Sample records for welded joints obtained

  1. End-grain butt joints obtained by friction welding of high density eucalyptus wood

    Microsoft Academic Search

    H. R. Mansouri; A. Pizzi; J.-M. Leban

    2010-01-01

    End-grain-to-end-grain welding gave butt joints of good strength with three high density Australian eucalyptus woods, namely\\u000a Sidney blue gum (Eucalyptus saligna), Spotted gum (Eucalyptus maculata, Corymbia maculata spp.) and Black butt (Eucalyptus\\u000a pilularis). The absence or limited tendency to defibration in end-grain-to-end-grain welding for wood densities as high as these, around\\u000a 800–900 kg\\/m3, indicates that end-grain-to-end-grain welding is possible and yields

  2. Fatigue resistance of titanium laser and hybrid welded joints

    Microsoft Academic Search

    C. Casavola; C. Pappalettere; G. Pluvinage

    2011-01-01

    This paper presents a detailed study on fatigue strength of welded joints made of two titanium alloys, grade 2 and grade 5, and welded by laser or hybrid process. Fatigue strength curves obtained for each alloy and each welding technique are compared in terms of safety factors with fatigue design curves of welded joints provided by standards. Material and welding

  3. Strength of welded copper joints

    SciTech Connect

    Kuzyukova, A.N.; Fedorenko, M.I.; Kovalenko, N.I.; Zelik, E.I.

    1983-07-01

    A coefficient of the strength of welded joints in structures of copper and its alloys made by manual arc welding are known. At the Severedonetsk Branch of the Institute of Chemical Engineering the strength coefficients were determined for welded joints made of MZR (phosphorous-deoxydized) copper produced by manual argonarc welding. Optimum welding regimes were selected, and specimens of strips tested for tensile strength. Metallographic investigations showed significant grain growth in the zone of thermal influence. The results of mechanical tests are given. The results are verified by the fabrication of nine models. All the models ruptured in the zone of thermal influence, confirming results that the zone of thermal influence was the weak point in the welded joints in copper.

  4. 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.

  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. 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.

  8. 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.

  9. Capacity prediction of welded timber joints

    Microsoft Academic Search

    Till Vallée; Thomas Tannert; Christelle Ganne-Chedville

    Linear vibration welding of timber structural elements provides new opportunities to potentially achieve structural joints.\\u000a This paper investigates to which extent welded joints can be considered for load-bearing structural joints. On the basis of\\u000a a series of experimental and numerical investigations on a series of welded single-lap joints, failure modes were identified,\\u000a and the associated failure criterion was quantified. A

  10. Fatigue Life Improvement Factors Obtained by Weld Reinforcement and Toe Grinding

    Microsoft Academic Search

    Christopher Mullen; John Merwin

    1982-01-01

    The potential of weld reinforcement and toe grinding techniques for improving the fatigue life of welded joints protected from seawater corrosion is quantified based on tests performed in air on welded plate specimens. Results are presented in terms of median fatigue life improvement factors and prediction intervals obtained by linear regression analysis. The significant improvements possible with weld reinforcement are

  11. Properties of Underwater Coated Electrode Welded Joints

    Microsoft Academic Search

    Constantin Miholc?; Elena Scutelnicu; Aurelia Mihailescu

    The paper presents the results of two comparative studies concerning some properties of underwater air-water coated-electrode welded joints (fillet and butt joints). The testes were performed using normal strength naval steel and hydro-protected medium coated-electrode (Ti). The welding environmental factors were accorded to the Romanian Register of Shipping regulations. The mechanical properties and HV 10 hardness of the welded joints

  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. Shrink-Fitting and Dowel Welding in Mortise and Tenon Structural Wood Joints

    Microsoft Academic Search

    E. Mougel; C. Segovia; A. Pizzi; A. Thomas

    2011-01-01

    Shrink-fitting, a common bonding technique in metal assemblies, was used for mortise and tenon wood joints. The joints had considerable strength. Shrink-fitting yielded joint strengths comparable to those obtained by using several welded dowels. Increasing the number of welded dowels, however, produced joints of higher strength than those bonded just by shrink-fitting. Combining in the same joint both dowel welding

  14. 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).

  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. Effect of Welding Time on the Joining Phenomena of Diffusion Welded Joint Between Aluminum Alloy and Stainless Steel

    Microsoft Academic Search

    Hongxin Shi; Shuang Qiao; Ranfeng Qiu; Jinhong Zhu; Hua Yu

    2012-01-01

    In the present study, direct diffusion welding of aluminum alloy 5A02 and stainless steel SUS304 has been carried out in vacuum in the welding time range of 35-110 minutes. The effect of welding time on the interfacial microstructure and tensile shear strength of the joint were investigated. The joint with tensile shear strength of 101.3 MPa was obtained under the condition

  17. INFLUENCE OF THE WELDING PROCESS ON THE MECHANICAL PROPERTIES OF THE WELDED JOINT

    Microsoft Academic Search

    Branko Bauer; Slobodan Kralj

    Laser and TIG welding processes are suitable for welding of thin sheets. Welding of heat-treatable steels causes substantial increase of the hardness in the welded joint area. The increase of hardness does not necessarily have a negative influence on the mechanical properties of the welded joint. Butt welds of 2 mm thick heat-treatable steel sheets 25CrMo4 and 42CrMo4 were welded

  18. The influence of welding parameters on the joint strength of resistance spot-welded titanium sheets

    Microsoft Academic Search

    Nizamettin Kahraman

    2007-01-01

    In this study, commercially pure (CP) titanium sheets (ASTM Grade 2) were welded by resistance spot welding at different welding parameters and under different welding environments. The welded joints were subjected to tensile-shearing tests in order to determine the strength of the welded zones. In addition, hardness and microstructural examinations were carried out in order to examine the influence of

  19. Residual Stress on Titanium Alloy Welded Joints

    Microsoft Academic Search

    Caterina Casavola; Carmine Pappalettere

    Titanium and its alloys presents an elevated strength\\/weight ratio, good mechanical properties also to high temperatures,\\u000a elevated resistance to corrosion and to most part of acids attack. These characteristics makes this material attractive for\\u000a numerous applications. Thanks to recent improvements in welding techniques that allow the realization of high quality welded\\u000a joints, the employ of titanium alloys is spreading in

  20. Joint strength of laser-welded titanium

    Microsoft Academic Search

    J Liu; I Watanabe; K Yoshida; M Atsuta

    2002-01-01

    Objective: The objective of this study was to examine the joint strength of titanium laser-welding using several levels of laser output energy [current (A)].Methods: Cast titanium plates (0.5×3.0×40 and 1.0×3.0×40mm3) were prepared and perpendicularly cut at the center of the plate. After the cut halves were fixed in a jig, they were laser-welded using a Nd: YAG laser at several

  1. 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.

  2. Performance of Dowel-Welded Wood Furniture Linear Joints

    Microsoft Academic Search

    C. Segovia; A. Pizzi

    2009-01-01

    Comparison of three types of furniture joints such as scarf joints, step butt joints and dovetail joints held together either by one or two welded dowels, glued dowels and steel nails showed that the dowels always gave better shear strength and greater stiffness than the steel nails. The results of welded dowels and glued dowel joints were found to be

  3. 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.

  4. Properties of welded joints in AT6 titanium alloy

    Microsoft Academic Search

    V. E. Blashchuk; G. E. Boeva; L. M. Onoprienko; G. M. Shelenkov; V. E. Troyanovskii

    1983-01-01

    The mechanical properties and corrosion resistance of the base metal AT6 titanium alloy is studied and joints welded with electromagnetic stirring of the weldpool (EMS) are investigated in order to choose the welding method which gives joints similar in properties to that of the base metal. The mechanical properties of welded joints in AT6 alloy by the automatic, manual with

  5. Fatigue Properties of Spot Welded and Spot Weld-Bonded Joints of Steel Sheet

    Microsoft Academic Search

    Tomoyuki Fujii; Keiichiro Tohgo; Yukinori Suzuki; Takahiro Yamamoto; Yoshinobu Shimamura; Yoshifumi Ojima

    2011-01-01

    In this paper, fatigue tests are carried out on spot welded and spot weld-bonded joints of mild steel and ultra-high strength steel plates. The fatigue strength of the spot weld-bonded joints is higher than that of the spot welded joints. On the spot weld-bonded specimens, the strain distribution around the bonded area during fatigue tests is measured by using strain

  6. 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.

  7. Advanced tests of wet welded joints

    SciTech Connect

    Pachniuk, I. [Stolt Comex Seaway S.A., Marseille (France); Petershagen, H.; Pohl, R. [Univ. Hamburg (Germany); Szelagowski, P.; Drews, O. [GKSS Research Centre, Geesthacht (Germany)

    1994-12-31

    Wet Welding has in former times only been applied to secondary structural components. Nowadays wet welding has become an upcoming repair process due to high process flexibility, its low investment costs and its high versatility. Even the quality of the wet welded joints has been improved remarkably due to intensive and concentrated development activities. However, especially in the North Sea regions owners of offshore structures and classifying authorities still hesitate to recognize the process as a reliable alternative to dry hyperbaric welding repair methods. It therefore requires further activities especially in the field of data development for life prediction of such repaired components. Advanced testing methods are necessary, additional design criteria are to be developed and achievable weldment quality data are to be included in acknowledged and approved standards and recommendations to improve the credibility of the process and to solve the problem of quality assurance for wet welded joints. A comprehensive project, sponsored by the European Community under the Thermie Programme, is in progress to develop new testing procedures to generate the required data and design criteria for the future application of the wet welding process to main components of offshore structures. It is the aim of the project to establish additional fitness for purpose data for this process.

  8. Microstructural and electrochemical characterization of a thin-section dissimilar stainless steel weld joint

    Microsoft Academic Search

    P. Bala Srinivasan; M. P. Satish Kumar

    2009-01-01

    A dissimilar weld joint consisting of an austenitic stainless steel (ASS) and a martensitic stainless steel (MSS) was obtained under optimized welding conditions by autogenous gas tungsten arc welding technique. The weld metal was found to be dual-phased, and was constituted with an austenite matrix containing interdendritic ferrite of about 3–8EFN, with over-matching mechanical properties. Electrochemical behaviour assessment of the

  9. The effect of controlled shot peening on fusion welded joints

    Microsoft Academic Search

    Nur Azida Che Lah; Aidy Ali; Napsiah Ismail; Lim Poon Chai; Abdul Aziz Mohamed

    2010-01-01

    This work examines the effect of controlled shot peening (CSP) treatment on the fatigue strength of an ASTM A516 grade 70 carbon steel welded joint. Metallurgical modifications, hardness, elemental compositions, and internal discontinuities, such as porosity, inclusions, lack of penetration, and undercut found in treated and untreated fusion welded joints, were characterized. The fatigue results of as-welded and peened skimmed

  10. An inelastic analysis of a welded aluminum joint

    Microsoft Academic Search

    R. E. Vaughan

    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

  11. Properties of welded joints in AT6 titanium alloy

    SciTech Connect

    Blashchuk, V.E.; Boeva, G.E.; Onoprienko, L.M.; Shelenkov, G.M.; Troyanovskii, V.E.

    1983-07-01

    The mechanical properties and corrosion resistance of the base metal AT6 titanium alloy is studied and joints welded with electromagnetic stirring of the weldpool (EMS) are investigated in order to choose the welding method which gives joints similar in properties to that of the base metal. The mechanical properties of welded joints in AT6 alloy by the automatic, manual with SP2V filler, and with the AT3sv filler methods are determined. Results indicate that welding with EMS raises the tensile strength, ductility, and impact strength of the welded joints to the level of the base metal. The results also show that joints welded manually with AT3sv filler have high strength, low susceptibility to anodic dissolution in the zone of active potential, and the lowest corrosion rates in the media studied. It is recommended that equipment made of AT6 alloy should be welded with EMS using AT3sv filler wire.

  12. Effect of weld geometry on the fatigue life of non-load-carrying fillet welded cruciform joints

    Microsoft Academic Search

    Chin-Hyung Lee; Kyong-Ho Chang; Gab-Chul Jang; Chan-Young Lee

    2009-01-01

    In the present study, the effect of weld geometry on the fatigue life of non-load-carrying fillet welded cruciform joints was experimentally investigated. The weld geometry of the cruciform specimens was intentionally varied, and fatigue tests were carried out on various weld geometry configurations. The configurations included weld flank angle, weld toe radius and weld throat thickness. Constant amplitude fatigue tests

  13. Fatigue crack propagation analysis for welded joint subjected to bending

    Microsoft Academic Search

    Biehn Baik; Kentaro Yamada; Toshiyuki Ishikawa

    2011-01-01

    In this paper, fatigue tests have been conducted on specimens, which are flat plate with a notch, stud-welded plate, T-shaped fillet welded joint and cruciform fillet welded joint, in such a way that fatigue cracks could be initiated and propagated in bending load. Under bending load, surface crack has formed flat semi-ellipse and propagated to about 80% of plate thickness

  14. An investigation of residual stress in welded joints

    E-print Network

    Moffat, William Hugh

    1951-01-01

    . flummery and Conclusions VII. '-. &uggested Procedure for I"uture Investigation 18 o i' VIII. ? . Ppendix IX. Bibliography LIST OP EIGURES Ro. Title Page 1. 'welded Plates snd Gptical Gage Used by Soulton and Martin ~ ~ 6 2. Dr. Rao~s Method... AN INVESTIGATION OF RESIDUAL STRESS IN WELDED JOINTS INTRODUCTION The object of the research reported in this paper was to investigate the magnitude of transverse and longi- tudial residual stress in a welded Joint. These are the stresses in a direction...

  15. Impact toughness of welded joints of niobium alloys

    Microsoft Academic Search

    E. A. Asnis; S. M. Gurevich; A. D. Demchenko; M. M. Nerodenko; M. D. Rabkina

    1975-01-01

    Conclusions 1.It was found that the impact toughness of welded joints of niobium alloys varies with the welding speed.2.The impact toughness reaches the highest values at welding speeds of 40–60 m\\/h and then remains constant. The impact toughness changes least for niobium alloys with solid solution hardening.3.Separation of the impact toughness into its component parts showed that higher welding speeds

  16. Comparison of Post Weld Treatment of High Strength Steel Welded Joints in Medium Cycle Fatigue

    Microsoft Academic Search

    M. M. Pedersen; O. Ø. Mouritsen; M. R. Hansen; J. G. Andersen; J. Wenderby

    This paper presents a comparison of three post weld treatments for fatigue life improvement of welded joints. The objective is to determine the most suitable post weld treatment for implementation in mass production of certain crane components manufactured from very high strength steel. The processes investigated are; burr grinding, TIG dressing and ultrasonic impact treatment. The focus of this investigation

  17. Neutron irradiation effect on the mechanical properties of type 316L SS welded joints

    NASA Astrophysics Data System (ADS)

    Saito, S.; Fukaya, K.; Ishiyama, S.; Amezawa, H.; Yonekawa, M.; Takada, F.; Kato, Y.; Takeda, T.; Takahashi, H.; Nakahira, M.

    2002-12-01

    In the International Thermonuclear Experimental Reactor design activity, the vacuum vessel (VV) is designed as a double walled structure so that some parts are not qualified by the conventional design standards. JAERI has executed the preparation activity of the new design standards and obtained the technical data to support them. In this study, neutron irradiation effects on the mechanical properties of 316L SS welded joints were investigated. The tensile and Charpy-impact specimens were irradiated at 473 K. The results of post irradiation experiments indicate that sufficient ductility is still maintained for tungsten inert gas (TIG) and electron beam (EB) welded joints; whereas, the impact properties of metal inert gas (MAG) weld metal are extremely poor. Consequently, the soundness of the 316L SS base metal and its TIG and EB welded joints are retained after 0.2-0.5 dpa neutron irradiation. However, it is rather difficult to adopt MAG welding for the fabrication of the VV.

  18. Influence of the method of welding of AT3 alloy on the weld joint properties and the tendency toward corrosion cracking

    Microsoft Academic Search

    V. E. Blashchuk; L. M. Onoprienko; A. A. Trufanov

    1986-01-01

    In this work an investigation was made of the influence of the welding method on the mechanical properties, corrosion resistance, and tendency toward corrosion cracking of weld joints of AT3 alloy produced by mechanized helium arc welding and manual argon are welding. Manual argon arc welding and mechanized helium arc welding with manual auxiliary welding, in which the weld joint

  19. Fatigue Behavior of Friction Stir-Welded Joints Repaired by Grinding

    NASA Astrophysics Data System (ADS)

    Vidal, C.; Infante, V.

    2014-04-01

    Fatigue is undoubtedly the most important design criterion in aeronautic structures. Although friction stir-welded joints are characterized by a high mechanical performance, they can enclose some defects, especially in their root. These defects along with the relatively low residual stresses of the friction stir-welding thermomechanical cycle can turn into primary sources of crack initiation. In this context, this article deals with the fatigue behavior of friction stir-welded joints subjected to surface smoothing by grinding improvement technique. The 4-mm-thick aluminum alloy 2024-T351 was used in this study. The fatigue strength of the base material, joints in the as-welded condition, and the sound and defective friction stir-welded joints improved by grinding were investigated in detail. The tests were carried out with a constant amplitude loading and with a stress ratio of R = 0. The fatigue results show that an improvement in fatigue behavior was obtained in the joints repaired by superficial grinding technique. The weld grinding technique is better especially for lower loads and increases the high cycle fatigue strength. The fatigue strength of the improved welded joints was higher than that of the base material.

  20. Improving Fatigue Life for Aluminum Cruciform Joints by Weld Toe Grinding

    Microsoft Academic Search

    Naiquan Ye; Torgeir Moan

    Fatigue improvement by weld toe grinding for aluminum welded joints has been investigated in this paper. Fatigue tests were performed for a number of as- welded and toe-ground non-load carrying cruciform joints. Finite element analyses were carried out to further study the influence of the variation of the main weld parameters such as the weld toe angle, weld toe radius

  1. Effect of Au coating on joint strength in laser welding for Invar-Invar packages

    Microsoft Academic Search

    S. C. Wang; C. Wang; Y. K. Tu; C. J. Hwang; S. Chi; W. H. Wang; W. H. Cheng

    1996-01-01

    The effect of Au coating on the joint strength, weld width, and penetration depth in laser welding technique for Invar-Invar packages is investigated experimentally. It is found that the joint strength, weld width, and penetration depth in the welded joints are strongly dependent on the Au thickness on the Invar material. The Invar-Invar joints with thick Au coating show narrower

  2. Wood joints and laminated wood beams assembled by mechanically-welded wood dowels

    Microsoft Academic Search

    J.-F. Bocquet; A. Pizzi; A. Despres; H. R. Mansouri; L. Resch; D. Michel; F. Letort

    2007-01-01

    Dowel welding by high-speed rotation was used to join two wood blocks and strong joints were obtained. Dowel angle to the surface of the wood blocks to be joined had a marked influence on the mechanical performance of the joint. When the dowel was inserted at 90° to the substrate, the dowel was subjected to and resisted a shear force

  3. SHRINK-FITTING AND DOWEL WELDING IN MORTISE AND TENON STRUCTURAL WOOD JOINTS

    E-print Network

    Paris-Sud XI, Université de

    SHRINK-FITTING AND DOWEL WELDING IN MORTISE AND TENON STRUCTURAL WOOD JOINTS E.Mougel1 , C.Segovia1, France 2 ENSTIB-CRAN, Nancy University, 27 Rue du Merle Blanc, 88000 Epinal, France ABSTRACT Shrink considerable strength. Shrink-fitting yielded joint strengths comparable to those obtained by using several

  4. Mechanical behavior study of laser welded joints for DP steel

    NASA Astrophysics Data System (ADS)

    Yan, Qi

    2008-03-01

    Advanced High Strength Steels (AHSS) are gaining considerable market shares in the automotive industry. The development and application of Dual Phase (DP) steel is just a consistent step towards high-strength steel grades with improved mechanical behavior. Tailor welded blanks with DP steel are promoted in the application of Body-In-White (BIW) structure by the automotive industry. A tailor welded blank consists of several flat sheets that are laser welded together before stamping. Applied cases of tailor welded blanks of high strength steels on the automotive structural parts are investigated in this paper. The mechanical behavior of laser welded joints for DP steel is studied. Microstructure of laser welded joints for DP steel was observed by SEM. Martensite in the weld seam explains the higher strength of welded joints than the base metal. Results show that the strain safety tolerance of laser welded seam for high strength steel can meet the requirement of automobile parts for stamping if the location of laser welded seam is designed reasonably.

  5. 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.

  6. An inelastic analysis of a welded aluminum joint

    NASA Astrophysics Data System (ADS)

    Vaughan, R. E.

    1994-09-01

    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.

  7. 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.

  8. 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%.

  9. Zigzag rotational dowel welding for exterior wood joints

    Microsoft Academic Search

    P. Omrani; J.-F. Bocquet; A. Pizzi; J.-M. Leban; H. Mansouri

    2007-01-01

    A zig-zag pattern of rotationally welded dowels across the interface of a butt joint between two wood planks was shown to yield strong joints without any adhesive. Tests after 2 h in boiling water showed that the joints were able to resist both 2 h immersion in boiling water, as well as the subsequent oven drying. Some unusual densification patterns

  10. Fatigue endurance of welded joints under variable amplitude loading

    Microsoft Academic Search

    V. I. Ryazantsev; V. A. Fedoseev; V. N. Shavyrin

    1980-01-01

    1.Spot-welded joints have a comparatively low level of endurance under acoustic loading. The nominal endurance limit for welded specimens of D16T aluminum alloy on a 108 cycle base does not exceed 1.5 kgf\\/ mm2, and for OT4-1 titanium alloy specimens on a 108 cycle base it is 5 kgf\\/mm2.2.Fatigue endurance of glued and welded D16T alloy specimens is an order

  11. Improving Fatigue Strength of Welded Joints by Ultrasonic Impact Treatment

    Microsoft Academic Search

    Sougata ROY

    Summary Enhancement in fatigue performance of welded joints by Ultrasonic Impact Treatment (UIT) was evaluated with large-scale rolled beam and built-up specimens having yield strength of 345 to 760 MPa. Eighteen rolled-beam specimens having welded details at cover plates and transverse stiffeners and eight built-up specimens having only transverse stiffener details were fatigue tested after treating the weld details by

  12. Measurement of Creep Deformation in Stainless Steel Welded Joints

    Microsoft Academic Search

    Y. Sakanashi; S. Gungor; P. J. Bouchard

    \\u000a This article reports early findings of an experimental programme aimed at determining local creep properties of welded joints\\u000a made from AISI Type 316H austenitic stainless steel. For this purpose, 3 mm thick, flat cross-weld specimens were cut from\\u000a a pipe and subjected to creep testing at 550°C. In order to determine local creep properties around the weld within the gauge

  13. Influence of Welding Parameters and Wood Properties on the Water Absorption in Scots Pine Joints Induced by Linear Welding

    Microsoft Academic Search

    Mojgan Vaziri; Owe Lindgren; Antonio Pizzi

    2011-01-01

    Wood welding is an environmentally-friendly and very quick technique to yield wood joints in just a few minutes and without using any adhesives. The only limitation of welded wood is that the joint is suitable only for interior use. Exterior use, or use in an environment with varying humidity requires water resistance of the welded joints. An investigation was performed

  14. Austenitic stainless steel-ferritic steel weld joint failures

    SciTech Connect

    Klueh, R.L.; King, J.F.

    1982-09-01

    The cause of failures of dissimilar-alloy (austenitic or ferritic) joints in superheater and reheater tubes of fossil-fired steam plants was investigated. In the failures of interest, cracks form and propagate in the ferritic steel (usually 2 1/4 Cr-1 Mo steel) about 5 to 15 ..mu..m from the fusion lines. The complex microstructure developed at the interface between weld metal and 2 1/4 Cr-1 Mo steel during welding and elevated-temperature service was examined in (1) the as-welded and as-welded-and-tempered conditions, and (2) failed and unfailed joints having more than 100,000 h of service in a fossil-fired boiler. Metallographic observations on failed and unfailed joints were combined with literature observations to explain the interface microstructure and subsequent failure mode. On the basis of the proposed failure model, recommendations are presented for improving joint reliability.

  15. Application of Numerical Modelling to Dowel-Welded Wood Joints

    Microsoft Academic Search

    M. Oudjene; M. Khelifa; C. Segovia; A. Pizzi

    2010-01-01

    Numerical models using a 3-D finite element analysis method and the behaviour of dowel-welded wood joints are presented. Simulation results for step butt wood joints with two welded wood dowels under shear are analyzed and a good agreement with the experimental results is shown. Anisotropic elasto-plastic constitutive law with hardening associated with material densification, without distinction between radial and tangential

  16. Fracture toughness of partially welded joints of SUS316 in high magnetic field at 4K

    Microsoft Academic Search

    A. Nishimura; J. Yamamoto; O. Motojima

    1997-01-01

    Two kinds of partially welded austenitic stainless steel joints were prepared using SUS 316, 75 mm thick. One joint was fabricated using tungsten inert gas welding and metal arc gas welding, and the other was electron beam welded. Compact tension specimens for fracture toughness tests were machined out from these welded plates in the thickness direction. The fracture toughness tests

  17. 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.

  18. 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.

  19. Crack resistance of the near-weld region of welded joints of titanium and aluminum alloys

    Microsoft Academic Search

    N. M. Lebid’; M. S. Kohut

    1998-01-01

    We studied the crack resistance Kc (KIc) of the near-weld region of welded joints of VT3-1 and VT14 titanium alloys and AMg6NPP, 12401, and 1420 high-strength aluminum\\u000a alloys under fatigue and static loading. By the methods of fracture mechanics and according to the results of testing cylindrical\\u000a specimens with external circular cracks initiated in the weld metal, fusion zone, zone

  20. The influence of welding heat input on submerged arc welded duplex steel joints imperfections

    Microsoft Academic Search

    Jerzy Nowacki; Pawe? Rybicki

    2005-01-01

    The influence of the heat input submerged arc welding (SAW) of duplex steel UNS S31803 on kind and quantity of welded butt joints defects has been determined. Defects were identified by a radiographic method. For the defectiveness rate in the ratio of quantity negative test results RN to complete radiographic test RC were taken. Radiograms have been classified on the

  1. Effect of welding conditions on the impact toughness of welded joints in titanium alloys

    Microsoft Academic Search

    V. Yu. Zubarev; B. A. Kolomenskii; A. B. Kolomenskii

    2011-01-01

    Effect of the welding conditions and annealing on the impact strength of different heat-affected areas of the titanium welded joints is studied. Maximum impact strength is established in the range of 350–550°C, in practice this coincides with the temperature peaks for short-time strength and fatigue life.

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

    NASA Astrophysics Data System (ADS)

    Michalska, J.; ?abanowski, J.; ?wiek, J.

    2012-05-01

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

  3. 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

  4. 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.

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

    SciTech Connect

    Qiu Ranfeng, E-mail: xdqrf@yahoo.com.cn [School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang, 471003 (China); Henan Key Laboratory of Advanced Non-ferrous Metals, Henan University of Science and Technology, Luoyang 471003 (China); Shi Hongxin; Zhang Keke; Tu Yimin [School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang, 471003 (China); Iwamoto, Chihiro; Satonaka, Shinobu [Graduate School of Science and Technology, Kumamoto University, Kurokami 2-39-1, Kumamoto, 860-8555 (Japan)

    2010-07-15

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

  6. Artificial neural network modeling of weld joint strength prediction of a pulsed metal inert gas welding process using arc signals

    Microsoft Academic Search

    Sukhomay Pal; Surjya K. Pal; Arun K. Samantaray

    2008-01-01

    This paper addresses the weld joint strength monitoring in pulsed metal inert gas welding (PMIGW) process. Response surface methodology is applied to perform welding experiments. A multilayer neural network model has been developed to predict the ultimate tensile stress (UTS) of welded plates. Six process parameters, namely pulse voltage, back-ground voltage, pulse duration, pulse frequency, wire feed rate and the

  7. The effect of weld geometry and residual stresses on the fatigue of welded joints under combined loading

    Microsoft Academic Search

    T. Ninh Nguyen; M. A. Wahab

    1998-01-01

    A mathematical model is developed to predict the overall effect of the influencing weld geometry parameters such as (e.g. weld toe radius, weld toe undercut, flank angle, plate thickness, misalignment) and residual stresses on the fatigue strength and fatigue life of butt-welded joints subjected to combined loading (tensile and bending). The concepts of linear elastic fracture mechanics (LEFM), finite element

  8. 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.

  9. Laser beam welding of dissimilar ferritic/martensitic stainless steels in a butt joint configuration

    NASA Astrophysics Data System (ADS)

    Khan, M. M. A.; Romoli, L.; Dini, G.

    2013-07-01

    This paper investigates laser beam welding of dissimilar AISI430F and AISI440C stainless steels. A combined welding and pre-and-postweld treatment technique was developed and used successfully to avoid micro-crack formation. This paper also examined the effects of laser welding parameters and line energy on weld bead geometry and tried to obtain an optimized laser-welded joint using a full factorial design of experiment technique. The models developed were used to find optimal parameters for the desired geometric criteria. All the bead characteristics varied positively as laser power increased or welding speed decreased. Penetration size factor decreased rapidly due to keyhole formation for line energy input in the range of 15-20 kJ/m. Laser power of 790-810 W and welding speed of 3.6-4.0 m/min were the optimal parameters providing an excellent welded component. Whatever the optimization criteria, beam incident angle was around its limiting value of 15° to achieve optimal geometrical features of the weld.

  10. Characterization of Gas Metal Arc Welding welds obtained with new high Cr-Mo ferritic stainless steel filler wires

    E-print Network

    Paris-Sud XI, Université de

    on the fusion zone a good ductility even in the as-welded state at room temperature. Unfortunately, titanium1 Characterization of Gas Metal Arc Welding welds obtained with new high Cr-Mo ferritic stainless Several compositions of metal cored filler wire were manufactured to define the best welding conditions

  11. Assessment of the fatigue life of aluminium spot-welded and weld-bonded joints

    Microsoft Academic Search

    A. M. Pereira; J. A. M. Ferreira; F. V. Antunes; P. J. Bártolo

    2012-01-01

    In modern machinery and automobile structures weight reduction and increased durability are the main issues in design. In these applications, lap welded and\\/or bonded joints are widely used; therefore, tools are needed to accurately predict their fatigue life. This paper is concerned with the fatigue strength of single lap joints formed with thin plates of 6082-T6 aluminium alloy using a

  12. Fatigue strength of transverse butt welded joints under random loading. Application of Miner's rule in ?max = ?y tests

    Microsoft Academic Search

    A. Ota; Y. Maeda; N. Suzuki

    1997-01-01

    The fatigue strength of transverse butt welded joints is obtained in tests involving the maximum stress ?max being kept the same as the yield strength of the material ?y while the minimum stress ?min is randomly varied. The tests involve modification of the stress conditions of actual welded structures containing high tensile residual stress up to the yield strength. The

  13. Application of laser peening without coating on steel welded joints

    Microsoft Academic Search

    Yoshihiro Sakino; Yuji Sano; You-Chul Kim

    2011-01-01

    Purpose – Laser peening without coating (LPwC) is an innovative surface enhancement technology for introducing compressive residual stress in metallic materials. The purpose of this study is to examine the characteristic at the laser-peened welded zone and the fatigue lives of the welding joints. Design\\/methodology\\/approach – LPwC conditions for 490 MPa grades of structural steels were selected. By using the

  14. 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; Welding; Heat-affected zone; Impact toughness; Fracture 1. Introduction Welding of titanium alloys in the investigation were extracted from a butt-welded joints of a TiÁ/6AlÁ/4V titanium * Corresponding author E

  15. Influence of the area of the sections of an unremelted production joint on the properties of weld joints of a bimetal

    SciTech Connect

    Leibzon, V.M.; Pavlov, A.A.; Pavlova, E.Kh.

    1987-01-01

    An investigation was made of the influence of the basic production parameters of the welding conditions on the area of the unremelted portion of the production joint and the interrelationship of this area and the indices determining the service reliability of the weld joint is established. In the experiments a 14 mm thick 16GS + 12Kh18N10T bimetal, 4 mm diam. Sv-08Kh25N13BTYu and Sv-03MYu welding wire, 5 mm diam. Sv-08A welding wire, and AN-26s and AN-348A welding fluxes were used. The plan of assembly and the order of applying the weld joints are shown. An analysis of the results showed that the basic parameters of the welding conditions presented have an insignificant influence on the area of the unremelted portions of the production joint. On the basis of data obtained, recommendations have been developed on the use of the welding variation with use of a production joint in production of chemical and petroleum apparatus.

  16. 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.

  17. A new fracture mechanics method to predict the fatigue life of welded cruciform joints

    Microsoft Academic Search

    Bimalendu Guha

    1995-01-01

    The fatigue life of MIG welded cruciform joint failing from root (LOP) region was successfully predicted using new fracture mechanics equations. These equations were developed by combining Paris' law and ?Ki-endurance equation and incorporating an integral factor (Ip) obtained by integrating Paris' equation. In the numerical formulation of the equation, the initiation life (Ni) and propagation life (Np) of the

  18. Research on fatigue behavior evaluation and fatigue fracture mechanisms of cruciform welded joints

    Microsoft Academic Search

    J. L. Fan; X. L. Guo; C. W. Wu; Y. G. Zhao

    2011-01-01

    The applications of infrared thermographic method and the relationship between the microstructures and mechanical properties of materials were reviewed. Experimental tests, using the thermographic method, have been carried out in order to evaluate the fatigue behavior of cruciform welded joints subjected to a high mean stress. A good agreement was achieved between the predicted values and those obtained by the

  19. Fatigue damage assessment of various welded joints under uniaxial loading based on energy methods

    Microsoft Academic Search

    F. Pakandam; A. Varvani-Farahani

    2011-01-01

    The present study intends to evaluate fatigue damage of different welded joints under uniaxial loading condition and its response on fatigue lifetime. The main variables influencing the fatigue life of a welded joint are: applied stress amplitude, material properties, geometrical stress concentration factor. Energy approaches were employed to evaluate the fatigue damage of various weld joints under uniaxial loading conditions.

  20. Design consideration for wet welded joints

    SciTech Connect

    Szelagowski, P.; Osthus, V. [GKSS Research Center, Geesthacht (Germany); Petershagen, H.; Pohl, R. [Univ. Hamburg (Germany). Inst. fuer Schiffbau; Lafaye, G. [Stolt Comex Seaway S.A., Marseille (France)

    1996-12-01

    Wet welding has become a joining technique that under certain circumstances can provide results which cannot be distinguished between wet or dry production and the achievable mechanical quality is comparable to dry atmospheric welds. Wet welding is not a process which can be applied easily and which can be properly handled by untrained diver welders. Wet welding is more than any other kind of welding process or procedure a joining technique that requires the full job-concentration and -knowledge of an excellent trained and skilled diver welder throughout the whole production time, who is 100% identifying himself with his task. Furthermore he must be fully aware of the production requirements and possible metallurgical/environmental reactions and outcomes. He must be able to be fully concentrated on the process performance throughout his total work shift. In short: he must be an outstanding expert in his field. The following paper will highlight these subjects and show the necessity of their exact observation to achieve excellent quality in wet welding.

  1. Corrosion-fatigue strength of spot-welded joints

    Microsoft Academic Search

    Vo No Shavyrin; G. S. Suvorova

    1973-01-01

    The corrosion-fatigu e strength of steel has been extensively investigated; theory of the mechanism of corrosion-fatigu e fracture has been developed, and a large fund of experimental data has been accumulated [1-3]o However, an overwhelming majority of investigations were concerned with monolithic steel parts, although joints (especially welded lap joints) made between various structural elements and characterized by high stress

  2. Friction welding of titanium–tungsten pseudoalloy joints

    Microsoft Academic Search

    Andrzej Ambroziak

    2010-01-01

    The friction welding of a dissimilar-metal joint in titanium and tungsten pseudoalloy, in which sintered tungsten grains and alloy Ni–Fe formed respectively the matrix (W-95wt.%) and the bonding phase, was investigated. The aim of the investigations was to determine which microstructures occur in the titanium–tungsten pseudoalloy joint and which interlayers ensure that there are no brittle structures in it. The

  3. Problems of Pore Formation in Welded Joints of Titanium Alloys

    Microsoft Academic Search

    V. I. Murav'ev

    2005-01-01

    Special features of formation of the connection zone in front of the front of molten pool and changes in the macro- and microstructure of the weld metal are considered for conditions of fusion welding of titanium alloys on an example of pseudo-?-titanium alloy VT20.Ways for forming macrotexture on the surface of joined preforms are determined with the aim of obtaining

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

    SciTech Connect

    Koshovyi, V.V.; Pakhn`o, M.I.; Tsykhan, O.I. [Karpenko Physicomechanical Institute, L`viv (Ukraine)

    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.

  5. Automatic joint tracking for CNC-programmed electron beam welding

    Microsoft Academic Search

    M. J. Carroll; D. E. Powers

    1985-01-01

    In an effort to provide a means for actively maintaining precise alignment during an entire welding procedure, various types of contact and non-contact joint sensing and tracking methods have been investigated over the years. A stylus riding in the groove or a cam follower running along a machined reference surface that parallels the groove, coupled to a transducer for producing

  6. Analysis of residual stresses and distortions in T-joint fillet welds

    Microsoft Academic Search

    Tso-Liang Teng; Chin-Ping Fung; Peng-Hsiang Chang; Wei-Chun Yang

    2001-01-01

    T-joint fillet welds are extensively used in ship engineering and bridge structures. Localized heating from the welding process and subsequent rapid cooling induce tensile residual stress near the toe of the T-joint in fillet welds. Welding produces thermal stresses that cause structural distortions, which influence the buckling strength of the welded structures. This study describes the thermal elasto-plastic analysis using

  7. 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.

  8. 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.

  9. Effect of UIT on Fatigue Life in Web-Gusset Welded Joints

    Microsoft Academic Search

    Yu Togasaki; Hirokazu Tsuji; Takashi Honda; Tetsuya Sasaki; Atsushi Yamaguchi

    2010-01-01

    Ultrasonic impact treatment (UIT), which is a peening method, is usually used as a post-weld treatment in order to improve the fatigue strength of welded joints. In this study, fatigue tests were carried out on web-gusset welded joints treated by UIT and the results were compared with the fatigue lives of as-welded joints in order to examine the effects of

  10. 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.

  11. Influences of post-weld heat treatment on tensile properties of friction stir-welded AA6061 aluminum alloy joints

    SciTech Connect

    Elangovan, K. [Department of Mechanical and Production Engineering, Annamalai University, Annamalai Nagar - 608 002, Tamil Nadu (India); Balasubramanian, V. [Centre for Materials Joining Research (CEMAJOR), Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar - 608 002, Tamil Nadu (India)], E-mail: visvabalu@yahoo.com

    2008-09-15

    This paper reports on studies of the influences of various post-weld heat treatment procedures on tensile properties of friction stir-welded AA6061 aluminum alloy joints. Rolled plates of 6-mm thick AA6061 aluminum alloy were used to fabricate the joints. Solution treatment, an artificial aging treatment and a combination of both were given to the welded joints. Tensile properties such as yield strength, tensile strength, elongation and joint efficiency were evaluated. Microstructures of the welded joints were analyzed using optical microscopy and transmission electron microscopy. A simple artificial aging treatment was found to be more beneficial than other treatment methods to enhance the tensile properties of the friction stir-welded AA6061 aluminum alloy joints.

  12. Early fatigue crack shape development in welded tubular joints

    SciTech Connect

    Monahan, C.C. [Memorial Univ. of Newfoundland, St. John`s, Newfoundland (Canada). Centre for Cold Ocean Resources Engineering; Dover, W.D. [University College, London (United Kingdom). Dept. of Mechanical Engineering

    1995-12-31

    Electromagnetic-based non-destructive testing techniques are used to monitor the growth and interaction of small surface fatigue cracks in welded tubular joints. The stress fields surrounding each joint are also analyzed using strain gauge rosettes. Crack growth trends are found to have a strong dependence on the geometric surface stress distribution around the brace-chord intersection. A correlation between the average geometric surface stress and the peak aspect ratio is used to derive an empirical forcing function for predicting early crack shape development behavior. Model predictions are compared with actual test results for the cases of IPB and OPB in multi-brace tubular T- and Y-joints.

  13. Fatigue Properties of Stainless Steel Lap Joints. Spot welded, adhesive bonded, weldbonded, laser welded and clinched joints of stainless steel sheets-a review of their fatigue properties

    Microsoft Academic Search

    Hans Nordberg

    The type of joints covered are i) spot welded stainless to stainless and to galvanised carbon steel, ii) adhesive bonded stainless to stainless, iii) weld bonded stainless to stainless, iv) laser welded stainless to stainless and to galvanised carbon steel, v) clinched stainless to stainless steel. The materials studied are AISI 301 and 304 stainless steel and high strength duplex

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

    Microsoft Academic Search

    Z SUN

    1993-01-01

    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

  15. Stability of the stress-strain state of titanium alloy weld joints

    Microsoft Academic Search

    A. I. Akulov; V. F. Savel'ev; L. D. Stolyarova; É. A. Mikheev; V. I. Gavryusev

    1986-01-01

    1.Microresidual weld stresses (microdistortion ?a\\/a) in weld joints of titanium alloy VT1-0 during aging at normal and raised (125°C) temperatures spontaneously lower.2.Both the relaxation curves and deformation curves of weld joints of alloy VT1-0 may be divided into two parts.

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

    Microsoft Academic Search

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

    2005-01-01

    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

  17. Fatigue life prediction of welded cruciform joints using strain energy density factor approach

    Microsoft Academic Search

    V Balasubramanian; B Guha

    2000-01-01

    The influences of two welding processes, namely, shielded metal arc welding (SMAW) and flux cored arc welding (FCAW), on fatigue life of cruciform joints containing lack of penetration (LOP) defects have been analyzed by using the strain energy density factor (SEDF) approach. Load carrying cruciform joints were fabricated from ASTM 517 ‘F’ grade steel. Fatigue crack growth experiments were carried

  18. Fatigue Endurance of Welded Joints, Residual Stresses and Fatigue Improvement Treatments

    Microsoft Academic Search

    V. I. Trufyakovi; Yu. F. Kudryavtsevi; D. N. Reznik

    Under certain conditions residual welding stresses greatly effect fatigue performance. Residual tensile stresses re- duce the fatigue life of welded joints in the region of multi-cycle loading by two to three times and more. The effect of tensile residual stresses on the fatigue limit of symmetrically loaded (R= minus 1) welded joints is equal to that of stress concentration factor.

  19. Thermoelasticity and CCD analysis of crack propagation in AA6082 friction stir welded joints

    Microsoft Academic Search

    P. Cavaliere; A. De Santis; F. Panella; A. Squillace

    2009-01-01

    The advantages of friction stir welding (FSW) process compared to conventional fusion welding technologies have been clearly demonstrated in recent years. In the present study, AA6082 FSW joints were produced by employing different welding parameters. The principal aim of this work is to apply thermoelastic stress analysis (TSA) to study crack propagation characteristics of friction stir welded aluminum sheets, during

  20. 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.

  1. Effects of flux type of covered electrodes on the fatigue strength of one?pass fillet welded joints

    Microsoft Academic Search

    S. Ota; K. Asai; T. Wada; T. Asakawa

    1996-01-01

    It is generally recognised that the flux type of covered electrodes affects the profile and mechanical properties of welds and may well control the fatigue strength of fillet welded joints. Fillet welded joints, however, have seen few systematic investigations. The purpose of this investigation is to improve the fatigue strength of fillet welded joints through appropriate design of the covered

  2. Structure and properties of welded joints from various titanium alloys

    Microsoft Academic Search

    A. A. Popov; A. G. Illarionov; M. A. Khorev; N. A. Drozdova

    1992-01-01

    Metallographic, x-ray diffraction, x-ray microspectral and hardness testing techniques have been used to examine the changes in the structure, phase composition, microhardness and the distribution of alloying elements in the parent metal and in the heat affected zone and in the seams of welded joints formed from various titanium alloys (VT6-OT4, VT6-VT20, VT23-OT4, VT23-VT6, VT23-VT19 and VT23-VT32) in the post

  3. Tendency of weld joints in titanium alloys toward delayed cracking

    Microsoft Academic Search

    A. S. Mikhaylov; V. S. Krylov

    1962-01-01

    Conclusions 1.The main reason for the tendency of weld joints in titanium alloys toward delayed cracking is the creased hydrogen content.2.High-strength titanium alloys as well as titanium alloys of medium and low strength with an increased amount of nitrogen and oxygen are more likely to form cracks because of lower ductility, all other things being equal.3.The most dangerous point for

  4. The joint-limits and singularity avoidance in robotic welding

    Microsoft Academic Search

    Liguo Huo; Luc Baron

    2008-01-01

    Purpose – The aim of this paper is to develop a redundancy-resolution (RR) algorithm to optimize the joint space trajectory of the six-rotation-axis industrial robot as performing arc-welding tasks. Design\\/methodology\\/approach – The rotation of the tool around its symmetry axis is clearly irrelevant to the view of the task to be accomplished besides some exceptional situations. When performed with a

  5. Mode I failure modeling of friction stir welding joints

    Microsoft Academic Search

    Guido Borino; Livan Fratini; Francesco Parrinello

    2009-01-01

    This paper analyzes mechanical response by finite element method up to the decohesion failure in fracture mode I for joints\\u000a of friction stir welding (FSW) of an aluminum alloy. It first describes experimental investigations on specimens with FSW\\u000a embedded, subjected to uniform traction and local punch tests used to characterize local elastic and plastic material parameters.\\u000a The heterogeneity of the

  6. Microstructure and properties of laser micro welded joint of TiNi shape memory alloy

    Microsoft Academic Search

    Wei-huai GONG; Yu-hua CHEN; Li-ming KE

    2011-01-01

    Butt welding of 0.2 mm-thick TiNi shape memory alloy sheet (SMA) was carried out using impulse laser, and tensile strength, fracture morphology, microstructure and phase change behaviour of welded joint were studied. The results show that using impulse laser can realize good butt welding of TiNi SMA sheet, tensile strength of welded joint is 683 MPa, which achieves 97% of

  7. Mechanical properties of welded joints of alloy VT23 after repeated heating by an electron beam

    Microsoft Academic Search

    V. S. Lyasotskaya; S. I. Knyazeva; Yu. T. Lysenkov

    1995-01-01

    Welded joints of high-strength titanium alloys are characterized by low properties of the weld and the heat-affected zone (HAZ). Heat treatment can improve these properties, especially in heat-affected zones. Heat treatment by standard regimes improves the properties of welded joints, but the weld and the HAZ usually have lower mechanical characteristics than the base metal and are still the most

  8. Influence of Weldling Parameters on Weldline Density and Its Relation to Crack Formation in Welded Scots Pine Joints

    Microsoft Academic Search

    Mojgan Vaziri; Owe Lindgren; Antonio Pizzi

    2011-01-01

    Exterior use of welded wood laminates without further treatment is not recommended. Frictional welded joints have poor resistance to moisture variation, especially to drying. Therefore, application of welded woods is limited to interior use without exposure to highly variable air humidity. Influences of some welding and wood parameters such as welding pressure, welding time and heartwood\\/sapwood on weldline density of

  9. Some investigations on microstructure and mechanical properties of submerged arc welded HSLA steel joints

    Microsoft Academic Search

    Keshav Prasad; D. K. Dwivedi

    2008-01-01

    This paper investigates the influence of the submerged arc welding (SAW) process parameters (welding current and welding speed)\\u000a on the microstructure, hardness, and toughness of HSLA steel weld joints. Attempts have also been made to analyze the results\\u000a on the basis of the heat input. The SAW process was used for the welding of 16 mm thick HSLA steel plates. The

  10. Fatigue strength improvement of MIG-welded joint by shot peening

    NASA Astrophysics Data System (ADS)

    Azida Che Lah, Nur; Ali, Aidy

    2011-02-01

    In this study, the effect of controlled shot peening (CSP) treatment on the fatigue strength of an ASTM A516 grade 70 carbon steel MIG-welded joint has been studied quantitatively. Metallurgical modifications, hardness, elemental compositions, and internal discontinuities, such as porosity and inclusions found in treated and untreated fusion welded joints, were characterized. The fatigue results of as-welded and peened skimmed joints were compared. It was observed that the effect of the CSP and skimming processes improved the fatigue life of the fusion weld by 63% on MIG-welded samples.

  11. 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.

  12. Effects of residual stress on fatigue strength of small diameter welded pipe joint

    SciTech Connect

    Yamashita, Tetsuo; Hattori, Takahiro [Mitsubishi Heavy Industries, Ltd., Takasago (Japan). Takasago R and D Center; Nomoto, Toshiharu [Univ. of Tokyo (Japan). Dept. of Naval Architecture and Ocean Engineering; Iida, Kunihiro [Sibaura Inst. of Tech., Tokyo (Japan). Dept. of Mechanical Engineering; Sato, Masanobu [Japan Power Engineering and Inspection Corp., Tokyo (Japan). Welding Engineering Dept.

    1996-12-01

    A power plant consists of many welded components, therefore, it is essential in establishing the reliability of the power plant to maintain the reliability of all welded components. The fatigue failure caused by mechanical vibrations of small diameter welded joints, which is represented by socket welded joints, is one of the major causes of trouble for the welded parts of the power plant. Here, bending fatigue tests were conducted to investigate the fatigue strength of small diameter socket welded pipe joints. In the most cases of large diameter socket joints, a fatigue crack started from the root of the fillet weld though the stress amplitude at the root was smaller than that at the toe of fillet weld. Additionally, the fatigue strength was affected by the weld bead sequence. The residual stress was considered to be one of the important parameters governing fatigue strength, therefore, its effects were investigated. In several types of pipe joints, the local stress and residual stress distributions were calculated by finite element analysis. The residual stresses were compressive at the toe and tensile at the root of the socket welded joints. Based on these results, the effects of residual stresses on the fatigue strength are discussed for small diameter welded pipe joints in the present work.

  13. Performance of Dowel-Welded T-Joints for Wood Furniture

    Microsoft Academic Search

    C. Segovia; A. Pizzi

    2009-01-01

    Comparison of two types of furniture joints namely step butt T-joints and mortise and tennon T-joints held together either by one or two welded or glued dowels showed that the shear strength results of welded dowel and glued dowel joints were comparable. For mortise and tennon T-joints there is, in general, no difference if the dowel is inserted at a

  14. Fatigue crack growth behaviour of A5083 series aluminium alloys and their welded joints

    Microsoft Academic Search

    Koji Gotoh; Koji Murakami; Yasuo Noda

    We investigated the difference in fatigue behaviour between the aluminium alloys A5083-O and A5083-H321, which are used as\\u000a structural components in ships and high speed craft. We obtained S–N curves for the base materials and the welded joints made\\u000a of A5083-O. The relationships between the fatigue crack propagation rates and the stress intensity factor ranges ?K, ?K\\u000a eff and ?K

  15. 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.

  16. Hardening of welded joints in titanium alloys, produced by electron-beam welding

    Microsoft Academic Search

    M. A. Khorev

    1985-01-01

    The ultimate strength of welded joints in alloys VT6S, VT14, VT23, and VT19 is 1100, 1150, 1300, and 1250 MPa, and the effectiveness of hardening, ?su=200, 250, 300, and 250, respectively, as a result of hardening heat treatment — quenching from the temperature of the upper boundary of the (a+ß)-region and subsequent aging at 450–560°C.

  17. Performance of Dowel-Welded L-joints for Wood Furniture

    Microsoft Academic Search

    C. Segovia; A. Renaud; A. Pizzi

    2011-01-01

    Rotationally welded wood dowels were used to hold together step butt and mortise and tenon L-joints and these joints were tested against European Norms for these types of joints. A factorial experiment was carried out in which (1) these two types of joints were tested, (2) 4 or 6 dowels per joint were used, (3) dowels were inserted at either

  18. Effects of peening on mechanical properties in friction stir welded 2195 aluminum alloy joints

    Microsoft Academic Search

    Omar Hatamleh

    2008-01-01

    The effects of surface treatment techniques like laser and shot peening on the mechanical properties were investigated for friction stir welded 2195 aluminum alloy joints. The loading in the tensile specimens was applied in a direction perpendicular to the weld direction. The peening effects on the local mechanical properties through the different regions of the weld were characterized using a

  19. IMPROVEMENT OF PROPERTIES OF WELDED JOINTS OF CIRCULAR COMPONENTS FOR GAS TURBINE ENGINES

    Microsoft Academic Search

    E. N. Eremin

    Method of electroslag welding with the combined electrode under ANF-21 flux, resulting in high-quality melting of the edges and satisfactory formation of the welded joint is described. In order to increase the properties of the weld metal, the latter was modified with the ultrafine powder of titanium carbonitride. The results of metallographic examination the zone or failure, the grain size,

  20. CRITICAL ANALYSIS OF CURRENT CODES ON FATIGUE DESIGN OF WELDED JOINTS

    Microsoft Academic Search

    Giuseppe Chiofalo; Vincenzo Crupi; Eugenio Guglielmino; Letterio Scibilia

    SUMMARY The aim of this paper is focused on the critical analysis of the recommendations, reported in some current codes, for the fatigue strength assessment of welded structures in ship. This paper collects a large amount of experimental data for fatigue assessment of welded joints, which differ for: base material (steel, aluminium alloys), yield stress, welding technique, geometry (i.e. butt,

  1. Modeling and validation of multiple joint reflections for ultra- narrow gap laser welding

    SciTech Connect

    Milewski, J.; Keel, G. [Los Alamos National Lab., NM (United States); Sklar, E. [Opticad Corp., Santa Fe, New Mexico (United States)

    1995-12-01

    The effects of multiple internal reflections within a laser weld joint as a function of joint geometry and processing conditions have been characterized. A computer model utilizing optical ray tracing is used to predict the reflective propagation of laser beam energy focused into the narrow gap of a metal joint for the purpose of predicting the location of melting and coalescence which form the weld. The model allows quantitative analysis of the effects of changes to joint geometry, laser design, materials and processing variables. This analysis method is proposed as a way to enhance process efficiency and design laser welds which display deep penetration and high depth to width aspect ratios, reduced occurrence of defects and enhanced melting. Of particular interest to laser welding is the enhancement of energy coupling to highly reflective materials. The weld joint is designed to act as an optical element which propagates and concentrates the laser energy deep within the joint to be welded. Experimentation has shown that it is possible to produce welds using multiple passes to achieve deep penetration and high depth to width aspect ratios without the use of filler material. The enhanced laser melting and welding of aluminum has been demonstrated. Optimization through modeling and experimental validation has resulted in the development of a laser welding process variant we refer to as Ultra-Narrow Gap Laser Welding.

  2. Comparison of creep rupture behaviour of type 316L(N) austenitic stainless steel joints welded by TIG and activated TIG welding processes

    Microsoft Academic Search

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

    2011-01-01

    Creep rupture behaviour of type 316L(N) austenitic stainless steel base metal and its weld joints fabricated both by single-pass activated TIG (A-TIG) and multi-pass conventional TIG (MP-TIG) welding processes were studied at 923K over a stress range of 160–280MPa. Both the weld joints possessed lower creep rupture lives than the base metal. The A-TIG weld joint displayed higher rupture lives

  3. 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.

  4. 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.

  5. Characteristics of Laser Beam and Friction Stir Welded AISI 409M Ferritic Stainless Steel Joints

    NASA Astrophysics Data System (ADS)

    Lakshminarayanan, A. K.; Balasubramanian, V.

    2012-04-01

    This article presents the comparative evaluation of microstructural features and mechanical properties of friction stir welded (solid-state) and laser beam welded (high energy density fusion welding) AISI 409M grade ferritic stainless steel joints. Optical microscopy, microhardness testing, transverse tensile, and impact tests were performed. The coarse ferrite grains in the base material were changed to fine grains consisting duplex structure of ferrite and martensite due to the rapid cooling rate and high strain induced by severe plastic deformation caused by frictional stirring. On the other hand, columnar dendritic grain structure was observed in fusion zone of laser beam welded joints. Tensile testing indicates overmatching of the weld metal relative to the base metal irrespective of the welding processes used. The LBW joint exhibited superior impact toughness compared to the FSW joint.

  6. Type IV Creep Damage Behavior in Gr.91 Steel Welded Joints

    NASA Astrophysics Data System (ADS)

    Hongo, Hiromichi; Tabuchi, Masaaki; Watanabe, Takashi

    2012-04-01

    Modified 9Cr-1Mo steel (ASME Grade 91 steel) is used as a key structural material for boiler components in ultra-supercritical (USC) thermal power plants at approximately 873 K (600 °C). The creep strength of welded joints of this steel decreases as a result of Type IV creep cracking that forms in the heat-affected zone (HAZ) under long-term use at high temperatures. The current article aims to elucidate the damage processes and microstructural degradations that take place in the HAZ of these welded joints. Long-term creep tests for base metal, simulated HAZ, and welded joints were conducted at 823 K, 873 K, and 923 K (550 °C, 600 °C, and 650 °C). Furthermore, creep tests of thick welded joint specimens were interrupted at several time steps at 873 K (600 °C) and 90 MPa, after which the distribution and evolution of creep damage inside the plates were measured quantitatively. It was found that creep voids are initiated in the early stages (0.2 of life) of creep rupture life, which coalesce to form a crack at a later stage (0.8 of life). In a fine-grained HAZ, creep damage is concentrated chiefly in an area approximately 20 pct below the surface of the plate. The experimental creep damage distributions coincide closely with the computed results obtained by damage mechanics analysis using the creep properties of a simulated fine-grained HAZ. Both the concentration of creep strain and the high multiaxial stress conditions in the fine-grained HAZ influence the distribution of Type IV creep damage.

  7. Influence of defects on fatigue crack propagation in laser hybrid welded eccentric fillet joint

    Microsoft Academic Search

    M. M. Alam; Z. Barsoum; P. Jonsén; A. F. H. Kaplan; H. Å. Häggblad

    2011-01-01

    Fatigue cracking of laser hybrid welded eccentric fillet joints has been studied for stainless steel. Two-dimensional linear elastic fracture mechanics analysis was carried out for this joint geometry for four point bending load. The numerical simulations explain for the experimental observations why the crack propagates from the lower weld toe and why the crack gradually bends towards the root. Lack

  8. Cracking of Welded Joints of Cast and Deformed Titanium Alloy VT5

    Microsoft Academic Search

    A. M. Polyanskii; V. M. Polyanskii

    2004-01-01

    The macro- and microstructure and microhardness of welded joints of titanium alloy VT5 are investigated. Fracture surfaces are studied and fractional analysis of hydrogen in cast metals is performed. Suggestions are put forward as to the causes and mechanisms of formation of cracks in a weld joint of a forging and a casting from alloy VT5. Places of crack initiation

  9. Investigation of the fatigue strength of the welded joints treated by TIG dressing

    Microsoft Academic Search

    Zoran D. Perovi?

    2007-01-01

    The fatigue fracture of structural details subjected to cyclic loads mostly occurs at a critical cross section with stress concentration. The welded joint is particularly dangerous location because of sinergetic harmful effects of stress concentration, tensile residual stresses, deffects, microstructural heterogeneity. Because of these reasons many methods for improving the fatigue resistance of welded joints are developed. Significant increase in

  10. Fatigue strength of welded joints in 6N01 aluminium alloy extrusions

    Microsoft Academic Search

    K. Matsuoka; S. Chiaki; T. Uemura; K. Kamata

    1994-01-01

    In this paper, the fatigue strength of welded joints in 6N01 aluminium alloy extrusions is discussed. Low copper content (?0.02%) alloys were chosen, considering corrosion resistance in sea water. Two series of specimens were prepared. One had two longitudinal stiffeners welded on both sides of the main plate (L?TYPE), and the other a non?load carrying fillet welded cruciform joint (T?TYPE).

  11. Fatigue behavior of welded joint spray fused by nickel-base alloy powder

    Microsoft Academic Search

    Xiaohui Zhao; Dongpo Wang; Caiyan Deng

    2011-01-01

    Modification of spray fusing (MSF), which is a new method, was used to improve the fatigue strength of welded joints. Cruciform welded joint of Q235B steel was processed by MSF with nickel-base alloy powder of Ni60A and Ni25A. The bonding layer between coating and weld was studied by optical microscopy, scanning electron microscopy (SEM) and energy spectrum analysis. The results

  12. Study of the crack resistance of a welded joint of titanium alloy type VT6S

    Microsoft Academic Search

    V. V. Pokrovskii; P. V. Yasnii; V. L. Yarusevich; V. I. Mikhailov; V. A. Sher

    1988-01-01

    Conclusions 1.In the welded joints studied according to the results of short-term static tests the basic metal and the heat-affected zone have higher strength and lower ductility than weld metal.2.A crack in the metal of the heat-affected zone in the test welded joints always deviated from the plane of its development solely in the direction of the basic metal.3.An increase

  13. Fatigue properties of welded joints using steel with high resistance to fatigue crack growth

    Microsoft Academic Search

    Kiyotaka Nakashima; Hiroshi Shimanuki; Tetsuro Nose; Tadashi Ishikawa

    2010-01-01

    It has been generally recognized that the fatigue life of welded joints is little influenced by the strength of steels owing to the high-stress concentration and the tensile residual stress near the weld toe. In this paper, improvement of the fatigue life of welded joints using steel with high resistance to fatigue crack growth (ferrite\\/martensite (F\\/M) steel) is investigated. F\\/M

  14. Fatigue strength improvement of MIG-welded joint by shot peening

    Microsoft Academic Search

    Nur Azida Che Lah; Aidy Ali

    2011-01-01

    In this study, the effect of controlled shot peening (CSP) treatment on the fatigue strength of an ASTM A516 grade 70 carbon steel MIG-welded joint has been studied quantitatively. Metallurgical modifications, hardness, elemental compositions, and internal discontinuities, such as porosity and inclusions found in treated and untreated fusion welded joints, were characterized. The fatigue results of as-welded and peened skimmed

  15. 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.

  16. 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

    2015-04-01

    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.

  17. 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

  18. Application of thermal methods for characterization of steel welded joints

    NASA Astrophysics Data System (ADS)

    Galietti, U.; Palumbo, D.

    2010-06-01

    Despite the large number of proposals in the field of fatigue prediction of welded joints, a globally accepted and unified theory, which applies easily to any load condition, does not exist. Real life components, indeed, differ in geometry and/or type of load from the structural design for which they are regarded by Standards, so that a lot of precautionary safety factors are used that lead to an underestimation of the actual fatigue life of joints. Infrared thermography has a great potential in this field, both from structural and thermomechanical points of view. It enables a full field stress analysis with a sufficient spatial resolution so that the complexity of the stress state at the weld toe and its time evolution are taken into account, emphasizing anomalies that may predict structural failure. A new methods for evaluation fatigue limit damage is presented in this paper and in particular interesting results derived from analysis of the evolution of thermoelastic signal phase. Variations in the value of signal phase indicate a not elastic behaviour and plastic dissipation in the material.

  19. 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.

  20. Finite element analysis of the residual stresses in T-joint fillet welds made of similar and dissimilar steels

    Microsoft Academic Search

    Kyong-Ho Chang; Chin-Hyung Lee

    2009-01-01

    In this paper, weld residual stress analyses are performed for T-joint fillet welds made of similar and dissimilar steels.\\u000a Three-dimensional uncoupled thermo-mechanical finite element model which can accurately capture residual stresses in a weld\\u000a piece is developed in order to predict the residual stress states in the fillet-welded T-joint. Results show that the maximum\\u000a longitudinal residual stresses near the weld

  1. Low-Power Laser\\/TIG Hybrid Welding Process of Magnesium Alloy with Filler Wire

    Microsoft Academic Search

    Liming Liu; Xinfeng Hao

    2010-01-01

    In the welding process of magnesium alloy, evaporative loss of alloying elements will induce welding defects and reduce the mechanical properties of weld joint. In this article, low-power laser\\/arc hybrid welding process of magnesium alloy with filler metal is studied to resolve this problem. Under the optimal welding parameters, weld joint with good formation and high quality can be obtained.

  2. 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.

  3. Determination of Residual Stress Profiles in A Friction Stir Welded Stringer-to-Skin Lap Joint

    NASA Astrophysics Data System (ADS)

    Bach, Michael

    Riveting has been for many years the conventional method of joining aluminum components such as aircraft stringer-to-skin panels in the lap joint configuration. Due to a demand for a more economical and improved joining method, friction stir welding has been proposed as an alternative welding process. Residual stresses left behind from the friction stir welding process caused the stringer-to-skin lap joint to twist after the clamps are removed. A post-welding process of hammer peening was able to remove the distortion in the plate. In this thesis, the crack compliance method is used to calculate the residual stresses in the friction stir welded lap joints in the through thickness, transverse, and longitudinal direction. A non-destructive residual stress measurement technique known as neutron diffraction was used on the lap joint in both as-welded and hammer peened conditions. The residual stress profiles in the through thickness, transverse and longitudinal directions were successfully measured and compared with the residual stress from the compliance method. It was determined that the compliance method was successful in calculating the residual stresses in the through thickness and transverse direction but was not able to calculate the residual stress in the longitudinal direction. Distortion in the plate was a result of a combination of non-uniform residual stress profile in the three principal directions. Fatigue testing was performed on the as-welded and hammer peened configuration and it was determined that the hammer peened condition outlived that of the as-welded condition under the same loading frequency. An examination of the failure locations in the friction stir welded lap joints concluded that the as-welded specimens failed at a location in the weld region with a combination of weld defects, lowest hardness value and highest tensile residual stresses.

  4. Characterization of Eurofer-97 TIG-welded joints by FIMEC indentation tests

    NASA Astrophysics Data System (ADS)

    Montanari, R.; Filacchioni, G.; Riccardi, B.; Tata, M. E.; Costanza, G.

    2004-08-01

    Welded joints of 25-mm thick plates of Eurofer-97, produced by a multi-pass GTAW + filler material method, have been investigated before and after different heat treatments to identify the temperature-time combination that gives mechanical properties as close as possible to those of the base material. After NDE (non-destructive examinations), samples were annealed in the temperature range 730-750 °C for 1 and 2 h, microhardness was measured across the joints and FIMEC (flat-top cylinder indenter for mechanical characterization) tests were carried out in the molten zone (MZ), heat affected zone (HAZ) and in the matrix. The FIMEC method allowed determination on a local scale of the yield stress as obtained in standard tensile tests. Mechanical tests were supplemented by optical microscopy observations. The best results were obtained by the treatment at 750 °C for 2 h: original characteristics are substantially recovered in the HAZ but not completely in the MZ.

  5. Tensile Properties and Work Hardening Behavior of Laser-Welded Dual-Phase Steel Joints

    NASA Astrophysics Data System (ADS)

    Farabi, N.; Chen, D. L.; Zhou, Y.

    2012-02-01

    The aim of this investigation was to evaluate the microstructural change after laser welding and its effect on the tensile properties and strain hardening behavior of DP600 and DP980 dual-phase steels. Laser welding led to the formation of martensite and significant hardness rise in the fusion zone because of the fast cooling, but the presence of a soft zone in the heat-affected zone was caused by partial vanishing and tempering of the pre-existing martensite. The extent of softening was much larger in the DP980-welded joints than in the DP600-welded joints. Despite the reduction in ductility, the ultimate tensile strength (UTS) remained almost unchanged, and the yield strength (YS) indeed increased stemming from the appearance of yield point phenomena after welding in the DP600 steel. The DP980-welded joints showed lower YS and UTS than the base metal owing to the appearance of severe soft zone. The YS, UTS, and strain hardening exponent increased slightly with increasing strain rate. While the base metals had multi-stage strain hardening, the welded joints showed only stage III hardening. All the welded joints failed in the soft zone, and the fracture surfaces exhibited characteristic dimple fracture.

  6. Improvement of fatigue strength of fillet-welded joints by water jet treatment of weld toe region

    Microsoft Academic Search

    S. Ota; T. Ishimura; T. Tamura

    1997-01-01

    This paper describes an investigation of improvement of the fatigue strength of non-load-carrying cruciform fillet welded joints through the kinetic energy of an abrasive water jet being applied to the weld toe region at a nozzle travel speed of 30 cm\\/min. An FEM analysis, measurements of the residual stress and hardness in the toe region, and 0-tension fatigue tests of

  7. Fatigue Performance of Gas Tungsten Arc, Electron Beam, and Laser Beam Welded Ti-6Al-4V Alloy Joints

    NASA Astrophysics Data System (ADS)

    Balasubramanian, T. S.; Balasubramanian, V.; Muthumanikkam, M. A.

    2011-12-01

    Titanium alloys have been successfully applied for aerospace, ship, and chemical industries because they possess many good characteristics such as high strength to weight ratio, superior corrosion resistance, and excellent high temperature resistance. Though these alloys show reasonable weldability characteristics, the joint properties are greatly influenced by the welding processes. The evaluation and prediction of fatigue life are very important for the welded joints to avoid catastrophic failure particularly in titanium alloys. This article compares the fatigue performance of Ti-6Al-4V alloy fabricated by gas tungsten arc welding, laser beam welding, and electron beam welding processes. The resultant fatigue properties of the welded joints are correlated with the tensile properties and microstructural characteristics. Of the three processes considered the joint welded by laser beam welding exhibits higher fatigue limit when compared with the other two processes due to the presence of fine lamellar microstructure in the weld metal region.

  8. 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

    2015-05-01

    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.

  9. Fatigue strength of joints made in hyperbaric and wet underwater welding

    Microsoft Academic Search

    J. Doyen; P. Castellucci; D. Colchen

    1992-01-01

    Synopsis: Wet underwater welding has proved to be very useful in emergency situations or for temporary jobs.Still not a recommended technique, it requires good understanding of the problems encountered when using it. With this understanding, the welds obtained offer fatigue characteristics comparable with those obtained in hyperbaric welding.

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

    Microsoft Academic Search

    Jun Yan; Ming Gao; Xiaoyan Zeng

    2010-01-01

    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

  11. Influences of welding processes on fatigue life of cruciform joints of pressure vessel grade steels containing LOP defects

    Microsoft Academic Search

    V Balasubramanian; B Guha

    2000-01-01

    The influences of two welding processes, namely, shielded metal arc welding (SMAW) and flux cored arc welding (FCAW), on fatigue life of cruciform joints, containing lack of penetration (LOP) defects, have been studied. Load carrying cruciform joints were fabricated from high strength, quenched and tempered steels of pressure vessel (ASTM 517 ‘F’) grade. Fatigue crack growth experiments were carried out

  12. A Finite Element Calculation of Stress Intensity Factors of Cruciform and Butt Welded Joints for Some Geometrical Parameters

    Microsoft Academic Search

    A. M. Al-Mukhtar; S. Henkel; H. Biermann; P. Hübner; M. S. Samhouri; A. Al-Ghandoor; R. H. Fouad; M. A. Ali; J. Chebil; G. Noel; M. Mesbah; M. Deriche; A. Omran; M. Bayoumi; A Kassem; G. El-Bayoumi

    2009-01-01

    With welded joints, stress concentrations occur at the weld toe and at the weld root, which make these regions the points from which fatigue cracks may initiate. To calculate the fatigue life of welded structures and to analyze the progress of these cracks using fracture mechanics technique requires an accurate calculation of the stress intensity factor SIF. The existing SIFs

  13. Microstructure and Mechanical Properties of 316L Stainless Steel Filling Friction Stir-Welded Joints

    NASA Astrophysics Data System (ADS)

    Zhou, L.; Nakata, K.; Tsumura, T.; Fujii, H.; Ikeuchi, K.; Michishita, Y.; Fujiya, Y.; Morimoto, M.

    2014-10-01

    Keyhole left at 316L stainless steel friction stir welding/friction stir processing seam was repaired by filling friction stir welding (FFSW). Both metallurgical and mechanical bonding characteristics were obtained by the combined plastic deformation and flow between the consumable filling tool and the wall of the keyhole. Two ways based on the original conical and modified spherical keyholes, together with corresponding filling tools and process parameters were investigated. Microstructure and mechanical properties of 316L stainless steel FFSW joints were evaluated. The results showed that void defects existed at the bottom of the refilled original conical keyhole, while excellent bonding interface was obtained on the refilled modified spherical keyhole. The FFSW joint with defect-free interface obtained on the modified spherical keyhole fractured at the base metal side during the tensile test due to microstructural refinement and hardness increase in the refilled keyhole. Moreover, no ? phase but few Cr carbides were formed in the refilled zone, which would not result in obvious corrosion resistance degradation of 316L stainless steel.

  14. Fracture Mechanics of Linearly Welded Wood Joints: Effect of Wood Species and Grain Orientation

    Microsoft Academic Search

    P. Omrani; H. R. Mansouri; G. Duchanois; A. Pizzi

    2009-01-01

    The energy release rates of beech, oak and pine wood specimens welded by linear friction were determined using double cantilever beam (DCB) tests. The influence of grain orientation both in welding along the wood longitudinal direction as well as in end-grain-to-end-grain welding to give butt joints was determined. The analysis of results was done with the experimental compliance method, based

  15. Interface microstructure and mechanical properties of laser welding copper–steel dissimilar joint

    Microsoft Academic Search

    Chengwu Yao; Binshi Xu; Xiancheng Zhang; Jian Huang; Jun Fu; Yixiong Wu

    2009-01-01

    Relatively the high reflectivity of copper to CO2 laser led to the difficulty in joining copper to steel using laser welding. In this paper, a new method was proposed to complete the copper–steel laser butt welding. The scarf joint geometry was used, i.e., the sides of the copper and steel were in obtuse and acute angles, respectively. During the welding

  16. Microstructural zones and tensile characteristics of friction stir welded joint of TC4 titanium alloy

    Microsoft Academic Search

    Hui-jie LIU; Li ZHOU

    2010-01-01

    TC4 titanium alloy was friction stir welded using a W-Re pin tool, and the defect-free weld was produced with proper welding parameters. The joint consists of stir zone, heat affected zone and base material. The stir zone is characterized by equiaxed dynamically recrystallized a phases and transformed ? phases with fine a+? lamellar microstructure. The microstructure of the heat-affected zone

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

    Microsoft Academic Search

    Wei Zhou; K. G. Chew

    2003-01-01

    Impact toughness of a gas tungsten arc welded Ti–6Al–4V alloy butt-joint was evaluated at room temperature using standard Charpy V-notch specimens. The Charpy specimens were prepared with notch roots located either in the parent metal, in the heat-affected zone (HAZ), or in the weld metal. Optical metallography and Vickers microhardness test showed that the weld metal has the coarsest grains

  18. Welding in narrow partings of longitudinal and annular butt joints of thick low-alloy steel

    Microsoft Academic Search

    I. S. Vlas'ev; Z. V. Geinish; G. N. Gorkunenko; V. M. Stepanov

    1986-01-01

    fected zone; to waive subsequent heat treatment of the welded joints; to reduce the weight of the built-up metal by a factor of 2.5; to reduce the amount of machining of the welding edges by a factor of 1.5; and to reduce shrinkage of the metal. As a result of past research [1-3], welding in a narrow parting began to

  19. Fusion Zone Microstructures of Laser and Plasma Welded Dissimilar Steel Joints

    Microsoft Academic Search

    Z. Sun

    1999-01-01

    Dissimilar steel joints between 13CrMo44 low-alloyed ferritic steel and A1SI 347 austenitic stainless steel were produced using laser beam and plasma arC welding. Both autogenous welding (without Filler) and welding with nickel-based filler wire were employed in each process. Fusion zone microstructures were characterized using both optical and scanning electron microscopy. Compositional analysis was performed using scanning electron microscopy. Hardness

  20. Metal magnetic memory testing of welded joints of ferritic and austenitic steels

    Microsoft Academic Search

    Maciej Roskosz

    2011-01-01

    The method of the metal magnetic memory testing is a passive method of non-destructive testing based on the residual magnetic field (RMF) of a component. It allows the localization of stress concentration zones in the objects under examination. The defects in welded joints are places of stress concentration. Also, due to the geometric notch effect and thermal deformations after welding,

  1. Fatigue life improvement of AISI 304L cruciform welded joints by cryogenic treatment

    Microsoft Academic Search

    P Johan Singh; B Guha; D. R. G Achar

    2003-01-01

    Existing theories and reported practical experience show that cryogenic processing greatly increases abrasion resistance and contact fatigue resistance of some metals and alloys. In the present work, an attempt has been made to investigate the effect of cryogenic treatment on the axial fatigue performance of fillet welded cruciform joints of AISI 304L stainless steel, which failed in the weld metal.

  2. Experimental and numerical study of static and fatigue properties of titanium alloy welded joints

    Microsoft Academic Search

    C. Casavola; C. Pappalettere; F. Tattoli

    2009-01-01

    Titanium and its alloys have high specific strength, good mechanical properties at high temperature, high resistance to corrosion and to attack by most acid solutions. Such characteristics make this material attractive for numerous applications because of recent improvements in welding techniques that allow to realize high quality welded joints. For example, new utilizations of titanium alloys are currently being studied

  3. Experimental study on repair of fatigue cracks at welded web gusset joint using CFRP strips

    Microsoft Academic Search

    Hitoshi Nakamura; Wei Jiang; Hiroyuki Suzuki; Ken-ichi Maeda; Takao Irube

    2009-01-01

    This paper presents repair methods of fatigue cracks using CFRP strips. In particular, the subject of repair is fatigue cracks initiated at welded web gusset joints, which are the typical details in steel bridges. Several repair methods were investigated experimentally focusing on weld details. In addition, more effective repair methods were also investigated using combination of CFRP strips and drill-holes.

  4. Stress relieving and its effect on life of welded tubular joints

    Microsoft Academic Search

    A. M. Paradowska; J. W. H. Price; B. Kerezsi; P. Dayawansa; X.-L. Zhao

    2010-01-01

    This paper describes investigations into the fabrication and repair of large welded tubular joints and how the processes used affect fatigue life. Research has been conducted to determine the benefit of local post weld heat treatment (PWHT) of the connections in terms of hardness and residual stress. The use of hole drilling and trepanning techniques for residual stresses measurements in

  5. Analysis of non-loading carrying fillet welds joint using SGBEM

    Microsoft Academic Search

    Xu Kai; Lu Yong; S. T. Lie

    2004-01-01

    Fatigue failure is probably the most common type of failure in welded construction. It is usually initiates at a stress concentration area within the structure. The fatigue behavior of non-load carrying cruciform fillet welded joint has been studied extensively using boundary element method. The symmetric boundary element method for multiple cracks problem is derived using Betti's reciprocal theorem in auxiliary

  6. A simplified fatigue assessment method for high quality welded cruciform joints

    Microsoft Academic Search

    T. Nykänen; G. Marquis; T. Björk

    2009-01-01

    The primary goal of this study was to develop an equation relating the geometric parameters to fatigue strength which can be used is routine design assessment. To attain this, the influence of local geometrical weld variations on the fatigue strength of non-load-carrying cruciform fillet welded joints were systematically studied using plane strain linear elastic fracture mechanics (LEFM). The effects of

  7. Comparison of fatigue life for T and cruciform welded joints with different combinations of geometrical parameters

    Microsoft Academic Search

    A. Khodadad Motarjemi; A. H Kokabi; F. M Burdekin

    2000-01-01

    The fatigue life for T and cruciform welded joints containing different extents of lack of root penetration was calculated for different combinations of geometrical parameters, including thicknesses up to 45 mm, by integration of the Paris law and use of stress intensity factor solutions calculated previously. The effect of attachment and main plate thickness, weld leg length and initial lack

  8. HIGH CYCLE FATIGUE BEHAVIOUR OF WELDED JOINTS BASED ON NOTCH STRESS INTENSITY FACTORS

    Microsoft Academic Search

    B. Atzori; P. Lazzarin; R. Tovo

    The present paper summarises the application of NSIF approach to stress analysis and high cycle fatigue assessment of welded joints. This approach is based on linear elastic stress analysis of the open sharp corner defined at the weld toe; in that corner the NSIFs evaluate the intensity of the stress singularity similarly to the evaluation of the stress field ahead

  9. 46 CFR 154.524 - Piping joints: Welded and screwed couplings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS...Equipment Cargo and Process Piping Systems § 154.524 Piping joints: Welded...d) Screwed couplings are allowed for instrumentation and control piping that meets §...

  10. 46 CFR 154.524 - Piping joints: Welded and screwed couplings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS...Equipment Cargo and Process Piping Systems § 154.524 Piping joints: Welded...d) Screwed couplings are allowed for instrumentation and control piping that meets §...

  11. 46 CFR 154.524 - Piping joints: Welded and screwed couplings.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS...Equipment Cargo and Process Piping Systems § 154.524 Piping joints: Welded...d) Screwed couplings are allowed for instrumentation and control piping that meets §...

  12. 46 CFR 154.524 - Piping joints: Welded and screwed couplings.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS...Equipment Cargo and Process Piping Systems § 154.524 Piping joints: Welded...d) Screwed couplings are allowed for instrumentation and control piping that meets §...

  13. 46 CFR 154.524 - Piping joints: Welded and screwed couplings.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR SELF-PROPELLED VESSELS...Equipment Cargo and Process Piping Systems § 154.524 Piping joints: Welded...d) Screwed couplings are allowed for instrumentation and control piping that meets §...

  14. 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.

  15. Crack propagation analysis of welded thin-walled joints using boundary element method

    Microsoft Academic Search

    F. R. Mashiri; Xiao-Ling Zhao; P. Grundy

    2000-01-01

    Tube-to-plate nodal joints under cyclic bending are widely used in the road transport and agricultural industry. The square\\u000a hollow sections (SHS) used in these constructions are thin-walled and cold formed, and they have thicknesses of less than\\u000a 4?mm. Some fatigue failures have been observed. The weld undercut may affect the fatigue life of welded tubular joints especially\\u000a for thin-walled sections.

  16. ANALYSIS OF SPOT WELD JOINTS BY ULTRASONIC INSPECTION, FEM AND RESIDUAL STRESS MEASUREMENTS

    Microsoft Academic Search

    D. Stocco; R. Magnabosco; R. M. Barros

    The present work seeks to determine the parameters for approval, through ultrasonic techniques, of spot welded joints of low carbon steel sheets. For such experience the mechanical behavior of a spotwelded joint was characterized under fatigue, in load cycles ranging from zero to 14 kN, on sheets of 1.5 mm thickness, joined by three spot welds of 7.5 mm of

  17. 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.

  18. Microstructural evolution under dual ion irradiation and in-reactor creep of type 316 stainless steel welded joints*1

    NASA Astrophysics Data System (ADS)

    Kohyama, A.; Kohno, Y.; Hishinuma, A.

    1994-09-01

    Electron beam (EB) welding was applied to 316SS and the titanium modified 316SS (JPCA). For the prospective improvement of swelling in welded joints, modified TIG or EB welding procedures utilizing titanium or nickel foil insertion were employed. For the case of EB welding of 15 mm thickness I-butt joint, the higher weld heat input showed better swelling resistance in the joints. The in-reactor creep results suggest that irradiation creep in welded joints may not be a big concern, as far as swelling resistance is maintained. So, Ni addition, stress relief treatment and high heat input for EB welding with optimization of welding condition are recommended for suppressing irradiation creep and swelling.

  19. 46 CFR 56.30-5 - Welded joints.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...accordance with part 57 of this subchapter. (b) Butt welds—general. Butt welds may be made with or without backing or insert...insert rings must be used. Commonly used types of butt welding end preparations are shown in ASME...

  20. 46 CFR 56.30-5 - Welded joints.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...accordance with part 57 of this subchapter. (b) Butt welds—general. Butt welds may be made with or without backing or insert...insert rings must be used. Commonly used types of butt welding end preparations are shown in ASME...

  1. 46 CFR 56.30-5 - Welded joints.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...accordance with part 57 of this subchapter. (b) Butt welds—general. Butt welds may be made with or without backing or insert...insert rings must be used. Commonly used types of butt welding end preparations are shown in ASME...

  2. Fatigue life assessment of load-carrying fillet-welded cruciform joints inclined to uniaxial cyclic loading

    Microsoft Academic Search

    In-Tae Kim; Shigenobu Kainuma

    2005-01-01

    This study examines, the relationship between the direction of an applied stress cycle and the fatigue behaviour of load-carrying fillet-welded cruciform joints with weld root cracks, and presents the fatigue life assessment of the joints. Fatigue tests were performed on four sets of cruciform joints inclined at an angle of 0, 15, 30, or 45° to the normal direction of

  3. Analysing the influences of weld size on fatigue life prediction of FCAW cruciform joints by strain energy concept

    Microsoft Academic Search

    V Balasubramanian; B Guha

    1999-01-01

    The effect of weld size on fatigue life of flux cored arc welded (FCAW) cruciform joints containing lack of penetration (LOP) defect has been analysed by using the strain energy density factor (SEDF) concept. Moreover, new fracture mechanics equations have been developed to predict the fatigue life of the cruciform joints. Load carrying cruciform joints were fabricated from ASTM 517

  4. Fatigue strength of cruciform and other fillet welded joints in aluminum alloys

    NASA Astrophysics Data System (ADS)

    1992-08-01

    ESDU 92017 presents the results extracted from the literature of nearly 850 constant amplitude loading fatigue tests. Joints were load-carrying and non load-carrying transverse cruciform, load-carrying and non load-carrying transverse and longitudinal cover plate, and single- and double-fillet lap under axial loading. Data are included on fillet welded attachments under axial loading and tee fillet welded joints under either axial or bending loading. The effect of mean stress is shown for cruciform and cover plate joints, and the effect of post-weld treatments (shot peening and tungsten-inert-gas dressing) is shown for some cover plate joints. The joints were in twelve alloys in the 5000, 6000, or 7000 series with fillers in the 5000 series. All welding process variables and geometries are detailed and the location of failure is indicated. A table summarizes fatigue strengths at lives of a million and 10 million cycles for stress ratios of zero and -1. Summary graphs compare the scatter bands for all joint types in all materials and also mean fatigue strength curves for all types in alloy 5083. A graph also shows the influence of parent alloy tensile strength on welded joint fatigue strength.

  5. 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

  6. 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.

  7. 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.

  8. 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

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

    NASA Astrophysics Data System (ADS)

    Rule, William K.

    1992-12-01

    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. 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.

  10. 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.

  11. Numerical study of strengths of spot-welded joints of steel

    Microsoft Academic Search

    X. Kong; Q. Yang; B. Li; G. Rothwell; R. English; X. J. Ren

    2008-01-01

    A resistance spot-welding (RSW) joint consists of several material zones with different microstructure and properties as a result of the thermal, metallurgical and mechanical deformation process. Detailed material properties are essential to accurately simulate the mechanical behavior of a joint and its dependency on some key structural parameters (e.g. nugget size, sheet thickness etc.). The work presented in this paper

  12. The fatigue life improvement of high strength steel welded joints using hammer peening techniques

    SciTech Connect

    Bell, R.; Militaru, D.V. [Carleton Univ., Ottawa, Ontario (Canada). Dept. of Mechanical and Aerospace Engineering; Braid, J.E.M. [Canada Centre for Materials and Metals Technology, Ottawa, Ontario (Canada). Metals Technology Labs.

    1995-12-31

    The fatigue strength of welded joints can be substantially improved by a number of methods. This paper will investigate the high cycle fatigue strength that is attainable in joints of high strength steels in the as-welded and hammer peened condition. A T-joint with a longitudinal fillet weld representing a stiffener or bracket end structural detail was selected for testing. These details are typical of joints found in ships, bridges and decks of offshore platforms. The specimens were fabricated from 350 MPa and 550 MPa yield strength grade steels and were loaded through the vertical member. During fatigue testing at several load levels the crack growth and crack shape development were monitored using potential drop and benchmarking techniques.

  13. Investigation of welding parameter dependent microstructure and mechanical properties in friction stir welded pure Ti joints

    Microsoft Academic Search

    Hidetoshi Fujii; Yufeng Sun; Hideaki Kato; Kazuhiro Nakata

    2010-01-01

    Commercial purity titanium plates with 2mm in thickness were successfully friction stir butt-welded at a welding speed ranged from 50 to 300mm\\/min. The measured peak temperatures during all the welding processes were below the ?\\/? phase transformation point. The microstructural characterization revealed that the stir zone has an equiaxial grain structure and low density of dislocations at lower welding speed,

  14. Life improvement and repair of fatigue cracks in welded joints by hammer peening

    SciTech Connect

    Haagensen, P.J. [Norwegian Inst. of Technology, Trondheim (Norway). Dept. of Civil Engineering

    1995-12-31

    Hammer peening is an effective method for extending the life of welded joints by the introduction of a deep compressive stress field which delays crack growth. In this paper hammer peening is examined as a repair method for cracks in welded T-joints. Fatigue cracks were grown is as-welded joints to depths from approximately 0.5 mm to 2 mm. The crack line was then hammer peened following typical peening procedures. The remaining fatigue life of components with untreated cracks of these sizes would constitute from a few hundred cycles to a few percent of the told life. The fatigue strength of the repaired specimens was compared with data from earlier tests on as-welded specimens and specimens that had been improved by weld toe grinding followed by hammer peening. All tests were carried out at constant amplitude loading in air. The material was a low carbon micro alloyed steel of 360 MPa yield strength. The specimens were T-joints with non-load carrying welds loaded in four point bending.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  16. High temperature low-cycle fatigue of friction welded joints - type 304-304 stainless steel and alloy 718-718 nickel base superalloy

    SciTech Connect

    Wakai, T. (Power Reactor and Nuclear Fuel Development Corp., Ibaraki (Japan). Oarai Engineering Center); Sakane, M.; Ohnami, M. (Ritsumeikan Univ., Kyoto (Japan). Dept. of Mechanical Engineering); Okita, K. (Hyogo Prefectural Inst. of Industrial Research, Miki (Japan). Technical Center for Machinery and Metals); Fukuchi, Y. (Hyogo Prefectural Inst. of Industrial Research, Kobe (Japan))

    1993-01-01

    This paper assesses the high-temperature low-cycle fatigue of the Type 304 stainless steel and Alloy 718 superalloy friction-welded joints. Strain controlled low-cycle fatigue tests for 304-304 and 718-718 friction-welded specimens were carried out at 923 K in air to obtain the fatigue strength of the joints. These materials were selected as the cyclic hardening and softening materials, respectively. The 304-304 welded specimens showed inferior fatigue strength in comparison with the base metal while the 718-718 specimens exhibited fatigue strength equivalent to that of the base metal. The difference in the fatigue strength between the two materials is discussed from the viewpoint of the cyclic deformation behavior and strain reduction at weld interface.

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

    NASA Astrophysics Data System (ADS)

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

    2010-11-01

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

  18. 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.

  19. 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.

  20. Experimental investigations on welded double lap joints composed of timber

    Microsoft Academic Search

    Benjamin Hahn; Yves Weinand; Bernhard Stamm; Till Vallée

    2011-01-01

    Fabrication of wood-to-wood connections by means of friction welding is an relatively new process holding high potential for development. To connect wooden pieces by means of friction welding, they are initially pressed against each other. The rapid movement of one of the pieces, applied simultaneously leads to friction, and heating generation, which is softening the material at the interface within

  1. Small-scale resistance spot welding of austenitic stainless steels

    Microsoft Academic Search

    Shinji Fukumoto; Kana Fujiwara; Shin Toji; Atsushi Yamamoto

    2008-01-01

    Small-scale resistance spot welding (SSRSW) was carried out for austenitic stainless steels. A weld lobe that shows the process window for making sound joints was obtained for type 304 stainless steel thin sheets, and the effects of welding current, force and weld time on joint strength and nugget size were investigated. The cooling rate that was estimated from the solidification

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

    SciTech Connect

    Shen, Junjun, E-mail: junjun.shen@hzg.de; Suhuddin, Uceu F. H.; Cardillo, Maria E. B.; Santos, Jorge F. dos [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Materials Mechanics, Solid-State Joining Processes, Max-Planck-Str. 1, 21502 Geesthacht (Germany)

    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.

  3. Finite element analysis of an inelastic interface in ultrasonic welded metal\\/fibre-reinforced polymer joints

    Microsoft Academic Search

    N. Konchakova; F. Balle; F. J. Barth; R. Mueller; D. Eifler; P. Steinmann

    2010-01-01

    The ultrasonic welding technology is an innovative method to produce hybrid joints for multi-material components. In this contribution, the behaviour of an interface layer of metal\\/fibre-reinforced polymer single overlap tensile specimens is considered. The investigations are carried out using the ultrasonic metal welding technique (UMW) for joining carbon fibre reinforced thermoplastic composites (CFRP) with aluminium alloys. An interfacial traction-separation-law based

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    A dissimilar joint of AA5083 Al alloy and copper was produced by friction spot welding. The Al-MgCuAl2 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.

  5. Analysis of residual stresses in thick aluminum friction stir welded butt joints

    Microsoft Academic Search

    Weifeng Xu; Jinhe Liu; Hongqiang Zhu

    2011-01-01

    Plates of aluminum alloys 2219-T62 were joined in a butt joint by friction stir welding. The residual stresses on the top and bottom surfaces were measured using the hole-drilling strain-gauge method. In the test specimen, it was found that the residual stresses on the top surface peaked at about 171MPa, while the value reached 243MPa for the weld with tunnel

  6. Microstructure evolution of electron beam welded Ti{sub 3}Al-Nb joint

    SciTech Connect

    Feng Jicai [State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001, Heilongjiang Province (China); Wu Huiqiang [State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001, Heilongjiang Province (China)]. E-mail: huiqiang_wu@hit.edu.cn; He Jingshan [State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001, Heilongjiang Province (China); Zhang Bingang [State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001, Heilongjiang Province (China)

    2005-02-15

    The microstructure evolution characterization in high containing Nb, low Al titanium aluminide alloy of electron beam welded joints was investigated by means of OM, SEM, XRD, TEM and microhardness analysis. The results indicated that the microstructure of the weld metal made with electron beam under the welding conditions employed in this work was predominantly metastable, retaining ordered {beta} phase (namely B2 phase), and was independent of the welding parameters but independent of the size and the orientation of the weld solidification structures. As the heat input is decreased, the cellular structure zone is significantly reduced, and then the crystallizing morphology of fusion zone presented dendritically columnar structure. There existed grain growth coarsening in heat affected zone (HAZ) for insufficient polygonization. Both fusion zone (FZ) and the HAZ had higher microhardness than the base metal.

  7. Characterization of microstructure, mechanical properties and corrosion resistance of dissimilar welded joint between 2205 duplex stainless steel and 16MnR

    Microsoft Academic Search

    Shaogang Wang; Qihui Ma; Yan Li

    2011-01-01

    The joint of dissimilar metals between 2205 duplex stainless steel and 16MnR low alloy high strength steel are welded by tungsten inert gas arc welding (GTAW) and shielded metal arc welding (SMAW) respectively. The microstructures of welded joints are investigated using scanning electron microscope, optical microscope and transmission electron microscopy respectively. The relationship between mechanical properties, corrosion resistance and microstructure

  8. 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.

  9. Low cycle fatigue strength of butt-welded steel joint by means of new testing system with image technique

    Microsoft Academic Search

    Kazuo Tateishi; Takeshi Hanji

    2004-01-01

    In this study, we investigated the low cycle fatigue strength of welded joints using a new fatigue testing system in which the image analysis technique was used to measure the strains in specimens. After checking the validity of the testing system, we used this new system to conduct fatigue tests on welded joint specimens. The test results indicate that the

  10. Effect of protective atmosphere composition during welding on the strength of welded niobium alloy joints

    Microsoft Academic Search

    M. D. Rabkina; M. M. Nerodenko; S. M. Gurevich; É. S. Umanskii; V. K. Kharchenko; V. V. Krivenyuk; G. É. Cholovskii; G. A. Petrunin; N. F. Chugai

    1984-01-01

    Conclusions 1.Saturation of niobium alloys with nitrogen and oxygen during welding leads to the appearance of clearly defined peaks on the temperature dependence curves for ultimate strength.2.As a result of arc welding in a protective controlled helium atmosphere dosed with oxygen and nitrogen (from 0.001 to 1 vol.% of each), saturation of weld metal with impurities, which is possible with

  11. An elastic-plastic fracture mechanics analysis of weld-toe surface cracks in fillet welded T-butt joint

    SciTech Connect

    Fu, B. [British Gas plc, Newcastle upon Tyne (United Kingdom). Engineering Research Station

    1994-12-31

    This paper describes an elastic-plastic fracture mechanics (EPFM) study of shallow weld-toe cracks. Two limiting crack configurations, plane strain edge crack and semi-circular surface crack in fillet welded T-butt plate joint, were analyzed using the finite element method. Crack depth ranging from 2 to 40% of plate thickness were considered. The elastic-plastic analysis, assuming power-law hardening relationship and Mises yield criterion, was based on incremental plasticity theory. Tension and bending loads applied were monotonically increased to a level causing relatively large scale yielding at the crack tip. Effects of weld-notch geometry and ductile material modeling on prediction of fracture mechanics characterizing parameter were assessed. It was found that the weld-notch effect reduces and the effect of material modeling increases as crack depth increases. Material modeling is less important than geometric modeling in analysis of very shallow cracks but is more important for relatively deeper cracks, e.g. crack depth more than 20% of thickness. The effect of material modeling can be assessed using a simplified structural model. Weld magnification factors derived assuming linear elastic conditions can be applied to EPFM characterization.

  12. Microstructures and Mechanical Properties of Electron Beam-Welded Titanium-Steel Joints with Vanadium, Nickel, Copper and Silver Filler Metals

    NASA Astrophysics Data System (ADS)

    Wang, Ting; Zhang, Binggang; Wang, Houqin; Feng, Jicai

    2014-04-01

    Electron beam welding experiments of titanium alloy to stainless steel with V, Ni, Cu and Ag filler metals were carried out. The interfacial microstructures of the joints were examined by optical microscopy, scanning electron microscopy, and x-ray diffraction analysis. Mechanical properties of the joints were evaluated according to tensile strength and microhardness. The results showed that all the filler metals were helpful to restrain the Ti-Fe intermetallics formed in the Ti/Fe joint. The welds with different filler metals were all characterized by solid solution and interfacial intermetallics. And the type of solid solution and interfacial intermetallics were depended on the metallurgical reactions between the filler metals and base metals. The interfacial intermetallics were Fe2Ti + Ni3Ti + NiTi2, TiFe, Ti2Ag, and Cu2Ti + CuTi + CuTi2 in the joints welded with Ni, V, Ag, and Cu filler metals, respectively. The tensile strengths of the joints were primarily determined by the hardness of the interfacial intermetallics. The highest tensile strength was obtained in the joint welded with silver filler metal, which is about 310 MPa.

  13. The role of residual stress and heat affected zone properties on fatigue crack propagation in friction stir welded 2024-T351 aluminium joints

    Microsoft Academic Search

    G Bussu; P. E Irving

    2003-01-01

    The effects of weld residual stress and heat affected zone on the fatigue propagation of cracks parallel and orthogonal to the weld direction in friction stir welded (FSW) 2024-T351 joints were investigated. Crack propagation behaviour was sensitive to both weld orientation and the distance of the crack from the weld line. Growth rates both faster and slower than in the

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

    NASA Astrophysics Data System (ADS)

    Tabuchi, Masaaki; Hongo, Hiromichi; Abe, Fujio

    2014-10-01

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

  15. Missed joint induced by thermoelectric magnetic field in electron-beam welding dissimilar metals—Experiment and scale analysis

    Microsoft Academic Search

    P. S. Wei; Chih-Wei Wen

    2002-01-01

    A missed joint, resulting from an induced thermoelectric magnetism in welding dissimilar metals with a high-intensity electron\\u000a beam, is experimentally and analytically investigated. Election-beam welding is a very useful process for joining a wide range\\u000a of dissimilar metals, which may be difficult or impossible to weld by other techniques. Certain combinations of materials,\\u000a unfortunately, readily give rise to a missed-joint

  16. Effect of Welding Parameters on Microstructure, Thermal, and Mechanical Properties of Friction-Stir Welded Joints of AA7075-T6 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Lotfi, Amir Hossein; Nourouzi, Salman

    2014-06-01

    A high-strength Al-Zn-Mg-Cu alloy AA7075-T6 was friction-stir welded with various process parameter combinations incorporating the design of the experiment to investigate the effect of welding parameters on the microstructure and mechanical properties. A three-factors, five-level central composition design (CCD) has been used to minimize the number of experimental conditions. The friction-stir welding parameters have significant influence on the heat input and temperature profile, which in turn regulates the microstructural and mechanical properties of the joints. The weld thermal cycles and transverse distribution of microhardness of the weld joints were measured, and the tensile properties were tested. The fracture surfaces of tensile specimens were observed by a scanning electron microscope (SEM), and the formation of friction-stir processing zone has been analyzed macroscopically. Also, an equation was derived to predict the final microhardness and tensile properties of the joints, and statistical tools are used to develop the relationships. The results show that the peak temperature during welding of all the joints was up to 713 K (440 °C), which indicates the key role of the tool shoulder diameter in deciding the maximum temperature. From this investigation, it was found that the joint fabricated at a rotational speed of 1050 rpm, welding speed of 100 mm/min, and shoulder diameter of 14 mm exhibited higher mechanical properties compared to the other fabricated joints.

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

    SciTech Connect

    Milewski, J. O. (John 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.

  18. Residual stresses analysis of ND-YAG laser welded joints

    Microsoft Academic Search

    J. M. Costa; J. T. B. Pires; F. Antunes; J. P. Nobre; L. P. Borrego

    2010-01-01

    Laser deposit welding based on modern ND-YAG lasers is a new mould repair process with advantages relatively to the traditional methods (micro-plasma and TIG methods), namely deposition of small volumes of the filler material without distortion. Residual stresses play a major role on the fatigue and thermal–mechanical fatigue behaviour of welds. This paper presents the experimental results and numerical predictions

  19. Effects of defect size in root region on fatigue strength of fillet welded joints—root failure of non?load?carrying cruciform fillet welded joints due to toe treatment (2 report)

    Microsoft Academic Search

    S. Ohta; H. Kitamura

    1994-01-01

    This paper describes an investigation of the effects of the defect size in the root region on the fatigue strength of non?load?carrying cruciform fillet welded joints by FEM analysis, fatigue tests, and hardness tests. The results may be summarised as follows. 1. Through TIG dressing of the toe region of fillet welded joints, joints have a fatigue limit of 1.4?2.5

  20. Columnar jointing in non-welded Cerro Galan ignimbrite: Paycuqui, Argentina

    NASA Astrophysics Data System (ADS)

    Wright, H. M.; Cas, R.; Lesti, C.; Viramonte, J.; Folkes, C.; Porreca, M.

    2007-12-01

    Well-developed columnar joint sets are thought to occur most commonly in moderately to densely welded facies of ignimbrites. Columnar joints in welded deposits form when sintering between juvenile grains provides sufficient cohesion to allow thermal volume contraction to be accommodated in brittle fracture. However, well- developed columnar joints can also form in unwelded deposits, where cohesion is produced by high temperature devitrification of the deposit. Such is the case at Paycuqui, Argentina, in the Cerro Galan ignimbrite. The Cerro Galan ignimbrite is a very large volume rhyodacitic pyroclastic flow deposit (>1000 km3), which erupted ~2.3 Ma. At the Paycuqui locality, 29 km west of the caldera margin, the flow is valley-confined and is over 30 m thick. The deposit is massive, pumice-poor, lithic-poor, crystal-rich, and contains well-developed joint sets in the upper 15m. Remant magnetization analyses of incorporated lithics indicate high temperature emplacement. However, welding deformation and sintering textures are absent. Instead, textural differences between the nonjointed base and the jointed top of the ignimbrite are coincident with devitrification variations, inluding dominant cryptocrystalline sanidine and crystobalite that increase in abundance upwards in the section. The presence of a 1mm wide, more devitrified zone along columnar joint faces constrains the timing of high temperature devitrification. Devitrification must have begun prior to brittle fracture and continued after joints had formed. The morphology of joints at Paycuqui differs from well-described joint sets elsewhere. The average diameter of polygons is 0.75 m. Intersecting columnar joint surfaces at Paycuqui form polygons with fewer sides (mean of 4.5 sides) than on many lava flows or than predicted in models. These polygonal patterns vary within the flow due to the presence of vertical, rose-shaped, and radiating joints. Such complexities may result from fumarolic vapor rise.

  1. 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.

  2. 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.

  3. 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.

  4. Effect of rotation speed on microstructure and mechanical properties of Ti–6Al–4V friction stir welded joints

    Microsoft Academic Search

    L. Zhou; H. J. Liu; Q. W. Liu

    2010-01-01

    The effect of tool rotation speed on microstructure and mechanical properties of friction stir welded joints was investigated for Ti–6Al–4V titanium alloy. Joints were produced by employing rotation speeds ranging from 400 to 600rpm at a constant welding speed of 75mm\\/min. It was found that rotation speed had a significant impact on microstructure and mechanical properties of the joints. A

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

    SciTech Connect

    Shah, Bhavesh [General Motors Corporation-R& D; Frame, Barbara J [ORNL; Dove, Caroline [ACC, USCAR; Fuchs, Hannes [Multimatic Engineering

    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.

  6. Effectiveness of grinding and peening techniques for fatigue life extension of welded joints

    SciTech Connect

    Haagensen, P.J. [Univ. of Trondheim (Norway)

    1994-12-31

    Weld improvement methods can be used to upgrade existing structures and to repair weldments containing fatigue cracks. Some methods are suitable for use underwater to repair damaged structures. The fatigue strength properties of as-welded specimens and specimens improved by weld toe grinding, and toe grinding combined with hammer peening were investigated in constant amplitude tests in air. The material was a low carbon microalloyed steel of 360 MPa yield strength. The specimens were non-load carrying T-joints that were loaded in four point bending. The effectiveness of weld toe grinding and grinding combined with hammer peening to repair fatigue cracks was examined in tests on specimens with simulated fatigue cracks repaired by grinding followed by hammer peening.

  7. High Density Panels Obtained by Welding of Wood Veneers without any Adhesives

    Microsoft Academic Search

    H. R. Mansouri; J.-M. Leban; A. Pizzi

    2010-01-01

    High density panels obtained by pressing wood veneers together in plywood or laminated veneer lumber (LVL) assembly configurations, at temperatures of 225°C to 250°C, high pressure and long press times, as long as 60 min or longer, have been shown by tensile tests, X-ray microdensitometry and scanning electron microscopy to present interphases where wood has welded just by application of

  8. Fatigue Strength Evaluation of Spot-Welded Multi-Lap Joint by the Maximum Stress Intensity Factor, K?max

    NASA Astrophysics Data System (ADS)

    Bae, Dongho; Nam, Taehun; Jung, Wonseok; Sohn, Ilseon

    Fatigue strength and reliability of structural components in railroad commercial vehicles are usually decided by spot weld. Thus, it is very important to develop a fatigue design method for spot welded multi-lap joints in railroad commercial vehicles. The objective of this paper is to provide an integrated fatigue design criterion for spot-welded multi-lap joints used in the body of railroad commercial vehicles. Based on finite element analysis, the fatigue life data for spot-welded multi-lap joints is correlated in terms of the maximum stress intensity factor, K?max, that is the fracture mechanical parameter. From the results, using ? K?max - Nf relationship, a proper fatigue life design rule independent on geometric variables and material properties for components having spot welded multi-lap joints can be established.

  9. 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.

  10. Mechanical properties of laser-pressure-welded joint between dissimilar galvannealed steel and pure aluminium

    Microsoft Academic Search

    Koji Nishimoto; Tomoki Harano; Yoshihiro Okumoto; Ken Atagi; Hiroo Fujii; Seiji Katayama

    2009-01-01

    Dissimilar metal joints of Zn-coated Galvannealed steel (GA steel) and commercially available pure aluminium (A1050) sheets were produced by changing the laser power and the roller pressure by the laser pressure welding method. By this method, the YAG laser beam was irradiated into a flare groove made by these dissimilar metal sheets. In addition, the laser beam was scanned at

  11. Enhancing water resistance of welded dowel wood joints by acetylated lignin

    Microsoft Academic Search

    A. Pizzi; X. Zhou; P. Navarrete; C. Segovia; H. R. Mansouri; M. I. Placentia Pena; F. Pichelin

    2012-01-01

    Low molecular mass acetylated organosolv lignin from wheat straw and from depolymerised low sulphur organosolv wood lignin have been shown to markedly improve both the water resistance and the mechanical performance of welded dowel wood joints. The acetylated oligomers distribution and extent of acetylation of the two lignins were determined by Matrix assisted laser desorption ionization-time-of-flight mass spectrometry. Extensive acetylation

  12. Causes for the Improved Water Resistance in Pine Wood Linear Welded Joints

    Microsoft Academic Search

    H. R. Mansouri; A. Pizzi; J. M. Leban; L. Delmotte; O. Lindgren; M. Vaziri

    2011-01-01

    Linear vibration welding of good quality pine (Pinus sylvestris) wood from Sweden containing a small proportion of a native mixture of terpenoic acids, known under the collective name of rosin, has been shown to yield joints of much upgraded water resistance. This has been shown to be due to the protecting influence the molten rosin from the wood itself has

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

    Microsoft Academic Search

    O. Debbouz; F. Navai

    1999-01-01

    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 μm (1 x 10⁻³

  14. Reliability based fatigue design of maintained welded joints in the side shell of tankers

    Microsoft Academic Search

    C. Guedes Soares; Y. Garbatov

    1999-01-01

    The present work deals with the application of reliability based techniques to the design welded joints subjected to the process of crack growth and repair. A formulation is presented for the assessment of the fatigue damage and of the reliability of the side shell of a ship hull structure. The potential cracks are considered to occur in the side shell,

  15. Nondestructive detection of creep and creep-fatigue damages in welded joints by ultrasonic technique

    SciTech Connect

    Okazaki, M. [Nagaoka Univ. of Technology (Japan). Dept. of Mechanical Engineering; Hashimoto, M. [Babcock Hitachi K.K., Kure (Japan). Kure Research Center

    1995-12-01

    The non-destructive detection of creep and creep-fatigue damages was studied by employing an ultrasonic technique, taking account of the applicability to welded joints. Particular attention was paid to the change of ultrasonic wave attenuation and that of the anisotropy during the creep and creep-fatigue failures. The experimental results, using the welded joint of 2 1/4 Cr-1 Mo steel and the dissimilar metal welded joint between 2 1/4 Cr-1 Mo and Type 316 steels, showed that the development process of creep damage ad that of creep-fatigue one were successfully reflected on the change of the ultrasonic attenuation as follows: the ultrasonic wave attenuation remarkably increased with creep and the creep-fatigue damages, especially at the final rupture zone, while the change was not noticeable at the other zones accompanying with negligible damage. In addition, the attenuation exhibited a comparable change to the other useful engineering parameters, such as the A-parameter; i.e., the change was satisfied,or competent for detection. These results indicate that the ultrasonic attenuation properties provide the useful information to detect the creep and creep-fatigue damages nondestructively, as well as to find out the dangerous sites to failure, in welded joints.

  16. Analysis of the S– N curves of welded joints enhanced by ultrasonic peening treatment

    Microsoft Academic Search

    Xiaohui Zhao; Dongpo Wang; Lixing Huo

    2011-01-01

    Contrast fatigue tests were carried out on T-shape tubular joints of 20 steel in three conditions: as welded, treated by ultrasonic peening treatment (UPT) before loading and UPT under loading. Results are: (1) Dispersity of test results measured by nominal stress is much larger than that measured by hot spot stress. After UPT before loading, fatigue strength of 20 steel

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

    Microsoft Academic Search

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

    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.

  18. Assessment of some factors affecting fatigue endurance of welded cruciform joints using statistical techniques

    Microsoft Academic Search

    V. Balasubramanian; B. Guha

    1999-01-01

    Three statistical techniques have been used to optimise some of the factors affecting fatigue life of Flux Cored Arc Welded (FCAW) cruciform joints containing Lack of Penetration (LOP) defects. High strength, quenched and tempered steel (ASTM 517 ‘F’ Grade) has been used as the base material throughout the investigation. Design of Experiments (DoE) concept has been used to optimise the

  19. A fracture mechanics based fatigue life prediction for welded joints of square tubes

    Microsoft Academic Search

    J. M. Ferreira; A. H. Pereira; C. M. Branco

    1995-01-01

    Square tubes of mild and low alloy steels are extensively used in vehicle structures and offshore platforms. Despite this fact the fatigue behaviour of welded nodes of these tubes is not sufficiently known, especially in thin sections.The paper presents the results of fatigue life predictions based on fracture mechanics, in non-load carrying T and also load carrying cruciform joints. The

  20. Bending stresses at longitudinal weld joints of pressurized cylindrical shells due to angular distortion

    Microsoft Academic Search

    L. S. Ong; K. H. Hoon

    1996-01-01

    This article presents a simple second-order theory for the determination of bending stresses which arise at the longitudinal welded joint of a pressurized, cylindrical shell subject to peaking, i.e., angular misalignment. Although this problem has been studied quite extensively over the years by a few authors and a few versions of simple formulas are available for the calculations of bending

  1. A boundary element analysis of misaligned load-carrying cruciform welded joints

    Microsoft Academic Search

    S. T Lie; S Lan

    1998-01-01

    Although it has been found that misalignment of the welded joints can reduce fatigue strength significantly, further studies are still required for comprehensive investigation, including varying geometry variables. In this study, boundary element technique and hypersingular boundary integral equation (HBIE) are employed to calculated the notch stress concentration factors and then predict the fatigue life as this method can lead

  2. The limit of joint penetration in high energy density beam welding

    Microsoft Academic Search

    C. E. Albright; S. Chiang

    1993-01-01

    A theoretical limit of penetration for laser welding (LBW) is established to determine if further gains in joint penetration depth over existing process capability are theoretically possible. The penetration limit is calculated based on an analysis proposed by Swift-Hook and Gick with the assumption that the minimum bead width possible is equal to the diffraction limited focused spot size. The

  3. Fatigue Life Improvement for Cruciform Welded Joint by Mechanical Surface Treatment using Hammer Peening and UNSM

    NASA Astrophysics Data System (ADS)

    Han, Seung-Ho; Han, Jeong-Woo; Nam, Yong-Yun; Cho, In-Ho

    For the improvement of fatigue strength of welded structures, mechanical post treatments have been applied in various industrial fields and have in most cases been founded to give substantial increases in their fatigue lives. These methods, generally, consist of the modification of weld toe geometry and the introduction of compressive residual stresses. In mechanical surface treatments, e.g. PHP (pneumatic hammer peening) and UNSM (ultrasonic nano-crystal surface modification), the weld profile is modified due to remove or reduce minute crack-like flaws, and compressive residual stresses are also induced. In this study, a pneumatic hammer peening procedure and a UNSM device were introduced, and a quantitative measure of fatigue strength improvement was performed. The fatigue strength at 2 × 106 cycles of hammer-peened and UNSM treated on a non-load carrying cruciform welded joint shows 220 and 260MPa, respectively, which are more than two times higher than that of as-welded specimen. Especially, the surface layer in the vicinity weld toe treated by the UNSM provides nano-crystal structure created by an ultrasonic cold forging and introduces very high welding residual stress in compression.

  4. 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.

  5. 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

  6. Missed joint induced by thermoelectric magnetic field in electron-beam welding dissimilar metals—Experiment and scale analysis

    NASA Astrophysics Data System (ADS)

    Wei, P. S.; Wen, Chih-Wei

    2002-10-01

    A missed joint, resulting from an induced thermoelectric magnetism in welding dissimilar metals with a high-intensity electron beam, is experimentally and analytically investigated. Election-beam welding is a very useful process for joining a wide range of dissimilar metals, which may be difficult or impossible to weld by other techniques. Certain combinations of materials, unfortunately, readily give rise to a missed-joint defect because of thermoelectric-magnetic deflection of the beam. Combinations of dissimilar metals chosen for this study are low-carbon steel and type 304 stainless steel, low-carbon steel and Ni-Cu alloy, and type 304 stainless steel and Ni-Cu alloy. The experimental results find agreement with a previous study showing that the electron beam deflects toward the metal with a larger Seebeck coefficient (denoted by metal 1). A general and algebraic expression for predicting deflection angle as a function of dimensionless beam power, accelerating voltage-to-Seebeck electromotive force (EMF) parameter, Peclet and Prandtl numbers, and electrical conductivity ratio between metals 1 and 2 has been derived from a scale analysis for the first time. The predicted results agree well with experimental data obtained from the literature, this work, and three-dimensional theoretical prediction.

  7. GMA Underwater Dry Welding - Mechanical Properties of Butt Joints

    Microsoft Academic Search

    Constantin Miholc?; Emil Constantin; Viorica Constantin

    Since '90, authors developed an underwater research program in the Department of Robotics and Welding, Dunarea de Jos University of Galati, Romania. Several laboratory stands were achieved and the results of the researches were or will be presented in different issues. First, the paper is presenting a laboratory-testing stand able to simulate water depths by 100 m and its main

  8. 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.

  9. On the Critical Technological Issues of Friction Stir Welding T-Joints of Dissimilar Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Astarita, A.; Squillace, A.; Scala, A.; Prisco, A.

    2012-08-01

    In this article, friction stir welded T-joints of innovative dissimilar aluminum alloys have been produced and tested with the aim to investigate the feasibility of using this joining technique, in this configuration, in the aerospace field with the final aim to save weight. The introduction of both this new welding technique and innovative alloys, such as AA 2198 and AA 6056, could allow making lighter and stronger structures. Some experiments, carried out previously, have shown that the fixturing device, the tool geometry, and the tilt angle play a significant role in the joint soundness. A wide experimental characterization has been carried out on FSW T-joints of AA 6056 T4 extrudes to AA 2198 T3 rolled plates. The results attained allow to put in evidence some critical issues on the investigated configuration and can be considered as a further acquired knowledge in the understanding and the design of friction stir processes.

  10. 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.

  11. 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. [JSC 'All-Russia Thermal Engineering Institute' (JSC 'VTI') (Russian Federation)] [JSC 'All-Russia Thermal Engineering Institute' (JSC 'VTI') (Russian Federation)

    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.

  12. 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. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam- 603 102 (India)

    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)

  13. 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.

  14. Study on fatigue crack propagation characteristics around welded joint interface in complexed conditions

    NASA Astrophysics Data System (ADS)

    Ota, Akihiko; Suzuki, Naoyuki; Maeda, Yoshio; Mawari, Toshio; Matsuoka, Saburo; Nishijima, Satoshi

    1993-01-01

    Marine structures are often constructed by welding, and they are subject to repeated loading such as waves and mechanical vibrations which can create fatigue cracks and consequently break the structures. Fatigue crack propagation properties of welded joints are studied under random loading in the air, synthetic sea water, and compressive cycling. It was found that the most crucial factor that controls fatigue crack propagation was high tensile residual stress fields of welded joints. This stress constantly kept the cracks open, simplifying fatigue crack propagation, and therefore, the rate of crack propagation could be assessed with high accuracy. In the transverse matching welded joints with cracks in the center, crack closure did not occur due to the tensile residual stress constantly induced at the crack ends in the center of the test samples. Fatigue crack propagation was accelerated both in artificial sea water and in compressive cycling compared to that in the air, and the fatigue lowest values were about half. Serious crack closures occurred in compressive cycling in which dry hours exceeded 45 minutes, and the fatigue crack propagation rate deteriorated remarkably. Mean fatigue crack propagation rate under the random loading is estimated precisely using equivalent stress intensity factor limit.

  15. 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.

  16. Effects of weld profile and undercut on fatigue crack propagation life of thin-walled cruciform joint

    Microsoft Academic Search

    F. R. Mashiri; X. L. Zhao; P. Grundy

    2001-01-01

    Fatigue may occur in undercarriages and support systems of trailers, haymakers, graders and swing-ploughs made up of thin-walled tubular sections with wall thicknesses less than 4 mm. Little research has been done on the fatigue of thin-walled tubular sections below 4 mm thickness. The weld profile and weld undercut may affect the fatigue crack propagation life of welded joints especially

  17. Microstructure characteristics and mechanical property of aluminum alloy\\/stainless steel lap joints fabricated by MIG welding–brazing process

    Microsoft Academic Search

    Hongtao Zhang; Jiakun Liu

    2011-01-01

    Lap joints of aluminum alloy 2B50 and stainless steel 1Cr18Ni9Ti were welded by MIG welding–brazing method with 4043 Al–Si filler metal. The effect of aluminizing coating and galvanized zinc coating on fusion metal spreadability were studied. The aluminized coating had limited effect to promote weld surface appearance and obvious micro-cracks were found between the compound layer and the steel side.

  18. Fatigue analysis of thin AlMgSi welded joints under constant and variable amplitude block loadings

    Microsoft Academic Search

    J. A. M Pinho-da-Cruz; J. A. M Ferreira; J. D. M Costa; L. F. P Borrego

    2003-01-01

    This paper reports the fatigue behaviour of thin AlMgSi1 aluminium alloy weldments and the improvement in fatigue strength due to post-weld treatments. Several fatigue tests were performed using two distinct types of thin welded joints, T and single lap, manufactured using a 6xxx series aluminium alloy, and the efficiency of fatigue life improvement techniques, such as post-weld heat treatment and

  19. Effects of the Heterogeneity in the Electron Beam Welded Joint on Mechanical Properties of Ti6Al4V Alloy

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    The aim of this investigation was to evaluate the effect of microstructure heterogeneity on the tensile and low cycle fatigue properties of electron beam welded (EBW) Ti6Al4V sheets. To achieve this goal, the tensile and low cycle fatigue property in the EBW joints and base metal (BM) specimens is compared. During the tensile testing, digital image correlation technology was used to measure the plastic strain field evolution within the specimens. The experimental results showed that the tensile ductility and low cycle fatigue strength of EBW joints are lower than that of BM specimens, mainly because of the effect of microstructure heterogeneity of the welded joint. Moreover, the EBW joints exhibit the cyclic hardening behavior during low fatigue process, while BM specimens exhibit the cyclic softening behavior. Compared with the BM specimens with uniform microstructure, the heterogeneity of microstructure in the EBW joint is found to decrease the mechanical properties of welded joint.

  20. 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.

  1. Microstructure and mechanical properties as a function of rotation speed in underwater friction stir welded aluminum alloy joints

    Microsoft Academic Search

    H. J. Zhang; H. J. Liu; L. Yu

    2011-01-01

    A 2219-T6 aluminum alloy was underwater friction stir welded at a fixed welding speed and various rotation speeds in order to illuminate the influence of rotation speed on the performance of underwater joints. With increasing rotation speed, the hardness of the stir zone (SZ) gradually increases due to the increase in dislocation density. The tensile strength first increases from 600

  2. The influence of surface geometry and topography on the fatigue cracking behaviour of laser hybrid welded eccentric fillet joints

    Microsoft Academic Search

    M. M. Alam; Z. Barsoum; P. Jonsén; A. F. H. Kaplan; H. Å. Häggblad

    2010-01-01

    Laser hybrid welding of an eccentric fillet joint causes a complex geometry for fatigue load by 4-point bending. The weld surface geometry and topography were measured and studied in order to understand the crack initiation mechanisms. The crack initiation location and the crack propagation path were studied and compared to Finite Element stress analysis, taking into account the surface macro-

  3. Influence of the method of protection on the cyclic strength and character of fracture of titanium alloy weld joints

    Microsoft Academic Search

    B. Y. Mozeiko; T. Y. Yakovleva

    1985-01-01

    In the argon-arc welding of titanium assemblies of complex spatial configuration done outside controlled atmosphere chambers it is often difficult to provide reliable protection of the root side of the joint with known gas protection equipment. The necessary reliability in protection is provided by a special, technologically stable two-layer coating applied to the reverse side of the edges being welded.

  4. 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.

  5. Effects of heat treatments on mechanical properties of Fe\\/Al explosion-welded structural transition joints

    Microsoft Academic Search

    L. Tricarico; R. Spina; D. Sorgente; M. Brandizzi

    2009-01-01

    The aluminum\\/steel structural transition joints are widely used in shipbuilding industry due to the advantages of joining these two materials with important weight savings while exploiting their best properties. The research objective is the evaluation of process feasibility to laser weld structural transition joints to overcome manufacturing limitations of traditional TIG\\/MIG welding. This study presents results achieved during as-simulated laser

  6. Weld line detection and process control for welding automation

    NASA Astrophysics Data System (ADS)

    Yang, Sang-Min; Cho, Man-Ho; Lee, Ho-Young; Cho, Taik-Dong

    2007-03-01

    Welding has been widely used as a process to join metallic parts. But because of hazardous working conditions, workers tend to avoid this task. Techniques to achieve the automation are the recognition of joint line and process control. A CCD (charge coupled device) camera with a laser stripe was applied to enhance the automatic weld seam tracking in GMAW (gas metal arc welding). The adaptive Hough transformation having an on-line processing ability was used to extract laser stripes and to obtain specific weld points. The three-dimensional information obtained from the vision system made it possible to generate the weld torch path and to obtain information such as the width and depth of the weld line. In this study, a neural network based on the generalized delta rule algorithm was adapted to control the process of GMAW, such as welding speed, arc voltage and wire feeding speed. The width and depth of the weld joint have been selected as neurons in the input layer of the neural-network algorithm. The input variables, the width and depth of the weld joint, are determined by image information. The voltage, weld speed and wire feed rate are represented as the neurons in the output layer. The results of the neural-network learning applied to the welding are as follows: learning ratio 0.5, momentum ratio 0.7, the number of hidden layers 2 and the number of hidden units 8. They have significant influence on the weld quality.

  7. 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

  8. Dissimilar material lap joints by friction stir welding of steel and titanium sheets: Process modeling

    NASA Astrophysics Data System (ADS)

    Buffa, Gianluca; Ducato, Antonino; Fratini, Livan

    2013-05-01

    In the paper a continuum based FEM model for Friction Stir Welding of different material lap joint made out of thin stainless steel and titanium sheets is proposed. The simulation campaign was made out using the 3D Lagrangian implicit code DEFORM{trade mark, serif} by means of a rigid-visco-plastic approach. The model, already set up and tuned for FSW process of similar materials and geometrical configurations takes into account the different mechanical and thermal behavior of the two materials and the microstructural evolution of the considered titanium alloy in the same joint. Additionally, it is able to predict temperature, phase, strain and strain rate distributions and evolution at the varying of the main process variables. The phase evolution models take into account only the main phases called Alpha, Beta and Alpha+Baeta so that, at the end of the simulation, the complete phase distribution in the welded zone.

  9. Strengthening effect of nickel and copper interlayers on hybrid laser-TIG welded joints between magnesium alloy and mild steel

    Microsoft Academic Search

    Liming Liu; Xiaodong Qi

    2010-01-01

    AZ31B magnesium alloy and Q235 mild steel were lap joined with Ni and Cu interlayers using hybrid laser-TIG welding technique. Microstructure and mechanical properties of joints were examined. The results showed that the shear strength of Cu-added joint was a little higher than that of Ni-added joint, and the strength of both joints exceeded that of base material AZ31B Mg

  10. High Temperature Plasticity of Bimetallic Magnesium and Aluminum Friction Stir Welded Joints

    NASA Astrophysics Data System (ADS)

    Regev, Michael; El Mehtedi, Mohamad; Cabibbo, Marcello; Quercetti, Giovanni; Ciccarelli, Daniele; Spigarelli, Stefano

    2014-02-01

    The high temperature deformation of a bimetallic AZ31/AA6061 Friction Stir Welded joint was investigated in the present study by constant load creep experiments carried out at 473 K (200 °C). The microstructural analysis revealed the strongly inhomogeneous nature of the weld, which was characterized by an extremely fine grain size in the magnesium-rich zones and by the extensive presence of intermetallic phases. In the high stress regime, the creep strain was concentrated in the refined and particle-rich microstructure of the weld zone, while the AA6061 base metal remained undeformed. In the low stress regime, deformation became more homogeneously distributed between the AZ31 base metal and the weld zone. The creep behavior of the weld was found to obey the constitutive equation describing the minimum creep rate dependence on applied stress for the base AZ31, slightly modified to take into account the finer microstructure and the role of secondary phase particles, i.e., the retardation of grain growth and the obstruction of grain boundary sliding.

  11. Stress Corrosion Cracking Behavior of Peened Friction Stir Welded 2195 Aluminum Alloy Joints

    Microsoft Academic Search

    Omar Hatamleh; Preet M. Singh; Hamid Garmestani

    2009-01-01

    The surface treatment techniques of laser and shot peening were used to investigate their effect on stress corrosion cracking\\u000a (SCC) in friction stir welded (FSW) 2195 aluminum alloy joints. The investigation consisted of two parts: the first part explored\\u000a the peening effects on slow strain rate testing (SSRT) in a 3.5% NaCl solution, while the second part investigated the effects

  12. A life prediction model for welded joints under multiaxial variable amplitude loading histories

    Microsoft Academic Search

    Yung-Li Lee; Tana Tjhung; Algernon Jordan

    2007-01-01

    This paper describes a simple damage model for fatigue life predictions of welded joints under nonproportional, constant, and variable amplitude loading histories. This model, an extension of Sonsino’s effective equivalent stress amplitude method, consists of four material parameters accounting for the severity of nonproportional loading paths, the material’s susceptibility to nonproportional hardening, the material’s fatigue life under shear versus normal

  13. Problems of the strength of welded joints in niobium and its alloys

    Microsoft Academic Search

    S. M. Gurevich; M. M. Nerodenko; E. A. Asnis; S. V. Smirnov; M. D. Rabkina

    1973-01-01

    Translated from Probl. Prochnosti; 5: No. 1, 112-114(Jan 1973). The ; static and fatigue strength of welded joints of niobium and its alloys were ; investigated. The experimental materials (sheets 2 mm thick) included technical ; grade niobium, a hardened solidsolution type alloy Nb--W--Mo--Zr (alloy 1), and a ; dispersionhardening alloy Nb--Zr--C (alloy 2). All these materials were used in

  14. Assessment of the high-frequency mechanical forging mode effect on fatigue strength of welded joints

    Microsoft Academic Search

    V. A. Degtyarev

    2011-01-01

    We present results of fatigue testing of strengthened butt-welded joints of St. 3sp steel subjected to various modes of high-frequency\\u000a mechanical forging. As the treatment effectiveness criterion, we propose to use the groove depth in the work-hardened area.\\u000a The optimal values of groove depth and high-frequency mechanical forging rates have been determined at various vibration amplitudes\\u000a of the forging tool,

  15. 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.

  16. Corrosion fatigue of welded high-strength cast and structural steel joints under constant and variable amplitude loading

    SciTech Connect

    Sonsino, C.M.; Lipp, K. [Fraunhofer-Inst. fuer Betriebsfestigkeit, Darmstadt (Germany); Lachmann, E. [Industrieanlagen-Betriebsgesellschaft mbH, Ottobrunn (Germany)

    1995-12-31

    Structures of offshore platforms are generally subjected to high loads. These structures are mainly fabricated from steel with welded complex tubular steel nodes where fatigue cracking occurs in the weld toe, weld undercut or in the weld due to stress concentrations. Greater sea depths lead to higher loads and therefore major efforts have been devoted to the development of hybrid design concepts combining rolled steel with cast steel inserts. This paper discusses the results of fatigue tests of cast/structural steel joints under free corrosion as well as under cathodic protection for constant and variable amplitude loading.

  17. A robust method for vision-based seam tracking in robotic arc welding

    Microsoft Academic Search

    Jae Seon Kim; Young Tak Son; Hyung Suck Cho; Kwang Il Koh

    1995-01-01

    This paper presents a robotic seam tracking system which is aimed at achieving robustness against some welding noises such as arc glares, welding spatters, fumes etc. In particularly, a syntactic analysis is used to improve the extraction reliability of the joint features. The joint features thus obtained are used to extract the 3-dimensional information of the weld joint and then

  18. FATIGUE LIFE EVALUATION OF WELDED JOINTS BASED ON NOMINAL STRESS AND FINITE ELEMENT ANALYSIS

    Microsoft Academic Search

    B. C. GOO; S. Y. YANG; J. W. SEO

    In the first part, experimental study on the fatigue behavior of a material, SM 490 A was carried out on double V-grooved butt welded plates such as reinforcement removed, as-welded and weld toe ground. In addition, welded plates with transverse fillet welded web, load carrying cruciform fillet welded plates, non- load carrying cruciform fillet welded plate and longitudinal butt welded

  19. Characterizations of 21-4N to 4Cr9Si2 stainless steel dissimilar joint bonded by electric-resistance-heat-aided friction welding

    Microsoft Academic Search

    Wen-Ya Li; Min Yu; Jinglong Li; Guifeng Zhang; Shiyuan Wang

    2009-01-01

    A new welding process, electric-resistance-heat-aided friction welding (ERHAFW), was introduced in this study. To further improve the joint quality and energy-saving, electric resistance welding was combined with the conventional continuous-drive friction welding. 21-4N (austenitic stainless steel) and 4Cr9Si2 (martensitic stainless steel) valve steel rods of 4mm diameter were used as base metals. The results show that electric-resistance-heat-aided friction welding can

  20. Tensile properties of austenitic stainless steels and their weld joints after irradiation by the ORR-spectrally-tailoring experiment

    NASA Astrophysics Data System (ADS)

    Jitsukawa, S.; Maziasz, P. J.; Ishiyama, T.; Gibson, L. T.; Hishinuma, A.

    1992-09-01

    Tensile specimens of the Japanese heat of PCA (JPCA) and type 316 stainless steels were irradiated in spectrally tailored capsules in the Oak Ridge Research Reactor (ORR) to a peak dose of 7.4 dpa and a peak helium level of 105 appm in the temperature range between 328 and 673 K. Specimens of type 316 steel with weld joints produced by tungsten inert gas (TIG) and electron beam (EB) welding techniques were also included. Irradiation caused both increases in flow stress and decreases in elongation. Weld joint specimens exhibited both lower strength and elongation after irradiation. The reduction of area (RA) for the TIG weld joint specimens decreased by a factor of 5 compared to unirradiated base metal specimens, however, they still fractured in a ductile mode. The EB weld joints maintained RA levels similar to that of the unirradiated base metal specimens. Post-radiation ductilities of weld joints and base metal specimens of these steels should be adequate for their application to next generation fusion experimental devices, such as the International Tokamak Experimental Reactor (ITER).

  1. Heat Strength Evaluation and Microstructures Observation of the Welded Joints of One China-Made T91 Steel

    NASA Astrophysics Data System (ADS)

    Gong, Yi; Yang, Zhen-Guo; Yang, Fa-Yun

    2012-07-01

    T91 (9Cr1MoVNb), the martensitic heat-resistant steel, is widely applied in industries like power generation, petrochemical, nuclear, etc., and a wealth of researches has been conducted on its properties so far. However, actually for China, T91 was begun to be domestically manufactured only from the end of last century. Hence, thorough assessments of the China-made T91 steels are always urgently required, especially for its welded joints. In this paper, the relationship between mechanical properties and microstructures of the welded joints of one China-made T91 steel was experimentally discussed. Moreover, aging test and creep rupture test were utilized for both analyzing the heat strength and predicting the service life of the joints. Results showed that welded joints of this China-made T91 steel could exhibit sufficient strength under the operating conditions of most nuclear reactors used nowadays.

  2. 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.

  3. 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.

  4. 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.

  5. The influence of radiation on the properties of welds and joints

    NASA Astrophysics Data System (ADS)

    Tavassoli, A. A.

    1988-07-01

    The effect of radiation on mechanical properties of candidate structural materials for the first wall and breeder blanket of fusion reactors is reviewed. The emphasis is placed on austenitic stainless steel type 316L and its weld metals; design parameters considered are similar to those currently specified for the Next European Torus, namely, irradiation doses ?15 dpa, temperatures ? 400°C, number of pulse cycles ?10 5 and hold times ?15 mn. The effect of irradiation on other materials, including austenitic stainless steel Type 304L, weld metal Type 308L and ferritic/martensitic steels (9-12% Cr-Mo), as well as other service conditions such as temperatures as high as 550°C are also briefly discussed. The data collected and presented in this review are those usually measured before and after irradiation, through tensile, impact toughness, fracture toughness, fatigue, creep-fatigue and fatigue crack propagation testing. In each case the influence of irradiation parameters on the observed changes are discussed and relative conclusions are drawn. The most important observation made is the lack of medium dose irradiation data on the weld metal and in particular on the electron beam welded joints.

  6. Study of the fatigue behavior in welded joints of stainless steels treated by weld toe grinding and subjected to salt water corrosion

    Microsoft Academic Search

    R. Baptista; V. Infante; C. M. Branco

    2008-01-01

    This paper presents the fatigue results obtained in two types of stainless steels: Duplex S31803 and Austenitic 304L. The main objective was to compare the fatigue behavior in terms of environment (air and 3% NaCl) and weld toe treatment (as welded and toe grinding). The tests were carried out in tension on cruciform specimens with a constant amplitude fatigue cycle

  7. Tensile properties of friction stir welded and friction stir welded-superplastically formed Ti–6Al–4V butt joints

    Microsoft Academic Search

    M. Ramulu; P. D. Edwards; D. G. Sanders; A. P. Reynolds; T. Trapp

    2010-01-01

    A University and Industry collaborative research project was undertaken to evaluate the performance of as friction stir welded (FSW) and friction stir welded-superplastically formed Ti–6Al–4V alloy sheets. The purpose of this particular effort was to evaluate the tensile properties of friction stir welded and superplastically formed friction stir welded Ti–6Al–4V. Welds were produced out of both standard grain and fine

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  9. 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.

  10. Fatigue crack growth performance of peened friction stir welded 2195 aluminum alloy joints at elevated and cryogenic temperatures

    Microsoft Academic Search

    Omar Hatamleh; Michael Hill; Scott Forth; Daniel Garcia

    2009-01-01

    The effects of various surface treatments on fatigue crack growth and residual stress distributions in friction stir welded 2195 aluminum alloy joints were investigated. The objective was to understand the degree to which residual stress treatments can reduce fatigue crack growth rates, and enhance fatigue life of friction stir welded components. Specimens were fabricated from 12.5mm thick 2195-T8 aluminum plate,

  11. Fatigue life prediction of GTA welded AISI 304L cruciform joints with lack of penetration using local-stress approach

    Microsoft Academic Search

    P Johan Singh; B Guha; D. R. G Achar

    2003-01-01

    The influence of welding procedure on fatigue properties of gas tungsten arc welded (GTAW) AISI 304L load carrying cruciform joints, containing lack of penetration (LOP) has been studied using a crack initiation–propagation (I-P) method. The crack process normally comprises two major phases: (1) the crack initiation life (NI): and (2) the crack propagation life (Np). The local stress-life approach is

  12. Multiaxial fatigue of welded joints under in-phase and out-of-phase local strains and stresses

    Microsoft Academic Search

    C. M. Sonsino

    1995-01-01

    Welded cruciform-type specimens from fine-grained steel StE 290 and flange-tube as well as tube-tube joints from fine-grained steel StE 460 with unmachined and machined welds were investigated under biaxial constant-amplitude loading in the range 103 to 5 × 106 cycles to crack initiation and breakthrough respectively. In order not to interfere with residual stresses they were relieved by heat treatment.

  13. Elastic–plastic stress\\/strain response of friction stir-welded titanium butt joints using moiré interferometry

    Microsoft Academic Search

    M. Ramulu; P. Labossiere; T. Greenwell

    2010-01-01

    An experimental investigation is conducted to examine, evaluate, and characterize the fundamental elastic–plastic stress\\/strain response of friction stir-welded butt joints in thin-sheet, fine grain Ti–6Al–4V titanium alloy under normal tensile loading using the full-field optical strain analysis technique of moiré interferometry. It was found that the overall strength of friction stir-welded Ti–6Al–4V is comparable to the accepted values for pure

  14. 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.

  15. 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.

  16. Experimental study on fatigue performance and damage model of aluminum alloy welding joints for high-speed train car body

    NASA Astrophysics Data System (ADS)

    Wang, Wenjing; Li, Qiang; Liu, Zhiming; Wang, Binjie

    2010-03-01

    In order to realize lightweight, security and comfort, the aluminum alloy profile becomes the first choice of the high speed train carbody. The fatigue experiments are carried on the typical welding joins such as butt, fillet, cruciform and lap joins. The fatigue limits and P-S-N curves are obtained. The non-linearity cumulative damage model is proposed taking loading sequences for consideration and the two-level loading experiments on butt and fillet joints are studied to verify the feasibility of the damage model. The fatigue life of carbody is predicted based on the proposed damage model and the online dynamic stress test results. The results show that the fatigue life calculated by non-linearity damage model is close to that by modified Miner law and 22% less than that by Miner law.

  17. Experimental study on fatigue performance and damage model of aluminum alloy welding joints for high-speed train car body

    NASA Astrophysics Data System (ADS)

    Wang, Wenjing; Li, Qiang; Liu, Zhiming; Wang, Binjie

    2009-12-01

    In order to realize lightweight, security and comfort, the aluminum alloy profile becomes the first choice of the high speed train carbody. The fatigue experiments are carried on the typical welding joins such as butt, fillet, cruciform and lap joins. The fatigue limits and P-S-N curves are obtained. The non-linearity cumulative damage model is proposed taking loading sequences for consideration and the two-level loading experiments on butt and fillet joints are studied to verify the feasibility of the damage model. The fatigue life of carbody is predicted based on the proposed damage model and the online dynamic stress test results. The results show that the fatigue life calculated by non-linearity damage model is close to that by modified Miner law and 22% less than that by Miner law.

  18. 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.

  19. Research on Metal Magnetic Memory Testing Technology in Welding Joint of Structure Train (Railway High-Speed Motor Train Set) Locomotive

    Microsoft Academic Search

    Shengyun Wan; Donglei Lu; Xiaokang Zheng

    2011-01-01

    Metal Magnetic Memory Technology?ƒ MMMT?? can find out the residual stress concentration zone and provide early diagnosis for ferromagnetic structure components. The application of MMMT in welded joints inspection has been investigated and compared with the result of X-ray inspection in this paper. The applicability of MMMT in welded joints NDT is also analyzed. The experimental results show MMMT can

  20. Introductory fatigue tests on welded joints in high strength steel and aluminium improved by various methods including ultrasonic impact treatment (UIT)

    Microsoft Academic Search

    NORWEGIAN DELEGATION; P. J. Haagensen; E. S. Statnikov; L. Lopez-Martinez

    This paper summarizes fatigue test on high strength steel specimens in the as-welded condition and specimens treated by ultrasonic impact treatment, TIG dressing and a combination of TIG dressing and ultrasonic impact treatment. Single lap joint specimens in 6 mm aluminium plate material were tested in the as-welded, hammer peened, needle peened and ground condition. Aluminium joints with longitudinal stiffeners

  1. 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.

  2. Microstructural characteristics and mechanical properties of friction stir welded joints of Ti–6Al–4V titanium alloy

    Microsoft Academic Search

    H. J. Liu; L. Zhou; Q. W. Liu

    2010-01-01

    The ?+? titanium alloy, Ti–6Al–4V, was friction stir welded at a constant tool rotation speed of 400rpm. Defect-free welds were successfully obtained with welding speeds ranging from 25 to 100mm\\/min. The base material was mill annealed with an initial microstructure composed of elongated primary ? and transformed ?. A bimodal microstructure was developed in the stir zone during friction stir

  3. Robotic Vision for Welding

    NASA Technical Reports Server (NTRS)

    Richardson, R. W.

    1986-01-01

    Vision system for robotic welder looks at weld along axis of welding electrode. Gives robot view of most of weld area, including yet-unwelded joint, weld pool, and completed weld bead. Protected within welding-torch body, lens and fiber bundle give robot closeup view of weld in progress. Relayed to video camera on robot manipulator frame, weld image provides data for automatic control of robot motion and welding parameters.

  4. Carbothermic reduction of pirolusite to obtain carbon-bearing ferromanganese and slag suited to the development of welding materials

    Microsoft Academic Search

    A. Cruz-Crespo; R. Quintana-Puchol; L Perdomo González; C. R. Gomez-Perez; L. L. Garcia-Sanchez; G. Ejimenez-Vielsa; A. Cores-Sanchez

    2005-01-01

    This article examines the process for obtaining high carbon ferromanganese by means of carbothermic reduction in a direct current electric arc furnace. It establishes the ideal composition of slag oxides to make a flux for use in submerged arc welding (SAW). The charge components (pirolusite, coke, steel wool, lime, rutile and fluorite) are calculated for a flux-free technology to obtain

  5. 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.

  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. Influence of welding quality on the corrosion resistance of titanium weld joints

    Microsoft Academic Search

    Go K. Kudryavitskaya; N. N. Rodin; A. E. Romanushkina; V. G. Lambrev; M. V. Mamylikhina

    1985-01-01

    The investigations were made with the use of the highly sensitive method of neutron activation and gamma-spectrometry [i], making it possible to reduce the length of the comparative corrosion tests and obtain information on the kinetics of solution of the investigated metal (titanium) and the impurities (chromium, antimony, gold)contained in it in very small quantities (10-3-10 -7 wt.%) [2, 3].

  8. Effect of Application of Short and Long Holds on Fatigue Life of Modified 9Cr-1Mo Steel Weld Joint

    NASA Astrophysics Data System (ADS)

    Shankar, Vani; Mariappan, K.; Sandhya, R.; Mathew, M. D.; Jayakumar, T.

    2013-11-01

    Modified 9Cr-1Mo steel is a heat-treatable steel and hence the microstructure is temperature sensitive. During welding, the weld joint (WJ) is exposed to various temperatures resulting in a complex heterogeneous microstructure across the weld joint, such as the weld metal, heat-affected zone (HAZ) (consisting of coarse-grained HAZ, fine-grained HAZ, and intercritical HAZ), and the unaffected base metal of varying mechanical properties. The overall creep-fatigue interaction (CFI) response of the WJ is hence due to a complex interplay between various factors such as surface oxides and stress relaxation (SR) occurring in each microstructural zone. It has been demonstrated that SR occurring during application of hold in a CFI cycle is an important parameter that controls fatigue life. Creep-fatigue damage in a cavitation-resistant material such as modified 9Cr-1Mo steel base metal is accommodated in the form of microstructural degradation. However, due to the complex heterogeneous microstructure across the weld joint, SR will be different in different microstructural zones. Hence, the damage is accommodated in the form of preferential coarsening of the substructure, cavity formation around the coarsened carbides, and new surface formation such as cracks in the soft heat-affected zone.

  9. Physicochemical Causes of the Extent of Water Resistance of Linearly Welded Wood Joints

    Microsoft Academic Search

    P. Omrani; A. Pizzi; H. R. Mansouri; J.-M. Leban; L. Delmotte

    2009-01-01

    A change in linear welding conditions, namely higher vibration frequency (150 Hz) and lower displacement (2 mm) during welding, produced a quicker rise in temperature of the weldline. This allowed a much shorter welding time (1.5 s). X-ray microdensitometry mapping showed a progressive increase in broadening and average density of the weldline as the welding time lengthens. As the welding

  10. Inelastic behavior of a dissimilar-metal-welded pipe transition joint: comparison of experimental measurements and analytical prediction

    Microsoft Academic Search

    T. M. Yang; A. W. Dalcher

    1979-01-01

    The subject study involved the prediction and observed behavior of a dissimilar metal pipe joint made from 2 1\\/4 Cr-1Mo steel welded to Type 316 austenitic stainless steel using a nickel-base filler metal, ERNiCr-3. A two-dimensional axi-symmetric finite element model was employed in the analysis, with certain assumptions made relative to the initial stress state of the joint. Internal pressure

  11. Creep property measurements of welded joint of reduced-activation ferritic steel by the small-punch creep test

    Microsoft Academic Search

    Shin-ichi Komazaki; Taichiro Kato; Yutaka Kohno; Hiroyasu Tanigawa

    2009-01-01

    The small-punch (SP) test and the SP creep test were carried out by using a further miniaturized plate-type specimen (3mm diameter×0.25mm thick). Those tests were applied to the electron-beam welded joint of reduced-activation ferritic steel for evaluating the distribution of high-temperature strength in the joint. The experimental results revealed that the distribution of the maximum load measured by the SP

  12. Experimental investigations for mechanical joint strength following ultrasonically welded pin osteosynthesis

    Microsoft Academic Search

    Heike Meissner; Eckart Pilling; Gert Richter; Rainer Koch; Uwe Eckelt; Bernd Reitemeier

    2008-01-01

    The purpose of this study was to determine whether fixation of cranial bone segments using ultrasonically welded pin osteosynthesis\\u000a showed differences in mechanical stability as compared to fixation of cranial bone segments using screw osteosynthesis. Right\\u000a and left cranial bone segments from each of 16 young sheep were obtained by craniotomy and re-fixed: on the right with a mesh\\u000a plate

  13. 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.

  14. An investigation of the residual stress characterization and relaxation in peened friction stir welded aluminum–lithium alloy joints

    Microsoft Academic Search

    Omar Hatamleh; Iris V. Rivero; Shayla E. Swain

    2009-01-01

    In this investigation the residual stresses generated from friction stir welded (FSW) 2195 aluminum–lithium alloy joints were characterized. The results derived from this research revealed significant levels of tensile residual stresses at the surface and throughout the thickness of the FSW samples. Furthermore, residual stress relaxation at the surface and throughout the thickness of the samples was assessed for laser

  15. Optimising the shielded metal arc welded cruciform joint dimensions of ASTM 517 F grade steels containing LOP defects

    Microsoft Academic Search

    V. Balasubramanian; B. Guha

    1999-01-01

    A new method was developed to optimise the dimensions of shielded metal arc welded (SMAW) cruciform joints, containing lack of penetration (LOP) defects, to attain maximum fatigue lives. High strength, quenched and tempered steel (ASTM 517 F grade) was used as the base material throughout the investigation. Design of experiments (DoE) concept was used to optimise the required number of

  16. Characterisation of dissimilar joints in laser welding of steel–kovar, copper–steel and copper–aluminium

    Microsoft Academic Search

    T. A. Mai; A. C. Spowage

    2004-01-01

    Joining of dissimilar materials is one of the challenging tasks facing modern manufacturers. Dissimilar joining technologies find applications in many sectors including microelectronics, medical, optoelectronics and microsystems. The tiny geometry of the joints and the different optical and thermal properties of the materials makes laser welding one of the most suitable production methods. This paper presents the results of an

  17. C-ring stress corrosion test for Inconel 600 and Inconel 690 sleeve joint welded by Nd:YAG laser

    Microsoft Academic Search

    Jae-Do Kim; Ju-Hong Moon

    2004-01-01

    C-ring stress corrosion test for Inconel 600 and Inconel 690 sleeve joint welded by Nd:YAG laser were carried out to evaluate the applicability of the technique in the repair of heat exchanger tube of nuclear power plant. Corrosion test were carried out mainly in caustic solution. The applied stresses range between 207 and 414 MPa at 348 °C and the

  18. Growth rate of fatigue cracks in fields of residual stresses in titanium welded joints with different content of embrittling impurities

    Microsoft Academic Search

    V. T. Troshchenko; V. V. Pokrovskii; V. L. Yarusevich; V. I. Mikhailov; V. A. Sher

    1990-01-01

    Investigations were carried out into the fatigue crack growth resistance of welded joints in structural titanium alloys contaminated with embrittling impurities. The crack closure effect was taken into account so that it is possible to determine the effective stress intensity factor. The results show that the fatigue crack growth rate (FCGR) depends strongly on the magnitude and direction of residual

  19. Fatigue life prediction of gas metal arc welded crucifrom joints of AA7075 aluminium alloy failing from root region

    Microsoft Academic Search

    B. RAVINDRA; T. SENTHIL KUMAR; V. BALASUBRAMANIAN

    2011-01-01

    Empirical relationship was developed to predict the fatigue life of gas metal arc welded (GMAW) cruciform joints failing from root region. High strength, age hardenable aluminium alloy of AA7075-T6 grade was used as the base material. The design of experiments concept was used to optimize the required number of fatigue testing experiments. Fatigue experiment was conducted in a servo hydraulic

  20. Fatigue life prediction of shielded metal arc welded cruciform joints containing LOP defects by a mathematical model

    Microsoft Academic Search

    V. Balasubramanian; B. Guha

    1999-01-01

    A new mathematical model is developed to predict the fatigue life of Shielded Metal Arc Welded (SMAW) cruciform joints containing Lack of Penetration (LOP) defect. High strength, quenched and tempered steel (ASTM 517 ‘F’ Grade) is used as the base material throughout the investigation. Four factors, five level, central composite, rotatable design matrix is used to optimise the required number

  1. Influences of shielded metal arc welded cruciform joint dimensions on toe crack failures of pressure vessel grade steels

    Microsoft Academic Search

    V Balasubramanian; B Guha; A. S. J Swamidas; R Seshadri

    2000-01-01

    A mathematical model has been developed to predict the fatigue life of Shielded Metal Arc Welded (SMAW) cruciform joints failing from toe region. High strength, quenched and tempered steel (ASTM 517 ‘F’ Grade) has been used as the base material throughout the investigation. Design of Experiments (DoE) concept has been used to optimise the required number of experiments. Fatigue experiments

  2. Investigation of the fatigue behaviour of the welded joints treated by TIG dressing and ultrasonic peening under variable-amplitude load

    Microsoft Academic Search

    Lixing Huo; Dongpo Wang; Yufeng Zhang

    2005-01-01

    Weld toe treatment by ultrasonic peening (IIW.Doc.XIII-1817-00; J. Mech. Strength 21(1999)289; Welding World (3\\/4)(2001); Welding World (37)(1996)72) or TIG dressing (Trans. Jpn. Welded Soc. 17(2)(1986)3; Int. J. Fatigue 21(6)(1999)587; Metal Construction 19(2)(1984)143; Int. J. Fatigue 20(9)(1998)677) improves the fatigue performance of welded joints and structures significantly. This has been verified by many constant amplitude fatigue tests. However, there is the

  3. Effect of residual stresses on the fatigue behaviour of welded joints depending on loading conditions and weld geometry

    Microsoft Academic Search

    C. M. Sonsino

    2009-01-01

    The structural durability of welded structures is determined by the interaction of different influencing parameters such as loading mode, spectrum shape, residual stresses and weld geometry among others. Examples from plant, offshore, transportation and automotive engineering show how these parameters influence the fatigue life and to what extent they are considered in design codes. Especially, under spectrum loading, the stress

  4. The significance of weld imperfections and surface peening on fatigue crack propagation life of butt-welded joints

    Microsoft Academic Search

    M. A. Wahab; M. S. Alam

    2004-01-01

    This study describes the influence of various weld imperfections (solidification crack, undercut and porosity) on fatigue crack propagation life due to combined axial and torsional fatigue loading. The stress intensity factors for different weld imperfections have been calculated by finite element method. The fatigue crack propagation life has been calculated using fracture mechanics approaches. It has been found that the

  5. Establishing Mathematical Models to Predict Grain Size and Hardness of the Friction Stir-Welded AA 7020 Aluminum Alloy Joints

    NASA Astrophysics Data System (ADS)

    Rahimzadeh Ilkhichi, A.; Soufi, R.; Hussain, G.; Vatankhah Barenji, R.; Heidarzadeh, A.

    2015-02-01

    In this study, response surface methodology in conjunction with a central composite design was applied to predict the grain size and hardness of friction stir-welded AA 7020 aluminum alloy joints. For this purpose, three welding parameters, including tool rotational speed, traverse speed, and tool axial force, at five levels and 20 runs were considered. In order to validate the predicted models, the analysis of variance was performed. Hardness and microstructural features of the joints were investigated using microhardness test and optical microscopy, respectively. In addition, the influences of friction stir welding parameters on grain size and hardness of the joints were examined thoroughly. The analysis of variance results revealed that the developed models were significant and accurate to predict the responses. Furthermore, with increasing the heat input, the hardness of the joints decreased, where the grain size increased continuously. In addition, the optimized condition for achieving the lowest grain size and highest hardness of the joints was reached as 800 rpm, 125 mm/min and 8 kN.

  6. Multiscale Characterization of Deformation Mechanisms in the Weld Joint of a Nickel-based Superalloy

    SciTech Connect

    Barabash, Oleg M.; Horton, Joe; Babu, Suresh; Vitek, John; David, Stan; Ice, Gene; Barabash, Rozaliya (ORNL)

    2007-12-19

    Multiscale plastic deformation in the heat affected zone (HAZ) of a Ni-based single crystal superalloy has been characterized using white microbeam synchrotron diffraction measurements together with OIM imaging, electron and optical microscopy. Characteristic length scales on the macro, meso and nano scale are determined. Dissolution of the {gamma} - phase particles during heating and secondary precipitation of {gamma} - phase during cooling is found, as well as formation and multiplication of dislocations. This process is more intense as one approaches the fusion line (FL). In the regions immediately neighboring the FL, {gamma} - phase particles dissolve completely and re-precipitate from the solid solution in the form of very small (50-70nm) particles. In the immediate vicinity of the FL, the temperature gradient and the rate of it's change reaches maximal values and causes the formation of large amounts of dislocations. Dislocations are concentrated in the ? matrix of the single crystal superalloy. X-ray Laue diffraction (both conventional and microbeam) and electron microscopy show that alternating dislocations slip systems dominate in the HAZ with typical Burgers vector b=[110]. Local lattice rotations in different zones of the weld joint are linking with the microslip events in different zones of the weld.

  7. Multiscale characterization of deformation mechanisms in the weld joint of a nickel-based superalloy

    SciTech Connect

    Barabash, Oleg M [ORNL; Horton Jr, Joe A [ORNL; Babu, Sudarsanam S [ORNL; Vitek, John Michael [ORNL; David, Stan A [ORNL; Ice, Gene E [ORNL; Barabash, Rozaliya [ORNL

    2005-01-01

    Multiscale plastic deformation in the heat affected zone (HAZ) of a Ni-based single crystal superalloy has been characterized using white microbeam synchrotron diffraction measurements together with OIM imaging, electron and optical microscopy. Characteristic length scales on the macro, meso and nano scale are determined. Dissolution of the gamma' - phase particles during heating and secondary precipitation of gamma' during cooling is found, as well as formation and multiplication of dislocations. This process is more intense as one approaches the fusion line (FL). In the regions immediately neighboring the FL, gamma' - phase particles dissolve completely and re-precipitate from the solid solution in the form of very small (10-20nm) particles. In the immediate vicinity of the FL, the temperature gradient and the rate of it's change reaches maximal values and causes the formation of large amounts of dislocations. Dislocations are concentrated in the gamma matrix of the single crystal superalloy. X-ray Laue diffraction (both conventional and microbeam) and electron microscopy show that alternating dislocations slip systems dominate in the HAZ with Burgers vector b=[110] and dislocation lines [1-12] and [1-1-2] ; or b=[-110], dislocation lines [112] and [11-2] . Each of these two dislocation groups forms two Z-shaped dislocation lines fluctuating around two cubic directions [100] and [010]. Local lattice rotations in different zones of the weld joint are linking with the microslip events in different zones of the weld.

  8. Multiscale Characterization of Deformation Mechanisms in the Weld Joint of a Nickel-based Superalloy

    SciTech Connect

    Barabash, Oleg M [ORNL

    2005-01-01

    Multiscale plastic deformation in the heat affected zone (HAZ) of a Ni-based single crystal superalloy has been characterized using white microbeam synchrotron diffraction measurements together with OIM imaging, electron and optical microscopy. Characteristic length scales on the macro, meso and nano scale are determined. Dissolution of the {gamma}{prime} - phase particles during heating and secondary precipitation of {gamma}{prime} - phase during cooling is found, as well as formation and multiplication of dislocations. This process is more intense as one approaches the fusion line (FL). In the regions immediately neighboring the FL, {gamma}{prime} - phase particles dissolve completely and re-precipitate from the solid solution in the form of very small (50-70nm) particles. In the immediate vicinity of the FL, the temperature gradient and the rate of it's change reaches maximal values and causes the formation of large amounts of dislocations. Dislocations are concentrated in the {gamma} matrix of the single crystal superalloy. X-ray Laue diffraction (both conventional and microbeam) and electron microscopy show that alternating dislocations slip systems dominate in the HAZ with typical Burgers vector b=[110]. Local lattice rotations in different zones of the weld joint are linking with the microslip events in different zones of the weld.

  9. Stress Corrosion Cracking Behavior of Peened Friction Stir Welded 2195 Aluminum Alloy Joints

    NASA Astrophysics Data System (ADS)

    Hatamleh, Omar; Singh, Preet M.; Garmestani, Hamid

    2009-06-01

    The surface treatment techniques of laser and shot peening were used to investigate their effect on stress corrosion cracking (SCC) in friction stir welded (FSW) 2195 aluminum alloy joints. The investigation consisted of two parts: the first part explored the peening effects on slow strain rate testing (SSRT) in a 3.5% NaCl solution, while the second part investigated the effects of peening on corrosion while submerged in a 3.5% NaCl solution with no external loads applied. For the SSRT, the laser-peened samples demonstrated superior properties to the other samples, but no signs of corrosion pitting or SCC were evident on any of the samples. For the second part of the study, the FSW plates were inspected periodically for signs of corrosion. After 60 days there were signs of corrosion pitting, but no stress corrosion cracking was noticed in any of the peened and unpeened samples.

  10. 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.

  11. Moisture Sensitivity of Scots Pine Joints Produced by Linear Frictional Welding

    Microsoft Academic Search

    Mojgan Vaziri; Owe Lindgren; Antonio Pizzi; Hamid Reza Mansouri

    2010-01-01

    The industrial application range of welded wood so far has been limited to interior use because of its poor moisture resistance. Influences of some welding and wood parameters such as welding pressure, welding time, and heartwood\\/sapwood on water resistance of Scots pine (Pinus sylvestris) were investigated. An X-ray Computed Tomography scanner was used to monitor density change in weldlines during

  12. Improving the Water Resistance of Linear Vibration-Welded Wood Joints

    Microsoft Academic Search

    H. R. Mansouri; P. Omrani; A. Pizzi

    2009-01-01

    A change in linear welding conditions from those previously used, namely higher vibration frequency (150 Hz) and lower displacement (2 mm) during welding afforded a quicker rise in temperature of the weldline. This allowed a much shorter welding time (1.5 s). This resulted (a) in no fibres being expelled from the welded interface edge and (b) the thin exposed interface

  13. The application of the fusion method of thermit welding to small diameter tubing: An analysis of joint geometry. 

    E-print Network

    Glynn, Thomas Michael

    1972-01-01

    of aluminum. This reaction has been used not only for welding, but for localized heat treating, the production of high quality alloy steel, and as military ordnance. The thermit welding process, specifically, involves the reduction of powdered iron oxide... solidify around the pipe joint, but would not adhere to the pipe due to the layer of slag between them. The operator would then knock the ring of solid thermit steel off the pipe, and it would be disposed of as waste. In this application of thermit...

  14. 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.

  15. 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)

  16. Joint performance of laser-TIG double-side welded 5A06 aluminum alloy

    Microsoft Academic Search

    Yan-bin CHEN; Yu-gang MIAO; Li-qun LI; Lin WU

    2009-01-01

    The influence of welding parameters on mechanical properties and microstructure of the welds of laser-TIG double-side welded 5A06 aluminum alloy was investigated. The results show that the weld cross-sectional shape has an intimate relation with the mechanical properties and microstructure of the welds. The symmetrical “X” cross-section possesses a relatively higher tensile strength and elongation than the others, about 91%

  17. Variation of the creep limit and structure of a welded joint in PT3V titanium alloy under cyclic loading. Report 1

    Microsoft Academic Search

    T. Yu. Yakovleva; V. I. Vlasenko

    1996-01-01

    The creep of PT-3V titanium alloy and of a butt welded joint in this alloy (PT-2V filler material) was investigated on cylindrical specimens 7 mm in diameter with a gage length of 50 mm. The plane of the weld 10-mm wide, produced by manual submerged-arc welding, was situated in the center of the specimen in the direction normal to its

  18. A comprehensive investigation on the effects of laser and shot peening on fatigue crack growth in friction stir welded AA 2195 joints

    Microsoft Academic Search

    Omar Hatamleh

    2009-01-01

    The effects of various surface treatment techniques on the fatigue crack growth performance of friction stir welded 2195 aluminum alloy were investigated. The objective was to reduce fatigue crack growth rates and enhance the fatigue life of welded joints. The crack growth rates were assessed and characterized for different peening conditions at a stress ratio (R) of 0.1, and 0.7.

  19. Accuracy of the Modified Wöhler Curve Method applied along with the r ref = 1 mm concept in estimating lifetime of welded joints subjected to multiaxial fatigue loading

    Microsoft Academic Search

    L. Susmel; C. M. Sonsino; R. Tovo

    2011-01-01

    In the present paper the accuracy of the Modified Wöhler Curve Method (MWCM) in estimating fatigue lifetime of welded joints subjected to multiaxial fatigue loading is investigated when this bi-parametrical critical plane approach is applied in conjunction with the reference radius concept. In more detail, local liner-elastic stress fields in the vicinity of weld toes are suggested as being determined

  20. Investigation into plastic damage behavior of the CO 2 laser deep penetration welded joint for Ti–6Al–4V alloy

    Microsoft Academic Search

    Zhang Jianxun; Song Xu; Zheng Li

    There are great nonlinear gradient distributions of microstructures in CO2 laser deep penetration welded joints of Ti–6Al–4V alloy. Although there are great developments on the damage behavior of titanium alloy, there is a few to investigate the plastic damage behavior of the laser welded joint with heterogeneous microstructures. In order to understand the effects of nonlinear microstructures on the plastic

  1. Influence of flux cored arc welded cruciform joint dimensions on fatigue life of ASTM 517 `F' grade steels

    Microsoft Academic Search

    V Balasubramanian; B Guha

    1998-01-01

    A mathematical model has been developed to predict the fatigue life of flux-cored arc-welded (FCAW) cruciform joints containing lack of penetration (LOP) defects. High strength, quenched and tempered steel (ASTM 517 `F' grade) has been used as the base material throughout the investigation. The design of experiments (DoE) concept has been used to optimize the required number of experiments. Fatigue

  2. A new model to predict the fatigue life of flux cored arc welded cruciform joints containing LOP defects

    Microsoft Academic Search

    V. Balasubramanian; B. Guha

    1998-01-01

    A mathematical model has been developed to predict the fatigue life of Flux Cored Arc Welded (FCAW) cruciform joints containing\\u000a Lack of Penetration (LOP) defect. High strength, Quenched and Tempered steel ASTM 517 ‘F’ Grade has been used as the base\\u000a material throughout the investigation. Two level, full factorial technique has been applied to design the experiments. The\\u000a model has

  3. fatigue assessment of welded joints in AlMg 4.5Mn aluminium alloy (AA 5083) by local approaches

    Microsoft Academic Search

    C. M. Sonsino; D. Radaj; U. Brandt; H. P. Lehrke

    1999-01-01

    Three different local stress approaches, the stress averaging approach, the highly stressed volume approach and the crack propagation approach were applied to the fatigue assessment of welded joints in AlMg 4.5 Mn aluminium alloy (AA 5083) with different stress concentrations and plate thicknesses. These approaches rendered strength or life estimates with acceptable accuracy in the high-cycle fatigue range (N ?

  4. Investigation of fatigue-induced socket-welded joint failures for small-bore piping used in power plants

    Microsoft Academic Search

    Daniel N. Hopkins; Daniel J. Benac

    2001-01-01

    Nuclear power plants typically experience two or three high-cycle fatigue failures of stainless steel socketwelded connections\\u000a in small bore piping during each plant-year of operation. This paper discusses fatigue-induced failure in socket-welded joints\\u000a and the strategy Texas Utilities Electric Company (TU Electric) has implemented in response to these failures. High-cycle\\u000a fatigue is invisible to proven commercial nondestructive evaluation (NDE) methods

  5. Fatigue life prediction of gas tungsten arc welded AISI 304L cruciform joints with different LOP sizes

    Microsoft Academic Search

    P. Johan Singh; D. R. G Achar; B Guha; Hans Nordberg

    2003-01-01

    Fatigue life evaluations have been carried out on gas tungsten arc welded (GTAW) load-carrying cruciform joints of AISI 304L stainless steel with lack of penetration (LOP) using conventional S-N and crack initiation-propagation (I-P) methods. The crack process normally comprises two major phases: (1) the crack initiation life (Ni): and (2) the crack propagation life (Np). The local stress-life approach is

  6. Evaluation of impact properties of weld joint of reactor pressure vessel steels with the use of miniaturized specimens

    Microsoft Academic Search

    Byung Jun Kim; Hideaki Mitsui; Ryuta Kasada; Akihiko Kimura

    2012-01-01

    The effects of specimen size and location of V-notch on the Charpy impact properties were investigated with different sizes of specimens, standard, CVN-1\\/2, CVN-1\\/3, and CVN-1.5 mm, for A533B steel, low Mn, high Cu, high phosphorus (P), and high Cu\\/P steel weld joint. A part of the specimens was irradiated with neutron at 563 K up to 8 × 10 n\\/cm. The heat affected

  7. Comparative study on characteristics of hybrid laser-TIG welded AZ61\\/Q235 lap joints with and without interlayers

    Microsoft Academic Search

    Xiao-Dong Qi; Li-Ming Liu

    2010-01-01

    AZ61 Mg alloy to Q235 mild steel were lap joined using hybrid laser-TIG welding technique. At the joint interface and fusion\\u000a zone (FZ), microstructure was revealed by scanning electron microscopy equipped with energy dispersive X-ray spectroscopy;\\u000a element distribution was analyzed by electron probe micro-analyzer; intermediate phases were identified using X-ray diffraction\\u000a test. Comparing with interlayer-free joints, the new intermediate phases

  8. 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.

  9. 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.

    2015-04-01

    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.

  10. Numerical modelling and strength prediction of welded double lap joints made of timber

    Microsoft Academic Search

    Till Vallée; Yves Weinand; Benjamin Hahn; Bernhard Stamm

    2011-01-01

    Welding of wood is a relatively new method of joining load bearing elements, which holds the potential to compete with structural adhesion, since it allows for an almost instantaneous bond. First experimental and numerical investigations showed that failure of wood-welded connections is linked to a combination of shear and transverse-tensile stresses in the welded interface. One of the main conclusions

  11. Effects of Welding Parameters Onto Keyhole Geometry for Partial Penetration Laser Welding

    NASA Astrophysics Data System (ADS)

    Vänskä, M.; Abt, F.; Weber, R.; Salminen, A.; Graf, T.

    The material and parameters like welding speed and laser beam parameters define the geometry of the keyhole. The keyhole geometry affects the weld geometry, such as width and depth, and in some cases it should be considered when selecting welding parameters. In-situ X-ray videography makes it possible to obtain time-and space resolved information about the keyhole geometry during the welding process. This paper describes the partial penetration laser welding experiments and shows the effects of a welding speed and a focal point position change onto some geometry values of the keyhole. Two different joint types were used, bead on plate to simulate a very good machined joint preparation and laser cut I-butt joint.

  12. 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.

  13. 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

    2015-04-01

    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.

  14. An investigation of the peening effects on the residual stresses in friction stir welded 2195 and 7075 aluminum alloy joints

    Microsoft Academic Search

    Omar Hatamleh; Adrian DeWald

    2009-01-01

    Surface treatment processes including laser and shot peening were applied to friction stir welded samples fabricated using aluminum alloys (AA) 2195 and 7075. Surface residual stress measurements on these samples were acquired using X-ray diffraction. Measurements of the through thickness bulk residual stresses were obtained using the contour method. The deepest compressive residual stresses were obtained with multiple layers of

  15. ANALYSIS OF RESIDUAL STRESS STATE IN WELDED STEEL PLATES BY X-RAY DIFFRACTION METHOD

    Microsoft Academic Search

    Vladimir I. Monin

    2009-01-01

    There were investigated geometrical distortions of two steel plates jointed by metal inert gas welding. The distributions of residual stresses in this welded joint were measured by X-ray diffraction method. The measured residual stress distributions were compared with residual stress state obtained by means of finite element analysis with using of ABAQUS software. A good agree- ment was obtained between

  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. Effect of pulsed current welding on fatigue behaviour of high strength aluminium alloy joints

    Microsoft Academic Search

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

    2008-01-01

    High strength aluminium alloys (Al–Zn–Mg–Cu alloys) have 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 high strength aluminium alloy are frequently gas tungsten arc welding (GTAW) process and gas metal arc welding (GMAW) process due

  19. A New Method for Reduction of Residual Stress of Welded Joint Using Ultrasonic Vibrational Load

    Microsoft Academic Search

    Shigeru Aoki; Seiji Hirai; Tadashi Nishimura; Tetsumaro Hiroi

    A new method for reduction of residual stress using ultrasonic vibrational load during welding is proposed. The proposed method\\u000a is examined experimentally. First, in order to simulate butt-welding of thin plates, reduction of residual stress is examined\\u000a by using a specimen with a groove and specimens supported on the supporting device. Next, in order to simulate repair welding\\u000a of press

  20. Mechanical properties of laser-welded cast titanium joints under different conditions

    Microsoft Academic Search

    Tsongi Chai; Chia Kai Chou

    1998-01-01

    Statement of the problem. Data on optimal conditions for laser welding commercial pure cast titanium used in dental restorations are sparse and not well established.Purpose. The mechanical properties of laser-welded cast commercially pure titanium under different laser welding conditions were evaluated to find the optimal parameters in terms of duration and voltage (energy level).Material and methods. Fifty-seven cast pure titanium

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

    SciTech Connect

    Liu, Fei; Wang, Hongyang; Liu, Liming, E-mail: liulm@dlut.edu.cn

    2014-04-01

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

  2. Effects of heat input on microstructure and mechanical property of Al\\/Ti joints by rectangular spot laser welding-brazing method

    Microsoft Academic Search

    Yanbin Chen; Shuhai Chen; Liqun Li

    2009-01-01

    A rectangular spot laser welding–brazing method was developed to join butted Ti\\/Al dissimilar alloys. In order to evaluate\\u000a effects of heat input on mechanical property of the joints, microstructure of the joints were characterized. TiAl3 intermetallic compounds (IMCs) were found at the joint interface in the case of low-heat input and TiAl3, TiAl, Ti5Si3, and Ti3Al IMCs were observed at

  3. Effect of calcium on intermetallic compound layer at interface of calcium added magnesium–aluminum alloy and titanium joint by friction stir welding

    Microsoft Academic Search

    Masayuki Aonuma; Kazuhiro Nakata

    2010-01-01

    Commercial AMCa602 alloy (Mg–6% Al–2% Ca) and AM60 alloy (Mg–6% Al) were joined to titanium plates by friction stir welding to evaluate the effect of a calcium on the reaction layer at the dissimilar joint interface and the joint tensile strength. At the titanium and AM60 joint interface, a TiAl3 intermetallic compound layer was formed. The thickness of this layer

  4. Effects of residual stress, weld toe notch and weld defects on fatigue of welded steel structures

    NASA Astrophysics Data System (ADS)

    Shen, Wenyu

    In studying the fatigue behavior of fillet welded railroad tank car shell structures, the effects of welding residual stress, weld toe notch, and weld defects on the fatigue of fillet welded A515 steel specimens were evaluated. Both hole-drilling and sectioning measurement techniques were used to obtain residual stress information. Pad-on-plate weld specimens were designed to simulate the tank car structure for welding residual stress measurement. Simple bead-on-plate and fillet weld specimens, which have similar welding residual stresses near the weld end toe to the pad-on-plate specimens, were designed to be as compact as possible for fatigue testing. As-welded and stress-relieved simple weld specimens were tested under pulsed tension and alternating cyclic load conditions to determine stress-life and fatigue crack propagation properties. Weld toe stress concentration effects were determined by strain gage measurement. Fracture surface features and crack initiation sites were studied by visual analysis, scanning electron microscopy, and optical microscopy. Welding residual stresses were found to be biaxial tension-compression near the weld end toe and biaxial tension-tension near the weld center toe. Longitudinal tensile residual stress was significantly relieved when the applied longitudinal tensile cyclic load was greater than 14 Ksi. Test results did not show a consistent effect of tensile residual stress on the fatigue strength under pulsed tension loads. However, tensile residual stress had a significant influence on the fatigue strength under alternating cyclic loads. The weld end toe was associated with a stress concentration factor of approximately 3 and was the most critical factor in initiating fatigue cracks. Weld defects, such as slag inclusions, lack of fusion, and porosity were found to significantly affect the fatigue strength of a welded joint when the load magnitude or mean stress was low. An equivalent crack concept, based on linear elastic fracture mechanics theory, was introduced to quantify the weld toe stress concentration effect. This concept was shown to be effective for fatigue design life prediction of welded structures.

  5. 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.

  6. Fatigue Damage Evaluation of Friction Stir Spot Welded Cross-Tension Joints Under Repeated Two-Step Force Amplitudes

    NASA Astrophysics Data System (ADS)

    Joy-A-Ka, Sutep; Ogawa, Yuki; Akebono, Hiroyuki; Kato, Masahiko; Sugeta, Atsushi; Sun, Yufeng; Fujii, Hidetoshi

    2015-06-01

    This paper investigates an approach to evaluate the fatigue damage of FSSW cross-tension specimens under two-step force amplitude conditions. In fatigue tests with repeated two-step force amplitude, the fatigue limit of the welded joint disappeared. However, the fatigue damage evaluation using the modified Miner's rule erred too much on the side of safety, as the modified Miner's rule tends to overestimate the damage by applied forces below the fatigue limit. Thus, it was determined that, within the testing conditions used in this study, the fatigue damage evaluation using Haibach's method yielded an accurate evaluation. In the case where significant plastic deformation caused by the applied force occurred near the welded zone, the cumulative fatigue damage value based on Miner's rule was often larger than unity. Therefore, it is important to consider a cumulative damage estimation that takes into account the effect of pre-strain from the high force amplitude.

  7. 49 CFR 179.300-9 - Welding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... (a) Longitudinal joints must be fusion welded. Head-to-shell joints must be forge welded on class DOT-106A tanks and fusion welded on class DOT-110A tanks. Welding...171.7 of this subchapter). (b) Fusion-welded joints must be in...

  8. 49 CFR 179.300-9 - Welding.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... (a) Longitudinal joints must be fusion welded. Head-to-shell joints must be forge welded on class DOT-106A tanks and fusion welded on class DOT-110A tanks. Welding...171.7 of this subchapter). (b) Fusion-welded joints must be in...

  9. 49 CFR 179.300-9 - Welding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... (a) Longitudinal joints must be fusion welded. Head-to-shell joints must be forge welded on class DOT-106A tanks and fusion welded on class DOT-110A tanks. Welding...171.7 of this subchapter). (b) Fusion-welded joints must be in...

  10. Microstructure development in Nd:YAG laser welding of AISI 304 and Inconel 600

    Microsoft Academic Search

    Maurício David M. das Neves; André Lotto; José Roberto Berretta; Wagner de Rossi; Nilson Dias V. Júnior

    2010-01-01

    In this work, the morphology of solidification of the weld zone (WZ) was studied in a joint formed from dissimilar materials, composed of austenitic AISI 304 stainless steel and Inconel 600 nickel alloy, welded with an Nd:YAG-pulsed laser. The laser beam and optical system parameters were selected with a view to obtain a weld with total penetration and good surface

  11. 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.

  12. Fatigue Life Improvement for Cruciform Welded Joint by Mechanical Surface Treatment using Hammer Peening and UNSM

    Microsoft Academic Search

    Seung-Ho Han; Jeong-Woo Han; Yong-Yun Nam; In-Ho Cho

    2009-01-01

    For the improvement of fatigue strength of welded structures, mechanical post treatments have been applied in various industrial fields and have in most cases been founded to give substantial increases in their fatigue lives. These methods, generally, consist of the modification of weld toe geometry and the introduction of compressive residual stresses. In mechanical surface treatments, e.g. PHP (pneumatic hammer

  13. Modeling of temperature distribution in ultrasonic welding of thermoplastics for various joint designs

    Microsoft Academic Search

    K. S. Suresh; M. Roopa Rani; K. Prakasan; R. Rudramoorthy

    2007-01-01

    Use of engineering plastics in structural and non-structural applications is rapidly increasing. As the demand for plastics increases so does the requirements for joining. Of the many techniques that are available for joining of thermoplastics, ultrasonic welding is one of the preferred processes. Thermoplastic polymers are categorized according to their molecular structure as amorphous and semi-crystalline. Ultrasonic welding of these

  14. Welding Residual Stresses in Two Competing Single V-Butt Joints

    Microsoft Academic Search

    Pornwasa Wongpanya

    During fabrication of welded components residual stresses are generated as a result of non-uniform temperature distribution during the welding and particularly the cooling process. Such residual stresses have a major effect on the overall performance of a component in service, especially when hydrogen is involved and the component might become prone to Hydrogen Assisted Cold Cracking (HACC). Up to the

  15. 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).

  16. Effect of 0.5 wt.% hydrogen addition on microstructural evolution of Ti–6Al–4V alloy in the friction stir welding and post-weld dehydrogenation process

    Microsoft Academic Search

    L. Zhou; H. J. Liu

    2011-01-01

    The ?+? titanium alloy, Ti–6Al–4V, was thermohydrogen processed with 0.5wt.% hydrogen and friction stir welded using a W–Re pin tool. Defect-free joints were obtained with proper parameters. Hydrogen was removed from the joint through a post-weld dehydrogenation process. The microstructures of the as-welded and dehydrogenated joints were examined. The effect of 0.5wt.% hydrogen addition on microstructural evolution of Ti–6Al–4V alloy

  17. 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.

  18. Variation of the creep limit and structure of a welded joint in pT3V titanium alloy under cyclic loading. Report 3

    Microsoft Academic Search

    T. Yu. Yakovleva; V. I. Vlasenko

    1996-01-01

    The metallographic methods and microanalysis were used for investigation of the welded butt-joint specimens from PT-3V titanium\\u000a alloys. The specimens were in initial state and after cyclic loading. Duration of loading was 5104 and 1107 cycles on a\\u000a frequency of 35 Hz. The stress amplitude was 150 MPa; this value is below the endurance limit of weld material. The polished

  19. Fatigue strength improvement of 5083 H11 Al-alloy T-welded joints by shot peening: experimental characterization and predictive approach

    Microsoft Academic Search

    N. Sidhom; A. Laamouri; R. Fathallah; C. Braham; H. P. Lieurade

    2005-01-01

    Shot peening improvement of high cycle fatigue (HCF) behavior of metal inert gas (MIG) welded T-joints made from 5083 H11 Al-alloy plates using 5183 Al-alloy welding wires was evaluated by means of four-point bending fatigue tests. The enhancement of the fatigue limits at 2×106 cycles were 135 and 59% for the stress ratios R1=0.1 and R2=0.5, respectively. The properties of

  20. Influence of incomplete annealing of titanium (a + ?)-alloy and its welded joints on fatigue resistance and corrosion-fatigue resistance

    Microsoft Academic Search

    O. S. Kalakhan; V. I. Pokhmurs’kyi

    2000-01-01

    We investigate the influence of incomplete annealing (675?C, 10 h) on fatigue, corrosion-fatigue, and high-temperature (up\\u000a to 500?C) fatigue resistance of titanium (a+ ?)-alloy Ti-5A1- 1.5V- IMo with nominal composition as well as its welded joints\\u000a made by the electron-beam method. The effect of annealing depends on a totality of factors which dominate in different ways\\u000a under fatigue fracture in

  1. Polishing-assisted galvanic corrosion in the dissimilar friction stir welded joint of AZ31 magnesium alloy to 2024 aluminum alloy

    SciTech Connect

    Liu, C. [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Chen, D.L. [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada)], E-mail: dchen@ryerson.ca; Bhole, S. [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Cao, X.; Jahazi, M. [Aerospace Manufacturing Technology Centre, Institute For Aerospace Research, National Research Council Canada, 5145 Decelles Avenue, Montreal, Quebec H3T 2B2 (Canada)

    2009-05-15

    Galvanic corrosion of a dissimilar friction stir welded 2024-T3 Al/AZ31B-H24 Mg joint prepared using a water-based and a non-water-based polishing solution was characterized. Microstructure and the distribution of chemical elements were analyzed using optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. The stir zone polished using water-based solution was observed to be much more susceptible to galvanic corrosion attack than that obtained using non-water-based polishing solution. The location of corrosion attack was observed in the narrow regions of AZ31 Mg alloy adjacent to Al2024 regions in the stir zone. The occurrence of galvanic corrosion was due to the formation of Mg/Al galvanic couples with a small ratio of anode-to-cathode surface area. The corrosion product was primarily the porous magnesium hydroxide with characteristic microcracks and exhibited a low microhardness value.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. A Comparative Analysis of the Impact of Tool Design to Fatigue Behavior of Single-Sided and Double-Sided Welded Butt Joints of EN AW 6082-T6 Alloy

    NASA Astrophysics Data System (ADS)

    Krasnowski, K.; Dymek, S.

    2013-12-01

    In this paper, the results of fatigue behavior on friction stir welded joints of aluminum alloy EN AW 6082-T6 are reported. In particular, the study presents the influence of the geometry of a welding tool on fatigue strengths and tensile strengths. The test joints were prepared as single side welded and double side welded by FSW. The welding was performed at various linear welding speeds (224, 560, and 900 mm/min) and one rotational speed of 710 rev./min using three different tool shapes. The results of macro examination and tensile test led to the selection of a single set of tool movement parameters at which the test joints for fatigue test were made. Samples were tested in two states of surface condition, i.e., "as-welded" and with mechanically removed marks left by rotating and moving tool during FSW process. Studies have shown that fatigue behavior of FSW joints depends on the tool shape used in the welding process as well as the surface condition of welded joints and manner of joint production.

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

    NASA Astrophysics Data System (ADS)

    Akinlabi, E. T.

    2012-07-01

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

  10. Fatigue behaviour of laser and resistance seam welds in the automotive industry

    Microsoft Academic Search

    P. Lazzarin; E. Rabino; D Zandonella Necca

    1995-01-01

    This paper summarises fatigue strength in laser?welded butt joints made of Fe P04?UNI 8092 deep drawing steel with standard and galvanized surfaces. The Wöhler curves obtained are compared with those of a series of seam?welded joints, which have been subjected to special forging of the beads after welding.Fatigue behaviour is similar to that of the parent material since fracture does

  11. Analysis of residual stress in stainless steel pipe weld subject to mechanical axial tension loading

    Microsoft Academic Search

    Kyong-Ho Chang; Chin-Hyung Lee; Ki-Tae Park; Young-Jun You; Bong-Chul Joo; Gab-Chul Jang

    2010-01-01

    This paper presents the characteristics of welding residual stresses in circumferentially butt-welded stainless steel pipe\\u000a by utilizing three-dimensional (3-D) uncoupled thermo-mechanical finite element (FE) analysis method. Moreover, stress variations\\u000a in welded joints of the pipe under superimposed mechanical axial tension loading are further investigated employing the welding\\u000a residual stresses and plastic strains obtained from the thermo-mechanical FE analysis as an

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

    SciTech Connect

    Creutz, M.; Mewes, D. [Inst. fuer Verfahrenstechnik, Hannover (Germany); Bartzsch, J.; Draugelates, U. [Inst. fuer Schweisstechnik und Trennende Fertigungsverfahren, Clausthal-Zellerfeld (Germany)

    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.

  13. Sensor fusion using neural network in the robotic welding

    SciTech Connect

    Ohshima, Kenji; Yabe, Masaaki; Akita, Kazuya; Kugai, Katsuya; Yamane, Satoshi [Saitama Univ., Urawa, Saitama (Japan); Kubota, Takefumi [Himeji Inst. of Tech., Himeji, Hyougo (Japan)

    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.

  14. The Guiding of Ultrasound by a Welded Joint in a Plate

    NASA Astrophysics Data System (ADS)

    Juluri, Naresh; Lowe, Michael; Cawley, Peter

    2007-03-01

    Experimental observation has shown that a compression wave (similar to the Lamb wave S0) traveling along a weld between two plates is strongly guided by the weld and so does not decay as quickly as it would in a plain plate. This phenomenon is attractive for NDE because it may offer the potential to inspect long lengths of weld using a wave which travels along the weld and is guided by it. In order to understand the guiding phenomenon, studies have been carried out on an idealized structure consisting of a plate with a thickened region of rectangular cross section. Finite element simulations and experimental measurements of waves propagating along this structure have revealed the physics of the guiding effect. The guiding occurs principally because of the geometry: the wave in the thickened region is slower than that in the plate. The paper discusses the nature of the guiding effect, illustrates the effects, and proposes its potential for practical NDE of welds and other geometric features.

  15. Effect of the Surface State of Steel on the Microstructure and Mechanical Properties of Dissimilar Metal Lap Joints of Aluminum and Steel by Friction Stir Welding

    Microsoft Academic Search

    Y. C. Chen; K. Nakata

    2008-01-01

    Friction stir lap joints of AC4C Al alloy (top sheet) and steel (zinc-coated steel, brushed finish steel, and mirror finish\\u000a steel) were produced when the friction stir welding tool did not touch the lower steel surface. For zinc coat steel, the strength\\u000a of joints could reach 97.7 pct of that of steel; for brushed finish steel, the strength was 63.2 pct of

  16. Experimental study on fatigue performance and damage model of aluminum alloy welding joints for high-speed train car body

    Microsoft Academic Search

    Wenjing Wang; Qiang Li; Zhiming Liu; Binjie Wang

    2009-01-01

    In order to realize lightweight, security and comfort, the aluminum alloy profile becomes the first choice of the high speed train carbody. The fatigue experiments are carried on the typical welding joins such as butt, fillet, cruciform and lap joins. The fatigue limits and P-S-N curves are obtained. The non-linearity cumulative damage model is proposed taking loading sequences for consideration

  17. Modeling buckling distortion of DP600 overlap joints due to gas metal arc welding and the influence of the mesh density

    Microsoft Academic Search

    T. Schenk; I. M. Richardson; M. Kraska; S. Ohnimus

    2009-01-01

    This paper presents a computational framework for the modeling of buckling distortion of 1mm thick DP600 overlap joints due to gas metal arc welding. The results have been compared to experiments and show good agreement. The simulations have been repeated for various FE meshes and different linear finite elements. It is shown that not only the distortion amplitude but also

  18. Effect of Segregation of Secondary Phase Particles and "S" Line on Tensile Fracture Behavior of Friction Stir-Welded 2024Al-T351 Joints

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Xiao, B. L.; Ma, Z. Y.

    2013-09-01

    A 5-mm-thick 2024Al-T351 plate was friction stir welded (FSWed) at welding speeds of 100, 200, and 400 mm min-1 with a constant rotation rate of 800 rpm, and the microstructure and tensile fracture behavior of the joints were investigated in detail. FSW resulted in the redistribution of secondary phase particles along the recrystallized grain boundaries at the nugget zone (NZ), forming linear segregation bands consisting of secondary phase particles. The segregation bands, mainly present in the shoulder-driven zone, were believed to result from periodic material flow, with the average band spacing on the longitudinal and horizontal cross sections equal to the tool advancement per revolution. At a low welding speed of 100 mm min-1, in spite of the highest density of segregation bands, the FSWed 2024Al-T351 joint fractured along the low hardness zone (LHZ) of the heat-affected zone because of large hardness gap between NZ and LHZ. Increasing the welding speed to 200 and 400 mm min-1 reduced both the hardness gap between NZ and LHZ and the density of segregation bands. In this case, the segregation bands played a role, resulting in unusual fracture of the joints along the segregation bands. The "S" line originated from the oxide film on the initial butting surfaces and did not affect the fracture behavior of the FSWed 2024Al-T351 joints.

  19. Three different ways of using the Modified Wöhler Curve Method to perform the multiaxial fatigue assessment of steel and aluminium welded joints

    Microsoft Academic Search

    Luca Susmel

    2009-01-01

    The present paper reviews the different procedures to be followed to use the Modified Wöhler Curve Method (MWCM) to estimate fatigue lifetime of steel and aluminium welded joints subjected to multiaxial cyclic loading. In more detail, the MWCM is a conventional critical plane approach which postulates that fatigue damage reaches its maximum value on the plane experiencing the maximum shear

  20. Fabrication procedure effects on fatigue resistance of rib -to-deck welded joints of steel orthotropic bridge decks

    E-print Network

    Sim, Hyoung-Bo

    2010-01-01

    in orthotropic steel bridge decks. ” Welding in the World ,steel plates and closed ribs joined together by extensive welding,steel decks have experienced a variety of fatigue problems, resulting from high cyclic stresses in conjunction with poor welding

  1. 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

  2. Identification of diffusion parameters in welded joints of titanium and its alloys

    Microsoft Academic Search

    Andrzej Sluzalec

    2009-01-01

    Titanium and its alloys may experience a progressive embrittlement leading to catastrophic failure. Such embrittlement is a consequence of hydrogen migration and the accumulation of brittle titanium hydrides in the presence of a sharp alloy composition gradient near a weld fusion line. The governing equations for such migration are presented. The identification problem for parameters responsible for this phenomenon is

  3. Estimation of the fatigue life according to lap joint weld profiles for ferritic stainless steel

    Microsoft Academic Search

    Jaesong Kim; Kyungmin Lee; Boyoung Lee

    2011-01-01

    Steel structures such as ships, ocean structures, automobile, aircraft and bridges should be designed and manufactured to be able to endure under various environmental conditions such as static load, impact, fatigue and torsion etc. Especially, many researches about improvement of fatigue strength have been performed in relation towelding to be used for connection of steel structures. In case that welded

  4. 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.

  5. Influence of Machine Setting and Wood Parameters on Crack Formation in Scots Pine Joints Produced by Linear Friction Welding

    Microsoft Academic Search

    Mojgan Vaziri; Owe Lindgren; Antonio Pizzi

    2012-01-01

    Previous investigations on linear welded woods have shown that the connections are not sufficiently resistant to water for use in outdoor conditions. Therefore, they are utilized mainly for non-structural use, with only short time exposure to varying humidity. Influences of some welding and wood parameters such as welding pressure, welding time and heartwood or sapwood on crack formation in the

  6. Numerical and experiment analysis of residual stress on magnesium alloy and steel butt joint by hybrid laser-TIG welding

    Microsoft Academic Search

    Zhi Zeng; Xunbo Li; Yugang Miao; Gang Wu; Zijun Zhao

    2011-01-01

    Hybrid welding technology has received significant attention in the welding of dissimilar materials recently. While, great welding residual stress and deformation often result by the difference of coefficient of thermal expansion This study describes the thermal elastic–plastic analysis using finite element techniques to analyze the thermo mechanical behavior and evaluate the residual stresses and welding distortion on the AZ31B magnesium

  7. 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

  8. Corrosion fatigue strength of ship structural steel butt welded joints in synthetic sea-water

    Microsoft Academic Search

    Y. Kobayashi; Y. Tanaka; H. Goto; K. Matsuoka; Y. Motohashi

    1999-01-01

    This paper describes an investigation into the corrosion fatigue strength of a MAG-welded 50 MPa class TMCP steel in fatigue tests carried out under a constant-amplitude load at a stress ratio of 0.1 in air and synthetic sea-water. The tests took place under natural corrosion conditions at 25°C at a cycling rate in air and sea water of 3–12 and

  9. Mechanical heterogeneity and validity of J-dominance in welded joints

    Microsoft Academic Search

    Jianqing Fu; Yaowu Shi

    2000-01-01

    Fracture criterion of the J-integral finds wide application in the integrity evaluation of welded components, but there exist some confused problems such as the dependence of the fracture toughness on the strength mis-matching and specimen geometry which need to be clarified. It is rough and unsuitable to attribute the variation of J-integral fracture parameter simply to the effect of mechanical

  10. The use of the J V parameter in welded joints: Stress analysis and fatigue assessment

    Microsoft Academic Search

    Paolo Livieri; Roberto Tovo

    2009-01-01

    This paper investigates the use of the JV parameter, a path-independent integral, for the evaluation of the elastic local stress parameters in welded details and for the estimation of their fatigue life.First, the stress intensity factors (SIF) of an embedded crack lying along the bisector of a sharp V-notch is calculated by means of the JV without modelling the crack

  11. Multiple-beam irradiation effects in electron-beam-welded F82H joint

    Microsoft Academic Search

    N. Hashimoto; H. Tanigawa; H. Kinoshita; S. Ohnuki

    2011-01-01

    Electron-beam-welded reduced-activation ferritic\\/martensitic steel F82H, which is one of prime candidate materials for experimental fusion reactors, have been irradiated by electron and helium ion beams using a High Voltage Electron Microscope (HVEM) as the experimental evaluation of the modeling and simulations. Growth rate and saturated number density of dislocation loops have been measured to calculate the migration energies of point

  12. Metallurgical and mechanical characterization of electron beam welded DP600 steel joints

    Microsoft Academic Search

    P. Ferro; A. Tiziani

    Several new commercial advanced high-strength steels exhibit high strength and enhanced formability. These materials have\\u000a the potential to affect cost and weight saving while improving performance. However, welding, by modifying the microstructure\\u000a of the steel, has in general a detrimental effect on the mechanical properties of structural components. If high power density\\u000a technologies are used, the result is that the

  13. 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.

  14. Improvement of laser keyhole formation with the assistance of arc plasma in the hybrid welding process of magnesium alloy

    Microsoft Academic Search

    Liming Liu; Xinfeng Hao

    2009-01-01

    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

  15. Comparative potential of alternative wood welding systems, ultrasonic and microfriction stir welding

    Microsoft Academic Search

    G. Tondi; S. Andrews; A. Pizzi; J.-M. Leban

    2007-01-01

    Two alternative welding systems were evaluated for wood welding. Ultrasonic welding produces joints of good strength but it appears to be applicable only to thin wood pieces. It does not appear that further possible process improvement could bring the joint strength to a structural level. Microfriction stir welding does show potential for welding continuously wooden plates without any limitation on

  16. 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.

  17. Effect of Welding Parameters on the Microstructure and Strength of Friction Stir Weld Joints in Twin Roll Cast EN AW Al-Mn1Cu Plates

    NASA Astrophysics Data System (ADS)

    Birol, Yucel; Kasman, Sefika

    2013-10-01

    Twin roll cast EN AW Al-Mn1Cu plates were butt welded with the friction stir welding process which employed a non-consumable tool, tilted by 1.5° and 3° with respect to the plate normal, rotated in a clockwise direction at 400 and 800 rpm, while traversing at a fixed rate of 80 mm/min along the weld line. Microstructural observations and microhardness tests were performed on sections perpendicular to the tool traverse direction. Tensile tests were carried out at room temperature on samples cut perpendicular to the weld line. The ultimate tensile strength of the welded EN AW Al-Mn1Cu plates improved with increasing tool rotation speed and decreasing tool tilt angle. This marked improvement in ultimate tensile strength is attributed to the increase in the heat input owing to an increased frictional heat generation. There appears to be a perfect correlation between the ultimate tensile strength and the size of the weld zone. The fracture surfaces of the base plate and the welded plates are distinctly different. The former is dominated by dimples typical of ductile fractures. A vast majority of the intermetallic particles inside the weld zones are too small to generate dimples during a tensile test. The fracture surface of the welded plates is thus characterized by occasional dimples that are elongated in the same direction suggesting a tensile tearing mechanism.

  18. Developments of electrical joints for aluminium stabilized superconducting tables

    E-print Network

    Fabbricatore, P; Farinon, S; Horváth, I; Musenich, R; Prian, C

    1999-01-01

    Electrical joints for the aluminum stabilized conductors of the LHC experiment magnets have been studied. Two techniques have been tested: electron beam welding and MIG welding. The joint resistance was measured as a function of the magnetic field on ring shaped samples using the MA.RI.S.A. test facility: varying the magnet field, current is induced in the sample. The resistance is obtained by measuring either the voltage drop or the decay time. Calculation and FE simulation have been performed in order to separate the effect of both the copper-aluminum contact resistivity and the aluminum resistivity from the effect due to the joint technique ( joint configuration, resistivity of the filler material, increasing of aluminum resistivity in the welding zone). The copper-aluminum contact resistivity and the current transfer length were obtained by measurements of the joint resistance of butt welded samples

  19. Developments of electrical joints for aluminum-stabilized superconducting cables

    E-print Network

    Curé, B

    1999-01-01

    Electrical joints for the aluminum-stabilized conductors of the LHC experiment magnets have been studied. Two techniques have been tested: electron beam welding and MIG welding. The joint resistance was measured as a function of the magnetic field on ring shaped samples using the MA.RI.S.A. test facility, wherein current is induced in the test conductor by a varying magnetic field. The resistance is obtained by measuring either the voltage drop or the decay time. Calculation and finite-element simulation have been performed in order to separate the effect of both the copper-aluminum contact resistivity and the aluminum resistivity from the effect due to the joint technique (joint configuration, resistivity of the filler material, increasing of aluminum resistivity in the welding zone). The copper-aluminum contact resistivity and the current transfer length were obtained by measurements of the joint resistance of butt welded samples. (2 refs).

  20. Efficient weld seam detection for robotic welding based on local image processing

    Microsoft Academic Search

    Fanhuai Shi; Tao Lin; Shanben Chen

    2009-01-01

    Purpose – The weld seam detection is required for a welding robot to preplan the weld seam track before the actual welding. The purpose of this paper is to investigate this subject in natural lighting conditions. Design\\/methodology\\/approach – This paper presents an efficient algorithm of weld seam detection for butt joint welding from a single image. The basic idea of

  1. 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 [ORNL; Kim, Jin Weon [ORNL

    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.

  2. Application of YAG Laser TIG Arc Hybrid Welding to Thin AZ31B Magnesium Alloy Sheet

    NASA Astrophysics Data System (ADS)

    Kim, Taewon; Kim, Jongcheol; Hasegawa, Yu; Suga, Yasuo

    A magnesium alloy is said to be an ecological material with high ability of recycling and lightweight property. Especially, magnesium alloys are in great demand on account of outstanding material property as a structural material. Under these circumstances, research and development of welding process to join magnesium alloy plates are of great significance for wide industrial application of magnesium. In order to use it as a structure material, the welding technology is very important. TIG arc welding process is the most ordinary process to weld magnesium alloy plates. However, since the heat source by the arc welding process affects the magnesium alloy plates, HAZ of welded joint becomes wide and large distortion often occurs. On the other hand, a laser welding process that has small diameter of heat source seems to be one of the possible means to weld magnesium alloy in view of the qualitative improvement. However, the low boiling point of magnesium generates some weld defects, including porosity and solidification cracking. Furthermore, precise edge preparation is very important in butt-welding by the laser welding process, due to the small laser beam diameter. Laser/arc hybrid welding process that combines the laser beam and the arc is an effective welding process in which these two heat sources influence and assist each other. Using the hybrid welding, a synegistic effect is achievable and the disadvantages of the respective processes can be compensated. In this study, YAG laser/TIG arc hybrid welding of thin magnesium alloy (AZ31B) sheets was investigated. First of all, the effect of the irradiation point and the focal position of laser beam on the quality of a weld were discussed in hybrid welding. Then, it was confirmed that a sound weld bead with sufficient penetration is obtained using appropriate welding conditions. Furthermore, it was made clear that the heat absorption efficiency is improved with the hybrid welding process. Finally, the tensile tests of welded joints were performed, and it was confirmed that they have sufficient mechanical properties. As a result of this study, it is confirmed that, if the appropriate welding conditions are selected, sound welded joints of AZ31B magnesium alloy are obtainable by the YAG laser/TIG arc hybrid welding process.

  3. 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.

  4. Torch kit for welding in difficult areas

    NASA Technical Reports Server (NTRS)

    Stein, J. A.

    1971-01-01

    Miniature tungsten inert gas welding torch, used with variously formed interchangeable soft copper tubing extensions, provides inexpensive, accurate welding capability for inaccessible joints. Kit effectively welds stainless steel tubing 0.089 cm thick. Other applications are cited.

  5. 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.

  6. 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.

  7. Effect of alloying elements on interface microstructure of Mg–Al–Zn magnesium alloys and titanium joint by friction stir welding

    Microsoft Academic Search

    Masayuki Aonuma; Kazuhiro Nakata

    2009-01-01

    An effect of alloying element on interfacial microstructure of Mg–Al–Zn alloys and Ti dissimilar butt joints by friction stir welding (FSW) was studied. Mg–Al–Zn alloy and Ti plates of 2mm in thickness were successfully butt joined by inserting a probe into the Mg alloy plate and slightly offsetting it by 0.5mm into the Ti plate side. Al-rich thin layers and

  8. Variation of the creep limit and structure of a welded joint in PT3V titanium alloy under the effect of cyclic loading. Report 2

    Microsoft Academic Search

    T. Yu. Yakovleva; V. I. Vlasenko

    1996-01-01

    Comparative analysis of the characteristics of amplitude-dependent internal friction (IF) was carried out to explain reasons leading to an increase of the creep limit of the butt welded joint in PT-3V titanium alloy (PT-2V filler material) after cyclic loading. IF was measured by the method of the direct torsional pendulum on cylindrical specimens representing the gage part of the specimens

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

    Microsoft Academic Search

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

    2009-01-01

    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

  10. Effects of copper addition on microstructure and strength of the hybrid laser-TIG welded joints between magnesium alloy and mild steel

    Microsoft Academic Search

    Liming Liu; Xiaodong Qi

    2009-01-01

    Lap joint of magnesium alloy AZ31B to mild steel Q235 with the addition of copper interlayer by hybrid laser-TIG welding technique\\u000a was investigated. The microstructure, element distribution at interfaces, and intermediate phases of joints were examined\\u000a by scanning electron microscopy (SEM), electron probe micro-analyzer (EPMA), and X-ray diffraction (XRD), respectively. The\\u000a results showed that intermetallic compounds Mg2Cu with rod-like structure

  11. Effect of formation and state of interface on joint strength in friction stir spot welding for advanced high strength steel sheets

    NASA Astrophysics Data System (ADS)

    Taniguchi, Koichi; Matsushita, Muneo; Ikeda, Rinsei; Oi, Kenji

    2014-08-01

    The tensile shear strength and cross tension strength of friction stir spot welded joints were evaluated in the cases of lap joints of 270 N/mm2 grade and 980 N/mm2 grade cold rolled steel sheets with respect to the stir zone area, hardness distribution, and interface condition between the sheets. The results suggested that both the tensile shear strength and cross tension strength were based on the stir zone area and its hardness in both grades of steel. The "hook" shape of the interface also affected the joint strength. However, the joining that occurred across the interfaces had a significant influence on the value of the joint strength in the case of the 270 N/mm2 grade steel.

  12. Influence of Microstructure of Friction Stir Welded Joints on Growth and Properties of Microarc Oxidation Coatings on AZ31B Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Chen, Tingfang; Li, Yongliang; Xue, Wenbin; Yang, Chaolin; Qu, Yao; Hua, Ming

    2015-03-01

    Ceramic coatings on friction stir welded (FSW) joints of AZ31B magnesium alloy were fabricated by microarc oxidation (MAO) method in silicate electrolyte. Microstructure, phase constituents, microhardness and electrochemical corrosion behaviors of bare and coated magnesium alloys at different zones of FSW joints for different oxidation time were investigated. The influence of microstructure at different zones on the growth of MAO coatings was analyzed. The results show that the MAO coatings on FSW joints are uniform, and they have almost the same morphology, phase constituents, hardness and corrosion resistance at base metal, stir zone and heat-affected zone. The properties of MAO coatings are independent on the microstructures of AZ31B alloy. In addition, the microstructures of magnesium alloy near the coating/alloy interface at different zones of FSW joint was not changed by microarc discharge process.

  13. Analysis of the Creep Behavior of P92 Steel Welded Joint

    NASA Astrophysics Data System (ADS)

    An, Junchao; Jing, Hongyang; Xiao, Guangchun; Zhao, Lei; Xu, Lianyong

    2011-11-01

    Different regions of heat-affected zone (HAZ) were simulated by heat treatment to investigate the mechanisms of the Type IV fracture of P92 (9Cr-2W) steel weldments. Creep deformation of simulated HAZ specimens with uniform microstructures was investigated and compared with those of the base metal (BM) and the weld metal (WM) specimens. The results show that the creep strain rate of the fine-grained HAZ (FGHAZ) is much higher than that of the BM, WM, the coarse-grained HAZ (CGHAZ), and the inter-critical HAZ (ICHAZ). According to the metallurgical investigation of stress-rupture, the FGHAZ and the ICHAZ have the most severely cavitated zones. During creep process, carbides become coarser, and form on grain boundaries again, leading to the deterioration of creep property and the decline of creep strength. In addition, the crack grows along the FGHAZ adjacent to the BM in the creep crack growth test (CCG) of HAZ.

  14. Microstructure of the interface in magnesium alloy to aluminium alloy dissimilar joints produced by friction stir welding

    Microsoft Academic Search

    S. Hirano; K. Okamoto; M. Doi; O. Kamura; M. Inagaki; Y. Aono

    2004-01-01

    Friction stir welding (FSW) is a process that was developed by the UK Welding Institute (TWI) in 1991. Because of its status as a solid-phase joining process operating at a temperature below the melting point of the materials being joined, FSW usually generates less residual stress than fusion welding, being also advantageously free from fume, porosity, and solidification cracking. The

  15. Low cycle fatigue behavior of electron beam and friction welded joints of an α-β titanium alloy

    Microsoft Academic Search

    T. Mohandas; V. K. Varma; D. Banerjee; V. V. Kutumbarao

    1996-01-01

    Fusion welds in titanium alloys, with intermediate β stabilizing additions, show poor mechanical properties due to large fusion zone grain size coupled with a brittle plate martensitic microstructure and hydrogen induced microporosity. These problems, associated with fusion welding, have been reported to be overcome by friction welding. The alloy used in this study is a Soviet composition (VT9) of the

  16. Microstructure and Toughness of Simulated Heat-Affected Zone of Laser Welded Joint for 960 MPa Grade High Strength Steel

    NASA Astrophysics Data System (ADS)

    Meng, Wei; Li, Zhuguo; Jiang, Xiaoxia; Huang, Jian; Wu, Yixiong; Katayama, Seiji

    2014-10-01

    The microstructure and toughness of coarse grain zone (CGZ) and mixed grain zone (MGZ) for laser welded 960 MPa grade high strength steel joints were investigated by thermal simulation with a Gleeble-3500 thermal simulator. The results show that microstructure of the stimulated CGZ mainly consists of uniform interweaved lath martensite, and grain growth is not severe upon increasing the cooling time ( t 8/5). Microstructure of the stimulated MGZ presents strip-like in low peak temperature, and small block martensite is formed on the grain boundary. However, in high peak temperature, the strip-like microstructure disappears and small block martensite presents net-like structure. The lath character for MGZ and CGZ is very obvious under TEM observation, and the average lath thickness of BM, MGZ, and CGZ is 100, 150 and 200 nm, respectively. The impact energy and microhardness of CGZ are higher than MGZ and reduce with increasing the cooling time. The fracture toughness deteriorating drastically for MGZ may be related with the formation of the mixture microstructure, in which the small block martensite is distributed in the shape of a network.

  17. An application of the implicit gradient method to welded structures under multiaxial fatigue loadings

    Microsoft Academic Search

    A. Cristofori; P. Livieri; R. Tovo

    2009-01-01

    This paper deals with the problem of fatigue strength assessment of welded joints subjected to multiaxial loading. Three-dimensional solid modelling and linear elastic stress analysis, by means of numerical methods, are used to investigate the local stress field at weld toes and roots, geometrically regarded as sharp notches. Starting from the stress field obtained from a linear elastic analysis and

  18. 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

  19. Low cycle fatigue behavior of electron beam and friction welded joints of an {alpha}-{beta} titanium alloy

    SciTech Connect

    Mohandas, T.; Varma, V.K.; Banerjee, D. [Defence Metallurgical Research Lab., Hyderabad (India)] [Defence Metallurgical Research Lab., Hyderabad (India); Kutumbarao, V.V. [B.H.U., Varanasi (India). Dept. of Metallurgical Engineering] [B.H.U., Varanasi (India). Dept. of Metallurgical Engineering

    1996-07-15

    Fusion welds in titanium alloys, with intermediate {beta} stabilizing additions, show poor mechanical properties due to large fusion zone grain size coupled with a brittle plate martensitic microstructure and hydrogen induced microporosity. These problems, associated with fusion welding, have been reported to be overcome by friction welding. The alloy used in this study is a Soviet composition (VT9) of the {alpha}-{beta} class with the nominal chemical composition Ti-6.5Al-3.3Mo-1.6Zr-0.3 Si (in weight percent), intended to be used as discs and blades in compressor stages of gas turbine engine where low cycle fatigue (LCF) loading is experienced. Electron beam welding of the alloy was largely unsuccessful for the reasons described above. Fatigue properties of such welds had large scatter due to the presence of microporosity. A continuous drive friction welding technique was investigated to overcome this problem These welds showed encouraging results in that microporosity, a problem in the electron beam welding, was not observed and the mechanical properties were at par or better than those of the base metal. This paper deals with the study of stress controlled LCF behavior of friction welds and electron beam welds of the {alpha}-{beta} titanium alloy at ambient temperature and the results are compared with those of base metal.

  20. Laser Beam Welding of Nitride Steel Components

    NASA Astrophysics Data System (ADS)

    Gu, Hongping; Yin, Guobin; Shulkin, Boris

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

  1. Phase Matching Mode Between Laser Pulse and TIG Arc in Hybrid Welding Process

    Microsoft Academic Search

    Liming Liu; Xinfeng Hao

    2010-01-01

    In previous work, the low-power laser\\/arc hybrid welding technique was used to weld a magnesium alloy, and high-quality weld joints were obtained. For the pulsed laser and alternating current (ac) tungsten inert gas (TIG) arc, there are two typical phase matching modes between the laser pulse and the ac TIG arc: laser pulse acting on the positive wave, during which

  2. Microstructure, local and global mechanical properties of friction stir welds in aluminium alloy 6005AT6

    Microsoft Academic Search

    A. Simar; Y. Bréchet; B. de Meester; A. Denquin; T. Pardoen

    2008-01-01

    The effect of the welding speed on the microstructure, local and overall mechanical properties of friction stir welded joints has been investigated in the aluminium alloy 6005A-T6. The fine hardening precipitation within the heat-affected zone has been characterized by differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). Post-welding heat treatments have been applied to obtain indications on the level

  3. 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.

  4. 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.

  5. A robust visual seam tracking system for robotic arc welding

    Microsoft Academic Search

    Jae Seon Kim; Young Tak Son; Hyung Suck Cho; Kwang Il Koh

    1996-01-01

    A robotic seam tracking system is developed to achieve robustness against optical noises such as arc glares, welding spatters, fume, and other unexpected brightness sources. The profile data of a weld joint to be welded are reliably extracted using two separate vision processing algorithms: the first is for joint modeling before welding starts, while the second is for joint feature

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  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. 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.

  13. Feasibility evaluations for the integration of laser butt welding of tubes in industrial pipe coil production lines

    Microsoft Academic Search

    Mauro Penasa; Enrico Colombo; Mauro Giolfo

    1994-01-01

    Due to the good performance shown by laser welded joints, to the quality and repeatability achievable by this welding technique and to its high process productivity, a feature inherent to the laser technology which, together with its high flexibility, allows different operations to be performed by a single source, consistent savings in a production line may be obtained. Therefore laser

  14. Effect of Pin Length on Hook Size and Joint Properties in Friction Stir Lap Welding of 7B04 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Wang, Min; Zhang, Huijie; Zhang, Jingbao; Zhang, Xiao; Yang, Lei

    2014-05-01

    Friction stir lap welding of 7B04 aluminum alloy was conducted in the present paper, and the effect of pin length on hook size and joint properties was investigated in detail. It is found that for each given set of process parameters, the size of hook defect on the advancing side shows an "M" type evolution trend as the pin length is increased. The affecting characteristics of pin length on joint properties are dependent on the heat input levels. When the heat input is low, the fracture strength is firstly increased to a peak value and then shows a decrease. When the heat input is relatively high, the evolution trend of fracture strength tends to exhibit a "W" type with increasing the pin length.

  15. 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

  16. Fatigue Performance of Advanced High-Strength Steels (AHSS) GMAW Joints

    SciTech Connect

    Feng, Zhili [ORNL; Sang, Yan [AET Integration, Inc; Jiang, Cindy [AET Integration, Inc; Chiang, Dr. John [Ford Motor Company; Kuo, Dr. Min [MIttal Steel

    2009-01-01

    The fatigue performance of gas metal arc welding (GMAW) joints of advanced high strength steels (AHSS) are compared and analyzed. The steel studied included a number of different grades of AHSS and baseline mild steels: DP600, DP780, DP980, M130, M220, solution annealed boron steel, fully hardened boron steels, HSLA690 and DR210 (a mild steel). Fatigue testing was conducted under a number of nominal stress ranges to obtain the S/N curves of the weld joints. A two-phase analytical model is developed to predict the fatigue performance of AHSS welds. It was found that there are appreciable differences in the fatigue S/N curves among different AHSS joints made using the same welding practices, suggesting that the local microstructure in the weld toe and root region plays non-negligible role in the fatigue performance of AHSS welds. Changes in weld parameters can influence the joint characteristics which in turn influence fatigue life of the weld joints, particularly of those of higher strength AHSS. The analytical model is capable of reasonably predicting the fatigue performance of welds made with various steel grades in this study.

  17. 49 CFR 179.400-11 - Welding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...inner tank and the outer jacket must be a fusion double welded butt joint. (b) The closure for openings and the circumferential...jacket, including head to shell joints, may be a single welded butt joint using a backing strip on the inside of the joint....

  18. 49 CFR 179.400-11 - Welding.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...inner tank and the outer jacket must be a fusion double welded butt joint. (b) The closure for openings and the circumferential...jacket, including head to shell joints, may be a single welded butt joint using a backing strip on the inside of the joint....

  19. 49 CFR 179.400-11 - Welding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...inner tank and the outer jacket must be a fusion double welded butt joint. (b) The closure for openings and the circumferential...jacket, including head to shell joints, may be a single welded butt joint using a backing strip on the inside of the joint....

  20. 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.

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

    SciTech Connect

    Asl, Y. Dadgar; Mostafa, N. B.; Panahizadeh, V. R. [Department of Mechanical Engineering, Shahid Rajaee Teacher Training University, Tehran (Iran, Islamic Republic of); Seyedkashi, S. M. H. [Department of Mechanical Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of)

    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.

  2. The effects of ultrasonic peening treatment on the ultra-long life fatigue behavior of welded joints

    Microsoft Academic Search

    Danqing Yin; Dongpo Wang; Hongyang Jing; Lixing Huo

    2010-01-01

    The conventional fatigue design codes was formulated based on the data from test stress cycles less than 1×107. Most of them could not be applied for welded structures serviced in the ultra-long life region so the new recommendations were discussed. The method of ultrasonic peening treatment (UPT) was introduced in this thesis as a post-weld treatment to improve the fatigue

  3. Comparative and Joint Analysis of Two Metagenomic Datasets from a Biogas Fermenter Obtained by 454-Pyrosequencing

    PubMed Central

    Jaenicke, Sebastian; Ander, Christina; Bekel, Thomas; Bisdorf, Regina; Dröge, Marcus; Gartemann, Karl-Heinz; Jünemann, Sebastian; Kaiser, Olaf; Krause, Lutz; Tille, Felix; Zakrzewski, Martha; Pühler, Alfred

    2011-01-01

    Biogas production from renewable resources is attracting increased attention as an alternative energy source due to the limited availability of traditional fossil fuels. Many countries are promoting the use of alternative energy sources for sustainable energy production. In this study, a metagenome from a production-scale biogas fermenter was analysed employing Roche's GS FLX Titanium technology and compared to a previous dataset obtained from the same community DNA sample that was sequenced on the GS FLX platform. Taxonomic profiling based on 16S rRNA-specific sequences and an Environmental Gene Tag (EGT) analysis employing CARMA demonstrated that both approaches benefit from the longer read lengths obtained on the Titanium platform. Results confirmed Clostridia as the most prevalent taxonomic class, whereas species of the order Methanomicrobiales are dominant among methanogenic Archaea. However, the analyses also identified additional taxa that were missed by the previous study, including members of the genera Streptococcus, Acetivibrio, Garciella, Tissierella, and Gelria, which might also play a role in the fermentation process leading to the formation of methane. Taking advantage of the CARMA feature to correlate taxonomic information of sequences with their assigned functions, it appeared that Firmicutes, followed by Bacteroidetes and Proteobacteria, dominate within the functional context of polysaccharide degradation whereas Methanomicrobiales represent the most abundant taxonomic group responsible for methane production. Clostridia is the most important class involved in the reductive CoA pathway (Wood-Ljungdahl pathway) that is characteristic for acetogenesis. Based on binning of 16S rRNA-specific sequences allocated to the dominant genus Methanoculleus, it could be shown that this genus is represented by several different species. Phylogenetic analysis of these sequences placed them in close proximity to the hydrogenotrophic methanogen Methanoculleus bourgensis. While rarefaction analyses still indicate incomplete coverage, examination of the GS FLX Titanium dataset resulted in the identification of additional genera and functional elements, providing a far more complete coverage of the community involved in anaerobic fermentative pathways leading to methane formation. PMID:21297863

  4. Controlling conditions for wet welding

    SciTech Connect

    Hill, M.

    1985-11-01

    Wet welding is finding increased use for repairing and maintaining vessel hulls around the world. Users are developing new methods and procedures to expand the technology. A wet welded joint underwater can be made as strong as one welded in a dry habitat, but at a greatly reduced cost. The design of the joint for wet welding and the procedures that need to be followed are outlined. In designing for wet welding, high tensile strength, ease of access, and over-design should be considered.

  5. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

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

  7. New explosive seam welding concepts

    NASA Technical Reports Server (NTRS)

    Bement, L. J.

    1973-01-01

    Recently developed techniques provide totally-confined linear explosive seam welding and produce scarf joint with linear explosive seam welding. Linear ribbon explosives are utilized in making narrow, continuous, airtight joints in variety of aluminum alloys, titanium, copper, brass, and stainless steel.

  8. 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.

  9. 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.

  10. 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.

  11. Measures for ensuring reliable operation of the welded joint connecting the reactor coolant circuit's header to the shell of a steam generator used at a VVER-1000 reactor-based nuclear power station

    NASA Astrophysics Data System (ADS)

    Kharchenko, S. A.; Trunov, N. B.; Korotaev, N. F.; Lyakishev, S. L.

    2011-03-01

    Problems that arose around the weld joint connecting the reactor coolant circuit's header to the steam generator shell during operation of steam generators at nuclear power stations equipped with VVER-1000 reactors are considered. Works on studying the defects occurred in the header's metal are described, and ways for preventing their development are determined.

  12. Modified Wöhler curve method, theory of critical distances and Eurocode 3: A novel engineering procedure to predict the lifetime of steel welded joints subjected to both uniaxial and multiaxial fatigue loading

    Microsoft Academic Search

    L. Susmel

    2008-01-01

    In order to propose a procedure suitable for assessing steel welded joints by post-processing simple linear-elastic finite element (FE) models, this paper summarises an attempt to formalise a novel approach based on the use of the modified Wöhler curve method (MWCM) applied along with the theory of critical distances (TCD). This engineering procedure was initially calibrated by using the standard

  13. 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:…

  14. 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.

  15. Apparatus for welding blades to rotors

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

    Using magnetic force upset welding to form T-joints between dissimilar thickness parts. This type of resistance welding is used to join compressor and turbine parts thereby reducing the weight and cost of a jet engine.

  16. Effect of welding parameters on microstructure in the stir zone of FSW joints of aluminum die casting alloy

    Microsoft Academic Search

    Y. G. Kim; H. Fujii; T. Tsumura; T. Komazaki; K. Nakata

    2006-01-01

    The effect of the welding speed and the rotation speed on the microstructure in the stir zone has been investigated by measuring the Si particle distribution in the ADC12 alloy. The stir zone has fine recrystallized grains without dendritic structures, and the eutectic Si was uniformly dispersed in the stir zone. The size of the Si particles was statistically determined

  17. Laser and shot peening effects on fatigue crack growth in friction stir welded 7075-T7351 aluminum alloy joints

    Microsoft Academic Search

    Omar Hatamleh; Jed Lyons; Royce Forman

    2007-01-01

    The influence of shot and laser peening on the fatigue crack growth behavior of friction stir welded (FSW) aluminum alloy (AA) 7075-T7351 sheets was investigated. The alterations resulting from this surface modification on the fatigue crack growth of FSW were characterized and evaluated for two different crack configurations. A systematic investigation of the various peening effects indicated a significant decrease

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

    NASA Astrophysics Data System (ADS)

    Ravikumar, S.; Rao, V. S.

    2013-10-01

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

  19. Re-weldability of neutron-irradiated stainless steels studied by multi-pass TIG welding

    NASA Astrophysics Data System (ADS)

    Nakata, K.; Oishi, M.; Koshiishi, M.; Hashimoto, T.; Anzai, H.; Saito, Y.; Kono, W.

    2002-12-01

    Weldability of neutron-irradiated stainless steel (SS) has been studied by multi-pass bead-on-plate and build-up tungsten inert gas (TIG) welding, simulating the repair-welding of reactor components. Specimens were submerged arc welding (SAW) joint of Type 304 SS containing 0.5 appm helium (1.8 appm in the SAW weld metal). Sound welding could be obtained by one- to three-pass welding on the plates at weld heat inputs less than 1 MJ/m in the irradiated 304 SS base metal. In the case of the build-up welding of a groove, no visible defects appeared in the specimen at a heat input as low as 0.4 MJ/m. However, build-up welding at a high heat input of 1 MJ/m was prone to weld cracking, owing to the formation of helium bubbles on grain boundaries of the base metal or dendrite boundaries of pre-existing SAW weld metal, in the area within 0.6 mm from the fusion line.

  20. Influence of Wood Welding Frequency on Wood Constituents Chemical Modifications

    Microsoft Academic Search

    L. Delmotte; H. R. Mansouri; P. Omrani; A. Pizzi

    2009-01-01

    Interesting chemical differences betwen weldlines obtained at 100 Hz and 150 Hz frequencies in linear vibration wood welding were observed by FT-IR and C NMR. An increase in the proportion of unoxidized phenolic groups in the lignin is observed by FT-IR and the increased joint strength observed is ascribed to the improved adhesion derived from this. The much decreased level

  1. Welding experiments of aluminium pipe by space GHTA welding in aircraft-borne simulated space environment

    Microsoft Academic Search

    Yoshikazu Suita; Masahiro Ohara; Hiroki Sogawa; Kazunori Matsushita; Shinichiro Shobako; Noboru Terajima; Yoshiyuki Tsukuda; Koichi Masubuchi; Shoji Yamauchi

    2009-01-01

    The gas hollow tungsten arc (GHTA) welding experiments on aluminum pipe were carried out in a simulated space environment using an aircraft. A vacuum chamber and welding machine for GHTA welding test were placed in the cabin of the aircraft and the 10 G gravity environment was produced by a parabolic flight of the aircraft. The square butt welding joints with

  2. Advances in solar cell welding technology

    Microsoft Academic Search

    L. G. Chidester; D. R. Lott

    1982-01-01

    In addition to developing the rigid substrate welded conventional cell panels for an earlier U.S. flight program, LMSC recently demonstrated a welded lightweight array system using both 2 x 4 and 5.9 x 5.9 cm wraparound solar cells. This weld system uses infrared sensing of weld joint temperature at the cell contact metalization interface to precisely control weld energy on

  3. A numerical simulation of the residual stresses in laser-peened friction stir-welded aluminum 2195 joints

    Microsoft Academic Search

    Kelly S. Carney; Omar Hatamleh; James Smith; Thomas Matrka; Amos Gilat; Michael Hill; Chanh Truong

    2011-01-01

    Purpose – The purpose of this paper is to present an analytical framework for predicting the residual stresses that result from the laser shock peening of a friction stir-welded 2195 aluminum alloy sample, using the finite element software LS-DYNA. Design\\/methodology\\/approach – The pressures resulting from the laser peening are directly applied in an explicit transient analysis as forces. At the

  4. Microstructure and mechanical properties of an inertia friction welded INCOLOY alloy 909–INCONEL alloy 718 joint for rotating applications

    Microsoft Academic Search

    O. Roder; J. Albrecht; G. Lütjering

    2006-01-01

    Inertia welding is a common practice to join axially symmetrical parts for aero-engine applications. The shaft for a new advanced high-pressure compressor will be produced ed by joining the high strength superalloys INCOLOY® alloy 909 (Incoloy909) and INCONEL® alloy 718 (IN718). IN718 is the work-horse nickel-iron-chromium alloy for a variety of parts for aero-engine applications due to a good combination

  5. Low cycle fatigue properties of modified 9Cr1Mo ferritic martensitic steel weld joints in sodium environment

    Microsoft Academic Search

    R. Sandhya; R. Kannan; V. Ganesan; M. Valsan; K. Bhanu Sankara Rao

    2010-01-01

    Mod.9Cr-1Mo ferritic-martensitic steel is the material chosen for the steam generator of the Prototype Fast Breeder Reactor\\u000a being built at Kalpakkam, India. The use of sodium as a heat transfer medium for Liquid Metal Fast Breeder Reactors (LMFBRs)\\u000a necessitates a comprehensive understanding of the effects of dynamic sodium on the Low Cycle Fatigue (LCF) behaviour of structural\\u000a components. Moreover welds

  6. Research on laser welding of aluminum matrix composite SiCw\\/6061

    Microsoft Academic Search

    Jitai Niu; Longxiu Pan; Muzhen Wang; Chengbin Fu; Xiaodong Meng

    2006-01-01

    Effects of laser welding parameters on strength of welded joint were studied. Mechanism of loss of joint strength was analyzed. It was pointed out that an important factor affecting joint strength is the reaction between matrix and reinforced phase. On the basis of this, the concept of critical Si activity was proposed. In appropriate welding parameters and Si activity, welded

  7. Use of DL-EPR Test to Assess Sensitization Resistance of AISI 409M Grade Ferritic Stainless Steel Joints

    NASA Astrophysics Data System (ADS)

    Lakshminarayanan, A. K.; Balasubramanian, V.

    2013-08-01

    The susceptibility of 409M grade ferritic stainless steels to sensitization due to welding was investigated. Joints were fabricated by gas tungsten arc welding, friction stir welding, laser beam welding, and electron beam welding processes. Double loop electrochemical potentiokinetic reactivation test was carried out for determining the degree of sensitization of welded joints. The experimental result reveals that, the friction stir welded joint is less prone to sensitization, when compared to the other joints.

  8. Resistance welding graphite-fiber composites

    NASA Technical Reports Server (NTRS)

    Lamoureux, R. T.

    1980-01-01

    High-strength joints are welded in seconds in carbon-reinfored thermoplastic beams. Resistance-welding electrode applies heat and pressure to joint and is spring-loaded to follow softening material to maintain contact; it also holds parts together for cooling and hardening. Both transverse and longitudinal configurations can be welded. Adhesive bonding and encapsulation are more time consuming methods and introduce additional material into joint, while ultrasonic heating can damage graphite fibers in composite.

  9. Calibration Fixture For Welding Robot

    NASA Technical Reports Server (NTRS)

    Holly, Krisztina J.

    1990-01-01

    Compact, lightweight device used in any position or orientation. Calibration fixture designed for use on robotic gas/tungsten-arc welding torch equipped with vision-based seam-tracking system. Through optics in hollow torch cylinder, video camera obtains image of weld, viewing along line of sight coaxial with welding electrode. Attaches to welding-torch cylinder in place of gas cup normally attached in use. By use of longer or shorter extension tube, fixture accommodates welding electrode of unusual length.

  10. 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.

  11. Application of YAG laser welding to gas turbine components

    NASA Astrophysics Data System (ADS)

    Tsubota, Shuho; Mega, Masahiko; Takahashi, Koji; Uemura, Yoshitaka; Hirota, Norihide; Yamaguchi, Kengo

    2003-03-01

    An investigation to apply YAG laser welding to gas turbine components was carried out. The materials of gas turbine such as Ni base alloy are difficult to weld by conventional arc welding methods because of large heat affection. But laser welding can reduce heat input compared with conventional methods and keeps the good repeatability. The welding parameter survey was carried out to satisfy the designing requirements. The YAG laser welding under appropriate conditions enables to prevent welding defects such as HAZ cracks and improves the weld joints quality and performance. Tensile test and low cycle fatigue test were carried out. Tensile strength and fatigue life of laser weld joints are same or higher than that of conventional manual TIG weld joints. The Automatic YAG laser welding system was also developed and put into practical use.

  12. Customized orbital welding meets the challenge of titanium welding

    SciTech Connect

    NONE

    1996-12-01

    Titanium has emerged as the material of choice for tubing used in surface condensers around the world in both new and retrofit configurations. A major worldwide supplier of steam surface condensers to the electric utility industry, Senior Engineering is finding an increased use of titanium tubes and tube sheets in condenser specifications. When compared to other alloys, titanium`s light weight is efficient in design, handling, transportation and installation activities. Additionally, it maintains a stable price structure. Senior Engineering implements an orbital welding process using fusion gas tungsten arc welding (GTAW) for its titanium tube-to-tube sheet welding. Orbital welding involves the use of a welding apparatus placed inside a tube or pipe to automatically and precisely weld a 360-deg joint. When welding manually, a welder stops several times during the weld due to the large amount of time and fatigue involved in achieving 360-deg welds, which results in lack of fusion. An automated orbital welding system, however, can accomplish the task as one continuous weld. This reduces process time and decreases lack of fusion. The orbital welding systems, featuring a microprocessor-based controller, an inverter-based power supply, an expandable mandrel and a customized torch shroud, reduced welding labor by 35%. The improved labor efficiency justified the addition of two more of the systems in January 1996.

  13. 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.

  14. 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.

  15. 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

  16. A New Perspective on Fatigue Performance of Advanced High- Strength Steels (AHSS) GMAW Joints

    SciTech Connect

    Feng, Zhili [ORNL; Chiang, Dr. John [Ford Motor Company; Kuo, Dr. Min [MIttal Steel; Jiang, Cindy [AET Integration, Inc; Sang, Yan [AET Integration, Inc

    2008-01-01

    Weld fatigue performance is a critical aspect for application of advanced high-strength steels (AHSS) in automotive body structures. A comparative study has been conducted to evaluate the fatigue life of AHSS welds. The material studied included seven AHSS of various strength levels - DP 600, DP 780, DP 980, M130, M220, solution annealed boron and fully hardened boron steels. Two conventional steels, HSLA 590 and DR 210, were also included for baseline comparison. Lap fillet welds were made on 2-mm nominal thick sheets by the gas metal arc welding process (GMAW). Fatigue test was conducted under a number of stress levels to obtain the S/N curves of the weld joints. It was found that, unlike in the static and impact loading conditions, the fatigue performance of AHSS is not influenced by the HAZ softening in AHSS. There are appreciable differences in the fatigue lives among different AHSS. Changes in weld parameters can influence the fatigue life of the weld joints, particularly of these of higher strength AHSS. A model is developed to predict the fatigue performance of AHSS welds. The validity of the model is benchmarked with the experimental results. This model is capable to capture the effects of weld geometry and weld microstructure and strength on the fatigue performance experimentally observed. The theoretical basis and application of the newly developed fatigue modeling methodology will be discussed.

  17. Joint Variability of Airborne Passive Microwave and Ground-based Radar Observations Obtained in the TRMM Kwajalein Experiment

    NASA Astrophysics Data System (ADS)

    Yuter, S. E.; Kingsmill, D. E.

    2007-12-01

    The Tropical Rainfall Measuring Mission (TRMM) Kwajalein Experiment (KWAJEX) held July-September 1999 in the west Pacific was designed to obtain an empirical physical characterization of precipitating convective clouds over the tropical ocean. The majority of the precipitation was from mixed-phase clouds. Coordinated data sets were obtained from aircraft and ground-based sensors including passive microwave measurements by the Advanced Microwave Precipitation Radiometer (AMPR) instrument on the NASA DC-8 aircraft and S-band volumetric radar data by the KPOL radar. The AMPR and KPOL data sets were processed to yield a set of 25,049 matching observations at ~ 2 km x 2 km horizontal spatial resolution and within 6 min. The TRMM satellite Microwave Imager (TMI) has a similar set of channels to AMPR but coarser spatial resolution (19 GHz: 35 km, 85 GHz: 7.7 km). During KWAJEX, the 0 deg C level height was nearly constant at ~ 4800 m. Hence, two potential sources of uncertainty in relating passive microwave brightness temperatures (Tbs) to surface precipitation, inhomogeneous beam filling and variations in depth of the rain layer are much smaller sources of error in the KWAJEX data set than for TMI. TRMM was originally designed to yield monthly rainfall estimates over 5 deg x 5 deg grid boxes. The use of these data to yield instantaneous rainrate products at smaller spatial scales is more sensitive to the detailed characteristics of the joint distributions of passive microwave Tbs versus rain rate. KWAJEX data sets reveal poor correlations, very wide scatter, and weak modes in these distributions. The spread of emission Tb values for a given rain-layer reflectivity (e.g., 75 K at 30 dBZ for 19 GHz) is similar or larger within convective compared to stratiform precipitation regions. This result implies that the enhancement in emission Tbs associated with partially melted ice particles can occur whether the particles are concentrated within a thin layer in stratiform regions or are more dispersed in the column in convective regions. There is little information in either ice-layer radar reflectivity or scattering (85 GHz) Tbs on the underlying quantitative surface rain rates at the spatial scale examined.

  18. CHARACTERIZATION OF DEFECTS IN ALLOY 152, 52 AND 52M WELDS

    SciTech Connect

    Bruemmer, Stephen M.; Toloczko, Mychailo B.; Olszta, Matthew J.; Seffens, Rob J.; Efsing, Pal G.

    2009-08-27

    Defect distributions have been documented by optical metallography, scanning electron microscopy and electron backscatter diffraction in alloy 152 and 52 mockups welds, alloy 52 and 52M overlay mockups and an alloy 52M inlay. Primary defects were small cracks at grain boundaries except for more extensive cracking in the dilution zone of an alloy 52 overlay on 304SS. Detailed characterizations of the dilution zone cracks were performed by analytical transmission electron microscopy identifying grain boundary titanium-nitride precipitation associated with the intergranular separations. I. INTRODUCTION Weldments continue to be a primary location of stress-corrosion cracking (SCC) in light-water reactor systems. While problems related to heat-affected-zone (HAZ) sensitization and intergranular (IG) SCC of austenitic stainless alloys in boiling-water reactors (BWRs) have been significantly reduced, SCC has now been observed in HAZs of non-sensitized materials and in dissimilar metal welds where Ni-base alloy weld metals are used. IGSCC in weld metals has been observed in both BWRs and pressurized water reactors (PWRs) with recent examples for PWR pressure vessel penetrations producing the most concern. This has led to the replacement of alloy 600/182/82 welds with higher Cr, more corrosion-resistant replacement materials (alloy 690/152/52/52M). Complicating this issue has been a known susceptibility to cracking during welding [1-7] of these weld metals. There is a critical need for an improved understanding of the weld metal metallurgy and defect formation in Ni-base alloy welds to effectively assess long-term performance. A series of macroscopic to microscopic examinations were performed on available mockup welds made with alloy 52 or alloy 152 plus selected overlay and inlay mockups. The intent was to expand our understanding of weld metal structures in simulated LWR service components with a focus on as-welded defects. Microstructural features, defect distributions, defect characteristics and weld residual strains were examined by optical metallography, scanning electron microscopy, electron backscatter diffraction and transmission electron microscopy. Industry-supplied mock-up welds were characterized including alloy 52 and 152 weldments, alloy 52M overlay and inlay welds, and an alloy 52 overlay. II. WELDMENTS II.A. Alloy 52 and 152 Weld Mockups The alloy 52 and 152 weld mockups were fabricated by MHI for the Kewaunee reactor and were obtained from the EPRI NDE Center. The mockups were U-groove welds joining two plates of 304SS as shown in Figure 1. Alloy 152 butter (heat 307380) was placed on the U-groove surface for both mockups by shielded metal arc welding (SMAW). For the alloy 152 weld mockup, the alloy 152 fill (heat 307380) was also applied using SMAW while for the alloy 52 weld mockup, the alloy 52 fill (heat NX2686JK) was applied using gas tungsten arc welding (GTAW). Welding parameters for the fill materials were substantially different with the alloy 152 SMAW having a deposition speed of 4-25 cm/min with a current of 95-145 A and the alloy 52 GTAW having a deposition speed of 4-10 cm/min with a current of 150-300 A. One prominent feature in these mockup welds is the presence of a crack starting at the 304SS butt joint at the bottom of the U-groove and extending up into the weld. It appears that the 304SS plate on either side of the butt joint acted as an anchor for the weld resulting in a stress rise across the slit that drove crack formation and extension up into the fill weld. As will be shown in the next section, the extent of the cracking around this stress riser was much greater in the MHI 52 weld mockup.

  19. Sensitivity of the stability of a waste emplacement drift to variation in assumed rock joint parameters in welded tuff

    SciTech Connect

    Christianson, M.

    1989-04-01

    This report presents the results of a numerical analysis to determine the effects of variation of rock joint parameters on stability of waste disposal rooms for vertical emplacement. Conditions and parameters used were taken from the Nevada Nuclear Waste Storage Investigation (NNWSI) Project Site Characterization Plan Conceptual Design report (MacDougall et al., 1987). Mechanical results are presented which illustrate the predicted distribution of stress, joint slip, and room deformations for times of initial excavation and after 50 years heating. 82 refs., 93 figs.

  20. Efficient Weld Seam Detection for Robotic Welding from a Single Image

    Microsoft Academic Search

    Fanhuai Shi; Lv Zhou; Tao Lin; Shanben Chen

    The weld seam recognition is a key technology in robotic welding. This paper presents an efficient algorithm of weld seam\\u000a detection for butt joint welding from a single image. The basic idea of our approach is to find a pair of weld seam edges\\u000a in the local area first. Then, starting from the two endpoints of each edge, search for