding speed, travel angle, tip-to-work distance, and shielded gas flow rate. A regression model to predict ultimate tensile strength was developed. Finally, we verified optimization of the process parameters experimentally. We achieved an optimum tensile strength (558 MPa) and wire feed rate, 19 m/min, had the greatest effect, followed by tip-to-work distance, 7 mm, welding speed, 200 mm/min, welding voltage, 30 V, and travel angle, 60°. Shield gas flow rate, 10 L/min, was slightly better but had little effect in the 10–20 L/min range. Tests showed that our regression model was able to predict the ultimate tensile strength within 4%. PMID:26491719

  4. Explosive Welding of Aluminum, Titanium and Zirconium to Copper Sheet Metal

    NASA Technical Reports Server (NTRS)

    Hegazy, A. A.; Mote, J. D.

    1985-01-01

    The main material properties affecting the explosive weldability of a certain metal combination are the yield strength, the ductility, the density and the sonic velocity of the two metals. Successful welding of the metal combination depends mainly on the correct choice of the explosive welding parameters; i.e., the stand off distance, the weight of the explosive charge relative to the weight of the flyer plate and the detonation velocity of the explosive. Based on the measured and the handbook values of the properties of interest, the explosive welding parameters were calculated and the arrangements for the explosive welding of the Al alloy 6061-T6, titanium and zirconium to OFHC copper were determined. The relatively small sheet metal thickness (1/8") and the fact that the thickness of the explosive layer must exceed a certain minimum value were considered during the determination of the explosive welding conditions. The results of the metallographic investigations and the measurements of the shear strength at the interface demonstrate the usefulness of these calculations to minimize the number of experimental trials.

  5. Computer Tomography 3-D Imaging of the Metal Deformation Flow Path in Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Schneider, Judy; Beshears, Ronald; Nunes, Arthur C., Jr.

    2004-01-01

    In friction stir welding, a rotating threaded pin tool is inserted into a weld seam and literally stirs the edges of the seam together. This solid-state technique has been successfully used in the joining of materials that are difficult to fusion weld such as aluminum alloys. To determine optimal processing parameters for producing a defect free weld, a better understanding of the resulting metal deformation flow path is required. Marker studies are the principal method of studying the metal deformation flow path around the FSW pin tool. In our study, we have used computed tomography (CT) scans to reveal the flow pattern of a lead wire embedded in a FSW weld seam. At the welding temperature of aluminum, the lead becomes molten and thus tracks the aluminum deformation flow paths in a unique 3-dimensional manner. CT scanning is a convenient and comprehensive way of collecting and displaying tracer data. It marks an advance over previous more tedious and ambiguous radiographic/metallographic data collection methods.

  6. Method of beam welding metallic parts together and apparatus for doing same

    DOEpatents

    Lewandowski, E.F.; Cassidy, D.A.; Sommer, R.G.

    1985-11-29

    This method provides for temporarily clamping a metallic piece to one side of a metallic plate while leaving the opposite side of the plate exposed, and providing a heat conductive heat sink body configured to engage the adjacent portions of such one side of the plate and the piece at all regions proximate to but not at the interface between these components. The exposed side of such plate is then subjected to an electron welding beam, in exact registry with but opposite to the piece. The electron welding beam is supplied with adequate energy for penetrating through the plate, across the interface, and into the piece, whereby the electron welding beam produces molten material from both the plate and the piece in the region of the interface. The molten material flows into any interstices that may exist in the interface, and upon cooling solidifies to provide a welded joint between the plate and piece, where the interface was, virtually without any interstices. The heat sink material prevents the molten material from extrucing beyond what was the interface, to provide a clean welded joint. The heat sink body also mechanically holds the plate and piece together prior to the actual welding.

  7. Method of beam welding metallic parts together and apparatus for doing same

    DOEpatents

    Lewandowski, Edward F.; Cassidy, Dale A.; Sommer, Robert G.

    1987-01-01

    The disclosed method provides for temporarily clamping a metallic piece to one side of a metallic plate while leaving the opposite side of the plate exposed, and providing a heat conductive heat sink body configured to engage the adjacent portions of such one side of the plate and the piece at all regions proximate to but not at the interface between these components. Such exposed side of such plate is then subjected to an electron welding beam, in exact registry with but opposite to the piece. The electron welding beam is supplied with adequate energy for penetrating through the plate, across the interface, and into the piece, whereby the electron welding beam produces molten material from both the plate and the piece in the region of the interface. The molten material flows into any interstices that may exist in the interface, and upon cooling solidifies to provide a welded joint between the plate and piece, where the interface was, virtually without any interstices. The heat sink material prevents the molten material from extruding beyond what was the interface, to provide a clean welded joint. The heat sink body also mechanically holds the plate and piece together prior to the actual welding.

  8. Weldability characteristics of shielded metal arc welded high strength quenched and tempered plates

    NASA Astrophysics Data System (ADS)

    Datta, R.; Mukerjee, D.; Jha, S.; Narasimhan, K.; Veeraraghavan, R.

    2002-02-01

    High strength, quench and tempered (Q&T) plates having yield strength of a minimum of 670 MPa and conforming to SA 517 Gr. F specification were successfully developed at Rourkela Steel Plant in plates up to 40 mm thickness. The plates are used extensively for the fabrication of impellers, penstocks, excavators, dumpers, and raw material handling devices, where welding is an important processing step. SA 517 Gr. F plates, characterized by a relatively high carbon equivalent (CE: ˜0.6) and alloyed with Ni, Cr, Mo, Cu, and V, are susceptible to a crack-sensitive microstructure and cold cracking during welding. In view of the above, the present study investigated the weldability properties of 20 mm thick plates using the shielded metal arc welding (SMAW) process. Implant and elastic restraint cracking (ERC) tests were carried out to assess the cold cracking resistance of the weld joint under different welding conditions. Preheat of 100 °C, partial or full rebake, and a heat input of 14.9 to 15.4 KJ/cm resulted in static fatigue limit (SFL) values well in excess of the minimum specified yield strength (MSYS) of 670 MPa and a critical restraint intensity (K cr) value of 34,650 MPa, indicating adequate cold cracking resistance. Lamellar tear tests conducted using full thickness plates at heat input levels ranging from 9.7 to 14.4 KJ/cm and weld restraint loads (WRL) of 510 to 685 MPa showed no incidence of lamellar tear upon visual, ultrasonic, and four-section macroexamination. The weld joint, based on optimized welding parameters, exhibited adequate tensile strength (812.4 MPa) and low temperature impact toughness 88.3 and 63.4 J (9.2 and 6.6 kg-m) at -40 °C for weld metal (WM), and heat-affected zone (HAZ) properties, respectively. The crack tip opening displacement (CTOD) values of WM and HAZ (0.40 and 0.36 mm, respectively) were superior to that of the parent metal (0.29 mm), indicating adequate resistance of weld joint to brittle fracture. It was concluded that

  9. Solid State Joining of Dissimilar Titanium Alloys

    NASA Astrophysics Data System (ADS)

    Morton, Todd W.

    Solid state joining of titanium via friction stir welding and diffusion bonding have emerged as enablers of efficient monolithic structural designs by the eliminations fasteners for the aerospace industry. As design complexity and service demands increase, the need for joints of dissimilar alloys has emerged. Complex thermomechanical conditions in friction stir weld joints and high temperature deformation behavior differences between alloys used in dissimilar joints gives rise to a highly variable flow pattern within a stir zone. Experiments performed welding Ti-6Al-4V to beta21S show that mechanical intermixing of the two alloys is the primary mechanism for the generation of the localized chemistry and microstructure, the magnitude of which can be directly related to pin rotation and travel speed weld parameters. Mechanical mixing of the two alloys is heavily influenced by strain rate softening phenomena, and can be used to manipulate weld nugget structure by switching which alloy is subjected to the advancing side of the pin. Turbulent mixing of a weld nugget and a significant reduction in defects and weld forces are observed when the beta21S is put on the advancing side of the weld where higher strain rates are present. Chemical diffusion driven by the heat of weld parameters is characterized using energy dispersive x-ray spectroscopy (EDS) and is shown to be a secondary process responsible for generating short-range chemical gradients that lead to a gradient of alpha particle structures. Diffusion calculations are inconsistent with an assumption of steady-state diffusion and show that material interfaces in the weld nugget evolve through the break-down of turbulent interface features generated by material flows. A high degree of recrystallization is seen throughout the welds, with unique, hybrid chemistry grains that are generated at material interfaces in the weld nugget that help to unify the crystal structure of dissimilar alloys. The degree of

  10. Stability evaluation of short-circuiting gas metal arc welding based on ensemble empirical mode decomposition

    NASA Astrophysics Data System (ADS)

    Huang, Yong; Wang, Kehong; Zhou, Zhilan; Zhou, Xiaoxiao; Fang, Jimi

    2017-03-01

    The arc of gas metal arc welding (GMAW) contains abundant information about its stability and droplet transition, which can be effectively characterized by extracting the arc electrical signals. In this study, ensemble empirical mode decomposition (EEMD) was used to evaluate the stability of electrical current signals. The welding electrical signals were first decomposed by EEMD, and then transformed to a Hilbert–Huang spectrum and a marginal spectrum. The marginal spectrum is an approximate distribution of amplitude with frequency of signals, and can be described by a marginal index. Analysis of various welding process parameters showed that the marginal index of current signals increased when the welding process was more stable, and vice versa. Thus EEMD combined with the marginal index can effectively uncover the stability and droplet transition of GMAW.

  11. Metal nanoparticles and IR laser applications in medicine for biotissue ablation and welding

    NASA Astrophysics Data System (ADS)

    Lalayan, A. A.; Israelyan, S. S.

    2016-05-01

    We report the possibility of laser welding and ablation of biotissue by using metal and hybrid metal nanoparticles (NPs) and infrared laser irradiation spectrally located far from plasmon resonances. A nanosecond YAG:Nd laser of wavelength 1064 nm has been used for synthesis of metal NPs. The Ag, Au, Cu, Ti and Ni, as well as Au-Ag and Au-Cu hybrid metal colloidal NPs were formed in a liquid medium. The diagnostic technique of second harmonic generation (SHG) has been applied to determine the biotissue ablation area after IR laser irradiation. The effectiveness of biotissue ablation was 4-5 times larger in the case of a tissue sample colored with metal NPs than for an uncolored sample. IR laser welding has been demonstrated for deep-located biotissue layers colored by metal NPs.

  12. Influence of Solute Content and Solidification Parameters on Grain Refinement of Aluminum Weld Metal

    NASA Astrophysics Data System (ADS)

    Schempp, Philipp; Cross, Carl Edward; Pittner, Andreas; Rethmeier, Michael

    2013-07-01

    Grain refinement provides an important possibility to enhance the mechanical properties ( e.g., strength and ductility) and the weldability (susceptibility to solidification cracking) of aluminum weld metal. In the current study, a filler metal consisting of aluminum base metal and different amounts of commercial grain refiner Al Ti5B1 was produced. The filler metal was then deposited in the base metal and fused in a GTA welding process. Additions of titanium and boron reduced the weld metal mean grain size considerably and resulted in a transition from columnar to equiaxed grain shape ( CET). In commercial pure aluminum (Alloy 1050A), the grain-refining efficiency was higher than that in the Al alloys 6082 and 5083. Different welding and solidification parameters influenced the grain size response only slightly. Furthermore, the observed grain-size reduction was analyzed by means of the undercooling parameter P and the growth restriction parameter Q, which revealed the influence of solute elements and nucleant particles on grain size.

  13. 29 CFR 1915.54 - Welding, cutting and heating of hollow metal containers and structures not covered by § 1915.12.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 7 2011-07-01 2011-07-01 false Welding, cutting and heating of hollow metal containers and... STANDARDS FOR SHIPYARD EMPLOYMENT Welding, Cutting and Heating § 1915.54 Welding, cutting and heating of... which have contained flammable substances shall, before welding, cutting, or heating is undertaken...

  14. 29 CFR 1915.54 - Welding, cutting and heating of hollow metal containers and structures not covered by § 1915.12.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 7 2013-07-01 2013-07-01 false Welding, cutting and heating of hollow metal containers and... STANDARDS FOR SHIPYARD EMPLOYMENT Welding, Cutting and Heating § 1915.54 Welding, cutting and heating of... which have contained flammable substances shall, before welding, cutting, or heating is undertaken...

  15. 29 CFR 1915.54 - Welding, cutting and heating of hollow metal containers and structures not covered by § 1915.12.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 7 2012-07-01 2012-07-01 false Welding, cutting and heating of hollow metal containers and... STANDARDS FOR SHIPYARD EMPLOYMENT Welding, Cutting and Heating § 1915.54 Welding, cutting and heating of... which have contained flammable substances shall, before welding, cutting, or heating is undertaken...

  16. 29 CFR 1915.54 - Welding, cutting and heating of hollow metal containers and structures not covered by § 1915.12.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 7 2014-07-01 2014-07-01 false Welding, cutting and heating of hollow metal containers and... STANDARDS FOR SHIPYARD EMPLOYMENT Welding, Cutting and Heating § 1915.54 Welding, cutting and heating of... which have contained flammable substances shall, before welding, cutting, or heating is undertaken...

  17. 29 CFR 1915.54 - Welding, cutting and heating of hollow metal containers and structures not covered by § 1915.12.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Welding, cutting and heating of hollow metal containers and... STANDARDS FOR SHIPYARD EMPLOYMENT Welding, Cutting and Heating § 1915.54 Welding, cutting and heating of... which have contained flammable substances shall, before welding, cutting, or heating is undertaken...

  18. The Impact of Teaching Oxy-Fuel Welding on Gas Metal Arc Welding Skills

    ERIC Educational Resources Information Center

    Sgro, Sergio D.; Field, Dennis W.; Freeman, Steven A.

    2008-01-01

    Industrial technology programs around the country must be sensitive to the demands of manufacturing and industry as they continue to replace "vocational" curriculum with high-tech alternatives. This article examines whether or not teaching oxyacetylene welding in the industrial technology classroom is required to learn arc welding…

  19. Precipitation of sigma and chi phases in δ-ferrite of Type 316FR weld metals

    SciTech Connect

    Chun, Eun Joon; Baba, Hayato; Nishimoto, Kazutoshi; Saida, Kazuyoshi

    2013-12-15

    The decomposition behavior and kinetics of δ-ferrite are examined using aging treatments between 873 and 1073 K for Type 316FR stainless steel weld metals with different solidification modes (316FR AF, 316FR FA). The dominant precipitates are sigma, chi, and secondary austenite nucleated at δ-ferrite/austenite interfaces or in the interior of the ferrite grains. These precipitates consume all the ferrite during isothermal aging in both 316FR AF and FA weld metals. Differences in the precipitation behavior (precipitation initiation time and precipitation speed) between weld metals can be explained by i) the degree of Cr and Mo microsegregation within δ-ferrite or austenite near ferrite and ii) the nucleation sites induced due to the solidification mode (AF or FA), such as the ferrite amount. For both weld materials, a Johnson–Mehl-type equation can express the precipitation behavior of the sigma + chi phases and quantitatively predict the behavior at the service-exposure temperatures of a fast breed reactor. - Highlights: • Precipitation of σ and χ phase in Type 316FR welds (two solidification modes) • Different precipitation behaviors: precipitation initiation time and growth speed • Johnson-Mehl–type equation is the most applicable to the precipitation behaviors • Precipitation behaviors are predicted under service conditions of FBRs.

  20. Heat and fluid flow in complex joints during gas metal arc welding—Part I: Numerical model of fillet welding

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Kim, C.-H.; DebRoy, T.

    2004-05-01

    Gas metal arc (GMA) fillet welding is one of the most important processes for metal joining because of its high productivity and amiability to automation. This welding process is characterized by the complicated V-shaped joint geometry, a deformable weld pool surface, and the additions of hot metal droplets. In the present work, a three-dimensional numerical heat transfer and fluid flow model was developed to examine the temperature profiles, velocity fields, weld pool shape and size, and the nature of the solidified weld bead geometry during GMA fillet welding. The model solved the equations of conservation of mass, momentum, and energy using a boundary fitted curvilinear coordinate system. Apart from the direct transport of heat from the welding arc, additional heat from the metal droplets was modeled considering a volumetric heat source. The deformation of the weld pool surface was calculated by minimizing the total surface energy. Part I of this article is focused on the details of the numerical model such as coordinate transformation and calculation of volumetric heat source and free surface profile. An application of the model to GMA fillet welding of mild steel is described in an accompanying article (W. Zhang, C.-H. Kim and T. DebRoy, J. Appl Phys. 95, 5220 (2004)).

  1. Seal welded cast iron nuclear waste container

    DOEpatents

    Filippi, Arthur M.; Sprecace, Richard P.

    1987-01-01

    This invention identifies methods and articles designed to circumvent metallurgical problems associated with hermetically closing an all cast iron nuclear waste package by welding. It involves welding nickel-carbon alloy inserts which are bonded to the mating plug and main body components of the package. The welding inserts might be bonded in place during casting of the package components. When the waste package closure weld is made, the most severe thermal effects of the process are restricted to the nickel-carbon insert material which is far better able to accommodate them than is cast iron. Use of nickel-carbon weld inserts should eliminate any need for pre-weld and post-weld heat treatments which are a problem to apply to nuclear waste packages. Although the waste package closure weld approach described results in a dissimilar metal combination, the relative surface area of nickel-to-iron, their electrochemical relationship, and the presence of graphite in both materials will act to prevent any galvanic corrosion problem.

  2. Innovative Tools Advance Revolutionary Weld Technique

    NASA Technical Reports Server (NTRS)

    2009-01-01

    (no toxic smoke or shielding gas, liquid metal splatter, arcing, dangerous voltage, or radiation), and environmentally sound (no consumables, fumes, or noise) than fusion welding. Under computer control, an automated FSW machine can create welds with high reproducibility, improving efficiency and overall quality of manufactured materials. The process also allows for welding dissimilar metals as well as those metals considered to be "unweldable" such as the 7xxx series aluminum alloys. Its effectiveness and versatility makes FSW useful for aerospace, rail, automotive, marine, and military applications. A downside to FSW, however, is the keyhole opening left in the weld when the FSW pin tool exits the weld joint. This is a significant problem when using the FSW process to join circumferential structures such as pipes and storage containers. Furthermore, weld joints that taper in material thickness also present problems when using the conventional FSW pin tool, because the threaded pin rotating within the weld joint material is a fixed length. There must be capability for the rotating pin to both increase and decrease in length in real time while welding the tapered material. (Both circumferential and tapered thickness weldments are found in the space shuttle external tank.) Marshall engineers addressed both the keyhole and tapered material thickness problems by developing the auto-adjustable pin tool. This unique piece of equipment automatically withdraws the pin into the tool s shoulder for keyhole closeout. In addition, the auto-adjustable pin tool retracts, or shortens, the rotating pin while welding a weld joint that tapers from one thickness to a thinner thickness. This year, the impact of the Marshall innovation was recognized with an "Excellence in Technology Transfer Award" from the Federal Laboratory Consortium.

  3. Effect of alloying on microstructure and precipitate evolution in ferritic weld metal

    NASA Astrophysics Data System (ADS)

    Narayanan, Badri Kannan

    The effect of alloying on the microstructure of ferritic weld metal produced with an self-shielded flux cored arc welding process (FCAW-S) has been studied. The welding electrode has a flux core that is intentionally alloyed with strong deoxidizers and denitriding elements such as aluminum, titanium and zirconium in addition to austenite formers such as manganese and nickel. This results in formation of microstructure consisting of carbide free bainite, retained austenite and twinned martensite. The work focuses on characterization of the microstructures and the precipitates formed during solidification and the allotropic phase transformation of the weld metal. Aluminum, manganese and nickel have significant solubility in iron while aluminum, titanium and zirconium have very strong affinity for nitrogen and oxygen. The effect of these alloying elements on the phase transformation and precipitation of oxides and nitrides have been studied with various characterization techniques. In-situ X-ray synchrotron diffraction has been used to characterize the solidification path and the effect of heating and cooling rates on microstructure evolution. Scanning Transmission Electron Microscopy (STEM) in conjunction with Energy Dispersive Spectroscopy (EDS) and Electron energy loss spectroscopy (EELS) was used to study the effect of micro-alloying additions on inclusion evolution. The formation of core-shell structure of oxide/nitride is identified as being key to improvement in toughness of the weld metal. Electron Back Scattered Diffraction (EBSD) in combination with Orientation Imaging Microscopy (OIM) and Transmission electron microscopy (TEM) has been employed to study the effect of alloying on austenite to ferrite transformation modes. The prevention of twinned martensite has been identified to be key to improving ductility for achieving high strength weld metal.

  4. Ballistic-Failure Mechanisms in Gas Metal Arc Welds of MIL A46100 Armor-Grade Steel: A Computational Investigation

    DTIC Science & Technology

    2014-06-12

    distribution is unlimited. Ballistic-Failure Mechanisms in Gas Metal Arc Welds of Mil A46100 Armor- Grade Steel : A Computational Investigation The views...Welds of Mil A46100 Armor- Grade Steel : A Computational Investigation Report Title In our recent work, a multi-physics computational model for the...utility of the upgraded GMAW process model, it is next applied to the case of butt-welding of a prototypical high-hardness armor- grade martensitic steel

  5. Cardiovascular effects in rats after intratracheal instillation of metal welding particles

    PubMed Central

    Zheng, Wen; Antonini, James M.; Lin, Yen-Chang; Roberts, Jenny R.; Kashon, Michael L.; Castranova, Vincent; Kan, Hong

    2015-01-01

    Studies have indicated that pulmonary exposure to welding fumes can induce a series of adverse effects in the respiratory system, including infection, bronchitis, siderosis and decreased pulmonary function. Recent clinical and epidemiological studies have found that pulmonary exposure to welding fumes is also associated with a higher incidence of cardiovascular events. However, there is insufficient evidence to confirm a direct effect of welding fumes on the cardiovascular system. The present study investigated the effects of pulmonary exposure to welding fumes on the heart and the vascular system in rats. Two chemically distinct welding fumes generated from manual metal arc-hard surfacing (MMA-HS) and gas metal arc-mild steel (GMA-MS) welding were tested. Three groups of rats were instilled intratracheally with MMA-HS (2 mg/rat), GMA-MS (2 mg/rat) or saline as control once a week for seven weeks. On days 1 and 7 after the last treatment, basal cardiovascular function and the cardiovascular response to increasing doses of adrenoreceptor agonists were assessed. MMA-HS treatment reduced the basal levels of left ventricle end-systolic pressure and dP/dtmax at 1 day post-treatment, and decreased dP/dtmin in response to isoproterenol (ISO) at 7 days post-treatment. Unlike MMA-HS, GMA-MS only affected left ventricular end-diastolic pressure in response to ISO at 7 days post-treatment. Treatment with MMA-HS or GMA-MS did not alter heart rate and blood pressure. Our findings suggest that exposure to different welding fumes can induce different adverse effects on the cardiovascular system, and that cardiac contractility may be a sensitive indicator of cardiovascular dysfunction. PMID:25600139

  6. Cardiovascular effects in rats after intratracheal instillation of metal welding particles.

    PubMed

    Zheng, Wen; Antonini, James M; Lin, Yen-Chang; Roberts, Jenny R; Kashon, Michael L; Castranova, Vincent; Kan, Hong

    2015-01-01

    Studies have indicated that pulmonary exposure to welding fumes can induce a series of adverse effects in the respiratory system, including infection, bronchitis, siderosis and decreased pulmonary function. Recent clinical and epidemiological studies have found that pulmonary exposure to welding fumes is also associated with a higher incidence of cardiovascular events. However, there is insufficient evidence to confirm a direct effect of welding fumes on the cardiovascular system. The present study investigated the effects of pulmonary exposure to welding fumes on the heart and the vascular system in rats. Two chemically distinct welding fumes generated from manual metal arc-hard surfacing (MMA-HS) and gas metal arc-mild steel (GMA-MS) welding were tested. Three groups of rats were instilled intratracheally with MMA-HS (2 mg/rat), GMA-MS (2 mg/rat) or saline as control once a week for seven weeks. On days 1 and 7 after the last treatment, basal cardiovascular function and the cardiovascular response to increasing doses of adrenoreceptor agonists were assessed. MMA-HS treatment reduced the basal levels of left ventricle end-systolic pressure and dP/dt(max) at 1 day post-treatment, and decreased dP/dt(min) in response to isoproterenol (ISO) at 7 days post-treatment. Unlike MMA-HS, GMA-MS only affected left ventricular end-diastolic pressure in response to ISO at 7 days post-treatment. Treatment with MMA-HS or GMA-MS did not alter heart rate and blood pressure. Our findings suggest that exposure to different welding fumes can induce different adverse effects on the cardiovascular system, and that cardiac contractility may be a sensitive indicator of cardiovascular dysfunction.

  7. Mass Transfer of Nickel-Base Alloy Covered Electrode During Shielded Metal Arc Welding

    NASA Astrophysics Data System (ADS)

    Qin, Renyao; He, Guo

    2013-03-01

    The mass transfer in shielded metal arc welding of a group of nickel-base alloy covered electrodes according to AWS specification A5.11-A5.11M was investigated by directly measuring their deposited metal compositions. The results indicate that the chromium mass-transfer coefficient is in the range of 86 to 94 pct, iron in the range of 82 to 89 pct, manganese in the range of 60 to 73 pct, niobium in the range of 44 to 56 pct, and silicon in the range of 41 to 47 pct. The metal mass-transfer coefficient from the core wire is markedly higher than that from the coating. The basicity of slag, the metal contents in the flux coating, and the welding current together affect the mass transfer. As the basicity of slag increases, the mass-transfer coefficients of Mn, Fe, and Cr slightly increase, but those of Nb and Si decrease significantly. As the niobium and manganese contents increase in the coating, their mass-transfer coefficients also increase. However, iron is different. The content of iron in the coating in the range of 8 to 20 wt pct results in the optimal effective mass transfer. The lower, or higher, iron content leads to lower mass-transfer coefficient. As the welding current increases, the mass-transfer coefficients of niobium and manganese decrease, but chromium and silicon increase. Iron has the lowest mass-transfer coefficient when welded under the operating current of 100 A.

  8. Investigation of Friction Stir Welding and Laser Engineered Net Shaping of Metal Matrix Composite Materials

    NASA Technical Reports Server (NTRS)

    Diwan, Ravinder M.

    2002-01-01

    The improvement in weld quality by the friction stir welding (FSW) process invented by TWI of Cambridge, England, patented in 1991, has prompted investigation of this process for advanced structural materials including Al metal matrix composite (Al-MMC) materials. Such materials can have high specific stiffness and other potential beneficial properties for the extreme environments in space. Developments of discontinuous reinforced Al-MMCs have found potential space applications and the future for such applications is quite promising. The space industry has recognized advantages of the FSW process over conventional welding processes such as the absence of a melt zone, reduced distortion, elimination of the need for shielding gases, and ease of automation. The process has been well proven for aluminum alloys, and work is being carried out for ferrous materials, magnesium alloys and copper alloys. Development work in the FSW welding process for joining of Al-MMCs is relatively recent and some of this and related work can be found in referenced research publications. NASA engineers have undertaken to spear head this research development work for FSW process investigation of Al-MMCs. Some of the reported related work has pointed out the difficulty in fusion welding of particulate reinforced MMCs where liquid Al will react with SiC to precipitate aluminum carbide (Al4C3). Advantages of no such reaction and no need for joint preparation for the FSW process is anticipated in the welding of Al-MMCs. The FSW process has been best described as a combination of extrusion and forging of metals. This is carried out as the pin tool rotates and is slowly plunged into the bond line of the joint as the pin tool's shoulder is in intimate contact with the work piece. The material is friction-stirred into a quality weld. Al-MMCs, 4 in. x 12 in. plates of 0.25 in. (6.35mm) thickness, procured from MMCC, Inc. were butt welded using FSW process at Marshall Space Flight Center (MSFC) using

  9. Analysis of Dissimilar Material Defect Based on Eddy Current Conductivity Testing

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaofan; Li, Lifu

    In this experiment, the conductivity distribution of lack of penetration (LOP) in friction stir welding (FSW) of dissimilar materials has been tested, and has been compared with the conductivity distribution of the same kind of material, by using eddy current conductivity meter. CZ state and M state LY12 aluminum alloy has been studied. The results show that when the depth of LOP is small, the conductivity of M state is the highest, the conductivity decreases gradually to the weld center, reduce to the minimum until reach the CZ state base metal. When the depth of LOP is larger, the conductivity of the weld center decreases sharply with the depth of LOP increases gradually. Scilicet, the larger the depth of LOP, the lower the conductivity. The conductivity distribution of other areas is similar to the distribution when the depth of LOP is small.

  10. Solar cell welded interconnection development program. [parallel gap and ultrasonic metal-metal bonding

    NASA Technical Reports Server (NTRS)

    Katzeff, J. S.

    1974-01-01

    Parallel gap welding and ultrasonic bonding techniques were developed for joining selected interconnect materials (silver, aluminum, copper, silver plated molybdenum and Kovar) to silver-titanium and aluminum contact cells. All process variables have been evaluated leading to establishment of optimum solar cell, interconnect, electrodes and equipment criteria for obtainment of consistent high quality welds. Applicability of nondestructive testing of solar cell welds has been studied. A pre-weld monitoring system is being built and will be utilized in the numerically controlled parallel gap weld station.

  11. Microstructure-Based Strength Distribution Across the Welds of Nickel-Based Superalloy Inconel 751 and Austenite Steel 21-4N Joined by Inertia Friction Welding

    NASA Astrophysics Data System (ADS)

    Zhu, Yuanzhi; Guo, Yingying; Yang, Libin

    2013-04-01

    Welding dissimilar metals is always a challenge for their different physical property and microstructures. In this study, the two dissimilar metals 21-4N and Inconel 751 are welded together by inertia friction welding. Microstructure observation shows that the weld can be divided into three regions in 21-4N: the chemical composition mixture zone, shear zone, and base metal. The width of the chemical composition mixture zone (CMZ) is about 80 μm, with relatively larger grains and lower dislocation density distributed in this zone. Shear banding occurs in the shear zone, and carbides are found to have precipitated strongly along these shear bands noncontinuously. The base metal contains an austenite microstructure with carbides distributed in the matrix. In Inconel 751, only two typical zones can be observed: the CMZ and the base metal. The heat-affected zone is too small to be observed in the whole weld. Finally, a strength model based on microstructural evolution is proposed. The strength distribution along the axial direction of the welds is calculated. The results are in good agreement with the measurements.

  12. JOINING DISSIMILAR MATERIALS USING FRICTION STIR SCRIBE TECHNIQUE

    SciTech Connect

    Upadhyay, Piyush; Hovanski, Yuri; Jana, Saumyadeep; Fifield, Leonard S.

    2016-09-01

    Development of robust and cost effective method of joining dissimilar materials can provide a critical pathway to enable widespread use of multi-material design and components in mainstream industrial applications. The use of multi-material components such as Steel-Aluminum, Aluminum-Polymer allows design engineers to optimize material utilization based on service requirements and often lead weight and cost reductions. However producing an effective joint between materials with vastly different thermal, microstructural and deformation response is highly problematic using conventional joining and /or fastening methods. This is especially challenging in cost sensitive high volume markets that largely rely on low–cost joining solutions. Friction Stir Scribe technology was developed to meet the demands of joining materials with drastically different properties and melting regimes. The process enables joining of light metals like Magnesium and Aluminum to high temperature materials like Steels and Titanium. Additionally viable joints between polymer composites and metal can also be made using this method. This paper will present state of the art, progress made and challenges associated with this innovative derivative of Friction Stir welding in reference to joining dissimilar metals and polymer/metal combinations.

  13. Joining Dissimilar Materials Using Friction Stir Scribe Technique

    SciTech Connect

    Upadhyay, Piyush; Hovanski, Yuri; Jana, Saumyadeep; Fifield, Leonard S.

    2016-10-03

    Development of a robust and cost-effective method of joining dissimilar materials could provide a critical pathway to enable widespread use of multi-material designs and components in mainstream industrial applications. The use of multi-material components such as steel-aluminum and aluminum-polymer would allow design engineers to optimize material utilization based on service requirements and could often lead to weight and cost reductions. However, producing an effective joint between materials with vastly different thermal, microstructural, and deformation responses is highly problematic using conventional joining and/or fastening methods. This is especially challenging in cost sensitive, high volume markets that largely rely on low cost joining solutions. Friction stir scribe technology was developed to meet the demands of joining materials with drastically different properties and melting regimes. The process enables joining of light metals like magnesium and aluminum to high temperature materials like steel and titanium. Viable joints between polymer composites and metal can also be made using this method. This paper will present the state of the art, progress made, and challenges associated with this innovative derivative of friction stir welding in reference to joining dissimilar metals and polymer/metal combinations.

  14. Disk Laser Weld Brazing of AW5083 Aluminum Alloy with Titanium Grade 2

    NASA Astrophysics Data System (ADS)

    Sahul, Miroslav; Sahul, Martin; Vyskoč, Maroš; Čaplovič, Ľubomír; Pašák, Matej

    2017-03-01

    Disk laser weld brazing of dissimilar metals was carried out. Aluminum alloy 5083 and commercially pure titanium Grade 2 with the thickness of 2.0 mm were used as experimental materials. Butt weld brazed joints were produced under different welding parameters. The 5087 aluminum alloy filler wire with a diameter of 1.2 mm was used for joining dissimilar metals. The elimination of weld metal cracking was attained by offsetting the laser beam. When the offset was 0 mm, the intermixing of both metals was too high, thus producing higher amount of intermetallic compounds (IMCs). Higher amount of IMCs resulted in poorer mechanical properties of produced joints. Grain refinement in the fusion zone occurred especially due to the high cooling rates during laser beam joining. Reactions at the interface varied in the dependence of its location. Continuous thin IMC layer was observed directly at the titanium-weld metal interface. Microhardness of an IMC island in the weld metal reached up to 452.2 HV0.1. The XRD analysis confirmed the presence of tetragonal Al3Ti intermetallic compound. The highest tensile strength was recorded in the case when the laser beam offset of 300 μm from the joint centerline toward aluminum alloy was utilized.

  15. An Assessment of Molten Metal Detachment Hazards for Electron Beam Welding in the Space Environment: Analysis and Test Results

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.; Russell, C.; Bhat, B.; Fragomeni, J. M.

    1998-01-01

    Conditions under which molten metal detachments might occur in a space welding environment are analyzed. A weld pool detachment parameter specifying conditions for pool detachment by impact is derived and corroborated by experimental evidence. Impact detachment for the pool is unlikely. Impact detachment for a drop of metal on the end of the weld wire may be possible under extreme conditions. Other potential causes of molten metal detachment considered, vaporization pressure forces and wire flickout from the pool, did not appear to present significant detachment threats.

  16. Friction-Stir Welding - Heavy Inclusions in Bi-metallic welds of Al 2219/2195

    NASA Technical Reports Server (NTRS)

    Rietz, Ward W., Jr.

    2008-01-01

    Heavy Inclusions (HI) were detected for the first time by radiographic examination in aluminum alloy 2219forging/2195plate (advancing/retreating side) Friction Sir Welds (FSW) for the Space Shuttle External Tank (ET) Program. Radiographic HI indications appear as either small (approx.0.005"-0.025") individual particles or clusters of small particles. Initial work was performed to verify that the HI was not foreign material or caused by FSW pin tool debris. That and subsequent elemental analysis determined that the HI were large agglomerations of Al2Cu (theta phase), which is the strengthening precipitate in Al2219. A literature search on that subject determined that the agglomeration of phase has also been found in Al2219 bead on plate FSW [Ref. 1]. Since this was detected in ET space flight hardware, an investigative study of the effect of agglomerated theta phase particles in FSW Al2219f/2195p was performed. Numerous panels of various lengths were welded per ET weld procedures and radiographically inspected to determine if any HI was detected. Areas that had HI were sampled for room temperature and cyclic cryogenic (-423F) tensile testing and determined no significant adverse affect on mechanical properties when compared to test specimens without HI and historical data. Fracture surface examination using the Scanning Electron Microscope (SEM) revealed smaller phase agglomerations undetectable by radiographic inspection dispersed throughout the Al2219f/2195p FSW. This indicates that phase agglomeration is inherent to the Al2219f/2195p FSW process and only rarely creates agglomerations large enough to be detected by radiography. HI has not been observed in FSW of plate to plate material for either Al2219 or AL2195.

  17. Al-Si-Mn Alloy Coating on Aluminum Substrate Using Cold Metal Transfer (CMT) Welding Technique

    NASA Astrophysics Data System (ADS)

    Rajeev, G. P.; Kamaraj, M.; Bakshi, S. R.

    2014-06-01

    The cold metal transfer (CMT) process was explored as a weld overlay technique for synthesizing Al-Si-Mn alloy coating on a commercially pure Al plate. The effect of welding speed on the bead geometry, deposition rate, and the dilution were studied and the best parameter was used to synthesize the coatings. The CMT process can be used to produce thick coatings (>2.5 mm) without porosity and with low dilution levels. The Vickers hardness number of the Al substrate increased from 28 in the bulk to 57 in the coating. It is suggested that the CMT process can be an effective and energy-efficient technique for depositing thick coatings and is useful in weld repair of aluminum alloy components.

  18. Study on fundamental processes of laser welded metals observed with intense x-ray beams

    NASA Astrophysics Data System (ADS)

    Muramatsu, T.; Daido, H.; Shobu, T.; Takase, K.; Tsukimori, K.; Kureta, M.; Segawa, M.; Nishimura, A.; Suzuki, Y.; Kawachi, T.

    With use of photon techniques including visible light, soft and hard x-rays, precise fundamental laser welding processes in the repair and maintenance of nuclear plant engineering were reviewed mechanistically. We make discussions centered on the usefulness of an intense soft x-ray beams for evaluations of spatial residual strain distribution and welded metal convection behavior including the surface morphology. Numerical results obtained with a general purpose three-dimensional code SPLICE for the simulation of the welding and solidifying phenomena. Then it is concluded that the x-ray beam would be useful as one of the powerful tools for understanding the mechanisms of various complex phenomena with higher accuracy and higher resolution.

  19. Total Fume and Metal Concentrations during Welding in Selected Factories in Jeddah, Saudi Arabia

    PubMed Central

    Balkhyour, Mansour Ahmed; Goknil, Mohammad Khalid

    2010-01-01

    Welding is a major industrial process used for joining metals. Occupational exposure to welding fumes is a serious occupational health problem all over the world. The degree of risk to welder’s health from fumes depends on composition, concentration, and the length of exposure. The aim of this study was to investigate workers’ welding fume exposure levels in some industries in Jeddah, Saudi Arabia. In each factory, the air in the breathing zone within 0.5 m from welders was sampled during 8-hour shifts. Total particulates, manganese, copper, and molybdenum concentrations of welding fumes were determined. Mean values of eight-hour average particulate concentrations measured during welding at the welders breathing zone were 6.3 mg/m3 (Factory 1), 5.3 mg/m3 (Factory 2), 11.3 mg/m3 (Factory 3), 6.8 mg/m3 (Factory 4), 4.7 mg/m3 (Factory 5), and 3.0 mg/m3 (Factory 6). Mean values of airborne manganese, copper, and molybdenum levels measured during welding were in the range of 0.010 mg/m3–0.477 mg/m3, 0.001 mg/m3–0.080 mg/m3 and 0.001 mg/m3–0.058 mg/m3 respectively. Mean values of calculated equivalent exposure values were: 1.50 (Factory 1), 1.56 (Factory 2), 5.14 (Factory 3), 2.21 (Factory 4), 2.89 (Factory 5), and 1.20 (Factory 6). The welders in factories 1, 2, 3, and 4 were exposed to welding fume concentration above the SASO limit value, which may increase the risk of respiratory health problems. PMID:20717553

  20. Total fume and metal concentrations during welding in selected factories in Jeddah, Saudi Arabia.

    PubMed

    Balkhyour, Mansour Ahmed; Goknil, Mohammad Khalid

    2010-07-01

    Welding is a major industrial process used for joining metals. Occupational exposure to welding fumes is a serious occupational health problem all over the world. The degree of risk to welder's health from fumes depends on composition, concentration, and the length of exposure. The aim of this study was to investigate workers' welding fume exposure levels in some industries in Jeddah, Saudi Arabia. In each factory, the air in the breathing zone within 0.5 m from welders was sampled during 8-hour shifts. Total particulates, manganese, copper, and molybdenum concentrations of welding fumes were determined. Mean values of eight-hour average particulate concentrations measured during welding at the welders breathing zone were 6.3 mg/m(3) (Factory 1), 5.3 mg/m(3) (Factory 2), 11.3 mg/m(3) (Factory 3), 6.8 mg/m(3) (Factory 4), 4.7 mg/m(3) (Factory 5), and 3.0 mg/m(3) (Factory 6). Mean values of airborne manganese, copper, and molybdenum levels measured during welding were in the range of 0.010 mg/m(3)-0.477 mg/m(3), 0.001 mg/m(3)-0.080 mg/m(3) and 0.001 mg/m(3)-0.058 mg/m(3) respectively. Mean values of calculated equivalent exposure values were: 1.50 (Factory 1), 1.56 (Factory 2), 5.14 (Factory 3), 2.21 (Factory 4), 2.89 (Factory 5), and 1.20 (Factory 6). The welders in factories 1, 2, 3, and 4 were exposed to welding fume concentration above the SASO limit value, which may increase the risk of respiratory health problems.

  1. An Investigation of Mechanical Properties of Shielded Metal Arc Welding and Friction Stir Welding in 7020-T6 A1 Alloy

    NASA Astrophysics Data System (ADS)

    Jalal, Shawnim R.; Saeed, Mohammedtahir M.; Khider, Gawhar I.

    2014-06-01

    Two different types of welds, shielded metal arc (SMA) welding and friction stir welding (FSW) have been used to weld Aluminum alloy 7020-T6.Investigation has been carried out on mechanical properties such as (yield and tensile strength, impact, harnesses, ductility ,and microstructure) . The result shows that both method could be used to weld such alloy although FSW weld show higher mechanical properties comparison to SMA with joint efficiency equal to 97% compared to 58% in SMA .The extension of the heat affected zone is higher in SMA method in comparison to the FSW and localized grain size for FSW in the stirred zone was 15-18 micron and it was 37- 39 micron for SMA, while it was 32-35 micron for the base metal.In general decay of mechanical properties of SMA joints, was due to high temperature experienced by the material, but in FSW joint lower temperature are involved in the process due to sever plastic deformation induced by the tool motion.

  2. Urinary neutrophil gelatinase-associated lipocalin is associated with heavy metal exposure in welding workers

    NASA Astrophysics Data System (ADS)

    Chuang, Kai-Jen; Pan, Chih-Hong; Su, Chien-Ling; Lai, Ching-Huang; Lin, Wen-Yi; Ma, Chih-Ming; Ho, Shu-Chuan; Bien, Mauo-Ying; Chen, Cheng-Hsien; Chuang, Hsiao-Chi

    2015-12-01

    Metals cause nephrotoxicity with acute and/or chronic exposure; however, few epidemiological studies have examined impacts of exposure to metal fumes on renal injury in welding workers. In total, 66 welding workers and 12 office workers were recruited from a shipyard located in southern Taiwan. Urine samples from each subject were collected at the beginning (baseline) and end of the work week (1-week exposure). Personal exposure to PM2.5 was measured. The 8-h mean PM2.5 was 50.3 μg/m3 for welding workers and 27.4 μg/m3 for office workers. iTRAQs coupled with LC-MS/MS were used to discover the pathways in response to welding PM2.5 in the urine, suggesting that extracellular matrix (ECM)-receptor interactions are a critical mechanism. ECM-receptor interaction-related biomarkers for renal injury, kidney injury molecule (KIM)-1 and neutrophil gelatinase-associated lipocalin (NGAL), were significantly elevated in welding workers post-exposure, as well as were urinary Al, Cr, Mn, Fe, Co, and Ni levels. NGAL was more significantly associated with Al (r = 0.737, p < 0.001), Cr (r = 0.705, p < 0.001), Fe (r = 0.709, p < 0.001), and Ni (r = 0.657, p < 0.001) than was KIM-1, suggesting that NGAL may be a urinary biomarker for welding PM2.5 exposure. Nephrotoxicity (e.g., renal tubular injury) may be an emerging concern in occupational health.

  3. Urinary neutrophil gelatinase-associated lipocalin is associated with heavy metal exposure in welding workers.

    PubMed

    Chuang, Kai-Jen; Pan, Chih-Hong; Su, Chien-Ling; Lai, Ching-Huang; Lin, Wen-Yi; Ma, Chih-Ming; Ho, Shu-Chuan; Bien, Mauo-Ying; Chen, Cheng-Hsien; Chuang, Hsiao-Chi

    2015-12-17

    Metals cause nephrotoxicity with acute and/or chronic exposure; however, few epidemiological studies have examined impacts of exposure to metal fumes on renal injury in welding workers. In total, 66 welding workers and 12 office workers were recruited from a shipyard located in southern Taiwan. Urine samples from each subject were collected at the beginning (baseline) and end of the work week (1-week exposure). Personal exposure to PM2.5 was measured. The 8-h mean PM2.5 was 50.3 μg/m(3) for welding workers and 27.4 μg/m(3) for office workers. iTRAQs coupled with LC-MS/MS were used to discover the pathways in response to welding PM2.5 in the urine, suggesting that extracellular matrix (ECM)-receptor interactions are a critical mechanism. ECM-receptor interaction-related biomarkers for renal injury, kidney injury molecule (KIM)-1 and neutrophil gelatinase-associated lipocalin (NGAL), were significantly elevated in welding workers post-exposure, as well as were urinary Al, Cr, Mn, Fe, Co, and Ni levels. NGAL was more significantly associated with Al (r = 0.737, p < 0.001), Cr (r = 0.705, p < 0.001), Fe (r = 0.709, p < 0.001), and Ni (r = 0.657, p < 0.001) than was KIM-1, suggesting that NGAL may be a urinary biomarker for welding PM2.5 exposure. Nephrotoxicity (e.g., renal tubular injury) may be an emerging concern in occupational health.

  4. Urinary neutrophil gelatinase-associated lipocalin is associated with heavy metal exposure in welding workers

    PubMed Central

    Chuang, Kai-Jen; Pan, Chih-Hong; Su, Chien-Ling; Lai, Ching-Huang; Lin, Wen-Yi; Ma, Chih-Ming; Ho, Shu-Chuan; Bien, Mauo-Ying; Chen, Cheng-Hsien; Chuang, Hsiao-Chi

    2015-01-01

    Metals cause nephrotoxicity with acute and/or chronic exposure; however, few epidemiological studies have examined impacts of exposure to metal fumes on renal injury in welding workers. In total, 66 welding workers and 12 office workers were recruited from a shipyard located in southern Taiwan. Urine samples from each subject were collected at the beginning (baseline) and end of the work week (1-week exposure). Personal exposure to PM2.5 was measured. The 8-h mean PM2.5 was 50.3 μg/m3 for welding workers and 27.4 μg/m3 for office workers. iTRAQs coupled with LC-MS/MS were used to discover the pathways in response to welding PM2.5 in the urine, suggesting that extracellular matrix (ECM)-receptor interactions are a critical mechanism. ECM-receptor interaction-related biomarkers for renal injury, kidney injury molecule (KIM)-1 and neutrophil gelatinase-associated lipocalin (NGAL), were significantly elevated in welding workers post-exposure, as well as were urinary Al, Cr, Mn, Fe, Co, and Ni levels. NGAL was more significantly associated with Al (r = 0.737, p < 0.001), Cr (r = 0.705, p < 0.001), Fe (r = 0.709, p < 0.001), and Ni (r = 0.657, p < 0.001) than was KIM-1, suggesting that NGAL may be a urinary biomarker for welding PM2.5 exposure. Nephrotoxicity (e.g., renal tubular injury) may be an emerging concern in occupational health. PMID:26673824

  5. Friction Stir Welding of SiC/Aluminum Metal Matrix Composites

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    1999-01-01

    Friction Stir Welding (FSW) is a new solid state process for joining metals by plasticizing and consolidating materials around the bond line using thermal energy producing from frictional forces. A feasibility study for FSW of Metal Matrix Composites (MMC) was investigated using aluminum 6092 alloy reinforced with 17% SiC particulates. FSW process consists of a special rotating pin tool that is positioned to plunge into the MMC surface at the bond line. As the tool rotates and move forward along the bond line, the material at the bond line is heated up and forced to flow around the rotating tip to consolidate on the tip's backside to form a solid state joint. FSW has the potential for producing sound welds with MMC because the processing temperature occurs well below the melting point of the metal matrix; thereby eliminating the reinforcement-to-matrix solidification defects, reducing the undesirable chemical reactions and porosity problems.

  6. Study on ductility dip cracking susceptibility in Filler Metal 82 during welding

    NASA Astrophysics Data System (ADS)

    Chen, Jing-Qing; Lu, Hao; Cui, Wei

    2011-06-01

    In this paper, Ductility Dip Cracking (DDC) susceptibility in Inconel600 companion Filler Metal 82 (FM82) under different stress states is investigated. Inconel600 is a Ni-Cr-Fe alloy with excellent resistance to general corrosion, localized corrosion, and stress corrosion, which has been widely used in nuclear power plants. However, the companion FM82 has been shown to be susceptible to DDC in welding process. To resolve the problem, this work is mainly focused on evaluating DDC susceptibility in FM82 in welding process. First of all, Strain to Fracture (STF) test is used to achieve the DDC criterion under simple stress state, and the formation mechanism of DDC was explained. Real welding is a process with complex stress state. Later, to get the DDC susceptibility under complex stress state, models about multi-pass welding were built up by means of finite element method. According to numerical simulation results, relationship of deformation and temperature history is achieved. Moreover, susceptible locations and moments could be determined associated with STF results. The simulation results fairly agree with welding experiment from another research.

  7. Welding blades to rotors

    NASA Technical Reports Server (NTRS)

    Hoklo, K. H.; Moore, T. J. (Inventor)

    1973-01-01

    A process is described to form T-joints between dissimilar thickness parts by magnetic force upset welding. This type of resistance welding is used to join compressor and turbine parts which thereby reduces the weight and cost of jet engines.

  8. An investigation of the weld region on the SAE 1020 joined with metal active gas and determination of the mismatch factor

    SciTech Connect

    Meric, C.; Tokdemir, M.

    1999-10-01

    In this study, the joining process of SAE 1020 low carbon steel, generally used in the industry, has been completed using the metal active gas (MAG) weld method. The goal of this study was to examine the mismatch between base and weld metal. After the joining process, mechanical properties of the samples of the base metal (BM), the heat affected zone (HAZ), and the weld metal (WM) were investigated, and the crack tip opening displacement (CTOD) test was performed.

  9. Electrically driven rapidly vaporizing foils, wires and strips used for collision welding and sheet metal forming

    DOEpatents

    Vivek, Anupam; Daehn, Glenn S; Taber, Geoffrey A; Johnson, Jason R

    2015-05-05

    A method for forming a piece of a sheet metal is performed by positioning a consumable body, made of metal, proximate to the piece of the sheet metal. The consumable body is rapidly vaporized, and the gas pressure generated thereby is directed into the piece of the sheet metal. This results in acceleration of the piece of sheet metal, and it is collided into a stationary body at a velocity, generally in excess of 200 m/s. Depending upon the type of stationary body, the piece of sheet metal is deformed into a predetermined shape or is welded onto the stationary body. The vaporization is accomplished by passing a high current of electricity into the consumable body. The effect of the vaporized metal may be augmented by additional components in the consumable body.

  10. Determination of the Effect of Current and Travel Speed of Gas Metal-Arc Welding on the Mechanical Properties of A36, A516, and A514 Steels

    DTIC Science & Technology

    1980-05-01

    Identify by block number) steel welded joints gas metal-arc welding 70. AWTRr A ass is ,eYe slob If neoemy Md identify by block numfber) This study was...impact properties of butt joint welds produced by fully automatic gas metal-arc weld - ing (GMAW) in carbon steel (A36), pressure-vessel steel (A5 16), and...with American Society for CURRENT AND TRAVEL SPEED OF GAS Testing and Materials [ASTM] A201 mild steel up to METAL-ARC WELDING ON THE MECHAN- 2 in. (51

  11. Correlation of Flux Composition and Inclusion Characteristics With Submerged Arc Weld Metal Properties in HY-100 Steel

    DTIC Science & Technology

    1993-09-01

    WITH SUBMERGED ARC WELD METAL PROPERTIES IN HY- 100 STEEL by Kent William Kettell September 1993 Thesis Advisor: Alan G. Fox Approved for public... STEEL 12. PERSONAL AUTHOR(S) Kettell, Kent William ,3a. TYPE OF REPORT 13b. TIME COVERED 14. DATE OF REPORT (Year.Month.Day) 15. PAGE COUNT Master’s...necessary and identify by block number) FIELD GROUP SUB-GROUP HY- 100 steel , submerged arc welding, SAW, fluxes, basicity index, non-metallic inclusions

  12. Microstructural Features Controlling Ductile-to-Brittle Transition Behavior in High-Strength, Martensitic Steel Weld Metals

    DTIC Science & Technology

    1990-10-01

    Development Report Microstructural Features Controlling Ductile-to- Brittle Transition Behavior in High-Strength, Martensitic Steel Weld Metals C 0by...Martensitic Steel Weld Metals PERSONAL AUTHOR(S) .J. DeLoach, Jr. .TYPE OF REPORT 13b TIME COVERED 114 DATE OF REPORT (Year, Month, Day) 1S PAGE COUNT I...if necessary and identify by block number) FIELD GROUP SUB-GROUP High strength steel , Ductile-brittle transition Martensitic Mechanical proper ties

  13. Weld pool phenomena

    SciTech Connect

    David, S.A.; Vitek, J.M.; Zacharia, T.; DebRoy, T.

    1994-09-01

    During welding, the composition, structure and properties of the welded structure are affected by the interaction of the heat source with the metal. The interaction affects the fluid flow, heat transfer and mass transfer in the weld pool, and the solidification behavior of the weld metal. In recent years, there has been a growing recognition of the importance of the weld pool transport processes and the solid state transformation reactions in determining the composition, structure and properties of the welded structure. The relation between the weld pool transport processes and the composition and structure is reviewed. Recent applications of various solidification theories to welding are examined to understand the special problems of weld metal solidification. The discussion is focussed on the important problems and issues related to weld pool transport phenomena and solidification. Resolution of these problems would be an important step towards a science based control of composition, structure and properties of the weld metal.

  14. Weld-Bead Shaver

    NASA Technical Reports Server (NTRS)

    Guirguis, Kamal; Price, Daniel S.

    1990-01-01

    Hand-held power tool shaves excess metal from inside circumference of welded duct. Removes excess metal deposited by penetration of tungsten/inert-gas weld or by spatter from electron-beam weld. Produces smooth transition across joint. Easier to use and not prone to overshaving. Also cuts faster, removing 35 in. (89 cm) of weld bead per hour.

  15. Effect of the Metal Transport on the Mechanical Properties of Al-2Si Alloys Processed through Friction Stir Welding Processes

    NASA Astrophysics Data System (ADS)

    Shailesh Rao, A.; Naik, Yuvaraja

    2017-03-01

    In this study, Al-2Si alloys were joined using friction stir welding with various process parameters. The process parameters considered here were rotational speeds from 600 to 1200 rpm, feed rate from 50 to 150 mm/min with three equal increments. In this study, the mushy state metal movements during the processes are discussed. The experimental observation and results indicate that the flaw formations, surface roughness of the weld, and hardness value depend on the metal movement and are explained in this study. The microstructure of the weld zone was studied finally.

  16. Al-to-Cu Friction Stir Lap Welding

    NASA Astrophysics Data System (ADS)

    Firouzdor, Vahid; Kou, Sindo

    2012-01-01

    Recently, friction stir welding (FSW) has been used frequently to join dissimilar metals, for instance, Al to Mg, Cu, and steel. The formation of brittle intermetallic compounds often severely limits the strength and ductility of the resultant welds. In the present study, Al-to-Cu lap FSW was studied by welding 6061 Al to commercially pure Cu. Conventional lap FSW was modified by butt welding a small piece of Al to the top of Cu, with a slight pin penetration into the bottom of Al. At travel speeds up to 127 mm/min (5 ipm), the modified welds were about twice the joint strength and five to nine times the ductility of the conventional lap welds. In the conventional lap welds, voids were present along the Al-Cu interface, and fracture occurred along the interface in tensile testing. No such voids were observed in the modified lap welds, and fracture occurred through Cu. Thus, as in the case of Al-to-Mg lap FSW recently studied by the authors, modified lap FSW significantly improved the weld quality in Al-to-Cu lap FSW. At the relatively high travel speed of 203 mm/min (8 ipm), however, modified lap FSW was no longer superior because of channel formation.

  17. Processing, Microstructure, and Residual Stress Effects on Strength and Fatigue Crack Growth Properties in Friction Stir Welding: A Review

    NASA Astrophysics Data System (ADS)

    Biro, Andrew L.; Chenelle, Brendan F.; Lados, Diana A.

    2012-12-01

    The purpose of this review is to provide a comprehensive overview of friction stir welding (FSW), as well as to introduce current research and applications involving this relatively new process. FSW is a new, efficient way of joining metal alloys that are considered unsuitable for welding via conventional fusion joining methods, and is capable of welding dissimilar metals with ease. This process also has the benefit of being solid-state, which mitigates the need for liquid filler metals that are common with conventional fusion welding techniques. This review will examine different facets of the FSW process, exploring the resulting static and dynamic properties and factors that influence these properties including weld zone boundaries, grain refinement, residual stress, and addition of reinforcing particles. Highlights of current research in this area and applications of this process in various industries will also be presented and discussed.

  18. 30 CFR 56.15007 - Protective equipment or clothing for welding, cutting, or working with molten metal.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., cutting, or working with molten metal. 56.15007 Section 56.15007 Mineral Resources MINE SAFETY AND HEALTH..., cutting, or working with molten metal. Protective clothing or equipment and face shields, or goggles shall be worn when welding, cutting, or working with molten metal....

  19. Effect of pressure and shielding gas on the microstructure of hyperbaric metal cored GMAW welds down to 111 bar

    SciTech Connect

    Jorge, J.C.F.; Santos, V.R. dos

    1995-12-31

    The microstructural evolution of hyperbaric C-Mn weld metals was studied by means of bead-on-plate welds deposit with GMAW process using a commercial metal cored wire. The welding was carried out in the flat position in the range of 51 bar to 111 bar with He+ CO{sub 2} as shielding gas, which CO{sub 2} content varied from 0.1% to 0.8 %. The microstructures were quantitatively analyzed by optical microscopy to evaluate the amount of constituents according to the IIW/IIS terminology. The results showed that all weld metals presented great amounts of acicular ferrite and a stronger influence of pressure on microstructure compared to the influence of the shielding gas.

  20. All-weld-metal design for AWS E10018M, E11018M and E12018M type electrodes

    SciTech Connect

    Surian, E.S.; Vedia, L.A. de

    1999-06-01

    This paper presents the results of a research program conducted to design the all-weld metal deposited with AWS A5.5-81 E10018M, E11018M and E12018M SMAW-type electrodes. The role that different alloying elements such as manganese, carbon and chromium play on the tensile properties, hardness and toughness as well as on the microstructure was studied. Criteria for selecting the weld metal composition leading to optimum combination of tensile strength and toughness are suggested. The effect of the variation of heat input, within the requirements of the AWS standard, on the mentioned properties was also analyzed. It was found that the E11018M and E12018M all-weld-metal tensile properties are very sensitive to variations in heat input. For certain values of chemical composition, welding parameter ranges suitable to guarantee the fulfillment of AWS requirements were determined.

  1. Thermal aging behavior of ERNiCr-3 alloy (weld and base metal)

    SciTech Connect

    Klueh, R.L.; King, J.F.

    1981-08-01

    The nickel-base filler metal alloy ERNiCr-3, containing nominally 67% Ni, 20% Cr, 3% Fe, 3% Mn, and 2.5% Nb, is used widely to make welds for elevated-temperature service. To determine the effect of elevated temperature on tensile and creep-rupture properties of ERNiCr-3, weld metal specimens were thermally aged to 10,000 h at 510/sup 0/C, to 15,000 h at 566/sup 0/C, and to 1000 h at 677/sup 0/C. Wrought ERNiCr-3 was also aged at 566 and 677/sup 0/C. The 0.2% yield strength of the ERNiCr-3 weld metal increased with thermal aging time at 510 and 566/sup 0/C. The ultimate tensile strength also increased continuously with aging time at 566/sup 0/C, whereas at 510/sup 0/C, it went through a maximum (the strength of the material aged 10,000 h was less than was that aged 5000 h).

  2. Experimental comparison of the MIG, friction stir welding, cold metal transfer and hybrid laser-MIG processes for AA 6005-T6 aluminium alloy

    NASA Astrophysics Data System (ADS)

    Caruso, Serafino; Sgambitterra, Emanuele; Rinaldi, Sergio; Gallone, Antonello; Viscido, Lucio; Filice, Luigino; Umbrello, Domenico

    2016-10-01

    In this study, the mechanical properties of welded joints of AA 6005-T6 aluminum alloy obtained with hybrid laser-MIG and cold metal transfer (CMT) welding were analyzed. The performance of hybrid laser-MIG and CMT welded joints were identified using tensile, bending, shear and fatigue life tests. Taking into account the process conditions and requirements, hybrid laser-MIG and CMT welding processes were compared with friction stir welding (FSW) and conventional metal inert gas (MIG) welding processes, shown in a previous work, to understand the advantages and disadvantages of the processes for welding applications of studied Al alloy. Better tensile, bending and shear strength and fatigue life behavior were obtained with hybrid laser-MIG and FSW welded joints compared with conventional MIG processes.

  3. Evaluation and monitoring of UVR in Shield Metal ARC Welding processing.

    PubMed

    Peng, Chiung-yu; Liu, Hung-hsin; Chang, Cheng-ping; Shieh, Jeng-yueh; Lan, Cheng-hang

    2007-08-01

    This study established a comprehensive approach to monitoring UVR magnitude from Shield Metal Arc Welding (SMAW) processing and quantified the effective exposure based on measured data. The irradiances from welding UVR were calculated with biological effective parameter (Slambda) for human exposure assessment. The spectral weighting function for UVR measurement and evaluation followed the American Conference of Governmental Industrial Hygienists (ACGIH) guidelines. Arc welding processing scatters bright light with UVR emission over the full UV spectrum (UVA, UVB, and UVC). The worst case of effective irradiance from a 50 cm distance arc spot with a 200 A electric current and an electrode E6011 (4 mm) is 311.0 microW cm(-2) and has the maximum allowance time (Tmax) of 9.6 s. Distance is an important factor affecting the irradiance intensity. The worst case of the effective irradiance values from arc welding at 100, 200, and 300 cm distances are 76.2, 16.6, and 12.1 microW cm(-2) with Tmax of 39.4, 180.7, and 247.9 s, respectively. Protective materials (glove and mask) were demonstrated to protect workers from hazardous UVR exposure. From this study, the methodology of UVR monitoring in SMAW processing was developed and established. It is recommended that welders should be fitted with appropriate protective materials for protection from UVR emission hazards.

  4. Characterization of airborne particles generated from metal active gas welding process.

    PubMed

    Guerreiro, C; Gomes, J F; Carvalho, P; Santos, T J G; Miranda, R M; Albuquerque, P

    2014-05-01

    This study is focused on the characterization of particles emitted in the metal active gas welding of carbon steel using mixture of Ar + CO2, and intends to analyze which are the main process parameters that influence the emission itself. It was found that the amount of emitted particles (measured by particle number and alveolar deposited surface area) are clearly dependent on the distance to the welding front and also on the main welding parameters, namely the current intensity and heat input in the welding process. The emission of airborne fine particles seems to increase with the current intensity as fume-formation rate does. When comparing the tested gas mixtures, higher emissions are observed for more oxidant mixtures, that is, mixtures with higher CO2 content, which result in higher arc stability. These mixtures originate higher concentrations of fine particles (as measured by number of particles by cm(3) of air) and higher values of alveolar deposited surface area of particles, thus resulting in a more severe worker's exposure.

  5. Factors Affecting the Capture Efficiency of a Fume Extraction Torch for Gas Metal Arc Welding

    PubMed Central

    Bonthoux, Francis

    2016-01-01

    Welding fumes are classified as Group 2B ‘possibly carcinogenic’ and this prompts to the implementation of local exhaust ventilation (LEV). The fume extraction torch with LEV integrated into the tool is the most attractive solution but its capture efficiency is often disappointing in practice. This study assesses the main parameters affecting fume capture efficiency namely the extraction flow rate, the positioning of the suction openings on the torch, the angle of inclination of the torch to the workpiece during welding, the metal transfer modes, and the welding deposition rate. The theoretical velocity induced by suction, estimated from the extraction flow rate and the position of the suction openings, is the main parameter affecting effectiveness of the device. This is the design parameter and its value should never be <0.25 m s−1. The angle of the torch relative to the workpiece also has a great deal of influence. To improve efficiency, work station layouts need to favour positions where the torch is held with angles closer to perpendicular (<15°). Welding with high deposition rates (>1.1g s−1) and spray transfer leads to low capture efficiency if induced velocities are <0.5 m s−1. The results of the study can be used in the design of integrated on-torch extraction systems and provide information for fixing system objectives. PMID:27074798

  6. Electroslag and electrogas welding

    NASA Technical Reports Server (NTRS)

    Campbell, H. C.

    1972-01-01

    These two new joining methods perform welding in the vertical position, and therein lies the secret of their impressive advantages in material handling, in weld preparation, in welding speed, in freedom from distortion, and in weld soundness. Once the work has been set in the proper vertical position for welding, no further plate handling is required. The molten filler metal is held in place by copper shoes or dams, and the weld is completed in one pass.

  7. Characterization of Stainless Steel and Refractory Metal Welds Made using a Diode-Pumped, Continuous Wave Nd: Yag Laser

    SciTech Connect

    Palmer, T A; Wood, B; Elmer, J W; Westrich, C; Milewski, J O; Piltch, M; Barbe, M; Carpenter, R

    2001-10-19

    A series of laser welds have been made on several materials using a Rofin-Sinar DY-033, 3.3 kW, Diode-Pumped Continuous Wave (CW) Nd:YAG laser system, located at Los Alamos National Laboratory. Materials welded in these experiments include 21-6-9 stainless steel, 304L stainless steel, vanadium, and tantalum. The effects of changes in the power input at a constant travel speed on the depth, width, aspect ratio, and total melted area of the welds have been analyzed. Increases in the measured weld pool dimensions as a function of power input are compared for each of the base metals investigated. These results provide a basis for further examining the characteristics of diode pumped CW Nd:YAG laser systems in welding applications.

  8. Automated process control for capacitor-discharge welding

    SciTech Connect

    Wilson, Rick D.; Paul, Brian K.

    1998-01-01

    Capacitor discharge welding (CDW) is an autogenous, rapid solidification, joining process ideal for joining small parts of similar or dissimilar metals. Potential applications include welding of electrical contacts, cutting tool inserts, and automotive valves. Because of high cooling rates in excess of one million °C/s, the production rate for CDW process is very high. However potential industrial users have been hesitant to use CDW due largely to the unavailability of automated process control. The objective of this research was to develop models for an on-line quality control feedback system for CDW. The system described monitors current and voltage curves produced during the welding cycle. These curves have been found to be good indicators of certain types of welding defects. A closed-loop automation architecture for future work will also be discussed.

  9. Interface Phenomena and Bonding Mechanism in Magnetic Pulse Welding

    NASA Astrophysics Data System (ADS)

    Stern, A.; Shribman, V.; Ben-Artzy, A.; Aizenshtein, M.

    2014-10-01

    Magnetic pulse welding (MPW) is a solid-state impact welding technology that provides metallurgical joints while exhibiting a negligible heat-affected zone. The MPW process is a high speed single shot welding technique used mainly for joining tubular components in a lap configuration and characteristic length scales of few millimeters to centimeters. It is similar in operation to explosive welding and shares the same physical principles. The nature of bonding in MPW is not sufficiently understood yet and some controversial explanations are reported in the literature. The two major ideas are based on either solid state bonding or local melting and solidification. The present work summarizes our current understanding of the bonding mechanism and the structure in various similar and dissimilar metal pairs joined by MPW.

  10. Creep behavior and in-depth microstructural characterization of dissimilar joints

    PubMed Central

    Kauffmann, F; Klein, T; Klenk, A; Maile, K

    2013-01-01

    The 700 °C power plants currently under development will utilize Ni-base alloys such as alloy 617 for components to be operated at temperatures >650 °C. Due to economic reasons for components or parts of components which are subjected to temperatures <650 °C, 2% Cr or 9–12% Cr steels is used, depending on the required mechanical properties. This makes the dissimilar joining of Ni-base alloys and Cr steels a necessity in these plants. Experimental investigations show that these joints have to be identified as weak points with regard to damage development under creep and creep-fatigue loading. The present investigation focuses on welds between the alloy 617 and 2% Cr steel. Under creep load the fracture occurs near the fusion line between the 2% Cr steel base metal and alloy 617 weld metal. To explain the reasons for this fracture location, the microstructure of this fusion line was investigated using TEM and FIB techniques after welding and after creep loading. The TEM investigations have shown a small zone in the weld metal near the fusion line exhibiting chromium depletion and clearly reduced amounts of chromium carbides, leading to a weakening of this zone. PMID:27877551

  11. Creep behavior and in-depth microstructural characterization of dissimilar joints.

    PubMed

    Kauffmann, F; Klein, T; Klenk, A; Maile, K

    2013-02-01

    The 700 °C power plants currently under development will utilize Ni-base alloys such as alloy 617 for components to be operated at temperatures >650 °C. Due to economic reasons for components or parts of components which are subjected to temperatures <650 °C, 2% Cr or 9-12% Cr steels is used, depending on the required mechanical properties. This makes the dissimilar joining of Ni-base alloys and Cr steels a necessity in these plants. Experimental investigations show that these joints have to be identified as weak points with regard to damage development under creep and creep-fatigue loading. The present investigation focuses on welds between the alloy 617 and 2% Cr steel. Under creep load the fracture occurs near the fusion line between the 2% Cr steel base metal and alloy 617 weld metal. To explain the reasons for this fracture location, the microstructure of this fusion line was investigated using TEM and FIB techniques after welding and after creep loading. The TEM investigations have shown a small zone in the weld metal near the fusion line exhibiting chromium depletion and clearly reduced amounts of chromium carbides, leading to a weakening of this zone.

  12. Creep behavior and in-depth microstructural characterization of dissimilar joints

    NASA Astrophysics Data System (ADS)

    Kauffmann, F.; Klein, T.; Klenk, A.; Maile, K.

    2013-02-01

    The 700 °C power plants currently under development will utilize Ni-base alloys such as alloy 617 for components to be operated at temperatures >650 °C. Due to economic reasons for components or parts of components which are subjected to temperatures <650 °C, 2% Cr or 9-12% Cr steels is used, depending on the required mechanical properties. This makes the dissimilar joining of Ni-base alloys and Cr steels a necessity in these plants. Experimental investigations show that these joints have to be identified as weak points with regard to damage development under creep and creep-fatigue loading. The present investigation focuses on welds between the alloy 617 and 2% Cr steel. Under creep load the fracture occurs near the fusion line between the 2% Cr steel base metal and alloy 617 weld metal. To explain the reasons for this fracture location, the microstructure of this fusion line was investigated using TEM and FIB techniques after welding and after creep loading. The TEM investigations have shown a small zone in the weld metal near the fusion line exhibiting chromium depletion and clearly reduced amounts of chromium carbides, leading to a weakening of this zone.

  13. Ultrasonic Additive Manufacturing: Weld Optimization for Aluminum 6061, Development of Scarf Joints for Aluminum Sheet Metal, and Joining of High Strength Metals

    NASA Astrophysics Data System (ADS)

    Wolcott, Paul J.

    Ultrasonic additive manufacturing (UAM) is a low temperature, solid-state manufacturing process that enables the creation of layered, solid metal structures with designed anisotropies and embedded materials. As a low temperature process, UAM enables the creation of active composites containing smart materials, components with embedded sensors, thermal management devices, and many others. The focus of this work is on the improvement and characterization of UAM aluminum structures, advancing the capabilities of ultrasonic joining into sheet geometries, and examination of dissimilar material joints using the technology. Optimized process parameters for Al 6061 were identified via a design of experiments study indicating a weld amplitude of 32.8 synum and a weld speed of 200 in/min as optimal. Weld force and temperature were not significant within the levels studied. A methodology of creating large scale builds is proposed, including a prescribed random stacking sequence and overlap of 0.0035 in. (0.0889 mm) for foils to minimize voids and maximize mechanical strength. Utilization of heat treatments is shown to significantly increase mechanical properties of UAM builds, within 90% of bulk material. The applied loads during the UAM process were investigated to determine the stress fields and plastic deformation induced during the process. Modeling of the contact mechanics via Hertzian contact equations shows that significant stress is applied via sonotrode contact in the process. Contact modeling using finite element analysis (FEA), including plasticity, indicates that 5000 N normal loads result in plastic deformation in bulk aluminum foil, while at 3000 N no plastic deformation occurs. FEA studies on the applied loads during the process, specifically a 3000 N normal force and 2000 N shear force, show that high stresses and plastic deformation occur at the edges of a welded foil, and base of the UAM build. Microstructural investigations of heat treated foils confirms

  14. Thermal analysis of friction welding process in relation to the welding of YSZ-alumina composite and 6061 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Uday, M. B.; Fauzi, M. N. Ahmad; Zuhailawati, H.; Ismail, A. B.

    2012-08-01

    The objective of this work is to establish an analytical data for heat generation by friction welding, based on different parameters of the contact condition between two dissimilar materials. The ceramic composite of Al2O3-YSZ and 6061 Al alloy, which is the example of joining materials by friction welding was used in the experiments. Alumina rods containing 0, 25 and 50 wt% yttria stabilized zirconia were produced by slip casting in Plaster of Paris molds and subsequently sintered at 1600 °C. The diameter of both the ceramic and metal rods was 16 mm. Rotational speeds for friction welding were between 630 and 2500 rpm. As a result, different data was evaluated for obtaining joint properties and operating conditions, and obtained results are useful in modeling the welding process and reliability joint under various conditions.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  16. Ballistic-Failure Mechanisms in Gas Metal Arc Welds of Mil A46100 Armor-Grade Steel: A Computational Investigation

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Snipes, J. S.; Galgalikar, R.; Ramaswami, S.; Yavari, R.; Yen, C.-F.; Cheeseman, B. A.

    2014-09-01

    In our recent work, a multi-physics computational model for the conventional gas metal arc welding (GMAW) joining process was introduced. The model is of a modular type and comprises five modules, each designed to handle a specific aspect of the GMAW process, i.e.: (i) electro-dynamics of the welding-gun; (ii) radiation-/convection-controlled heat transfer from the electric-arc to the workpiece and mass transfer from the filler-metal consumable electrode to the weld; (iii) prediction of the temporal evolution and the spatial distribution of thermal and mechanical fields within the weld region during the GMAW joining process; (iv) the resulting temporal evolution and spatial distribution of the material microstructure throughout the weld region; and (v) spatial distribution of the as-welded material mechanical properties. In the present work, the GMAW process model has been upgraded with respect to its predictive capabilities regarding the spatial distribution of the mechanical properties controlling the ballistic-limit (i.e., penetration-resistance) of the weld. The model is upgraded through the introduction of the sixth module in the present work in recognition of the fact that in thick steel GMAW weldments, the overall ballistic performance of the armor may become controlled by the (often inferior) ballistic limits of its weld (fusion and heat-affected) zones. To demonstrate the utility of the upgraded GMAW process model, it is next applied to the case of butt-welding of a prototypical high-hardness armor-grade martensitic steel, MIL A46100. The model predictions concerning the spatial distribution of the material microstructure and ballistic-limit-controlling mechanical properties within the MIL A46100 butt-weld are found to be consistent with prior observations and general expectations.

  17. Preliminary study on pressure brazing and diffusion welding of Nb-1Zr to Inconel 718

    NASA Technical Reports Server (NTRS)

    Moore, T. J.

    1990-01-01

    Future space power systems may include Nb-1Zr/Inconel 718 dissimilar metal joints for operation at 1000 K for 60,000 h. The serviceability of pressure-brazed and diffusion-welded joints was investigated. Ni-based metallic glass foil filler metals were used for brazing. Ni and Fe foils were used as diffusion welding inter-layers. Joint soundness was determined by metallographic examination in the as-brazed and as-welded condition, after aging at 1000 K, and after thermal cycling. Brazed joints thermally cycled in the as-brazed condition and diffusion-welded joints were unsatisfactory because of cracking problems. Brazed joints may meet the service requirements if the joints are aged at 1000 K prior to thermal cycling.

  18. Assessment of the biological effects of welding fumes emitted from metal inert gas welding processes of aluminium and zinc-plated materials in humans.

    PubMed

    Hartmann, L; Bauer, M; Bertram, J; Gube, M; Lenz, K; Reisgen, U; Schettgen, T; Kraus, T; Brand, P

    2014-03-01

    The aim of this study was to investigate biological effects and potential health risks due to two different metal-inert-gas (MIG) welding fumes (MIG welding of aluminium and MIG soldering of zinc coated steel) in healthy humans. In a threefold cross-over design study 12 male subjects were exposed to three different exposure scenarios. Exposures were performed under controlled conditions in the Aachener Workplace Simulation Laboratory (AWSL). On three different days the subjects were either exposed to filtered ambient air, to welding fumes from MIG welding of aluminium, or to fumes from MIG soldering of zinc coated materials. Exposure was performed for 6 h and the average fume concentration was 2.5 mg m(-3). Before, directly after, 1 day after, and 7 days after exposure spirometric and impulse oscillometric measurements were performed, exhaled breath condensate (EBC) was collected and blood samples were taken and analyzed for inflammatory markers. During MIG welding of aluminium high ozone concentrations (up to 250 μg m(-3)) were observed, whereas ozone was negligible for MIG soldering. For MIG soldering, concentrations of high-sensitivity CRP (hsCRP) and factor VIII were significantly increased but remained mostly within the normal range. The concentration of neutrophils increased in tendency. For MIG welding of aluminium, the lung function showed significant decreases in Peak Expiratory Flow (PEF) and Mean Expiratory Flow at 75% vital capacity (MEF 75) 7 days after exposure. The concentration of ristocetin cofactor was increased. The observed increase of hsCRP during MIG-soldering can be understood as an indicator for asymptomatic systemic inflammation probably due to zinc (zinc concentration 1.5 mg m(-3)). The change in lung function observed after MIG welding of aluminium may be attributed to ozone inhalation, although the late response (7 days after exposure) is surprising.

  19. The dynamics of droplet formation and detachment in gas metal arc welding

    SciTech Connect

    Johnson, J.A.; Smartt, H.B.; Clark, D.E.; Carlson, N.M.; Watkins, A.D.; Lethcoe, B.J.

    1990-01-01

    Experimental measurements of gas metal arc welding are required for the development and confirmation of models of the process. This paper reports on two experiments that provide information for models of the arc physics and of the weld pool dynamics. The heat transfer efficiency of the spray transfer mode in gas metal arc welding was measured using a calorimetry technique. The efficiency varied from 75 to 85%. A special fixture was used to measure the droplet contribution, which is determined to be between 35 and 45% of the total input energy. A series of experiments was performed at a variety of conditions ranging from globular to spray to streaming transfer. The transfer was observed by taking high-speed movies at 500 to 5000 frames per second of the backlighted droplets. An automatic image analysis system was used to obtain information about the droplets including time between detachments, droplet size, and droplet acceleration. At the boundary between the globular and spray modes, the droplet size varies between small droplets that melt off faster than average, resulting in a smaller electrode extension, and large droplets that melt off slower than average, resulting in an increase in the electrode extension. 5 refs., 4 figs., 2 tabs.

  20. Effect of Post-Weld Heat Treatment on Mechanical and Electrochemical Properties of Gas Metal Arc-Welded 316L (X2CrNiMo 17-13-2) Stainless Steel

    NASA Astrophysics Data System (ADS)

    Muhammad, F.; Ahmad, A.; Farooq, A.; Haider, W.

    2016-10-01

    In the present research work, corrosion behavior of post-weld heat-treated (PWHT) AISI 316L (X2CrNiMo 17-13-2) specimens joined by gas metal arc welding is compared with as-welded samples by using potentiodynamic polarization technique. Welded samples were PWHT at 1323 K for 480 s and quenched. Mechanical properties, corrosion behavior and microstructures of as-welded and PWHT specimens were investigated. Microstructural studies have shown grain size refinement after PWHT. Ultimate tensile strength and yield strength were found maximum for PWHT samples. Bend test have shown that PWHT imparted ductility in welded sample. Fractographic analysis has evidenced ductile behavior for samples. Potentiodynamic polarization test was carried out in a solution composed of 1 M H2SO4 and 1 N NaCl. Corrosion rate of weld region was 127.6 mpy, but after PWHT, it was decreased to 13.12 mpy.

  1. A Phenomenological Model for Tool Wear in Friction Stir Welding of Metal Matrix Composites

    NASA Astrophysics Data System (ADS)

    Prater, Tracie J.; Strauss, Alvin M.; Cook, George E.; Gibson, Brian T.; Cox, Chase D.

    2013-08-01

    Friction stir welding (FSW) of metal matrix composites (MMCs) is advantageous because the solid-state nature of the process precludes formation of deleterious intermetallic phases which accompany melting. FSW of MMCs is complicated by rapid and severe wear of the welding tool, a consequence of contact between the tool and the much harder abrasive reinforcement which gives the workpiece material its enhanced strength. The current article demonstrates that Nunes's rotating plug model of material flow in FSW, which has been successfully applied in many other contexts, can also help us understand wear in FSW of MMCs. An equation for predicting the amount of wear in this application is developed and compared with experimental data. This phenomenological model explains the relationship between wear and FSW process parameters documented in previous studies.

  2. 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.

  3. Friction Stir Welding of Metal Matrix Composites for use in aerospace structures

    NASA Astrophysics Data System (ADS)

    Prater, Tracie

    2014-01-01

    Friction Stir Welding (FSW) is a relatively nascent solid state joining technique developed at The Welding Institute (TWI) in 1991. The process was first used at NASA to weld the super lightweight external tank for the Space Shuttle. Today FSW is used to join structural components of the Delta IV, Atlas V, and Falcon IX rockets as well as the Orion Crew Exploration Vehicle. A current focus of FSW research is to extend the process to new materials which are difficult to weld using conventional fusion techniques. Metal Matrix Composites (MMCs) consist of a metal alloy reinforced with ceramics and have a very high strength to weight ratio, a property which makes them attractive for use in aerospace and defense applications. MMCs have found use in the space shuttle orbiter's structural tubing, the Hubble Space Telescope's antenna mast, control surfaces and propulsion systems for aircraft, and tank armors. The size of MMC components is severely limited by difficulties encountered in joining these materials using fusion welding. Melting of the material results in formation of an undesirable phase (formed when molten Aluminum reacts with the reinforcement) which leaves a strength depleted region along the joint line. Since FSW occurs below the melting point of the workpiece material, this deleterious phase is absent in FSW-ed MMC joints. FSW of MMCs is, however, plagued by rapid wear of the welding tool, a consequence of the large discrepancy in hardness between the steel tool and the reinforcement material. This work characterizes the effect of process parameters (spindle speed, traverse rate, and length of joint) on the wear process. Based on the results of these experiments, a phenomenological model of the wear process was constructed based on the rotating plug model for FSW. The effectiveness of harder tool materials (such as Tungsten Carbide, high speed steel, and tools with diamond coatings) to combat abrasive wear is explored. In-process force, torque, and

  4. Characterization of Service Induced Flaws on the Far Side of Austenitic Welds Using Phased Array Technology

    SciTech Connect

    Anderson, Michael T.; Cumblidge, Stephen E.

    2004-01-01

    Conventional ultrasonic testing methods continue to exhibit problems for applications involving coarse-grained structures. Pacific Northwest National Laboratory is evaluating the capabilities and limitations of phased array (PA) technology to detect service-type flaws in these coarse-grained materials. The work is being sponsored by the U.S. Nuclear Regulatory Commission, Office of Research. Work to determine detection capabilities through welds with varied grain structures is being explored to provide a better understanding of the acoustic properties of these welded structures. Piping specimens with welds fabricated in vertical and horizontal positions to simulate field conditions have been studied. The insights gained from the austenitic piping will be applied to dissimilar metal weld configurations, corrosion resistant clad piping and cast stainless steels. This paper presents results for using PA ultrasonic technology to determine the effectiveness of detecting and accurately characterizing flaws on the far-side of austenitic piping welds.

  5. FORMATION MECHANISM FOR THE NANOSCALE AMORPHOUS INTERFACE IN PULSE-WELDED AL/FE BIMETALLIC SYSTEM

    SciTech Connect

    Li, Jingjing; Yu, Qian; Zhang, Zijiao; Xu, Wei; Sun, Xin

    2016-05-20

    Pulse or impact welding traditionally has been referred to as “solid-state” welding. By integrating advanced interface characterizations and diffusion calculations, we report that the nanoscale amorphous interface in the pulse-welded Al/Fe bimetallic system is formed by rapid heating and melting of a thin Al layer at the interface, diffusion of iron atoms in the liquid aluminum, and subsequent rapid quenching with diffused iron atoms in solution. This finding challenges the commonly held belief regarding the solid-state nature of the impact-based welding process for dissimilar metals. Elongated ultra-fine grains with high dislocation density and ultra-fine equiaxed grains also are observed in the weld interface vicinity on the steel and aluminum sides, respectively, which further confirms that melting and the resulted recrystallization occurred on the aluminum side of the interface.

  6. Formation mechanism for the nanoscale amorphous interface in pulse-welded Al/Fe bimetallic systems

    NASA Astrophysics Data System (ADS)

    Li, Jingjing; Yu, Qian; Zhang, Zijiao; Xu, Wei; Sun, Xin

    2016-05-01

    Pulse or impact welding traditionally has been referred to as "solid-state" welding. By integrating advanced interface characterizations and diffusion calculations, we report that the nanoscale amorphous interface in the pulse-welded Al/Fe bimetallic system is formed by rapid heating and melting of a thin Al layer at the interface, diffusion of iron atoms in the liquid aluminum, and subsequent rapid quenching with diffused iron atoms in solution. This finding challenges the commonly held belief regarding the solid-state nature of the impact-based welding process for dissimilar metals. Elongated ultra-fine grains with high dislocation density and ultra-fine equiaxed grains also are observed in the weld interface vicinity on the steel and aluminum sides, respectively, which further confirms that melting and the subsequent recrystallization occurred on the aluminum side of the interface.

  7. Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur C., Jr.

    2008-01-01

    Friction stir welding (FSW) is a solid state welding process invented in 1991 at The Welding Institute in the United Kingdom. A weld is made in the FSW process by translating a rotating pin along a weld seam so as to stir the sides of the seam together. FSW avoids deleterious effects inherent in melting and promises to be an important welding process for any industries where welds of optimal quality are demanded. This article provides an introduction to the FSW process. The chief concern is the physical effect of the tool on the weld metal: how weld seam bonding takes place, what kind of weld structure is generated, potential problems, possible defects for example, and implications for process parameters and tool design. Weld properties are determined by structure, and the structure of friction stir welds is determined by the weld metal flow field in the vicinity of the weld tool. Metal flow in the vicinity of the weld tool is explained through a simple kinematic flow model that decomposes the flow field into three basic component flows: a uniform translation, a rotating solid cylinder, and a ring vortex encircling the tool. The flow components, superposed to construct the flow model, can be related to particular aspects of weld process parameters and tool design; they provide a bridge to an understanding of a complex-at-first-glance weld structure. Torques and forces are also discussed. Some simple mathematical models of structural aspects, torques, and forces are included.

  8. Gas Metal Arc Welding and Flux-Cored Arc Welding. Third Edition. Teacher Edition [and] Student Edition [and] Student Workbook.

    ERIC Educational Resources Information Center

    Knapp, John; Harper, Eddie

    This packet, containing a teacher's edition, a student edition, and a student workbook, introduces students to high deposition welding and processes for "shielding" a weld. In addition to general information, the teacher edition consists of introductory pages and teacher pages, as well as unit information that corresponds to the…

  9. The effects of the coupling of titanium implants and dissimilar metal abutments on osteoblast differentiation in vitro.

    PubMed

    Taylor, J C; Anderson, G I; Sutow, E J; Driscoll, C F; Mackey, D C

    1999-01-01

    This study evaluated the effect of titanium endosseous dental implants coupled to dissimilar materials on the capacity of preosteoblasts in bone marrow culture to differentiate, to form alkaline phosphatase-positive colonies, and to mineralize. Ten UCLA abutments were cast in each of 4 alloys: Type III gold, ceramometal gold, commercially pure grade I titanium, and titanium-aluminum-vanadium (Ti-6Al-4V); 10 ceramic abutments and 30 sterile Brånemark System implants were also used. Five abutments of each material and 5 implants were incubated individually in rat bone marrow culture, as were 5 of each abutment attached to an implant; bone marrow cultures not containing test samples were used as controls. Following 17 days of culture, the solution potentials of individual abutments (except ceramic), the implant, and the implant-abutment couples were measured in the test medium. One dish of each group of 5 was then stained for bone nodule mineralization; the remainder were quantified by area for alkaline phosphatase staining. Statistical analysis of measured in vitro potentials showed that the uncoupled samples formed 2 groups, and coupled samples formed 3 groups. Analysis of variance for alkaline phosphatase-positive area values showed no significant differences between coupled or uncoupled groups and the control. Normal cell differentiation and morphology as well as a lack of zones of inhibition, were observed. Bone nodule mineralization was evident in all groups. It was concluded that the presence of these commonly used implant abutment biomaterials coupled to titanium endosseous dental implants had no adverse effects on the in vitro capacity of preosteoblasts in marrow to differentiate and to form mineralized bone nodules, despite measured differences in solution potentials.

  10. A self-organizing fuzzy control approach to arc sensor for weld joint tracking in gas metal arc welding of butt joints

    SciTech Connect

    Na, S.J. ); Kim, J.W.

    1993-02-01

    For the artificial intelligence (AI) approach to automatic control, the fuzzy rule-based control schemes have been successfully applied to the control of complex processes. The arc welding process is one of the processes due to the fact that it possesses complex and nonlinear characteristics such as a moving distributed heat source, a current path and metal transfer. One possible solution to the design of an effective controller suitable for such a process is to use the fuzzy control scheme. The fuzzy rule-based control can easily realize the heuristic rules obtained from human experiences that cannot be expressed in mathematical form. In this study, an arc sensor, which utilizes the electrical signal obtained from the welding arc itself, was developed for CO[sub 2] gas metal arc welding of butt joints using the fuzzy set theory. A simple fuzzy controller without any adaptation was implemented for the weld joint tracking. A set of fixed rules, which was designed based upon the experiments, and a self-organizing fuzzy controller, which could improve the control rules automatically, were examined. Through a series of experiments, the performance and learning action of the proposed self-organizing fuzzy controller were assessed.

  11. Introduction to Welding.

    ERIC Educational Resources Information Center

    Fortney, Clarence; Gregory, Mike

    This curriculum guide provides six units of instruction on basic welding. Addressed in the individual units of instruction are the following topics: employment opportunities for welders, welding safety and first aid, welding tools and equipment, basic metals and metallurgy, basic math and measuring, and procedures for applying for a welding job.…

  12. Persistence of deposited metals in the lungs after stainless steel and mild steel welding fume inhalation in rats.

    PubMed

    Antonini, James M; Roberts, Jenny R; Stone, Samuel; Chen, Bean T; Schwegler-Berry, Diane; Chapman, Rebecca; Zeidler-Erdely, Patti C; Andrews, Ronnee N; Frazer, David G

    2011-05-01

    Welding generates complex metal fumes that vary in composition. The objectives of this study were to compare the persistence of deposited metals and the inflammatory potential of stainless and mild steel welding fumes, the two most common fumes used in US industry. Sprague-Dawley rats were exposed to 40 mg/m(3) of stainless or mild steel welding fumes for 3 h/day for 3 days. Controls were exposed to filtered air. Generated fume was collected, and particle size and elemental composition were determined. Bronchoalveolar lavage was done on days 0, 8, 21, and 42 after the last exposure to assess lung injury/inflammation and to recover lung phagocytes. Non-lavaged lung samples were analyzed for total and specific metal content as a measure of metal persistence. Both welding fumes were similar in particle morphology and size. Following was the chemical composition of the fumes-stainless steel: 57% Fe, 20% Cr, 14% Mn, and 9% Ni; mild steel: 83% Fe and 15% Mn. There was no effect of the mild steel fume on lung injury/inflammation at any time point compared to air control. Lung injury and inflammation were significantly elevated at 8 and 21 days after exposure to the stainless steel fume compared to control. Stainless steel fume exposure was associated with greater recovery of welding fume-laden macrophages from the lungs at all time points compared with the mild steel fume. A higher concentration of total metal was observed in the lungs of the stainless steel welding fume at all time points compared with the mild steel fume. The specific metals present in the two fumes were cleared from the lungs at different rates. The potentially more toxic metals (e.g., Mn, Cr) present in the stainless steel fume were cleared from the lungs more quickly than Fe, likely increasing their translocation from the respiratory system to other organs.

  13. 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.

  14. Toenail as Non-invasive Biomarker in Metal Toxicity Measurement of Welding Fumes Exposure - A Review

    NASA Astrophysics Data System (ADS)

    Bakri, S. F. Z.; Hariri, A.; Ma'arop, N. F.; Hussin, N. S. A. W.

    2017-01-01

    Workers are exposed to a variety of heavy metal pollutants that are released into the environment as a consequence of workplace activities. This chemical pollutants are incorporated into the human by varies of routes entry and can then be stored and distributed in different tissues, consequently have a potential to lead an adverse health effects and/or diseases. As to minimize the impact, a control measures should be taken to avoid these effects and human biological marker is a very effective tool in the assessment of occupational exposure and potential related risk as the results is normally accurate and reproducible. Toenail is the ideal matrix for most common heavy metals due to its reliability and practicality compared to other biological samples as well as it is a non-invasive and this appears as a huge advantage of toenail as a biomarker. This paper reviews studies that measure the heavy metals concentration in toenail as non-invasive matrix which later may adapt in the investigation of metal fume emitted from welding process. The development of new methodology and modern analytical techniques has allowed the use of toenail as non-invasive approach. The presence of a heavy metal in this matrix reflects an exposure but the correlations between heavy metal levels in the toenail must be established to ensure that these levels are related to the total body burden. These findings suggest that further studies on interactions of these heavy metals in metal fumes utilizing toenail biomarker endpoints are highly warranted especially among welders.

  15. Potential for EMU Fabric Damage by Electron Beam and Molten Metal During Space Welding for the International Space Welding Experiment

    NASA Technical Reports Server (NTRS)

    Fragomeni, James M.

    1998-01-01

    As a consequence of preparations concerning the International Space Welding Experiment (ISWE), studies were performed to better understand the effect of molten metal contact and electron beam impingement with various fabrics for space suit applications. The question arose as to what would occur if the electron beam from the Ukrainian Universal Hand Tool (UHT) designed for welding in space were to impinge upon a piece of Nextel AF-62 ceramic cloth designed to withstand temperatures up to 1427 C. The expectation was that the electron beam would lay down a static charge pattern with no damage to the ceramic fabric. The electron beam is capable of spraying the fabric with enough negative charge to repel further electrons from the fabric before significant heating occurs. The static charge pattern would deflect any further charge accumulation except for a small initial amount of leakage to the grounded surface of the welder. However, when studies were made of the effect of the electron beam on the insulating ceramic fabric it was surprisingly found that the electron beam did indeed burn through the ceramic fabric. It was also found that the shorter electron beam standoff distances had longer burnthrough times than did some greater electron beam standoff distances. A possible explanation for the longer burnthrough times for the small electron beam standoff distance would be outgassing of the fabric which caused the electron beam hand-tool to cycle on and off to provide some protection for the cathodes. The electron beam hand tool was observed to cycle off at the short standoff distance of two inches likely due to vapors being outgassed. During the electron beam welding process there is an electron leakage, or current leakage, flow from the fabric. A static charge pattern is initially laid down by the electron beam current flow. The static charge makes up the current leakage flow which initially slightly heats up the fabric. The initially laid down surface charge leaks a

  16. 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.

  17. Study of metal transfer in CO2 laser+GMAW-P hybrid welding using argon-helium mixtures

    NASA Astrophysics Data System (ADS)

    Zhang, Wang; Hua, Xueming; Liao, Wei; Li, Fang; Wang, Min

    2014-03-01

    The metal transfer in CO2 Laser+GMAW-P hybrid welding by using argon-helium mixtures was investigated and the effect of the laser on the mental transfer is discussed. A 650 nm laser, in conjunction with the shadow graph technique, is used to observe the metal transfer process. In order to analyze the heat input to the droplet and the droplet internal current line distribution. An optical emission spectroscopy system was employed to estimate default parameter and optimized plasma temperature, electron number densities distribution. The results indicate that the CO2 plasma plume have a significant impact to the electrode melting, droplet formation, detachment, impingement onto the workpiece and weld morphology. Since the current distribution direction flow changes to the keyhole, to obtain a metal transfer mode of one droplet per pulse, the welding parameters should be adjusted to a higher pulse time (TP) and a lower voltage.

  18. Method for Assessing Grain Boundary Density in High-Strength, High-Toughness Ferritic Weld Metal

    NASA Astrophysics Data System (ADS)

    Lei, Xuanwei; Huang, Jihua; Chen, Shuhai; Zhao, Xingke

    2017-01-01

    A method for measuring peak values on the maxlength-area fraction curve and the perimeter-area fraction curve with morphological photos using Image Pro Plus 6.0 Soft for assessing grain boundary density in high-strength, high-toughness ferritic weld metals is developed. Results show the sizes of the peak values have a tough relationship with grain boundary densities in that a larger peak value stands for a larger grain boundary density. As ferrite transforms into a certain orientation relationship, this semi-empirical method provides handy references for judging the sizes of effective grain boundary densities.

  19. Localized Corrosion Currents from Graphite/Aluminum and Welded SiC/Al Metal Matrix Composites.

    DTIC Science & Technology

    1985-02-28

    the corrosion rate in the absence of flaws might be improved by additions of poisions to the fiber to retard the oxygen reduction reaction on graphite...weidment 8 Al4C3 + 12H 20 + 4Al(OH) 3 + 3CH 4 This reaction, along with other metallurgical variations caused by the heat of welding, leads to...efficient cathodic sites along anodic corrosion paths and can lead to exfoliation in 6061 Al when the inter- metallics are present in an appropriate

  20. Design for low-cost gas metal arc weld-based aluminum 3-D printing

    NASA Astrophysics Data System (ADS)

    Haselhuhn, Amberlee S.

    Additive manufacturing, commonly known as 3-D printing, has the potential to change the state of manufacturing across the globe. Parts are made, or printed, layer by layer using only the materials required to form the part, resulting in much less waste than traditional manufacturing methods. Additive manufacturing has been implemented in a wide variety of industries including aerospace, medical, consumer products, and fashion, using metals, ceramics, polymers, composites, and even organic tissues. However, traditional 3-D printing technologies, particularly those used to print metals, can be prohibitively expensive for small enterprises and the average consumer. A low-cost open-source metal 3-D printer has been developed based upon gas metal arc weld (GMAW) technology. Using this technology, substrate release mechanisms have been developed, allowing the user to remove a printed metal part from a metal substrate by hand. The mechanical and microstructural properties of commercially available weld alloys were characterized and used to guide alloy development in 4000 series aluminum-silicon alloys. Wedge casting experiments were performed to screen magnesium, strontium, and titanium boride alloying additions in hypoeutectic aluminum-silicon alloys for their properties and the ease with which they could be printed. Finally, the top performing alloys, which were approximately 11.6% Si modified with strontium and titanium boride were cast, extruded, and drawn into wire. These wires were printed and the mechanical and microstructural properties were compared with those of commercially available alloys. This work resulted in an easier-to-print aluminum-silicon-strontium alloy that exhibited lower porosity, equivalent yield and tensile strengths, yet nearly twice the ductility compared to commercial alloys.

  1. Influence of chromium on the mechanical properties and microstructure of weld metal from a high-strength SMA electrode

    SciTech Connect

    Surian, E.; Trotti, J. ); Cassanelli, A. ); Vedia, L.A. De )

    1994-03-01

    In the present work, the influence of Cr on mechanical properties and microstructure of weld metal from a high-strength SMA electrode is analyzed by considering 12 experimental low-alloy low-hydrogen iron powder AWS E10018, E11018, E12018-M type covered electrodes. These electrodes were manufactured to obtain in the weld deposits Cr contents ranging from 0 to 1.8%, with two different Mn levels for each Cr content, maintaining the amount of other elements at a fixed value. All-weld-metal specimens and production type single V-groove welds were mechanically tested in the as-welded and stress-relieved conditions, and a metallographic study was conducted. Chromium was found to be deleterious to toughness with only a minor influence due to Mn variations. A postweld heat treatment led in all cases to a reduction of toughness. Increasing Cr content in the welds produced a higher proportion of acicular ferrite and a general refinement of the microstructure.

  2. Effects of Different Filler Metals on the Mechanical Behaviors of GTA Welded AA7A52(T6)

    NASA Astrophysics Data System (ADS)

    Shu, Fengyuan; Lv, Yaohui; Liu, Yuxin; Lin, Jianjun; Sun, Zhe; Xu, Binshi; He, Peng

    2014-06-01

    ER4043, ER5356, and AA7A52 on behalf of the Al-Si, Al-Mg, and Al-Zn-Mg-based welding material, respectively, were chosen as the filler metal to weld AA7A52(T6) plates by GTAW. The variance in mechanical performances of the joints caused by the various filler materials was investigated with reference to the SEM and EDS test results for the weld seam and the fracture surface. Failure was found in the seam for all the welded joints. With regard to the joint obtained with ER4043 welding wire, the total elongation was limited by the brittle intergranular compound Mg2Si of which Mg was introduced by convection mass transfer. As for the other two welds, the content ratio of Zn and Mg was found to play the dominant role in deciding the mechanical properties of the intergranular Mg-Zn compounds which were responsible for the tensile behavior of the joints. The content ratio (wt.%) of beyond 2:1 gave birth to the strengthening phase MgZn2 leading to a ductile fracture. Cr in the seam obtained with AA7A52 filler metal was found to enhance the strength of the joint through isolated particles.

  3. Evolution of weld metals nanostructure and properties under irradiation and recovery annealing of VVER-type reactors

    NASA Astrophysics Data System (ADS)

    Gurovich, B.; Kuleshova, E.; Shtrombakh, Ya.; Fedotova, S.; Zabusov, O.; Prikhodko, K.; Zhurko, D.

    2013-03-01

    The results of VVER-440 steel Sv-10KhMFT and VVER-1000 steel SV-10KhGNMAA investigations by transmission electron microscopy, scanning electron microscopy, Auger-electron spectroscopy and mechanical tests are presented in this paper. The both types of weld metals with different content of impurities and alloying elements were studied after irradiations to fast neutron (E > 0.5 MeV) fluences in the wide range below and beyond the design values, after recovery annealing procedures and after re-irradiation following the annealing. The distinctive features of embrittlement kinetics of VVER-440 and VVER-1000 RPV weld metals conditioned by their chemical composition differences were investigated. It is shown that the main contribution into radiation strengthening within the design fluence can be attributed to radiation-induced precipitates, on reaching the design or beyond design values of fast neutron fluencies the main contribution into VVER-440 welds strengthening is made by radiation-induced dislocation loops, and in case of VVER-1000 welds - radiation-induced precipitates and grain-boundary phosphorous segregations. Recovery annealing of VVER-440 welds at 475 °C during 100 h causes irradiation-induced defects disappearance, transformation of copper enriched precipitates into bigger copper-rich precipitates with lower number density and leads to almost full recovery of mechanical properties followed by comparatively slow re-embrittlement rate. The recovery annealing temperature of VVER-1000 welds was higher - 565 °C during 100 h - to avoid temper brittleness. The annealing of VVER-1000 welds leads to almost full recovery of mechanical properties due to irradiation-induced defects disappearance and decrease in precipitates number density and grain-boundary segregation of phosphorus. The re-embrittlement rate of VVER-1000 weld during subsequent re-irradiation is at least not higher than the initial rate.

  4. Relation between biomarkers in exhaled breath condensate and internal exposure to metals from gas metal arc welding.

    PubMed

    Hoffmeyer, Frank; Raulf-Heimsoth, Monika; Weiss, Tobias; Lehnert, Martin; Gawrych, Katarzyna; Kendzia, Benjamin; Harth, Volker; Henry, Jana; Pesch, Beate; Brüning, Thomas

    2012-06-01

    Concerning possible harmful components of welding fumes, besides gases and quantitative aspects of the respirable welding fumes, particle-inherent metal toxicity has to be considered.The objective of this study was to investigate the effect markers leukotriene B4 (LTB4),prostaglandin E2 (PGE2) and 8-isoprostane (8-Iso PGF2α) as well as the acid–base balance(pH) in exhaled breath condensate (EBC) of 43 full-time gas metal arc welders (20 smokers) in relation to welding fume exposure. We observed different patterns of iron, chromium and nickel in respirable welding fumes and EBC. Welders with undetectable chromium in EBC(group A, n = 24) presented high iron and nickel concentrations. In this group, higher 8-isoPGF2α and LTB4 concentrations could be revealed compared to welders with detectable chromium and low levels of both iron and nickel in EBC (group B): 8-iso PGF2α443.3 pg mL−1 versus 247.2 pg mL−1; p = 0.001 and LTB4 30.5 pg mL−1 versus 17.3 pgmL−1; p = 0.016. EBC-pH was more acid in samples of group B (6.52 versus 6.82; p = 0.011).Overall, effect markers in welders were associated with iron concentrations in EBC according to smoking habits--non-smokers/smokers: LTB4 (rs = 0.48; p = 0.02/rs = 0.21; p = 0.37),PGE2 (rs = 0.15; p = 0.59/rs = 0.47; p = 0.07), 8-iso PGF2α (rs = 0.18; p = 0.54/rs = 0.59;p = 0.06). Sampling of EBC in occupational research provides a matrix for the simultaneous monitoring of metal exposure and effects on target level. Our results suggest irritative effects in the airways of healthy welders. Further studies are necessary to assess whether these individual results might be used to identify welders at elevated risk for developing a respiratory disease.

  5. In-flight behavior of dissimilar co-injected particles in the spraying of metal-ceramic functionally gradient materials

    SciTech Connect

    Fincke, J.R.; Swank, W.D.; Haggard, D.C.

    1997-12-31

    In the spraying of functionally gradient coatings the particle ensemble delivered to the substrate can vary from a relatively low melting point metallic particle to a significantly higher melting point ceramic particle. At various stages in the spray process the particle ensemble can be either predominantly metallic, ceramic, or an intermediate combination. For co-injected particles the mixtures do not behave as a simple linear superposition of the spray patterns of the individual particle types. The particle temperature, velocity, size distributions, and pattern characteristics of the resulting spray fields is examined for all ceramic particle sprays (ZrO{sub 2}), all metallic particle sprays (NiCrAlY), and for a 1:1 mixture. The major particle-particle interaction occurs in the injector itself and results in a modified spray pattern which is different from that of either material sprayed alone. The particle velocity distributions generally exhibit a bimodal nature which is dependent on the size and density of the injected particles.

  6. Sensitization behaviour of modified 316N and 316L stainless steel weld metals after complex annealing and stress relieving cycles

    NASA Astrophysics Data System (ADS)

    Parvathavarthini, N.; Dayal, R. K.; Khatak, H. S.; Shankar, V.; Shanmugam, V.

    2006-09-01

    Sensitization behaviour of austenitic stainless steel weld metals prepared using indigenously developed modified 316N (C = 0.05%; N = 0.12%) and 316L (C = 0.02%; N = 0.07%) electrodes was studied. Detailed optical and scanning electron microscopic examination was carried out to understand the microstructural changes occurring in the weld metal during isothermal exposure at various temperatures ranging from 500 °C to 850 °C (773-1123 K). Based on these studies the mechanism of sensitization in the austenite-ferrite weld metal has been explained. Time-temperature-sensitization (TTS) diagrams were established using ASTM A262 Practice E test. From the TTS diagrams, critical cooling rate (CCR) above which there is no risk of sensitization was calculated for both materials. The heating/cooling rates to be followed for avoiding sensitization during heat treatment cycles consisting of solution-annealing and stress-relieving in fabrication of welded components of AISI 316LN stainless steel (SS) were estimated taking into account the soaking time and the number of times the component undergoes thermal excursions in the sensitization regime. The results were validated by performing controlled heating and cooling heat treatment trials on welded specimens.

  7. Coexistence of dissimilar metals after conversion of intertrochanteric osteotomy to total hip arthroplasty. 18 patients followed for 5-20 years after conversion.

    PubMed

    Papapolychroniou, T; Vafiadis, J; Zacharopoulos, K; Michelinakis, E

    1997-10-01

    Extraction of an internal fixation device during the conversion of a failed intertrochanteric osteotomy to a total hip arthroplasty (THR) may lead to excessive trauma of the femoral shaft. In an attempt to bypass this risk, we performed THR leaving the old osteosynthetic material (straight plates and screws) in 10 of 48 patients operated on during the last 20 years. In another 8 patients, most of the osteosynthetic material was removed, but screw fragments were left in the canal. Insertion of the cement and the stem was unexpectedly easy in all 18 cases. After a mean follow-up of 10 (5-20) years there were no clinical problems. Radiographically, there were no signs of loosening, with only an occasional slight osteoporosis of the greater trochanter. Although theoretically the coexistence of different metals in the shaft should be avoided, in practice it does not appear to create a problem for patients. This may be attributed to insulation of the dissimilar materials by the cement. In conclusion, in cases where removal of the osteosynthetic device is expected to lead to severe trauma of the femur, our findings indicate that it is no disadvantage to perform the THR leaving the internal fixation material in place.

  8. Effect of Pin Tool Shape on Metal Flow During Friction Stir Welding

    NASA Technical Reports Server (NTRS)

    McClure, J. C.; Coronado, E.; Aloor, S.; Nowak, B.; Murr, L. M.; Nunes, Arthur C., Jr.; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    It has been shown that metal moves behind the rotating Friction Stir Pin Tool in two separate currents or streams. One current, mostly on the advancing side, enters a zone of material that rotates with the pin tool for one or more revolutions and eventually is abandoned behind the pin tool in crescent-shaped pieces. The other current, largely on the retreating side of the pin tool is moved by a wiping process to the back of the pin tool and fills in between the pieces of the rotational zone that have been shed by the rotational zone. This process was studied by using a faying surface copper trace to clarify the metal flow. Welds were made with pin tools having various thread pitches. Decreasing the thread pitch causes the large scale top-to-bottorn flow to break up into multiple vortices along the pin and an unthreaded pin tool provides insufficient vertical motion for there to be a stable rotational zone and flow of material via the rotational zone is not possible leading to porosity on the advancing side of the weld.

  9. Effect of Hyperbaric Chamber Gas on Transformation Texture of the API-X70 Pipeline Weld Metal

    NASA Astrophysics Data System (ADS)

    Azar, Amin S.; Østby, Erling; Akselsen, Odd M.

    2012-09-01

    The development of the texture components in the X70 weld metal under several shielding environments was investigated using the electron-backscattered diffraction (EBSD) and orientation imaging microscopy (OIM) techniques. A new method for assigning the reference direction (RD), transverse direction (TD), and normal direction (ND) was introduced based on the morphological orientation of the grains. The analyses showed that different shielding gases affect the weld metal texture and microstructure. The shielding environment with pure argon shows the highest orientational pole density values and dominant acicular ferrite microstructure. It was observed that the distribution of misorientation angle and special coincidence site lattice (CSL) grain boundaries play significant roles in determining the tensile characteristics of the weld samples. Moreover, the bainite lattice orientation was found dependent on the directional heat flow unlike the other detected constituents.

  10. Recent developments in Micro Friction Stir Welding: A review

    NASA Astrophysics Data System (ADS)

    Sithole, Keydon; Vasudeva Rao, Veeredhi

    2016-02-01

    The advent of friction stir welding (FSW) in 1991 has been evolutionary in the joining of metals and related materials. Friction stir welding has enabled the joining of metals that could not be joined by other welding processes. Research has shown that dissimilar materials with very different properties, plastics, composites and even wood can be joined by FSW. Recent activities in the application of FSW has seen the development of micro friction stir welding (μFSW), which is the FSW of very thin sections of thickness 1000 μm (1 mm) or less. Micro friction stir welding further extends the applications of FSW to areas such as copper electrical contacts, tailor-welded blanks, wood. Though μFSW is relatively new development significant work has been done to date with interesting research findings being reported. This paper aims to review developments in μFSW to date. The focus of the paper will be on problems peculiar to μFSW due to downscaling to the micro scale and other practical considerations.

  11. Welding fumes from stainless steel gas metal arc processes contain multiple manganese chemical species.

    PubMed

    Keane, Michael; Stone, Samuel; Chen, Bean

    2010-05-01

    Fumes from a group of gas metal arc welding (GMAW) processes used on stainless steel were generated using three different metal transfer modes and four different shield gases. The objective was to identify and measure manganese (Mn) species in the fumes, and identify processes that are minimal generators of Mn species. The robotic welding system was operated in short-circuit (SC) mode (Ar/CO2 and He/Ar), axial spray (AXS) mode (Ar/O2 and Ar/CO2), and pulsed axial-spray (PAXS) mode (Ar/O2). The fumes were analyzed for Mn by a sequential extraction process followed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analysis, and by X-ray diffraction (XRD). Total elemental Mn, iron (Fe), chromium (Cr) and nickel (Ni) were separately measured after aqua regia digestion and ICP-AES analysis. Soluble Mn2+, Fe2+, Fe3+, and Ni2+ in a simple biological buffer (phosphate-buffered saline) were determined at pH 7.2 and 5.0 after 2 h incubation at 37 C by ion chromatography. Results indicate that Mn was present in soluble form, acid-soluble form, and acid-soluble form after reduction by hydroxylamine, which represents soluble Mn0 and Mn2+ compounds, other Mn2+ compounds, and (Mn3+ and Mn4+) compounds, respectively. The dominant fraction was the acid-soluble Mn2+ fraction, but results varied with the process and shield gas. Soluble Mn mass percent in the fume ranged from 0.2 to 0.9%, acid-soluble Mn2+ compounds ranged from 2.6 to 9.3%, and acid plus reducing agent-soluble (Mn3+ and Mn4+) compounds ranged from 0.6 to 5.1%. Total Mn composition ranged from 7 to 15%. XRD results showed fumes had a crystalline content of 90-99% Fe3O4, and showed evidence of multiple Mn oxides, but overlaps and weak signals limited identification. Small amounts of the Mn2+ in the fume (<0.01 to ≈ 1% or <0.1 to ≈ 10 microg ml(-1)) and Ni2+ (<0.01 to ≈ 0.2% or <0.1 to ≈ 2 mg ml(-1)) ions were found in biological buffer media, but amounts were highly dependent on pH and the

  12. Transverse-Weld Tensile Properties of a New Al-4Cu-2Si Alloy as Filler Metal

    NASA Astrophysics Data System (ADS)

    Sampath, K.

    2009-12-01

    AA2195, an Al-Cu-Li alloy in the T8P4 age-hardened condition, is a candidate aluminum armor for future combat vehicles, as this material offers higher static strength and ballistic protection than current aluminum armor alloys. However, certification of AA2195 alloy for armor applications requires initial qualification based on the ballistic performance of welded panels in the as-welded condition. Currently, combat vehicle manufacturers primarily use gas metal arc welding (GMAW) process to meet their fabrication needs. Unfortunately, a matching GMAW consumable electrode is currently not commercially available to allow effective joining of AA2195 alloy. This initial effort focused on an innovative, low-cost, low-risk approach to identify an alloy composition suitable for effective joining of AA2195 alloy, and evaluated transverse-weld tensile properties of groove butt joints produced using the identified alloy. Selected commercial off-the-shelf (COTS) aluminum alloy filler wires were twisted to form candidate twisted filler rods. Representative test weldments were produced using AA2195 alloy, candidate twisted filler rods and gas tungsten arc welding (GTAW) process. Selected GTA weldments produced using Al-4wt.%Cu-2wt.%Si alloy as filler metal consistently provided transverse-weld tensile properties in excess of 275 MPa (40 ksi) UTS and 8% El (over 25 mm gage length), thereby showing potential for acceptable ballistic performance of as-welded panels. Further developmental work is required to evaluate in detail GMAW consumable wire electrodes based on the Al-Cu-Si system containing 4.2-5.0 wt.% Cu and 1.6-2.0 wt.% Si.

  13. Shielded Metal Arc Welding and Carbon Arc Cutting--Air. Teacher Edition [and] Student Edition [and] Student Workbook. Third Edition.

    ERIC Educational Resources Information Center

    Harper, Eddie; Knapp, John

    This document contains the teacher and student texts and student workbook for a secondary-level course in shielded metal arc welding (SMAW) and carbon arc cutting that consists of units on the following topics: SMAW safety; SMAW equipment, applications, and techniques; hardfacing; and carbon arc cutting--air. The teacher edition includes the…

  14. Effect of Ti-containing inclusions on the nucleation of acicular ferrite and mechanical properties of multipass weld metals.

    PubMed

    Fattahi, M; Nabhani, N; Hosseini, M; Arabian, N; Rahimi, E

    2013-02-01

    In the present study, the influence of Ti-containing inclusions on the development of acicular ferrite microstructure and mechanical properties in the multipass weld metals has been studied. Shielded metal arc weld deposits were prepared by varying titanium content in the range of 0.003-0.021%. The variation in the titanium content was obtained by the addition of different amounts of titanium oxide nanoparticles to the electrode coating. The dispersion of titanium oxide nanoparticles, composition of inclusions, microstructural analysis, tensile properties and Charpy impact toughness were evaluated. As the amount of Ti-containing inclusions in the weld metal was increased, the microstructure of the weld metal was changed from the grain boundary allotriomorphic ferrite structure to acicular ferrite with the intragranular nucleation of ferrite on the Ti-containing inclusions, and the mechanical properties were improved. This improvement is attributable to the increased percentage of acicular ferrite due to the uniform dispersion of Ti-containing inclusions and the pinning force of oxide nanoparticles against the growth of allotriomorphic ferrite and Widmanstätten ferrite from the austenite grain boundaries.

  15. 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.

  16. 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.

  17. Automatic welding comes of age. [Offshore

    SciTech Connect

    Turner, D.L. Jr.

    1981-07-01

    Automatic pipe welding systems today fall into three main categories: gas metal arc welding, gas-tungsten arc welding, and flash-butt welding. The first automatic welding devices used offshore were the CRC and H.C. Price systems. Both use gas metal arc welding with a consumable steel filler wire. The recently developed McDermott flash-butt welding system is described. (DLC)

  18. Investigation on the Interface Morphologies of Explosive Welding of Inconel 625 to Steel A516 Plates

    SciTech Connect

    Mousavi, S. A. A. Akbari; Zareie, H. R.

    2011-01-17

    The purpose of this study is to produce composite plates by explosive cladding process. This is a process in which the controlled energy of explosives is used to create a metallic bond between two similar or dissimilar materials. The welding conditions were tailored through parallel geometry route with different operational parameters. In this investigation, a two-pronged study was adopted to establish the conditions required for producing successful solid state welding: (a) Analytical calculations to determine the weldability domain or welding window; (b) Metallurgical investigations of explosive welding experiments carried out under different explosive ratios to produce both wavy and straight interfaces. The analytical calculations confirm the experimental results. Optical microscopy studies show that a transition from a smooth to wavy interface occurs with an increase in explosive ratio. SEM studies show that the interface was outlined by characteristic sharp transition between two materials.

  19. Behavior of Ti-5Al-2.5Sn ELI titanium alloy sheet parent and weld metal in the presence of cracks at 20 K

    NASA Technical Reports Server (NTRS)

    Sullivan, T. L.

    1971-01-01

    Through- and surface-cracked specimens of two thicknesses were tested in uniaxial tension. Surface-cracked specimens were generally found to be stronger than through-cracked specimens with the same crack length. Apparent surface-crack fracture toughness calculated using the Anderson modified Irwin equation remained relatively constant for cracks as deep as 90 percent of the sheet thickness. Subcritical growth of surface cracks was investigated. Comparison of chamber and open air welds showed chamber welds to be slightly tougher. Both methods produced welds with toughness that compared favorably with that of the parent metal. Weld efficiencies were above 94 percent.

  20. Metallic layered composite materials produced by explosion welding: Structure, properties, and structure of the transition zone

    NASA Astrophysics Data System (ADS)

    Mal'tseva, L. A.; Tyushlyaeva, D. S.; Mal'tseva, T. V.; Pastukhov, M. V.; Lozhkin, N. N.; Inyakin, D. V.; Marshuk, L. A.

    2014-10-01

    The structure, morphology, and microhardness of the transition zone in multilayer metallic composite joints are studied, and the cohesion strength of the plates to be joined, the mechanical properties of the formed composite materials, and fracture surfaces are analyzed. The materials to be joined are plates (0.1-1 mm thick) made of D16 aluminum alloy, high-strength maraging ZI90-VI (03Kh12N9K4M2YuT) steel, BrB2 beryllium bronze, and OT4-1 titanium alloy. Composite materials made of different materials are shown to be produced by explosion welding. The dependence of the interface shape (smooth or wavelike) on the physicomechanical properties of the materials to be joined is found. The formation of a wavelike interface is shown to result in the formation of intense-mixing regions in transition zones. Possible mechanisms of layer adhesion are discussed.

  1. Novel concepts in weld metal science: Role of gradients and composite structure. Annual technical progress report, January 1, 1991--December 31, 1991

    SciTech Connect

    Matlock, D.K.; Olson, D.L.

    1991-12-01

    The effects of compositional and microstructural gradients on weld metal properties are being investigated. Crack propagation is solidified alloy structures is being characterized as to solidification orientation and the profile of the compositional variations. The effects of compositional gradients, are considered based on a thermodynamic analysis, referred to as the Cahn-Hillard analysis, which describes the degree to which a local surface energy is modified by the presence of a compositional gradient. The analysis predicts that both ductile and brittle fracture mechanisms are enhanced by the presence of a composition gradient. Special techniques to produce laboratory samples with microstructures which simulate the composition and microstructure gradients in solidified weld metal are used, along with appropriate mathematical models, to evaluate the properties of the composite weld metals. The composite modeling techniques are being applied to describe the effects of compositional and microstructural gradients on weld metal properties in Ni-Cu alloys. The development of metal matrix composition weld deposits on austenitic stainless steels has been studied. The particulate metal matrix composites were produced with ceramic or refractory metal powder filled cored wire, which was gas tungsten arc and gas metal arc welded.

  2. 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

  3. Control of Cr6+ emissions from gas metal arc welding using a silica precursor as a shielding gas additive.

    PubMed

    Topham, Nathan; Wang, Jun; Kalivoda, Mark; Huang, Joyce; Yu, Kuei-Min; Hsu, Yu-Mei; Wu, Chang-Yu; Oh, Sewon; Cho, Kuk; Paulson, Kathleen

    2012-03-01

    Hexavalent chromium (Cr(6+)) emitted from welding poses serious health risks to workers exposed to welding fumes. In this study, tetramethylsilane (TMS) was added to shielding gas to control hazardous air pollutants produced during stainless steel welding. The silica precursor acted as an oxidation inhibitor when it decomposed in the high-temperature welding arc, limiting Cr(6+) formation. Additionally, a film of amorphous SiO(2) was deposited on fume particles to insulate them from oxidation. Experiments were conducted following the American Welding Society (AWS) method for fume generation and sampling in an AWS fume hood. The results showed that total shielding gas flow rate impacted the effectiveness of the TMS process. Increasing shielding gas flow rate led to increased reductions in Cr(6+) concentration when TMS was used. When 4.2% of a 30-lpm shielding gas flow was used as TMS carrier gas, Cr(6+) concentration in gas metal arc welding (GMAW) fumes was reduced to below the 2006 Occupational Safety and Health Administration standard (5 μg m(-3)) and the efficiency was >90%. The process also increased fume particle size from a mode size of 20 nm under baseline conditions to 180-300 nm when TMS was added in all shielding gas flow rates tested. SiO(2) particles formed in the process scavenged nanosized fume particles through intercoagulation. Transmission electron microscopy imagery provided visual evidence of an amorphous film of SiO(2) on some fume particles along with the presence of amorphous SiO(2) agglomerates. These results demonstrate the ability of vapor phase silica precursors to increase welding fume particle size and minimize chromium oxidation, thereby preventing the formation of hexavalent chromium.

  4. 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.

  5. Al-to-Mg Friction Stir Welding: Effect of Material Position, Travel Speed, and Rotation Speed

    NASA Astrophysics Data System (ADS)

    Firouzdor, Vahid; Kou, Sindo

    2010-11-01

    Because joining dissimilar metals is often difficult by fusion joining, interest has been growing rapidly in using friction stir welding (FSW), which is considered a revolutionary solid-state welding process, as a new way to join dissimilar metals such as Al alloys to Mg alloys, Cu, and steels. Butt FSW of Al to Mg alloys has been studied frequently recently, but the basic issue of how the welding conditions affect the resultant joint strength still is not well understood. Using the widely used alloys 6061 Al and AZ31 Mg, the current study investigated the effect of the welding conditions, including the positions of Al and Mg with respect to the welding tool, the tool travel speed, and the tool rotation speed on the weld strength. Unlike previous studies, the current study (1) determined the heat input by both torque and temperature measurements during FSW, (2) used color metallography with Al, Mg, Al3Mg2, and Al12Mg17 all shown in different colors to reveal clearly the formation of intermetallic compounds and material flow in the stir zone, which are known to affect the joint strength significantly, and (3) determined the windows for travel and rotation speeds to optimize the joint strength for various material positions. The current study demonstrated clearly that the welding conditions affect the heat input, which in turn affects (1) the formation of intermetallics and even liquid and (2) material flow. Thus, the effect of welding conditions in Al-to-Mg butt FSW on the joint strength now can be explained.

  6. Infrared measurement of base metal temperature in gas tungsten arc welding

    SciTech Connect

    Farson, D.; Richardson, R.; Li, X.

    1998-09-01

    Quantification of infrared (IR) radiation is a convenient, non-contact method for making the base metal temperature measurements needed for on-line feedback controls. However, the problem of interference from the arc is a complicating factor in applying IR temperature sensing to welding. The objective of this research is to implement and test a top-face, non-contact temperature measurement system based on optical pyrometry. Investigations relating to the development of an infrared temperature measurement system are described. An apparatus consisting of a fiberoptic cable, a silicon photodiode/power meter and a computer data acquisition system were configured and used for the tests. Results of the experiments showed that radiation from both the arc and the hot tungsten electrode were important sources of interference in the IR emissions from the base metal. Attenuation of the interfering radiation using a band-pass optical filter and a specially-designed gas cup was investigated. Finally, the sensing system was calibrated using thermocouple measurements of actual base metal temperature.

  7. Occupational exposure to dioxins by thermal oxygen cutting, welding, and soldering of metals.

    PubMed

    Menzel, H M; Bolm-Audorff, U; Turcer, E; Bienfait, H G; Albracht, G; Walter, D; Emmel, C; Knecht, U; Päpke, O

    1998-04-01

    This paper focuses on one aspect of occupational dioxin exposure that is novel and unexpected. Exposures in excess of the German threshold limit value of 50 pg international toxicity equivalent (I-TEQ)/m3 are very frequent, unpredictable, and sometimes very high--up to 6612 pg I-TEQ/m3--during thermal oxygen cutting at scrap metal and demolition sites. The same procedure involving virgin steel in steel trade and mass production of steel objects gave no such evidence, even though no final conclusions can be drawn because of the low number of samples analyzed. Low dioxin exposures during inert gas electric arc welding confirm previous literature findings, whereas soldering and thermal oxygen cutting in the presence of polyvinyl chloride give rise to concern. The consequences of occupational dioxin exposure were studied by analysis of the dioxin-blood concentration, the body burden, of men performing thermal oxygen cutting at scrap metal reclamation and demolition sites, in steel trade and producing plants as well as for industrial welders and white-collar workers. The results concerning body burdens are in excellent agreement with the dioxin exposure as characterized by dioxin air concentration in the workplace. The significant positive correlation between duration and frequency of performing thermal oxygen cutting at metal reclamation and demolition sites expressed in job-years and dioxin body burden speaks for the occupational origin of the observed overload after long times. The results reported here lead to consequences for occupational health, which are discussed and require immediate attention.

  8. Effect of Heat Treatment on Low Temperature Toughness of Reduced Pressure Electron Beam Weld Metal of Type 316L Stainless Steel

    SciTech Connect

    Nakagawa, H.; Fujii, H.; Tamura, M.

    2006-03-31

    Austenitic stainless steels are considered to be the candidate materials for liquid hydrogen vessels and the related equipments, and those welding parts that require high toughness at cryogenic temperature. The authors have found that the weld metal of Type 316L stainless steel processed by reduced pressure electron beam (RPEB) welding has high toughness at cryogenic temperature, which is considered to be due to the single-pass welding process without reheating effect accompanied by multi-pass welding process.In this work, the effect of heat treatment on low temperature toughness of the RPEB weld metal of Type 316L was investigated by Charpy impact test at 77K. The absorbed energy decreased with higher temperature and longer holding time of heat treatment. The remarkable drop in the absorbed energy was found with heat treatment at 1073K for 2 hours, which is as low as that of conventional multi-pass weld metal such as tungsten inert gas welding. The observations of fracture surface and microstructure revealed that the decrease in the absorbed energy with heat treatment resulted from the precipitation of intermetallic compounds near delta-ferrite phase.

  9. Experimental and numerical investigation of laser shock synchronous welding and forming of Copper/Aluminum

    NASA Astrophysics Data System (ADS)

    Wang, Xiao; Zhang, Hongfeng; Shen, Zongbao; Li, Jianwen; Qian, Qing; Liu, Huixia

    2016-11-01

    A novel laser shock synchronous welding and forming method is introduced, which utilizes laser-induced shock waves to accelerate the flyer plate towards the base plate to achieve the joining of dissimilar metals and forming in a specific shape of mold. The samples were obtained with different laser energies and standoff distances. The surface morphology and roughness of the samples were greatly affected by the laser energy and standoff distances. Fittability was investigated to examine the forming accuracy. The results showed that the samples replicate the mold features well. Straight and wavy interfaces with un-bonded regions in the center were observed through metallographic analysis. Moreover, Energy Disperse Spectroscopy analysis was conducted on the welding interface, and the results indicated that a short-distance elemental diffusion emerged in the welding interface. The nanoindentation hardness of the welding regions was measured to evaluate the welding interface. In addition, the Smoothed Particle Hydrodynamics method was employed to simulate the welding and forming process. It was shown that different standoff distances significantly affected the size of the welding regions and interface waveform characteristics. The numerical analysis results indicated that the opposite shear stress direction and effective plastic strain above a certain threshold are essential to successfully obtain welding and forming workpiece.

  10. Thermal Stir Welding: A New Solid State Welding Process

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey

    2003-01-01

    Thermal stir welding is a new welding process developed at NASA's Marshall Space Flight Center in Huntsville, AL. Thermal stir welding is similar to friction stir welding in that it joins similar or dissimilar materials without melting the parent material. However, unlike friction stir welding, the heating, stirring and forging elements of the process are all independent of each other and are separately controlled. Furthermore, the heating element of the process can be either a solid-state process (such as a thermal blanket, induction type process, etc), or, a fusion process (YG laser, plasma torch, etc.) The separation of the heating, stirring, forging elements of the process allows more degrees of freedom for greater process control. This paper introduces the mechanics of the thermal stir welding process. In addition, weld mechanical property data is presented for selected alloys as well as metallurgical analysis.

  11. Thermal Stir Welding: A New Solid State Welding Process

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

    Thermal stir welding is a new welding process developed at NASA's Marshall Space Flight Center in Huntsville, AL. Thermal stir welding is similar to friction stir welding in that it joins similar or dissimilar materials without melting the parent material. However, unlike friction stir welding, the heating, stirring and forging elements of the process are all independent of each other and are separately controlled. Furthermore, the heating element of the process can be either a solid-state process (such as a thermal blanket, induction type process, etc), or, a fusion process (YG laser, plasma torch, etc.) The separation of the heating, stirring, forging elements of the process allows more degrees of freedom for greater process control. This paper introduces the mechanics of the thermal stir welding process. In addition, weld mechanical property data is presented for selected alloys as well as metallurgical analysis.

  12. Advanced fusion welding processes, solid state joining and a successful marriage. [production of aerospace structures

    NASA Technical Reports Server (NTRS)

    Miller, F. R.

    1972-01-01

    Joining processes for aerospace systems combine fusion welding and solid state joining during production of metal structures. Detailed characteristics of electron beam welding, plasma arc welding, diffusion welding, inertia welding and weldbond processes are discussed.

  13. Lightweight, High-Current Welding Gun

    NASA Technical Reports Server (NTRS)

    Starck, Thomas F.; Brennan, Andrew D.

    1989-01-01

    Lighweight resistance-welding, hand-held gun supplies alternating or direct current over range of 600 to 4,000 A and applies forces from 40 to 60 lb during welding. Used to weld metal sheets in multilayered stacks.

  14. Multiphysics Modeling and Simulations of Mil A46100 Armor-Grade Martensitic Steel Gas Metal Arc Welding Process

    DTIC Science & Technology

    2013-05-23

    Multiphysics Modeling and Simulations of Mil A46100 Armor-Grade Martensitic Steel Gas Metal Arc Welding Process M. Grujicic, S. Ramaswami, J.S...hardness armor martensitic steel . The model consists of five distinct modules, each covering a specific aspect of the GMAW process, i.e., (a) dynamics...FZ, and the adjacent heat-affected zone, HAZ) of a prototypical high-hardness armor-grade martensitic steel MIL A46100 (Ref 1). It is hoped that the

  15. On-line quality monitoring in short-circuit gas metal arc welding

    SciTech Connect

    Adolfsson, S. |; Bolmsjoe, G.; Claesson, I.

    1999-02-01

    This paper addresses the problems involved in the automatic monitoring of the weld quality produced by robotized short-arc welding. A simple statistical change detection algorithm for the weld quality, the repeated Sequential Probability Ratio Test (SPRT), was used. The algorithm may similarly be viewed as a cumulative sum (CUSUM) type test, and is well-suited to detecting sudden minor changes in the monitored test statistic. The test statistic is based on the variance of the weld voltage, wherein it will be shown that the variance decreases when the welding process is not operating under optimal conditions. The performance of the algorithm is assessed through the use of experimental data. The results obtained from the algorithm show that it is possible to detect changes in weld quality automatically and on-line.

  16. Technical Letter Report Assessment of Ultrasonic Phased Array Testing for Cast Austenitic Stainless Steel Pressurizer Surge Line Piping Welds and Thick Section Primary System Cast Piping Welds JCN N6398, Task 2A

    SciTech Connect

    Diaz, Aaron A.; Denslow, Kayte M.; Cinson, Anthony D.; Morra, Marino; Crawford, Susan L.; Prowant, Matthew S.; Cumblidge, Stephen E.; Anderson, Michael T.

    2008-07-21

    Research is being conducted for the NRC at PNNL to assess the effectiveness and reliability of advanced NDE methods for the inspection of LWR components. The scope of this research encompasses primary system pressure boundary materials including cast austenitic stainless steels (CASS), dissimilar metal welds (DMWs), piping with corrosion-resistant cladding, weld overlays, and far-side examinations of austenitic piping welds. A primary objective of this work is to evaluate various NDE methods to assess their ability to detect, localize, and size cracks in coarse-grained steel components. This interim technical letter report (TLR) provides a synopsis of recent investigations at PNNL aimed at evaluating the capabilities of phased-array (PA) ultrasonic testing (UT) methods as applied to the inspection of CASS welds in nuclear reactor piping. A description of progress, recent developments and interim results are provided.

  17. Microstructural analysis of a single pass 2.25% Cr-1.0% Mo steel weld metal with different manganese contents

    SciTech Connect

    Guimares de Souza, Luis Felipe; Souza Bott, Ivani de; Ferreira Jorge, Jorge Carlos; Sauer Guimaraes, Ari; Pinheiro Rocha Paranhos, Ronaldo . E-mail: paranhos@uenf.br

    2005-07-15

    Weld metals of the 2.25% Cr-1.0% Mo type with 0.84%, 1.21% and 2.3% Mn produced by submerged-arc welding were analyzed in the as-welded (AW), post weld heat treatment (PWHT) and PWHT followed by step-cooling (SC) heat treatment conditions. Fracture surface analysis revealed an evolution in the mode of fracture due to Mn content variations and heat treatment conditions, the occurrence of intergranular fracture being observed in welds with 2.30% Mn that were step-cooled. Transmission electron microscopy revealed that the microstructure was predominantly composed of bainite, although martensite was also observed for high Mn contents. A marked carbide precipitation was observed, preferentially at grain boundaries. This could be attributed to the SC heat treatment and associated with the embrittlement. However, the application of a de-embrittlement heat treatment to this step cooled weld metal has proved efficient, because the impact energy levels after this heat treatment surpassed those obtained in the stress relieved condition. This indicates that segregation of impurities to grain boundaries was responsible for the low impact energy levels observed after SC of weld metal containing > 0.84% Mn.

  18. The structure and properties of filler metal-free laser beam welded joints in steel S700MC subjected to TMCP

    NASA Astrophysics Data System (ADS)

    Górka, Jacek; Stano, Sebastian

    2016-12-01

    The research-related tests aimed to determine the effect of filer-metal free laser beam welding on the structure and properties of 10 mm thick steel S700MC subjected to the Thermo-Mechanical Control Process (TMCP). The nondestructive tests revealed that the welded joints represented quality level B according to the requirements of standard 13919-1. The destructive tests revealed that the joints were characterised by tensile strength being by approximately 5% lower than that of the base material. The tests of thin foils performed using a high-resolution scanning transmission electron microscope revealed that filler metal-free welding led to the increased amount of alloying microagents (Ti and Nb) in the weld (particularly near fusion line) in comparison with welding performed using a filler metal. The significant content of hardening phases in the welds during cooling resulted in considerable precipitation hardening through finedispersive (Ti,Nb)(C,N) type precipitates (several nm in size) leading to the deterioration of plastic properties. The destructive tests revealed that the joints were characterised by tensile strength being by approximately 5% lower than that of the base material. The increase in the concentration of microagents responsible for steel hardening (Ti and Nb) also contributed to the decrease in weld toughness being below the allowed value of 25 J/cm2.

  19. A Microsample Tensile Test Application: Local Strength of Impact Welds Between Sheet Metals

    NASA Astrophysics Data System (ADS)

    Benzing, J. T.; He, M.; Vivek, A.; Taber, G. A.; Mills, M. J.; Daehn, G. S.

    2017-01-01

    Microsample tensile testing was conducted to evaluate the quality of impact welds created by vaporizing foil actuator welding. Tensile test samples with a gauge length of 0.6 mm were electro-discharge machined out of welds created between 1-mm-thick aluminum alloy type 6061 (AA6061) sheets and 6-mm-thick copper (Cu110) plates. Aluminum sheets were used as flyers, while copper plates acted as targets. Flyer sheets in T6 as well as T4 temper conditions were utilized to create welds. Some of the welds made with T4 temper flyers were heat treated to a T6 temper. It was found that the welds made with T4 temper flyers were slightly stronger (max. of 270 MPa) than those produced with T6 temper flyers. Generally, failure propagated in a brittle manner across the weld interface; however, elemental mapping reveals material transfer on either member of the welded system. This work proves the feasibility to apply microsample tensile testing to assess impact welding, even when conducted with flyer sheets of 1 mm or less, and provides insight that is complementary to other test methods.

  20. Effects of weld metal strength and defects on the ductility of HSLA-100 plates

    SciTech Connect

    Dexter, R.J.; Ferrell, M.

    1995-12-31

    Wide-plate tension tests were performed on high-strength low-alloy steel, minimum yield strength of 690 MPa, with various controlled intentional defects in both undermatched and overmatched welds. Lack-of-fusion areas on the sidewall comprising about 10 percent of the cross-section resulted in full net-section strength. Weld undercut to a depth of 12 percent of the thickness resulted in gross-section yielding and good elongation. Misalignment (offset) of 3 mm slightly reduced the elongation relative to plates within tolerances. There was no consistent difference between the results of the undermatched welds and the overmatched welds.

  1. Assessment of weld quality of aerospace grade metals by using ultrasonic matrix phased array technology

    NASA Astrophysics Data System (ADS)

    Na, Jeong K.; Gleeson, Sean T.

    2014-03-01

    Advantages of two dimensional electronic ultrasonic beam focusing, steering and scanning with the matrix phased array (MPA) technology has been used to visualize the conditions of resistance spot welds in auto vehicle grade advanced high strength steel carbon steels nondestructively. Two of the commonly used joining techniques, resistance spot welding and resistance seam welding, for thin aerospace grade plates made of aluminum, titanium, and stainless steels have also been inspected with the same MPA NDE system. In this study, a detailed discussions of the current MPA based ultrasonic real time imaging methodology has been made followed by some of the NDT results obtained with various welded test coupons.

  2. A Microsample Tensile Test Application: Local Strength of Impact Welds Between Sheet Metals

    NASA Astrophysics Data System (ADS)

    Benzing, J. T.; He, M.; Vivek, A.; Taber, G. A.; Mills, M. J.; Daehn, G. S.

    2017-03-01

    Microsample tensile testing was conducted to evaluate the quality of impact welds created by vaporizing foil actuator welding. Tensile test samples with a gauge length of 0.6 mm were electro-discharge machined out of welds created between 1-mm-thick aluminum alloy type 6061 (AA6061) sheets and 6-mm-thick copper (Cu110) plates. Aluminum sheets were used as flyers, while copper plates acted as targets. Flyer sheets in T6 as well as T4 temper conditions were utilized to create welds. Some of the welds made with T4 temper flyers were heat treated to a T6 temper. It was found that the welds made with T4 temper flyers were slightly stronger (max. of 270 MPa) than those produced with T6 temper flyers. Generally, failure propagated in a brittle manner across the weld interface; however, elemental mapping reveals material transfer on either member of the welded system. This work proves the feasibility to apply microsample tensile testing to assess impact welding, even when conducted with flyer sheets of 1 mm or less, and provides insight that is complementary to other test methods.

  3. Welding Development: Marshall Space Flight Center

    NASA Technical Reports Server (NTRS)

    Ding, Jeff

    2007-01-01

    This paper presents the basic understanding of the friction stir welding process. It covers process description, pin tool operation and materials, metal flow theory, mechanical properties, and materials welded using the process. It also discusses the thermal stir welding process and the differences between thermal stir and friction stir welding. MSFC weld tools used for development are also presented.

  4. Occupational exposure to dioxins by thermal oxygen cutting, welding, and soldering of metals.

    PubMed Central

    Menzel, H M; Bolm-Audorff, U; Turcer, E; Bienfait, H G; Albracht, G; Walter, D; Emmel, C; Knecht, U; Päpke, O

    1998-01-01

    This paper focuses on one aspect of occupational dioxin exposure that is novel and unexpected. Exposures in excess of the German threshold limit value of 50 pg international toxicity equivalent (I-TEQ)/m3 are very frequent, unpredictable, and sometimes very high--up to 6612 pg I-TEQ/m3--during thermal oxygen cutting at scrap metal and demolition sites. The same procedure involving virgin steel in steel trade and mass production of steel objects gave no such evidence, even though no final conclusions can be drawn because of the low number of samples analyzed. Low dioxin exposures during inert gas electric arc welding confirm previous literature findings, whereas soldering and thermal oxygen cutting in the presence of polyvinyl chloride give rise to concern. The consequences of occupational dioxin exposure were studied by analysis of the dioxin-blood concentration, the body burden, of men performing thermal oxygen cutting at scrap metal reclamation and demolition sites, in steel trade and producing plants as well as for industrial welders and white-collar workers. The results concerning body burdens are in excellent agreement with the dioxin exposure as characterized by dioxin air concentration in the workplace. The significant positive correlation between duration and frequency of performing thermal oxygen cutting at metal reclamation and demolition sites expressed in job-years and dioxin body burden speaks for the occupational origin of the observed overload after long times. The results reported here lead to consequences for occupational health, which are discussed and require immediate attention. Images Figure 1 PMID:9599722

  5. WELDING PROCESS

    DOEpatents

    Zambrow, J.; Hausner, H.

    1957-09-24

    A method of joining metal parts for the preparation of relatively long, thin fuel element cores of uranium or alloys thereof for nuclear reactors is described. The process includes the steps of cleaning the surfaces to be jointed, placing the sunfaces together, and providing between and in contact with them, a layer of a compound in finely divided form that is decomposable to metal by heat. The fuel element members are then heated at the contact zone and maintained under pressure during the heating to decompose the compound to metal and sinter the members and reduced metal together producing a weld. The preferred class of decomposable compounds are the metal hydrides such as uranium hydride, which release hydrogen thus providing a reducing atmosphere in the vicinity of the welding operation.

  6. Chemical welding of binary nanoparticles: room temperature sintering of CuSe and In2S3 nanoparticles for solution-processed CuInS(x)Se(1-x) solar cells.

    PubMed

    Min Lim, Hui; Batabyal, Sudip K; Pramana, Stevin S; Wong, L H; Magdassi, Shlomo; Mhaisalkar, S G

    2013-06-14

    Chemical welding of oppositely charged dissimilar metal chalcogenide nanomaterials is reported to produce a quaternary metal chalcogenide. CuSe and In2S3 nanoparticles were synthesized with opposite surface charges by stabilizing with polyacrylic acid and polydiallyldimethylammonium chloride. Upon mixing these nanoparticles at room temperature, the electrostatic attraction induced coalescence of these nanoparticles and led to the formation of CuInSxSe1-x nanoparticles.

  7. Irradiation-induced structural changes in surveillance material of VVER 440-type weld metal

    NASA Astrophysics Data System (ADS)

    Grosse, M.; Denner, V.; Böhmert, J.; Mathon, M.-H.

    2000-01-01

    The irradiation-induced microstructural changes in surveillance materials of the VVER 440-type weld metal Sv-10KhMFT were investigated by small angle neutron scattering (SANS) and anomalous small angle X-ray scattering (SAXS). Due to the high fluence, a strong effect was found in the SANS experiment. No significant effect of the irradiation is detected by SAXS. The reason for this discrepancy is the different scattering contrast of irradiation-induced defects for neutrons and X-rays. An analysis of the SAXS shows that the scattering intensity is mainly caused by vanadium-containing (VC) precipitates and grain boundaries. Both types of scattering defects are hardly changed by irradiation. Neutron irradiation rather produces additional scattering defects of a few nanometers in size. Assuming these defects are clusters containing copper and other foreign atoms with a composition according to results of atom probe field ion microscopy (APFIM) investigations, both the high SANS and the low SAXS effect can be explained.

  8. Investigation of microstructure within metal welds by energy resolved neutron imaging

    NASA Astrophysics Data System (ADS)

    Tremsin, A. S.; Kockelmann, W.; Paradowska, A. M.; Zhang, Shu-Yan; Korsunsky, A. M.; Shinohara, T.; Feller, W. B.; Lehmann, E. H.

    2016-09-01

    The recent development of bright pulsed neutron sources and high resolution neutron counting detectors enables simultaneous acquisition of a neutron transmission spectrum for each pixel of the image. These spectra can be used to reconstruct microstructure parameters within welds, such as strain, texture and phase composition through Bragg edge analysis, and in some cases elemental composition through resonance absorption analysis. In this paper we demonstrate the potential of energy-resolved neutron imaging to study the microstructures of two steel welds, where the spatial distribution of residual strain within the welds, as well as some information on the texture, are obtained with sub-mm spatial resolution. A friction stir weld of two steel plates and a conventional weld of two steel pipes were studied at pulsed neutron facilities, where a Δλ/λ resolution as low as 0.2% can be attained over a wide range of neutron wavelengths ranging from 0.5 Å to 8 Å.

  9. Fabrication and characterization of metal-packaged fiber Bragg grating sensor by one-step ultrasonic welding

    NASA Astrophysics Data System (ADS)

    Zhang, Yumin; Zhu, Lianqing; Luo, Fei; Dong, Mingli; Ding, Xiangdong; He, Wei

    2016-06-01

    A metallic packaging technique of fiber Bragg grating (FBG) sensors is developed for measurement of strain and temperature, and it can be simply achieved via one-step ultrasonic welding. The average strain transfer rate of the metal-packaged sensor is theoretically evaluated by a proposed model aiming at surface-bonded metallic packaging FBG. According to analytical results, the metallic packaging shows higher average strain transfer rate compared with traditional adhesive packaging under the same packaging conditions. Strain tests are performed on an elaborate uniform strength beam for both tensile and compressive strains; strain sensitivities of approximately 1.16 and 1.30 pm/μɛ are obtained for the tensile and compressive situations, respectively. Temperature rising and cooling tests are also executed from 50°C to 200°C, and the sensitivity of temperature is 36.59 pm/°C. All the measurements of strain and temperature exhibit good linearity and stability. These results demonstrate that the metal-packaged sensors can be successfully fabricated by one-step welding technique and provide great promise for long-term and high-precision structural health monitoring.

  10. Improved Gas Metal Arc Welding Multi-Physics Process Model and Its Application to MIL A46100 Armor-Grade Steel Butt-welds

    DTIC Science & Technology

    2014-01-01

    within the weld. Design/methodology/approach The improved GMAW process model is next applied to the case of butt-welding of MIL A46100 (a...improved GMAW process model pertaining to the spatial distribution of the material microstructure and properties within the MIL A46100 butt-weld are

  11. Evaluation of High Temperature Properties and Microstructural Characterization of Resistance Spot Welded Steel Lap Shear Joints

    NASA Astrophysics Data System (ADS)

    Gupta, R. K.; Anil Kumar, V.; Panicker, Paul G.

    2016-02-01

    Joining of thin sheets (0.5 mm) of stainless steel 304 and 17-4PH through resistance spot welding is highly challenging especially when joint is used for high temperature applications. Various combinations of stainless steel sheets of thickness 0.5 mm are spot welded and tested at room temperature as well as at high temperatures (800 K, 1,000 K, 1,200 K). Parent metal as well as spot welded joints are tested and characterized. It is observed that joint strength of 17-4PH steel is highest and then dissimilar steel joint of 17-4PH with SS-304 is moderate and of SS-304 is lowest at all the temperatures. Joint strength of 17-4PH steel is found to be >80% of parent metal properties up to 1,000 K then drastic reduction in strength is noted at 1,200 K. Gradual reduction in strength of SS-304 joint with increase in temperature from 800 to 1,200 K is noted. At 1,200 K, joint strength of all combinations of joints is found to be nearly same. Microstructural evaluation of weld nugget after testing at different temperatures shows presence of tempered martensite in 17-4PH containing welds and homogenized structure in stainless steel 304 weld.

  12. Method for welding beryllium

    DOEpatents

    Dixon, Raymond D.; Smith, Frank M.; O'Leary, Richard F.

    1997-01-01

    A method is provided for joining beryllium pieces which comprises: depositing aluminum alloy on at least one beryllium surface; contacting that beryllium surface with at least one other beryllium surface; and welding the aluminum alloy coated beryllium surfaces together. The aluminum alloy may be deposited on the beryllium using gas metal arc welding. The aluminum alloy coated beryllium surfaces may be subjected to elevated temperatures and pressures to reduce porosity before welding the pieces together. The aluminum alloy coated beryllium surfaces may be machined into a desired welding joint configuration before welding. The beryllium may be an alloy of beryllium or a beryllium compound. The aluminum alloy may comprise aluminum and silicon.

  13. Study for corrosion characteristics of ferritic stainless steel weld metal with respect to added contents of Ti and Nb

    NASA Astrophysics Data System (ADS)

    Kim, JongMin; Lee, HaeWoo

    2014-03-01

    This paper identified the effects of Ti and Nb on pitting and intergranular corrosion resistance in a ferritic stainless steel weld metal of the automobile exhaust system. We fabricated 4 flux cored wires designed with 0-0.2 wt% Ti and 0-1.0 wt% Nb and performed Flux Cored Arc Welding. Through the potentiodynamic polarization test in 0.5M NaCl, we evaluated pitting resistance. And in order to evaluate the intergranular corrosion resistance, we observed microstructure after we performed DL-EPR test in 0.5M H2SO4+0.01M KSCN. As a result of the test, the specimen added with 0.2%Ti+1.0%Nb showed the highest pitting resistance. From observing the degree of sensitization and microstructure, the intergranular corrosion resistance was higher as the contents of Ti and Nb increased. And through EBSD we observed Cr carbide which affects the corrosion resistance.

  14. Resistance-Welding Test Fixture

    NASA Technical Reports Server (NTRS)

    Brennan, Andrew D.

    1990-01-01

    Realistic welding conditions produce reliable specimens. Simple fixture holds resistance-welding test specimens. Specimen holder includes metallic holder and clamps to provide electrical and thermal paths and plastic parts providing thermal and electrical isolation.

  15. Effects of Thermal Aging on Material Properties, Stress Corrosion Cracking, and Fracture Toughness of AISI 316L Weld Metal

    NASA Astrophysics Data System (ADS)

    Lucas, Timothy; Forsström, Antti; Saukkonen, Tapio; Ballinger, Ronald; Hänninen, Hannu

    2016-08-01

    Thermal aging and consequent embrittlement of materials are ongoing issues in cast stainless steels, as well as duplex, and high-Cr ferritic stainless steels. Spinodal decomposition is largely responsible for the well-known "748 K (475 °C) embrittlement" that results in drastic reductions in ductility and toughness in these materials. This process is also operative in welds of either cast or wrought stainless steels where δ-ferrite is present. While the embrittlement can occur after several hundred hours of aging at 748 K (475 °C), the process is also operative at lower temperatures, at the 561 K (288 °C) operating temperature of a boiling water reactor (BWR), for example, where ductility reductions have been observed after several tens of thousands of hours of exposure. An experimental program was carried out in order to understand how spinodal decomposition may affect changes in material properties in Type 316L BWR piping weld metals. The study included material characterization, nanoindentation hardness, double-loop electrochemical potentiokinetic reactivation (DL-EPR), Charpy-V, tensile, SCC crack growth, and in situ fracture toughness testing as a function of δ-ferrite content, aging time, and temperature. SCC crack growth rates of Type 316L stainless steel weld metal under simulated BWR conditions showed an approximate 2 times increase in crack growth rate over that of the unaged as-welded material. In situ fracture toughness measurements indicate that environmental exposure can result in a reduction of toughness by up to 40 pct over the corresponding at-temperature air-tested values. Material characterization results suggest that spinodal decomposition is responsible for the degradation of material properties measured in air, and that degradation of the in situ properties may be a result of hydrogen absorbed during exposure to the high-temperature water environment.

  16. Making Superconducting Welds between Superconducting Wires

    NASA Technical Reports Server (NTRS)

    Penanen, Konstantin I.; Eom, Byeong Ho

    2008-01-01

    A technique for making superconducting joints between wires made of dissimilar superconducting metals has been devised. The technique is especially suitable for fabrication of superconducting circuits needed to support persistent electric currents in electromagnets in diverse cryogenic applications. Examples of such electromagnets include those in nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) systems and in superconducting quantum interference devices (SQUIDs). Sometimes, it is desirable to fabricate different parts of a persistent-current-supporting superconducting loop from different metals. For example, a sensory coil in a SQUID might be made of Pb, a Pb/Sn alloy, or a Cu wire plated with Pb/Sn, while the connections to the sensory coil might be made via Nb or Nb/Ti wires. Conventional wire-bonding techniques, including resistance spot welding and pressed contact, are not workable because of large differences between the hardnesses and melting temperatures of the different metals. The present technique is not subject to this limitation. The present technique involves the use (1) of a cheap, miniature, easy-to-operate, capacitor-discharging welding apparatus that has an Nb or Nb/Ti tip and operates with a continuous local flow of gaseous helium and (2) preparation of a joint in a special spark-discharge welding geometry. In a typical application, a piece of Nb foil about 25 m thick is rolled to form a tube, into which is inserted a wire that one seeks to weld to the tube (see figure). The tube can be slightly crimped for mechanical stability. Then a spark weld is made by use of the aforementioned apparatus with energy and time settings chosen to melt a small section of the niobium foil. The energy setting corresponds to the setting of a voltage to which the capacitor is charged. In an experiment, the technique was used to weld an Nb foil to a copper wire coated with a Pb/Sn soft solder, which is superconducting. The joint was evaluated as

  17. The Effect of Heat Input and Composition on Weld Metal Microstructures in Thin Section HY-130 GMAW(Gas Metal Are Welding) Weldments

    DTIC Science & Technology

    1988-12-01

    carbon segregation [Ref. 2]. 2. Tempered and Autotempered Martensite Martensite is not an equilibrium microstructure so it can be t,,mpered by...due to either carbon segregation or precipitation of carbides on a scale too fine to observe with standard TEM techniques. 12 C. EFFECT OF HEAT INPUT...with no carbides in the martensite. They also observed the presence of twinned martensite in bainite within HY-130 weld zones due to carbon segregation [Ref

  18. Characterization of solid-phase welds between Ti-6Al-2Sn-4Zr-2Mo-0. 01Si and Ti-13. 5A1-21. 5Nb titanium aluminide

    SciTech Connect

    Baeslack, W.A. III; Juhas, M.; Fraser, H.L. ); Broderick, T.F. . Materials Directorate)

    1994-12-01

    Dissimilar-alloy welds have been produced between Ti-6Al-2Sn-4Zr-2Mo-0.1Si (wt.%) and Ti-13.5Al-21.5Nb (wt.%) titanium aluminide using three different solid-phase welding processes that create significantly different thermo-mechanical conditions at the weld interface. Exposure to supertransus temperatures, appreciable deformation and rapid cooling of the weld interface region during linear-friction welding promote dynamic recrystallization of beta grains and beta decomposition to fine martensitic products. In contrast, diffusion welding at temperatures below the base metal beta transus temperatures and at relatively low pressures minimizes deformation and microstructural variations in the weld interface region relative to the unaffected base metal. During capacitor-discharge resistance spot welding, extremely rapid heating of the weld interface region to near-solidus temperatures, and subsequent rapid cooling, result in the formation of a metastable, ordered-beta microstructure in the Ti-13.5ASl-21.5Nb and fine alpha-prime martensite in the Ti-6Al-2Sn-4Zr-2Mo-0.1Si.

  19. Improved TIG weld joint strength in aluminum alloy 2219-T87 by filler metal substitution

    NASA Technical Reports Server (NTRS)

    Poorman, R. M.; Lovoy, C. V.

    1972-01-01

    The results of an investigation on weld joint characteristics of aluminum alloy 2219-T87 are given. Five different alloys were utilized as filler material. The mechanical properties of the joints were determined at ambient and cryogenic temperatures for weldments in the as-welded condition and also, for weldments after elevated temperature exposures. Other evaluations included hardness surveys, stress corrosion susceptibility, and to a limited extent, the internal metallurgical weld structures. The overall results indicate that M-943 filler weldments are superior in strength to weldments containing either the standard 2319 filler or fillers 2014, 2020, and a dual wire feed consisting of three parts 2319 and one part 5652. In addition, no deficiencies were evident in M-934 filler weldments with regard to ductility, joint strength after elevated temperature exposure, weld hardness, metallographic structures, or stress corrosion susceptibility.

  20. Simultaneous laser cutting and welding of metal foil to edge of a plate

    DOEpatents

    Pernicka, J.C.; Benson, D.K.; Tracy, C.E.

    1996-03-19

    A method is described for welding an ultra-thin foil to the edge of a thicker sheet to form a vacuum insulation panel comprising the steps of providing an ultra-thin foil having a thickness less than 0.002, providing a top plate having an edge and a bottom plate having an edge, clamping the foil to the edge of the plate wherein the clamps act as heat sinks to distribute heat through the foil, providing a laser, moving the laser relative to the foil and the plate edges to form overlapping weld beads to weld the foil to the plate edges while simultaneously cutting the foil along the weld line formed by the overlapping beads. 7 figs.

  1. Simultaneous laser cutting and welding of metal foil to edge of a plate

    DOEpatents

    Pernicka, John C.; Benson, David K.; Tracy, C. Edwin

    1996-01-01

    A method of welding an ultra-thin foil to the edge of a thicker sheet to form a vacuum insulation panel comprising the steps of providing an ultra-thin foil having a thickness less than 0.002, providing a top plate having an edge and a bottom plate having an edge, clamping the foil to the edge of the plate wherein the clamps act as heat sinks to distribute heat through the foil, providing a laser, moving the laser relative to the foil and the plate edges to form overlapping weld beads to weld the foil to the plate edges while simultaneously cutting the foil along the weld line formed by the overlapping beads.

  2. Field Testing Pulsed Power Inverters in Welding Operations to Control Heavy Metal Emissions

    DTIC Science & Technology

    2009-12-01

    material (for steel alloys the flux is limestone i.e., calcium carbonate based) to inhibit oxidation of the parts being bonded. “Stick” welding (i.e...of steel alloys are primarily argon in combination with smaller percentages of carbon dioxide and/or oxygen. Stick welding is reported to produce...OSHA regulation Experience from demonstration Depends on alloy & space − Heat Stress Slight increase Wet Globe Bulb Temperature (WGBT

  3. Effective Use of Weld Metal Yield Strength for HY-Steels

    DTIC Science & Technology

    1983-01-01

    and Hasubuchi 1959; Hall et al. 1967). Residual stresses also play important roles in stress corrosion cracking and-hydrogen-induced delayed cracking ... stress corrosion cracking . Weldments with inferior strength have been acceptable only in a few limited cases--repair melds in HY-S0 (made with covered...residual weld stresses could reduce the tendency for hydrogen-induced cracking . Welding processes with very low hydrogen potential are available

  4. Inhomogeneities of the interface produced by explosive welding

    NASA Astrophysics Data System (ADS)

    Greenberg, B. A.; Ivanov, M. A.; Rybin, V. V.; Inozemtsev, A. V.; Antonova, O. V.; Elkina, O. A.; Patselov, A. M.; Kuz'min, S. V.; Lysak, V. I.; Kozhevnikov, V. E.

    2012-02-01

    Results of studying structure of the transition zone for a number of joints produced by explosive welding are presented. The joints of dissimilar metals (titanium-orthorhombic titanium aluminide, coppertantalum, and others) have been investigated. The welded pairs of metals differ from each other in mutual solubility; moreover, some pairs (copper-tantalum) virtually lack it. The interface was found to be uneven; it contains inhomogeneities, irrespective of whether it is flat or wavy. It is shown that the formation of interfacial protrusions determines the adhesion of materials. A granulating fragmentation has been found near the protrusions. The role of various processes in explosive welding has been discussed. The formation of protrusions does not depend on whether the metals of a pair have mutual solubility or not. However, this factor affects the structure of zones of local melting. The metals that have mutual solubility form true solutions; in the absence of solubility, these zones represent colloidal solutions. It is shown that sometimes the local melting zones do not present a real danger for the strength of the joint. A hypothesis is proposed that the formation of a wavy surface is possible through the self-organization of the previously formed protrusions.

  5. Novel Process Revolutionizes Welding Industry

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Glenn Research Center, Delphi Corporation, and the Michigan Research Institute entered into a research project to study the use of Deformation Resistance Welding (DRW) in the construction and repair of stationary structures with multiple geometries and dissimilar materials, such as those NASA might use on the Moon or Mars. Traditional welding technologies are burdened by significant business and engineering challenges, including high costs of equipment and labor, heat-affected zones, limited automation, and inconsistent quality. DRW addresses each of those issues, while drastically reducing welding, manufacturing, and maintenance costs.

  6. Solidification of underwater wet welds

    SciTech Connect

    Pope, A.M.; Medeiros, R.C. de; Liu, S.

    1995-12-31

    It is well known that the shape of a weld pool can influence the microstructure and segregation pattern of the final solidified weld metal. Mechanical properties and susceptibility to defects are consequently affected by the solidification mode of the weld. In this work the solidification behavior of weld beads deposited in air and underwater wet welding using rutile electrodes were compared. The welds were deposited by gravity feed, on low carbon, manganese steel plates using similar welding conditions. Macroscopic observation of the weld craters showed that welds deposited in air presented an elliptical weld pool. The underwater wet welds, on the other hand, solidified with a tear drop shape. Although the welds differed in shape, their lengths were approximately the same. Microscopic examinations carried out on transverse, normal and longitudinal sections revealed a coarser columnar grain structure in the underwater welds. These results suggest that the tear-drop shaped pool induced solidification in a preferred orientation with segregation more likely in welds deposited under wet conditions. This change in weld pool geometry can be explained by the surface heat loss conditions that occur in a wet weld: slower when covered by the steam bubble and faster in the region in contact with water behind the pool.

  7. Weld electrode cooling study

    NASA Astrophysics Data System (ADS)

    Masters, Robert C.; Simon, Daniel L.

    1999-03-01

    The U.S. auto/truck industry has been mandated by the Federal government to continuously improve their fleet average gas mileage, measured in miles per gallon. Several techniques are typically used to meet these mandates, one of which is to reduce the overall mass of cars and trucks. To help accomplish this goal, lighter weight sheet metal parts, with smaller weld flanges, have been designed and fabricated. This paper will examine the cooling characteristics of various water cooled weld electrodes and shanks used in resistance spot welding applications. The smaller weld flanges utilized in modern vehicle sheet metal fabrications have increased industry's interest in using one size of weld electrode (1/2 inch diameter) for certain spot welding operations. The welding community wants more data about the cooling characteristics of these 1/2 inch weld electrodes. To hep define the cooling characteristics, an infrared radiometer thermal vision system (TVS) was used to capture images (thermograms) of the heating and cooling cycles of several size combinations of weld electrodes under typical production conditions. Tests results will show why the open ended shanks are more suitable for cooling the weld electrode assembly then closed ended shanks.

  8. Development of Fiber Laser Weld Parameters for Stainless Steel and Refractory Metals

    SciTech Connect

    Elmer, J; Pong, R

    2009-05-19

    Laser welds were made in 21-6-9 stainless steel, vanadium and tantalum using LLNL's new 6kW fiber laser to target 1 mm penetration depths. The materials were machined into flat coupon samples with standard step-joint geometries, and were welded in a continuous wave mode. The laser was characterized using the Primes laser beam diagnostic system so that the beams can be reproduced in the future. The optical configuration consisted of a 200 {micro}m fiber, 200 mm collimator and 250 mm focusing lens, which delivered electron-beam level power densities in the 5 to 20 kW/mm2 range. The three different materials required different power densities to produce the desired penetration, and this report summarizes the results of this screening study that was directed at developing a first approximation to the proper welding parameters for future work. The results show that 1 mm penetrations can be achieved using a 400W beam for 21-6-9 stainless steel, a 600W beam for vanadium, and a 1,100W beam for tantalum using sharp focus and a travel speed of 40 inch/min. Future welds should incorporate a trailing gas shield to prevent discoloration of the surface and to prevent oxygen and nitrogen pickup in the welds.

  9. Friction Stir Weld Inspection Through Conductivity Imaging Using Shaped Field MWM(TM)-Arrays

    NASA Technical Reports Server (NTRS)

    Goldfine, Neil; Grundy, David; Zilberstein, Vladimir; Kinchen, David G.; McCool, Alex (Technical Monitor)

    2002-01-01

    Friction Stir Welds (FSW) of A1 2195-T8 and A1 2219-T8, provided by Lockheed Martin Michoud Operations, were inspected for lack-of-penetration (LOP) defects using a custom designed MWM-Array, a multi-element eddy-current sensor. MWM electrical conductivity mapping demonstrated high sensitivity to LOP as small as 0.75 mm (0.03 in.), as confirmed by metallographic data that characterized the extent of LOP defects. High sensitivity and high spatial resolution was achieved via a 37-element custom designed MWM-Array allowing LOP detection using the normalized longitudinal component of the MWM measured conductivity. This permitted both LOP detection and correlation of MWM conductivity features with the LOP defect size, as changes in conductivity were apparently associated with metallurgical features within the near-surface layer of the LOP defect zone. MWM conductivity mapping reveals information similar to macroetching as the MWM-Array is sensitive to small changes in conductivity due to changes in microstructure associated with material thermal processing, in this case welding. The electrical conductivity measured on the root side of FSWs varies across the weld due to microstructural differences introduced by the FSW process, as well as those caused by planar flaws. Weld metal, i.e., dynamically recrystallized zone (DXZ), thermomechanically affected zone (TMZ), heat-affected zone (HAZ), and parent metal (PM) are all evident in the conductivity maps. While prior efforts had met with limited success for NDE of dissimilar alloy, A12219 to A12195 FSW, the new custom designed multi-element MWM-Array achieved detection of all LOP defects even in dissimilar metal welds.

  10. Friction Stir Weld Inspection Through Conductivity Imaging Using Shaped Field MWM(Registered Trademark) - Arrays

    NASA Technical Reports Server (NTRS)

    Goldfine, Neil; Grundy, David; Zilberstein, Vladimir; Kinchen, David G.; McCool, Alex (Technical Monitor)

    2002-01-01

    Friction Stir Welds (FSW) of Al 2195-T8 and Al 2219-T8, provided by Lockheed Martin Michoud Operations, were inspected for lack-of-penetration (LOP) defects using a custom designed MWM-Array, a multi-element eddy-current sensor. MWM (registered trademark) electrical conductivity mapping demonstrated high sensitivity to LOP as small as 0.75 mm (0.03 in.), as confirmed by metallographic data that characterized the extent of LOP defects. High sensitivity and high spatial resolution was achieved via a 37-element custom designed MWM-Array allowing LOP detection using the normalized longitudinal component of the MWM measured conductivity. This permitted both LOP detection and correlation of MWM conductivity features with the LOP defect size, as changes in conductivity were apparently associated with metallurgical features within the near-surface layer of the LOP defect zone. MWM conductivity mapping reveals information similar to macro-etching as the MWM-Array is sensitive to small changes in conductivity due to changes in microstructure associated with material thermal processing, in this case welding. The electrical conductivity measured on the root side of FSWs varies across the weld due to microstructural differences introduced by the FSW process, as well as those caused by planar flaws. Weld metal, i.e., dynamically recrystallized zone (DXZ), thermomechanically affected zone (TMZ), heat-affected zone (HAZ), and parent metal (PM) are all evident in the conductivity maps. While prior efforts had met with limited success for NDE (Nondestructive Evaluation) of dissimilar alloy, Al2219 to Al2195 FSW, the new custom designed multi-element MWM-Array achieved detection of all LOP defects even in dissimilar metal welds.

  11. Evaluation of crack arrest fracture toughness of parent plate, weld metal and heat affected zone of BIS 812 EMA ship plate steel

    NASA Astrophysics Data System (ADS)

    Burch, I. A.

    1993-10-01

    The steel chosen for the pressure hull of the Collins class submarine has undergone evaluation to compare the crack arrest fracture toughness, K(Ia), of the parent plate with that of weld metal and heat affected zone. The tests were conducted over a range of subzero temperatures on specimens slightly outside the ASTM standard test method specimen configuration. Shallow face grooved specimens were used to vary the propagating crack velocity from that of non face grooved specimens and determine if K(Ia), is sensitive to changes in crack velocity. The weld metal, heat affected zone (HAZ), and parent plate were assessed to determine if the welding process had a deleterious effect on the crack arrest properties of this particular steel. Tests on each of these regions revealed that, for the combination of parent plate, welding procedure and consumables, no adverse effect on crack arrest properties was encountered. Crack arrest fracture toughness of the weld metal and HAZ was superior to that of the parent plate at comparable temperatures.

  12. Nanorobotic spot welding: controlled metal deposition with attogram precision from copper-filled carbon nanotubes.

    PubMed

    Dong, Lixin; Tao, Xinyong; Zhang, Li; Zhang, Xiaobin; Nelson, Bradley J

    2007-01-01

    With the continuing development of bottom-up nanotechnology fabrication processes, spot welding can play a role similar to its macro counterpart for the interconnection of nano building blocks for the assembly of nanoelectronics and nanoelectromechanical systems (NEMS). Spot welding using single-crystalline copper-filled carbon nanotubes (CNTs) is investigated experimentally using nanorobotic manipulation inside a transmission electron microscope (TEM). Controlled melting and flowing of copper inside nanotube shells are realized by applying bias voltages between 1.5 and 2.5 V. The average mass flow rate of the copper was found to be 120 ag/s according to TEM video imaging (measured visually at approximately 11.6 nm/s through the CNT). Successful soldering of a copper-filled CNT onto another CNT shows promise for nano spot welding and thermal dip-pen lithography.

  13. Weld-bonded titanium structures

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Creedon, J. F. (Inventor)

    1976-01-01

    Structurally stronger titanium articles are produced by a weld-bonding technique comprising fastening at least two plates of titanium together using spotwelding and curing an adhesive interspersed between the spot-weld nuggets. This weld-bonding may be employed to form lap joints or to stiffen titanium metal plates.

  14. Fast, Nonspattering Inert-Gas Welding

    NASA Technical Reports Server (NTRS)

    Gilbert, Jeffrey L.

    1991-01-01

    Proposed welding technique combines best features of metal (other than tungsten)/inert-gas welding, plasma arc welding, and tungsten/inert-gas welding. Advantages include: wire fed to weld joint preheated, therefore fed at high speed without spattering; high-frequency energy does not have to be supplied to workpiece to initiate welding; size of arc gap not critical, power-supply control circuit adjusts voltage across gap to compensate for changes; only low gas-flow rate needed; welding electrode replaced easily as prefabricated assembly; external wire-feeding manipulator not needed; and welding process relatively forgiving of operator error.

  15. 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.

  16. Simulation of Metal Flow During Friction Stir Welding Based on the Model of Interactive Force Between Tool and Material

    NASA Astrophysics Data System (ADS)

    Chen, G. Q.; Shi, Q. Y.; Fujiya, Y.; Horie, T.

    2014-04-01

    In this research, the three-dimensional flow of metal in friction stir welding (FSW) has been simulated based on computational fluid dynamics. Conservation equations of mass, momentum, and energy were solved in three dimensions. The interactive force was imposed as boundary conditions on the tool/material boundary in the model. The strain rate- and temperature-dependent non-Newtonian viscosity was adopted for the calculation of metal flow. The distribution of temperature, velocity, and strain rate were simulated based on the above models. The simulated temperature distribution agreed well with the experimental results. The simulation results showed that the velocity on the pin was much higher than that on the shoulder. From the comparison between the simulation results and the experiments results, contours line, corresponding to strain rate = 4 s-1, reflected reasonably well the shape of stir zone, especially at the ground portion.

  17. Physics of Fusion Welding

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.

    1986-01-01

    Applicabilities and limitations of three techniques analyzed. NASA technical memorandum discusses physics of electron-beam, gas/ tungsten-arc, and laser-beam welding. From comparison of capabilities and limitations of each technique with regard to various welding conditions and materials, possible to develop criteria for selecting best welding technique in specific application. All three techniques classified as fusion welding; small volume of workpiece melted by intense heat source. Heat source moved along seam, leaving in wake solid metal that joins seam edges together.

  18. Investigation of Friction Stir Welding of Al Metal Matrix Composite Materials

    NASA Technical Reports Server (NTRS)

    Diwan, Ravinder M.

    2003-01-01

    The innovative process of Friction Stir Welding (FSW) has generated tremendous interest since its inception about a decade or so ago since the first patent in 1991 by TWI of Cambridge, England. This interest has been seen in many recent international conferences and publications on the subject and relevant published literature. Still the process needs both intensive basic study of deformation mechanisms during this FSW process and analysis and feasibility study to evaluate production methods that will yield high quality strong welds from the stirring action of the appropriate pin tool into the weld plate materials. Development of production processes is a complex task that involves effects of material thickness, materials weldability, pin tool design, pin height, and pin shoulder diameter and related control conditions. The frictional heating with rotational speeds of the pin tool as it plunges into the material and the ensuing plastic flow arising during the traverse of the welding faying surfaces provide the known special advantages of the FSW process in the area of this new advanced joining technology.

  19. METAL FUSION AND FABRICATION WELDING. AGRICULTURAL MACHINERY--SERVICE OCCUPATIONS, MODULE, NUMBER 6.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Center for Vocational and Technical Education.

    ONE IN A SERIES DESIGNED TO HELP TEACHERS PREPARE POSTSECONDARY STUDENTS FOR THE AGRICULTURAL MACHINERY SERVICE OCCUPATIONS AS PARTS MEN, MECHANICS, MECHANIC'S HELPERS, OR SERVICE SUPERVISORS, THIS GUIDE AIMS TO DEVELOP STUDENT UNDERSTANDING OF WELDING EQUIPMENT AND SUPPLIES, AND ABILITY TO PERFORM SKILLS REQUIRED OF AGRICULTURAL MECHANICS. IT WAS…

  20. Deconvoluting the Friction Stir Weld Process for Optimizing Welds

    NASA Technical Reports Server (NTRS)

    Schneider, Judy; Nunes, Arthur C.

    2008-01-01

    In the friction stir welding process, the rotating surfaces of the pin and shoulder contact the weld metal and force a rotational flow within the weld metal. Heat, generated by the metal deformation as well as frictional slippage with the contact surface, softens the metal and makes it easier to deform. As in any thermo-mechanical processing of metal, the flow conditions are critical to the quality of the weld. For example, extrusion of metal from under the shoulder of an excessively hot weld may relax local pressure and result in wormhole defects. The trace of the weld joint in the wake of the weld may vary geometrically depending upon the flow streamlines around the tool with some geometry more vulnerable to loss of strength from joint contamination than others. The material flow path around the tool cannot be seen in real time during the weld. By using analytical "tools" based upon the principles of mathematics and physics, a weld model can be created to compute features that can be observed. By comparing the computed observations with actual data, the weld model can be validated or adjusted to get better agreement. Inputs to the model to predict weld structures and properties include: hot working properties ofthe metal, pin tool geometry, travel rate, rotation and plunge force. Since metals record their prior hot working history, the hot working conditions imparted during FSW can be quantified by interpreting the final microstructure. Variations in texture and grain size result from variations in the strain accommodated at a given strain rate and temperature. Microstructural data from a variety of FSWs has been correlated with prior marker studies to contribute to our understanding of the FSW process. Once this stage is reached, the weld modeling process can save significant development costs by reducing costly trial-and-error approaches to obtaining quality welds.