Science.gov

Sample records for aluminum weld strength

  1. U-groove aluminum weld strength improvement

    NASA Technical Reports Server (NTRS)

    Verderaime, V.; Vaughan, R.

    1995-01-01

    Though butt-welds are among the most preferred joining methods in aerostructures, their strength dependence on inelastic mechanics is generally the least understood. This study investigated experimental strain distributions across a thick aluminum U-grooved weld and identified two weld process considerations for improving the multipass weld strength. The extreme thermal expansion and contraction gradient of the fusion heat input across the groove tab thickness produces severe peaking which induces bending under uniaxial loading. The filler strain-hardening deceased with increasing filler pass sequence, producing the weakest welds on the last pass side. Current welding schedules unknowingly compound these effects which reduce the weld strength. A de-peaking index model was developed to select filler pass thicknesses, pass numbers, and sequences to improve de-peaking in the welding process. Intent is to combine the strongest weld pass side with the peaking induced bending tension to provide a more uniform stress and stronger weld under axial tensile loading.

  2. U-Groove aluminum weld strength improvement

    NASA Technical Reports Server (NTRS)

    Verderaime, V.; Vaughan, R.

    1996-01-01

    Though butt-welds are among the most preferred joining methods in aerostructures, their strength dependence on inelastic mechanics is generally the least understood. This study investigated experimental strain distributions across a thick aluminum U-grooved weld and identified two weld process considerations for improving the multipass weld strength. The extreme thermal expansion and contraction gradient of the fusion heat input across the groove tab thickness produces severe peaking, which induces bending under uniaxial loading. The filler strain-hardening decreased with increasing filler pass sequence, producing the weakest welds on the last pass side. Current welding schedules unknowingly compound these effects which reduce the weld strength. A depeaking index model was developed to select filler pass thicknesses, pass numbers, and sequences to improve depeaking in the welding process. The intent is to combine the strongest weld pass side with the peaking induced bending tension to provide a more uniform stress and stronger weld under axial tensile loading.

  3. U-Groove Aluminum Weld Strength Improvement

    NASA Technical Reports Server (NTRS)

    Verderaime, V.; Vaughan, R.

    1997-01-01

    Though butt-welds are among the most preferred joining methods in aerostructures, their strength dependence on inelastic mechanics is generally the least understood. This study investigated experimental strain distributions across a thick aluminum U-grooved weld and identified two weld process considerations for improving the multipass weld strength. One is the source of peaking in which the extreme thermal expansion and contraction gradient of the fusion heat input across the groove tab thickness produces severe angular distortion that induces bending under uniaxial loading. The other is the filler strain hardening decreasing with increasing filler pass sequences, producing the weakest welds on the last weld pass side. Both phenomena are governed by weld pass sequences. Many industrial welding schedules unknowingly compound these effects, which reduce the weld strength. A depeaking index model was developed to select filler pass thickness, pass numbers, and sequences to improve depeaking in the welding process. The result was to select the number and sequence of weld passes to reverse the peaking angle such as to combine the strongest weld pass side with the peaking induced bending tension component side to provide a more uniform stress and stronger weld under axial tensile loading.

  4. Welding high-strength aluminum alloys at the Paton Institute

    SciTech Connect

    Kuchuk, Yatsenko, S.I.; Cherednichok, V.T.; Semenov, L.A. )

    1993-07-01

    The choice of the flash method for welding aluminum-alloy sections was governed first of all by the possibility of producing homogeneous-structure joints with the minimum amount of possible discontinuities and an insignificant metal strength loss in the welding zone. The aluminum alloy welding technology under consideration relies on the method of flash welding without using any protective atmospheres. The reason is first of all that a complex cross-sectional shape of workpieces being joined, their configuration and considerable overall dimensions make it difficult to use chambers of any type. Besides, conducted studies ascertained that in flash welding, in contrast to various fusion welding processes, the use of protective atmospheres or a vacuum is of little benefit. Here are the results of studying the specifics of thermal and electric processes in flashing, the physical features of weld joint formation, the basics of the welding technology, and the characteristics of the equipment.

  5. Corrosion Behavior of Friction Stir Welded High Strength Aluminum Alloys

    DTIC Science & Technology

    2002-01-18

    Angelo Guinasso, " Stress Corrosion Susceptibility in 7050 -T751 Aluminum Following Friction Stir Welding", Proc. First Friction Stir Welding Symposium...potential of the nugget. Susceptibility to stress corrosion cracking (SCC) was evaluated using the slow strain rate (SSR) method described in ASTM Standards...UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP015941 TITLE: Corrosion Behavior of Friction Stir Welded High Strength

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

    SciTech Connect

    Babu, N. Kishore; Cross, Carl E.

    2012-06-28

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

  7. High-strength laser welding of aluminum-lithium scandium-doped alloys

    NASA Astrophysics Data System (ADS)

    Malikov, A. G.; Ivanova, M. Yu.

    2016-11-01

    The work presents the experimental investigation of laser welding of an aluminum alloy (system Al-Mg-Li) and aluminum alloy (system Al-Cu-Li) doped with Sc. The influence of nano-structuring of the surface layer welded joint by cold plastic deformation on the strength properties of the welded joint is determined. It is founded that, regarding the deformation degree over the thickness, the varying value of the welded joint strength is different for these aluminum alloys. The strength of the plastically deformed welded joint, aluminum alloys of the Al-Mg-Li and Al-Cu-Li systems reached 0.95 and 0.6 of the base alloy strength, respectively.

  8. A hot-cracking mitigation technique for welding high-strength aluminum alloy

    SciTech Connect

    Yang, Y.P.; Dong, P.; Zhang, J.; Tian, X.

    2000-01-01

    A hot-cracking mitigation technique for gas tungsten arc welding (GTAW) of high-strength aluminum alloy 2024 is presented. The proposed welding technique incorporates a trailing heat sink (an intense cooling source) with respect to the welding torch. The development of the mitigation technique was based on both detailed welding process simulation using advanced finite element techniques and systematic laboratory experiments. The finite element methods were used to investigate the detailed thermomechanical behavior of the weld metal that undergoes the brittle temperature range (BTR) during welding. As expected, a tensile deformation zone within the material BTR region was identified behind the weld pool under conventional GTA welding process conventional GTA welding process conditions for the aluminum alloy studied. To mitigate hot cracking, the tensile zone behind the weld pool must be eliminated or reduce to a satisfactory level if the weld metal hot ductility cannot be further improved. With detailed computational modeling, it was found that by the introduction of a trailing heat sink at some distance behind the welding arc, the tensile strain rate with respect to temperature in the zone encompassing the BTR region can be significantly reduced. A series of parametric studies were also conducted to derive optimal process parameters for the trailing heat sink. The experimental results confirmed the effectiveness of the trailing heat sink technique. With a proper implementation of the trailing heat sink method, hot cracking can be completely eliminated in welding aluminum alloy 2024 (AA 2024).

  9. Towards the problem of forming full strength welded joints on aluminum alloy sheets. Part II: AA7475

    NASA Astrophysics Data System (ADS)

    Kalashnikova, Tatiana; Tarasov, Sergey; Eliseev, Alexander; Fortuna, Anastasiya

    2016-11-01

    The microstructural evolution in welded joint zones obtained both by friction stir welding and ultrasonic- assisted friction stir welding on dispersion hardened 7475 aluminum alloy has been examined together with the analysis of mechanical strength and microhardness. It was established that ultrasonic-assisted friction stir provided leveled microhardness profiles across the weld zones as well as higher joint strength as compared to those of standard friction stir welding.

  10. Change of Hot Cracking Susceptibility in Welding of High Strength Aluminum Alloy AA 7075

    NASA Astrophysics Data System (ADS)

    Holzer, M.; Hofmann, K.; Mann, V.; Hugger, F.; Roth, S.; Schmidt, M.

    High strength aluminum alloys are known as hard to weld alloys due to their high hot crack susceptibility. However, they have high potential for applications in light weight constructions of automotive industry and therefore it is needed to increase weldability. One major issue is the high hot cracking susceptibility. Vaporization during laser beam welding leads to a change of concentration of the volatile elements magnesium and zinc. Hence, solidification range of the weld and therefore hot cracking susceptibility changes. Additionally, different welding velocities lead to changed solidification conditions with certain influence on hot cracking. This paper discusses the influence of energy per unit length during laser beam welding of AA 7075 on the change of element concentration in the weld seam and the resulting influence on hot cracking susceptibility. Therefore EDS-measurements of weld seams generated with different velocities are performed to determine the change of element concentration. These quantitative data is used to numerically calculate the solidification range in order to evaluate its influence on the hot cracking susceptibility. Besides that, relative hot crack length and mechanical properties are measured. The results increase knowledge about welding of high strength aluminum alloy AA 7075 and hence support further developing of the welding process.

  11. The Strength and Characteristics of VPPA Welded 2219-T87 Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Jemian, W. A.

    1985-01-01

    A study of the variable polarity plasma arc (VPPA) welding process and those factors that control the structure and properties of VPPA welded aluminum alloy 2219-T87 was conducted. The importance of joint preparation, alignment of parts and welding process variables are already established. Internal weld defects have been eliminated. However, a variation of properties was found to be due to the size variation of interdendritic particles in the fusion zone. These particles contribute to the void formation process, which controls the ultimate tensile strength of the welded alloy. A variation of 150 microns in particle size correlated with a 10 ksi variation of ultimate tensile strength. It was found that all fracture surfaces were of the dimple rupture type, with fracture initiating within the fusion zone.

  12. 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.

  13. 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.

  14. Weld bead reinforcement removal: A method of improving the strength and ductility of peaked welds in 2219-T87 aluminum alloy plate

    NASA Technical Reports Server (NTRS)

    Lovoy, C. V.

    1979-01-01

    The results of a study to determine the degree to which the ductility and tensile properties of peaked welds could be enhanced by removing the reinforcing bead and fairing the weld nugget into the adjacent parent metal are presented. The study employed 2219-T87 aluminum alloy plate, tungsten inert gas (TIG) welding, and 2319 filler wire. The study concluded that significant improvements in peak weld, ultimate strength, and ductility can be obtained through removal and fairing of the weld reinforcing bead. The specimens so treated and tested in this program exhibited ultimate strength improvements of 2 to 3 percent for peak angles of 5.8 to 10 degrees and 10 to 22 percent for welds with peak angles of 11.7 to 16.9 degrees. It was also determined that removal of the weld bead enhanced the ability of peaked welds to straighten when exposed to cyclic loading at stress levels above the yield strength.

  15. Neural network prediction of aluminum-lithium weld strengths from acoustic emission amplitude data

    NASA Astrophysics Data System (ADS)

    Hill, Eric V. K.; Israel, Peggy L.; Knotts, Gregory L.

    1993-09-01

    AE flaw growth activity was monitored in aluminum-lithium weld specimens from the onset of tensile loading to failure. Data on actual ultimate strengths together with AE data from the beginning of loading up to 25 percent of the expected ultimate strength were used to train a backpropagation neural network to predict ultimate strengths. Architecturally, the fully interconnected network consisted of an input layer for the AE amplitude data, a hidden layer to accommodate failure mechanism mapping, and an output layer for ultimate strength prediction. The trained network was then applied to the prediction of ultimate strengths in the remaining six specimens. The worst case prediction error was found to be +2.6 percent.

  16. Neural network prediction of aluminum-lithium weld strengths from acoustic emission amplitude data

    NASA Technical Reports Server (NTRS)

    Hill, Eric V. K.; Israel, Peggy L.; Knotts, Gregory L.

    1993-01-01

    AE flaw growth activity was monitored in aluminum-lithium weld specimens from the onset of tensile loading to failure. Data on actual ultimate strengths together with AE data from the beginning of loading up to 25 percent of the expected ultimate strength were used to train a backpropagation neural network to predict ultimate strengths. Architecturally, the fully interconnected network consisted of an input layer for the AE amplitude data, a hidden layer to accommodate failure mechanism mapping, and an output layer for ultimate strength prediction. The trained network was then applied to the prediction of ultimate strengths in the remaining six specimens. The worst case prediction error was found to be +2.6 percent.

  17. Neural network prediction of aluminum-lithium weld strengths from acoustic emission amplitude data

    SciTech Connect

    Hill, E.V.K. . Aerospace Engineering Dept.); Israel, P.L. . Computer Science Dept.); Knotts, G.L. )

    1993-09-01

    Acoustic emission (AE) flaw growth activity was monitored in aluminum-lithium weld specimens from the onset of tensile loading to failure. Data on actual ultimate strengths together with AE data from the beginning of loading up to 25 percent of the expected ultimate strength were used to train a backpropagation neural network to predict ultimate strengths. Architecturally, the fully interconnected network consisted of an input layer for the AE amplitude data, a hidden layer to accommodate failure mechanism mapping, and an output layer for ultimate strength prediction. The trained network was then applied to the prediction of ultimate strengths in the remaining six specimens. The worst case prediction error was found to be +2.6 percent.

  18. Neural Network Prediction of Aluminum-Lithium Weld Strengths from Acoustic Emission Amplitude Data

    NASA Technical Reports Server (NTRS)

    Hill, Eric v. K.; Israel, Peggy L.; Knotts, Gregory L.

    1993-01-01

    Acoustic Emission (AE) flaw growth activity was monitored in aluminum-lithium weld specimens from the onset tensile loading to failure. Data on actual ultimate strengths together with AE data from the beginning of loading up to 25 percent of the expected ultimate strength were used to train a backpropagation neural network to predict ultimate strengths. Architecturally, the fully interconnected network consisted of an input layer for the AE amplitude data, a hidden layer to accommodate failure mechanism mapping, and an output layer for ultimate strength prediction. The trained network was the applied to the prediction of ultimate strengths in the remaining six specimens. The worst case prediction error was found to be +2.6 percent.

  19. Identifying Combination of Friction Stir Welding Parameters to Maximize Strength of Lap Joints of AA2014-T6 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Rajendrana, C.; Srinivasan, K.; Balasubramanian, V.; Balaji, H.; Selvaraj, P.

    2017-01-01

    AA2014 aluminum alloy (Al-Cu alloy) has been widely utilized in fabrication of lightweight structures like aircraft structures, demanding high strength to weight ratio and good corrosion resistance. The fusion welding of these alloys will lead to solidification problems such as hot cracking. Friction stir welding is a new solid state welding process, in which the material being welded does not melt and recast. Lot of research works have been carried out by many researchers to optimize process parameters and establish empirical relationships to predict tensile strength of friction stir welded butt joints of aluminum alloys. However, very few investigations have been carried out on friction stir welded lap joints of aluminum alloys. Hence, in this investigation, an attempt has been made to optimize friction stir lap welding (FSLW) parameters to attain maximum tensile strength using statistical tools such as design of experiment (DoE), analysis of variance (ANOVA), response graph and contour plots. By this method, it is found that maximum tensile shear fracture load of 12.76 kN can be achieved if a joint is made using tool rotational speed of 900 rpm, welding speed of 110 mm/min, tool shoulder diameter of 12 mm and tool tilt angle of 1.5°.

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

    SciTech Connect

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

    2014-12-30

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

  1. 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.

  2. Optimizing friction stir welding parameters to maximize tensile strength of AA2219 aluminum alloy joints

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

    AA2219 aluminium 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. In contrast to the fusion welding processes that are routinely used for joining structural aluminium alloys, the 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 non-consumable tool to generate frictional heat in the abutting surfaces. The welding parameters such as tool rotational speed, welding speed, axial force etc., and the tool pin profile play a major role in determining the joint strength. An attempt has been made here to develop a mathematical model to predict the tensile strength of friction stir welded AA2219 aluminium alloy by incorporating FSW process parameters. A central composite design with four factors and five levels has been used to minimize the number of experimental conditions. The response surface method (RSM) has been used to develop the model. The developed mathematical model has been optimized using the Hooke and Jeeves search technique to maximize the tensile strength of the friction stir welded AA2219 aluminium alloy joints.

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

    DOE PAGES

    Lim, Yong Chae; Squires, Lile; Pan, Tsung-Yu; ...

    2014-12-30

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  5. Laser welding of aluminum alloys

    SciTech Connect

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

    1997-03-01

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

  6. 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

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

    SciTech Connect

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

    2010-10-25

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

  8. 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.

  9. Shear strength of fillet welds in aluminum alloy 2219. [for use on the solid rocket motor and external tank

    NASA Technical Reports Server (NTRS)

    Lovoy, C. V.

    1978-01-01

    Fillet size is discussed in terms of theoretical or design dimensions versus as-welded dimensions, drawing attention to the inherent conservatism in the design load sustaining capabilities of fillet welds. Emphasis is placed on components for the solid rocket motor, external tank, and other aerospace applications. Problems associated with inspection of fillet welds are addresses and a comparison is drawn between defect counts obtained by radiographic inspection and by visual examination of the fracture plane. Fillet weld quality is related linearly to ultimate shear strength. Correlation coefficients are obtained by simple straight line regression analysis between the variables of ultimate shear strength and accumulative discontinuity summation. Shear strength allowables are found to be equivalent to 57 percent of butt weld A allowables (F sub tu.)

  10. Ultrasonic Additive Manufacturing: Weld Optimization for Aluminum 6061, Development of Scarf Joints for Aluminum Sheet Metal, and Joining of High Strength Metals

    NASA Astrophysics Data System (ADS)

    Wolcott, Paul J.

    Ultrasonic additive manufacturing (UAM) is a low temperature, solid-state manufacturing process that enables the creation of layered, solid metal structures with designed anisotropies and embedded materials. As a low temperature process, UAM enables the creation of active composites containing smart materials, components with embedded sensors, thermal management devices, and many others. The focus of this work is on the improvement and characterization of UAM aluminum structures, advancing the capabilities of ultrasonic joining into sheet geometries, and examination of dissimilar material joints using the technology. Optimized process parameters for Al 6061 were identified via a design of experiments study indicating a weld amplitude of 32.8 synum and a weld speed of 200 in/min as optimal. Weld force and temperature were not significant within the levels studied. A methodology of creating large scale builds is proposed, including a prescribed random stacking sequence and overlap of 0.0035 in. (0.0889 mm) for foils to minimize voids and maximize mechanical strength. Utilization of heat treatments is shown to significantly increase mechanical properties of UAM builds, within 90% of bulk material. The applied loads during the UAM process were investigated to determine the stress fields and plastic deformation induced during the process. Modeling of the contact mechanics via Hertzian contact equations shows that significant stress is applied via sonotrode contact in the process. Contact modeling using finite element analysis (FEA), including plasticity, indicates that 5000 N normal loads result in plastic deformation in bulk aluminum foil, while at 3000 N no plastic deformation occurs. FEA studies on the applied loads during the process, specifically a 3000 N normal force and 2000 N shear force, show that high stresses and plastic deformation occur at the edges of a welded foil, and base of the UAM build. Microstructural investigations of heat treated foils confirms

  11. Effect of Multi-repair Welding on Fatigue Performance of Aluminum Alloy Profile Welded Joint

    NASA Astrophysics Data System (ADS)

    Diao, You-De; Shi, Chun-Yuan; Tian, Hong-Lei

    2016-05-01

    Aluminum alloy profile has been widely used in the manufacture of the rail vehicles. But it's necessary for the repair welding of the welded joints to be conducted because some defects exist in the weld such as porosity, inclusions and incomplete penetrations in the welding processes. In this paper, the influence of the multi-repair welding of 6005A aluminum alloy profile butt welded joints on the fatigue performance are investigated based on the results of fatigue tests. The parameters of curves and the fatigue strength of the welded joints are calculated, and Goodman fatigue limit diagram is also obtained. The results show that fatigue strength of aluminum alloy profile butt welded joints, in condition of 107 cycle life, meet the standard requirement for the as-welded, repair welded state one time or two times respectively.

  12. Mechanical properties of laser welded aluminum alloys

    SciTech Connect

    Douglass, D.M.; Mazumder, J.

    1996-12-31

    The demand for lighter weight vehicles has prompted accelerated development in processing aluminum alloys for automobile structural applications. One of the current research initiatives centers on laser beam welding of aluminum alloys. Autogenous butt welds have been performed on Al 3003, 5754, 6111, and 6061-T6 plates with a 6 kW CO2 laser. For 6061, tensile data indicate about 60% of the base metal strength was attained in the as-welded condition, with a brittle fracture occurring through the weld. A post-weld heat treatment to the T6 condition resulted in a recovery of original ultimate tensile strengths, although these also failed in the weld. Hardness measurements of the post-weld T6 reveal a uniform hardness across the HAZ and fusion zone that is comparable to the original hardness. All 3003 welds fractured in the parent material in a ductile fashion. A high quality bead was consistently achieved with the 3003 alloy, whereas the other alloys demonstrated bead irregularities. SEM photographs reveal large, spherical pores, suggesting that they were formed by gas entrapment rather than by shrinkage.

  13. Properties of welded joints in laser welding of aeronautic aluminum-lithium alloys

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    The work presents the experimental investigation of the laser welding of the aluminum-lithium alloys (system Al-Mg-Li) and aluminum alloy (system Al-Cu-Li) doped with Sc. The influence of the nano-structuring of the surface layer welded joint by the cold plastic deformation method on the strength properties of the welded joint is determined. It is founded that, regarding the deformation degree over the thickness, the varying value of the welded joint strength is different for these aluminum alloys.

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

    NASA Astrophysics Data System (ADS)

    Horton, Karla Renee

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

  15. Tests show that aluminum welds are improved by bead removal

    NASA Technical Reports Server (NTRS)

    Hood, D. W.

    1967-01-01

    Tests with 2218-T87 aluminum alloy plate indicate improvements in strength, ductility, fatigue properties, and burst pressure result when one or both of the top and bottom weld beads are removed. There is, however, a drop in yield strength. The consistency of test data is considerably improved by weld bead removal.

  16. Influences of post weld heat treatment on tensile strength and microstructure characteristics of friction stir welded butt joints of AA2014-T6 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Rajendran, C.; Srinivasan, K.; Balasubramanian, V.; Balaji, H.; Selvaraj, P.

    2016-08-01

    Friction stir welded (FSWed) joints of aluminum alloys exhibited a hardness drop in both the advancing side (AS) and retreating side (RS) of the thermo-mechanically affected zone (TMAZ) due to the thermal cycle involved in the FSW process. In this investigation, an attempt has been made to overcome this problem by post weld heat treatment (PWHT) methods. FSW butt (FSWB) joints of Al-Cu (AA2014-T6) alloy were PWHT by two methods such as simple artificial aging (AA) and solution treatment followed by artificial aging (STA). Of these two treatments, STA was found to be more beneficial than the simple aging treatment to improve the tensile properties of the FSW joints of AA2014 aluminum alloy.

  17. Particulate and gaseous emissions when welding aluminum alloys.

    PubMed

    Cole, Homer; Epstein, Seymour; Peace, Jon

    2007-09-01

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

  18. Towards the problem of forming full strength welded joints on aluminum alloy sheets. Part I: AA2024

    NASA Astrophysics Data System (ADS)

    Fortuna, Sergey; Eliseev, Alexander; Kalashnikova, Tatiana; Kolubaev, Evgeny

    2016-11-01

    This work shows the microstructural evolution of solid solution grains and secondary phase precipitates in the stirring zones of ultrasonic-assisted friction stir welding (UAFSW) and standard friction stir welding (FSW). As shown, fine spherical AlMgCu precipitates dominate in FSW stirring zone whereas nanosized Al2MgCu (S-phase) platelets ones are the main finding in UAFSW sample. The mechanical strength of AA2024 is provided by precipitation of coherent intermetallic S-phase particles. The dominating amount of S-phase precipitates in UAFSW sample provided the ultimate stress level close to that of the base metal, i.e. 402 MPa as compared to 302 MPa of FSW sample. These values constituted 93 and 85%, respectively, of the base metal strength.

  19. Weld Repair of Thin Aluminum Sheet

    NASA Technical Reports Server (NTRS)

    Beuyukian, C. S.; Mitchell, M. J.

    1986-01-01

    Weld repairing of thin aluminum sheets now possible, using niobium shield and copper heat sinks. Refractory niobium shield protects aluminum adjacent to hole, while copper heat sinks help conduct heat away from repair site. Technique limits tungsten/inert-gas (TIG) welding bombardment zone to melt area, leaving surrounding areas around weld unaffected. Used successfully to repair aluminum cold plates on Space Shuttle, Commercial applications, especially in sealing fractures, dents, and holes in thin aluminum face sheets or clad brazing sheet in cold plates, heat exchangers, coolers, and Solar panels. While particularly suited to thin aluminum sheet, this process also used in thicker aluminum material to prevent surface damage near weld area.

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

    SciTech Connect

    Gates, W.G.; Jimenez, E.

    1981-04-01

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

  1. Effect of Weld Characteristic on Mechanical Strength of Laser-Arc Hybrid-Welded Al-Mg-Si-Mn Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Zhang, Chen; Gao, Ming; Jiang, Ming; Zeng, Xiaoyan

    2016-11-01

    Laser-arc hybrid welding (LAHW) was employed to improve the tensile properties of the joints of 8-mm-thick Al-Mg-Si-Mn alloy (AA6082) using Al-5Mg filler wire. The weld microstructures were examined by scanning electron microscope, electron backscattered diffraction, and transmission electron microscopy in detail. The LAHW joints with pore-free and high-tensile performances were obtained. The strength enhancement of the fusion zone and heat-affected zone in the LAHW joint was mainly attributed to the grain refinement strengthening and the precipitation strengthening, respectively. The microstructure characteristics were related to the effects of laser-arc interaction on the energy transfer within the molten pool. The arc caused the majority of laser energy to dissipate out of the keyhole, and then it reduced the heat input. The lower heat input refined the grain size, weakened the overaging effect, and thus improved the tensile strength.

  2. Theoretical Model of the Effect of Crack Tip Blunting on the Ultimate Tensile Strength of Welds in 2219-T87 Aluminum

    NASA Technical Reports Server (NTRS)

    Beil, R. J.

    1982-01-01

    A theoretical model representing blunting of a crack tip radius through diffusion of vacancies is presented. The model serves as the basis for a computer program which calculates changes, due to successive weld heat passes, in the ultimate tensile strength of 2219-T81 aluminum. In order for the model to yield changes of the same order in the ultimate tensile strength as that observed experimentally, a crack tip radius of the order of .001 microns is required. Such sharp cracks could arise in the fusion zone of a weld from shrinkage cavities or decohered phase boundaries between dendrites and the eutectic phase, or, possibly, from plastic deformation due to thermal stresses encountered during the welding process. Microstructural observations up to X2000 (resolution of about .1 micron) did not, in the fusion zone, show structural details which changed significantly under the influence of a heat pass, with the exception of possible small changes in the configuration of the interdendritic eutectic and in porosity build-up in the remelt zone.

  3. Comparing Laser Welding Technologies with Friction Stir Welding for Production of Aluminum Tailor-Welded Blanks

    SciTech Connect

    Hovanski, Yuri; Carsley, John; Carlson, Blair; Hartfield-Wunsch, Susan; Pilli, Siva Prasad

    2014-01-15

    A comparison of welding techniques was performed to determine the most effective method for producing aluminum tailor-welded blanks for high volume automotive applications. Aluminum sheet was joined with an emphasis on post weld formability, surface quality and weld speed. Comparative results from several laser based welding techniques along with friction stir welding are presented. The results of this study demonstrate a quantitative comparison of weld methodologies in preparing tailor-welded aluminum stampings for high volume production in the automotive industry. Evaluation of nearly a dozen welding variations ultimately led to down selecting a single process based on post-weld quality and performance.

  4. Interpretation of aluminum-alloy weld radiography

    NASA Technical Reports Server (NTRS)

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

    1971-01-01

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

  5. Nd:YAG laser welding aluminum alloys

    SciTech Connect

    Jimenez, E. Jr.

    1992-02-01

    Autogenous Nd:YAG laser welding wrought 4047, 1100, 3003, 2219, 5052, 5086, 5456, and 6061 and cast A356 aluminum alloys to cast A356 aluminum alloy in restrained annular weld joints was investigated. The welds were 12.7 mm (0.375 in.) and 9.5 mm (0.375 in.) diameter with approximately 0.30 mm (0.012 in.) penetration. This investigation determined 4047 aluminum alloy to be the optimum alloy for autogenous Nd:YAG laser welding to cast A356 aluminum alloy. This report describes the investigation and its results.

  6. Microstructure analysis in friction welding of copper and aluminum

    NASA Astrophysics Data System (ADS)

    Wibowo, A. G. Wahyu; Ismail, Rifky; Jamari, J.

    2016-04-01

    The Friction welding is a welding method with utilizing heat generated due to friction. Surfaces of two materials to be joined, one rotates the other being idle, is contacted by a pressure force. Friction on the second contact surface is done continuously so that the heat generated by the continuous friction will continue to rise. With the heat and the pressure force on the second surface to the second meeting of the material reaches its melting temperature then there is the process of welding. This paper examines the influence of the pressure force, rotational speed and contact time on friction welding of Aluminum (Al) and Copper (Cu) to the quality of welded joints. Friction welding process is performed on a friction welding machine that is equipped with the loading mechanism. The parameters used are the pressure force, rotational speed and friction time. Determination of the quality of welding is done by testing the tensile strength, hardness, and micro structure on the weld joint areas. The results showed that the friction welding quality is very good, this is evidenced by the results of a tensile strength test where the fault occurs outside the weld joint and increased violence in the weld joint. On the results visually cuts the welding area did not reveal any porosity so that it can be concluded that each metal contacts have melted perfectly and produce a connection with good quality.

  7. Filler wire for aluminum alloys and method of welding

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  8. Friction-Stir Welding of Aluminum For the Space Program

    NASA Technical Reports Server (NTRS)

    Jones, Clyde S.; Smelser, Jerry W. (Technical Monitor)

    2002-01-01

    The Marshall Space Flight Center is developing and characterizing the friction stir welding process for the Space Shuttle and other space programs. This revolutionary process, invented and patented by The Weld Institute in England, offers tremendous advantages for joining aluminum for high performance applications. It is particularly suited for advanced aluminum-lithium alloys, such as 2195, the primary structural alloy used in the External Tank. The friction stir welding process joins metals with minimal heat input, resulting in high-strength joints with high ductility. It is a simple process to demonstrate using a common milling machine for sample parts, but relatively expensive to implement on large-scale hardware, due to the high cost of tooling needed to handle the high forging pressures characteristic of the process. Recent developments at the Marshall Space Flight Center have demonstrated friction stir welding on linear joints up to 5 meters (15 ft.), with material thickness ranging between 2.5 mm and 16.5 mm (0.100" to 0.650"). High efficiency weld joints have been produced in aluminum from the 2000, 5000, and 6000 series alloy systems. A "retractable pin tool" system was patented by MSFC that allows use of friction stir welding for joints with changing material thickness, and with less rigid tooling than previously considered. This presentation will describe the details of alloys welded to-date and technical advances under development at MSFC. These developments could have substantial benefit to industrial applications for welding aluminum.

  9. Laser beam welding of 5182 aluminum alloys sheet.

    SciTech Connect

    Leong, K. H.; Sabo, K. R.; Altshuller, B.; Wilkinson, T. L.; Albright, C. E.; Technology Development; Alcan International Limited; Reynolds Metals Co.; Ohio State Univ.

    1999-06-01

    Conditions were determined for consistent coupling of a CO{sub 2} laser beam to weld 5182 aluminum alloy sheet. Full penetration butt and bead-on-plate welds on 0.8 and 1.8 mm sheets were performed. Process conditions examined included beam mode, spot size and irradiance, shielding gas flow, and edge quality and fitup. The observed weld quality variations with the different process parameters were consistent with physical phenomena and a threshold irradiance model. Optimal conditions were determined for obtaining consistent welds on 5182 alloy sheets. Formability and tensile tests were performed on the welded samples. All test failures occurred in the fusion zone. Reduction in formability and tensile strength of the welded samples are discussed with respect to weld profiles and process parameters.

  10. Hybrid manufacturing processes for fusion welding and friction stir welding of aerospace grade aluminum alloys

    NASA Astrophysics Data System (ADS)

    Gegesky, Megan Alexandra

    Friction stir welding and processing can provide for joints in aerospace grade aluminum alloys that have preferable material properties as compared to fusion welding techniques. Aerospace grade aluminum alloys such as AA2024-T3 and AA7075-T6 are considered non-weldable by traditional fusion welding techniques. Improved mechanical properties over previously used techniques are usually preferable for aerospace applications. Therefore, by combining traditional fusion welding and friction stir processing techniques, it could be plausible to create more difficult geometries in manufactured parts instead of using traditional techniques. While this combination of fusion welding and friction stir processing is not a new technology, its introduction to aerospace grade aluminum alloys as well as non-weldable alloys, is new. This is brought about by a lowered required clamping force required by adding a fusion weld before a friction stir processing technique. The changes in properties associated with joining techniques include: microstructural changes, changes in hardness, tensile strength, and corrosion resistance. This thesis illustrates these changes for the non-weldable AA2024-T351 and AA7075-T651 as well as the weldable alloy AA5052-H32. The microhardness, tensile strength and corrosion resistance of the four processing states: base material, fusion welded material, friction stir welded material, and friction stir processed fusion welded material is studied. The plausibility of this hybrid process for the three different materials is characterized, as well as plausible applications for this joining technique.

  11. Welding the four most popular aluminum alloys

    SciTech Connect

    Irving, B.

    1994-02-01

    The fact that business is good in aluminum welding is a sure sign that more manufacturers and fabricators are using GMA and GTA welding to build new products out of this lightweight nonferrous metal. Among the most widely specified weldable grades are Alloys 6061, 5083, 5052 and 5454. A rundown on these four alloys, including properties and selected applications, is provided. Any company working with aluminum for the first time needs to know something about these four alloys. Alloys of copper-magnesium-silicon combination, of which 6061 is one, are heat-treatable. The three 5XXX series alloys, on the other hand, are nonheat-treatable. According to P.B. Dickerson, consultant, Lower Burrell, Pa., 5083, because of its high magnesium content, is the easiest of the four alloys to arc weld. Dickerson put the cut-off point in weldability at 3.5% magnesium. To prevent cracking, he added, both 6061 and 5052 require much more filler metal than do the other two alloys. Alloy 6061 consists of 0.25Cu, 0.6Si, 1.0Mg, and 0.20Cr. The main applications for 6061 aluminum are structural, architectural, automotive, railway, marine and pipe. It has good formability, weldability, corrosion resistance and strength. Although the 6XXX series alloys are prone to hot cracking, this condition can be readily overcome by correct choice of joint design and electrode. The most popular temper for 6061 is T6, although the -T651, -T4, and -F temper are also popular. The -T651 temper is like a -T6 temper, only it has received some final stretch hardening. The -T4 temper has been solution heat-treated and quenched. The -F temper is in the as-fabricated condition.

  12. Ultrasonic Real-Time Quality Monitoring Of Aluminum Spot Weld Process

    NASA Astrophysics Data System (ADS)

    Perez Regalado, Waldo Josue

    The real-time ultrasonic spot weld monitoring system, introduced by our research group, has been designed for the unsupervised quality characterization of the spot welding process. It comprises the ultrasonic transducer (probe) built into one of the welding electrodes and an electronics hardware unit which gathers information from the transducer, performs real-time weld quality characterization and communicates with the robot programmable logic controller (PLC). The system has been fully developed for the inspection of spot welds manufactured in steel alloys, and has been mainly applied in the automotive industry. In recent years, a variety of materials have been introduced to the automotive industry. These include high strength steels, magnesium alloys, and aluminum alloys. Aluminum alloys have been of particular interest due to their high strength-to-weight ratio. Resistance spot welding requirements for aluminum vary greatly from those of steel. Additionally, the oxide film formed on the aluminum surface increases the heat generation between the copper electrodes and the aluminum plates leading to accelerated electrode deterioration. Preliminary studies showed that the real-time quality inspection system was not able to monitor spot welds manufactured with aluminum. The extensive experimental research, finite element modelling of the aluminum welding process and finite difference modeling of the acoustic wave propagation through the aluminum spot welds presented in this dissertation, revealed that the thermodynamics and hence the acoustic wave propagation through an aluminum and a steel spot weld differ significantly. For this reason, the hardware requirements and the algorithms developed to determine the welds quality from the ultrasonic data used on steel, no longer apply on aluminum spot welds. After updating the system and designing the required algorithms, parameters such as liquid nugget penetration and nugget diameter were available in the ultrasonic data

  13. Weld repair method for aluminum lithium seam

    NASA Technical Reports Server (NTRS)

    McGee, William Floyd (Inventor); Rybicki, Daniel John (Inventor)

    1998-01-01

    Aluminum-lithium plates are butt-welded by juxtaposing the plates and making a preliminary weld from the rear or root side of the seam. An initial weld is then made from the face side of the seam, which may cause a defect in the root portion. A full-size X-ray is made and overlain over the seam to identify the defects. The defect is removed from the root side, and rewelded. Material is then removed from the face side, and the cavity is rewelded. The procedure repeats, alternating from the root side to the face side, until the weld is sound.

  14. Heat Treatment of Friction-Stir-Welded 7050 Aluminum Plates

    NASA Technical Reports Server (NTRS)

    Petter, George E.; Figert, John D.; Rybicki, Daniel J.; Burns, Timothy

    2006-01-01

    A method of heat treatment has been developed to reverse some of the deleterious effects of friction stir welding of plates of aluminum alloy 7050. This alloy is considered unweldable by arc and high-energy-density beam fusion welding processes. The alloy can be friction stir welded, but as-welded workpieces exhibit low ductility, low tensile and yield strengths, and low resistance to stress corrosion cracking. Heat treatment according to the present method increases tensile and yield strengths, and minimizes or eliminates stress corrosion cracking. It also increases ductility. This method of heat treatment is a superior alternative to a specification-required heat treatment that caused the formation of large columnar grains, which are undesired. Workpieces subjected to the prior heat treatment exhibited elongations <2 percent, and standard three-point bend specimens shattered. The development of the present heat treatment method was guided partly by the principles that (1) by minimizing grain sizes and relieving deformation stresses, one can minimize or eliminate stress corrosion cracking and (2) the key to maximizing strength and eliminating residual stresses is to perform post-weld solution heating for as long a time as possible while incurring little or no development of large columnar grains in friction stir weld nuggets. It is necessary to perform some of the solution heat treatment (to soften the alloy and improve machine welding parameters) before welding. The following is an example of thickness- dependent pre- and post-weld heat treatments according to the present method: For plates 0.270 in. (approx.6.86 mm) thick milled from plates 4.5 in. (114.3 mm) thick, perform pre-weld solution heating at 890 F (477 C) for 1 hour, then cool in air. After friction stir welding, perform solution heating for 10 minutes, quench, hold at room temperature for 96 hours, then age at 250 F (121 C) for 5 hours followed by 325 F (163 C) for 27 hours.

  15. Recommended Aluminum Pipe Welding Procedures for Corps of Engineers Construction.

    DTIC Science & Technology

    1984-09-01

    tungsten -arc welding process) (4) Use of the extended land joint configuration; O-s (5) Use of current limits set by the Aluminum Association and ALCOA. ~0...Design Used for the 1-In. Schedule 10 Pipe 9 3 Typical Metal Weld Made Using Gas Tungsten -Arc Welding 11 4 Typical Small-Diameter Pipe Tensile Test...aluminum pipe commonly Approach used in military applications (Table 1). The gas Available literature on aluminum welding was tungsten -arc welding

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

    SciTech Connect

    Elangovan, K.; Balasubramanian, V.

    2008-09-15

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

  17. Fabrication of Aluminum Foam/Dense Steel Composite by Friction Stir Welding

    NASA Astrophysics Data System (ADS)

    Hangai, Yoshihiko; Koyama, Shinji; Hasegawa, Makoto; Utsunomiya, Takao

    2010-09-01

    Aluminum foam/dense steel composites were fabricated by friction stir welding (FSW). It is expected that both mixing a blowing agent into aluminum and bonding the aluminum precursor to steel can be conducted simultaneously by FSW. It was shown that although heat treatment of the precursor evolved a brittle intermetallic compound layer, the bonding strength of the interface consisting of the intermetallic compound layer was relatively high compared with the fracture strength of the aluminum foam itself.

  18. Welding of Aluminum Alloys to Steels: An Overview

    DTIC Science & Technology

    2013-08-01

    95] K. Kimapong1, T. Watanabe, Effect of welding process parameters on mechanical property of FSW lap joint between aluminum alloy and steel ...UNCLASSIFIED: Distribution Statement A. Approved for public release. 1 UNCLASSIFIED Welding of aluminum alloys to steels : an overview M. Mazar...welding methods for joining aluminum alloys to steels . The microstructural development, mechanical properties and application of the joints are discussed

  19. 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.

  20. 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

  1. A study on friction stir welding of 12mm thick aluminum alloy plates

    NASA Astrophysics Data System (ADS)

    Kumar, Deepati Anil; Biswas, Pankaj; Tikader, Sujoy; Mahapatra, M. M.; Mandal, N. R.

    2013-12-01

    Most of the investigations regarding friction stir welding (FSW) of aluminum alloy plates have been limited to about 5 to 6 mm thick plates. In prior work conducted the various aspects concerning the process parameters and the FSW tool geometry were studied utilizing friction stir welding of 12 mm thick commercial grade aluminum alloy. Two different simple-to-manufacture tool geometries were used. The effect of varying welding parameters and dwell time of FSW tool on mechanical properties and weld quality was examined. It was observed that in order to achieve a defect free welding on such thick aluminum alloy plates, tool having trapezoidal pin geometry was suitable. Adequate tensile strength and ductility can be achieved utilizing a combination of high tool rotational speed of about 2000 r/min and low speed of welding around 28 mm/min. At very low and high dwell time the ductility of welded joints are reduced significantly.

  2. Friction Pull Plug Welding in Aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Brooke, Shane A.; Bradford, Vann

    2012-01-01

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

  3. Aluminum alloys with improved strength

    NASA Technical Reports Server (NTRS)

    Deiasi, R.; Adler, P.

    1975-01-01

    Mechanical strength and stress corrosion of new BAR and 7050 alloys that include Zn instead of Cr have been studied and compared with those of 7075 aluminum alloy. Added mechanical strength of new alloys is attributed to finer grain size of 5 to 8 micrometers, however, susceptibility to stress corrosion attack is increased.

  4. 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.

  5. FRICTION STIR LAP WELDING OF ALUMINUM - POLYMER USING SCRIBE TECHNOLOGY

    SciTech Connect

    Upadhyay, Piyush; Hovanski, Yuri; Fifield, Leonard S.; Simmons, Kevin L.

    2015-02-16

    Friction Stir Scribe (FSS) technology is a relatively new variant of Friction Stir Welding (FSW) which enables lap joining of dissimilar material with very different melting points and different high temperature flow behaviors. The cutter scribe attached at the tip of FSW tool pin effectively cuts the high melting point material such that a mechanically interlocking feature is created between the dissimilar materials. The geometric shape of this interlocking feature determines the shear strength attained by the lap joint. This work presents first use of scribe technology in joining polymers to aluminum alloy. Details of the several runs of scribe welding performed in lap joining of ~3.175mm thick polymers including HDPE, filled and unfilled Nylon 66 to 2mm thick AA5182 are presented. The effect of scribe geometry and length on weld interlocking features is presented along with lap shear strength evaluations.

  6. Friction Pull Plug Welding in Aluminum Alloys

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  7. An investigation into geometry and microstructural effects upon the ultimate tensile strengths of butt welds

    NASA Technical Reports Server (NTRS)

    Gordon, Stephen S.

    1992-01-01

    A mathematical theory was evaluated empirically. This theory predicts weld ultimate tensile strength based on material properties and fusion line angles, mismatch, peaking, and weld widths. Welds were made on 1/4 and 1/2 in. aluminum 2219-T87, their geometries were measured, they were tensile tested, and these results were compared to theoretical predictions. Statistical analysis of results was performed to evaluate correlation of theory to results for many different categories of weld geometries.

  8. FSW of Aluminum Tailor Welded Blanks across Machine Platforms

    SciTech Connect

    Hovanski, Yuri; Upadhyay, Piyush; Carlson, Blair; Szymanski, Robert; Luzanski, Tom; Marshall, Dustin

    2015-02-16

    Development and characterization of friction stir welded aluminum tailor welded blanks was successfully carried out on three separate machine platforms. Each was a commercially available, gantry style, multi-axis machine designed specifically for friction stir welding. Weld parameters were developed to support high volume production of dissimilar thickness aluminum tailor welded blanks at speeds of 3 m/min and greater. Parameters originally developed on an ultra-high stiffness servo driven machine where first transferred to a high stiffness servo-hydraulic friction stir welding machine, and subsequently transferred to a purpose built machine designed to accommodate thin sheet aluminum welding. The inherent beam stiffness, bearing compliance, and control system for each machine were distinctly unique, which posed specific challenges in transferring welding parameters across machine platforms. This work documents the challenges imposed by successfully transferring weld parameters from machine to machine, produced from different manufacturers and with unique control systems and interfaces.

  9. Weld Growth Mechanisms and Failure Behavior of Three-Sheet Resistance Spot Welds Made of 5052 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Li, Yang; Yan, Fuyu; Luo, Zhen; Chao, Y. J.; Ao, Sansan; Cui, Xuetuan

    2015-06-01

    This paper investigates the weld nugget formation in three-sheet aluminum alloy resistance spot welding. The nugget formation process in three equal thickness sheets and three unequal thickness sheets of 5052 aluminum alloy were studied. The results showed that the nugget was initially formed at the workpiece/workpiece interfaces (i.e., both upper interface and lower interface). The two small nuggets then grew along the radial direction and axial direction (welding direction) as the welding time increased. Eventually, the two nuggets fused into one large nugget. During the welding process, the Peltier effect between the Cu-Al caused the shift of the nugget in the welding direction. In addition, the mechanical strength and fracture mode of the weld nuggets at the upper and lower interfaces were also studied using tensile shear specimen configuration. Three failure modes were identified, namely interfacial, mixed, and pullout. The critical welding time and critical nugget diameter corresponding to the transitions of these modes were investigated. Finally, an empirical failure load formula for three-sheet weld similar to two-sheet spot weld was developed.

  10. Aluminum U-groove weld enhancement based on experimental stress analyses

    NASA Technical Reports Server (NTRS)

    Verderaime, V.; Vaughan, R.

    1995-01-01

    Though butt-welds are among the most preferred joining methods in aerostructures because of their sealing and assembly integrity and general elastic performance; their inelastic mechanics are generally the least understood. This study investigated experimental strain distributions across a thick aluminum U-grooved weld and identified two weld process considerations for improving the multipass weld strength. The extreme thermal expansion and contraction gradient of the fusion heat input across the tab thickness between the grooves produce severe peaking, which induces bending moment under uniaxial loading. The filler strain hardening decreased with increasing filler pass sequence. These combined effects reduce the weld strength, and a depeaking index model was developed to select filler pass thicknesses, pass numbers, and sequences to improve the welding process results over the current normal weld schedule.

  11. Reasons for superior mechanical and corrosion properties of 2219 aluminum alloy electron beam welds

    SciTech Connect

    Koteswara Rao, S.R. . E-mail: sajjarkr@yahoo.com; Madhusudhan Reddy, G.; Srinivasa Rao, K.; Kamaraj, M.; Prasad Rao, K.

    2005-11-15

    Electron beam welds of aluminum alloy 2219 offer much higher strength compared to gas tungsten arc welds of the same alloy and the reasons for this have not been fully explored. In this study both types of welds were made and mechanical properties were evaluated by tensile testing and pitting corrosion resistance by potentio dynamic polarization tests. It is shown that electron beam welds exhibit superior mechanical and corrosion properties. The weld metals have been characterized by scanning electron microscopy; transmission electron microscopy and electron probe micro analysis. Presence of partially disintegrated precipitates in the weld metal, finer micro porosity and uniform distribution of copper in the matrix were found to be the reasons for superior properties of electron beam welds apart from the fine equiaxed grain structure. Transmission electron micrographs of the heat affected zones revealed the precipitate disintegration and over aging in gas tungsten arc welds.

  12. 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.

  13. High Strength Steel Welding Research

    DTIC Science & Technology

    2007-11-02

    ical A nalysis ............................................................................ 124 4.6.1 Inductively Coupled Plasm a...welding, the heat source is not stationary ................................................................................................ 19 0 Figure 5...primary and secondary phases in weld m etal inclusions ................................................................. 52 Figure 13: HAC in heat

  14. Microstructures and Mechanical Properties of Friction Stir Spot Welded Aluminum Alloy AA2014

    NASA Astrophysics Data System (ADS)

    Babu, S.; Sankar, V. S.; Janaki Ram, G. D.; Venkitakrishnan, P. V.; Madhusudhan Reddy, G.; Prasad Rao, K.

    2013-01-01

    Friction stir spot welding (FSSW) is a relatively recent development, which can provide a superior alternative to resistance spot welding and riveting for fabrication of aluminum sheet metal structures. In the current work, FSSW experiments were conducted in 3-mm thick sheets of aluminum alloy 2014 in T4 and T6 conditions, with and without Alclad layers. The effects of tool geometry and welding process parameters on joint formation were investigated. A good correlation between process parameters, bond width, hook height, joint strength, and fracture mode was observed. The presence of Alclad layers and the base metal temper condition were found to have no major effect on joint formation and joint strength. Friction stir spot welds produced under optimum conditions were found to be superior to riveted joints in lap-shear and cross-tension tests. The prospects of FSSW in aluminum sheet metal fabrication are discussed.

  15. Effect of Welding Speeds on Mechanical Properties of Level Compensation Friction Stir Welded 6061-T6 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Wen, Quan; Yue, Yumei; Ji, Shude; Li, Zhengwei; Gao, Shuangsheng

    2016-04-01

    In order to eliminate the flash, arc corrugation and concave in weld zone, level compensation friction stir welding (LCFSW) was put forward and successfully applied to weld 6061-T6 aluminum alloy with varied welding speed at a constant tool rotational speed of 1,800 rpm in the present study. The glossy joint with equal thickness of base material can be attained, and the shoulder affected zone (SAZ) was obviously reduced. The results of transverse tensile test indicate that the tensile strength and elongation reach the maximum values of 248 MPa and 7.1% when the welding speed is 600 mm/min. The microhardness of weld nugget (WN) is lower than that of base material. The tensile fracture position locates at the heat affected zone (HAZ) of the advancing side (AS), where the microhardness is the minimum. The fracture surface morphology represents the typical ductile fracture.

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

    PubMed

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

    2013-01-01

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

  17. CO2 laser beam welding of 6061-T6 aluminum alloy thin plate

    NASA Astrophysics Data System (ADS)

    Hirose, Akio; Kobayashi, Kojiro F.; Todaka, Hirotaka

    1997-12-01

    Laser beam welding is an attractive welding process for age-hardened aluminum alloys, because its low heat input minimizes the width of weld fusion and heat-affected zones (HAZs). In the present work, 1-mm-thick age-hardened Al-Mg-Si alloy, 6061-T6, plates were welded with full penetration using a 2.5-kW CO2 laser. Fractions of porosity in the fusion zones were less than 0.05 pct in bead-on-plate welding and less than 0.2 pct in butt welding with polishing the groove surface before welding. The width of a softened region in the-laser beam welds was less than 1/4 times that of a tungsten inert gas (TIG) weld. The softened region is caused by reversion of strengthening β″ (Mg2Si) precipitates due to weld heat input. The hardness values of the softened region in the laser beam welds were almost fully recovered to that of the base metal after an artificial aging treatment at 448 K for 28.8 ks without solution annealing, whereas those in the TIG weld were not recovered in a partly reverted region. Both the bead-on-plate weld and the butt weld after the postweld artificial aging treatment had almost equivalent tensile strengths to that of the base plate.

  18. 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.

  19. Study of inertia welding: the sensitivity of weld configuration and strength to variations in welding parameters

    SciTech Connect

    Mote, M.W.

    1981-12-01

    An experiment is described which is designed to demonstrate the forgiveness of inertia welding, that is, the relative insensitivity of weld strength to variations in energy (rotational speed of parts) and axial force. Although easily observed variations in the welding parameters produced easily observed changes in weldment configuration and changes in dimension (upset), only extremes in parameters produced changes in weld strength. Consequently, process monitoring and product inspection would be sufficient for quality assurance in a production environment.

  20. Fatigue performance of welded aluminum deck structures

    SciTech Connect

    Haagensen, P.J.; Ranes, M.; Kluken, A.O.; Kvale, I.

    1996-12-01

    Aluminum alloys are used increasingly in load carrying structures where low weight and low maintenance costs are at a premium. Helicopter decks, structures for living quarters and personnel transfer bridges between platforms are examples of offshore applications. While these structures are not usually subjected to high fatigue loads, the increasing use of aluminum in high speed ships, and more recently in highway bridge structures, makes the question of fatigue performance more important. In this paper the fatigue properties of small scale weldments in an AA6005 alloy are compared with the results of fatigue tests on full scale sections of welded extrusions in the same material, which were used in an aluminum bridge deck structure. The fatigue performance is also compared with the fatigue clauses in the new British design code BS8118 for aluminium structures and the proposed Eurocode 9. The prospects of using a new joining technique, friction stir welding (FSW), in the production of large scale panels for deck and ship hull structures is discussed. The FSW process is described briefly, and some fatigue test data are presented.

  1. 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.

  2. Friction Stir Welding of Aluminum and Titanium Alloys

    DTIC Science & Technology

    2007-11-02

    What is this? Jata/US Air Force Typical FSW Tools W-Re tool in collet- style tool holder. Used for welding steels and Ti alloys 3-piece self...Friction Stir Welding of Aluminum and Titanium alloys NATO Advanced Research Workshop Metallic Materials with High Structural Efficiency Kyiv...valid OMB control number. 1. REPORT DATE 18 MAR 2004 2. REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Friction Stir Welding of Aluminum

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

    PubMed Central

    Oyyaravelu, Ramachandran; Kuppan, Palaniyandi; Arivazhagan, Natarajan

    2016-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

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

    DTIC Science & Technology

    2013-08-01

    and around particle inclusions within the WZ. In the case of FSW aluminum to steel , the structure often seen is one of steel particles dispersed...the microstructure and mechanical performance of dissimilar FSWs between aluminum and steel , this study focuses on the characterization of the...MICROSTRUCTURAL CHARACTERIZATION OF FRICTION STIR WELDED ALUMINUM - STEEL JOINTS By ERIN ELIZABETH PATTERSON A thesis submitted in

  6. Shear Strength of Aluminum Oxynitride

    NASA Astrophysics Data System (ADS)

    Dandekar, Dattatraya P.; Vaughan, Brian A. M.; Proud, William G.

    2007-06-01

    Aluminum oxynitride (AlON) is a transparent, polycrystalline cubic spinel. The results of investigations^1-4 on shock response of AlON permit determination of the equation of state, and shear strength retained under shock compression. Whereas the values of the HEL of AlON holds no surprises, the inelastic response of AlON reported in Ref. 1-4 differ significantly and is stress dependent. The results of Ref. 1-2 show that AlON retains a shear strength of 3 to 4 GPa when shocked up to around 20 GPa, but the results of Ref, 3-4 seem to suggest a possible loss of shear strength when shocked to 16 GPa and beyond. Our analysis examines the observed differences in the inelastic response of AlON reported in these four studies . 1. J. U. Cazamias, et. al., in Fundamental Issues and Applications of Shock-Wave and High Strain Rate Phenomena, Eds. Staudhammer, Murr, and Meyers, Elsevier, NY, 173 (2001). 2. B. A. M. Vaughn, et.al., Shock Physics, Cavendish Laboratory, Report SP/1092 (2001) 3. T. Sekine, et.al., J. Appl. Phys. 94, 4803 (2003). 4. T. F. Thornhill, et.al., Shock Compression of Matter-2005, Eds. Furnish, Elert, Russell, White, AIP, NY, 143 (2006).

  7. Improved microstructure and mechanical properties in gas tungsten arc welded aluminum joints by using graphene nanosheets/aluminum composite filler wires.

    PubMed

    Fattahi, M; Gholami, A R; Eynalvandpour, A; Ahmadi, E; Fattahi, Y; Akhavan, S

    2014-09-01

    In the present study, different amounts of graphene nanosheets (GNSs) were added to the 4043 aluminum alloy powders by using the mechanical alloying method to produce the composite filler wires. With each of the produced composite filler wires, one all-weld metal coupon was welded using the gas tungsten arc (GTA) welding process. The microstructure, mechanical properties and fracture surface morphology of the weld metals have been evaluated and the results are compared. As the amount of GNSs in the composition of filler wire is increased, the microstructure of weld metal was changed from the dendritic structure to fine equiaxed grains. Furthermore, the tensile strength and microhardness of weld metal was improved, and is attributed to the augmented nucleation and retarded growth. From the results, it was seen that the GNSs/Al composite filler wire can be used to improve the microstructure and mechanical properties of GTA weld metals of aluminum and its alloys.

  8. Ultrasonic Impact Treatment to Improve Stress Corrosion Cracking Resistance of Welded Joints of Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Yu, J.; Gou, G.; Zhang, L.; Zhang, W.; Chen, H.; Yang, Y. P.

    2016-07-01

    Stress corrosion cracking is one of the major issues for welded joints of 6005A-T6 aluminum alloy in high-speed trains. High residual stress in the welded joints under corrosion results in stress corrosion cracking. Ultrasonic impact treatment was used to control the residual stress of the welded joints of 6005A-T6 aluminum alloy. Experimental tests show that ultrasonic impact treatment can induce compressive longitudinal and transverse residual stress in the welded joint, harden the surface, and increase the tensile strength of welded joints. Salt-fog corrosion tests were conducted for both an as-welded sample and an ultrasonic impact-treated sample. The surface of the treated sample had far fewer corrosion pits than that of the untreated sample. The treated sample has higher strength and lower tensile residual stress than the untreated sample during corrosion. Therefore, ultrasonic impact treatment is an effective technique to improve the stress corrosion cracking resistance of the welded joints of 6005A-T6 aluminum alloy.

  9. Enabling high speed friction stir welding of aluminum tailor welded blanks

    NASA Astrophysics Data System (ADS)

    Hovanski, Yuri

    Current welding technologies for production of aluminum tailor-welded blanks (TWBs) are utilized in low-volume and niche applications, and have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailor-welded blank technology for aluminum alloys at high-volumes. While friction stir welding (FSW) has traditionally been applied at linear velocities less than one meter per minute, high volume production applications demand the process be extended to higher velocities more amenable to cost sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low to moderate welding velocities do not directly translate to high speed linear friction stir welding. Therefore, in order to facilitate production of high volume aluminum FSW components, parameters were developed with a minimum welding velocity of three meters per minute. With an emphasis on weld quality, welded blanks were evaluated for post-weld formability using a combination of numerical and experimental methods. Evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum tailor-welded blanks, which provided validation of the numerical and experimental analysis of laboratory scale tests.

  10. Joining Uranium to Aluminum using Electron Beam Welding and an Explosively Clad Niobium Interlayer

    SciTech Connect

    Elmer, J W; Terrill, P; Brasher, D; Butler, D

    2001-06-12

    A uranium alloy was joined to a high strength aluminum alloy using a commercially pure niobium interlayer. Joining of the Nb interlayer to the aluminum alloy was performed using an explosive welding process, while joining the Nb interlayer to the uranium alloy was performed using an electron beam welding process. Explosive welding was selected to bond the Nb to the aluminum alloy in order to minimize the formation of brittle intermetallic phases. Electron beam welding was selected to join the Nb to the uranium alloy in order to precisely control melting so as to minimize mixing of the two metals. A Modified Faraday Cup (MFC) technique using computer-assisted tomography was employed to determine the power distribution of the electron beam so that the welding parameters could be directly transferred to other welding machines. Optical microscopy, scanning electron microscopy, microhardness, and tensile testing of the welds were used to characterize the resulting joints. This paper presents the welding techniques and processing parameters that were developed to produce high integrity ductile joints between these materials.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  12. Tool For Friction Stir Tack Welding of Aluminum Alloys

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  13. Residual Stress and Fatigue Strength of Hybrid Laser-MIG-Welded A7N01P-T4

    NASA Astrophysics Data System (ADS)

    Wang, Qiuying; Chen, Hui; Qiu, Peixian; Zhu, Zongtao

    2017-02-01

    A7N01P-T4 aluminum alloy is widely used in some important welded components of high-speed trains. The hybrid laser-metal inert gas (MIG) welding process was studied to solve problems associated with the MIG welding process, such as low welding efficiency, high residual stress and deformation, and serious loss of strength. A high-speed camera, a voltage and current collection system, and NI DAQ were used to acquire arc profiles, welding voltage, and welding current simultaneously. Thermal cycle tests were carried out. Residual stresses induced by the welding process and fatigue strength of the joint were investigated. Large-size fatigue specimens were used in fatigue tests. The results show that the energy of the hybrid welding process is focused, and the power density of hybrid welding process is intense. The heat input per unit of the hybrid welding process is only half of that of the MIG welding process. Compared with the MIG welded joint, the overall residual stress level of the hybrid-welded joint is lower. The peak longitudinal stress of the hybrid-welded joint is reduced by 20 pct. The fatigue strength of hybrid joints is 14 pct higher than that of MIG-welded joints. Narrow weld and HAZ, weak softening behavior, and low residual stress level are the causes of the improvement of fatigue strength.

  14. The feasibility of producing aluminum-lithium structures for cryogenic tankage applications by laser beam welding

    NASA Technical Reports Server (NTRS)

    Martukanitz, R. P.; Lysher, K. G.

    1993-01-01

    Aluminum-lithium alloys exhibit high strength, high elastic modulus, and low density as well as excellent cryogenic mechanical properties making them ideal material candidates for cryogenic tanks. NASA has proposed the use of 'built-up' structure for panels fabricated into cryogenic tanks replacing current conventional machining. Superplastically formed stiffeners would be joined to sheet (tank skin) that had been roll formed to the radius of the tank in order to produce panels. Aluminum-lithium alloys of interest for producing the built-up structure include alloy 2095-T6 stiffeners to 2095-T8 sheet and alloy 8090-T6 stiffeners to 2090-T83 sheet. Laser welding, with comparable joint properties, offers the following advantages over conventional welding: higher production rates, minimal degradation within the heat affected zones, and full process automation. This study established process parameters for laser beam welding, mechanical property determinations, metallographic characterization, and fabrication of prototype panels. Tensile tests representing partial penetration of the skin alloys provided joint efficiencies between 65 and 77 percent, depending upon alloy and degree of penetration. Results of tension shear tests of lap welds indicated that the combination of 2095-T6 to 2090-T8 exhibited significantly higher weld shear strength at the interface in comparison to welds of 8090-T6 to 2090-T83. The increased shear strength associated with 2095 is believed to be due to the alloy's ability to precipitation strengthening (naturally age) after welding.

  15. High-Speed Friction-Stir Welding To Enable Aluminum Tailor-Welded Blanks

    SciTech Connect

    Hovanski, Yuri; Upadhyay, Piyush; Carsley, John; Luzanski, Tom; Carlson, Blair; Eisenmenger, Mark; Soulami, Ayoub; Marshall, Dustin; Landino, Brandon; Hartfield-Wunsch, Susan

    2015-05-01

    Current joining technologies for automotive aluminum alloys are utilized in low-volume and niche applications, and have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailor-welded blank technology for aluminum alloys at high-volumes. While friction stir welding has been traditionally applied at linear velocities less than one meter per minute, high volume production applications demand the process be extended to higher velocities more amenable to cost sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low to moderate welding velocities do not directly translate to high speed linear friction stir welding. Therefore, in order to facilitate production of high volume aluminum welded components, parameters were developed with a minimum welding velocity of three meters per minute. With an emphasis on weld quality, welded blanks were evaluated for post-weld formability utilizing a combination of numerical and experimental methods. Evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum tailor-welded blanks, which provided validation of the numerical and experimental analysis of laboratory scale tests.

  16. Diode laser welding of aluminum to steel

    SciTech Connect

    Santo, Loredana; Quadrini, Fabrizio; Trovalusci, Federica

    2011-05-04

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

  17. Laser welding of automotive aluminum alloys to achieve defect-free, structurally sound and reliable welds

    SciTech Connect

    DebRoy, T.

    2000-11-17

    The objective of this program was to seek improved process control and weldment reliability during laser welding of automotive aluminum alloys while retaining the high speed and accuracy of the laser beam welding process. The effects of various welding variables on the loss of alloying elements and the formation of porosity and other geometric weld defects such as underfill and overfill were studied both experimentally and theoretically.

  18. Welding of aluminum alloy with high power direct diode laser

    NASA Astrophysics Data System (ADS)

    Abe, Nobuyuki; Morikawa, Atsuhito; Tsukamoto, Masahiro; Maeda, Koichi; Namba, Keizo

    2003-06-01

    Characterized by high conversion efficiency, small size, light weight and a long lifetime, high power diode lasers are currently being developed for application to various types of metal fabrication, such as welding. In this report, a 4kW high power direct diode laser was used to weld aluminum alloys, which are the focus of increasing attention from the automobile industry because of their light weight, high formability and easy recyclability. The applicability of a direct diode laser to aluminum alloy bead-on plate, butt and lap-fillet welding was studied under various welding conditions. A sound bead without cracks was successfully obtained when 1 mm thick aluminum alloy was welded by bead-on welding at a speed of 12m/min. Moreover, the bead cross section was heat conduction welding type rather than the keyhole welding type of conventional laser welding. Investigation of the welding phenomena with a high-speed video camera showed no spattering or laser plasma, so there was no problem with laser plasma damaging the focusing lens despite the diode laser's short focusing distance.

  19. Mechanical Properties of Aluminum Tailor Welded Blanks at Superplastic Temperatures

    SciTech Connect

    Davies, Richard W.; Vetrano, John S.; Smith, Mark T.; Pitman, Stan G.

    2002-10-06

    This paper describes an investigation of the mechanical properties of weld material in aluminum tailor welded blanks (TWB) at superplastic temperatures and discusses the potential application of TWBs in superplastic forming operations. Aluminum TWBs consist of multiple sheet materials of different thickness or alloy that are butt-welded together into a single, variable thickness blank. To evaluate the performance of the weld material in TWBs, a series of tensile tests were conducted at superplastic temperatures with specimens that contained weld material in the gage area. The sheet material used in the study was Sky 5083 aluminum alloy, which was joined to produce the TWBs by gas tungsten arc welding using an AA5356 filler wire. The experimental results show that, in the temperature range of 500?C to 550?C and at strain rates ranging from 10-4 sec-1 to 10-2 sec-1, the weld material has a higher flow stress and lower ductility than the monolithic sheet material. The weld material exhibited elongations of 40% to 60% under these conditions, whereas the monolithic sheet achieved 220% to 360% elongation. At the same temperatures and strain rates, the weld material exhibited flow stresses 1.3 to 4 times greater than the flow stress in the monolithic sheet. However, the weld material did show a substantial increase in the strain rate sensitivity and ductility when compared to the same material formed at room temperature.

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

    DTIC Science & Technology

    1998-02-01

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

  1. Renewal of corrosion protection of coated aluminum after welding

    NASA Technical Reports Server (NTRS)

    Higgins, R. H.

    1969-01-01

    Effectiveness of conversion coatings designed to protect aluminum alloys against atmospheric corrosion is reduced after exposure to high temperature or welding. Damaged coating should be manually stripped six inches from the weld and then recoated by sponge or spray with the original solution.

  2. Aluminum Tailor-Welded Blanks for High Volume Automotive Applications

    SciTech Connect

    Hovanski, Yuri; Upadhyay, Piyush; Pilli, Siva Prasad; Carlson, Blair; Carsley, John; Hartfield-Wunsch, Susan; Eisenmenger, Mark

    2014-02-04

    A Design of Experiment based approach is used to systematically investigate relationships between 8 different welding factors (4 related to tool geometry, 4 related to weld process control) and resulting weld properties including strength, elongation and formability in 1.2mm-2mm thick friction stir welding of AA5182-O for TWB application. The factors that result in most significant effects are elucidated. The interactions between several key factors like plunge depth, tool tilt, pin feature and pin length on the overall weld quality is discussed. Appropriate levels of factors that lead to excellent weld properties are also identified.

  3. Friction Stir Spot Welding of Advanced High Strength Steels

    SciTech Connect

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

    2009-11-13

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

  4. Welded repairs of punctured thin-walled aluminum pressure vessels

    NASA Technical Reports Server (NTRS)

    Jones, D. J.

    1969-01-01

    Punctures in thin-walled aluminum pressure vessels are repaired by plugging the hole with an interference-fit disc and welding the unit. The repaired vessels withstood test pressures in excess of vessel ultimate design values for 2-, 4-, and 6-inch holes in 0.202-inch-thick aluminum alloy parent material.

  5. Friction Stir Welding of Age-Hardenable Aluminum Alloys: A Parametric Approach Using RSM Based GRA Coupled With PCA

    NASA Astrophysics Data System (ADS)

    Vijayan, D.; Rao, V. S.

    2014-04-01

    Age-hardenable aluminum alloys, primarily used in the aerospace, automobile and marine industries (2×××, 6××× and 7×××), can be welded using solid-state welding techniques. Friction stir welding is an emerging solid-state welding technique used to join both similar and dissimilar materials. The strength of a friction stir welded joint depends on the joining process parameters. Therefore, a combination of the statistical techniques of a response surface methodology based on a grey relational analysis coupled to a principal component analysis was proposed to select the process parameters suitable for joining AA 2024 and AA 6061 aluminum alloys via friction stir welding. The significant process parameters, such as rotational speed, welding speed, axial load and pin shapes (PS) were considered during the statistical experiment. The results indicate that the square PS plays a vital role and yields an ultimate tensile strength of 141 MPa for an elongation of 12 % versus cylinder and taper pin profiles. The root cause for joint strength loss and fracture mode was analyzed using scanning electron microscopy. Severe material flow during macro defects, such as pin holes and porosity, degrades the joint strength by approximately 44 % for AA 2024 and 51 % for AA 6061 fabricated FS-welded aluminum alloys relative to the base material. The results of this approach are useful for accurately controlling the response and optimize the process parameters.

  6. High-Speed Friction-Stir Welding to Enable Aluminum Tailor-Welded Blanks

    NASA Astrophysics Data System (ADS)

    Hovanski, Yuri; Upadhyay, Piyush; Carsley, John; Luzanski, Tom; Carlson, Blair; Eisenmenger, Mark; Soulami, Ayoub; Marshall, Dustin; Landino, Brandon; Hartfield-Wunsch, Susan

    2015-05-01

    Current welding technologies for production of aluminum tailor-welded blanks (TWBs) are utilized in low-volume and niche applications, and they have yet to be scaled for the high-volume vehicle market. This study targeted further weight reduction, part reduction, and cost savings by enabling tailor-welded blank technology for aluminum alloys at high volumes. While friction-stir welding (FSW) has been traditionally applied at linear velocities less than 1 m/min, high-volume production applications demand the process be extended to higher velocities more amenable to cost-sensitive production environments. Unfortunately, weld parameters and performance developed and characterized at low-to-moderate welding velocities do not directly translate to high-speed linear FSW. Therefore, to facilitate production of high-volume aluminum FSW components, parameters were developed with a minimum welding velocity of 3 m/min. With an emphasis on weld quality, welded blanks were evaluated for postweld formability using a combination of numerical and experimental methods. An evaluation across scales was ultimately validated by stamping full-size production door inner panels made from dissimilar thickness aluminum TWBs, which provided validation of the numerical and experimental analysis of laboratory-scale tests.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  8. Yield detection in aluminum welded joints using photostress

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

  9. Gas-tungsten arc welding of aluminum alloys

    DOEpatents

    Frye, Lowell D.

    1984-01-01

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

  10. Gas-tungsten arc welding of aluminum alloys

    DOEpatents

    Frye, L.D.

    1982-03-25

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

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

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

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

  12. Effect of Preheating in Hybrid Friction Stir Welding of Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Yaduwanshi, D. K.; Bag, S.; Pal, S.

    2014-10-01

    The controlled energy input into the system by introducing an extra heat source to enhance the material flow along with reduction of the plunging force remains a potential area of considerate for the development of hybrid friction stir welding (FSW) process. Hence, the effect of preheating on the weld joint properties is evaluated using plasma-assisted friction stir welding (P-FSW) process for joining aluminum alloy. A comparative study of mechanical and macro-microstructural characterizations of weld joint by FSW and P-FSW has been performed. Transverse tensile strength of weld joint is approximately 95% of base metal produced by P-FSW and is 8% more than conventional FSW welds. The effect of preheating enhances material flow and dissolution of fine oxide particles by plasma arc results in increase of strength and marginal modification of deformation behavior. The preheating brings uniformly distributed hardness in weld zone and the magnitude is higher in the advancing side with overall increase in average hardness value. Grain sizes are much finer due to the pinning effect of Al2O3 particles that retarded grain growth following recrystallization during P-FSW and thus led to more pronounced reduction in grain size and relatively brittle fracture during tensile loading of welded joint. Overall, the influence of preheating acts quite homogeneously throughout the structure as compared to conventional FSW. However, the results reveal that the development of P-FSW is still in initial stage and needs to improve in various aspects.

  13. Experimental Study of Stationary Shoulder Friction Stir Welded 7N01-T4 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Ji, S. D.; Meng, X. C.; Li, Z. W.; Ma, L.; Gao, S. S.

    2016-03-01

    Stationary shoulder friction stir welding (SSFSW) was successfully used to weld 7N01-T4 aluminum alloy with the thickness of 4 mm. Effects of welding speed on formations, microstructures, and mechanical properties of SSFSW joint were investigated in detail. Under a constant rotational velocity of 2000 rpm, defect-free joints with smooth surface and small flashes are attained using welding speeds of 20 and 30 mm/min. Macrostructure of nugget zone in cross section presents kettle shape. For 7N01-T4 aluminum alloy with low thermal conductivity, decreasing welding speed is beneficial to surface formation of joint. With the increase of welding speed, mechanical properties of joints firstly increase and then decrease. When the welding speed is 30 mm/min, the tensile strength and elongation of joint reach the maximum values of 379 MPa and 7.9%, equivalent to 84.2 and 52% of base material, respectively. Fracture surface morphology exhibits typical ductile fracture. In addition, the minimum hardness value of joint appears in the heat affected zone.

  14. Friction Stir Spot Welding of 6061 Aluminum-to-Copper

    NASA Astrophysics Data System (ADS)

    Heideman, Robert J.

    Friction stir spot welding (FSSW) between 1.5mm thick 6061 Al on top and 1.5mm thick Cu at bottom was conducted. First, weld parameters and the weld macrostructure that were necessary to form good quality welds, as determined using lap shear weld strength, were identified. Tool rotation speed and tool pin length are key variables that control weld strength. To obtain high quality strong welds, a Cu ring extruded upward from the lower Cu sheet into the upper 6061 Al-sheet, which promoted bonding and interlocking between the sheets, and an Al-rich stir zone between Cu ring and weld keyhole were both necessary. Second, a technique where the tool remained in the sample after FSSW helped determine the material flow that takes place during high quality weld formation and the functions of the welding tool features. The tool threads cause 6061 Al from the upper sheet to move downward into the region near the threads. The tool shoulder causes a counter flow movement of 6061 Al that results in the formation of the Al-rich stir zone and also causes the upward extrusion of the lower Cu sheet. This technique also identified that a Cu-rich material forms on the tool tip, that this material sheds and rebuilds during subsequent welds, and that this material can form large Cu-rich particles that can completely fill the tool threads, impede proper material flow and lead to a low strength, poor quality weld. Third, to further understand welding parameters, weld temperatures, torque, and vertical forces were measured. Temperature data was collected using a tool holder that permitted wireless thermocouple data collection. Through these measurements, rotational plunge weld energy was recognized as important in determining if a quality weld formed, and weld plunge rate was identified as the welding parameter that significantly impacted rotational weld plunge energy. The final phase of research was to improve weld quality consistency. Through repetitive trials with a single tool

  15. Microstructural Investigation of Friction-Stir-Welded 7005 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Xu, Xuesong; Lu, Yan; Zheng, Feiyan; Chen, Bin

    2015-11-01

    This paper is aimed to investigate the microstructure of 7005 aluminum sheets joined by friction-stir welding as well as their mechanical properties. Specimens with ten different sets of welding parameters were studied. Tensile test and fracture analysis determined that the joint of the best quality was obtained at the rotation speed of 1000 rpm matching with the travel speed of 200 mm/min, and the travel speed has more impact on the ultimate tensile strength. Optical microscope observation was applied to this high-quality specimen and gave evidence to explaining the formation of the onion ring structure. Electron back-scattered diffraction (EBSD) technique was employed to characterize the textures and revealed the evolution of microstructures during friction stir processing. The EBSD results showed that the grains maintain their original orientations at relatively low deformation while the orientations rotate under increasing strain. Accumulated rotation will turn the textures into mixed shear components, which finally results in grain refinement and contributes to the high quality of the joint.

  16. 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.

  17. Damage Tolerance Behavior of Friction Stir Welds in Aluminum Alloys

    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 various aerospace structures. Self-reacting and conventional friction stir welding are variations of the friction stir weld process employed in the fabrication of cryogenic propellant tanks which are classified as pressurized structure in many spaceflight vehicle architectures. In order to address damage tolerance behavior associated with friction stir welds in these safety critical structures, 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 describing fracture behavior, residual strength capability, and cyclic mission life capability of friction stir welds at ambient and cryogenic temperatures have been generated and will be presented in this paper. Fracture behavior will include fracture toughness and tearing (R-curve) response of the friction stir welds. Residual strength behavior will include an evaluation of the effects of lack of penetration on conventional friction stir welds, the effects of internal defects (wormholes) on self-reacting friction stir welds, and an evaluation of the effects of fatigue cycled surface cracks on both conventional and selfreacting welds. Cyclic mission life capability will demonstrate the effects of surface crack defects on service load cycle capability. The fracture data will be used to evaluate nondestructive inspection and proof test requirements for the welds.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  19. 49 CFR 178.68 - Specification 4E welded aluminum cylinders.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Specification 4E welded aluminum cylinders. 178.68... PACKAGINGS Specifications for Cylinders § 178.68 Specification 4E welded aluminum cylinders. (a) Type, size and service pressure. A DOT 4E cylinder is a welded aluminum cylinder with a water capacity...

  20. 49 CFR 178.68 - Specification 4E welded aluminum cylinders.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Specification 4E welded aluminum cylinders. 178.68... PACKAGINGS Specifications for Cylinders § 178.68 Specification 4E welded aluminum cylinders. (a) Type, size and service pressure. A DOT 4E cylinder is a welded aluminum cylinder with a water capacity...

  1. 49 CFR 178.68 - Specification 4E welded aluminum cylinders.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Specification 4E welded aluminum cylinders. 178.68... PACKAGINGS Specifications for Cylinders § 178.68 Specification 4E welded aluminum cylinders. (a) Type, size and service pressure. A DOT 4E cylinder is a welded aluminum cylinder with a water capacity...

  2. 49 CFR 178.68 - Specification 4E welded aluminum cylinders.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Specification 4E welded aluminum cylinders. 178.68... PACKAGINGS Specifications for Cylinders § 178.68 Specification 4E welded aluminum cylinders. (a) Type, size and service pressure. A DOT 4E cylinder is a welded aluminum cylinder with a water capacity...

  3. Flaw growth behavior in thick welded plates of 2219-T87 aluminum at room and cryogenic temperatures

    NASA Technical Reports Server (NTRS)

    Forman, R. G.; Glorioso, S. V.; Medlock, J. D.

    1973-01-01

    Axial load fatigue and fracture tests were conducted on thick welded plates of 2219-T87 aluminum alloy to determine the tensile strength properties and the flaw growth behavior in electron beam, gas metal arc, and pulse current gas tungsten arc welds for plates 6.35 centimeters (2.5 in.) thick. The tests were conducted in room temperature air and in liquid nitrogen environments. Specimens were tested in both the as-welded and the aged after welding conditions. The experimental crack growth rate were correlated with theoretical crack growth rate predictions for semielliptical surface flaws.

  4. Neural network modeling of pulsed-laser weld pool shapes in aluminum alloy welds

    SciTech Connect

    Vitek, J.M.; Iskander, Y.S.; Oblow, E.M.; Babu, S.S.; David, S.A.; Fuerschbach, P.W.; Smartt, H.B.; Pace, D.P. Tolle, C.R.

    1998-11-01

    A model was developed to predict the weld pool shape in pulsed Nd:YAG laser welds of aluminum alloy 5754. The model utilized neural network analysis to relate the weld process conditions to four pool shape parameters: penetration, width, width at half-penetration, and cross-sectional area. The model development involved the identification of the input (process) variables, the desired output (shape) variables, and the optimal neural network architecture. The latter was influenced by the number of defined inputs and outputs as well as the amount of data that was available for training the network. After appropriate training, the best network was identified and was used to predict the weld shape. A routine to convert the shape parameters into predicted weld profiles was also developed. This routine was based on the actual experimental weld profiles and did not impose an artificial analytical function to describe the weld profile. The neural network model was tested on experimental welds. The model predictions were excellent. It was found that the predicted shapes were within the experimental variations that were found along the length of the welds (due to the pulsed nature of the weld power) and the reproducibility of welds made under nominally identical conditions.

  5. Neural network modeling of pulsed-laser weld pool shapes in aluminum alloy welds

    SciTech Connect

    Vitek, J.M.; Iskander, Y.S.; Oblow, E.M.; Babu, S.S.; David, S.A.; Fuerschbach, P.W.; Smartt, H.B.

    1998-09-01

    A model was developed to predict the weld pool shape in pulsed Nd:YAG laser welds of aluminum alloy 5754. The model utilized neural network analysis to relate the weld process conditions to four pool shape parameters: (1) penetration width, (2) width at half-penetration, and (3) cross-sectional area. The model development involved the identification of the input (process) variables, the desired output (shape) variables, and the optimal neural network architecture. The latter was influenced by the number of defined inputs and outputs as well as the amount of data that was available for training the network. After appropriate training, die best network was identified and was used to predict the weld shape. A routine to convert the shape parameters into predicted weld profiles was also developed. This routine was based on the actual experimental weld profiles and did not impose an artificial analytical function to describe the weld profile. The neural network model was tested on experimental welds. The model predictions were excellent. It was found that the predicted shapes were within the experimental variations that were found along the length of the welds (due to the pulsed nature of the weld power) and the reproducibility of welds made under nominally identical conditions.

  6. Vertical Compensation Friction Stir Welding of 6061-T6 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Ji, Shude; Meng, Xiangchen; Xing, Jingwei; Ma, Lin; Gao, Shuangsheng

    2016-09-01

    Vertical compensation friction stir welding (VCFSW) was proposed in order to solve the adverse effect caused by a big gap at the interface between two welded workpieces. VCFSW was successfully applied to weld 6061-T6 aluminum alloy with the thickness of 4 mm, while 2024-T4 aluminum alloy was selected as a rational compensation material. The results show that VCFSW is difficult to get a sound joint when the width of strip is no less than 1.5 mm. Decreasing the welding speed is beneficial to break compensation strip into pieces and then get higher quality joint. When the width of strip is 1 mm, the tensile strength and elongation of joint at the welding speed of 50 mm/min and rotational velocity of 1,800 rpm reach the maximum values of 203 MPa and 5.2%, respectively. Moreover, the addition of 2024-T4 alloy plays a strengthening effect on weld zone (WZ) of VCFSW joint. The fracture surface morphology of joint consisting of amounts of dimples exhibits ductile fracture.

  7. Copper Electrode Degradation Due to the Resistance Welding of Aluminum

    DTIC Science & Technology

    2007-11-02

    pieces employed in the automotive and aerospace induatries. When the. copper and aluminum make contact at the interface, there is some undesirable...refractory metals, such as molybdenum, niobium , and chromium, have been fabricated. Since the refractory metals are not readily soluble in copper, it...focuses on increasing the life of copper electrodes used in the resistance welding of aluminum work pieces employed in the automotive and aerospace

  8. 2195 Aluminum-Copper-Lithium Friction Plug Welding Development

    NASA Technical Reports Server (NTRS)

    Takeshita, Rike P.; Hartley, Paula J.; Baker, Kent S.

    1997-01-01

    Technology developments and applications of friction plug welding is presented. This friction repair welding technology is being studied for implementation on the Space Transportation System's Super Light Weight External Tank. Single plug repairs will be used on a vast majority of weld defects, however, linear defects of up to several inches can be repaired by overlapping plug welds. Methods and results of tensile, bend, simulated service, surface crack tension and other tests at room and cryogenic temperatures is discussed. Attempts to implement Friction Plug Welding has led to both tool and process changes in an attempt to minimize expansive tooling and lengthy implementation times. Process control equipment and data storage methods intended for large scale production will also be addressed. Benefits include increased strength and toughness, decreased weld repair time, automated and highly reliable process, and a lower probability of having to re-repair defect locations.

  9. Molten pool characterization of laser lap welded copper and aluminum

    NASA Astrophysics Data System (ADS)

    Xue, Zhiqing; Hu, Shengsun; Zuo, Di; Cai, Wayne; Lee, Dongkyun; Elijah, Kannatey-Asibu, Jr.

    2013-12-01

    A 3D finite volume simulation model for laser welding of a Cu-Al lap joint was developed using ANSYS FLUENT to predict the weld pool temperature distribution, velocity field, geometry, alloying element distribution and transition layer thickness—all key attributes and performance characteristics for a laser-welded joint. Melting and solidification of the weld pool was simulated with an enthalpy-porosity formulation. Laser welding experiments and metallographic examination by SEM and EDX were performed to investigate the weld pool features and validate the simulated results. A bowl-shaped temperature field and molten pool, and a unique maximum fusion zone width were observed near the Cu-Al interface. Both the numerical simulation and experimental results indicate an arch-shaped intermediate layer of Cu and Al, and a gradual transition of Cu concentration from the aluminum plate to the copper plate with high composition gradient. For the conditions used, welding with Cu on top was found to result in a better weld joint.

  10. Electromagnetic hammer removes weld distortions from aluminum tanks

    NASA Technical Reports Server (NTRS)

    Schwinghamer, R. J.

    1965-01-01

    Distortions around weld areas on sheet-aluminum tanks and other structures are removed with a portable electromagnetic hammer. The hammer incorporates a coil that generates a controlled high-energy pulsed magnetic field over localized areas on the metal surface.

  11. Microstructure and Mechanical Properties of Friction Stir Welded 5083 and 7075 Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Kalemba-Rec, I.; Hamilton, C.; Kopyściański, M.; Miara, D.; Krasnowski, K.

    2017-02-01

    Through microscopy, mechanical testing, and numerical modeling, the microstructure and mechanical performance of friction stir welded aluminum alloys 7075-T651 and 5083-H111 were characterized. In particular, the influence of the weld configuration, i.e., the locations of the 7075 and 5083 alloys alternately on the advancing and retreating sides, on material flow, microstructure, and mechanical properties was considered. Thermographic data in conjunction with a process simulation demonstrated that the weld configuration significantly impacts heat generation during friction stir welding. The microstructure in the stir zone was a clear visualization of the material flow and was characterized by a vortex-like structure with alternating bands of the alloys being joined. These bands differed in elemental content and grain size. The microstructure became more complex when greater heat generation (higher temperatures) occurred. The weld configuration strongly influenced the material flow, but did not impact the tensile properties (such as yield strength, tensile strength, and elongation). The configuration of 5083 on the advancing side and 7075 on the retreating side produced the most uniform material flow. The joint efficiencies of all tested welds were above 100%.

  12. Mechanical and microstructural characterization of single and double pass Aluminum AA6061 friction stir weld joints

    NASA Astrophysics Data System (ADS)

    Othman, N. H.; Shah, L. H.; Ishak, M.

    2015-12-01

    This study focuses on the effect of single pass (SP), double sided pass (DSP) and normal double pass (NDP) method on friction stir welding of aluminum AA6061. Two pieces of AA6061 alloy with thickness of 6 mm were friction stir welded by using conventional milling machine. The rotational speeds that were used in this study were 800 rpm, 1000 rpm and 1200 rpm, respectively. The welding speed is fixed to 100 mm/min. Microstructure observation of welded area was studied by using optical microscope. Tensile test and Vickers hardness test were used to evaluate the mechanical properties of this specimen. Mechanical property analysis results indicate that at low rotational speeds, defects such as surface lack of fill and tunneling in the welded area can be observed. Vickers hardness of specimens however did not vary much when rotational speed is varied. Welded specimens using single pass method shows higher tensile strength and hardness value compared to both double pass methods up to 180.61 MPa. Moreover, DSP showed better tensile test and hardness test compared to NDP method. The optimum parameters were found to be single pass method with 1200 rpm of rotational speed. Therefore economically sound to only perform SP method to obtain maximum tensile strength for AA6061 FSW with thickness of 6 mm.

  13. Microstructure and Mechanical Properties of Friction Stir Welded 5083 and 7075 Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Kalemba-Rec, I.; Hamilton, C.; Kopyściański, M.; Miara, D.; Krasnowski, K.

    2017-03-01

    Through microscopy, mechanical testing, and numerical modeling, the microstructure and mechanical performance of friction stir welded aluminum alloys 7075-T651 and 5083-H111 were characterized. In particular, the influence of the weld configuration, i.e., the locations of the 7075 and 5083 alloys alternately on the advancing and retreating sides, on material flow, microstructure, and mechanical properties was considered. Thermographic data in conjunction with a process simulation demonstrated that the weld configuration significantly impacts heat generation during friction stir welding. The microstructure in the stir zone was a clear visualization of the material flow and was characterized by a vortex-like structure with alternating bands of the alloys being joined. These bands differed in elemental content and grain size. The microstructure became more complex when greater heat generation (higher temperatures) occurred. The weld configuration strongly influenced the material flow, but did not impact the tensile properties (such as yield strength, tensile strength, and elongation). The configuration of 5083 on the advancing side and 7075 on the retreating side produced the most uniform material flow. The joint efficiencies of all tested welds were above 100%.

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

    SciTech Connect

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

    1998-02-03

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

  15. Aluminum Lithium Alloy 2195 Fusion Welding Improvements with New Filler Wire

    NASA Technical Reports Server (NTRS)

    Russell, Carolyn; Bjorkman, Gerry; McCool, Carolyn (Technical Monitor)

    2000-01-01

    A viewgraph presentation outlines NASA Marshall Space Flight Center, Lockheed Martin Michoud Space Systems, and McCook Metals' development an aluminum-copper weld filler wire for fusion welding 2195 aluminum lithium. The aluminum-copper based weld filler wire has been identified as B218, which is the result of six years of weld filler wire development funded by NASA, Lockheed Martin, and McCook Metals. The Super Lightweight External Tank for the NASA Space Shuttle Program consists of 2195 welded with 4043 aluminum-silicon weld filler wire. The B218 filler wire chemistry was developed to produce enhanced 2195 weld and repair weld mechanical properties. An initial characterization of the B218 weld filler wire was performed consisting of initial weld and repair weld evaluation comparing B218 and 4043. The testing involved room temperature and cryogenic tensile testing along with fracture toughness testing. B218 weld filler wire proved to produce enhanced initial and repair weld tensile and fracture properties over 4043. B218 weld filler wire has proved to be a superior weld filler wire for welding 2195 and other aluminum lithium alloys over 4043.

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  18. Neural Network Modeling of Weld Pool Shape in Pulsed-Laser Aluminum Welds

    SciTech Connect

    Iskander, Y.S.; Oblow, E.M.; Vitek, J.M.

    1998-11-16

    A neural network model was developed to predict the weld pool shape for pulsed-laser aluminum welds. Several different network architectures were examined and the optimum architecture was identified. The neural network was then trained and, in spite of the small size of the training data set, the network accurately predicted the weld pool shape profiles. The neural network output was in the form of four weld pool shape parameters (depth, width, half-width, and area) and these were converted into predicted weld pool profiles with the use of the actual experimental poo1 profiles as templates. It was also shown that the neural network model could reliably predict the change from conduction-mode type shapes to keyhole-mode shapes.

  19. Mechanical Characteristics of Welded Joints of Aluminum Alloy 6061 T6 Formed by Arc and Friction Stir Welding

    NASA Astrophysics Data System (ADS)

    Astarita, A.; Squillace, A.; Nele, L.

    2016-01-01

    Butt welds formed by arc welding in inert gas with nonconsumable electrode (tungsten inert gas (TIG) welding) and by friction stir welding (FSW) from aluminum alloy AA6061 T6 are studied. Comparative analysis of the structures and mechanical properties of the welded joints is performed using the results of optical and electron microscopy, tensile tests, tests for residual bending ductility, and measurements of microhardness. The changes in the microstructure in different zones and the degrees of degradation of the mechanical properties after the welding are determined. It is shown that the size of the tool for the friction stir welding affects the properties of the welds. Quantitative results showing the relation between the microscopic behavior of the alloy and the welding-induced changes in the microstructure are obtained. Friction stir welding is shown to provide higher properties of the welds.

  20. Friction Stir Spot Welding of Advanced High Strength Steels

    SciTech Connect

    Santella, M. L.; Hovanski, Yuri; Grant, Glenn J.; Carpenter, Joseph A.; Warren, C. D.; Smith, Mark T.

    2008-12-28

    Experiments are continuing to evaluate the feasibility of friction stir spot welding advanced high-strength steels including, DP780, martensitic hot-stamp boron steel, and TRIP steels. Spot weld lap-shear strengths can exceed those required by industry standards such as AWS D8.1.

  1. Welding Phenomenon and Removal Mechanism of Aluminum-Oxide Films by Space GHTA Welding Process in Vacuum

    NASA Astrophysics Data System (ADS)

    Suita, Yoshikazu; Ekuni, Tomohide; Kamei, Misa; Tsukuda, Yoshiyuki; Terajima, Noboru; Yamashita, Masahiro; Imagawa, Kichiro; Masubuchi, Koichi

    Aluminum alloys have been widely used in constructing various space structures including the ISS (International Space Station) and launch vehicles. In order to apply the welding technology in space, welding experiments on aluminum alloy were performed using by the GHTA (Gas Hollow Tungsten Arc) welding processes using an inverter controlled DC/AC GTA welding machine in vacuum. We observed the removal mechanism of aluminum-oxide films on molten metal in detail during the welding using a high-speed video camera. As a result, it is clarified that the impact arc pressure produced by pulsed current mechanically crushes and removes aluminum-oxide films on the molten pool. This removal mechanism of aluminum-oxide films is completely different from a removal mechanism by cleaning action.

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

    SciTech Connect

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

    2014-11-15

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

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

    NASA Astrophysics Data System (ADS)

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

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

  4. Impact Welding of Aluminum to Copper and Stainless Steel by Vaporizing Foil Actuator: Effect of Heat Treatment Cycles on Mechanical Properties and Microstructure

    NASA Astrophysics Data System (ADS)

    Vivek, Anupam; Hansen, Steven; Benzing, Jake; He, Mei; Daehn, Glenn

    2015-10-01

    This work studies the mechanical property effect of microstructure on impact welds of aluminum alloy AA6061 with both copper alloy Cu 110 and stainless steel AISI 304. AA6061-T6 and T4 temper aluminum sheets of 1 mm thickness were launched toward copper and stainless steel targets using the vaporizing foil actuator technique. Flyer plate velocities, measured via photonic Doppler velocimetry, were observed to be approximately 800 m/s. The welded aluminum-copper samples were subjected to instrumented peel testing, microhardness testing, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. The welded joints exhibited cracks through their continuous intermetallic layers. The cracks were impeded upon encountering a ductile metallic wave. The welds created with T6 temper flyer sheets were found to have smaller intermetallic-free and wavy interface regions as compared to those created with T4 temper flyer sheets. Peel strength tests of the two weld combinations resulted in failure along the interface in the case of the T6 flyer welds, while the failure generally occurred in the parent aluminum for the T4 temper flyer welds. Half of the T4 flyer welds were subjected to aging for 18 h at 433 K (160 °C) to convert the aluminum sheet to the T6 condition. Although the aged flyer material did not attain the hardness of the as-received T6 material, it was found to be significantly stronger than the T4 material. These welds retained their strength after the aging process, and diffusion across the interface was minimal. The welded aluminum-stainless steel samples were analyzed on a more basic level than aluminum-copper samples, but were found to exhibit similar results.

  5. 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.

  6. High Temperature Analysis of Aluminum-Lithium 2195 Alloy to Aid in the Design of Improved Welding Techniques

    NASA Technical Reports Server (NTRS)

    Talia, George E.; Widener, Christian

    1996-01-01

    Aluminum-lithium alloys have extraordinary properties. The addition of lithium to an aluminum alloy decreases its density, while making large increases in its strength and hardness. The down side is that they are unstable at higher temperatures, and are subsequently difficult to weld or even manufacture. Martin Marietta, though, developed an aluminum-lithium alloy 2195 that was reported to have exceptional properties and good weldability. Thus, it was chosen as the alloy for the space shuttles super light external tank. Unfortunately, welding 2195 has turned out to be much more of a challenge than anticipated. Thus, research has been undergone in order to understand the mechanisms that are causing the welding problems. Gas reactions have been observed to be detrimental to weld strength. Water vapor has often been identified as having a significant role in these reactions. Nitrogen, however, has also been shown to have a direct correlation to porosity. These reactions were suspected as being complex and responsible for the two main problems of welding 2195. One, the initial welds of 2195 are much weaker than the parent metal. Second, each subsequent welding pass increases the size and number of cracks and porosity, yielding significant reductions in strength. Consequently, the objective of this research was to characterize the high-temperature reactions of 2195 in order to understand the mechanisms for crack growth and the formation of porosity in welds. In order to accomplish that goal, an optical hot-stage microscope, HSM, was used to observe those reactions as they occurred. Surface reactions of 2195 were observed in a variety of environments, such as air, vacuum, nitrogen and helium. For comparison, some samples of Al-2219 were also observed. Some of the reacted surfaces were then analyzed on a scanning electron microscope, SEM. Additionally, a gas chromatograph was used to analyze the gaseous products of the high temperature reactions.

  7. Neutron diffraction studies of welds of aerospace aluminum alloys

    SciTech Connect

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

    1996-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  9. The effect of postprocessing on tensile property and microstructure evolution of friction stir welding aluminum alloy joint

    SciTech Connect

    Hu, Z.L.; Wang, X.S.; Pang, Q.; Huang, F.; Qin, X.P.; Hua, L.

    2015-01-15

    Friction stir welding is an efficient manufacturing method for joining aluminum alloy and can dramatically reduce grain size conferring excellent plastic deformation properties. Consequently, friction stir welding is used to manufacture tailor welded blanks to optimize weight or performance in the final component. In the study, the microstructural evolution and mechanical properties of friction stir welding joint during plastic forming and subsequent heat treatment were investigated. The microstructural characteristics of the friction stir welding joints were studied by Electron Backscattered Diffraction and Transmission Electron Microscopy. The mechanical properties were evaluated by tensile and microhardness tests. It is found that the tensile and yield strengths of friction stir welding joints are significantly improved after severe plastic deformation due to the grain refinement. Following heat treatment, the strength of the friction stir welding joints significantly decrease due to the obvious abnormal grain growth. Careful attention must be given to the processing route of any friction stir welding joint intended for plastic forming, especially the annealing between forming passes. Severe plastic deforming of the friction stir welding joint leads to a high level of stored energy/dislocation density, which causes the abnormal grain growth during subsequent heat treatment, and consequently reduce the mechanical properties of the friction stir welding joint. - Highlights: • Great changes are observed in the microstructure of FSW joint after postprocessing. • Postprocessing shows great effect on the microstructure stability of FSW joint. • The weld shows more significant decrease in strength than the BM due to the AGG. • Attention must be given to the processing route of FSW joint for plastic forming.

  10. Spatial Mechanical Response and Strain Gradient Evolution of Friction Stir Welded Aluminum-2139

    DTIC Science & Technology

    2012-02-01

    Background Aluminum alloys are becoming increasingly desirable structural metals for replacing steel due to their lower density, 2.67 and 7.87 g/cm 3... aluminum alloys. FSW is an optimal process for welding aluminum , in comparison to conventional welding techniques that are difficult to fuse together...due to the aluminum oxide (Al2O3) formed on the surface (3). FSW reduces the cracks and voids that are formed during other joining processes. FSW

  11. Friction Stir Welding of Thick Section Aluminum for Military Vehicle Applications

    DTIC Science & Technology

    2012-12-01

    production-level, single-pass friction stir welding ( FSW ) parameters for thicknesses ranging from 0.5 to 1.6 inches in aluminum alloys 5083, 5059, and 2139...developing thick section aluminum Friction Stir Welding ( FSW ) for use in aluminum military vehicle applications. The primary objective of this...this demonstration article represents a significant step forward in the acceptance of FSW technology as a viable joining method for aluminum hulled

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

    SciTech Connect

    Talia, G.E.

    1996-02-01

    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. 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.

  13. 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.

  14. FLUXES FOR MECHANIZED ELECTRIC WELDING,

    DTIC Science & Technology

    WELDING FLUXES, WELDING ), (* WELDING , WELDING FLUXES), ARC WELDING , WELDS, STABILITY, POROSITY, WELDING RODS, STEEL, CERAMIC MATERIALS, FLUXES(FUSION), TITANIUM ALLOYS, ALUMINUM ALLOYS, COPPER ALLOYS, ELECTRODEPOSITION

  15. TIG welding of aluminum alloys for the APS storage ring - a UHV application

    SciTech Connect

    Goeppner, G.A.

    1996-05-29

    The Advanced Photon Source (APS) incorporates a 7-GeV positron storage ring 1104 meters in circumference. The storage ring vacuum system is designed to maintain a pressure of 1 nTorr or less with a circulating current of 300 mA to enable beam lifetimes of greater than 10 hours. The vacuum chamber is an aluminum extrusion of 6063T5 alloy. There are 235 separate aluminum vacuum chambers in the storage ring connected by stainless steel bellows assemblies. Aluminum was chosen for the vacuum chamber because it can be economically extruded and machined, has good thermal conductivity, low thermal emissivity, a low outgassing rate, low residual radioactivity, and is non-magnetic. The 6063 aluminum-silicon-magnesium alloy provides high strength combined with good machining and weldability characteristics. The extrusion process provides the interior surface finish needed for the ultrahigh vacuum (UHV) environments There are six different vacuum chambers with the same extrusion cross section. The average vacuum chamber length is 171.6 inches. The extruded vacuum chambers are welded to flange assemblies made up of machined 2219 aluminum alloy pieces and 2219 aluminum vacuum flanges from a commercial source.

  16. Strength of Welded Joints in Tubular Members for Aircraft

    DTIC Science & Technology

    1930-02-06

    STRENGTH OF WELDED JOINTS IN TUBULAR MEMBERS FOR AIRCRAFT By H. L. WHITTEMORE and W. C. BRUEGGEMAN Bureau of Standards ——— - ..— .-.— .— .— —___ 107346->1...331 331 332 341 341 342 343 343 343 347 347 347 367 .— .— — ● REPORT ~0, 348 STRENGTH OF WELDED JOINTS IN TUBULAR MELMBERS FOR AIRCRAFT By H. L...airoraft welds has been publi~hed)lit ig beh%redthat euch tests made by a disinterested governmental laboratory should be of considerablemdueto the

  17. Friction Stir Spot Welding of Advanced High Strength Steels

    SciTech Connect

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

    2009-12-28

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

  18. Precipitate evolution in friction stir welding of 2219-T6 aluminum alloys

    SciTech Connect

    Chen, Y.C.; Feng, J.C.; Liu, H.J.

    2009-06-15

    Precipitate evolution in friction stir welding of 2219-T6 aluminum alloys was characterized by transmission electron microscopy. In the weld nugget zone and the thermo-mechanically affected zone some metastable precipitates overaged to equilibrium phase while others solutionized into the aluminum solid solution. In the heat-affected zone the precipitates coarsened.

  19. Joining aluminum to titanium alloy by friction stir lap welding with cutting pin

    SciTech Connect

    Wei, Yanni; Li, Jinglong; Xiong, Jiangtao; Huang, Fu; Zhang, Fusheng; Raza, Syed Hamid

    2012-09-15

    Aluminum 1060 and titanium alloy Ti-6Al-4V plates were lap joined by friction stir welding. A cutting pin of rotary burr made of tungsten carbide was employed. The microstructures of the joining interface were observed by scanning electron microscopy. Joint strength was evaluated by a tensile shear test. During the welding process, the surface layer of the titanium plate was cut off by the pin, and intensively mixed with aluminum situated on the titanium plate. The microstructures analysis showed that a visible swirl-like mixed region existed at the interface. In this region, the Al metal, Ti metal and the mixed layer of them were all presented. The ultimate tensile shear strength of joint reached 100% of 1060Al that underwent thermal cycle provided by the shoulder. - Highlights: Black-Right-Pointing-Pointer FSW with cutting pin was successfully employed to form Al/Ti lap joint. Black-Right-Pointing-Pointer Swirl-like structures formed due to mechanical mixing were found at the interface. Black-Right-Pointing-Pointer High-strength joints fractured at Al suffered thermal cycle were produced.

  20. Aluminum Rayleigh Taylor Strength Measurements and Calculations

    SciTech Connect

    Lindquist, M J; Cavallo, R M; Lorenz, K T; Pollaine, S M; Remington, B A; Raevsky, V A

    2007-01-10

    A traditional approach to the study of material strength has been revitalized at the Russian Federal Nuclear Center (VNIIEF). Rayleigh Taylor strength experiments have long been utilized to measure the material response of metals at high pressure and strain rates. A modulated (sinusoidal or sawtooth perturbation) surface is shocklessly (quasi-isentropically) accelerated by a high explosive (HE) driver, and radiography is used to measure the perturbation amplitude as a function of time. The Aluminum T-6061 targets are designed with several sets of two-dimensional sawtooth perturbations machined on the loading surface. The HE driver was designed to reach peak pressures in the range of 200 to 300 kbar and strain rates in the range of 10{sup 4} - 10{sup 6} s{sup -1}. The standard constitutive strength models, Steinberg-Guinan (SG) [1], Steinberg-Lund (SL) [2], Preston-Tonks-Wallace (PTW) [3], Johnson-Cooke (JC) [4], and Mechanical Threshold Stress (MTS) [5], have been calibrated by traditional techniques: (Hopkinson-Bar, Taylor impact, flyer plate/shock-driven experiments). The VNIIEF experimental series accesses a strain rate regime not attainable using traditional methods. We have performed a detailed numerical study with a two-dimensional Arbitrary Lagrangian Eulerian hydrodynamics computer code containing several constitutive strength models to predict the perturbation growth. Results show that the capabilities of the computational methodology predict the amplitude growth to within 5 percent of the measured data, thus validating both the code and the strength models under the given conditions and setting the stage for credible future design work using different materials.

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

    NASA Astrophysics Data System (ADS)

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

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

  2. Automatic Welding System of Aluminum Pipe by Monitoring Backside Image of Molten Pool Using Vision Sensor

    NASA Astrophysics Data System (ADS)

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

    An automatic welding system using Tungsten Inert Gas (TIG) welding with vision sensor for welding of aluminum pipe was constructed. This research studies the intelligent welding process of aluminum alloy pipe 6063S-T5 in fixed position and moving welding torch with the AC welding machine. The monitoring system consists of a vision sensor using 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. Neural network model for welding speed control were constructed to perform the process automatically. From the experimental results it shows the effectiveness of the control system confirmed by good detection of molten pool and sound weld of experimental result.

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

    SciTech Connect

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

    2014-11-14

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

  4. Strength of Welded Joints in Tubular Members for Aircraft

    NASA Technical Reports Server (NTRS)

    Whittemore, H L; Brueggeman, W C

    1931-01-01

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

  5. Reduction of Residual Stress and Distortion in HY100 and HY130 High Strength Steels During Welding

    DTIC Science & Technology

    1989-06-01

    High Yields) Steels for pressure hulls and special applications like flight decks where aluminum is impractical to use. HY80 is the most famous and...most widely used of the HYQ & T steels developed. Interest waned in widely using the steels with strengths above HY80 because of cracking problems...Reduction of Residual Stress and Distortion in HYI00 and HYI30 High Strength Steels During Welding CY) by _RICHARD ALLEN BASS B.S. Electrical

  6. High Strength and Compatible Aluminum Alloy for Hydrogen-Peroxide Fuel Tanks

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    2004-01-01

    This paper describes the development of a new high strength and Hydrogen Peroxide (HP) propellant compatible aluminum alloy for NASA Hyper-X vehicle's fuel tanks and structures. The tensile strength of the new alloy is more than 3 times stronger than the conventional 5254 alloy while it still maintains HP compatibility similar to 5254 (Class 1 category). The alloy development strategy consists of selecting certain rare earth and transition metals, with unique electrochemical properties, that will not act as catalysts to decompose liquid HP at the atomic level. Such elements will added to the aluminum alloy and the mixture will be cast and rolled into thin sheet metals. Test coupons are machined from sheet metals for HP long-term exposure testing and mechanical properties testing. In addition, the ability to weld the new alloy using Friction Stir Welding has also been explored. Currently, aluminum alloy 5254 is the state-of-the-art material for HP storage, but its yield strength is very low (420 ksi) and may not be suitable for the development of light-weight fuel tanks for Hyper-X vehicles. The new high strength and HP compatible alloy could represent an enabling material technology for NASA's Hyper-X vehicles, where flight weight reduction is a critical requirement. These X-planes are currently under studied as air-breathing hypersonic research vehicles featuring a lifting body configuration with a Rocket Based Combined Cycle (RBCC) engine system.

  7. 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.

  8. Laser beam welding of aluminum die casting with reduced pore formation

    SciTech Connect

    Rehbein, D.H.; Decker, I.; Wohlfahrt, H.

    1994-12-31

    Laser beam welding is already well treated within the laboratory, but there is still a minor industrial application because of the lack of reliability of the process due to violent fluctuations of the plasma formation above and melt flow turbulence around the welding key-hole. An even greater challenge is the welding of die cast aluminum since the high hydrogen content dissolved within the material during the casting process is responsible for a strong pore formation of the weld and a rather unsteady welding process. During the last 10 years, intensive research work has been executed by the research institute of the authors in order to increase the weldability of die-case aluminum by optimization of the casting process. The casting process has been optimized in such a way that as few gases as possible can penetrate into the castings. The porosity of the welds has been reduced to a level comparable to that of high-quality joints of wrought material. The weld quality achieved by electron beam welding is excellent. The range of possible welding speeds and the necessary laser power depending on the wall thickness and the chosen optical arrangement are quantified. Die casting of aluminum is a manufacturing operation of high productivity. However, it s not suited for production of hollow structures. A combination with a highly productive welding technique such as laser beam welding is now available, and one may expect it to be of reasonable economic benefit in the future.

  9. Superplastic Forming of Aluminum Multisheet Structures Fabricated Using Friction Stir Welding and Refill Friction Stir Spot Welding

    SciTech Connect

    Grant, Glenn J.; Herling, Darrell R.; Arbegast, William J.; Allen, Casey D.; Degen, Cassandra M.

    2006-12-20

    5083 aluminum multisheet packs that can be SPF formed into 3-D structural or integrally stiffened panels. Several configurations of 3-sheet egg crate and truss structures were friction stir welded and hot gas SPF formed in a parallel-platen SPF press. Data on weld conditions for optimum SPF forming as well as pre- and post- forming microstructures will be presented. It is found that FSW process conditions are a key feature of a successful SPF forming operation and the nugget microstructures and other features of the weld zone can be optimized to produce a wide range of weld region elongations. Friction Stir Welding may prove to be the enabler that allows aluminum to be considered in multisheet and integrally stiffened SPF Aluminum structures.

  10. Recovery of Mechanical Properties of a 6061-T6 Aluminum Weld by Heat Treatment After Welding

    NASA Astrophysics Data System (ADS)

    Pérez, Javier Serrano; Ambriz, Ricardo Rafael; López, Francisco Fernando Curiel; Vigueras, David Jaramillo

    2016-07-01

    The dilution effects in welds of a 6061-T6 (Al-Si-Mg) alloy obtained by the modified indirect electric arc (MIEA), using an ER4043 filler metal (Al-Si), and postweld heat treatment (PWHT) were analyzed. The soft zone (55 to 70 HV0.1) formed by the microstructural transformation in the heat-affected zone (HAZ) was eliminated. The hardness measurements were presented on a traditional microhardness profile and mapping representation. A hardening effect of the fusion zone was observed; the hardness values were above 120 HV0.1 and tended to be uniform. This behavior could be attributed to the chemical composition of the filler metal, the Mg migration from the base to the weld metal, and the reversible process of the PWHT, which promotes precipitation hardening. Improvement for yield (260 MPa) and tensile strength (310 MPa) of the MIEA joints was observed; these values were similar to those obtained for the base metal. However, the presence of porosity in the fusion zone limits the ductility of the joints (4.3 pct). Even though the yield and tensile strengths of the base metal and welded joints were similar, the stress concentration due to porosity in the weld metal generated data dispersion in fatigue life. As a consequence, the high-cycle fatigue life decreases with respect to the base metal. In contrast, when the crack propagates under elastic conditions, the crack-tip singularity is affected by the porosity in the weld metal (stress liberator). This aspect, in conjunction with the hardening effect in joints subjected to PWHT, improves the fatigue crack growth rate when compared to the as-welded condition.

  11. The study on microstructural and mechanical properties of weld heat affected zone of 7075-T651 aluminum alloy

    SciTech Connect

    Hwang, R.Y.; Chou, C.P.

    1997-12-22

    Aluminum alloys play an important role in aerospace industry due to their high strength and low density. The general accepted precipitation behavior of 7075 alloy was represented as: supersaturated solid solution {alpha}{sub ss} {yields} Gp zones {yields} {eta}{prime}(MgZn{sub 2}) {yields} {eta}(MgZn{sub 2}). The Addition of Cu in Al-Zn-Mg alloy would promote the transformation of GP zones into {eta}{prime}(MgZn{sub 2}) phase and stabilize the {eta}(MgZn{sub 2}) phase. The T6 temper has the maximum strength but lower ductility. The T73 temper may lose some strength, but can gain higher corrosion resistance and lower susceptibility to stress corrosion cracking as compared to the T6 temper. The welding fabrication can produce thermal cycling on the weldment. In the heat affected zone (HAZ) beside the fusion zone, different temperatures can be obtained. This would cause change of microstructure in the HAZ of aluminum alloy weldment. Many workers studied the behavior of weld HAZ by cutting the HAZ into many small pieces or using short time isothermal heat treatment to simulate the HAZ. This may lose some information, especially near the fusion zone, because high temperature gradient occurred in this region. In this study, the Gleeble system was used to simulate the weld HAZ. It can accurately simulate every point of weld HAZ by heating and cooling the specimen to the thermal history of weld HAZ as the same as measured. The microstructural and mechanical properties of weld HAZ of 7075-T651 alloy were investigated.

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  13. Friction Stir Weld Failure Mechanisms in Aluminum-Armor Structures Under Ballistic Impact Loading Conditions

    DTIC Science & Technology

    2013-01-01

    FSW joints found in thick aluminum -armor weldments, the overall ballistic performance of 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 13...welding ( FSW ) joints found in armor structures made of high-performance aluminum alloys (including solution-strengthened and age-hardenable aluminum alloy...grades). It is argued that due to the large width of FSW joints found in thick aluminum -armor weldments, the overall ballistic performance of the

  14. Influence of Process Parameters on Laser Weld Characteristics in Aluminum Alloys

    DTIC Science & Technology

    1988-08-01

    1 1󈧚 , 4 4 2.1.2 Alloying Element Vaporization Alloying elements added to aluminum for improving the mechanical properties and corrosion...effects the properties of the base metal surrounding the weld zone called the heat affected zone (HAZ). In the non-heat treatable aluminum alloys in the...Hydrogen in Aluminum . Magnesium, Copper, and Their Alloys . Int. Metall. Reviews, Review 201, 20:166-184. 31. Hatch, J.E. 1984. Aluminum , Properties and

  15. High strength cast aluminum alloy development

    NASA Astrophysics Data System (ADS)

    Druschitz, Edward A.

    The goal of this research was to understand how chemistry and processing affect the resulting microstructure and mechanical properties of high strength cast aluminum alloys. Two alloy systems were investigated including the Al-Cu-Ag and the Al-Zn-Mg-Cu systems. Processing variables included solidification under pressure (SUP) and heat treatment. This research determined the range in properties that can be achieved in BAC 100(TM) (Al-Cu micro-alloyed with Ag, Mn, Zr, and V) and generated sufficient property data for design purposes. Tensile, stress corrosion cracking, and fatigue testing were performed. CuAl2 and Al-Cu-Fe-Mn intermetallics were identified as the ductility limiting flaws. A solution treatment of 75 hours or longer was needed to dissolve most of the intermetallic CuAl 2. The Al-Cu-Fe-Mn intermetallic was unaffected by heat treatment. These results indicate that faster cooling rates, a reduction in copper concentration and a reduction in iron concentration might increase the ductility of the alloy by decreasing the size and amount of the intermetallics that form during solidification. Six experimental Al-Zn-Mg-Cu series alloys were produced. Zinc concentrations of 8 and 12wt% and Zn/Mg ratios of 1.5 to 5.5 were tested. Copper was held constant at 0.9%. Heat treating of the alloys was optimized for maximum hardness. Al-Zn-Mg-Cu samples were solution treated at 441°C (826°F) for 4 hours before ramping to 460°C (860°F) for 75 hours and then aged at 120°C (248°F) for 75 hours. X-ray diffraction showed that the age hardening precipitates in most of these alloys was the T phase (Mg32Zn 31.9Al17.1). Tensile testing of the alloys showed that the best mechanical properties were obtained in the lowest alloy condition. Chilled Al-8.2Zn-1.4Mg-0.9Cu solidified under pressure resulted in an alloy with a yield strength of 468MPa (68ksi), tensile strength of 525MPa (76ksi) and an elongation of 9%.

  16. A microstructural study of flash welded and aged 6061 and 6013 aluminum alloys

    SciTech Connect

    Barbosa, C.; Dille, J.; Delplancke, J.-L.; Rebello, J.M.A.

    2006-09-15

    Extruded, flash welded and artificially aged 6061 and 6013 aluminum alloys were analyzed with the use of techniques such as transmission electron microscopy (TEM) imaging, selected area electron diffraction (SAD) and X-ray energy-dispersive spectroscopy (EDS) in order to identify the precipitates present in both alloys. Vickers microindentation hardness measurements were performed at different distances from the weld interface. The results show a small decrease in hardness near the 6013 alloy weld interface. On the other hand, there is an important hardness drop near the 6061 weld interface. This drop can be explained by a lack of fine structural precipitation during the aging treatment in the 6061 weld interface zone.

  17. The effect of impurity gasses on variable polarity plasma arc welded 2219 aluminum

    NASA Technical Reports Server (NTRS)

    Mcclure, John C.; Torres, Martin R.; Gurevitch, Alan C.; Newman, Robert A.

    1989-01-01

    Variable polarity plasma arc (VPPA) welding has been used with considerable success by NASA for the welds on the Space Shuttle External Tank as well as by others concerned with high quality welded structures. The effects of gaseous contaminants on the appearance of VPPA welds on 2219 aluminum are examined so that a welder can recognize that such contamination is present and take corrective measures. There are many possible sources of such contamination including, contaminated gas bottles, leaks in the gas plumbing, inadequate shield gas flow, condensed moisture in the gas lines or torch body, or excessive contaminants on the workpiece. The gasses chosen for study in the program were nitrogen, oxygen, methane, and hydrogen. Welds were made in a carefully controlled environment and comparisons were made between welds with various levels of these contaminants and welds made with research purity (99.9999 percent) gasses. Photographs of the weld front and backside as well as polished and etched cross sections are presented.

  18. The effects of microstructure on MIC susceptibility in high strength aluminum alloys

    SciTech Connect

    Walsh, D.W.

    1999-11-01

    Aluminum alloys, and in particular Al-Li-Cu alloys are attractive to the aerospace industry. The high specific strength and stiffness of these alloys will improve lift efficiency, fuel economy, performance and increase payload capabilities of air and spacecraft. The objectives of this work were to examine the corrosion behavior of Al 2195 (UNS A92195) (Al-4Cu-1Li) and to assess the effect of welding on corrosion behavior in biologically active and in sterile waters. Al 2219 (UNS A922 19) samples were used in parallel tests to provide a baseline for the data generated. In this study samples were exposed to mild corrosive water solutions in both the as received and as welded conditions. The results of the study indicate exposure to biologically active solutions increases the corrosion rate. In addition, welding increases the corrosion rate in both Al 2195 and Al 2219, and causes severe localization in Al 2195. Furthermore, autogenously welded Al 2195 samples were more susceptible to attack than heterogeneously welded Al 2195 samples. Heterogeneously welded samples in both materials also had high corrosion rates, but only the Al 2195 material was subject to localization of attack. The partially melted zones of Al 2195 samples were subject to severe, focused attack. In Al 2219, interdendritic constituents in welded areas and intergranular constituents in base material were cathodic to the Al rich matrix materials. In Al 2195, some interdendritic constituents in welded areas and intergranular constituents in base material were anodic to the Al rich matrix materials. Corrosion resistance was correlated to material microstructure using optical microscopy, scanning electron microscopy, electron probe microanalysis and polarization resistance.

  19. Ultrasonic girth weld evaluation for aluminum substrate of spherical Kevlar-epoxy test specimens

    SciTech Connect

    Brosey, W.D.; Dews, T.W.

    1984-08-28

    An ultrasonic weld inspection has been developed for the girth weld of the aluminum substrate for a Kevlar-epoxy filament wound test specimen. The filament wound spheres are test coupons in a study to evaluate NDE techniques on a composite material with enclosed geometry. The girth weld of the aluminum substrate has been examined to ensure the weld is not a weak point in the coupon in which failure will initiate. Analog and B-scan data are combined to determine the presence of lack of penetration, suckback, protrusion, or porosity in the weld. The data are calibrated with a standard and then plotted as analog, B-scan, or color contour data as a function of angular position around the weld.

  20. Preventive strength training improves working ergonomics during welding.

    PubMed

    Krüger, Karsten; Petermann, Carmen; Pilat, Christian; Schubert, Emil; Pons-Kühnemann, Jörn; Mooren, Frank C

    2015-01-01

    To investigate the effect of a preventive strength training program on cardiovascular, metabolic and muscular strains during welding. Welders are one of the occupation groups which typically have to work in extended forced postures which are known to be an important reason for musculoskeletal disorders. Subjects (exercise group) accomplished a 12-week strength training program, while another group served as controls (control group). Pre and post training examinations included the measurements of the one repetition maximum and an experimental welding test. Local muscle activities were analysed by surface electromyography. Furthermore, heart rate, blood pressure, lactate and rating of perceived exertion were examined. In the exercise group, strength training lead to a significant increase of one repetition maximum in all examined muscles (p<.05). During the experimental welding test muscle activities of trunk and shoulder muscles and arm muscles were significantly reduced in the exercise group after intervention (p<.05). While no changes of neither cardiovascular nor metabolic parameters were found, subjects of the exercise group rated a significantly decreased rate of perceived exertion welding (p<.05). Effects of strength training can be translated in an improved working ergonomics and tolerance against the exposure to high physical demands at work.

  1. Laser beam interactions with vapor plumes during Nd:YAG laser welding on aluminum

    NASA Astrophysics Data System (ADS)

    Peebles, H. C.; Russo, A. J.; Hadley, G. R.; Akau, R. L.

    Welds produced on pure aluminum targets using pulsed Nd:YAG lasers can be accurately described using a relatively simple conduction mode heat transfer model provided that the fraction of laser energy absorbed is known and the amount of metal vaporized is smalled however at laser fluences commonly used in many production welding schedules significant aluminum vaporization does occur. The possible mechanisms have been identified which could result in laser beam attenuation by the vapor plume.

  2. Technique for in-place welding of aluminum backed up by a combustible material

    NASA Technical Reports Server (NTRS)

    Spagnuolo, A. C.

    1971-01-01

    Welding external aluminum jacket, tightly wrapped around inner layer of wood composition fiberboard, in oxygen free environment prevents combustion and subsequent damage to underlying fiberboard. Technique also applies to metal cutting in similar assemblies without disassembly to remove combustible materials from welding heat proximity.

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

    SciTech Connect

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

    2015-05-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  5. Polymer Welding and Self-healing: Strength Through Entanglements

    NASA Astrophysics Data System (ADS)

    Ge, Ting; Robbins, Mark O.; Perahia, Dvora; Grest, Gary S.

    2013-03-01

    Polymer interfaces are crucial in determining the mechanical strength of many systems. A common means of welding joints or self-healing cracks is to apply heat and allow polymers to interdiffuse. As the microscopic mechanism of interface strengthening is difficult to isolate experimentally, we probe the molecular origins of interfacial strength using large scale molecular simulations of welding and self-healing of cut systems. Systems are heated well above the glass temperature Tg and then quenched below Tg for mechanical testing. The interfacial strength is characterized by the maximum shear stress σmax before failure. As strength grows, the dominant failure mode changes from chain pullout at the interface to chain scission, as in the bulk. In all simulations, σmax saturates long before polymers diffuse by their own size. Bulk strength is observed for miscible welds, while strength is suppressed for cut systems due to short chain segments that remain near the interface. Entanglements are tracked using the Primitive Path Analysis. We find that the bulk response is not fully recovered until the density of entanglements at the interface reaches the bulk value. Moreover, the increase of σmax beforesaturationisproportionaltothenumberofinterfacial entanglements between chains from opposite sides, which correlates linearly with the interdiffusion depth. This material is based upon work supported by NSF Grant DMR-1006805 and DMR-0907390.

  6. Ultrasonic-promoted rapid TLP bonding of fine-grained 7034 high strength aluminum alloys.

    PubMed

    Guo, Weibing; Leng, Xuesong; Luan, Tianmin; Yan, Jiuchun; He, Jingshan

    2017-05-01

    High strength aluminum alloys are extremely sensitive to the thermal cycle of welding. An ultrasonic-promoted rapid TLP bonding with an interlayer of pure Zn was developed to join fine-grained 7034 aluminum alloys at the temperature of lower 400°C. The oxide film could be successfully removed with the ultrasonic vibration, and the Al-Zn eutectic liquid phase generated once Al and Zn contacted with each other. Longer ultrasonic time can promote the diffusion of Zn into the base metal, which would shorten the holding time to complete isothermal solidification. The joints with the full solid solution of α-Al can be realized with the ultrasonic action time of 60s and holding time of only 3min at 400°C, and the shear strength of joints could reach 223MPa. The joint formation mechanism and effects of ultrasounds were discussed in details.

  7. Influence of shielding gas on the mechanical and metallurgical properties of DP-GMA-welded 5083-H321 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Koushki, Amin Reza; Goodarzi, Massoud; Paidar, Moslem

    2016-12-01

    In the present research, 6-mm-thick 5083-H321 aluminum alloy was joined by the double-pulsed gas metal arc welding (DP-GMAW) process. The objective was to investigate the influence of the shielding gas composition on the microstructure and properties of GMA welds. A macrostructural study indicated that the addition of nitrogen and oxygen to the argon shielding gas resulted in better weld penetration. Furthermore, the tensile strength and bending strength of the welds were improved when oxygen and nitrogen (at concentrations as high as approximately 0.1vol%) were added to the shielding gas; however, these properties were adversely affected when the oxygen and nitrogen contents were increased further. This behavior was attributed to the formation of excessive brown and black oxide films on the bead surface, the formation of intermetallic compounds in the weld metal, and the formation of thicker oxide layers on the bead surface with increasing nitrogen and oxygen contents in the argon-based shielding gas. Analysis by energy-dispersive X-ray spectroscopy revealed that most of these compounds are nitrides or oxides.

  8. Laser Welded versus Resistance Spot Welded Bone Implants: Analysis of the Thermal Increase and Strength

    PubMed Central

    Fornaini, Carlo; Meleti, Marco; Bonanini, Mauro; Lagori, Giuseppe; Vescovi, Paolo; Merigo, Elisabetta; Nammour, Samir

    2014-01-01

    Introduction. The first aim of this “ex vivo split mouth” study was to compare the thermal elevation during the welding process of titanium bars to titanium implants inserted in pig jaws by a thermal camera and two thermocouples. The second aim was to compare the strength of the joints by a traction test with a dynamometer. Materials and Methods. Six pigs' jaws were used and three implants were placed on each side of them for a total of 36 fixtures. Twelve bars were connected to the abutments (each bar on three implants) by using, on one side, laser welding and, on the other, resistance spot welding. Temperature variations were recorded by thermocouples and by thermal camera while the strength of the welded joint was analyzed by a traction test. Results. For increasing temperature, means were 36.83 and 37.06, standard deviations 1.234 and 1.187, and P value 0.5763 (not significant). For traction test, means were 195.5 and 159.4, standard deviations 2.00 and 2.254, and P value 0.0001 (very significant). Conclusion. Laser welding was demonstrated to be able to connect titanium implant abutments without the risk of thermal increase into the bone and with good results in terms of mechanical strength. PMID:25110731

  9. Microstructural Characterization of 6061 Aluminum to 304L Stainless Steel Inertia Welds

    SciTech Connect

    Dunn, K.A.

    1999-09-29

    'Microstructural characterization of 6061-T6 aluminum-to-Type 304L stainless steel inertia welds provided a technical basis to conclude that transition joints fabricated from such welds should satisfactorily contain helium/hydrogen gas mixtures. This conclusion is based on the lack of semi-continuous alignments of particles and/or inclusions at, or near, the aluminum-to-stainless steel interface. These dissimilar metal transition joints play a key role in the operation of an accelerator driven, spallation neutron source designed for the production of tritium. The Accelerator Production of Tritium system will produce tritium through neutron interactions with 3He gas contained in water-cooled, 6061-T6 aluminum pressure tubes. Current design concepts include thousands of thin-walled pressure tubes distributed throughout a number of aluminum-clad, lead-filled, blanket modules. The aluminum pressure tubes are connected to a tritium extraction and purification system through a stainless steel manifold. The transition from aluminum to stainless steel is made via transition joints machined from the aluminum-to-stainless steel inertia welds. The paper describes the baseline microstructural characterization of the welds, including optical, scanning and transmission electron microscopy and uses that characterization to evaluate potential gas leakage across the weld.'

  10. Relationship between apposition pressure during welding and tensile strength of the acute weld

    NASA Astrophysics Data System (ADS)

    Wu, Paul J.; Walsh, Joseph T., Jr.

    2001-05-01

    Dye-assisted photothermal welding is a technique used to close wounds by thermally cross-linking collagen across apposed tissue edges. For a successful weld, not only do laser parameters have to be optimized, but also apposition of the incision has to be consistent and controlled. The objective of this study was to quantify the relationship between the applied apposition pressure (i.e., the compressive force holding the wound closed during the welding procedure divided by the area of the skin-to-skin interface) and the tensile strength of the wound following the welding procedure. By using a clamping device made of two complementary pieces, each 3 cm wide with a row of 10 equally spaced blunt wire mesh tips, the apposition pressure along a 2-cm-long incision in each albino guinea pig was quantified using a 127-micrometers -thick load cell and varied from 0-1.8 kgf/cm2. A continuous wave, Nd:YAG laser emitting 10.0 W of 1.06-micrometers radiation from a 600-micrometers -diameter fiber irradiating a 5-mm-diameter spot size was scanned across the incision in order to deliver 300 J of total energy. As the apposition pressure of the incisions was increased, the resulting tensile strength of welded skin increased in a sigmoidal manner. For this welding technique, an apposition pressure of at least 1.2 kgf/cm2 is necessary to obtain maximum weld strength of the skin (2.56+/- 0.36 kg/cm2).

  11. Effect of thermal exposure, forming, and welding on high-temperature, dispersion-strengthened aluminum alloy: Al-8Fe-1V-2Si

    NASA Technical Reports Server (NTRS)

    Kennedy, J. R.; Gilman, P. S.; Zedalis, M. S.; Skinner, D. J.; Peltier, J. M.

    1991-01-01

    The feasibility of applying conventional hot forming and welding methods to high temperature aluminum alloy, Al-8Fe-1V-2Si (FVS812), for structural applications and the effect of thermal exposure on mechanical properties were determined. FVS812 (AA8009) sheet exhibited good hot forming and resistance welding characteristics. It was brake formed to 90 deg bends (0.5T bend radius) at temperatures greater than or equal to 390 C (730 F), indicating the feasibility of fabricating basic shapes, such as angles and zees. Hot forming of simple contoured-flanged parts was demonstrated. Resistance spot welds with good static and fatigue strength at room and elevated temperatures were readily produced. Extended vacuum degassing during billet fabrication reduced porosity in fusion and resistance welds. However, electron beam welding was not possible because of extreme degassing during welding, and gas-tungsten-arc welds were not acceptable because of severely degraded mechanical properties. The FVS812 alloy exhibited excellent high temperature strength stability after thermal exposures up to 315 C (600 F) for 1000 h. Extended billet degassing appeared to generally improve tensile ductility, fatigue strength, and notch toughness. But the effects of billet degassing and thermal exposure on properties need to be further clarified. The manufacture of zee-stiffened, riveted, and resistance-spot-welded compression panels was demonstrated.

  12. 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.

  13. A Micro-Electrochemical Study of Friction Stir Welded Aluminum 6061-T6

    NASA Technical Reports Server (NTRS)

    Hintze, Paul E.; Calle, Luz M.

    2005-01-01

    The corrosion behavior of friction stir welded Aluminum alloy 606 1-T6 was studied using a micro-electrochemical cell. The micro-electrochemical cell has a measurement area of about 0.25 square mm which allows for measurement of corrosion properties at a very small scale. The corrosion and breakdown potentials were measured at many points inside and outside the weld along lines perpendicular to the weld. The breakdown potential is approximately equal inside and outside the weld; however, it is lower in the narrow border between the weld and base material. The results of electrochemical measurements were correlated to micro-structural analysis. The corrosion behavior of the friction stir welded samples was compared to tungsten inert gas (TIG) welded samples of the same material.

  14. Design for low-cost gas metal arc weld-based aluminum 3-D printing

    NASA Astrophysics Data System (ADS)

    Haselhuhn, Amberlee S.

    Additive manufacturing, commonly known as 3-D printing, has the potential to change the state of manufacturing across the globe. Parts are made, or printed, layer by layer using only the materials required to form the part, resulting in much less waste than traditional manufacturing methods. Additive manufacturing has been implemented in a wide variety of industries including aerospace, medical, consumer products, and fashion, using metals, ceramics, polymers, composites, and even organic tissues. However, traditional 3-D printing technologies, particularly those used to print metals, can be prohibitively expensive for small enterprises and the average consumer. A low-cost open-source metal 3-D printer has been developed based upon gas metal arc weld (GMAW) technology. Using this technology, substrate release mechanisms have been developed, allowing the user to remove a printed metal part from a metal substrate by hand. The mechanical and microstructural properties of commercially available weld alloys were characterized and used to guide alloy development in 4000 series aluminum-silicon alloys. Wedge casting experiments were performed to screen magnesium, strontium, and titanium boride alloying additions in hypoeutectic aluminum-silicon alloys for their properties and the ease with which they could be printed. Finally, the top performing alloys, which were approximately 11.6% Si modified with strontium and titanium boride were cast, extruded, and drawn into wire. These wires were printed and the mechanical and microstructural properties were compared with those of commercially available alloys. This work resulted in an easier-to-print aluminum-silicon-strontium alloy that exhibited lower porosity, equivalent yield and tensile strengths, yet nearly twice the ductility compared to commercial alloys.

  15. 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

  16. Laser Deep Penetration Welding of an Aluminum Alloy with Simultaneously Applied Vibrations

    NASA Astrophysics Data System (ADS)

    Woizeschke, Peer; Radel, Tim; Nicolay, Paul; Vollertsen, Frank

    2016-12-01

    In aluminum welding, the grain structure of produced seams is an essential factor with respect to the seam properties. In the casting technology the effect of mechanical vibrations on the grain growth during the solidification of liquid metals is known as a refinement method. In this paper, the transferability of this approach from comparatively long-time processes in the field of casting to the short-time process of laser deep penetration welding is investigated. Therefore, specimens were sinusoidal vibrated with frequencies up to 4 kHz during bead-on-plate full-penetration welding experiments. The resulting grain size was determined by applying the circular intercept procedure on the center of a cross-section micrograph of each weld. The results show that grain refinement is in general achievable by mechanical vibrations in the audible frequency range during laser full penetration keyhole welding of the aluminum alloy EN AW-5083.

  17. Self-Reacting Friction Stir Welding for Aluminum Complex Curvature Applications

    NASA Technical Reports Server (NTRS)

    Brown, Randy J.; Martin, W.; Schneider, J.; Hartley, P. J.; Russell, Carolyn; Lawless, Kirby; Jones, Chip

    2003-01-01

    This viewgraph representation provides an overview of sucessful research conducted by Lockheed Martin and NASA to develop an advanced self-reacting friction stir technology for complex curvature aluminum alloys. The research included weld process development for 0.320 inch Al 2219, sucessful transfer from the 'lab' scale to the production scale tool and weld quality exceeding strenght goals. This process will enable development and implementation of large scale complex geometry hardware fabrication. Topics covered include: weld process development, weld process transfer, and intermediate hardware fabrication.

  18. Ultrasonic-assisted friction stir welding on V95AT1 (7075) aluminum alloy

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    Ultrasonic-assisted friction stir butt welding on aluminum alloy V95AT1 (7075) has been carried out. Samples have been characterized using metallography, microhardness and XRD. As shown, ultrasonic treatment during welding provides extra plasticizing of metal and better stirring efficiency. The latter serves for elimination of defects, such as root flaw and grain refining in the stir zone. The stress state in the welded joint is characterized by tensile stress in the direction of the weld seam centerline and compression in the transversal direction. The ultrasonic treatment was shown to increase the compression stress and relieve the tensile one.

  19. Taguchi Optimization of Pulsed Current GTA Welding Parameters for Improved Corrosion Resistance of 5083 Aluminum Welds

    NASA Astrophysics Data System (ADS)

    Rastkerdar, E.; Shamanian, M.; Saatchi, A.

    2013-04-01

    In this study, the Taguchi method was used as a design of experiment (DOE) technique to optimize the pulsed current gas tungsten arc welding (GTAW) parameters for improved pitting corrosion resistance of AA5083-H18 aluminum alloy welds. A L9 (34) orthogonal array of the Taguchi design was used, which involves nine experiments for four parameters: peak current ( P), base current ( B), percent pulse-on time ( T), and pulse frequency ( F) with three levels was used. Pitting corrosion resistance in 3.5 wt.% NaCl solution was evaluated by anodic polarization tests at room temperature and calculating the width of the passive region (∆ E pit). Analysis of variance (ANOVA) was performed on the measured data and S/ N (signal to noise) ratios. The "bigger is better" was selected as the quality characteristic (QC). The optimum conditions were found as 170 A, 85 A, 40%, and 6 Hz for P, B, T, and F factors, respectively. The study showed that the percent pulse-on time has the highest influence on the pitting corrosion resistance (50.48%) followed by pulse frequency (28.62%), peak current (11.05%) and base current (9.86%). The range of optimum ∆ E pit at optimum conditions with a confidence level of 90% was predicted to be between 174.81 and 177.74 mVSCE. Under optimum conditions, the confirmation test was carried out, and the experimental value of ∆ E pit of 176 mVSCE was in agreement with the predicted value from the Taguchi model. In this regard, the model can be effectively used to predict the ∆ E pit of pulsed current gas tungsten arc welded joints.

  20. Prediction of Tensile Strength of Friction Stir Weld Joints with Adaptive Neuro-Fuzzy Inference System (ANFIS) and Neural Network

    NASA Technical Reports Server (NTRS)

    Dewan, Mohammad W.; Huggett, Daniel J.; Liao, T. Warren; Wahab, Muhammad A.; Okeil, Ayman M.

    2015-01-01

    Friction-stir-welding (FSW) is a solid-state joining process where joint properties are dependent on welding process parameters. In the current study three critical process parameters including spindle speed (??), plunge force (????), and welding speed (??) are considered key factors in the determination of ultimate tensile strength (UTS) of welded aluminum alloy joints. A total of 73 weld schedules were welded and tensile properties were subsequently obtained experimentally. It is observed that all three process parameters have direct influence on UTS of the welded joints. Utilizing experimental data, an optimized adaptive neuro-fuzzy inference system (ANFIS) model has been developed to predict UTS of FSW joints. A total of 1200 models were developed by varying the number of membership functions (MFs), type of MFs, and combination of four input variables (??,??,????,??????) utilizing a MATLAB platform. Note EFI denotes an empirical force index derived from the three process parameters. For comparison, optimized artificial neural network (ANN) models were also developed to predict UTS from FSW process parameters. By comparing ANFIS and ANN predicted results, it was found that optimized ANFIS models provide better results than ANN. This newly developed best ANFIS model could be utilized for prediction of UTS of FSW joints.

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

    NASA Technical Reports Server (NTRS)

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

    1944-01-01

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

  2. Effects of Fusion Tack Welds on Self-Reacting Friction Stir Welds

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.; Pendleton, M. L.; Brooke, S. A.; Russell, C. K.

    2012-01-01

    In order to know whether fusion tack welds would affect the strength of self-reacting friction stir seam welds in 2195-T87 aluminum alloy, the fracture stresses of 144 tensile test coupons cut from 24 welded panels containing segments of friction stir welds were measured. Each of the panels was welded under unique processing conditions. A measure of the effect of the tack welds for each panel was devised. An analysis of the measures of the tack weld effect supported the hypothesis that fusion tack welds do not affect the strength of self-reacting friction stir welds to a 5% level of confidence.

  3. Tensile and flexural strength of commercially pure titanium submitted to laser and tungsten inert gas welds.

    PubMed

    Atoui, Juliana Abdallah; Felipucci, Daniela Nair Borges; Pagnano, Valéria Oliveira; Orsi, Iara Augusta; Nóbilo, Mauro Antônio de Arruda; Bezzon, Osvaldo Luiz

    2013-01-01

    This study evaluated the tensile and flexural strength of tungsten inert gas (TIG) welds in specimens made of commercially pure titanium (CP Ti) compared with laser welds. Sixty cylindrical specimens (2 mm diameter x 55 mm thick) were randomly assigned to 3 groups for each test (n=10): no welding (control), TIG welding (10 V, 36 A, 8 s) and Nd:YAG laser welding (380 V, 8 ms). The specimens were radiographed and subjected to tensile and flexural strength tests at a crosshead speed of 1.0 mm/min using a load cell of 500 kgf applied on the welded interface or at the middle point of the non-welded specimens. Tensile strength data were analyzed by ANOVA and Tukey's test, and flexural strength data by the Kruskal-Wallis test (α=0.05). Non-welded specimens presented significantly higher tensile strength (control=605.84 ± 19.83) (p=0.015) and flexural strength (control=1908.75) (p=0.000) than TIG- and laser-welded ones. There were no significant differences (p>0.05) between the welding types for neither the tensile strength test (TIG=514.90 ± 37.76; laser=515.85 ± 62.07) nor the flexural strength test (TIG=1559.66; laser=1621.64). As far as tensile and flexural strengths are concerned, TIG was similar to laser and could be suitable to replace laser welding in implant-supported rehabilitations.

  4. Numerical simulation of friction stir spot welding process for aluminum alloys

    NASA Astrophysics Data System (ADS)

    Kim, Dongun; Badarinarayan, Harsha; Ryu, Ill; Kim, Ji Hoon; Kim, Chongmin; Okamoto, Kazutaka; Wagoner, R. H.; Chung, Kwansoo

    2010-04-01

    Thermo-mechanical simulations of the Friction Stir Spot Welding (FSSW) processes were performed for AA5083-H18 and AA6022-T4, utilizing commercial Finite Element Method (FEM) and Finite Volume Method (FVM) codes, which are based on Lagrangian and Eulerian formulations, respectively. The Lagrangian explicit dynamic FEM code, PAM-CRASH, and the Eulerian Computational Fluid Dynamics (CFD) FVM code, STAR-CD, were utilized to understand the effect of pin geometry on weld strength and material flow under the unsteady state condition. Using FVM code, material flow patterns near the tool boundary were analyzed to explain weld strength difference between welds by a cylindrical pin and welds by a triangular pin, whereas the frictional energy concept using the FEM code had a limited capacity to explain the weld strength difference.

  5. Comparison of the Effects of Tool Geometry for Friction Stir Welding Thin Sheet Aluminum Alloys for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Merry, Josh; Takeshita, Jennifer; Tweedy, Bryan; Burford, Dwight

    2006-01-01

    In this presentation, the results of a recent study on the effect of pin tool design for friction stir welding thin sheets (0.040") of aluminum alloys 2024 and 7075 are provided. The objective of this study was to investigate and document the effect of tool shoulder and pin diameter, as well as the presence of pin flutes, on the resultant microstructure and mechanical properties at both room temperature and cryogenic temperature. Specifically, the comparison between three tools will include: FSW process load analysis (tool forces required to fabricate the welds), Static Mechanical Properties (ultimate tensile strength, yield strength, and elongation), and Process window documenting the range of parameters that can be used with the three pin tools investigated. All samples were naturally aged for a period greater than 10 days. Prior research has shown 7075 may require post weld heat treatment. Therefore, an additional pair of room temperature and cryogenic temperature samples was post-weld aged to the 7075-T7 condition prior to mechanical testing.

  6. Physical Simulation Method for the Investigation of Weld Seam Formation During the Extrusion of Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Fang, Gang; Nguyen, Duc-Thien; Zhou, Jie

    2016-12-01

    Extrusion through the porthole die is a predominant forming process used in the production of hollow aluminum alloy profiles across the aluminum extrusion industry. Longitudinal weld seams formed during the process may negatively influence the quality of extruded profiles. It is therefore of great importance to understand the formation of weld seams inside the welding chamber during extrusion, as affected by extrusion process variables and die design. Previously developed physical simulation methods could not fully reproduce the thermomechanical conditions inside the welding chamber of porthole die. In this research, a novel physical simulation method for the investigation of weld seam formation during extrusion was developed. With a tailor-designed tooling set mounted on a universal testing machine, the effects of temperature, speed, and strain on the weld seam quality of the 6063 alloy were investigated. The strains inside the welding chamber were found to be of paramount importance for the bonding of metal streams, accompanied by microstructural changes, i.e., recovery or recrystallization, depending on the local deformation condition. The method was shown to be able to provide guidelines for the design of porthole dies and choice of extrusion process variables, thereby reducing the scrap rate of aluminum extrusion operation.

  7. Fine-tuned Remote Laser Welding of Aluminum to Copper with Local Beam Oscillation

    NASA Astrophysics Data System (ADS)

    Fetzer, Florian; Jarwitz, Michael; Stritt, Peter; Weber, Rudolf; Graf, Thomas

    Local beam oscillation in remote laser welding of aluminum to copper was investigated. Sheets of 1 mm thickness were welded in overlap configuration with aluminum as top material. The laser beam was scanned in a sinusoidal mode perpendicular to the direction of feed and the influence of the oscillation parameters frequency and amplitude on the weld geometry was investigated. Scanning frequencies up to 1 kHz and oscillation amplitudes in the range from 0.25 mm to 1 mm were examined. Throughout the experiments the laser power and the feed rate were kept constant. A decrease of welding depth with amplitude and frequency is found. The scanning amplitude had a strong influence and allowed coarse setting of the welding depth into the lower material, while the frequency allowed fine tuning in the order of 10% of the obtained depth. The oscillation parameters were found to act differently on the aluminum sheet compared to copper sheet regarding the amount of fused material. It is possible to influence the geometry of the fused zones separately for both sheets. Therefore the average composition in the weld can be set with high precision via the oscillation parameters. A setting of the generated intermetallics in the weld zone is possible without adjustment of laser power and feed rate.

  8. Microstructure and Fatigue Properties of Ultrasonic Spot Welded Joints of Aluminum 5754 Alloy

    NASA Astrophysics Data System (ADS)

    Mirza, F. A.; Macwan, A.; Bhole, S. D.; Chen, D. L.

    2016-05-01

    The purpose of this investigation was to evaluate the microstructural change, lap shear tensile load, and fatigue resistance of ultrasonic spot welded joints of aluminum 5754 alloy for automotive applications. A unique "necklace"-type structure with very fine equiaxed grains was observed to form along the weld line due to the mechanical interlocking coupled with the occurrence of dynamic recrystallization. The maximum lap shear tensile strength of 85 MPa and the fatigue limit of about 0.5 kN (at 1 × 107 cycles) were achieved. The tensile fracture occurred at the Al/Al interface in the case of lower energy inputs, and at the edge of nugget zone in the case of higher energy inputs. The maximum cyclic stress for the transition of fatigue fracture mode from the transverse through-thickness crack growth to the interfacial failure increased with increasing energy input. Fatigue crack propagation was mainly characterized by the formation of fatigue striations, which usually appeared perpendicular to the fatigue crack propagation.

  9. Bobbin-Tool Friction-Stir Welding of Thick-Walled Aluminum Alloy Pressure Vessels

    SciTech Connect

    Dalder, E C; Pastrnak, J W; Engel, J; Forrest, R S; Kokko, E; Ternan, K M; Waldron, D

    2007-06-06

    It was desired to assemble thick-walled Al alloy 2219 pressure vessels by bobbin-tool friction-stir welding. To develop the welding-process, mechanical-property, and fitness-for-service information to support this effort, extensive friction-stir welding-parameter studies were conducted on 2.5 cm. and 3.8 cm. thick 2219 Al alloy plate. Starting conditions of the plate were the fully-heat-treated (-T62) and in the annealed (-O) conditions. The former condition was chosen with the intent of using the welds in either the 'as welded' condition or after a simple low-temperature aging treatment. Since preliminary stress-analyses showed that stresses in and near the welds would probably exceed the yield-strength of both 'as welded' and welded and aged weld-joints, a post-weld solution-treatment, quenching, and aging treatment was also examined. Once a suitable set of welding and post-weld heat-treatment parameters was established, the project divided into two parts. The first part concentrated on developing the necessary process information to be able to make defect-free friction-stir welds in 3.8 cm. thick Al alloy 2219 in the form of circumferential welds that would join two hemispherical forgings with a 102 cm. inside diameter. This necessitated going to a bobbin-tool welding-technique to simplify the tooling needed to react the large forces generated in friction-stir welding. The bobbin-tool technique was demonstrated on both flat-plates and plates that were bent to the curvature of the actual vessel. An additional issue was termination of the weld, i.e. closing out the hole left at the end of the weld by withdrawal of the friction-stir welding tool. This was accomplished by friction-plug welding a slightly-oversized Al alloy 2219 plug into the termination-hole, followed by machining the plug flush with both the inside and outside surfaces of the vessel. The second part of the project involved demonstrating that the welds were fit for the intended service. This

  10. Forge Welding of Magnesium Alloy to Aluminum Alloy Using a Cu, Ni, or Ti Interlayer

    NASA Astrophysics Data System (ADS)

    Yamagishi, Hideki; Sumioka, Junji; Kakiuchi, Shigeki; Tomida, Shogo; Takeda, Kouichi; Shimazaki, Kouichi

    2015-08-01

    The forge-welding process was examined to develop a high-strength bonding application of magnesium (Mg) alloy to aluminum (Al) alloy under high-productivity conditions. The effect of the insert material on the tensile strength of the joints, under various preheat temperatures and pressures, was investigated by analyzing the reaction layers of the bonded interface. The tensile strengths resulting from direct bonding, using pure copper (Cu), pure nickel (Ni), and pure titanium (Ti) inserts were 56, 100, 119, and 151 MPa, respectively. The maximum joint strength reached 93 pct with respect to the Mg cast billet. During high-pressure bonding, a microscopic plastic flow occurred that contributed to an anchor effect and the generation of a newly formed surface at the interface, particularly prominent with the Ti insert in the form of an oxide layer. The bonded interfaces of the maximum-strength inserts were investigated using scanning electron microscopy-energy-dispersive spectroscopy and electron probe microanalysis. The diffusion reaction layer at the bonded interface consisted of brittle Al-Mg intermetallics having a thickness of approximately 30 μm. In contrast, for the three inserts, the thicknesses of the diffusion reaction layer were infinitely thin. For the pure Ti insert, exhibiting the maximum tensile strength value among the inserts tested, focused ion beam-transmission electron microscopy-EDS analysis revealed a 60-nm-thick Al-Ti reaction layer, which had formed at the bonded interface on the Mg alloy side. Thus, a high-strength Al-Mg bonding method in air was demonstrated, suitable for mass production.

  11. High Rotation Speed Friction Stir Welding for 2014 Aluminum Alloy Thin Sheets

    NASA Astrophysics Data System (ADS)

    Chen, Shujin; Zhou, Yang; Xue, Junrong; Ni, Ruiyang; Guo, Yue; Dong, Jianghui

    2017-02-01

    In this study, 2014 aluminum alloy sheets with 1 mm thickness are welded successfully by friction stir welding (FSW) robot under the condition of high rotation speed. When the high rotation speed of 10,000-16,500 rpm is applied, the lower axial pressure (less than 200 N) is obtained, which reduces stiffness requirements for equipment. Welding deformation is inevitable because high rotation speed can easily result in rapid heating rate and uneven heat input. The welding distortion caused by two cooling methods is measured, respectively, by laser range finder. The experimental results show that the welding distortion is smaller under the condition of water cooling. When the rotation speed is up to 15,000 rpm and welding speed 50-170 mm/min, the whole welding process is controllable. Under the higher rotation speed condition, the welding defects disappear gradually and more stable mechanical properties can be obtained up to 75% of base metal (ω = 16,000 rpm, ν = 110 mm/min). The results of different welding parameters demonstrate that the high rotation speed can increase material mixing and reduce the axial force (z force), and it can benefit lightweight sheet welding by using FSW robot.

  12. High Rotation Speed Friction Stir Welding for 2014 Aluminum Alloy Thin Sheets

    NASA Astrophysics Data System (ADS)

    Chen, Shujin; Zhou, Yang; Xue, Junrong; Ni, Ruiyang; Guo, Yue; Dong, Jianghui

    2017-03-01

    In this study, 2014 aluminum alloy sheets with 1 mm thickness are welded successfully by friction stir welding (FSW) robot under the condition of high rotation speed. When the high rotation speed of 10,000-16,500 rpm is applied, the lower axial pressure (less than 200 N) is obtained, which reduces stiffness requirements for equipment. Welding deformation is inevitable because high rotation speed can easily result in rapid heating rate and uneven heat input. The welding distortion caused by two cooling methods is measured, respectively, by laser range finder. The experimental results show that the welding distortion is smaller under the condition of water cooling. When the rotation speed is up to 15,000 rpm and welding speed 50-170 mm/min, the whole welding process is controllable. Under the higher rotation speed condition, the welding defects disappear gradually and more stable mechanical properties can be obtained up to 75% of base metal (ω = 16,000 rpm, ν = 110 mm/min). The results of different welding parameters demonstrate that the high rotation speed can increase material mixing and reduce the axial force (z force), and it can benefit lightweight sheet welding by using FSW robot.

  13. Ideal pure shear strength of aluminum and copper.

    PubMed

    Ogata, Shigenobu; Li, Ju; Yip, Sidney

    2002-10-25

    Although aluminum has a smaller modulus in [111]<112> shear than that of copper, we find by first-principles calculation that its ideal shear strength is larger because of a more extended deformation range before softening. This fundamental behavior, along with an abnormally high intrinsic stacking fault energy and a different orientation dependence on pressure hardening, are traced to the directional nature of its bonding. By a comparative analysis of ion relaxations and valence charge redistributions in aluminum and copper, we arrive at contrasting descriptions of bonding characteristics in these two metals that can explain their relative strength and deformation behavior.

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

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2017-02-01

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

  16. Low-temperature friction-stir welding of 2024 aluminum

    SciTech Connect

    Benavides, S.; Li, Y.; Murr, L.E.; Brown, D.; McClure, J.C.

    1999-09-10

    Solid-state, friction-stir welding (FSW) has been demonstrated to involve dynamic recrystallization producing ultra-fine, equiaxed grain structures to facilitate superplastic deformation as the welding or joining mechanism. Since the recrystallization temperature also decreases with increasing strain rate, the FSW process is somewhat complicated because the ambient temperature, the frictional heating fraction, and the adiabatic heating fraction (proportional to the product of strain and strain-rate) will all influence both the recrystallization and grain growth within the FSW zone. Significantly reducing the ambient temperature of the base metal or work pieces to be welded would be expected to reduce the residual weld-zone grain size. The practical consequences of this temperature reduction would be the achievement of low-temperature welding. This study compares the residual grain sizes and microstructures in 2024 Al friction-stir welded at room temperature ({approximately} 30 C) and low temperature ({minus} 30 C).

  17. Laser beam welding of aluminum alloy 5754-O using a 3 kW Nd:YAG laser and fiber optic beam delivery

    SciTech Connect

    Martukanitz, R.P.; Altshuller, B.

    1996-12-31

    A program was conducted to evaluate laser beam welding of aluminum alloy 5754-O using a 3.0 kW Nd:YAG laser and fiber optic beam delivery. The alloy and laser system were chosen based on consideration for potential applications in the automotive industry. Process parameters were developed for producing autogenous, square-butt welds in 1.6 mm thickness. Metallographic analyses, mechanical property testing, and post weld formability testing were conducted to characterize joints produced under these conditions. Results of these evaluations indicate that the 3.0 kW Nd:YAG laser provides adequate power density and beam quality for welding of this thickness. Enhanced absorption associated with the Nd:YAG laser is believed to be responsible for improved stability of the weld pool and increased weld consistency. Results of tensile tests of the Nd:YAG laser beam welds provided over 90 percent of base metal strength and measurements of post process formability of the welds yielded approximately 70 percent of base metal formability.

  18. Effect of cooling rate on microstructure of friction-stir welded AA1100 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Yi, D.; Mironov, S.; Sato, Y. S.; Kokawa, H.

    2016-06-01

    In this work, the microstructural changes occurring during cooling of friction-stir welded aluminum alloy AA1100 were evaluated. To this end, friction-stir welding (FSW) was performed in a wide range of cooling rates of 20-62 K/s and the evolved microstructures were studied by using electron backscatter diffraction. Below 0.6 Tm (Tm being the melting point), the stir zone material was found to experience no significant changes during cooling. At higher FSW temperatures, however, notable changes occurred in the welded material, including grain growth, sharpening of texture, reduction of the fraction of high-angle boundaries and material softening.

  19. Stability of the grain structure in 2219-O aluminum alloy friction stir welds during solution treatment

    SciTech Connect

    Chen, Y.C. . E-mail: armstrong@hit.edu.cn; Feng, J.C.; Liu, H.J.

    2007-02-15

    The stability of the grain structure in 2219-O aluminum alloy friction stir welds during solution treatment has been investigated. Experimental results show that the solution treatment causes drastic grain growth, Grain growth initiates at the surface and the bottom of the weld and then extends to the weld centre within several minutes. The solution treatment temperature and the welding heat input have a significant effect on grain growth. The higher the solution temperature, or the higher the welding heat input, the greater the grain growth. The instability of the grains is attributed to an imbalance between thermodynamic driving forces for grain growth and the pinning forces impeding grain boundary migration during solution treatment.

  20. Hazard of ultraviolet radiation emitted in gas tungsten arc welding of aluminum alloys.

    PubMed

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

    2016-01-01

    Ultraviolet radiation (UVR) emitted during arc welding frequently causes keratoconjunctivitis and erythema. The extent of the hazard of UVR varies depending on the welding method and conditions. Therefore, it is important to identify the levels of UVR that are present under various conditions. In this study, we experimentally evaluated the hazard of UVR emitted in gas tungsten arc welding (GTAW) of aluminum alloys. The degree of hazard of UVR is measured by the effective irradiance defined in the American Conference of Governmental Industrial Hygienists guidelines. The effective irradiances measured in this study are in the range 0.10-0.91 mW/cm(2) at a distance of 500 mm from the welding arc. The maximum allowable exposure times corresponding to these levels are only 3.3-33 s/day. This demonstrates that unprotected exposure to UVR emitted by GTAW of aluminum alloys is quite hazardous in practice. In addition, we found the following properties of the hazard of UVR. (1) It is more hazardous at higher welding currents than at lower welding currents. (2) It is more hazardous when magnesium is included in the welding materials than when it is not. (3) The hazard depends on the direction of emission from the arc.

  1. Hazard of ultraviolet radiation emitted in gas tungsten arc welding of aluminum alloys

    PubMed Central

    NAKASHIMA, Hitoshi; UTSUNOMIYA, Akihiro; FUJII, Nobuyuki; OKUNO, Tsutomu

    2015-01-01

    Ultraviolet radiation (UVR) emitted during arc welding frequently causes keratoconjunctivitis and erythema. The extent of the hazard of UVR varies depending on the welding method and conditions. Therefore, it is important to identify the levels of UVR that are present under various conditions. In this study, we experimentally evaluated the hazard of UVR emitted in gas tungsten arc welding (GTAW) of aluminum alloys. The degree of hazard of UVR is measured by the effective irradiance defined in the American Conference of Governmental Industrial Hygienists guidelines. The effective irradiances measured in this study are in the range 0.10–0.91 mW/cm2 at a distance of 500 mm from the welding arc. The maximum allowable exposure times corresponding to these levels are only 3.3–33 s/day. This demonstrates that unprotected exposure to UVR emitted by GTAW of aluminum alloys is quite hazardous in practice. In addition, we found the following properties of the hazard of UVR. (1) It is more hazardous at higher welding currents than at lower welding currents. (2) It is more hazardous when magnesium is included in the welding materials than when it is not. (3) The hazard depends on the direction of emission from the arc. PMID:26632121

  2. Friction Stir Welding for Aluminum Metal Matrix Composites (MMC's) (Center Director's Discretionary Fund, Project No. 98-09)

    NASA Technical Reports Server (NTRS)

    Lee, J. A.; Carter, R. W.; Ding, J.

    1999-01-01

    This technical memorandum describes an investigation of using friction stir welding (FSW) process for joining a variety of aluminum metal matrix composites (MMC's) reinforced with discontinuous silicon-carbide (SiC) particulate and functional gradient materials. Preliminary results show that FSW is feasible to weld aluminum MMC to MMC or to aluminum-lithium 2195 if the SiC reinforcement is <25 percent by volume fraction. However, a softening in the heat-affected zone was observed and is known to be one of the major limiting factors for joint strength. The pin tool's material is made from a low-cost steel tool H-13 material, and the pin tool's wear was excessive such that the pin tool length has to be manually adjusted for every 5 ft of weldment. Initially, boron-carbide coating was developed for pin tools, but it did not show a significant improvement in wear resistance. Basically, FSW is applicable mainly for butt joining of flat plates. Therefore, FSW of cylindrical articles such as a flange to a duct with practical diameters ranging from 2-5 in. must be fully demonstrated and compared with other proven MMC joining techniques for cylindrical articles.

  3. Redistribution Mechanisms and Quantification of Homogeneity in Friction Stir Welding and Processing of an Aluminum Silicon Alloy

    DTIC Science & Technology

    2012-09-01

    wide range of particle-containing materials. Materials such as Nickel Aluminum Bronze (NAB), high yield (HY) Steels , and AA5083 are common in many...REDISTRIBUTION MECHANISMS AND QUANTIFICATION OF HOMOGENEITY IN FRICTION STIR WELDING AND PROCESSING OF AN ALUMINUM SILICON ALLOY by Jeffrey C. Woertz...Homogeneity in Friction Stir Welding and Processing of an Aluminum Silicon Alloy 5. FUNDING NUMBERS 6. AUTHOR(S) Jeffrey C. Woertz 7

  4. Structural State of a Weld Formed in Aluminum Alloy by Friction Stir Welding and Treated by Ultrasound

    NASA Astrophysics Data System (ADS)

    Klimenov, V. A.; Abzaev, Yu. A.; Potekaev, A. I.; Vlasov, V. A.; Klopotov, A. A.; Zaitsev, K. V.; Chumaevskii, A. V.; Porobova, S. A.; Grinkevich, L. S.; Tazin, I. D.; Tazin, D. I.

    2016-11-01

    The experimental data on structural state of an aluminum alloy, AlMg6, in the weld zone formed by friction stir welding are analyzed in order to evaluate the effect of its subsequent ultrasonic treatment. It is found that the crystal lattice transits into a low-stability state as a result of combined heat-induced and severe shear deformation. This transition is accompanied by considerable structural-phase changes that are manifested as an increased lattice parameter of the solid solution. This increase is caused by both high values of internal stresses and increased concentration of Mg atoms in the solid solution due to essential dissolution of the β-Al2Mg3 particles with the content of manganese higher than that in the matrix. This is accompanied by high-intensity diffusion and relaxation processes due to the low-stability state of crystal lattice (inhomogeneous stresses) in the weld zone.

  5. Review of Fillet Weld Strength Parameters for Shipbuilding.

    DTIC Science & Technology

    1980-02-01

    AD-ACED 356M ASSACHUJSETTS INST OF TECH CAMRaIDOS DEPT OF OCEAN E-EcTC Pft 13110 REVIEW OF FILLET WELD STREMOYN PARAMETERS FOR SHIPSUILOINS. RU) FES...hours are devoted to welding . A further analysis indicated that 75 percent of the welded joints were fillet welded . Inasmuch as the requirements of...fillet weld sizes have not been revised for many years, the Ship Structure Committee considered a review and analysis of current marine fillet weld

  6. Stress corrosion in high-strength aluminum alloys

    NASA Technical Reports Server (NTRS)

    Dorward, R. C.; Hasse, K. R.

    1980-01-01

    Report describes results of stress-corrosion tests on aluminum alloys 7075, 7475, 7050, and 7049. Tests compare performance of original stress-corrosion-resistant (SCR) aluminum, 7075, with newer, higher-strength SCR alloys. Alloys 7050 and 7049 are found superior in short-transverse cross-corrosion resistance to older 7075 alloy; all alloys are subject to self-loading effect caused by wedging of corrosion products in cracks. Effect causes cracks to continue to grow, even at very-low externally applied loads.

  7. Microstructural Characteristics and Mechanical Properties of 7050-T7451 Aluminum Alloy Friction Stir-Welded Joints

    NASA Astrophysics Data System (ADS)

    Zhou, L.; Wang, T.; Zhou, W. L.; Li, Z. Y.; Huang, Y. X.; Feng, J. C.

    2016-06-01

    The ultra-high-strength Al-Zn-Mg-Cu alloy, 7050-T7451, was friction stir welded at a constant tool rotation speed of 600 rpm. Defect-free welds were successfully obtained at a welding speed of 100 mm/min, but lack-of-penetration defect was formed at a welding speed of 400 mm/min. The as-received material was mainly composed of coarse-deformed grains with some fine recrystallized grains. Fine equiaxed, dynamic, recrystallized grains were developed in the stir zone, and elongated grains were formed in the thermomechanically affected zone with dynamic recovered subgrains. Grain sizes in different regions of friction stir-welded joints varied depending on the welding speed. The sizes and distributions of precipitates changed in different regions of the joint, and wider precipitation free zone was developed in the heat-affected zone compared to that in the base material. Hardness of the heat-affected zone was obviously lower than that of the base material, and the softening region width was related to the welding speed. The tensile strength of the defect-free joints increased with the increasing welding speed, while the lack-of-penetration defect greatly reduced the tensile strength. The tensile fracture path was significantly influenced by the position and orientation of lack-of-penetration defect.

  8. Ultrasonic Spot and Torsion Welding of Aluminum to Titanium Alloys: Process, Properties and Interfacial Microstructure

    NASA Astrophysics Data System (ADS)

    Balle, Frank; Magin, Jens

    Hybrid lightweight structures shape the development of future vehicles in traffic engineering and the aerospace industry. For multi-material concepts made out of aluminum and titanium alloys, the ultrasonic welding technique is an alternative effective joining technology. The overlapped structures can be welded in the solid state, even without gas shielding. In this paper the conventional ultrasonic spot welding with longitudinal oscillation mode is compared to the recent ultrasonic torsion welding with a torsional mode at 20 kHz working frequency. For each technique the process parameters welding force, welding energy and oscillation amplitude were optimized for the hybrid joints using design of experiments. Relationships between the process parameters, mechanical properties and related welding zone should be understood. Central aspects of the research project are microscopic studies of the joining zone in cross section and extensive fracture surface analysis. Detailed electron microscopy and spectroscopy of the hybrid interface help to understand the interfacial formation during ultrasonic welding as well as to transfer the gained knowledge for further multi-metal joints.

  9. Effects of weld metal strength and defects on the ductility of HSLA-100 plates

    SciTech Connect

    Dexter, R.J.; Ferrell, M.

    1995-12-31

    Wide-plate tension tests were performed on high-strength low-alloy steel, minimum yield strength of 690 MPa, with various controlled intentional defects in both undermatched and overmatched welds. Lack-of-fusion areas on the sidewall comprising about 10 percent of the cross-section resulted in full net-section strength. Weld undercut to a depth of 12 percent of the thickness resulted in gross-section yielding and good elongation. Misalignment (offset) of 3 mm slightly reduced the elongation relative to plates within tolerances. There was no consistent difference between the results of the undermatched welds and the overmatched welds.

  10. Bond strength of cementitious borehole plugs in welded tuff

    SciTech Connect

    Akgun, H.; Daemen, J.J.K.

    1991-02-01

    Axial loads on plugs or seals in an underground repository due to gas, water pressures and temperature changes induced subsequent to waste and plug emplacement lead to shear stresses at the plug/rock contact. Therefore, the bond between the plug and rock is a critical element for the design and effectiveness of plugs in boreholes, shafts or tunnels. This study includes a systematic investigation of the bond strength of cementitious borehole plugs in welded tuff. Analytical and numerical analysis of borehole plug-rock stress transfer mechanics is performed. The interface strength and deformation are studied as a function of Young`s modulus ratio of plug and rock, plug length and rock cylinder outside-to-inside radius ratio. The tensile stresses in and near an axially loaded plug are analyzed. The frictional interface strength of an axially loaded borehole plug, the effect of axial stress and lateral external stress, and thermal effects are also analyzed. Implications for plug design are discussed. The main conclusion is a strong recommendation to design friction plugs in shafts, drifts, tunnels or boreholes with a minimum length to diameter ratio of four. Such a geometrical design will reduce tensile stresses in the plug and in the host rock to a level which should minimize the risk of long-term deterioration caused by excessive tensile stresses. Push-out tests have been used to determine the bond strength by applying an axial load to cement plugs emplaced in boreholes in welded tuff cylinders. A total of 130 push-out tests have been performed as a function of borehole size, plug length, temperature, and degree of saturation of the host tuff. The use of four different borehole radii enables evaluation of size effects. 119 refs., 42 figs., 20 tabs.

  11. Sample preparation method for glass welding by ultrashort laser pulses yields higher seam strength

    SciTech Connect

    Cvecek, K.; Miyamoto, I.; Strauss, J.; Wolf, M.; Frick, T.; Schmidt, M.

    2011-05-01

    Glass welding by ultrashort laser pulses allows joining without the need of an absorber or a preheating and postheating process. However, cracks generated during the welding process substantially impair the joining strength of the welding seams. In this paper a sample preparation method is described that prevents the formation of cracks. The measured joining strength of samples prepared by this method is substantially higher than previously reported values.

  12. The Effect of Nitrogen and Titanium on the Toughness of High Strength Saw Weld Deposits

    DTIC Science & Technology

    1989-05-12

    for joining high strength steels . In this endeavor, ten butt-welded HY-100 sample plates were produced using the submerged arc welding process. With...was shown to degrade toughness. In this case, the DBTT increased at a rate of +11C for every 0.01 weight percent increase in titanium. Examination of...to degrade toughness through precipitation and dispersion hardening effects. It is concluded that for the welding of high strength steels , nitrogen

  13. A Microsample Tensile Test Application: Local Strength of Impact Welds Between Sheet Metals

    NASA Astrophysics Data System (ADS)

    Benzing, J. T.; He, M.; Vivek, A.; Taber, G. A.; Mills, M. J.; Daehn, G. S.

    2017-01-01

    Microsample tensile testing was conducted to evaluate the quality of impact welds created by vaporizing foil actuator welding. Tensile test samples with a gauge length of 0.6 mm were electro-discharge machined out of welds created between 1-mm-thick aluminum alloy type 6061 (AA6061) sheets and 6-mm-thick copper (Cu110) plates. Aluminum sheets were used as flyers, while copper plates acted as targets. Flyer sheets in T6 as well as T4 temper conditions were utilized to create welds. Some of the welds made with T4 temper flyers were heat treated to a T6 temper. It was found that the welds made with T4 temper flyers were slightly stronger (max. of 270 MPa) than those produced with T6 temper flyers. Generally, failure propagated in a brittle manner across the weld interface; however, elemental mapping reveals material transfer on either member of the welded system. This work proves the feasibility to apply microsample tensile testing to assess impact welding, even when conducted with flyer sheets of 1 mm or less, and provides insight that is complementary to other test methods.

  14. A Microsample Tensile Test Application: Local Strength of Impact Welds Between Sheet Metals

    NASA Astrophysics Data System (ADS)

    Benzing, J. T.; He, M.; Vivek, A.; Taber, G. A.; Mills, M. J.; Daehn, G. S.

    2017-03-01

    Microsample tensile testing was conducted to evaluate the quality of impact welds created by vaporizing foil actuator welding. Tensile test samples with a gauge length of 0.6 mm were electro-discharge machined out of welds created between 1-mm-thick aluminum alloy type 6061 (AA6061) sheets and 6-mm-thick copper (Cu110) plates. Aluminum sheets were used as flyers, while copper plates acted as targets. Flyer sheets in T6 as well as T4 temper conditions were utilized to create welds. Some of the welds made with T4 temper flyers were heat treated to a T6 temper. It was found that the welds made with T4 temper flyers were slightly stronger (max. of 270 MPa) than those produced with T6 temper flyers. Generally, failure propagated in a brittle manner across the weld interface; however, elemental mapping reveals material transfer on either member of the welded system. This work proves the feasibility to apply microsample tensile testing to assess impact welding, even when conducted with flyer sheets of 1 mm or less, and provides insight that is complementary to other test methods.

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

    NASA Technical Reports Server (NTRS)

    Krantz, B. M.

    1972-01-01

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

  16. 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.

  17. Structure and Hardness of 01570 Aluminum Alloy Friction Stir Welds Processed Under Different Conditions

    NASA Astrophysics Data System (ADS)

    Il'yasov, R. R.; Avtokratova, E. V.; Markushev, M. V.; Predko, P. Yu.; Konkevich, V. Yu.

    2015-10-01

    Structure and hardness of the 01570 aluminum alloy joints processed by friction stir welding at various speeds are investigated. It is shown that increasing the traverse tool speed lowers the probability of macrodefect formation in the nugget zone; however, this can lead to anomalous grain growth in the zone of contact with the tool shoulder. Typical "onion-like" structure of the weld consisting of rings that differ by optical contrast is formed for all examined welding regimes. It is demonstrated that this contrast is caused by the difference in the grain sizes in the rings rather than by their chemical or phase composition. Mechanisms of transformation of the alloy structure during friction stir welding are discussed.

  18. Tensile Strength and Hardness Correlations with Microscopy in Friction welded Aluminium to Copper

    NASA Astrophysics Data System (ADS)

    Satish, Rengarajan; Seshagiri Rao, Vaddi; Ananthapadmanaban, Dattaguru; Ravi, Balappa

    2016-01-01

    Aluminium and copper are good conductors of heat and electricity, copper being the better conductor, is a costly metal indeed. On the other hand, aluminium is cheap, easily available and also has a lower density than copper. Hence, worldwide efforts are being made to partially replace copper wire. Solid state welding should be used to join aluminium to copper. This is because the use of fusion welding results in brittle phases formed in the weld interface. One of the solid state welding techniques used for joining aluminium to copper is friction welding. In this paper, an attempt has been made to join aluminium to copper by friction welding by varying the friction welding parameters, namely friction pressure, upset pressure, burn-off length and speed of rotation of the workpiece. Nine different friction welding parameter combinations were used during welding in accordance with ASTM standards and results have been reported. Tensile strength and hardness tests were carried out for each parameter combination. Optimum friction welding parameter combination was identified with respect to tensile strength. Scanning Electron Microscopy and Electron dispersive spectroanalysis were obtained to identify modes of fracture and presence of intermetallic phases for each friction welding combination with the aim to narrow down friction welding parameters that give good properties on the whole.

  19. High Strength Discontinuously Reinforced Aluminum For Rocket Applications

    NASA Technical Reports Server (NTRS)

    Pandey, A. B.; Shah, S. R.; Shadoan, M.

    2003-01-01

    This study presents results on the development of a new aluminum alloy with very high strength and ductility. Five compositions of Al-Mg-Sc-Gd-Zr alloy were selected for this purpose. These alloys were also reinforced with 15 volume percent silicon-carbide and boron-carbide particles to produce Discontinuously Reinforced Aluminum (DRA) materials. Matrix alloys and DRA were processed using a powder metallurgy process. The helium gas atomization produced very fine powder with cellular-dentritic microstructure. The microstructure of matrix alloys showed fine Al3Sc based precipitate which provides significant strengthening in these alloys. DRA showed uniform distribution of reinforcement in aluminum matrix. DRA materials were tested at -320 F, 75 F in air and 7S F in gaseous hydrogen environments and matrix alloys were tested at 75 F in air. DRA showed high strengths in the range of 89-111 ksi (614-697 MPa) depending on alloy compositions and test environments. Matrix alloys had a good combination of strength, 84-89 ksi (579-621 MPa) and ductility, 4.5-6.5%. The properties of these materials can further be improved by proper control of processing parameters.

  20. A Fundamental Study of Laser Beam Welding Aluminum-Lithium Alloy 2195 for Cryogenic Tank Applications

    NASA Technical Reports Server (NTRS)

    Martukanitz, R. P.; Jan. R.

    1996-01-01

    Based on the potential for decreasing costs of joining stiffeners to skin by laser beam welding, a fundamental research program was conducted to address the impediments identified during an initial study involving laser beam welding of aluminum-lithium alloys. Initial objectives of the program were the identification of governing mechanism responsible for process related porosity while establishing a multivariant relationship between process parameters and fusion zone geometry for laser beam welds of alloy 2195. A three-level fractional factorial experiment was conducted to establish quantitative relationships between primary laser beam processing parameters and critical weld attributes. Although process consistency appeared high for welds produced during partial completion of this study, numerous cracks on the top-surface of the welds were discovered during visual inspection and necessitated additional investigations concerning weld cracking. Two experiments were conducted to assess the effect of filler alloy additions on crack sensitivity: the first experiment was used to ascertain the effects of various filler alloys on cracking and the second experiment involved modification to process parameters for increasing filler metal dilution. Results indicated that filler alloys 4047 and 4145 showed promise for eliminating cracking.

  1. Microstructural Characteristics and Mechanical Properties of Friction Stir Welded Thick 5083 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Imam, Murshid; Sun, Yufeng; Fujii, Hidetoshi; Ma, Ninshu; Tsutsumi, Seiichiro; Murakawa, Hidekazu

    2017-01-01

    Joining thick sections of aluminum alloys by friction stir welding (FSW) in a single pass needs to overcome many challenges before it comes to full-scale industrial use. Important parameters controlling the structure-properties relationships both across weld cross-section and through thickness direction were investigated through mechanical testing, electron backscatter diffraction technique, transmission electron microscopy, and occurrence of serrated plastic flow. The evolution of the properties in the weld cross-section shows that the presence of undissolved and fragmented Al_6MnFe particles cause discrepancies in establishing the Hall-Petch relationship, and derive the strengthening from the Orowan strengthening mechanism. A `stop action' friction stir weld has been prepared to understand the role of geometrical features of the tool probe in the development of the final microstructure after complete weld. Sectioning through the `stop action' weld with the probe in situ displays the individual effect of thread and flat on the grain structure formation. The material at the thread surface experiences more severe deformation than the material at flat surface. Both the high-angle boundaries and mean grain size are found to be higher at the thread surface. The strain hardening capacity, stress serration amplitude, and frequency are observed to be higher in the stir zone than other weld regions.

  2. Thermal-mechanical modeling and experimental validation of weld solidification cracking in 6061-T6 aluminum

    SciTech Connect

    Dike, J.J.; Brooks, J.A.; Bammann, D.J.; Li, M.

    1997-12-31

    Finite element simulation using an internal state variable constitutive model coupled with a void growth and damage model are used to study weld solidification cracking of 6061-T6 aluminum. Calculated results are compared with data from an experimental program determining the locations of failure as a function of weld process parameters and specimen geometry. Two types of weld solidification cracking specimen were studied. One specimen, in which cracking did not occur, was used to evaluate finite element simulations of the thermal response and calculations of average strain across the weld. The other specimen type was used to determine the location of crack initiation as a function of weld process parameters. This information was used to evaluate the finite element simulations of weld solidification cracking. A solidification model which includes dendrite tip and eutectic undercooling was used in both thermal and mechanical finite element analyses. A strain rate and temperature history dependent constitutive model is coupled with a ductile void growth damage model in the mechanical analyses. Stresses near the weld pool are examined to explain results obtained in the finite element analyses and correlated with experimental observations. Good agreement is obtained between simulation and experiment for locations of crack initiation and extent of cracking. Some effects of uncertainties in material parameters are discussed.

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

    NASA Astrophysics Data System (ADS)

    Dahmen, Martin

    2015-03-01

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

  4. Structural strength of welded shells made of corrosion-resistant maraging steels

    SciTech Connect

    Raimond, E.D.; Lapin, P.G.; Pautkin, U.S.; Shiganov, N.V.; Tashchikov, V.S.

    1986-03-01

    The authors devise special measures to increase the resistance of welded shells made of corrosion-resistant maraging steels. High structural strenght is ensured for shells loaded by internal pressure when ait (impact toughness) greater than or equal to10 J/cm/sup 2/. For welds of corrosion-resistant maraging steels of the O3Kh11N10M2T type, this condition is satisfied when the weld strength does not exceed 1400-1450 MPa. A structural strength of 15001750 MPa in welds of corrosion-resistant maraging steels can be obtained by means of mechanicothermal treatment.

  5. Microstructure and Residual Stress Distributions Under the Influence of Welding Speed in Friction Stir Welded 2024 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Moghadam, Danial Ghahremani; Farhangdoost, Khalil; Nejad, Reza Masoudi

    2016-06-01

    Friction stir welding was conducted on 8-mm-thick plates made of AA2024-T351 aluminum alloy at tool traverse speeds between 8 and 31.5 mm/minutes and tool rotational speed between 400 and 800 rpm. Metallographic analyses and mechanical tests including hardness, tensile, residual stress, and fracture toughness tests were carried out to evaluate the microstructural and mechanical properties of the joints as a function of the process parameters. The finite element simulation of the FSW process was also performed using a thermal model. The hardness test results show that the increase in rotational speed or decrease in traverse speed of the tool would cause a decrease in weld zone hardness. The best tensile properties are obtained at rotational/traverse speed ratio between 20 and 32. Also, the longitudinal residual stress profiles were evaluated by employing X-ray diffraction method. The numerical and experimental results showed that the increase in a traverse or rotational speed would increase the residual stress of the weld zone. From the fracture toughness results, it was found that the welding process decreases the joints fracture toughness 18 to 49 pct with respect to the base metal.

  6. Acoustic Emission Weld Monitoring in the 2195 Aluminum-Lithium Alloy

    NASA Technical Reports Server (NTRS)

    Walker, James L.

    2005-01-01

    Due to its low density, the 2195 aluminum-lithium alloy was developed as a replacement for alloy 2219 in the Space Shuttle External Tank (ET). The external tank is the single largest component of the space shuttle system. It is 154 feet long and 27.6 feet in diameter, and serves as the structural backbone for the shuttle during launch, absorbing most of the 7 million plus pounds of thrust produced. The almost 4% decrease in density between the two materials provides an extra 7500 pounds of payload capacity necessary to put the International Space Station components into orbit. The ET is an all-welded structure; hence, the requirement is for up to five rewelds without hot cracking. Unfortunately, hot cracking during re-welding or repair operations was occurring and had to be dealt with before the new super lightweight tank could be used. Weld metal porosity formation was also of concern because it leads to hot cracking during weld repairs. Accordingly, acoustic emission (AE) nondestructive testing was employed to monitor the formation of porosity and hot cracks in order to select the best filler metal and optimize the weld schedule. The purpose of this work is to determine the feasibility of detecting hot cracking in welded aluminum-lithium (Al-Li) structures through the analysis of acoustic emission data. By acoustically characterizing the effects of reheating during a repair operation, the potential for hidden flaws coalescing and becoming "unstable" as the panel is repaired could be reduced. Identification of regions where microcrack growth is likely to occur and the location of active flaw growth in the repair weld will provide the welder with direct feedback as to the current weld quality enabling adjustments to the repair process be made in the field. An acoustic emission analysis of the source mechanisms present during welding has been conducted with the goals of locating regions in the weld line that are susceptible to damage from a repair operation

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

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

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

  8. Improvement of Transverse Strength in Graphite-Aluminum Composites by High-Strength Surface Foils.

    DTIC Science & Technology

    1982-02-01

    purchased from Material Concepts Incorporated. The precursor wire had Union Carbide’s VSB-32 or VS0054 pitch mesophase graphite fibers in a matrix of...probably valid. The reason for the low strength of these plates, particularly G4407, is not known. Pitch fiber graphite-aluminum composites usually have

  9. Effects of filling material and laser power on the formation of intermetallic compounds during laser-assisted friction stir butt welding of steel and aluminum alloys

    NASA Astrophysics Data System (ADS)

    Fei, Xinjiang; Jin, Xiangzhong; Peng, Nanxiang; Ye, Ying; Wu, Sigen; Dai, Houfu

    2016-11-01

    In this paper, two kinds of materials, Ni and Zn, are selected as filling material during laser-assisted friction stir butt welding of Q235 steel and 6061-T6 aluminum alloy, and their influences on the formation of intermetallic compounds on the steel/aluminum interface of the joints were first studied. SEM was used to analyze the profile of the intermetallic compound layer and the fractography of tensile fracture surfaces. In addition, EDS was applied to investigate the types of the intermetallic compounds. The results indicate that a thin iron-abundant intermetallic compound layer forms and ductile fracture mode occurs when Ni is added, but a thick aluminum-abundant intermetallic compound layer generates and brittle fracture mode occurs when Zn is added. So the tensile strength of the welds with Ni as filling material is greater than that with Zn as filling material. Besides, the effect of laser power on the formation of intermetallic compound layer when Ni is added was investigated. The preheated temperature field produced by laser beam in the cross section of workpiece was calculated, and the tensile strength of the joints at different laser powers was tested. Results show that only when suitable laser power is adopted, can suitable preheating temperature of the steel reach, then can thin intermetallic compound layer form and high tensile strength of the joints reach. Either excessive or insufficient laser power will reduce the tensile strength of the joints.

  10. Prediction of the Properties of Heat-Affected Zone of Welded Joints of Sheets from Aluminum Alloys with Structured Surface

    NASA Astrophysics Data System (ADS)

    Mikhailov, V. G.

    2016-05-01

    Welded joints of light structured sheets from aluminum alloy EN AW-6181-T4 (DIN EN 515) of the Al - Si - Mg system are studied. The welding is performed in an argon environment with a short arc by the method of cold metal transfer (CMT®). The results of the study are used in an amended Leblond model for describing the variation of the properties of the heat-affected zone of welded joints of structured sheets.

  11. Laser Beam Welding of Ultra-high Strength Chromium Steel with Martensitic Microstructure

    NASA Astrophysics Data System (ADS)

    Dahmen, Martin; Janzen, Vitalij; Lindner, Stefan; Wagener, Rainer

    A new class of steels is going to be introduced into sheet manufacturing. Stainless ferritic and martensitic steels open up opportunities for sheet metal fabrication including hot stamping. Strengths of up to 2 GPa at fracture elongations of 15% can be attained through this. Welding of these materials, as a result, became a challenge. Energy-reduced welding methods with in-situ heat treatment are required in order to ensure the delicate and complex heat control. Laser beam welding is the joining technique of choice to supply minimum heat input to the fusion process and to apply efficient heat control. For two application cases, tailored blank production in as-rolled condition and welding during assembly in hot stamped condition, welding processes have been developed. The welding suitability is shown through metallurgical investigations of the welds. Crash tests based on the KS-II concept as well as fatigue tests prove the applicability of the joining method.

  12. Effect of friction stir welding on microstructure and corrosion behavior of LF6 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Ghauri, Faizan Ali; Farooq, A.; Ahmad, A.; Deen, K. M.

    2017-03-01

    The LF6 aluminum alloy plates were joined by friction stir welding method. The tool rotational (1180 rpm) and transverse speed (0.56 mm s‑1) were kept constant during welding of 4 mm thick plates. The microstructural features, hardness and tensile properties of the welded samples were determined to evaluate the structural integrity in comparison with the base metal. The electrochemical behavior of base metal (BM), thermo-mechanically affected zone (TMAZ) and weld nugget zone (WNZ) was also investigated by potentiodynamic polarization and electrochemical impedance spectroscopy in 3.5% NaCl solution. The microstructural study revealed significant grain refinement and agglomeration of β (Mg2Al3) intermetallic precipitates in the WNZ. The relatively higher hardness and a decrease in the ductility (3%) also assured the formation of precipitates β precipitates in the WNZ welded samples. The fracture surface of welded sample also revealed the existence of β precipitates within the elongated dimples which may be considered as the crack initiation sites. The relatively lower corrosion rate (23.68 mpy) and higher charge transfer resistance (403 Ω cm2) of BM compared to WNZ could be associated with the galvanic dissolution of Al-matrix through competitive charge transfer and relaxation (adsorption/desorption of intermediate species) processes specifically at the vicinity of the β precipitates.

  13. Partially melted zone in aluminum welds -- Liquation mechanism and directional solidification

    SciTech Connect

    Huang, C.; Kou, S.

    2000-05-01

    Aluminum Alloy 2219 was welded by gas metal arc welding and the microstructure was examined in the partially melted zone (PMZ), which is a narrow region immediately outside the fusion zone. Extensive liquation was observed at three different locations: at large {theta} (Al{sub 2}Cu) particles, along grain boundaries (GBs) and at numerous isolated points within grains. Liquation was initiated at the eutectic temperature T{sub E}, by the eutectic reaction {alpha} + {theta} {r_arrow} L{sub E} and intensified by further melting, above T{sub E}, of the {alpha} matrix surrounding the eutectic liquid (L{sub E}). The microstructure of the liquated-and-solidified GB material is intriguing. First, the material consisted of a new GB of mostly thin, divorced eutectic and a eutectic-free strip of {alpha} immediately next to it. Second, within an individual grain, the strip was along the top and the side facing the weld. Third, with respect to the weld, the strip was always behind the new GB. These three characteristics point to an important phenomenon, that is, solidification of the liquated GB is directional - upward and toward the weld, as a result of the temperature gradients across the PMZ. A thin, brittle eutectic GB and a soft ductile {alpha} strip side by side are expected to be much weaker than a normal GB before welding.

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

    NASA Technical Reports Server (NTRS)

    Moore, Thomas J.; Watson, Gordon K.

    1994-01-01

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

  15. Bearing Strengths of Some Wrought-aluminum Alloys

    NASA Technical Reports Server (NTRS)

    Moore, R L; Wescoat, C

    1943-01-01

    Although a number of investigations of the bearing strength of aluminum alloys have been made, the problem remains one of considerable interest to the aircraft industry. For this reason it has seemed advisable to make additional tests of the commonly used aircraft alloys in an effort to establish a better basis for the selection of allowable bearing values. Current design practice does not recognize the effect of edge distance upon bearing strengths, and for this reason edge distance was one of the principal variables considered in this investigation. The increasing emphasis being placed upon permanent set limitations makes it essential that more information on bearing yield phenomena be obtained. The object of this investigation was to determine bearing yield and ultimate strengths of the following aluminum alloy products: 17S-T, 24S-T, Alclad 24S-T, 24S-RT, 52S-0, 52S-1/2H, 52S-H, 53S-T, and 61S-T extrusions. Ratios of these bearing properties to tensile properties were also determined.

  16. Efficient Welding Fabrication of Extruded Aluminum Mat Panels

    DTIC Science & Technology

    1991-09-01

    Degreasing with methyl ehyl ketone. BR - Edge preparation with fine stainless pneumatic brush. M - Edge miling on milling machine. GR - Edge grinding...degreasing in methyl ethyl ketone and then brushing with a fine stainless wire brush to bright metal. 5-27 * Do not soil cleaned surfaces with...method includes degreasing in methyl ethyl ketone followed by brushing with a fine stainless steel brush. Effect of weld storage period prior to testing on

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  18. Thermal Management in Friction-Stir Welding of Precipitation-Hardening Aluminum Alloys

    SciTech Connect

    Upadhyay, Piyush; Reynolds, Anthony

    2015-05-25

    Process design and implementation in FSW is mostly dependent on empirical information gathered through experience. Basic science of friction stir welding and processing can only be complete when fundamental interrelationships between process control parameters and response variables and resulting weld microstructure and properties are established to a reasonable extent. It is known that primary process control parameters like tool rotation and translation rate and forge axis force have complicated and interactive relationships to the process response variables such as peak temperature, time at temperature etc. Of primary influence to the other process response parameters are temperature and its gradient at the deformation and heat affected zones. Through review of pertinent works in the literature and some experimental results from boundary condition work performed in precipitation hardening aluminum alloys this paper will partially elucidate the nature and effects of temperature transients caused by variation of thermal boundaries in Friction Stir Welding.

  19. Statistical Analysis of Strength Data for an Aerospace Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Neergaard, Lynn; Malone, Tina; Gentz, Steven J. (Technical Monitor)

    2000-01-01

    Aerospace vehicles are produced in limited quantities that do not always allow development of MIL-HDBK-5 A-basis design allowables. One method of examining production and composition variations is to perform 100% lot acceptance testing for aerospace Aluminum (Al) alloys. This paper discusses statistical trends seen in strength data for one Al alloy. A four-step approach reduced the data to residuals, visualized residuals as a function of time, grouped data with quantified scatter, and conducted analysis of variance (ANOVA).

  20. Statistical Analysis of Strength Data for an Aerospace Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Neergaard, L.; Malone, T.

    2001-01-01

    Aerospace vehicles are produced in limited quantities that do not always allow development of MIL-HDBK-5 A-basis design allowables. One method of examining production and composition variations is to perform 100% lot acceptance testing for aerospace Aluminum (Al) alloys. This paper discusses statistical trends seen in strength data for one Al alloy. A four-step approach reduced the data to residuals, visualized residuals as a function of time, grouped data with quantified scatter, and conducted analysis of variance (ANOVA).

  1. Dye penetrant indications caused by superficial surface defects in 2014 aluminum alloy welds.

    NASA Technical Reports Server (NTRS)

    Hocker, R. G.; Wilson, K. R.

    1971-01-01

    Demonstration that dye penetrant indications on the heat-affected zone of 2014-T6 aluminum GMA weldments are frequently caused by superficial surface conditions and are less than 0.007 in. deep. The following methods are suggested for minimization of these surface defects: stabilization of the arc, application of dc ?GTA' welding procedures, reduction of the caustic etch time, and use of fine grain materials.

  2. Numerical Simulation and Experimental Validation of MIG Welding of T-Joints of Thin Aluminum Plates for Top Class Vehicles

    NASA Astrophysics Data System (ADS)

    Bonazzi, Enrico; Colombini, Elena; Panari, Davide; Vergnano, Alberto; Leali, Francesco; Veronesi, Paolo

    2017-01-01

    The integration of experiments with numerical simulations can efficiently support a quick evaluation of the welded joint. In this work, the MIG welding operation on aluminum T-joint thin plate has been studied by the integration of both simulation and experiments. The aim of the paper is to enlarge the global database, to promote the use of thin aluminum sheets in automotive body industries and to provide new data. Since the welding of aluminum thin plates is difficult to control due to high speed of the heat source and high heat flows during heating and cooling, a simulation model could be considered an effective design tool to predict the real phenomena. This integrated approach enables new evaluation possibilities on MIG-welded thin aluminum T-joints, as correspondence between the extension of the microstructural zones and the simulation parameters, material hardness, transient 3D temperature distribution on the surface and inside the material, stresses, strains, and deformations. The results of the mechanical simulations are comparable with the experimental measurements along the welding path, especially considering the variability of the process. The results could well predict the welding-induced distortion, which together with local heating during welding must be anticipated and subsequently minimized and counterbalance.

  3. Analysis of peel strength of consisting of an aluminum sheet, anodic aluminum oxide and a copper foil laminate composite

    NASA Astrophysics Data System (ADS)

    Shin, Hyeong-Won; Lee, Hyo-Soo; Jung, Seung-Boo

    2017-01-01

    Laminate composites consisting of an aluminum sheet, anodic aluminum oxide, and copper foil have been used as heat-spreader materials for high-power light-emitting diodes (LEDs). These composites are comparable to the conventional structure comprising an aluminum sheet, epoxy adhesives, and copper foil. The peel strength between the copper foil and anodic aluminum oxide should be more than 1.0 kgf/cm in order to be applied in high-power LED products. We investigated the effect of the anodic aluminum oxide morphology and heat-treatment conditions on the peel strength of the composites. We formed an anodic aluminum oxide layer on a 99.999% pure aluminum sheet using electrochemical anodization. A Ti/Cu seed layer was formed using the sputtering direct bonding copper process in order to form a copper circuit layer on the anodic aluminum oxide layer by electroplating. The developed heat spreader, composed of an aluminum layer, anodic aluminum oxide, and a copper circuit layer, showed peel strengths ranging from 1.05 to 3.45 kgf/cm, which is very suitable for high-power LED applications.

  4. Effect of strength mismatch on fracture toughness of HSLA steel weld joints

    SciTech Connect

    Rak, I.; Gliha, V.; Gubeljak, N.; Praunseis, Z.; Kocak, M.

    1995-12-31

    The purpose of this experimental work is to present the results of measured toughness and strength on mismatched weld joints made on HSLA steel grade HT 80. In the determined over and undermatched weld joints the local mismatching in the through thickness direction was found by hardness measurement. It seems that local mismatch because of WM low toughness has controlled the fracture behavior of weld metal and HAZ in both cases instead of the global one. Direct local CTOD({delta}{sub 5}) technique is found to be particular useful for the determination of fracture toughness values on mismatched weld joints.

  5. Strength Recovery in a High-Strength Steel During Multiple Weld Thermal Simulations

    NASA Astrophysics Data System (ADS)

    Yu, Xinghua; Caron, Jeremy L.; Babu, S. S.; Lippold, John C.; Isheim, Dieter; Seidman, David N.

    2011-12-01

    BlastAlloy 160 (BA160) is a low-carbon martensitic steel strengthened by copper and M2C precipitates. Heat-affected zone (HAZ) microstructure evaluation of BA160 exhibited softening in samples subjected to the coarse-grained HAZ thermal simulations of this steel. This softening is partially attributed to dissolution of copper precipitates and metal carbides. After subjecting these coarse-grained HAZs to a second weld thermal cycle below the A c1 temperature (at which austenite begins to form on heating), recovery of strength was observed. Atom-probe tomography and microhardness analyses correlated this strength recovery to re-precipitation of copper precipitates and metal carbides. A continuum model is proposed to rationalize strengthening and softening in the HAZ regions of BlastAlloy 160.

  6. Computational Investigation of Hardness Evolution During Friction-Stir Welding of AA5083 and AA2139 Aluminum Alloys

    DTIC Science & Technology

    2011-01-01

    is combined with the basic physical metallurgy of two wrought aluminum alloys to predict/assess their FSW behaviors. The two alloys selected are AA5083... Aluminum Alloys Report Title ABSTRACT A fully coupled thermo-mechanical finite-element analysis of the friction-stir welding ( FSW ) process developed in our...previous work is combined with the basic physical metallurgy of two wrought aluminum alloys to predict/assess their FSW behaviors. The two alloys

  7. 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.

  8. Crack Initiation and Growth Behavior at Corrosion Pit in 7075-T6 High Strength Aluminum Alloy

    DTIC Science & Technology

    2013-06-01

    CRACK INITIATION AND GROWTH BEHAVIOR AT CORROSION PIT IN 7075-T6 HIGH STRENGTH ALUMINUM ALLOY THESIS Eric M. Hunt, Second Lieutenant, USAF AFIT-ENY...7075-T6 HIGH STRENGTH ALUMINUM ALLOY THESIS Presented to the Faculty Department of Aerospace and Astronautical Engineering Graduate School of Engineering...RELEASE; DISTRIBUTION UNLIMITED AFIT-ENY-13-J-01 CRACK INITIATION AND GROWTH BEHAVIOR AT CORROSION PIT IN 7075-T6 HIGH STRENGTH ALUMINUM ALLOY Eric M

  9. Optimization of friction stir welding process to maximize tensile strength of AA6061/ZrB2 in-situ composite butt joints

    NASA Astrophysics Data System (ADS)

    Dinaharan, I.; Murugan, N.

    2012-02-01

    A variety of ceramic particles is added to aluminum alloys to produce aluminum matrix composites (AMCs). Establishing the joining procedure for AMCs is an essential requirement prior to extending their applications. Friction stir welding (FSW) is an emerging solid state welding which eliminates all the defects associated with fusion welding of AMCs. An attempt has been made to friction stir weld AA6061/ ZrB2 in-situ composite. A four factor, five level central composite rotatable design has been used to minimize the number of experiments. The four factors considered are tool rotational speed, welding speed, axial force and weight percentage of ZrB2. A mathematical model has been developed incorporating the FSW process parameters to predict the ultimate tensile strength (UTS) and FS process is optimized using generalized reduced gradient method (GRG) to maximize the UTS. The effect of process parameters on UTS was analyzed. It was observed that the process parameters independently influence the UTS over the entire range studied in this work.

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

    PubMed Central

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

    2015-01-01

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

  11. Friction Stir Spot Welding (FSSW) of Advanced High Strength Steel (AHSS)

    SciTech Connect

    Santella, M. L.; Hovanski, Yuri; Pan, Tsung-Yu

    2012-04-16

    Friction stir spot welding (FSSW) is applied to join advanced high strength steels (AHSS): galvannealed dual phase 780 MPa steel (DP780GA), transformation induced plasticity 780 MPa steel (TRIP780), and hot-stamped boron steel (HSBS). A low-cost Si3N4 ceramic tool was developed and used for making welds in this study instead of polycrystalline cubic boron nitride (PCBN) material used in earlier studies. FSSW has the advantages of solid-state, low-temperature process, and the ability of joining dissimilar grade of steels and thicknesses. Two different tool shoulder geometries, concave with smooth surface and convex with spiral pattern, were used in the study. Welds were made by a 2-step displacement control process with weld time of 4, 6, and 10 seconds. Static tensile lap-shear strength achieved 16.4 kN for DP780GA-HSBS and 13.2kN for TRIP780-HSBS, above the spot weld strength requirements by AWS. Nugget pull-out was the failure mode of the joint. The joining mechanism was illustrated from the cross-section micrographs. Microhardness measurement showed hardening in the upper sheet steel (DP780GA or TRIP780) in the weld, but softening of HSBS in the heat-affect zone (HAZ). The study demonstrated the feasibility of making high-strength AHSS spot welds with low-cost tools.

  12. Technology Of MIG-MAG Welds Strength Enhancement

    NASA Astrophysics Data System (ADS)

    Solodskiy, S. A.; Saraev, Yu N.; Malchik, A. G.; Korotkov, S. E.

    2016-08-01

    A new technology of MIG MAG welding control is developed. Authors introduce use of power AC and pulse feed of welding wire in the arc zone, that downsizes the heat affected zone, stabilizes formation of electrode metal droplets, as external magnetic field's effect on the arc is reduced. Principal criteria for electrode metal transfer control, when powered by AC sources, are specified.

  13. The "Lazy S" Feature in Friction Stir Welding of AA2099 Aluminum -Lithium Alloy

    DTIC Science & Technology

    2007-12-01

    stiffness and strength , and so these materials are attractive for selected aerospace structures . Friction Stir Welding (FSW) of Al-Li alloys may...process, FSW uses a combination of extruding and forging at temperatures well below the melting point of the material to form a high- strength bond ...deformation. The randomness of grain size and structure throughout the stir nugget is the same and supports the presence of a shear texture. The

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  15. Effects of fabrication and joining processes on compressive strength of boron/aluminum and borsic/aluminum structural panels

    NASA Technical Reports Server (NTRS)

    Royster, D. M.; Wiant, H. R.; Mcwithey, R. R.

    1978-01-01

    Processes for forming and joining boron/aluminum and borsic/aluminum to themselves and to titanium alloys were studied. Composite skin and titanium skin panels were joined to composite stringers by high strength bolts, by spotwelding, by diffusion bonding, by adhesive bonding, or by brazing. The effects of the fabrication and joining processes on panel compressive strengths were discussed. Predicted buckling loads were compared with experimental data.

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

    SciTech Connect

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

    2014-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  18. Fracture strength of different soldered and welded orthodontic joining configurations with and without filling material.

    PubMed

    Bock, Jens Johannes; Bailly, Jacqueline; Gernhardt, Christian Ralf; Fuhrmann, Robert Andreas Werner

    2008-01-01

    The aim of this study was to compare the mechanical strength of different joints made by conventional brazing, TIG and laser welding with and without filling material. Five standardized joining configurations of orthodontic wire in spring hard quality were used: round, cross, 3 mm length, 9 mm length and 7 mm to orthodontic band. The joints were made by five different methods: brazing, tungsten inert gas (TIG) and laser welding with and without filling material. For the original orthodontic wire and for each kind of joint configuration or connecting method 10 specimens were carefully produced, totalizing 240. The fracture strengths were measured with a universal testing machine (Zwick 005). Data were analyzed by ANOVA (p=0.05) and Bonferroni post hoc test (p=0.05). In all cases, brazing joints were ruptured on a low level of fracture strength (186-407 N). Significant differences between brazing and TIG or laser welding (p<0.05, Bonferroni post hoc test) were found in each joint configuration. The highest fracture strength means were observed for laser welding with filling material and 3 mm joint length (998 N). Using filling materials, there was a clear tendency to higher mean values of fracture strength in TIG and laser welding. However, statistically significant differences were found only in the 9-mm long joints (p<0.05, Bonferroni post hoc test). In conclusion, the fracture strength of welded joints was positively influenced by the additional use of filling material. TIG welding was comparable to laser welding except for the impossibility of joining orthodontic wire with orthodontic band.

  19. The effect of yield strength on side-bonding upset welds

    SciTech Connect

    Miller, R.G.; Perkins, M.A.

    1991-09-24

    During the course of 9{degree} tapered side-bonding resistance upset weld development at Mound, various studies have been conducted to evaluate the effect of yield strength on welds in 304L stainless steel. The results of these studies have concluded that at high yield strengths there may be a minor reduction in the length of Class 2 or better bond. Satisfactory welds have been produced with materials having yield strengths ranging from 36.0 to 141.0 ksi. However, when body yield strengths exceed 80.0 ksi a minor decrease in bond lengths begins. A significant inverse relationship between stem yield strength and bond length was shown to exist. 8 refs., 9 figs., 10 tabs.

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

    Fusion welding of cast A319 (Al-Si-Cu) alloy will lead to many problems including porosity, micro-fissuring, and hot cracking. Friction Stir Welding (FSW) can be used to weld A319 alloy without these defects. In this investigation, an attempt has been made to study the effect of FSW process parameters on the tensile strength of A319 alloy welded joints. Joints were made using different combinations of tool rotation speed, welding speed, and axial force, each at four levels. The quality of weld zone was analyzed using macrostructure and microstructure analysis. Tensile strength of the joints were evaluated and correlated with the weld zone microstructure. The joint fabricated with a 1200 rpm tool rotation speed, 40 mm/min welding speed, and 4 kN axial force showed superior tensile strength compared with the other joints.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  2. Numerical modelling of thermal phenomenon in friction stir welding of aluminum plates

    NASA Astrophysics Data System (ADS)

    Vaira Vignesh, R.; Padmanaban, R.; Arivarasu, M.; Thirumalini, S.; Gokulachandran, J.; Sai Ram, Mutyala Sesha Satya

    2016-09-01

    Friction stir welding (FSW) is a solid state welding process with potential to join materials that are non weldable by conventional fusion welding techniques. The study of heat transfer in FSW aids in the identification of defects like flash, inadequate heat input, poor material flow and mixing etc. In this paper, transient temperature distribution during FSW of aluminum alloy AA6061-T6 was simulated using finite element modelling. The model was used to predict the peak temperature and analyse the thermal history during FSW. The effect of process parameters namely tool rotation speed, tool traverse speed (welding speed), shoulder diameter and pin diameter of tool on the temperature distribution was investigated using two level factorial design. The model results were validated using the experimental results from the published literature. It was found that peak temperature was directly proportional to tool rotation speed and shoulder diameter and inversely proportional to tool traverse speed. The effect of pin diameter on peak temperature was found to be trivial.

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  4. Friction Stir Welding of SiC/Aluminum Metal Matrix Composites

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    1999-01-01

    Friction Stir Welding (FSW) is a new solid state process for joining metals by plasticizing and consolidating materials around the bond line using thermal energy producing from frictional forces. A feasibility study for FSW of Metal Matrix Composites (MMC) was investigated using aluminum 6092 alloy reinforced with 17% SiC particulates. FSW process consists of a special rotating pin tool that is positioned to plunge into the MMC surface at the bond line. As the tool rotates and move forward along the bond line, the material at the bond line is heated up and forced to flow around the rotating tip to consolidate on the tip's backside to form a solid state joint. FSW has the potential for producing sound welds with MMC because the processing temperature occurs well below the melting point of the metal matrix; thereby eliminating the reinforcement-to-matrix solidification defects, reducing the undesirable chemical reactions and porosity problems.

  5. Thermal Management in Friction-Stir Welding of Precipitation-Hardened Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Upadhyay, Piyush; Reynolds, Anthony P.

    2015-05-01

    Process design and implementation in friction-stir welding (FSW) is mostly dependent on empirical information. Basic science of FSW and processing can only be complete when fundamental interrelationships between the process control parameters and response variables and the resulting weld microstructure and properties are established to a reasonable extent. It is known that primary process control parameters such as tool rotation, translation rates, and forge axis force have complicated and interactive relationships to process-response variables such as peak temperature and time at temperature. Of primary influence on the other process-response parameters are temperature and its gradient in the deformation and heat-affected zones. Through a review of pertinent works in the literature and results from boundary condition experiments performed in precipitation-hardening aluminum alloys, this article partially elucidates the nature and effects of temperature transients caused by variation of thermal boundaries in FSW.

  6. Character of melting and evaporation in laser beam welding of two aluminum alloys

    SciTech Connect

    Xijing, W.; Katayama, S.; Matsunawa, A.

    1997-02-01

    The phenomenon of evaporation within the keyhole during laser beam welding of aluminum Alloys A5052 and A5083 was investigated under different welding conditions. The character of the molten pool was compared and analyzed. It was found that the evaporation of the main alloying element for these alloys, magnesium, greatly influenced the reaction force induced between the metal vapor and thermal plasma, which in turn affected the degree of penetration. The results of these experiments also confirmed that increasing shielding gas flow rate, within a limit, and a light increase in the entrance angle of the laser beam improved meltability and increased penetration depth. Surface preparation was also observed to improve beam absorption and increase penetration.

  7. 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).

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  9. 49 CFR 587.15 - Verification of aluminum honeycomb crush strength.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 7 2010-10-01 2010-10-01 false Verification of aluminum honeycomb crush strength. 587.15 Section 587.15 Transportation Other Regulations Relating to Transportation (Continued) NATIONAL... Deformable Barrier § 587.15 Verification of aluminum honeycomb crush strength. The following procedure...

  10. 49 CFR 587.15 - Verification of aluminum honeycomb crush strength.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 7 2013-10-01 2013-10-01 false Verification of aluminum honeycomb crush strength. 587.15 Section 587.15 Transportation Other Regulations Relating to Transportation (Continued) NATIONAL... Deformable Barrier § 587.15 Verification of aluminum honeycomb crush strength. The following procedure...

  11. 49 CFR 587.15 - Verification of aluminum honeycomb crush strength.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 7 2014-10-01 2014-10-01 false Verification of aluminum honeycomb crush strength. 587.15 Section 587.15 Transportation Other Regulations Relating to Transportation (Continued) NATIONAL... Deformable Barrier § 587.15 Verification of aluminum honeycomb crush strength. The following procedure...

  12. Microstructural characterisation of interfaces in magnetic pulse welded aluminum/aluminum joints

    NASA Astrophysics Data System (ADS)

    Sharafiev, S.; Pabst, C.; F-X Wagner, M.; Groche, P.

    2016-03-01

    Electromagnetic pulse welding provides novel and useful solutions in the field of multi-material structures. The joining occurs through the high-energy mechanical impact of metal sheets, which leads to a strong, cohesive, metallic bonding between the sheets. The high- velocity collision results in changes of the microstructure in the regions adjacent to the interface. The aim of this work is the microstructural characterization of the interface and the welding zone of Al/Al joints. One typical interface is analysed by optical and electron microscopy and using the electron backscatter diffraction technique. Our results show that the interface exhibits a well-known type of wavy weld geometry. Moreover, the formation of an intermediate layer that is different from the bulk aluminium structure is observed. The microstructure of this intermediate layer consists of ultrafine grains and in some regions exhibits a columnar grain structure. It is likely that this special microstructure (which plays an important role in determining the cohesive, continuous bonding between the metal sheets) is formed through a rapid melting and crystallisation process in the interface region.

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

    SciTech Connect

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

    1998-06-01

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

  14. Mechanical Properties of Laser Beam Welded Ultra-high Strength Chromium Steel with Martensitic Microstructure

    NASA Astrophysics Data System (ADS)

    Dahmen, Martin; Janzen, Vitalij; Lindner, Stefan; Wagener, Rainer

    A new class of steels is going to be introduced into sheet manufacturing. Stainless ferritic and martensitic steels open up opportunities for sheet metal fabrication including hot stamping. A strength of up to 2 GPa at a fracture strain of 15% can be attained. Welding of these materials became apparently a challenge. Energy-reduced welding methods with in-situ heat treatment are required in order to ensure the delicate and complex heat control. Laser beam welding is the joining technique of choice to supply minimum heat input to the fusion process and to apply an efficient heat control. For two application cases, production of tailored blanks in as-rolled condition and welding in assembly in hot stamped conditions, welding processes have been developed. The welding suitability is shown in metallurgical investigations of the welds. Crash tests based on the KSII concept as well as fatigue tests prove the applicability of the joining method. For the case of assembly also joining with deep drawing and manganese boron steel was taken into consideration. The strength of the joint is determined by the weaker partner but can benefit from its ductility.

  15. Effective Use of Weld Metal Yield Strength for HY-Steels

    DTIC Science & Technology

    1983-01-01

    and Hasubuchi 1959; Hall et al. 1967). Residual stresses also play important roles in stress corrosion cracking and-hydrogen-induced delayed cracking ... stress corrosion cracking . Weldments with inferior strength have been acceptable only in a few limited cases--repair melds in HY-S0 (made with covered...residual weld stresses could reduce the tendency for hydrogen-induced cracking . Welding processes with very low hydrogen potential are available

  16. Artificial neural networks application for modeling of friction stir welding effects on mechanical properties of 7075-T6 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Maleki, E.

    2015-12-01

    Friction stir welding (FSW) is a relatively new solid-state joining technique that is widely adopted in manufacturing and industry fields to join different metallic alloys that are hard to weld by conventional fusion welding. Friction stir welding is a very complex process comprising several highly coupled physical phenomena. The complex geometry of some kinds of joints makes it difficult to develop an overall governing equations system for theoretical behavior analyse of the friction stir welded joints. Weld quality is predominantly affected by welding effective parameters, and the experiments are often time consuming and costly. On the other hand, employing artificial intelligence (AI) systems such as artificial neural networks (ANNs) as an efficient approach to solve the science and engineering problems is considerable. In present study modeling of FSW effective parameters by ANNs is investigated. To train the networks, experimental test results on thirty AA-7075-T6 specimens are considered, and the networks are developed based on back propagation (BP) algorithm. ANNs testing are carried out using different experimental data that they are not used during networks training. In this paper, rotational speed of tool, welding speed, axial force, shoulder diameter, pin diameter and tool hardness are regarded as inputs of the ANNs. Yield strength, tensile strength, notch-tensile strength and hardness of welding zone are gathered as outputs of neural networks. According to the obtained results, predicted values for the hardness of welding zone, yield strength, tensile strength and notch-tensile strength have the least mean relative error (MRE), respectively. Comparison of the predicted and the experimental results confirms that the networks are adjusted carefully, and the ANN can be used for modeling of FSW effective parameters.

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

    SciTech Connect

    Kostrivas, A.; Lippold, J.C.

    2000-01-01

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

  18. Friction stir welding process and material microstructure evolution modeling in 2000 and 5000 series of aluminum alloy

    NASA Astrophysics Data System (ADS)

    Yalavarthy, Harshavardhan

    Interactions between the rotating and advancing pin-shaped tool (terminated at one end with a circular-cylindrical shoulder) with the clamped welding-plates and the associated material and heat transport during a Friction Stir Welding (FSW) process are studied computationally using a fully-coupled thermo-mechanical finite-element analysis. To surmount potential numerical problems associated with extensive mesh distortions/entanglement, an Arbitrary Lagrangian Eulerian (ALE) formulation was used which enabled adaptive re-meshing (to ensure the continuing presence of a high-quality mesh) while allowing full tracking of the material free surfaces. To demonstrate the utility of the present computational approach, the analysis is applied to the cases of same-alloy FSW of two Aluminum-alloy grades: (a) AA5083 (a solid-solution strengthened and strain-hardened/stabilized Al-Mg-Mn alloy); and (b) AA2139 (a precipitation hardened quaternary Al-Cu-Mg-Ag alloy). Both of these alloys are currently being used in military-vehicle hull structural and armor systems. In the case of non-age-hardenable AA5083, the dominant microstructure evolution processes taking place during FSW are extensive plastic deformation and dynamic recrystallization of highly-deformed material subjected to elevated temperatures approaching the melting temperature. To account for the competition between plastic-deformation controlled strengthening and dynamic-recrystallization induced softening phenomena during the FSW process, the original Johnson-Cook strain- and strain-rate hardening and temperature-softening material strength model is modified in the present work using the available recrystallization-kinetics experimental data. In the case of AA2139, in addition to plastic deformation and dynamic recrystallization, precipitates coarsening, over-aging, dissolution and re-precipitation had to be also considered. Limited data available in the open literature pertaining to the kinetics of the aforementioned

  19. Finite volume modeling of laser assisted friction stir welding of 2017A-T451 aluminum alloy for enhanced sustainability of welded joints

    NASA Astrophysics Data System (ADS)

    Mimouni, Oussama; Badji, Riad; Hadji, Mohamed; Kouadri-Henni, Afia

    2016-10-01

    This study focuses on a new welding modification friction stir welding, using a preheating during the welding phase. This method utilizes laser energy to pre-heat the workpiece to a localized area at the front of the FSW tool, thereby reducing the temperature gradient over a localized area in advance of the tool. The amount of heat generated during welding determines the quality of the weld. Therefore the understanding of the temperature distribution is required to determine the optimal method of welding parameters. In this study, a two-dimensional model of an aluminum alloy plate coupled to a circular laser source is developed, using FLUENT software that is based on the finite volume method, also the geometry of the pin of the FSW tool was modified in several configurations to highlight the effect of the geometry of the tool on the temperature distribution in the welded plate. The model developed can be used to better understand the process, predict process performance and to determine the optimal parameters of the process.

  20. 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.

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

    DTIC Science & Technology

    1992-02-01

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

  2. Addressing the Limit of Detectability of Residual Oxide Discontinuities in Friction Stir Butt Welds of Aluminum using Phased Array Ultrasound

    NASA Technical Reports Server (NTRS)

    Johnston, P. H.

    2008-01-01

    This activity seeks to estimate a theoretical upper bound of detectability for a layer of oxide embedded in a friction stir weld in aluminum. The oxide is theoretically modeled as an ideal planar layer of aluminum oxide, oriented normal to an interrogating ultrasound beam. Experimentally-measured grain scattering level is used to represent the practical noise floor. Echoes from naturally-occurring oxides will necessarily fall below this theoretical limit, and must be above the measurement noise to be potentially detectable.

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

    NASA Astrophysics Data System (ADS)

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

    2002-02-01

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

  4. Computational Analysis of Material Flow During Friction Stir Welding of AA5059 Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Arakere, G.; Pandurangan, B.; Ochterbeck, J. M.; Yen, C.-F.; Cheeseman, B. A.; Reynolds, A. P.; Sutton, M. A.

    2012-09-01

    Workpiece material flow and stirring/mixing during the friction stir welding (FSW) process are investigated computationally. Within the numerical model of the FSW process, the FSW tool is treated as a Lagrangian component while the workpiece material is treated as an Eulerian component. The employed coupled Eulerian/Lagrangian computational analysis of the welding process was of a two-way thermo-mechanical character (i.e., frictional-sliding/plastic-work dissipation is taken to act as a heat source in the thermal-energy balance equation) while temperature is allowed to affect mechanical aspects of the model through temperature-dependent material properties. The workpiece material (AA5059, solid-solution strengthened and strain-hardened aluminum alloy) is represented using a modified version of the classical Johnson-Cook model (within which the strain-hardening term is augmented to take into account for the effect of dynamic recrystallization) while the FSW tool material (AISI H13 tool steel) is modeled as an isotropic linear-elastic material. Within the analysis, the effects of some of the FSW key process parameters are investigated (e.g., weld pitch, tool tilt-angle, and the tool pin-size). The results pertaining to the material flow during FSW are compared with their experimental counterparts. It is found that, for the most part, experimentally observed material-flow characteristics are reproduced within the current FSW-process model.

  5. The tensile strength characteristics study of the laser welds of biological tissue using the nanocomposite solder

    NASA Astrophysics Data System (ADS)

    Rimshan, I. B.; Ryabkin, D. I.; Savelyev, M. S.; Zhurbina, N. N.; Pyanov, I. V.; Eganova, E. M.; Pavlov, A. A.; Podgaetsky, V. M.; Ichkitidze, L. P.; Selishchev, S. V.; Gerasimenko, A. Y.

    2016-04-01

    Laser welding device for biological tissue has been developed. The main device parts are the radiation system and adaptive thermal stabilization system of welding area. Adaptive thermal stabilization system provided the relation between the laser radiation intensity and the weld temperature. Using atomic force microscopy the structure of composite which is formed by the radiation of laser solder based on aqua- albuminous dispersion of multi-walled carbon nanotubes was investigated. AFM topograms nanocomposite solder are mainly defined by the presence of pores in the samples. In generally, the surface structure of composite is influenced by the time, laser radiation power and MWCNT concentration. Average size of backbone nanoelements not exceeded 500 nm. Bulk density of nanoelements was in the range 106-108 sm-3. The data of welding temperature maintained during the laser welding process and the corresponding tensile strength values were obtained. Maximum tensile strength of the suture was reached in the range 50-55°C. This temperature and the pointwise laser welding technology (point area ~ 2.5mm) allows avoiding thermal necrosis of healthy section of biological tissue and provided reliable bonding construction of weld join. In despite of the fact that tensile strength values of the samples are in the range of 15% in comparison with unbroken strips of pigskin leather. This situation corresponds to the initial stage of the dissected tissue connection with a view to further increasing of the joint strength of tissues with the recovery of tissue structure; thereby achieved ratio is enough for a medical practice in certain cases.

  6. 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.

  7. ARc Welding (Industrial Processing Series).

    DTIC Science & Technology

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

  8. Fatigue Strength of Welded Joints and Fatigue Strength of Welded Joints: A Review of the Literature to July 1, 1936

    DTIC Science & Technology

    1936-12-02

    the fatigue limits (see Appendix B, Tables 2 and 4). Kater also found that welded St 52, in the form of unstiffened I beams, gave a higher fatigue...4" flange, 11" web) which withstood 2 x 10u cycles at 29,400 psi. The welded I-bee.s tested by Kater (133) withstood 3 x i06 cycles at a lorer...using compressed air hammers, impact pendulums , and alternat. ing-bend devices. -79- Thustin (211) showed the value of pulsating tension tests on m

  9. Modeling of Residual Stresses and Property Distributions in Friction Stir Welds of Aluminum Alloy 6061-T6

    SciTech Connect

    Feng, Zhili; David, Stan A; Wang, Xun-Li; Sklad, Philip S

    2007-01-01

    An integrated thermal-metallurgical-mechanical model is used to analyze and provide insights into the formation of the residual stress and the changes in microstructure and property of Al6061-T6 friction stir welds. The simulations were conducted by means of a three-dimensional finite element model that accounts for the phenomena of frictional heating, weld microstructure and strength changes due to dissolution and reprecipitation of the hardening precipitate particles, and the mechanical workpiece/tool contact during the friction stir welding (FSW) process. The model predictions were confirmed by experimental measurement data from previous studies. For the friction stir welds investigated, it was found that the residual stress distribution is strongly dependent on the welding process parameters and the degree of material softening caused by welding. The recovery of material strength from natural aging does not increase the residual stress in the weld. The failure of friction stir weld under tensile load is controlled by the combination of the reduction in strength and the residual stresses in the heat affected zone (HAZ).

  10. Mechanical Property Analysis in the Retracted Pin-Tool (RPT) Region of Friction Stir Welded (FSW) Aluminum Lithium 2195

    NASA Technical Reports Server (NTRS)

    Ding, R. Jeffrey; Oelgoetz, Peter A.

    1999-01-01

    The "Auto-Adjustable Pin Tool for Friction Stir Welding", was developed at The Marshall Space Flight Center to address process deficiencies unique to the FSW process. The auto-adjustable pin tool, also called the retractable pin-tool (R.PT) automatically withdraws the welding probe of the pin-tool into the pin-tool's shoulder. The primary function of the auto-adjustable pin-tool is to allow for keyhole closeout, necessary for circumferential welding and localized weld repair, and, automated pin-length adjustment for the welding of tapered material thickness. An overview of the RPT hardware is presented. The paper follows with studies conducted using the RPT. The RPT was used to simulate two capabilities; welding tapered material thickness and closing out the keyhole in a circumferential weld. The retracted pin-tool regions in aluminum- lithium 2195 friction stir weldments were studied through mechanical property testing and metallurgical sectioning. Correlation's can be =de between retractable pin-tool programmed parameters, process parameters, microstructure, and resulting weld quality.

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

    SciTech Connect

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

    2015-05-13

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

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

    DOE PAGES

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

    2015-05-13

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

  13. Prospects of increasing the strength of aluminum by reinforcing it with stainless steel wire (a review)

    NASA Technical Reports Server (NTRS)

    Botvina, L. R.; Ivanova, V. S.; Kopev, I. M.

    1982-01-01

    The theoretical and experimental strength of aluminum reinforced with stainless steel wire is analyzed. Various methods of producing the composite material and it's static and cyclical strengths are considered. The reinforcement of aluminum with stainless steel wire was accomplished from the perspective of increasing the specific strength of aluminum and it's alloys, increasing the strength of the material with respect to high and low temperatures, as well as increasing the cyclical strength. The production of the composite aluminum-stainless steel wire material with approximated or calculated strengthening is possible by any of the considered methods. The selection of the proper production technology depends on precise details and conditions of application of the material.

  14. 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…

  15. Friction Stir Welding in Wrought and Cast Aluminum Alloys: Weld Quality Evaluation and Effects of Processing Parameters on Microstructure and Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Pan, Yi; Lados, Diana A.

    2017-01-01

    Friction stir welding (FSW) is a solid-state process widely used for joining similar and dissimilar materials for critical applications in the transportation sector. Understanding the effects of the process on microstructure and mechanical properties is critical in design for structural integrity. In this study, four aluminum alloy systems (wrought 6061-T651 and cast A356, 319, and A390) were processed in both as-fabricated and pre-weld heat-treated (T6) conditions using various processing parameters. The effects of processing and heat treatment on the resulting microstructures, macro-/micro-hardness, and tensile properties were systematically investigated and mechanistically correlated to changes in grain size, characteristic phases, and strengthening precipitates. Tensile tests were performed at room temperature both along and across the welding zones. A new method able to evaluate weld quality (using a weld quality index) was developed based on the stress concentration calculated under tensile loading. Optimum processing parameter domains that provide both defect-free welds and good mechanical properties were determined for each alloy and associated with the thermal history of the process. These results were further related to characteristic microstructural features, which can be used for component design and materials/process optimization.

  16. Friction Stir Welding in Wrought and Cast Aluminum Alloys: Weld Quality Evaluation and Effects of Processing Parameters on Microstructure and Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Pan, Yi; Lados, Diana A.

    2017-04-01

    Friction stir welding (FSW) is a solid-state process widely used for joining similar and dissimilar materials for critical applications in the transportation sector. Understanding the effects of the process on microstructure and mechanical properties is critical in design for structural integrity. In this study, four aluminum alloy systems (wrought 6061-T651 and cast A356, 319, and A390) were processed in both as-fabricated and pre-weld heat-treated (T6) conditions using various processing parameters. The effects of processing and heat treatment on the resulting microstructures, macro-/micro-hardness, and tensile properties were systematically investigated and mechanistically correlated to changes in grain size, characteristic phases, and strengthening precipitates. Tensile tests were performed at room temperature both along and across the welding zones. A new method able to evaluate weld quality (using a weld quality index) was developed based on the stress concentration calculated under tensile loading. Optimum processing parameter domains that provide both defect-free welds and good mechanical properties were determined for each alloy and associated with the thermal history of the process. These results were further related to characteristic microstructural features, which can be used for component design and materials/process optimization.

  17. Assessing Hydrogen Assisted Cracking Modes in High Strength Steel Welds

    DTIC Science & Technology

    1988-12-01

    posed theoretical hydrogen assisted cracking mechanisms. It was found that the microplasticity theory of Beachem can best describe how the stress ...steel and determined the stress corrosion cracking toughness, Kscc. Herman and Campbell found that the fracture toughness of this material was 16 MPa...embrittlement Welding Cracking (fracturing) Implant tests Stress intensity ("T, ) ’ 20. ABSTRACT (Continue on reverse side if necessary end identify by

  18. Column and Plate Compressive Strength of Extruded XB75S-T Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Heimerl, George J.; Roy, J. Albert

    1944-01-01

    Results are presented of tests to determine the column and plate compressive strength of extruded XB75S-T aluminum alloy, and comparative values are shown for 24S-T aluminum-alloy sheet. Stress-strain curves are also given,

  19. Hot press and roll welding of titanium-6-percent-aluminum-4-percent-vanadium bar and sheet with auto-vacuum cleaning

    NASA Technical Reports Server (NTRS)

    Holko, K. H.

    1972-01-01

    Hot press butt welds were made in 0.5 in. diameter bar, and roll lap welds were made in 0.060 in. thick sheet of Ti-6A1-4V. For hot press welds made after auto-vacuum cleaning at 1800 F for 2 hours, weld strength and ductility equaled the parent metal properties. Only 5 minutes of pressing time were needed at 1800 F and 200 psi to make the hot press welds. Roll welds were made in sheet at 1750 F with only 10 percent deformation. The welds in the bar and sheet were metallurgically indistinguishable from the parent material.

  20. The effect of weld porosity on the cryogenic fatigue strength of ELI grade Ti-5Al-2. 5Sn

    SciTech Connect

    Rogers, P.R.; Lambdin, R.C.; Fox, D.E.

    1992-09-01

    The effect of weld porosity on the fatigue strength of ELI grade Ti-5Al-2.5Sn at cryogenic temperature was determined. A series of high cycle fatigue (HCF) and tensile tests were performed at -320 F on specimens made from welded sheets of the material. All specimens were tested with weld beads intact and some amount of weld offset. Specimens containing porosity and control specimens containing no porosity were tested. Results indicate that for the weld configuration tested, the fatigue life of the material is not affected by the presence of spherical embedded pores.

  1. The effect of weld porosity on the cryogenic fatigue strength of ELI grade Ti-5Al-2.5Sn

    NASA Technical Reports Server (NTRS)

    Rogers, P. R.; Lambdin, R. C.; Fox, D. E.

    1992-01-01

    The effect of weld porosity on the fatigue strength of ELI grade Ti-5Al-2.5Sn at cryogenic temperature was determined. A series of high cycle fatigue (HCF) and tensile tests were performed at -320 F on specimens made from welded sheets of the material. All specimens were tested with weld beads intact and some amount of weld offset. Specimens containing porosity and control specimens containing no porosity were tested. Results indicate that for the weld configuration tested, the fatigue life of the material is not affected by the presence of spherical embedded pores.

  2. Effect of external applied steady magnetic field on the morphology of laser welding joint of 4-mm 2024 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Zhan, Xiaohong; Zhou, Junjie; Sun, Weihua; Chen, Jicheng; Wei, Yanhong

    2017-01-01

    Additional external steady magnetic fields were applied to investigate the influence of a steady magnetic field aligned perpendicular to the welding direction during laser beam welding of 2024 aluminum alloy. The flow pattern in the molten pool and the weld seam geometry were significantly changed by the induced Lorentz force distribution in the liquid metal. It revealed that the application of a steady magnetic field to laser beam welding was helpful to the suppression of the characteristic wineglass-shape and the depth-to-width ratio because of the Marangoni convection. The microstructures and component distributions at various laser power and magnetic field intensity were analyzed too. It was indicated that the suppression of the Marangoni convection by Lorentz force was beneficial to accumulation of component and grain coarsening near the fusion line.

  3. The Effects of Laser Peening and Shot Peening on Mechanical Properties in Friction Stir Welded 7075-T7351 Aluminum

    NASA Technical Reports Server (NTRS)

    Hatamleh, Omar

    2006-01-01

    Peening techniques like laser peening and shot peening were used to modify the surface of friction stir welded 7075-T7351 Aluminum Alloy specimens. The tensile coupons were machined such as the loading was applied in a direction perpendicular to the weld direction. The peening effects on the global and local mechanical properties through the different regions of the weld were characterized and assessed. The surface hardness levels resulting from various peening techniques were also investigated for both sides of the welds. Shot peening resulted in an increase to surface hardness levels, but no improvement was noticed on the mechanical properties. In contrast, mechanical properties were improved by laser peening when compared to the unpeened material.

  4. Grain structure and dislocation density measurements in a friction stir welded aluminum alloy using x-ray peak profile analysis

    SciTech Connect

    Woo, Wan Chuck; Balogh, Levente; Ungar, Prof Tomas; Choo, Hahn; Feng, Zhili

    2008-01-01

    The dislocation density and grain structure of a friction stir welded 6061-T6 aluminum alloy was determined as a function of distance from the weld centerline using high-resolution micro-beam x-ray diffraction. The results of the x-ray peak profile analysis show that the dislocation density is about 1.2 x 10^14 m-2 inside and 4.8 x 10^14 m-2 outside of the weld region. The average subgrain size is about 180 nm in both regions. Compared to the base material, the dislocation density was significantly decreased in the dynamic recrystallized zone of the friction stir welds, which is a good correlation with the TEM observations. The influence of the dislocation density on the strain hardening behavior during tensile deformation is also discussed.

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

    NASA Astrophysics Data System (ADS)

    Mroczka, Krzysztof; Wójcicka, Anna; Pietras, Adam

    2013-09-01

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

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

    NASA Astrophysics Data System (ADS)

    Mazar Atabaki, Mehdi

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

  7. Modeling, simulation and control of pulsed DE-GMA welding process for joining of aluminum to steel

    NASA Astrophysics Data System (ADS)

    Zhang, Gang; Shi, Yu; Li, Jie; Huang, Jiankang; Fan, Ding

    2014-09-01

    Joining of aluminum to steel has attracted significant attention from the welding research community, automotive and rail transportation industries. Many current welding methods have been developed and applied, however, they can not precisely control the heat input to work-piece, they are high costs, low efficiency and consist lots of complex welding devices, and the generated intermetallic compound layer in weld bead interface is thicker. A novel pulsed double electrode gas metal arc welding(Pulsed DE-GMAW) method is developed. To achieve a stable welding process for joining of aluminum to steel, a mathematical model of coupled arc is established, and a new control scheme that uses the average feedback arc voltage of main loop to adjust the wire feed speed to control coupled arc length is proposed and developed. Then, the impulse control simulation of coupled arc length, wire feed speed and wire extension is conducted to demonstrate the mathematical model and predict the stability of welding process by changing the distance of contact tip to work-piece(CTWD). To prove the proposed PSO based PID control scheme's feasibility, the rapid prototyping experimental system is setup and the bead-on-plate control experiments are conducted to join aluminum to steel. The impulse control simulation shows that the established model can accurately represent the variation of coupled arc length, wire feed speed and the average main arc voltage when the welding process is disturbed, and the developed controller has a faster response and adjustment, only runs about 0.1 s. The captured electric signals show the main arc voltage gradually closes to the supposed arc voltage by adjusting the wire feed speed in 0.8 s. The obtained typical current waveform demonstrates that the main current can be reduced by controlling the bypass current under maintaining a relative large total current. The control experiment proves the accuracy of proposed model and feasibility of new control scheme

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  9. Welding and healing of polymer interfaces: Connecting structure, dynamics and strength

    NASA Astrophysics Data System (ADS)

    Robbins, Mark

    2014-03-01

    Applying heat to polymer interfaces is a common means of welding polymer components or healing cracks in polymers. Once chains have diffused by their radius of gyration, the properties of the interface should be indistinguishable from those of the bulk. In practice, welds can achieve bulk strength at much shorter times. The mechanism of strength growth is difficult to determine with experiments, because they cannot directly access the evolution of molecular configurations and entanglements. Large-scale simulations were used to follow the dynamics of interdiffusion at welds and cracks and the associated changes in density and molecular conformations.[2] The evolution of entanglements was tracked using Primitive Path Analysis and shown to be directly related to the mechanical strength under shear and tensile loading. As in experiment, the maximum shear strength σmax of a homopolymer interface rises as a power of welding time t and then saturates at the bulk value. Simulations show that σmax is proportional to the areal density of interfacial entanglements at short times and saturates when chains have formed 2-3 entanglements across the interface. Enthalpy limits interdiffusion across heteropolymer interfaces, and there is a corresponding reduction in interfacial entanglements and mechanical strength. A minimum loop length of order the entanglement length must diffuse across the interface to form entanglements. Cracks are more complicated because of the presence of short segments produced during fracture. Segments that are too strong to confer bulk strength, but longer than the entanglement length, remain near the interface for long time intervals. This leads to a plateau in strength that is below the bulk value. Crazes form under tensile loading. A low interfacial entanglement density can stabilize craze formation and significantly enhance the fracture energy, but the bulk fracture energy is recovered at about the same time as bulk shear strength. Supported by NSF

  10. 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.

  11. Effect of Welding Speed on Mechanical Properties and the Strain-Hardening Behavior of Friction Stir Welded 7075 Aluminum Alloy Joints

    NASA Astrophysics Data System (ADS)

    Xu, Weifeng; Li, Zhaoxi; Sun, Xiaohong

    2017-03-01

    The effect of welding speed on the microstructural evolution, mechanical properties and strain-hardening behavior of friction stir welded (FSWed) high-strength AA7075-T651 was investigated. Large intermetallic particles and grains, whose sizes increased at lower welding speeds, were present in the heat-affected zone. FSWed joints fabricated at the higher welding speed or lower strain rates exhibited higher strength, joint efficiency and ductility than those fabricated at lower welding speeds or higher strain rates. A maximum joint efficiency of 97.5% and an elongation to failure of 15.9% were obtained using a welding speed of 400 mm/min at a strain rate of 10-5 s-1. The hardening capacity, strain-hardening exponent and strain-hardening rate of the FSWed joints were significantly higher than those of the base material, but materials exhibited stage III and stage IV hardening characteristics. The results morphology of the fracture surfaces is consistent with the above results.

  12. Prediction and Verification of Ductile Crack Growth from Simulated Defects in Strength Overmatched Butt Welds

    NASA Technical Reports Server (NTRS)

    Nishioka, Owen S.

    1997-01-01

    Defects that develop in welds during the fabrication process are frequently manifested as embedded flaws from lack of fusion or lack of penetration. Fracture analyses of welded structures must be able to assess the effect of such defects on the structural integrity of weldments; however, the transferability of R-curves measured in laboratory specimens to defective structural welds has not been fully examined. In the current study, the fracture behavior of an overmatched butt weld containing a simulated buried, lack-of-penetration defect is studied. A specimen designed to simulate pressure vessel butt welds is considered; namely, a center crack panel specimen, of 1.25 inch by 1.25 inch cross section, loaded in tension. The stress-relieved double-V weld has a yield strength 50% higher than that of the plate material, and displays upper shelf fracture behavior at room temperature. Specimens are precracked, loaded monotonically while load-CMOD measurements are made, then stopped and heat tinted to mark the extent of ductile crack growth. These measurements are compared to predictions made using finite element analysis of the specimens using the fracture mechanics code Warp3D, which models void growth using the Gurson-Tvergaard dilitant plasticity formulation within fixed sized computational cells ahead of the crack front. Calibrating data for the finite element analyses, namely cell size and initial material porosities are obtained by matching computational predictions to experimental results from tests of welded compact tension specimens. The R-curves measured in compact tension specimens are compared to those obtained from multi-specimen weld tests, and conclusions as to the transferability of R-curves is discussed.

  13. Hardening characteristics of CO2 laser welds in advanced high strength steel

    NASA Astrophysics Data System (ADS)

    Han, Tae-Kyo; Park, Bong-Gyu; Kang, Chung-Yun

    2012-06-01

    When the CO2 laser welder with 6 kW output was used to weld 4 TRIP steels, 2 DP steels and a precipitation-hardened steel, which have the tensile strength in the range of 600-1000 MPa, the effect of welding speed on hardening characteristics was investigated. In the weld of TRIP steels and DP steels, the maximum hardness was shown in the fusion zone and the HAZ near the bond line, and the hardness was decreased from the HAZ to the base metal. Only in the PH600 steel, the maximum hardness was shown in the fusion zone and the hardness was decreased from bond line to the base metal. The maximum hardness value was not changed due to the variation of the welding speed within a given range of the welding speed. When the correlation with maximum hardness value using 6 known carbon equivalents was examined, those of CEL (=C+Si/50+Mn/25+P/2+Cr/25) and PL (=C+Mn/22+14B) were 0.96 and 0.95 respectively, and CEL was better because it could reflect the contribution of Si and Cr added to AHSS. The maximum hardness value could be calculated by the equation "Hmax=701CEL+281". The phase transformation analysis indicated that only martensitic transformation was expected in the given range of the welding conditions. Therefore, the maximum hardness of the weld was the same as that of water cooled steel and not changed with the variation of the welding speed

  14. A review of computer aided interpretation technology for the evaluation of radiographs of aluminum welds

    NASA Technical Reports Server (NTRS)

    Lloyd, J. F., Sr.

    1987-01-01

    Industrial radiography is a well established, reliable means of providing nondestructive structural integrity information. The majority of industrial radiographs are interpreted by trained human eyes using transmitted light and various visual aids. Hundreds of miles of radiographic information are evaluated, documented and archived annually. In many instances, there are serious considerations in terms of interpreter fatigue, subjectivity and limited archival space. Quite often it is difficult to quickly retrieve radiographic information for further analysis or investigation. Methods of improving the quality and efficiency of the radiographic process are being explored, developed and incorporated whenever feasible. High resolution cameras, digital image processing, and mass digital data storage offer interesting possibilities for improving the industrial radiographic process. A review is presented of computer aided radiographic interpretation technology in terms of how it could be used to enhance the radiographic interpretation process in evaluating radiographs of aluminum welds.

  15. Microstructure and Phase Constitution Near the Interface of Explosively Welded Aluminum/Copper Plates

    NASA Astrophysics Data System (ADS)

    Paul, Henryk; Lityńska-Dobrzyńska, Lidia; Prażmowski, Mariusz

    2013-08-01

    The microstructure changes and the phase constitution within the layers close to the bonding interface strongly influence the properties of bimetallic strips. In this work, the layers near the interface of explosively welded aluminum and copper plates were investigated by means of microscopic observations, mostly with the use of transmission electron microscopy (TEM) equipped with energy dispersive spectrometry (EDX). The study was focused on the identification of the intermetallic phases, the possible interdiffusion between the copper and the aluminum, and the changes in the dislocation structure of the parent plates. In macro-/mesoscale, the interfaces were outlined by a characteristic sharp transition indicating that there was no mechanical mixing between the welded metals in the solid state. In micro-/nanoscale, the layers adhering to the interface show typical deformed microstructure features, i.e., structure refinement, elongated dislocation cells, slip bands, and microtwins (in copper plate). The internal microstructure of the intermetallic inclusion is composed mostly of dendrites. The electron diffractions and TEM/EDX chemical composition measurements revealed three crystalline equilibrium phases of the γ-Al4Cu9, η-AlCu, and Θ-Al2Cu type (the last one was dominant). However, most of the observed phases of the general Cu m Al n type (also crystalline) do not appear in the equilibrium Al-Cu phase diagram. Inside the intermetallic inclusions, no significant regularity in the phase distribution with respect to the parent sheets was observed. Therefore, it was concluded that the processes occurring in the melt determined their local chemical composition.

  16. Aluminum-Scandium Alloys: Material Characterization, Friction Stir Welding, and Compatibility With Hydrogen Peroxide (MSFC Center Director's Discretionary Fund Final Report, Proj. No. 04-14)

    NASA Technical Reports Server (NTRS)

    Lee, J. A.; Chen, P. S.

    2004-01-01

    This Technical Memorandum describes the development of several high-strength aluminum (Al) alloys that are compatible with hydrogen peroxide (H2O2) propellant for NASA Hypersonic-X (Hyper-X) vehicles fuel tanks and structures. The yield strengths for some of these Al-magnesium-based alloys are more than 3 times stronger than the conventional 5254-H112 Al alloy, while maintaining excellent H2O2 compatibility similar to class 1 5254 alloy. The alloy development strategy is to add scandium, zirconium, and other transitional metals with unique electrochemical properties, which will not act as catalysts, to decompose the highly concentrated 90 percent H2O2. Test coupons are machined from sheet metals for H2O2 long-term exposure testing and mechanical properties testing. In addition, the ability to weld the new alloys using friction stir welding has also been explored. The new high-strength alloys could represent an enabling material technology for Hyper-X vehicles, where flight weight reduction is a critical requirement.

  17. Mitigating Localized Corrosion Using Thermally Sprayed Aluminum (TSA) Coatings on Welded 25% Cr Superduplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Paul, S.; Lu, Q.; Harvey, M. D. F.

    2015-04-01

    Thermally sprayed aluminum (TSA) coating has been increasingly used for the protection of carbon steel offshore structures, topside equipment, and flowlines/pipelines exposed to both marine atmospheres and seawater immersion conditions. In this paper, the effectiveness of TSA coatings in preventing localized corrosion, such as pitting and crevice corrosion of 25% Cr superduplex stainless steel (SDSS) in subsea applications, has been investigated. Welded 25% Cr SDSS (coated and uncoated) with and without defects, and surfaces coated with epoxy paint were also examined. Pitting and crevice corrosion tests, on welded 25% Cr SDSS specimens with and without TSA/epoxy coatings, were conducted in recirculated, aerated, and synthetic seawater at 90 °C for 90 days. The tests were carried out at both the free corrosion potentials and an applied cathodic potential of -1100 mV saturated calomel electrode. The acidity (pH) of the test solution was monitored daily and adjusted to between pH 7.5 and 8.1, using dilute HCl solution or dilute NaOH, depending on the pH of the solution measured during the test. The test results demonstrated that TSA prevented pitting and crevice corrosion of 25% Cr SDSS in artificial seawater at 90 °C, even when 10-mm-diameter coating defect exposing the underlying steel was present.

  18. Microstructural analysis of cracks generated during welding of 2195 aluminum-lithium alloy

    NASA Technical Reports Server (NTRS)

    Talia, George E.

    1994-01-01

    This research summarizes a series of studies conducted at Marshall Space Flight Center to characterize the properties of 2195 Al-Li alloy. 2195 Al-Li alloy, developed by Martin Marietta laboratories, is designated as a replacement of 2219 Al-Cu alloy for the External Tank (E.T.) of the space shuttle. 2195 Al-Li alloy with its advantage of increased strength per weight over its predecessor, 2219 Al-Cu alloy, also challenges current technology. 2195 Al-Li has a greater tendency to crack than its predecessor. The present study began with the observation of pore formation in 2195 Al-Li alloy in a thermal aging process. In preliminary studies, Talia and Nunes found that most of the two pass welds studied exhibited round and crack-like porosity at the weld roots. Furthermore, the porosity observed was associated with the grain boundaries. The porosity level can be increased by thermal treatment in the air. A solid state reaction proceeding from dendritic boundaries in the weld fusion zone was observed to correlate with the generation of the porosity.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  20. Submerged Arc Welding Consumables for HSLA (High Strength Low Alloy)-100 Steel

    DTIC Science & Technology

    1989-06-01

    0.001 Manganese 0.02 Silicon 0.01 Phosphorus 0.002 Sulfur 0.001 Nickel 0.05 Molybdenum 0.01 Chromium 0.02 Vanadium 0.001 Aluminum 0.002 Titanium 0.002...carbon-manganese steels with small amounts of alloys added such as aluminum, titanium , niobium , or vanadium . Since these steels exhibit high strength...83 Chemical check analysis for boron and phosphorus ................................................. 88 Mechanical property data summary

  1. High Strength Aluminum Alloy For High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

    2005-01-01

    A cast article from an aluminum alloy has improved mechanical properties at elevated temperatures. The cast article has the following composition in weight percent: Silicon 6.0-25.0, Copper 5.0-8.0, Iron 0.05-1.2, Magnesium 0.5-1.5, Nickel 0.05-0.9, Manganese 0.05-1.2, Titanium 0.05-1.2, Zirconium 0.05-1.2, Vanadium 0.05-1.2, Zinc 0.05-0.9, Strontium 0.001-0.1, Phosphorus 0.001-0.1, and the balance is Aluminum, wherein the silicon-to-magnesium ratio is 10-25, and the copper-to-magnesium ratio is 4-15. The aluminum alloy contains a simultaneous dispersion of three types of Al3X compound particles (X=Ti, V, Zr) having a LI2 crystal structure, and their lattice parameters are coherent to the aluminum matrix lattice. A process for producing this cast article is also disclosed, as well as a metal matrix composite, which includes the aluminum alloy serving as a matrix containing up to about 60% by volume of a secondary filler material.

  2. Hybrid laser-arc welding of galvanized high-strength steels in a gap-free lap-joint configuration

    NASA Astrophysics Data System (ADS)

    Yang, Shanglu

    In order to meet the industry demands for increased fuel efficiency and enhanced mechanical and structural performance of vehicles as well as provided excellent corrosion resistance, more and more galvanized advanced high-strength steels (AHSS) have been used to fabricate automobile parts such as panels, bumpers, and front rails. The automotive industry has shown tremendous interest in using laser welding to join galvanized dual phase steels because of lower heat input and higher welding speed. However, the laser welding process tends to become dramatically unstable in the presence of highly pressurized zinc vapor because of the low boiling point of zinc, around 906°C, compared to higher melting point of steel, over 1500°C. A large number of spatters are produced by expelling the liquid metal from the molten pool by the pressurized zinc vapor. Different weld defects such as blowholes and porosities appear in the welds. So far, limited information has been reported on welding of galvanized high strength dual-phase steels in a gap-free lap joint configuration. There is no open literature on the successful attainment of defect-free welds from the laser or hybrid welding of galvanized high-strength steels. To address the significant industry demand, in this study, different welding techniques and monitoring methods are used to study the features of the welding process of galvanized DP steels in a gap-free lap joint configuration. The current research covers: (i) a feasibility study on the welding of galvanized DP 980 steels in a lap joint configuration using gas tungsten arc welding (GTAW), laser welding, hybrid laser/arc welding with the common molten pool, laser welding with the assistance of GTAW preheating source and hybrid laser-variable polarity gas tungsten arc welding (Laser-VPGTAW) techniques (Chapter 2-4); (ii) a welding process monitoring of the welding techniques including the use of machine vision and acoustic emission technique (Chapter 5); (iii

  3. Properties of the joints of sheets of 1565ch alloy in combination with other aluminum alloys that were performed by friction welding with mixing

    NASA Astrophysics Data System (ADS)

    Drits, A. M.; Ovchinnikov, V. V.

    2016-06-01

    The structure and properties of the butt-welded joints of a 1565ch M aluminum alloy with AMg5, AMg6, AV (60661), and 7021 alloys that were performed by friction welding with mixing are studied. The mechanical properties of these joints and their fracture zones are determined as functions of a combination of the alloys to be joined. These alloys are found to have good weldability under friction welding with mixing.

  4. Influence of the Strength Mismatch of a Narrow Gap Welded Joint of SA508 on the Plastic η 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 η factor was evaluated. The η 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 η factor equation considering the strength mismatch and the weld width of a narrow gap welded joint was suggested.

  5. Characterization of a Friction Stir Weld in Aluminum Alloy 7055 Using Microhardness, Electrical Conductivity, and Differential Scanning Calorimetry (DSC)

    NASA Astrophysics Data System (ADS)

    Bush, Ralph; Kiyota, Michelle; Kiyota, Catherine

    2016-07-01

    Optical microscopy, microhardness, electrical conductivity, and differential scanning calorimetry (DSC) were used to characterize the microstructure, hardness, and precipitate structure as a function of position in a friction stir weld, naturally aged for 10 years, in aluminum alloy 7055. Results are shown for the as-welded/naturally aged condition and for a weld that was post-aged using a -T76 regimen. The grain structure and microhardness results reveal the expected central recrystallized region, a thermo-mechanical affected zone (TMAZ), and heat-affected zone (HAZ) with typical changes in microhardness. DSC scans for the as-welded/naturally aged condition indicate a precipitate structure similar to that of a naturally aged condition in the central recrystallized region. Maximum precipitate coarsening and overaging occurs near the TMAZ/HAZ boundary with reduced precipitate dissolution and coarsening as the distance from the weld increases. The post-weld aging resulted in the transformation of GP zones to more stable precipitates plus coarsening of the more stable η' and η precipitates. A combination of DSC testing and CALPHAD calculations allowed calculation of precipitate volume fraction in the HAZ. The precipitate volume fraction decreased monotonically from 0.052 in the baseline material to 0.044 at the TMAZ/HAZ interface.

  6. Microstructural and Mechanical Properties of Friction Stir Welded Nickel-Aluminum Bronze (NAB) Alloy

    NASA Astrophysics Data System (ADS)

    Küçükömeroğlu, T.; Şentürk, E.; Kara, L.; İpekoğlu, G.; Çam, G.

    2016-01-01

    In this study, the applicability of friction stir welding to cast NAB alloy (i.e., C95800) with a thickness of 9 mm has been investigated. The joint performance was determined by conducting optical microscopy, microhardness measurements, and mechanical testing (e.g., tensile and Charpy impact tests). The effect of stir intensity on joint performance was also determined. A grain refinement (equiaxed fine grain structure) as well as evolution of a Widmanstätten structure was achieved within the stir zone of all the joints produced. Thus, all of the joints produced exhibited higher proof stress (i.e., between 512 and 616 MPa) than that of the base material, i.e., 397 MPa. On the other hand, only half of the specimens exhibited higher tensile strength values than that of the base plate (i.e., 794 MPa), whereas the other specimens displayed lower tensile strength than the base plate due to the existence of weld defects, namely cold bonding and/or tunnel defect.

  7. Effect of surface roughening of aluminum plates on the strength of bonds formed between aluminum and polyphenylene sulfide by thermosonic bonding

    NASA Astrophysics Data System (ADS)

    Yasuda, Kiyokazu; Saito, Ryo

    2014-08-01

    Thermosonic bonding of aluminum on polyphenylene sulfide was carried out in order to examine the effect of surface roughening of aluminum on the joint strength. Repeated chemical treatment of aluminum by immersion in aqueous sodium hydroxide and hydrochloric acid solutions increased its surface roughness (Ra ~25 μm) and surface area (~445% increase). Consequently, the bonding strength (~1.8N in average) was enhanced through anchoring effects.

  8. 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.

  9. Method for welding beryllium

    DOEpatents

    Dixon, Raymond D.; Smith, Frank M.; O'Leary, Richard F.

    1997-01-01

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

  10. Effect of friction stir welding parameters on defect formation

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  12. Grain refinement control in gas-shielded arc welding of aluminum tubing

    NASA Technical Reports Server (NTRS)

    Iceland, W. F.; Whiffen, E. L.

    1974-01-01

    When sections are being welded, operator varies pulse rate of power supply and simultaneously monitors signal on oscilloscope until rate is found which produces maximum arc gas voltage. Remainder of welding is performed with power supply set at this pulse rate, producing desired maximum weld puddle agitation and fine uniform weld of grain structure.

  13. Finite Element Simulation of Temperature and Strain Distribution during Friction Stir Welding of AA2024 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Jain, Rahul; Pal, Surjya Kanta; Singh, Shiv Brat

    2017-02-01

    Friction Stir Welding (FSW) is a solid state joining process and is handy for welding aluminum alloys. Finite Element Method (FEM) is an important tool to predict state variables of the process but numerical simulation of FSW is highly complex due to non-linear contact interactions between tool and work piece and interdependency of displacement and temperature. In the present work, a three dimensional coupled thermo-mechanical method based on Lagrangian implicit method is proposed to study the thermal history, strain distribution and thermo-mechanical process in butt welding of Aluminum alloy 2024 using DEFORM-3D software. Workpiece is defined as rigid-visco plastic material and sticking condition between tool and work piece is defined. Adaptive re-meshing is used to tackle high mesh distortion. Effect of tool rotational and welding speed on plastic strain is studied and insight is given on asymmetric nature of FSW process. Temperature distribution on the workpiece and tool is predicted and maximum temperature is found in workpiece top surface.

  14. Finite Element Simulation of Temperature and Strain Distribution during Friction Stir Welding of AA2024 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Jain, Rahul; Pal, Surjya Kanta; Singh, Shiv Brat

    2016-06-01

    Friction Stir Welding (FSW) is a solid state joining process and is handy for welding aluminum alloys. Finite Element Method (FEM) is an important tool to predict state variables of the process but numerical simulation of FSW is highly complex due to non-linear contact interactions between tool and work piece and interdependency of displacement and temperature. In the present work, a three dimensional coupled thermo-mechanical method based on Lagrangian implicit method is proposed to study the thermal history, strain distribution and thermo-mechanical process in butt welding of Aluminum alloy 2024 using DEFORM-3D software. Workpiece is defined as rigid-visco plastic material and sticking condition between tool and work piece is defined. Adaptive re-meshing is used to tackle high mesh distortion. Effect of tool rotational and welding speed on plastic strain is studied and insight is given on asymmetric nature of FSW process. Temperature distribution on the workpiece and tool is predicted and maximum temperature is found in workpiece top surface.

  15. 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…

  16. The Column Strength of Two Extruded Aluminum-Alloy H-Sections

    DTIC Science & Technology

    1938-09-30

    National Bureau of Standards for research in this fieId, and a part of these funds was used to investigate the cohmm strength of an extruded aluminum-alloy...id and discussed in part I of this report. The materkd for this investigation was supplied by the Aluminum Company of herica. Column tests were...requested by the NationaI Advisory Committee for Aeronautics. The results of these tests are presented and disoussed in part II of this report. A

  17. Weldability of Advanced High Strength Steels using Ytterbium:Yttrium Aluminium Garnet high power laser for Tailor-Welded Blank applications

    NASA Astrophysics Data System (ADS)

    Sharma, Rajashekhar Shivaram

    transverse direction were evaluated. Metallographic examinations determined that most of the fusion zone is martensitic with small regions of bainite and ferrite. High microhardness values of the order of 550--600 Hv were noted in most joints, which are attributed to high alloy content of the fusion zone as well as high rates of cooling typical of laser welds. During tensile, fatigue and formability tests, no fractures in the fusion or heat affected zones were observed. Geometric variability evaluations indicated that coatings such as aluminum (in the case of USIBOR) and galvanized zinc (TRIP780) can affect the variability of the weld zone and the surface roughness on the top of the weld. Excessive variability in the form of weld concavity in the weld zones can lead to fractures in the weld region, even though higher hardness can, to some extent, compensate for these surface irregularities. The 2-factor design of experiments further confirmed that coatings adversely affect the surface roughness on the top of the welds. Although thickness differentials alone do not make a significant impact on surface roughness, together with coatings, they can have an adverse effect on roughness. Tensile tests in the direction of rolling as well as in the transverse direction indicate that TRIP780 seems weaker in the direction of rolling when compared to transverse direction while mild steel is stronger in the direction of rolling. Weldability analyses revealed that the typical melting efficiency is on the order of 50--70% for full penetration welding. Formability tests showed that TR/MS joints fractured in a direction parallel to the weld line when tested with the loads perpendicular to the weld line. Tests have also confirmed that weld speed and power have no impact on the outcome of formability results. Overall, this work conclusively proves that high power Yb:YAG lasers can effectively join high strength materials such as DP980, TRIP780, USIBOR, as well as mild steel, for use in tailor-welded

  18. Development of Appropriate Spot Welding Practice for Advanced High Strength Steels (TRP 0114)

    SciTech Connect

    Brian Girvin; Warren Peterson; Jerry Gould

    2004-09-17

    This program evaluated the effects of common manufacturing variables on spike-tempering effectiveness. The investigation used design-of-experiment (DOE) techniques, and examined both dual-phase and martensitic grades of high-strength steels (HSS). The specific grades chosen for this project were: Dual-phase (DP) 600, galvannealed (GA), 1.55 mm (DP) 600; Dual-phase (DP) 980 (uncoated), 1.55 mm (DP) 980; and Martensitic (M) 1300, 1.55 mm (M) 1300. Common manufacturing conditions of interest included tempering practice (quench and temper time), button size, simulated part fitup (sheet angular misalignment and fitup), and electrode wear (increased electrode face diameter). All of these conditions were evaluated against mechanical performance (static and dynamic tensile shear). Weld hardness data was also used to examine correlations between mechanical performance and the degree of tempering. Mechanical performance data was used to develop empirical models. The models were used to examine the robustness of weld strength and toughness to the selected processing conditions. This was done using standard EWI techniques. Graphical representations of robustness were then coupled with metallographic data to relate mechanical properties to the effectiveness of spike tempering. Mechanical properties for all three materials were relatively robust to variation in tempering. Major deviations in mechanical properties were caused by degradation of the weld itself. This was supported by a lack of correlation between hardness data and mechanical results. Small button sizes and large electrode face diameters (worn electrodes) produced large reductions in both static and dynamic strength levels when compared to standard production setups. Dynamic strength was further degraded by edge-located welds.

  19. Effects of Fusion Zone Size on Failure Modes and Performance of Advanced High Strength Steel Spot Welds

    SciTech Connect

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

    2006-04-28

    This paper examines the effects of fusion zone size on failure modes, static strength and energy absorption of resistance spot welds (RSW) of advanced high strength steels (AHSS). DP800 and TRIP800 spot welds are considered. The main failure modes for spot welds are nugget pullout and interfacial fracture. Partial interfacial fracture is also observed. The critical fusion zone sizes to ensure nugget pull-out failure mode are developed for both DP800 and TRIP800 using the limit load based analytical model and the micro-hardness measurements of the weld cross sections. Static weld strength tests using cross tension samples were performed on the joint populations with controlled fusion zone sizes. The resulted peak load and energy absorption levels associated with each failure mode were studied using statistical data analysis tools. The results in this study show that the conventional weld size of 4 t can not produce nugget pullout mode for both the DP800 and TRIP800 materials. The results also suggest that performance based spot weld acceptance criteria should be developed for different AHSS spot welds.

  20. Microstructural Features Controlling Ductile-to-Brittle Transition Behavior in High-Strength, Martensitic Steel Weld Metals

    DTIC Science & Technology

    1990-10-01

    Development Report Microstructural Features Controlling Ductile-to- Brittle Transition Behavior in High-Strength, Martensitic Steel Weld Metals C 0by...Martensitic Steel Weld Metals PERSONAL AUTHOR(S) .J. DeLoach, Jr. .TYPE OF REPORT 13b TIME COVERED 114 DATE OF REPORT (Year, Month, Day) 1S PAGE COUNT I...if necessary and identify by block number) FIELD GROUP SUB-GROUP High strength steel , Ductile-brittle transition Martensitic Mechanical proper ties

  1. Numerical analysis of static performance comparison of friction stir welded versus riveted 2024-T3 aluminum alloy stiffened panels

    NASA Astrophysics Data System (ADS)

    Shao, Qing; He, Yuting; Zhang, Teng; Wu, Liming

    2014-07-01

    Most researches on the static performance of stiffened panel joined by friction stir welding(FSW) mainly focus on the compression stability rather than shear stability. To evaluate the potential of FSW as a replacement for traditional rivet fastening for stiffened panel assembly in aviation application, finite element method(FEM) is applied to compare compression and shear stability performances of FSW stiffened panels with stability performances of riveted stiffened panels. FEMs of 2024-T3 aluminum alloy FSW and riveted stiffened panels are developed and nonlinear static analysis method is applied to obtain buckling pattern, buckling load and load carrying capability of each panel model. The accuracy of each FEM of FSW stiffened panel is evaluated by stability experiment of FSW stiffened panel specimens with identical geometry and boundary condition and the accuracy of each FEM of riveted stiffened panel is evaluated by semi-empirical calculation formulas. It is found that FEMs without considering weld-induced initial imperfections notably overestimate the static strengths of FSW stiffened panels. FEM results show that, buckling patterns of both FSW and riveted compression stiffened panels represent local buckling of plate between stiffeners. The initial buckling waves of FSW stiffened panel emerge uniformly in each plate between stiffeners while those of riveted panel mainly emerge in the mid-plate. Buckling patterns of both FSW and riveted shear stiffened panels represent local buckling of plate close to the loading corner. FEM results indicate that, shear buckling of FSW stiffened panel is less sensitive to the initial imperfections than compression buckling. Load carrying capability of FSW stiffened panel is less sensitive to the initial imperfections than initial buckling. It can be concluded that buckling loads of FSW panels are a bit lower than those of riveted panels whereas carrying capabilities of FSW panels are almost equivalent to those of riveted

  2. Aerospace Patented High-Strength Aluminum Alloy Used in Commercial Industries

    NASA Technical Reports Server (NTRS)

    2004-01-01

    NASA structural materials engineer, Jonathan Lee, displays blocks and pistons as examples of some of the uses for NASA's patented high-strength aluminum alloy originally developed at Marshall Space Flight Center in Huntsville, Alabama. NASA desired an alloy for aerospace applications with higher strength and wear-resistance at elevated temperatures. The alloy is a solution to reduce costs of aluminum engine pistons and lower engine emissions for the automobile industry. The Boats and Outboard Engines Division at Bombardier Recreational Products of Sturtevant, Wisconsin is using the alloy for pistons in its Evinrude E-Tec outboard engine line.

  3. Thermal analysis of friction welding process in relation to the welding of YSZ-alumina composite and 6061 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Uday, M. B.; Fauzi, M. N. Ahmad; Zuhailawati, H.; Ismail, A. B.

    2012-08-01

    The objective of this work is to establish an analytical data for heat generation by friction welding, based on different parameters of the contact condition between two dissimilar materials. The ceramic composite of Al2O3-YSZ and 6061 Al alloy, which is the example of joining materials by friction welding was used in the experiments. Alumina rods containing 0, 25 and 50 wt% yttria stabilized zirconia were produced by slip casting in Plaster of Paris molds and subsequently sintered at 1600 °C. The diameter of both the ceramic and metal rods was 16 mm. Rotational speeds for friction welding were between 630 and 2500 rpm. As a result, different data was evaluated for obtaining joint properties and operating conditions, and obtained results are useful in modeling the welding process and reliability joint under various conditions.

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

    NASA Astrophysics Data System (ADS)

    Zhu, Yuanzhi; Guo, Yingying; Yang, Libin

    2013-04-01

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

  5. Investigation of plasma arc welding as a method for the additive manufacturing of titanium-(6)aluminum-(4)vanadium alloy components

    NASA Astrophysics Data System (ADS)

    Stavinoha, Joe N.

    The process of producing near net-shape components by material deposition is known as additive manufacturing. All additive manufacturing processes are based on the addition of material with the main driving forces being cost reduction and flexibility in both manufacturing and product design. With wire metal deposition, metal is deposited as beads side-by-side and layer-by-layer in a desired pattern to build a complete component or add features on a part. There are minimal waste products, low consumables, and an efficient use of energy and feedstock associated with additive manufacturing processes. Titanium and titanium alloys are useful engineering materials that possess an extraordinary combination of properties. Some of the properties that make titanium advantageous for structural applications are its high strength-to-weight ratio, low density, low coefficient of thermal expansion, and good corrosion resistance. The most commonly used titanium alloy, Ti-6Al-4V, is typically used in aerospace applications, pressure vessels, aircraft gas turbine disks, cases and compressor blades, and surgical implants. Because of the high material prices associated with titanium alloys, the production of near net-shape components by additive manufacturing is an attractive option for the manufacturing of Ti-6Al-4V alloy components. In this thesis, the manufacturing of cylindrical Ti-6Al-4V alloy specimens by wire metal deposition utilizing the plasma arc welding process was demonstrated. Plasma arc welding is a cost effective additive manufacturing technique when compared to other current additive manufacturing methods such as laser beam welding and electron beam welding. Plasma arc welding is considered a high-energy-density welding processes which is desirable for the successful welding of titanium. Metal deposition was performed using a constant current plasma arc welding power supply, flow-purged welding chamber, argon shielding and orifice gas, ERTi-5 filler metal, and Ti-6Al

  6. Factors Affecting the Inclusion Potency for Acicular Ferrite Nucleation in High-Strength Steel Welds

    NASA Astrophysics Data System (ADS)

    Kang, Yongjoon; Jeong, Seonghoon; Kang, Joo-Hee; Lee, Changhee

    2016-06-01

    Factors affecting the inclusion potency for acicular ferrite nucleation in high-strength weld metals were investigated and the contribution of each factor was qualitatively evaluated. Two kinds of weld metals with different hardenabilities were prepared, in both, MnTi2O4-rich spinel formed as the predominant inclusion phase. To evaluate the factors determining the inclusion potency, the inclusion characteristics of size, phase distribution in the multiphase inclusion, orientation relationship with ferrite, and Mn distribution near the inclusion were analyzed. Three factors affecting the ferrite nucleation potency of inclusions were evaluated: the Baker-Nutting (B-N) orientation relationship between ferrite and the inclusion; the formation of an Mn-depleted zone (MDZ) near the inclusion; and the strain energy around the inclusion. Among these, the first two factors were found to be the most important. In addition, it was concluded that the increased chemical driving force brought about by the formation of an MDZ contributed more to the formation of acicular ferrite in higher-strength weld metals, because the B-N orientation relationship between ferrite and the inclusion was less likely to form as the transformation temperature decreased.

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

    NASA Technical Reports Server (NTRS)

    Horton, Karla Renee

    2011-01-01

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

  8. Small-crack effects in high-strength aluminum alloys

    NASA Technical Reports Server (NTRS)

    Newman, J. C., Jr.; Wu, X. R.; Venneri, S. L.; Li, C. G.

    1994-01-01

    The National Aeronautics and Space Administration and the Chinese Aeronautical Establishment participated in a Fatigue and Fracture Mechanics Cooperative Program. The program objectives were to identify and characterize crack initiation and growth of small cracks (10 microns to 2 mm long) in commonly used US and PRC aluminum alloys, to improve fracture mechanics analyses of surface- and corner-crack configurations, and to develop improved life-prediction methods. Fatigue and small-crack tests were performed on single-edgenotch tension (SENT) specimens and large-crack tests were conducted on center-crack tension specimens for constant-amplitude (stress ratios of -1, 0, and 0.5) and Mini-TWIST spectrum loading. The plastic replica method was used to monitor the initiation and growth of small fatigue cracks at the semicircular notch. Crack growth results from each laboratory on 7075-T6 bare and LC9cs clad aluminum alloys agreed well and showed that fatigue life was mostly crack propagation from a material defect (inclusion particles or void) or from the cladding layer. Finite-element and weight-function methods were used to determine stress intensity factors for surface and corner cracks in the SENT specimens. Equations were then developed and used in a crack growth and crack-closure model to correlate small- and large-crack data and to make life predictions for various load histories. The cooperative program produced useful experimental data and efficient analysis methods for improving life predictions. The results should ultimately improve aircraft structural reliability and safety.

  9. Weldability of extruded aluminum-alumina composites

    SciTech Connect

    Gedeon, S.A.; Lane, C.; Altshuller, B.

    1994-12-31

    Acceptable procedure were developed for welding the following types of aluminum particle-reinforced aluminum: 6061/Al{sub 2}O{sub 3}/10p-T6, 6061/Al{sub x}/O{sub 3}20p-T6, and 7005Al{sub 2}O{sub 3}/10p-T6,. Automated and manual procedures were developed and using both gas tungsten arc welding (GTAW), with a cold wire feed, and gas metal arc welding (GMAW). The effect of welding procedures on porosity, reinforcing particulate distribution, and mechanical properties was determined. Postweld heat treatment and microhardness testing were used to understand the effect of the welded microstructure on the strength and ductility of the joint. Fracture surfaces and transverse microsections of mechanical test specimens were examined to determine the origins and mechanisms of failure. Cleanliness of the joint and weld wire were found to be essential to eliminate porosity. Based on these experimentally determined data, general guidelines for welding aluminum oxide particle-reinforced aluminum composites are proposed. Discussion includes proper selection of weld joint geometry, filler metals, travel speed, voltage, and current ranges. These parameters are compared to those used in an actual production environment for composite products. Distinctions between welding these composites and others produced via powder metallurgy or with silicon carbide reinforcements are also discussed.

  10. 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.

  11. Commercialization of NASA's High Strength Cast Aluminum Alloy for High Temperature Applications

    NASA Technical Reports Server (NTRS)

    Lee, Jonathan A.

    2003-01-01

    In this paper, the commercialization of a new high strength cast aluminum alloy, invented by NASA-Marshall Space Flight Center, for high temperature applications will be presented. Originally developed to meet U.S. automotive legislation requiring low- exhaust emission, the novel NASA aluminum alloy offers dramatic improvement in tensile and fatigue strengths at elevated temperatures (450 F-750 F), which can lead to reducing part weight and cost as well as improving performance for automotive engine applications. It is an ideal low cost material for cast components such as pistons, cylinder heads, cylinder liners, connecting rods, turbo chargers, impellers, actuators, brake calipers and rotors. NASA alloy also offers greater wear resistance, dimensional stability, and lower thermal expansion compared to conventional aluminum alloys, and the new alloy can be produced economically from sand, permanent mold and investment casting. Since 2001, this technology was licensed to several companies for automotive and marine internal combustion engines applications.

  12. Fatique Resistant, Energy Efficient Welding Program, Final Technical Report

    SciTech Connect

    Egland, Keith; Ludewig, Howard

    2006-05-25

    The program scope was to affect the heat input and the resultant weld bead geometry by synchronizing robotic weave cycles with desired pulsed waveform shapes to develop process parameters relationships and optimized pulsed gas metal arc welding processes for welding fatique-critical structures of steel, high strength steel, and aluminum. Quality would be addressed by developing intelligent methods of weld measurement that accurately predict weld bead geometry from process information. This program was severely underfunded, and eventually terminated. The scope was redirected to investigate tandem narrow groove welding of steel butt joints during the one year of partial funding. A torch was designed and configured to perform a design of experiments of steel butt weld joints that validated the feasability of the process. An initial cost model estimated a 60% cost savings over conventional groove welding by eliminating the joint preparation and reducing the weld volume needed.

  13. Microstructural Development during Welding of Silicon- and Aluminum-Based Transformation-Induced Plasticity Steels—Inclusion and Elemental Partitioning Analysis

    NASA Astrophysics Data System (ADS)

    Amirthalingam, M.; Hermans, M.; Richardson, I.

    2009-04-01

    Microstructural development in gas tungsten arc (GTA) welded silicon- and aluminum-based transformation-induced plasticity (TRIP) steels was studied by optical and electron microscopy. The fusion zone (FZ) of both welds contained complex inclusions. Energy-dispersive spectroscopic (EDS) analysis on these inclusions showed that the center of the inclusions contained oxides of silicon and aluminum in silicon- and aluminum-based steels, respectively. Epitaxial enrichment of manganese, sulfur, and phosphorous was found on the oxides in the inclusions, resulting in depletion of solutes in solid solution and thereby reducing the stability of austenite in the fusion zone. The fusion line of aluminum-based steel weldments contained higher amounts of allotriomorphic ferrite than silicon-based steel weldments due the partitioning of aluminum at the fusion line during solidification. The retained austenite (RA) contents in the heat-affected zones (HAZs) and FZs of both TRIP steels were found to be about 8 and 4 pct by volume, respectively.

  14. Optimization of calcium carbonate content on synthesis of aluminum foam and its compressive strength characteristic

    NASA Astrophysics Data System (ADS)

    Sutarno, Nugraha, Bagja; Kusharjanto

    2017-01-01

    One of the most important characteristic of aluminum foam is compressive strength, which is reflected by its impact energy and Young's modulus. In the present research, optimization of calcium carbonate (CaCO3) content in the synthesized aluminum foam in order to obtain the highest compressive strength was carried out. The results of this study will be used to determine the CaCO3 content synthesis process parameter in pilot plant scale production of an aluminum foam. The experiment was performed by varying the concentration of calcium carbonate content, which was used as foaming agent, at constant alumina concentration (1.5 wt%), which was added as stabilizer, and temperature (725°C). It was found that 4 wt% CaCO3 gave the lowest relative density, which was 0.15, and the highest porosity, which was 85.29%, and compressive strength of as high as 0.26 Mpa. The pore morphology of the obtained aluminum foam at such condition was as follow: the average pore diameter was 4.42 mm, the wall thickness minimum of the pore was 83.24 µm, roundness of the pore was 0.91. Based on the fractal porosity, the compressive strength was inversely proportional to the porosity and huddled on a power law value of 2.91.

  15. Environmentally assisted crack growth rates of high-strength aluminum alloys

    NASA Astrophysics Data System (ADS)

    Connolly, Brain J.; Deffenbaugh, Kristen L.; Moran, Angela L.; Koul, Michelle G.

    2003-01-01

    The scope of this project is to evaluate the environmentally assisted long crack growth behavior of candidate high-strength aluminum alloys/tempers, specifically AA7150-T7751 and AA7040-T7651, for consideration as viable replacements/refurbishment for stress-corrosion cracking in susceptible AA7075-T6 aircraft components found in aging aircraft systems.

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

    DOEpatents

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

    1996-06-11

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

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

    DOEpatents

    Santella, Michael L.; Sikka, Vinod K.

    1996-01-01

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

  18. Effect of Travel Speed on the Stress Corrosion Behavior of Friction Stir Welded 2024-T4 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Wang, Wen; Li, Tianqi; Wang, Kuaishe; Cai, Jun; Qiao, Ke

    2016-05-01

    The effect of travel speed on stress corrosion cracking (SCC) behavior of friction stir welded 2024-T4 aluminum alloy was investigated by slow strain rate tensile test. Microstructure and microhardness of the welded joint were studied. The results showed that the size of second phase particles increased with increasing travel speed, and the distribution of second phase particles was much more homogeneous at lower travel speed. The minimum microhardness was located at the boundary of nugget zone and thermomechanically affected zone. In addition, the SCC susceptibility of the friction stir welded joint increased with the increase of travel speed, owing to the size and distribution of second phase particles in the welds. The anodic applied potentials of -700, -650, -600 mV, and cathodic applied potential of -1200 mV facilitated SCC while the cathodic applied potential of -1000 mV improved the SCC resistance. The SCC behavior was mainly controlled by the metal anodic dissolution at the open circuit potential, and hydrogen accelerated metal embrittlement.

  19. Femtosecond fiber laser welding of dissimilar metals.

    PubMed

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

    2014-10-01

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

  20. 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.

  1. The influence of the corrosion product layer generated on the high strength low-alloy steels welded by underwater wet welding with stainless steel electrodes in seawater

    NASA Astrophysics Data System (ADS)

    Bai, Qiang; Zou, Yan; Kong, Xiangfeng; Gao, Yang; Dong, Sheng; Zhang, Wei

    2017-02-01

    The high strength low-alloy steels are welded by underwater wet welding with stainless steel electrodes. The micro-structural and electrochemical corrosion study of base metal (BM), weld zone (WZ) and heat affected zone (HAZ) are carried out to understand the influence of the corrosion product layer generated on the high strength low-alloy steels welded by underwater wet welding with stainless steel electrodes, methods used including, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM). The results indicate that the WZ acts as a cathode and there is no corrosion product on it throughout the immersion period in seawater. The HAZ and BM acts as anodes. The corrosion rates of the HAZ and BM change with the immersion time increasing. In the initial immersion period, the HAZ has the highest corrosion rate because it has a coarse tempered martensite structure and the BM exhibites a microstructure with very fine grains of ferrite and pearlite. After a period of immersion, the BM has the highest corrosion rate. The reason is that the corrosion product layer on the HAZ is dense and has a better protective property while that on the BM is loose and can not inhibit the diffusion of oxygen.

  2. YIELD STRENGTH PREDICTION FOR RAPID AGE-HARDENING HEAT TREATMENT OF ALUMINUM ALLOYS

    SciTech Connect

    Yin, Hebi; Sabau, Adrian S; Ludtka, Gerard Michael; Skszek, Timothy; Niu, X

    2013-01-01

    A constitutive model has been developed to predict the yield strength aging curves for aluminum casting alloys during non-isothermal age-hardening processes. The model provides the specific relationship between the process variables and yield strength. Several aging heat treatment scenarios have been investigated using the proposed model, including two-step aging recipes. Two-step aging heat treatments involve a low temperature regime to promote nucleation of secondary phases and a second step at higher temperature for the growth of the secondary phases. The predicted results show that yield strength of approximately 300MPa might be obtained in shorter aging time, of approximately 30 minutes. Thus, better mechanical properties can be obtained by optimizing the time-temperature schedules for the precipitation hardening process of heat treatable aluminum alloys.

  3. Effect of polymer coatings on fatigue strength of aluminum alloy 2024 box beams

    NASA Technical Reports Server (NTRS)

    Nordmark, G. E.; Kelsey, R. A.

    1972-01-01

    Previous investigators have shown that polymer coatings raise the fatigue strength of metals tested in air to about the same level as that of uncoated specimens tested in vacuum. The results are given of tests to determine if a polymer coating would improve the fatigue strength of built-up aluminum alloy members simulating aircraft construction. Aluminum alloy 2024-T4 riveted box beams were subjected to constant amplitude fatigue tests in air as well as in salt water fog. The coating did not improve the fatigue strength of beams tested in either environment. This is believed to result from the fact that most failures originated at rivet holes, which were isolated from both the coating and the environment.

  4. Characterization of Exposures to Airborne Nanoscale Particles During Friction Stir Welding of Aluminum

    PubMed Central

    Pfefferkorn, Frank E.; Bello, Dhimiter; Haddad, Gilbert; Park, Ji-Young; Powell, Maria; Mccarthy, Jon; Bunker, Kristin Lee; Fehrenbacher, Axel; Jeon, Yongho; Virji, M. Abbas; Gruetzmacher, George; Hoover, Mark D.

    2010-01-01

    Friction stir welding (FSW) is considered one of the most significant developments in joining technology over the last half century. Its industrial applications are growing steadily and so are the number of workers using this technology. To date, there are no reports on airborne exposures during FSW. The objective of this study was to investigate possible emissions of nanoscale (<100 nm) and fine (<1 μm) aerosols during FSW of two aluminum alloys in a laboratory setting and characterize their physicochemical composition. Several instruments measured size distributions (5 nm to 20 μm) with 1-s resolution, lung deposited surface areas, and PM2.5 concentrations at the source and at the breathing zone (BZ). A wide range aerosol sampling system positioned at the BZ collected integrated samples in 12 stages (2 nm to 20 μm) that were analyzed for several metals using inductively coupled plasma mass spectrometry. Airborne aerosol was directly collected onto several transmission electron microscope grids and the morphology and chemical composition of collected particles were characterized extensively. FSW generates high concentrations of ultrafine and submicrometer particles. The size distribution was bimodal, with maxima at ∼30 and ∼550 nm. The mean total particle number concentration at the 30 nm peak was relatively stable at ∼4.0 × 105 particles cm−3, whereas the arithmetic mean counts at the 550 nm peak varied between 1500 and 7200 particles cm−3, depending on the test conditions. The BZ concentrations were lower than the source concentrations by 10–100 times at their respective peak maxima and showed higher variability. The daylong average metal-specific concentrations were 2.0 (Zn), 1.4 (Al), and 0.24 (Fe) μg m−3; the estimated average peak concentrations were an order of magnitude higher. Potential for significant exposures to fine and ultrafine aerosols, particularly of Al, Fe, and Zn, during FSW may exist, especially in larger scale industrial

  5. Characterization of exposures to airborne nanoscale particles during friction stir welding of aluminum.

    PubMed

    Pfefferkorn, Frank E; Bello, Dhimiter; Haddad, Gilbert; Park, Ji-Young; Powell, Maria; McCarthy, Jon; Bunker, Kristin Lee; Fehrenbacher, Axel; Jeon, Yongho; Virji, M Abbas; Gruetzmacher, George; Hoover, Mark D

    2010-07-01

    Friction stir welding (FSW) is considered one of the most significant developments in joining technology over the last half century. Its industrial applications are growing steadily and so are the number of workers using this technology. To date, there are no reports on airborne exposures during FSW. The objective of this study was to investigate possible emissions of nanoscale (<100 nm) and fine (<1 microm) aerosols during FSW of two aluminum alloys in a laboratory setting and characterize their physicochemical composition. Several instruments measured size distributions (5 nm to 20 microm) with 1-s resolution, lung deposited surface areas, and PM(2.5) concentrations at the source and at the breathing zone (BZ). A wide range aerosol sampling system positioned at the BZ collected integrated samples in 12 stages (2 nm to 20 microm) that were analyzed for several metals using inductively coupled plasma mass spectrometry. Airborne aerosol was directly collected onto several transmission electron microscope grids and the morphology and chemical composition of collected particles were characterized extensively. FSW generates high concentrations of ultrafine and submicrometer particles. The size distribution was bimodal, with maxima at approximately 30 and approximately 550 nm. The mean total particle number concentration at the 30 nm peak was relatively stable at approximately 4.0 x 10(5) particles cm(-3), whereas the arithmetic mean counts at the 550 nm peak varied between 1500 and 7200 particles cm(-3), depending on the test conditions. The BZ concentrations were lower than the source concentrations by 10-100 times at their respective peak maxima and showed higher variability. The daylong average metal-specific concentrations were 2.0 (Zn), 1.4 (Al), and 0.24 (Fe) microg m(-3); the estimated average peak concentrations were an order of magnitude higher. Potential for significant exposures to fine and ultrafine aerosols, particularly of Al, Fe, and Zn, during FSW may

  6. Method for Assessing Grain Boundary Density in High-Strength, High-Toughness Ferritic Weld Metal

    NASA Astrophysics Data System (ADS)

    Lei, Xuanwei; Huang, Jihua; Chen, Shuhai; Zhao, Xingke

    2017-01-01

    A method for measuring peak values on the maxlength-area fraction curve and the perimeter-area fraction curve with morphological photos using Image Pro Plus 6.0 Soft for assessing grain boundary density in high-strength, high-toughness ferritic weld metals is developed. Results show the sizes of the peak values have a tough relationship with grain boundary densities in that a larger peak value stands for a larger grain boundary density. As ferrite transforms into a certain orientation relationship, this semi-empirical method provides handy references for judging the sizes of effective grain boundary densities.

  7. The Column Strength of Two Extruded Aluminum-Alloy H-Sections

    NASA Technical Reports Server (NTRS)

    Osgood, William R; Holt, Marshall

    1939-01-01

    Extruded aluminum-alloy members of various cross sections are used in aircraft as compression members either singly or as stiffeners for aluminum-alloy sheet. In order to design such members, it is necessary to know their column strength or, in the case of stiffeners, the value of the double modulus, which is best obtained for practical purposes from column tests. Column tests made on two extruded h-sections are described, and column formulas and formulas for the ratio of the double modulus to Young's modulus, based on the tests, are given.

  8. Galvanic corrosion of beryllium welds

    SciTech Connect

    Hill, M.A.; Butt, D.P.; Lillard, R.S.

    1997-12-01

    Beryllium is difficult to weld because it is highly susceptible to cracking. The most commonly used filler metal in beryllium welds is Al-12 wt.% Si. Beryllium has been successfully welded using Al-Si filler metal with more than 30 wt.% Al. This filler creates an aluminum-rich fusion zone with a low melting point that tends to backfill cracks. Drawbacks to adding a filler metal include a reduction in service temperature, a lowering of the tensile strength of the weld, and the possibility for galvanic corrosion to occur at the weld. To evaluate the degree of interaction between Be and Al-Si in an actual weld, sections from a mock beryllium weldment were exposed to 0.1 M Cl{sup {minus}} solution. Results indicate that the galvanic couple between Be and the Al-Si weld material results in the cathodic protection of the weld and of the anodic dissolution of the bulk Be material. While the cathodic protection of Al is generally inefficient, the high anodic dissolution rate of the bulk Be during pitting corrosion combined with the insulating properties of the Be oxide afford some protection of the Al-Si weld material. Although dissolution of the Be precipitate in the weld material does occur, no corrosion of the Al-Si matrix was observed.

  9. Effects of Fusion Zone Size and Failure Mode on Peak Load and Energy Absorption of Advanced High Strength Steel Spot Welds under Lap Shear Loading Conditions

    SciTech Connect

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

    2008-06-01

    This paper examines the effects of fusion zone size on failure modes, static strength and energy absorption of resistance spot welds (RSW) of advanced high strength steels (AHSS) under lap shear loading condition. DP800 and TRIP800 spot welds are considered. The main failure modes for spot welds are nugget pullout and interfacial fracture. Partial interfacial fracture is also observed. Static weld strength tests using lap shear samples were performed on the joint populations with various fusion zone sizes. The resulted peak load and energy absorption levels associated with each failure mode were studied for all the weld populations using statistical data analysis tools. The results in this study show that AHSS spot welds with conventionally required fusion zone size of can not produce nugget pullout mode for both the DP800 and TRIP800 welds under lap shear loading. Moreover, failure mode has strong influence on weld peak load and energy absorption for all the DP800 welds and the TRIP800 small welds: welds failed in pullout mode have statistically higher strength and energy absorption than those failed in interfacial fracture mode. For TRIP800 welds above the critical fusion zone level, the influence of weld failure modes on peak load and energy absorption diminishes. Scatter plots of peak load and energy absorption versus weld fusion zone size were then constructed, and the results indicate that fusion zone size is the most critical factor in weld quality in terms of peak load and energy absorption for both DP800 and TRIP800 spot welds.

  10. Friction Stir Welding in Wrought and Cast Aluminum Alloys: Heat Transfer Modeling and Thermal History Analysis

    NASA Astrophysics Data System (ADS)

    Pan, Yi; Lados, Diana A.

    2017-02-01

    Friction stir welding (FSW) is a technique that can be used for materials joining and local microstructural refinement. Owing to the solid-state character of the process, FSW has significant advantages over traditional fusion welding, including reduced part distortion and overheating. In this study, a novel heat transfer model was developed to predict weld temperature distributions and quantify peak temperatures under various combinations of processing parameters for different wrought and cast Al alloys. Specifically, an analytical analysis was first developed to characterize and predict heat generation rate within the weld nugget, and then a two-dimensional (2D) numerical simulation was performed to evaluate the temperature distribution in the weld cross-section and top-view planes. A further three-dimensional (3D) simulation was developed based on the heat generation analysis. The model was validated by measuring actual temperatures near the weld nugget using thermocouples, and good agreement was obtained for all studied materials and conditions.

  11. Solid state welding processes for an oxide dispersion strengthened nickel-chromium-aluminum alloy

    NASA Technical Reports Server (NTRS)

    Moore, T. J.

    1975-01-01

    Solid-state welding processes were evaluated for joining TD-NiCrAl (Ni-16Cr-4Al-2ThO2) alloy sheet. Both hot-press and resistance spot welding techniques were successfully applied in terms of achieving grain growth across the bond line. Less success was achieved with a resistance seam welding process. In stress-rupture shear and tensile shear tests of lap joints at 1100 C, most failures occurred in the parent material, which indicates that the weld quality was good and that the welds were not a plane of weakness. The overall weld quality was not as good as previously attained with TD-NiCr, probably because the presence of alumina at the faying surfaces and the developmental TD-NiCrAl sheet, which was not of the quality of the TD-NiCr sheet in terms of surface flatness and dimensional control.

  12. A Preliminary Report on the Strength and Metallography of a Bimetallic Friction Stir Weld Joint Between AA6061 and MIL-DTL-46100E High Hardness Steel Armor

    DTIC Science & Technology

    2012-11-26

    plates of 6061-T6 aluminum alloy and High Hardness steel armor (MIL-STD-46100) were successfully joined by the friction stir welding ( FSW ) process using a...b 124 c FSW 194 d High Hardness Steel (HHS) base material 1034 e GMAW f tbd g AA6061/HHS FSW joint 176 8 a Kaiser Aluminum Certified Test...bimetallic friction stir weld joint between AA6061 and MIL-DTL-46100E High Hardness steel armor. ABSTRACT One half inch thick plates of 6061-T6 aluminum

  13. Influence of the temperature and strain rate on the structure and fracture mode of high-strength steels upon the simulation of the thermal cycle of welding and post-welding tempering

    NASA Astrophysics Data System (ADS)

    Pazilova, U. A.; Il'in, A. V.; Kruglova, A. A.; Motovilina, G. D.; Khlusova, E. I.

    2015-06-01

    Structural changes and the main features of the fracture of the base metal and the coarse-grained region of the heat-affected zone of the welded joints of high-strength steels have been studied by simulating the thermal cycle of welding and post-welding heat treatment. The effects of the simultaneous action of heating for high-temperature tempering and of deformation allowing the estimation of the impact of residual welding stresses have been studied. The probable reasons of the formation of cracks in welds upon the postwelding tempering have been determined.

  14. Experimental and numerical investigation of laser shock synchronous welding and forming of Copper/Aluminum

    NASA Astrophysics Data System (ADS)

    Wang, Xiao; Zhang, Hongfeng; Shen, Zongbao; Li, Jianwen; Qian, Qing; Liu, Huixia

    2016-11-01

    A novel laser shock synchronous welding and forming method is introduced, which utilizes laser-induced shock waves to accelerate the flyer plate towards the base plate to achieve the joining of dissimilar metals and forming in a specific shape of mold. The samples were obtained with different laser energies and standoff distances. The surface morphology and roughness of the samples were greatly affected by the laser energy and standoff distances. Fittability was investigated to examine the forming accuracy. The results showed that the samples replicate the mold features well. Straight and wavy interfaces with un-bonded regions in the center were observed through metallographic analysis. Moreover, Energy Disperse Spectroscopy analysis was conducted on the welding interface, and the results indicated that a short-distance elemental diffusion emerged in the welding interface. The nanoindentation hardness of the welding regions was measured to evaluate the welding interface. In addition, the Smoothed Particle Hydrodynamics method was employed to simulate the welding and forming process. It was shown that different standoff distances significantly affected the size of the welding regions and interface waveform characteristics. The numerical analysis results indicated that the opposite shear stress direction and effective plastic strain above a certain threshold are essential to successfully obtain welding and forming workpiece.

  15. Studies of localized corrosion in welded aluminum alloys by the scanning reference electrode technique

    NASA Technical Reports Server (NTRS)

    Danford, M. D.; Nunes, A. C.

    1995-01-01

    Localized corrosion in welded samples of 2219-T87 Al alloy (2319 filler), 2090 Al-Li alloy (4043 and 2319 fillers), and 2195 Al-Li alloy (4043 and 2319 fillers) has been investigated using the relatively new scanning reference electrode technique. The weld beads are cathodic in all cases, leading to reduced anode/cathode ratios. A reduction in anode/cathode ratio leads to an increase in the corrosion rates of the welded metals, in agreement with results obtained in previous electrochemical and stress corrosion studies involving the overall corrosion rates of welded samples. The cathodic weld beads are bordered on both sides by strong anodic regions, with high propensity for corrosion.

  16. Localized corrosion and stress corrosion cracking resistance of friction stir welded aluminum alloy 5454

    SciTech Connect

    Frankel, G.S.; Xia, Z.

    1999-02-01

    The susceptibility of welded and unwelded samples of Al 5454 (UNS A95454) in the -O and -H34 tempers to pitting corrosion and stress corrosion cracking (SCC) in chloride solutions was studied. Welded samples were fabricated using the relatively new friction stir welding (FSW) process as well as a standard gas-tungsten arc welding process for comparison. Pitting corrosion was assessed through potentiodynamic polarization experiments. U-bend and slow strain rate tests were used to determine SCC resistance. The FSW samples exhibited superior resistance to pitting corrosion compared to the base metal and arc-welded samples. U-bend tests indicated adequate SCC resistance for the FSW samples. However, the FSW samples exhibited discontinuities that probably were associated with remnant boundaries of the original plates. These defects resulted in intermittent increased susceptibility to pitting and, particularly for Al 5454-H34 samples, poor mechanical properties in general.

  17. Aerospace Patented High-Strength Aluminum Alloy Used in Commercial Industries

    NASA Technical Reports Server (NTRS)

    2004-01-01

    NASA structural materials engineers at Marshall Space Flight Center (MSFC) in Huntsville, Alabama developed a high-strength aluminum alloy for aerospace applications with higher strength and wear-resistance at elevated temperatures. The alloy is a solution to reduce costs of aluminum engine pistons and lower engine emissions for the automobile industry. The Boats and Outboard Engines Division at Bombardier Recreational Products of Sturtevant, Wisconsin is using the alloy for pistons in its Evinrude E-Tec outboard, 40-90 horsepower, engine line. The alloy pistons make the outboard motor quieter and cleaner, while improving fuel mileage and increasing engine durability. The engines comply with California Air resources Board emissions standards, some of the most stringent in the United States. (photo credit: Bombardiier Recreational Products)

  18. X-ray and neutron diffraction measurements of dislocation density and subgrain size in a friction stir welded aluminum alloy

    SciTech Connect

    Claussen, Bjorn; Woo, Wanchuck; Zhili, Feng; Edward, Kenik; Ungar, Tamas

    2009-01-01

    The dislocation density and subgrain size were determined in the base material and friction-stir welds of 6061-T6 aluminum alloy. High-resolution X-ray diffraction measurement was performed in the base material. The result of the line profile analysis of the X-ray diffraction peak shows that the dislocation density is about 4.5 x 10{sup 14} m{sup 02} and the subgrain size is about 200 nm. Meanwhile, neutron diffraction measurements have been performed to observe the diffraction peaks during friction-stir welding (FSW). The deep penetration capability of the neutron enables us to measure the peaks from the midplane of the Al plate underneath the tool shoulder of the friction-stir welds. The peak broadening analysis result using the Williamson-Hall method shows the dislocation density of about 3.2 x 10{sup 15} m{sup -2} and subgrain size of about 160 nm. The significant increase of the dislocation density is likely due to the severe plastic deformation during FSW. This study provides an insight into understanding the transient behavior of the microstructure under severe thermomechanical deformation.

  19. Stress Corrosion Cracking of Wrought and P/M High Strength Aluminum Alloys.

    DTIC Science & Technology

    1983-03-01

    M 1 Jan. 1982 - 31 Dec. 1982 High Strength Aluminum Alloys 6. PERFORMING ORG. REPORT NUMBER ,". A4THOR( s ) 0. CONTRACT OR GRANT NUMBER(&) F, W...program are presented, C-3 with emphasis on the stress corrosion cracking and hydrogen embrittlement of S the P/M X-7090 AValloy. More complete results...specimens. The value obtained, about 󈧋 cm / s -is one of the first successful measurements of this type. We remain confident that we have established

  20. The Formability of Friction Stir Welds in Automotive Stamping Environments

    SciTech Connect

    Grant, Glenn J.; Davies, Richard W.; Stephens, Elizabeth V.; Wazny, Scott; Kaunitz, Leon; Waldron, Douglas J.

    2006-02-01

    Automobile body and truck cab structures are composed primarily of stampings formed from monolithic and constant gage blanks. Cost and weight penalties can arise when strength or other requirements in one small area of the part leads to the use of a material or gage that is overmatched to the needs of the rest of the stamping. Tailor Welded Blanks (TWBs) are hybrid sheet products composed of either different materials or different thickness sheets that are joined together, then subjected to a stamping operation to create a formed assembly. The strategy is employed generally to save weight and material costs in the formed assembly by placing higher strength or thicker sections only where needed. The forming or stamping process requires the joint to be severely deformed along with the parent sheets. Aluminum TWBs for automotive applications are particularly problematic because of the low formability of aluminum weld metal. Friction Stir Welding (FSW) is a process recently applied to Aluminum TWBs that has the potential to produce a higher quality weld. The current study presents data on the mechanical properties, formability, and FSW weld process parameter development for friction stir welded aluminum, Tailor Welded Blanks. Friction stir welded TWBs can be shown to have higher formability, higher ductility, and lower defect content than many competing joining processes, and they can be fabricated at speeds appropriate for automotive manufacturing.

  1. Temperature distribution study during the friction stir welding process of Al2024-T3 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Yau, Y. H.; Hussain, A.; Lalwani, R. K.; Chan, H. K.; Hakimi, N.

    2013-08-01

    Heat flux characteristics are critical to good quality welding obtained in the important engineering alloy Al2024-T3 by the friction stir welding (FSW) process. In the present study, thermocouples in three different configurations were affixed on the welding samples to measure the temperatures: in the first configuration, four thermocouples were placed at equivalent positions along one side of the welding direction; the second configuration involved two equivalent thermocouple locations on either side of the welding path; while the third configuration had all the thermocouples on one side of the layout but with unequal gaps from the welding line. A three-dimensional, non-linear ANSYS computational model, based on an approach applied to Al2024-T3 for the first time, was used to simulate the welding temperature profiles obtained experimentally. The experimental thermal profiles on the whole were found to be in agreement with those calculated by the ANSYS model. The broad agreement between the two kinds of profiles validates the basis for derivation of the simulation model and provides an approach for the FSW simulation in Al2024-T3 and is potentially more useful than models derived previously.

  2. Picosecond laser welding of similar and dissimilar materials.

    PubMed

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

    2014-07-01

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

  3. Quantitative investigation of the tensile plastic deformation characteristic and microstructure for friction stir welded 2024 aluminum alloy

    SciTech Connect

    Hu, Z.L.; Wang, X.S.; Yuan, S.J.

    2012-11-15

    The effect of the microstructure heterogeneity on the tensile plastic deformation characteristic of friction stir welded (FSW) 2024 aluminum alloy was investigated for the potential applications on light weight design of vehicles. The microstructure characteristics of the FSW joints, such as the grain structure, dislocation density and the distribution of precipitation, were studied by electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). The tensile deformation characteristic of the FSW joints was examined using the automatic strain measuring system (ASAME) by mapping the global and local strain distribution, and then was analyzed by mechanics calculation. It is found that the tensile deformation of the FSW joints is highly heterogeneous leading to a significant decrease in global ductility. The FSW joints mainly contain two typical deformation zones, which show great effect on the regional inhomogeneous deformation. One is the nugget zone (NZ) with a region of 8 mm in width, and the other is part of the BM with a region of 10 mm in width. The BM of the joints is the weakest region where the strain localizes early and this localization extends until fracture with a strain over 30%, while the strain in the NZ is only 4%. Differences in regional strain of FSW joints, which are essentially controlled by grain structure, the distribution of precipitation and dislocation density, result in decrease on the overall mechanical properties. - Highlights: Black-Right-Pointing-Pointer Microstructure heterogeneity of welds on tensile deformation behavior is studied. Black-Right-Pointing-Pointer The welds contain two typical deformation zones, affecting the global ductility. Black-Right-Pointing-Pointer Regional strain of welds is controlled by grain structure and dislocation density. Black-Right-Pointing-Pointer Theoretical calculation is in good agreement with experimental result.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  5. Control of surface defects on plasma-MIG hybrid welds in cryogenic aluminum alloys

    NASA Astrophysics Data System (ADS)

    Lee, Hee-Keun; Chun, Kwang-San; Park, Sang-Hyeon; Kang, Chung-Yun

    2015-07-01

    Lately, high production rate welding processes for Al alloys, which are used as LNG FPSO cargo containment system material, have been developed to overcome the limit of installation and high rework rates. In particular, plasma-metal inert gas (MIG) hybrid (PMH) welding can be used to obtain a higher deposition rate and lower porosity, while facilitating a cleaning effect by preheating and post heating the wire and the base metal. However, an asymmetric undercut and a black-colored deposit are created on the surface of PMH weld in Al alloys. For controlling the surface defect formation, the wire feeding speed and nozzle diameter in the PMH weld was investigated through arc phenomena with high-speed imaging and metallurgical analysis.

  6. Oxide film microstructure: the link between surface preparation processes and strength/durability of adhesively bonded aluminum. Final report

    SciTech Connect

    Hsia, K. Jimmy; Pearlstein, Arne J.; Scheeline, Alexander; Shang, Jian Ku

    2000-11-30

    Strength and durability of adhesive bonding of aluminum alloys structures are intrinsically determined by the surface microstructures and interfacial failure micromechanisms. The current project presents a multidisciplinary approach to addressing critical issues controlling the strength and durability of adhesive bonds of aluminum alloys. Three main thrust areas have been pursued: surface treatment technology development to achieve desirable surface microstructures; relationship between surface structure and properties of adhesive bonds; and failure mechanisms of adhesively bonded components.

  7. 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.

  8. Investigations Into the Influence of Weld Zone on Formability of Fiber Laser-Welded Advanced High Strength Steel

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    In this study, two different dual phase steel grades DP980 and DP600, and IFHS steel sheets were laser welded by a 2-kW fiber laser. The weld quality of these three different LWBs was assessed with the help of microstructure, micro-hardness and transverse tensile tests. Tensile testing of longitudinal and miniature samples was performed to evaluate the mechanical properties of the weld zone. Formability of parent materials and LWBs were assessed in bi-axial stretch forming condition by Erichsen cupping test. To validate the weld zone properties, 3-D finite element models of Erichsen cupping test of LWBs was developed, and the failures in the deformed cups were predicted using two theoretical forming limit diagrams. It was observed that hardness of the fusion zone and HAZ in laser welded DP600 and IFHS steels was more compared to the respective parent metal. However, 29% reduction in hardness was observed at the outer HAZ of DP980 steel weldments due to tempering of martensite. Reduction of formability was observed for all the LWBs with two distinct failure patterns, and the maximum reduction in formability was observed in the case of DP980 LWBs. The presence of the soft zone is detrimental in forming of welded DP steels.

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

    SciTech Connect

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

    2014-05-12

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

  10. Laser Peening for Mitigation of Stress Corrosion Cracking at Welds in Marine Aluminum

    DTIC Science & Technology

    2011-06-01

    therefore leaving the welded area and the HAZ in tension and the surround base metal in compression [ 6 ]. Figure 4 shows the residual stress of a MIG...either by electropolishing or vibratory polishing. The samples were electropolished in a Buehler Electromet 4 Electropolisher using a solution of...REPORT TYPE AND DATES COVERED Master’s Thesis 4 . TITLE AND SUBTITLE Laser Peening for Mitigation of Stress Corrosion Cracking at Welds in Marine

  11. 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.

  12. In-Situ Welding Carbon Nanotubes into a Porous Solid with Super-High Compressive Strength and Fatigue Resistance

    PubMed Central

    Lin, Zhiqiang; Gui, Xuchun; Gan, Qiming; Chen, Wenjun; Cheng, Xiaoping; Liu, Ming; Zhu, Yuan; Yang, Yanbing; Cao, Anyuan; Tang, Zikang

    2015-01-01

    Carbon nanotube (CNT) and graphene-based sponges and aerogels have an isotropic porous structure and their mechanical strength and stability are relatively lower. Here, we present a junction-welding approach to fabricate porous CNT solids in which all CNTs are coated and welded in situ by an amorphous carbon layer, forming an integral three-dimensional scaffold with fixed joints. The resulting CNT solids are robust, yet still highly porous and compressible, with compressive strengths up to 72 MPa, flexural strengths up to 33 MPa, and fatigue resistance (recovery after 100,000 large-strain compression cycles at high frequency). Significant enhancement of mechanical properties is attributed to the welding-induced interconnection and reinforcement of structural units, and synergistic effects stemming from the core-shell microstructures consisting of a flexible CNT framework and a rigid amorphous carbon shell. Our results provide a simple and effective method to manufacture high-strength porous materials by nanoscale welding. PMID:26067176

  13. 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…

  14. 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.…

  15. Intergranular corrosion following friction stir welding of aluminum alloy 7075-T651

    SciTech Connect

    Lumsden, J.B.; Mahoney, M.W.; Pollock, G.; Rhodes, C.G.

    1999-12-01

    Friction stir welding (FSW), a relatively new solid-state joining process, is used to join Al alloys of all compositions, including alloys essentially considered unweldable. This study focused on microstructures in FSW Al alloy 7075-T651 (AA 7075-T651 [UNS 97075-T651]), an alloy not commonly fusion welded, and the resultant corrosion susceptibility. Although the heat input associated with FSW was relatively low and the time at temperature was short compared to fusion welding, localized microstructures, chemical segregation, and precipitate distributions were created that generally are not present in parent metal AA 7075-T651. Typically, in the weld and heat affected zone (HAZ), the times at peak temperature were short, cooling was relatively rapid, and peak temperatures were {lt} {approx}500 C. Accordingly, a corresponding microstructural gradient developed from the weld nugget into the unaffected parent metal with the precipitate distribution in and around grain boundaries reflecting this temperature excursion. Some of these microstructures, when exposed to a corrosive environment, showed selective grain boundary attack and a decrease in the pitting potential relative to the parent metal. A characterization of the microstructure and localized chemistry differences within the weld zones suggested that the decrease in corrosion resistance correlated with a depletion of Cu within the grain boundaries and precipitate-free zones. These results provided evidence that the lowered resistance to intergranular corrosion following FSW of AA 7075-T651 was caused by a difference in pitting potentials.

  16. A mathematical model to predict the strength of aluminum alloys subjected to precipitation hardening

    SciTech Connect

    Qureshi, F.S.; Sheikh, A.K.; Rashid, M.

    1999-06-01

    A number of alloys, notably most of the aluminum alloys, can be heat treated by aging. This aging due to time-dependent precipitation hardening increases the strength and hardness as well as modifying other mechanical properties. Precipitation hardening has been a popular strengthening mechanism for many decades; therefore, extensive information is available in literature about the precipitation-hardening response of various series of aluminum alloys. The age-hardening response of these alloys is usually represented in graphical form as plotted between property changes and aging time for different temperatures. In designing a suitable precipitation-hardening strategy, one can refer to these graphs. However, for automatic control of aging furnaces, as well as for decision making regarding optimal selection of aging conditions (time/temperature combination), it is desirable to express these relationships in a formal mathematical structure. A mathematical model is developed in this article for widely used heat treatable aluminum alloys used in the extrusion industry. This model is a condensed representation of all {sigma} = f(T,t) curves in different series of aluminum alloys, and the parameters of this model characterize the various compositions of the alloys in the series.

  17. Strength advantages of chemically polished boron fibers before and after reaction with aluminum

    NASA Technical Reports Server (NTRS)

    Dicarlo, J. A.; Smith, R. J.

    1982-01-01

    In order to determine their strength potential, the fracture properties of different types of commercial boron fibers were measured before and after application of secondary strengthening treatments. The principal treatments employed were a slight chemical polish, which removed low strength surface flaws, and a heat treatment in oxygen, which contracted the fibers and thereby compressed intrinsic bulk flaws. Those fiber types most significantly strengthened were 200 to 400 micrometers (8 to 16 mil) diameter boron on tungsten fibers produced in a single chemical vapor deposition reactor. The slight polish increased average tensile strenghts from 3.4 to 4.4 CN/m2 (500 to 640 ksi) and reduced coefficients of variation from about 15 to 3 percent. The oxygen heat treatment plus slight polish further improved average strengths to 5.5 GN/m2 (800 ksi) with coefficients near 3 percent. To ascertain whether these excellent properties could be retained after fabrication of B/Al composites, as produced and polished 203 micrometers (8 mil) fibers were thinly coated with aluminum, heat treated at B/Al fabrication temperatures, and then tested in tension and flexure at room temperature. The pre-polished fibers were observed to retain their superior strengths to higher temperatures than the as-produced fibers even though both were subjected to the same detrimental reaction with aluminum.

  18. Influence of chromium on the mechanical properties and microstructure of weld metal from a high-strength SMA electrode

    SciTech Connect

    Surian, E.; Trotti, J. ); Cassanelli, A. ); Vedia, L.A. De )

    1994-03-01

    In the present work, the influence of Cr on mechanical properties and microstructure of weld metal from a high-strength SMA electrode is analyzed by considering 12 experimental low-alloy low-hydrogen iron powder AWS E10018, E11018, E12018-M type covered electrodes. These electrodes were manufactured to obtain in the weld deposits Cr contents ranging from 0 to 1.8%, with two different Mn levels for each Cr content, maintaining the amount of other elements at a fixed value. All-weld-metal specimens and production type single V-groove welds were mechanically tested in the as-welded and stress-relieved conditions, and a metallographic study was conducted. Chromium was found to be deleterious to toughness with only a minor influence due to Mn variations. A postweld heat treatment led in all cases to a reduction of toughness. Increasing Cr content in the welds produced a higher proportion of acicular ferrite and a general refinement of the microstructure.

  19. Examination of irradiated 304L stainless steel to 6061-T6 aluminum inertia welded transition joints after irradiation in a spallation neutron

    SciTech Connect

    Dunn, K.A.

    2000-04-28

    The Savannah River Technology Center (SRTC) designed and fabricated tritium target/blanket assemblies which were irradiated for six months at the Los Alamos Neutron Science Center (LANSCE). Cooling water was supplied to the assemblies through 1 inch diameter 304L Stainless Steel (SS) tubing. To attach the 304L SS tubing to the modules a 304L SS to 6061-T6 Aluminum (Al) inertia welded transition joint was used. These SS/Al inertia weld transition joints simulate expected transition joints in the Accelerator Production of Tritium (APT) Target/Blanket where as many as a thousand SS/Al weld transition joints will be used. Materials compatibility between the 304L SS and the 6061-T6 Al in the spallation neutron environment is a major concern as well as the corrosion associated with the cooling water flowing through the piping. The irradiated inertia weld examination will be discussed.

  20. Welding rework data acquisition and automation

    NASA Technical Reports Server (NTRS)

    Romine, Peter L.

    1996-01-01

    Aluminum-Lithium is a modern material that NASA MSFC is evaluating as an option for the aluminum alloys and other aerospace metals presently in use. The importance of aluminum-lithium is in it's superior weight to strength characteristics. However, aluminum-lithium has produced many challenges in regards to manufacturing and maintenance. The solution to these problems are vital to the future uses of the shuttle for delivering larger payloads into earth orbit and are equally important to future commercial applications of aluminum-lithium. The Metals Processes Branch at MSFC is conducting extensive tests on aluminum-lithium which includes the collection of large amounts of data. This report discusses the automation and data acquisition for two processes: the initial weld and the repair. The new approach reduces the time required to collect the data, increases the accuracy of the data, and eliminates several types of human errors during data collection and entry. The same material properties that enhance the weight to strength characteristics of aluminum-lithium contribute to the problems with cracks occurring during welding, especially during the repair/rework process. The repairs are required to remove flaws or defects discovered in the initial weld, either discovered by x-ray, visual inspection, or some other type of nondestructive evaluation. It has been observed that cracks typically appear as a result of or beyond the second repair. MSFC scientists have determined that residual mechanical stress introduced by the welding process is a primary cause of the cracking. Two obvious solutions are to either prevent or minimize the stress introduced during the welding process, or remove or reduce the stress after the welding process and MSFC is investigating both of these.

  1. Stress Corrosion Cracking Behavior of Multipass TIG-Welded AA2219 Aluminum Alloy in 3.5 wt pct NaCl Solution

    NASA Astrophysics Data System (ADS)

    Venugopal, A.; Sreekumar, K.; Raja, V. S.

    2012-09-01

    The stress corrosion cracking (SCC) behavior of the AA2219 aluminum alloy in the single-pass (SP) and multipass (MP) welded conditions was examined and compared with that of the base metal (BM) in 3.5 wt pct NaCl solution using a slow-strain-rate technique (SSRT). The reduction in ductility was used as a parameter to evaluate the SCC susceptibility of both the BM and welded joints. The results showed that the ductility ratio ( ɛ NaCl/( ɛ air) was 0.97 and 0.96, respectively, for the BM and MP welded joint, and the same was marginally reduced to 0.9 for the SP welded joint. The fractographic examination of the failed samples revealed a typical ductile cracking morphology for all the base and welded joints, indicating the good environmental cracking resistance of this alloy under all welded conditions. To understand the decrease in the ductility of the SP welded joint, preexposure SSRT followed by microstructural observations were made, which showed that the decrease in ductility ratio of the SP welded joint was caused by the electrochemical pitting that assisted the nucleation of cracks in the form of corrosion induced mechanical cracking rather than true SCC failure of the alloy. The microstructural examination and polarization tests demonstrated a clear grain boundary (GB) sensitization of the PMZ, resulting in severe galvanic corrosion of the SP weld joint, which initiated the necessary conditions for the localized corrosion and cracking along the PMZ. The absence of PMZ and a refined fusion zone (FZ) structure because of the lesser heat input and postweld heating effect improved the galvanic corrosion resistance of the MP welded joint greatly, and thus, failure occurred along the FZ.

  2. A fundamental study on the structural integrity of magnesium alloys joined by friction stir welding

    NASA Astrophysics Data System (ADS)

    Rao, Harish Mangebettu

    The goal of this research is to study the factors that influence the physical and mechanical properties of lap-shear joints produced using friction stir welding. This study focuses on understanding the effect of tool geometry and weld process parameters including the tool rotation rate, tool plunge depth and dwell time on the mechanical performance of similar magnesium alloy and dissimilar magnesium to aluminum alloy weld joints. A variety of experimental activities were conducted including tensile and fatigue testing, fracture surface and failure analysis, microstructure characterization, hardness measurements and chemical composition analysis. An investigation on the effect of weld process conditions in friction stir spot welding of magnesium to magnesium produced in a manner that had a large effective sheet thickness and smaller interfacial hook height exhibited superior weld strength. Furthermore, in fatigue testing of friction stir spot welded of magnesium to magnesium alloy, lap-shear welds produced using a triangular tool pin profile exhibited better fatigue life properties compared to lap-shear welds produced using a cylindrical tool pin profile. In friction stir spot welding of dissimilar magnesium to aluminum, formation of intermetallic compounds in the stir zone of the weld had a dominant effect on the weld strength. Lap-shear dissimilar welds with good material mixture and discontinues intermetallic compounds in the stir zone exhibited superior weld strength compared to lap-shear dissimilar welds with continuous formation of intermetallic compounds in the stir zone. The weld structural geometry like the interfacial hook, hook orientation and bond width also played a major role in influencing the weld strength of the dissimilar lap-shear friction stir spot welds. A wide scatter in fatigue test results was observed in friction stir linear welds of aluminum to magnesium alloys. Different modes of failure were observed under fatigue loading including crack

  3. Hybrid laser-MIG welding of aluminum alloys: The influence of shielding gases

    NASA Astrophysics Data System (ADS)

    Campana, G.; Ascari, A.; Fortunato, A.; Tani, G.

    2009-03-01

    In this paper, laser-GMAW hybrid welding technologies of light metals are investigated by focusing particularly on shielding gas related problems such as distribution on the welding zone, mixtures and flow. In particular, a Computational Fluid Dynamics (CFD) software was used with the aim to investigate the effect on gas distribution and contamination of the adoption of an isolation chamber surrounding the welding zone. In particular, the turbulent flow model adopted was a standard k- ɛ one. A simple parallelepipedal geometry for the isolation chamber was adopted whose width and depth were fixed, while the height was set as a variable. A simulation activity was carried out in order to evaluate the relationship among chamber height, flow rates and inlet angle inclinations. The simulated welding environment was simplified without considering the presence and the effect of the laser induced plasma plume and of the electric arc. The main results concern the influence of isolation chamber height, gas flow rate and gas inlet inclination on the shielding gas contamination and distribution in a zone near the heat sources-material interaction zone. These results underline that there are particular values of the chosen variables which optimize the gas distribution around the welding zone allowing to achieve an even and reliable shielding effect.

  4. The Formability of Friction Stir Welds in Automotive Stamping Environments

    SciTech Connect

    Grant, Glenn J.; Davies, Richard W.; Stephens, Elizabeth V.; wazny, scott; Kaunitz, Leon; Waldron, D.

    2005-04-01

    Automobile body and truck cab structures are composed primarily of stampings formed from monolithic and constant gage blanks. Cost and weight penalties can arrise when strength or other requirements in one small area of the part leads to the use of a material or gage that is overmatched to the needs of the rest of the stamping. Tailor Welded Blanks (TWBs) are hybrid sheet products composed of either different materials or different thickness sheets that are joined together, then subjected to a stamping operation to create a formed assembly. The strategy is employed generally to save weight and material costs in the formed assembly by placing higher strength or thicker sections only where needed. The forming or stamping process requires the joint to be severely deformed along with the parent sheets. Aluminum TWBs for automotive applications are particularly problematic because of the low formability of aluminum weld metal. Friction Stir Welding (FSW) is a process recently applied to Aluminum TWBs that has the potential to produce a higher quality weld. The current study presents data on the mechanical properties, formability, and FSW weld process parameter development for friction stir woined, aluminum, Tailor Welded Blanks. Friction stir welded TWBs can be shown to have higher formability, higher ductility, and lower defect content than many competing joining processes, and they can be fabricated at speeds appropriate for automotive manufacturing.

  5. Solute Enhanced Strain Hardening of Aluminum Alloys to Achieve Improved Combinations of Strength and Toughness

    NASA Astrophysics Data System (ADS)

    Hovanec, Christopher James

    2011-12-01

    The feasibility of achieving improved combinations of strength and toughness in aluminum alloy 2524 through solute enhanced strain hardening (SESH) has been explored in this study and shown to be viable. The effectiveness of SESH is directly dependent on the strain hardening rate (SHR) of the material being processed. Aluminum alloy 2524 naturally ages to the T4-temper after solution heat treating and quenching. The SHR of strain free and post cold rolled material as a function of natural aging time has been measured by means of simple compression. It has been determined that the SHR of AA2524 is more effective with solute in solution rather than clustered into GP zones. It has also been shown that the typical rapid formation of GP zones at room temperature (natural aging) is inhibited by moderate cold rolling strains (□CR ≥ 0.2) through dislocation aided vacancy annihilation. The practical limitations of quenching rate have been determined using hardness and eddy current electrical conductivity measurements. It has been shown that too slow of a quench rate results in solute being lost to both the formation of GP zones and embrittling precipitates during the quench, while too rapid of a quench rate results in mid-plane cracking of the work piece during the SESH processing. The mid-plane cracking was overcome by using an uphill quenching procedure to relieve residual stresses within the work piece. Aluminum alloy 2524 strengthened through SESH to a yield strength 11% greater than that in the T6-Temper exhibits: equivalent toughness, 5% greater UTS, 1% greater elongation, 7% greater R.A., and absorbs 15% more energy during tensile testing. At yield strengths comparable to published data for 2x24 alloys, the SESH 2524 exhibited up to a 60% increase in fracture toughness. The fractured surfaces of the SESH material exhibited transgranular dimpled rupture as opposed to the grain boundary ductile fracture (GBPF) observed in the artificially aged material.

  6. Evaluation of shear bond strength of porcelain bonded to laser welded titanium surface and determination of mode of bond failure.

    PubMed

    Patil, Narendra P; Dandekar, Minal; Nadiger, Ramesh K; Guttal, Satyabodh S

    2010-09-01

    The aim of this study was to evaluate the shear bond strength of porcelain to laser welded titanium surface and to determine the mode of bond failure through scanning electron microscopy (SEM) and energy dispersive spectrophotometry (EDS). Forty five cast rectangular titanium specimens with the dimension of 10 mm x 8 mm x 1 mm were tested. Thirty specimens had a perforation of 2 mm diameter in the centre. These were randomly divided into Group A and B. The perforations in the Group B specimens were repaired by laser welding using Cp Grade II titanium wire. The remaining 15 specimens were taken as control group. All the test specimens were layered with low fusing porcelain and tested for shear bond strength. The debonded specimens were subjected to SEM and EDS. Data were analysed with 1-way analysis of variance and Student's t-test for comparison among the different groups. One-way analysis of variance (ANOVA) showed no statistically significant difference in shear bond strength values at a 5% level of confidence. The mean shear bond strength values for control group, Group A and B was 8.4 +/- 0.5 Mpa, 8.1 +/- 0.4 Mpa and 8.3 +/- 0.3 Mpa respectively. SEM/EDS analysis of the specimens showed mixed and cohesive type of bond failure. Within the limitations of the study laser welding did not have any effect on the shear bond strength of porcelain bonded to titanium.

  7. Metallic Reinforcement of Direct Squeeze Die Casting Aluminum Alloys for Improved Strength and Fracture Resistance

    SciTech Connect

    D. Schwam: J.F. Wallace: Y. Zhu: J.W. Ki

    2004-10-01

    obtained with unreinforced 356 aluminum casting. Good strength can be obtained with a sound die casting without any defects produced by squeeze casting. The use of higher pressure to produce the squeeze casting has been shown to increase the strength of a hemispherical dome casting. This dome shape casting has been produced both with and without reinforcement and tested to determine its pressure resistance under internal pressure of water. Only a slight improvement in strength could be determined because of water leaks at the seal between hemispherical dome and its flat supporting side. However, when the ability of the casting was tested under the compressive force of a plunger, the strengthening effect of wire mesh or sheet was evident. Higher loads to failure were obtained because of the reinforcement of the stainless steel wire and punched sheet. Rather than a sudden failure occurring, the reinforcement of the stainless steel wire or the punched hard stainless steel sheet held the material together and prevented any loss of the fractured casting to the surroundings. Unalloyed steel did not have the required strength or mechanical properties to increase the properties of the casting.

  8. Tensile strength on friction stir processed AMg5 (5083) aluminum alloy

    NASA Astrophysics Data System (ADS)

    Chumaevsky, A. V.; Eliseev, A. A.; Filippov, A. V.; Rubtsov, V. E.; Tarasov, S. Yu.

    2016-11-01

    The results of the tensile tests carried out both on AMg5 (5083) aluminum alloy samples base and those obtained using friction stir processing technique are reported. The tensile test samples have been prepared from the friction stir processed plates so that their tensile axis was parallel to the processing direction. The maximum tensile strength of the processed samples was 9% higher than of the base metal. The fractographic examination shows the presence of flat areas inherent of the brittle fracture in all three friction processed samples. The load-extension curves show that friction stir processing may suppress the serrated yielding.

  9. Effect of Brake Forming on the Strength of 24S-T Aluminum-alloy Sheet

    NASA Technical Reports Server (NTRS)

    Heimerl, George J; Woods, Walter

    1946-01-01

    Tests were made to determine the effect of brake forming on the strength of 24S-T aluminum alloy sheet that had been formed to an inside bend radius of three times the sheet thickness. The results for both directions of the grain of the material showed that the compressive yield stresses were appreciably increased, that the tensile yield stresses were moderately increased, that the ultimate tensile stresses were only slightly increased, that the elongations were considerably reduced, and that the shapes of the tensile and compressive stress-strain curves were markedly changed.

  10. Effects of Fusion Zone Size and Failure Mode on Peak Load and Energy Absorption of Advanced High Strength Steel Spot Welds

    SciTech Connect

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

    2007-01-01

    This paper examines the effects of fusion zone size on failure modes, static strength and energy absorption of resistance spot welds (RSW) of advanced high strength steels (AHSS). DP800 and TRIP800 spot welds are considered. The main failure modes for spot welds are nugget pullout and interfacial fracture. Partial interfacial fracture is also observed. The critical fusion zone sizes to ensure nugget pull-out failure mode are developed for both DP800 and TRIP800 using limit load based analytical model and micro-hardness measurements of the weld cross sections. Static weld strength tests using cross tension samples were performed on the joint populations with controlled fusion zone sizes. The resulted peak load and energy absorption levels associated with each failure mode were studied for all the weld populations using statistical data analysis tools. The results in this study show that AHSS spot welds with fusion zone size of can not produce nugget pullout mode for both the DP800 and TRIP800 materials examined. The critical fusion zone size for nugget pullout shall be derived for individual materials based on different base metal properties as well as different heat affected zone (HAZ) and weld properties resulted from different welding parameters.

  11. Electrode formulation to reduce weld metal hydrogen and porosity

    SciTech Connect

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

    1994-12-31

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

  12. Temperature and Material Flow Prediction in Friction-Stir Spot Welding of Advanced High-Strength Steel

    SciTech Connect

    Miles, Michael; Karki, U.; Hovanski, Yuri

    2014-10-01

    Friction-stir spot welding (FSSW) has been shown to be capable of joining advanced high-strength steel, with its flexibility in controlling the heat of welding and the resulting microstructure of the joint. This makes FSSW a potential alternative to resistance spot welding if tool life is sufficiently high, and if machine spindle loads are sufficiently low that the process can be implemented on an industrial robot. Robots for spot welding can typically sustain vertical loads of about 8 kN, but FSSW at tool speeds of less than 3000 rpm cause loads that are too high, in the range of 11–14 kN. Therefore, in the current work, tool speeds of 5000 rpm were employed to generate heat more quickly and to reduce welding loads to acceptable levels. Si3N4 tools were used for the welding experiments on 1.2-mm DP 980 steel. The FSSW process was modeled with a finite element approach using the Forge* software. An updated Lagrangian scheme with explicit time integration was employed to predict the flow of the sheet material, subjected to boundary conditions of a rotating tool and a fixed backing plate. Material flow was calculated from a velocity field that is two-dimensional, but heat generated by friction was computed by a novel approach, where the rotational velocity component imparted to the sheet by the tool surface was included in the thermal boundary conditions. An isotropic, viscoplastic Norton-Hoff law was used to compute the material flow stress as a function of strain, strain rate, and temperature. The model predicted welding temperatures to within percent, and the position of the joint interface to within 10 percent, of the experimental results.

  13. Temperature and Material Flow Prediction in Friction-Stir Spot Welding of Advanced High-Strength Steel

    NASA Astrophysics Data System (ADS)

    Miles, M.; Karki, U.; Hovanski, Y.

    2014-10-01

    Friction-stir spot welding (FSSW) has been shown to be capable of joining advanced high-strength steel, with its flexibility in controlling the heat of welding and the resulting microstructure of the joint. This makes FSSW a potential alternative to resistance spot welding if tool life is sufficiently high, and if machine spindle loads are sufficiently low that the process can be implemented on an industrial robot. Robots for spot welding can typically sustain vertical loads of about 8 kN, but FSSW at tool speeds of less than 3000 rpm cause loads that are too high, in the range of 11-14 kN. Therefore, in the current work, tool speeds of 5000 rpm were employed to generate heat more quickly and to reduce welding loads to acceptable levels. Si3N4 tools were used for the welding experiments on 1.2-mm DP 980 steel. The FSSW process was modeled with a finite element approach using the Forge® software. An updated Lagrangian scheme with explicit time integration was employed to predict the flow of the sheet material, subjected to boundary conditions of a rotating tool and a fixed backing plate. Material flow was calculated from a velocity field that is two-dimensional, but heat generated by friction was computed by a novel approach, where the rotational velocity component imparted to the sheet by the tool surface was included in the thermal boundary conditions. An isotropic, viscoplastic Norton-Hoff law was used to compute the material flow stress as a function of strain, strain rate, and temperature. The model predicted welding temperatures to within 4%, and the position of the joint interface to within 10%, of the experimental results.

  14. Characterization of Residual Stress Effects on Fatigue Crack Growth of a Friction Stir Welded Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Newman, John A.; Smith, Stephen W.; Seshadri, Banavara R.; James, Mark A.; Brazill, Richard L.; Schultz, Robert W.; Donald, J. Keith; Blair, Amy

    2015-01-01

    An on-line compliance-based method to account for residual stress effects in stress-intensity factor and fatigue crack growth property determinations has been evaluated. Residual stress intensity factor results determined from specimens containing friction stir weld induced residual stresses are presented, and the on-line method results were found to be in excellent agreement with residual stress-intensity factor data obtained using the cut compliance method. Variable stress-intensity factor tests were designed to demonstrate that a simple superposition model, summing the applied stress-intensity factor with the residual stress-intensity factor, can be used to determine the total crack-tip stress-intensity factor. Finite element, VCCT (virtual crack closure technique), and J-integral analysis methods have been used to characterize weld-induced residual stress using thermal expansion/contraction in the form of an equivalent delta T (change in local temperature during welding) to simulate the welding process. This equivalent delta T was established and applied to analyze different specimen configurations to predict residual stress distributions and associated residual stress-intensity factor values. The predictions were found to agree well with experimental results obtained using the crack- and cut-compliance methods.

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

    PubMed

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

    2013-04-01

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

  16. 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

  17. Strength and structure of furnace-brazed joints between aluminum and stainless steel

    SciTech Connect

    Roulin, M.; Karadeniz, G.; Mortensen, A.; Luster, J.W.

    1999-05-01

    The structure and shear strength of brazed joints of aluminum to stainless steel are studied using a modification of the double lap joint configuration, which allows mechanical testing and joint microstructure examination on the same test piece. It is found that during furnace brazing of such joints at 600 C, using an Al-Si eutectic brazing alloy, the interfacial zone between the aluminum-rich braze and the stainless steel substrate features two intermetallic layers. The first is formed in the initial instants of the process and features an overall composition similar to that of the compound FeSiAl{sub 5}. The second appears after a 10-min hold time at the brazing temperature, and features an overall composition that parallels the FeAl{sub 3} intermetallic. Both layers are, however, more complex in structure than is suggested by these stoichiometric relations. The shear strength of the braze peaks at 21 MPa after a 10-min hold time at the brazing temperature. This peak is associated with nucleation of the second intermetallic layer, which is shown to fragilize the joint significantly. The presence of silicon in the brazing alloy would also seem to be beneficial by retarding formation of this second, more fragile Fe-Al intermetallic layer; however, more work is needed to substantiate this tentative conclusion.

  18. Weldable aluminum alloy has improved mechanical properties

    NASA Technical Reports Server (NTRS)

    Westerlund, R. W.

    1966-01-01

    Weldable aluminum alloy has good resistance to stress-corrosion cracking, shows unchanged strength and formability after storage at room temperature, and can be pre-aged, stretched, and aged. Since toxic fumes of cadmium oxide are evolved when the new alloy is welded, adequate ventilation must be provided.

  19. 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.

  20. 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.

  1. Aluminum alloys for satellite boxes : engineering guidelines for obtaining adequate strength while minimizing residual stresses and machining distortion.

    SciTech Connect

    Younger, Mandy S.; Eckelmeyer, Kenneth Hall

    2007-11-01

    This report provides strategies for minimizing machining distortion in future designs of aluminum alloy satellite boxes, based in part on key findings from this investigation. The report outlines types of aluminum alloys and how they are heat treated, how residual stresses develop during heat treatment of age hardening alloys, ways residual stresses can be minimized, and the design of machining approaches to minimize distortion in parts that contain residual stresses. Specific recommendations are made regarding alloy selection, heat treatment, stress relieving, and machining procedures for boxes requiring various strength levels with emphasis on 6061 and 7075 aluminum alloys.

  2. Effects of Fusion Zone Size on Failure Modes and Performance of Advanced High Strength Steel Spot Welds (2006-01-0531)

    SciTech Connect

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

    2007-03-01

    This paper examines the effects of fusion zone size on failure modes, static strength and energy absorption of resistance spot welds (RSW) of advanced high strength steels (AHSS). DP800 and TRIP800 spot welds are considered. The main failure modes for spot welds are nugget pullout and interfacial fracture. Partial interfacial fracture is also observed. The critical fusion zone sizes to ensure nugget pull-out failure mode are developed for both DP800 and TRIP800 using the limit load based analytical model and the micro-hardness measurements of the weld cross sections. Static weld strength tests using cross tension samples were performed on the joint populations with controlled fusion zone sizes. The resulted peak load and energy absorption levels associated with each failure mode were studied using statistical data analysis tools. The results in this study show that the conventional weld size of 4 t1/2 can not produce nugget pullout mode for both the DP800 and TRIP800 materials. The results also suggest that performance based spot weld acceptance criteria should be developed for different AHSS spot welds.

  3. Effect of low-velocity or ballistic impact damage on the strength of thin composite and aluminum shear panels

    NASA Technical Reports Server (NTRS)

    Farley, G. L.

    1985-01-01

    Impact tests were conducted on shear panels fabricated from 6061-T6 aluminum and from woven fabric prepreg of Du Pont Kevlara fiber/epoxy resin and graphite fiber/epoxy resin. The shear panels consisted of three different composite laminates and one aluminum material configuration. Three panel aspect ratios were evaluated for each material configuration. Composite panels were impacted with a 1.27-cm (0.05-in) diameter aluminum sphere at low velocities of 46 m/sec (150 ft/sec) and 67 m/sec (220 ft/sec). Ballistic impact conditions consisted of a tumbled 0.50-caliber projectile impacting loaded composite and aluminum shear panels. The results of these tests indicate that ballistic threshold load (the lowest load which will result in immediate failure upon penetration by the projectile) varied between 0.44 and 0.61 of the average failure load of undamaged panels. The residual strengths of the panels after ballistic impact varied between 0.55 and 0.75 of the average failure strength of the undamaged panels. The low velocity impacts at 67 m/sec (220 ft/sec) caused a 15 to 20 percent reduction in strength, whereas the impacts at 46 m/sec (150 ft/sec) resulted in negligible strength loss. Good agreement was obtained between the experimental failure strengths and the predicted strength with the point stress failure criterion.

  4. Microstructural Evolution During Friction Stir Welding of Near-Alpha Titanium

    DTIC Science & Technology

    2009-02-01

    focused on aluminum alloys. However, there is also substantial interest in developing FSW for higher strength alloys such as titanium and steels . Such...higher loads needed for some of these alloys. Although FSW of these high strength alloys has seen much less development than FSW of aluminum alloys... FSW of many high strength alloys in titanium and steel has been demonstrated and research on the welding of these alloys is increasing [e.g., 2– 14

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

    SciTech Connect

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

    2004-03-15

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

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

    SciTech Connect

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

    2007-05-17

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

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

  8. 49 CFR 178.68 - Specification 4E welded aluminum cylinders.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... cylinder must be constructed of aluminum of uniform quality. The following chemical analyses are authorized: Table 1—Authorized Materials Designation Chemical analysis—limits in percent 5154 1 Iron plus silicon 0... information required by § 178.35, the record of chemical analyses must also include applicable information...

  9. Advanced Welding Applications

    NASA Technical Reports Server (NTRS)

    Ding, Robert J.

    2010-01-01

    Some of the applications of advanced welding techniques are shown in this poster presentation. Included are brief explanations of the use on the Ares I and Ares V launch vehicle and on the Space Shuttle Launch vehicle. Also included are microstructural views from four advanced welding techniques: Variable Polarity Plasma Arc (VPPA) weld (fusion), self-reacting friction stir welding (SR-FSW), conventional FSW, and Tube Socket Weld (TSW) on aluminum.

  10. Residual strength of five boron/aluminum laminates with crack-like notches after fatigue loading

    NASA Technical Reports Server (NTRS)

    Simonds, R. A.

    1986-01-01

    Boron/aluminum specimens were made with crack-like slits in the center and with various proportions of 0 and + or - 45 deg plies. They were fatigue loaded and then fractured to determine their residual strengths. The fatigue loads were generally in the range of 60 to 80 percent of the static tensile strength of the specimen as determined from a previous study, and the stress ratio was .05. For virtually all of the specimens the fatigue loading was continued for 100,000 cycles. The specimens were radiographed after the fatigue loading to determine the nature of the fatigue damage. A few specimens were sectioned and examined in a scanning electron microscope after being radiographed in order to verify the interpretation of the radiographs and also to get a better insight into the nature of the fatigue damage. The results indicate that the fatiguing does not significantly affect the strength of the specimens tested. The results of the radiography and of the scanning electron microscopy indicate that the 45 deg plies suffer extensive damage in the form of split and broken fibers and matrix cracking in the vicinity of the ends of the split. By contrast, the only significant damage to the 0 deg plies was a single 0 deg matric crack growing from the ends of the slit and between the 0 deg fibers.

  11. Microtensile bond strength of composite resin to human enamel prepared using erbium: Yttrium aluminum garnet laser.

    PubMed

    Delfino, Carina Sinclér; Souza-Zaroni, Wanessa Christine; Corona, Silmara Aparecida Milori; Palma-Dibb, Regina Guenka

    2007-02-01

    The Erbium: Yttrium Aluminum Garnet (YAG) laser used for preparation of cavity can alter the substrate and it could influence the bond strength of enamel. The aim of this in vitro study was to evaluate the influence of Er:YAG laser's energy using microtensile bond test. Three groups were obtained (cavity preparation) and each group was divided into two subgroups (adhesive system). After that the adhesive protocol was performed, sections with a cross-sectional area of 0.8 mm2 (+/-0.2 mm2) were obtained. The specimens were mounted in a universal testing machine (0.5 mm/min). Statistical analysis showed a decrease in bond strength for lased groups (p < 0.01) and when the total-etching adhesive system was used the laser 300 mJ subgroup showed higher bond strength compared to the laser 250 mJ (p < 0.01). It was concluded that the cavities prepared using laser appear less receptive to adhesive procedures than conventional bur-cut cavities.

  12. Residual strength of five boron/aluminum laminates with crack-like notches after fatigue loading

    NASA Technical Reports Server (NTRS)

    Simonds, R. A.

    1984-01-01

    Boron/aluminum specimens were made with crack-like slits in the center and with various proportions of 0 and + or - 45 deg plies. They were fatigue loaded and then fractured to determine their residual strengths. The fatigue loads were generally in the range of 60 to 80 percent of the static tensile strength of the specimen as determined from a previous study, and the stress ratio was .05. For virtually all of the specimens the fatigue loading was continued for 100,000 cycles. The specimens were radiographed after the fatigue loading to determine the nature of the fatigue damage. A few specimens were sectioned and examined in a scanning electron microscope after being radiographed in order to verify the interpretation of the radiographs and also to get a better insight into the nature of the fatigue damage. The results indicate that the fatiguing does not significantly affect the strength of the specimens tested. The results of the radiography and of the scanning electron microscopy indicate that the 45 deg plies suffer extensive damage in the form of split and broken fibers and matrix cracking in the vicinity of the ends of the split. By contrast, the only significant damage to the 0 deg plies was a single 0 deg matric crack growing from the ends of the slit and between the 0 deg fibers.

  13. Effect of aluminum anodizing in phosphoric acid electrolyte on adhesion strength and thermal performance

    NASA Astrophysics Data System (ADS)

    Lee, Sulki; Kim, Donghyun; Kim, Yonghwan; Jung, Uoochang; Chung, Wonsub

    2016-01-01

    This study examined the adhesive bond strength and thermal performance of the anodized aluminum 6061 in phosphoric acid electrolyte to improve the adhesive bond strength and thermal performance for use in metal core printed circuit boards (MCPCB). The electrolyte temperature and applied voltage were altered to generate varied pore structures. The thickness, porosity and pore diameter of the anodized layer were measured. The pore morphologies were affected most by temperature, which was the driving force for ion transportation. The mechanism of adhesive bond was penetration of the epoxy into the pores. The optimal anodization conditions for maximum adhesive bond strength, 27 MPa, were 293 K and 100V. The maximum thermal conductivity of the epoxy-treated anodized layer was 1.6 W/m·K at 273 K. Compared with the epoxy-treated Al layer used for conventional MCPCBs, the epoxy-treated anodized layer showed advanced thermal performance due to a low difference of thermal resistance and high heat dissipation.

  14. Gas Metal Arc Weld (GMAW) Qualification of 7020-T651 Aluminum

    DTIC Science & Technology

    2015-11-01

    beam, and push-pull wire feed........................................................9 Fig. 6 Drawing of v-groove joint and end tabs used for ballistic...procedure 806-1, 5087 wire , GMAW-P, page 3 ........................52 vii Fig. C-1 Drawing of the 25.04-mm-thick qualification panels (QPs...plate made with the condition of 5556A wire , GMAW-P mode, and 25.04-mm plate thickness. Fig. 4 Drawing and tension specimens for welds of 39.94-mm

  15. Localized Corrosion Currents from Graphite/Aluminum and Welded SiC/Al Metal Matrix Composites.

    DTIC Science & Technology

    1985-02-28

    the corrosion rate in the absence of flaws might be improved by additions of poisions to the fiber to retard the oxygen reduction reaction on graphite...weidment 8 Al4C3 + 12H 20 + 4Al(OH) 3 + 3CH 4 This reaction, along with other metallurgical variations caused by the heat of welding, leads to...efficient cathodic sites along anodic corrosion paths and can lead to exfoliation in 6061 Al when the inter- metallics are present in an appropriate

  16. An investigation of the microstructure and strength of open-cell 6101 aluminum foams

    NASA Astrophysics Data System (ADS)

    Zhou, J.; Mercer, C.; Soboyejo, W. O.

    2002-05-01

    This article presents the results of a study of the microstructure and strength of open-cell 6101 aluminum alloy fans with three different levels of pore size (measured in pores per inch (PPI)). The macrostructures and microstructures of open-cell foam struts are characterized using a combination of optical and scanning electron microscopy (SEM). The compositions of the individual phases are also determined via energy-dispersive spectroscopy (EDS). The variations in strut microhardness are then measured using Vickers microindentation techniques. Following the measurement of the mechanical properties of foams, a modified model is used to estimate the relative density from measured strut dimensions. The mechanisms of compressive deformation are then elucidated before presenting a discussion on unit-cell modeling, strut plastic deformation, and the relationships between strut microstructure and microhardness.

  17. Examination of the physical processes associated with the keyhole region of variable polarity plasma arc welds in aluminum alloy 2219

    NASA Technical Reports Server (NTRS)

    Walsh, Daniel W.

    1987-01-01

    The morphology and properties of the Variable Polarity Plasma Arc (VPPA) weld composite zone are intimately related to the physical processes associated with the keyhole. This study examined the effects of oxide, halide, and sulfate additions to the weld plate on the keyhole and the weld pool. Changes in both the arc plasma character and the bead morphology were correlated to the chemical environment of the weld. Pool behavior was observed by adding flow markers to actual VPPA welds. A low temperature analog to the welding process was developed. The results of the study indicate that oxygen, even at low partial pressures, can disrupt the stable keyhole and weld pool. The results also indicate that the Marangoni surface tension driven flows dominate the weld pool over the range of welding currents studied.

  18. Development of Corrosion Resistant Surface Treatments for Aluminum Alloys for Spot-Weld Bonding

    DTIC Science & Technology

    1975-03-01

    success- fully. Both surface treatments, ammonium tartrate anodize and FPL etch/ dichromate seal, were carried forward in the program until an...Phosphoric Acid Anodize 3. Sulfuric Acid Anodize 4. Chromic Acid Anodize 5. Ammonium Tartrate Anodize 6. FPL Etch plus Dichromate Seal 7. A.R. Aluminum...Etch Plus Dichromate Seal Low Voltage Ammonium Tartrate Anodize Low Voltage Sulfuric Acid Anodize Low Voltage Phos- phoric Acid Anodize 30-280

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

    SciTech Connect

    Sun, Xin; Khaleel, Mohammad A.

    2007-10-01

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

  20. Picosecond laser welding of optical to metal components

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  1. General Corrosion Resistance Comparisons of Medium- and High-Strength Aluminum Alloys for DOD Systems Using Laboratory-Based Accelerated Corrosion Methods

    DTIC Science & Technology

    2009-09-01

    General Corrosion Resistance Comparisons of Medium- and High-Strength Aluminum Alloys for DOD Systems Using Laboratory-Based Accelerated... Aluminum Alloys for DOD Systems Using Laboratory-Based Accelerated Corrosion Methods Brian E. Placzankis Weapons and Materials Research Directorate...March 2006–October 2008 4. TITLE AND SUBTITLE General Corrosion Resistance Comparisons of Medium- and High-Strength Aluminum Alloys for DOD

  2. A Multi-scale Thermomechanical-Solidification Model to Simulate the Transient Force Field Deforming an Aluminum 6061 Semisolid Weld

    NASA Astrophysics Data System (ADS)

    Zareie Rajani, H. R.; Phillion, A. B.

    2015-08-01

    Formation of hot cracks is strongly affected by the transient force field acting on the semisolid weld-base metal interface. This paper presents a model that numerically simulates such a transient force field as a function of welding parameters. The model consists of two modules: (1) By means of a granular model of solidification, the microstructure of the semisolid area within the weld is reconstructed in three dimensions; (2) Since the transient force field is developed through the mechanical interaction between the semisolid weld and its base metal, the mechanical response of the base metal to the solidification of the weld is then simulated through finite element analysis. The results show that changing welding parameters and welding constraints varies the transient force field. Based on the obtained force fields, a qualitative study is also conducted to predict the susceptibility of various welds to hot cracking.

  3. Elevated temperature flow strength, creep resistance and diffusion welding characteristics of Ti-6Al-2Nb-1Ta-0.8Mo

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. D.; Moore, T. J.

    1979-01-01

    A study of the flow strength, creep resistance and diffusion welding characteristics of the titanium alloy Ti-6Al-2Nb-1Ta-0.8Mo has been conducted. Two mill-processed forms of this alloy were examined. The forged material had been processed above the beta transus (approximately 1275 K) while the rolled form had been subjected to work below the beta transus. Between 1150 and 1250 K, the forged material was stronger and more creep resistant than the rolled alloy. Both forms exhibit superplastic characteristics in this temperature range. Strain measurements during diffusion welding experiments at 1200 K reveal that weld interfaces have no measurable effect on the overall creep deformation. Significant deformation appears to be necessary to produce a quality diffusion weld between superplastic materials. A 'soft' interlayer inserted between faying surfaces would seemingly allow manufacture of quality diffusion welds with little overall deformation.

  4. Elevated-temperature flow strength, creep resistance and diffusion welding characteristics of Ti-gAl-2Nb-1Ta-0.8Mo

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. D.; Moore, T. J.

    1977-01-01

    A study of the flow strength, creep resistance and diffusion welding characteristics of the titanium alloy Ti-6Al-2Nb-1Ta-0.8Mo was conducted. Two mill-processed forms of this alloy were examined. The forged material was essentially processed above the beta transus while the rolled form was subjected to considerable work below the beta transus. Between 1150 and 1250 K, the forged material was stronger and more creep resistant than the rolled alloy. Both forms exhibit superplastic characteristics in this temperature range. Strain measurements during diffusion welding experiments at 1200 K reveal that weld interfaces have no measurable effect on the overall creep deformation. Significant deformation appears to be necessary to produce a quality diffusion weld between superplastic materials. A 'soft' interlayer inserted between faying surfaces would seemingly allow manufacture of quality diffusion welds with little overall deformation.

  5. Characterization of the tensile properties of friction stir welded aluminum alloy joints based on axial force, traverse speed, and rotational speed

    NASA Astrophysics Data System (ADS)

    Panda, Biranchi; Garg, A.; Jian, Zhang; Heidarzadeh, Akbar; Gao, Liang

    2016-09-01

    Friction stir welding (FSW) process has gained attention in recent years because of its advantages over the conventional fusion welding process. These advantages include the absence of heat formation in the affected zone and the absence of large distortion, porosity, oxidation, and cracking. Experimental investigations are necessary to understand the physical behavior that causes the high tensile strength of welded joints of different metals and alloys. Existing literature indicates that tensile properties exhibit strong dependence on the rotational speed, traverse speed, and axial force of the tool that was used. Therefore, this study introduces the experimental procedure for measuring tensile properties, namely, ultimate tensile strength (UTS) and tensile elongation of the welded AA 7020 Al alloy. Experimental findings suggest that a welded part with high UTS can be achieved at a lower heat input compared with the high heat input condition. A numerical approach based on genetic programming is employed to produce the functional relationships between tensile properties and the three inputs (rotational speed, traverse speed, and axial force) of the FSW process. The formulated models were validated based on the experimental data, using the statistical metrics. The effect of the three inputs on the tensile properties was investigated using 2D and 3D analyses. A high UTS was achieved, including a rotational speed of 1050 r/min and traverse speed of 95 mm/min. The results also indicate that 8 kN axial force should be set prior to the FSW process.

  6. Corrosion Behavior of Top and Bottom Surfaces for Single-Side and Double-Side Friction Stir Welded 7085-T7651 Aluminum Alloy Thick Plate Joints

    NASA Astrophysics Data System (ADS)

    Xu, Weifeng; Zhang, Wei; Wu, Xiaoli

    2017-01-01

    Thick plate joints of 7085-T7451 aluminum alloy were obtained through both single-side and double-side friction stir welding (SS or DS-FSW). The chloride ions effects on the corrosion behavior of the top and bottom surfaces of the joints were examined by cyclic potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). Results show that the corrosion susceptibility was suppressed significantly in the weld nugget zone, while the base material and heat-affected zone were prone to be corrosion attacked. For the SS-FSWed joint, the top surface showed a higher corrosion resistance than that of the bottom surface, but the larger corrosive heterogeneity was observed between the top and bottom surfaces compared with the two welds of DS-FSWed joint, which was confirmed by the morphology of corrosion attack. A deep insight on the microstructure of the joints indicates that the intermetallic particles played a key role in the corrosion behavior of the FSWed AA7085 aluminum alloy joints in chloride solution.

  7. Corrosion Behavior of Top and Bottom Surfaces for Single-Side and Double-Side Friction Stir Welded 7085-T7651 Aluminum Alloy Thick Plate Joints

    NASA Astrophysics Data System (ADS)

    Xu, Weifeng; Zhang, Wei; Wu, Xiaoli

    2017-03-01

    Thick plate joints of 7085-T7451 aluminum alloy were obtained through both single-side and double-side friction stir welding (SS or DS-FSW). The chloride ions effects on the corrosion behavior of the top and bottom surfaces of the joints were examined by cyclic potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). Results show that the corrosion susceptibility was suppressed significantly in the weld nugget zone, while the base material and heat-affected zone were prone to be corrosion attacked. For the SS-FSWed joint, the top surface showed a higher corrosion resistance than that of the bottom surface, but the larger corrosive heterogeneity was observed between the top and bottom surfaces compared with the two welds of DS-FSWed joint, which was confirmed by the morphology of corrosion attack. A deep insight on the microstructure of the joints indicates that the intermetallic particles played a key role in the corrosion behavior of the FSWed AA7085 aluminum alloy joints in chloride solution.

  8. Light weight and high strength materials made of recycled steel and aluminum

    NASA Astrophysics Data System (ADS)

    Nounezi, Thomas

    Recycling has proven not only to address today's economical, environmental and social issues, but also to be imperative for the sustainability of human technology. The current thesis has investigated the feasibility of a new philosophy for Recycling (Alloying-Recycling) using steel 1020 and aluminum 6061T6. The study was limited to the metallurgical aspects only and has highlighted the potential of recycled alloys made of recycled aluminum and steel to exhibit substantially increased wear resistance and strength-to-weight ratio as compared to initial primary materials. Three alloy-mixtures are considered: TN3 (5wt% 1020 +95wt% 6061T6); TN5 (0.7wt% 1020 + 99.3wt% 6061T6); and TN4 (10wt% 6061T6 + 90wt% 1020). A Tucker induction power supply system (3kW; 135-400 kHz) is used to melt the alloy mixtures for casting in graphite crucibles. Heat treatment of the cast samples is done using a radiation box furnace. Microscopy, Vickers hardness and pin-on-disc abrasive wear tests are performed. Casting destroyed the initial microstructures of the alloys leading to a hardness reduction in the as-cast and solution heat-treated aluminum rich samples to 60 Hv from 140 Hv. Ageing slightly increased the hardness of the cast samples and provided a wear resistance two times higher than that of the initial 6061T6 material. On the steel rich side, the hardness of the as-cast TN4 was 480 Hv, which is more than twice as high as the initial hardness of steel 1020 of 202 Hv; this hints to strong internal and residual stress, probably martensite formation during fast cooling following casting. Solution heat treatment lowered the hardness to the original value of steel 1020, but provided about ten (10) times higher wear resistance; this suggests higher ductility and toughness of normalised TN4 as compared to 1020. In addition, TN4 exhibits about 25% weight reduction as compared to 1020. The actual recycling process and the effect of non-metallic impurities shall be investigated in future

  9. Effects of welding and post-weld heat treatments on nanoscale precipitation and mechanical properties of an ultra-high strength steel hardened by NiAl and Cu nanoparticles

    SciTech Connect

    Jiao, Z. B.; Luan, J. H.; Guo, W.; Poplawsky, J. D.; Liu, C. T.

    2016-09-01

    The effects of welding and post-weld heat treatment (PWHT) on nanoscale co-precipitation, grain structure, and mechanical properties of an ultra-high strength steel were studied through a combination of atom probe tomography (APT) and mechanical tests. Our results indicate that the welding process dissolves all pre-existing nanoparticles and causes grain coarsening in the fusion zone, resulting in a soft and ductile weld without any cracks in the as-welded condition. A 550 °C PWHT induces fine-scale re-precipitation of NiAl and Cu co-precipitates with high number densities and ultra-fine sizes, leading to a large recovery of strength but a loss of ductility with intergranular failure, whereas a 600 °C PWHT gives rise to coarse-scale re-precipitation of nanoparticles together with the formation of a small amount of reverted austenite, resulting in a great recovery in both strength and ductility. Our analysis indicates that the degree of strength recovery is dependent mainly upon the re-precipitation microstructure of nanoparticles, together with grain size and reversion of austenite, while the ductility recovery is sensitive to the grain-boundary structure. In conclusion, APT reveals that the grain-boundary segregation of Mn and P may be the main reason for the 550 °C embrittlement, and the enhanced ductility at 600 °C is ascribed to a possible reduction of the segregation and reversion of austenite.

  10. Avoidance of stress corrosion susceptibility in high strength aluminum alloys by control of grain boundary and matrix microstructure

    NASA Technical Reports Server (NTRS)

    Adler, P.; Deiasi, R.

    1974-01-01

    The relation of microstructure to the mechanical strength and stress corrosion resistance of highest strength and overaged tempers of BAR and 7050 aluminum alloys was investigated. Comparison is made with previously studied 7075 aluminum alloy. Optical microscopy, transmission electron microscopy, and differential scanning calorimetry were used to characterize the grain morphology, matrix microstructure, and grain boundary microstructure of these tempers. Grain boundary interparticle spacing was significant to stress corrosion crack propagation for all three alloys; increasing interparticle spacing led to increased resistance to crack propagation. In addition, the fire grain size in Bar and 7050 appears to enhance crack propagation. The highest strength temper of 7050 has a comparatively high resistance to crack initiation. Overall stress corrosion behavior is dependent on environment pH, and evaluation over a range of pH is recommended.

  11. Submerged-arc welding slags: characterization and leaching strategies for the removal of aluminum and titanium.

    PubMed

    Annoni, Raquel; Souza, Poliana Santos; Petrániková, Martina; Miskufova, Andrea; Havlík, Tomáš; Mansur, Marcelo Borges

    2013-01-15

    In the present study, submerged-arc welding slags were characterized by applying a variety of methods, including X-ray fluorescence, X-ray diffraction, particle size, Raman spectroscopy, and scanning electron microscope with energy dispersive X-ray analysis. The content of Al proved to be quite similar within neutral and acid slags (10-14%), while that of Ti proved to be much higher in acid slags (approximately 10%) than in neutral slags (<1%). The presence of spinel structures associated with Al species could also be identified in the analyzed samples. This characterization study was accompanied by leaching tests performed under changing operating conditions in an attempt to evaluate to what extent the Al and Ti bearing components could be removed from the slags. The leaching work involved three distinct strategies: (i) NaOH leaching followed by H(2)SO(4) leaching, (ii) acid leaching (HCl and H(2)SO(4)) using oxidizing/reducing agents, and (iii) slag calcination followed by H(2)SO(4) leaching. In the best result, 80% of Al was extracted in one single leaching stage after calcination of the acid slag with NaCl+C at 900 °C. By contrast, the removal of Ti proved to be unsatisfactory.

  12. Alternating-Polarity Arc Welding

    NASA Technical Reports Server (NTRS)

    Schwinghamer, R. J.

    1987-01-01

    Brief reversing polarity of welding current greatly improves quality of welds. NASA technical memorandum recounts progress in art of variable-polarity plasma-arc (VPPA) welding, with emphasis on welding of aluminum-alloy tanks. VPPA welders offer important advantages over conventional single-polarity gas/tungsten arc welders.

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

    SciTech Connect

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

    2011-01-17

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

  14. Assessment of weld quality of aerospace grade metals by using ultrasonic matrix phased array technology

    NASA Astrophysics Data System (ADS)

    Na, Jeong K.; Gleeson, Sean T.

    2014-03-01

    Advantages of two dimensional electronic ultrasonic beam focusing, steering and scanning with the matrix phased array (MPA) technology has been used to visualize the conditions of resistance spot welds in auto vehicle grade advanced high strength steel carbon steels nondestructively. Two of the commonly used joining techniques, resistance spot welding and resistance seam welding, for thin aerospace grade plates made of aluminum, titanium, and stainless steels have also been inspected with the same MPA NDE system. In this study, a detailed discussions of the current MPA based ultrasonic real time imaging methodology has been made followed by some of the NDT results obtained with various welded test coupons.

  15. Analysing the strength of friction stir spot welded joints of aluminium alloy by fuzzy logic

    NASA Astrophysics Data System (ADS)

    Vaira Vignesh, R.; Padmanaban, R.; Arivarasu, M.; Karthick, K. P.; Abirama Sundar, A.; Gokulachandran, J.

    2016-09-01

    Friction stir spot welding (FSSW) is a recent joining technique developed for spot welding of thin metal sheets. This process currently finds application in automotive, aerospace, marine and sheet metal industry. In this work, the effect of FSSW process parameters namely tool rotation speed, shoulder diameter and dwell time on Tensile shear failure load (TSFL) is investigated. Box-Behnken design is selected for conducting experiments. Fuzzy based soft computing is used to develop a model for TSFL of AA6061 joints fabricated by FSSW. The interaction of the process parameters on TSFL is also presented.

  16. Cracking Tendancies of Restrained Welds in High Strength Low Alloy Steels under Hyperbaric Conditions.

    DTIC Science & Technology

    1987-06-01

    and burning flux of a typical SMA welding electrode is about equivalent to a CO2 gas flow of 12 litres per minute. 44 The effect of pressure in...the equivalent gas shield flow rate is reduced to about half so that even at thIs shallow depth, lack of adequate protection may begin to show its...subjects Including: 69 A (a) Welding processes and techniques. Which processes are used: "dry" or " wet " shielded metal ar-c process or gas metal ar-c

  17. Belled end fittings: A recently qualified, high strength, low cost, and production friendly welded fitting design

    SciTech Connect

    Bayard, R.R.; Oakes, F.D. Jr.

    1996-07-01

    This paper presents an overview of the design development, fatigue testing, MSS Standard Practice development and Navy shipboard use of light wall (Schedule 10) socket welded cold formed fittings designed to replace B16.9 type butt welded fittings in sizes 1/4 through 12 NPS. Variations of the belled end fitting design have been successfully used -- thus proven in service -- for almost 40 years. This Government-sponsored program has legitimized the fittings by laboratory testing, has standardized the fittings by Standard Practice publication and has given the fittings a market presence by acceptance on Navy ship new construction and repair.

  18. The tensile strength of 339 aluminum reinforced with Kaowool fibers: A comparison of T5 and T6 heat treatments

    SciTech Connect

    Baxter, W.J.; Sachdev, A.K.

    1999-07-01

    This study compares the effects of T5 and T6 heat treatment on the tensile strengths of both KAOWOOL fiber reinforced and unreinforced 339 aluminum. The 339 Al-T6 is stronger than 339 AL-T5 (as expected), but for a KAOWOOL/339 Al composite, the T5 condition is substantially stronger than the T6. The controlling parameter is the strength of the aluminum dendrites, which in turn is proportional to the concentration of magnesium retained in the dendrites. In the T5 condition, more than half of the magnesium is in the form of large intermetallics in both the unreinforced alloy and the KAOWOOL/339 Al composite. During a T6 heat treatment, magnesium in the intermetallics is redissolved. In the unreinforced T6 alloy, this additional magnesium is retained in and strengthens the dendrites. But in the T6 composite, the magnesium segregates extensively to the KAOWOOL/aluminum interfaces depleting and softening the dendrites. This factor along is sufficient to account for the low strength of the T6 composites. The tensile strengths of both the T5 and T6 composites correspond to the calculated values for a perfectly bonded system.

  19. Grain size effect on yield strength of titanium alloy implanted with aluminum ions

    NASA Astrophysics Data System (ADS)

    Popova, Natalya; Nikonenko, Elena; Yurev, Ivan; Kalashnikov, Mark; Kurzina, Irina

    2016-01-01

    The paper presents a transmission electron microscopy (TEM) study of the microstructure and phase state of commercially pure titanium VT1-0 implanted by aluminum ions. This study has been carried out before and after the ion implantation for different grain size, i.e. 0.3 µm (ultra-fine grain condition), 1.5 µm (fine grain condition), and 17 µm (polycrystalline condition). This paper presents details of calculations and analysis of strength components of the yield stress. It is shown that the ion implantation results in a considerable hardening of the entire thickness of the implanted layer in the both grain types. The grain size has, however, a different effect on the yield stress. So, both before and after the ion implantation, the increase of the grain size leads to the decrease of the alloy hardening. Thus, hardening in ultra-fine and fine grain alloys increased by four times, while in polycrystalline alloy it increased by over six times.

  20. Grain size effect on yield strength of titanium alloy implanted with aluminum ions

    SciTech Connect

    Popova, Natalya; Yurev, Ivan; Kalashnikov, Mark

    2016-01-15

    The paper presents a transmission electron microscopy (TEM) study of the microstructure and phase state of commercially pure titanium VT1-0 implanted by aluminum ions. This study has been carried out before and after the ion implantation for different grain size, i.e. 0.3 µm (ultra-fine grain condition), 1.5 µm (fine grain condition), and 17 µm (polycrystalline condition). This paper presents details of calculations and analysis of strength components of the yield stress. It is shown that the ion implantation results in a considerable hardening of the entire thickness of the implanted layer in the both grain types. The grain size has, however, a different effect on the yield stress. So, both before and after the ion implantation, the increase of the grain size leads to the decrease of the alloy hardening. Thus, hardening in ultra-fine and fine grain alloys increased by four times, while in polycrystalline alloy it increased by over six times.

  1. 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.

  2. A comparative evaluation of laser and GTA welds in a high-strength titanium alloy -- Ti-6-22-22S

    SciTech Connect

    Baeslack, W.A. III; Hurley, J.; Paskell, T.

    1994-12-31

    Titanium alloy Ti-6Al-2Sn-2Zr-2Mo-2Cr-025Si (hereafter designated Ti-6-22-22S)is an alpha-beta titanium alloy developed for deep hardenability, high strength, intermediate temperature creep resistance, and moderate toughness. As a potential structural material for next-generation aircraft and aerospace systems, the weldability of Ti-6-22-22S has recently become a subject of increasing importance and concern. In the welding of titanium sheet, achieving satisfactory ductility is the principal limitation to alloy weldability, with poor ductility promoted by a coarse beta grain structure in the weld fusion and near-heat-affected zones. Square-butt welds were produced in 1.6 mm thick Ti-6-22-22S sheet using automatic GTA and CO{sub 2} laser welding systems. Microstructure analysis and DPH hardness traverses were performed on mounted. polished and etched specimens. Three-point bend and tensile tests were performed on transverse-weld and longitudinal-weld oriented specimens. Microstructure analysis of the laser welds revealed a fine, columnar fusion zone beta grain macrostructure and a fully-martensitic transformed-beta microstructure. Consistent with the microstructural similarities, fusion zone hardnesses of the laser welds were comparable (385 and 390 DPG, respectively) and greater than that of the base metal (330 DPH). In general, laser welds did not exhibit markedly superior ductilities relative to the GTAW, which was attributed to differences in the nature of the intragranular transformed-beta microstructures, being coarser and softer for the GTAW, the response of these as-welded microstructures to heat treatment, and interactions between the transformed-beta microstructure and the beta grain macrostructure.

  3. Probing liquation cracking and solidification through modeling of momentum, heat, and solute transport during welding of aluminum alloys

    NASA Astrophysics Data System (ADS)

    Mishra, S.; Chakraborty, S.; DebRoy, T.

    2005-05-01

    A transport phenomena-based mathematical model is developed to understand liquation cracking in weldments during fusion welding. Equations of conservation of mass, momentum, heat, and solute transport are numerically solved considering nonequilibrium solidification and filler metal addition to determine the solid and liquid phase fractions in the solidifying region and the solute distribution in the weld pool. An effective partition coefficient that considers the local interface velocity and the undercooling is used to simulate solidification during welding. The calculations show that convection plays a dominant role in the solute transport inside the weld pool. The predicted weld-metal solute content agreed well with the independent experimental observations. The liquation cracking susceptibility in Al-Cu alloy weldments could be reliably predicted by the model based on the computed solidifying weld-metal composition and solid fraction considering nonequilibrium solidification.

  4. Microwave Induced Welding of Carbon Nanotube-Thermoplastic Interfaces for Enhanced Mechanical Strength of 3D Printed Parts

    NASA Astrophysics Data System (ADS)

    Sweeney, Charles; Lackey, Blake; Saed, Mohammad; Green, Micah

    Three-dimensional (3D) printed parts produced by fused-filament fabrication of a thermoplastic polymer have become increasingly popular at both the commercial and consumer level. The mechanical integrity of these rapid-prototyped parts however, is severely limited by the interfillament bond strength between adjacent extruded layers. In this report we propose for the first time a method for welding thermoplastic interfaces of 3D printed parts using the extreme heating response of carbon nanotubes (CNTs) to microwave energy. To achieve this, we developed a coaxial printer filament with a pure polylactide (PLA) core and a CNT composite sheath. This produces parts with a thin electrically percolating network of CNTs at the interfaces between adjacent extruded layers. These interfaces are then welded together upon microwave irradiation at 2.45GHz. Our patent-pending method has been shown to increase the tensile toughness by 1000% and tensile strength by 35%. We investigated the dielectric properties of the PLA/CNT composites at microwave frequencies and performed in-situ microwave thermometry using a forward-looking infrared (FLIR) camera to characterize the heating response of the PLA/CNT composites upon microwave irradiation.

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

    SciTech Connect

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

    2015-03-15

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

  6. Investigation of the Compressive Strength and Creep Lifetime of 2024-T3 Aluminum-Alloy Plates at Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Mathauser, Eldon E; Deveikis, William D

    1957-01-01

    The results of elevated-temperature compressive strength and creep tests of 2024-t3 (formerly 24s-t3) aluminum alloy plates supported in v-grooves are presented. The strength-test results indicate that a relation previously developed for predicting plate compressive strength for plates of all materials at room temperature is also satisfactory for determining elevated-temperature strength. Creep-lifetime results are presented for plates in the form of master creep-lifetime curves by using a time-temperature parameter that is convenient for summarizing tensile creep-rupture data. A comparison is made between tensile and compressive creep lifetime for the plates and a method that made use of isochronous stress-strain curves for predicting plate-creep failure stresses is investigated.

  7. On the determination of the origin of linear anomaly in the macrostructure of VPPA welded 2219-T87 aluminum alloy

    NASA Technical Reports Server (NTRS)

    Jemian, W. A.

    1986-01-01

    The objective was to determine the cause and significance of the weld radiograph enigma, which is a linear anomaly in the features of the X-ray film. By observing features on available radiographs and in studying published reports of similar features it was possible to conclude that there are many manifestations of the enigma, and that they are all specific features of fine structure in radiographs due to natural processes connected with welding and to specific X-ray absorption and diffraction phenomena. These processes include the thermal distribution and liquid metal flow in welding, the development of microstructure, morpohology, second phase particles and porosity due to the solidification process and to the pattern of residual stresses after the weld metal has cooled to the ambient temperature. Microdensitometer traces were made across weld radiographs of standard and enigmatic types. Similar patterns were produced by computer simulation. These show that the enigma is a relatively low contrast feature compared to real weld defects, such as undercuts or centerline cracks. The enigma can be distinguished from weld defects by these microdensitometer traces. The enigma effect on weld properties is not known but is expected to be minor.

  8. Welding of High-Strength Steels for Aircraft and Missile Applications

    DTIC Science & Technology

    1959-10-12

    investigations have been limited to unwelded ma- terial. Conventional impact testing (such as the V-notch Charpy test) of weld metals also has been limited...is X200 and 300M ... ..................... . .. . . . . . ..... . 16 HOT-WORK DIE STEELS . . . . . . . . . . . . . .............. 17 Peerless...metal. A survey of the procedures currently being used is presented. Low-Alloy Martensitic Steels AISI 4340, AMS 6434, XZOO, 300M , and 17-Z2AS all are

  9. Research on High-Strength Steels with an Improved Resistance against Weld Cracking.

    DTIC Science & Technology

    1984-06-01

    sticks are crayons which melt at a predetermined temperature, and can be applied to a piece of steel in order to monitor its temperature as it is...them from getting too close to those areas which might be melted by the actual welding process. As described previously temperature indicating crayons ...pure sample of metal will melt and solidify at a single temperature for any uniform set of testing conditions. When alloying elements are added to the

  10. Onset of the initial instability during the solidification of welding pool of aluminum alloy under transient conditions

    NASA Astrophysics Data System (ADS)

    Zheng, Wenjian; Dong, Zhibo; Wei, Yanhong; Song, Kuijing

    2014-09-01

    Onset of initial morphological instability is predicted by using a new analytic model and quantitative phase field model during the solidification of the welding pool of Al-Cu alloy under transient conditions. In the linear growth stage of the welding pool, the dynamic evolution of the interface instability is analyzed, and the interface behaviors under infinitesimal fluctuations are also investigated. The results show that the mean wavelength at the crossover time evaluated from this analytic model is in good agreement with those obtained by the quantitative phase field simulations and the experiments. The linear growth stage takes up quite a long time of the whole solidification of welding pool and thus it should be primarily considered in investigating the transient growth of welding pool. This study establishes a valid numerical framework for studying the dendrite growth under transient solidification conditions and provides a new approach for studying the transient solidification of welding pool.

  11. X-Ray and Neutron Diffraction Measurements of Dislocation Density and Subgrain Size in a Friction-Stir-Welded Aluminum Alloy

    SciTech Connect

    Woo, Wan Chuck; Ungar, Prof Tomas; Feng, Zhili; Kenik, Edward A; Clausen, B

    2009-01-01

    The dislocation density and subgrain size were determined in the base material and friction-stir welds of 6061-T6 aluminum alloy. High-resolution X-ray diffraction measurement was performed in the base material. The result of the line profile analysis of the X-ray diffraction peak shows that the dislocation density is about 4.5 x 10{sup 14} m{sup -2} and the subgrain size is about 200 nm. Meanwhile, neutron diffraction measurements have been performed to observe the diffraction peaks during friction-stir welding (FSW). The deep penetration capability of the neutron enables us to measure the peaks from the midplane of the Al plate underneath the tool shoulder of the friction-stir welds. The peak broadening analysis result using the Williamson-Hall method shows the dislocation density of about 3.2 x 10{sup 15} m{sup -2} and subgrain size of about 160 nm. The significant increase of the dislocation density is likely due to the severe plastic deformation during FSW. This study provides an insight into understanding the transient behavior of the microstructure under severe thermomechanical deformation.

  12. Welding-Induced Microstructure Evolution of a Cu-Bearing High-Strength Blast-Resistant Steel

    NASA Astrophysics Data System (ADS)

    Caron, Jeremy L.; Babu, Sudarsanam Suresh; Lippold, John C.

    2011-12-01

    A new high strength, high toughness steel containing Cu for precipitation strengthening was recently developed for naval, blast-resistant structural applications. This steel, known as BlastAlloy160 (BA-160), is of nominal composition Fe-0.05C-3.65Cu-6.5Ni-1.84Cr-0.6Mo-0.1V (wt pct). The evident solidification substructure of an autogenous gas tungsten arc (GTA) weld suggested fcc austenite as the primary solidification phase. The heat-affected zone (HAZ) hardness ranged from a minimum of 353 HV in the coarse-grained HAZ (CGHAZ) to a maximum of 448 HV in the intercritical HAZ (ICHAZ). After postweld heat treatment (PWHT) of the spot weld, hardness increases were observed in the fusion zone (FZ), CGHAZ, and fine-grained HAZ (FGHAZ) regions. Phase transformation and metallographic analyses of simulated single-pass HAZ regions revealed lath martensite to be the only austenitic transformation product in the HAZ. Single-pass HAZ simulations revealed a similar hardness profile for low heat-input (LHI) and high heat-input (HHI) conditions, with higher hardness values being measured for the LHI samples. The measured hardness values were in good agreement with those from the GTA weld. Single-pass HAZ regions exhibited higher Charpy V-notch impact toughness than the BM at both test temperatures of 293 K and 223 K (20 °C and -50 °C). Hardness increases were observed for multipass HAZ simulations employing an initial CGHAZ simulation.

  13. Friction plug welding

    NASA Technical Reports Server (NTRS)

    Takeshita, Riki (Inventor); Hibbard, Terry L. (Inventor)

    2001-01-01

    Friction plug welding (FPW) usage is advantageous for friction stir welding (FSW) hole close-outs and weld repairs in 2195 Al--Cu--Li fusion or friction stir welds. Current fusion welding methods of Al--Cu--Li have produced welds containing varied defects. These areas are found by non-destructive examination both after welding and after proof testing. Current techniques for repairing typically small (<0.25) defects weaken the weldment, rely heavily on welders' skill, and are costly. Friction plug welding repairs increase strength, ductility and resistance to cracking over initial weld quality, without requiring much time or operator skill. Friction plug welding while pulling the plug is advantageous because all hardware for performing the weld can be placed on one side of the workpiece.

  14. Combined effects of weld-induced residual stresses and flaws on the fracture strength of Ti-5Al-2.5Sn

    NASA Technical Reports Server (NTRS)

    Hall, L. R.

    1973-01-01

    The combined effects of weld-induced residual stresses and flaws on fracture strength were experimentally evaluated by testing Ti-5Al-2.5Sn surface flawed specimens at -320F (-195C) in liquid nitrogen. Flaws were located in weld metal with crack planes either parallel to or perpendicular to gas tungsten arc weld centerlines, and in base metal with the crack plane perpendicular to the rolling direction. Tests were conducted using two different flaw sizes to effect fracture stresses at two different levels including one level either at or near, and one level well below the tensile yield strength. Three different residual stress levels were generated, measured, and tested. Results were evaluated using modified linear elastic fracture mechanics theory.

  15. Experimental comparison of the MIG, friction stir welding, cold metal transfer and hybrid laser-MIG processes for AA 6005-T6 aluminium alloy

    NASA Astrophysics Data System (ADS)

    Caruso, Serafino; Sgambitterra, Emanuele; Rinaldi, Sergio; Gallone, Antonello; Viscido, Lucio; Filice, Luigino; Umbrello, Domenico

    2016-10-01

    In this study, the mechanical properties of welded joints of AA 6005-T6 aluminum alloy obtained with hybrid laser-MIG and cold metal transfer (CMT) welding were analyzed. The performance of hybrid laser-MIG and CMT welded joints were identified using tensile, bending, shear and fatigue life tests. Taking into account the process conditions and requirements, hybrid laser-MIG and CMT welding processes were compared with friction stir welding (FSW) and conventional metal inert gas (MIG) welding processes, shown in a previous work, to understand the advantages and disadvantages of the processes for welding applications of studied Al alloy. Better tensile, bending and shear strength and fatigue life behavior were obtained with hybrid laser-MIG and FSW welded joints compared with conventional MIG processes.

  16. Welding in airplane construction

    NASA Technical Reports Server (NTRS)

    Rechtlich, A; Schrenk, M

    1928-01-01

    The present article attempts to explain the principles for the production of a perfect weld and to throw light on the unexplained problems. Moreover, it is intended to elucidate the possibilities of testing the strength and reliability of welded parts.

  17. Design Optimization and Fatigue Analysis of Laser Stake Welded Connections

    DTIC Science & Technology

    2008-06-01

    DelI Research Corporation, Bethlehem, PA. m Irwin G.R., 1956, Onset of Fast Crack Propagation in High Strength Steel and Aluminum Alloys , Sagamore...study on a particular hybrid joint ideal for laser welding. In order to improve the strength and mechanical interlock properties of embedded hybrid joints... properties of the steel and composite attributed to the progressively widening hole pattern in the steel. Additionally, I the holes provided significant

  18. Effect of surface oxidation layer on tensile strength of Cu-Ni alloy in friction stir welding

    NASA Astrophysics Data System (ADS)

    Yoon, Taejin; Park, Sangwon; Chung, Sungwook; Noh, Joongsuk; Kim, Kwangho; Kang, Chungyun

    2016-05-01

    Friction stir welding (FSW) of thick Cu-Ni plate was successfully completed. The fracture position after tensile testing was located at the weld nugget zone (WNZ), where surface oxidation occurred. The oxidation morphologies on the surface of the base metal were analyzed by SEM, EPMA and XRD, with the oxide layer being obtained by simple and useful way to analyze the oxide products, namely, collecting oxide powders after immersing of the oxidized specimen into HNO3 solution. The results highlighted that an oxide layer of 30 μm thickness consists of a mixture of two phases, Cu2O and NiO, on the surface of the base metal. After FSW, the thickness of the oxide layer on the surface was decreased to approximately 5 μm, and broken oxide particles, which is NiO, penetrated into the WNZ by the rotating tool. NiO was preferentially formed at the surface after FSW because it has a lower Gibbs free energy value at 950 °C, which is the peak temperature measured during FSW. Oxide layer of Cu-Ni plate was clearly only removed by mechanical method grinding with 1200-grit SiC paper. The removal of oxide layer results in improved mechanical strength.

  19. Effect of Rotational Speed on Microstructure and Mechanical Properties of Refill Friction Stir Spot Welded 2024 Al Alloy

    NASA Astrophysics Data System (ADS)

    Li, Zhengwei; Gao, Shuangsheng; Ji, Shude; Yue, Yumei; Chai, Peng

    2016-04-01

    Refill friction stir spot welding (RFSSW) was successfully used to weld alclad 2024 aluminum alloy with different thicknesses. Effects of tool rotational speed on the weld formation, microstructure, and mechanical properties of the RFSSW welds were mainly discussed. Results show that keyhole is successfully refilled and welding defects such as flash, annular groove, and material adhesion can be observed. A bright contrast bonding ligament is found embedded in the weld and it is thicker in the center. Defects of hook, void, lack of mixing, and incomplete refilling can be found at the thermo-mechanically affected zone/stir zone (TMAZ/SZ) interface, which can be attributed to weak metallurgical bonding effect. With increasing the tool rotational speed, thickness of the bonding ligament decreases, grains in the SZ coarsen, hardness of the SZ decreases, and lap shear load of the welds decreases. When changing the rotating speed, impact strength shows rather complicated variation trend.

  20. On the Microstructural and Mechanical Characterization of Hybrid Laser-Welded Al-Zn-Mg-Cu Alloys

    NASA Astrophysics Data System (ADS)

    Wu, S. C.; Hu, Y. N.; Song, X. P.; Xue, Y. L.; Peng, J. F.

    2015-04-01

    Butt-welded 2-mm-thick high-strength aluminum alloys have been welded using a hybrid fiber laser and pulsed arc heat source system with the ER5356 filler. The microstructure, size of precipitates, texture, grain size and shape, change of strengthening elements, mechanical properties, and surface-based fatigue fracture characteristics of hybrid-welded joints were investigated in detail. The results indicate that the hybrid welds and the unaffected base materials have the lowest and largest hardness values, respectively, compared with the heat-affected zone. It is resonably believed that the elemental loss, coarse grains, and changed precipitates synthetically produce the low hardness and tensile strengths of hybrid welds. Meanwhile, the weaker grain boundary inside welds appears to initiate a microcrack. Besides, there exists an interaction of fatigue cracks and gas pores and microstructures.