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Sample records for welded joints obtained

  1. Structure of welded joints obtained by contact weld in nanostructured titanium

    NASA Astrophysics Data System (ADS)

    Klimenov, V. A.; Klopotov, A. A.; Gnysov, S. F.; Vlasov, V. A.; Lychagin, D. V.; Chumaevskii, A. V.

    2015-10-01

    The paper presents the research of the weld structure of two Ti specimens of the type VT6 that have nano- and submicrocrystalline structures. Electrical contact welding is used to obtain welds. The acicular structure is formed in the weld area. Two types of defects are detected, namely micropores and microcracks.

  2. Plating To Reinforce Welded Joints

    NASA Technical Reports Server (NTRS)

    Otousa, J. E.

    1982-01-01

    Electrodeposition used to strengthen welded joints gouged, nicked, or suffered other mechanical damage. Plating cell, typically of acrylic plastic such as poly (Methylmetacrylate), is assembled around part to be plated. Areas not to be plated are masked with plater's tape. Weld area is plated in standard nickel-plating process.

  3. Flexible Protective Shield For Newly Welded Joints

    NASA Technical Reports Server (NTRS)

    Dyer, Gerald E.

    1988-01-01

    Simple device promotes defect-free welds in oxidation-prone metals. Welding torch pulls trailing shield behind to provide protective shield of argon gas over hot weld bead. Guide at front of torch holder feeds welding wire to joint. Shield bent or straightened to fit closely against weld joint.

  4. Pyrothermal treatment of welded joints

    SciTech Connect

    Serikov, S.V.; Idiyatullin, R.S.; Myakushkin, S.N.; Yaufman, V.V.

    1992-03-01

    The results of investigation of the structure and distribution of residual stresses in welded joints in pipes after heat treatment, which includes heating of the surface being treated due to combustion of plates formed from a thermite-type material of pyrotechnic composition, placed around the perimeter of the welded joint, and also an assessment of the level of residual stresses prior to and after pyrotechnic treatment demonstrated the promising nature of the proposed method. 5 refs., 5 figs.

  5. The technology and welding joint properties of hybrid laser-tig welding on thick plate

    NASA Astrophysics Data System (ADS)

    Shenghai, Zhang; Yifu, Shen; Huijuan, Qiu

    2013-06-01

    The technologies of autogenous laser welding and hybrid laser-TIG welding are used on thick plate of high strength lower alloy structural steel 10CrNiMnMoV in this article. The unique advantages of hybrid laser-TIG welding is summarized by comparing and analyzing the process parameters and welding joints of autogenous laser welding laser welding and hybrid laser-TIG welding. With the optimal process parameters of hybrid welding, the good welding joint without visible flaws can be obtained and its mechanical properties are tested according to industry standards. The results show that the hybrid welding technology has certain advantages and possibility in welding thick plates. It can reduce the demands of laser power, and it is significant for lowering the aspect ratio of weld during hybrid welding, so the gas in the molten pool can rise and escape easily while welding thick plates. Therefore, the pores forming tendency decreases. At the same time, hybrid welding enhances welding speed, and optimizes the energy input. The transition and grain size of the microstructure of hybrid welding joint is better and its hardness is higher than base material. Furthermore, its tensile strength and impact toughness is as good as base material. Consequently, the hybrid welding joint can meet the industry needs completely.

  6. Investigation of the structure and properties of titanium-stainless steel permanent joints obtained by laser welding with the use of intermediate inserts and nanopowders

    NASA Astrophysics Data System (ADS)

    Cherepanov, A. N.; Orishich, A. M.; Pugacheva, N. B.; Shapeev, V. P.

    2015-03-01

    Results of an experimental study of the structure, the phase composition, and the mechanical properties of laser-welded joints of 3-mm thick titanium and 12Kh18N10T steel sheets obtained with the use of intermediate inserts and nanopowdered modifying additives are reported. It is shown that that such parameters as the speed of welding, the radiation power, and the laser-beam focal spot position all exert a substantial influence on the welding-bath process and on the seam structure formed. In terms of chemical composition, most uniform seams with the best mechanical strength are formed at a 1-m/min traverse speed of laser and 2.35-kW laser power, with the focus having been positioned at the lower surface of the sheets. Under all other conditions being identical, uplift of the focus to workpiece surface or to a higher position results in unsteady steel melting, in a decreased depth and reduced degree of the diffusion-induced mixing of elements, and in an interpolate connection formed according to the soldering mechanism in the root portion of the seam. The seam material is an over-saturated copper-based solid solution of alloying elements with homogeneously distributed intermetallic disperse particles (Ti(Fe, Cr)2 and TiCu3) contained in this alloy. Brittle fracture areas exhibiting cleavage and quasi-cleavage facets correspond to coarse Ti(Fe, Cr)2 intermetallic particles or to diffusion zones primarily occurring at the interface with the titanium alloy. The reported data and the conclusions drawn from the numerical calculations of the thermophysical processes of welding of 3-mm thick titanium and steel sheets through an intermediate copper insert are in qualitative agreement with the experimental data. The latter agreement points to adequacy of the numerical description of the melting processes of contacting materials versus welding conditions and focal-spot position in the system.

  7. Microstructure and Properties Analysis of Laser Welding and Laser Weld Bonding Mg to Al Joints

    NASA Astrophysics Data System (ADS)

    Liu, Liming; Wang, Hongyang

    2011-04-01

    Laser welding and laser weld bonding (LWB) Mg to Al joints were obtained in different welding parameters. The penetrations and microstructures of these kinds of joints changed with the increasing of pulse laser power density. Both laser welding and LWB Mg to Al joints with the best properties were obtained in conductive welding mode. In laser welding Mg to Al joint, several intermetallics formed at the bottom of the fusion zone, where some cracks were generated. In laser weld bonding Mg to Al joint, the decomposition of the adhesive caused a baffle effect on the diffusion between the Mg and the Al. The intermetallics formed in the middle of the fusion zone, and the thickness of Mg17Al12 layer was approximately 10 to 20 ?m and the Mg2Al3 layer was less than 5 ?m, which influenced the property of the joint less.

  8. The distinctive feature of weld joints structure by adding the nanomodifying to the weld pool

    NASA Astrophysics Data System (ADS)

    Shlyakhova, Galina; Danilov, Vladimir; Kuznetsov, Maxim; Zernin, Evgeny; Kartashov, Evgeny

    2015-10-01

    The experimental studies were carried on for the test samples of welds of the steel 12X18H10T; the results are presented. The effect produced by the nanostructured modifying powders added to the weld pool on the quality of weld joints was examined. The weld joints were obtained by arc welding in argon atmosphere using consumable electrode. Due to the weld pool modification, the dendrite size was found to decrease and a more equilibrium microstructure would form in the weld material.

  9. Fracturing behavior of aluminum alloys with welded joints

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  10. Improving Joint Properties of Friction Welded Joint of High Tensile Steel

    NASA Astrophysics Data System (ADS)

    Kimura, Masaaki; Kusaka, Masahiro; Seo, Kenji; Fuji, Akiyoshi

    This report describes the improvements in the joint properties of friction welded joint of 780MPa class high tensile steel. Welded joint made by a continuous drive friction welding machine, the conventional method, had not obtained 100% joint efficiency despite applying forge pressure. This was due to the softening of the welded interface zone for heat input during braking times. Therefore, we developed a continuous drive friction welding machine with an electromagnetic clutch to prevent heat input during braking time. We proposed the process as “The Low Heat Input Friction Welding Method (the LHI method).” In this case, the joint had the same tensile strength as the base metal at friction time when the friction torque reached the initial peak torque. That is, the welded joint obtained 100% joint efficiency by using only the friction stage up to the initial peak torque without the forge (upsetting) stage, despite the existence of a slightly softened region adjacent to the welded interface. Furthermore, the softened region was hardly generated when this joint was made by applying forge pressure at the initial peak torque. In conclusion, a welded joint of high tensile steel made by only the friction stage of the LHI method had excellent joint properties. The LHI method has a lot of advantages for joining such materials as super fine grain steel with which conventional fusion welding processes have difficulty.

  11. Strength of Welded Aircraft Joints

    NASA Technical Reports Server (NTRS)

    Brueggeman, W C

    1937-01-01

    This investigation is a continuation of work started in 1928 and described in NACA-TR-348 which shows that the insertion of gusset plates was the most satisfactory way of strengthening a joint. Additional tests of the present series show that joints of this type could be improved by cutting out the portion of the plate between the intersecting tubes. T and lattice joints in thin-walled tubing 1 1/2 by 0.020 inch have somewhat lower strengths than joints in tubing of greater wall thickness because of failure by local buckling. In welding the thin-walled tubing, the recently developed "carburizing flux" process was found to be the only method capable of producing joints free from cracks. The "magnetic powder" inspection was used to detect cracks in the joints and flaws in the tubing.

  12. Polyimide weld bonding for titanium alloy joints

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

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

  13. Measurement of micro weld joint position based on magneto-optical imaging

    NASA Astrophysics Data System (ADS)

    Gao, Xiang-Dong; Chen, Zi-Qin

    2015-01-01

    In a laser butt joint welding process, it is required that the laser beam focus should be controlled to follow the weld joint path accurately. Small focus wandering off the weld joint may result in insufficient penetration or unacceptable welds. Recognition of joint position offset, which describes the deviation between the laser beam focus and the weld joint, is important for adjusting the laser beam focus and obtaining high quality welds. A new method based on the magneto-optical (MO) imaging is applied to measure the micro weld joint whose gap is less than 0.2 mm. The weldments are excited by an external magnetic field, and an MO sensor based on principle of Faraday magneto effect is used to capture the weld joint images. A sequence of MO images which are tested under different magnetic field intensities and different weld joint widths are acquired. By analyzing the MO image characteristics and extracting the weld joint features, the influence of magnetic field intensity and weld joint width on the MO images and detection of weld joint position is observed and summarized. Project supported by the National Natural Science Foundation of China (Grant No. 51175095), the Natural Science Foundation of Guangdong Province, China (Grant No. 10251009001000001), the Guangdong Provincial Project of Science and Technology Innovation of Discipline Construction, China (Grant No. 2013KJCX0063), and the Science and Technology Plan Project of Guangzhou City, China (Grant No. 1563000554).

  14. Microstructure of AA 2024 fixed joints formed by friction stir welding

    NASA Astrophysics Data System (ADS)

    Eliseev, A. A.; Kalashnikova, T. A.; Tarasov, S. Yu.; Rubtsov, V. E.; Fortuna, S. V.; Kolubaev, E. A.

    2015-10-01

    Friction stir welded butt joints on 2024T3 alloy have been obtained using different process parameters. The microstructures of all the weld joint zones have been examined and such structural parameters as grain size, particle size and volume content of particles have been determined in order to find correlations with the microhardness of the corresponding zones of the weld.

  15. Welding technology transfer task/laser based weld joint tracking system for compressor girth welds

    NASA Technical Reports Server (NTRS)

    Looney, Alan

    1991-01-01

    Sensors to control and monitor welding operations are currently being developed at Marshall Space Flight Center. The laser based weld bead profiler/torch rotation sensor was modified to provide a weld joint tracking system for compressor girth welds. The tracking system features a precision laser based vision sensor, automated two-axis machine motion, and an industrial PC controller. The system benefits are elimination of weld repairs caused by joint tracking errors which reduces manufacturing costs and increases production output, simplification of tooling, and free costly manufacturing floor space.

  16. Virtual Welded-Joint Design Integrating Advanced Materials and Processing Technologies

    SciTech Connect

    Yang, Z.; Dong, P.; Liu, S.; Babu, S.; Olson, G.; DebRoy, T.

    2005-04-15

    The primary goal of this project is to increase the fatigue life of a welded-joint by 10 times and to reduce energy use by 25% through product performance and productivity improvements using an integrated modeling approach. The fatigue strength of a welded-joint is currently the bottleneck to design high performance and lightweight welded structures using advanced materials such as high strength steels. In order to achieve high fatigue strength in a welded-joint it is necessary to manage the weld bead shape for lower stress concentration, produce preferable residual stress distribution, and obtain the desired microstructure for improved material toughness and strength. This is a systems challenge that requires the optimization of the welding process, the welding consumable, the base material, as well as the structure design. The concept of virtual welded-joint design has been proposed and established in this project. The goal of virtual welded-joint design is to develop a thorough procedure to predict the relationship of welding process, microstructure, property, residual stress, and the ultimate weld fatigue strength by a systematic modeling approach. The systematic approach combines five sub-models: weld thermal-fluid model, weld microstructure model, weld material property model, weld residual stress model, and weld fatigue model. The systematic approach is thus based on interdisciplinary applied sciences including heat transfer, computational fluid dynamics, materials science, engineering mechanics, and material fracture mechanics. The sub-models are based on existing models with further development. The results from modeling have been validated with critical experiments. The systematic modeling approach has been used to design high fatigue resistant welds considering the combined effects of weld bead geometry, residual stress, microstructure, and material property. In particular, a special welding wire has been developed in this project to introduce compressive residual stress at weld toe for weld fatigue resistance.

  17. Low Distortion Welded Joints for NCSX

    SciTech Connect

    M. Denault, M Viola, W. England

    2009-02-19

    The National Compact Stellarator Experiment (NCSX) required precise positioning of the field coils in order to generate suitable magnetic fields. A set of three modular field coils were assembled to form the Half Field-Period Assemblies (HPA). Final assembly of the HPA required a welded shear plate to join individual coils in the nose region due to the geometric limitations and the strength constraints. Each of the modular coil windings was wound on a stainless steel alloy (Stellalloy) casting. The alloy is similar to austenitic 316 stainless steel. During the initial welding trials, severe distortion, of approximately 1/16", was observed in the joint caused by weld shrinkage. The distortion was well outside the requirements of the design. Solutions were attempted through several simultaneous routes. The joint design was modified, welding processes were changed, and specialized heat reduction techniques were utilized. A final joint design was selected to reduce the amount of weld material needed to be deposited, while maintaining adequate penetration and strength. Several welding processes and techniques using Miller Axcess equipment were utilized that significantly reduced heat input. The final assembly of the HPA was successful. Distortion was controlled to 0.012", well within the acceptable design tolerance range of 0.020" over a 3.5 foot length.

  18. Method of making an explosively welded scarf joint

    NASA Technical Reports Server (NTRS)

    Bement, L. J. (inventor)

    1974-01-01

    A method is presented for obtaining a bond joint between thin metal members without the addition of a bonding agent. The method yields bond strengths comparable to the parent metal. The method comprises overlapping the materials at the edges and bonding them by explosive welding while also making use of the explosive force to shape the materials into an essentially planar configuration.

  19. Investigation of weld joint detection capabilities of a coaxial weld vision system

    NASA Technical Reports Server (NTRS)

    Gangl, K. J.; Weeks, J. L.

    1985-01-01

    This report describes the second phase of a series of evaluations of a vision-based welding control sensor for the Space shuttle Main Engine Robotic Welding System. The robotic welding system is presently under development at the Marshall Space Flight Center. This evaluation determines the factors influencing the minimum joint gap required for consistent detection of the weld joint.

  20. Diffusion welding in air. [solid state welding of butt joint by fusion welding, surface cleaning, and heating

    NASA Technical Reports Server (NTRS)

    Moore, T. J.; Holko, K. H. (inventors)

    1974-01-01

    Solid state welding a butt joint by fusion welding the peripheral surfaces to form a seal is described along with, autogenetically cleaning the faying or mating surfaces of the joint by heating the abutting surfaces to 1,200 C and heating to the diffusion welding temperature in air.

  1. 78 FR 47486 - Joint Failure on Continuous Welded Rail Track

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-05

    ... Federal Railroad Administration Joint Failure on Continuous Welded Rail Track AGENCY: Federal Railroad..., internal continuous welded rail (CWR) plans and properly inspecting CWR joints to identify and correct locations that indicate potential joint failure that may cause a derailment. FRA is issuing this notice...

  2. 49 CFR 195.216 - Welding: Miter joints.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Transportation 3 2011-10-01 2011-10-01 false Welding: Miter joints. 195.216 Section 195.216 Transportation...HAZARDOUS LIQUIDS BY PIPELINE Construction § 195.216 Welding: Miter joints. A miter joint is not permitted (not...

  3. 49 CFR 195.216 - Welding: Miter joints.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...Transportation 3 2014-10-01 2014-10-01 false Welding: Miter joints. 195.216 Section 195.216 Transportation...HAZARDOUS LIQUIDS BY PIPELINE Construction § 195.216 Welding: Miter joints. A miter joint is not permitted (not...

  4. 49 CFR 195.216 - Welding: Miter joints.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...Transportation 3 2013-10-01 2013-10-01 false Welding: Miter joints. 195.216 Section 195.216 Transportation...HAZARDOUS LIQUIDS BY PIPELINE Construction § 195.216 Welding: Miter joints. A miter joint is not permitted (not...

  5. 49 CFR 195.216 - Welding: Miter joints.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...Transportation 3 2012-10-01 2012-10-01 false Welding: Miter joints. 195.216 Section 195.216 Transportation...HAZARDOUS LIQUIDS BY PIPELINE Construction § 195.216 Welding: Miter joints. A miter joint is not permitted (not...

  6. 49 CFR 195.216 - Welding: Miter joints.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Transportation 3 2010-10-01 2010-10-01 false Welding: Miter joints. 195.216 Section 195.216 Transportation...HAZARDOUS LIQUIDS BY PIPELINE Construction § 195.216 Welding: Miter joints. A miter joint is not permitted (not...

  7. 49 CFR 195.216 - Welding: Miter joints.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Welding: Miter joints. 195.216 Section 195.216 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... PIPELINE Construction § 195.216 Welding: Miter joints. A miter joint is not permitted (not...

  8. 49 CFR 195.216 - Welding: Miter joints.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Welding: Miter joints. 195.216 Section 195.216 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... PIPELINE Construction § 195.216 Welding: Miter joints. A miter joint is not permitted (not...

  9. 49 CFR 195.216 - Welding: Miter joints.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Welding: Miter joints. 195.216 Section 195.216 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... PIPELINE Construction § 195.216 Welding: Miter joints. A miter joint is not permitted (not...

  10. 49 CFR 195.216 - Welding: Miter joints.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Welding: Miter joints. 195.216 Section 195.216 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... PIPELINE Construction § 195.216 Welding: Miter joints. A miter joint is not permitted (not...

  11. 49 CFR 195.216 - Welding: Miter joints.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Welding: Miter joints. 195.216 Section 195.216 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... PIPELINE Construction § 195.216 Welding: Miter joints. A miter joint is not permitted (not...

  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. Influence of Protective Gas Content on Quality of Welded Joint While Welding With Impulse Supply of Electrode Wire

    NASA Astrophysics Data System (ADS)

    Pavlov, N. V.; Kryukov, A. V.; Zernin, E. A.; Gritsenko, V. V.

    2015-09-01

    Currently one of the advanced ways of obtaining quality welded joint while welding of medium alloy martensitic-bainitic steel is the one with impulse supply of electrode wire in gas mixture Ar(70%±3%)+C02(30%±3%). Results of experimental studies proved that application of protective gas Ar(70%±3%)+C02(30%±3%) in comparison with CO2(100%) enables to increase strength properties of the welded joint by 10-15% and enlarge the transition coefficient of chemical elements.

  14. Virtual Welded - Joint Design Integrating Advanced Materials and Processing Technology

    SciTech Connect

    Yang, Zhishang; Ludewig, Howard W.; Babu, S. Suresh

    2005-06-30

    Virtual Welede-Joint Design, a systematic modeling approach, has been developed in this project to predict the relationship of welding process, microstructure, properties, residual stress, and the ultimate weld fatique strength. This systematic modeling approach was applied in the welding of high strength steel. A special welding wire was developed in this project to introduce compressive residual stress at weld toe. The results from both modeling and experiments demonstrated that more than 10x fatique life improvement can be acheived in high strength steel welds by the combination of compressive residual stress from the special welding wire and the desired weld bead shape from a unique welding process. The results indicate a technology breakthrough in the design of lightweight and high fatique performance welded structures using high strength steels.

  15. Corrosion and Mechanical Properties of Austenic Steel Weld Joints

    NASA Astrophysics Data System (ADS)

    Kuznetsov, M. A.; Zernin, E. A.; Danilov, V. I.; Kolmogorov, D. E.; Zoubenko, L. N.

    2015-09-01

    This paper presents results of experiments on how tungsten, molybdenum and aluminum oxyhydroxide nanopowders, imbedded into the weld pool, affect corrosion resistance and mechanical properties of welded joints. It is shown that nanopowders have a significant effect on the intergranular corrosion of the weld.

  16. Yield detection in aluminum welded joints using photostress

    NASA Technical Reports Server (NTRS)

    Gambrell, S. C., Jr.; Kavikondala, K.

    1994-01-01

    Previous work using photostress to analyze behavior of aluminum welded joints was useful to determine mechanical properties of the weld and parent materials along the centerline of the joint. It was shown that significant differences exist in the stress-strain characteristics at points beginning at the centerline of the weld and extending for a distance of one inch to either side of the weld. Because of the highly variable behavior detected in the previous work, it was decided to extend the work to investigate behavior of joints 1/8, 1/2, and 1.40 inches thick.

  17. A study of the role of adhesives in weld-bonded joints

    SciTech Connect

    Chang, B.H. . School of Mechanical Engineering); Shi, Y.W. . School of Materials Science and Engineering); Dong, S.J. . Materials Dept.)

    1999-08-01

    Using a three-dimensional finite element analysis (FEA) method, the effect of elastic modulus and thickness of adhesives on the stress distribution in weld-bonded joints was studied to address the role of adhesive layer. Normal stress and shear stress distributed at the edges of a spot weld and in the lap region were computed for weld-bonded joints made with adhesives of different elastic moduli or thicknesses. The results showed great stress concentration at the edge of the spot weld in weld-bonded joints when the adhesive layer was thick or had a low elastic modulus. Shear stress values in adhesive layers were low under the same circumstances. Stress concentration around the spot weld was reduced and the shear stress in the adhesive layer was increased by increasing the elastic modulus or decreasing the thickness of the adhesive layer. An adhesive layer with appropriate thickness and elastic modulus is necessary to obtain reasonable distribution of stresses in the whole lap region of a weld-bonded joint. A thin adhesive layer of high elastic modulus is favorable to the fatigue properties of weld-bonded joints, and it is recommended on certain conditions.

  18. Investigation of Torsional Strength of the VT6 Weld Joint Produced by Linear Friction Welding

    NASA Astrophysics Data System (ADS)

    Suleimanova, G. R.; Kabirov, R. R.; Karavaeva, M. V.; Ershova, Yu. A.; Zhilyaev, A. P.

    2015-10-01

    Results of measurement of torsional strength of the weld joint of the VT6 titanium alloy produced by linear friction welding are presented. For a comparison, the same method was used to test monolithic specimens of the VT6 alloy. Torsional strength values of the weld joint (?US = 861 MPa and ? = 110°) correspond to the strength of the monolithic material. In this case, the specimens fail along the base metal.

  19. Predicting welding distortion in a panel structure with longitudinal stiffeners using inherent deformations obtained by inverse analysis method.

    PubMed

    Liang, Wei; Murakawa, Hidekazu

    2014-01-01

    Welding-induced deformation not only negatively affects dimension accuracy but also degrades the performance of product. If welding deformation can be accurately predicted beforehand, the predictions will be helpful for finding effective methods to improve manufacturing accuracy. Till now, there are two kinds of finite element method (FEM) which can be used to simulate welding deformation. One is the thermal elastic plastic FEM and the other is elastic FEM based on inherent strain theory. The former only can be used to calculate welding deformation for small or medium scale welded structures due to the limitation of computing speed. On the other hand, the latter is an effective method to estimate the total welding distortion for large and complex welded structures even though it neglects the detailed welding process. When the elastic FEM is used to calculate the welding-induced deformation for a large structure, the inherent deformations in each typical joint should be obtained beforehand. In this paper, a new method based on inverse analysis was proposed to obtain the inherent deformations for weld joints. Through introducing the inherent deformations obtained by the proposed method into the elastic FEM based on inherent strain theory, we predicted the welding deformation of a panel structure with two longitudinal stiffeners. In addition, experiments were carried out to verify the simulation results. PMID:25276856

  20. Predicting Welding Distortion in a Panel Structure with Longitudinal Stiffeners Using Inherent Deformations Obtained by Inverse Analysis Method

    PubMed Central

    Liang, Wei; Murakawa, Hidekazu

    2014-01-01

    Welding-induced deformation not only negatively affects dimension accuracy but also degrades the performance of product. If welding deformation can be accurately predicted beforehand, the predictions will be helpful for finding effective methods to improve manufacturing accuracy. Till now, there are two kinds of finite element method (FEM) which can be used to simulate welding deformation. One is the thermal elastic plastic FEM and the other is elastic FEM based on inherent strain theory. The former only can be used to calculate welding deformation for small or medium scale welded structures due to the limitation of computing speed. On the other hand, the latter is an effective method to estimate the total welding distortion for large and complex welded structures even though it neglects the detailed welding process. When the elastic FEM is used to calculate the welding-induced deformation for a large structure, the inherent deformations in each typical joint should be obtained beforehand. In this paper, a new method based on inverse analysis was proposed to obtain the inherent deformations for weld joints. Through introducing the inherent deformations obtained by the proposed method into the elastic FEM based on inherent strain theory, we predicted the welding deformation of a panel structure with two longitudinal stiffeners. In addition, experiments were carried out to verify the simulation results. PMID:25276856

  1. Structure and properties of fixed joints formed by ultrasonic-assisted friction-stir welding

    NASA Astrophysics Data System (ADS)

    Fortuna, S. V.; Ivanov, K. V.; Tarasov, S. Yu.; Eliseev, A. A.; Ivanov, A. N.; Rubtsov, V. E.; Kolubaev, E. A.

    2015-10-01

    This paper deals with structure and properties of aluminum alloy 7475 and its joints obtained by friction stir welding including under ultrasonic action. Microhardness measurements show that ultrasonic action increases strength properties of the joints. Optical and transmission electron microscopy reveals that this effect is related to the precipitation of tertiary coherent S-and T-phase particles.

  2. Detection of micro-weld joint by magneto-optical imaging

    NASA Astrophysics Data System (ADS)

    Gao, Xiangdong; Liu, Yonghua; You, Deyong

    2014-10-01

    It is required that the laser beam focus should be controlled to accurately follow the weld joint center during laser butt joint welding; therefore, the weld joint position must be detected automatically in real-time. An approach for detecting the micro-weld joint (weld gap less than 0.1 mm) based on magneto-optical (MO) imaging is investigated during laser butt-joint welding of low carbon steel. Magneto-optical sensor was used to capture the dynamic images of weld joint. Weld MO image gray distribution features were analyzed to extract the transition zone of weld joint. The influences of a different magnetic field intensity and the welding speed on detecting the weld joint position were mainly studied. Under different welding conditions where welding path, weld gap or welding speed varies, it has been found that using magneto-optic imaging technology could effectively detect the position of the micro-weld joint. Different weld joint positions in MO images have been detected with various magnetic field intensities. Experimental results show that the welding speed has little influence on the detection of weld joint position.

  3. Microstructure and mechanical properties of the welding joint filled with microalloying 5183 aluminum welding wires

    NASA Astrophysics Data System (ADS)

    Xu, Zhen; Zhao, Zhi-hao; Wang, Gao-song; Zhang, Chao; Cui, Jian-zhong

    2014-06-01

    In this study, 7A52 aluminum alloy sheets of 4 mm in thickness were welded by tungsten inert gas welding using microalloying welding wires containing traces of Zr and Er. The influence of rare earth elements Zr and Er on the microstructure and mechanical properties of the welded joints was analyzed by optical microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, hardness testing, and tensile mechanical properties testing. Systematic analyses indicate that the addition of trace amounts of Er and Zr leads to the formation of fine Al3Er, Al3Zr, and Al3(Zr,Er) phases that favor significant grain refinement in the weld zone. Besides, the tensile strength and hardness of the welded joints were obviously improved with the addition of Er and Zr, as evidenced by the increase in tensile strength and elongation by 40 MPa and 1.4%, respectively, and by the welding coefficient of 73%.

  4. An inelastic analysis of a welded aluminum joint

    NASA Technical Reports Server (NTRS)

    Vaughan, R. E.

    1994-01-01

    Butt-weld joints are most commonly designed into pressure vessels which then become as reliable as the weakest increment in the weld chain. In practice, weld material properties are determined from tensile test specimen and provided to the stress analyst in the form of a stress versus strain diagram. Variations in properties through the thickness of the weld and along the width of the weld have been suspect but not explored because of inaccessibility and cost. The purpose of this study is to investigate analytical and computational methods used for analysis of welds. The weld specimens are analyzed using classical elastic and plastic theory to provide a basis for modeling the inelastic properties in a finite-element solution. The results of the analysis are compared to experimental data to determine the weld behavior and the accuracy of prediction methods. The weld considered in this study is a multiple-pass aluminum 2219-T87 butt weld with thickness of 1.40 in. The weld specimen is modeled using the finite-element code ABAQUS. The finite-element model is used to produce the stress-strain behavior in the elastic and plastic regimes and to determine Poisson's ratio in the plastic region. The value of Poisson's ratio in the plastic regime is then compared to experimental data. The results of the comparisons are used to explain multipass weld behavior and to make recommendations concerning the analysis and testing of welds.

  5. Limit load solution for electron beam welded joints with single edge weld center crack in tension

    NASA Astrophysics Data System (ADS)

    Lu, Wei; Shi, Yaowu; Li, Xiaoyan; Lei, Yongping

    2012-05-01

    Limit loads are widely studied and several limit load solutions are proposed to some typical geometry of weldments. However, there are no limit load solutions exist for the single edge crack weldments in tension (SEC(T)), which is also a typical geometry in fracture analysis. The mis-matching limit load for thick plate with SEC(T) are investigated and the special limit load solutions are proposed based on the available mis-matching limit load solutions and systematic finite element analyses. The real weld configurations are simplified as a strip, and different weld strength mis-matching ratio M, crack depth/width ratio a/ W and weld width 2H are in consideration. As a result, it is found that there exists excellent agreement between the limit load solutions and the FE results for almost all the mis-matching ration M, a/ W and ligament-to-weld width ratio ( W-a)/ H. Moreover, useful recommendations are given for evaluating the limit loads of the EBW structure with SEC(T). For the EBW joints with SEC(T), the mis-matching limit loads can be obtained assuming that the components are wholly made of base metal, when M changing from 1.6 to 0.6. When M decreasing to 0.4, the mis-matching limit loads can be obtained assuming that the components are wholly made of base metal only for large value of ( W-a)/ H. The recommendations may be useful for evaluating the limit loads of the EBW structures with SEC(T). The engineering simplifications are given for assessing the limit loads of electron beam welded structure with SEC(T).

  6. 46 CFR 154.524 - Piping joints: Welded and screwed couplings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) An inert gas back-up on the first weld pass. (b) A slip-on welded joint with sleeves and attachment... lengths without flanges must be joined by one of the following: (a) A butt welded joint with complete penetration at the weld root except that for design temperatures colder than ?10 °C (14 °F) the butt weld...

  7. Apparatus for maintaining aligment of a shrinking weld joint in an electron-beam welding operation

    DOEpatents

    Trent, J.B.; Murphy, J.L.

    1980-01-03

    The invention is directed to an apparatus for automatically maintaining a shrinking weld joint in alignement with an electron beam during an electron-beam multipass-welding operation. The apparatus utilizes a bias means for continually urging a workpiece-supporting face plate away from a carriage mounted base that rotatably supports the face plate. The extent of displacement of the face plate away from the base in indicative of the shrinkage occuring in the weld joint area. This displacement is measured and is used to move the base on the carriage a distance equal to one-half the displacement for aligning the weld joint with the electron beam during each welding pass.

  8. Apparatus for maintaining alignment of a shrinking weld joint in an electron-beam welding operation

    DOEpatents

    Trent, Jett B. (Knoxville, TN); Murphy, Jimmy L. (Oak Ridge, TN)

    1981-01-01

    The present invention is directed to an apparatus for automatically maintaining a shrinking weld joint in alignment with an electron beam during an electron-beam multipass-welding operation. The apparatus utilizes a biasing device for continually urging a workpiece-supporting face plate away from a carriage mounted base that rotatably supports the face plate. The extent of displacement of the face plate away from the base is indicative of the shrinkage occuring in the weld joint area. This displacement is measured and is used to move the base on the carriage a distance equal to one-half the displacement for aligning the weld joint with the electron beam during each welding pass.

  9. Reduced heat input keyhole welding through improved joint design

    NASA Technical Reports Server (NTRS)

    Sanders, John M. (Inventor); Harwig, Dennis D. (Inventor)

    1993-01-01

    An improved high energy density welding method for reducing input keyhole welding prepares the weld joint (8) between two edges (10, 14) of at least one member by separating the edges (10, 14) of the member (12, 16) with a controllable gap (22) by a projecting portion (24) selectively positioned on one edge (10, 14) of the member (12, 16). The projecting portion (24) closely abuts the other edge of the member for maintaining the controlled distance (d) of the controllable gap (22) to enhance the welding method.

  10. Effect of Nanopowder Modifiers on Properties of Metal Laser-welded Joints

    NASA Astrophysics Data System (ADS)

    Orishich, A. M.; Malikov, A. G.; Cherepanov, A. N.

    Re-sults of experimental studies of nano-sized refractory compounds impact on structural and mechanical characteristics of a joint obtained by CO2 laser welding of metal plates are presented. Introduction of small quantity of specially prepared refractory nanoparticles with size less than 100 nm is shown to impact the alloy crystallization process, form fine-dispersed globular structure at its solidification. This results in increase of mechanical and operational properties of the weld seam.

  11. Mechanical and structural characteristics of commercially pure grade 2 Ti welds and solder joints.

    PubMed

    Anselm Wiskott, H W; Doumas, T; Scherrer, S S; Belser, U C; Susz, C

    2001-08-01

    This study aimed at determining whether data previously gathered for a laser welds and IR brazings using a Au-Pd alloy were applicable to titanium joints. As to its resistance under fatigue loading, Au-Pd alloy had shown a poor response to pre-ceramic laser welding and post-ceramic brazing. The present study was designed to assess the mechanical resistance, the microstructure and the elemental diffusion of laser welded, electric arch welded and brazed joints using commercially pure titanium as substrate metal. Mechanical resistance was determined by determining the joints' ultimate tensile strength and their resistance to fatigue loading. Elemental diffusion to and from the joints was assessed using microprobe tracings. Optical micrographs of the joints were also obtained and evaluated. Under monotonic tensile stress, three groups emerged: (1) the GTAW and the native (i.e. as received) substrate, (2) the annealed substrate and the laser welds and (3) the brazed joints. Under fatigue stress, the order was: first the native and annealed substrate, second the brazings and laser welds, third the GTAW joints. No Au-filler brazing withstood the applied fatigue loading. The micrographs showed various patterns, an absence of HAZ cracking and several occurrences of Widmanstätten structures. Elemental diffusion to and from the Ti substrate was substantial in the Ti filler brazings and virtually nil in the Au-based brazings. Under fatigue stress application, the titanium-based brazings as well as the laser- and electric arc welds performed equally well if not better than a previously tested AuPd alloy. There was a definite increase in grain size with increased heat application. However, no feature of the microstructures observed or the elemental analysis could be correlated with the specimen's resistance to fatigue stress application. PMID:15348244

  12. Portable power tool machines weld joints in field

    NASA Technical Reports Server (NTRS)

    Spier, R. A.

    1966-01-01

    Portable routing machine for cutting precise weld joints required by nonstandard pipe sections used in the field for transfer of cryogenic fluids. This tool is adaptable for various sizes of pipes and has a selection of router bits for different joint configurations.

  13. Characterization of Nitinol Laser-Weld Joints by Nondestructive Testing

    NASA Astrophysics Data System (ADS)

    Wohlschlögel, Markus; Gläßel, Gunter; Sanchez, Daniela; Schüßler, Andreas; Dillenz, Alexander; Saal, David; Mayr, Peter

    2015-11-01

    Joining technology is an integral part of today's Nitinol medical device manufacturing. Besides crimping and riveting, laser welding is often applied to join components made from Nitinol to Nitinol, as well as Nitinol components to dissimilar materials. Other Nitinol joining techniques include adhesive bonding, soldering, and brazing. Typically, the performance of joints is assessed by destructive mechanical testing, on a process validation base. In this study, a nondestructive testing method—photothermal radiometry—is applied to characterize small Nitinol laser-weld joints used to connect two wire ends via a sleeve. Two different wire diameters are investigated. Effective joint connection cross sections are visualized using metallography techniques. Results of the nondestructive testing are correlated to data from destructive torsion testing, where the maximum torque at fracture is evaluated for the same joints and criteria for the differentiation of good and poor laser-welding quality by nondestructive testing are established.

  14. Strength of Welded Joints in Tubular Members for Aircraft

    NASA Technical Reports Server (NTRS)

    Whittemore, H L; Brueggeman, W C

    1931-01-01

    The object of this investigation is to make available to the aircraft industry authoritative information on the strength, weight, and cost of a number of types of welded joints. This information will, also, assist the aeronautics branch in its work of licensing planes by providing data from which the strength of a given joint may be estimated. As very little material on the strength of aircraft welds has been published, it is believed that such tests made by a disinterested governmental laboratory should be of considerable value to the aircraft industry. Forty joints were welded under procedure specifications and tested to determine their strengths. The weight and time required to fabricate were also measured for each joint.

  15. 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.

  16. Numerical Simulation of Tension Properties for Al-Cu Alloy Friction Stir-Welded Joints with GTN Damage Model

    NASA Astrophysics Data System (ADS)

    Sun, Guo-Qin; Sun, Feng-Yang; Cao, Fang-Li; Chen, Shu-Jun; Barkey, Mark E.

    2015-11-01

    The numerical simulation of tensile fracture behavior on Al-Cu alloy friction stir-welded joint was performed with the Gurson-Tvergaard-Needleman (GTN) damage model. The parameters of the GTN model were studied in each region of the friction stir-welded joint by means of inverse identification. Based on the obtained parameters, the finite element model of the welded joint was built to predict the fracture behavior and tension properties. Good agreement can be found between the numerical and experimental results in the location of the tensile fracture and the mechanical properties.

  17. Toughness evaluation of a shielded metal arc carbon-manganese steel welded joint subjected to multiple post weld heat treatment

    SciTech Connect

    Bott, I.S.; Teixeira, J.C.G.

    1999-12-01

    This study was part of a program to investigate the influence of multiple post weld heat treatment (PWHT) on the fracture toughness and defect tolerance of a welded joint. The present work reports base metal data obtained for a quenched and tempered BS7191 Grade 450EM steel (0.10wt%C-1.08wt%Mn), weld metal data for a ferritic multipass weld obtained by shielded metal arc welding using an AWS E-9018M type electrode, and heat affected zone (HAZ) data obtained using a modified bead on groove technique for different PWHT conditions. The effect of the repeated heat treatment cycles on the mechanical properties was evaluated by hardness tests and toughness testing assessed by Charpy V-notch and crack tip opening displacement (CTOD) techniques. The characterization of the microstructure was undertaken utilizing optical and electron microscopy. As fabrication codes for new equipment do not allow more than three PWHT cycles, the application of more cycles is only justifiable for old equipment when a fitness for purpose criterion is applied and these restrictions are not applicable. The results obtained are currently applied in repair work and revamps of pressure vessels and gas storage tanks.

  18. Tensile strength of simulated and welded butt joints in W-Cu composite sheet

    NASA Technical Reports Server (NTRS)

    Moore, Thomas J.; Watson, Gordon K.

    1994-01-01

    The weldability of W-Cu composite sheet was investigated using simulated and welded joints. The welded joints were produced in a vacuum hot press. Tensile test results showed that simulated joints can provide strength and failure mode data which can be used in joint design for actual weldments. Although all of the welded joints had flaws, a number of these joints were as strong as the W-Cu composite base material.

  19. Explosive Welding of Tubular Configurated Joints for Critical Applications

    NASA Technical Reports Server (NTRS)

    Hardwick, R.

    1985-01-01

    Explosive welding can provide the answer to problems of permanently joining metals typically used in the aerospace industry. The explosive bonding process is a solid state bonding process enabling material incompatibility problems associated with fusion welding to be overcome. In addition, heat affected zones are eliminated thus, enhancing joint strength, properties and performance. The process requires the parts being joined to be impelled, by means of explosives, to collide with each other. Certain critical collision parameters must be met and controlled and these parameters are defined. Various component geometries which satisfy the collision parameters are described. Examples of transition joints used in the aerospace industry are described and illustrated.

  20. Superconducting properties of ultra-pure niobium welded joints

    NASA Astrophysics Data System (ADS)

    Demyanov, S. E.; Kaniukov, E. Yu.; Pobol, I. L.; Yurevich, S. V.; Baturitsky, M. A.; Shirkov, G. D.; Budagov, Yu. A.; Demin, D. L.; Azaryan, N. S.

    2015-07-01

    An optimal electron-beam welding operating regime for ultra-pure sheet niobium has been developed for use in a superconducting resonator for the International Linear Collider (ILC). The formation of weld joints is studied and their microstructure and microhardness are investigated taking the required geometry of the weld seams into account. Low-temperature electrical measurements in magnetic fields up to 2 T are used to determine the critical parameters of the superconducting transition in the weld area. From the standpoint of the superconducting properties of the resonator, the slight degradation in the characteristics of sheet niobium observed in the thermally affected area (about 10% on average) is not of fundamental importance.

  1. Thermoacoustic method for relaxation of residual stresses in welded joints

    SciTech Connect

    Koshovyi, V.V.; Pakhn`o, M.I.; Tsykhan, O.I.

    1995-01-01

    We propose a thermoacoustic method for the relaxation of residual stresses in welded joints, present a block diagram of a generator of local thermoacoustic pulses designed for implementation of this method, and describe our experiment aimed at relaxation of residual tensile stresses.

  2. 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.

  3. Influence of the Strength Mismatch of a Narrow Gap Welded Joint of SA508 on the Plastic ? Factor

    NASA Astrophysics Data System (ADS)

    Koo, J. M.; Huh, Y.; Seok, C. S.

    2012-11-01

    In this article, the influence of the strength mismatch of a narrow gap welded joint of SA508 on the ? factor was evaluated. The ? factor is the principal parameter that determines the plastic portion of the J-integral. The specimens for tensile and hardness tests were collected from piping with narrow gap welding and the stress-strain curve and hardness were obtained from those. From these results, the Ramberg-Osgood (R-O) constant was obtained. Also, the finite element analysis was performed with variations in the strength mismatch and the weld width. The ? factor equation considering the strength mismatch and the weld width of a narrow gap welded joint was suggested.

  4. Effects of stress concentration on the fatigue strength of 7003-T5 aluminum alloy butt joints with weld reinforcement

    NASA Astrophysics Data System (ADS)

    Zhu, Zongtao; Li, Yuanxing; Zhang, Mingyue; Hui, Chen

    2015-03-01

    7003-T5 Aluminum (Al) alloy plates with a thickness of 5 mm are welded by gas metal arc welding (GMAW) method in this work. In order to investigate the influence of stress concentration introduced by weld reinforcement on fatigue strength, the stress concentration factor of the butt joint is calculated. Microscopic and X-ray techniques were utilized to make sure there are no weld defects with large size in butt weld, which can induce extra stress concentration. The cyclic stress - number of cycles to failure (S-N) curves of the joints with and without the welder were obtained by fatigue testing, and the results show that the fatigue strength of 7003-T5 Al alloy butt joints with the weld reinforcement is 50 MPa, which is only 45% of the joints without the weld reinforcement. Fracture surface observation indicated that the fatigue source and propagation are dissimilar for the specimens with and without the welder due to the stress concentration at the weld root. The stress concentration with a factor of 1.7 has great effect on the fatigue strength, but little influence on the tensile strength.

  5. Comparison of Tensile Damage Evolution in Ti6A14V Joints Between Laser Beam Welding and Gas Tungsten Arc Welding

    NASA Astrophysics Data System (ADS)

    Gao, Xiao-Long; Zhang, Lin-Jie; Liu, Jing; Zhang, Jian-Xun

    2014-09-01

    The present paper studied the evolution of tensile damage in joints welded using laser beam welding (LBW) and gas tungsten arc welding (TIG) under a uniaxial tensile load. The damage evolution in the LBW joints and TIG-welded joints was studied by using digital image correlation (DIC) technology and monitoring changes in Young's modulus during tensile testing. To study the mechanism of void nucleation and growth in the LBW joints and TIG-welded joints, test specimens with various amounts of plastic deformation were analyzed using a scanning electron microscope (SEM). Compared with TIG-welded joints, LBW-welded joints have a finer microstructure and higher microhardness in the fusion zone. The SEM analysis and DIC test results indicated that the critical strain of void nucleation was greater in the LBW-welded joints than in the TIG-welded joints, while the growth rate of voids was lower in the LBW-welded joints than in the TIG-welded joints. Thus, the damage ratio in the LBW joints was lower than that in the TIG-welded joints during tensile testing. This can be due to the coarser martensitic ?' and the application of TC-1 welding rods in the TIG-welded joint.

  6. Comparison of Tensile Damage Evolution in Ti6A14V Joints Between Laser Beam Welding and Gas Tungsten Arc Welding

    NASA Astrophysics Data System (ADS)

    Gao, Xiao-Long; Zhang, Lin-Jie; Liu, Jing; Zhang, Jian-Xun

    2014-12-01

    The present paper studied the evolution of tensile damage in joints welded using laser beam welding (LBW) and gas tungsten arc welding (TIG) under a uniaxial tensile load. The damage evolution in the LBW joints and TIG-welded joints was studied by using digital image correlation (DIC) technology and monitoring changes in Young's modulus during tensile testing. To study the mechanism of void nucleation and growth in the LBW joints and TIG-welded joints, test specimens with various amounts of plastic deformation were analyzed using a scanning electron microscope (SEM). Compared with TIG-welded joints, LBW-welded joints have a finer microstructure and higher microhardness in the fusion zone. The SEM analysis and DIC test results indicated that the critical strain of void nucleation was greater in the LBW-welded joints than in the TIG-welded joints, while the growth rate of voids was lower in the LBW-welded joints than in the TIG-welded joints. Thus, the damage ratio in the LBW joints was lower than that in the TIG-welded joints during tensile testing. This can be due to the coarser martensitic ?' and the application of TC-1 welding rods in the TIG-welded joint.

  7. Investigation of the Microstructure of Joints of Aluminum Alloys Produced by Friction Stir Welding

    NASA Astrophysics Data System (ADS)

    Kolubaev, E. A.

    2015-02-01

    Special features of the microstructure of joints of aluminum-magnesium and aluminum-copper alloys produced by friction stir welding are analyzed. It is demonstrated that a layered structure with ultradisperse grains is produced by friction stir welding at the center of the weld joint. An analogy is drawn between the microstructures of joints produced by friction stir welding and surface layer produced by sliding friction.

  8. Significance of weld profile on the fatigue lives of tubular joints

    SciTech Connect

    Maddox, S.J.; Wylde, J.G.; Yamamoto, Noboru

    1995-12-31

    This paper presents the results of a major joint industry project which investigated the influence of weld profile on the fatigue performance of tubular joints. Fatigue tests were performed on steel tubular T-joints under in-plane bending, with the main aim of ``testing`` the value of the weld profile control measures laid down by AWS. The range of welds produced enabled the effects of as-welded surface finish, weld leg length, and hence weld angle, and weld toe grinding to be explored. The results throw serious doubt on the value of the AWS weld profile control measures. However, they do confirm the potential benefit of the increased weld leg length if it moves the weld toe into a lower stressed region. Recommendations are made for changes to current design codes.

  9. Thermal analysis for resistance welding of large-scale thermoplastic composite joints

    NASA Astrophysics Data System (ADS)

    Holmes, Scott T.; Gillespie, John W., Jr.

    1993-06-01

    The need for effective and reliable joining methods continues to grow as the use of thermoplastic composites becomes widespread. It is now possible to join large-scale components with the development of an automated sequential resistance welding process. The thermal history generated by the heating element placed at the interface between adherends determines the quality and performance of the welded joint. This article presents a thermal analysis for the resistance welding of large-scale components that overcomes the limitations of previous models. To simulate welding of the interface, a heat generation term was incorporated that accounts for the Joule heating of graphite fibers in the heating element. A parametric study was conducted to investigate the influence of welding parameters and assess the uniformity of interface temperatures. Components were joined by the resistance welding process to obtain experimental verification. Regions of localized overheating where potential current leakage may occur were identified as a function of process parameters. Insights on promoting more uniform heating for the resistance welding process are discussed.

  10. Nuclear Technology. Course 28: Welding Inspection. Module 28-4, Weld Joint Verification.

    ERIC Educational Resources Information Center

    Espy, John

    This fourth in a series of ten modules for a course titled Welding Inspection discusses the nomenclature, symbols, and the purposes of most common joint designs, preparations, and fit-ups. The module follows a typical format that includes the following sections: (1) introduction, (2) module prerequisites, (3) objectives, (4) notes to…

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  12. Influence of control parameters on the joint tracking performance of a coaxial weld vision system

    NASA Technical Reports Server (NTRS)

    Gangl, K. J.; Weeks, J. L.

    1985-01-01

    The first phase of a series of evaluations of a vision-based welding control sensor for the Space Shuttle Main Engine Robotic Welding System is described. The robotic welding system is presently under development at the Marshall Space Flight Center. This evaluation determines the standard control response parameters necessary for proper trajectory of the welding torch along the joint.

  13. GTAW penetration based on electrode tip location versus weld joint center line

    NASA Astrophysics Data System (ADS)

    Daumeyer, G. J., III

    1992-11-01

    Gas Tungsten Arc Welding (GTAW) is often the chosen process for final enclosure welds of heat sensitive electrical and electronic product. GTAW is used to produce welds that satisfy design requirements (usually a penetration requirement) and not expose the product to such high heat that would cause unwanted damage. An important variable in the GTAW process is the location of the Electrode tip over the weld joint center line. This study shows the tolerance of positional location over a narrow scope. Using coupons which represent the W88 container weld joint geometry, penetration vs. electrode tip positional location (offset) is investigated. Results indicate a positional location tolerance of +/- 0.008 in. is acceptable. Several different major components (MC's) supporting various weapons programs require low heat input GTA welds. The electrode tip positional location tolerance is determined by each MC's weld joint tolerances and heat sensitivity. For this short study, the weld joint geometry of a container weld was used. These coupons were welded with the specified weld schedule and one additional weld schedule in order to show the relationship based on both travel speed and gap. Multiple coupon welds were made to eliminate error in the results. Within the scope of this research, a positional tolerance of +/- 0.008 in. of the electrode center over the weld joint center is required. For other MC's this tolerance may be tighter or more relaxed depending upon the specific considerations.

  14. Residual stress in laser welded dissimilar steel tube-to-tube joints

    SciTech Connect

    Sun, Zheng . Lab. of Production Engineering)

    1993-09-01

    Austenitic-ferritic dissimilar steel joints are widely used in power generation systems. Their utilization has proved to be efficient in terms of satisfactory properties and the economics. These types of joints have usually been produced using conventional welding processes, such as tungsten inert gas (TIG) welding. With the rapid development of high power lasers, laser welding has received considerable attention. Laser welding offers many advantages over conventional welding processes, e.g. low heat input, small heat-affected zone (HAZ), small distortion, and welding in an exact and reproducible manner. Residual stress distribution in laser welds may also differ from those made by conventional welding processes due to its special features. Residual stress, particularly tensile residual stress in the weld, can be very important factor in controlling the quality and service life of the welded structure. The formation of tensile residual stress in the weld may result in the initiation of fatigue cracking, stress corrosion cracking or other types of fractures. It is useful, therefore, to understand the distribution of residual stress in austenitic-ferritic laser welds, and thus evaluate the quality of the joints. Although residual stress distribution in the welded joints has been extensively investigated, little data are available for the residual stress distribution in laser welds. The aim of the work was to examine residual stress distribution along laser welds of dissimilar steel tube-to-tube joints, which were made by both autogeneous welding and welding with filler wire. The results were also compared with the joints made by plasma arc and TIG welding.

  15. Lap and butt joints of dissimilar stainless steels welded by CO2 laser

    NASA Astrophysics Data System (ADS)

    Daurelio, Giuseppe; Dionoro, G.; Memola Capece Minutolo, F.; Panagopoulos, Christos N.

    1993-05-01

    This work concerns the lap welding of dissimilar (AISI 304 - 430, AISI 430 - 304, AISI 316 - 430, and AISI 430 - 316) stainless steels and the butt welding of dissimilar (AISI 304 - 316 and AISI 304 - 430) ones using a fast axial flow 2 kW cw CO2 laser (B.O.C. Laser Ltd.). Two covering gases, He and N2, are used fed coaxially to the laser beam through a 12 mm outlet diameter nozzle at a flow rate varying from 1.67 to 1.87 X 10-3)m3/s. The influence of the process parameters, such as power level, covering gas, and speed on the quality of the welded joints is examined. In the second part of the work laser lap and butt welds of dissimilar stainless steels are characterized by macro and micro graphic investigations to enable structural evaluations. Fillet weld morphology and quality of the same specimens is examined for the two different covering gases, He and N2. Moreover, the different structural aspects of the melted zones obtained with laser welds of the same pair of stainless steels, but with the beam impinging first on the austenitic stainless steel (e.g., AISI 304 - 430) and then the ferritic one (e.g., AISI 430 - 304), or vice versa, are also studied and evaluated.

  16. Tensile Properties of Under-Matched Weld Joints for 950 MPa Steel.

    NASA Astrophysics Data System (ADS)

    Yamamoto, Kouji; Arakawa, Toshiaki; Akazawa, Nobuki; Yamamoto, Kousei; Matsuo, Hiroki; Nakagara, Kiyoyuki; Suita, Yoshikazu

    In welding of 950 MPa-class high tensile strength steel, preheating is crucial in order to avoid cold cracks, which, however, eventually increases welding deformations. One way to decrease welding deformations is lowering preheating temperature by using under-matched weld metal. Toyota and others clarify that although breaking elongation can decrease due to plastic constraint effect under certain conditions, static tensile of under-matched weld joints is comparable to that of base metal. However, there has still been no report about joint static tensile of under-matched weld joints applied to 950 MPa-class high tensile strength steel. In this study, we aim to research tensile strength and fatigue strength of under-matched weld joints applied to 950 MPa-class high tensile steel.

  17. Fabrication of niobium superconducting accelerator cavity by electron beam welded joints

    NASA Astrophysics Data System (ADS)

    Saha, T. K.; Mondal, J.; Mittal, K. C.; Bhushan, K. G.; Bapat, A. V.

    2012-11-01

    Fabrication of superconducting cavities has been taken up as a part of the development of accelerator driven sub critical system (ADSS) by Bhabha Atomic Research Centre. Large grain (RRR>99) pure niobium was chosen as the material for the cavity. Niobium,for its application as superconductor requires extremely high quality joints, feasible only by electron beam welding at high vacuum environment. An indigenously developed 100kV, 4kW high vacuum electron beam welding machine has been utilized to carry out the welding operations. Planning of the weld sequences was chalked out. Holding fixtures for the cavity, consists of seven numbers of joints have been fabricated beforehand. A few coupons were welded for optimization of the weld parameters and for inspection of the weld purity by indigenously developed secondary ion mass spectroscopy. The report describes the welding equipment and the stage wise joining operations of the cavity in details and also discusses the qualification testing of the welded cavity.

  18. Effect of a copper filler metal on the microstructure and mechanical properties of electron beam welded titanium-stainless steel joint

    SciTech Connect

    Wang, Ting; Zhang, Binggang; Feng, Jicai; State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin, 150001 ; Tang, Qi

    2012-11-15

    Cracking in an electron beam weld of titanium to stainless steel occurred during the cooling process because of internal thermal stress. Using a copper filler metal, a crack free joint was obtained, which had a tensile strength of 310 MPa. To determine the reasons for cracking in the Ti/Fe joint and the function of the copper filler metal on the improvement of the cracking resistance of the Ti/Cu/Fe joint, the microstructures of the joints were studied by optical microscopy, scanning electron microscopy and X-ray diffraction. The cracking susceptibilities of the joints were evaluated with microhardness tests on the cross-sections. In addition, microindentation tests were used to compare the brittleness of the intermetallics in the welds. The results showed that the Ti/Fe joint was characterized by continuously distributed brittle intermetallics such as TiFe and TiFe(Cr){sub 2} with high hardness ({approx} 1200 HV). For the Ti/Cu/Fe joint, most of the weld consisted of a soft solid solution of copper with dispersed TiFe intermetallics. The transition region between the weld and the titanium alloy was made up of a relatively soft Ti-Cu intermetallic layer with a lower hardness ({approx} 500 HV). The formation of soft phases reduced the cracking susceptibility of the joint. - Highlights: Black-Right-Pointing-Pointer Electron beam welded Ti/Fe joint cracked for the brittleness and residual stress. Black-Right-Pointing-Pointer Electron beam welded Ti/Cu/Fe joint with tensile strength of 310 MPa was obtained. Black-Right-Pointing-Pointer Cu diluted Ti and Fe contents in weld and separated the TiFe{sub 2} into individual blocks. Black-Right-Pointing-Pointer Interfacial hard Ti-Fe compounds were replaced by soft Ti-Cu compounds in the weld. Black-Right-Pointing-Pointer A large amount of solid solution of copper formed in the weld.

  19. Evaluation of the nugget diameter in spot welded joints between two steel sheets by means of a potential drop technique

    NASA Astrophysics Data System (ADS)

    Tohmyoh, Hironori; Ikarashi, Hidetomo; Matsui, Yoichi; Hasegawa, Yuta; Obara, Satoshi

    2015-08-01

    A potential drop technique which utilizes the electrical circuit used in resistance spot welding is reported. Spot welded samples comprising two steel sheets were inserted between the two Cu electrodes and a constant direct current was supplied between the electrodes. The potential drop between two points, one on each electrode, was determined by analysis for various values of nugget diameter and various values of the contact resistance between the Cu electrodes and the steel sheet sample. The nugget diameter of the spot welded joint could be quantitatively evaluated from the measured potential drop and the equation obtained from the analysis.

  20. Electrochemical impedance spectroscopy study on the corrosion of the weld zone of 3Cr steel welded joints in CO2 environments

    NASA Astrophysics Data System (ADS)

    Xu, Li-ning; Zhu, Jin-yang; Lu, Min-xu; Zhang, Lei; Chang, Wei

    2015-05-01

    The welded joints of 3Cr pipeline steel were fabricated with commercial welding wire using the gas tungsten arc welding (GTAW) technique. Potentiodynamic polarization curves, linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and energy-dispersive spectrometry (EDS) were used to investigate the corrosion resistance and the growth of a corrosion film on the weld zone (WZ). The changes in electrochemical characteristics of the film were obtained through fitting of the EIS data. The results showed that the average corrosion rate of the WZ in CO2 environments first increased, then fluctuated, and finally decreased gradually. The formation of the film on the WZ was divided into three stages: dynamic adsorption, incomplete-coverage layer formation, and integral layer formation.

  1. Joint properties of cast Fe-Pt magnetic alloy laser-welded to Co-Cr alloy.

    PubMed

    Baba, Naoki; Watanabe, Ikuya; Tanaka, Yasuhiro; Hisatsune, Kunihiro; Atsuta, Mitsuru

    2005-12-01

    This study investigated the joint properties of Fe-Pt alloy laser-welded to Co-Cr alloy. Cast plates (0.5 x 3.0 x 10 mm) were prepared with Fe-Pt and Co-Cr alloys. Fe-Pt plates were butted against Co-Cr plates and laser-welded using Nd:YAG laser. Control and homogeneously welded specimens were also prepared. Laser welding was performed with and without argon shielding. Tensile testing was conducted, and both fracture force (Ff: N) and elongation (El: %) were recorded. There were no differences in the Ff value between the specimens with and without argon shielding for the welded Fe-Pt/Co-Cr. Lower Ff value of the welded specimen was obtained in the order of Fe-Pt alloy < Fe-Pt/Co-Cr < Co-Cr alloy. The results indicated that Fe-Pt welded to Co-Cr had Ff values between the values of homogeneously welded Fe-Pt and Co-Cr alloys. Argon shielding, on the other hand, had no effect on the weld strength between Fe-Pt and Co-Cr alloys. PMID:16445017

  2. Structure and properties of joints produced by ultrasound-assisted explosive welding

    NASA Astrophysics Data System (ADS)

    Peev, A. P.; Kuz'min, S. V.; Lysak, V. I.; Kuz'min, E. V.; Dorodnikov, A. N.

    2015-08-01

    This paper presents the results of the effect of ultrasound on explosion welded materials. It has been established that simultaneous treatment with ultrasonic vibrations and explosion welding of the materials to be welded has a significant effect on the structure and properties of the heat-affected zone of formed joints.

  3. Camera Based Closed Loop Control for Partial Penetration Welding of Overlap Joints

    NASA Astrophysics Data System (ADS)

    Abt, F.; Heider, A.; Weber, R.; Graf, T.; Blug, A.; Carl, D.; Höfler, H.; Nicolosi, L.; Tetzlaff, R.

    Welding of overlap joints with partial penetration in automotive applications is a challenging process, since the laser power must be set very precisely to achieve a proper connection between the two joining partners without damaging the backside of the sheet stack. Even minor changes in welding conditions can lead to bad results. To overcome this problem a camera based closed loop control for partial penetration welding of overlap joints was developed. With this closed loop control it is possible to weld such configurations with a stable process result even under changing welding conditions.

  4. 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.

  5. Weld cracking in corner joints by submerged-arc welding with high heat input

    SciTech Connect

    Wada, T.; Satoshi, I.; Terasaki, T.

    1995-12-31

    One-pass submerged arc welding (SAW) with high heat input is widely employed in Japan for the comer seam of box-shaped columns with a plate thickness of up to 70mm. The welding efficiency of one-pass SAW is several times higher than that of multipass welding. However, an internal crack similar to lamellar tearing occasionally occurs in the center-thickness position of the flange plate. ne mechanism of this crack and appropriate countermeasures to cracking were studied. It was found that this cracking was a kind of hydrogen induced cracking(HIC), and that the dominant material factors of this cracking were an elongated manganese sulfide (MnS) in the center segregation band, and martensite-austenite constituents (M-A) around MnS formed by intercritical heat affection of one-pass SAW. Drying of the flux was the most effective countermeasure in the welding conditions. As a groove for the one-pass SAW comer joint, a bevel groove was preferable to a V groove to prevent cracking. These effects were also clarified by the finite differential method(FDM) for the diffusion of hydrogen. As countermeasures in the production of steel plates, addition of Ca, soft reduction in continuous casting, and application of thermo-mechanical-control-process (TMCP) were effective.

  6. Grinding assembly, grinding apparatus, weld joint defect repair system, and methods

    DOEpatents

    Larsen, Eric D.; Watkins, Arthur D.; Bitsoi, Rodney J.; Pace, David P.

    2005-09-27

    A grinding assembly for grinding a weld joint of a workpiece includes a grinder apparatus, a grinder apparatus includes a grinding wheel configured to grind the weld joint, a member configured to receive the grinding wheel, the member being configured to be removably attached to the grinder apparatus, and a sensor assembly configured to detect a contact between the grinding wheel and the workpiece. The grinding assembly also includes a processing circuitry in communication with the grinder apparatus and configured to control operations of the grinder apparatus, the processing circuitry configured to receive weld defect information of the weld joint from an inspection assembly to create a contour grinding profile to grind the weld joint in a predetermined shape based on the received weld defect information, and a manipulator having an end configured to carry the grinder apparatus, the manipulator further configured to operate in multiple dimensions.

  7. X-Ray Structural Study of 09Nn2Si Steel Welded Joints

    NASA Astrophysics Data System (ADS)

    Golikov, N. I.; Platonov, A. A.; Saraev, Y. N.

    2015-09-01

    The article is devoted to handling a vital scientific and technical problem of improving operational reliability and safety of critical constructions, exploited in Siberia and Far North, by developing of new technological approaches to welding. In the article results of X-ray diffraction examinations of 09Mn2Si steel welded joints are given, produced by different welding operations. Resulting from researches, the authors have concluded that pulse-arc welding is the most preferred welding process as compared with direct current welding.

  8. Test device prevents weld joint damage by eliminating axial pin forces on unpotted modules

    NASA Technical Reports Server (NTRS)

    Cree, R. E.

    1967-01-01

    Test device makes electrical connection to pins on unpotted electronic modules without introducing any displacing forces of the pins, thus preventing weld joint damage. The pins are spaced in a potting header, but are free to slide in and out except for restraint from welded wire joints.

  9. Effect of welding on impact toughness of butt-joints in a titanium alloy

    E-print Network

    Zhou, Wei

    Effect of welding on impact toughness of butt-joints in a titanium alloy Wei Zhou a, *, K.G. Chew b-2901, USA b School of Mechanical and Production Engineering, Nanyang Technological University, 50 Nanyang Abstract Impact toughness of a gas tungsten arc welded TiÁ/6AlÁ/4V alloy butt-joint was evaluated at room

  10. Fracture resistance of Nd:YAG laser-welded cast titanium joints with various clinical thicknesses and welding pulse energies.

    PubMed

    Lin, Mau-Chin; Lin, Sheng-Chieh; Wang, Yu-Tsai; Hu, Suh-Woan; Lee, Tzu-Hsin; Chen, Li-Kai; Huang, Her-Hsiung

    2007-05-01

    The purpose of this study was to evaluate the fracture resistance of Nd:YAG laser-welded cast titanium (Ti) joints with various clinical thicknesses and welding pulse energies. A four-point bending test was used to assess the effects of various specimen thicknesses (1-3 mm) and welding pulse energies (11-24 J) on the fracture resistance of Nd:YAG laser-welded Ti dental joints. Fracture resistance was evaluated in terms of the ratio of the number of fractured specimens to the number of tested specimens. As for the fracture frequencies, they were compared using the Cochran-Mantel-Haenszel test. Morphology of the fractured Ti joints was observed using a scanning electron microscope. Results showed that decreasing the specimen thickness and/or increasing the welding pulse energy, i.e., increasing the welded area percentage, resulted in an increase in the fracture resistance of the Ti joint. Where fracture occurred, the fracture site would be at the center of the weld metal. PMID:17694746

  11. 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.

  12. Application of welding simulation to block joints in shipbuilding and assessment of welding-induced residual stresses and distortions

    NASA Astrophysics Data System (ADS)

    Fricke, Wolfgang; Zacke, Sonja

    2014-06-01

    During ship design, welding-induced distortions are roughly estimated as a function of the size of the component as well as the welding process and residual stresses are assumed to be locally in the range of the yield stress. Existing welding simulation methods are very complex and time-consuming and therefore not applicable to large structures like ships. Simplified methods for the estimation of welding effects were and still are subject of several research projects, but mostly concerning smaller structures. The main goal of this paper is the application of a multi-layer welding simulation to the block joint of a ship structure. When welding block joints, high constraints occur due to the ship structure which are assumed to result in accordingly high residual stresses. Constraints measured during construction were realized in a test plant for small-scale welding specimens in order to investigate their and other effects on the residual stresses. Associated welding simulations were successfully performed with fine-mesh finite element models. Further analyses showed that a courser mesh was also able to reproduce the welding-induced reaction forces and hence the residual stresses after some calibration. Based on the coarse modeling it was possible to perform the welding simulation at a block joint in order to investigate the influence of the resulting residual stresses on the behavior of the real structure, showing quite interesting stress distributions. Finally it is discussed whether smaller and idealized models of definite areas of the block joint can be used to achieve the same results offering possibilities to consider residual stresses in the design process.

  13. Microstructure and mechanical properties of high power CO 2 laser welded joint of Mg-Rare earth alloy NZ30K

    NASA Astrophysics Data System (ADS)

    Dai, Jun; Huang, Jian; Li, Zhuguo; Wu, Yixiong

    The weldability of a 9.5 mm thick Mg-Rare earth alloy NZ30K using 15 kW high power CO2 laser was studied. The microstructure and mechanical properties of the typical welded joints had been analyzed and tested. When using the right laser welding parameters, good weld forming can be obtained. The microstructure of the fusion zone is small equiaxed grains. There is no softening zone to be observed according to the micro-hardness distribution across the welded joints. The results show that the thick Mg-Rare earth alloy NZ30K plate can be welded by the high power CO2 laser with good weld quality.

  14. 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)

    ?peko?lu, 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.

  15. Higher-Quality Weld Joints for Tube Sections

    NASA Technical Reports Server (NTRS)

    Olszewski, John T.

    1987-01-01

    Less material in weld inserts results in better fusion. Redesigned insert for joining tubes by welding improves quality of weld. In new insert, leg of T shorter so it does not protrude into tube cavity.

  16. The Diagnostic Method of Inner Parts of Welded Joints at Nuclear Power Plant

    SciTech Connect

    Bednarova, O.; Janovec, J.

    2010-06-22

    There is no possibility to check any inner part at real welded joint at nuclear power station (NPS) during operation because any destructive test cannot be used. In practice there is checked surface of weld. There are used four methodical instructions for the check of real welds: 1. The visual inspection, 2. The measurement of hardness, 3. The chemical composition checking and 4. The microstructure replica analysis. It is necessary to know how these information of weld surface are in accordance with characteristics of inner parts of weld. If there is not any difference between surface weld microstructure and internal weld microstructure of experimental weld it is supposed to that there is not any difference in other measured properties of welds. If is changed structural characteristics of microstructure, it is changed also hardness, chemical analysis etc. It was observed that the microstructure of real welds is almost the same with simulated weld and also the surface microstructure of experimental weld is in accordance with microstructure of inner parts of this weld. It can be supposed extension of lifetime of NPS if there is not any difference between replicas microstructure taken after six year operation of NPS and microstructure of inner parts of simulated weld is almost the same with surface microstructure.

  17. Residual Stress Evaluation of AA2024-T3 Friction Stir Welded Joints

    NASA Astrophysics Data System (ADS)

    Milan, M. T.; Bose Filho, W. W.; Tarpani, J. R.; Malafaia, A. M. S.; Silva, C. P. O.; Pellizer, B. C.; Pereira, L. E.

    2007-02-01

    The main aim of this study was to evaluate the residual stress field in friction stir welded joints of 2024-T3 aluminum alloy plates using the slitting method. This is based on the fact that when a cut, simulating a growing crack, is incrementally introduced into a part, residual stresses are relieved on the slot surfaces created, causing the part to deform. Such deformation can be measured by strain gages attached to specific regions of the part and the residual stress profile that originally existed can be evaluated. Cuts were introduced by wire electro discharge machining (WEDM), in finishing mode, either perpendicularly or longitudinally to the weld nugget, in 3.2 × 60 × 120 mm3 rectangular testpieces. For the longitudinal testpieces, the slot was introduced in two different positions: on the center of the weld nugget and 5 mm distant from the weld center line, in order to sample the thermomechanically/heat affected zone. The residual stress intensity factor, K r, was calculated using a fracture mechanics approach and the inverse weight function method was employed to obtain the initial residual stress profile. Residual stress redistribution profiles ahead of the slot tip could also be derived using the inverse weight function method. However, for cracked components subjected to compressive residual stress fields, when the crack faces are in contact, a non-linear problem arises and the zero displacement condition has to be taken into account in order to provide a more accurate solution of the residual stress field.

  18. Numerical and Experimental Evaluation on the Residual Stresses of Welded Joints

    NASA Astrophysics Data System (ADS)

    Huh, Sun Chul; Park, Wonjo; Yang, Haesug; Jung, Haeyoung; Kim, Chuyoung

    Wings for the defense industry such as fighters, missiles, and rockets should show no deformation or damage on the structure. The structures of existing wings had holes for weight reduction. The plates and frames were fixed with rivets or screws, which limited the weight reduction possible. In this study, an improvement was made in jointing methods through EB welding and laser welding. Welding strength was measured through tension testing. In addition, finite element analysis was performed for the welding process so as to deduce the optimum welding condition.

  19. Effects of Sealing Run Welding with Defocused Laser Beam on the Quality of T-joint Fillet Weld

    NASA Astrophysics Data System (ADS)

    Unt, Anna; Poutiainen, Ilkka; Salminen, Antti

    Fillet weld is the predominant weld type used for connecting different elements e.g. in shipbuilding, offshore and bridge structures. One of prevalent research questions is the structural integrity of the welded joint. Post weld improvement techniques are being actively researched, as high stress areas like an incomplete penetration on the root side or fluctuations in penetration depth cannot be avoided. Development of laser and laser-arc hybrid welding processes have greatly contributed to increase of production capacity and reduction of heat-induced distortions by producing single pass full penetration welds in thin- and medium thickness structural steel parts. Present study addresses the issue of how to improve the quality of the fillet welds by welding the sealing run on the root side with defocused laser beam. Welds having incomplete or excessive penetration were produced with several beam angles and laser beam spot sizes on surface. As a conclusion, significant decrease or even complete elimination of the seam irregularities, which act as the failure starting points during service, is achieved.

  20. Study on microstructure and mechanical properties of 304 stainless steel joints by TIG, laser and laser -TIG hybrid welding

    NASA Astrophysics Data System (ADS)

    Yan, Jun; Gao, Ming; Zeng, Xiaoyan

    2010-04-01

    This paper investigated the microstructure and mechanical properties of 304 stainless steel joints by tungsten inert gas (TIG) welding, laser welding and laser-TIG hybrid welding. The X-ray diffraction was used to analyze the phase composition, while the microscopy was conducted to study the microstructure characters of joints. Finally, tensile tests were performed and the fracture surfaces were analyzed. The results showed that the joint by laser welding had highest tensile strength and smallest dendrite size in all joints, while the joint by TIG welding had lowest tensile strength, biggest dendrite size. Furthermore, transition zone and heat affected zone can be observed in the joint of TIG welding. The fractograph observation showed that the TIG welding joint existed as cup-cone shaped fracture, while the laser welding and hybrid welding joints existed as pure-shear fracture. The laser welding and hybrid welding are suitable for welding 304 stainless steel owing to their high welding speed and excellent mechanical properties.

  1. A Study on the compensation margin on butt welding joint of Large Steel plates during Shipbuilding construction.

    NASA Astrophysics Data System (ADS)

    Kim, J.; Jeong, H.; Ji, M.; Jeong, K.; Yun, C.; Lee, J.; Chung, H.

    2015-09-01

    This paper examines the characteristics of butt welding joint shrinkage for shipbuilding and marine structures main plate. The shrinkage strain of butt welding joint which is caused by the process of heat input and cooling, results in the difference between dimensions of the actual parent metal and the dimensions of design. This, in turn, leads to poor quality in the production of ship blocks and reworking through period of correction brings about impediment on improvement of productivity. Through experiments on butt welding joint's shrinkage strain on large structures main plate, the deformation of welding residual stress in the form of I, Y, V was obtained. In addition, the results of experiments indicate that there is limited range of shrinkage in the range of 1 ? 2 mm in 11t ? 21.5t thickness and the effect of heat transfer of weld appears to be limited within 1000 mm based on one side of seam line so there was limited impact of weight of parent metal on the shrinkage. Finally, it has been learned that Shrinkage margin needs to be applied differently based on groove phenomenon in the design phase in order to minimize shrinkage.

  2. Integrity of Polymethylmethacrylate (PMMA) Chemically Welded Joints Examined

    NASA Technical Reports Server (NTRS)

    Lerch, Bradley A.; Thesken, John C.; Bunnell, Charles T.; Kurta, Carol E.; Sydenstricker, Mike

    2005-01-01

    NASA Glenn Research Center s Capillary Flow Experiments (CFE) program is developing experiment payloads to explore fluid interfaces in microgravity on the International Space Station. The information to be gained from the CFE is relevant to the design of fluid-bearing systems in which capillary forces predominate, for example in the passive positioning of liquids in spacecraft fuel tanks. To achieve the science goals of CFE, Glenn researchers constructed several types of experiment vessels. One type of vessel, known as the interior corner flow (ICF), will be used to determine important transients for low-gravity liquid management in a two-phase system. Each vessel has a cylindrical fluid reservoir connected to each end of the test chamber by internal transport tubes, each with a quarter-turn shutoff valve (see the following photograph). These multipiece vessels are made from polymethylmethacrylate (PMMA) because of its excellent optical properties (i.e., the fluids can be observed easily in the vessel). Because of the complexity of certain vessels, the test chamber had to be manufactured in pieces and welded chemically. Some past experience with adhesive bonded plastic showed that the experiment fluid degraded the adhesive to the point of failure. Therefore, it was necessary to see if the fluid also degraded the chemically welded PMMA joints.

  3. Distortion and residual stresses in laser beam weld shaft-hub joints

    NASA Astrophysics Data System (ADS)

    Buschenhenke, F.; Hofmann, M.; Seefeld, T.; Vollertsen, F.

    In laser beam welding, a serious challenge is to control the distortion during the process. Understanding the whole process chain in view of different distortion potentials applied in each processing step provides the ability to control the distortion of the welded components. Every manufacturing step induces residual stresses in the component which can be released by the heat of the welding process, while further residual stresses are introduced into the welded parts upon cooling. The laser beam sources of the new generation permit a high power welding process and high beam quality at the same time. These laser beams are capable of producing deep and narrow seams. Thus the thermal strains of the joined parts are expected to be minimized. Especially axial welded shaft-hub joints show an irregular distribution of bending deformation, which is caused by the self-influencing welding gap. This work deals with the investigation of different laser beam sources and their effect on the welding distortion in axial welded shafthub joints made of steel (20MnCr5). The aim of the work done was to achieve minimal distortion after the welding process. To characterize the influences on the distortion behaviour of the welded parts, residual stresses have been determined by neutron diffraction.

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

    NASA Astrophysics Data System (ADS)

    Výrostková, Anna; Kepi?, 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.

  5. Nondestructive testing of 2017 aluminum copper alloy diffusion welded joints by an automatic ultrasonic system

    SciTech Connect

    Debbouz, O.; Navai, F.

    1999-12-01

    The quality assurance of diffusion welded joints of 2017 aluminum copper alloys has been performed by ultrasonic nondestructive testing (NDT) at high frequency ranges. An ultrasonic automatic system with a high frequency pulser receiver focused probe (D = 15 MHz) was used to detect and artificial calibrated discontinuity (tungsten wire) with an opening diameter of 25 {micro}m (1 x 10{sup {minus}3} in.), in a scanned area of 0.25 mm{sup 2} (4 x 10{sup 4}in.{sup 2}). By this technique, it was also possible to detect clusters of residual microdiscontinuities and some unwelded zones predicting the state of the welded joints, before their dynamic tensile loading test. The difference between a sound and a rejectable welded joint was made by comparison with an ultrasonic autograph image of a treated sample which was the base material specimen subjected to the same thermal cycle as the welded sample. Furthermore, the reflected echoes of the welded samples, as well as the dynamic stress elongation behavior of loaded samples, were compared to those of a treated base material. The average magnitude of the reflected echoes of the extracted curves, arising from a sound welded joint corresponded to a total average value of 45.6 dB, whereas those of a bad joint were equal to 80.2 dB. Thus, beyond this last value it is concluded that the dynamic mechanical properties of diffusion welded joints become often very weak.

  6. Microstructure of Aluminum/Glass Joint Bonded by Ultrasonic Wire Welding

    NASA Astrophysics Data System (ADS)

    Iwamoto, Chihiro

    2013-11-01

    An Al/glass joint created by using ultrasonic welding was analyzed by means of multiscale observation techniques. A cross-sectional analysis of the microstructure revealed that a directly joined interface without reaction phases formed at the periphery of a round joined region. The size of Al grains markedly decreased after ultrasonic welding and some subgrains were observed along the interface. The finer Al grains observed around the periphery of the joined interface showed active plastic flow that promoted welding.

  7. Effects of activating fluxes on the weld penetration and corrosion resistant property of laser welded joint of ferritic stainless steel

    NASA Astrophysics Data System (ADS)

    Wang, Yonghui; Hu, Shengsun; Shen, Junqi

    2015-10-01

    This study was based on the ferritic stainless steel SUS430. Under the parallel welding conditions, the critical penetration power values (CPPV) of 3mm steel plates with different surface-coating activating fluxes were tested. Results showed that, after coating with activating fluxes, such as ZrO2, CaCO3, CaF2 and CaO, the CPPV could reduce 100~250 W, which indicating the increases of the weld penetrations (WP). Nevertheless, the variation range of WP with or without activating fluxes was less than 16.7%. Compared with single-component ones, a multi-component activating flux composed of 50% ZrO2, 12.09% CaCO3, 10.43% CaO, and 27.49% MgO was testified to be much more efficient, the WP of which was about 2.3-fold of that without any activating fluxes. Furthermore, a FeCl3 spot corrosion experiment was carried out with samples cut from weld zone to test the effects of different activating fluxes on the corrosion resistant (CR) property of the laser welded joints. It was found that all kinds of activating fluxes could improve the CR of the welded joints. And, it was interesting to find that the effect of the mixed activating fluxes was inferior to those single-component ones. Among all the activating fluxes, the single-component of CaCO3 seemed to be the best in resisting corrosion. By means of Energy Dispersive Spectrometer (EDS) testing, it was found that the use of activating fluxes could effectively restrain the loss of Cr element of weld zone in the process of laser welding, thus greatly improving the CR of welded joints.

  8. Electrical resistance determination of actual contact area of cold welded metal joints

    NASA Technical Reports Server (NTRS)

    Hordon, M. J.

    1970-01-01

    Method measures the area of the bonded zone of a compression weld by observing the electrical resistance of the weld zone while the load changes from full compression until the joint ruptures under tension. The ratio of bonding force to maximum tensile load varies considerably.

  9. Experiments and simulation for 6061-T6 aluminum alloy resistance spot welded lap joints

    NASA Astrophysics Data System (ADS)

    Florea, Radu Stefanel

    This comprehensive study is the first to quantify the fatigue performance, failure loads, and microstructure of resistance spot welding (RSW) in 6061-T6 aluminum (Al) alloy according to welding parameters and process sensitivity. The extensive experimental, theoretical and simulated analyses will provide a framework to optimize the welding of lightweight structures for more fuel-efficient automotive and military applications. The research was executed in four primary components. The first section involved using electron back scatter diffraction (EBSD) scanning, tensile testing, laser beam profilometry (LBP) measurements, and optical microscopy(OM) images to experimentally investigate failure loads and deformation of the Al-alloy resistance spot welded joints. Three welding conditions, as well as nugget and microstructure characteristics, were quantified according to predefined process parameters. Quasi-static tensile tests were used to characterize the failure loads in specimens based upon these same process parameters. Profilometer results showed that increasing the applied welding current deepened the weld imprints. The EBSD scans revealed the strong dependency between the grain sizes and orientation function on the process parameters. For the second section, the fatigue behavior of the RSW'ed joints was experimentally investigated. The process optimization included consideration of the forces, currents, and times for both the main weld and post-heating. Load control cyclic tests were conducted on single weld lap-shear joint coupons to characterize the fatigue behavior in spot welded specimens. Results demonstrate that welding parameters do indeed significantly affect the microstructure and fatigue performance for these welds. The third section comprised residual strains of resistance spot welded joints measured in three different directions, denoted as in-plane longitudinal, in-plane transversal, and normal, and captured on the fusion zone, heat affected zone and base metal of the joints. Neutron diffraction results showed residual stresses in the weld are approximately 40% lower than the yield strength of the parent material, with maximum variation occurring in the vertical position of the specimen because of the orientation of electrode clamping forces that produce a non-uniform solidification pattern. In the final section a theoretical continuum modeling framework for 6061-T6 aluminum resistance spot welded joints is presented.

  10. 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.

  11. Numerical simulation of the effect of constraints on welding deformations and residual stresses in a pipe flange joint

    NASA Astrophysics Data System (ADS)

    Abid, Muhammad; Siddique, Muhammad

    2005-09-01

    This paper presents a detailed three-dimensional finite element (FE) study to investigate the effect of mechanical constraints on welding distortions and residual stresses in a pipe-flange joint. The FE model of a pipe-flange joint is subjected to sequentially couple nonlinear transient thermo-mechanical analysis to simulate complex welding phenomena. Single-pass gas metal arc welding for single 'V' butt-weld joint geometry of a 100 mm diameter pipe with compatible weld-neck ANSI flange class #300 of low carbon steel is simulated. Two tack-welds at 90° and 270° from the weld start position are modelled. Four different constraint conditions representing the welding of unassembled joints, welding of assembled joints, welding of assembled joints with reflective symmetry and welding of perfectly constrained joints are analysed. To model the constraints and boundary conditions more realistically contact pairs are used between the matching surfaces of different structural components. Basic FE models are validated with experimental data for temperature distribution and deformations. Predicted welding distortions and residual stresses are compared and discussed in detail. From the results, axial displacement and tilt of the flange face are found to be strongly dependant on the constraint conditions. Minimum axial distortion on the flange face is found for rigidly clamped flanges. However, residual stresses have a weak dependence on the constraints set.

  12. Orbital plasma keyhole welding of 12--13% Cr low carbon martensitic line pipe steels and weld joint corrosion properties

    SciTech Connect

    Hoffmeister, H.; Dietrich, S.; Tystad, M.; Knagenhjelm, H.O.; Andersen, T.R.

    1995-10-01

    Based on requirements for more economical pipe laying procedures in the oil and gas industry, the potential of the orbital plasma keyhole process for welding of 12--13% Cr martensitic low carbon steels together with resulting hardness and corrosion properties is investigated. As a result, downhill orbital welding speeds up to 6--7 mm/s at 6--10 mm wall thickness are achieved. For hardness reduction, local postweld heating of 600--700 C at up to 10 min was required. Pitting corrosion resistance of the weld joints was reduced by welding but could be restored by postweld heating above 750--800 C, which, however, might produce hardness levels not satisfying NACE requirements due to formation of untempered martensite.

  13. The Effect of Weld Profile and Geometries of Butt Weld Joints on Fatigue Life Under Cyclic Tensile Loading

    NASA Astrophysics Data System (ADS)

    Al-Mukhtar, A. M.; Biermann, H.; Hübner, P.; Henkel, S.

    2011-11-01

    The fatigue life of welded joint was calculated based on numerical integration of simple Paris' law and a reliable solution of the stress intensity factor (SIF). The initial crack length ( a i) was assumed to be equal to 0.1 mm in case of weld toe. This length was satisfactory for different butt joints geometries. The comparisons with the available data from standards and literature were demonstrated. It was shown numerically that the machining of weld reinforcements will increase the fatigue life. The increase of plate thickness decreases the fatigue strength (FAT) and the number of cycles to failure when using the proportional scaling of crack length. The validation processes of the current calculations have been shown. Therefore, it can be concluded that it will prevent the unnecessary waste of time consumed to carry out the experiments.

  14. Joint strength in high speed friction stir spot welded DP 980 steel

    SciTech Connect

    Saunders, Nathan; Miles, Michael; Hartman, Trent; Hovanski, Yuri; Hong, Sung Tae; Steel, Russell

    2014-05-01

    High speed friction stir spot welding was applied to 1.2 mm thick DP 980 steel sheets under different welding conditions, using PCBN tools. The range of vertical feed rates used during welding was 2.5 mm – 102 mm per minute, while the range of spindle speeds was 2500 – 6000 rpm. Extended testing was carried out for five different sets of welding conditions, until tool failure. These welding conditions resulted in vertical welding loads of 3.6 – 8.2 kN and lap shear tension failure loads of 8.9 – 11.1 kN. PCBN tools were shown, in the best case, to provide lap shear tension fracture loads at or above 9 kN for 900 spot welds, after which tool failure caused a rapid drop in joint strength. Joint strength was shown to be strongly correlated to bond area, which was measured from weld cross sections. Failure modes of the tested joints were a function of bond area and softening that occurred in the heat-affected zone.

  15. TEM Observation of Martensite Layer at the Weld Interface of an A508III to Inconel 82 Dissimilar Metal Weld Joint

    NASA Astrophysics Data System (ADS)

    Chen, Z. R.; Lu, Y. H.

    2015-12-01

    A lenticular martensite layer at the weld interface in an A508III/Inconel 82 dissimilar metal weld (DMW) joint was studied by TEM. The martensite/weld metal boundary was observed as the fusion boundary. There was a K-S orientation relationship between martensite and weld metal. The formation of the martensite was mainly determined by the distribution of alloy elements. The martensite was responsible for the hardness peak in the DMW.

  16. Microstructure of friction stir welded joints of 2017A aluminium alloy sheets.

    PubMed

    Mroczka, K; Dutkiewicz, J; Pietras, A

    2010-03-01

    The present study examines a friction stir welded 2017A aluminium alloy. Transmission electron microscope investigations of the weld nugget revealed the average grain size of 5 microm, moderate density of dislocations as well as the presence of nanometric precipitates located mostly in grains interiors. Scanning electron microscope observations of fractures showed the presence of ductile fracture in the region of the weld nugget with brittle precipitates in the lower part. The microhardness analysis performed on the cross-section of the joints showed fairly small changes; however, after the artificial ageing process an increase in hardness was observed. The change of the joint hardness subject to the ageing process indicates partial supersaturation in the material during friction stir welding and higher precipitation hardening of the joint. PMID:20500429

  17. 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.

  18. Comparison of the Stress Intensity Factor of Load-Carrying Cruciform Welded Joints with Different Geometries

    NASA Astrophysics Data System (ADS)

    Al-Mukhtar, A.; Biermann, H.; Henkel, S.; Hübner, P.

    2010-08-01

    The investigation of fatigue strength needs an accurate solution and reliable values of the stress intensity factor (SIF). In this study, SIF of load-carrying cruciform welded joints has been evaluated using finite element method (FEM), and compared with the available solutions from literature. Load-carrying cruciform welded joints with isosceles triangles and non-isosceles triangle fillet weld shapes were considered and have been analyzed by the FEM-based simulator FRANC2D program. Moreover, the effects of plate thickness and penetration depth have been considered. The aim of this work was to study the effects of these geometrical variables on fatigue SIF of the load-carrying welded joints with lack of penetration. The ability of FRANC2D to find an appropriate SIF solution is shown and compared with available solutions.

  19. A Study of Microstructure and Mechanical Properties of Grade 91 Steel A-TIG Weld Joint

    NASA Astrophysics Data System (ADS)

    Arivazhagan, B.; Vasudevan, M.

    2013-12-01

    In the present study, A-TIG welding was carried out on grade 91 steel plates of size 220 × 110 × 10 mm using the in-house developed activated flux to produce butt-joints. The room-temperature impact toughness of the A-TIG as-welded joint was low due to the presence of untempered martensite matrix despite the low microinclusion density caused by activated flux and also low ?-ferrite (<0.5 %) content. Toughness after postweld heat treatment (PWHT) at 760 °C-2 h was 20 J as against the required value of 47 J as per the specification EN: 1557:1997. However, there was a significant improvement in impact toughness after PWHT at 760 °C for 3 h. The improvement in toughness was attributed to softening of martensite matrix caused by precipitation of carbides due to tempering reactions. The precipitates are of type M23C6, and they are observed at grain boundary as well as within the grains. The A-TIG-processed grade 91 steel weld joint was found to meet the toughness requirements after PWHT at 760 °C-3 h. Observations of fracture surfaces using SEM revealed that the as-welded joint failed by brittle fracture, whereas post-weld heat-treated weld joints failed by decohesive rupture mode.

  20. Comparison of joint designs for laser welding of cast metal plates and wrought wires.

    PubMed

    Takayama, Yasuko; Nomoto, Rie; Nakajima, Hiroyuki; Ohkubo, Chikahiro

    2013-01-01

    The purpose of the present study was to compare joint designs for the laser welding of cast metal plates and wrought wire, and to evaluate the welded area internally using X-ray micro-focus computerized tomography (micro-CT). Cast metal plates (Ti, Co-Cr) and wrought wires (Ti, Co-Cr) were welded using similar metals. The specimens were welded using four joint designs in which the wrought wires and the parent metals were welded directly (two designs) or the wrought wires were welded to the groove of the parent metal from one or both sides (n = 5). The porosity and gap in the welded area were evaluated by micro-CT, and the maximum tensile load of the welded specimens was measured with a universal testing machine. An element analysis was conducted using an electron probe X-ray microanalyzer. The statistical analysis of the results was performed using Bonferroni's multiple comparisons (? = 0.05). The results included that all the specimens fractured at the wrought wire when subjected to tensile testing, although there were specimens that exhibited gaps due to the joint design. The wrought wires were affected by laser irradiation and observed to melt together and onto the filler metal. Both Mo and Sn elements found in the wrought wire were detected in the filler metal of the Ti specimens, and Ni was detected in the filler metal of the Co-Cr specimens. The four joint designs simulating the designs used clinically were confirmed to have adequate joint strength provided by laser welding. PMID:22080283

  1. 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.

  2. Design of a welded joint for robotic, on-orbit assembly of space trusses

    NASA Technical Reports Server (NTRS)

    Rule, William K.

    1992-01-01

    In the future, some spacecraft will be so large that they must be assembled on-orbit. These spacecraft will be used for such tasks as manned missions to Mars or used as orbiting platforms for monitoring the Earth or observing the universe. Some large spacecraft will probably consist of planar truss structures to which will be attached special purpose, self-contained modules. The modules will most likely be taken to orbit fully outfitted and ready for use in heavy-lift launch vehicles. The truss members will also similarly be taken to orbit, but most unassembled. The truss structures will need to be assembled robotically because of the high costs and risks of extra-vehicular activities. Some missions will involve very large loads. To date, very few structures of any kind have been constructed in space. Two relatively simple trusses were assembled in the Space Shuttle bay in late 1985. Here the development of a design of a welded joint for on-orbit, robotic truss assembly is described. Mechanical joints for this application have been considered previously. Welded joints have the advantage of allowing the truss members to carry fluids for active cooling or other purposes. In addition, welded joints can be made more efficient structurally than mechanical joints. Also, welded joints require little maintenance (will not shake loose), and have no slop which would cause the structure to shudder under load reversal. The disadvantages of welded joints are that a more sophisticated assembly robot is required, weld flaws may be difficult to detect on-orbit, the welding process is hazardous, and welding introduces contamination to the environment. In addition, welded joints provide less structural damping than do mechanical joints. Welding on-orbit was first investigated aboard a Soyuz-6 mission in 1969 and then during a Skylab electron beam welding experiment in 1973. A hand held electron beam welding apparatus is currently being prepared for use on the MIR space station. Presently, Marshall Space Flight Center is evaluating processes appropriate for on-orbit welding. A low gravity environment has been found to have very minor effects on the welding processes appropriate for this application. This is based on tests run on-orbit as well as low gravity environments achieved by flying aircraft in parabolic trajectories. It appears that a modified form of gas tungsten arc welding (GTAW) will be most appropriate for welding together structures on-oribt. The process has been modified to work in a vacuum by providing gas to the arc zone by means of a hollow tungsten electrode with special shielding. A commercial tube welding head has been successfully modified for use on-orbit with a gas leakage rate of approximately 2.5 liters/min. To develop as realistic a joint as possible, a specific truss structure was selected on which to base the design. The structure considered was based on the 120 foot diameter aerobrake tetrahedral truss structure. The truss members were assumed to consist of graphite/epoxy tubes. Also, it was assumed that the nodes were constructed of 2219-T87 aluminum alloy. The magnitude of the member load assumed for design purposes was 100 kips.

  3. Effect of Thermal Cycle on the Formation of Intermetallic Compounds in Laser Welding of Aluminum-Steel Overlap Joints

    NASA Astrophysics Data System (ADS)

    Fan, J.; Thomy, C.; Vollertsen, F.

    The intermetallic compound (IMC) (or intermetallic phase layer) has a significant influence on the mechanical properties ofjoints between dissimilar metals obtained by thermal processes such as laser welding. Its formation is basically affected by thermal cycles in the joining or contact zone, where the IMC is formed. Within this study, the influence of the thermal cycle on the formation of the IMC during laser welding of an aluminum-steel (Al99.5-DC01) overlap joint was investigated. The temperature was measured directly by a thermocouple, and the weld seam was analyzed by scanning electron microscope (SEM). The influence of peak temperature, cooling time and the integral of the thermal cycle on the thickness of the IMC was identified and discussed. It was identified that cooling time has the biggest influence on the thickness of the IMC.

  4. Design of a welded joint for robotic, on-orbit assembly of space trusses

    NASA Technical Reports Server (NTRS)

    Rule, W. K.; Thomas, F. P.

    1992-01-01

    A preliminary design for a weldable truss joint for on-orbit assembly of large space structures is described. The joint was designed for ease of assembly, for structural efficiency, and to allow passage of fluid (for active cooling or other purposes) along the member through the joint. The truss members were assumed to consist of graphite/epoxy tubes to which were bonded 2219-T87 aluminum alloy end fittings for welding on-orbit to truss nodes of the same alloy. A modified form of gas tungsten arc welding was assumed to be the welding process. The joint was designed to withstand the thermal and structural loading associated with a 120-ft diameter tetrahedral truss intended as an aerobrake for a mission to Mars.

  5. Effect of Activated Flux on the Microstructure, Mechanical Properties, and Residual Stresses of Modified 9Cr-1Mo Steel Weld Joints

    NASA Astrophysics Data System (ADS)

    Maduraimuthu, V.; Vasudevan, M.; Muthupandi, V.; Bhaduri, A. K.; Jayakumar, T.

    2012-02-01

    A novel variant of tungsten inert gas (TIG) welding called activated-TIG (A-TIG) welding, which uses a thin layer of activated flux coating applied on the joint area prior to welding, is known to enhance the depth of penetration during autogenous TIG welding and overcomes the limitation associated with TIG welding of modified 9Cr-1Mo steels. Therefore, it is necessary to develop a specific activated flux for enhancing the depth of penetration during autogeneous TIG welding of modified 9Cr-1Mo steel. In the current work, activated flux composition is optimized to achieve 6 mm depth of penetration in single-pass TIG welding at minimum heat input possible. Then square butt weld joints are made for 6-mm-thick and 10-mm-thick plates using the optimized flux. The effect of flux on the microstructure, mechanical properties, and residual stresses of the A-TIG weld joint is studied by comparing it with that of the weld joints made by conventional multipass TIG welding process using matching filler wire. Welded microstructure in the A-TIG weld joint is coarser because of the higher peak temperature in A-TIG welding process compared with that of multipass TIG weld joint made by a conventional TIG welding process. Transverse strength properties of the modified 9Cr-1Mo steel weld produced by A-TIG welding exceeded the minimum specified strength values of the base materials. The average toughness values of A-TIG weld joints are lower compared with that of the base metal and multipass weld joints due to the presence of ?-ferrite and inclusions in the weld metal caused by the flux. Compressive residual stresses are observed in the fusion zone of A-TIG weld joint, whereas tensile residual stresses are observed in the multipass TIG weld joint.

  6. Characterization of Kovar-to-Kovar laser welded joints and its mechanical strength

    NASA Astrophysics Data System (ADS)

    Tan, C. W.; Chan, Y. C.; Leung, Bernard N. W.; Tsun, John; So, Alex C. K.

    2005-02-01

    For the packaging of a pump laser in butterfly package, the most crucial assembly step is the fiber-to-laser diode coupling and attachment. The use of laser welding as the joining method offers several advantages if compared with the adhesive joints: strong joining strength, short process time and less contamination. This paper reports on laser welding process characteristics; weld strength and its fracture mode. The penetration depth and melt area of laser spot welds were found to be complicated functions of laser pulse energy, intensity, and beam diameter. Effects of pulse width, input power and size of the focal spot on the rate of energy input to the workpieces and consequently, the weld strength were reported. The weld strength was found to be dependent on the overlapping area between the two joining materials. Surface roughness, R, has influence on the fraction of energy absorbed, A, and therefore, affecting the penetration depth. Thermal analysis was carried out on the laser-welded joints and its heat-affected zone (HAZ) induced by various power densities was examined. These data are important in order to optimize and utilize the laser welding process as an effective manufacturing tool for fabrication of reliable pump laser.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  8. Microstructural Characterization of Internal Welding Defects and Their Effect on the Tensile Behavior of FSW Joints of AA2198 Al-Cu-Li Alloy

    NASA Astrophysics Data System (ADS)

    Le Jolu, Thomas; Morgeneyer, Thilo F.; Denquin, Anne; Sennour, Mohamed; Laurent, Anne; Besson, Jacques; Gourgues-Lorenzon, Anne-Françoise

    2014-11-01

    Internal features and defects such as joint line remnant, kissing bond, and those induced by an initial gap between the two parent sheets were investigated in AA2198-T851 friction stir welded joints. They were compared with the parent material and to defect-free welds obtained using a seamless sheet. The cross-weld tensile strength was reduced by the defects by less than 6 pct. The fracture elongation was not significantly affected in view of experimental scatter. Fracture location, however, changed from the thermomechanically affected zone (retreating side) to the defect in the weld nugget for the welds bearing a kissing bond and for some of the gap welds. The kissing bond was shown by EBSD to be an intergranular feature; it fractured under a normal engineering stress close to 260 MPa during an in situ SEM tensile test. Synchrotron tomography after interrupted tensile testing confirmed opening of the kissing bond. For an initial gap of 23 pct of the sheet thickness, intergranular fracture of copper-enriched or oxide-bearing grain boundaries close to the nugget root was evidenced. The stress and strain state of cross-weld specimens loaded under uniaxial tension was assessed using a 3D finite element, multi-material model, determined on the basis of experimental data obtained on the same specimens using digital image correlation.

  9. Microstructural Characterization of Internal Welding Defects and Their Effect on the Tensile Behavior of FSW Joints of AA2198 Al-Cu-Li Alloy

    NASA Astrophysics Data System (ADS)

    Le Jolu, Thomas; Morgeneyer, Thilo F.; Denquin, Anne; Sennour, Mohamed; Laurent, Anne; Besson, Jacques; Gourgues-Lorenzon, Anne-Françoise

    2014-09-01

    Internal features and defects such as joint line remnant, kissing bond, and those induced by an initial gap between the two parent sheets were investigated in AA2198-T851 friction stir welded joints. They were compared with the parent material and to defect-free welds obtained using a seamless sheet. The cross-weld tensile strength was reduced by the defects by less than 6 pct. The fracture elongation was not significantly affected in view of experimental scatter. Fracture location, however, changed from the thermomechanically affected zone (retreating side) to the defect in the weld nugget for the welds bearing a kissing bond and for some of the gap welds. The kissing bond was shown by EBSD to be an intergranular feature; it fractured under a normal engineering stress close to 260 MPa during an in situ SEM tensile test. Synchrotron tomography after interrupted tensile testing confirmed opening of the kissing bond. For an initial gap of 23 pct of the sheet thickness, intergranular fracture of copper-enriched or oxide-bearing grain boundaries close to the nugget root was evidenced. The stress and strain state of cross-weld specimens loaded under uniaxial tension was assessed using a 3D finite element, multi-material model, determined on the basis of experimental data obtained on the same specimens using digital image correlation.

  10. Low Gravity Improves Welds

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.; Kaukler, William F.; Plaster, Teresa C.

    1993-01-01

    Hardnesses and tensile strengths greater. Welds made under right conditions in low gravity appear superior to those made under high gravity. Conclusion drawn from results of welding experiments conducted during low- and high-gravity-simulating maneuvers of KC-135 airplane. Results have implications not only for welding in outer space but also for repeated rapid welding on Earth or in airplanes under simulated low gravity to obtain unusually strong joints.

  11. 78 FR 47486 - Joint Failure on Continuous Welded Rail Track

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-05

    ...conditions of actual or potential joint failure for which railroad personnel must inspect, including, at a minimum, (i) loose, bent, or missing joint bolts; (ii) rail end batter or mismatch that contributes to instability of the joint; and (iii)...

  12. Eutectic structures in friction spot welding joint of aluminum alloy to copper

    SciTech Connect

    Shen, Junjun Suhuddin, Uceu F. H.; Cardillo, Maria E. B.; Santos, Jorge F. dos

    2014-05-12

    A dissimilar joint of AA5083 Al alloy and copper was produced by friction spot welding. The Al-MgCuAl{sub 2} eutectic in both coupled and divorced manners were found in the weld. At a relatively high temperature, mass transport of Cu due to plastic deformation, material flow, and atomic diffusion, combined with the alloy system of AA5083 are responsible for the ternary eutectic melting.

  13. Characterization of lap joints laser beam welding of thin AA 2024 sheets with Yb:YAG disk-laser

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

    Lap joints obtained by overlapping two plates are widely diffused in aerospace industry. Nevertheless, because of natural aging, adhesively bonded and riveted aircraft lap joints may be affected by cracks from rivets, voids or corrosion. Friction stir welding has been proposed as a valid alternative, although large heat affected zones are produced both in the top and the bottom plate due to the pin diameter. Interest has therefore been shown in studying laser lap welding as the laser beam has been proved to be competitive since it allows to concentrate the thermal input and increases productivity and quality. Some challenges arise as a consequence of aluminum low absorptance and high thermal conductivity; furthermore, issues are due to metallurgical challenges such as both micro and macro porosity formation and softening in the fused zone. Welding of AA 2024 thin sheets in a lap joint configuration is discussed in this paper: tests are carried out using a recently developed Trumpf TruDisk 2002 Yb:YAG disk-laser with high beam quality which allows to produce beads with low plates distortion and better penetration. The influence of the processing parameters is discussed considering the fused zone extent and the bead shape. The porosity content as well as the morphological features of the beads have been examined.

  14. Effect of Postweld Aging Treatment on Fatigue Behavior of Pulsed Current Welded AA7075 Aluminum Alloy Joints

    NASA Astrophysics Data System (ADS)

    Balasubramanian, V.; Ravisankar, V.; Madhusudhan Reddy, G.

    2008-04-01

    This article reports the effect of postweld aging treatment on fatigue behavior of pulsed current welded AA 7075 aluminum alloy joints. AA7075 aluminum alloy (Al-Zn-Mg-Cu alloy) has gathered wide acceptance in the fabrication of light weight structures requiring high strength-to weight ratio, such as transportable bridge girders, military vehicles, road tankers, and railway transport systems. The preferred welding processes of AA7075 aluminum alloy are frequently gas tungsten arc welding (GTAW) process and gas metal arc welding (GMAW) process due to their comparatively easier applicability and better economy. Weld fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal solidification. This often results inferior weld mechanical properties and poor resistance to hot cracking. In this investigation, an attempt has been made to refine the fusion zone grains by applying pulsed current welding technique. Rolled plates of 10 mm thickness have been used as the base material for preparing multipass welded joints. Single V butt joint configuration has been prepared for joining the plates. The filler metal used for joining the plates is AA 5356 (Al-5Mg (wt.%)) grade aluminum alloy. Four different welding techniques have been used to fabricate the joints and they are: (i) continuous current GTAW (CCGTAW), (ii) pulsed current GTAW (PCGTAW), (iii) continuous current GMAW (CCGMAW), and (iv) pulsed current GMAW (PCGMAW) processes. Argon (99.99% pure) has been used as the shielding gas. Rotary bending fatigue testing machine has been used to evaluate fatigue behavior of the welded joints. Current pulsing leads to relatively finer and more equi-axed grain structure in GTA and GMA welds. Grain refinement is accompanied by an increase in fatigue life and endurance limit. Simple postweld aging treatment applied to the joints is found to be beneficial to enhance the fatigue performance of the welded joints.

  15. Modeling and analysis of novel laser weld joint designs using optical ray tracing.

    SciTech Connect

    Milewski, J. O.

    2002-01-01

    Reflection of laser energy presents challenges in material processing that can lead to process inefficiency or process instability. Understanding the fundamentals of non-imaging optics and the reflective propagation of laser energy can allow process and weld joint designs to take advantage of these reflections to enhance process efficiency or mitigate detrimental effects. Optical ray tracing may be used within a 3D computer model to evaluate novel joint and fixture designs for laser welding that take advantage of the reflective propagation of laser energy. This modeling work extends that of previous studies by the author and provides comparison with experimental studies performed on highly reflective metals. Practical examples are discussed.

  16. Fracture Behaviour of Nickel-Titanium Laser Welded Joints

    NASA Astrophysics Data System (ADS)

    Maletta, C.; Falvo, A.; Furgiuele, F.; Barbieri, G.; Brandizzi, M.

    2009-08-01

    In this study, the effects of Nd:YAG laser welding on the fracture behavior of Ni-rich nickel-titanium sheets are analyzed by experimental investigations. The welding was carried out in open air conditions by using a special shielding/clamping system to avoid the chemical contamination of the molten zone and the formation of hot cracks. Mechanical tests of standard dog bone-shaped and single edge crack specimens were carried out to measure the stress-strain response and the fracture resistance of both the base and the welded materials. Furthermore, scanning electron microscopy observations of the fracture surfaces were carried out in order to better understand the failure mechanisms. Finally, systematic comparative studies between base and laser-welded materials were carried out.

  17. Strength analysis of laser welded lap joint for ultra high strength steel

    NASA Astrophysics Data System (ADS)

    Jeong, Young Cheol; Kim, Cheol Hee; Cho, Young Tae; Jung, Yoon Gyo

    2013-12-01

    Several industries including the automotive industry have recently applied the process of welding high strength steel. High strength steel is steel that is harder than normal high strength steel, making it much stronger and stiffer. HSS can be formed in pieces that can be up to 10 to 15 percent thinner than normal steel without sacrificing strength, which enables weight reduction and improved fuel economy. Furthermore, HSS can be formed into complex shapes that can be welded into structural areas. This study is based on previous experiments and is aimed at establishing the stress distribution for laser welded high strength steel. Research on the stress distribution for laser welded high strength steel is conducted by using Solid Works, a program that analyzes the stress of a virtual model. In conclusion, we found that the stress distribution is changed depending on the shape of welded lap joint. In addition, the Influence of the stress distribution on welded high strength steel can be used to standard for high energy welding of high strength steel, and we can also predict the region in welded high strength steel that may cracked.

  18. 46 CFR 56.30-5 - Welded joints.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) Each socket weld must conform to ASME B16.11 (incorporated by reference; see 46 CFR 56.01-2), to applicable standards listed in 46 CFR 56.60-1, Table 56.60-1(b), and to Figure 127.4.4C in ASME B31.1... types of butt welding end preparations are shown in ASME B16.25 (incorporated by reference; see 46...

  19. 46 CFR 56.30-5 - Welded joints.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... types of butt welding end preparations are shown in ASME B16.25 (incorporated by reference; see 46 CFR...) Each socket weld must conform to ASME B16.11 (incorporated by reference; see 46 CFR 56.01-2), to applicable standards listed in 46 CFR 56.60-1, Table 56.60-1(b), and to Figure 127.4.4C in ASME...

  20. 46 CFR 56.30-5 - Welded joints.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... types of butt welding end preparations are shown in ASME B16.25 (incorporated by reference; see 46 CFR...) Each socket weld must conform to ASME B16.11 (incorporated by reference; see 46 CFR 56.01-2), to applicable standards listed in 46 CFR 56.60-1, table 56.60-1(b), and to Figure 127.4.4C in ASME...

  1. 46 CFR 56.30-5 - Welded joints.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... types of butt welding end preparations are shown in ASME B16.25 (incorporated by reference; see 46 CFR...) Each socket weld must conform to ASME B16.11 (incorporated by reference; see 46 CFR 56.01-2), to applicable standards listed in 46 CFR 56.60-1, table 56.60-1(b), and to Figure 127.4.4C in ASME...

  2. 46 CFR 56.30-5 - Welded joints.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... types of butt welding end preparations are shown in ASME B16.25 (incorporated by reference; see 46 CFR...) Each socket weld must conform to ASME B16.11 (incorporated by reference; see 46 CFR 56.01-2), to applicable standards listed in 46 CFR 56.60-1, Table 56.60-1(b), and to Figure 127.4.4C in ASME...

  3. Columnar jointing in vapor-phase-altered, non-welded Cerro Galán Ignimbrite, Paycuqui, Argentina

    USGS Publications Warehouse

    Wright, Heather M.; Lesti, Chiara; Cas, Ray A.F.; Porreca, Massimiliano; Viramonte, Jose G.; Folkes, Christopher B.; Giordano, Guido

    2011-01-01

    Columnar jointing is thought to occur primarily in lavas and welded pyroclastic flow deposits. However, the non-welded Cerro Galán Ignimbrite at Paycuqui, Argentina, contains well-developed columnar joints that are instead due to high-temperature vapor-phase alteration of the deposit, where devitrification and vapor-phase crystallization have increased the density and cohesion of the upper half of the section. Thermal remanent magnetization analyses of entrained lithic clasts indicate high emplacement temperatures, above 630°C, but the lack of welding textures indicates temperatures below the glass transition temperature. In order to remain below the glass transition at 630°C, the minimum cooling rate prior to deposition was 3.0?×?10?3–8.5?×?10?2°C/min (depending on the experimental data used for comparison). Alternatively, if the deposit was emplaced above the glass transition temperature, conductive cooling alone was insufficient to prevent welding. Crack patterns (average, 4.5 sides to each polygon) and column diameters (average, 75 cm) are consistent with relatively rapid cooling, where advective heat loss due to vapor fluxing increases cooling over simple conductive heat transfer. The presence of regularly spaced, complex radiating joint patterns is consistent with fumarolic gas rise, where volatiles originated in the valley-confined drainage system below. Joint spacing is a proxy for cooling rates and is controlled by depositional thickness/valley width. We suggest that the formation of joints in high-temperature, non-welded deposits is aided by the presence of underlying external water, where vapor transfer causes crystallization in pore spaces, densifies the deposit, and helps prevent welding.

  4. Development of Laser Welding of Ni based Superalloys for Aeronautic Engine Applications (Experimental Process and Obtained Properties).

    NASA Astrophysics Data System (ADS)

    Zapirain, Fidel; Zubiri, Fidel; Garciandía, Fermín; Tolosa, Itziar; Chueca, Samuel; Goiria, Aimar

    Superalloys are designed for service at temperatures above 540 °C. Due to their properties at high temperatures, this family of materials is used in different aircraft engine components. Aeronautic components demand reliable joining technologies. The laser welding of three different superalloys have been performed and analysed. Due to reduced extension of the heat affected zone (HAZ), and high quality and ratio "depth/width" of welded seams, laser welding has been a first joining technology candidate to new designs of components for new engines. The laser welding trials results, properties obtained, and development of the homologation of laser welding process are described.

  5. Effects of welding pulse energy and fluoride ion on the cracking susceptibility and fatigue behavior of Nd:YAG laser-welded cast titanium joints.

    PubMed

    Huang, Her-Hsiung; Lin, Mau-Chin; Lin, Chien-Chan; Lin, Sheng-Chieh; Hsu, Chii-Chih; Chen, Fang-Lung; Lee, Shyh-Yuan; Hung, Chun-Cheng

    2006-09-01

    In this study, the cracking susceptibility and fatigue behavior of Nd:YAG laser-welded cast Ti joints (welding pulse energy: 11, 15, and 18 J) in fluoride-containing (0 and 0.5% NaF) artificial saliva were evaluated using constant elongation rate test (CERT) and fatigue test (FT), respectively. Both CERT and FT were also carried out in open air as controls. Results showed that increasing the welding energy increased the elongation and fatigue life, but decreased the tensile strength, of cast Ti joints in open-air environment. With a welding energy of 11 J, the fluoride ions in the artificial saliva increased the cracking susceptibility and decreased the fatigue life of Ti joints. When the welding energy exceeded 15 J, the presence of fluoride ions still increased the cracking susceptibility, but did not reduce the fatigue life of Ti joints. Rupture of Ti joints--if it occurred--occurred only at the welded metal (versus the non-welded part). PMID:17076339

  6. Structure and microhardness of cu-ta joints produced by explosive welding.

    PubMed

    Maliutina, Iu N; Mali, V I; Bataev, I A; Bataev, A A; Esikov, M A; Smirnov, A I; Skorokhod, K A

    2013-01-01

    The structure and microhardness of Cu-Ta joints produced by explosive welding were studied. It was found that, during explosive welding, an intermediate layer 20?40? ? m thick with a finely dispersed heterophase structure, formed between the welded copper and tantalum plates. The structure of the layer was studied by scanning and transmission electron microscopy. Microvolumes with tantalum particles distributed in a copper matrix and microvolumes of copper particles in a tantalum matrix were detected. The tantalum particles in copper have a size of 5?500 nm, with a predominance of 5?50 nm particles. A mechanism for the formation of the finely dispersed heterophase structure in explosive welding is proposed. The microhardness of interlayers with the heterophase structure reaches 280 HV, which far exceeds the microhardness of copper (~130 HV) and tantalum (~160 HV). Many twins of deformation origin were found in the structure of the copper plate. The effect of heating temperature in the range from 100 to 900°C on the microhardness of copper, tantalum, and the Cu-Ta welded joint was studied. Upon heating to 900°C, the microhardness of the intermediate layer decreases from 280 to 150 HV. The reduction in the strength properties of the weld material is mainly due to structural transformations in copper. PMID:24453818

  7. The microstructure of aluminum A5083 butt joint by friction stir welding

    NASA Astrophysics Data System (ADS)

    Jasri, M. A. H. M.; Afendi, M.; Ismail, A.; Ishak, M.

    2015-05-01

    This study presents the microstructure of the aluminum A5083 butt joint surface after it has been joined by friction stir welding (FSW) process. The FSW process is a unique welding method because it will not change the chemical properties of the welded metals. In this study, MILKO 37 milling machine was modified to run FSW process on 4 mm plate of aluminum A5083 butt joint. For the experiment, variables of travel speed and tool rotational speed based on capability of machine were used to run FSW process. The concentrated heat from the tool to the aluminum plate changes the plate form from solid to plastic state. Two aluminum plates is merged to become one plate during plastic state and return to solid when concentrated heat is gradually further away. After that, the surface and cross section of the welded aluminum were investigated with a microscope by 400 x multiplication zoom. The welding defect in the FSW aluminum was identified. Then, the result was compared to the American Welding Society (AWS) FSW standard to decide whether the plate can be accepted or rejected.

  8. The microstructure of aluminum A5083 butt joint by friction stir welding

    SciTech Connect

    Jasri, M. A. H. M.; Afendi, M.; Ismail, A.; Ishak, M.

    2015-05-15

    This study presents the microstructure of the aluminum A5083 butt joint surface after it has been joined by friction stir welding (FSW) process. The FSW process is a unique welding method because it will not change the chemical properties of the welded metals. In this study, MILKO 37 milling machine was modified to run FSW process on 4 mm plate of aluminum A5083 butt joint. For the experiment, variables of travel speed and tool rotational speed based on capability of machine were used to run FSW process. The concentrated heat from the tool to the aluminum plate changes the plate form from solid to plastic state. Two aluminum plates is merged to become one plate during plastic state and return to solid when concentrated heat is gradually further away. After that, the surface and cross section of the welded aluminum were investigated with a microscope by 400 x multiplication zoom. The welding defect in the FSW aluminum was identified. Then, the result was compared to the American Welding Society (AWS) FSW standard to decide whether the plate can be accepted or rejected.

  9. Structure and Microhardness of Cu-Ta Joints Produced by Explosive Welding

    PubMed Central

    Maliutina, Iu. N.; Mali, V. I.; Bataev, I. A.; Bataev, A. A.; Esikov, M. A.; Smirnov, A. I.; Skorokhod, K. A.

    2013-01-01

    The structure and microhardness of Cu-Ta joints produced by explosive welding were studied. It was found that, during explosive welding, an intermediate layer 20?40??m thick with a finely dispersed heterophase structure, formed between the welded copper and tantalum plates. The structure of the layer was studied by scanning and transmission electron microscopy. Microvolumes with tantalum particles distributed in a copper matrix and microvolumes of copper particles in a tantalum matrix were detected. The tantalum particles in copper have a size of 5?500?nm, with a predominance of 5?50?nm particles. A mechanism for the formation of the finely dispersed heterophase structure in explosive welding is proposed. The microhardness of interlayers with the heterophase structure reaches 280?HV, which far exceeds the microhardness of copper (~130?HV) and tantalum (~160?HV). Many twins of deformation origin were found in the structure of the copper plate. The effect of heating temperature in the range from 100 to 900°C on the microhardness of copper, tantalum, and the Cu-Ta welded joint was studied. Upon heating to 900°C, the microhardness of the intermediate layer decreases from 280 to 150?HV. The reduction in the strength properties of the weld material is mainly due to structural transformations in copper. PMID:24453818

  10. Structure and ductility of the heat-affected zone of welded joints of a high-strength steel

    NASA Astrophysics Data System (ADS)

    Tabatchikova, T. I.; Nosov, A. D.; Goncharov, S. N.; Gudnev, N. Z.; Delgado Reina, S. Yu.; Yakovleva, I. L.

    2014-12-01

    Methods of optical microscopy and scanning and transmission electron microscopy have been used to study the structure of welded joints of a high-strength structural steel with different types of the weld metal. The impact toughness of the heat-affected zone (HAZ) has been determined at temperatures of +20 and -40°C. Based on the fractograph investigations of the character of the fracture of the welded joints after tests for impact bending, the regions that are the most dangerous for crack initiation have been determined. Structural factors that affect the brittleness of the near-weld zone of welded joints with the austenite metal of the weld are indicated, including the existence of an austenite-bainite structure and coarse carbides, as well as the specific distribution of hydrogen.

  11. Joints, fissures, and voids in rhyolite welded ash-flow tuff at Teton damsite, Idaho

    USGS Publications Warehouse

    Prostka, Harold J.

    1977-01-01

    Several kinds of joints, fissures, and voids are present in densely welded rhyolite ash-flow tuff at Teton damsite. Older fissures and voids probably were formed in the ash-flow sheet during secondary flowage, which probably was caused by differential compaction or settling over irregular topography. The younger, more abundant fissures are mostly steep cooling joints that probably have been opened farther by horizontal tectonic extension and gravitational creep, perhaps aided by lateral stress relief.

  12. Structural Performance Evaluation of Composite-To-Steel Weld Bonded Joint

    SciTech Connect

    Shah, Bhavesh; Frame, Barbara J; Dove, Caroline; Fuchs, Hannes

    2010-01-01

    The Automotive Composites Consortium (ACC), a collaboration of Chrysler, Ford, General Motors, and the US Department of Energy is conducting a focal project to demonstrate the use of composite materials in high volume structural applications such as an underbody capable of carrying crash loads. One of the critical challenges is to attach the composite part to the steel structure in a high-volume automotive manufacturing environment and meet the complex requirements for crash. Weld-bonding, a combination of adhesive bonding and spot welding, was selected as the primary joining method. A novel concept of bonding doubler steel strips to composite enabled the spot welding to the steel structure, ensuring the compability with the OEM assembly processes. The structural performance of the joint, including durability, was assessed via analytical and physical testing under quasi-static loading at various temperatures. This paper discusses the results of the experiments designed to generate key modeling parameters for Finite Element Analysis of the joint.

  13. Effect of friction stir welding parameters on defect formation

    NASA Astrophysics Data System (ADS)

    Tarasov, S. Yu.; Rubtsov, V. E.; Eliseev, A. A.; Kolubaev, E. A.; Filippov, A. V.; Ivanov, A. N.

    2015-10-01

    Friction stir welding is a perspective method for manufacturing automotive parts, aviation and space technology. One of the major problems is the formation of welding defects and weld around the welding zone. The formation of defect is the main reason failure of the joint. A possible way to obtain defect-free welded joints is the selection of the correct welding parameters. Experimental results describing the effect of friction stir welding process parameters on the defects of welded joints on aluminum alloy AMg5M have been shown. The weld joint defects have been characterized using the non-destructive radioscopic and ultrasound phase array methods. It was shown how the type and size of defects determine the welded joint strength.

  14. Microstructure and Properties of TIG/FSW Welded Joints of a New Al-Zn-Mg-Sc-Zr Alloy

    NASA Astrophysics Data System (ADS)

    Lei, Xuefeng; Deng, Ying; Peng, Yongyi; Yin, Zhimin; Xu, Guofu

    2013-09-01

    A new Al-Zn-Mg-Sc-Zr alloy with low Sc content was welded by tungsten inert gas (TIG) and friction stir welding (FSW) techniques. The microstructure and properties of those two welded joints were investigated by property tests and microstructural observations. The results show that the new Al-Zn-Mg-Sc-Zr alloy has desirable welding property. The ultimate tensile strength and welding coefficient of the TIG joint reach 405 MPa and 76.7%, respectively, and in FSW joint those property values reach 490 MPa and 92.6%, respectively. The studied base metal has a deformed fibrous subgrains structure, many nano-scaled Al3(Sc,Zr) particles, and very fine aging precipitates. In the TIG joint, the fusion zone consists of coarsened dendritic grains and the heat-affected zone (HAZ) has fibrous micro-scaled subgrains. The FSW welded joint is characterized by a weld nugget zone, thermo-mechanically affected zone (TMAZ), and HAZ. Due to plastic deformation around the rotating pin and anti-recrystallized effectiveness of Al3(Sc,Zr) particles, the weld nugget zone has a very fine subgrain structure. The TMAZ experiences some dissolution of aging precipitates. Coarsening of aging precipitates was observed in the HAZ. The better mechanical properties of the FSW joint are derived from a fine subgrain structure and homogeneous chemical compositions.

  15. Ultrasonic examination of welded joints of great thickness in mechanical equipment under pressure

    NASA Technical Reports Server (NTRS)

    Emil, N.

    1974-01-01

    The requirements involved in choosing ultrasonic devices, the factors that affect testing, and recommended calibration methods are discussed. The ultrasonic testing method is the only method that up to now permits detection of defects in welded joints of great thickness. The results are conditioned by the performances of the devices employed as well as by the degree of instruction of the personnel.

  16. Local corrosion behaviour of hybrid laser-MIG welded AlZnMg alloy joints

    E-print Network

    Qin, Qinghua

    of Engineering, Australia National University, Acton, ACT 2601, Australia b School of Materials Science and Lashermes [10] conducted the study of influence of filler materials and PWHT on the corrosion behaviourLocal corrosion behaviour of hybrid laser-MIG welded Al­Zn­Mg alloy joints Shaohua Yan a,1 , Hui

  17. Parallel-gap welding for joints between copper conductors and Kovar

    NASA Technical Reports Server (NTRS)

    Mc Daniel, G. E.

    1971-01-01

    Welding technique produces more reliable joints than soldering. Investigation used different sizes of copper conductors and component lead ribbons, corrosion protection platings, and melting points of metals being joined. Optimum combination is gold-plated component lead ribbons and solder-plated copper conductors.

  18. New Equipment for Testing the Fatigue Strength of Riveted and Welded Joints

    NASA Technical Reports Server (NTRS)

    Muller, W

    1940-01-01

    The mechanical and electrical construction of a new experimental instrument for fatigue testing riveted and welded joints is described. This experimental device has the advantage of being able to stress, even with comparatively low magnetic exciter force, structural components in alternate bending by resonance vibrations up to incipient fatigue failure.

  19. T-joints of Ti alloys with hybrid laser-MIG welding: macro-graphic and micro-hardness analyses

    NASA Astrophysics Data System (ADS)

    Spina, R.; Sorgente, D.; Palumbo, G.; Scintilla, L. D.; Brandizzi, M.; Satriano, A. A.; Tricarico, L.

    2012-03-01

    Titanium alloys are characterized by high mechanical properties and elevated corrosion resistance. The combination of laser welding with MIG/GMAW has proven to improve beneficial effects of both processes (keyhole, gap-bridging ability) while limiting their drawbacks (high thermal gradient, low mechanical resistance) In this paper, the hybrid Laser-GMAW welding of Ti-6Al-4V 3-mm thick sheets is investigated using a specific designed trailing shield. The joint geometry was the double fillet welded T-joint. Bead morphologies, microstructures and mechanical properties (micro-hardness) of welds were evaluated and compared to those achieved for the base metals.

  20. Radiographic inspection of porosity in Ti-6Al-4V laser-welded joints.

    PubMed

    Nuñez-Pantoja, Juliana Maria Costa; Takahashi, Jessica Mie Ferreira Koyama; Nóbilo, Mauro Antônio de Arruda; Consani, Rafael Leonardo Xediek; Mesquita, Marcelo Ferraz

    2011-01-01

    Widely used in dentistry, Ti-6Al-4V alloy is difficult to cast and solder, as it frequently exhibits pores inside the structure. This study was conducted to evaluate the effect of joint openings and diameters of laser-welded joints executed in Ti-6Al-4V structures on the presence of pores as checked by radiographic procedures. Sixty dumbbell rods with central diameters of 1.5, 2.0 and 3.5 mm were created from Ti-6Al-4V-wrought bars. Specimens were sectioned and welded using two joint openings (0.0 and 0.6 mm). The combination of variables created six groups (n = 10). Laser welding was executed using 360V/8ms (1.5 and 2.0 mm) and 380V/9ms (3.5 mm), with the focus and frequency set to zero. The joints were finished, polished and submitted to radiographic examination. The radiographs were visually examined for the presence of pores in the joints, qualitatively. The percentage of radiographic presence of pores was calculated without counting pores per joint. Data were analyzed using a chi-square test (? = 0.05). For the 1.5-mm specimens, the incidence of pore presence was significantly higher (p = 0.0001) when using 0.6-mm joint openings (40%) compared to 0.0-mm openings (0%). For the 2.0-mm specimens, there was no significant difference between groups (p = 0.2008). However, for the 3.5-mm specimens, the incidence of pore presence was lower (p = 0.0061) for 0.6-mm openings (50%) compared to 0.0-mm openings (70%). Therefore, laser welding of Ti-6Al-4V structures with thin diameters provides the best condition for the juxtaposition of the parts. PMID:21359490

  1. X-ray opaque additive for inspection of weld joints

    NASA Technical Reports Server (NTRS)

    Brown, R. L.; Cook, J. L.

    1974-01-01

    Thin coating of copper applied to each faying surface of aluminum-alloy improve X ray detection of welding defects. Copper may be applied by spraying, coating, or deposition. Its thickness of faying surfaces must be uniform in range. Coating must be free from spalling and blistering and must contain no porosity.

  2. Upsetting Butt Edge Increases Weld-Joint Strength

    NASA Technical Reports Server (NTRS)

    Vesco, D.

    1964-01-01

    Mechanical upsetting /a mode of cold forging/ of butt edges to be welded is accomplished by the use of hydraulic rams and pressure rollers. The mechanical upsetting increases the thickness of the material in the heat-affected zone and compensates for the lower specific strength per unit thickness common to this area.

  3. A study on an efficient prediction of welding deformation for T-joint laser welding of sandwich panel PART I : Proposal of a heat source model

    NASA Astrophysics Data System (ADS)

    Kim, Jae Woong; Jang, Beom Seon; Kim, Yong Tai; Chun, Kwang San

    2013-09-01

    The use of I-Core sandwich panel has increased in cruise ship deck structure since it can provide similar bending strength with conventional stiffened plate while keeping lighter weight and lower web height. However, due to its thin plate thickness, i.e. about 4~6 mm at most, it is assembled by high power CO2 laser welding to minimize the welding deformation. This research proposes a volumetric heat source model for T-joint of the I-Core sandwich panel and a method to use shell element model for a thermal elasto-plastic analysis to predict welding deformation. This paper, Part I, focuses on the heat source model. A circular cone type heat source model is newly suggested in heat transfer analysis to realize similar melting zone with that observed in experiment. An additional suggestion is made to consider negative defocus, which is commonly applied in T-joint laser welding since it can provide deeper penetration than zero defocus. The proposed heat source is also verified through 3D thermal elasto-plastic analysis to compare welding deformation with experimental results. A parametric study for different welding speeds, defocus values, and welding powers is performed to investigate the effect on the melting zone and welding deformation. In Part II, focuses on the proposed method to employ shell element model to predict welding deformation in thermal elasto-plastic analysis instead of solid element model.

  4. 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…

  5. 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.

  6. Experimental and numerical evaluation of the fatigue behaviour in a welded joint

    NASA Astrophysics Data System (ADS)

    Almaguer, P.; Estrada, R.

    2014-07-01

    Welded joints are an important part in structures. For this reason, it is always necessary to know the behaviour of them under cyclic loads. In this paper a S - N curve of a butt welded joint of the AISI 1015 steel and Cuban manufacturing E6013 electrode is showed. Fatigue tests were made in an universal testing machine MTS810. The stress ratio used in the test was 0,1. Flaws in the fatigue specimens were characterized by means of optical and scanning electron microscopy. SolidWorks 2013 software was used to modeling the specimens geometry, while to simulate the fatigue behaviour Simulation was used. The joint fatigue limit is 178 MPa, and a cut point at 2 039 093 cycles. Some points of the simulations are inside of the 95% confidence band.

  7. Estimate of the allowable dimensions of diagnosed defects in category III and IV welded pipeline joints{sup 1}

    SciTech Connect

    Grin', E. A.; Bochkarev, V. I.

    2013-01-15

    An approach for estimating the permissible dimensions of technological defects in butt welded joints in category III and IV pipelines is described. The allowable size of a welding defect is determined from the condition of compliance with the specifications on strength for a reference cross section (damaged joint) of the pipeline taking into account its weakening by a given defect.With regard to the fairly widespread discovery of technological defects in butt welded joints during diagnostics of auxiliary pipelines for thermal electric power plants, the proposed approach can be used in practice by repair and consulting organizations.

  8. 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)

  9. Synchrotron X-ray CT characterization of friction-welded joints in tial turbocharger components

    NASA Astrophysics Data System (ADS)

    Sun, J. G.; Kropf, A. J.; Vissers, D. R.; Sun, W. M.; Katsoudas, J.; Yang, N.; Fei, D.

    2012-05-01

    Titanium aluminide (TiAl) is an advanced intermetallic material and is being investigated for application in turbocharger components for diesel engines. A TiAl turbocharger rotor consists of a cast TiAl turbine wheel and a Ti-alloy shaft that are joined by friction welding. Although friction welding is an established industrial process, it is still challenging to join dissimilar materials especially for brittle intermetallics. These joints are therefore required to be inspected using a nondestructive evaluation (NDE) method. In this study, synchrotron X-ray computed tomography (CT) developed at the Advanced Photon Source at Argonne National Laboratory was used for NDE characterization of friction-welded joint in three TiAl turbocharger rotors. The filtered synchrotron X-ray source has high peak energies to penetrate thick metallic materials, and the detector (imager) has high spatial resolutions to resolve small flaws. The CT inspections revealed detailed 3D crack distributions within poorly welded joints. The crack detection sensitivity and resolution was calibrated and found to be correlated well with destructive examination.

  10. Effect of Vibrations with Different Frequencies on Reduction of Residual Stress of Welded Joint

    NASA Astrophysics Data System (ADS)

    Aoki, Shugeru; Nishimura, Tadashi; Hiroi, Tetsumaro; Hirai, Seiji

    Welding is widely used for construction of many structures. It is well known that residual stress is generated near the bead because base metal is heated near the bead. Tensile residual stress on the surface degrades fatigue strength. Some reduction methods of residual stress are practically used, for example, heat treatment and shot peening. The authors developed a new method for reduction of residual stress using vibration during welding. In this method, single vibration was used. The effectiveness of the method was demonstrated. In this paper, the effect of vibrations with different frequencies on reduction of residual stress is examined. The effect is examined experimentally by butt-welding of thin plates. First, two thin plates are butt-welded using ultrasonic vibrations with different frequencies on each plate. Some plates are welded using single ultrasonic vibration and without ultrasonic vibration for comparison. When thin plates are welded using vibrations with different frequencies, tensile residual stresses are reduced and reduction rate is largest compared with other conditions. Second, two thin plates are butt-welded using ultrasonic vibration and vibration with low frequency. Some plates are welded using single vibration and without vibration for comparison. In this case, tensile residual stresses are reduced and reduction rate is largest compared with other conditions. Obtained results are examined by analytical method.

  11. Laser-assisted friction stir welding of aluminum alloy lap joints: microstructural and microhardness characterizations

    NASA Astrophysics Data System (ADS)

    Casalino, Giuseppe; Campanelli, Sabina L.; Contuzzi, Nicola; Angelastro, Andrea; Ludovico, Antonio D.

    2014-02-01

    Friction Stir Welding (FSW) is a solid-state joining process; i.e., no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. The laser Assisted Friction Stir Welding (LAFSW) combines a Friction Stir Welding machine and a laser system. Laser power is used to preheat and to plasticize the volume of the workpiece ahead of the rotating tool; the workpiece is then joined in the same way as in the conventional FSW process. In this work an Ytterbium fiber laser with maximum power of 4 kW and a commercial FSW machine were coupled. Both FSW and LAFSW tests were conducted on 3 mm thick 5754H111 aluminum alloy plates in lap joint configuration with a constant tool rotation rate and with different feed rates. The two processes were compared and evaluated in terms of differences in the microstructure and in the micro-hardness profile.

  12. Numerical and experimental study of the weld joints formation in welding foam materials

    SciTech Connect

    Bezginov, Roman O. E-mail: rakrekt@mail.ru; Krektuleva, Raisa A. E-mail: rakrekt@mail.ru; Mishin, Mikhail A. E-mail: rakrekt@mail.ru; Cherepanov, Oleg I. Cherepanov, Roman O.

    2014-11-14

    A numerical analysis of fusion welding of steel- and aluminum-based foam materials is carried out. The schemes of the structured and stochastic pore distribution are considered. The research results were used to conduct the experiments which confirmed the reliability of the numerical calculations.

  13. Combination Effects of Nocolok Flux with Ni Powder on Properties and Microstructures of Aluminum-Stainless Steel TIG Welding-Brazing Joint

    NASA Astrophysics Data System (ADS)

    He, Huan; Lin, Sanbao; Yang, Chunli; Fan, Chenglei; Chen, Zhe

    2013-11-01

    A flux consisting of Nocolok and nickel powder was first applied for TIG welding-brazing of aluminum-stainless steel. Results of tensile and impact tests illustrated that a significant improvement in mechanical properties of the butt joint was obtained with the flux, tensile strength increased from 116 to 158 MPa, and impact energy increased from 3.2 to 6.7 J. Investigation results on microstructures of interfaces and seams suggested that Ni addition significantly decreased the thickness of intermetallic compound (IMC) layer on the interfaces, but did not change the phase structure of Al13Fe4. Furthermore, precipitate phase in the welded seams changed from Al6Fe to Al9FeNi, and the quantity of precipitate phases decreased from 12 to 9% approximately. Finally, effect of Ni powder's addition on the joint was analyzed and discussed. The reduction in the thickness of IMC and quantity of precipitate phases are beneficial to joint properties.

  14. 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.

  15. Mechanical and interfacial characterization of laser welded Co-Cr alloy with different joint configurations

    PubMed Central

    Kokolis, John; Chakmakchi, Makdad; Theocharopoulos, Antonios; Prombonas, Anthony

    2015-01-01

    PURPOSE The mechanical and interfacial characterization of laser welded Co-Cr alloy with two different joint designs. MATERIALS AND METHODS Dumbbell cast specimens (n=30) were divided into 3 groups (R, I, K, n=10). Group R consisted of intact specimens, group I of specimens sectioned with a straight cut, and group K of specimens with a 45° bevel made at the one welding edge. The microstructure and the elemental distributions of alloy and welding regions were examined by an SEM/EDX analysis and then specimens were loaded in tension up to fracture. The tensile strength (TS) and elongation (?) were determined and statistically compared among groups employing 1-way ANOVA, SNK multiple comparison test (?=.05) and Weibull analysis where Weibull modulus m and characteristic strength ?? were identified. Fractured surfaces were imaged by a SEM. RESULTS SEM/EDX analysis showed that cast alloy consists of two phases with differences in mean atomic number contrast, while no mean atomic number was identified for welded regions. EDX analysis revealed an increased Cr and Mo content at the alloy-joint interface. All mechanical properties of group I (TS, ?, m and ??) were found inferior to R while group K showed intermediated values without significant differences to R and I, apart from elongation with group R. The fractured surfaces of all groups showed extensive dendritic pattern although with a finer structure in the case of welded groups. CONCLUSION The K shape joint configuration should be preferred over the I, as it demonstrates improved mechanical strength and survival probability. PMID:25722836

  16. Hydrogen permeability over the joint weld of the steel parts of fusion reactor with magnet confinement of plasma

    NASA Astrophysics Data System (ADS)

    Fedorov, V. V.; Dyomina, E. V.; Zasadny, T. M.; Ivanov, L. I.; Prusakova, M. D.; Vinogradova, N. A.; Zabelin, A. M.

    2002-12-01

    Hydrogen and its isotopes diffusion and permeability over the laser joint weld of low-activation 10Cr9WVA ferritic steels have been studied. Welding of steel sheets were produced with the help of Russian gas laser TL-5M type ( l=10.6 mm, P=2.5 kW) in He atmosphere with the rate of 66 mm/s. Hydrogen diffusion over the joint welds was detected by the conventional method of electrical resistance measurement. By this way, the kinetics of resistance changes during hydrogenation of specimens engraved from weld metal, neighboring zone of thermal effect as well as basic metal have been determined. Coefficients of hydrogen diffusion were measured in the temperature range from 773 to 1073 K. So, for 10Cr9WVA steel at 873 K it was established that the hydrogen diffusion coefficient in the weld metal is approximately 10 times higher than in the basic metal, and three times higher than that in the zone of thermal effect. Hydrogen permeability over the joint weld specimens was measured by the Dines-Barrer method on the volummetric setup. It was established that the hydrogen flux over the laser joint weld is significantly (up to two orders) more than that over the basic metal. Using the data on the hydrogen permeability and diffusion coefficient, the hydrogen solubility in the weld metal was estimated, which is several ten times higher than that in the basic metal of the steel investigated. As a result, it was concluded that welding the steel parts of the first wall of thermonuclear reactors with magnet confinement of plasma is undesirable due to possible tritium leaking into the environment. A possible way of decreasing the joint welds hydrogen permeability, including application of protective impermeable for hydrogen coatings, is considered.

  17. WELDING RESEARCH -s85WELDING JOURNAL

    E-print Network

    Zhang, YuMing

    skilled human welders can achieve good weld quality through observing the weld pool, the pool surface must contain suffi- cient information to judge weld quality, such as weld joint penetration. Mean- whileWELDING RESEARCH -s85WELDING JOURNAL ABSTRACT. Measurement of weld pool surface is a difficult

  18. Comparative analysis of the friction stir welded aluminum-magnesium alloy joint grain structure

    NASA Astrophysics Data System (ADS)

    Zaikina, A. A.; Sizova, O. V.; Novitskaya, O. S.

    2015-10-01

    A comparative test of the friction stir welded aluminum-magnesium alloy joint microstructure for plates of a different thickness was carried out. Finding out the structuring regularities in the weld nugget zone, that is the strongest zone of the weld, the effects of temperature-deformational conditions on the promotion of a metal structure refinement mechanism under friction stir welding can be determined. In this research friction stir welded rolled plates of an AMg5M alloy; 5 and 8 mm thick were investigated. Material fine structure pictures of the nugget zone were used to identify and measure subgrain and to define a second phase location. By means of optical microscopy it was shown that the fine-grained structure developed in the nugget zone. The grain size was 5 flm despite the thickness of the plates. In the sample 5.0 mm thick grains were coaxial, while in the sample 8.0 mm thick grains were elongate at a certain angle to the tool travel direction.

  19. Effect of high temperature aging on bonded and weld bonded joints

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.

    1975-01-01

    Development of adhesives for applications requiring long-term service at temperatures up to 600 F is discussed. This development work utilizes polyimide (PI) and polyphenylquinoxaline (PPQ) resin technology worked out previously. The resultant adhesives are evaluated in structural joints of titanium, steel and composite adherends and in honeycomb sandwich panels. Suitable adhesives also are evaluated in weld bonded titanium alloy joints. Testing includes determination of long-term aging of stressed and unstressed specimens at temperatures from about 450 F to 600 F as well as under dynamic fatigue conditions.

  20. Distributed strain measurement of welded tubular joint with long gauge FBG

    NASA Astrophysics Data System (ADS)

    Murayama, H.; Kageyama, K.; Ohara, K.; Uzawa, K.; Kanai, M.; Igawa, H.

    2008-04-01

    Strain along a welded joint submitted to a load can fluctuate because of inhomogeneity in thickness or residual stress distributions and defects. Inversely, strain fluctuation may represent such inhomogeneities or defects. We applied the distributed strain sensing technique with a long gauge FBG to monitoring strain distributions along a welded tubular joint of a steel pipe. By using this sensing technique, we can measure a strain distribution at an arbitrary position along a FBG with the high spatial resolution less than 1 mm. In the tensile test of the steel pipe, we could successfully measure the strain distribution along the weld line of about 100 mm in length. We also observed the strain fluctuating sharply in some areas and acoustic emissions were simultaneously detected by the other sensors. In some areas where sharp fluctuations occurred, defects were observed by also computer tomography carried out after the tensile test. Applications for the sensing technique include health monitoring for other joint configurations, such as fastening and bonding.

  1. Dual-beam laser welding of AZ31B magnesium alloy in zero-gap lap joint configuration

    NASA Astrophysics Data System (ADS)

    Harooni, Masoud; Carlson, Blair; Kovacevic, Radovan

    2014-03-01

    Porosity within laser welds of magnesium alloys is one of the main roadblocks to achieving high quality joints. One of the causes of pore formation is the presence of pre-existing coatings on the surface of magnesium alloy such as oxide or chromate layers. In this study, single-beam and dual-beam laser heat sources are investigated in relation to mitigation of pores resulting from the presence of the as-received oxide layer on the surface of AZ31B-H24 magnesium alloy during the laser welding process. A fiber laser with a power of up to 4 kW is used to weld samples in a zero-gap lap joint configuration. The effect of dual-beam laser welding with different beam energy ratios is studied on the quality of the weld bead. The purpose of this paper is to identify the beam ratio that best mitigates pore formation in the weld bead. The laser molten pool and the keyhole condition, as well as laser-induced plasma plume are monitored in real-time by use of a high speed charge-coupled device (CCD) camera assisted with a green laser as an illumination source. Tensile and microhardness tests were used to measure the mechanical properties of the laser welded samples. Results showed that a dual-beam laser configuration can effectively mitigate pore formation in the weld bead by a preheating-welding mechanism.

  2. Experimental and numerical studies on the issues in laser welding of light-weight alloys in a zero-gap lap joint configuration

    NASA Astrophysics Data System (ADS)

    Harooni, Masoud

    It is advantageous for the transportation industry to use lightweight components in the structure in order to save mass and reduce CO2 emissions. One of the lightest structural metals, magnesium, fulfills the need for mass reduction within the automotive industry. Many of the body structure components in the automotive industry are assembled using joining processes such as fusion welding. Furthermore, laser welding offers a low heat impact, high process rate, joining method which is becoming increasingly popular as the cost for laser systems continues to decrease. However, there is a limited body of work investigating the laser welding of magnesium and therefore, in the current study, different techniques and methods for laser welding of magnesium alloys are numerically and experimentally studied in order to optimize process parameters to achieve high quality welds. A feasibility study was designed in order to study the effect of various laser welding process parameters (such as laser power levels and welding speeds) on weld quality. Three regression models were developed to find the best fit model that relates process parameters to the shear load of the weld. Furthermore, to understand the effect of laser welding parameters on temperature distribution in laser welding of AZ31B magnesium alloy, a numerical model was developed. A rotary Gaussian volumetric body heat source was applied in this study to obtain the temperature history during the laser welding process. Cross-sectional views of the weld beads, temperature history recorded by thermocouples, and temperature history recorded by infrared camera were used to validate the numerical model. In order to study the real-time dynamic behavior of the molten pool and the keyhole during the welding process, a high speed charge-coupled device (CCD) assisted with a green laser as an illumination source was used. In order to observe the presence of pores, prior studies destructively evaluated the weld bead however; in the current study a non-destructive evaluation method based on spectroscopy is proposed to detect the presence of pores in the lap joint of laser welded AZ31B magnesium alloy. The electron temperature that is calculated by the Boltzmann plot method is correlated to the presence of pores in the weld bead. A separate series of experiments was performed to evaluate the effect of an oxide coating layer on the dynamic behavior of the molten pool in the laser welding of an AZ31B magnesium alloy in a zero-gap lap joint configuration. A high speed CCD camera assisted with a green laser as an illumination source was selected to record the weld pool dynamics. Another technique used in this study was two-pass laser welding process to join AZ31B magnesium sheet in a zero-gap, lap-shear configuration. Two groups of samples including one pass laser welding (OPLW) and two pass laser welding (TPLW) were studied. In the two pass laser welding procedure, the first pass is performed by a defocused laser beam on the top of the two overlapped sheets in order to preheat the faying surface prior to laser welding, while the second pass is applied to melt and eventually weld the samples. Tensile and microhardness tests were used to measure the mechanical properties of the laser welded samples. A spectrometer was also used in real-time to correlate pore formation with calculated electron temperature using the Boltzmann plot method. The results of calculated electron temperature confirmed the previous results in earlier chapter. Magnesium and aluminum are two alloys which are used in different industries mainly due to their light weight. The main use of these two alloys is in automotive industry. Since different parts of the automobiles can be manufactured with each of these two alloys, it is essential to evaluate the joining feasibility of dissimilar metals such as aluminum to magnesium. A 4 kW fiber laser is used to join AZ31B magnesium alloy to AA 6014 using an overlap joint configuration. Two different methods including focused beam laser welding (FBLW) and defocused beam laser welding

  3. Improvement of ultrasonic characteristics in butt-welded joint of austenitic stainless steel using magnetic stirring method

    SciTech Connect

    Tanosaki, M.; Yoshikawa, K.; Arakawa, T.

    1995-08-01

    Magnetic Stirring Method of Tungsten Inert Gas(TIG) Welding are applied to butt-welded joint of austenitic stainless steel. The purpose of this method is to refine the welded structure and to improve the ultrasonic characteristics. In the conventional method of ultrasonic test in austenitic stainless steel weldments, dendritic solidification structure of weldment prevents smooth ultrasonic beam transmission. The tests are performed in three welding conditions; One is conventional TIG welding (without magnetic stirring), the other two are TIG welding using magnetic stirring method. Each test piece is evaluated by observing macro structure of cross section and by several ultrasonic tests examining pulse amplitudes, beam path length and proceeding beam direction. The detectability of artificial notches in weldment is also investigated and compared.

  4. Methods for Improving Laser Beam Welding Efficiency

    NASA Astrophysics Data System (ADS)

    Sokolov, Mikhail; Salminen, Antti

    The aim of this paper is to evaluate methods for improving laser beam welding efficiency, namely, obtaining increased penetration depth and enhanced weld quality without an increase in laser power or a decrease in welding speed. Increased efficiency can be realized with several techniques: butt joint edge surface modifications, preheating and modifications of ambient atmospheric conditions.

  5. 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…

  6. Assessment of Creep Strain Distribution Across Base Metal of 316LN Austenitic Stainless Steel Weld Joint by an EBSD-Based Parameter

    NASA Astrophysics Data System (ADS)

    Vijayanand, V. D.; Ganesan, V.; Ganesh Kumar, J.; Parameswaran, P.; Naveena; Laha, K.

    2015-11-01

    Electron backscatter diffraction (EBSD) analysis has been used to estimate the accumulated strain in base metal region of 316LN austenitic stainless steel weld joints, creep tested at 923 K (650 °C), and at stresses of 175 and 225 MPa. The variation in strength of weld metal, heat-affected zone (HAZ), and base metal-induced stress and strain gradients across the weld joint under creep exposure. Finite element analysis (FEA) of von-Mises stress distribution across the joint has been carried out on incorporating strength of different constituents of the joint, derived by miniature specimen testing techniques. The FEA simulations revealed preferential accumulation of von-Mises stress in the base metal region near to HAZ. The variation in accumulated plastic strain across the base metal has been estimated using a `crystal deformation' ( C d) parameter which quantifies the orientation spread within a grain. This parameter was obtained by EBSD analysis carried out using a scanning electron microscope. The trend in variation of accumulated plastic strain across the base metal accounted well with the von-Mises stress variation, which causes plastic deformation. The plastic strain in the base metal in both the stress levels was found to accumulate preferentially near to the HAZ and reduced steadily toward the ridge at the end of specimen. Transmission electron microscopic study has been carried out to substantiate the findings of the EBSD investigation.

  7. Assessment of Creep Strain Distribution Across Base Metal of 316LN Austenitic Stainless Steel Weld Joint by an EBSD-Based Parameter

    NASA Astrophysics Data System (ADS)

    Vijayanand, V. D.; Ganesan, V.; Ganesh Kumar, J.; Parameswaran, P.; Naveena; Laha, K.

    2015-08-01

    Electron backscatter diffraction (EBSD) analysis has been used to estimate the accumulated strain in base metal region of 316LN austenitic stainless steel weld joints, creep tested at 923 K (650 °C), and at stresses of 175 and 225 MPa. The variation in strength of weld metal, heat-affected zone (HAZ), and base metal-induced stress and strain gradients across the weld joint under creep exposure. Finite element analysis (FEA) of von-Mises stress distribution across the joint has been carried out on incorporating strength of different constituents of the joint, derived by miniature specimen testing techniques. The FEA simulations revealed preferential accumulation of von-Mises stress in the base metal region near to HAZ. The variation in accumulated plastic strain across the base metal has been estimated using a `crystal deformation' (C d) parameter which quantifies the orientation spread within a grain. This parameter was obtained by EBSD analysis carried out using a scanning electron microscope. The trend in variation of accumulated plastic strain across the base metal accounted well with the von-Mises stress variation, which causes plastic deformation. The plastic strain in the base metal in both the stress levels was found to accumulate preferentially near to the HAZ and reduced steadily toward the ridge at the end of specimen. Transmission electron microscopic study has been carried out to substantiate the findings of the EBSD investigation.

  8. Sensitization of 21% Cr Ferritic Stainless Steel Weld Joints Fabricated With/Without Austenitic Steel Foil as Interlayer

    NASA Astrophysics Data System (ADS)

    Wu, Wenyong; Hu, Shengsun; Shen, Junqi; Ma, Li; Han, Jian

    2015-04-01

    The effects of sensitization heat treatment on the microstructure and electrochemical behavior of 21% Cr ferritic stainless steel weld joints with or without 309L austenite stainless steel as an interlayer were investigated. The joints were processed by pulsed gas tungsten arc welding. With the interlayer, grains in weld bead were refined, and almost fully ferrite. When the joints with the interlayer were maintained at 500 °C for 1 and 4 h, no microstructure changes occurred, whereas Widmanstatten austenite and needle-like austenite formed in the weld bead after sensitization at 815 °C for 1 h. In general, sensitization treatment worsens the corrosion resistance of welds, but the resistance of samples with the 4-h treatment at 500 °C recovered in part compared to those subjected to sensitization at 500 °C for 1 h. This could be due to Cr diffusion from the ferrite that heals the chromium-depletion zone along the grain boundary. However, an increase in temperature does not have the same effect. The corrosion morphology of samples in the weld bead is different from those in base metal after heat treatment at 500 °C for 1 h; in base metal, pitting corrosion occurs, whereas grain boundary corrosion occurs in the weld bead. Corrosion morphology is closely associated with precipitation and segregation along the grain boundary.

  9. Reactor cooling water expansion joint bellows: The role of the seam weld in fatigue crack development

    SciTech Connect

    West, S.L.; Nelson, D.Z.; Louthan, M.R. Jr.

    1992-01-01

    The secondary cooling water system pressure boundary of Savannah River Site reactors includes expansion joints utilizing a thin-wall bellows. While successfully used for over thirty years, an occasional replacement has been required because of the development of small, circumferential fatigue cracks in a bellows convolute. One such crack was recently shown to have initiated from a weld heat-affected zone liquation microcrack. The crack, initially open to the outer surface of the rolled and seam welded cylindrical bellows section, was closed when cold forming of the convolutes placed the outer surface in residual compression. However, the bellows was placed in tension when installed, and the tensile stresses reopened the microcrack. This five to eight grain diameter microcrack was extended by ductile fatigue processes. Initial extension was by relatively rapid propagation through the large-grained weld metal, followed by slower extension through the fine-grained base metal. A significant through-wall crack was not developed until the crack extended into the base metal on both sides of the weld. Leakage of cooling water was subsequently detected and the bellows removed and a replacement installed.

  10. Reactor cooling water expansion joint bellows: The role of the seam weld in fatigue crack development

    SciTech Connect

    West, S.L.; Nelson, D.Z.; Louthan, M.R. Jr.

    1992-12-01

    The secondary cooling water system pressure boundary of Savannah River Site reactors includes expansion joints utilizing a thin-wall bellows. While successfully used for over thirty years, an occasional replacement has been required because of the development of small, circumferential fatigue cracks in a bellows convolute. One such crack was recently shown to have initiated from a weld heat-affected zone liquation microcrack. The crack, initially open to the outer surface of the rolled and seam welded cylindrical bellows section, was closed when cold forming of the convolutes placed the outer surface in residual compression. However, the bellows was placed in tension when installed, and the tensile stresses reopened the microcrack. This five to eight grain diameter microcrack was extended by ductile fatigue processes. Initial extension was by relatively rapid propagation through the large-grained weld metal, followed by slower extension through the fine-grained base metal. A significant through-wall crack was not developed until the crack extended into the base metal on both sides of the weld. Leakage of cooling water was subsequently detected and the bellows removed and a replacement installed.

  11. The susceptibility of low carbon steel welded joint to sulphide stress cracking (SSC)

    NASA Astrophysics Data System (ADS)

    Alshwigi, Mohamed A. M.; Musa, Salem. M.; Basir, Ali

    2013-12-01

    The resistance of low carbon steel pipes API 5L GR.B as welded joints to sulphide stress cracking SSC was tested using NACE Standard test method TM 0177_Method (C). Two stress levels of the material's yield strength were applied, 75 % ?y and 100 % ?y in three different conditions; as received, as welded, and stress relieved samples. Total of seventeen samples were tested; two as received samples without any welding process, six samples as heat treated, and nine samples as welded. The effect of hardness level on material's susceptibility to sulphide stress cracking was examined. Raw Natural Gas was used as a source of Hydrogen Sulphide (H2S) in the test, which represents the real environment that the material was exposed to. Results show that samples with high hardness (higher than 22 HRC) were failed the test which was expected as in the NACE Standard MR175. Samples with low hardness (lower than 22 HRC) were passed the test which was expected as in the NACE Standard MR175. The received samples of low hardness failed the test which was not expected.

  12. Checking weld penetration

    NASA Technical Reports Server (NTRS)

    Macfarlane, D. I.

    1979-01-01

    Fused wire in weld root area verifies weld penetration in electron-beam-welded joints. Method could be used in automotive, aircraft, and machinery manufacturing when electron-beam-welds cannot be inspected ultrasonically.

  13. Impact of tool wear on joint strength in friction stir spot welding of DP 980 steel

    SciTech Connect

    Miles, Michael; Ridges, Chris; Hovanski, Yuri; Peterson, Jeremy; Santella, M. L.; Steel, Russel

    2011-09-14

    Friction stir spot welding has been shown to be a viable method of joining ultra high strength steel (UHSS), both in terms of joint strength and process cycle time. However, the cost of tooling must be reasonable in order for this method to be adopted as an industrial process. Recently a new tool alloy has been developed, using a blend of PCBN and tungsten rhenium (W-Re) in order to improve the toughness of the tool. Wear testing results are presented for two of these alloys: one with a composition of 60% PCBN and 40% W-Re, and one with 70% PCBN and 30% W-Re. The sheet material used for all wear testing was 1.4 mm DP 980. Lap shear testing was used to show the relationship between tool wear and joint strength. The Q70 tool provided the best combination of wear resistance and joint strength.

  14. Effects of aging treatment and heat input on the microstructures and mechanical properties of TIG-welded 6061-T6 alloy joints

    NASA Astrophysics Data System (ADS)

    Peng, Dong; Shen, Jun; Tang, Qin; Wu, Cui-ping; Zhou, Yan-bing

    2013-03-01

    Aging treatment and various heat input conditions were adopted to investigate the microstructural evolution and mechanical properties of TIG welded 6061-T6 alloy joints by microstructural observations, microhardness tests, and tensile tests. With an increase in heat input, the width of the heat-affected zone (HAZ) increases and grains in the fusion zone (FZ) coarsen. Moreover, the hardness of the HAZ decreases, whereas that of the FZ decreases initially and then increases with an increase in heat input. Low heat input results in the low ultimate tensile strength of the welded joints due to the presence of partial penetrations and pores in the welded joints. After a simple artificial aging treatment at 175°C for 8 h, the microstructure of the welded joints changes slightly. The mechanical properties of the welded joints enhance significantly after the aging process as few precipitates distribute in the welded seam.

  15. The use of ion beam cleaning to obtain high quality cold welds with minimal deformation

    NASA Technical Reports Server (NTRS)

    Sater, B. L.; Moore, T. J.

    1978-01-01

    A variation of cold welding is described which utilizes an ion beam to clean mating surfaces prior to joining in a vacuum environment. High quality solid state welds were produced with minimal deformation.

  16. EFFECT OF TOOL FEATURE ON THE JOINT STRENGTH OF DISSIMILAR FRICTION STIR LAP WELDS

    SciTech Connect

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

    2011-04-25

    Several variations of friction stir tools were used to investigate the effects on the joint strengths of dissimilar friction stir lap welds. In the present lap weld configuration the top sheet was a 2.32 mm thick Mg (AZ 31) alloy. The bottom sheet consisted of two different steels, a (i) 0.8 mm thick electro-galvanized (EG) mild steel, or a (ii) 1.5 mm thick hot dip galvanized (HDG) high strength low alloy (HSLA) steel. Initially the tool shape was modified to accommodate the material, at which point the tool geometry was fixed. With a fixed tool geometry an additional feature was added to the pin bottom on one of the tools by incorporating a short hard insert, which would act as a stronger bottom sheet cutter. The effects of such modification on the unguided lap shear strength, and associated microstructural changes are discussed in this study.

  17. Increasing Strength and Operational Reliability of Fixed Joints of Tubes by MMA Welding

    NASA Astrophysics Data System (ADS)

    Il'yaschenko, D. P.; Chinakhov, D. A.; Danilov, V. I.; Schlyakhova, G. V.; Gotovschik, Y. M.

    2015-09-01

    This paper presents peculiar properties of structure formation, phase and chemical composition while welding of low-alloy steel 09MnSi2-l depending on the dynamic characteristics of power sources of different types. Proper selection of power sources enables to decrease burning of alloy elements in metal of weld (Mn by 14% and Si by 17% of the weight ratio), to obtain more homogenous structure of deposited metal, to reduce length of heat-affected zone by 50% and to improve impact strength by 4-9%.

  18. Effect of Heat Input Pulse on the Structure and Properties of Welded Joints of Steels Ferritic-Pearlitic Class, Operating Under Low-Frequency Temperature-Force Loading

    NASA Astrophysics Data System (ADS)

    Saraev, Y. N.; Bezborodov, V. P.; Putilova, E. A.

    2015-09-01

    We have investigated the influence of the modes of adaptive pulse-arc welding and surfacing on the structure and physical-mechanical properties of welded joints of steel 09Mn2Si and the surfaced composition of this steel coated with modified powder material of chromium carbide with the submicrocrystalline structure. It is shown that the pulsed mode of welding and surfacing can improve the homogeneity of the structure of the welded joint of steel and surfaced coating and reduce the grain size of metals in both of them. Structural changes lead to the increase in ductility and toughness of the weld metal.

  19. First samples of Ti and Nb tubes explosion welding joint with stainless steel for ILC 1.8 K cryomodule

    NASA Astrophysics Data System (ADS)

    Sabirov, B. M.; Budagov, J. A.; Shirkov, G. D.

    2013-07-01

    The world first samples of Ti and Nb tubes joint with stainless steel ones by an explosion welding by the JINR-VNIIEF-FNAL-INFN cooperation were manufactured in the frame of ILC R&D programe. An applying methods of relaxation of residual tensions (after explosion and electron beam welding), macro- and microanalyses of welding seam and cryogenic tests of the samples produced manifest the achievement of high mechanic strength (?250 MPa/share) of welding seam, solidity and leak absence on 10-10 l atm/s level at 1.8 K. The explosion welding technology and methods introducing to industrial manufacturing of the 4-th generation of cryomodule of TESLA TYPE DESIGN can exclude the Ti—communications, connect the Nb—cavity with stainless steel vessel and reduce significantly the accelerator cost.

  20. Effect of Post-Weld Heat Treatment on Microstructure and Mechanical Properties of X52 Linepipe HFIW Joints

    NASA Astrophysics Data System (ADS)

    Kavousi Sisi, A.; Mirsalehi, S. E.

    2015-04-01

    In the present paper, influences of normalization heat treatment on microstructural and mechanical properties of high-frequency induction welded (HFIW) joints of X52 steel have been investigated. HFIW joints were post-weld heat treated at different times and temperatures. The microstructure and mechanical properties of the heat treated joints were then comprehensively investigated. Based on the results, a proper normalization of the primary fine grain steel caused the grain size to increase; but because of converting brittle microstructure into ductile microstructure, it caused the toughness to increase also. In addition, the ductility of the joints was enhanced. Nevertheless, tensile strength, yield strength, and hardness were reduced. The results showed that 950 °C was the optimum normalization temperature from the standpoint of fracture toughness for the X52 steel joints. At 1050 °C, the carbides and/or nitrides in the steel dissolved, and excessive grain growth occurred. Hence, the maximum allowable temperature for normalization was found to be 1000 °C.

  1. Effects of laser heat treatment on the fracture morphologies of X80 pipeline steel welded joints by stress corrosion

    NASA Astrophysics Data System (ADS)

    Kong, De-jun; Ye, Cun-dong

    2014-09-01

    The surfaces of X80 pipeline steel welded joints were processed with a CO2 laser, and the effects of laser heat treatment (LHT) on H2S stress corrosion in the National Association of Corrosion Engineers (NACE) solution were analyzed by a slow strain rate test. The fracture morphologies and chemical components of corrosive products before and after LHT were analyzed by scanning electron microscopy and energy-dispersive spectroscopy, respectively, and the mechanism of LHT on stress corrosion cracking was discussed. Results showed that the fracture for welded joints was brittle in its original state, while it was transformed to a ductile fracture after LHT. The tendencies of hydrogen-induced corrosion were reduced, and the stress corrosion sensitivity index decreased from 35.2% to 25.3%, indicating that the stress corrosion resistance of X80 pipeline steel welded joints has been improved by LHT.

  2. 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.

  3. Application of laser in seam welding of dissimilar steel to aluminium joints for thick structural components

    NASA Astrophysics Data System (ADS)

    Meco, S.; Pardal, G.; Ganguly, S.; Williams, S.; McPherson, N.

    2015-04-01

    Laser welding-brazing technique, using a continuous wave (CW) fibre laser with 8000 W of maximum power, was applied in conduction mode to join 2 mm thick steel (XF350) to 6 mm thick aluminium (AA5083-H22), in a lap joint configuration with steel on the top. The steel surface was irradiated by the laser and the heat was conducted through the steel plate to the steel-aluminium interface, where the aluminium melts and wets the steel surface. The welded samples were defect free and the weld micrographs revealed presence of a brittle intermetallic compounds (IMC) layer resulting from reaction of Fe and Al atoms. Energy Dispersive Spectroscopy (EDS) analysis indicated the stoichiometry of the IMC as Fe2Al5 and FeAl3, the former with maximum microhardness measured of 1145 HV 0.025/10. The IMC layer thickness varied between 4 to 21 ?m depending upon the laser processing parameters. The IMC layer showed an exponential growth pattern with the applied specific point energy (Esp) at a constant power density (PD). Higher PD values accelerate the IMC layer growth. The mechanical shear strength showed a narrow band of variation in all the samples (with the maximum value registered at 31.3 kN), with a marginal increase in the applied Esp. This could be explained by the fact that increasing the Esp results into an increase in the wetting and thereby the bonded area in the steel-aluminium interface.

  4. Tensile properties of a titanium modified austenitic stainless steel and the weld joints after neutron irradiation

    SciTech Connect

    Shiba, K.; Ioka, I.; Jitsukawa, S.; Hamada, A.; Hishinuma, A.

    1996-10-01

    Tensile specimens of a titanium modified austenitic stainless steel and its weldments fabricated with Tungsten Inert Gas (TIG) and Electron Beam (EB) welding techniques were irradiated to a peak dose of 19 dpa and a peak helium level of 250 appm in the temperature range between 200 and 400{degrees}C in spectrally tailored capsules in the Oak Ridge Research Reactor (ORR) and the High Flux Isotope Reactor (HFIR). The He/dpa ratio of about 13 appm/dpa is similar to the typical helium/dpa ratio of a fusion reactor environment. The tensile tests were carried out at the irradiation temperature in vacuum. The irradiation caused an increase in yield stress to levels between 670 and 800 MPa depending on the irradiation temperature. Total elongation was reduced to less than 10%, however the specimens failed in a ductile manner. The results were compared with those of the specimens irradiated using irradiation capsules producing larger amount of He. Although the He/dpa ratio affected the microstructural change, the impact on the post irradiation tensile behavior was rather small for not only base metal specimens but also for the weld joint and the weld metal specimens.

  5. Tensile properties of a titanium modified austenitic stainless steel and the weld joints after neutron irradiation

    SciTech Connect

    Shiba, Kiyoyuki; Ioka, Ikuo; Jitsukawa, Shiro; Hamada, Shozo; Hishinuma, Atkinichi; Robertson, J.P.

    1999-10-01

    Tensile specimens of a titanium modified austenitic stainless steel and its weldments fabricated with Tungsten Inert Gas (TIG) and Electron Beam (EB) welding techniques were irradiated to a peak dose of 19 dpa and a peak helium level of 250 appm in the temperature range between 200 and 400 C in spectrally tailored capsules in the Oak Ridge Research Reactor (ORR) and the High Flux Isotope Reactor (HFIR). The He/dpa ratio of about 13 appm/dpa is similar to the typical helium/.dpa ratio of a fusion reactor environment. The tensile tests were carried out at the irradiation temperature in vacuum. The irradiation caused an increase in yield stress to levels between 670 and 800 MPa depending on the irradiation temperature. Total elongation was reduced to less than 10%, however the specimens failed in a ductile manner. The results were compared with those of the specimens irradiated using irradiation capsules producing larger amount of He. Although the He/dpa ratio affected the microstructural change, the impact on the post irradiation tensile behavior was rather small not only for base metal specimens but also for the weld joint and the weld metal specimens.

  6. Narrow gap laser welding

    DOEpatents

    Milewski, John O. (Santa Fe, NM); Sklar, Edward (Santa Fe, NM)

    1998-01-01

    A laser welding process including: (a) using optical ray tracing to make a model of a laser beam and the geometry of a joint to be welded; (b) adjusting variables in the model to choose variables for use in making a laser weld; and (c) laser welding the joint to be welded using the chosen variables.

  7. Narrow gap laser welding

    DOEpatents

    Milewski, J.O.; Sklar, E.

    1998-06-02

    A laser welding process including: (a) using optical ray tracing to make a model of a laser beam and the geometry of a joint to be welded; (b) adjusting variables in the model to choose variables for use in making a laser weld; and (c) laser welding the joint to be welded using the chosen variables. 34 figs.

  8. The use of ion beam cleaning to obtain high quality cold welds with minimal deformation

    NASA Technical Reports Server (NTRS)

    Sater, B. L.; Moore, T. J.

    1978-01-01

    This paper describes a variation of cold welding which utilizes an ion beam to clean mating surfaces prior to joining in a vacuum environment. High quality solid state welds were produced with minimal deformation. Due to experimental fixture limitation in applying pressure work has been limited to a few low yield strength materials.

  9. Influence of tacking sequence on residual stress and distortion of single sided fillet submerged arc welded joint

    NASA Astrophysics Data System (ADS)

    Mondal, Arpan Kumar; Biswas, Pankaj; Bag, Swarup

    2015-07-01

    Submerged arc welding (SAW) is advantageous for joining high thickness materials in large structure due to high material deposition rate. The non-uniform heating and cooling generates the thermal stresses and subsequently the residual stresses and distortion. The longitudinal and transverse residual stresses and angular distortion are generally measured in large panel structure of submerged arc welded fillet joints. Hence, the objective of this present work is to quantify the amount of residual stress and distortion in and around the weld joint due to positioning of stiffeners tack. The tacking sequence influences the level of residual stress and proper controlling of tacking sequences is required to minimize the stress. In present study, an elasto-plastic material behavior is considered to develop the thermo mechanical model which predicts the residual stress and angular distortion with varying tacking sequences. The simulated result reveals that the tacking sequence heavily influences the residual stress and deformation pattern of the single sided fillet joint. The finite element based numerical model is calibrated by comparing the experimental data from published literature. Henceforth, the angular distortions are measured from an in-house developed experimental set-up. A fair agreement between the predicted and experimental results indicates the robustness of the developed numerical model. However, the most significant conclusion from present study states that tack weld position should be placed opposite to the fillet weld side to minimize the residual stress.

  10. Numerical study of local PWHT condition for EB welded joint between first and side walls in ITER-TBM

    NASA Astrophysics Data System (ADS)

    Serizawa, Hisashi; Nakamura, Shinichiro; Tanigawa, Hiroyasu; Ogiwara, Hiroyuki; Murakawa, Hidekazu

    2013-11-01

    The stress relaxation behavior of post-weld heat treatment (PWHT) F82H was examined to determine the appropriate PWHT condition for electron beam welded joints between the first and side walls of the International Thermonuclear Experimental Reactor (ITER) test blanket module. Thermal elastic-plastic creep finite element analyses were conducted assuming Norton creep law. Uniform heat treatment and four types of local heating near the weld line were studied. Numerical analyses concluded that the welding residual stress could be reduced by a local heat treatment near the penetration from both the first and side walls, where the cooling area and rate could be controlled. In addition, the stress on the channel surface in the first wall was found to decrease to less than 50 MPa with the appropriate local PWHT.

  11. Effects of the types of overlap on the mechanical properties of FSSW welded AZ series magnesium alloy joints

    NASA Astrophysics Data System (ADS)

    Wang, Dan; Shen, Jun; Wang, Lin-Zhi

    2012-03-01

    The effects of the types of overlap on the mechanical properties of the friction stir spot welding (FSSW) welded AZ series magnesium alloy joints were investigated by microstructural observations, microhardness tests, and tensile tests. The results show that the microstructure of the stir zone adjacent to the periphery of the rotating pin is mainly composed of the upper sheet. The average distance D between the longitudinal segment of the curved interface and the keyhole periphery, the tensile shear force, and the microhardness of the stir zone of the FSSW welded AZ61 alloy joint are the highest in all samples. During FSSW of AZ31 and AZ61 dissimilar magnesium alloys, the irregular deformation of the longitudinal segment of the curved interface appears, while the microhardness of the stir zone is higher when AZ61 alloy is the upper sheet. Moreover, the microhardness of the stir zone increases initially and then decreases sharply in the longitudinal test position.

  12. Development of Mathematic Model of Cold Welding at Drawing-up the Flange Joint of Pneumohydraulic Systems

    NASA Astrophysics Data System (ADS)

    Boyko, Y. S.

    2002-01-01

    Provision of high airtightness of joints of pipe- lines of pneumohydraulic systems (PHS) operating under high pressure, is an important task for designing and operation of launch vehicles. In the process of assembly and tests of PHS of launch vehicles, it was found that detachable flange joints do not lose their airtightness after removal of fastening elements, even in conditions of standard loads. The task of this work is in studying a phenomenon connected with initiation of the observed effect of adhesion and also stresses in the zone of contact at drawing- up the flange detachable joints with a plastic gasket. Investigations have shown that density of the joint is kept due to cold welding, as the created conditions are helpful for that process. As a result of the investigations performed, we have developed a mathematic model which is based on application of the theory of metal bonds; that theory explains the essence of the effect observed. Basic factors which provide optimum mode of cold welding, are effort which can cause microplastic deformation and form maximum contact, and also quality of processing the material of the surfaces joined. Strength of all- metal joint depends on factual area of contact. So, surface processing quality defines a configuration of microbulges which come into contact not simultaneously, and their stressed state is different, and it influences the character of dependence of the contact area on loading. Results of calculations by the mathematic model are expressed by dependencies of factual area of contact and a single diameter of the contact spot on the load applied which compresses the materials with various physical properties, and on the surface processing quality. The mathematic model allows to explain the common character of the cold welding process in detachable flange joints with the plastic gasket, to determine the nature and the character of acting forces, to define kinetics and the mechanism of formation of cold welding of detachable joints. It also helps to analyze the state of airtightness and to metal welding technology in the plastic state at drawing- up of detachable flange joints with a plastic gasket and to review cold welding as a positive phenomenon.

  13. Weld penetration and defect control

    SciTech Connect

    Chin, B.A.

    1992-05-15

    Highly engineered designs increasingly require the use of improved materials and sophisticated manufacturing techniques. To obtain optimal performance from these engineered products, improved weld properties and joint reliability are a necessarily. This requirement for improved weld performance and reliability has led to the development of high-performance welding systems in which pre-programmed parameters are specified before any welding takes place. These automated systems however lack the ability to compensate for perturbations which arise during the welding process. Hence the need for systems which monitor and control the in-process status of the welding process. This report discusses work carried out on weld penetration indicators and the feasibility of using these indicators for on-line penetration control.

  14. A Fatigue Life Prediction Model of Welded Joints under Combined Cyclic Loading

    NASA Astrophysics Data System (ADS)

    Goes, Keurrie C.; Camarao, Arnaldo F.; Pereira, Marcos Venicius S.; Ferreira Batalha, Gilmar

    2011-01-01

    A practical and robust methodology is developed to evaluate the fatigue life in seam welded joints when subjected to combined cyclic loading. The fatigue analysis was conducted in virtual environment. The FE stress results from each loading were imported to fatigue code FE-Fatigue and combined to perform the fatigue life prediction using the S x N (stress x life) method. The measurement or modelling of the residual stresses resulting from the welded process is not part of this work. However, the thermal and metallurgical effects, such as distortions and residual stresses, were considered indirectly through fatigue curves corrections in the samples investigated. A tube-plate specimen was submitted to combined cyclic loading (bending and torsion) with constant amplitude. The virtual durability analysis result was calibrated based on these laboratory tests and design codes such as BS7608 and Eurocode 3. The feasibility and application of the proposed numerical-experimental methodology and contributions for the technical development are discussed. Major challenges associated with this modelling and improvement proposals are finally presented.

  15. Detection of defects in laser welding of AZ31B magnesium alloy in zero-gap lap joint configuration by a real-time spectroscopic analysis

    NASA Astrophysics Data System (ADS)

    Harooni, Masoud; Carlson, Blair; Kovacevic, Radovan

    2014-05-01

    The effect of surface oxide layer existing at the lap-joint faying surface of magnesium sheets is investigated on the keyhole dynamics of the weld pool and weld bead qualities. It is observed that by removing the oxide layer from the faying surface of the lap joint, a high quality weld can be achieved in the laser welding process. However, the presence of an oxide layer deteriorates the quality of the weld by forming pores at the interface of the two overlapped sheets. The purpose of this paper is to identify the correlation between the integrity of the weld and the interaction between the laser and material. A spectroscopy sensor was applied to detect the spectra emitted from a plasma plume during the laser welding of AZ31B magnesium alloy in a zero-gap lap joint configuration. The electron temperature was calculated by applying a Boltzmann plot method based on the detected spectra, and the correlation between the pore formation and the spectral signals was studied. The laser molten pool and the keyhole condition were monitored in real-time by a high speed charge-coupled device (CCD) camera. A green laser was used as an illumination source in order to detect the influence of the oxide layer on the dynamic behavior of the molten pool. Results revealed that the detected spectrum and weld defects had a meaningful correlation for real-time monitoring of the weld quality during laser welding of magnesium alloys.

  16. Welding Many Thin Metal Layers

    NASA Technical Reports Server (NTRS)

    Hartwell, B. O.; Caras, P.; Hobbes, P. H.

    1985-01-01

    Electron-beam welding yields reliable, leakproof joints. Welding bands (also called "doublers") sandwiched between layers welded to increase final weld-section thickness. New technique ensures repeatable leakproof assemblies.

  17. Periscope For Viewing Weld Penetration

    NASA Technical Reports Server (NTRS)

    Gordon, Stephen S.; Marman, Jonathan M.

    1988-01-01

    Periscope enables viewing of weld joint from inside cylindrical duct to determine when weld penetration occurs. Supplies steady stream of inert gas to shield joint. Device used to calibrate and evaluate techniques for sensing weld penetration.

  18. 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.

  19. Analysis of Formation and Interfacial WC Dissolution Behavior of WC-Co/Invar Laser-TIG Welded Joints

    NASA Astrophysics Data System (ADS)

    Xu, P. Q.; Ren, J. W.; Zhang, P. L.; Gong, H. Y.; Yang, S. L.

    2013-02-01

    During the valve fabrication, hard metal is welded to stainless steel or invar alloy for sealing purposes because of its good heat resistance operating at 500 °C. However, WC (tungsten carbide) dissolution in weld pool softens the hard metal and decreases mechanical properties near the hard metal/weld interface. In order to analyze the WC dissolution in welded joint, joining of hard metal and invar alloy was carried out using laser-tungsten inert gas hybrid welding method. Microstructures of the weld region, chemical composition were investigated using optical microscope, scanning electron microscopy, and EDAX, respectively. Mechanical properties such as microhardness and four-point bend strength test were performed. Larger and smaller WC dissolution and WC dissolution through transition layer based on thermo-dynamics were discussed. The results thus indicate that WC dissolution led to cellular microstructure, columnar crystal, and transition layer under the effect of laser beam and tungsten arc. WC dissolution was affected by metal ions Fe+, Ni+, Co+ exchange in W-M-C system, and WC grain growth was driven by forces caused by laser beam and tungsten arc in larger WC, smaller WC, and liquid Fe, Ni systems.

  20. Improvement of localised corrosion resistance of AISI 2205 Duplex Stainless Steel joints made by gas metal arc welding under electromagnetic interaction of low intensity

    NASA Astrophysics Data System (ADS)

    García-Rentería, M. A.; López-Morelos, V. H.; García-Hernández, R.; Dzib-Pérez, L.; García-Ochoa, E. M.; González-Sánchez, J.

    2014-12-01

    The resistance to localised corrosion of AISI 2205 duplex stainless steel plates joined by Gas Metal Arc Welding (GMAW) under the effect of electromagnetic interaction of low intensity (EMILI) was evaluated with sensitive electrochemical methods. Welds were made using two shielding gas mixtures: 98% Ar + 2% O2 (M1) and 97% Ar + 3% N2 (M2). Plates were welded under EMILI using the M1 gas with constant welding parameters. The modified microstructural evolution in the high temperature heat affected zone and at the fusion zone induced by application of EMILI during welding is associated with the increase of resistance to localised corrosion of the welded joints. Joints made by GMAW using the shielding gas M2 without the application of magnetic field presented high resistance to general corrosion but high susceptibility to undergo localised attack.

  1. Fatigue Strength and Related Characteristics of Aircraft Joints I : Comparison of Spot-Weld and Rivet Patterns in 24s-t Alclad and 75s-t Alclad

    NASA Technical Reports Server (NTRS)

    Russell, H W; Jackson, L R; Grover, H J; Beaver, W W

    1944-01-01

    Report contains detailed results of a number of fatigue tests on spot-welded joints in aluminum alloys. The tests described include: (1) fatigue tests on spot-welded lap joints in sheets of unequal thickness of alclad 24s-t. These tests indicate that the fatigue strength of a spot-welded joint in sheets of two different gages is slightly higher than that of a similar joint in two sheets of the thinner gage but definitely lower than that of a similar joint in two sheets of the thicker gage. (2) Fatigue tests on spot-welded alclad 75s-t spot-welded lap-joint specimens of alclad 75s-t were not any stronger in fatigue than similar specimens of alclad 24s-t. (3) Fatigue tests on lap-joint specimens spot -welded after various surface preparations--these included ac welding wire-brushed surfaces, dc welding wire-brushed surfaces, and dc welding chemically cleaned surfaces. While the ac welds were strongest statically, the dc welds on wire-brushed surfaces were strongest in fatigue. Specimens prepared in this way were very nearly as strong as the best riveted specimens tested for comparison. (4) Fatigue tests on specimens spot-welded with varying voltage so as to include a wide range of static spot-weld strengths. The fatigue strengths were in the same order as the static strengths but showed less range. (author)

  2. 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.…

  3. 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…

  4. JFIT: a framework to obtain combined experimental results through joint fits

    E-print Network

    Eli Ben-Haim; René Brun; Bertrand Echenard; Thomas E. Latham

    2015-09-18

    A master-worker architecture is presented for obtaining combined experimental results through joint fits of datasets from several experiments, ensuring that correlations are correctly taken into account and resulting in a better determination of nuisance parameters. The JFIT framework allows such joint fits to be performed keeping the data separated, in its original format, and using independent fitting environments. We present a C++ implementation of such a framework based on the ROOT package, and demonstrate its functionalities with concrete examples.

  5. Microstructure and Mechanical Properties of Friction Stir Spot-Welded IF/DP Dissimilar Steel Joints

    NASA Astrophysics Data System (ADS)

    Sarkar, Rajarshi; Sengupta, Shiladitya; Pal, Tapan Kumar; Shome, Mahadev

    2015-11-01

    Interstitial-free (IF) and dual-phase (DP) steel sheets of 1-mm thickness were joined by friction stir spot welding with a convex shoulder tool. Two different combinations were used; one with IF as top sheet (IF/DP) and another with DP as top sheet (DP/IF). Material intermixing between the overlapping sheets takes place within the stirred zone. The truncated sheet interface curls upward into the top sheet, more so in case of IF/DP, due to lower resistance offered by the top (IF) sheet to the upward migrating bottom (DP) sheet material. Material from the IF steel contains ferrite phases, while that from the DP steel contains acicular ferrite and lath martensite. Under quasi-static loading, the crack passes along the dissimilar interface and into the top sheet thickness, resulting in pull-out failure. Under cyclic loading, the failure is brought about by the initiation of kinked fatigue cracks and their subsequent propagation through the top and bottom sheet thickness. The dominant fatigue crack moves through the reduced top sheet thickness. The mechanical performance of DP/IF is better than IF/DP owing to higher strength of the stirred zone. The mechanical performances of the dissimilar joints are intermediate to that of the similar material joints.

  6. Robotic welding

    SciTech Connect

    Lane, J.D.

    1986-01-01

    The purpose of this book is to provide the reader with the latest up-to-date information on robotic welding, associated components, and systems. This information has been compiled on automatic robotic arc welding systems which are presently employed and being worked on for future applications along with various adaptive control techniques and welt joint seam,-tracking systems being investigated for continuous robotic arc welding. In addition to arc welding, robotic resistance welding and laser welding systems and applications are presented with the idea of illustrating detailed knowledge on the most established and the newest robotic integrated systems, respectively.

  7. The Anti-fatigue Mechanisms on Alterations of Structures and Performances of Alloy Welded Joints with Ultrasonic Impact Treatment

    NASA Astrophysics Data System (ADS)

    Li, Z. M.; Zhu, Y. L.; Du, X. K.

    The specimens of aluminum alloy welded joint were prepared by gas tungsten arc welding using 2A12 sheets and ER5356 welding wires. Some specimens were full coverage strengthened by ultrasonic impact treatment and the others were not strengthened. The surface layer microstructures of the ultrasonic impact treated and untreated specimens were investigated by optical microscopy and transmission electron microscopy. The surface layer hardness and residual stress distributions along the thickness direction were measured by micro-hardness tester and X-ray diffraction method. The results showed that a grain refinement layer which depth extended up to about 150?200 ?m was produced by ultrasonic impact treatment. The average hardness value of the treated specimens was up to 110 HV, increasing by 45% compared with 76 HV of the untreated specimen. A residual compressive stress layer was also produced by ultrasonic impact treatment, and the depth was close to 900 ?m. The maximum residual compressive stress was -285 MPa. At the same time, the anti-fatigue mechanisms on grain refinement, work hardening and residual compressive stress of aluminum alloy welded joint with ultrasonic impact treatment were also discussed.

  8. Effect of the Number of Welding Repairs with GTAW on the Mechanical Behavior of AA7020 Aluminum Alloy Welded Joints

    NASA Astrophysics Data System (ADS)

    Maya-Johnson, Santiago; Santa, Juan Felipe; Mejía, Oscar L.; Aristizábal, Santiago; Ospina, Sebastian; Cortés, Paula Andrea; Giraldo, Jorge Enrique

    2015-10-01

    In this work, two different tests were done to establish the effect of heating cycles by welding in an AA7020-T6 aluminum alloy welded with ER5087 and ER5356 electrodes. During 10 months, welds were done to simulate in the laboratory several welding repairs (up to six repairs). Tensile and hardness measurements were done to evaluate the evolution of the properties against time. It was found that a single pass is enough to generate a heat-affected zone (HAZ) of 30 mm, and after four repairs the width of the HAZ exceeds 210 mm. In the HAZ, two regions were observed: the dissolution zone, which recovers a percentage of hardness by natural aging, and the over-aging zone, showing no increase in hardness. The results indicate that there is a maximum number of welding repairs that can be performed in a heat-treatable aluminum superstructure before it fails on the HAZ of the base material, since the tensile strength is reduced around 40 pct compared to the base metal.

  9. Development of Residual Stress Improvement for Nuclear Pressure Vessel Instrumentation Nozzle Weld Joint (P-43+P-8) by Means of Induction Heating

    SciTech Connect

    Takuro Terajima; Takashi Hirano

    2006-07-01

    As a counter measurement of intergranular stress corrosion cracking (IGSCC) in boiling water reactors, the induction heating stress improvement (IHSI) has been developed as a method to improve the stress factor, especially residual stresses in affected areas of pipe joint welds. In this method, a pipe is heated from the outside by an induction coil and cooled from the inside with water simultaneously. By thermal stresses to produce a temperature differential between the inner and outer pipe surfaces, the residual stress inside the pipe is improved compression. IHSI had been applied to weld joints of austenitic stainless steel pipes (P-8+P-8). However IHSI had not been applied to weld joints of nickel-chromium-iron alloy (P-43) and austenitic stainless steel (P-8). This weld joint (P-43+P-8) is used for instrumentation nozzles in nuclear power plants' reactor pressure vessels. Therefore for the purpose of applying IHSI to this one, we studied the following: Investigation of IHSI conditions (Essential Variables); Residual stresses after IHSI; Mechanical properties after IHSI. This paper explains that IHSI is sufficiently effective in improvement of the residual stresses for this weld joint (P-43+P-8), and that IHSI does not cause negative effects by results of mechanical properties, and IHSI is verified concerning applying it to this kind of weld joint. (authors)

  10. Automated Welding System

    NASA Technical Reports Server (NTRS)

    Bayless, E. O.; Lawless, K. G.; Kurgan, C.; Nunes, A. C.; Graham, B. F.; Hoffman, D.; Jones, C. S.; Shepard, R.

    1993-01-01

    Fully automated variable-polarity plasma arc VPPA welding system developed at Marshall Space Flight Center. System eliminates defects caused by human error. Integrates many sensors with mathematical model of the weld and computer-controlled welding equipment. Sensors provide real-time information on geometry of weld bead, location of weld joint, and wire-feed entry. Mathematical model relates geometry of weld to critical parameters of welding process.

  11. On the Use of Infrared Thermography for Analysis of Fatigue Damage in Ti6Al4V-Welded Joints

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Gao, Xiao-Long; Zhang, Lin-Jie; Zhang, Jian-Xun

    2014-08-01

    The present work is aimed at comparatively studying fatigue damage evolution of a pulsed Nd:YAG laser beam-welded (LBW) joint and the base metal (BM) of Ti6Al4V alloy subjected to cyclic loading. To reveal crack nucleation and propagation during the fatigue process, in situ fatigue was generated using infrared measurement methods. The results indicate that the rate of damage accumulated in the LBW joint was higher than in the BM specimens during a fatigue test, which decreased the fatigue life of the LBW joint. This observation is attributable to the LBW joint fusion zone microstructure, which has a higher void nucleation and growth rate compared with the BM microstructure.

  12. Effect of Interfacial Microstructure Evolution on Mechanical Properties and Fracture Behavior of Friction Stir-Welded Al-Cu Joints

    NASA Astrophysics Data System (ADS)

    Xue, P.; Xiao, B. L.; Ma, Z. Y.

    2015-07-01

    The interfacial microstructure evolution of Al-Cu joints during friction stir welding and post-welding annealing and its influence on the tensile strength and the fracture behavior were investigated in detail. An obvious interface including three sub-layers of ?-Al, Al2Cu, and Al4Cu9 intermetallic compound (IMC) layers is generated in the as-FSW joint. With the development of annealing process, the ?-Al layer disappeared and a new IMC layer of AlCu formed between initial two IMC layers of Al2Cu and Al4Cu9. The growth rate of IMC layers was diffusion controlled before the formation of Kirkendall voids, with activation energy of 117 kJ/mol. When the total thickness of IMC layers was less than the critical value of 2.5 ?m, the FSW joints fractured at the heat-affected zone of Al side with a high ultimate tensile strength (UTS) of ~100 MPa. When the thickness of IMC layers exceeded 2.5 ?m, the joints fractured at the interface. For relatively thin IMC layer, the joints exhibited a slightly decreased UTS of ~90 MPa and an inter-granular fracture mode with crack propagating mainly between the Al2Cu and AlCu IMC layers. However, when the IMC layer was very thick, crack propagated in the whole IMC layers and the fracture exhibited trans-granular mode with a greatly decreased UTS of 50-60 MPa.

  13. 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.

  14. 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.

  15. Joints in fiber-reinforced aluminum alloys

    NASA Technical Reports Server (NTRS)

    Gerber, K.; Vanrensen, E.

    1988-01-01

    Problems of joining involving structural components made of aluminum alloys with boron-fiber reinforcements are discussed, giving attention to a diffusion-welding process. The tension characteristics and weight factors in the case of various types of welded joints are considered. Diffusion-welding equipment used in the experimental investigation is described. The strength characteristics obtained in various cases of weld and component design are examined, taking into account static and dynamic stresses.

  16. Microstructural characterization and hardness properties of electric resistance welding titanium joints for dental applications.

    PubMed

    Ceschini, Lorella; Boromei, Iuri; Morri, Alessandro; Nardi, Diego; Sighinolfi, Gianluca; Degidi, Marco

    2015-06-01

    The electric resistance welding procedure is used to join a titanium bar with specific implant abutments in order to produce a framework directly in the oral cavity of the patient. This investigation studied the effects of the welding process on microstructure and hardness properties of commercially pure (CP2 and CP4) Ti components. Different welding powers and cooling procedures were applied to bars and abutments, normally used to produce the framework, in order to simulate the clinical intraoral welding procedure. The analyses highlighted that the joining process did not induce appreciable changes in the geometry of the abutments. However, because of unavoidable microstructural modifications in the welded zones, the hardness decreased to values lower than those of the unwelded CP2 and CP4 Ti grades, irrespective of the welding environments and parameters. PMID:26045042

  17. A Nondestructive Evaluation Method: Measuring the Fixed Strength of Spot-Welded Joint Points by Surface Electrical Resistivity.

    PubMed

    Shimamoto, Akira; Yamashita, Keitaro; Inoue, Hirofumi; Yang, Sung-Mo; Iwata, Masahiro; Ike, Natsuko

    2013-04-01

    Destructive tests are generally applied to evaluate the fixed strength of spot-welding nuggets of zinc-plated steel (which is a widely used primary structural material for automobiles). These destructive tests, however, are expensive and time-consuming. This paper proposes a nondestructive method for evaluating the fixed strength of the welded joints using surface electrical resistance. A direct current nugget-tester and probes have been developed by the authors for this purpose. The proposed nondestructive method uses the relative decrease in surface electrical resistance, ?. The proposed method also considers the effect of the corona bond. The nugget diameter is estimated by two factors: R Quota, which is calculated from variation of resistance, and a constant that represents the area of the corona bond. Since the maximum tensile strength is correlated with the nugget diameter, it can be inferred from the estimated nugget diameter. When appropriate measuring conditions for the surface electrical resistance are chosen, the proposed method can effectively evaluate the fixed strength of the spot-welded joints even if the steel sheet is zinc-plated. PMID:24891747

  18. Influence of Accelerated Cooling Condition on Welding Thermal Cycle, Residual Stress, and Deformation in SM490A Steel ESW Joint

    NASA Astrophysics Data System (ADS)

    Deng, Dean; Sun, Jiamin; Dai, Deping; Jiang, Xiaohua

    2015-09-01

    Electro-slag welding (ESW) has been widely used to join the box column because of high productivity. The heat input of ESW is far larger than those of other fusion welding processes, so ESW usually results in a long holding time over certain elevated temperature (? t H time), a long cooling time from 800 to 500 °C (? t 8/5 time), and a wide heat-affected zone (HAZ). It can be foreseen that the mechanical properties especially fracture toughness of the fusion zone and HAZ will be inferior to those of base metal. As a fundamental research, a computational approach based on MSC.Marc code was developed to simulate the thermo-mechanical behaviors in a typical SM490A steel ESW joint under different cooling conditions. Meanwhile, the thermal cycles computed by numerical model were compared with the experimental measurements. Moreover, the influence of accelerated cooling methods on welding residual stress and deformation was examined numerically. Simulation results show that accelerated cooling methods not only can largely shorten ? t H time as well as ? t 8/5 time and reduce the size of HAZ, but also can affect the residual stress distribution and deformation. It is believed that the accelerated cooling methods proposed by this study potentially improve the mechanical properties of ESW joint.

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

    NASA Astrophysics Data System (ADS)

    Liu, Liming; Qi, Xiaodong; Zhang, Zhaodong

    2012-06-01

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

  20. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1972-01-01

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

  2. Residual Stress Distribution of 600MPa Grade High Tensile Strength Steel Pipe Using Welding fe Simulation

    NASA Astrophysics Data System (ADS)

    Chang, Kyong-Ho; Jang, Gab-Chul

    2011-06-01

    This paper aims to determine the residual stress distribution of 600MPa grade high tensile strength steel pipe (STKT590) by girth welding. Welding FE simulation is achieved considering temperature dependent physical constants and mechanical properties, obtained by the temperature elevated tensile tests. Comparative analyses clarify the characteristics of residual stress profile near weld joint of STKT590 pipe.

  3. Weld penetration and defect control. Final report

    SciTech Connect

    Chin, B.A.

    1992-05-15

    Highly engineered designs increasingly require the use of improved materials and sophisticated manufacturing techniques. To obtain optimal performance from these engineered products, improved weld properties and joint reliability are a necessarily. This requirement for improved weld performance and reliability has led to the development of high-performance welding systems in which pre-programmed parameters are specified before any welding takes place. These automated systems however lack the ability to compensate for perturbations which arise during the welding process. Hence the need for systems which monitor and control the in-process status of the welding process. This report discusses work carried out on weld penetration indicators and the feasibility of using these indicators for on-line penetration control.

  4. Effects of Heat Input on Microstructure and Mechanical Properties of Laser-Welded Mg-Rare Earth Alloy

    NASA Astrophysics Data System (ADS)

    Dai, Jun; Huang, Jian; Li, Zhuguo; Dong, Jie; Wu, Yixiong

    2013-01-01

    The effects of heat input on the quality of laser-welded Mg-rare earth alloy NZ30K were studied. Using a 15-kW high-power CO2 laser, the microstructure and mechanical properties of welded joints under different heat inputs had been analyzed and tested. It is found that the welding heat input plays an important role in laser welding of NZ30K. Good welded joint without macroscopic defects can be obtained using the proper heat input. With the increasing heat input, welding penetration gets deeper, the width of the heat-affected-zone becomes larger, and the distribution of precipitates changes concentration. Tensile tests display that the ultimate tensile strength (UTS) of the welded joint tends to increase at first with the increasing heat input. After the welded joint gets full penetration, the UTS remains almost the same, although the heat input is increased.

  5. Imaging The Leading Edge Of A Weld

    NASA Technical Reports Server (NTRS)

    Mcgee, William F.; Rybicki, Daniel J.

    1994-01-01

    Proposed optical system integrated into plasma arc welding torch provides image of leading edge of weld pool and welding-arc-initiation point. Welding torch aligned better with joint. System includes coherent bundle of optical fibers and transparent cup.

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

    NASA Astrophysics Data System (ADS)

    Vasantharaja, P.; Vasudevan, M.

    2012-02-01

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

  7. Mechanical Characteristics of 9% Ni Steel Welded Joint for Lng Storage Tank at Cryogenic

    NASA Astrophysics Data System (ADS)

    Yoon, Yong-Keun; Kim, Jae-Hoon; Shim, Kyu-Taek; Kim, Young-Kyun

    To confirm the safety performance of LNG storage tank, the change in fatigue crack growth rate and fracture toughness within X-grooved weld heat-affected zone (HAZ) of newly developed 9% Ni steel, which was SMAW welded, was investigated. These materials were produced by QT (quenching, tempering) heat treatment. The weld metal specimens were prepared by taking the same weld procedure applied in actual inner shell of LNG storage tank. All tests were performed in the temperature ranging from R.T. and -162°C. The fatigue crack growth behavior was carried out using CT specimen. Investigation has been carried out to study the influence of temperature and weld effect on fatigue crack growth behavior. Also, Fracture surfaces after tests were observe by scanning electron microscope (SEM).

  8. Fracture mechanics for weld acceptance

    NASA Technical Reports Server (NTRS)

    Bolstad, C. A.; Loechel, L. W.

    1976-01-01

    Criteria include specifications for allowable cracklike defect lengths, undercut, underfill, suckback, mismatch, peaking in butt welds, root penetration, weld beam dimensions, lap joint dimensions, and acceptable defect sizes and densities for double and single fillet welds.

  9. Cleaning Internal-Weld Splatter

    NASA Technical Reports Server (NTRS)

    Snodgrass, R.

    1982-01-01

    Splattered metal produced by welding can be easily removed from inaccessible areas by method resembling ball milling. Hard steel balls are vibrated inside welded unit so that they "scrub away" excess metal on interior side of weld joint.

  10. Heat treatment of welded joints of steel 0.3?-1Cr-1Si produced by high-power fiber lasers

    NASA Astrophysics Data System (ADS)

    Kuryntsev, S. V.; Gilmutdinov, A. Kh.

    2015-11-01

    The effect of heat treatment on the welded joints of steel grade 0.3?-1Cr-1Si produced by 30 kW power fiber lasers was investigated in the paper. The speed of the welding process was 20 mm/s. Heat treatment was carried out on two levels, quenching with subsequent middle tempering and high tempering. The samples were examined before and after heat treatment, macro- and microstructure were studied using SEM, UTS, three points bent test, microhardness. The effect of heat treatment was significant: it allowed reduction of the weld hardness of considerably and enhancement of its ductility.

  11. Effects of CaF2 Coating on the Microstructures and Mechanical Properties of Tungsten Inert Gas Welded AZ31 Magnesium Alloy Joints

    NASA Astrophysics Data System (ADS)

    Shen, Jun; Wang, Linzhi; Peng, Dong; Wang, Dan

    2012-11-01

    The effects of CaF2 coating on the macromorphologies of the welded seams were studied by morphological analysis. Microstructures and mechanical properties of butt joints welded with different amounts of CaF2 coatings were investigated using optical microscopy and tensile tests. The welding defects formed in the welded seams and the fracture surfaces were analyzed by scanning electron microscopy. An increase in the amount of CaF2 coating deteriorated the appearances of the welded seams but it improved the weld penetration depth and the depth/width ( D/ W) ratio of the tungsten inert gas (TIG) welded joints. The ?-Mg grains and Mg17(Al,Zn)12 intermetallic compound (IMC) were coarser in the case of a higher amount of CaF2 coating. The increase in the amount of CaF2 coating reduced the porosities and total length of solidification cracks in the fusion zone (FZ). The ultimate tensile strength (UTS) value and elongation increased at first and then decreased sharply.

  12. 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.

  13. Determination of the uncertainty of microhardness in the evaluation of hardfacing obtained by welding

    NASA Astrophysics Data System (ADS)

    Cruz-Crespo, A.; Leal, J. E. S.; Piratelli-Filho, A.; Mendez, T. O.; Arencibia, R. V.

    2015-10-01

    The present work evaluates the microhardness measurement uncertainty using a Vickers indenter in the characterization of hard deposits, obtained with experimental electrode for hardfacing of cutting knives in sugar mills. The following stages were proposed: i) obtainment of the deposit with experimental electrode, ii) obtainment of the samples, iii) chemical characterization, iv) metallographic analysis, v) microhardness measurement and vi) uncertainty measurement assessment. It was observed that the obtained deposit presents chrome carbides and eutectic matrix composed of austenite and carbides. The expanded uncertainty associated to the microhardness measurement is highly influenced by the low repeatability of the obtained microhardness values.

  14. Effects of porosity on weld-joint tensile strength of aluminum alloys

    NASA Technical Reports Server (NTRS)

    Lovoy, C. V.

    1974-01-01

    Tensile properties in defect-free weldments of aluminum alloys 2014-T6 and 2219-T87 (sheet and plate) are shown to be related to the level or concentration of induced simulated porosity. The scatter diagram shows that the ultimate tensile strength of the weldments displays the most pronounced linear relationship with the level of porosity. The relationships between yield strength or elongation and porosity are either trivial or inconsequential in the lower and intermediate levels of porosity content. In highly concentrated levels of porosity, both yield strength and elongation values decrease markedly. Correlation coefficients were obtained by simple straight line regression analysis between the variables of ultimate tensile strength and pore level. The coefficients were greater, indicating a better correlation, using a pore area accumulation concept or pore volume accumulation than the accumulation of the pore diameters. These relationships provide a useful tool for assessing the existing aerospace radiographic acceptance standards with respect to permissible porosity. In addition, these relationships, in combination with known design load requirements, will serve as an engineering guideline in determining when a weld repair is necessary based on accumulative pore level as detected by radiographic techniques.

  15. Experimental study of cyclic creep and high-cycle fatigue of welded joints of St3 steel by the DIC technique

    NASA Astrophysics Data System (ADS)

    Kibitkin, Vladimir V.; Solodushkin, Andrey I.; Pleshanov, Vasily S.

    2015-10-01

    In the paper the mechanisms of plastic deformation and fracture of welded joints of steel St3 were investigated at high-cycle fatigue and cyclic creep by the digital image correlation (DIC) technique. The evolution of strain rate is studied for the following regions: base metal, HAZ, and fusion zone. This strain rate evolution can be considered as a mechanical response of material. Three stages of deformation evolution are shown: deformation hardening (I), fatigue crack initiation (II), and the last stage is related to main crack (III). Two criteria are offered to evaluate the current mechanical state of welded joints.

  16. Weld joint concepts for on-orbit repair of Space Station Freedom fluid system tube assemblies

    NASA Astrophysics Data System (ADS)

    Jolly, Steven D.

    1993-11-01

    Because Space Station Freedom (SSF) is an independent satellite, not depending upon another spacecraft for power, attitude control, or thermal regulation, it has a variety of tubular, fluid-carrying assemblies on-board. The systems of interest in this analysis provide breathing air (oxygen and nitrogen), a working fluid (two-phase anhydrous ammonia) for thermal control, and a monopropellant (hydrazine) for station reboost. The tube assemblies run both internally and externally with respect to the habitats. They are found in up to 50 ft. continuous lengths constructed of mostly AISI 316L stainless steel tubing, but also including some Inconel 625 nickel-iron and Monel 400 nickel-copper alloy tubing. The outer diameters (OD) of the tubes range from 0.25-1.25 inches, and the wall thickness between 0.028-.095 inches. The system operational pressures range from 377 psi (for the thermal control system) to 3400 psi (for the high pressure oxygen and nitrogen supply lines in the ECLSS). SSF is designed for a fifteen to thirty year mission. It is likely that the tubular assemblies (TA's) will sustain damage or fail during this lifetime such that they require repair or replacement. The nature of the damage will be combinations of punctures, chips, scratches, and creases and may be cosmetic or actually leaking. The causes of these hypothetical problems are postulated to be: (1) faulty or fatigued fluid joints--both QD's and butt-welds; (2) micro-meteoroid impacts; (3) collison with another man-made object; and (4) over-pressure strain or burst (system origin). While the current NASA baseline may be to temporarily patch the lines by clamping metal c-sections over the defect, and then perform high pressure injection of a sealing compound, it is clear that permanent repair of the line(s) is necessary. This permanent repair could be to replace the entire TA in the segment, or perhaps the segment itself, both alternatives being extremely expensive and risky. The former would likely require extensive EVA to release TA clamps and pose great risk to other engineering subsystems, and the latter would require major de-servicing of the Station.

  17. Weld joint concepts for on-orbit repair of Space Station Freedom fluid system tube assemblies

    NASA Technical Reports Server (NTRS)

    Jolly, Steven D.

    1993-01-01

    Because Space Station Freedom (SSF) is an independent satellite, not depending upon another spacecraft for power, attitude control, or thermal regulation, it has a variety of tubular, fluid-carrying assemblies on-board. The systems of interest in this analysis provide breathing air (oxygen and nitrogen), a working fluid (two-phase anhydrous ammonia) for thermal control, and a monopropellant (hydrazine) for station reboost. The tube assemblies run both internally and externally with respect to the habitats. They are found in up to 50 ft. continuous lengths constructed of mostly AISI 316L stainless steel tubing, but also including some Inconel 625 nickel-iron and Monel 400 nickel-copper alloy tubing. The outer diameters (OD) of the tubes range from 0.25-1.25 inches, and the wall thickness between 0.028-.095 inches. The system operational pressures range from 377 psi (for the thermal control system) to 3400 psi (for the high pressure oxygen and nitrogen supply lines in the ECLSS). SSF is designed for a fifteen to thirty year mission. It is likely that the tubular assemblies (TA's) will sustain damage or fail during this lifetime such that they require repair or replacement. The nature of the damage will be combinations of punctures, chips, scratches, and creases and may be cosmetic or actually leaking. The causes of these hypothetical problems are postulated to be: (1) faulty or fatigued fluid joints--both QD's and butt-welds; (2) micro-meteoroid impacts; (3) collison with another man-made object; and (4) over-pressure strain or burst (system origin). While the current NASA baseline may be to temporarily patch the lines by clamping metal c-sections over the defect, and then perform high pressure injection of a sealing compound, it is clear that permanent repair of the line(s) is necessary. This permanent repair could be to replace the entire TA in the segment, or perhaps the segment itself, both alternatives being extremely expensive and risky. The former would likely require extensive EVA to release TA clamps and pose great risk to other engineering subsystems, and the latter would require major de-servicing of the Station.

  18. Underwater plasma-MIG arc welding: Shielding technique and pressure reduction by a centrifugal pump

    SciTech Connect

    Creutz, M.; Mewes, D.; Bartzsch, J.; Draugelates, U.

    1995-12-31

    In comparison to hyperbaric underwater welding in diving chambers, wet welding techniques promise higher flexibility and lower costs. One technique for creating a local dry and pressure reduced welding zone is the use of a centrifugal pump. Results of experimental investigations in combination with a plasma-MIG arc welding system are presented in this paper. Special importance is attached to the local pressure reduction in view of the fact that low pressure, i.e. a high pressure difference between surrounding water and dry welding area, is a good condition for welding but is difficult to be obtained with other shielding systems than pressure chambers. Plasma-MIG welding has been done under water with a good result on the weld quality. Values of the hardness of the joint and the appearance of the weld structure are nearly comparable to atmospheric welds.

  19. Sensor fusion using neural network in the robotic welding

    SciTech Connect

    Ohshima, Kenji; Yabe, Masaaki; Akita, Kazuya; Kugai, Katsuya; Yamane, Satoshi; Kubota, Takefumi

    1995-12-31

    It is important to realize intelligent welding robots to obtain a good quality of the welding results. For this purpose, it is required to detect the torch height, the torch attitude, the deviation from the center of the gap. In order to simultaneously detect those, the authors propose the sensor fusion by using the neural network, i.e., the information concerning the welding torch is detected by using both the welding current and the welding voltage. First, the authors deal with the welding phenomena as the melting phenomena in the electrode wire of the MIG welding and the CO{sub 2} short circuiting welding. Next, the training data of the neutral networks are made from the numerical simulations. The neuro arc sensor is trained so as to get the desired performance of the sensor. By using it, the seam tracking is carried out in the T-joint.

  20. Radiographic detection of defects in friction stir welding on aluminum alloy AMg5M

    SciTech Connect

    Tarasov, Sergei Yu. Kolubaev, Evgeny A.; Rubtsov, Valery E.

    2014-11-14

    In order to reveal weld defects specific to friction stir welding we undertook radiographic inspection of AMg5M aluminum alloy welded joints. Weld defects in the form of voids have been revealed in the weld obtained under the non-optimal rotation and feed rate. Both shape and size of these defects have been confirmed by examining metallographically successive sections prepared in the weld plane as well as in the plane transversal to the tool feed direction. Linear defects have been also found in the sections that are not seen in the radiographic images. Both the preferable localization and origination of the defects have been analyzed.

  1. Infrared Thermography For Welding

    NASA Technical Reports Server (NTRS)

    Gilbert, Jeffrey L.; Lucky, Brian D.; Spiegel, Lyle B.; Hudyma, Russell M.

    1992-01-01

    Infrared imaging and image-data-processing system shows temperatures of joint during welding and provides data from which rates of heating and cooling determined. Information used to control welding parameters to ensure reliable joints, in materials which microstructures and associated metallurgical and mechanical properties depend strongly on rates of heating and cooling. Applicable to variety of processes, including tungsten/inert-gas welding; plasma, laser, and resistance welding; cutting; and brazing.

  2. Study of weld offset in longitudinally welded SSME HPFTP inlet

    NASA Technical Reports Server (NTRS)

    Min, J. B.; Spanyer, K. S.; Brunair, R. M.

    1992-01-01

    Welded joints are an essential part of rocket engine structures such as the Space Shuttle Main Engine (SSME) turbopumps. Defects produced in the welding process can be detrimental to weld performance. Recently, review of the SSME high pressure fuel turbopump (HPFTP) titanium inlet X-rays revealed several weld discrepancies such as penetrameter density issues, film processing discrepancies, weld width discrepancies, porosity, lack of fusion, and weld offsets. Currently, the sensitivity of welded structures to defects is of concern. From a fatigue standpoint, weld offset may have a serious effect since local yielding, in general, aggravates cyclic stress effects. Therefore, the weld offset issue is considered in this report. Using the FEM and beamlike plate approximations, parametric studies were conducted to determine the influence of weld offsets and a variation of weld widths in longitudinally welded cylindrical structures with equal wall thicknesses on both sides of the joint. Following the study, some conclusions are derived for the weld offsets.

  3. Intelligent Modeling Combining Adaptive Neuro Fuzzy Inference System and Genetic Algorithm for Optimizing Welding Process Parameters

    NASA Astrophysics Data System (ADS)

    Gowtham, K. N.; Vasudevan, M.; Maduraimuthu, V.; Jayakumar, T.

    2011-04-01

    Modified 9Cr-1Mo ferritic steel is used as a structural material for steam generator components of power plants. Generally, tungsten inert gas (TIG) welding is preferred for welding of these steels in which the depth of penetration achievable during autogenous welding is limited. Therefore, activated flux TIG (A-TIG) welding, a novel welding technique, has been developed in-house to increase the depth of penetration. In modified 9Cr-1Mo steel joints produced by the A-TIG welding process, weld bead width, depth of penetration, and heat-affected zone (HAZ) width play an important role in determining the mechanical properties as well as the performance of the weld joints during service. To obtain the desired weld bead geometry and HAZ width, it becomes important to set the welding process parameters. In this work, adaptative neuro fuzzy inference system is used to develop independent models correlating the welding process parameters like current, voltage, and torch speed with weld bead shape parameters like depth of penetration, bead width, and HAZ width. Then a genetic algorithm is employed to determine the optimum A-TIG welding process parameters to obtain the desired weld bead shape parameters and HAZ width.

  4. Improving fatigue performance of rail thermite welds

    NASA Astrophysics Data System (ADS)

    Jezzini-Aouad, M.; Flahaut, P.; Hariri, S.; Winiar, L.

    2010-06-01

    Rail transport development offers economic and ecological interests. Nevertheless, it requires heavy investments in rolling material and infrastructure. To be competitive, this transportation means must rely on safe and reliable infrastructure, which requires optimization of all implemented techniques and structure. Rail thermite (or aluminothermic) welding is widely used within the railway industry for in-track welding during re-rail and defect replacement. The process provides numerous advantages against other welding technology commonly used. Obviously, future demands on train traffic are heavier axle loads, higher train speeds and increased traffic density. Thus, a new enhanced weld should be developed to prevent accidents due to fracture of welds and to lower maintenance costs. In order to improve such assembly process, a detailed metallurgical study coupled to a thermomechanical modelling of the phenomena involved in the thermite welding process is carried out. Obtained data enables us to develop a new improved thermite weld (type A). This joint is made by modifying the routinely specified procedure (type B) used in a railway rail by a standard gap alumino-thermic weld. Joints of type A and B are tested and compared. Based on experimental temperature measurements, a finite element analysis is used to calculate the thermal residual stresses induced. In the vicinity of the weld, the residual stress patterns depend on the thermal conditions during welding as it also shown by litterature [1, 2]. In parallel, X-Ray diffraction has been used to map the residual stress field that is generated in welded rail of types A and B. Their effect on fatigue crack growth in rail welds is studied. An experimental study based on fatigue tests of rails welded by conventional and improved processes adjudicates on the new advances and results will be shown.

  5. Influences of Friction Stir Welding Parameters on Microstructural and Mechanical Properties of AA5456 (AlMg5) at Different Lap Joint Thicknesses

    NASA Astrophysics Data System (ADS)

    Pishevar, M. R.; Mohandesi, J. Aghazadeh; Omidvar, H.; Safarkhanian, M. A.

    2015-10-01

    Friction stir welding is suitable for joining series 5000 alloys because no fusion welding problems arise for the alloys in this process. The present study examined the effects of double-pass welding and tool rotational and travel speeds for the second-pass welding on the mechanical and microstructural properties of friction stir lap welding of AA5456 (AlMg5)-H321 (5 mm thickness) and AA5456 (AlMg5)-O (2.5 mm thickness). The first pass of all specimens was performed at a rotational speed of 650 rpm and a travel speed of 50 mm/min. The second pass was performed at rotational speeds of 250, 450, and 650 rpm and travel speeds of 25, 50, and 75 mm/min. The results showed that the second pass changed the grain sizes in the center of the nugget zone compared with the first pass. It was observed that the size of the hooking defect of the double-pass-welded specimens was higher than that for the single-pass-welded specimen. The size of the hooking defect was found to be a function of the rotational and travel speeds. The optimal joint tensile shear properties were achieved at a rotational speed of 250 rpm and travel a speed of 75 mm/min.

  6. Dual wire welding torch and method

    DOEpatents

    Diez, Fernando Martinez (Peoria, IL); Stump, Kevin S. (Sherman, IL); Ludewig, Howard W. (Groveland, IL); Kilty, Alan L. (Peoria, IL); Robinson, Matthew M. (Peoria, IL); Egland, Keith M. (Peoria, IL)

    2009-04-28

    A welding torch includes a nozzle with a first welding wire guide configured to orient a first welding wire in a first welding wire orientation, and a second welding wire guide configured to orient a second welding wire in a second welding wire orientation that is non-coplanar and divergent with respect to the first welding wire orientation. A method of welding includes moving a welding torch with respect to a workpiece joint to be welded. During moving the welding torch, a first welding wire is fed through a first welding wire guide defining a first welding wire orientation and a second welding wire is fed through a second welding wire guide defining a second welding wire orientation that is divergent and non-coplanar with respect to the first welding wire orientation.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  8. Effects of laser-weld joint opening size on fatigue strength of Ti-6Al-4V structures with several diameters.

    PubMed

    Nuñez-Pantoja, J M C; Vaz, L G; Nóbilo, M A A; Henriques, G E P; Mesquita, M F

    2011-03-01

    This study was conducted to evaluate the fatigue strength of Ti-6Al-4V laser-welded joints with several diameters and joint openings. Sixty dumbbell rods were machined in Ti-6Al-4V alloy with central diameters of 1·5, 2·0 and 3·5 mm. The specimens were sectioned and then welded using two joint openings (0·0 and 0·6 mm). The combination of variables created six groups, which when added to the intact groups made a total of nine groups (n = 10). Laser welding was executed as follows: 360 V per 8 ms (1·5 and 2·0 mm) and 380 V per 9 ms (3·5 mm) with focus and frequency regulated to zero. The joints were finished, polished and submitted to radiographic examination to be analysed visually for the presence of porosity. The specimens were then subjected to a mechanical cyclic test, and the number of cycles until failure was recorded. The fracture surface was examined with a scanning electron microscope (SEM). The Kruskal-Wallis test and Dunn test (? = 0·05) indicated that the number of cycles required for fracture was lower for all specimens with joint openings of 0·6 mm, and for 3·5-mm-diameter specimens with joint openings of 0·0 mm. The Spearman correlation coefficient (? = 0·05) indicated that there was a negative correlation between the number of cycles and the presence of porosity. So, laser welding of Ti-6Al-4V structures with a thin diameter provides the best conditions for the juxtaposition of parts. Radiographic examination allows for the detection of internal voids in titanium joints. PMID:20678101

  9. Residual stress evaluation and fatigue life prediction in the welded joint by x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Yoo, Keun Bong; Hwang, Kwon Tae; Chang, Jung Chel; Kim, Jae Hoon

    2009-07-01

    In the fossil power plant, the reliability of the components which consist of the many welded parts depends on the quality of welding. The residual stress is occurred by the heat flux of high temperature during weld process. This decreases the mechanical properties as the strength of fatigue and fracture. The residual stress of the welded part in the recently constructed power plants has been the cause of a variety of accidents. The objective of this study is measurement of the residual stress and the full width at half maximum intensity (FWHM) by X-ray diffraction method and to estimate the feasibility of this application for fatigue life assessment of the high-temperature pipeline. The materials used for the study is P92 steel for the use of high temperature pipe on super critical condition. The test results were analyzed by the distributed characteristics of residual stresses and FWHM in x-ray diffraction intensity curve. Also, X-ray diffraction tests using specimens simulated low cycle fatigue damage were performed in order to analyze fatigue properties when fatigue damage conditions become various stages. As a result of X-ray diffraction tests for specimens simulated fatigue damages, we conformed that the ratio of the FWHM due to fatigue damage has linear relationship with fatigue life ratio algebraically. From this relationship, it was suggested that direct expectation of the life consumption rate was feasible.

  10. Process modeling and parameter optimization using radial basis function neural network and genetic algorithm for laser welding of dissimilar materials

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    The welded joints of dissimilar materials have been widely used in automotive, ship and space industries. The joint quality is often evaluated by weld seam geometry, microstructures and mechanical properties. To obtain the desired weld seam geometry and improve the quality of welded joints, this paper proposes a process modeling and parameter optimization method to obtain the weld seam with minimum width and desired depth of penetration for laser butt welding of dissimilar materials. During the process, Taguchi experiments are conducted on the laser welding of the low carbon steel (Q235) and stainless steel (SUS301L-HT). The experimental results are used to develop the radial basis function neural network model, and the process parameters are optimized by genetic algorithm. The proposed method is validated by a confirmation experiment. Simultaneously, the microstructures and mechanical properties of the weld seam generated from optimal process parameters are further studied by optical microscopy and tensile strength test. Compared with the unoptimized weld seam, the welding defects are eliminated in the optimized weld seam and the mechanical properties are improved. The results show that the proposed method is effective and reliable for improving the quality of welded joints in practical production.

  11. Process modeling and parameter optimization using radial basis function neural network and genetic algorithm for laser welding of dissimilar materials

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    The welded joints of dissimilar materials have been widely used in automotive, ship and space industries. The joint quality is often evaluated by weld seam geometry, microstructures and mechanical properties. To obtain the desired weld seam geometry and improve the quality of welded joints, this paper proposes a process modeling and parameter optimization method to obtain the weld seam with minimum width and desired depth of penetration for laser butt welding of dissimilar materials. During the process, Taguchi experiments are conducted on the laser welding of the low carbon steel (Q235) and stainless steel (SUS301L-HT). The experimental results are used to develop the radial basis function neural network model, and the process parameters are optimized by genetic algorithm. The proposed method is validated by a confirmation experiment. Simultaneously, the microstructures and mechanical properties of the weld seam generated from optimal process parameters are further studied by optical microscopy and tensile strength test. Compared with the unoptimized weld seam, the welding defects are eliminated in the optimized weld seam and the mechanical properties are improved. The results show that the proposed method is effective and reliable for improving the quality of welded joints in practical production.

  12. Fatigue crack initiation life prediction in high strength structural steel welded joints

    NASA Astrophysics Data System (ADS)

    Tricoteaux, A.; Fardoun, F.; Degallaix, S.; Sauvage, F.

    1995-02-01

    The local approach method is used to calculate the fatigue crack initiation/early crack growth lives (N(i)) in high strength structural steel weldments. Weld-toe geometries, welding residual stresses and HAZ (heat affected zone) cyclic mechanical properties are taken into account in the N(i) estimation procedure. Fatigue crack initiation lives are calculated from either a Basquin type or a Manson-Coffin type equation. The local (HAZ) stress and strain amplitudes and the local mean stress are determined from an analysis based on the Neuber rule and the Molski-Glinka energy approach. The accuracy of the different methods is evaluated and discussed. Finally the previous methods are used with HAZ cyclic mechanical properties estimated from hardness measurements.

  13. Visualization of local electrochemical activity and local nickel ion release on laser-welded NiTi/steel joints using combined alternating current mode and stripping mode SECM.

    PubMed

    Ruhlig, D; Gugel, H; Schulte, A; Theisen, W; Schuhmann, W

    2008-12-01

    Smoothly polished cross-sections of laser-fabricated welds between NiTi shape memory alloy and stainless steel (SS) microwires of approximately the same diameter and, for comparison, between identical stainless steel or NiTi wires have been subjected to local chemical activity and nickel release measurements using scanning electrochemical microscopy (SECM). In the alternating current mode (AC-SECM), the measurements detected clear differences in the local interfacial chemical activity of the passivated weld and the base metals only for the heterogeneous joints of the type NiTi-SS. In this case the local electrochemical acvtivity was lower above the weld material. Subjecting cross-sections of NiTi-SS to stripping mode SECM (SM-SECM), higher Ni(2+) concentrations were measured above the regions of the parental NiTi wire, which correlates well with the results from AC-SECM imaging which showed this region as being less passivated. An energy-dispersive elemental analysis of the specimen in a scanning electron microscope revealed the coexistence of Ti and Cr in the weld mass. Possibly, a joint action of these two metals in terms of protective oxide formation is better for passivation of the weld region than the individual action of one or the other element for passivating the original wires. Better passivation of course led to decreased electrochemical activity of the weld surface. Apparently, AC- and SM-mode SECM imaging were sufficiently sensitive to detect and visualize the impact of the changed surface passivation upon laser welding. PMID:19082072

  14. 3D Polymer Weld Seam Characterization Based on Optical Coherence Tomography for Laser Transmission Welding Applications

    NASA Astrophysics Data System (ADS)

    Schmitt, Robert; Mallmann, Guilherme; Devrient, Martin; Schmidt, Michael

    Laser transmission welding is an established single-stage plastic joining process, which enables hermetically sealed joints under the workpiece surface. The process requires joining partners with proper degrees of transmission and absorption to the processing wavelength. For reaching a stable process an in-process quality assurance is very valuable. Current monitoring systems have a limited usage, as no quantitative information of the weld itself is obtained without its destruction. In medical and pharmaceutical applications a weld with leakage is e.g. unacceptable. The main objective of this paper is the presentation of the optical coherence tomography as a tool for the quality assurance in laser transmission welding. This approach enables the measurement of any residual gap, weld geometry, internal pores and leaks. The presented results show that this technique allows even the characterization of welds using joining partners with thicknesses of 2 mm or with glass fiber reinforcement levels of 30% per weight.

  15. WELDING RESEARCH -S59WELDING JOURNAL

    E-print Network

    DuPont, John N.

    WELDING RESEARCH -S59WELDING JOURNAL ABSTRACT. The fatigue crack propaga- tion behavior of 316L stainless steel gas metal arc welds has been investigated using the K-increasing testing procedure. A series- come closure for all the gas metal arc welds tested. Crack closure measurements obtained through

  16. Quantitative ultrasonic testing of acoustically anisotropic materials with verification on austenitic and dissimilar weld joints

    NASA Astrophysics Data System (ADS)

    Boller, C.; Pudovikov, S.; Bulavinov, A.

    2012-05-01

    Austenitic stainless steel materials are widely used in a variety of industry sectors. In particular, the material is qualified to meet the design criteria of high quality in safety related applications. For example, the primary loop of the most of the nuclear power plants in the world, due to high durability and corrosion resistance, is made of this material. Certain operating conditions may cause a range of changes in the integrity of the component, and therefore require nondestructive testing at reasonable intervals. These in-service inspections are often performed using ultrasonic techniques, in particular when cracking is of specific concern. However, the coarse, dendritic grain structure of the weld material, formed during the welding process, is extreme and unpredictably anisotropic. Such structure is no longer direction-independent to the ultrasonic wave propagation; therefore, the ultrasonic beam deflects and redirects and the wave front becomes distorted. Thus, the use of conventional ultrasonic testing techniques using fixed beam angles is very limited and the application of ultrasonic Phased Array techniques becomes desirable. The "Sampling Phased Array" technique, invented and developed by Fraunhofer IZFP, allows the acquisition of time signals (A-scans) for each individual transducer element of the array along with fast image reconstruction techniques based on synthetic focusing algorithms. The reconstruction considers the sound propagation from each image pixel to the individual sensor element. For anisotropic media, where the sound beam is deflected and the sound path is not known a-priori, a novel phase adjustment technique called "Reverse Phase Matching" is implemented. By taking into account the anisotropy and inhomogeneity of the weld structure, a ray tracing algorithm for modeling the acoustic wave propagation and calculating the sound propagation time is applied. This technique can be utilized for 2D and 3D real time image reconstruction. The "Gradient Constant Descent Method" (GECDM), an iterative algorithm, is implemented, which is essential for examination of inhomogeneous anisotropic media having unknown properties (elastic constants). The Sampling Phased Array technique with Reverse Phase Matching extended by GECDM-technique determines unknown elastic constants and provides reliable and efficient quantitative flaw detection in the austenitic welds. The validation of ray-tracing algorithm and GECDM-method is performed by number of experiments on test specimens with artificial as well as natural material flaws. A mechanized system for ultrasonic testing of stainless steel and dissimilar welds is developed. The system works on both conventional and Sampling Phased Array techniques. The new frontend ultrasonic unit with optical data link allows the 3D visualization of the inspection results in real time.

  17. The variable polarity plasma arc welding process: Characteristics and performance

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Zhu, G. J.

    1991-01-01

    Significant advantages of the Variable Polarity Plasma Arc (VPPA) Welding Process include faster welding, fewer repairs, less joint preparation, reduced weldment distortion, and absence of porosity. The power distribution was analyzed for an argon plasma gas flow constituting the fluid in the VPPA Welding Process. The major heat loss at the torch nozzle is convective heat transfer; in the space between the outlet of the nozzle and the workpiece; radiative heat transfer; and in the keyhole in the workpiece, convective heat transfer. The power absorbed at the workpiece produces the molten puddle that solidifies into the weld bead. Crown and root widths, and crown and root heights of the weld bead are predicted. The basis is provided for an algorithm for automatic control of VPPA welding machine parameters to obtain desired weld bead dimensions.

  18. Friction Stir Spot Welding of DP780 Carbon Steel

    SciTech Connect

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

    2009-09-15

    Friction stir spot welds were made in uncoated and galvannneled DP780 sheets using polycrystalline boron nitride stir tools. The tools were plunged at either a single continuous rate or in two segments consisting of a relatively high rate followed by a slower rate of shorter depth. Welding times ranged from 1-10 s. Increasing tool rotation speed from 800 to 1600 rpm increased strength values. The 2-segment welding procedures also produced higher strength joints. Average lap-shear strengths exceeding 10.3 kN were consistently obtained in 4 s on both the uncoated and the galvannealed DP780. The likelihood of diffusion and mechanical interlocking contributing to bond formation was supported by metallographic examinations. A cost analysis based on spot welding in automobile assembly showed that for friction stir spot welding to be economically competitive with resistance spot welding the cost of stir tools must approach that of resistance spot welding electrode tips.

  19. 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.

  20. Double-Sided Single-Pass Submerged Arc Welding for 2205 Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Luo, Jian; Yuan, Yi; Wang, Xiaoming; Yao, Zongxiang

    2013-09-01

    The duplex stainless steel (DSS), which combines the characteristics of ferritic steel and austenitic steel, is used widely. The submerged arc welding (SAW) method is usually applied to join thick plates of DSS. However, an effective welding procedure is needed in order to obtain ideal DSS welds with an appropriate proportion of ferrite (?) and austenite (?) in the weld zone, particularly in the melted zone and heat-affected zone. This study evaluated the effectiveness of a high efficiency double-sided single-pass (DSSP) SAW joining method for thick DSS plates. The effectiveness of the converse welding procedure, characterizations of weld zone, and mechanical properties of welded joint are analyzed. The results show an increasing appearance and continuous distribution feature of the ? phase in the fusion zone of the leading welded seam. The converse welding procedure promotes the ? phase to precipitate in the fusion zone of leading welded side. The microhardness appears to significantly increase in the center of leading welded side. Ductile fracture mode is observed in the weld zone. A mixture fracture feature appears with a shear lip and tears in the fusion zone near the fusion line. The ductility, plasticity, and microhardness of the joints have a significant relationship with ? phase and heat treatment effect influenced by the converse welding step. An available heat input controlling technology of the DSSP formation method is discussed for SAW of thick DSS plates.

  1. Development of Alloy and Superalloy Large Shafts by Friction Welding Process

    NASA Astrophysics Data System (ADS)

    Jeong, H. S.; Cho, J. R.; Choi, S. K.; Oh, J. S.; Kim, E. N.

    2010-06-01

    The aim of this study is to examine the process parameters of superalloy and alloy steel inertia welding using FE simulation and to evaluate the mechanical properties of a welded joint. FE simulation was carried out to optimize the inertia welding process parameters. Disk of rotor shaft and head of exhaust valve spindle are made by the hot closed die forging. Dissimilar inertia welding for large exhaust valve spindle manufacturing composed of the Nimonic 80 A valve head of 540 mm diameter and the SNCrW valve stem of 115 mm diameter, and for large rotor shaft manufacturing composed of the 310 mm diameter disk and the 140 mm diameter shaft were carried out with optimal process parameter conditions obtained simulation result. Inertia friction welded joint part was joined by inertia friction welder, MTI model 400. Mechanical and metallurgical properties of welded joints were evaluated by using microstructure, tensile, hardness and fatigue tests.

  2. The Mechanical Behavior of Friction-Stir Spot Welded Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Güler, Hande

    2014-09-01

    Aluminum and alloys are widely used in the automotive industry due to the light weight, good formability, and malleability. Spot welding is the most commonly used joining method of these materials, but the high current requirements and the inconsistent quality of the final welds make this process unsuitable. An alternative welding technique, the friction-stir spot welding process, can also be successfully used in joining of aluminum and alloys. In this study, 1-mm-thick AA5754 Al-alloy plates in the H-111 temper conditions were joined by friction-stir spot welding using two different weld parameters such as tool rotational speed and dwell time. Mechanical properties of the joints were obtained with extensive hardness measurements and tensile shear tests. The effect of these parameters on the failure modes of welded joints was also determined.

  3. The Mechanical Behavior of Friction-Stir Spot Welded Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Güler, Hande

    2014-10-01

    Aluminum and alloys are widely used in the automotive industry due to the light weight, good formability, and malleability. Spot welding is the most commonly used joining method of these materials, but the high current requirements and the inconsistent quality of the final welds make this process unsuitable. An alternative welding technique, the friction-stir spot welding process, can also be successfully used in joining of aluminum and alloys. In this study, 1-mm-thick AA5754 Al-alloy plates in the H-111 temper conditions were joined by friction-stir spot welding using two different weld parameters such as tool rotational speed and dwell time. Mechanical properties of the joints were obtained with extensive hardness measurements and tensile shear tests. The effect of these parameters on the failure modes of welded joints was also determined.

  4. 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.

  5. Adaptive welding of fillet welds using a fast seam-tracking sensor in combination with a standard industrial robot

    NASA Astrophysics Data System (ADS)

    Pischetsrieder, Alexandra

    1996-08-01

    In laser welding, problems often arise from the accuracy required by the laser process, particularly where joints have narrow tolerance limits, e.g. with a fillet weld at an overlap joint. In a number of applications seam-tracking sensors can improve this situation. They are able to detect and follow the joint geometry autonomously. In addition to the tolerances, a varying gap between the parts to weld can cause welding flaws. To solve the problems caused by the height of the gap a functionality for adaptive welding can be integrated into the tracking sensor, rendering possible a determined influence on process parameters. Functional dependencies between the height of the gap and the welding parameters are presented in this paper. To further enhance the accuracy of path tracking the dynamic behavior of the system is investigated. With the integration of these dependencies into the tracking sensor, an algorithm for adaptive welding has been obtained, which takes another step towards the raise of profitability of laser installations by a simplified weld seam preparation and an enhanced stability of the welding process.

  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. Capillary flow weld-bonding

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Jones, R. J. (inventors)

    1976-01-01

    The invention of a weld-bonding technique for titanium plates was described. This involves fastening at least two plates of titanium together using spot-welding and applying a bead of adhesive along the edge of the resistance spot-welded joint which upon heating, flows and fills the separation between the joint components.

  8. A study on the control of melting ratio to increase mechanical properties of laser welded joints between AISI 440C and AISI 430F

    NASA Astrophysics Data System (ADS)

    Romoli, L.; Rashed, C. A. A.; Lovicu, G.; Ishak, R.

    2015-05-01

    Laser beam welding of dissimilar AISI 440C and AISI 430F stainless steels was investigated in a circular constrained configuration. The beam incidence angle and the offset of the focusing position respect to the contact point between the two materials were used as main control parameters to vary the melting ratio inside the seam. The objective of the study is twofold: to avoid surface microcracks related to the high percentage of carbon of the martensitic steel and to enhance the shear strength of the weld by making it less brittle. To reach this scope the effects of incidence angle and offset on weld bead geometry and melting ratio were studied by means of metallographic analyses, microstructure and microhardness characterization. As last step, the weld mechanical strength was tested by tensile-shear stress test on the whole seam. Experiments demonstrated that varying incidence angle and offsetting the focal position is a reliable method to modify the melting ratio and maintaining the expected resistance length at the material interface, as well. It was found that increasing the percentage of ferritic steel into the joint has beneficial effects on the weld quality and on the shear resistance. The critical carbon content determining the mechanical properties in the fusion zone can be calculated by taking into account the melting ratio.

  9. Summary of Results of Tests Made by Aluminum Research Laboratories of Spot-welded Joints and Structural Elements

    NASA Technical Reports Server (NTRS)

    HARTMANN E C; Stickley, G W

    1942-01-01

    Available information concerning spot welding as a means of joining aluminum-alloy parts has been summarized and comparisons have been made of the relative merits of spot-welded and riveted aluminum-alloy structural elements. The results indicated that spot welding was as satisfactory as riveting insofar as resistance to static loads is concerned. Spot welds showed slightly lower resistance to impact loads but definitely lower resistance to repeated loads than rivets.

  10. Assessment of the influence of surface finishing and weld joints on the corrosion/oxidation behaviour of stainless steels in lead bismuth eutectic

    NASA Astrophysics Data System (ADS)

    Martín-Muñoz, F. J.; Soler-Crespo, L.; Gómez-Briceño, D.

    2011-09-01

    The objective of this paper is to gain some insight into the influence of the surface finishing in the oxidation/corrosion behaviour of 316L and T91 steels in lead bismuth eutectic (LBE). Specimens of both materials with different surface states were prepared (as-received, grinded, grinded and polished, and electrolitically polished) and oxidation tests were carried out at 775 and 825 K from 100 to 2000 h for two different oxygen concentrations and for H 2/H 2O molar ratios of 3 and 0.03. The general conclusion for these tests is that the effect of surface finishing on the corrosion/protection processes is not significant under the tested conditions. In addition the behaviour of weld joints, T91-T91 Tungsten Inert Gas (TIG) and T91-316L have been also studied under similar conditions. The conclusions are that, whereas T91-T91 welded joint shows the same corrosion properties as the parent materials for the conditions tested, AISI 316L-T91 welded joint, present an important dissolution over seam area that it associated to the electrode 309S used for the fabrication process.

  11. Thermo-mechanical History of a Friction Stir Welded Plate; Influence of the Mechanical Loading on the Residual Stress Distribution

    NASA Astrophysics Data System (ADS)

    Paun, Florin; Azouzi, Alexandre

    2004-06-01

    The Friction Stir Welding is considered to be one of the most promising processing for aeronautics. The obtained welded joints (for the best welding parameters) seem to have better resistance than conventional joining techniques including riveting. To predict the best welding process conditions, current work aims to completely describe the thermo-mechanical history using computer simulation. In this paper, we will present the latest numerical results, thermal and stress-strain fields, obtained for a "virtual" welded plate. This numerical simulation introduces both thermal and mechanical loadings using a step by step advancing coupled method with SAMCEF code. Further works are proposed for the development of a FSW predictive numerical tool.

  12. Modeling of plasma and thermo-fluid transport in hybrid welding

    NASA Astrophysics Data System (ADS)

    Ribic, Brandon D.

    Hybrid welding combines a laser beam and electrical arc in order to join metals within a single pass at welding speeds on the order of 1 m min -1. Neither autonomous laser nor arc welding can achieve the weld geometry obtained from hybrid welding for the same process parameters. Depending upon the process parameters, hybrid weld depth and width can each be on the order of 5 mm. The ability to produce a wide weld bead increases gap tolerance for square joints which can reduce machining costs and joint fitting difficulty. The weld geometry and fast welding speed of hybrid welding make it a good choice for application in ship, pipeline, and aerospace welding. Heat transfer and fluid flow influence weld metal mixing, cooling rates, and weld bead geometry. Cooling rate affects weld microstructure and subsequent weld mechanical properties. Fluid flow and heat transfer in the liquid weld pool are affected by laser and arc energy absorption. The laser and arc generate plasmas which can influence arc and laser energy absorption. Metal vapors introduced from the keyhole, a vapor filled cavity formed near the laser focal point, influence arc plasma light emission and energy absorption. However, hybrid welding plasma properties near the opening of the keyhole are not known nor is the influence of arc power and heat source separation understood. A sound understanding of these processes is important to consistently achieving sound weldments. By varying process parameters during welding, it is possible to better understand their influence on temperature profiles, weld metal mixing, cooling rates, and plasma properties. The current literature has shown that important process parameters for hybrid welding include: arc power, laser power, and heat source separation distance. However, their influence on weld temperatures, fluid flow, cooling rates, and plasma properties are not well understood. Modeling has shown to be a successful means of better understanding the influence of processes parameters on heat transfer, fluid flow, and plasma characteristics for arc and laser welding. However, numerical modeling of laser/GTA hybrid welding is just beginning. Arc and laser welding plasmas have been previously analyzed successfully using optical emission spectroscopy in order to better understand arc and laser plasma properties as a function of plasma radius. Variation of hybrid welding plasma properties with radial distance is not known. Since plasma properties can affect arc and laser energy absorption and weld integrity, a better understanding of the change in hybrid welding plasma properties as a function of plasma radius is important and necessary. Material composition influences welding plasma properties, arc and laser energy absorption, heat transfer, and fluid flow. The presence of surface active elements such as oxygen and sulfur can affect weld pool fluid flow and bead geometry depending upon the significance of heat transfer by convection. Easily vaporized and ionized alloying elements can influence arc plasma characteristics and arc energy absorption. The effects of surface active elements on heat transfer and fluid flow are well understood in the case of arc and conduction mode laser welding. However, the influence of surface active elements on heat transfer and fluid flow during keyhole mode laser welding and laser/arc hybrid welding are not well known. Modeling has been used to successfully analyze the influence of surface active elements during arc and conduction mode laser welding in the past and offers promise in the case of laser/arc hybrid welding. A critical review of the literature revealed several important areas for further research and unanswered questions. (1) The understanding of heat transfer and fluid flow during hybrid welding is still beginning and further research is necessary. (2) Why hybrid welding weld bead width is greater than that of laser or arc welding is not well understood. (3) The influence of arc power and heat source separation distance on cooling rates during hybrid welding are not known. (4) Convect

  13. Optimal welding of beta titanium orthodontic wires.

    PubMed

    Nelson, K R; Burstone, C J; Goldberg, A J

    1987-09-01

    Today the orthodontist is confronted by an array of new orthodontic wire materials that, when applied to appliance design, can vastly increase the flexibility and versatility of therapy. Welded joints, especially for the newer titanium alloy wires, provide a means to extend the useful applications of these materials. The purpose of this study was to determine the optimum settings for electrical resistance welding of various configurations of titanium-molybdenum (TMA) wires. Specimens were of a t-joint configuration and were mechanically tested in torsion to simulate the failure mode most often observed in clinical practice. Variables included wire size, wire orientation, and welding voltage. Results indicated that excellent welds can be obtained with very little loss of strength and ductility in the area of the weld joint. Torsional loads at failure were at least 90% of the unwelded base material. Although a wide range of voltage settings resulted in high-strength welds, typically a narrow range of voltages yielded optimal ductility. PMID:2888304

  14. Effect of long-term aging on microstructure and local behavior in the heat-affected zone of a Ni–Cr–Mo–V steel welded joint

    SciTech Connect

    Zhu, Ming-Liang Wang, De-Qiang; Xuan, Fu-Zhen

    2014-01-15

    Evolution of microstructure, micro-hardness and micro-tensile strength behavior was investigated in the heat-affected zone of a Ni–Cr–Mo–V steel welded joint after the artificial aging at 350 °C for 3000 h. After detailed characterization of microstructures in optical microscopy, scanning electron microscopy and transmission electron microscopy, it is revealed that the change of martensite–bainite constituent promotes more homogeneous microstructure distribution. The aging treatment facilitates redistribution of carbon and chromium elements along the welded joint, and the micro-hardness is increased slightly through the welds due to enrichment of carbon. The types of precipitates in the weldment mainly include M{sub 3}C, MC, M{sub 2}C and M{sub 23}C{sub 6}. The carbides in base metal, weld metal and coarse-grained heat-affected zone are prone to change from ellipsoidal to platelet form whereas more uniform spherical carbides are observed in the fine-grained zone. Precipitation and coarsening of M{sub 23}C{sub 6} near the fusion line, and formation of MC and M{sub 2}C, are responsible for the tensile strength decrease and its smooth distribution in the aged heat-affected zone. This implies that the thermal aging can relieve strength mismatch in the weldments. - Highlights: • Microstructure homogeneity improved in HAZ after long-term aging. • Tensile strength decreased in HAZ due to precipitation and coarsening of M{sub 23}C{sub 6}. • Strength mismatch in NiCrMoV steel welds was relieved after aging at 350 °C × 3000 h.

  15. Residual stress analysis of welded joints by the variational eigenstrain approach

    NASA Astrophysics Data System (ADS)

    Korsunsky, Alexander M.; Regino, Gabriel; Nowell, David

    2005-04-01

    We present the formulation for finding the distribution of eigenstrains, i.e. the sources of residual stress, from a set of measurements of residual elastic strain (e.g. by diffraction), or residual stress, or stress redistribution, or distortion. The variational formulation employed seeks to achieve the best agreement between the model prediction and some measured parameters in the sense of a minimum of a functional given by a sum over the entire set of measurements. The advantage of this approach lies in its flexibility: different sets of measurements and information about different components of the stress-strain state can be incorporated. We demonstrate the power of the technique by analysing experimental data for welds in thin sheet of a nickel superalloy aerospace material. Very good agreement can be achieved between the prediction and the measurement results without the necessity of using iterative solution. In practice complete characterisation of residual stress states is often very difficult, due to limitations of facility access, measurement time or specimen dimensions. Implications of the new technique for experimental analysis are all the more significant, since it allows the reconstruction of the entire stress state from incomplete sets of data.

  16. Prediction of the Grain-Microstructure Evolution Within a Friction Stir Welding (FSW) Joint via the Use of the Monte Carlo Simulation Method

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Ramaswami, S.; Snipes, J. S.; Avuthu, V.; Galgalikar, R.; Zhang, Z.

    2015-09-01

    A thermo-mechanical finite element analysis of the friction stir welding (FSW) process is carried out and the evolution of the material state (e.g., temperature, the extent of plastic deformation, etc.) monitored. Subsequently, the finite-element results are used as input to a Monte-Carlo simulation algorithm in order to predict the evolution of the grain microstructure within different weld zones, during the FSW process and the subsequent cooling of the material within the weld to room temperature. To help delineate different weld zones, (a) temperature and deformation fields during the welding process, and during the subsequent cooling, are monitored; and (b) competition between the grain growth (driven by the reduction in the total grain-boundary surface area) and dynamic-recrystallization grain refinement (driven by the replacement of highly deformed material with an effectively "dislocation-free" material) is simulated. The results obtained clearly revealed that different weld zones form as a result of different outcomes of the competition between the grain growth and grain refinement processes.

  17. Segregation behavior of phosphorus in the heat-affected zone of an A533B/A182 dissimilar weld joint before and after simulated thermal aging

    NASA Astrophysics Data System (ADS)

    Zhai, Ziqing; Miyahara, Yuichi; Abe, Hiroshi; Watanabe, Yutaka

    2014-09-01

    The segregation behavior of phosphorus (P) in the heat-affected zone (HAZ) of an A533B/A182 dissimilar weld joint before and after step cooling was investigated with atom probe tomography. At grain/packet boundaries, the final P segregation level consisted of non-equilibrium segregation that occurred during cooling after welding and post-weld heat treatment (PWHT) and equilibrium segregation that occurred during step cooling. In both processes, higher P coverage was observed in the coarse-grained and intercritically reheated coarse-grained HAZ than in the fine-grained HAZ and base material. The cooling after welding and PWHT seemed to have a pronounced impact on P segregation in the subsequent aging process. In addition, P segregation also occurred at the precipitate/matrix interfaces of cementite, Mo2C and Al-Si rich precipitates. The evolution of P coverage at these two types of sites suggested increasing risks of embrittlement with an increase in aging time.

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

    NASA Astrophysics Data System (ADS)

    Kim, Jin Weon; Lee, Kyoungsoo; Kim, Jong Sung; Byun, Thak Sang

    2009-02-01

    The distributions of mechanical and microstructural properties were investigated for the dissimilar metal weld joints between SA508 Gr.1a ferritic steel and F316 austenitic stainless steel with Alloy 82/182 filler metal using small-size tensile specimens. The material properties varied significantly in different zones while those were relatively uniform within each material. In particular, significant gradient of the mechanical properties were observed near the both heat-affected zones (HAZs) of F316 SS and SA508 Gr.1a. Thus, the yield stress (YS) was under-matched with respect to the both HAZs, although, the YS of the weld metal was over-matched with respect to both base metals. The minimum ductility occurred in the HAZ of SA508 Gr.1a at both test temperatures. The plastic instability stress also varied considerably across 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. The transmission electron micrographs showed that the strengthening in the HAZ of F316 SS was attributed to the strain hardening, induced by a strain mismatch between the weldment and the base metal, which was evidenced by high dislocation density in the HAZ of F316 SS.

  19. 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. The heat and mass transfer and the issues in joining of dissimilar alloys by the hybrid laser/arc welding process (HLAW) were explicitly explained in details. A finite element model was developed to simulate the heat transfer in HLAW of the aluminum alloys. Two double-ellipsoidal heat source models were considered to describe the heat input of the gas metal arc welding and laser welding processes. An experimental procedure was also developed for joining thick advanced high strength steel plates by using the HLAW, by taking into consideration different butt joint configurations. The geometry of the weld groove was optimized according to the requirements of ballistic test, where the length of the softened heat affected zone should be less than 15.9 mm measured from the weld centerline. Since the main issue in HLAW of the AHSS was the formation of the pores, the possible mechanisms of the pores formation and their mitigation methods during the welding process were investigated. Mitigation methods were proposed to reduce the pores inside in the weld area and the influence of each method on the process stability was investigated by an on-line monitoring system of the HLAW process. The groove angle was optimized for the welding process based on the allowed amount of heat input along the TRICLADRTM interface generated by an explosive welding. The weld was fractured in the heat affected zone of the aluminum side in the tensile test. The microharness was shown that the temperature variation caused minor softening in the heat affected zone satisfying the requirement that the width of the softened heat affected zone in the steel side falls within 15.9 mm far away from the weld centerline. The microstructure analysis showed the presence of tempered martensite at the vicinity of the weld area, which it was a cause of softening in the heat affected zone.

  20. Development of the weld-braze joining process

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

    A joining process, designated weld-brazing, was developed which combines resistance spot welding and brazing. Resistance spot welding is used to position and aline the parts, as well as to establish a suitable faying-surface gap for brazing. Fabrication is then completed at elevated temperature by capillary flow of the braze alloy into the joint. The process was used successfully to fabricate Ti-6Al-4V alloy joints by using 3003 aluminum braze alloy and should be applicable to other metal-braze systems. Test results obtained on single-overlap and hat-stiffened panel specimens show that weld-brazed joints were superior in tensile shear, stress rupture, fatigue, and buckling compared with joints fabricated by conventional means. Another attractive feature of the process is that the brazed joint is hermetically sealed by the braze material, which may eliminate many of the sealing problems encountered with riveted or spot welded structures. The relative ease of fabrication associated with the weld-brazing process may make it cost effective over conventional joining techniques.

  1. Weld bonding of titanium with polyimide adhesives

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Sheppard, C. H.; Orell, M. K.

    1975-01-01

    A conductive adhesive primer and a capillary flow adhesive were developed for weld bonding titanium alloy joints. Both formulations contained ingredients considered to be non-carcinogenic. Lap-shear joint test specimens and stringer-stiffened panels were weld bonded using a capillary flow process to apply the adhesive. Static property information was generated for weld bonded joints over the temperature range of 219K (-65 F) to 561K (550 F). The capillary flow process was demonstrated to produce weld bonded joints of equal strength to the weld through weld bonding process developed previously.

  2. Observation of Joining Phenomena in Friction Stage and Improving Friction Welding Method

    NASA Astrophysics Data System (ADS)

    Kimura, Masaaki; Seo, Kenji; Kusaka, Masahiro; Fuji, Akiyoshi

    This report describes the observation result of joining phenomena in the friction stage, and an improvement of the conventional friction welding method with similar materials. The materials used were carbon steels and a brake type (direct drive) friction welding machine was used for joining. As the improving friction welding method, relative speed was instantaneously rendered to zero at the end of each friction time. The wear of both surfaces started at periphery portion (outer surface) of the joint and moved to center portion (center axis). Seizure and joining began at center portion and then extended toward periphery portion. The friction torque reached to initial peak torque when the welded interface was joined completely and upsetting of both base metals started. It was determined that friction welded joints with 100% joint efficiency and good bend ductility could be obtained by using only the friction stage up to initial peak torque and without the need for the forging (upsetting) stage. As a conclusion, friction welded joints made without using the forging stage has the same mechanical properties as those welded by the conventional friction welding process including that stage. The friction welding method without forging stage has the advantages of less burn-off (axial shortening) and less burr.

  3. Method for welding beryllium

    DOEpatents

    Dixon, Raymond D. (Los Alamos, NM); Smith, Frank M. (Espanola, NM); O'Leary, Richard F. (Los Alamos, NM)

    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.

  4. Double-sided fiber laser beam welding process of T-joints for aluminum aircraft fuselage panels: Filler wire melting behavior, process stability, and their effects on porosity defects

    NASA Astrophysics Data System (ADS)

    Tao, Wang; Yang, Zhibin; Chen, Yanbin; Li, Liqun; Jiang, Zhenguo; Zhang, Yunlong

    2013-11-01

    Aluminum alloy T-joints for aircraft fuselage panels were fabricated by double-sided fiber laser beam welding with filler wire, and the influence of the wire feeding posture on the welding process stability was investigated. A CMOS high speed video system was used to observe the wire melting behavior and the weld pool dynamics in real time during the welding process by using a bandpass red laser with an emission wavelength of 808 nm as backlight source to illuminate the welding zone. The weld porosity defects were analyzed by X-ray radiography. The effects of wire feeding posture on the wire melting behavior, process stability, and porosity defects were investigated. The experimental results indicated that three distinct filler material transfer modes were identified under different wire feeding positions: liquid bridge transfer mode, droplet transfer mode, and spreading transfer mode. The liquid bridge transfer mode could guarantee a stable welding process, and result in the lowest porosity. Compared with wire feeding in the leading direction, the process was not stable and porosity increased when wire feeding in the trailing direction. Increased in the wire feeding angle was disadvantage for pores to escape from the weld molten pool, meanwhile, it made the welding process window smaller due to increasing the centering precision requirement for adjusting the filler wire.

  5. Direct welding with arc discharging to joint quart optical fiber to multicomponent glass mold lens (small factor fiber collimator with new push-pull welding method)

    NASA Astrophysics Data System (ADS)

    Koishi, Musubu; Nishizawa, Koichi; Kawai, Shigeru

    2011-03-01

    In this paper, a new direct splicing method called push-pull welding is described. Direct coupling based on direct fusion splicing, which makes an optical fiber joining a multicomponent glass lens, gives not only a high optical performance but also high reliability and easy alignment.

  6. The aluminum spot weld

    SciTech Connect

    Thornton, P.H.; Krause, A.R.; Davies, R.G.

    1996-03-01

    Weld conditions which promote long tip life for aluminum spot welds are not necessarily associated with high weld quality in terms of freedom from defects such as porosity, cracks and expulsion. Schedules which produce good weld nuggets in terms of the peel test and long tip life may not produce a good response in terms of fatigue life. The fatigue life range is optimized by maximizing the weld nugget diameter, i.e., by employing a weld schedule which may lead to expulsion and weld porosity. Weld strength, in both peel and overlap shear configurations, was found to be linearly dependent upon weld diameter. In the peel test, the strength was also dependent upon the base metal thickness, in that for a given thickness, there is a critical diameter for the transition between weld fracture and nugget pull-out. For a given nugget diameter, if pull-out is observed then the strength is greater than if fracture occurs through the weld. In the shear test, the opposite response was observed, the strength for nugget pull-out being less than that for weld shear failure. Weld pull-out was found only for the thinnest base metal thickness tested and the shear load depended only upon the weld diameter over the range of thicknesses tested. Maximum strength in an aluminum spot weld is obtained by maximizing the weld nugget diameter for that thickness of material.

  7. Monitoring Weld Penetration Via Gas Pressure

    NASA Technical Reports Server (NTRS)

    Coby, J. Ben, Jr.; Todd, Douglas M.

    1991-01-01

    Welding monitor uses pressure on back side of weldment to monitor penetration of weld. Sudden drop on pressure chart means weld pool has fully penetrated; sudden rise means pool no longer extends through joint. Devised to ensure full penetration along full lengths of weld joints, when direct observation of back sides by visual inspection, x rays, or fiber optics not possible. Used in initial development of welding parameters or during production as safeguard.

  8. The Marshall Automated Weld System (MAWS)

    NASA Technical Reports Server (NTRS)

    Russell, Carolyn K.; Lawless, Kirby G.; Nunes, A. C.

    1993-01-01

    A fully automated welding system, which can operate totally independent of human intervention, is currently unavailable in the welding industry. Development of the Marshall Automated Weld System (MAWS) has been undertaken to fill this void. The system will enable application of statistical process control practices to assure weld quality prior to post weld nondestructive testing. The Variable Polarity Plasma Arc (VPPA) welding process has been baselined for MAWS because it has eliminated process related defects in the welding of the Space Shuttle External Tank. The few remaining weld defects occurring on the tank can be associated with human error. The system integrates multiple sensors (providing real time information on weld bead geometry, weld joint location, wirefeed entry, and inert gas quality) with a weld model (describing weld geometry in relation to critical parameters) and computer-controlled VPPA weld equipment. This system is designed to provide real-time, closed-loop control of the weld as it is being made.

  9. The Marshall Automated Weld System (MAWS)

    NASA Technical Reports Server (NTRS)

    Russell, Carolyn K.; Lawless, Kirby G.; Nunes, A. C.

    1993-01-01

    A fully automated welding system, which can operate totally independent of human intervention, is currently unavailable in the welding industry. Development of the Marshall Automated Weld System (MAWS) has been undertaken to fill this void. The system will enable application of statistical process control practices to assure weld quality prior to post weld nondestructive testing. The Variable Polarity Plasma Arc (VPPA) welding process has been baselined for MAWS because it has eliminated process related defects in the welding of the Space Shuttle External Tank. The few remaining weld defects occurring on the tank can be associated with human error. The system integrates multiple sensors (providing real time information on weld bead geometry, weld joint location, wirefeed entry, and inert gas quality) with a weld model (describing weld geometry in relation to critical parameters) and computer controlled VPPA weld equipment. This system is designed to provide real-time, closed-loop control of the weld as it is being made.

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

    NASA Technical Reports Server (NTRS)

    Bjorkman, Gerry; Cantrell, Mark; Carter, Robert

    2003-01-01

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

  11. Study on the Formation and Characterization of the Intermetallics in Friction Stir Welding of Aluminum Alloy to Coated Steel Sheet Lap Joint

    NASA Astrophysics Data System (ADS)

    Das, H.; Ghosh, R. N.; Pal, T. K.

    2014-10-01

    Multimaterial fabrication such as joining of steel and aluminum is currently prominent in a variety of industries. Friction stir welding is a novel solid-state welding process that causes good joint strength between steel and aluminum. However, the phenomenon contributing significant strength at the interface is not yet clear. In the present study, the interface of the friction stir lap-welded aluminum and coated steel sheet having joint strength maximum (71.4 pct of steel base metal) and minimum, respectively, under two parameter combinations, i.e., 1000 rpm 50 mm min-1 and 500 rpm 100 mm min-1, was exclusively characterized by X-ray diffraction, transmission electron microscopy (TEM), concentration profile, and elemental mapping by electron-probe microanalysis. A TEM-assisted EDS study identifies the morphologies of large size Al13Fe4 and small size Fe3Al-type intermetallic compounds at the interface. The diffusion-induced intermetallic growth (thickness) measured from a backscattered image and concentration profile agreed well with the numerically calculated one. The growth of these two phases at 1000 rpm 50 mm min-1 is attributed to the slower cooling rate (~3.5 K/s) with higher diffusion time (44 seconds) along the interface in comparison to the same for 500 rpm 100 mm min-1 with faster cooling rate (~10 K/s) and less diffusion time (13.6 seconds). The formation of thermodynamically stable and hard intermetallic phase Al13Fe4 at 1000 rpm and travel speed 50 mm min-1 in amounts higher than 500 rpm and a travel speed of 100 mm min-1 results in better joint strength, i.e., 71.4 pct, of the steel base metal.

  12. Microstructural characterization of weld joints of 9Cr reduced activation ferritic martensitic steel fabricated by different joining methods

    SciTech Connect

    Thomas Paul, V.; Saroja, S.; Albert, S.K.; Jayakumar, T.; Rajendra Kumar, E.

    2014-10-15

    This paper presents a detailed electron microscopy study on the microstructure of various regions of weldment fabricated by three welding methods namely tungsten inert gas welding, electron beam welding and laser beam welding in an indigenously developed 9Cr reduced activation ferritic/martensitic steel. Electron back scatter diffraction studies showed a random micro-texture in all the three welds. Microstructural changes during thermal exposures were studied and corroborated with hardness and optimized conditions for the post weld heat treatment have been identified for this steel. Hollomon–Jaffe parameter has been used to estimate the extent of tempering. The activation energy for the tempering process has been evaluated and found to be corresponding to interstitial diffusion of carbon in ferrite matrix. The type and microchemistry of secondary phases in different regions of the weldment have been identified by analytical transmission electron microscopy. - Highlights: • Comparison of microstructural parameters in TIG, electron beam and laser welds of RAFM steel • EBSD studies to illustrate the absence of preferred orientation and identification of prior austenite grain size using phase identification map • Optimization of PWHT conditions for indigenous RAFM steel • Study of kinetics of tempering and estimation of apparent activation energy of the process.

  13. Joining characteristics of orthodontic wires with laser welding.

    PubMed

    Iijima, Masahiro; Brantley, William A; Yuasa, Toshihiro; Muguruma, Takeshi; Kawashima, Isao; Mizoguchi, Itaru

    2008-01-01

    Laser welding 0.016 x 0.022 in. beta-Ti, Ni-Ti, and Co-Cr-Ni orthodontic wires was investigated by measuring joint tensile strength, measuring laser penetration depth, determining metallurgical phases using micro X-ray diffraction (micro-XRD), and examining microstructures with an scanning electron microscope (SEM). Welding was performed from 150 to 230 V. Mean tensile strength for Ni-Ti groups was significantly lower (p < 0.05) than for most other groups of laser-welded specimens. Although mean tensile strength for beta-Ti and Co-Cr-Ni was significantly lower than for control specimens joined by silver soldering, it was sufficient for clinical use. The beta-Ti orthodontic wire showed deeper penetration depth from laser welding than the Ni-Ti and Co-Cr-Ni orthodontic wires. Micro-XRD patterns of laser-welded beta-Ti and Ni-Ti obtained 2 mm from the boundary were similar to as-received specimens, indicating that original microstructures were maintained. When output voltages of 190 V and higher were used, most peaks from joint areas disappeared or were much weaker, perhaps because of a directional solidification effect, evidenced by SEM observation of fine striations in welded beta-Ti. Laser welding beta-Ti and Co-Cr-Ni wires may be acceptable clinically, since joints had sufficient strength and metallurgical phases in the original wires were not greatly altered. PMID:17514661

  14. Mechanical and structural properties of similar and dissimilar steel joints

    SciTech Connect

    Celik, A.; Alsaran, A.

    1999-11-01

    The mechanical properties of specimens from similar and dissimilar weld joints were examined. A ferritic steel (St37-2) and an austenitic stainless steel (AISI 304) were joined by the gas tungsten arc weld (GTAW) process using an austenitic filler metal. Mechanical and metallographic properties of the specimens were obtained by means of microhardness testing, tensile testing, bending fatigue testing, and light optical and scanning electron microscopy. The highest microhardness values were recorded on the ferritic-austenitic dissimilar weld joint, whereas the highest tensile strength and bending fatigue life were obtained with the austenitic-austenitic joints. Ferritic and pearlitic structures were observed in the microstructure of the ferritic-ferritic joint. The microstructures of austenitic-austenitic and austenitic-ferritic joints showed small recrystallization grains in addition to the typical austenitic and ferritic structures. Scanning electron microscopy was used to observe the fracture surfaces of the specimens and the origins of the fatigue cracks.

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

    NASA Astrophysics Data System (ADS)

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

    2011-01-01

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

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

    SciTech Connect

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

    2011-01-17

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

  17. Enhanced diffusion welding

    NASA Technical Reports Server (NTRS)

    Holko, K. H.; Moore, T. J. (inventors)

    1973-01-01

    Surfaces of unrecrystallized alloys are sanded and polished. This is followed by a two-step welding process by which the strength of the parent metal is retained at the weld joint. The first step forces the surfaces into intimate contact at a temperature where the metal still has good ductility. The second step causes diffusion, recrystallization, and grain growth across the original weld interface.

  18. Improved welding of Rene-41

    NASA Technical Reports Server (NTRS)

    Nunez, S.

    1970-01-01

    Gas-tungsten arc welding with a filler of Rene-41 produces strong welded joints. When Rene-41 is used, resistance to strain-age cracking is greatly increased by post-weld solution annealing in an inert atmosphere. Mechanical properties of Rene-41 and Hastelloy-W are compared.

  19. Weld-bonded titanium structures

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Creedon, J. F. (inventors)

    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.

  20. 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+?2 and B2+?2+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 ?? 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 ? 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.

  1. A Feasiblity Study on Spot Friction Welding of Magnesium Alloy AZ31

    SciTech Connect

    Santella, Michael L; Pan, Dr. Tsung-Yu; Frederick, David Alan; Schwartz, William

    2007-01-01

    Spot friction welding (SFW) is a novel variant of the linear friction stir welding process with the potential to create strong joints between similar, as well as dissimilar sheet metals. It is particularly suitable for soft, low melting point metals such as aluminum, magnesium, and their alloys where resistance spot welding can cause defects such as voids, trapped gas and micro-cracks due to the intense heat requirement for joint formation. Up to now, spot friction welding has focused primarily on aluminum alloys. This paper presents a feasibility study on spot friction welding of AZ31, a wrought magnesium alloy available in sheet form. Lap joints of 1.58-mm-thick magnesium alloy AZ31B-O sheet were produced by spot friction welding. The spot welds were made in 2 sec with 15-mm-diameter pin tool rotating at 500-2,000 rpm. The tool was inserted into 2-sheet stack-ups to depths of either 2.4 or 2.8 mm relative to the top sheet surface. Tensile-shear testing showed that joint strengths up to 4.75 kN were obtained. The removal of surface oxides from the sheets prior to welding increased lap shear strengths about 50% at the 2.4-mm insertion depth and it promoted failure by nugget pull-out rather than by interface separation.

  2. Gas Shielding Technology for Welding and Brazing

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur J.; Gradl, Paul R.

    2012-01-01

    Welding is a common method that allows two metallic materials to be joined together with high structural integrity. When joints need to be leak-tight, light-weight, or free of contaminant-trapping seams or surface asperities, welding tends to be specified. There are many welding techniques, each with its own advantages and disadvantages. Some of these techniques include Forge Welding, Gas Tungsten Arc Welding, Friction Stir Welding, and Laser Beam Welding to name a few. Whichever technique is used, the objective is a structural joint that meets the requirements of a particular component or assembly. A key practice in producing quality welds is the use of shielding gas. This article discusses various weld techniques, quality of the welds, and importance of shielding gas in each of those techniques. Metallic bonds, or joints, are produced when metals are put into intimate contact. In the solid-state "blacksmith welding" process, now called Forge Welding (FOW), the site to be joined is pounded into intimate contact. The surfaces to be joined usually need to be heated to make it easier to deform the metal. The surfaces are sprinkled with a flux to melt surface oxides and given a concave shape so that surface contamination can be squeezed out of the joint as the surfaces are pounded together; otherwise the surface contamination would be trapped in the joint and would weaken the weld. In solid-state welding processes surface oxides or other contamination are typically squeezed out of the joint in "flash."

  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. The use of exploratory experimental designs combined with thermal numerical modelling to obtain a predictive tool for hybrid laser/MIG welding and coating processes

    NASA Astrophysics Data System (ADS)

    Bidi, Lyes; Mattei, Simone; Cicala, Eugen; Andrzejewski, Henri; Le Masson, Philippe; Schroeder, Jeanne

    2011-04-01

    While hybrid laser welding and coating processes involve a large number of physical phenomena, it is currently impossible to predict, for a given set of influencing factors, the shape of the molten zone and the history of temperature fields inside the parts. This remains true for complex processes, such as the hybrid laser/MIG welding process, which consists in combining a laser beam with a MIG torch. The gains obtained result essentially from the synergy of the associated processes: the stability of the process, the quality of the seam realized, and the productivity are increased. This article shows how, by means of a reduced number of experiments (8), it is possible to predict the shape of the molten zone and the temperature field inside parts, for a given window of influencing factors. This method consists in combining the method of exploratory experimental designs with a numerical modelling of the thermal phenomena that occurs during the process, by using the 'heat equivalent source" approach [1-4]. Two validations of this method have been carried out: the first for a set of parameters inside the experimental design, and the other for a set of parameters that lies outside the experimental design, but inside the domain investigated.

  5. 49 CFR 179.100-9 - Welding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false Welding. 179.100-9 Section 179.100-9...112, 114 and 120) § 179.100-9 Welding. (a) All joints shall be fusion-welded...see § 171.7 of this subchapter). Welding procedures, welders and fabricators...

  6. 49 CFR 179.200-10 - Welding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Welding. 179.200-10 Section 179.200-10...DOT-111AW and 115AW) § 179.200-10 Welding. (a) All joints shall be fusion-welded...see § 171.7 of this subchapter). Welding procedures, welders and fabricators...

  7. 49 CFR 179.200-10 - Welding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false Welding. 179.200-10 Section 179.200-10...DOT-111AW and 115AW) § 179.200-10 Welding. (a) All joints shall be fusion-welded...see § 171.7 of this subchapter). Welding procedures, welders and fabricators...

  8. 49 CFR 179.200-10 - Welding.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 false Welding. 179.200-10 Section 179.200-10...DOT-111AW and 115AW) § 179.200-10 Welding. (a) All joints shall be fusion-welded...see § 171.7 of this subchapter). Welding procedures, welders and fabricators...

  9. 49 CFR 179.100-9 - Welding.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 false Welding. 179.100-9 Section 179.100-9...112, 114 and 120) § 179.100-9 Welding. (a) All joints shall be fusion-welded...see § 171.7 of this subchapter). Welding procedures, welders and fabricators...

  10. 49 CFR 179.200-10 - Welding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Welding. 179.200-10 Section 179.200-10...DOT-111AW and 115AW) § 179.200-10 Welding. (a) All joints shall be fusion-welded...see § 171.7 of this subchapter). Welding procedures, welders and fabricators...

  11. 49 CFR 179.300-9 - Welding.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 false Welding. 179.300-9 Section 179.300-9...DOT-106A and 110AW) § 179.300-9 Welding. (a) Longitudinal joints must...fusion welded on class DOT-110A tanks. Welding procedures, welders and...

  12. 49 CFR 179.300-9 - Welding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Welding. 179.300-9 Section 179.300-9...DOT-106A and 110AW) § 179.300-9 Welding. (a) Longitudinal joints must...fusion welded on class DOT-110A tanks. Welding procedures, welders and...

  13. 49 CFR 179.300-9 - Welding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Welding. 179.300-9 Section 179.300-9...DOT-106A and 110AW) § 179.300-9 Welding. (a) Longitudinal joints must...fusion welded on class DOT-110A tanks. Welding procedures, welders and...

  14. 49 CFR 179.300-9 - Welding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false Welding. 179.300-9 Section 179.300-9...DOT-106A and 110AW) § 179.300-9 Welding. (a) Longitudinal joints must...fusion welded on class DOT-110A tanks. Welding procedures, welders and...

  15. 49 CFR 179.100-9 - Welding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Welding. 179.100-9 Section 179.100-9...112, 114 and 120) § 179.100-9 Welding. (a) All joints shall be fusion-welded...see § 171.7 of this subchapter). Welding procedures, welders and fabricators...

  16. 49 CFR 179.100-9 - Welding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Welding. 179.100-9 Section 179.100-9...112, 114 and 120) § 179.100-9 Welding. (a) All joints shall be fusion-welded...see § 171.7 of this subchapter). Welding procedures, welders and fabricators...

  17. 49 CFR 179.300-9 - Welding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false Welding. 179.300-9 Section 179.300-9...DOT-106A and 110AW) § 179.300-9 Welding. (a) Longitudinal joints must...fusion welded on class DOT-110A tanks. Welding procedures, welders and...

  18. 49 CFR 179.100-9 - Welding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false Welding. 179.100-9 Section 179.100-9...112, 114 and 120) § 179.100-9 Welding. (a) All joints shall be fusion-welded...see § 171.7 of this subchapter). Welding procedures, welders and fabricators...

  19. 49 CFR 179.200-10 - Welding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false Welding. 179.200-10 Section 179.200-10...DOT-111AW and 115AW) § 179.200-10 Welding. (a) All joints shall be fusion-welded...see § 171.7 of this subchapter). Welding procedures, welders and fabricators...

  20. Clamp and Gas Nozzle for TIG Welding

    NASA Technical Reports Server (NTRS)

    Gue, G. B.; Goller, H. L.

    1982-01-01

    Tool that combines clamp with gas nozzle is aid to tungsten/inert-gas (TIG) welding in hard-to-reach spots. Tool holds work to be welded while directing a stream of argon gas at weld joint, providing an oxygen-free environment for tungsten-arc welding.

  1. Magnetic Deflection Of Welding Electron Beam

    NASA Technical Reports Server (NTRS)

    Malinzak, R. Michael; Booth, Gary N.

    1991-01-01

    Electron-beam welds inside small metal parts produced with aid of magnetic deflector. Beam redirected so it strikes workpiece at effective angle. Weld joint positioned to where heavy microfissure concentration removed when subsequent machining required, increasing likelihood of removing any weld defects located in face side of electron-beam weld.

  2. Analytical model of residual stress determination in girth weld pipes

    NASA Astrophysics Data System (ADS)

    Donato, G. V.; Teodosio, Joel R.

    2000-02-01

    This paper presents a theoretical model to determine the superficial inside and outside residual stresses in girth weld pipes. The model is an analytical solution using geometric dimensions of the pipe, material properties and the weld procedure in order to define the residual stress distribution which was compared with the experimental measurements by x-ray diffraction method and with the results presented in other papers. The equations considering the most important variables of the problem were proposed to obtain a quick residual stress estimation in the middle of the weld metal of the joint. The proposed model is useful to preview the welding process stresses as well as allowing welding variables study sensibility and the residual stress optimization. The model considers all inherent simplification applied to the theory.

  3. Analytical model of residual stress determination in girth weld pipes

    NASA Astrophysics Data System (ADS)

    Donato, G. V. P.; Teodosio, Joel R.

    2001-02-01

    This paper presents a theoretical model to determine the superficial inside and outside residual stresses in girth weld pipes. The model is an analytical solution using geometric dimensions of the pipe, material properties and the weld procedure in order to define the residual stress distribution which was compared with the experimental measurements by x-ray diffraction method and with the results presented in other papers. The equations considering the most important variables of the problem were proposed to obtain a quick residual stress estimation in the middle of the weld metal of the joint. The proposed model is useful to preview the welding process stresses as well as allowing welding variables study sensibility and the residual stress optimization. The model considers all inherent simplification applied to the theory.

  4. Optimization of laser welding of DP/TRIP steel sheets using statistical approach

    NASA Astrophysics Data System (ADS)

    Reisgen, U.; Schleser, M.; Mokrov, O.; Ahmed, E.

    2012-02-01

    Generally, the quality of a weld joint is directly influenced by the welding input parameter settings. Selection of proper process parameters is important to obtain the desired weld bead profile and quality. In this research work, numerical and graphical optimization techniques of the CO 2 laser beam welding of dual phase (DP600)/transformation induced plasticity (TRIP700) steel sheets were carried out using response surface methodology (RSM) based on Box-Behnken design. The procedure was established to improve the weld quality, increase the productivity and minimize the total operation cost by considering the welding parameters range of laser power (2-2.2 kW), welding speed (40-50 mm/s) and focus position (-1 to 0 mm). It was found that, RSM can be considered as a powerful tool in experimental welding optimization, even when the experimenter does not have a model for the process. Strong, efficient and low cost weld joints could be achieved using the optimum welding conditions.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  6. Parametric study in weld mismatch of longitudinally welded SSME HPFTP inlet

    NASA Technical Reports Server (NTRS)

    Min, J. B.; Spanyer, K. L.; Brunair, R. M.

    1991-01-01

    Welded joints are an essential part of pressure vessels such as the Space Shuttle Main Engine (SSME) Turbopumps. Defects produced in the welding process can be detrimental to weld performance. Recently, review of the SSME high pressure fuel turbopump (HPFTP) titanium inlet x rays revealed several weld discrepancies such as penetrameter density issues, film processing discrepancies, weld width discrepancies, porosity, lack of fusion, and weld offsets. Currently, the sensitivity of welded structures to defects is of concern. From a fatigue standpoint, weld offset may have a serious effect since local yielding, in general, aggravates cyclic stress effects. Therefore, the weld offset issue is considered. Using the finite element method and mathematical formulations, parametric studies were conducted to determine the influence of weld offsets and a variation of weld widths in longitudinally welded cylindrical structures with equal wall thickness on both sides of the joint. From the study, the finite element results and theoretical solutions are presented.

  7. Microstructures and Mechanical Properties of Laser Penetration Welding Joint With/Without Ni-Foil in an Overlap Steel-on-Aluminum Configuration

    NASA Astrophysics Data System (ADS)

    Chen, Shuhai; Huang, Jihua; Ma, Ke; Zhao, Xingke; Vivek, Anupam

    2014-06-01

    The microstructures and mechanical properties of laser penetration welding joints with/without Ni-foil in an overlap steel-on-aluminum configuration were investigated. The interfacial structure between fusion zone and aluminum alloy without Ni-foil consists of FeAl/FeAl3. After the Ni-foil is added, the interfacial structure transforms into Ni1.1Al0.9/FeAl3, and the molten pool of aluminum alloy is expanded, which leads to the formation of the NiAl3 between Ni-foil and the molten pool. A banded structure composed of ?(Fe, Ni)Al appears whether the joints are made with/without Ni-foil over the reaction zone. It was found that the Ni-foil enhanced tensile property of the joint, expanded usable processing parameters, and decreased microhardness of the intermetallic compounds. The enhancement of mechanical properties is attributed to the improvement of the toughness of the joint made by Ni-foil.

  8. Measuring Weld Parameters By Spectroscopy

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur; Mcclure, John C.; Marques, Richard E.; Martinez, Luis F.

    1993-01-01

    Optical-emission spectrometric apparatus used to monitor variable-polarity plasma arc welding of aluminum alloys. Spectrometer incorporated into control system to ensure quality of weld because in keyhole, arc fully penetrates weld joint and impurities flushed out. Apparatus helps ensure high quality of weld by monitoring such contaminants as oxygen and hydrogen in shield gas, detecting inadequate flow of shield gas, and sensing changes in temperature of arc with changes in arc current and voltage.

  9. Identification Of Anomalies In Welds

    NASA Technical Reports Server (NTRS)

    Knichen, David G.

    1989-01-01

    Advanced techniques combined with conventional analytical methods. Combination of real-time radiography, scanning electron microscopy, and energy-dispersive spectrometry identify enigmatic features in radiographs of welds where standard tensile, hardness, and electrical-conductivity tests and visible-light microscopic and macroscopic examinations insufficient. New combination of techniques applied successfully to variable-polarity-plasma-arc welds of 2219 aluminum alloy. Joints subjected to penetration, fill, and weld-repair passes with 2319 aluminum weld wire.

  10. Analysis and Characterization of the Role of Ni Interlayer in the Friction Welding of Titanium and 304 Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Muralimohan, C. H.; Ashfaq, M.; Ashiri, Rouholah; Muthupandi, V.; Sivaprasad, K.

    2015-10-01

    Joining of commercially pure Ti to 304 stainless steel by fusion welding processes possesses problems due to the formation of brittle intermetallic compounds in the weld metal, which degrade the mechanical properties of the joints. Solid-state welding processes are contemplated to overcome these problems. However, intermetallic compounds are likely to form even in Ti-SS joints produced with solid-state welding processes such as friction welding process. Therefore, interlayers are employed to prevent the direct contact between two base metals and thereby mainly to suppress the formation of brittle Ti-Fe intermetallic compounds. In the present study, friction-welded joints between commercially pure titanium and 304 stainless steel were obtained using a thin nickel interlayer. Then, the joints were characterized by optical microscopy, scanning electron microscopy, energy dispersive spectrometry, and X-ray diffractometry. The mechanical properties of the joints were evaluated by microhardness survey and tensile tests. Although the results showed that the tensile strength of the joints is even lower than titanium base metal, it is higher than that of the joints which were produced without nickel interlayer. The highest hardness value was observed at the interface between titanium and nickel interlayers indicating the formation of Ni-Ti intermetallic compounds. Formation these compounds was validated by XRD patterns. Moreover, in tensile tests, fracture of the joints occurred along this interface which is related to its brittle nature.

  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 impedance and Lamb wave SHM techniques for monitoring structural integrity of and through welded joints

    NASA Astrophysics Data System (ADS)

    Grisso, Benjamin L.; Salvino, Liming W.; Singh, Gurjiwan; Singh, Gurjashan; Tansel, Ibrahim N.

    2011-04-01

    In this study, the feasibility of monitoring the structural integrity of welded thick aluminum plates was experimentally tested using two widely used SHM methods: impedance and Lamb wave analyses. The test structure was fabricated from two 1/4 inch thick aluminum plates welded together, and various structural defects, such as holes and cuts, were applied. At each of these damage steps, data were collected for both the impedance and Lamb wave techniques. Results consistently revealed the impedance method to be sensitive to damage in and through the weld. The envelopes of the Lamb wave signals were calculated using the S-transformation of the time histories. There was significant change to the curves when different defects were added to the plate. Both of the SHM methods studied detected each of the cuts and holes acting to reduce the overall strength of the structure. Each technique also detected the hole damage on the opposite side of the weld as the sensor(s) used for damage detection. The study further verified that surface waves move across welds allowing SHM methods to detect the defects even if the sensors are located on neighboring plates or geometries.

  13. 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.

  14. Improvement of Weld Characteristics by Laser-Arc Double-Sided Welding Compared to Single Arc Welding

    NASA Astrophysics Data System (ADS)

    Lei, Zhenglong; Zhang, Kezhao; Hu, Xue; Yang, Yuhe; Chen, Yanbin; Wu, Yichao

    2015-11-01

    The single arc welding and laser-arc double-sided welding (LADSW) processes are investigated by virtue of test welds. The impacts of the laser beam during the LADSW process on the weld characteristics are studied from weld geometry, crystal morphology, and the mechanical properties of the joints. Compared with the single arc welding, the LADSW process improves the energy density and reduces the range of arc action, which together leads to a doubling of weld penetration depth. When penetrated by the laser beam, the liquid metal of the arc welding pool experiences severe fluctuations, leading to a finer grain size in the range of 17-26 ?m in the LADSW weld, a reduction of nearly 63% compared to the grains in the single arc weld. The tensile strength and elongation-to-failure of the LADSW weld were increased by nearly 10 and 100% over the single arc welding, respectively.

  15. Corrosion behavior of the friction-stir-welded joints of 2A14-T6 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Qin, Hai-long; Zhang, Hua; Sun, Da-tong; Zhuang, Qian-yu

    2015-06-01

    The corrosion behavior of friction-stir-welded 2A14-T6 aluminum alloy was investigated by immersion testing in immersion exfoliation corrosion (EXCO) solution. Electrochemical measurements (open circuit potential, potentiodynamic polarization curves, and electrochemical impedance spectroscopy), scanning electron microscopy, and energy dispersive spectroscopy were employed for analyzing the corrosion mechanism. The results show that, compared to the base material, the corrosion resistance of the friction-stir welds is greatly improved, and the weld nugget has the highest corrosion resistance. The pitting susceptibility originates from the edge of Al-Cu-Fe-Mn-Si phase particles as the cathode compared to the matrix due to their high self-corrosion potential. No corrosion activity is observed around the ? phase (Al2Cu) after 2 h of immersion in EXCO solution.

  16. Development of a New Joint Geometry for FSW

    NASA Astrophysics Data System (ADS)

    Penalva, M. L.; Otaegi, A.; Pujana, J.; Rivero, A.

    2009-11-01

    Friction Stir Welding (FSW) is an emerging solid state joining technology that allows welding most aluminum alloys that otherwise are difficult to weld by using conventional fusion based technologies. The technology is of particular interest for transport applications, since welded structures are considered to offer cost and weight savings. From a point of view of the joint geometries, FSW is mature for simple configurations. Most work to date has concentrated on butt welds and, only to a certain degree, on overlap configurations. Different designs such as T-sections, corner welds, box sections… are then principally restricted to the use of butt weld configurations. However, it is necessary for FSW to be able to be applied to new geometries in order to spread its use to a wider range of applications. Present work explores the feasibility of producing corner fillet geometries using FSW. Although such a kind of geometry has traditionally been considered unfeasible for the process, it seems to have the greatest potential to be used for T-joint configurations, a recurrent design pattern in transport applications. In order to study the feasibility of the proposed new joint geometry, a specific tool has been developed and a set of welds has been produced with it. Microstructure of the produced welds has been analyzed. According to the obtained results, the proposed joint geometry seems to be feasible. Main problem pending to solve is how to avoid the formation of a tunnel defect in the weld centre line due to a suck effect of the tool on the stirred material. Further improvements are proposed to produce welds with acceptable quality.

  17. Internal Filler-Wire Feed For Arc Welding

    NASA Technical Reports Server (NTRS)

    Morgan, Gene E.; Dyer, Gerald E.

    1990-01-01

    Tungsten electrode for gas/tungsten arc welding contains lengthwise channel for feeding filler wire to weld joint. Channel makes it unnecessary to feed wire through guides outside electrode, conserving valuable space near weld and protects wire from deformation by contact with other parts in vicinity of weld. Helpful in robotic or automatic welding.

  18. General Mechanical Repair. Welding. Volume 2. Teacher's Guide.

    ERIC Educational Resources Information Center

    East Texas State Univ., Commerce. Occupational Curriculum Lab.

    Five units on welding are presented in this teacher's guide. The units are the following: introduction to oxyacetylene welding, oxyacetylene welding positions and applications, use of the cutting torch, introduction to shielded metal arc welding, and welding joints and positions. Each instructional unit generally contains eight components:…

  19. Residual stress improvement process by vibration during welding

    SciTech Connect

    Nishimura, T.; Aoki, S.

    1995-12-31

    The strong effect of residual stresses on fatigue or stress-corrosion cracking is a well-recognized phenomenon. There are a number of important technological processes which produce or reduce residual stresses. The residual stress created in a structure by a welding operation may influence the mechanical behavior of the structure in several ways. In particular, a reduction in the residual stress caused by welding is very important. A new welding residual stress improvement process is proposed in this paper. The new method is carried out using vibrational loading which is applied during the welding operation. The advantage of this method is that the vibrational load is generated by a small shaker. Hence, this method is expected to be a practical one. A simple experiment was carried out for a single pass V-shaped groove welded steel plate. The residual stress distributions on several conditions of the excitation frequencies were measured using X-ray diffraction techniques. The experimental results show that tensile residual stress in the bead can be reduced by this method. The mechanism of stress redistribution in a welded joint during vibrational loading is described qualitatively. An elasto-plastic model has been presented to describe the behavior of welded joints under the action of a vibrational force and cooling temperature. Since this process uses a small shaker, it is believed that the benefit of this method can be obtained through minimum additional cost.

  20. Welding of 316L Austenitic Stainless Steel with Activated Tungsten Inert Gas Process

    NASA Astrophysics Data System (ADS)

    Ahmadi, E.; Ebrahimi, A. R.

    2015-02-01

    The use of activating flux in TIG welding process is one of the most notable techniques which are developed recently. This technique, known as A-TIG welding, increases the penetration depth and improves the productivity of the TIG welding. In the present study, four oxide fluxes (SiO2, TiO2, Cr2O3, and CaO) were used to investigate the effect of activating flux on the depth/width ratio and mechanical property of 316L austenitic stainless steel. The effect of coating density of activating flux on the weld pool shape and oxygen content in the weld after the welding process was studied systematically. Experimental results indicated that the maximum depth/width ratio of stainless steel activated TIG weld was obtained when the coating density was 2.6, 1.3, 2, and 7.8 mg/cm2 for SiO2, TiO2, Cr2O3, and CaO, respectively. The certain range of oxygen content dissolved in the weld, led to a significant increase in the penetration capability of TIG welds. TIG welding with active fluxes can increase the delta-ferrite content and improves the mechanical strength of the welded joint.

  1. Effects of thermal aging on the microstructure of Type-II boundaries in dissimilar metal weld joints

    NASA Astrophysics Data System (ADS)

    Yoo, Seung Chang; Choi, Kyoung Joon; Bahn, Chi Bum; Kim, Si Hoon; Kim, Ju Young; Kim, Ji Hyun

    2015-04-01

    In order to investigate the effects of long-term thermal aging on the microstructural evolution of Type-II boundary regions in the weld metal of Alloy 152, a representative dissimilar metal weld was fabricated from Alloy 690, Alloy 152, and A533 Gr.B. This mock-up was thermally aged at 450 °C to accelerate the effects of thermal aging in a nuclear power plant operation condition (320 °C). The microstructure of the Type-II boundary region of the weld root, which is parallel to and within 100 ?m of the fusion boundary and known to be more susceptible to material degradation, was then characterized after different aging times using a scanning electron microscope equipped with an energy dispersive X-ray spectroscope for micro-compositional analysis, electron backscattered diffraction detector for grain and grain boundary orientation analysis, and a nanoindenter for measurement of mechanical properties. Through this, it was found that a steep compositional gradient and high grain average misorientation is created in the narrow zone between the Type-II and fusion boundaries, while the concentration of chromium and number of low-angle grain boundaries increases with aging time. A high average hardness was also observed in the same region of the dissimilar metal welds, with hardness peaking with thermal aging simulating an operational time of 15 years.

  2. 46 CFR 154.650 - Cargo tank and process pressure vessel welding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... following: (1) Each welded joint of the shells must be a full penetration butt weld, except dome to shell connections may have full penetration tee welds. (2) Each nozzle weld must be of the full penetration type, except for small penetrations on domes. (d) Each welded joint in an independent tank type C or in...

  3. Differences in skeletal components of temporomandibular joint of an early medieval and contemporary Croatian population obtained by different methods.

    PubMed

    Kranjcic, Josip; Slaus, Mario; Persic, Sanja; Vodanovic, Marin; Vojvodic, Denis

    2016-01-01

    The temporomandibular joint (TMJ) is one of the most complex joints in the human body. The anatomical configuration of the TMJ allows for a large range of mandibular movements as well as transmission of masticatory forces and loads to the skull base. The measurements of the TMJ's anatomical structures and their interpretations contribute to the understanding of how pathological changes, tooth loss, and the type of diet (changing throughout human history) can affect biomechanical conditions of the masticatory system and the TMJ. The human TMJ and its constituent parts are still the subject of extensive investigation and comparisons of measurement methods are being made in order to determine the most precise and suitable measurement methods. The aim of this study has been to examine the morphology of skeletal components of TMJ of an early medieval population (EMP) in Croatia and to compare measured values with TMJ values of the contemporary Croatian population (CP) using various methods of measurement. The study was performed on 30 EMP specimens - human dry skulls, aged from 18 to 55 years, and 30 CP human dry skulls, aged from 18 to 65 years. Only fully preserved specimens (in measured areas) were included. The articular eminence (AE) inclination was measured in relation to the Frankfurt horizontal using two methods. Also, the AE height (glenoid fossa depth) and the length of the curved line - highest to the lowest point of the AE were measured. Measurements were performed on lateral skull photographs, panoramic radiographs and lateral cephalograms using VistaMetrix software on skull images. The results were statistically analyzed using SPSS statistical software. No statistically significant differences were obtained for AE parameters between the EMP and CP populations independent of age and gender. However, statistically significant (p<0.05) differences were revealed when comparing results of three different measuring methods. It could not be determined which of the used measurement methods is the most accurate due to the different results obtained as well as the presence of possible shortcomings and limitations of the various methods (measuring points are difficult to determine and/or they are not clearly observed in the investigated images to be precisely marked and measured; distortion and magnification of structures on radiographic images are present). Therefore, due to the limitations of this study, the obtained results could serve only as orienting information. PMID:25899341

  4. Numerical simulation of MIG type arc welding induced residual stresses and distortions in thin sheets of S235 steel

    NASA Astrophysics Data System (ADS)

    Sakri, A.; Guidara, M.; Elhalouani, F.

    2010-11-01

    This paper investigates distortions and residual stresses which are induced in butt joint of thin plates using Metal Inert Gas welding. In fact, a distribution of heat flux is implemented in finite element simulation of the welding process. Thermo-elastic-plastic finite element methods are applied to modelling the thermal and mechanical behaviour of the welded plate during the welding process. Prediction of temperature variations and heat affected zone as well as longitudinal and transverse shrinkage, angular distortion, and residual stress are obtained. Comparisons are made between numerical and experimental results on out-of-plane displacements of steel assembly.

  5. Physical Nature of the Processes in Forming Structures, Phase and Chemical Compositions of Medium-Carbon Steel Welds

    NASA Astrophysics Data System (ADS)

    Il'yaschenko, D. P.; Chinakhov, D. A.; Danilov, V. I.; Schlyakhova, G. V.; Gotovshchik, Yu M.

    2015-09-01

    This work presents peculiarities of forming a structure, phase and chemical composition while welding medium-carbon steels (Steel 45) depending on a heat content of molten electrode metal droplets when using welding power sources having different power parameters. It was experimentally established that the power inverter provides the decreased heat input into droplets of electrode metal during the welding process. This stimulates obtaining a fine-grained structure of the deposited metal and heat affected zone, reduces the extent of the HAZ that enhances working properties of welded joints.

  6. 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.

  7. Better welds for launch vehicles

    NASA Technical Reports Server (NTRS)

    Schwinghamer, Robert J.

    1987-01-01

    The use and benefits of automated variable polarity plasma arc (VPPA) welding of Al joints are described. The entire welding system, including welding head manipulator, weld-wire feed, torch, and power supply are computer controlled. The importance of proper torch dynamics and the control of argon gas flow through the plasma orifice are discussed. The use of arc-voltage control, the improvements in system monitoring, and the reduction or elimination of electromagnetic interferences are examined. VPPA welding is applicable to joining Space Shuttle components, and an example of its use on an External Tank of the Shuttle is presented.

  8. Shimmed electron beam welding process

    DOEpatents

    Feng, Ganjiang (Clifton Park, NY); Nowak, Daniel Anthony (Alplaus, NY); Murphy, John Thomas (Niskayuna, NY)

    2002-01-01

    A modified electron beam welding process effects welding of joints between superalloy materials by inserting a weldable shim in the joint and heating the superalloy materials with an electron beam. The process insures a full penetration of joints with a consistent percentage of filler material and thereby improves fatigue life of the joint by three to four times as compared with the prior art. The process also allows variable shim thickness and joint fit-up gaps to provide increased flexibility for manufacturing when joining complex airfoil structures and the like.

  9. Creep rupture strength of activated-TIG welded 316L(N) stainless steel

    NASA Astrophysics Data System (ADS)

    Sakthivel, T.; Vasudevan, M.; Laha, K.; Parameswaran, P.; Chandravathi, K. S.; Mathew, M. D.; Bhaduri, A. K.

    2011-06-01

    316L(N) stainless steel plates were joined using activated-tungsten inert gas (A-TIG) welding and conventional TIG welding process. Creep rupture behavior of 316L(N) base metal, and weld joints made by A-TIG and conventional TIG welding process were investigated at 923 K over a stress range of 160-280 MPa. Creep test results showed that the enhancement in creep rupture strength of weld joint fabricated by A-TIG welding process over conventional TIG welding process. Both the weld joints fractured in the weld metal. Microstructural observation showed lower ?-ferrite content, alignment of columnar grain with ?-ferrite along applied stress direction and less strength disparity between columnar and equiaxed grains of weld metal in A-TIG joint than in MP-TIG joint. These had been attributed to initiate less creep cavitation in weld metal of A-TIG joint leading to improvement in creep rupture strength.

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

    PubMed

    Watanabe, Ikuya; Wallace, Cameron

    2008-01-01

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

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

    PubMed Central

    Watanabe, Ikuya; Wallace, Cameron

    2008-01-01

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

  12. Heavy-section welding with very high power laser beams: the challenge

    NASA Astrophysics Data System (ADS)

    Goussain, Jean-Claude; Becker, Ahim; Chehaibou, A.; Leca, P.

    1997-08-01

    The 45 kW CO2 laser system of Institut de Soudure was used to evaluate and explore the possibilities offered by the high power laser beams for welding different materials in various thickness and in different welding positions. Stainless steels, low carbon steels, aluminum and titanium alloys were studied. Butt joints in 10 to 35 mm thick plates were achieved and evaluated by radiographic, metallurgical and mechanical tests. Gaps and alignment tolerances were determined with and without filler wire in order to obtain acceptable welds concerning the weld geometry, the aspect on front and end root sides. The main problem raised by heavy section welding concerns weld porosity in the weld which increases drastically with the thickness of the weld. Indications are given on their origin and the way to proceed in order to better control them. Lastly some large parts, recently welded on the system, are presented and discussed before drawing some conclusions on the prospects of very high power laser welding.

  13. Predictive permeability model of faults in crystalline rocks; verification by joint hydraulic factor (JH) obtained from water pressure tests

    NASA Astrophysics Data System (ADS)

    Barani, Hamidreza Rostami; Lashkaripour, Gholamreza; Ghafoori, Mohammad

    2014-08-01

    In the present study, a new model is proposed to predict the permeability per fracture in the fault zones by a new parameter named joint hydraulic factor (JH). JH is obtained from Water Pressure Test (WPT) and modified by the degree of fracturing. The results of JH correspond with quantitative fault zone descriptions, qualitative fracture, and fault rock properties. In this respect, a case study was done based on the data collected from Seyahoo dam site located in the east of Iran to provide the permeability prediction model of fault zone structures. Datasets including scan-lines, drill cores, and water pressure tests in the terrain of Andesite and Basalt rocks were used to analyse the variability of in-site relative permeability of a range from fault zones to host rocks. The rock mass joint permeability quality, therefore, is defined by the JH. JH data analysis showed that the background sub-zone had commonly <3 Lu (less of 5 ×10-5 m 3/s) per fracture, whereas the fault core had permeability characteristics nearly as low as the outer damage zone, represented by 8 Lu (1.3 ×10-4 m 3/s) per fracture, with occasional peaks towards 12 Lu (2 ×10-4 m 3/s) per fracture. The maximum JH value belongs to the inner damage zone, marginal to the fault core, with 14-22 Lu (2.3 ×10-4-3.6 ×10-4 m 3/s) per fracture, locally exceeding 25 Lu (4.1 ×10-4 m 3/s) per fracture. This gives a proportional relationship for JH approximately 1:4:2 between the fault core, inner damage zone, and outer damage zone of extensional fault zones in crystalline rocks. The results of the verification exercise revealed that the new approach would be efficient and that the JH parameter is a reliable scale for the fracture permeability change. It can be concluded that using short duration hydraulic tests (WPTs) and fracture frequency (FF) to calculate the JH parameter provides a possibility to describe a complex situation and compare, discuss, and weigh the hydraulic quality to make predictions as to the permeability models and permeation amounts of different zone structures.

  14. Effect of Different Chromium Additions on the Microstructure and Mechanical Properties of Multipass Weld Joint of Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Kang, Dong Hoon; Lee, Hae Woo

    2012-12-01

    The correlation between the mechanical properties and ferrite volume fraction (approximately 40, 50, and 60 Ferrite Number [FN]) in duplex stainless steel weld metals were investigated by changing the Cr content in filler wires with a flux-cored arc-welding (FCAW) process. The interpass temperature was thoroughly maintained under a maximum of 423 K (150 °C), and the heat input was also sustained at a level under 15 KJ/cm in order to minimize defects. The microstructure examination demonstrated that the ?-ferrite volume fraction in the deposited metals increased as the Cr/Ni equivalent ratio increased, and consequently, chromium nitride (Cr2N) precipitation was prone to occur in the ferrite domains due to low solubility of nitrogen in this phase. Thus, more dislocations are pinned by the precipitates, thereby lowering the mobility of the dislocations. Not only can this lead to the strength improvement, but also it can accentuate embrittlement of the weld metal at subzero temperature. Additionally, the solid-solution strengthening by an increase of Cr and Mo content in austenite phase depending on the reduction of austenite proportion also made an impact on the increase of the tensile and yield strength. On the other hand, the impact test (at 293 K, 223 K, and 173 K [20 °C, -50 °C, and -100 °C]) showed that the specimen containing about 40 to 50 FN had the best result. The absorbed energy of about 40 to 50 J sufficiently satisfied the requirements for industrial applications at 223 K (-50 °C), while the ductile-to-brittle transition behavior exhibited in weldment containing 60 FN. As the test temperature decreased under 223 K (-50 °C), a narrow and deep dimple was transformed into a wide and shallow dimple, and a significant portion of the fracture surface was occupied by a flat cleavage facet with river patterns.

  15. 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.

  16. Method for welding beryllium

    SciTech Connect

    Dixon, R.D.; Smith, F.M.; O`Leary, R.F.

    1995-12-31

    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. Beryllium parts made using this method can be used as structural components in aircraft, satellites and space applications.

  17. Method for welding beryllium

    DOEpatents

    Dixon, R.D.; Smith, F.M.; O`Leary, R.F.

    1997-04-01

    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. 9 figs.

  18. Weld braze technique

    DOEpatents

    Kanne, Jr., William R. (Aiken, SC); Kelker, Jr., John W. (North Augusta, SC); Alexander, Robert J. (Aiken, SC)

    1982-01-01

    High-strength metal joints are formed by a combined weld-braze technique. A hollow cylindrical metal member is forced into an undersized counterbore in another metal member with a suitable braze metal disposed along the bottom of the counterbore. Force and current applied to the members in an evacuated chamber results in the concurrent formation of the weld along the sides of the counterbore and a braze along the bottom of the counterbore in one continuous operation.

  19. Welding and joining techniques.

    PubMed

    Chipperfield, F A; Dunkerton, S B

    2001-05-01

    There is a welding solution for most applications. As products must meet more stringent requirements or require more flexible processes to aid design or reduce cost, further improvements or totally new processes are likely to be developed. Quality control aspects are also becoming more important to meet regulation, and monitoring and control of welding processes and the standardised testing of joints will meet some if not all of these requirements. PMID:11521652

  20. Thermal stir welding apparatus

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey (Inventor)

    2011-01-01

    A welding method and apparatus are provided for forming a weld joint between first and second elements of a workpiece. The method includes heating the first and second elements to form an interface of material in a plasticized or melted state interface between the elements. The interface material is then allowed to cool to a plasticized state if previously in a melted state. The interface material, while in the plasticized state, is then mixed, for example, using a grinding/extruding process, to remove any dendritic-type weld microstructures introduced into the interface material during the heating process.

  1. Thermal stir welding process

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey (Inventor)

    2012-01-01

    A welding method is provided for forming a weld joint between first and second elements of a workpiece. The method includes heating the first and second elements to form an interface of material in a plasticized or melted state interface between the elements. The interface material is then allowed to cool to a plasticized state if previously in a melted state. The interface material, while in the plasticized state, is then mixed, for example, using a grinding/extruding process, to remove any dendritic-type weld microstructures introduced into the interface material during the heating process.

  2. Microstructure change in the interface of co2 laser welded zirconium alloys

    NASA Astrophysics Data System (ADS)

    Boutarek, N.; Azzougui, B.; Saidi, D.; Neggache, M.

    2009-11-01

    Welding is a joining procedure that offers some benefits over mechanical fasteners such as weight reduction and absence of notches induced by machining operations. CO2 laser beam welding with a continuous wave is a high energy density and low heat input process. The result of this is a small heat-affected zone (HAZ), which cools very rapidly with very little distortion, and a high depth-to-width ratio for the Welding is a necessary process during fabricating fuel rods and fuel assemblies with Zircaloy-4 cladding, and electron beam welding is one of the commonly- used method. In this work, the joining of zirconium alloys was attempted by laser beam welding. A 2 kW CO2 laser is used and the joints are obtained from similar materials, which are plates of Zircaloy-4 (2 mm thick). A series of zirconium alloys were welded and investigated in a tow-fold approach: (1) process optimisation: the laser processing parameters are optimized to obtain welds with minimum defects, and (2) material characterisation: weld microstructures were evaluated. The microstructure and the phases present in the resolidified zone of the laser -welded specimens were analyzed by optical and scanning electron microscopy, X-ray diffraction, and also by the realization of micro hardness diagrams. A particular attention was made to study the correlation between surface structure and mechanical behaviour.

  3. Research on key influence factors of laser overlap welding of automobile body galvanized steel

    NASA Astrophysics Data System (ADS)

    Chen, Genyu; Mei, Lifang; Zhang, Mingjun; Zhang, Yi; Wang, Zujian

    2013-02-01

    In views of structure characteristics of the auto-body parts, the influences of the beam incident angle and joint gap on the performance of laser overlap welded joints were investigated. The experimental results indicate that there were the critical values of beam incident angle and joint gap during laser overlap welding of galvanized steel. The thickness of sheet and the width of joint had a certain influence on the critical beam incident angle and the limit joint gap. With regard to thicker sheet, the limit joint gap can increase appropriately, but the critical beam incident angle should not be too big. With narrow weld width, the laser beam incident angle can increase appropriately, but the joint gap should not be bigger. Additionally, the critical beam incident angle and the limit joint gap were varied with the thickness of the upper sheet. The tensile-shear tests show that the maximum tensile-shear strength of the joint can be obtained with an optimized beam incident angle and joint gap.

  4. 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.

    2015-07-01

    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.

  5. 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.

  6. Numerical Simulation on Joining of Ceramics with Metal by Friction Welding Technique

    NASA Astrophysics Data System (ADS)

    Jesudoss Hynes, N. Rajesh; Nagaraj, P.; Basil, S. Joshua

    The joining of ceramic and metals can be done by different techniques such as ultrasonic joining, brazing, transient liquid phase diffusion bonding, and friction welding. Friction Welding is a solid state joining process that generates heat through mechanical friction between a moving workpiece and a stationary component. In this article, numerical simulation on thermal analysis of friction welded ceramic/metal joint has been carried out by using Finite Element Analysis (FEA) software. The finite element analysis helps in better understanding of the friction welding process of joining ceramics with metals and it is important to calculate temperature and stress fields during the welding process. Based on the obtained temperature distribution the graphs were plotted between the lengths of the joint corresponding to the temperatures. To increase the wettability, aluminium sheet was used as an interlayer. Hence, numerical simulation of friction welding process is done by varying the interlayer sheet thickness. Transient thermal analysis had been carried out for each cases and temperature distribution was studied. From the simulation studies, it is found that the increase in interlayer thickness reduces the heat affected zone and eventually improves the joint efficiency of alumina/aluminum alloy joints.

  7. Quick Check Of Butt-Weld Alignment

    NASA Technical Reports Server (NTRS)

    Smith, Matthew A.

    1990-01-01

    Proposed tool measures alignments of plates before butt-welded. Provides nearly instantaneous check on alignment, thereby facilitating repetitive measurements along length of weld joint. Reduces risk of contamination of weld from dirty measuring tools. Middle photodetector indicates acceptable alignment when position of transmitter fiber preciously matches that of center receiver fiber. If plates offset, other photodetectors signal misalignment.

  8. Viewing electron-beam welds in progress

    NASA Technical Reports Server (NTRS)

    Armenoff, C. T.

    1980-01-01

    With aid of optical filter, operator of electron-beam welding machine can view TV image of joint that is being welded and can make corrections as necessary. Operator can see when weld bead gets out of alinement, for example, and compensate for deflection of electron beam caused by changes in magnetic field.

  9. Welds chilled by liquid coolant manifold

    NASA Technical Reports Server (NTRS)

    Odor, M. E.; Whiffen, E. E.

    1966-01-01

    Liquid coolant chill tool provides uniform cooling to materials adjacent to weld areas on long or contoured butt welds. This tool incorporates a manifold that clamps to the weld joint by vacuum and circulates liquid in direct contact with adjacent material.

  10. 49 CFR 179.220-10 - Welding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false Welding. 179.220-10 Section 179.220-10...DOT-111AW and 115AW) § 179.220-10 Welding. (a) All joints must be fusion...see § 171.7 of this subchapter). Welding procedures, welders, and...

  11. 49 CFR 179.220-10 - Welding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Welding. 179.220-10 Section 179.220-10...DOT-111AW and 115AW) § 179.220-10 Welding. (a) All joints must be fusion...see § 171.7 of this subchapter). Welding procedures, welders, and...

  12. 49 CFR 179.220-10 - Welding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false Welding. 179.220-10 Section 179.220-10...DOT-111AW and 115AW) § 179.220-10 Welding. (a) All joints must be fusion...see § 171.7 of this subchapter). Welding procedures, welders, and...

  13. 49 CFR 179.220-10 - Welding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Welding. 179.220-10 Section 179.220-10...DOT-111AW and 115AW) § 179.220-10 Welding. (a) All joints must be fusion...see § 171.7 of this subchapter). Welding procedures, welders, and...

  14. 49 CFR 179.220-10 - Welding.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 false Welding. 179.220-10 Section 179.220-10...DOT-111AW and 115AW) § 179.220-10 Welding. (a) All joints must be fusion...see § 171.7 of this subchapter). Welding procedures, welders, and...

  15. 49 CFR 179.220-10 - Welding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Welding. 179.220-10 Section 179.220-10...-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.220-10 Welding. (a) All joints must be fusion... subchapter). Welding procedures, welders, and fabricators shall be approved. (b) Radioscopy of the...

  16. 49 CFR 179.300-9 - Welding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Welding. 179.300-9 Section 179.300-9...-Unit Tank Car Tanks (Classes DOT-106A and 110AW) § 179.300-9 Welding. (a) Longitudinal joints must be... class DOT-110A tanks. Welding procedures, welders and fabricators must be approved in accordance...

  17. 49 CFR 179.400-11 - Welding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Welding. 179.400-11 Section 179.400-11...-11 Welding. (a) Except for closure of openings and a maximum of two circumferential closing joints in... subchapter). (d) Each welding procedure, welder, and fabricator must be approved....

  18. 49 CFR 179.100-9 - Welding.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Welding. 179.100-9 Section 179.100-9... Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120) § 179.100-9 Welding. (a) All joints shall be..., see § 171.7 of this subchapter). Welding procedures, welders and fabricators shall be approved. (b)...

  19. 49 CFR 179.300-9 - Welding.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Welding. 179.300-9 Section 179.300-9...-Unit Tank Car Tanks (Classes DOT-106A and 110AW) § 179.300-9 Welding. (a) Longitudinal joints must be... class DOT-110A tanks. Welding procedures, welders and fabricators must be approved in accordance...

  20. 49 CFR 179.200-10 - Welding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Welding. 179.200-10 Section 179.200-10... Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.200-10 Welding. (a) All joints... W (IBR, see § 171.7 of this subchapter). Welding procedures, welders and fabricators shall...

  1. 49 CFR 179.200-10 - Welding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Welding. 179.200-10 Section 179.200-10...-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.200-10 Welding. (a) All joints shall be fusion... § 171.7 of this subchapter). Welding procedures, welders and fabricators shall be approved. (b)...

  2. 49 CFR 179.300-9 - Welding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Welding. 179.300-9 Section 179.300-9...-Unit Tank Car Tanks (Classes DOT-106A and 110AW) § 179.300-9 Welding. (a) Longitudinal joints must be... class DOT-110A tanks. Welding procedures, welders and fabricators must be approved in accordance...

  3. 49 CFR 179.220-10 - Welding.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Welding. 179.220-10 Section 179.220-10...-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.220-10 Welding. (a) All joints must be fusion... subchapter). Welding procedures, welders, and fabricators shall be approved. (b) Radioscopy of the...

  4. 49 CFR 179.200-10 - Welding.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Welding. 179.200-10 Section 179.200-10...-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.200-10 Welding. (a) All joints shall be fusion... § 171.7 of this subchapter). Welding procedures, welders and fabricators shall be approved. (b)...

  5. 49 CFR 179.100-9 - Welding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Welding. 179.100-9 Section 179.100-9... Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120) § 179.100-9 Welding. (a) All joints shall be..., see § 171.7 of this subchapter). Welding procedures, welders and fabricators shall be approved. (b)...

  6. 49 CFR 179.300-9 - Welding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Welding. 179.300-9 Section 179.300-9...-Unit Tank Car Tanks (Classes DOT-106A and 110AW) § 179.300-9 Welding. (a) Longitudinal joints must be... class DOT-110A tanks. Welding procedures, welders and fabricators must be approved in accordance...

  7. 49 CFR 179.220-10 - Welding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Welding. 179.220-10 Section 179.220-10... Specifications for Non-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.220-10 Welding. (a) All joints... of this subchapter). Welding procedures, welders, and fabricators shall be approved. (b)...

  8. 49 CFR 179.220-10 - Welding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Welding. 179.220-10 Section 179.220-10...-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.220-10 Welding. (a) All joints must be fusion... subchapter). Welding procedures, welders, and fabricators shall be approved. (b) Radioscopy of the...

  9. 49 CFR 179.200-10 - Welding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Welding. 179.200-10 Section 179.200-10...-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.200-10 Welding. (a) All joints shall be fusion... § 171.7 of this subchapter). Welding procedures, welders and fabricators shall be approved. (b)...

  10. 49 CFR 179.220-10 - Welding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Welding. 179.220-10 Section 179.220-10...-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.220-10 Welding. (a) All joints must be fusion... subchapter). Welding procedures, welders, and fabricators shall be approved. (b) Radioscopy of the...

  11. 49 CFR 179.100-9 - Welding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Welding. 179.100-9 Section 179.100-9... Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120) § 179.100-9 Welding. (a) All joints shall be..., see § 171.7 of this subchapter). Welding procedures, welders and fabricators shall be approved. (b)...

  12. 49 CFR 179.200-10 - Welding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Welding. 179.200-10 Section 179.200-10...-Pressure Tank Car Tanks (Classes DOT-111AW and 115AW) § 179.200-10 Welding. (a) All joints shall be fusion... § 171.7 of this subchapter). Welding procedures, welders and fabricators shall be approved. (b)...

  13. 49 CFR 179.100-9 - Welding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Welding. 179.100-9 Section 179.100-9... Tank Car Tanks (Classes DOT-105, 109, 112, 114 and 120) § 179.100-9 Welding. (a) All joints shall be..., see § 171.7 of this subchapter). Welding procedures, welders and fabricators shall be approved. (b)...

  14. Seam tracking performance of a Coaxial Weld Vision System and pulsed welding

    NASA Technical Reports Server (NTRS)

    Gangl, K. J.; Weeks, J. L.; Todd, D.

    1986-01-01

    This report describes a continuation of a series of tests on the Coaxial Weld Vision System at MSFC. The ability of the system to compensate for transients associated with pulsed current welding is analyzed. Using the standard image processing approach for root pass seam tracking, the system is also tested for the ability to track the toe of a previous weld bead, for tracking multiple pass weld joints. This Coaxial Weld Vision System was developed by the Ohio State University (OSU) Center for Welding Research and is a part of the Space Shuttle Main Engine Robotic Welding Development System at MSFC.

  15. The methods of detection and the analysis of welded and brazed joint defects emerging during ITER components manufacturing

    NASA Astrophysics Data System (ADS)

    Gurieva, T. M.; Pronyakin, V. T.

    1996-10-01

    The nondestructive testing (NDT) methods to test materials and welds in the bearing structures of a superconducting magnet system, vacuum vessel and divertor are described. The experimental results are presented on estimating the efficiency of different NDT methods to identify the type and to assess the size of defects in mock-ups and components manufactured by applying the technologies to be used for the commercial production of the real ITER systems. The results are given on detecting and assessing actual defect-like cracks, sagging and edge displacement in the titanium cylindrical jacket during the commercial manufacture of the experimental conductor samples. The analysis of the results allows the conclusion to be made on a comparative efficiency of different NDT methods for the detection of defects arising during ITER component manufacture.

  16. The influence of laser welding parameters on the microstructure and mechanical property of the as-jointed NiTi alloy wires

    E-print Network

    Zheng, Yufeng

    The influence of laser welding parameters on the microstructure and mechanical property of the as September 2007; accepted 27 November 2007 Available online 4 December 2007 Abstract The Nd:YAG laser welding.%Ni) which had the same diameter of 1 mm. The wires were welded with different parameters, including impulse

  17. Friction Stir Spot Welding of DP780 Carbon Steel

    SciTech Connect

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

    2010-01-01

    Friction stir spot welds were made in uncoated and galvannealed DP780 sheets using polycrystalline boron nitride stir tools. The tools were plunged at either a single continuous rate or in two segments consisting of a relatively high rate followed by a slower rate of shorter depth. Welding times ranged from 1 to 10 s. Increasing tool rotation speed from 800 to 1600 rev min{sup -1} increased strength values. The 2-segment welding procedures also produced higher strength joints. Average lap shear strengths exceeding 10 {center_dot} 3 kN were consistently obtained in 4 s on both the uncoated and the galvannealed DP780. The likelihood of diffusion and mechanical interlocking contributing to bond formation was supported by metallographic examinations. A cost analysis based on spot welding in automobile assembly showed that for friction stir spot welding to be economically competitive with resistance spot welding the cost of stir tools must approach that of resistance spot welding electrode tips.

  18. Aircraft and ground vehicle friction correlation test results obtained under winter runway conditions during joint FAA/NASA Runway Friction Program

    NASA Technical Reports Server (NTRS)

    Yager, Thomas J.; Vogler, William A.; Baldasare, Paul

    1988-01-01

    Aircraft and ground vehicle friction data collected during the Joint FAA/NASA Runway Friction Program under winter runway conditions are discussed and test results are summarized. The relationship between the different ground vehicle friction measurements obtained on compacted snow- and ice-covered conditions is defined together with the correlation to aircraft tire friction performance under similar runway conditions.

  19. Polyimide adhesives for weld-bonding titanium

    NASA Technical Reports Server (NTRS)

    Vaughan, R. W.; Sheppard, C. H.; Baucom, R.

    1976-01-01

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

  20. Evaluation of Microstructure and Mechanical Properties in Dissimilar Austenitic/Super Duplex Stainless Steel Joint

    NASA Astrophysics Data System (ADS)

    Rahmani, Mehdi; Eghlimi, Abbas; Shamanian, Morteza

    2014-10-01

    To study the effect of chemical composition on microstructural features and mechanical properties of dissimilar joints between super duplex and austenitic stainless steels, welding was attempted by gas tungsten arc welding process with a super duplex (ER2594) and an austenitic (ER309LMo) stainless steel filler metal. While the austenitic weld metal had vermicular delta ferrite within austenitic matrix, super duplex stainless steel was mainly comprised of allotriomorphic grain boundary and Widmanstätten side plate austenite morphologies in the ferrite matrix. Also the heat-affected zone of austenitic base metal comprised of large austenite grains with little amounts of ferrite, whereas a coarse-grained ferritic region was observed in the heat-affected zone of super duplex base metal. Although both welded joints showed acceptable mechanical properties, the hardness and impact strength of the weld metal produced using super duplex filler metal were found to be better than that obtained by austenitic filler metal.

  1. Experimental Investigation into the Effects of Weld Sequence and Fixture on Residual Stresses in Arc Welding Process

    NASA Astrophysics Data System (ADS)

    Kohandehghan, A. R.; Serajzadeh, S.

    2012-06-01

    This study concentrates on the effects of weld sequence and welding fixtures on distribution and magnitude of induced arc welding residual stresses built up in butt-joint of Gas Tungsten Arc Welding (GTAW) AA5251 plates. Aluminum plates have been welded under different welding conditions and then, longitudinal and transverse residual stresses were measured in different points of the welded plates employing hole-drilling technique. The results indicate that welding sequence significantly alters the distributions of both longitudinal and transverse residual stresses while the changing in the weld sequence leads to 44% decrease in longitudinal residual stress. Besides, both the geometry of weld pool and distribution of residual stresses are affected by the welding fixtures while implementation of fixture causes about 21 and 76% reductions in the depth of weld pool and transverse residual stress, respectively, for the material and welding conditions used in this research.

  2. Laser welding of bone: Successful in vitro experiments

    SciTech Connect

    Mourant, J.R.; Anderson, G.D.; Bigio, I.J.; Johnson, T.M.

    1994-02-01

    A method for ``welding`` bones is being developed. Tensile joint strengths of chicken bones welded in vitro have exceeded one kilogram. Welding was performed with either a Nd:YAG (1064 nm) or a diode laser (820 nm). Light was delivered with an optical fiber held a few millimeters from the bone surface. A solder was developed to assist in the welding process.

  3. Welding arc plasma physics

    NASA Technical Reports Server (NTRS)

    Cain, Bruce L.

    1990-01-01

    The problems of weld quality control and weld process dependability continue to be relevant issues in modern metal welding technology. These become especially important for NASA missions which may require the assembly or repair of larger orbiting platforms using automatic welding techniques. To extend present welding technologies for such applications, NASA/MSFC's Materials and Processes Lab is developing physical models of the arc welding process with the goal of providing both a basis for improved design of weld control systems, and a better understanding of how arc welding variables influence final weld properties. The physics of the plasma arc discharge is reasonably well established in terms of transport processes occurring in the arc column itself, although recourse to sophisticated numerical treatments is normally required to obtain quantitative results. Unfortunately the rigor of these numerical computations often obscures the physics of the underlying model due to its inherent complexity. In contrast, this work has focused on a relatively simple physical model of the arc discharge to describe the gross features observed in welding arcs. Emphasis was placed of deriving analytic expressions for the voltage along the arc axis as a function of known or measurable arc parameters. The model retains the essential physics for a straight polarity, diffusion dominated free burning arc in argon, with major simplifications of collisionless sheaths and simple energy balances at the electrodes.

  4. Improved microstructure and mechanical properties in gas tungsten arc welded aluminum joints by using graphene nanosheets/aluminum composite filler wires.

    PubMed

    Fattahi, M; Gholami, A R; Eynalvandpour, A; Ahmadi, E; Fattahi, Y; Akhavan, S

    2014-09-01

    In the present study, different amounts of graphene nanosheets (GNSs) were added to the 4043 aluminum alloy powders by using the mechanical alloying method to produce the composite filler wires. With each of the produced composite filler wires, one all-weld metal coupon was welded using the gas tungsten arc (GTA) welding process. The microstructure, mechanical properties and fracture surface morphology of the weld metals have been evaluated and the results are compared. As the amount of GNSs in the composition of filler wire is increased, the microstructure of weld metal was changed from the dendritic structure to fine equiaxed grains. Furthermore, the tensile strength and microhardness of weld metal was improved, and is attributed to the augmented nucleation and retarded growth. From the results, it was seen that the GNSs/Al composite filler wire can be used to improve the microstructure and mechanical properties of GTA weld metals of aluminum and its alloys. PMID:24981209

  5. Laser transmission welding of ABS: Effect of CNTs concentration and process parameters on material integrity and weld formation

    NASA Astrophysics Data System (ADS)

    Rodríguez-Vidal, E.; Quintana, I.; Gadea, C.

    2014-04-01

    This paper reports a study of the laser transmission welding of polymeric joints composed by two ABS (acrylonitrile/butadiene/styrene) sheets, one transparent (natural ABS) and the other absorbent (filled by different percentages of carbon nanotubes (CNTs)). The objective of this work is to analyze the effect of process parameters and CNTs concentrations on weld formation and mechanical resistance of the weld joints.

  6. Welding in Space Workshop

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.

    1990-01-01

    The potential was discussed for welding in space, its advantages and disadvantages, and what type of programs can benefit from the capability. Review of the various presentations and comments made in the course of the workshop suggests several routes to obtaining a better understanding of how welding processes can be used in NASA's initiatives in space. They are as follows: (1) development of a document identifying well processes and equipment requirements applicable to space and lunar environments; (2) more demonstrations of welding particular hardware which are to be used in the above environments, especially for space repair operations; (3) increased awareness among contractors responsible for building space equipment as to the potential for welding operations in space and on other planetary bodies; and (4) continuation of space welding research projects is important to maintain awareness within NASA that welding in space is viable and beneficial.

  7. Oil-Ash Corrosion Resistance of Dissimilar T22/T91 Welded Joint of Super Heater Tubes

    NASA Astrophysics Data System (ADS)

    Mittal, Rutash; Sidhu, Buta Singh

    2015-02-01

    The studies on the high temperature corrosion of the dissimilar metal weldment are necessary for longer service of the weldments in corrosive medium. This paper reports the performance of microstructurally different regions, namely heat-affected zone (HAZ), weld metal (WM), and base metal (BM) of dissimilar metal weldment of T22/T91 in the molten salt (Na2SO4-60%V2O5) environment under cyclic studies. The T22 HAZ, WM, and T91 HAZ were observed to oxidize at higher rates and develop more scale thickness than other regions in the weldment. Microstructures and elemental analysis indicate lesser availability of Cr in T22 HAZ and T91 HAZ due to formation of Cr-rich phases, which ultimately causes the difference in oxidation behavior of different regions. The presence of chromium carbides and intermetallics in un-oxidized T22 HAZ region and martensitic structure with the presence of delta ferrites in un-oxidized T91 HAZ region was observed to be the major cause behind the weak corrosion resistance of the respective HAZs. The higher oxidation rate of T22 HAZ may be attributed to the absence of protective scale of Cr2O3 and presence of Fe3O4 phases. Similarly higher oxidation rate of T91 HAZ region can be attributed to lesser availability of Cr due to the propensity of development of delta ferrite in martensitic structure.

  8. Potential industrial application of laser welding with wire feed

    SciTech Connect

    Sun, Z.; Moisio, T.

    1996-12-31

    Laser welding with wire feed is a relative new technique which can widen the application of autogenous welding (without filler) in addition to retaining the many advantages of laser welding. The advantages of the technique compared with autogenous laser welding include the possibilities of modifying fusion zone chemistry, lessening joint fit-up requirement, and enhancing thick section welding with multipasses. This technique is particularly applicable to dissimilar metal welding due to the reduced mismatches of the base metals by the use of suitable filler material. Therefore, the technique has recently received more attention and is being evaluated for some industrial applications. In this paper, a case study is presented to illustrate the potential of the technique. Austenitic/ferritic dissimilar steel joints were laser welded with nickel-base filler wire. Although the philosophy of using nickel-base filler in this type of joints has been an established practice for conventional welding processes, its suitability in laser welding requires further investigation. Evaluation of the joints indicates that they possess improved weld quality as compared to autogenous laser welded joints. Some special advantages over conventional welding processes such as smaller heat-affected zone (HAZ), less distortion and lower residual stresses have also been demonstrated. It can be seen that this type of laser welded joints has potential future applications for several industrial sectors.

  9. Weld peaking on heavy aluminum structures

    NASA Technical Reports Server (NTRS)

    Bayless, E.; Poorman, R.; Sexton, J.

    1978-01-01

    Weld peaking is usually undesirable in any welded structure. In heavy structures, the forces involved in the welding process become very large and difficult to handle. With the shuttle's solid rocket booster, the weld peaking resulted in two major problems: (1) reduced mechanical properties across the weld joint, and (2) fit-up difficulties in subsequent assembly operation. Peaking from the weld shrinkage forces can be fairly well predicted in simple structures; however, in welding complicated assemblies, the amount of peaking is unpredictable because of unknown stresses from machining and forming, stresses induced by the fixturing, and stresses from welds in other parts of the assembly. When excessive peaking is encountered, it can be corrected using the shrinkage forces resulting from the welding process. Application of these forces is discussed in this report.

  10. Weld width indicates weld strength

    NASA Technical Reports Server (NTRS)

    Nunes, A. C. J.; Novak, H. L.; Mcllwain, M. C.

    1982-01-01

    Width of butt weld in 2219-T87 aluminum has been found to be more reliable indicator of weld strength than more traditional parameters of power input and cooling rate. Yield stress and ultimate tensile strength tend to decrease with weld size. This conclusion supports view of many professional welders who give priority to weld geometry over welding energy or cooling rate as indicator of weld quality.

  11. Wire-Guide Manipulator For Automated Welding

    NASA Technical Reports Server (NTRS)

    Morris, Tim; White, Kevin; Gordon, Steve; Emerich, Dave; Richardson, Dave; Faulkner, Mike; Stafford, Dave; Mccutcheon, Kim; Neal, Ken; Milly, Pete

    1994-01-01

    Compact motor drive positions guide for welding filler wire. Drive part of automated wire feeder in partly or fully automated welding system. Drive unit contains three parallel subunits. Rotations of lead screws in three subunits coordinated to obtain desired motions in three degrees of freedom. Suitable for both variable-polarity plasma arc welding and gas/tungsten arc welding.

  12. 46 CFR 154.650 - Cargo tank and process pressure vessel welding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... the quality assurance measures, weld procedure qualification, design details, materials, construction... following: (1) Each welded joint of the shells must be a full penetration butt weld, except dome to shell connections may have full penetration tee welds. (2) Each nozzle weld must be of the full penetration...

  13. 46 CFR 154.650 - Cargo tank and process pressure vessel welding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... the quality assurance measures, weld procedure qualification, design details, materials, construction... following: (1) Each welded joint of the shells must be a full penetration butt weld, except dome to shell connections may have full penetration tee welds. (2) Each nozzle weld must be of the full penetration...

  14. 46 CFR 154.650 - Cargo tank and process pressure vessel welding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... the quality assurance measures, weld procedure qualification, design details, materials, construction... following: (1) Each welded joint of the shells must be a full penetration butt weld, except dome to shell connections may have full penetration tee welds. (2) Each nozzle weld must be of the full penetration...

  15. 46 CFR 154.650 - Cargo tank and process pressure vessel welding.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... the quality assurance measures, weld procedure qualification, design details, materials, construction... following: (1) Each welded joint of the shells must be a full penetration butt weld, except dome to shell connections may have full penetration tee welds. (2) Each nozzle weld must be of the full penetration...

  16. Verifying root fusion in electron-beam welds

    NASA Technical Reports Server (NTRS)

    Becker, F. L.; Doctor, S.; Kleint, R. E.

    1980-01-01

    Ultrasonic equipment and x-y recorder indicate where back side of joint is properly welded. Wire waveguide placed in groove at root of joint to be welded is fused when joint is adequately penetrated. Ultransonic signal moving down waveguide is reflected where guide is melted. Change in reflected-signal arrival time with change in weld-head position is nearly constant unless joint is incompletely penetrated. Method permits determination of penetration depth in preweld samples without opening vacuum chamber and sectioning weld. Technique is particularly valuable when back side of joint is inaccessible.

  17. Mössbauer characterization of joints of steel pieces in transient liquid phase bonding experiences

    NASA Astrophysics Data System (ADS)

    di Luozzo, N.; Martínez Stenger, P. F.; Canal, J. P.; Fontana, M. R.; Arcondo, B.

    2011-11-01

    Joining of seamless, low carbon, steel tubes were performed by means of Transient Liquid Phase Bonding process employing a foil of Fe-Si-B metallic glass as filler material. The influence of the main parameters of the process was evaluated: temperature, holding time, pressure and post weld heat treatment. Powder samples were obtained from the joint of tubes and characterized employing Mössbauer Spectroscopy in transmission geometry. The sampling was performed both in tubes successfully welded and in those which show joint defects. The results obtained are correlated with the obtained microstructure and the diffusion of Si and B during the process.

  18. Fatique Resistant, Energy Efficient Welding Program, Final Technical Report

    SciTech Connect

    Egland, Keith; Ludewig, Howard

    2006-05-25

    The program scope was to affect the heat input and the resultant weld bead geometry by synchronizing robotic weave cycles with desired pulsed waveform shapes to develop process parameters relationships and optimized pulsed gas metal arc welding processes for welding fatique-critical structures of steel, high strength steel, and aluminum. Quality would be addressed by developing intelligent methods of weld measurement that accurately predict weld bead geometry from process information. This program was severely underfunded, and eventually terminated. The scope was redirected to investigate tandem narrow groove welding of steel butt joints during the one year of partial funding. A torch was designed and configured to perform a design of experiments of steel butt weld joints that validated the feasability of the process. An initial cost model estimated a 60% cost savings over conventional groove welding by eliminating the joint preparation and reducing the weld volume needed.

  19. Spot-Welding Gun With Adjustable Pneumatic Spring

    NASA Technical Reports Server (NTRS)

    Burley, Richard K.

    1990-01-01

    Proposed spot-welding gun equipped with pneumatic spring, which could be bellows or piston and cylinder, exerts force independent of position along stroke. Applies accurate controlled force to joint welded, without precise positioning at critical position within stroke.

  20. Welding of titanium alloy by Disk laser

    NASA Astrophysics Data System (ADS)

    Lisiecki, Aleksander

    2013-01-01

    The following article describes results of investigations on influence of laser welding parameters on the weld shape, quality and mechanical properties of 2.0 mm thick butt joints of titanium alloy Ti6Al4V (Grade 5 according to ASTM B265) welded with a new generation disk laser TRUMPF TRUDISK 3302, emitting at 1030 nm, with maximum output power 3300 W at circular laser beam spot, characterized by laser beam divergence 8.0 mm•mrad. The test butt joints of Ti6Al4V titanium alloy sheets were prepared as single square groove (I-type joint) and one-side laser welded without an additional material, at a flat position, using a specially designed system for shielding gas (purity 99.999%). The investigations at the initial stage were focused on detailed analysis of influence of the basic laser welding parameters such as laser power and welding speed on the shape and quality of single bead produced during bead-on-plate welding. Then the optimal parameters were chosen for laser welding of 2.0 mm thick butt joints of the titanium alloy Ti6Al4V. Edges of the titanium alloy sheets were melted in argon atmosphere by the laser beam focused on the top surface of butt joints. The test welded joints were investigated by visual inspection, metallographic examinations, hardness and micro-hardness measurements and mechanical tests such as tensile tests and bending tests. It was found that the welding mode is a keyhole welding and providing high quality of joints requires a special techniques and conditions of laser welding, as well as special gas shielding nozzles is required.

  1. Residual Stresses and Tensile Properties of Friction Stir Welded AZ31B-H24 Magnesium Alloy in Lap Configuration

    NASA Astrophysics Data System (ADS)

    Naik, Bhukya Srinivasa; Cao, Xinjin; Wanjara, Priti; Friedman, Jacob; Chen, Daolun

    2015-08-01

    AZ31B-H24 Mg alloy sheets with a thickness of 2 mm were friction stir welded in lap configuration using two tool rotational rates of 1000 and 1500 rpm and two welding speeds of 10 and 20 mm/s. The residual stresses in the longitudinal and transverse directions of the weldments were determined using X-ray diffraction. The shear tensile behavior of the lap joints was evaluated at low [233 K (-40 °C)], room [298 K (25 °C)], and elevated [453 K (180 °C)] temperatures. The failure load was highest for the lower heat input condition that was obtained at a tool rotational rate of 1000 rpm and a welding speed of 20 mm/s for all the test temperatures, due to the smaller hooking height, larger effective sheet thickness, and lower tensile residual stresses, as compared to the other two welding conditions that were conducted at a higher tool rotational rate or lower welding speed. The lap joints usually fractured on the advancing side of the top sheet near the interface between the thermo-mechanically affected zone and the stir zone. Elevated temperature testing of the weld assembled at a tool rotational rate of 1000 rpm and a welding speed of 20 mm/s led to the failure along the sheet interface in shear fracture mode due to the high integrity of the joint that exhibited large plastic deformation and higher total energy absorption.

  2. Welding IV.

    ERIC Educational Resources Information Center

    Allegheny County Community Coll., Pittsburgh, PA.

    Instructional objectives and performance requirements are outlined in this course guide for Welding IV, a competency-based course in advanced arc welding offered at the Community College of Allegheny County to provide students with proficiency in: (1) single vee groove welding using code specifications established by the American Welding Society…

  3. Welding Curriculum.

    ERIC Educational Resources Information Center

    Alaska State Dept. of Education, Juneau. Div. of Adult and Vocational Education.

    This competency-based curriculum guide is a handbook for the development of welding trade programs. Based on a survey of Alaskan welding employers, it includes all competencies a student should acquire in such a welding program. The handbook stresses the importance of understanding the principles associated with the various elements of welding.…

  4. Role of the micro/macro structure of welds in crack nucleation and propagation in aerospace aluminum-lithium alloy

    NASA Technical Reports Server (NTRS)

    Talia, George E.

    1996-01-01

    Al-Li alloys offer the benefits of increased strength, elastic modulus and lower densities as compared to conventional aluminum alloys. Martin Marietta Laboratories has developed an Al-Li alloy designated 2195 which is designated for use in the cryogenic tanks of the space shuttle. The Variable Polarity Plasma Arc (VPPA) welding process is currently being used to produce these welds [1]. VPPA welding utilizes high temperature ionized gas (plasma) to transfer heat to the workpiece. An inert gas, such as Helium, is used to shield the active welding zone to prevent contamination of the molten base metal with surrounding reactive atmospheric gases. [1] In the Space Shuttle application, two passes of the arc are used to complete a butt-type weld. The pressure of the plasma stream is increased during the first pass to force the arc entirely through the material, a practice commonly referred to as keyholing. Molten metal forms on either side of the arc and surface tension draws this liquid together as the arc passes. 2319 Al alloy filler material may also be fed into the weld zone during this pass. During the second pass, the plasma stream pressure is reduced such that only partial penetration of the base material is obtained. Al 2319 filler material is added during this pass to yield a uniform, fully filled welded joint. This additional pass also acts to alter the grain structure of the weld zone to yield a higher strength joint.

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

    PubMed

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

    2012-06-01

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

  6. 49 CFR 213.119 - Continuous welded rail (CWR); plan contents.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... installation after October 21, 2009, the track owner shall either, within 60 days— (i) Weld the joint; (ii... present, the track owner shall either— (i) Weld the joint; (ii) Replace the broken bar(s), replace the broken bolts, adjust the anchors and, within 30 days, weld the joint; (iii) Replace the broken...

  7. Diode laser welding of aluminum to steel

    SciTech Connect

    Santo, Loredana; Quadrini, Fabrizio; Trovalusci, Federica

    2011-05-04

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

  8. Diode laser welding of aluminum to steel

    NASA Astrophysics Data System (ADS)

    Santo, Loredana; Quadrini, Fabrizio; Trovalusci, Federica

    2011-05-01

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

  9. Inert-Gas Diffuser For Plasma Or Arc Welding

    NASA Technical Reports Server (NTRS)

    Gilbert, Jeffrey L.; Spencer, Carl N.; Hosking, Timothy J.

    1994-01-01

    Inert-gas diffuser provides protective gas cover for weld bead as it cools. Follows welding torch, maintaining continuous flow of argon over newly formed joint and prevents it from oxidizing. Helps to ensure welds of consistently high quality. Devised for plasma arc keyhole welding of plates of 0.25-in. or greater thickness, also used in tungsten/inert-gas and other plasma or arc welding processes.

  10. Welding, Bonding and Fastening, 1984

    NASA Technical Reports Server (NTRS)

    Buckley, J. D. (editor); Stein, B. A. (editor)

    1985-01-01

    A compilation of papers presented in a joint NASA, American Society for Metals, The George Washington University, American Welding Soceity, and Society of Manufacturing Engineers conference on Welding, Bonding, and Fastening at Langley Research Center, Hampton, VA, on October 23 to 25, 1984 is given. Papers were presented on technology developed in current research programs relevant to welding, bonding, and fastening of structural materials required in fabricating structures and mechanical systems used in the aerospace, hydrospace, and automotive industries. Topics covered in the conference included equipment, hardware and materials used when welding, brazing, and soldering, mechanical fastening, explosive welding, use of unique selected joining techniques, adhesives bonding, and nondestructive evaluation. A concept of the factory of the future was presented, followed by advanced welding techniques, automated equipment for welding, welding in a cryogenic atmosphere, blind fastening, stress corrosion resistant fasteners, fastening equipment, explosive welding of different configurations and materials, solid-state bonding, electron beam welding, new adhesives, effects of cryogenics on adhesives, and new techniques and equipment for adhesive bonding.

  11. Weld-brazing of titanium

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

    A joining process, designated weld-brazing, which combines resistance spotwelding and brazing has been developed at the NASA Langley Research Center. Resistance spot-welding is employed to position and align the parts and to establish a suitable faying surface gap for brazing; it contributes to the integrity of the joint. Brazing enhances the properties of the joint and reduces the stress concentrations normally associated with spotwelds. Ti-6Al-4V titanium alloy joints have been fabricated using 3003 aluminum braze both in a vacuum furnace and in a retort containing an inert gas environment.

  12. Laser Welding and Syncristallization Techniques Comparison: In Vitro Study

    PubMed Central

    Fornaini, C.; Merigo, E.; Vescovi, P.; Meleti, M.; Nammour, S.

    2012-01-01

    Background. Laser welding was first reported in 1967 and for many years it has been used in dental laboratories with several advantages versus the conventional technique. Authors described, in previous works, the possibility of using also chair-side Nd?:?YAG laser device (Fotona Fidelis III, ? = 1064?nm) for welding metallic parts of prosthetic appliances directly in the dental office, extra- and also intra-orally. Syncristallisation is a soldering technique based on the creation of an electric arc between two electrodes and used to connect implants to bars intra-orally. Aim. The aim of this study was to compare two different laser welding devices with a soldering machine, all of these used in prosthetic dentistry. Material and Methods. In-lab Nd?:?YAG laser welding (group A = 12 samples), chair-side Nd?:?YAG laser welding (group B = 12 samples), and electrowelder (group C = 12 samples) were used. The tests were performed on 36 CrCoMo plates and the analysis consisted in evaluation, by microscopic observation, of the number of fissures in welded areas of groups A and B and in measurement of the welding strength in all the groups. The results were statistically analysed by means of one-way ANOVA and Tukey-Kramer multiple comparison tests. Results. The means and standard deviations for the number of fissures in welded areas were 8.12 ± 2.59 for group A and 5.20 ± 1.38 for group B. The difference was statistical significant (P = 0.0023 at the level 95%). On the other hand, the means and standard deviations for the traction tests were 1185.50 ± 288.56?N for group A, 896.41 ± 120.84?N for group B, and 283.58 ± 84.98?N for group C. The difference was statistical significant (P = 0.01 at the level 95%). Conclusion. The joint obtained by welding devices had a significant higher strength compared with that obtained by the electrowelder, and the comparison between the two laser devices used demonstrated that the chair-side Nd?:?YAG, even giving a lower strength to the joints, produced the lowest number of fissures in the welded area. PMID:22778737

  13. Laser welding and syncristallization techniques comparison: in vitro study.

    PubMed

    Fornaini, C; Merigo, E; Vescovi, P; Meleti, M; Nammour, S

    2012-01-01

    Background. Laser welding was first reported in 1967 and for many years it has been used in dental laboratories with several advantages versus the conventional technique. Authors described, in previous works, the possibility of using also chair-side Nd?:?YAG laser device (Fotona Fidelis III, ? = 1064?nm) for welding metallic parts of prosthetic appliances directly in the dental office, extra- and also intra-orally. Syncristallisation is a soldering technique based on the creation of an electric arc between two electrodes and used to connect implants to bars intra-orally. Aim. The aim of this study was to compare two different laser welding devices with a soldering machine, all of these used in prosthetic dentistry. Material and Methods. In-lab Nd?:?YAG laser welding (group A = 12 samples), chair-side Nd?:?YAG laser welding (group B = 12 samples), and electrowelder (group C = 12 samples) were used. The tests were performed on 36 CrCoMo plates and the analysis consisted in evaluation, by microscopic observation, of the number of fissures in welded areas of groups A and B and in measurement of the welding strength in all the groups. The results were statistically analysed by means of one-way ANOVA and Tukey-Kramer multiple comparison tests. Results. The means and standard deviations for the number of fissures in welded areas were 8.12 ± 2.59 for group A and 5.20 ± 1.38 for group B. The difference was statistical significant (P = 0.0023 at the level 95%). On the other hand, the means and standard deviations for the traction tests were 1185.50 ± 288.56?N for group A, 896.41 ± 120.84?N for group B, and 283.58 ± 84.98?N for group C. The difference was statistical significant (P = 0.01 at the level 95%). Conclusion. The joint obtained by welding devices had a significant higher strength compared with that obtained by the electrowelder, and the comparison between the two laser devices used demonstrated that the chair-side Nd?:?YAG, even giving a lower strength to the joints, produced the lowest number of fissures in the welded area. PMID:22778737

  14. Experimental and Numerical Investigation of an Electromagnetic Weld Pool Control for Laser Beam Welding

    NASA Astrophysics Data System (ADS)

    Bachmann, M.; Avilov, V.; Gumenyuk, A.; Rethmeier, M.

    The objective of this study was to investigate the influence of externally applied magnetic fields on the weld quality in laser beam welding. The optimization of the process parameters was performed using the results of computer simulations. Welding tests were performed with up to 20 kW laser beam power. It was shown that the AC magnet with 3 kW power supply allows for a prevention of the gravity drop-out for full penetration welding of 20 mm thick stainless steel plates. For partial penetration welding it was shown that an0.5 T DC magnetic field is enough for a suppression of convective flows in the weld pool. Partial penetration welding tests with 4 kW beam power showed that the application of AC magnetic fields can reduce weld porosity by a factor of 10 compared to the reference joints. The weld surface roughness was improved by 50%.

  15. Laser Welding in Space

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.; Kaukler, William F.

    1989-01-01

    Solidification type welding process experiments in conditions of microgravity were performed. The role of convection in such phenomena was examined and convective effects in the small volumes obtained in the laser weld zone were observed. Heat transfer within the weld was affected by acceleration level as indicated by the resulting microstructure changes in low gravity. All experiments were performed such that both high and low gravity welds occurred along the same weld beam, allowing the effects of gravity alone to be examined. Results indicate that laser welding in a space environment is feasible and can be safely performed IVA or EVA. Development of the hardware to perform the experiment in a Hitchhiker-g platform is recomended as the next step. This experiment provides NASA with a capable technology for welding needs in space. The resources required to perform this experiment aboard a Shuttle Hitchhiker-pallet are assessed. Over the four year period 1991 to 1994, it is recommended that the task will require 13.6 manyears and $914,900. In addition to demonstrating the technology and ferreting out the problems encountered, it is suggested that NASA will also have a useful laser materials processing facility for working with both the scientific and the engineering aspects of materials processing in space. Several concepts are also included for long-term optimization of available solar power through solar pumping solid state lasers directly for welding power.

  16. Improvement of laser keyhole formation with the assistance of arc plasma in the hybrid welding process of magnesium alloy

    NASA Astrophysics Data System (ADS)

    Liu, Liming; Hao, Xinfeng

    2009-11-01

    In the previous work, low-power laser/arc hybrid welding technique is used to weld magnesium alloy and high-quality weld joints are obtained. In order to make clear the interactions between low-power laser pulse and arc plasma, the effect of arc plasma on laser pulse is studied in this article. The result shows that the penetration of low-power laser welding with the assistance of TIG arc is more than two times deeper than that of laser welding alone and laser welding transforms from thermal-conduction mode to keyhole mode. The plasma behaviors and spectra during the welding process are studied, and the transition mechanism of laser-welding mode is analyzed in detail. It is also found that with the assistance of arc plasma, the threshold value of average power density to form keyhole welding for YAG laser is only 3.3×10 4 W/cm 2, and the average peak power density is 2.6×10 5 W/cm 2 in the present experiment. Moreover, the distribution of energy density during laser pulse is modulated to improve the formation and stability of laser keyholes.

  17. Microstructural analysis of solar cell welds

    NASA Technical Reports Server (NTRS)

    Moore, T. J.; Watson, G. K.; Baraona, C. R.

    1982-01-01

    Parallel-gap resistance welding of silicon solar cells with copper interconnects results in complex microstructural variations that depend on the welding variables. At relatively low heat input solid-state welds are produced. At medium heat the Ag-Cu eutectic forms resulting in a braze joint. High heat produces a fusion weld with complete melting of the silver layer on the silicon solar cell. If the silicon is also melted, cracking occurs in the silicon cell below the weld nugget. These determinations were made using light microscopy, microprobe, and scanning electron microscopy analyses.

  18. Advances in welding science - a perspective

    SciTech Connect

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

    1995-02-01

    The ultimate goal of welding technology is to improve the joint integrity and increase productivity. Over the years, welding has been more of an art than a science, but in the last few decades major advances have taken place in welding science and technology. With the development of new methodologies at the crossroads of basic and applied sciences, enormous opportunities and potential exist to develop a science-based tailoring of composition, structure, and properties of welds with intelligent control and automation of the welding processes.

  19. Optimization of weld bead geometry in laser welding with filler wire process using Taguchi’s approach

    NASA Astrophysics Data System (ADS)

    dongxia, Yang; xiaoyan, Li; dingyong, He; zuoren, Nie; hui, Huang

    2012-10-01

    In the present work, laser welding with filler wire was successfully applied to joining a new-type Al-Mg alloy. Welding parameters of laser power, welding speed and wire feed rate were carefully selected with the objective of producing a weld joint with the minimum weld bead width and the fusion zone area. Taguchi approach was used as a statistical design of experimental technique for optimizing the selected welding parameters. From the experimental results, it is found that the effect of welding parameters on the welding quality decreased in the order of welding speed, wire feed rate, and laser power. The optimal combination of welding parameters is the laser power of 2.4 kW, welding speed of 3 m/min and the wire feed rate of 2 m/min. Verification experiments have also been conducted to validate the optimized parameters.

  20. Advanced Welding Concepts

    NASA Technical Reports Server (NTRS)

    Ding, Robert J.

    2010-01-01

    Four advanced welding techniques and their use in NASA are briefly reviewed in this poster presentation. The welding techniques reviewed are: Solid State Welding, Friction Stir Welding (FSW), Thermal Stir Welding (TSW) and Ultrasonic Stir Welding.

  1. Damage Tolerance Assessment of Friction Pull Plug Welds

    NASA Technical Reports Server (NTRS)

    McGill, Preston; Burkholder, Jonathan

    2012-01-01

    Friction stir welding is a solid state welding process developed and patented by The Welding Institute in Cambridge, England. Friction stir welding has been implemented in the aerospace industry in the fabrication of longitudinal welds in pressurized cryogenic propellant tanks. As the industry looks to implement friction stir welding in circumferential welds in pressurized cryogenic propellant tanks, techniques to close out the termination hole associated with retracting the pin tool are being evaluated. Friction pull plug welding is under development as a one means of closing out the termination hole. A friction pull plug weld placed in a friction stir weld results in a non-homogenous weld joint where the initial weld, plug weld, their respective heat affected zones and the base metal all interact. The welded joint is a composite, plastically deformed material system with a complex residual stress field. In order to address damage tolerance concerns associated with friction plug welds in safety critical structures, such as propellant tanks, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size in the test or service environments. Test data relating residual strength capability to flaw size in two aluminum alloy friction plug weld configurations is presented.

  2. Arc spot welding technique for underwater use

    SciTech Connect

    Koga, H.; Ide, Y.; Ogawa, Y.

    1995-12-31

    An arc spot welding equipment with special local cavity shroud was developed for underwater salvaging activity. Arc spot welding for lapped plates is an effective method to recover defects. This method in surface is so simple to use widely in the field of railways and chemical plants manufacturing. But there is some problems on the reliability of joint strength and bead shapes. A special arc spot nozzle to improve welding quality was developed. A small outlet of air jet at the bottom of the nozzle was created to maintain the swirl flow of shielding gas and certain rejection of excessive molten metal. This nozzle covers the welding part completely, then it also works as a local cavity shroud under water. This paper describes the design and function of the nozzle for CO{sub 2} arc spot welding system. A programmable controller manages the welding sequence of shielding gas flow, air jet flow, and arcing time. This welding gun is operated manually, but the operation is only to press the gun on the weld point. After that welding will proceed automatically, and arcing time is about three seconds. Whole time for welding which includes pre and post gas flow time is less than ten seconds for surface use, it is required some more additional pre drying process of welding point for underwater use to guarantee the high quality welding results. Fundamental analysis of welding conditions and the effects of air jet were considered.

  3. A Study on the Welding Characteristics of Tailor Welded Blank Metal Sheets Using GTAW and Laser Welding

    NASA Astrophysics Data System (ADS)

    Thasanaraphan, Pornsak

    In this study, a computational and experimental effort was carried out to qualitatively understand the weld pool shape, distortion and residual stress for continuous laser welding and manual pulsed gas metal arc welding. For all the welding simulations given in this dissertation, a welding specific finite element package, SYSWELD, is used. This research focuses on the welding behavior observed in light-weight metal structures known as the tailor-welded blanks, TWBs. They are a combination of two or more metal sheets with different thickness and/or different materials that are welded together in a single plane prior to forming, e.g., stamping. They made from the low carbon steel. As laser welding experiment results show, the weld pool shape at the top and bottom surface, is strongly influenced by surface tension, giving it a characteristic hourglass shape. In order to simulate the hourglass shape, a new volumetric heat source model was developed to predict the transient temperature profile and weld pool shape, including the effect of surface tension. Tailor welded blanks with different thicknesses were examined in the laser welding process. All major physical phenomena such as thermal conduction, heat radiation and convection heat losses are taken into account in the model development as well as temperature-dependant thermal and mechanical material properties. The model is validated for the case of butt joint welding of cold rolled steel sheets. The results of the numerical simulations provide temperature distributions representing the shape of the molten pool, distortion and residual stress with varying laser beam power and welding speed. It is demonstrated that the finite element simulation results are in good agreement with the experiment results. This includes the weld pool shape and sheet metal distortion. While there is no experimental data to compare directly with residual stress results, the distorted shape provides an indirect measure of the welding residual stresses. The welding details such as clamping, butt joint configuration, material, sample thickness are similar for both the laser welding process and the manual pulsed GTAW process. Also as same metallurgical investigation, the weld pool shape displays wider full penetration without the effect of surface tension. The double ellipsoid volumetric heat source is applied in the finite element simulation to determine the temperature distribution, distortion and residual stress. The simulation results are compared with the experimental results and show good agreement. In addition, the results from the laser welding process are compared to the equivalent results from the GTAW process in the order to better understand the fundamental differences between these two welding processes.

  4. Development of automated welding process for field fabrication of thick walled pressure vessels. Fourth quarter, FY 1980

    SciTech Connect

    Not Available

    1980-12-19

    Progress is reported in research on the automated welding of heavy steel plate for the fabrication of pressure vessels. Information is included on: torch and shield adaptation; mechanical control of the welding process; welding parameters; joint design; filler wire optimizaton; nondestructive testing of welds; and weld repair. (LCL)

  5. Solid-state and fusion resistance spot welding of TD-NiCr sheet

    NASA Technical Reports Server (NTRS)

    Moore, T. J.

    1973-01-01

    By using specially processed TD-NiCr sheet in both 0.4-mm (0.015-in.) and 1.6-mm (0.062-in.) thicknesses and carefully selected welding procedures, solid state resistance spot welds were produced which, after postheating at 1200 C, were indistinguishable from the parent material. Stress-rupture shear tests of single-spot lap joints in 0.4-mm (0.015-in.) thick sheet showed that these welds were as strong as the parent material. Similar results were obtained in tensile-shear tests at room temperature and 1100 C and in fatigue tests. Conventional fusion spot welds in commercial sheet were unsatisfactory because of poor stress-rupture shear properties resulting from metallurgical damage to the parent material.

  6. Welding Technician

    ERIC Educational Resources Information Center

    Smith, Ken

    2009-01-01

    About 95% of all manufactured goods in this country are welded or joined in some way. These welded products range in nature from bicycle handlebars and skyscrapers to bridges and race cars. The author discusses what students need to know about careers for welding technicians--wages, responsibilities, skills needed, career advancement…

  7. SmartWeld working session for the GTS4

    SciTech Connect

    Kleban, S.; Hicken, K.; Ng, R.; Fricke, B.

    1997-08-01

    Results from SmartWeld`s first working session involving in-progress designs is presented. The Welding Advisor component of SmartWeld was thoroughly exercised, evaluated all eleven welds of the selected part. The Welding Advisor is an expert system implemented with object-oriented techniques for knowledge representation. With two welding engineers in attendance, the recommendations of the Welding Advisor were thoroughly examined and critiqued for accuracy and for areas of improvement throughout the working session. The Weld Schedule Database component of SmartWeld was also exercised. It is a historical archive of proven, successful weld schedules that can be intelligently searched using the current context of SmartWeld`s problem solving state. On all eleven welds, the experts agreed that Welding Advisor recommended the most risk free options. As a result of the Advisor`s recommendation, six welds agreed completely with the experts, two welds had their joint geometry modified for production, and three welds were not modified but extra care was exercised during welding. 25 figs., 3 tabs.

  8. Identification of Damaged Spot Welds in a Complicated Joined Structure

    NASA Astrophysics Data System (ADS)

    Yunus, M. A.; Rani, M. N. Abdul; Ouyang, H.; Deng, H.; James, S.

    2011-07-01

    In automotive engineering, spot welds on assembled structures such as Body in White (BiW) have a significant effect on the vehicles' dynamic characteristics. Understandably, imperfections in the spot welds will cause variations in the dynamic properties such as natural frequencies and mode shapes of the structure. In this paper, a complicated welded structure which is a simplified Natural Gas Vehicle (NGV) platform is investigated. The structure fabricated from thin metal sheets consists of ten components. They are jointed together by a number of scattered spot welds. NASTRAN Solution 200 based on sensitivity analysis is used to identify the most sensitive parameters to natural frequencies. The numerical model of the undamaged structure is initially updated in order to minimise the discrepancies between the measured and numerical data using NASTRAN optimisation code. The initial updated model serves as a benchmark for the subsequent structural damage identification. The numerical data of the benchmark model is then compared with the measured data obtained from the damaged structure. The same updating procedure is applied to the benchmark model in order to bring the numerical data as close as possible to the measured data of the damaged structure. The disparity in certain parameter values from the parameter values used in the benchmark model shows a fault or damage in the location of a particular joint, depending on the severity of this disparity. The challenge in this work is to localise damaged area and quantify the damage of the complicated structure with multiple spot welds in the presence of uncertainty in the location and material properties of the welds.

  9. 46 CFR 59.10-30 - Seal welding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Seal welding. 59.10-30 Section 59.10-30 Shipping COAST... VESSELS AND APPURTENANCES Welding Repairs to Boilers and Pressure Vessels in -Service § 59.10-30 Seal welding. Where leaks occur in riveted joints or connections, they shall be carefully investigated...

  10. 46 CFR 59.10-30 - Seal welding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Seal welding. 59.10-30 Section 59.10-30 Shipping COAST... VESSELS AND APPURTENANCES Welding Repairs to Boilers and Pressure Vessels in -Service § 59.10-30 Seal welding. Where leaks occur in riveted joints or connections, they shall be carefully investigated...

  11. 46 CFR 59.10-30 - Seal welding.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Seal welding. 59.10-30 Section 59.10-30 Shipping COAST... VESSELS AND APPURTENANCES Welding Repairs to Boilers and Pressure Vessels in -Service § 59.10-30 Seal welding. Where leaks occur in riveted joints or connections, they shall be carefully investigated...

  12. 46 CFR 59.10-30 - Seal welding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Seal welding. 59.10-30 Section 59.10-30 Shipping COAST... VESSELS AND APPURTENANCES Welding Repairs to Boilers and Pressure Vessels in -Service § 59.10-30 Seal welding. Where leaks occur in riveted joints or connections, they shall be carefully investigated...

  13. 46 CFR 59.10-30 - Seal welding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Seal welding. 59.10-30 Section 59.10-30 Shipping COAST... VESSELS AND APPURTENANCES Welding Repairs to Boilers and Pressure Vessels in -Service § 59.10-30 Seal welding. Where leaks occur in riveted joints or connections, they shall be carefully investigated...

  14. Integration of NASA-sponsored studies on aluminum welding

    NASA Technical Reports Server (NTRS)

    Masubuchi, K.

    1972-01-01

    The results are presented of numerous studies relating to aluminum alloy welding. The subjects covered include: (1) effects of porosity on weld joint performance, (2) sources of porosity, (3) weld thermal effects, (4) residual stresses and distortion, and (5) manufacturing process system control.

  15. Noncontact Ultrasonic Vibration Of Weld Puddles

    NASA Technical Reports Server (NTRS)

    Gilbert, Jeffrey L.

    1990-01-01

    Proposed ultrasonic stimulator vibrates weld puddle without making contact. Vibration breaks up large grain clumps in solidifying puddle, creating more uniform, fine-grain microstructure. Resulting weld joint less susceptible to hot cracking and other stress-related forms of degradation.

  16. Determining Asymmetry Of A Weld Puddle

    NASA Technical Reports Server (NTRS)

    Gutow, David A.

    1992-01-01

    Sensing-and-data-processing subsystem provides information of asymmetry of weld puddle with respect to original midplane of joint. Shape of puddle inferred from surface-temperature distribution. Part of welding-control system which enables system to correct for asymmetry.

  17. Feasibility study on welding and cutting methods for thick plate in fusion reactor

    SciTech Connect

    Osaki, T.; Nakayama, Y.; Kobayashi, T.

    1995-12-31

    Application of tungsten-arc inert-gas (TIG) welding with narrow gap has been considered as a hopeful joint method to suppress post welding deformation for thick plates. The authors studied some parameters to predict the post-welding deformation for the narrow gap shape of TIG welding. As for cutting methods, the water jet method was applied for weld joints in this study. Reweld tests by using the TIG welding method were successfully performed under the condition of cutting surface as it was. Results of tensile tests for reweld joints showed no reduction in strength. This reveals a good prospect of providing reweld groove surface without any machining on site.

  18. Effect of Weld Tool Geometry on Friction Stir Welded AA2219-T87 Properties

    NASA Technical Reports Server (NTRS)

    Querin, Joseph A.; Schneider, Judy A.

    2008-01-01

    In this study, flat panels of AA2219-T87 were friction stir welded (FSWed) using weld tools with tapered pins The three pin geometries of the weld tools included: 0 (straight cylinder), 30 , and 60 angles on the frustum. For each weld tool geometry, the FSW process parameters were optimized to eliminate defects. A constant heat input was maintained while varying the process parameters of spindle rpm and travel speed. This provided a constant heat input for each FSW weld panel while altering the hot working conditions imparted to the workpiece. The resulting mechanical properties were evaluated from tensile test results of the FSW joint.

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

    SciTech Connect

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

    2011-01-17

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

  20. Study of a fiber laser assisted friction stir welding process

    NASA Astrophysics Data System (ADS)

    Casalino, G.; Campanelli, S.; Ludovico, A. D.; Contuzzi, N.; Angelastro, A.

    2012-03-01

    Friction stir welding is a relatively new joining technique. This technique, which is considered a derivative of the more common friction welding method, was developed mainly for aluminum and its alloys. In recent years, this method has been used to join various other alloys. FSW has many advantages, including the following: the welding procedure is relatively simple with no consumables or filler metal; joint edge preparation is not needed; oxide removal prior to welding is unnecessary; high joint strength has been achieved in aluminum and magnesium alloys; FSW can be used with alloys that cannot be fusion welded due to crack sensitivity. The drawbacks of FSW include the need for powerful fixtures to clamp the workpiece to the welding table, the high force needed to move the welding tool forward, the relatively high wear rate of the welding tool, and weld speeds in FSW are slower, which can lead to longer process times. To overcome these drawbacks, a fiber laser-assisted friction stir welding system was designed (FLAFSW). The system combined a conventional commercial friction machine and a fiber pumped laser system. The scope is to investigate the influence of the laser assistance on the weld quality. A number of different aluminum plates, which are still mentioned to be difficult to be joint as intermetallic phases appear during melting welding techniques, were used. The evaluation of quality was performed through analysis of appearance, mechanical and microstructure characterization of the weld.

  1. Historical overview on Vacuum suitable Welding and fatigue resistance in Research Devices

    E-print Network

    Wolf, Martin

    2015-01-01

    New inventions change the approach of vacuum suitable welding for research purpose. With orbital welding, laser welding and robot welding the possibilities increase to fabricate larger vessels more accurately. Despite this development there is still no perfect understanding on how to avoid virtual leaks and how to make such joints suitable for dynamic stress. By recalling its historical development, it is apparent how welding mistakes began occurring systematically and how to avoid them. With ASDEX-Upgrade as an example, it is shown how the attempt to conduct vacuum suitable welding has decreased the fatigue strength. ITER could repeat the mistakes of ASDEX-Upgrade even for unwanted welding (accidental fusing of joints).

  2. Effect of Repair Welding on Electrochemical Corrosion and Stress Corrosion Cracking Behavior of TIG Welded AA2219 Aluminum Alloy in 3.5 Wt Pct NaCl Solution

    NASA Astrophysics Data System (ADS)

    Venugopal, A.; Sreekumar, K.; Raja, V. S.

    2010-12-01

    The stress corrosion cracking (SCC) behavior of AA2219 aluminum alloy in the as-welded (AW) and repair-welded (RW) conditions was examined and compared with that of the base metal (BM) in 3.5 wt pct NaCl solution using the slow strain rate technique (SSRT). The reduction in ductility was used as a parameter to evaluate the SCC susceptibility of both BM and welded joints. The results show that the ductility ratio ( ? NaCl/( ? air)) of the BM was close to one (0.97) and reduced to 0.9 for the AW joint. This value further reduced to 0.77 after carrying out one repair welding operation. However, the RW specimen exhibited higher ductility than the single-weld specimens even in 3.5 wt pct NaCl solution. SSRT results obtained using pre-exposed samples followed by post-test metallographic observations clearly showed localized pitting corrosion along the partially melted zone (PMZ), signifying that the reduction in ductility ratio of both the AW and RW joints was more due to mechanical overload failure, caused by the localized corrosion and a consequent reduction in specimen thickness, than due to SCC. Also, the RW joint exhibited higher ductility than the AW joint both in air and the environment, although SCC index (SI) for the former is lower than that of the latter. Fractographic examination of the failed samples, in general, revealed a typical ductile cracking morphology for all the base and welded joints, indicating the good environmental cracking resistance of this alloy. Microstructural examination and polarization tests further demonstrate grain boundary melting along the PMZ, and that provided the necessary electrochemical condition for the preferential cracking on that zone of the weldment.

  3. Friction Stir Welding of Tapered Thickness Welds Using an Adjustable Pin Tool

    NASA Technical Reports Server (NTRS)

    Adams, Glynn; Venable, Richard; Lawless, Kirby

    2003-01-01

    Friction stir welding (FSW) can be used for joining weld lands that vary in thickness along the length of the weld. An adjustable pin tool mechanism can be used to accomplish this in a single-pass, full-penetration weld by providing for precise changes in the pin length relative to the shoulder face during the weld process. The difficulty with this approach is in accurately adjusting the pin length to provide a consistent penetration ligament throughout the weld. The weld technique, control system, and instrumentation must account for mechanical and thermal compliances of the tooling system to conduct tapered welds successfully. In this study, a combination of static and in-situ measurements, as well as active control, is used to locate the pin accurately and maintain the desired penetration ligament. Frictional forces at the pin/shoulder interface were a source of error that affected accurate pin position. A traditional FSW pin tool design that requires a lead angle was used to join butt weld configurations that included both constant thickness and tapered sections. The pitch axis of the tooling was fixed throughout the weld; therefore, the effective lead angle in the tapered sections was restricted to within the tolerances allowed by the pin tool design. The sensitivity of the FSW process to factors such as thickness offset, joint gap, centerline offset, and taper transition offset were also studied. The joint gap and the thickness offset demonstrated the most adverse affects on the weld quality. Two separate tooling configurations were used to conduct tapered thickness welds successfully. The weld configurations included sections in which the thickness decreased along the weld, as well as sections in which the thickness increased along the weld. The data presented here include weld metallography, strength data, and process load data.

  4. Weld geometry strength effect in 2219-T87 aluminum

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.; Novak, H. L.; Mcilwain, M. C.

    1981-01-01

    A theory of the effect of geometry on the mechanical properties of a butt weld joint is worked out based upon the soft interlayer weld model. Tensile tests of 45 TIG butt welds and 6 EB beads-on-plate in 1/4-in. 2219-T87 aluminum plate made under a wide range of heat sink and power input conditions are analyzed using this theory. The analysis indicates that purely geometrical effects dominate in determining variations in weld joint strength with heat sink and power input. Variations in weld dimensions with cooling rate are significant as well as with power input. Weld size is suggested as a better indicator of the condition of a weld joint than energy input.

  5. 3D reconstruction of bony elements of the knee joint and finite element analysis of total knee prosthesis obtained from the reconstructed model

    PubMed Central

    Djoudi, Farid

    2013-01-01

    Two separate themes are presented in this paper. Aims The first theme is to present a graphical modeling approach of human anatomical structures namely, the femur and the tibia. The second theme involves making a finite element analysis of stresses, displacements and deformations in prosthetic implants (the femoral implant and the polyethylene insert). Objectives The graphical modeling approach comes in two parts. The first is the segmentation of MRI scanned images, retrieved in DICOM format for edge detection. In the second part, 3D-CAD models are generated from the results of the segmentation stage. The finite element analysis is done by first extracting the prosthetic implants from the reconstructed 3D-CAD model, then do a finite element analysis of these implants under objectively determined conditions such as; forces, allowed displacements, the materials composing implant, and the coefficient of friction. Conclusion The objective of this work is to implement an interface for exchanging data between 2D MRI images obtained from a medical diagnosis of a patient and the 3D-CAD model used in various applications, such as; the extraction of the implants, stress analysis at the knee joint and can serve as an aid to surgery, also predict the behavior of the prosthetic implants vis-a-vis the forces acting on the knee joints. PMID:24396234

  6. Development of mobile robot for pipe welding with visual sensor

    SciTech Connect

    Suga, Yasuo; Saito, Keishin; Ishii, Hideaki

    1994-12-31

    An autonomous mobile robot with visual sensor and four driving axes for pipe welding was constructed. The robot can move along a pipe, and detect the weld line to be welded by visual sensor. Moreover, in order to perform welding automatically, the welding torch can track the weld line of the pipes by rotating the robot head. In the case of welding of T-joint of pipes, the robot can detect the contact angle between the two base metals to be welded, and the torch angle changes according to the contact angle. As the result of tracking test by the robot system, it was made clear that the recognition of the geometry of the T-joint by the laser lighting method and automatic seam tracking were possible. The average tracking error was 0.4 mm approximately and the torch angle could be always kept at the optimum angle.

  7. Matrix penetration in the bulk:In uence of humidity: Morphological analysis of wood welding

    E-print Network

    Psaltis, Demetri

    Matrix penetration in the bulk:In uence of humidity: Morphological analysis of wood welding.pichelin@b .ch Context: Wood can be welded using linear vibration welding tech- niques similar to the ones in plastic and metal industry[1] . Wood welding allows bonding strength similar to glued joints. However, due

  8. Weld-brazing of titanium. [resistance spot welding combined with brazing

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

    A joining process, designated weld-brazing, which combines resistance spot-welding and brazing has been developed at the NASA Langley Research Center. Resistance spot-welding is employed to position and aline the parts and to establish a suitable faying surface gap for brazing and contributes to the integrity of the joint. Brazing enhances the properties of the joint and reduces the stress concentrations normally associated with spotwelds. Ti-6Al-4V titanium alloy joints have been fabricated using 3003 aluminum braze both in a vaccum furnace and in a retort containing an inert gas environment.

  9. 49 CFR 192.233 - Miter joints.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...CONTINUED) PIPELINE SAFETY TRANSPORTATION OF NATURAL AND OTHER GAS BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Welding of Steel in Pipelines § 192.233 Miter joints. (a) A miter joint on steel pipe to be operated at a pressure...

  10. Friction Stir Spot Welding of Advanced High Strength Steels

    SciTech Connect

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

    2009-11-13

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

  11. The filler powders laser welding of ODS ferritic steels

    NASA Astrophysics Data System (ADS)

    Liang, Shenyong; Lei, Yucheng; Zhu, Qiang

    2015-01-01

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

  12. Laser welding of aluminum alloys

    SciTech Connect

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

    1997-03-01

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

  13. Shape memory effect of laser welded NiTi plates

    NASA Astrophysics Data System (ADS)

    Oliveira, J. P.; Fernandes, F. M. Braz; Schell, N.; Miranda, R. M.

    2015-07-01

    Laser welding is a suitable joining technique for shape memory alloys (SMAs). This paper reports the existence of shape memory effect (SME) on laser welded NiTi joints, subjected to bending tests, and correlates this effect with the microstructural analysis performed with X-ray diffraction (XRD). All welded samples were able to recover their initial shape after bending to 180°, which is a remarkable result for industrial applications of NiTi involving laser welding.

  14. Welding of aluminum with linear ribbon explosives.

    NASA Technical Reports Server (NTRS)

    Bement, L. J.

    1971-01-01

    A small-scale simplified, parallel plate process of welding aluminum with very small quantities of lead-sheathed linear ribbon RDX explosive is described. The results of the welding of five different alloys, obtained by using this technique, show that the weld strengths are up to 90% of the parent metal tensile strength.

  15. Soldadura (Welding). Spanish Translations for Welding.

    ERIC Educational Resources Information Center

    Hohhertz, Durwin

    Thirty transparency masters with Spanish subtitles for key words are provided for a welding/general mechanical repair course. The transparency masters are on such topics as oxyacetylene welding; oxyacetylene welding equipment; welding safety; different types of welds; braze welding; cutting torches; cutting with a torch; protective equipment; arc…

  16. WELDING RESEARCH -s231WELDING JOURNAL

    E-print Network

    Zhang, YuMing

    welding, the productivity is mostly determined by the travel speed provided that the welding performanceWELDING RESEARCH -s231WELDING JOURNAL ABSTRACT. Double-electrode gas metal arc welding (DE the welding wire and the bypass torch. To control the base metal current at the desired level, a group

  17. WELDING RESEARCH -s229WELDING JOURNAL

    E-print Network

    Zhang, YuMing

    weld quality and higher productivity. Since the characteristic of metal transfer in GMAW significantlyWELDING RESEARCH -s229WELDING JOURNAL ABSTRACT. Dual-bypass gas metal arc welding (DB agrees with experimental data. Introduction Gas metal arc welding (GMAW) is an arc welding process

  18. Friction stir welding of thin-sheet, age-hardenable aluminum alloys: A study of process/structure/property relationships

    NASA Astrophysics Data System (ADS)

    Shukla, Alpesh Khushalchand

    Friction Stir Welding (FSW) is a relatively new joining process that, as a solid-state process, offers several advantages over conventional fusion welding. Although FSW has been used extensively for the joining of age-hardenable aluminum alloys, the detailed effects of process parameters on the microstructures and mechanical properties of these welds have not been studied, especially for thin-sheet alloys. The present study investigated the FSW of thin-sheet, age-hardenable aluminum alloys, including: the development and optimization of welding process parameters that produce high-integrity, defect-free welds; the systematic evaluation of the effect of the base metal microstructure, FSW process parameters, and corresponding weld zone thermal conditions on microstructure evolution across the weld zone; the analysis of FSW mechanical properties and fracture behavior; and the development of relationships between the process parameters, microstructure, properties, and fracture that allow the optimization of weld performance. Two alloy systems, viz., Al-Cu-Mg (2024) and Al-Cu-Li (2195) in naturally-aged and artificially-aged conditions, respectively, were studied. Process optimization in 1 mm thick 2024-T3 sheet resulted in superior properties versus those of FS welds in thick sheet and plate, and nearly 100% joint efficiency. Microstructures, hardness and tensile properties of FS welds in 2024-T3 exhibited a strong dependency on process parameters. The heat of welding promoted various weld zone microstructures that were produced via the dissolution of base metal GPB zones, the nucleation of GBP and GPB II, and the nucleation and coarsening of S phase. SZ hardness for 2024-T3 welds exhibited a strong, but unusual dependency on the FSW process parameters, which was related to different mechanisms related to GPB zone formation. The microstructures of FS welds in 1 mm thick 2195-T8 were generally insensitive to the FSW process parameters. For all weld heat inputs, FSW resulted in almost complete dissolution of the base metal strengthening phases T 1 and theta'' in the SZ and their partial dissolution in the HAZ, resulting in FSW hardness and tensile strength below that of the base metal and that were comparable to FSW weld properties obtained in thicker materials.

  19. Characterization of Friction Stir Welded Tubes by Means of Tube Bulge Test

    SciTech Connect

    D'Urso, G.; Longo, M.; Giardini, C.

    2011-05-04

    Mechanical properties of friction stir welded joints are generally evaluated by means of conventional tensile test. This testing method might provide insufficient information because maximum strain obtained in tensile test before necking is small; moreover, the application of tensile test is limited when the joint path is not linear or even when the welds are executed on curved surfaces. Therefore, in some cases, it would be preferable to obtain the joints properties from other testing methods. Tube bulge test can be a valid solution for testing circumferential or longitudinal welds executed on tubular workpieces. The present work investigates the mechanical properties and the formability of friction stir welded tubes by means of tube bulge tests. The experimental campaign was performed on tubular specimens having a thickness of 3 mm and an external diameter of 40 mm, obtained starting from two semi-tubes longitudinally friction stir welded. The first step, regarding the fabrication of tubes, was performed combining a conventional forming process and friction stir welding. Sheets in Al-Mg-Si-Cu alloy AA6060 T6 were adopted for this purpose. Plates having a dimension of 225x60 mm were bent (with a bending axis parallel to the main dimension) in order to obtain semi-tubes. A particular care was devoted to the fabrication of forming devices (punch and die) in order to minimize the springback effects. Semi-tubes were then friction stir welded by means of a CNC machine tool. Some preliminary tests were carried out by varying the welding parameters, namely feed rate and rotational speed. A very simple tool having flat shoulder and cylindrical pin was used. The second step of the research was based on testing the welded tubes by means of tube bulge test. A specific equipment having axial actuators with a conical shape was adopted for this study. Some analyses were carried out on the tubes bulged up to a certain pressure level. In particular, the burst pressure and the wall thickness were measured for each tested tube.

  20. Adjustable Bracket For Entry Of Welding Wire

    NASA Technical Reports Server (NTRS)

    Gilbert, Jeffrey L.; Gutow, David A.

    1993-01-01

    Wire-entry bracket on welding torch in robotic welding system provides for adjustment of angle of entry of welding wire over range of plus or minus 30 degrees from nominal entry angle. Wire positioned so it does not hide weld joint in view of through-the-torch computer-vision system part of robot-controlling and -monitoring system. Swiveling bracket also used on nonvision torch on which wire-feed-through tube interferes with workpiece. Angle simply changed to one giving sufficient clearance.