Sample records for welded joints obtained

  1. Ultrasonic Welding of Hybrid Joints

    NASA Astrophysics Data System (ADS)

    Wagner, Guntram; Balle, Frank; Eifler, Dietmar

    2012-03-01

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

  2. Plating To Reinforce Welded Joints

    NASA Technical Reports Server (NTRS)

    Otousa, J. E.

    1982-01-01

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

  3. 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.

  4. Effect of weld schedule variation on the weldability and durability of AHSS spot weld joints

    NASA Astrophysics Data System (ADS)

    Weishaupt, Eric Raymond

    Tensile strength testing and high cycle fatigue testing of advanced high strength steel spot welded shear lap joints were performed for the various weld conditions. The materials used in this study were DP 980, DP 780 and TRIP 780. The microstructure and microhardness of the shear lap joints were examined in an effort to identify the effect of microstructural changes on the strength and fatigue durability of the spot weld specimens. The occurrence of interfacial failure was recorded for the differing weld processes. Several weld schedules were examined and used to produce shear lap spot weld joints, specifically varying the squeeze force and the average current. The weld force used to produce a spot weld does not have a significant effect on the fracture mode of the specimen given the average current is constant. The average current used to produce a spot weld has a significant effect on the fracture mode of the spot weld for several squeeze forces. Interfacial failure of spot welded TRIP 780 can be mitigated using a certain range of currents when welding. This appears to come as a tradeoff for sacrificing the strength of the joint. Higher values of weld strength were obtainable; however, welds that failed with higher strengths also experienced interfacial failure. A fracture mechanics approach to estimating the high cycle fatigue life of the shear lap specimen is also proposed and represents a conservative estimate of the shear lap specimen durability.

  5. 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.

  6. 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

  7. 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).

  8. Fatigue strength of socket welded pipe joint

    SciTech Connect

    Higuchi, Makoto [Ishikawajima-Harima Heavy Industries, Yokohama (Japan). Research Inst.; Hayashi, Makoto [Hitachi Ltd. (Japan). Mechanical Research Inst.; Yamauchi, Takayoshi [Mitsubishi Heavy Industries Ltd., Takasago (Japan). Takasago Research Inst.; Iida, Kunihiro [Shibaura Inst. of Technology, Tokyo (Japan). Dept. of Mechanical Engineering; Sato, Masanobu [Japan Power Engineering and Inspection Corp., Tokyo (Japan). Welding Engineering Dept.

    1995-12-01

    Fully reversed four point bending fatigue tests were carried out on small diameter socket welded joints made of carbon steels. Experimental parameters were pipe diameter, thicknesses of pipe and socket wall, throat depth and shape of fillet welds, slip-on and diametral gaps in the socket welding, lack of penetration at the root of fillet welds, and peening of fillet welds. In most cases a fatigue crack started from the root of the fillet, but in the case of higher stress amplitude, it tended to start from the toe of fillet. The standard socket welded joint for a pipe with a 50 mm nominal diameter showed a relatively low fatigue strength of 46 MPa in stress amplitude at the 10{sup 7} cycles failure life. This value corresponds to about 1/5 of that for the smoothed base metal specimens in axial fatigue. The fatigue strength decreased with increasing pipe diameter, and increased with increasing thickness of the pipe and socket wall. The effects of throat depth and shape of fillet welds on fatigue strength were not significant. Contrary to expectation, the fatigue strength of a socket welded joint without slip-on gap is Higher than that of the joint with a normal gap. A lack of penetration at the root deleteriously reduced fatigue strength, showing 14 MPa in stress amplitude at the 10{sup 7} cycles failure life for the 50 mm diameter socket joint.

  9. Joint strength of Inconel 718 alloy and its improvement by post-weld heat treatment – joint performance and its controlling factors in friction welding of Inconel 718 alloy

    Microsoft Academic Search

    Hongjie Wang; Kenji Ikeuchi; Masatoshi Aritoshi; Makoto Takahashi; Akio Ikeda

    2009-01-01

    The influences of welding parameters on tensile properties of friction-welded joints of Inconel 718 alloy (subjected to a post-weld heat treatment (PWHT) consisting of a solution treatment at 1253 K and double ageing treatments at 993 and 893 K) have been investigated to reveal the controlling factor of the joint performance. All joints obtained were fractured near the bond interface at smaller

  10. 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.

  11. 46 CFR 56.30-5 - Welded joints.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 2011-10-01 2011-10-01 false Welded joints. 56.30-5 Section 56.30-5 Shipping...Limitations of Piping Joints § 56.30-5 Welded joints. (a) General. Welded joints may be used for materials for which...

  12. 46 CFR 56.30-5 - Welded joints.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 2010-10-01 2010-10-01 false Welded joints. 56.30-5 Section 56.30-5 Shipping...Limitations of Piping Joints § 56.30-5 Welded joints. (a) General. Welded joints may be used for materials for which...

  13. 78 FR 47486 - Joint Failure on Continuous Welded Rail Track

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-05

    ...Advisory 2013-05] Joint Failure on Continuous Welded Rail Track AGENCY: Federal Railroad...importance of reviewing current, internal continuous welded rail (CWR) plans and properly...Regulations (CFR) Section 213.118, Continuous welded rail (CWR), plan review...

  14. 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.

  15. 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

  16. 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

  17. Characterization of AZ31B wrought magnesium alloy joints welded by high power fiber laser

    SciTech Connect

    Wang Zemin; Gao Ming, E-mail: mgao@mail.hust.edu.cn; Tang Haiguo; Zeng Xiaoyan

    2011-10-15

    A 6 kW fiber laser is used to weld AZ31B wrought magnesium alloy and the characterization of welded joints are studied by the observations of bead size, microstructure and mechanical properties. The accepted joints without macro-defects can be obtained when the laser power is in the range of 2.5 to 4.0 kW. Typical hexagonal dendrites are observed in the fusion zone, whose average semi-axis length increases with increasing heat input or decreasing welding speed. The minimum ultimate tensile strength of welded joints reaches 227 MPa, 94.6% of the base metal. And when the heat input reduces to 48 J/mm or lower, the joints are fractured in the base metal, showing stronger failure strength compared to the base metal. For the joints ruptured in the weld metal, the fracture surface is characterized by a ductile-brittle mixed pattern consisting of both dimples and cleavages. Finally, the formation mechanism of pore in the welds is discussed and summarized by the pore morphologies on the fracture surface. - Highlights: {yields} Accepted joints of AZ31B Mg alloy are produced by high power fiber laser. {yields} Optimal welding parameters are summarized by experimental observations. {yields} Obvious hexagonal dendrites are observed in the fusion zone. {yields} The joints are stronger than base metal as the heat input is lower than 48 J/mm. {yields} Pore formation mechanism of welded joints is discussed and summarized.

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

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

  20. 46 CFR 154.524 - Piping joints: Welded and screwed couplings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false Piping joints: Welded and screwed couplings. 154...Systems § 154.524 Piping joints: Welded and screwed couplings. Pipe...the following: (a) A butt welded joint with complete penetration at...

  1. 46 CFR 154.524 - Piping joints: Welded and screwed couplings.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 false Piping joints: Welded and screwed couplings. 154...Systems § 154.524 Piping joints: Welded and screwed couplings. Pipe...the following: (a) A butt welded joint with complete penetration at...

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

    SciTech Connect

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

    2005-06-30

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

  3. Investigation of Fatigue Crack Propagation in Spot-Welded Joints Based on Fracture Mechanics Approach

    NASA Astrophysics Data System (ADS)

    Hassanifard, S.; Bonab, M. A. Mohtadi; Jabbari, Gh.

    2013-01-01

    In this paper, fatigue crack propagation life of resistance spot welds in tensile-shear specimens is investigated based on the calculation of stress intensity factors and J-integral using three-dimensional finite element method. For comparison, experimental works on 5083-O aluminum alloy spot-welded joints have been carried out to verify the numerical predictions of fatigue crack propagation of welded joints. A lot of analyses have been performed to obtain stress intensity factors and J-integral in tensile-shear specimens of spot-welded joints by using commercial software ANSYS. These gathered data have been formulated by using statistical software SPSS. The results of fatigue propagation life and predicted fatigue crack path revealed very good agreement with the experimental fatigue test data and photograph of cross-section of the fatigued spot-weld specimens.

  4. 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

  5. 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.

  6. Tensile and shear behavior of undermatched welded joints

    SciTech Connect

    Ferrel, M.; Dexter, R.J. [Lehigh Univ., Bethlehem, PA (United States)

    1995-12-31

    Large-scale specimens were made from HSLA-100 steel plate (690 MPa minimum yield strength) featuring groove welds with varying strength ranging from overmatched to significantly undermatched. Tensile tests with transverse groove welds demonstrated that moderately undermatched joints (15% or less) can achieve strength and ductility as good as the overmatched welds. Severely undermatched joints (> 25%) provide full strength, but only limited ductility. The constraint in the large-scale specimens, as in the actual structures, increases the load capacity of the undermatched joints. Unlike the large-scale specimens, conventional flat-strap cross-weld tension specimens cut from the same undermatched welds fail prematurely due to lack of constraint. Shear tests showed that undermatched groove welds do not affect shear strength and ductility. The test results could be reasonably simulated using small-strain elastoplastic finite-element analysis.

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

    PubMed

    Liang, Wei; Murakawa, Hidekazu

    2014-01-01

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

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

    PubMed Central

    Liang, Wei; Murakawa, Hidekazu

    2014-01-01

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

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. Characterization of 2024-T351 friction stir welding joints

    Microsoft Academic Search

    A. Ali; M. W. Brown; C. A. Rodopoulos; S. Gardiner

    2006-01-01

    Characterization of macrostructure, microstructure, hardness, precipitate distribution, residual stress, and cyclic deformation\\u000a behavior of 2024-T351 friction stir welded joints has been conducted. Inhomogeneous microparameters governing the nonuniform\\u000a residual stresses and cyclic strength are discussed. The cyclic strength of the weld microregimes is controlled by grain size\\u000a and distribution of precipitates achieved during the weld process. The comprehensive information of micro-and

  14. Resistance welding of thermoplastic composites skin\\/stringer joints

    Microsoft Academic Search

    M. Dubé; P. Hubert; A. Yousefpour; J. Denault

    2007-01-01

    An experimental investigation of resistance welding of APC-2\\/AS4 PEEK\\/carbon fibre composite using a stainless steel mesh heating element is presented. A special specimen geometry, the skin\\/stringer configuration, was used to represent a typical reinforced aerospace structural joint. The specimens consisted of a flange, representing a stringer or frame, welded onto a skin laminate. The effects of the welding parameters such

  15. 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

  16. 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

  17. 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.

  18. Effects of laser power density on static and dynamic mechanical properties of dissimilar stainless steel welded joints

    NASA Astrophysics Data System (ADS)

    Wei, Yan-Peng; Li, Mao-Hui; Yu, Gang; Wu, Xian-Qian; Huang, Chen-Guang; Duan, Zhu-Ping

    2012-10-01

    The mechanical properties of laser welded joints under impact loadings such as explosion and car crash etc. are critical for the engineering designs. The hardness, static and dynamic mechanical properties of AISI304 and AISI316 L dissimilar stainless steel welded joints by CO2 laser were experimentally studied. The dynamic strain-stress curves at the strain rate around 103 s-1 were obtained by the split Hopkinson tensile bar (SHTB). The static mechanical properties of the welded joints have little changes with the laser power density and all fracture occurs at 316 L side. However, the strain rate sensitivity has a strong dependence on laser power density. The value of strain rate factor decreases with the increase of laser power density. The welded joint which may be applied for the impact loading can be obtained by reducing the laser power density in the case of welding quality assurance.

  19. Solid-state welding of tubular joints of titanium and copper with application of electrohydropulse loading

    Microsoft Academic Search

    L. Yu. Demidenko; N. A. Onatskaya

    2008-01-01

    The possibility of welding in the hard state of tubular connections from titanium and copper with application of electrohydraulic\\u000a pulse beading and postheating in the narrow temperature-temporal range of the parameters of the process was showed experimentally.\\u000a The index of the compactness of the obtained joint weld takes on values of 79.3 ± 12.4% here, and the fastness on the

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

    NASA Astrophysics Data System (ADS)

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

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

  1. Creep Rupture Properties of Welded Joints of Heat Resistant Steels

    NASA Astrophysics Data System (ADS)

    Yamazaki, Masayoshi; Watanabe, Takashi; Hongo, Hiromichi; Tabuchi, Masaaki

    In this study, the high-temperature mechanical and creep rupture properties of Grade 91/Grade 91 (Mod. 9Cr-Mo) similar welded joints and Grade 91/Inconel 82/SUS304 dissimilar welded joints were examined. The effects of temperature and stress on the failure location in the joints were also investigated. Creep rupture tests were conducted at 823, 873, and 923 K; the applied stress ranges were 160-240, 80-160, and 40-80 MPa, respectively. The creep rupture strengths of the specimens with welded joints were lower than those of the specimens of the base metal at all temperature levels; in addition, these differences in creep strength increased with temperature. After being subjected to long-term creep rupture tests, the fracture type exhibited by the dissimilar welded joints was transformed from Types V and VII to Type IV. It was estimated that the fracture type exhibited by the dissimilar welded joints after 100,000-h rupture strength tests at 823 K and 873 K was Type IV fracture.

  2. 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

  3. 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.

  4. 46 CFR 154.524 - Piping joints: Welded and screwed couplings.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 5 2012-10-01 2012-10-01 false Piping joints: Welded and screwed couplings. 154...Construction and Equipment Cargo and Process Piping Systems § 154.524 Piping joints: Welded and screwed couplings....

  5. 46 CFR 154.524 - Piping joints: Welded and screwed couplings.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 5 2013-10-01 2013-10-01 false Piping joints: Welded and screwed couplings. 154...Construction and Equipment Cargo and Process Piping Systems § 154.524 Piping joints: Welded and screwed couplings....

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

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 5 2014-10-01 2014-10-01 false Piping joints: Welded and screwed couplings. 154...Construction and Equipment Cargo and Process Piping Systems § 154.524 Piping joints: Welded and screwed couplings....

  7. High cycle fatigue of welded joints: The TCD experience

    Microsoft Academic Search

    David Taylor; David Hoey

    2009-01-01

    This paper reports on the use of two methods for the prediction of high cycle fatigue failure in welded joints. The development of these methods – known as the crack modelling method and the theory of critical distances – is described, summarising previously published work on test specimens using steels and aluminium alloys. It is concluded that the methods work

  8. Fatigue design of welded aluminum rectangular hollow section joints

    Microsoft Academic Search

    K. a. Macdonald; P. J. Haagensen

    1999-01-01

    Fatigue design methods for welded aluminum joints are reviewed, including various approaches to fatigue life estimation currently adopted in design codes across a range of industrial applications. The applicability of these established methodologies to the fatigue design of automotive space frame structures is critically assessed. The hot spot stress method is identified as the most promising in terms of providing

  9. 18. DETAIL VIEW OF A TYPICAL WELDED JOINT BETWEEN THE ...

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

    18. DETAIL VIEW OF A TYPICAL WELDED JOINT BETWEEN THE MAIN GIRDER AND THE FLOOR BEAM, SHOWING THE ATTACHMENT OF A LATERAL BRACING MEMBER AT THIS POINT, SOUTH GIRDER, PANEL 5, LOOKING SOUTH-SOUTHWEST Ryan & Wieskamp - Benton Street Bridge, Spanning Iowa River at Benton Street, Iowa City, Johnson County, IA

  10. Upper bound of the limit load for a tensile cylinder with a soft welded (soldered) joint containing a crack

    NASA Astrophysics Data System (ADS)

    Alexandrov, S. E.

    2012-09-01

    The limit load is one of the main characteristics in estimating the performance of different structures, in particular, structures with soft welded (soldered) joints. In some cases, the difference between the yield strengths of the main material and the joint material is so great that plastic strain is localized in a thin joint. With some features of such strain distribution taken into account, an upper bound of the limit load of a tensile axisymmetric sample with a crack in a welded (soldered) joint is obtained.

  11. 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

  12. Microstructure and mechanical properties of the TIG welded joints of fusion CLAM steel

    Microsoft Academic Search

    Zhizhong Jiang; Litian Ren; Jihua Huang; Xin Ju; Huibin Wu; Qunying Huang; Yican Wu

    2010-01-01

    The CLAM steel plates were butt-welded through manual tungsten inert gas welding (TIG) process, and the following post-welding heat treatment (PWHT) at 740°C for 1h. The microstructure and mechanical properties of the welded joints were measured. The results show that both hardening and softening occur in the weld joints before PWHT, but the hardening is not removed completely in the

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  15. 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.

  16. 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.

  17. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  20. 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-fitting, a common bonding technique in metal assemblies, was used for mortise and tenon wood joints. The joints had, a wood welding technique, has been shown to yield joints of considerable strength [15-18]. This paper

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

    ERIC Educational Resources Information Center

    Espy, John

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

  2. Stochastic fatigue of welded steel joints

    SciTech Connect

    Sarkani, S. [George Washington Univ., Washington, DC (United States). Dept. of Civil, Mechanical and Environmental Engineering; Kihl, D.P.; Beach, J.E. [David Taylor Model Basin CDNSWC, Bethesda, MD (United States)

    1995-12-31

    Fatigue tests were conducted on high strength welded steel cruciform shaped specimens subjected to random amplitude loadings. Results of these tests are used to experimentally investigate the effects of loading intensity, non-normality and frequency bandwidth on the rate of fatigue damage accumulation. Test results are compared with predictions made using Rayleigh approximation and rainflow analysis in terms of cycles and times to failure. Results indicate non-normality can significantly increase the rate of fatigue damage accumulation and result in non-conservative fatigue life estimates if its effect is not accounted for. Likewise, frequency content was also found to influence the rate of fatigue damage accumulation, but to a lesser extent than non-normality. When higher frequency components were included, shorter fatigue lives were observed. Fatigue life predictions using rainflow analysis produced generally good agreement with experimental results.

  3. Effect of Post-Weld Annealing Treatment on Plastic Deformation of 2024 Friction-Stir-Welded Joints

    NASA Astrophysics Data System (ADS)

    Yuan, S. J.; Hu, Z. L.; Wang, X. S.; Liu, G.; Liu, H. J.

    2012-06-01

    Post-weld annealing treatment (PWAT) process was developed to improve the plasticity of friction-stir-welded 2024 aluminum alloy. The effect of the PWAT on plastic deformation behavior and microstructure of the joints were studied using tensile test, the ASAME® automatic strain measuring system, and the electron backscattered diffraction (EBSD). It is found that the elongation of the as-welded joint can be improved by PWAT and increases with the decreasing PWAT temperature. The maximum elongation of the PWAT joints can reach up to 160% of that of the as-welded joint, and the joints exhibit no decrease in the tensile strength. The deformation inhomogeneity of the as-welded joint is significantly improved by large plastic strain occurring in the thermo-mechanically affected zone (TMAZ) when the PWAT temperature is lower than 250°. As the PWAT temperature increases, the deformation in the weld nugget is found to be more beneficial than that in the TMAZ for improving the plasticity of the joint. The high plasticity of the joint is attributed to the presence of the fine-equiaxed grains in the weld nugget during PWAT.

  4. 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.

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

    SciTech Connect

    Wang, Ting, E-mail: fgwangting@163.com [Key Laboratory of Special Welding in Shandong Province, Harbin Institute of Technology at Weihai, Weihai, 264209 (China)] [Key Laboratory of Special Welding in Shandong Province, Harbin Institute of Technology at Weihai, Weihai, 264209 (China); Zhang, Binggang, E-mail: zhang_bg@126.com [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin, 150001 (China)] [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin, 150001 (China); Feng, Jicai, E-mail: fengjc@hit.edu.cn [Key Laboratory of Special Welding in Shandong Province, Harbin Institute of Technology at Weihai, Weihai, 264209 (China) [Key Laboratory of Special Welding in Shandong Province, Harbin Institute of Technology at Weihai, Weihai, 264209 (China); State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin, 150001 (China); Tang, Qi, E-mail: tangqi@163.com [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin, 150001 (China)] [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin, 150001 (China)

    2012-11-15

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

  6. An investigation of residual stress in welded joints

    E-print Network

    Moffat, William Hugh

    1951-01-01

    of Relaxation of Longitudinal Residual Stresses by Removal of Specimens by Sawing ~ ~ 9 3. Tensile Test Specimen Set Up 4. Stress-Strain Curve for ASTiI 1010 Steel 5. Test Specimen 6. Test Specimen Refore Vielding 16 7. Test Specimen with Joints 'i... the stresses due to depositing weld metal in a nearly continuous run along one or two edges of a mild steel plate which was entirely free from restraint at its boundaries. This procedure, by enabling the longi- tudinal residual stresses to be investigated...

  7. 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.

  8. 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.

  9. Evaluation of the Joint-Interface Properties of SCM440-S45C Steels Joined by Friction Welding

    NASA Astrophysics Data System (ADS)

    Kim, Seon-Jin; Kong, Yu-Sik; Yoon, Han-Ki; Jung, Won-Taek; Choi, Sung-Woong

    The purpose of this study is to investigate experimentally the hardness distributions and micro-structural properties of the dissimilar joints using chrome molybdenum steel (SCM440) to carbon steel (S45C) parts. The experiments were carried out using a beforehand designed and constructed experimental friction welding set-up, constructed as a continuous-drive brake type. The pilot dissimilar welding experiments under different friction pressure and friction time were carried out to obtain optimum welding parameters using visual examination and tensile tests. Vicker's hardness distributions and microstructures in the interfaces of the dissimilar joints for PWHT were also obtained and examined. The obtained results were compared with those of the previous study.

  10. 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.

  11. High-Cycle Constant Amplitude Fatigue Life Variability of Welded Round HSS Y-Joints

    E-print Network

    Foley, Christopher M.

    High-Cycle Constant Amplitude Fatigue Life Variability of Welded Round HSS Y-Joints By John L for generating accurate fatigue life predictions for these structures. Cracking found in existing sign support 2003 #12;i Preface The variability in fatigue life estimates for welded pipe joints commonly found

  12. Inertia Radial Friction Welding Joint of Large Size H90 Brass\\/D60 Steel Dissimilar Metals

    Microsoft Academic Search

    Jian Luo; Xiaoming Wang; Dejia Liu; Fei Li; Junfeng Xiang

    2012-01-01

    CT-130 Special Inertia Friction Welding Machine is used to weld a large size (156 mm diameter) of brass\\/steel by radial friction welding. Optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and Vickers microhardness measurements are used to analyze the welding joint. The results show a refined grain zone near the welding interface at the brass side, which is

  13. Inertia Radial Friction Welding Joint of Large Size H90 Brass\\/D60 Steel Dissimilar Metals

    Microsoft Academic Search

    Dejia Liu; Jian Luo; Xiaoming Wang; Fei Li; Junfeng Xiang

    2011-01-01

    CT-130 Special Inertia Friction Welding Machine is used to weld a large size (156 mm diameter) of brass\\/steel by radial friction welding. OM, SEM, EDS and Vickers microhardness measurements are used to analyze the welding joint. The results show a refined grain zone near the welding interface at the brass side, which is closely related to the smaller stacking fault energy

  14. 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).

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

    ?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.

  17. 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.

  18. 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.

  19. Fracture behavior under monotonic and low cycle loadings in carbon steel pipes and welded pipe joints with a defect

    SciTech Connect

    Miyazaki, Katsumasa; Kanno, Satoshi; Hayashi, Makoto [Hitachi Limited, Ibaraki (Japan); Ishiwata, Masayuki; Gotoh, Nobuho [Hitachi Limited, Ibaraki (Japan). Dept. of Nuclear Engineering; Miura, Naoki; Fujioka, Terutaka; Kashima, Koichi [Central Research Inst. of Electric Power Industry, Tokyo (Japan)

    1996-12-01

    To evaluate the structural integrity of power plant piping during earthquakes, fracture behavior under monotonic and low cycle loadings was examined, using 4-inch carbon steel pipes made of base metal and welded pipe joints with a circumferential defect at room and elevated temperatures in air. In the monotonic bending tests, the maximum loads increased slightly with the loading rates for base metal pipes and welded pipe joints. The maximum loads in welded pipe joints were about 10% higher than those in base metal pipes for various displacement rate. In the cyclic bending tests, the number of cycles to failure, N{sub f} was closely correlated with the ratio of the load amplitude, Pa to the maximum load, Pmax obtained in the monotonic bending tests, in spite of the difference in the maximum loads for base metal pipes and welded pipe joints. The number of loading cycles during an earthquake was assumed as about 100 cycles in design. The relationship between Pa/Pmax and the number of cycles to failure showed that the allowable load amplitude ratio was estimated as about 0.7.

  20. Penetration and Bead Shape of SUS304 Stainless Steel on Double-Side Flux Cored Arc Welding Joint

    Microsoft Academic Search

    Narin Intawong; Bovornchok Poopat

    This research was a study of joint interface penetration and bead shape by flux cored arc welding on SUS304 austenitic stainless steel that welded with double-side technique. The traditional flux cored arc welding machine was used with two welding torches, leading torch and following torch that were installed at opposite side. Torches are set for work angle by 80° and

  1. 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

  2. Fatigue failure characterisation of resistance-welded thermoplastic composites skin\\/stringer joints

    Microsoft Academic Search

    M. Dubé; P. Hubert; A. Yousefpour; J. Denault

    2009-01-01

    An experimental investigation characterising the fatigue failure mechanisms of resistance-welded thermoplastic composites skin\\/stringer joints is presented. Unidirectional (UD) and quasi-isotropic adherends were welded using stainless steel meshes as heating elements. The specimen geometry consisted of a flange laminate, representing a stringer, welded onto a skin laminate. In order to avoid current leakage to the electrically conductive adherends, a ceramic-coated heating

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

    NASA Astrophysics Data System (ADS)

    Iwamoto, Chihiro

    2013-11-01

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

  4. 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.

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

    Microsoft Academic Search

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

    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

  6. 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.

  7. 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.

  8. Influences of process parameters on tensile strength of friction stir welded cast A319 aluminium alloy joints

    Microsoft Academic Search

    M. Jayaraman; R. Sivasubramanian; V. Balasubramanian; S. Babu

    2009-01-01

    Fusion welding of cast A319 (Al-Si-Cu) alloy will lead to many problems including porosity, micro-fissuring, and hot cracking.\\u000a Friction Stir Welding (FSW) can be used to weld A319 alloy without these defects. In this investigation, an attempt has been\\u000a made to study the effect of FSW process parameters on the tensile strength of A319 alloy welded joints. Joints were made

  9. Multi-Response Optimization of Friction-Stir-Welded AA1100 Aluminum Alloy Joints

    NASA Astrophysics Data System (ADS)

    Rajakumar, S.; Balasubramanian, V.

    2012-06-01

    AA1100 aluminum alloy has gathered wide acceptance in the fabrication of light weight structures. Friction stir welding process (FSW) is an emerging solid state joining process in which the material that is being welded does not melt and recast. The process and tool parameters of FSW play a major role in deciding the joint characteristics. In this research, the relationships between the FSW parameters (rotational speed, welding speed, axial force, shoulder diameter, pin diameter, and tool hardness) and the responses (tensile strength, hardness, and corrosion rate) were established. The optimal welding conditions to maximize the tensile strength and minimize the corrosion rate were identified for AA1100 aluminum alloy and reported here.

  10. Structure and mechanical properties of the welded joints of large-diameter pipes

    NASA Astrophysics Data System (ADS)

    Khotinov, V. A.; Arabei, A. B.; Pyshmintsev, I. Yu.; Farber, V. M.

    2013-05-01

    The structure and mechanical properties of the technological welded joints of large-diameter pipes of strength class K60 produced by two companies are studied. Along with standard mechanical properties (?0.2, ?u, ?, ?), specific work of deformation a (tensile toughness) and true rupture strength S f are estimated from an analysis of the stress-strain diagrams constructed in true coordinates. The mechanical behavior is found to be different for samples cut from different zones of a welded joint (central weld, heat-affected zone, and base metal). The mutual correlation between parameters a, S f, and impact toughness KCV is considered.

  11. Radiation resistance of weld joints of type 316 stainless steel containing about 10 appm He

    NASA Astrophysics Data System (ADS)

    Fabritsiev, S. A.; Pokrovsky, A. S.

    2000-12-01

    Welding is supposed to be an important method for making joints in the pipes conducting the heat agent when replacing divertor and first wall elements. Embrittlement through helium accumulation within the ITER components repaired by welding during maintenance is one of the factors limiting the materials lifetime. To investigate this problem, a set of the 316 RF type steel specimens was saturated by He up to 50 appm at 80°C. Another part was irradiated in the SM-2 reactor up to 0.1 dpa at 80°C. Afterwards, they were subjected to e-beam welding and arc welding, respectively. A part of each specimen underwent LCF bending; another part was tested to tension. These tensile and LCF tests of the specimens showed that neutron irradiation of the weld joints leads to their embrittlement and rapidly reduces the number of cycles to failure.

  12. Evaluation of the effect of production and operating parameters on the durability and safety of assembled welded joints of valve fittings

    Microsoft Academic Search

    L. A. Efimenko; O. Yu. Elagina; G. I. Vyshegorodtseva; O. V. Konovalova

    2010-01-01

    Questions are considered of the reliability of assembled welded joints of valve fittings. It is proposed to use impact strength\\u000a as a criterion of welded metal durability for welded joints. The effect of welding heating cycle on the structure and phase\\u000a composition, and properties of metal around the joint (MAJ) of the heataffected zone (HAZ) of welded joints made from

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

    SciTech Connect

    Blashchuk, V.E.; Onoprienko, L.M.; Gorban', V.A.; Trufanov, A.A.

    1986-09-01

    The authors investigate 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 arc welding. The specimens were prepared from 22-mm thick hot-rolled plate with a composition (wt. %) of Al 3.5, Cr 0.6, Fe 0.6, Si 0.4, Mo 0.064, Zr 0.3, remainder titanium.

  14. 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.

  15. 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.

  16. 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

  18. 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.

  19. Effect of post-weld heat treatment on the mechanical properties of electron beam welded joints for CLAM steel

    NASA Astrophysics Data System (ADS)

    Wu, Qingsheng; Zheng, Shuhui; Liu, Shaojun; Li, Chunjing; Huang, Qunying

    2013-11-01

    In this paper the microstructure and mechanical properties of electron beam weld (EBW) joints for China low activation martensitic (CLAM) steel, which underwent a series of different post weld heat treatments (PWHTs) were studied. The aim of the study was to identify suitable PWHTs that give a good balance between strength and toughness of the EBW joints. The microstructural analyses were performed by means of optical microscope (OM) and scanning electron microscope (SEM). The mechanical properties were determined via tensile tests and Charpy impact tests. The results showed that the tensile strength of the as-weld joint (i.e. without any PWHT) were close to that of the base metal, but the impact toughness was only 13% of that of the base metal due to the existence of a delta-ferrite microstructure. To achieve a significant improvement in toughness a PWHT needs to be performed. If a one-step PWHT is applied tempering at 760 °C for 2 h gives EBW joints with high strength at a still acceptable toughness level. If a two-step PWHT is applied, a process involving quenching at 980 °C for 0.5 h followed by tempering at 740 °C or 760 °C for 2 h gives EBW joints with high strength and toughness properties. Whenever possible a two-step PWHT should be applied in favor of a one-step process, because of higher resulting strength and toughness properties.

  20. Effects of weld defects at root on rotating bending fatigue strength of small diameter socket welded pipe joints

    SciTech Connect

    Higuchi, Makoto; Nakagawa, Akira [Ishikawajima-Harima Heavy Industries, Yokohama (Japan). Production Engineering Center; Chujo, Noriyuki [Toshiba Corp., Yokohama (Japan). Nuclear Energy Div.; Iida, Kunihiro [Shibaura Inst. of Tech., Tokyo (Japan). Dept. of Mechanical Engineering; Matsuda, Fukuhisa [Osaka Univ. (Japan). Welding Research Inst.; Sato, Masanobu [JAPEIC, Tokyo (Japan). Welding Engineering Dept.

    1996-12-01

    Rotating bending fatigue tests were conducted on socket welded joints of a nominal diameter 20 mm, and effects of root defect and other various factors, including post-weld heat treatment (PWHT), pipe wall thickness, and socket wall thickness, were investigated. The socket joints exhibited, in the rotating bending fatigue mode, fatigue strengths that were markedly lower than the same 20 mm diameter joints in four-point bending fatigue. Also, where the latter specimens failed always at the toe, root-failures occurred in rotating bending fatigue. When PWHT`d, however, the fatigue strength showed a remarkable improvement, while the failure site reverted to toe. Thicker pipe walls and socket walls gave rise to higher fatigue strength. A formula relating the size of root defects to the fatigue strength reduction has been proposed.

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

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  3. Dual beam Nd:YAG laser welding: influence of lubricants to lap joint welding of steel sheets

    NASA Astrophysics Data System (ADS)

    Geiger, M.; Merklein, M.; Otto, A.; Blankl, A.

    2007-05-01

    Laser welding is applied in large-volume production since the late eighties and has revolutionized the possibilities of designing and engineering products. Nevertheless, problems appear during application because the operational conditions in industrial environments fluctuate and can influence the welding process negatively. Contaminations, like lubricants and organic solids, are an example of changing conditions in laser beam welding. If a lap joint is welded, these materials have to be removed from the sheets, otherwise pores and surface failures may appear due to keyhole instabilities induced by uncontrolled outgassing. One possibility for solving this problem is the use of two separate laser beams. For producing these two beams several systems are available for all different kind of lasers. A bifocal optic is such a solution for an Nd:YAG laser. By using this system, the laser beam is divided after collimation with a prism. Afterwards the two beams are focussed with a lens to the surface of the sheet and two single spots are produced. If the distance between the two spots is low, one common, elliptical keyhole is created. With this system two different welding strategies are possible. The spots can be oriented parallel or normal to the feed direction. For stabilizing the laser welding of contaminated steel sheets the parallel arrangement is better, because the amount of contamination is nearly the same as in single spot welding but the total volume of the keyhole is greater and so pressure variations due to uncontrolled evaporation of contaminations are lower. In order to prove this theory and to determine the exact effects some investigations were made at the Chair of Manufacturing Technology of the University of Erlangen-Nuremberg. A 4 kW Nd:YAG laser with a beam parameter product of 25 mm*mrad and a focal distance of 200 mm was used to weld two 1 mm DC04 steel sheets together with a lap joint. Between the sheets a deep drawing lubricant, Castrol FST 6, was used to simulate the contaminations. The sheets were welded with mono- and bifocal optic, whereas with bifocal the power distribution between the two beams was varied. After welding, the seams were qualified by analyzing surface defects and mechanical properties. The results of the investigations show that the adoption of a bifocal optic can increase the stability of the welding process. The distribution between the two single spots has an essential influence on the welding result. In order to get a higher penetration and failure free seams, a 30 % to 70 % distribution between the two spots is better. Furthermore the blade angle has another slight impact on the welding result. For monofocus and bifocus a towing angle between the sheets and the beam produces better welding results. Considering these results it can be resumed that the application of a bifocal optic is a possibility to increase the quality and the stability of lap joint welding but the parameter settings for good results can only be varied in a tight tolerance zone.

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

    NASA Astrophysics Data System (ADS)

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

    2005-02-01

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

  5. 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.

  6. 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

  7. Effect of Welding Current and Time on the Microstructure, Mechanical Characterizations, and Fracture Studies of Resistance Spot Welding Joints of AISI 316L Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Kianersi, Danial; Mostafaei, Amir; Mohammadi, Javad

    2014-09-01

    This article aims at investigating the effect of welding parameters, namely, welding current and welding time, on resistance spot welding (RSW) of the AISI 316L austenitic stainless steel sheets. The influence of welding current and welding time on the weld properties including the weld nugget diameter or fusion zone, tensile-shear load-bearing capacity of welded materials, failure modes, energy absorption, and microstructure of welded nuggets was precisely considered. Microstructural studies and mechanical properties showed that the region between interfacial to pullout mode transition and expulsion limit is defined as the optimum welding condition. Electron microscopic studies indicated different types of delta ferrite in welded nuggets including skeletal, acicular, and lathy delta ferrite morphologies as a result of nonequilibrium phases, which can be attributed to a fast cooling rate in the RSW process. These morphologies were explained based on Shaeffler, WRC-1992, and pseudo-binary phase diagrams. The optimum microstructure and mechanical properties were achieved with 8-kA welding current and 4-cycle welding time in which maximum tensile-shear load-bearing capacity or peak load of the welded materials was obtained at 8070 N, and the failure mode took place as button pullout with tearing from the base metal. Finally, fracture surface studies indicated that elongated dimples appeared on the surface as a result of ductile fracture in the sample welded in the optimum welding condition.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  10. Prediction of welding distortions and residual stresses in a pipe flange joint using the finite element technique

    Microsoft Academic Search

    M. Abid; M. Siddique; R. A. Mufti

    2005-01-01

    This paper presents a comparative study of three- and two-dimensional axisymmetric finite element (FE) analyses of a welded pipe–flange joint for residual stresses and deformations in order to identify their merits or demerits. Sequentially coupled thermal stress analysis is performed to simulate single pass metal inert gas welding. Butt weld geometry with a single ‘V’ for a 100 mm nominal

  11. Residual Stress on Ti6Al4V Hybrid and Laser Welded Joints

    Microsoft Academic Search

    C. Casavola; C. Pappalettere; F. Tursi

    \\u000a Ti6Al4V alloy combines mechanical strength, deformability, excellent fatigue and corrosion resistance and high strength to\\u000a weight ratio. Furthermore, the mechanical behavior remains excellent at high temperature. Such characteristics make this material\\u000a attractive for numerous applications (structural, aerospace and naval) because of recent improvements in welding techniques\\u000a (laser, hybrid laser\\/MIG) that allow realizing high quality titanium welded joints. However some problems

  12. 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.

  13. Sensitization resistance of friction stir welded AISI 409 M grade ferritic stainless steel joints

    Microsoft Academic Search

    A. K. Lakshminarayanan; V. Balasubramanian

    Friction stir welded low chromium AISI 409 M ferritic stainless steel was investigated for susceptibility to intergranular\\u000a corrosion by oxalic and double-loop electrochemical potentiodynamic reactivation tests, and the degree of sensitization were\\u000a evaluated by the ratio of the reactivating and activating currents. Stir zone of friction stir welded joint exhibited smaller\\u000a degree of sensitization compared to the base metal and it

  14. 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.

  15. 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.

  16. Effects of joint configuration for the arc welding of cast Ti6Al4V alloy rods in argon

    Microsoft Academic Search

    James C. Taylor; Steven O. Hondrum; Arun Prasad; Craig A. Brodersen

    1998-01-01

    Statement of problem. Titanium and its alloys are more commonly used in prosthodontics and welding has become the most common modality for their joining. Studies on the welding of titanium and its alloys have not quantified this value, though its importance has been suggested.Purpose. This study compared the strength and properties of the joint achieved at various butt joint gaps

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

    NASA Astrophysics Data System (ADS)

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

    2008-04-01

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

  18. 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.

  19. 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.

  20. 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.

  1. Influence of post-weld heat treatment (PWHT) on the structure and properties of welded joints of chromium–nickel stainless steel with soft martensite

    Microsoft Academic Search

    Edmund Tasak; Aneta Ziewiec; Barbara Wasilewska; Jaros?aw Walczyk

    2011-01-01

    This paper reviews the results of investigations on how post-weld heat treatment (PWHT) influences the hardness and microstructures of welded joints in stainless steel X3Cr-NiMo 13-4. It is known that welding leads to high segregation of components in the solidification process, which has an influence on phase transitions in PWHT. The investigated steel has a very narrow PWHT range, about

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

    USGS Publications Warehouse

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

    2011-01-01

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

  3. Microstructures forming in friction welding of Inconel 718 alloy – joint performance and its controlling factors in friction welding of Inconel 718 alloy

    Microsoft Academic Search

    Hongjie Wang; Kenji Ikeuchi; Masatoshi Aritoshi; Makoto Takahashi; Akio Ikeda

    2009-01-01

    Microstructures forming in the friction welding of Inconel 718 alloy have been investigated in order to understand the phenomena occurring during the welding process and to determine the factor controlling the joint performance from a metallographic point of view. In the interfacial zone, liquation microstructures characterized by a eutectic structure consisting of ? and Laves phases, and Nb-rich microstructures along

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

    PubMed Central

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

    2013-01-01

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

  5. 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.

  6. A comparative study of the mechanical properties of 6061-T6 GMA welds obtained by the indirect electric arc (IEA) and the modified indirect electric arc (MIEA)

    Microsoft Academic Search

    R. R. Ambriz; G. Barrera; R. García; V. H. López

    2009-01-01

    Plates of a 6061-T6 aluminium alloy with 12.7mm in thickness were welded with the gas metal arc welding process (GMAW) using three different joint designs; a single V groove butt joint, the indirect electric arc (IEA) joint and the modified indirect electric arc joint (MIEA). The later is a modification of the IEA joint which requires preheating of the plates

  7. Impact Tensile Properties of YAG Laser Welded Butt Joints Made by Different Steel Sheets for Vehicles

    NASA Astrophysics Data System (ADS)

    Takahashi, Y.; Daimaruya, M.; Kobayashi, H.; Tsuda, H.; Fujiki, H.

    The tensile properties of YAG laser welded butt joints using different high strength steel sheets with a tensile strength of 270 MPa, 590 MPa and 980 MPa (denoted HR270, HR590 and HR980, respectively) were investigated at static and dynamic rates, together with the three kinds of laser welded joints made by the same steel sheets. The impact tensile tests were performed by using the vertical type of split Hopkinson tension bar apparatus, while the static tensile tests were carried out using a universal testing machine INSTRON5586. The impact tensile strengths were significantly increased in comparison with the static ones due to the effect of strain rate, which might be the contribution of the part of HR270 base metal. And in both of static and impact tests, the fracture strains of HR270-HR590 joint, HR270-HR980 joint and HR590-HR980 joint were about one half of the fracture strains observed in the same steel welded joints of HR270-HR270, HR270-HR270 and HR590-HR590, respectively.

  8. 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.

  9. 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.

  10. Corrosion susceptibility of peened friction stir welded 7075 aluminum alloy joints

    Microsoft Academic Search

    Omar Hatamleh; Preet M. Singh; Hamid Garmestani

    2009-01-01

    Effects of surface treatment techniques like laser and shot peening on stress corrosion cracking (SCC) susceptibility of friction stir welded (FSW) 7075 aluminum alloy joints were investigated. This study had two parts; the first part investigated the peening effects on stress corrosion cracking susceptibility in FSW samples by slow strain rate testing in a 3.5% NaCl solution. The second part

  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. From the Practice of Non-destructive Examinations at Steel Welded Joints in Civil Constructions

    Microsoft Academic Search

    Emil V. Nastase; Mihaela Bucurenciu

    The use of steel in civil constructions has many advanta ges of which I mention the fact that the weight of the construction is more reduced which leads to smaller strains on foundations and gives a better earthquake performance. . The welded joints used in civil constructions require, at the same time, to take some measures specific to the new

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

    NASA Technical Reports Server (NTRS)

    Mc Daniel, G. E.

    1971-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Emil, N.

    1974-01-01

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

  16. Failure of weld joints between carbon steel pipe and 304 stainless steel elbows

    Microsoft Academic Search

    Anwar Ul-Hamid; Hani M. Tawancy; Nureddin M. Abbas

    2005-01-01

    A number of weld joints between carbon steel (CS) pipe and type 304 stainless steel (SS) elbows constituting a gas piping system of a petrochemical unit developed cracks after a relatively short period of usage, resulting in leakage. The gas flowing through the pipe, was hydrogen rich at a temperature of 45 °C and a pressure of 16 kg\\/cm2. Light

  17. EXECUTIVE SUMMARY Type IV Cracking in Modified 9Cr1Mo Steel Weld Joint

    Microsoft Academic Search

    The steam generator of the Prototype Fast Breeder (PFBR) is being fabricated out of modified 9Cr-1Mo steel. Type IV cracking in the heat affected zone (HAZ) of weld joint limits the life of the component. Detailed investigations have been carried out to understand the cracking so as to mitigate or minimize the problem. Creep tests performed on the steel and

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  19. A heat-transfer and fluid-flow-based model to obtain a specific weld geometry using various combinations of welding variables

    NASA Astrophysics Data System (ADS)

    Mishra, S.; DebRoy, T.

    2005-08-01

    Numerical heat transfer and fluid flow models have provided significant insight into welding processes and welded materials that could not have been achieved otherwise. However, the use of these models has been limited by two major problems. First, the model predictions do not always agree with the experimental results because some input parameters such as the arc efficiency cannot be accurately prescribed. Second, and more important, these models cannot determine multiple pathways or sets of welding variables that can lead to a particular weld attribute such as the weld pool geometry, which is defined by an equilibrium temperature surface. Here we show that the computational heat transfer and fluid flow models of fusion welding can overcome the aforementioned difficulties by combining with a genetic algorithm. The reliability of the convective heat transfer model can be significantly improved by optimizing the values of the uncertain input parameters from a limited volume of the experimental data. Furthermore, the procedure can calculate multiple sets of welding variables, each leading to the same weld geometry. These multiple paths were obtained via a global search using a genetic algorithm within the phenomenological framework of the equations of conservation of mass, momentum, and energy. This computational procedure was applied to the gas tungsten arc welding of Ti-6Al-4V alloy to calculate various sets of welding variables to achieve a specified weld geometry. The calculated sets of welding parameters showed wide variations of values. However, each set of welding parameters resulted in a specified geometry showing the effectiveness of the computational procedure.

  20. An assessment of creep deformation and fracture behavior of 2.25Cr1Mo similar and dissimilar weld joints

    Microsoft Academic Search

    K. Laha; K. S. Chandravathi; K. Bhanu Sankara Rao; S. L. Mannan; D. H. Sastry

    2001-01-01

    The evaluation of the creep deformation and fracture behavior of a 2.25Cr-1Mo steel base metal, a 2.25Cr-1Mo\\/2.25Cr-1Mo similar\\u000a weld joint, and a 2.25Cr-1Mo\\/Alloy 800 dissimilar weld joint at 823 K over a stress range of 90 to 250 MPa has been carried\\u000a out. The specimens for creep testing were taken from single-V weld pads fabricated by a shielded metal arc-welding

  1. 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

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

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

  4. 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.

  5. 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)

  6. Development of phased array ultrasonic testing in lieu of radiography for testing complete joint penetration (CJP) welds

    NASA Astrophysics Data System (ADS)

    Haldipur, P.; Boone, Shane D.

    2014-04-01

    The past decade has seen new, emerging innovation of Ultrasonic Testing (UT). Specifically, multiple manufacturers have produced Phased Array Ultrasonic Testing (PAUT) systems. The PAUT systems embed a matrix of multiple (some up to 128) single transducers into one probe used for scanning elastic materials. Simultaneously exciting multiple transducers offers distinct advantages; depending on the sequencing of transducer excitation, the ultrasonic beam could be steered within the material and multiple beams help develop extra dimensional data to assist with visualization of possible flaws including the discontinuity size, shape and location. Unfortunately, there has not been broad acceptance of PAUT in the bridge fabrication industry because it is currently not a recognized inspection technology in AWS D1.5. One situation in which the technology would excel would be inspection of Complete Joint Penetration (CJP) butt welds. Currently, AWS D1.5 required CJP welds subjected to tensile or reversal stresses only be inspected by Radiographic Testing (RT). However, discontinuities normally seen by RT can also be seen with PAUT. Until specification language is adopted into D1.5, there will continue to be hesitancy to use PAUT for the inspection of CJP butt welds. Developmental work must first be performed to develop the acceptance criteria and the specification language. The developmental work from the inspections carried out on butt-weld specimens and transition butt-weld specimens are presented in this paper. Specific scan plans were developed using the ES-Beam simulation software for each of the test specimens. In depth analysis of PAUT data obtained to determine exact location and sizing information of the defects was performed. The results also present the comparison of results from PAUT to those obtained using conventional UT and radiography.

  7. 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.

  8. Welding.

    ERIC Educational Resources Information Center

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

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

  9. Stress and strain concentration factors of welded multiplanar joints between square hollow sections

    NASA Astrophysics Data System (ADS)

    Panjehshahi, E.

    The results of an experimental and numerical investigation on the fatigue behavior of uniplanar and multiplanar joints made of square hollow sections are presented in this work. This work has been carried out within the framework of the research program DCT80-1457 sponsored by the Netherlands Technical Foundation (STW). After calibration of the numerical models of the joints with the experimental results, a numerical investigation for the joint parameters for the determination of stress concentration factors (SCF's) and strain concentration factors (SNCF's) was conducted. The software 'HOTSHS' is developed which uses the data base of this parameter study to calculate the hot spot stresses at the weld toes in the various joint types investigated for a given load combination, within the range of the parameters studied. The aim of this research program is to provide stress concentration factors for the fatigue design of uniplanar and multiplanar joints in square hollow sections.

  10. 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 variations in joint geome- try on the mechanical properties of the weld. Second, the attitudes of several persons, representative of different phases of the pipeline welding field, as to possible commercial applications of this process. Soint geometries... different phases of the pipeline welding field were asked to comment on possible commercial applications of' this process. While differing in some specific comments, the interviewees all concurred that more detailed research would have to be carried out...

  11. 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.

  12. 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.

  13. 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.

    2015-01-01

    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.

  14. Microstructure and mechanical properties of laser welded dissimilar DP600\\/DP980 dual-phase steel joints

    Microsoft Academic Search

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

    2011-01-01

    The use of dual phase (DP) steels in the automobile industry unavoidably involves welding and dynamic loading. The aim of this investigation was to evaluate the microstructural change and mechanical properties of laser welded dissimilar DP600\\/DP980 steel joints. The dissimilar joints showed a significant microstructural change from nearly full martensite in the fusion zone (FZ) to the unchanged ferrite–martensite dual-phase

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

    PubMed Central

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

    2015-01-01

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

  16. Evaluation of fatigue properties of 316FR stainless steel welded joints at elevated temperature

    SciTech Connect

    Kaguchi, Hitoshi; Koto, Hiroyuki [Mitsubishi Heavy Industries, Ltd., Kobe (Japan); Fujioka, Terutaka [Japan Atomic Power Co., Tokyo (Japan); Taguchi, Kosei [Toshiba Corp., Yokohama (Japan); Sukekawa, Masayuki [Hitachi Ltd. (Japan)

    1996-12-01

    316FR is an improved version of type 316 stainless steel for elevated temperature use with lower carbon content than conventional type 316 stainless steel. Fatigue properties of GTAW joints of 316FR stainless steel have been investigated. Heat affected zone (HAZ) of 316FR becomes harder than base metal. A method based on the stress-strain relationship of three elements, which are base metal, HAZ and weld portions, has been proposed and applied to the evaluations of fatigue tests. The tri-metal analysis model gives good agreements between experimental results and predicted fatigue lives of the 316FR welded joints. This material is to be used in the DFBR reactor in Japan.

  17. 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.

  18. Electron-microscopic examination of the transition zone of aluminum-tantalum bimetallic joints (explosion welding)

    NASA Astrophysics Data System (ADS)

    Volkova, A. Yu.; Greenberg, B. A.; Ivanov, M. A.; Elkina, O. A.; Inozemtsev, A. V.; Plotnikov, A. V.; Patselov, A. M.; Kozhevnikov, V. E.

    2014-04-01

    A study of the structure of an aluminum-tantalum joint and a comparison of this structure with the structures of iron-silver and copper-tantalum joints have revealed the following processes of the interpenetration of the materials that occur during explosion welding: the formation of protrusions, the injection of particles of one material into the other, and the formation of zones of local melting. Regardless of the mutual solubility of the metals being welded, two types of fragmentation occur, i.e., (1) a granulating fragmentation (GF), which includes the formation, explosion-governed (EG) dispersion, and partial consolidation of particles, and (2) the fragmentation that is usually observed during severe plastic deformation. It is important that this traditional fragmentation is not accompanied by the formation and EG dispersion of particles. This feature allows one to easily distinguish these types of fragmentation (traditional and GF fragmentation).

  19. 49 CFR 179.300-9 - Welding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...Welding. (a) Longitudinal joints must be fusion welded. Head-to-shell joints must...subchapter). (b) Fusion-welded joints must be in compliance with...radiotaped. (c) Forge-welded joints shall be thoroughly...

  20. 49 CFR 179.300-9 - Welding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Welding. (a) Longitudinal joints must be fusion welded. Head-to-shell joints must...subchapter). (b) Fusion-welded joints must be in compliance with...radiotaped. (c) Forge-welded joints shall be thoroughly...

  1. 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.

  2. Creep modeling of welded joints using the theta projection concept and finite element analysis

    SciTech Connect

    Law, M.; Payten, W.; Snowden, K.

    2000-02-01

    Modeling of welded joints under creep conditions with element analysis was undertaken using the theta projection method. The results were compared to modeling based on a simple Norton law. Theta projection data extends the accuracy and predictive capability of finite element modeling of critical structures operating at high temperature and pressure. In some cases analyzed, it was found that the results diverged from those gained using a Norton law creep model.

  3. Effects of minor Sc on microstructure and mechanical properties of Al-Zn-Mg-Zr alloy welded joint

    Microsoft Academic Search

    XIAO Jing; YIN Zhi-min; LEI Xue-feng; JIANG Feng; NIE Bo; HE Zhen-bo

    Two kinds of Al-6.0Zn-2.0Mg-0.12Zr and Al-6.0Zn-2.0Mg-0.2Sc-0.12Zr alloy plates were prepared by ingot-metallurgy. The alloy plates with 3 mm thickness were welded by argon shield welding method, and the mechanical properties and microstructures of the two welded joints filled with Al-Mg-Sc welding wire were studied comparatively. The results show that firstly, minor Sc can raise the mechanical properties of the Al-Zn-Mg-Zr

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

    NASA Astrophysics Data System (ADS)

    Harooni, Masoud; Carlson, Blair; Kovacevic, Radovan

    2014-03-01

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

  5. Prediction of Weld Bead Profile Using Neural Networks

    Microsoft Academic Search

    Vidyut Dey; Dilip Kumar Pratihar; G. L. Datta

    2008-01-01

    In fusion welding process, a monolithic structure is obtained at the weldment between the two pieces to be joined. This monolithic structure called the welded zone has got different shapes, which depend upon the type of welding process and its parameters. The strength of the welded structure depends upon the extent to which the metal penetrates between the joint and

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

    NASA Astrophysics Data System (ADS)

    Harooni, Masoud

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

  7. Study on weld bead surface profile and angular distortion in 6 mm thick butt weld joints of SS304 using fiber laser

    NASA Astrophysics Data System (ADS)

    Bhargava, P.; Paul, C. P.; Mundra, G.; Premsingh, C. H.; Mishra, S. K.; Nagpure, D.; Kumar, Atul; Kukreja, L. M.

    2014-02-01

    We deployed a 2 kW continuous wave fiber laser integrated with the 5-axis workstation to understand the effect of various processing parameters (laser power, welding speed, beam spot size and chamfer at welded edges) on depth of penetration, angular distortion and welded bead surface profile during autogenous laser welding of 6 mm thick austenitic stainless steel type 304 plates. Full penetration with reduced weld bead surface undulation (<100 µm) and least angular distortion (<0.8°) was achieved for butt joints having chamfered edges of 0.8 mm. The microscopic studies revealed grossly defect-free fusion zone with a few porosities at isolated locations. The microstructure at the fusion zone was largely austenitic with few ferrites and the direction of growth was epitaxial towards the fusion line. The measured values of microhardness at base material and fusion zone were 208±4 HV0.1 and 235±10 HV0.1 respectively. The tensile testing of laser welded samples indicated the ultimate strength >605 MPa and these samples could be bent for an angle >170° without noticeable crack during bend test. The study opened the avenues for the deployment of fiber laser welding technology for applications demanding critical values of surface weld bead profile and distortion.

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

    SciTech Connect

    Tanosaki, M.; Yoshikawa, K.; Arakawa, T. [Ishikawajima-Harima Heavy Industries Co., Ltd., Yokohama (Japan)

    1995-08-01

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

  9. Electrical, Corrosion, and Mechanical Properties of Aluminum-Copper Joints Produced by Explosive Welding

    NASA Astrophysics Data System (ADS)

    Acarer, Mustafa

    2012-11-01

    This study investigates the microstructure, electrical, corrosion, and mechanical properties of plate-shaped aluminum-copper couple produced using the explosive welding method. Mechanical tests, including hardness, tensile, tensile-shear, and impact test, concluded that the Al-Cu bimetal had an acceptable joint resistance. In this study, local intermetallic regions formed on the interface of the joint of the aluminum-copper bimetal, produced using the explosive welding technique. However, the formed intermetallic regions had no significant effect on the mechanical properties of the joint, except for increasing its hardness. According to electrical conductivity tests, the Al-Cu bimetal had an average electrical conductivity in comparison to the electrical conductivity of aluminum and copper, which were the original materials forming the joint. According to the results of electro-chemical corrosion test, during which galvanic corrosion formed, the Al side of the Al-Cu bimetal was more anodic due to its high electronegativity; as a result, it was exposed to more corrosion in comparison to the copper side.

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

    SciTech Connect

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

    1992-01-01

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

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

    SciTech Connect

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

    1992-12-01

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

  12. 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.

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

    SciTech Connect

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

    2011-09-14

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

  14. Microstructure and Softening of Laser-Welded 960 MPa Grade High Strength Steel Joints

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    The microstructural evolution of laser-welded 960 MPa grade high strength steel joints and its effect on softening behavior of heat affected zone (HAZ) were investigated in this paper. The results show that microstructure of HAZ and fusion zone (FZ) is composed of lath martensite and bainitic ferrite. The microstructure of mixed grained zone presents strip-like characteristics and small block martensite distributes along the grain boundary. The grain size near the fusion line is about 25 ?m, and the grain size in the fine grain zone is less than 5 ?m. Microhardness of HAZ and FZ is lower than base metal. The soft zone locates in transitional region between tempering zone and mixed grained zone due to the interaction of the martensite tempering and the recovery and recrystallization of the rolled microstructure. Microhardness of soft zone is 310 HV and drops 18% compared to base material. Welding heat input has a remarkable effect on the width of soft zone and microhardness. The tensile properties of weld joints are closely related to the softening behavior of HAZ.

  15. 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

    2015-02-01

    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.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

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

    SciTech Connect

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

    2011-04-25

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

  19. 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.

  20. Welding.

    ERIC Educational Resources Information Center

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

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

  1. [Clinical study to obtain true view of the glenohumeral joint on scapula-45].

    PubMed

    Fujisawa, Hironobu; Kato, Kyoichi; Nishimura, Hiroki; Nishinaka, Naoya; Mihara, Kenichi; Tsutsui, Hiroaki; Nakazawa, Yasuo

    2012-01-01

    Scapula-45 is an original roentogenographical technique to clarify objectively the function of the rotator cuff and scapulothoracic joint. This examination enables assessment of the function of the rotator cuff and scapulothoracic joint utilizing the radiographs of the glenohumeral joint. However, in the former technique, it was difficult for the technician to properly align the patient for the view of the true glenohumeral joint because of the individual postural difference of the patients, such as kyphosis. In the present study, we reported a new technique with the use of the acromion, coracoid process, and inferior angle of the scapula as a landmark to obtain the consistent radiographs of the glenohumeral joint. PMID:22516591

  2. 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.

  3. Azides and nitrides in joints welded by laser using N2 as covering gas

    NASA Astrophysics Data System (ADS)

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

    1993-05-01

    A large amount of metals and alloys are successfully penetration welded by pulsed or cw laser. The laser welding process requires a gas flow (covering gas) to ensure adequate protection of the melt against atmospheric oxidation. The gas can be supplied in a variety of ways but in many cases the coaxial gas-laser geometry is used. This work is concerned with technological and structural investigations (using SEM and A.E.S. microanalysis) aimed at identifying any particular differences in the welds obtained using N2 instead of He as the covering gas. The investigations conducted on INCONEL 600 and stainless steel appear to provide conclusive evidence that N2 may be readily used as an alternative to He. Very recent works have studied some peculiarities (blanketing, transmission, and process efficiency) of N2 as a covering gas, when used in 2 kW CO2 laser welding. The influence of the covering gas in welding two stainless steels (AISI 304 and 430) and of a nickel alloy (INCONEL 600) using a 2 kW CO2 laser is examined.

  4. 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.

  5. 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.

  6. 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.

    2015-02-01

    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.

  7. 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.

  8. 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.

  9. Evaluation of creep damage in a welded joint of modified 9Cr-1Mo steel

    NASA Astrophysics Data System (ADS)

    Li, Yongkui; Monma, Yoshio; Hongo, Hiromichi; Tabuchi, Masaaki

    2010-10-01

    This paper aims to evaluate the creep damage of modified 9Cr-1Mo steel under 600 °C operating conditions, using constitutive equations based on the continuum damage mechanics. The accumulation of voids over a long period is believed to contribute to the formation of Type IV cracking, which in turn leads eventually to the failure of weldment under conditions of higher temperatures and lower stresses. Specimens of base metal, a simulated fine-grained heat affected zone, and a thin (thick) welded joint were kept under stress from 80 to 160 MPa at 600 °C. During the creep tests of thick plate welded joint specimens, the application of stress was suspended several times, and the creep damage as indicated by the void distribution was examined quantitatively using a laser microscope. The combined effect of the equivalent creep strain and the stress triaxial factor was considered and introduced into the constitutive equations with the aid of a finite element method. The logarithms of m and 1/? in the continuum damage mechanics equations were determined to have a linear correlation with the ratio of the applied stress to the yield stress for homogeneous materials. In this way, the damage distribution and evolution in the fine-grained heat affected zone were evaluated successfully.

  10. 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

  11. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  13. 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.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  16. Formation mechanism of linear friction welded Ti-6Al-4V alloy joint based on microstructure observation

    SciTech Connect

    Ma Tiejun; Chen Tao, E-mail: ctwc-13@163.com; Li Wenya; Wang Shiwei; Yang Siqian

    2011-01-15

    The microstructure of the linear friction welded Ti-6Al-4V titanium alloy joint was investigated by optical microscope, scanning electronic microscope and transmission electron microscope. Results show that the dynamic recovery and recrystallization resulting from the intensive plastic deformation and fast heating and cooling processes during linear friction welding account for the superfine {alpha} + {beta} grains in the weld center. Fine {alpha} grains distribute in the {beta} matrix or at the boundaries of {beta} grains. A mass of dislocations networks and metastructures present within the {alpha} and {beta} grains. - Research Highlights: {yields} TEM is employed in the analysis. {yields} The dynamic recovery is the main mechanism in thermal deformation of TC4. {yields} Superfine grains in the weld result from dynamic recovery and dynamic recrystallizaion, but the recrystallization is inadequate.

  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. A study on fatigue strength reduction factor for small diameter socket welded pipe joints

    SciTech Connect

    Higuchi, Makoto; Nakagawa, Akira [Ishikawajima-Harima Heavy Industries, Yokohama (Japan); Hayashi, Makoto [Hitachi Ltd. (Japan); Yamauchi, Takayoshi [Mitsubishi Heavy Industries, Takasago (Japan); Saito, Masahiro [Toshiba Corp., Yokohama (Japan); Iida, Kunihiro [Shibaura Inst. of Tech., Tokyo (Japan); Matsuda, Fukuhisa [Osaka Univ., Ibaraki, Osaka (Japan); Sato, Masanobu [Japan Power Engineering and Inspection Corp., Minato, Tokyo (Japan)

    1996-12-01

    Factors that may exert influence on the fatigue strength of small diameter socket welded joints of nominal diameter in the 20--50 mm range have been investigated by the fully reversed four-point bending fatigue test with the material, diameter, pipe schedule, throat depth, bead shape, slip-on gap, and root defect as the testing parameters. The fatigue strength of socket joints depended acutely on the diameter. When the diameter is large, the fatigue strength tended to be low and the fracture is of the root-failure mode; when it is small, on the other hand, the fatigue strength is high and the fracture is of the toe-failure mode. Stainless steel proved to be superior to carbon steel; it gave rise to 1.37 times the fatigue strength of the latter for socket joints of nominal diameter 50 mm; the fatigue strength reduction factor determined at 10{sup 7} cycles with respect to the fatigue strength of smooth base metal in the fully reversed fatigue was about 4 for stainless steel and about 5 for carbon steel. The fatigue strength was higher, the larger the Sche number (i.e., the thicker the pipe wall); it was improved markedly by placing one final refinement pass on the toe or by eliminating the slip-on gap. An empirical formula relating the size of the root defect to the fatigue strength reduction has been proposed.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. Joint characteristics and dissimilar materials joining of pure-Al\\/5083 by friction stir welding

    Microsoft Academic Search

    M. Katoh; K. Nishio; T. Yamaguchi; M. Uemura; S. Oohara

    2005-01-01

    Friction stir welding (FSW), developed in 1991 by The Welding Institute, UK is a joining process which overthrew welding concepts which existed at the time; its application has been progressed not only for soft alloys including aluminium, but also, in recent years, for steel. Sato and others carried out friction stir welding on 1080-O and 5083-O materials and investigated variations

  4. Joint formation in the solid-phase welding of highly refractory single-phase components

    Microsoft Academic Search

    I. S. Kainarskii; É. V. Degtyareva; I. I. Boyarina

    1973-01-01

    During the welding of heated metal components, plastic deformation is an essential condition for the formation of the welded connection. It leads to a warping of the microirregularit ies on the welded surfaces, resulting in the formation of physical contact between the components, and activation of recrystallizatio n in the contact zones. The processes of welding refractory materials have not

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  7. Effect of Nd:YAG Laser Welding Parameters on the Hardness of lap joint: experimental and numerical approach

    NASA Astrophysics Data System (ADS)

    Seang, C.; David, A. Kouadr; Ragneau, E.

    The observation on microstructure and microhardness has been evaluated by experimental methods and also approached to simulation work. One found out higher volume fraction of martensite inside the HAZ and the FZ that is the main cause of higher hardness insides these zones and no softening zone created by laser Nd: YAG on sheet metal of dual phase steel DP600. So the precaution during laser welding Nd: YAG at any welding speed, focal point position and power should be considered in order to prevent a crack and fracture of laser lap joint DP600 during service.

  8. 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.

  9. Effect of the welding heat input on residual stresses in butt-welds of dissimilar pipe joints

    Microsoft Academic Search

    D. Akbari; I. Sattari-Far

    2009-01-01

    This study used finite element techniques to analyse the thermo-mechanical behaviour and residual stresses in dissimilar butt-welded pipes. The residual stresses at the surface of some weld specimens were measured experimentally by using the hole-drilling method. The results of the finite element analysis were compared with experimentally measured data to evaluate the accuracy of the finite element modelling. Based on

  10. Welding.

    ERIC Educational Resources Information Center

    Cowan, Earl; And Others

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

  11. Welding.

    ERIC Educational Resources Information Center

    Baldwin, Harold; Whitney, Gregory

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

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

    SciTech Connect

    Takuro Terajima; Takashi Hirano [Ishikawajima-Harima Heavy Industies Co., Ltd (Japan)

    2006-07-01

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

  13. 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

  14. Numerical simulation of the laser welding process in butt-joint specimens

    Microsoft Academic Search

    S. A Tsirkas; P Papanikos; Th Kermanidis

    2003-01-01

    A three-dimensional finite element model has been developed to simulate the laser welding process and predict laser welded panel distortions. The finite element calculations were performed using the SYSWELD FE code, which takes into account thermal, metallurgical and mechanical aspects. The simulation of the laser welding process was performed using a nonlinear heat transfer analysis, based on a keyhole formation

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

  16. Optimization of FS Welding Parameters for Improving Mechanical Behavior of AA2024-T351 Joints Based on Taguchi Method

    NASA Astrophysics Data System (ADS)

    Vidal, C.; Infante, V.

    2013-08-01

    In the present study, the design of an experiment technique, the Taguchi method, has been used to optimize the friction stir welding (FSW) parameters for improving mechanical behavior of AA2024-T351 joints. The parameters considered were vertical downward forging force, tool travel speed, and probe length. An orthogonal array of L9 (34) was used; ANOVA analyses were carried out to identify the significant factors affecting tensile strength (Global Efficiency to Tensile Strength—GETS), bending strength (Global Efficiency to Bending—GEB), and hardness field. The percentage contribution of each parameter was also determined. As a result of the Taguchi analysis in this study, the probe length is the most significant parameter on GETS, and the tool travel speed is the most important parameter affecting both the GEB and the hardness field. An algebraic model for predicting the best mechanical performance, namely fatigue resistance, was developed and the optimal FSW combination was determined using this model. The results obtained were validated by conducting confirmation tests, the results of which verify the adequacy and effectiveness of this approach.

  17. Surface preparation is key to girth weld coating performance. [Corrosion resistive coatings on welded joints in pipeline construction

    SciTech Connect

    Neal, D. (Harding and Neal, Inc., Houston, TX (United States))

    1994-02-01

    Test evaluations show that girth weld coatings, regardless of the type of coating, provides better performance when applied over an ideally prepared surface. Primary coating for most new pipe lines is applied in a coating plant under detailed specifications and controlled conditions. Typically, surface preparation, preheat, application, and other important parameters are well controlled and the coating is, of course, applied inside a building. This is not the case for girth weld coatings. Obviously, they are applied in the open air along the right-of-way and, in many cases, specification and quality control are minimal. The exception is fusion bond epoxy (FBE) girth weld coatings, usually applied to specification and often under conditions and requirements that approach or equal those in the coating plant. An important factor that frequently is poorly controlled is surface preparation. Although it is generally believed pipe line coatings perform better over clean surfaces, girth well coatings are frequently applied over wire-brushed or poorer surfaces. To evaluate the performance, five girth weld coatings were applied to surfaces with different levels of cleanliness. Testing was undertaken at ambient and elevated temperatures. Some selected coatings were premium coatings for their type, others were not. Individual performance by type, therefore, may not necessarily by typical for similar coatings.

  18. Deconvoluting the Friction Stir Weld Process for Optimizing Welds

    NASA Technical Reports Server (NTRS)

    Schneider, Judy; Nunes, Arthur C.

    2008-01-01

    In the friction stir welding process, the rotating surfaces of the pin and shoulder contact the weld metal and force a rotational flow within the weld metal. Heat, generated by the metal deformation as well as frictional slippage with the contact surface, softens the metal and makes it easier to deform. As in any thermo-mechanical processing of metal, the flow conditions are critical to the quality of the weld. For example, extrusion of metal from under the shoulder of an excessively hot weld may relax local pressure and result in wormhole defects. The trace of the weld joint in the wake of the weld may vary geometrically depending upon the flow streamlines around the tool with some geometry more vulnerable to loss of strength from joint contamination than others. The material flow path around the tool cannot be seen in real time during the weld. By using analytical "tools" based upon the principles of mathematics and physics, a weld model can be created to compute features that can be observed. By comparing the computed observations with actual data, the weld model can be validated or adjusted to get better agreement. Inputs to the model to predict weld structures and properties include: hot working properties ofthe metal, pin tool geometry, travel rate, rotation and plunge force. Since metals record their prior hot working history, the hot working conditions imparted during FSW can be quantified by interpreting the final microstructure. Variations in texture and grain size result from variations in the strain accommodated at a given strain rate and temperature. Microstructural data from a variety of FSWs has been correlated with prior marker studies to contribute to our understanding of the FSW process. Once this stage is reached, the weld modeling process can save significant development costs by reducing costly trial-and-error approaches to obtaining quality welds.

  19. Features of misoriented structures in a copper-copper bilayer plate obtained by explosive welding

    NASA Astrophysics Data System (ADS)

    Rybin, V. V.; Ushanova, E. A.; Zolotorevskii, N. Yu.

    2013-09-01

    Structures induced by deformation in the narrow zone of a contact between two copper plates that is prepared by explosive welding are systematically investigated at the micro-, meso-, and macrolevels. Plastic jets, regions of metal plastic flow anomalous localization, are discovered in areas adjacent to the contact surface. The defect structure of the plastic jets is examined by transmission electron microscopy and electron backscatter diffraction. It is shown that at the mesolevel the plastic jets are regions with a heavily fragmented structure. The statistics of the fragment distribution over misorientations and transverse sizes is studied.

  20. Effects of strain-rate and pre-fatigue on tensile properties of laser welded joint of high strength steel plates

    NASA Astrophysics Data System (ADS)

    Kobayashi, H.; Daimaruya, M.; Tsuda, H.; Horikawa, K.

    2006-08-01

    The impact tensile properties of laser welded butt joints of two kinds of high strength steel plates with the tensile strength level of 590 MPa and 780 MPa (denoted by HR590 and HR780, respectively), were investigated using split Hopkinson bar tensile testing apparatus. Impact tension tests for the joint specimens pre-fatigued were also carried out to examine the effect of pre-fatigue. There were no significant effects of strain-rate and pre-fatigue on the dynamic and quasi-static tensile strength of laser welded butt joints. However, the decrease in the elongation of HR780 welded joints subjected high cycle pre-fatigue was observed only at a high strain-rate. From the observation of fracture surface, it was found that the decrease in the elongation may be caused by a number of damages due to the combination of high cycle pre-fatigue and high strain-rate.

  1. 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

  2. WELDING RESEARCH -S237WELDING JOURNAL

    E-print Network

    Cambridge, University of

    the tallest building in the world -- Fig. 1. These are all made from steel and rely on welding there is little that can be done once the weld is completed (Refs. 1­3). This contrasts with wrought steel, which of welding consum- ables involves all weld-metal tests in which a joint is deposited such that sam- ples can

  3. Effect of pre- and post-weld heat treatment on metallurgical and tensile properties of Inconel 718 alloy butt joints welded using 4 kW Nd:YAG laser

    Microsoft Academic Search

    X. Cao; B. Rivaux; M. Jahazi; J. Cuddy; A. Birur

    2009-01-01

    The effects of pre- and post-weld heat treatments on the butt joint quality of 3.18-mm thick Inconel 718 alloy were studied\\u000a using a 4 kW continuous wave Nd:YAG laser system and 0.89-mm filler wire with the composition of the parent metal. Two pre-weld\\u000a conditions, i.e., solution treated, or solution treated and aged, were investigated. The welds were then characterized in\\u000a the

  4. Effect of strong shot peening cleaning and hot galvanizing on fatigue strength of steel welded joint

    Microsoft Academic Search

    Masayoshi Hasegawa; Hiroaki Suzuki; Ken Miura

    2009-01-01

    The soiling of the slag, spatter and the fume, etc., which come into contact with the steel sheet surface with welding, is cleaned making use of steel sphere shot material of large particle diameter, high projection pressure with strong peening processing (below, called strong peening cleaning). In this research, the cleaning state of the soiling with welding and improvement of

  5. 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).

  6. Stress concentration factors and fatigue behaviour of welded thin-walled CHS–SHS T-joints under in-plane bending

    Microsoft Academic Search

    Fidelis Rutendo Mashiri; Xiao-Ling Zhao; Paul Grundy

    2004-01-01

    Fatigue tests were carried out on welded thin-walled (t<4 mm) T-joints made of circular hollow section (CHS) braces welded onto square hollow section (SHS) chords, under the loading conditions of “in-plane bending in the brace”. Stress distributions were measured at different hot spot locations around the chord–brace junction, where cracks were observed to initiate and grow causing fatigue failure. The

  7. 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

  8. 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.

  9. 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.

  10. Effect of Capping Front Layer Materials on the Penetration Resistance of Q&T Steel Welded Joints Against 7.62-mm Armor-Piercing Projectile

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    In the present investigation, an attempt has been made to study the effect of capping front layers on the ballistic performance of shielded metal arc-welded armor steel joints which were fabricated with a chromium carbide-rich hardfaced middle layer on the buttered/beveled edge. Two different capping front layer materials were chosen for achieving better ballistic performance, namely, low hydrogen ferritic (LHF) and austenitic stainless steel (SS) fillers. On the other hand, the bottom layers are welded with SS filler for both joints. The consequent sandwiched joint served the dual purpose of weld integrity and penetration resistance of the bullet. It is observed that the penetration resistance is due to the high hardness of the hardfacing layer on the one hand and the energy-absorbing capacity of the soft backing SS weld deposits on the other hand. The complementary effect of layers successfully provided resistance to the projectile penetration. On a comparative analysis, the joint fabricated using the LHF filler capping front layer offered superior ballistic performance with respect to depth of penetration. This is mainly due to the presence of acicular ferrite along the bainitic structure in the LHF capping front layer, which caused a shallow hardness gradient along the weld center line.

  11. Computational-experimental investigation of the lifetime of welded pipe joints based on the method of local modelling

    NASA Astrophysics Data System (ADS)

    Belokurov, V. N.; Pavlovskij, V. E.; Strel'Chenko, A. S.; Strel'Chenko, I. G.; Filatov, E. Ya.

    1994-06-01

    A conception of local modeling of fatigue lifetime for thin-walled structural elements of shell type is formulated. An experimental procedure to determine the lifetime of welded thin-walled pipe joints is given. The estimation of the structure lifetime is performed on the basis of testing its local models which provide the similarity of fatigue fracture process parameters. Fatigue test results for T-shaped pipe joints and their models are presented. A specific choice of the model geometry makes it possible to 'reproduce' the values of the lifetime close to those of a full-scale structure, with the magnitude of the repeated variable load being essentially lower than that on the structure.

  12. 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.

  13. Microstructure and Mechanical Properties of Pulsed Laser Beam Welded Ti-2Al-1.5Mn Titanium Alloy Joints

    NASA Astrophysics Data System (ADS)

    Fang, Xiuyang; Liu, Hong; Zhang, Jianxun

    2014-06-01

    The microstructure and mechanical properties in the pulsed laser beam welded joints of Ti-2Al-1.5Mn titanium alloy thin sheet were investigated in this study. The results show that the original ? + ?-phases and the transformed ? + ?'-phases are found in the partially transformed heat-affected zone (HAZ) together with the remaining ?-phase, and the microhardness gradually enhances in the region as the result of the increase of ?'-phase. The martensitic ?'-phase and the remaining ?-phase are detected in the fully transformed HAZ and the fusion zone (FZ), and the highest microhardness is found in these regions in virtue of the dominant ?'-phase structure. The fine ?'-phase appeared in the FZ results in higher average microhardness at high welding speed. Moreover, similar to the results of microhardness test, the tensile test results mean that the HAZ and FZ are stronger than the base metal (BM). Therefore, pulsed laser beam welding is feasible for joining thin sheet of Ti-2Al-1.5Mn titanium alloy.

  14. Properties of Friction Stir Welded Joints: A Review of the Literature

    Microsoft Academic Search

    D. Harris; A. F. Norman

    The solid-state process of friction stir welding (FSW) was invented in 1991 by TWI (1), and its emergence as a commercial joining technique is partly due to the ease with which the more difficult-to-weld high strength aluminium alloys can be joined. Whilst the process was developed initially for aluminium alloys, over the past decade the number of materials found to

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

    Microsoft Academic Search

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

    2011-01-01

    The aim of this investigation was to evaluate the microstructural change after laser welding and its effect on the tensile\\u000a properties and strain hardening behavior of DP600 and DP980 dual-phase steels. Laser welding led to the formation of martensite\\u000a and significant hardness rise in the fusion zone because of the fast cooling, but the presence of a soft zone in

  16. 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.

  17. 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.

  18. Characterization of microstructure, chemical composition, corrosion resistance and toughness of a multipass weld joint of superduplex stainless steel UNS S32750

    SciTech Connect

    Tavares, S.S.M. [Universidade Federal Fluminense, Departamento de Engenharia Mecanica/PGMEC, Rua Passo da Patria, 156, CEP 24210-240, Niteroi/RJ (Brazil)]. E-mail: ssmtavares@terra.com.br; Pardal, J.M. [Universidade Federal Fluminense, Departamento de Engenharia Mecanica/PGMEC, Rua Passo da Patria, 156, CEP 24210-240, Niteroi/RJ (Brazil); Lima, L.D. [Universidade Federal Fluminense, Departamento de Engenharia Mecanica/PGMEC, Rua Passo da Patria, 156, CEP 24210-240, Niteroi/RJ (Brazil); Bastos, I.N. [Universidade do Estado do Rio de Janeiro (UERJ), Instituto Politecnico (IPRJ), Nova Friburgo/RJ (Brazil); Nascimento, A.M. [Universidade Estadual de Campinas (UNICAMP), Departamento de Engenharia Mecanica, Campinas/SP (Brazil); Souza, J.A. de [Universidade Federal Fluminense, Departamento de Engenharia Mecanica/PGMEC, Rua Passo da Patria, 156, CEP 24210-240, Niteroi/RJ (Brazil)

    2007-07-15

    The superduplex stainless steels have an austeno-ferritic microstructure with an average fraction of each phase of approximately 50%. This duplex microstructure improves simultaneously the mechanical properties and corrosion resistance. Welding of these steels is often a critical operation. In this paper we focus on characterization and analysis of a multipass weld joint of UNS S32750 steel prepared using welding conditions equal to industrial standards. The toughness and corrosion resistance properties of the base metal, root pass welded with gas tungsten arc welding, as well as the filler passes, welded with shielded metal arc welding, were evaluated. The microstructure and chemical composition of the selected areas were also determined and correlated to the corrosion and mechanical properties. The root pass was welded with low nickel filler metal and, as a consequence, presented low austenite content and significant precipitation. This precipitation is reflected in the corrosion and mechanical properties. The filler passes presented an adequate ferrite:austenite proportion but, due to their high oxygen content, the toughness was lower than that of the root pass. Corrosion properties were evaluated by cyclic polarization tests in 3.5% NaCl and H{sub 2}SO{sub 4} media.

  19. 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.

  20. 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.

  1. Careers in Welding

    NSDL National Science Digital Library

    Careers in Welding is a portal jointly produced by the American Welding Society and Weld-Ed, the Nation Center for Welding Education and Training. Here, visitors will find information for educators, students, and welding professionals, in addition to general information about exploring a career in welding. Educators can find teaching tips, curriculum, professional development information, resources and products, events, and networking opportunities. Students can find information about schools with welding programs, scholarships, jobs, and much more. For the welding professional, the site has tips for building a resume, finding a job, and AWS certification information. The site also features videos of technicians and general articles, such as "Why Welding?" and "Welding Fast Facts," that offer information on why to choose a career in welding.

  2. Welding deep water pipelines

    SciTech Connect

    Teale, R.A.; Laing, B.S. [CRC-Evans Automatic Welding, Houston, TX (United States)

    1994-12-31

    The objective of this research program was to investigate the girth welding of pipe in the vertical or near vertical position (2G) for J-welding construction in deep-water applications. The tasks investigated included two approaches (depositing the root pass on the pipe I.D. with the balance of welding on the O.D. and all welding on the O.D.), arc-welding processes, shielding gases, arc welding parameters, weld joint design, mechanical properties of deposited welds, and determination of the extent of heat buildup in the pipe during welding. Welding procedures were developed for both the internal root/balance O.D. welding and for the all external welding approaches.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  4. 49 CFR 179.400-11 - Welding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...jacket must be a fusion double welded butt joint. (b) The closure for openings...shell joints, may be a single welded butt joint using a backing strip on the inside of the joint. (c) Each joint must be welded in accordance with the...

  5. 49 CFR 179.400-11 - Welding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...jacket must be a fusion double welded butt joint. (b) The closure for openings...shell joints, may be a single welded butt joint using a backing strip on the inside of the joint. (c) Each joint must be welded in accordance with the...

  6. Microstructure and hardness of friction stir welded 7075 aluminium alloy joints

    Microsoft Academic Search

    T. Shibayanagi; M. Maeda

    2005-01-01

    Friction stir welding (FSW) is a process which induces a reduction in flow stress owing to friction heat generated by pressing a protruded object into a solid material and rotating it at high speed. It induces part of the material to have plastic flow owing to friction force in order to join materials together. The FSW method was developed for

  7. FATIGUE ANALYSIS METHODS: THEIR PERFORMANCE EVALUATION FOR A CLASS OF PRESSURE VESSELS WITH WELDED JOINTS

    Microsoft Academic Search

    Arturs Kalnins

    2009-01-01

    This paper provides a basis for evaluating the performance of a fatigue analysis method for a selected class of welded pressure vessels. After the allowable number of cycles that the method permits for a member of the class is calculated, the question is addressed whether that number of cycles can be regarded as conservative or unconservative. To answer that question,

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

    NASA Astrophysics Data System (ADS)

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

    2009-07-01

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

  9. 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

  10. Improving fatigue performance of rail thermite welds

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

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

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1995-02-01

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

  13. 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

  14. Study on microstructures and mechanical properties of laser-arc hybrid welded S355J2W+N steel

    NASA Astrophysics Data System (ADS)

    Zhen, Shu; Duan, Zhenzhen; Sun, Daqian; Li, Yexiong; Gao, Dandan; Li, Hongmei

    2014-07-01

    The technology of laser-MAG hybrid welding was used on 16 mm thick plate of weathering steel S355J2W+N. Under the welding parameters used in the experiment, full penetration weld without flaws such as pores, cracks and lack of fusion was obtained by a three-layer and three-pass welding technique. In this study, the outstanding advantages of laser-arc hybrid welding were summarized by comparison with welded joint of traditional MAG welding. The microstructure of hybrid welded joint has also been detailed investigated. Besides, the mechanical property tests were performed according to corresponding European standards. Furthermore, the tensile and impact strength of laser-MAG hybrid welded joint turned out to be almost as good as base metal. Most of the hybrid welded joints had a good bending property, but for some sample, there was a micro-crack with the length of 0.9 mm emerging within the transition region where contraction stress would accumulate and remain, being one of the most vulnerable zones in weld metal. The results show that laser-MAG hybrid welding technology is appropriate for S355J2W+N thick plate welding, in favor of not only improving the product performance, but also lowering the production cost and improving the productivity.

  15. Investigation of the effect of welding parameters on weld quality of plasma arc keyhole welding of structural steels

    SciTech Connect

    Martikainen, J.K.; Moisio, T.J.I. (Lappeenranta Univ. of Technology, Lappeenranta (Finland). Welding Technology Lab.)

    1993-07-01

    In the present investigation, the individual and interactive effects of the main welding parameters on weld quality of plasma arc keyhole welding of conventional structural steel, high strength microalloyed steel and strong formable microalloyed steel have been examined using welding of butt joints with a square groove in various welding positions, and welding of joint roots with a single-V-groove and the root face in the flat position. The most important welding parameters are welding current, welding speed and welding gases, especially plasma gas flow rate. Welding parameter combinations producing the best quality welds are presented. It is shown that it is possible to achieve defect-free high-quality welds with good strength and toughness properties, but the allowable range of variation of welding parameters, especially for the highest weld quality, is narrow. An argonhydrogen mixture for the plasma gas together with argon as shielding and backing gases give the best results with respect to weld quality.

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

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

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

  17. 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. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  20. Friction welding.

    NASA Technical Reports Server (NTRS)

    Moore, T. J.

    1972-01-01

    Results of an exploratory study of the structure and properties of friction welds in Udimet 700 (U-700) and TD-nickel (TD-Ni) bar materials, as well as dissimilar U-700/TD-Ni friction welds. Butt welds were prepared by friction welding 12.7-mm-diam U-700 bars and TD-Ni bars. Specimens for elevated temperature tensile and stress rupture testing were machined after a postweld heat treatment. Friction welding of U-700 shows great potential because the welds were found to be as strong as the parent metal in stress rupture and tensile tests at 760 and 980 C. In addition, the weld line was not detectable by metallographic examination after postheating. Friction welds in TD-Ni or between U-700 and TD-Ni were extremely weak at elevated temperatures. The TD-Ni friction welds could support only 9% as much stress as the base metal for 10-hour stress rupture life at 1090 C. The U-700/TD-Ni weld could sustain only 15% as much stress as the TD-Ni parent metal for a 10-hour stress rupture life at 930 C. Thus friction welding is not a suitable joining method for obtaining high-strength TD-Ni or U-700/TD-Ni weldments.

  1. Automated Variable-Polarity Plasma-Arc Welding

    NASA Technical Reports Server (NTRS)

    Numes, A. C., Jr.; Bayless, E. O., Jr.; Jones, S. C., III; Munafo, P.; Munafo, A.; Biddle, A.; Wilson, W.

    1984-01-01

    Variable-polarity plasma-arc methods produces better welds at lower cost than gas-shielded tungsten-arc welding in assemblies. Weld porosity very low and costs of joint preparation, depeaking, inspection, and weld repair minimized.

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

    NASA Technical Reports Server (NTRS)

    HARTMANN E C; Stickley, G W

    1942-01-01

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

  3. 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

  4. 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

  5. A transient finite element simulation of the temperature and bead profiles of T-joint laser welds

    Microsoft Academic Search

    N. Siva Shanmugam; G. Buvanashekaran; K. Sankaranarayanasamy; S. Ramesh Kumar

    2010-01-01

    Laser welding is a high power density welding technology, which has the capability of focusing the beam power to a very small spot diameter. Its characteristics such as high precision and low and concentrated heat input, helps in minimizing the micro-structural modifications, residual stresses and distortions on the welded specimens. In this study, finite element method (FEM) is adopted for

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  7. 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.

  8. 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.

  9. 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.

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

    NASA Technical Reports Server (NTRS)

    Schaper, V. D.; Pollack, A.

    1972-01-01

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

  11. Joints

    NSDL National Science Digital Library

    Olivia Worland (Purdue University; Biological Sciences)

    2008-06-06

    Hinge joints move only in one direction, ball-and-socket joints are free to rotate in all directions, and gliding joints are able to move forward, backward, and side to side, but do not rotate freely.

  12. 46 CFR 154.650 - Cargo tank and process pressure vessel welding.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...meet the following: (1) Each welded joint of the shells must be a full...penetrations on domes. (d) Each welded joint in an independent tank type...Commandant (CG-522). (e) Each welded joint in a membrane tank must...

  13. 46 CFR 154.650 - Cargo tank and process pressure vessel welding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...meet the following: (1) Each welded joint of the shells must be a full...penetrations on domes. (d) Each welded joint in an independent tank type...Commandant (CG-522). (e) Each welded joint in a membrane tank must...

  14. 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.

  15. A Study of the Effect of Tool Pin Profiles on Tensile Strength of Welded Joints Produced Using Friction Stir Welding Process

    Microsoft Academic Search

    C. N. Suresha; B. M. Rajaprakash; Sarala Upadhya

    2011-01-01

    Friction Stir Welding (FSW) has evolved into a process focused on joining of arc-weldable (5xxx and 6xxx) and which are difficult to weld (2xxx and 7xxx) aluminium alloys. The method described in this paper for the prediction of tensile properties and optimization can eliminate the need for performing experiments on the basis of conventional trial and error method. The present

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

    SciTech Connect

    Zhu, Ming-Liang, E-mail: mlzhu@ecust.edu.cn; Wang, De-Qiang; Xuan, Fu-Zhen

    2014-01-15

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

  17. Fracture evaluation of fusion line cracks in bimetallic welds

    SciTech Connect

    Scott, P.M.; Rudland, D.L.; Francini, R.B.; Marschall, C.; Wilkoswski, G.M. [Battelle, Columbus, OH (United States)

    1996-12-01

    There are many locations in nuclear power plants piping systems where carbon steel pipe or components are jointed to stainless steel pipe or components with a bimetallic weld. The objective of the research described in this paper was to assess the accuracy of current fracture analyses for the case of a crack along a carbon steel to austenitic weld fusion line. To achieve th is objective, material property data and data from a large-diameter (i.e., 36-inch) pipe fracture experiment were developed to assess current analytical methods. The bimetallic welds evaluated in this program were bimetallic welds obtained from a canceled Combustion Engineering plant. The welds joined sections of the carbon steel cold-leg piping system to stainless steel safe ends that were to be welded to stainless steel pump housings. The weld procedure involved buttering the carbon steel pipe with Inconel 182 weld metal and then completing the bulk of the weld using a shielded-metal-arc weld (SMAW) process using Inconel 182 weld rod. The major conclusion drawn as a result of these efforts was that the fracture behavior of the bimetallic weld evaluated in this program could be evaluated with reasonable accuracy using the strength and toughness properties of the carbon steel pipe base metal in conjunction with conventional J-estimation schemes. As will be discussed in this paper, this conclusion is only valid for the case where the weld is made using an Inconel weld procedure. If the weld is made using a stainless steel weld procedure, then decarburization at the fusion line may affect the fusion line toughness.

  18. Algunas consideraciones sobre la contaminación ambiental en la obtención y uso de fundentes para la soldadura automática por arco sumergido Some considerations about the environmental contamination in the fluxes obtaining and use in the submerged arc welding

    Microsoft Academic Search

    Facultad de Ingeniería Mecánica; Eriel Pérez Zapico; Carlos R. Gómez Pérez; Rafael Quintana Puchol; Lorenzo Perdomo González

    In the paper a some considerations about the environmental contamination during the obtaining process and use welding fluxes for submerged arc welding process are given. Is appreciated that the processes GMAW, SMAW and FCAW are those more studied regarding the indicative of environmental contamination, but solely related with the affections on the operatives and welders. However, the productive processes of

  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. 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.

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

    Microsoft Academic Search

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

    2011-01-01

    The microstructure and mechanical properties of Inconel 617\\/310 austenitic stainless steel dissimilar welds were investigated in this work. Three types of filler materials, Inconel 617, Inconel 82 and 310 austenitic stainless steels were used to obtain dissimilar joint using the gas tungsten arc welding process. Microstructural observations showed that there was no evidence of any possible cracking in the weldments

  2. 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.

  3. Friction stir welding of AZ-91 and AM-Lite magnesium alloys

    Microsoft Academic Search

    Lechos?aw Tuz; Pawe? Ko?odziejczak; Andrzej Kolasa

    2011-01-01

    The objective of this paper was to report the results of butt joint quality of friction stir welding (FSW) of samples of alloys of MgAlZn group. Welding has been carried out with the FSW tool of welding speed ranging from 140 to 355 mm\\/min. In the stir zone and the surrounding, neither porosity nor cracks have been obtained. Microhardness in the

  4. Solid-state welding of metals with application of high density current pulses

    Microsoft Academic Search

    V. D. Polovinko; E. S. Yurchenko

    2008-01-01

    The results of solid-state welding of homogeneous and heterogeneous metals with application of high density current pulses\\u000a are presented. A chart of the current treatment allowing obtaining of the welded joint at its heating in an air atmosphere\\u000a is proposed. The influence of alternating and unipolar current on the deformation of contact surface microroughnesses in the\\u000a welding zone is considered.

  5. Behaviour of trace bismuth in welded joints of nodular cast iron and development of ZU238F covered electrodes

    Microsoft Academic Search

    Peng Gaoe; Zhang Baoguo; Li Fengyun

    1988-01-01

    The effect of trace bismuth in nodular cast iron welds on nodulisation, graphitisation and ferrite formation has been investigated. The results indicate that as trace Bi increases the graphite nodule count and nodulising stability increase, promoting the forming of ferrite, and effectively decreasing or even eliminating the cementite in the weld and partial melting region. Therefore, the crack resistance and

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 46 CFR 52.05-45 - Circumferential joints in pipes, tubes and headers (modifies PW-41).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... (a) Circumferential welded joints of pipes, tubes and headers...PW-41.1 ) Circumferential welded joints in pipes, tubes, and headers...radiography is not required, welded socket or sleeve type joints meeting the requirements...

  11. 46 CFR 52.05-45 - Circumferential joints in pipes, tubes and headers (modifies PW-41).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... (a) Circumferential welded joints of pipes, tubes and headers...PW-41.1 ) Circumferential welded joints in pipes, tubes, and headers...radiography is not required, welded socket or sleeve type joints meeting the requirements...

  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. 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.

  14. 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.

  15. Enhanced diffusion welding

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

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

  16. Some studies on temperature profiles in AISI 304 stainless steel sheet during laser beam welding using FE simulation

    Microsoft Academic Search

    N. Siva Shanmugam; G. Buvanashekaran; K. Sankaranarayanasamy; K. Manonmani

    2009-01-01

    The investigation of transient temperature profiles of a weld joint produced by the laser welding process is presented. A\\u000a three-dimensional finite element model is developed using a commercial finite element code ANSYS in order to obtain the behavior\\u000a of temperature field and molten pool shape during the welding process. A three-dimensional conical Gaussian heat source is\\u000a employed as a heat

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  18. Welding blades to rotors

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

    A process is described to form T-joints between dissimilar thickness parts by magnetic force upset welding. This type of resistance welding is used to join compressor and turbine parts which thereby reduces the weight and cost of jet engines.

  19. Gas Shielding Technology for Welding and Brazing

    NASA Technical Reports Server (NTRS)

    Nunes, Arthur J.; Gradl, Paul R.

    2012-01-01

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

  20. Clamp and Gas Nozzle for TIG Welding

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  1. Measuring Weld Parameters By Spectroscopy

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  2. Microstructure and mechanical properties in TIG welding of CLAM steel

    Microsoft Academic Search

    Qiang Zhu; Yu-cheng Lei; Xi-zhang Chen; Wen-jie Ren; Xin Ju; Yi-min Ye

    2011-01-01

    Tungsten insert gas (TIG) welding on China low activation martensitic (CLAM) steel under identical conditions was performed. Microhardness test, tensile test, Charpy impact test and microstructure measurements were carried out on TIG welded joints after post weld heat-treatment. Hardening at WM and softening in HAZ is detected in the TIG weld joint. Microhardness in WM decreased when the temperature of

  3. 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

  4. Details of the Electro-Mechanical (E/M) Impedance Health Monitoring of Spot-Welded Structural Joints

    E-print Network

    Giurgiutiu, Victor

    -alloy spot-welded lap shear specimens under fatigue loading to determine a stable pattern of crack propagation in correlation with applied fatigue cycles. The specimen stiffness method was used to correlate method of assessing the degree of structural deterioration as a function of applied fatigue cycles

  5. 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:…

  6. 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.

  7. 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.

  8. 49 CFR 179.200-10 - Welding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...SPECIFICATIONS FOR TANK CARS Specifications for Non-Pressure...179.200-10 Welding. (a) All joints...requirements of AAR Specifications for Tank Cars, appendix...this subchapter). Welding procedures, welders and...

  9. 49 CFR 179.100-9 - Welding.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...SPECIFICATIONS FOR TANK CARS Specifications for Pressure Tank... § 179.100-9 Welding. (a) All joints...requirements of AAR Specifications for Tank Cars, appendix...this subchapter). Welding procedures, welders and...

  10. 49 CFR 179.200-10 - Welding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...SPECIFICATIONS FOR TANK CARS Specifications for Non-Pressure...179.200-10 Welding. (a) All joints...requirements of AAR Specifications for Tank Cars, appendix...this subchapter). Welding procedures, welders and...

  11. 49 CFR 179.100-9 - Welding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...SPECIFICATIONS FOR TANK CARS Specifications for Pressure Tank... § 179.100-9 Welding. (a) All joints...requirements of AAR Specifications for Tank Cars, appendix...this subchapter). Welding procedures, welders and...

  12. 49 CFR 179.100-9 - Welding.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...SPECIFICATIONS FOR TANK CARS Specifications for Pressure Tank... § 179.100-9 Welding. (a) All joints...requirements of AAR Specifications for Tank Cars, appendix...this subchapter). Welding procedures, welders and...

  13. 49 CFR 179.200-10 - Welding.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...SPECIFICATIONS FOR TANK CARS Specifications for Non-Pressure...179.200-10 Welding. (a) All joints...requirements of AAR Specifications for Tank Cars, appendix...this subchapter). Welding procedures, welders and...

  14. 49 CFR 179.200-10 - Welding.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...SPECIFICATIONS FOR TANK CARS Specifications for Non-Pressure...179.200-10 Welding. (a) All joints...requirements of AAR Specifications for Tank Cars, appendix...this subchapter). Welding procedures, welders and...

  15. 49 CFR 179.100-9 - Welding.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...SPECIFICATIONS FOR TANK CARS Specifications for Pressure Tank... § 179.100-9 Welding. (a) All joints...requirements of AAR Specifications for Tank Cars, appendix...this subchapter). Welding procedures, welders and...

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

    NASA Astrophysics Data System (ADS)

    Ahmadi, E.; Ebrahimi, A. R.

    2015-02-01

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

  17. Laser Spot Welding of Copper-aluminum Joints Using a Pulsed Dual Wavelength Laser at 532 and 1064 nm

    NASA Astrophysics Data System (ADS)

    Stritt, Peter; Hagenlocher, Christian; Kizler, Christine; Weber, Rudolf; Rüttimann, Christoph; Graf, Thomas

    A modulated pulsed laser source emitting green and infrared laser light is used to join the dissimilar metals copper and aluminum. The resultant dynamic welding process is analyzed using the back reflected laser light and high speed video observations of the interaction zone. Different pulse shapes are applied to influence the melt pool dynamics and thereby the forming grain structure and intermetallic phases. The results of high-speed images and back-reflections prove that a modulation of the pulse shape is transferred to oscillations of the melt pool at the applied frequency. The outcome of the melt pool oscillation is shown by the metallurgically prepared cross-section, which indicates different solidification lines and grain shapes. An energy-dispersivex-ray analysis shows the mixture and the resultant distribution of the two metals, copper and aluminum, within the spot weld. It can be seen that the mixture is homogenized the observed melt pool oscillations.

  18. Predictive permeability model of faults in crystalline rocks; verification by joint hydraulic factor (JH) obtained from water pressure tests

    NASA Astrophysics Data System (ADS)

    Barani, Hamidreza Rostami; Lashkaripour, Gholamreza; Ghafoori, Mohammad

    2014-08-01

    In the present study, a new model is proposed to predict the permeability per fracture in the fault zones by a new parameter named joint hydraulic factor (JH). JH is obtained from Water Pressure Test (WPT) and modified by the degree of fracturing. The results of JH correspond with quantitative fault zone descriptions, qualitative fracture, and fault rock properties. In this respect, a case study was done based on the data collected from Seyahoo dam site located in the east of Iran to provide the permeability prediction model of fault zone structures. Datasets including scan-lines, drill cores, and water pressure tests in the terrain of Andesite and Basalt rocks were used to analyse the variability of in-site relative permeability of a range from fault zones to host rocks. The rock mass joint permeability quality, therefore, is defined by the JH. JH data analysis showed that the background sub-zone had commonly <3 Lu (less of 5 ×10-5 m 3/s) per fracture, whereas the fault core had permeability characteristics nearly as low as the outer damage zone, represented by 8 Lu (1.3 ×10-4 m 3/s) per fracture, with occasional peaks towards 12 Lu (2 ×10-4 m 3/s) per fracture. The maximum JH value belongs to the inner damage zone, marginal to the fault core, with 14-22 Lu (2.3 ×10-4-3.6 ×10-4 m 3/s) per fracture, locally exceeding 25 Lu (4.1 ×10-4 m 3/s) per fracture. This gives a proportional relationship for JH approximately 1:4:2 between the fault core, inner damage zone, and outer damage zone of extensional fault zones in crystalline rocks. The results of the verification exercise revealed that the new approach would be efficient and that the JH parameter is a reliable scale for the fracture permeability change. It can be concluded that using short duration hydraulic tests (WPTs) and fracture frequency (FF) to calculate the JH parameter provides a possibility to describe a complex situation and compare, discuss, and weigh the hydraulic quality to make predictions as to the permeability models and permeation amounts of different zone structures.

  19. Effect of Different Chromium Additions on the Microstructure and Mechanical Properties of Multipass Weld Joint of Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Kang, Dong Hoon; Lee, Hae Woo

    2012-12-01

    The correlation between the mechanical properties and ferrite volume fraction (approximately 40, 50, and 60 Ferrite Number [FN]) in duplex stainless steel weld metals were investigated by changing the Cr content in filler wires with a flux-cored arc-welding (FCAW) process. The interpass temperature was thoroughly maintained under a maximum of 423 K (150 °C), and the heat input was also sustained at a level under 15 KJ/cm in order to minimize defects. The microstructure examination demonstrated that the ?-ferrite volume fraction in the deposited metals increased as the Cr/Ni equivalent ratio increased, and consequently, chromium nitride (Cr2N) precipitation was prone to occur in the ferrite domains due to low solubility of nitrogen in this phase. Thus, more dislocations are pinned by the precipitates, thereby lowering the mobility of the dislocations. Not only can this lead to the strength improvement, but also it can accentuate embrittlement of the weld metal at subzero temperature. Additionally, the solid-solution strengthening by an increase of Cr and Mo content in austenite phase depending on the reduction of austenite proportion also made an impact on the increase of the tensile and yield strength. On the other hand, the impact test (at 293 K, 223 K, and 173 K [20 °C, -50 °C, and -100 °C]) showed that the specimen containing about 40 to 50 FN had the best result. The absorbed energy of about 40 to 50 J sufficiently satisfied the requirements for industrial applications at 223 K (-50 °C), while the ductile-to-brittle transition behavior exhibited in weldment containing 60 FN. As the test temperature decreased under 223 K (-50 °C), a narrow and deep dimple was transformed into a wide and shallow dimple, and a significant portion of the fracture surface was occupied by a flat cleavage facet with river patterns.

  20. 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.

  1. Prediction of weld strength and seam width for laser transmission welding of thermoplastic using response surface methodology

    NASA Astrophysics Data System (ADS)

    Acherjee, Bappa; Misra, Dipten; Bose, Dipankar; Venkadeshwaran, K.

    2009-11-01

    In the present work, a study is made to investigate the effects of process parameters, namely, laser power, welding speed, size of the laser beam and clamp pressure, on the lap-shear strength and weld-seam width for laser transmission welding of acrylic (polymethyl methacrylate), using a diode laser system. Response surface methodology (RSM) is employed to develop mathematical relationships between the welding process parameters and the output variables of the weld joint to determine the welding input parameters that lead to the desired weld quality. In addition, using response surface plots, the interaction effects of process parameters on the responses are analyzed and discussed. The statistical software Design-Expert v7 is used to establish the design matrix and to obtain the regression equations. The developed mathematical models are tested by analysis-of-variance (ANOVA) method to check their adequacy. Finally, a comparison is made between measured and calculated results, which are in good agreement. This indicates that the developed models can predict the responses adequately within the limits of welding parameters being used.

  2. 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.

  3. 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.

  4. 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

  5. Aircraft and ground vehicle friction correlation test results obtained under winter runway conditions during joint FAA/NASA Runway Friction Program

    NASA Technical Reports Server (NTRS)

    Yager, Thomas J.; Vogler, William A.; Baldasare, Paul

    1988-01-01

    Aircraft and ground vehicle friction data collected during the Joint FAA/NASA Runway Friction Program under winter runway conditions are discussed and test results are summarized. The relationship between the different ground vehicle friction measurements obtained on compacted snow- and ice-covered conditions is defined together with the correlation to aircraft tire friction performance under similar runway conditions.

  6. Effects of Different Filler Metals on the Mechanical Behaviors of GTA Welded AA7A52(T6)

    NASA Astrophysics Data System (ADS)

    Shu, Fengyuan; Lv, Yaohui; Liu, Yuxin; Lin, Jianjun; Sun, Zhe; Xu, Binshi; He, Peng

    2014-06-01

    ER4043, ER5356, and AA7A52 on behalf of the Al-Si, Al-Mg, and Al-Zn-Mg-based welding material, respectively, were chosen as the filler metal to weld AA7A52(T6) plates by GTAW. The variance in mechanical performances of the joints caused by the various filler materials was investigated with reference to the SEM and EDS test results for the weld seam and the fracture surface. Failure was found in the seam for all the welded joints. With regard to the joint obtained with ER4043 welding wire, the total elongation was limited by the brittle intergranular compound Mg2Si of which Mg was introduced by convection mass transfer. As for the other two welds, the content ratio of Zn and Mg was found to play the dominant role in deciding the mechanical properties of the intergranular Mg-Zn compounds which were responsible for the tensile behavior of the joints. The content ratio (wt.%) of beyond 2:1 gave birth to the strengthening phase MgZn2 leading to a ductile fracture. Cr in the seam obtained with AA7A52 filler metal was found to enhance the strength of the joint through isolated particles.

  7. Weld braze technique

    DOEpatents

    Kanne, Jr., William R. (Aiken, SC); Kelker, Jr., John W. (North Augusta, SC); Alexander, Robert J. (Aiken, SC)

    1982-01-01

    High-strength metal joints are formed by a combined weld-braze technique. A hollow cylindrical metal member is forced into an undersized counterbore in another metal member with a suitable braze metal disposed along the bottom of the counterbore. Force and current applied to the members in an evacuated chamber results in the concurrent formation of the weld along the sides of the counterbore and a braze along the bottom of the counterbore in one continuous operation.

  8. Welding and joining techniques.

    PubMed

    Chipperfield, F A; Dunkerton, S B

    2001-05-01

    There is a welding solution for most applications. As products must meet more stringent requirements or require more flexible processes to aid design or reduce cost, further improvements or totally new processes are likely to be developed. Quality control aspects are also becoming more important to meet regulation, and monitoring and control of welding processes and the standardised testing of joints will meet some if not all of these requirements. PMID:11521652

  9. Method for welding beryllium

    DOEpatents

    Dixon, R.D.; Smith, F.M.; O`Leary, R.F.

    1997-04-01

    A method is provided for joining beryllium pieces which comprises: depositing aluminum alloy on at least one beryllium surface; contacting that beryllium surface with at least one other beryllium surface; and welding the aluminum alloy coated beryllium surfaces together. The aluminum alloy may be deposited on the beryllium using gas metal arc welding. The aluminum alloy coated beryllium surfaces may be subjected to elevated temperatures and pressures to reduce porosity before welding the pieces together. The aluminum alloy coated beryllium surfaces may be machined into a desired welding joint configuration before welding. The beryllium may be an alloy of beryllium or a beryllium compound. The aluminum alloy may comprise aluminum and silicon. 9 figs.

  10. Method for welding beryllium

    SciTech Connect

    Dixon, R.D.; Smith, F.M.; O`Leary, R.F.

    1995-12-31

    A method is provided for joining beryllium pieces which comprises: depositing aluminum alloy on at least one beryllium surface; contacting that beryllium surface with at least one other beryllium surface; and welding the aluminum alloy coated beryllium surfaces together. The aluminum alloy may be deposited on the beryllium using gas metal arc welding. The aluminum alloy coated beryllium surfaces may be subjected to elevated temperatures and pressures to reduce porosity before welding the pieces together. The aluminum alloy coated beryllium surfaces may be machined into a desired welding joint configuration before welding. The beryllium may be an alloy of beryllium or a beryllium compound. The aluminum alloy may comprise aluminum and silicon. Beryllium parts made using this method can be used as structural components in aircraft, satellites and space applications.

  11. Effect of proof testing on the flaw growth characteristics of 304 stainless steel. [crack propagation in welded joints

    NASA Technical Reports Server (NTRS)

    Finger, R. W.

    1974-01-01

    The effects of proof overload frequency and magnitude on the cyclic crack growth rates of 304 stainless steel weldments were investigated. The welding procedure employed was typical of those used on over-the-road cryogenic vessels. Tests were conducted at room temperature with an overload ratio of 1.50 to determine the effect of overload frequency. Effect of overload magnitude was determined from tests where a room temperature overload was applied between blocks of 1000 cycles applied at 78 K (-320 F). The cyclic stress level used in all tests was typical of the nominal membrane stress generally encountered in full scale vessels. Test results indicate that judicious selection of proof overload frequency and magnitude can reduce crack growth rates for cyclic stress levels.

  12. Thermal stir welding apparatus

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey (Inventor)

    2011-01-01

    A welding method and apparatus are provided for forming a weld joint between first and second elements of a workpiece. The method includes heating the first and second elements to form an interface of material in a plasticized or melted state interface between the elements. The interface material is then allowed to cool to a plasticized state if previously in a melted state. The interface material, while in the plasticized state, is then mixed, for example, using a grinding/extruding process, to remove any dendritic-type weld microstructures introduced into the interface material during the heating process.

  13. Microstructure change in the interface of co2 laser welded zirconium alloys

    NASA Astrophysics Data System (ADS)

    Boutarek, N.; Azzougui, B.; Saidi, D.; Neggache, M.

    2009-11-01

    Welding is a joining procedure that offers some benefits over mechanical fasteners such as weight reduction and absence of notches induced by machining operations. CO2 laser beam welding with a continuous wave is a high energy density and low heat input process. The result of this is a small heat-affected zone (HAZ), which cools very rapidly with very little distortion, and a high depth-to-width ratio for the Welding is a necessary process during fabricating fuel rods and fuel assemblies with Zircaloy-4 cladding, and electron beam welding is one of the commonly- used method. In this work, the joining of zirconium alloys was attempted by laser beam welding. A 2 kW CO2 laser is used and the joints are obtained from similar materials, which are plates of Zircaloy-4 (2 mm thick). A series of zirconium alloys were welded and investigated in a tow-fold approach: (1) process optimisation: the laser processing parameters are optimized to obtain welds with minimum defects, and (2) material characterisation: weld microstructures were evaluated. The microstructure and the phases present in the resolidified zone of the laser -welded specimens were analyzed by optical and scanning electron microscopy, X-ray diffraction, and also by the realization of micro hardness diagrams. A particular attention was made to study the correlation between surface structure and mechanical behaviour.

  14. Numerical Simulation on Joining of Ceramics with Metal by Friction Welding Technique

    NASA Astrophysics Data System (ADS)

    Jesudoss Hynes, N. Rajesh; Nagaraj, P.; Basil, S. Joshua

    The joining of ceramic and metals can be done by different techniques such as ultrasonic joining, brazing, transient liquid phase diffusion bonding, and friction welding. Friction Welding is a solid state joining process that generates heat through mechanical friction between a moving workpiece and a stationary component. In this article, numerical simulation on thermal analysis of friction welded ceramic/metal joint has been carried out by using Finite Element Analysis (FEA) software. The finite element analysis helps in better understanding of the friction welding process of joining ceramics with metals and it is important to calculate temperature and stress fields during the welding process. Based on the obtained temperature distribution the graphs were plotted between the lengths of the joint corresponding to the temperatures. To increase the wettability, aluminium sheet was used as an interlayer. Hence, numerical simulation of friction welding process is done by varying the interlayer sheet thickness. Transient thermal analysis had been carried out for each cases and temperature distribution was studied. From the simulation studies, it is found that the increase in interlayer thickness reduces the heat affected zone and eventually improves the joint efficiency of alumina/aluminum alloy joints.

  15. Welds chilled by liquid coolant manifold

    NASA Technical Reports Server (NTRS)

    Odor, M. E.; Whiffen, E. E.

    1966-01-01

    Liquid coolant chill tool provides uniform cooling to materials adjacent to weld areas on long or contoured butt welds. This tool incorporates a manifold that clamps to the weld joint by vacuum and circulates liquid in direct contact with adjacent material.

  16. Evaluation of Microstructure and Mechanical Properties in Dissimilar Austenitic/Super Duplex Stainless Steel Joint

    NASA Astrophysics Data System (ADS)

    Rahmani, Mehdi; Eghlimi, Abbas; Shamanian, Morteza

    2014-10-01

    To study the effect of chemical composition on microstructural features and mechanical properties of dissimilar joints between super duplex and austenitic stainless steels, welding was attempted by gas tungsten arc welding process with a super duplex (ER2594) and an austenitic (ER309LMo) stainless steel filler metal. While the austenitic weld metal had vermicular delta ferrite within austenitic matrix, super duplex stainless steel was mainly comprised of allotriomorphic grain boundary and Widmanstätten side plate austenite morphologies in the ferrite matrix. Also the heat-affected zone of austenitic base metal comprised of large austenite grains with little amounts of ferrite, whereas a coarse-grained ferritic region was observed in the heat-affected zone of super duplex base metal. Although both welded joints showed acceptable mechanical properties, the hardness and impact strength of the weld metal produced using super duplex filler metal were found to be better than that obtained by austenitic filler metal.

  17. Laser welding of thermoplastic materials.

    PubMed

    Chipperfield, F A; Jones, I A

    2001-06-01

    The capabilities of the three main types of laser are compared and a new technique is introduced, which laser welds plastics using an infrared absorber to create a joint that is almost invisible to the human eye. PMID:11488201

  18. Properties of friction welds between 9Cr-ODS martensitic and ferritic martensitic steels

    NASA Astrophysics Data System (ADS)

    Uwaba, Tomoyuki; Ukai, Shigeharu; Nakai, Tatsuyoshi; Fujiwara, Masayuki

    2007-08-01

    Friction welding of oxide-dispersion-strengthened-steel (ODS) and ferritic-martensitic 11Cr-0.5Mo-2W, V, Nb steel (PNC-FMS) was examined to investigate the feasibility of the welding of this alloy combination. Forge pressure was varied in the welding test to investigate the effect on the soundness of the weld joint. Post-weld heat treatment was necessary for the weld joint because of quench hardening in the heat-affected zone in the as-welded condition. The welds were cross-sectioned and examined to determine their metallurgical structure, hardness and tensile strength. Since the heat treatment produced a softened zone near the weld interface, the furnace-cooling rate was investigated to determine the rate at which the softening did not occur. The weld joints were cold-rolled and the soundness of the weld interface was determined by tensile testing the cold-rolled weld joints.

  19. Friction Stir Spot Welding of DP780 Carbon Steel

    SciTech Connect

    Santella, Michael L [ORNL; Hovanski, Yuri [ORNL; Frederick, David Alan [ORNL; Grant, Glenn J [ORNL; Dahl, Michael E [ORNL

    2010-01-01

    Friction stir spot welds were made in uncoated and galvannealed DP780 sheets using polycrystalline boron nitride stir tools. The tools were plunged at either a single continuous rate or in two segments consisting of a relatively high rate followed by a slower rate of shorter depth. Welding times ranged from 1 to 10 s. Increasing tool rotation speed from 800 to 1600 rev min{sup -1} increased strength values. The 2-segment welding procedures also produced higher strength joints. Average lap shear strengths exceeding 10 {center_dot} 3 kN were consistently obtained in 4 s on both the uncoated and the galvannealed DP780. The likelihood of diffusion and mechanical interlocking contributing to bond formation was supported by metallographic examinations. A cost analysis based on spot welding in automobile assembly showed that for friction stir spot welding to be economically competitive with resistance spot welding the cost of stir tools must approach that of resistance spot welding electrode tips.

  20. Oil-Ash Corrosion Resistance of Dissimilar T22/T91 Welded Joint of Super Heater Tubes

    NASA Astrophysics Data System (ADS)

    Mittal, Rutash; Sidhu, Buta Singh

    2015-02-01

    The studies on the high temperature corrosion of the dissimilar metal weldment are necessary for longer service of the weldments in corrosive medium. This paper reports the performance of microstructurally different regions, namely heat-affected zone (HAZ), weld metal (WM), and base metal (BM) of dissimilar metal weldment of T22/T91 in the molten salt (Na2SO4-60%V2O5) environment under cyclic studies. The T22 HAZ, WM, and T91 HAZ were observed to oxidize at higher rates and develop more scale thickness than other regions in the weldment. Microstructures and elemental analysis indicate lesser availability of Cr in T22 HAZ and T91 HAZ due to formation of Cr-rich phases, which ultimately causes the difference in oxidation behavior of different regions. The presence of chromium carbides and intermetallics in un-oxidized T22 HAZ region and martensitic structure with the presence of delta ferrites in un-oxidized T91 HAZ region was observed to be the major cause behind the weak corrosion resistance of the respective HAZs. The higher oxidation rate of T22 HAZ may be attributed to the absence of protective scale of Cr2O3 and presence of Fe3O4 phases. Similarly higher oxidation rate of T91 HAZ region can be attributed to lesser availability of Cr due to the propensity of development of delta ferrite in martensitic structure.

  1. 30 CFR 18.98 - Enclosures, joints, and fastenings; pressure testing.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... false Enclosures, joints, and fastenings; pressure...18.98 Enclosures, joints, and fastenings; pressure...testing. (a) Cast or welded enclosures shall be...oscillograms. (c) Welded joints forming an enclosure...

  2. FURTHER PREDICTIONS ABOUT WELD METAL STRENGTH 6.1 INTRODUCTION

    E-print Network

    Cambridge, University of

    -1973 specifications. An ISO-2560 specification was used, since it is a joint geometry that leaves much of the weld analyses. Figure 6.1 illustrates the welding procedure used, and shows the macrostructure of "Weld6CHAPTER 6 FURTHER PREDICTIONS ABOUT WELD METAL STRENGTH 6.1 INTRODUCTION In general, when

  3. Electromagnetically and Thermally Driven Flow Phenomena in Electroslag Welding

    E-print Network

    Eagar, Thomas W.

    . Electroslag welding has been shown to produce rela- tively defect-free joints at fast deposition rates, with, that the size and shape of the weld pool are the controlling factors in the production of sound welds. While) Electromagnetically and Thermally Driven Flow Phenomena in Electroslag Welding A. H. DILAWARI, J

  4. Laser welding of bone: Successful in vitro experiments

    SciTech Connect

    Mourant, J.R.; Anderson, G.D.; Bigio, I.J.; Johnson, T.M.

    1994-02-01

    A method for ``welding`` bones is being developed. Tensile joint strengths of chicken bones welded in vitro have exceeded one kilogram. Welding was performed with either a Nd:YAG (1064 nm) or a diode laser (820 nm). Light was delivered with an optical fiber held a few millimeters from the bone surface. A solder was developed to assist in the welding process.

  5. Digital simulation of the friction stir welding process

    Microsoft Academic Search

    D. Lawrjaniec; A. Abisror; C. Decker; M. Kocak; J Dos Santos; S. Gardiner

    2004-01-01

    A recently developed welding process has proven to be well suited to making high strength aluminium alloy joints. This friction stir welding (FSW) process was invented and patented by The Welding Institute (TWI). The objective was to develop a means of simulating the process that could subsequently be used as a means of enhancing the design of these welded structures.

  6. Effects of friction stir welding on microstructure of 7075 aluminum

    Microsoft Academic Search

    C. G. Rhodes; M. W. Mahoney; W. H. Bingel; R. A. Spurling; C. C. Bampton

    1997-01-01

    Friction stir welding is a relatively new technique developed by The Welding Institute (TWI) for the joining of aluminum alloys. The technique, based on friction heating at the faying surfaces of two pieces to be joined, results in a joint created by interface deformation, heat, and solid-state diffusion. In evaluating friction stir welding, critical issues (beyond a sound joint) include

  7. Experimental Investigation into the Effects of Weld Sequence and Fixture on Residual Stresses in Arc Welding Process

    NASA Astrophysics Data System (ADS)

    Kohandehghan, A. R.; Serajzadeh, S.

    2012-06-01

    This study concentrates on the effects of weld sequence and welding fixtures on distribution and magnitude of induced arc welding residual stresses built up in butt-joint of Gas Tungsten Arc Welding (GTAW) AA5251 plates. Aluminum plates have been welded under different welding conditions and then, longitudinal and transverse residual stresses were measured in different points of the welded plates employing hole-drilling technique. The results indicate that welding sequence significantly alters the distributions of both longitudinal and transverse residual stresses while the changing in the weld sequence leads to 44% decrease in longitudinal residual stress. Besides, both the geometry of weld pool and distribution of residual stresses are affected by the welding fixtures while implementation of fixture causes about 21 and 76% reductions in the depth of weld pool and transverse residual stress, respectively, for the material and welding conditions used in this research.

  8. Welding arc plasma physics

    NASA Technical Reports Server (NTRS)

    Cain, Bruce L.

    1990-01-01

    The problems of weld quality control and weld process dependability continue to be relevant issues in modern metal welding technology. These become especially important for NASA missions which may require the assembly or repair of larger orbiting platforms using automatic welding techniques. To extend present welding technologies for such applications, NASA/MSFC's Materials and Processes Lab is developing physical models of the arc welding process with the goal of providing both a basis for improved design of weld control systems, and a better understanding of how arc welding variables influence final weld properties. The physics of the plasma arc discharge is reasonably well established in terms of transport processes occurring in the arc column itself, although recourse to sophisticated numerical treatments is normally required to obtain quantitative results. Unfortunately the rigor of these numerical computations often obscures the physics of the underlying model due to its inherent complexity. In contrast, this work has focused on a relatively simple physical model of the arc discharge to describe the gross features observed in welding arcs. Emphasis was placed of deriving analytic expressions for the voltage along the arc axis as a function of known or measurable arc parameters. The model retains the essential physics for a straight polarity, diffusion dominated free burning arc in argon, with major simplifications of collisionless sheaths and simple energy balances at the electrodes.

  9. Friction stir welding of aluminium casting alloys

    Microsoft Academic Search

    Damian Miara; Adam Pietras

    2012-01-01

    It has been presented the results of testing of friction stir welding quality in relation to EN AC-43200 (AK9) and EN AC-45000 (AK64) aluminium casting alloys. The test joints were made with the use of the welding machine constructed on the basis of numerically controlled milling machines. The assessment of the joints quality was made basing oneself on the visual

  10. Laser transmission welding of ABS: Effect of CNTs concentration and process parameters on material integrity and weld formation

    NASA Astrophysics Data System (ADS)

    Rodríguez-Vidal, E.; Quintana, I.; Gadea, C.

    2014-04-01

    This paper reports a study of the laser transmission welding of polymeric joints composed by two ABS (acrylonitrile/butadiene/styrene) sheets, one transparent (natural ABS) and the other absorbent (filled by different percentages of carbon nanotubes (CNTs)). The objective of this work is to analyze the effect of process parameters and CNTs concentrations on weld formation and mechanical resistance of the weld joints.

  11. Welding in Space Workshop

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.

    1990-01-01

    The potential was discussed for welding in space, its advantages and disadvantages, and what type of programs can benefit from the capability. Review of the various presentations and comments made in the course of the workshop suggests several routes to obtaining a better understanding of how welding processes can be used in NASA's initiatives in space. They are as follows: (1) development of a document identifying well processes and equipment requirements applicable to space and lunar environments; (2) more demonstrations of welding particular hardware which are to be used in the above environments, especially for space repair operations; (3) increased awareness among contractors responsible for building space equipment as to the potential for welding operations in space and on other planetary bodies; and (4) continuation of space welding research projects is important to maintain awareness within NASA that welding in space is viable and beneficial.

  12. Mössbauer characterization of joints of steel pieces in transient liquid phase bonding experiences

    NASA Astrophysics Data System (ADS)

    di Luozzo, N.; Martínez Stenger, P. F.; Canal, J. P.; Fontana, M. R.; Arcondo, B.

    2011-11-01

    Joining of seamless, low carbon, steel tubes were performed by means of Transient Liquid Phase Bonding process employing a foil of Fe-Si-B metallic glass as filler material. The influence of the main parameters of the process was evaluated: temperature, holding time, pressure and post weld heat treatment. Powder samples were obtained from the joint of tubes and characterized employing Mössbauer Spectroscopy in transmission geometry. The sampling was performed both in tubes successfully welded and in those which show joint defects. The results obtained are correlated with the obtained microstructure and the diffusion of Si and B during the process.

  13. Investigation of the fatigue behaviour of butt-welded joints treated by ultrasonic peening process and compared with fatigue life assessment standards

    Microsoft Academic Search

    G. R. Jinu; P. Sathiya; G. Ravichandran; A. Rathinam

    2009-01-01

    Ultrasonic peening is a technique to be used for improving the fatigue life of welded structures. The technique makes use\\u000a of an ultrasonically vibrated pin which is pressed against the toe regions of the weld. The beneficial effect is mainly due\\u000a to the introduction of favourable compressive stresses on weld toe regions, causing local plastic deformation and reducing\\u000a stress concentration

  14. Numerical Study for Gta Weld Shape Variation by Coupling Welding Arc and Weld Pool

    NASA Astrophysics Data System (ADS)

    Dong, Wenchao; Lu, Shanping; Li, Dianzhong; Li, Yiyi

    A numerical modeling of the welding arc and weld pool is studied for moving GTA welding to investigate the effect of the surface active element oxygen and the plasma drag force on the weld shape. Based on the 2D axisymmetric numerical modeling of the argon arc, the heat flux, current density and plasma drag force are obtained under different welding currents. Numerical calculations to the weld pool development are carried out for moving GTA welding on SUS304 stainless steel with different oxygen contents 30 ppm and 220 ppm, respectively. The results show that the plasma drag force is another dominating driving force affecting the liquid pool flow pattern, except for the Marangoni force. The different welding currents will change the temperature distribution and plasma drag force on the pool surface, and affect the strength of Marangoni convection and the weld shape. The weld D/W ratio initially increases, followed by a constant value around 0.5 with the increasing welding current under high oxygen content. The weld D/W ratio under the low oxygen content slightly decreases with the increasing welding current. The predicted weld shape by simulation agrees well with experimental results.

  15. Potential industrial application of laser welding with wire feed

    SciTech Connect

    Sun, Z. [Metalock Singapore Ltd., Singapore (Singapore); Moisio, T. [Lappeenranta Univ. of Technology (Finland)

    1996-12-31

    Laser welding with wire feed is a relative new technique which can widen the application of autogenous welding (without filler) in addition to retaining the many advantages of laser welding. The advantages of the technique compared with autogenous laser welding include the possibilities of modifying fusion zone chemistry, lessening joint fit-up requirement, and enhancing thick section welding with multipasses. This technique is particularly applicable to dissimilar metal welding due to the reduced mismatches of the base metals by the use of suitable filler material. Therefore, the technique has recently received more attention and is being evaluated for some industrial applications. In this paper, a case study is presented to illustrate the potential of the technique. Austenitic/ferritic dissimilar steel joints were laser welded with nickel-base filler wire. Although the philosophy of using nickel-base filler in this type of joints has been an established practice for conventional welding processes, its suitability in laser welding requires further investigation. Evaluation of the joints indicates that they possess improved weld quality as compared to autogenous laser welded joints. Some special advantages over conventional welding processes such as smaller heat-affected zone (HAZ), less distortion and lower residual stresses have also been demonstrated. It can be seen that this type of laser welded joints has potential future applications for several industrial sectors.

  16. Methods for reducing weld porosity in argon-shielded arc welding of aluminium alloys

    Microsoft Academic Search

    M. M. Shtrikman; A. V. Pinskii; A. A. Filatov; V. V. Koshkin; E. A. Mezentseva; N. V. Guk

    2011-01-01

    Cause analysis of porosity in aluminium argon-arc welded joints is carried out, particularly that of aluminium–lithium alloy 1424. Feasible production methods of reducing the quantity of voids in the joints are considered.

  17. Weld peaking on heavy aluminum structures

    NASA Technical Reports Server (NTRS)

    Bayless, E.; Poorman, R.; Sexton, J.

    1978-01-01

    Weld peaking is usually undesirable in any welded structure. In heavy structures, the forces involved in the welding process become very large and difficult to handle. With the shuttle's solid rocket booster, the weld peaking resulted in two major problems: (1) reduced mechanical properties across the weld joint, and (2) fit-up difficulties in subsequent assembly operation. Peaking from the weld shrinkage forces can be fairly well predicted in simple structures; however, in welding complicated assemblies, the amount of peaking is unpredictable because of unknown stresses from machining and forming, stresses induced by the fixturing, and stresses from welds in other parts of the assembly. When excessive peaking is encountered, it can be corrected using the shrinkage forces resulting from the welding process. Application of these forces is discussed in this report.

  18. Verifying root fusion in electron-beam welds

    NASA Technical Reports Server (NTRS)

    Becker, F. L.; Doctor, S.; Kleint, R. E.

    1980-01-01

    Ultrasonic equipment and x-y recorder indicate where back side of joint is properly welded. Wire waveguide placed in groove at root of joint to be welded is fused when joint is adequately penetrated. Ultransonic signal moving down waveguide is reflected where guide is melted. Change in reflected-signal arrival time with change in weld-head position is nearly constant unless joint is incompletely penetrated. Method permits determination of penetration depth in preweld samples without opening vacuum chamber and sectioning weld. Technique is particularly valuable when back side of joint is inaccessible.

  19. Solid state welding of dispersion-strengthened nickel alloys

    NASA Technical Reports Server (NTRS)

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

    1971-01-01

    Two-step solid state welding cycle applied to carefully prepared surfaces of an unrecrystallized alloy prevents loss of parent-metal strength at weld joint of dispersion-strengthened, nickel-chromium alloy.

  20. Spot-Welding Gun With Adjustable Pneumatic Spring

    NASA Technical Reports Server (NTRS)

    Burley, Richard K.

    1990-01-01

    Proposed spot-welding gun equipped with pneumatic spring, which could be bellows or piston and cylinder, exerts force independent of position along stroke. Applies accurate controlled force to joint welded, without precise positioning at critical position within stroke.

  1. FRICTION-STIR-LAP-WELDS OF AA6111 ALUMINUM ALLOY

    SciTech Connect

    Yadava, Manasij; Mishra, Rajiv S.; Chen, Y. L.; Gayden, X.; Grant, Glenn J.

    2007-01-09

    Lap joints of 1 mm thick AA6111 aluminum sheets were made by friction stir welding, using robotic and conventional machines. Welds were made for advancing as well as retreating side loading. Thinning in welds was quantified. Lap shear test of welds was conducted in as-welded and paint-baked conditions. Conventional machine welds showed less thinning and better strength than robotic machine welds. Process forces in conventional machine welding were higher. Paint bake treatment improved the weld strength; but the improvement varied with process parameters. Advancing side loaded welds achieved higher strength than the retreating side loaded welds. Fracture location was found to occur on the loaded side of the weld and along the thinning defect.

  2. Wire-Guide Manipulator For Automated Welding

    NASA Technical Reports Server (NTRS)

    Morris, Tim; White, Kevin; Gordon, Steve; Emerich, Dave; Richardson, Dave; Faulkner, Mike; Stafford, Dave; Mccutcheon, Kim; Neal, Ken; Milly, Pete

    1994-01-01

    Compact motor drive positions guide for welding filler wire. Drive part of automated wire feeder in partly or fully automated welding system. Drive unit contains three parallel subunits. Rotations of lead screws in three subunits coordinated to obtain desired motions in three degrees of freedom. Suitable for both variable-polarity plasma arc welding and gas/tungsten arc welding.

  3. Fiber laser welding of nickel based superalloy Inconel 625

    NASA Astrophysics Data System (ADS)

    Janicki, Damian M.

    2013-01-01

    The paper describes the application of single mode high power fiber laser (HPFL) for the welding of nickel based superalloy Inconel 625. Butt joints of Inconel 625 sheets 0,8 mm thick were laser welded without an additional material. The influence of laser welding parameters on weld quality and mechanical properties of test joints was studied. The quality and mechanical properties of the joints were determined by means of tensile and bending tests, and micro hardness tests, and also metallographic examinations. The results showed that a proper selection of laser welding parameters provides non-porous, fully-penetrated welds with the aspect ratio up to 2.0. The minimum heat input required to achieve full penetration butt welded joints with no defect was found to be 6 J/mm. The yield strength and ultimate tensile strength of the joints are essentially equivalent to that for the base material.

  4. Laser-roll welding of a dissimilar metal joint of low carbon steel to aluminium alloy using 2 kW fibre laser

    Microsoft Academic Search

    Hitoshi Ozaki; Muneharu Kutsuna

    2009-01-01

    Recently, lightening, speed-up and decreasing vibration of the transport vehicles have been discussed for improving of environmental problems. As one solution, the material hybrid concept using aluminum alloys and high strength steels has been proposed. Therefore, new welding processes by which these dissimilar materials can be joined in high reliability and productivity are demanded. Laser roll welding was developed for

  5. Role of the micro/macro structure of welds in crack nucleation and propagation in aerospace aluminum-lithium alloy

    NASA Technical Reports Server (NTRS)

    Talia, George E.

    1996-01-01

    Al-Li alloys offer the benefits of increased strength, elastic modulus and lower densities as compared to conventional aluminum alloys. Martin Marietta Laboratories has developed an Al-Li alloy designated 2195 which is designated for use in the cryogenic tanks of the space shuttle. The Variable Polarity Plasma Arc (VPPA) welding process is currently being used to produce these welds [1]. VPPA welding utilizes high temperature ionized gas (plasma) to transfer heat to the workpiece. An inert gas, such as Helium, is used to shield the active welding zone to prevent contamination of the molten base metal with surrounding reactive atmospheric gases. [1] In the Space Shuttle application, two passes of the arc are used to complete a butt-type weld. The pressure of the plasma stream is increased during the first pass to force the arc entirely through the material, a practice commonly referred to as keyholing. Molten metal forms on either side of the arc and surface tension draws this liquid together as the arc passes. 2319 Al alloy filler material may also be fed into the weld zone during this pass. During the second pass, the plasma stream pressure is reduced such that only partial penetration of the base material is obtained. Al 2319 filler material is added during this pass to yield a uniform, fully filled welded joint. This additional pass also acts to alter the grain structure of the weld zone to yield a higher strength joint.

  6. Welding I.

    ERIC Educational Resources Information Center

    Allegheny County Community Coll., Pittsburgh, PA.

    Instructional objectives and performance requirements are outlined in this course guide for Welding I, a performance-based course offered at the Community College of Allegheny County to introduce students to shielded arc welding procedures involving stringer beads, butt welds, and lap welds. After introductory material outlining course objectives,…

  7. Welding Curriculum.

    ERIC Educational Resources Information Center

    Alaska State Dept. of Education, Juneau. Div. of Adult and Vocational Education.

    This competency-based curriculum guide is a handbook for the development of welding trade programs. Based on a survey of Alaskan welding employers, it includes all competencies a student should acquire in such a welding program. The handbook stresses the importance of understanding the principles associated with the various elements of welding.…

  8. Welding IV.

    ERIC Educational Resources Information Center

    Allegheny County Community Coll., Pittsburgh, PA.

    Instructional objectives and performance requirements are outlined in this course guide for Welding IV, a competency-based course in advanced arc welding offered at the Community College of Allegheny County to provide students with proficiency in: (1) single vee groove welding using code specifications established by the American Welding Society…

  9. Diode laser welding of aluminum to steel

    SciTech Connect

    Santo, Loredana; Quadrini, Fabrizio; Trovalusci, Federica [University of Rome Tor Vergata, Department of Mechanical Engineering, Via del Politecnico 1, 00133 Rome (Italy)

    2011-05-04

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

  10. Optical-Fiber-Welding Machine

    NASA Technical Reports Server (NTRS)

    Goss, W. C.; Mann, W. A.; Goldstein, R.

    1985-01-01

    Technique yields joints with average transmissivity of 91.6 percent. Electric arc passed over butted fiber ends to melt them together. Maximum optical transmissivity of joint achieved with optimum choice of discharge current, translation speed, and axial compression of fibers. Practical welding machine enables delicate and tedious joining operation performed routinely.

  11. Inert-Gas Diffuser For Plasma Or Arc Welding

    NASA Technical Reports Server (NTRS)

    Gilbert, Jeffrey L.; Spencer, Carl N.; Hosking, Timothy J.

    1994-01-01

    Inert-gas diffuser provides protective gas cover for weld bead as it cools. Follows welding torch, maintaining continuous flow of argon over newly formed joint and prevents it from oxidizing. Helps to ensure welds of consistently high quality. Devised for plasma arc keyhole welding of plates of 0.25-in. or greater thickness, also used in tungsten/inert-gas and other plasma or arc welding processes.

  12. Welding, Bonding and Fastening, 1984

    NASA Technical Reports Server (NTRS)

    Buckley, J. D. (editor); Stein, B. A. (editor)

    1985-01-01

    A compilation of papers presented in a joint NASA, American Society for Metals, The George Washington University, American Welding Soceity, and Society of Manufacturing Engineers conference on Welding, Bonding, and Fastening at Langley Research Center, Hampton, VA, on October 23 to 25, 1984 is given. Papers were presented on technology developed in current research programs relevant to welding, bonding, and fastening of structural materials required in fabricating structures and mechanical systems used in the aerospace, hydrospace, and automotive industries. Topics covered in the conference included equipment, hardware and materials used when welding, brazing, and soldering, mechanical fastening, explosive welding, use of unique selected joining techniques, adhesives bonding, and nondestructive evaluation. A concept of the factory of the future was presented, followed by advanced welding techniques, automated equipment for welding, welding in a cryogenic atmosphere, blind fastening, stress corrosion resistant fasteners, fastening equipment, explosive welding of different configurations and materials, solid-state bonding, electron beam welding, new adhesives, effects of cryogenics on adhesives, and new techniques and equipment for adhesive bonding.

  13. Welding Penetration Control of Fixed Pipe in TIG Welding Using Fuzzy Inference System

    NASA Astrophysics Data System (ADS)

    Baskoro, Ario Sunar; Kabutomori, Masashi; Suga, Yasuo

    This paper presents a study on welding penetration control of fixed pipe in Tungsten Inert Gas (TIG) welding using fuzzy inference system. The welding penetration control is essential to the production quality welds with a specified geometry. For pipe welding using constant arc current and welding speed, the bead width becomes wider as the circumferential welding of small diameter pipes progresses. Having welded pipe in fixed position, obviously, the excessive arc current yields burn through of metals; in contrary, insufficient arc current produces imperfect welding. In order to avoid these errors and to obtain the uniform weld bead over the entire circumference of the pipe, the welding conditions should be controlled as the welding proceeds. This research studies the intelligent welding process of aluminum alloy pipe 6063S-T5 in fixed position using the AC welding machine. The monitoring system used a charge-coupled device (CCD) camera to monitor backside image of molten pool. The captured image was processed to recognize the edge of molten pool by image processing algorithm. Simulation of welding control using fuzzy inference system was constructed to simulate the welding control process. The simulation result shows that fuzzy controller was suitable for controlling the welding speed and appropriate to be implemented into the welding system. A series of experiments was conducted to evaluate the performance of the fuzzy controller. The experimental results show the effectiveness of the control system that is confirmed by sound welds.

  14. Laser welding and syncristallization techniques comparison: in vitro study.

    PubMed

    Fornaini, C; Merigo, E; Vescovi, P; Meleti, M; Nammour, S

    2012-01-01

    Background. Laser welding was first reported in 1967 and for many years it has been used in dental laboratories with several advantages versus the conventional technique. Authors described, in previous works, the possibility of using also chair-side Nd?:?YAG laser device (Fotona Fidelis III, ? = 1064?nm) for welding metallic parts of prosthetic appliances directly in the dental office, extra- and also intra-orally. Syncristallisation is a soldering technique based on the creation of an electric arc between two electrodes and used to connect implants to bars intra-orally. Aim. The aim of this study was to compare two different laser welding devices with a soldering machine, all of these used in prosthetic dentistry. Material and Methods. In-lab Nd?:?YAG laser welding (group A = 12 samples), chair-side Nd?:?YAG laser welding (group B = 12 samples), and electrowelder (group C = 12 samples) were used. The tests were performed on 36 CrCoMo plates and the analysis consisted in evaluation, by microscopic observation, of the number of fissures in welded areas of groups A and B and in measurement of the welding strength in all the groups. The results were statistically analysed by means of one-way ANOVA and Tukey-Kramer multiple comparison tests. Results. The means and standard deviations for the number of fissures in welded areas were 8.12 ± 2.59 for group A and 5.20 ± 1.38 for group B. The difference was statistical significant (P = 0.0023 at the level 95%). On the other hand, the means and standard deviations for the traction tests were 1185.50 ± 288.56?N for group A, 896.41 ± 120.84?N for group B, and 283.58 ± 84.98?N for group C. The difference was statistical significant (P = 0.01 at the level 95%). Conclusion. The joint obtained by welding devices had a significant higher strength compared with that obtained by the electrowelder, and the comparison between the two laser devices used demonstrated that the chair-side Nd?:?YAG, even giving a lower strength to the joints, produced the lowest number of fissures in the welded area. PMID:22778737

  15. Laser Welding and Syncristallization Techniques Comparison: In Vitro Study

    PubMed Central

    Fornaini, C.; Merigo, E.; Vescovi, P.; Meleti, M.; Nammour, S.

    2012-01-01

    Background. Laser welding was first reported in 1967 and for many years it has been used in dental laboratories with several advantages versus the conventional technique. Authors described, in previous works, the possibility of using also chair-side Nd?:?YAG laser device (Fotona Fidelis III, ? = 1064?nm) for welding metallic parts of prosthetic appliances directly in the dental office, extra- and also intra-orally. Syncristallisation is a soldering technique based on the creation of an electric arc between two electrodes and used to connect implants to bars intra-orally. Aim. The aim of this study was to compare two different laser welding devices with a soldering machine, all of these used in prosthetic dentistry. Material and Methods. In-lab Nd?:?YAG laser welding (group A = 12 samples), chair-side Nd?:?YAG laser welding (group B = 12 samples), and electrowelder (group C = 12 samples) were used. The tests were performed on 36 CrCoMo plates and the analysis consisted in evaluation, by microscopic observation, of the number of fissures in welded areas of groups A and B and in measurement of the welding strength in all the groups. The results were statistically analysed by means of one-way ANOVA and Tukey-Kramer multiple comparison tests. Results. The means and standard deviations for the number of fissures in welded areas were 8.12 ± 2.59 for group A and 5.20 ± 1.38 for group B. The difference was statistical significant (P = 0.0023 at the level 95%). On the other hand, the means and standard deviations for the traction tests were 1185.50 ± 288.56?N for group A, 896.41 ± 120.84?N for group B, and 283.58 ± 84.98?N for group C. The difference was statistical significant (P = 0.01 at the level 95%). Conclusion. The joint obtained by welding devices had a significant higher strength compared with that obtained by the electrowelder, and the comparison between the two laser devices used demonstrated that the chair-side Nd?:?YAG, even giving a lower strength to the joints, produced the lowest number of fissures in the welded area. PMID:22778737

  16. Investigation into Microstructures of Maraging Steel 250 Weldments and Effect of Post-Weld Heat Treatments

    NASA Astrophysics Data System (ADS)

    Tariq, Fawad; Baloch, Rasheed Ahmed; Ahmed, Bilal; Naz, Nausheen

    2010-03-01

    This study was undertaken to gain a better understanding of microstructures obtained by multipass gas tungsten arc welding in maraging steel grade 250. Metallography and microhardness measurements were carried out on sheet and welded joints in as-welded and post-weld aged conditions. It was found that there was a significant amount of reverted austenite formed on cell boundaries of weld metal after aging at 758-823 K for 3-5 h, and was stable at room temperature. Aging at higher temperatures led to an increase in the continuous network of patchy austenite along the cell boundaries. The reason for the above, in our opinion, is the concentrational heterogeneity which characterizes the microstructure of maraging steel welds. No reverted austenite was observed in as-welded specimens. Solution annealing at 1093 K for 1 h did not completely eliminate the chemical heterogeneity associated with weld structures. However, homogenizing at 1373 K produced homogenous structure that on subsequent aging produces austenite-free lath martensitic structure.

  17. Structure and mechanical properties of 1570C alloy welds produced by friction stir welding

    NASA Astrophysics Data System (ADS)

    Malopheyev, S. S.; Kulitskiy, V. A.

    2012-09-01

    The effect of the conditions of friction stir welding (FSW) of 1570C aluminum alloy sheets on the structure and mechanical properties of the welded joints is studied. A recrystallized fine-grained structure with a grain size changing with the rate of welding tool rotation forms in a weld during FSW. As compared to the base metal, the yield strength of the weld metal decreases by 9-22% depending on the rate of welding tool rotation, and the ultimate tensile strength is almost independent of the FSW conditions and accounts for ˜90% of the ultimate tensile strength of the base metal. The plasticity of the weld metal is >13% for all rates of welding tool rotation. The microstructure and mechanical properties of the weld zone are discussed.

  18. Experimental and Numerical Investigation of an Electromagnetic Weld Pool Control for Laser Beam Welding

    NASA Astrophysics Data System (ADS)

    Bachmann, M.; Avilov, V.; Gumenyuk, A.; Rethmeier, M.

    The objective of this study was to investigate the influence of externally applied magnetic fields on the weld quality in laser beam welding. The optimization of the process parameters was performed using the results of computer simulations. Welding tests were performed with up to 20 kW laser beam power. It was shown that the AC magnet with 3 kW power supply allows for a prevention of the gravity drop-out for full penetration welding of 20 mm thick stainless steel plates. For partial penetration welding it was shown that an0.5 T DC magnetic field is enough for a suppression of convective flows in the weld pool. Partial penetration welding tests with 4 kW beam power showed that the application of AC magnetic fields can reduce weld porosity by a factor of 10 compared to the reference joints. The weld surface roughness was improved by 50%.

  19. Advances in welding science - a perspective

    SciTech Connect

    David, S.A.; Vitek, J.M. [Oak Ridge National Lab., TN (United States); Babu, S.S.; DebRoy, T. [Pennsylvania State Univ., University Park, PA (United States)

    1995-02-01

    The ultimate goal of welding technology is to improve the joint integrity and increase productivity. Over the years, welding has been more of an art than a science, but in the last few decades major advances have taken place in welding science and technology. With the development of new methodologies at the crossroads of basic and applied sciences, enormous opportunities and potential exist to develop a science-based tailoring of composition, structure, and properties of welds with intelligent control and automation of the welding processes.

  20. Microstructural analysis of solar cell welds

    NASA Technical Reports Server (NTRS)

    Moore, T. J.; Watson, G. K.; Baraona, C. R.

    1982-01-01

    Parallel-gap resistance welding of silicon solar cells with copper interconnects results in complex microstructural variations that depend on the welding variables. At relatively low heat input solid-state welds are produced. At medium heat the Ag-Cu eutectic forms resulting in a braze joint. High heat produces a fusion weld with complete melting of the silver layer on the silicon solar cell. If the silicon is also melted, cracking occurs in the silicon cell below the weld nugget. These determinations were made using light microscopy, microprobe, and scanning electron microscopy analyses.

  1. Laser Welding in Space

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.; Kaukler, William F.

    1989-01-01

    Solidification type welding process experiments in conditions of microgravity were performed. The role of convection in such phenomena was examined and convective effects in the small volumes obtained in the laser weld zone were observed. Heat transfer within the weld was affected by acceleration level as indicated by the resulting microstructure changes in low gravity. All experiments were performed such that both high and low gravity welds occurred along the same weld beam, allowing the effects of gravity alone to be examined. Results indicate that laser welding in a space environment is feasible and can be safely performed IVA or EVA. Development of the hardware to perform the experiment in a Hitchhiker-g platform is recomended as the next step. This experiment provides NASA with a capable technology for welding needs in space. The resources required to perform this experiment aboard a Shuttle Hitchhiker-pallet are assessed. Over the four year period 1991 to 1994, it is recommended that the task will require 13.6 manyears and $914,900. In addition to demonstrating the technology and ferreting out the problems encountered, it is suggested that NASA will also have a useful laser materials processing facility for working with both the scientific and the engineering aspects of materials processing in space. Several concepts are also included for long-term optimization of available solar power through solar pumping solid state lasers directly for welding power.

  2. Damage Tolerance Assessment of Friction Pull Plug Welds

    NASA Technical Reports Server (NTRS)

    McGill, Preston; Burkholder, Jonathan

    2012-01-01

    Friction stir welding is a solid state welding process developed and patented by The Welding Institute in Cambridge, England. Friction stir welding has been implemented in the aerospace industry in the fabrication of longitudinal welds in pressurized cryogenic propellant tanks. As the industry looks to implement friction stir welding in circumferential welds in pressurized cryogenic propellant tanks, techniques to close out the termination hole associated with retracting the pin tool are being evaluated. Friction pull plug welding is under development as a one means of closing out the termination hole. A friction pull plug weld placed in a friction stir weld results in a non-homogenous weld joint where the initial weld, plug weld, their respective heat affected zones and the base metal all interact. The welded joint is a composite, plastically deformed material system with a complex residual stress field. In order to address damage tolerance concerns associated with friction plug welds in safety critical structures, such as propellant tanks, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size in the test or service environments. Test data relating residual strength capability to flaw size in two aluminum alloy friction plug weld configurations is presented.

  3. A Study on the Welding Characteristics of Tailor Welded Blank Metal Sheets Using GTAW and Laser Welding

    NASA Astrophysics Data System (ADS)

    Thasanaraphan, Pornsak

    In this study, a computational and experimental effort was carried out to qualitatively understand the weld pool shape, distortion and residual stress for continuous laser welding and manual pulsed gas metal arc welding. For all the welding simulations given in this dissertation, a welding specific finite element package, SYSWELD, is used. This research focuses on the welding behavior observed in light-weight metal structures known as the tailor-welded blanks, TWBs. They are a combination of two or more metal sheets with different thickness and/or different materials that are welded together in a single plane prior to forming, e.g., stamping. They made from the low carbon steel. As laser welding experiment results show, the weld pool shape at the top and bottom surface, is strongly influenced by surface tension, giving it a characteristic hourglass shape. In order to simulate the hourglass shape, a new volumetric heat source model was developed to predict the transient temperature profile and weld pool shape, including the effect of surface tension. Tailor welded blanks with different thicknesses were examined in the laser welding process. All major physical phenomena such as thermal conduction, heat radiation and convection heat losses are taken into account in the model development as well as temperature-dependant thermal and mechanical material properties. The model is validated for the case of butt joint welding of cold rolled steel sheets. The results of the numerical simulations provide temperature distributions representing the shape of the molten pool, distortion and residual stress with varying laser beam power and welding speed. It is demonstrated that the finite element simulation results are in good agreement with the experiment results. This includes the weld pool shape and sheet metal distortion. While there is no experimental data to compare directly with residual stress results, the distorted shape provides an indirect measure of the welding residual stresses. The welding details such as clamping, butt joint configuration, material, sample thickness are similar for both the laser welding process and the manual pulsed GTAW process. Also as same metallurgical investigation, the weld pool shape displays wider full penetration without the effect of surface tension. The double ellipsoid volumetric heat source is applied in the finite element simulation to determine the temperature distribution, distortion and residual stress. The simulation results are compared with the experimental results and show good agreement. In addition, the results from the laser welding process are compared to the equivalent results from the GTAW process in the order to better understand the fundamental differences between these two welding processes.

  4. Development of automated welding process for field fabrication of thick walled pressure vessels. Fourth quarter, FY 1980

    SciTech Connect

    Not Available

    1980-12-19

    Progress is reported in research on the automated welding of heavy steel plate for the fabrication of pressure vessels. Information is included on: torch and shield adaptation; mechanical control of the welding process; welding parameters; joint design; filler wire optimizaton; nondestructive testing of welds; and weld repair. (LCL)

  5. Solid-state and fusion resistance spot welding of TD-NiCr sheet

    NASA Technical Reports Server (NTRS)

    Moore, T. J.

    1973-01-01

    By using specially processed TD-NiCr sheet in both 0.4-mm (0.015-in.) and 1.6-mm (0.062-in.) thicknesses and carefully selected welding procedures, solid state resistance spot welds were produced which, after postheating at 1200 C, were indistinguishable from the parent material. Stress-rupture shear tests of single-spot lap joints in 0.4-mm (0.015-in.) thick sheet showed that these welds were as strong as the parent material. Similar results were obtained in tensile-shear tests at room temperature and 1100 C and in fatigue tests. Conventional fusion spot welds in commercial sheet were unsatisfactory because of poor stress-rupture shear properties resulting from metallurgical damage to the parent material.

  6. Three-Dimensional Visualization of Material Flow During Friction Stir Welding of Steel and Aluminum

    NASA Astrophysics Data System (ADS)

    Morisada, Yoshiaki; Imaizumi, Takuya; Fujii, Hidetoshi; Matsushita, Muneo; Ikeda, Rinsei

    2014-11-01

    Material flow is a key phenomenon to obtain sound joints by friction stir welding (FSW), and it is highly dependent of the welded material. It is well known that the optimal FSW condition depends on the welded material. However, the material flow during FSW has not been totally clarified in spite of many researches. Especially, the material flow of steel during FSW is still unclear. It seems difficult to understand the material flow by the traditional method such as the tracer method or observation of the microstructure in the stir zone. Therefore, in this study, the material flow of steel was three dimensionally visualized by x-ray radiography using two pairs of x-ray transmission real-time imaging systems, and was then compared with the material flow of aluminum. The result revealed the effect of the welded material on the material flow during FSW.

  7. Welding Technician

    ERIC Educational Resources Information Center

    Smith, Ken

    2009-01-01

    About 95% of all manufactured goods in this country are welded or joined in some way. These welded products range in nature from bicycle handlebars and skyscrapers to bridges and race cars. The author discusses what students need to know about careers for welding technicians--wages, responsibilities, skills needed, career advancement…

  8. Interfacial structure of the joints between magnesium alloy and mild steel with nickel as interlayer by hybrid laser-TIG welding

    Microsoft Academic Search

    Xiaodong Qi; Gang Song

    2010-01-01

    The joint interface of Mg alloy to steel with Ni interlayer was investigated. Comparing with that without any interlayer, the joint shear strength was improved significantly. The characterization of interfaces in the joint with Ni interlayer was analyzed and discussed. The results show that the formation of intermetallic compound Mg2Ni and solid solution of Ni in Fe at the interface

  9. Laser assisted non-consumable arc welding process development

    SciTech Connect

    Fuerschach, P.W.; Hooper, F.M.

    1997-09-01

    The employment of Laser Beam Welding (LBW) for many traditional arc welding applications is often limited by the inability of LBW to compensate for variations in the weld joint gap. This limitation is associated with fluctuations in the energy transfer efficiency along the weld joint. Since coupling of the laser beam to the workpiece is dependent on the maintenance of a stable absorption keyhole, perturbations to the weld pool can lead to decreased energy transfer and resultant weld defects. Because energy transfer in arc welding does not similarly depend on weld pool geometry, it is expected that combining these two processes together will lead to an enhanced fusion welding process that exhibits the advantages of both arc welding and LBW. Laser assisted non-consumable arc welds have been made on thin section aluminum. The welds combine the advantages of arc welding and laser welding, with enhanced penetration and fusion zone size. The use of a pulsed Nd:YAG laser with the combined process appears to be advantageous since this laser is effective in removing the aluminum oxide and thereby allowing operation with the tungsten electrode negative. The arc appears to increase the size of the weld and also to mitigate hot cracking tendencies that are common with the pulsed Nd:YAG laser.

  10. SmartWeld working session for the GTS4

    SciTech Connect

    Kleban, S. [Sandia National Labs., Albuquerque, NM (United States); Hicken, K.; Ng, R. [Sandia National Labs., Livermore, CA (United States); Fricke, B. [Allied Signal Kansas City Division, MO (United States)

    1997-08-01

    Results from SmartWeld`s first working session involving in-progress designs is presented. The Welding Advisor component of SmartWeld was thoroughly exercised, evaluated all eleven welds of the selected part. The Welding Advisor is an expert system implemented with object-oriented techniques for knowledge representation. With two welding engineers in attendance, the recommendations of the Welding Advisor were thoroughly examined and critiqued for accuracy and for areas of improvement throughout the working session. The Weld Schedule Database component of SmartWeld was also exercised. It is a historical archive of proven, successful weld schedules that can be intelligently searched using the current context of SmartWeld`s problem solving state. On all eleven welds, the experts agreed that Welding Advisor recommended the most risk free options. As a result of the Advisor`s recommendation, six welds agreed completely with the experts, two welds had their joint geometry modified for production, and three welds were not modified but extra care was exercised during welding. 25 figs., 3 tabs.

  11. Integration of NASA-sponsored studies on aluminum welding

    NASA Technical Reports Server (NTRS)

    Masubuchi, K.

    1972-01-01

    The results are presented of numerous studies relating to aluminum alloy welding. The subjects covered include: (1) effects of porosity on weld joint performance, (2) sources of porosity, (3) weld thermal effects, (4) residual stresses and distortion, and (5) manufacturing process system control.

  12. Identification of Damaged Spot Welds in a Complicated Joined Structure

    NASA Astrophysics Data System (ADS)

    Yunus, M. A.; Rani, M. N. Abdul; Ouyang, H.; Deng, H.; James, S.

    2011-07-01

    In automotive engineering, spot welds on assembled structures such as Body in White (BiW) have a significant effect on the vehicles' dynamic characteristics. Understandably, imperfections in the spot welds will cause variations in the dynamic properties such as natural frequencies and mode shapes of the structure. In this paper, a complicated welded structure which is a simplified Natural Gas Vehicle (NGV) platform is investigated. The structure fabricated from thin metal sheets consists of ten components. They are jointed together by a number of scattered spot welds. NASTRAN Solution 200 based on sensitivity analysis is used to identify the most sensitive parameters to natural frequencies. The numerical model of the undamaged structure is initially updated in order to minimise the discrepancies between the measured and numerical data using NASTRAN optimisation code. The initial updated model serves as a benchmark for the subsequent structural damage identification. The numerical data of the benchmark model is then compared with the measured data obtained from the damaged structure. The same updating procedure is applied to the benchmark model in order to bring the numerical data as close as possible to the measured data of the damaged structure. The disparity in certain parameter values from the parameter values used in the benchmark model shows a fault or damage in the location of a particular joint, depending on the severity of this disparity. The challenge in this work is to localise damaged area and quantify the damage of the complicated structure with multiple spot welds in the presence of uncertainty in the location and material properties of the welds.

  13. Economical Joint for Truss Structures

    NASA Technical Reports Server (NTRS)

    Moore, Carleton J.

    1987-01-01

    Mass-produced flat parts easily assembled. Joint for three-dimensional truss made of simple die-cutplates and inexpensive fasteners. Each truss joint consists of two identical interlocking plates bolted, welded, or glued together. Truss struts bolted to joint through holes in plate. Alternatively, ends of struts forked so that they slip over plates and fastened to them by bolts or pins.

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

    NASA Astrophysics Data System (ADS)

    Pal, Kamal; Pal, Surjya K.

    2011-08-01

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

  15. Dissimilar Joining of Zircaloy-4 to Type 304L Stainless Steel by Friction Welding Process

    NASA Astrophysics Data System (ADS)

    Ravi Shankar, A.; Suresh Babu, S.; Ashfaq, Mohammed; Kamachi Mudali, U.; Prasad Rao, K.; Saibaba, N.; Raj, Baldev

    2009-12-01

    Zirconium- and titanium-based dissolver vessels containing highly radioactive and concentrated corrosive nitric acid solution needs to be joined to the rest of fuel reprocessing plant made of AISI type 304L stainless steel (SS), which demands high integrity and corrosion resistant dissimilar joints. Solid-state joining process of friction welding was proposed in the present work to join zircaloy-4 and type 304L SS since fusion welding processes produce brittle intermetallic precipitates at the interface which reduce the mechanical strength as well as the corrosion resistance of the joint. The present study attempts to optimize joining parameters, without and with thin Ta and Ni interlayers that can prevent brittle intermetallic formation. Tensile test, three-point bend test, and microhardness measurements were performed on the joints. Characterization techniques such as optical microscopy, scanning electron microscopy (SEM), and x-ray diffraction (XRD) were employed. A good friction weld joint of zircaloy-4 to 304L SS was achieved with the joint strength (~540 MPa) greater than that of the base of zircaloy-4, without using any interlayer. A bend ductility of 5° was only obtained without using any interlayer. However, XRD patterns indicated the presence of intermetallics in the friction-welded joints without interlayers. Corrosion test carried out on zircaloy-4 to 304L SS friction joint in boiling 11.5 M nitric acid exhibited corrosion rate of 225 ?m/year after 240 h. SEM examination of the corroded joint indicated severe intergranular corrosion attack over stainless steel and preferential dissolution at the interface.

  16. Effect of Weld Tool Geometry on Friction Stir Welded AA2219-T87 Properties

    NASA Technical Reports Server (NTRS)

    Querin, Joseph A.; Schneider, Judy A.

    2008-01-01

    In this study, flat panels of AA2219-T87 were friction stir welded (FSWed) using weld tools with tapered pins The three pin geometries of the weld tools included: 0 (straight cylinder), 30 , and 60 angles on the frustum. For each weld tool geometry, the FSW process parameters were optimized to eliminate defects. A constant heat input was maintained while varying the process parameters of spindle rpm and travel speed. This provided a constant heat input for each FSW weld panel while altering the hot working conditions imparted to the workpiece. The resulting mechanical properties were evaluated from tensile test results of the FSW joint.

  17. Aligning Plasma-Arc Welding Oscillations

    NASA Technical Reports Server (NTRS)

    Norris, Jeff; Fairley, Mike

    1989-01-01

    Tool aids in alignment of oscillator probe on variable-polarity plasma-arc welding torch. Probe magnetically pulls arc from side to side as it moves along joint. Tensile strength of joint depends on alignment of weld bead and on alignment of probe. Operator installs new tool on front of torch body, levels it with built-in bubble glass, inserts probe in slot on tool, and locks probe in place. Procedure faster and easier and resulting alignment more accurate and repeatable.

  18. Matrix penetration in the bulk:In uence of humidity: Morphological analysis of wood welding

    E-print Network

    Dalang, Robert C.

    in plastic and metal industry[1] . Wood welding allows bonding strength similar to glued joints. However, dueMatrix penetration in the bulk:In uence of humidity: Morphological analysis of wood welding.pichelin@b .ch Context: Wood can be welded using linear vibration welding tech- niques similar to the ones

  19. Solid-state and fusion resistance spot welding of TD-NiCr sheet

    Microsoft Academic Search

    1974-01-01

    Four welding schedules were evaluated using convertional resistance ; welding equipment. Both specially processed (unrecrystallized) and commercial TD-; - NiCr sheet (0.4 mm thick) were used. Welding parameters were selected in order ; to produce both solid state and fusion resistance spot welds. All mechanical ; tests of the weldments were conducted using a single-spot lap joint specimen ; after

  20. 46 CFR 154.182 - Contiguous hull structure: Production weld test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...barrier, each 100m (328 ft.) of full penetration butt welded joints in that portion of the contiguous hull structure must...production weld tests in the position that the joint is welded: (a) Bend tests under § 57.06-4 of this...

  1. 46 CFR 154.182 - Contiguous hull structure: Production weld test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...barrier, each 100m (328 ft.) of full penetration butt welded joints in that portion of the contiguous hull structure must...production weld tests in the position that the joint is welded: (a) Bend tests under § 57.06-4 of this...

  2. Temperature and density distribution in mechanical vibration wood welding

    Microsoft Academic Search

    C. Ganne-Chedeville; J. M. Leban; M. Properzi; F. Pichelin; A. Pizzi

    2006-01-01

    Nondestructive evaluation of wood joints welded by linear vibration welding was performed with an infrared (IR) thermography\\u000a technique, which allowed the maximal and average peak temperature profile\\/distribution to be measured. The density profile\\/distribution\\u000a at the joint interface was measured by X-ray microdensitometry. The results show that the width of the welded zone also varies\\u000a as a function of the maximum

  3. Laser welding of aluminum alloys

    SciTech Connect

    Leong, K.H.; Sabo, K.R.; Sanders, P.G. [Argonne National Lab., IL (United States). Technology Development Div.; Spawr, W.J.

    1997-03-01

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

  4. Ultrasonic evaluation of solid-state welds

    Microsoft Academic Search

    Graham H. Thomas; Jay R. Spingarn

    1988-01-01

    Ultrasonic techniques for evaluating the quality of solid-state weld interfaces have been investigated over the past several years. Promising results have been obtained on a variety of solid-state welds by extracting features from the ultrasonic wave forms and applying pattern recognition algorithms to separate acceptable from unacceptable welds. The general conclusion is that the ultrasonic features most sensitive to interfacial

  5. Characterization of Friction Stir Welded Tubes by Means of Tube Bulge Test

    SciTech Connect

    D'Urso, G.; Longo, M.; Giardini, C. [University of Bergamo-Dept. of Design and Technologies-Italy-Viale Marconi 5, 24044 Dalmine (Italy)

    2011-05-04

    Mechanical properties of friction stir welded joints are generally evaluated by means of conventional tensile test. This testing method might provide insufficient information because maximum strain obtained in tensile test before necking is small; moreover, the application of tensile test is limited when the joint path is not linear or even when the welds are executed on curved surfaces. Therefore, in some cases, it would be preferable to obtain the joints properties from other testing methods. Tube bulge test can be a valid solution for testing circumferential or longitudinal welds executed on tubular workpieces. The present work investigates the mechanical properties and the formability of friction stir welded tubes by means of tube bulge tests. The experimental campaign was performed on tubular specimens having a thickness of 3 mm and an external diameter of 40 mm, obtained starting from two semi-tubes longitudinally friction stir welded. The first step, regarding the fabrication of tubes, was performed combining a conventional forming process and friction stir welding. Sheets in Al-Mg-Si-Cu alloy AA6060 T6 were adopted for this purpose. Plates having a dimension of 225x60 mm were bent (with a bending axis parallel to the main dimension) in order to obtain semi-tubes. A particular care was devoted to the fabrication of forming devices (punch and die) in order to minimize the springback effects. Semi-tubes were then friction stir welded by means of a CNC machine tool. Some preliminary tests were carried out by varying the welding parameters, namely feed rate and rotational speed. A very simple tool having flat shoulder and cylindrical pin was used. The second step of the research was based on testing the welded tubes by means of tube bulge test. A specific equipment having axial actuators with a conical shape was adopted for this study. Some analyses were carried out on the tubes bulged up to a certain pressure level. In particular, the burst pressure and the wall thickness were measured for each tested tube.

  6. Characterization of Friction Stir Welded Tubes by Means of Tube Bulge Test

    NASA Astrophysics Data System (ADS)

    D'Urso, G.; Longo, M.; Giardini, C.

    2011-05-01

    Mechanical properties of friction stir welded joints are generally evaluated by means of conventional tensile test. This testing method might provide insufficient information because maximum strain obtained in tensile test before necking is small; moreover, the application of tensile test is limited when the joint path is not linear or even when the welds are executed on curved surfaces. Therefore, in some cases, it would be preferable to obtain the joints properties from other testing methods. Tube bulge test can be a valid solution for testing circumferential or longitudinal welds executed on tubular workpieces. The present work investigates the mechanical properties and the formability of friction stir welded tubes by means of tube bulge tests. The experimental campaign was performed on tubular specimens having a thickness of 3 mm and an external diameter of 40 mm, obtained starting from two semi-tubes longitudinally friction stir welded. The first step, regarding the fabrication of tubes, was performed combining a conventional forming process and friction stir welding. Sheets in Al-Mg-Si-Cu alloy AA6060 T6 were adopted for this purpose. Plates having a dimension of 225×60 mm were bent (with a bending axis parallel to the main dimension) in order to obtain semi-tubes. A particular care was devoted to the fabrication of forming devices (punch and die) in order to minimize the springback effects. Semi-tubes were then friction stir welded by means of a CNC machine tool. Some preliminary tests were carried out by varying the welding parameters, namely feed rate and rotational speed. A very simple tool having flat shoulder and cylindrical pin was used. The second step of the research was based on testing the welded tubes by means of tube bulge test. A specific equipment having axial actuators with a conical shape was adopted for this study. Some analyses were carried out on the tubes bulged up to a certain pressure level. In particular, the burst pressure and the wall thickness were measured for each tested tube.

  7. Soldadura (Welding). Spanish Translations for Welding.

    ERIC Educational Resources Information Center

    Hohhertz, Durwin

    Thirty transparency masters with Spanish subtitles for key words are provided for a welding/general mechanical repair course. The transparency masters are on such topics as oxyacetylene welding; oxyacetylene welding equipment; welding safety; different types of welds; braze welding; cutting torches; cutting with a torch; protective equipment; arc…

  8. In-process weld sampling during hot end welds of type W overpacks

    SciTech Connect

    Barnes, G.A.

    1998-08-27

    Establish the criteria and process controls to be used in obtaining, testing, and evaluating in-process weld sample during the hot end welding of Type W Overpack capsules used to overpack CsCl capsules for storage at WESF.

  9. Development of Simplified Ultrasonic CT System for Imaging of Weld Metal and It's Comparison with TOFD Method

    NASA Astrophysics Data System (ADS)

    Kim, Kyung-Cho; Fukuhara, Hiroaki; Yamawaki, Hisashi

    In this paper, as a new measurement method to estimate the structure change of weld metal, the simplified ultrasonic CT system, which uses the information of three directions, that is, 90°, +45° and -45° about inspection plane is developed. Use of simplified ultrasonic CT system has two merits: Firstly, the measurement time is very short comparing with general CT. Secondly, it can detect sensitively very infinitesimal defect in vertical or slant direction about inspection plane because the obtained image is not C scan image but CT image calculated from three directions. From these merits, this method can be considered as a very effective method for the evaluation of material condition. In order to compare the performance of simplified ultrasonic CT, the CT image obtained from several specimens with several simple defects was compared with the D scan image obtained by TOFD (Time of Flight Diffraction) method. We can see simple defects more clearly by new proposed method. Experimental results on several kinds of specimen, having welded joint by electron beam welding, welded joint by electron beam welding and fatigue crack showed that the obtained C scan or CT image has better resolution than the D scan image by TOFD method and shows similar image to actual shape.

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

    NASA Astrophysics Data System (ADS)

    Shanmugarajan, B.; Padmanabham, G.

    2012-11-01

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

  11. Laser welding of discontinuously reinforced composite materials

    NASA Astrophysics Data System (ADS)

    Shiganov, I. N.

    1999-01-01

    The features of metal composite materials fusion welding are examined and the main defects arising at argon-arc, electron-beam and laser welding of alloys Al-Be-Mg, Fe-Cu-Pb and Al-Pb are revealed. The defects formation mechanisms are indicated and technological welding methods of metal composite materials are developed. These methods allow to prevent defects formation and obtain the welds with required mechanical properties and quality.

  12. Tube-to-header joint for bimetallic construction

    NASA Technical Reports Server (NTRS)

    Lessmann, G. G.; Stoner, D. R.

    1967-01-01

    Design advantages of bimetallic construction enables an all-welded bimetallic joint to be made from the accessible header side of the tube-to-header joint. In the two-piece header design the weld joints completely seal the tube-header plate crevice and prevent crevice and stringer corrosion.

  13. Plasma arc welding weld imaging

    NASA Technical Reports Server (NTRS)

    Rybicki, Daniel J. (inventor); Mcgee, William F. (inventor)

    1994-01-01

    A welding torch for plasma arc welding apparatus has a transparent shield cup disposed about the constricting nozzle, the cup including a small outwardly extending polished lip. A guide tube extends externally of the torch and has a free end adjacent to the lip. First and second optical fiber bundle assemblies are supported within the guide tube. Light from a strobe light is transmitted along one of the assemblies to the free end and through the lip onto the weld site. A lens is positioned in the guide tube adjacent to the second assembly and focuses images of the weld site onto the end of the fiber bundle of the second assembly and these images are transmitted along the second assembly to a video camera so that the weld site may be viewed continuously for monitoring the welding process.

  14. Investigation and control of factors influencing resistance upset butt welding

    Microsoft Academic Search

    N. F. H. Kerstens

    2010-01-01

    The purpose of this work is to investigate the factors influencing the resistance upset butt welding process to obtain an understanding of the metal behaviour and welding process characteristics, so that new automotive steels can be welded with reduced development time and fewer failures in production. In principle the welding process is rather simple, the materials to be\\u000ajoined are

  15. Modeling of the Weld Shape Development During the Autogenous Welding Process by Coupling Welding Arc with Weld Pool

    NASA Astrophysics Data System (ADS)

    Dong, Wenchao; Lu, Shanping; Li, Dianzhong; Li, Yiyi

    2010-10-01

    A numerical model of the welding arc is coupled to a model for the heat transfer and fluid flow in the weld pool of a SUS304 stainless steel during a moving GTA welding process. The described model avoids the use of the assumption of the empirical Gaussian boundary conditions, and at the same time, provides reliable boundary conditions to analyze the weld pool. Based on the two-dimensional axisymmetric numerical modeling of the argon arc, the heat flux to workpiece, the input current density, and the plasma drag stress are obtained. The arc temperature contours, the distributions of heat flux, and current density at the anode are in fair agreement with the reported experimental results. Numerical simulation and experimental studies to the weld pool development are carried out for a moving GTA welding on SUS304 stainless steel with different oxygen content from 30 to 220 ppm. The calculated result show that the oxygen can change the Marangoni convection from outward to inward direction on the liquid pool surface and make the wide shallow weld shape become narrow deep one. The calculated result for the weld shape and weld D/W ratio agrees well with the experimental one.

  16. Process parameter selection for optimizing the weld pool geometry in the tungsten inert gas welding of stainless steel

    Microsoft Academic Search

    S. C Juang; Y. S Tarng

    2002-01-01

    In this paper, the selection of process parameters for obtaining an optimal weld pool geometry in the tungsten inert gas (TIG) welding of stainless steel is presented. Basically, the geometry of the weld pool has several quality characteristics, for example, the front height, front width, back height and back width of the weld pool. To consider these quality characteristics together

  17. Welding II.

    ERIC Educational Resources Information Center

    Allegheny County Community Coll., Pittsburgh, PA.

    Instructional objectives and performance requirements are outlined in this course guide for Welding II, a performance-based course offered at the Community College of Allegheny County to introduce students to out-of-position shielded arc welding with emphasis on proper heats, electrode selection, and alternating/direct currents. After introductory…

  18. Welding Curriculum.

    ERIC Educational Resources Information Center

    EASTCONN Regional Educational Services Center, North Windham, CT.

    The purpose of this welding program is to provide students with skills and techniques to become employed as advanced apprentice welders. The welding program manual includes the following sections: (1) course description; (2) general objectives; (3) competencies; (4) curriculum outline for 13 areas; (5) 13 references; and (6) student progress…

  19. Welding system

    SciTech Connect

    Church, J.G.

    1984-07-31

    An electric arc welding gas system utilizing a welding gas comprising a mixture of argon, helium, carbon dioxide and oxygen; electrode currents in the range of 100 to 1100 amperes so as to form electrode metal globules of at least the size of the electrode diameter at the rate of 400 to 1200 globules per second.

  20. Welding III.

    ERIC Educational Resources Information Center

    Allegheny County Community Coll., Pittsburgh, PA.

    Instructional objectives and performance requirements are outlined in this course guide for Welding III, an advanced course in arc welding offered at the Community College of Allegheny County to provide students with the proficiency necessary for industrial certification. The course objectives, which are outlined first, specify that students will…

  1. Innovative Tools Advance Revolutionary Weld Technique

    NASA Technical Reports Server (NTRS)

    2009-01-01

    The iconic, orange external tank of the space shuttle launch system not only contains the fuel used by the shuttle s main engines during liftoff but also comprises the shuttle s backbone, supporting the space shuttle orbiter and solid rocket boosters. Given the tank s structural importance and the extreme forces (7.8 million pounds of thrust load) and temperatures it encounters during launch, the welds used to construct the tank must be highly reliable. Variable polarity plasma arc welding, developed for manufacturing the external tank and later employed for building the International Space Station, was until 1994 the best process for joining the aluminum alloys used during construction. That year, Marshall Space Flight Center engineers began experimenting with a relatively new welding technique called friction stir welding (FSW), developed in 1991 by The Welding Institute, of Cambridge, England. FSW differs from traditional fusion welding in that it is a solid-state welding technique, using frictional heat and motion to join structural components without actually melting any of the material. The weld is created by a shouldered pin tool that is plunged into the seam of the materials to be joined. The tool traverses the line while rotating at high speeds, generating friction that heats and softens but does not melt the metal. (The heat produced approaches about 80 percent of the metal s melting temperature.) The pin tool s rotation crushes and stirs the plasticized metal, extruding it along the seam as the tool moves forward. The material cools and consolidates, resulting in a weld with superior mechanical properties as compared to those weld properties of fusion welds. The innovative FSW technology promises a number of attractive benefits. Because the welded materials are not melted, many of the undesirables associated with fusion welding porosity, cracking, shrinkage, and distortion of the weld are minimized or avoided. The process is more energy efficient, safe (no toxic smoke or shielding gas, liquid metal splatter, arcing, dangerous voltage, or radiation), and environmentally sound (no consumables, fumes, or noise) than fusion welding. Under computer control, an automated FSW machine can create welds with high reproducibility, improving efficiency and overall quality of manufactured materials. The process also allows for welding dissimilar metals as well as those metals considered to be "unweldable" such as the 7xxx series aluminum alloys. Its effectiveness and versatility makes FSW useful for aerospace, rail, automotive, marine, and military applications. A downside to FSW, however, is the keyhole opening left in the weld when the FSW pin tool exits the weld joint. This is a significant problem when using the FSW process to join circumferential structures such as pipes and storage containers. Furthermore, weld joints that taper in material thickness also present problems when using the conventional FSW pin tool, because the threaded pin rotating within the weld joint material is a fixed length. There must be capability for the rotating pin to both increase and decrease in length in real time while welding the tapered material. (Both circumferential and tapered thickness weldments are found in the space shuttle external tank.) Marshall engineers addressed both the keyhole and tapered material thickness problems by developing the auto-adjustable pin tool. This unique piece of equipment automatically withdraws the pin into the tool s shoulder for keyhole closeout. In addition, the auto-adjustable pin tool retracts, or shortens, the rotating pin while welding a weld joint that tapers from one thickness to a thinner thickness. This year, the impact of the Marshall innovation was recognized with an "Excellence in Technology Transfer Award" from the Federal Laboratory Consortium.

  2. Increasing Productivity of Welding

    E-print Network

    Uhrig, J. J.

    1983-01-01

    -20, 1983 Welding Process Filler Metal Utilization (% deposited) 100% 908070 Figure No. )4. Pipe We/ding Glv\\AW 40 Plasma Arc (c:old wire) Flux Cored Arc Electroslag Gas Tungsten Arc (cold wire) Submerged Arc ~~Im... processes. These are shown by Figure 2 and included shielded metal-arc welding (stick welding), gas tungsten arc welding (TIG), gas metal arc welding (MIG), flux cored arc welding, submerged arc welding, plasma arc welding, stud arc welding and carbon...

  3. ??????????????????????? ??????????????????????????????? A356 ???????? ???????????? ?????????????????? ??????????????????????????????????? Investigation of Metallurgical and Mechanical properties of Joining of Semi Solid (SSM) A356 by Friction stir Welding process

    Microsoft Academic Search

    Abdul Binraheem

    The butt joints of semi solid A356 were produced in as cast conditions by friction stir welding process (FSW). The effects of the speed and the welding speed on the microstructure and mechanical properties were investigated. The variations of welding parameters produced various joints properties. It was found that the integrity of the joint contributed for the mechanical properties of

  4. Modeling eddy current analysis data to determine depth of weld penetration

    SciTech Connect

    Hench, K. W. (Karen W.); Christensen, W. (Wynn); Gallant, D.A. (Danny A.); Hinde, R. F. (Ralph F.), Jr.; Lopez, A. A. (Aaron A.); Martin, Chuck; Phillips, T. T. (Thomas Terrence)

    2002-01-01

    The Applied Engineering Technology Croup in the Engineering Sciences and Applications Division at Los Alamos National Laboratory is currently providing the design, engineering, assembly, and testing of an eddy current instrument for weld inspection. This instrument is designed to provide an in situ weld depth measurement of nuclear weapons primary components during fabrication. The goal of this effort is to improve the accuracy and reliability of the measurement of the weld joint depth and provide a mechanism for inspection without removing the part from the fixture. This feature is essential to accommodate the re-welding process if the inspection fails. The production system consists of a commercially available eddy current instrument and eddy current probe connected to a portable PC. The objective of the system software is acquire and analyze voltage and phase angle data to produce a near-real time estimate of weld depth. The data obtained from the instrument are perfectly suited for analysis by a neural network technique. This paper compares the effectiveness of a neural network application with traditional mathematical models for the analysis of weld depth information.

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

    NASA Astrophysics Data System (ADS)

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

    2001-06-01

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

  6. Automated GMA welding of austenitic stainless steel pipe

    SciTech Connect

    Tahash, G.J. [GE Gas Turbine Operation, Greenville, SC (United States)

    1996-12-31

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

  7. Effect of Tool Offset and Tool Rotational Speed on Enhancing Mechanical Property of Al/Mg Dissimilar FSW Joints

    NASA Astrophysics Data System (ADS)

    Liang, Zhiyuan; Chen, Ke; Wang, Xiaona; Yao, Junshan; Yang, Qi; Zhang, Lanting; Shan, Aidang

    2013-08-01

    Friction stir welding (FSW) is a promising solid-state joining technique for producing effective welds between Al alloy and Mg alloy. However, previously reported Al/Mg dissimilar FSW joints generally have limited strength or barely any ductility with relatively high strength, which was blamed on the brittle intermetallics formed during welding. In this study, effective joints with comparably high strength (163 MPa) and large elongation (~6 pct) were obtained. Three crucial/weak zones were identified in the welds: (1) Al/Mg bottom interface (BI) zone that resulted from the insufficient materials' intermixing and interdiffusion; (2) banded structure (BS) zone which contains intermetallic particles possibly formed by constitutional liquation; and (3) softened Al alloy to the retreating side (SAA-RS) zone due to the dissolution and coarsening of the strengthening precipitates. Three fracture modes observed in the tensile specimens perpendicular to the weld seam were found closely related to these zones. Their microstructure evolution with the change of tool rotational speed and tool offset was characterized and the consequent effect on the fracture mode alteration was studied. It turned out that enhancing the strengths of all these zones, but keeping the strength of the SAA lowest, is an effective way for enhancing ductility while keeping comparatively high strength in Al/Mg FSW joints. Also, suggestions for further improving the mechanical property of the Al/Mg dissimilar FSW joints were made accordingly for practical applications.

  8. Electron Beam Welding of Gear Wheels by Splitted Beam

    NASA Astrophysics Data System (ADS)

    D?ímal, Daniel

    2014-06-01

    This contribution deals with the issue of electron beam welding of high-accurate gear wheels composed of a spur gearing and fluted shaft joined with a face weld for automotive industry. Both parts made of the high-strength low-alloy steel are welded in the condition after final machining and heat treatment, performed by case hardening, whereas it is required that the run-out in the critical point of weldment after welding, i. e. after the final operation, would be 0.04 mm max.. In case of common welding procedure, cracks were formed in the weld, initiated by spiking in the weld root. Crack formation was prevented by the use of an interlocking joint with a rounded recess and suitable welding parameters, eliminating crack initiation by spiking in the weld root. Minimisation of the welding distortions was achieved by the application of tack welding with simultaneous splitting of one beam into two parts in the opposite sections of circumferential face weld attained on the principle of a new system of controlled deflection with digital scanning of the beam. This welding procedure assured that the weldment temperature after welding would not be higher than 400 °C. Thus, this procedure allowed achieving the final run-outs in the critical point of gearwheels within the maximum range up to 0.04 mm, which is acceptable for the given application. Accurate optical measurements did not reveal any changes in the teeth dimensions.

  9. WELDING RESEARCH -s77WELDING JOURNAL

    E-print Network

    DuPont, John N.

    ) in 1991 (Ref. 1), is a solid-state welding process that offers an attractive alternative to fusion weldingWELDING RESEARCH -s77WELDING JOURNAL ABSTRACT. The microstructure of AL- 6XN plates joined via a double-sided fric- tion stir weld has been investigated. The microstructural zones that develop during

  10. Establishing relationship between the base metal properties and friction stir welding process parameters of cast aluminium alloys

    Microsoft Academic Search

    M. Jayaraman; R. Sivasubramanian; V. Balasubramanian

    2010-01-01

    In friction stir welding (FSW), the material under the rotating action of non-consumable tool has to be stirred properly to get defect free welds in turn it will improve the strength of the welded joints. The welding conditions and parameters are differing based on the mechanical properties of base materials such as tensile strength, ductility and hardness which control the

  11. Picosecond Laser Welding of Spherical Glass Bead to Substrate

    NASA Astrophysics Data System (ADS)

    Ratautas, K.; Gedvilas, M.; Ra?iukaitis, G.

    Welding of a spherical shaped glass beads with the diameter of 0.7 mm to a float glass plate by using picosecond laser irradiation was investigated. The glass bead itself acts as focusing lens and should be considered as a part of optical system. The different number of pulses, repetition rate and average laser power were applied to estimate the joint strength dependence on the laser process parameters. Two types of crack-free welding regimes were found, namely, the point welding with a low number of laser pulses and a weak joint and the fusion welding when irradiation lasts up to one second.

  12. Electron beam weld development on a Filter Pack Assembly

    NASA Astrophysics Data System (ADS)

    Dereskiewicz, J. P.

    1994-06-01

    A continuous electron beam welding procedure was developed to replace the manual gas tungsten arc welding procedure on the Filter Pack Assembly. A statistical study was used to evaluate the feasibility of electron beam welding 6061-T6 aluminum covers to A356 cast weldments throughout the joint tolerance range specified on product drawings. Peak temperature exposures were not high enough to degrade the heat sensitive electrical components inside the cast weldment. Actual weldments with alodine coating on the weld joint area were successfully cleaned using a nonmetallic fiberglass brush cleaning method.

  13. Correlation analysis of the variation of weld seam and tensile strength in laser welding of galvanized steel

    NASA Astrophysics Data System (ADS)

    Sinha, Amit Kumar; Kim, Duck Young; Ceglarek, Darek

    2013-10-01

    Many advantages of laser welding technology such as high speed and non-contact welding make the use of the technology more attractive in the automotive industry. Many studies have been conducted to search the optimal welding condition experimentally that ensure the joining quality of laser welding that relies both on welding system configuration and welding parameter specification. Both non-destructive and destructive techniques, for example, ultrasonic inspection and tensile test are widely used in practice for estimating the joining quality. Non-destructive techniques are attractive as a rapid quality testing method despite relatively low accuracy. In this paper, we examine the relationship between the variation of weld seam and tensile shear strength in the laser welding of galvanized steel in a lap joint configuration in order to investigate the potential of the variation of weld seam as a joining quality estimator. From the experimental analysis, we identify a trend in between maximum tensile shear strength and the variation of weld seam that clearly supports the fact that laser welded parts having larger variation in the weld seam usually have lower tensile strength. The discovered relationship leads us to conclude that the variation of weld seam can be used as an indirect non-destructive testing method for estimating the tensile strength of the welded parts.

  14. Effect of welding speed on microstructural and mechanical properties of friction stir welded Inconel 600

    Microsoft Academic Search

    K. H. Song; H. Fujii; K. Nakata

    2009-01-01

    In order to evaluate the properties of a friction stir welded Ni base alloy, Inconel 600 (single phase type) was selected. Sound friction stir welds without weld defect were obtained at 150 and 200mm\\/min in welding speed, however, a groove like defect occurred at 250mm\\/min. The electron back scattered diffraction (EBSD) method was used to analyze the grain boundary character

  15. CLOSURE WELD DEVELOPMENT FOR 3013 OUTER CONTAINERS

    SciTech Connect

    Daugherty, W.; Howard, S.; Peterson, K.; Stokes, M.

    2009-11-10

    Excess plutonium materials in the DOE complex are packaged and stored in accordance with DOE-STD-3013. This standard specifies requirements for the stabilization of such materials and subsequent packaging in dual nested seal-welded containers. Austenitic stainless steels have been selected for container fabrication. The inner 3013 container provides contamination control while the outer 3013 container is the primary containment vessel and is the focus of this paper. Each packaging site chose a process for seal welding the outer 3013 containers in accordance with its needs and expertise. The two processes chosen for weld closure were laser beam welding (LBW) and gas tungsten arc welding (GTAW). Following development efforts, each system was qualified in accordance with DOE-STD-3013 prior to production use. The 3013 outer container closure weld joint was designed to accommodate the characteristics of a laser weld. This aspect of the joint design necessitated some innovative process and equipment considerations in the application of the GTAW process. Details of the weld requirements and the development processes are presented and several potential enhancements for the GTAW system are described.

  16. Laser Assisted Micro Wire GMAW and Droplet Welding

    SciTech Connect

    FUERSCHBACH, PHILLIP W.; LUCK, D. L.; BERTRAM, LEE A.; ANDERSON, ROBERT A.

    2002-03-01

    Laser beam welding is the principal welding process for the joining of Sandia weapon components because it can provide a small fusion zone with low overall heating. Improved process robustness is desired since laser energy absorption is extremely sensitive to joint variation and filler metal is seldom added. This project investigated the experimental and theoretical advantages of combining a fiber optic delivered Nd:YAG laser with a miniaturized GMAW system. Consistent gas metal arc droplet transfer employing a 0.25 mm diameter wire was only obtained at high currents in the spray transfer mode. Excessive heating of the workpiece in this mode was considered an impractical result for most Sandia micro-welding applications. Several additional droplet detachment approaches were investigated and analyzed including pulsed tungsten arc transfer(droplet welding), servo accelerated transfer, servo dip transfer, and electromechanically braked transfer. Experimental observations and rigorous analysis of these approaches indicate that decoupling droplet detachment from the arc melting process is warranted and may someday be practical.

  17. European and International Standards on health and safety in welding

    NASA Astrophysics Data System (ADS)

    Howe, A.

    2009-02-01

    A number of European and International Standards on health and safety in welding have been published in recent years and work on several more is nearing completion. These standards have been prepared jointly by the International Standards Organization (ISO) and the European Committee for Standardization (CEN). The standards development work has mostly been led by CEN/TC 121/SC 9, with excellent technical input from experts within Europe; but work on the revision of published standards, which has recently gathered pace, is now being carried out by ISO/TC 44/SC 9, with greater international involvement. This paper gives an overview of the various standards that have been published, are being revised or are under development in this field of health and safety in welding, seeking to (i) increase international awareness of published standards, (ii) encourage wider participation in health and safety in welding standards work and (iii) obtain feedback and solicit comments on standards that are currently under development or revision. Such an initiative is particularly timely because work is currently in progress on the revision of one of the more important standards in this field, namely EN ISO 10882:2001 Health and safety in welding and allied processes— Sampling of airborne particles and gases in the operator's breathing zone — Part 1: Sampling of airborne particles.

  18. Numerical simulation of linear fiction welding (LFW) processes

    SciTech Connect

    Fratini, L.; La Spisa, D. [University of Palermo-Dept. of Industrial engineering (Italy)

    2011-05-04

    Solid state welding processes are becoming increasingly important due to a large number of advantages related to joining ''unweldable'' materials and in particular light weight alloys. Linear friction welding (LFW) has been used successfully to bond non-axisymmetric components of a range of materials including titanium alloys, steels, aluminum alloys, nickel, copper, and also dissimilar material combinations. The technique is useful in the research of quality of the joints and in reducing costs of components and parts of the aeronautic and automotive industries.LFW involves parts to be welded through the relative reciprocating motion of two components under an axial force. In such process the heat source is given by the frictional forces work decaying into heat determining a local softening of the material and proper bonding conditions due to both the temperature increase and the local pressure of the two edges to be welded. This paper is a comparative test between the numerical model in two dimensions, i.e. in plane strain conditions, and in three dimensions of a LFW process of AISI1045 steel specimens. It must be observed that the 3D model assures a faithful simulation of the actual threedimensional material flow, even if the two-dimensional simulation computational times are very short, a few hours instead of several ones as the 3D model. The obtained results were compared with experimental values found out in the scientific literature.

  19. Numerical simulation of linear fiction welding (LFW) processes

    NASA Astrophysics Data System (ADS)

    Fratini, L.; La Spisa, D.

    2011-05-01

    Solid state welding processes are becoming increasingly important due to a large number of advantages related to joining "unweldable" materials and in particular light weight alloys. Linear friction welding (LFW) has been used successfully to bond non-axisymmetric components of a range of materials including titanium alloys, steels, aluminum alloys, nickel, copper, and also dissimilar material combinations. The technique is useful in the research of quality of the joints and in reducing costs of components and parts of the aeronautic and automotive industries. LFW involves parts to be welded through the relative reciprocating motion of two components under an axial force. In such process the heat source is given by the frictional forces work decaying into heat determining a local softening of the material and proper bonding conditions due to both the temperature increase and the local pressure of the two edges to be welded. This paper is a comparative test between the numerical model in two dimensions, i.e. in plane strain conditions, and in three dimensions of a LFW process of AISI1045 steel specimens. It must be observed that the 3D model assures a faithful simulation of the actual threedimensional material flow, even if the two-dimensional simulation computational times are very short, a few hours instead of several ones as the 3D model. The obtained results were compared with experimental values found out in the scientific literature.

  20. Geoengineering characterization of welded tuffs from laboratory and field investigations

    SciTech Connect

    Zimmerman, R.M.; Nimick, F.B.; Board, M.P.

    1984-12-31

    Welded tuff beneath Yucca Mountain adjacent to the Nevada Test Site (NTS) is being considered for development as a high-level radioactive waste repository by the Nevada Nuclear Waste Storage Investigations (NNWSI) Project. Because access into Yucca Mountain has been limited to borehole explorations, early geoengineering materials characterizations have been derived from laboratory tests on cores from Yucca Mountain and from laboratory and field tests on welded tuffs located in G-Tunnel on the NTS. G-Tunnel contains welded tuffs that have similar properties and stress states to those at Yucca Mountain and has been the location for in situ rock mechanics testing. The purpose of this paper is to summarize the geoengineering material property data obtained to date and to compare appropriate laboratory and field data from G-Tunnel to findings from Yucca Mountain. Geomechanical and thermal data are provided and are augmented by limited geological and hydrological data. A comparison of results of laboratory measurements on tuffs from Yucca Mountain and G-Tunnel indicates good agreement between the bulk densities, saturations, moduli of elasticity, Poisson`s ratios, and P-wave velocities. The G-Tunnel tuff has slightly lower thermal conductivity, tensile strength, compressive strength and slightly higher matrix permeability than does the welded tuff near the proposed repository horizon at Yucca Mountain. From a laboratory-to-field scaling perspective, the modulus of deformation shows the most sensitivity to field conditions because of the presence of the joints found in the field. 14 references, 1 table.

  1. Geoengineering characterization of welded tuffs from laboratory and field investigations

    SciTech Connect

    Zimmerman, R.M.; Nimick, F.B.; Board, M.P.

    1984-12-31

    Welded tuff beneath Yucca Mountain adjacent to the Nevada Test Site (NTS) is being considered for development as a high-level radioactive waste repository by the Nevada Nuclear Waste Storage Investigations (NNWSI) Project. Because access into Yucca Mountain has been limited to borehole explorations, early geoengineering materials characterizations have been derived from laboratory tests on cores from Yucca Mountain and from laboratory and field tests on welded tuffs located in G-Tunnel on the NTS. G-Tunnel contains welded tuffs that have similar properties and stress states to those at Yucca Mountain and has been the location for in situ rock mechanics testing. The purpose of this paper is to summarize the geoengineering material property data obtained to date and to compare appropriate laboratory and field data from G-Tunnel to findings from Yucca Mountain. Geomechanical and thermal data are provided and are augmented by limited geological and hydrological data. A comparison of results of laboratory measurements on tuffs from Yucca Mountain and G-Tunnel indicates good agreement between the bulk densities, saturations, moduli of elasticity, Poisson`s ratios, and P-wave velocities. The G-Tunnel tuff has slightly lower thermal conductivity, tensile strength, compressive strength and slightly higher matrix permeability than does the welded tuff near the proposed repository horizon at Yucca Mountain. From a laboratory-to-field scaling perspective, the modulus of deformation shows the most sensitivity to field conditions because of the presence of joints found in the field. 14 refs., 1 tab.

  2. Laser Welding in Electronic Packaging

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The laser has proven its worth in numerous high reliability electronic packaging applications ranging from medical to missile electronics. In particular, the pulsed YAG laser is an extremely flexible and versatile too] capable of hermetically sealing microelectronics packages containing sensitive components without damaging them. This paper presents an overview of details that must be considered for successful use of laser welding when addressing electronic package sealing. These include; metallurgical considerations such as alloy and plating selection, weld joint configuration, design of optics, use of protective gases and control of thermal distortions. The primary limitations on use of laser welding electronic for packaging applications are economic ones. The laser itself is a relatively costly device when compared to competing welding equipment. Further, the cost of consumables and repairs can be significant. These facts have relegated laser welding to use only where it presents a distinct quality or reliability advantages over other techniques of electronic package sealing. Because of the unique noncontact and low heat inputs characteristics of laser welding, it is an ideal candidate for sealing electronic packages containing MEMS devices (microelectromechanical systems). This paper addresses how the unique advantages of the pulsed YAG laser can be used to simplify MEMS packaging and deliver a product of improved quality.

  3. Wonder Weld

    SciTech Connect

    None

    2012-01-01

    Engineers at the U.S. Department of Energy's Princeton Plasma Physics Laboratory are using the process shown here to create a super-strong weld for the upgrade of a key component of the Lab's experimental nuclear fusion reactor.

  4. Welding Supervisor

    NSDL National Science Digital Library

    WGBH Educational Foundation

    2009-12-24

    In this video segment adapted from Pennsylvania College of Technology and WVIA, get a behind-the-scenes look at a Toyota manufacturing plant with a manufacturing specialist who oversees robotic welding cells.

  5. Evaluation of Training Samples Manually Welded With the Universal Handtool in a Space Simulation Chamber

    NASA Technical Reports Server (NTRS)

    Russell, C. K.; Malone, T. W.; Cato, S. N.

    2004-01-01

    The international space welding experiment was designed to evaluate the universal handtool (UHT) functions as a welding, brazing, coating, and cutting tool for in-space operations. The UHT is an electron beam welding system developed by the Paton Welding Institute (PWI), Kiev, Ukraine, and operated a 8 kV with up to 1 kW of power. In preparation for conducting the space welding experiment, cosmonauts were trained to properly operate the UHT and correctly process samples. This Technical Memorandum presents the results of the destructive and nondestructive evaluation of the training samples made in Russia in 1998. It was concluded that acceptable welds can be made with the UHT despite the constraints imposed by a space suit. The lap joint fillet weld configuration was more suitable than the butt joint configuration for operators with limited welding experience. The tube braze joint configuration designed by the PWI was easily brazed in a repeatable manner.

  6. Syllabus in Trade Welding.

    ERIC Educational Resources Information Center

    New York State Education Dept., Albany. Bureau of Secondary Curriculum Development.

    The syllabus outlines material for a course two academic years in length (minimum two and one-half hours daily experience) leading to entry-level occupational ability in several welding trade areas. Fourteen units covering are welding, gas welding, oxyacetylene welding, cutting, nonfusion processes, inert gas shielded-arc welding, welding cast…

  7. Automatic programming of arc welding robots

    NASA Astrophysics Data System (ADS)

    Padmanabhan, Srikanth

    Automatic programming of arc welding robots requires the geometric description of a part from a solid modeling system, expert weld process knowledge and the kinematic arrangement of the robot and positioner automatically. Current commercial solid models are incapable of storing explicitly product and process definitions of weld features. This work presents a paradigm to develop a computer-aided engineering environment that supports complete weld feature information in a solid model and to create an automatic programming system for robotic arc welding. In the first part, welding features are treated as properties or attributes of an object, features which are portions of the object surface--the topological boundary. The structure for representing the features and attributes is a graph called the Welding Attribute Graph (WAGRAPH). The method associates appropriate weld features to geometric primitives, adds welding attributes, and checks the validity of welding specifications. A systematic structure is provided to incorporate welding attributes and coordinate system information in a CSG tree. The specific implementation of this structure using a hybrid solid modeler (IDEAS) and an object-oriented programming paradigm is described. The second part provides a comprehensive methodology to acquire and represent weld process knowledge required for the proper selection of welding schedules. A methodology of knowledge acquisition using statistical methods is proposed. It is shown that these procedures did little to capture the private knowledge of experts (heuristics), but helped in determining general dependencies, and trends. A need was established for building the knowledge-based system using handbook knowledge and to allow the experts further to build the system. A methodology to check the consistency and validity for such knowledge addition is proposed. A mapping shell designed to transform the design features to application specific weld process schedules is described. A new approach using fixed path modified continuation methods is proposed in the final section to plan continuously the trajectory of weld seams in an integrated welding robot and positioner environment. The joint displacement, velocity, and acceleration histories all along the path as a function of the path parameter for the best possible welding condition are provided for the robot and the positioner to track various paths normally encountered in arc welding.

  8. Developing an Empirical Relationship to Predict Tensile Strength of Friction Stir Welded AA2219 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Elangovan, K.; Balasubramanian, V.; Babu, S.

    2008-12-01

    AA2219 aluminum alloy (Al-Cu-Mn alloy) has gathered wide acceptance in the fabrication of lightweight structures requiring a high strength-to-weight ratio and good corrosion resistance. Friction stir welding (FSW) process is an emerging solid state joining process in which the material that is being welded does not melt and recast. This process uses a nonconsumable tool to generate frictional heat in the abutting surfaces. The welding parameters such as tool rotational speed, welding speed, axial force, etc., and tool pin profile play a major role in deciding the joint strength. An attempt has been made to develop an empirical relationship between FSW variables to predict tensile strength of the friction stir welded AA2219 aluminum alloy. To obtain the desired strength, it is essential to have a complete control over the relevant process parameters to maximize the tensile strength on which the quality of a weldment is based. Therefore, it is very important to select and control the welding process parameter for obtaining maximum strength. To achieve this various prediction methods such as response surface method (RSM), analysis of variance (ANOVA), Student’s t-test, coefficient of determination, etc., can be applied to define the desired output variables through developing mathematical models to specify the relationship between the output parameters and input variables. Four factors, five levels central composite design have been used to minimize number of experimental conditions. The developed mathematical relationship can be effectively used to predict the tensile strength of FSW joints of AA2219 aluminum alloy at 95% confidence level.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  10. 49 CFR 192.233 - Miter joints.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 2011-10-01 2011-10-01 false Miter joints. 192.233 Section 192.233 Transportation...Welding of Steel in Pipelines § 192.233 Miter joints. (a) A miter joint on steel pipe to be operated at a pressure...

  11. 49 CFR 192.233 - Miter joints.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 2010-10-01 2010-10-01 false Miter joints. 192.233 Section 192.233 Transportation...Welding of Steel in Pipelines § 192.233 Miter joints. (a) A miter joint on steel pipe to be operated at a pressure...

  12. 49 CFR 178.345-4 - Joints.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 2011-10-01 false Joints. 178.345-4 Section 178...Transportation § 178.345-4 Joints. (a) All joints between the cargo tank shell...rings, and bulkheads must be welded in conformance with Section...

  13. 49 CFR 178.345-4 - Joints.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 2010-10-01 false Joints. 178.345-4 Section 178...Transportation § 178.345-4 Joints. (a) All joints between the cargo tank shell...attaching rings, and bulkheads must be welded in conformance with Section...

  14. Reliability fatigue design of welded structures

    SciTech Connect

    Shen, M.H.H.; Lanning, D. [Ohio State Univ., Columbus, OH (United States). Dept. of Aerospace Engineering, Applied Mechanics and Aviation

    1996-12-31

    This article presents a new design method for fatigue reliability of welded structural components. The method consists of determining the probabilistic crack path and calculating the cumulative probability of failure for new or existing welded structural components with uncertainties in external loadings, material properties and initial fatigue crack geometry. An example of the application of this method to an offshore structural joint with fatigue cracks is presented.

  15. Tailoring weld geometry during keyhole mode laser welding using a genetic algorithm and a heat transfer model

    NASA Astrophysics Data System (ADS)

    Rai, R.; Roy, T. Deb

    2006-03-01

    Tailoring of weld attributes based on scientific principles remains an important goal in welding research. The current generation of unidirectional laser keyhole models cannot determine sets of welding variables that can lead to a particular weld attribute such as specific weld geometry. Here we show how a computational heat transfer model of keyhole mode laser welding can be restructured for systematic tailoring of weld attributes based on scientific principles. Furthermore, the model presented here can calculate multiple sets of laser welding variables, i.e. laser power, welding speed and beam defocus, with each set leading to the same weld pool geometry. Many sets of welding variables were obtained via a global search using a real number-based genetic algorithm, which was combined with a numerical heat transfer model of keyhole laser welding. The reliability of the numerical heat transfer calculations was significantly improved by optimizing values of the uncertain input parameters from a limited volume of experimental data. The computational procedure was applied to the keyhole mode laser welding of the 5182 Al-Mg alloy to calculate various sets of welding variables to achieve a specified weld geometry. The calculated welding parameter sets showed wide variations of the values of welding parameters, but each set resulted in a similar fusion zone geometry. The effectiveness of the computational procedure was examined by comparing the computed weld geometry for each set of welding parameters with the corresponding experimental geometry. The results provide hope that systematic tailoring of weld attributes via multiple pathways, each representing alternative welding parameter sets, is attainable based on scientific principles.

  16. Dissimilar metals joint evaluation

    NASA Technical Reports Server (NTRS)

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

    1974-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

  18. Metallurgical investigations of pulsed Nd:YAG laser welding of AISI 321 and AISI 630 stainless steels

    Microsoft Academic Search

    S. A. A. Akbari Mousavi; A. R. Sufizadeh

    2009-01-01

    In this paper, pulsed Nd:YAG laser welding of 321 austenitic stainless steel and 630 (17-4PH) precipitation hardening stainless steel is being studied. The joints had a circular geometry and butt welded. Studies were focused on the effects of laser power, beam diameter and pulse duration on the depth and width of the welds. Microstructures of the welded joints were investigated

  19. Welding characteristics of 27, 40 and 67 kHz ultrasonic plastic welding systems using fundamental- and higher-resonance frequencies.

    PubMed

    Tsujino, Jiromaru; Hongoh, Misugi; Yoshikuni, Masafumi; Hashii, Hidekazu; Ueoka, Tetsugi

    2004-04-01

    The welding characteristics of 27, 40 and 67 kHz ultrasonic plastic welding systems that are driven at only the fundamental-resonance frequency vibration were compared, and also those of the welding systems that were driven at the fundamental and several higher resonance frequencies simultaneously were studied. At high frequency, welding characteristics can be improved due to the larger vibration loss of plastic materials. For welding of rather thin or small specimens, as the fundamental frequency of these welding systems is higher and the numbers of driven higher frequencies are driven simultaneously, larger welded area and weld strength were obtained. PMID:15047274

  20. Microstructure and Strength Characteristics of Alloy 617 Welds

    SciTech Connect

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

    2005-06-01

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

  1. Study on welding such dissimilar materials as AISI 304 stainless steel and DHP copper in a sea-water environment. Influence of weld metals on corrosion

    Microsoft Academic Search

    E. Zumelzu; C. Cabezas

    1996-01-01

    This work determines which material performs best according to its specific properties, by means of welding joints and evaluating the different welding processes and weld metals employed, considering their mechanical performance and resistance to sea-water corrosion. The base materials were butt-welded to produce 1.5 mm thick test pieces of AISI 304 stainless steel and copper, and de-oxidized in DHP phosphorus,

  2. A comparative study of laser beam welding and laser–MIG hybrid welding of Ti–Al–Zr–Fe titanium alloy

    Microsoft Academic Search

    Ruifeng Li; Zhuguo Li; Yanyan Zhu; Lei Rong

    2011-01-01

    Ti–Al–Zr–Fe titanium alloy sheets with thickness of 4mm were welded using laser beam welding (LBW) and laser-MIG hybrid welding (LAMIG) methods. To investigate the influence of the methods difference on the joint properties, optical microscope observation, microhardness measurement and mechanical tests were conducted. Experimental results show that the sheets can be welded at a high speed of 1.8m\\/min and power

  3. Pulsed magnetic welding

    SciTech Connect

    Sheely, W.F.

    1986-11-20

    Solid state welding techniques are an alternative to fusion welding. Two solid state welding techniques are pulsed magnetic welding and explosive bonding. Both achieve bonds by impacting the metals to be joined at high velocity. Development of the pulsed magnetic welding process by Hanford Engineers for fuel fabrication may make this process useful for a variety of other applications. Hanford engineers have developed advanced equipment for pulsed magnetic welding and have defined conditions for reliably welding stainless steel fuel pins using this equipment.

  4. Finite element analysis and simulation of welding - an addendum: a bibliography (1996-2001)

    NASA Astrophysics Data System (ADS)

    Mackerle, Jaroslav

    2002-05-01

    This paper gives a bibliographical review of the finite element methods applied to the analysis and simulation of welding processes. The bibliography is an addendum to the finite element analysis and simulation of welding: a bibliography (1976-96) published in Modelling Simul. Mater. Sci. Eng. (1996) 4 501-33. The added bibliography at the end of this paper contains approximately 550 references to papers and conference proceedings on the subject that were published in 1996-2001. These are classified in the following categories: modelling of welding processes in general; modelling of specific welding processes; influence of geometrical parameters; heat transfer and fluid flow in welds; residual stresses and deformations in welds; fracture mechanics and welding; fatigue of welded structures; destructive and non-destructive evaluation of weldments and cracks; welded tubular joints, pipes and pressure vessels/components; welds in plates and other structures/components.

  5. Effect of Pre- and Post-weld Heat Treatments on Linear Friction Welded Ti-5553

    NASA Astrophysics Data System (ADS)

    Wanjara, Priti; Dalgaard, Elvi; Gholipour, Javad; Cao, Xinjin; Cuddy, Jonathan; Jonas, John J.

    2014-10-01

    Linear friction welding allows solid-state joining of near-beta ( ?) titanium alloy Ti-5553 (Ti-5Al-5V-5Mo-3Cr). In the as-welded condition, the weld zone (WZ) exhibits ? grain refinement and marked softening as compared with Ti-5553 in the solution heat treated and aged condition. The softening of the weldment is attributed to the depletion of the strengthening alpha ( ?) phase in the WZ and the adjacent thermo-mechanically affected zone (TMAZ). Specifically, in near- ? titanium alloys, the strength of the material mainly depends on the shape, size, distribution, and fraction of the primary ? and other decomposition products of the ? phase. Hence, a combination of pre- and post-weld heat treatments were applied to determine the conditions that allow mitigating the ? phase depletion in the WZ and TMAZ of the welds. The mechanical response of the welded samples to the heat treatments was determined by performing microhardness measurements and tensile testing at room temperature with an automated 3D deformation measurement system. It was found that though the joint efficiency in the as-welded condition was high (96 pct), strain localization and failure occurred in the TMAZ. The application of post-weld solution heat treatment with aging was effective in restoring ?, increasing the joint efficiency (97 to 99 pct) and inducing strain localization and failure in the parent material region.

  6. WELDING RESEARCH -s281WELDING JOURNAL

    E-print Network

    DuPont, John N.

    WELDING RESEARCH -s281WELDING JOURNAL ABSTRACT. Superaustenitic stainless steel alloys can often beam welds were also deposited on the surfaces of the button melts in order to observe the influ- ence. There- fore, the processing parameters used dur- ing welding must be carefully controlled in order

  7. WELDING RESEARCH -S125WELDING JOURNAL

    E-print Network

    DuPont, John N.

    - rosion resistance. However, during solid- ification of the weld, Mo segregates pref- erentiallyWELDING RESEARCH -S125WELDING JOURNAL ABSTRACT. Microstructural evolution and solidification cracking susceptibility of dissimilar metal welds between AL- 6XN super austenitic stainless steel and two

  8. Comparative study: Mechanical and metallurgical aspects of tailored welded blanks (TWBs)

    Microsoft Academic Search

    E. Bayraktar; D. Kaplan; B. S. Yilbas

    2008-01-01

    In order to satisfy the requirements of productivity and quality, in recent years, LASER welding processes of certain grades of steels mainly thin sheets assemblies or tailored welded blanks (TWBs) have given many successful advantages in manufacturing engineering. This welding process of in particular makes it possible very easily to joint the steel parts in thickness and grade identical or

  9. Enhancing the Exterior Performance of Wood Joined by Linear and Rotational Welding

    Microsoft Academic Search

    A. Pizzi; H. R. Mansouri; J. M. Leban; L. Delmotte; F. Pichelin

    2011-01-01

    Application of rosin, a wood derived, non-toxic, natural, inexpensive and easily and abundantly available natural material, to the wood faces to be joined by either linear vibration welding or rotational dowel welding has shown to greatly enhance the water resistance of welded wood joints. The method of application has been shown to have a marked effect on the results, with

  10. Materials and Design 50 (2013) 38-43 Regeneration Technique for Welding Nanostructured Bainite

    E-print Network

    Cambridge, University of

    2013-01-01

    match those of the base metal. Keywords: Nanostructured Bainitic Steel; Welded Joint; Regeneration generated during welding process. 2. Experimental procedure 2.1 Materials and experimental procedure HighMaterials and Design 50 (2013) 38-43 1 Regeneration Technique for Welding Nanostructured Bainite K

  11. Understanding Mechanical Properties of Novel High Strength Steel Weld Metals Through High-Resolution Microstructural Investigations

    E-print Network

    Cambridge, University of

    Understanding Mechanical Properties of Novel High Strength Steel Weld Metals Through High such steels must be joined with care with particular attention placed on welding parameters, if both strength) with a compatible experimental composition was also investigated. Experimental procedures Welded joints were made

  12. Creep strength of high chromium steels welded parts under multiaxial stress conditions

    Microsoft Academic Search

    Masatsugu Yaguchi; Takashi Ogata; Takayuki Sakai

    2010-01-01

    Internal pressure creep tests as well as uniaxial creep tests were conducted on 9Cr and 12Cr steels welded joints in order to evaluate creep strength of the high chromium steels welded parts under multiaxial stress conditions, where a welding direction of the internal pressure specimen was longitudinal one. Except under high stress conditions, cracks occurred at fine grained HAZ region

  13. Statistical Analysis of High-Cycle Fatigue Behavior of Friction Stir Welded AA5083-H321

    E-print Network

    Grujicic, Mica

    stir-welded (FSW) joints of AA5083-H321 (a solid-solution-strengthened and strain Friction stir welding (FSW) is a relatively new solid-state metal-joining process that was inventedStatistical Analysis of High-Cycle Fatigue Behavior of Friction Stir Welded AA5083-H321 M. Grujicic

  14. Modeling of AA5083 Material-Microstructure Evolution During Butt Friction-Stir Welding

    E-print Network

    Grujicic, Mica

    . Introduction Friction stir welding (FSW) is a solid-state metal-joining process (Ref 1-3). Within FSW tool and forged into a welding joint behind the tool. Owing to its solid-state character and lowerModeling of AA5083 Material-Microstructure Evolution During Butt Friction-Stir Welding M. Grujicic

  15. Dissimilar welding of AISI 310 austenitic stainless steel to nickel-based alloy Inconel 657

    Microsoft Academic Search

    H. Naffakh; M. Shamanian; F. Ashrafizadeh

    2009-01-01

    The current work was carried out to characterize welding of AISI 310 austenitic stainless steel to Inconel 657 nickel–chromium superalloy. The welds were produced using four types of filler materials; the nickel-based corresponding to Inconel 82, Inconel A, Inconel 617 and 310 austenitic stainless steels. This paper describes the selection of welding consumables for the joint. The comparative evaluation was

  16. A PRELIMINARY STUDY OF DOUBLE-SIDED ARC WELDING PROCESS IN SHIP STRUCTURE MANUFACTURING

    E-print Network

    Zhang, YuMing

    : Inconel 625 Filler Metal Microhardness Traverse Across Butt Joint of DSAW Weld. Base Metal - DH-36. Filler.L. HAZ BM Relative Distance from Weld Metal, inch #12;What to Do Next? o Complete testing of Inconel 625A PRELIMINARY STUDY OF DOUBLE-SIDED ARC WELDING PROCESS IN SHIP STRUCTURE MANUFACTURING Yu

  17. High powder CO 2 and Nd?YAG laser welding of wrought Inconel 718

    Microsoft Academic Search

    S. Gobbi; Li Zhang; J. Norris; K. H. Richter; J. H. Loreau

    1996-01-01

    High power laser welding techniques and related metallurgy have been investigated on Inconel 718 sheets, 4 mm and 8 mm of thickness, in annealed and aged states. The CO2 CW laser welded joint, with high depth to width ratio, is suitable for post welding machining. The uniform bead profiles were acheived by using an Nd?YAG pulsed laser, which have an

  18. Friction Stir Weld Failure Mechanisms in Aluminum-Armor Structures Under Ballistic

    E-print Network

    Grujicic, Mica

    Friction Stir Weld Failure Mechanisms in Aluminum-Armor Structures Under Ballistic Impact Loading and of the attendant ballistic-impact failure mechanisms in prototypical friction stir welding (FSW) joints found limit, failure mechanisms, friction stir welding 1. Introduction In the context of military tactical

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

    SciTech Connect

    Candan, L.; Demir, A.; Akman, E. [University of Kocaeli, Laser Technologies Research and Application Center, Kocaeli (Turkey)

    2007-04-23

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

  20. Explosive welding technique for joining aluminum and steel tubes

    NASA Technical Reports Server (NTRS)

    Wakefield, M. E.

    1975-01-01

    Silver sheet is wrapped around aluminum portion of joint. Mylar powder box is wrapped over silver sheet. Explosion welds silver to aluminum. Stainless-steel tube is placed over silver-aluminum interface. Mylar powder box, covered with Mylar tape, is wrapped around steel member. Explosion welds steel to silver-aluminum interface.

  1. Joining of aluminum alloy to steel by friction stir welding

    Microsoft Academic Search

    Takehiko Watanabe; Hirofumi Takayama; Atsushi Yanagisawa

    2006-01-01

    The authors tried to butt-weld an aluminum alloy plate to a mild steel plate by friction stir welding, and investigated the effects of a pin rotation speed, the position for the pin axis to be inserted on the tensile strength and the microstructure of the joint. The behavior of the oxide film on the faying surface of the steel during

  2. Nondestructive testing of welds on thin-walled tubing

    NASA Technical Reports Server (NTRS)

    Hagemaier, D. J.; Posakony, G. J.

    1969-01-01

    Special ultrasonic search unit, or transducer assembly, reliably inspects the quality of melt-through welds of fusion welded tubing couplers for hydraulic lines. This instrumentation can also be used to detect faulty braze bonds in thin-walled, small diameter joints and wall thickness of thin-walled metal tubing.

  3. Optical sensor for real-time weld defect detection

    NASA Astrophysics Data System (ADS)

    Ancona, Antonio; Maggipinto, Tommaso; Spagnolo, Vincenzo; Ferrara, Michele; Lugara, Pietro M.

    2002-04-01

    In this work we present an innovative optical sensor for on- line and non-intrusive welding process monitoring. It is based on the spectroscopic analysis of the optical VIS emission of the welding plasma plume generated in the laser- metal interaction zone. Plasma electron temperature has been measured for different chemical species composing the plume. Temperature signal evolution has been recorded and analyzed during several CO2-laser welding processes, under variable operating conditions. We have developed a suitable software able to real time detect a wide range of weld defects like crater formation, lack of fusion, excessive penetration, seam oxidation. The same spectroscopic approach has been applied for electric arc welding process monitoring. We assembled our optical sensor in a torch for manual Gas Tungsten Arc Welding procedures and tested the prototype in a manufacturing industry production line. Even in this case we found a clear correlation between the signal behavior and the welded joint quality.

  4. Automated weld torch guidance control system

    NASA Technical Reports Server (NTRS)

    Smith, H. E.; Wall, W. A.; Burns, M. R., Jr. (inventors)

    1986-01-01

    A device for automatically controlling the movement of a welding torch while welding an elongated joint is described. A charge injection television camera is carried on a movable support. The camera includes a matrix of individual light sensing video elements which generate voltages responsive to light reflected off of the joint and surrounding areas of the work piece. The voltages produced by the pixels are converted to digital words which are fed to a microprocessor for generating an error signal. This error signal is fed to a digital motor which is used to drive a movable support upon which the television camera is carried.

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

    SciTech Connect

    Shah Hosseini, H., E-mail: h.shahhosseini@ma.iut.ac.ir; Shamanian, M.; Kermanpur, A.

    2011-04-15

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

  6. Signal Analysis of Gas Tungsten Arc Welds

    NASA Technical Reports Server (NTRS)

    Eagar, T. W.

    1985-01-01

    Gas tungsten arc welding is a process in which the input parameters such as current, voltage and travel speed, can be easily controlled and/or monitored. However, weld quality is not solely a function of these parameters. An adaptive method of observing weld quality is desired to improve weld quality assurance. The use of dynamic electrical properties of the welding arc as a weld quality monitor was studied. The electrical properties of the arc are characterized by the current voltage transfer function. The hardware and software necessary to collect the data at a maximum rate of 45 kHz and to allow the off-line processing of this data are tested. The optimum input current waveform is determined. Bead-on-plate welds to observe such characteristics of the weld as the fundamental frequency of the puddle are studied. Future work is planned to observe changes of the arc response with changes in joint geometry, base metal chemistry, and shielding gas composition are discussed.

  7. Pulsed magnetic welding

    Microsoft Academic Search

    Sheely

    1986-01-01

    Solid state welding techniques are an alternative to fusion welding. Two solid state welding techniques are pulsed magnetic welding and explosive bonding. Both achieve bonds by impacting the metals to be joined at high velocity. Development of the pulsed magnetic welding process by Hanford Engineers for fuel fabrication may make this process useful for a variety of other applications. Hanford

  8. A Laser-Based Vision System for Weld Quality Inspection

    PubMed Central

    Huang, Wei; Kovacevic, Radovan

    2011-01-01

    Welding is a very complex process in which the final weld quality can be affected by many process parameters. In order to inspect the weld quality and detect the presence of various weld defects, different methods and systems are studied and developed. In this paper, a laser-based vision system is developed for non-destructive weld quality inspection. The vision sensor is designed based on the principle of laser triangulation. By processing the images acquired from the vision sensor, the geometrical features of the weld can be obtained. Through the visual analysis of the acquired 3D profiles of the weld, the presences as well as the positions and sizes of the weld defects can be accurately identified and therefore, the non-destructive weld quality inspection can be achieved. PMID:22344308

  9. Welded Scoria

    USGS Multimedia Gallery

    Samples of welded scoria. Scoria is another word for the ‘cinders’ that make up volcanic cinder cones. Roza Member, Columbia River Basalt Group. Southeast of Winona, WA. Cinder cones (otherwise known as scoria cones) are the most common type of volcano on Earth. They’re also one o...

  10. Development of sensor augmented robotic weld systems for aerospace propulsion system fabrication

    NASA Technical Reports Server (NTRS)

    Jones, C. S.; Gangl, K. J.

    1986-01-01

    In order to meet stringent performance goals for power and reuseability, the Space Shuttle Main Engine was designed with many complex, difficult welded joints that provide maximum strength and minimum weight. To this end, the SSME requires 370 meters of welded joints. Automation of some welds has improved welding productivity significantly over manual welding. Application has previously been limited by accessibility constraints, requirements for complex process control, low production volumes, high part variability, and stringent quality requirements. Development of robots for welding in this application requires that a unique set of constraints be addressed. This paper shows how robotic welding can enhance production of aerospace components by addressing their specific requirements. A development program at the Marshall Space Flight Center combining industrial robots with state-of-the-art sensor systems and computer simulation is providing technology for the automation of welds in Space Shuttle Main Engine production.

  11. Damage Tolerance Assessment of Friction Pull Plug Welds in an Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    McGill, Preston; Burkholder, Jonathan

    2012-01-01

    Friction stir welding is a solid state welding process used in the fabrication of cryogenic propellant tanks. Self-reacting friction stir welding is one variation of the friction stir weld process being developed for manufacturing tanks. Friction pull plug welding is used to seal the exit hole that remains in a circumferential self-reacting friction stir weld. A friction plug weld placed in a self-reacting friction stir weld results in a non-homogenous weld joint where the initial weld, plug weld, their respective heat affected zones and the base metal all interact. The welded joint is a composite plastically deformed material system with a complex residual stress field. In order to address damage tolerance concerns associated with friction plug welds in safety critical structures, such as propellant tanks, nondestructive inspection and proof testing may be required to screen hardware for mission critical defects. The efficacy of the nondestructive evaluation or the proof test is based on an assessment of the critical flaw size. Test data relating residual strength capability to flaw size in an aluminum alloy friction plug weld will be presented.

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

    Microsoft Academic Search

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

    2004-01-01

    Weld strength, formability, and impact resistance for joints on automotive steels is dependent on the underlying microstructure. A martensitic weld area is often a precursor to reduced mechanical performance. In this paper, efforts are made to predict underlying joint microstructures for a range of processing approaches, steel types, and gauges. This was done first by calculating cooling rates for some

  13. Demonstration of a Large-Scale Tank Assembly Via Circumferential Friction Stir Welds

    NASA Technical Reports Server (NTRS)

    Jones, Chip; Adams, Glynn; Colligan, Kevin; McCool, A. (Technical Monitor)

    2000-01-01

    Five (5) each 14-foot diameter circumferential FSWelds were conducted on the modified CWT, two (2) each pathfinder and three (3) each assembly welds Tapered circumferential welds were successfully demonstrated The use of a closeout anvil was successfully demonstrated during one of the pathfinder welds Considerable difficulty maintaining joint f it-up during the weld process Anvil deflections Hardware dimensional tolerances Inadequate clamping Variations in the heat sink characteristics of the circumferential anvil as compared to the test panel anvil

  14. Serviceability of the shrouding of K-300-240 turbine moving blades reconditioned by deposition welding

    SciTech Connect

    Gonserovskii, F.G.; Khotmirov, V.G.

    1983-01-01

    The authors discuss the reasons for selecting argon-arc deposition welding as the method for reconditioning worn seals on the shrouds of the moving blades of K-300-240 turbines. The problems of the welding process, metallographic analysis, the mechanical properties of the welded joints and the resistance to brittle and fatigue failure of the shrouds are examined. Recommendations are made for the selection of the filler metal and for taking account of the special features of the welding of shrouds.

  15. Preliminary study on pressure brazing and diffusion welding of Nb-1Zr to Inconel 718

    SciTech Connect

    Moore, T.J. (National Aeronautics and Space Administration, Cleveland, OH (USA). Lewis Research Center)

    1990-03-01

    Future space power systems may include Nb-1Zr/Inconel 718 dissimilar metal joints for operation at 1000 K for 60,000 h. In this study, the serviceability of pressure-brazed and diffusion-welded joints was investigated. Nickel-based metallic glass foil filler metals were used for brazing. Nickel and iron foils were used as diffusion welding interlayers. Joint soundness was determined by metallographic examination in the as-brazed and as-welded condition, after aging at 1000 K, and after thermal cycling. Brazed joints thermally cycled in the as-brazed condition and diffusion-welded joints were unsatisfactory because of cracking problems. Brazed joints may meet the service requirements if the joints are aged at 1000 K prior to thermal cycling.

  16. Preliminary study on pressure brazing and diffusion welding of Nb-1Zr to Inconel 718

    NASA Technical Reports Server (NTRS)

    Moore, T. J.

    1990-01-01

    Future space power systems may include Nb-1Zr/Inconel 718 dissimilar metal joints for operation at 1000 K for 60,000 h. The serviceability of pressure-brazed and diffusion-welded joints was investigated. Ni-based metallic glass foil filler metals were used for brazing. Ni and Fe foils were used as diffusion welding inter-layers. Joint soundness was determined by metallographic examination in the as-brazed and as-welded condition, after aging at 1000 K, and after thermal cycling. Brazed joints thermally cycled in the as-brazed condition and diffusion-welded joints were unsatisfactory because of cracking problems. Brazed joints may meet the service requirements if the joints are aged at 1000 K prior to thermal cycling.

  17. Analysis of weld-induced residual stresses and distortions in thin-walled cylinders

    Microsoft Academic Search

    Naeem Ullah Dar; Ejaz M. Qureshi; M. M. I. Hammouda

    2009-01-01

    Circumferential weld specifically in thin-walled structures is a common joint type in the fabrication of structural members\\u000a in aerospace, aeronautical and pressure vessel industries. This type of weld joint suffers various types of weld-induced residual\\u000a stress fields (hoop and axial) and deformation patterns (axial shrinkage, radial shrinkage). These imperfections have negative\\u000a effects on fabrication accuracies and result in low strength

  18. Friction Stir Welding Development at NASA, Marshall Space Flight Center

    NASA Technical Reports Server (NTRS)

    McGill, Preston; Gentz, Steve (Technical Monitor)

    2001-01-01

    Friction stir welding (FSW) is a solid state process that pan be used to join materials without melting. The process was invented by The Welding Institute (TWI), Cambridge, England. Friction stir welding exhibits several advantages over fusion welding in that it produces welds with fewer defects and higher joint efficiency and is capable of joining alloys that are generally considered non-weldable with a fusion weld process. In 1994, NASA-Marshall began collaborating with TWI to transform FSW from a laboratory curiosity to a viable metal joining process suitable for manufacturing hardware. While teamed with TWI, NASA-Marshall began its own FSW research and development effort to investigate possible aerospace applications for the FSW process. The work involved nearly all aspects of FSW development, including process modeling, scale-up issues, applications to advanced materials and development of tooling to use FSW on components of the Space Shuttle with particular emphasis on aluminum tanks. The friction stir welding process involves spinning a pin-tool at an appropriate speed, plunging it into the base metal pieces to be joined, and then translating it along the joint of the work pieces. In aluminum alloys the rotating speed typically ranges from 200 to 400 revolutions per minute and the translation speed is approximately two to five inches per minute. The pin-tool is inserted at a small lead angle from the axis normal to the work piece and requires significant loading along the axis of the tool. An anvil or reaction structure is required behind the welded material to react the load along the axis of the pin tool. The process requires no external heat input, filler material, protective shielding gas or inert atmosphere typical of fusion weld processes. The FSW solid-state weld process has resulted in aluminum welds with significantly higher strengths, higher joint efficiencies and fewer defects than fusion welds used to join similar alloys.

  19. Microhardness Testing of Aluminum Alloy Welds

    NASA Technical Reports Server (NTRS)

    Bohanon, Catherine

    2009-01-01

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

  20. Sensing the gas metal arc welding process

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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