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Sample records for alloys laser welded

  1. Nd:YAG laser welding aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. Underwater laser beam welding of Alloy 690

    International Nuclear Information System (INIS)

    Hino, Takehisa; Tamura, Masataka; Kono, Wataru; Kawano, Shohei; Yoda, Masaki

    2009-01-01

    Stress Corrosion Clacking (SCC) has been reported at Alloy 600 welds between nozzles and safe-end in Pressurized Water Reactor (PWR) plant. Alloy 690, which has higher chromium content than Alloy 600, has been applied for cladding on Alloy 600 welds for repairing damaged SCC area. Toshiba has developed Underwater Laser Beam Welding technique. This method can be conducted without draining, so that the repairing period and the radiation exposure during the repair can be dramatically decreased. In some old PWRs, high-sulfur stainless steel is used as the materials for this section. It has a high susceptibility of weld cracks. Therefore, the optimum welding condition of Alloy 690 on the high-sulfur stainless steel was investigated with our Underwater Laser Beam Welding unit. Good cladding layer, without any crack, porosity or lack of fusion, could be obtained. (author)

  3. Laser assisted arc welding for aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Fuerschbach, P.W.

    2000-01-01

    Experiments have been performed using a coaxial end-effector to combine a focused laser beam and a plasma arc. The device employs a hollow tungsten electrode, a focusing lens, and conventional plasma arc torch nozzles to co-locate the focused beam and arc on the workpiece. Plasma arc nozzles were selected to protect the electrode from laser generated metal vapor. The project goal is to develop an improved fusion welding process that exhibits both absorption robustness and deep penetration for small scale (<1.5 mm thickness) applications. On aluminum alloys 6061 and 6111, the hybrid process has been shown to eliminate hot cracking in the fusion zone. Fusion zone dimensions for both stainless steel and aluminum were found to be wider than characteristic laser welds, and deeper than characteristic plasma arc welds.

  4. Development of laser welding techniques for vanadium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Strain, R.V.; Leong, K.H.; Smith, D.L.

    1996-04-01

    Laser welding is potentially advantageous because of its flexibility and the reduced amount of material affected by the weld. Lasers do not require a vacuum (as do electron beam welders) and the welds they produce high depth-to-width ratios. Scoping with a small pulsed 50 J YAG laser indicated that lasers could produce successful welds in vanadium alloy (V-5%Cr-5%Ti) sheet (1 mm thick) when the fusion zone was isolated from air. The pulsed laser required an isolating chamber filled with inert gas to produce welds that did not contain cracks and showed only minor hardness increases. Following the initial scoping tests, a series of tests were preformed with a 6 kW continuous CO{sub 2} laser. Successful bead-on-plate welds were made on V-4%Cr-4%Ti and V-5%Cr-5%Ti alloys to depths of about 4 mm with this laser.

  5. Laser welding of 6xxx series aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zervaki, A.D.; Haidenmenopoulos, G.N. [Thessaly Univ., Volos (Greece). Dept. of Mechanical and Industrial Engineering

    2000-07-01

    Considerable interest has emerged recently in applying laser welding to aluminum alloys especially in the aerospace, automotive and shipbuilding industries. in the present work experimental results regarding CO{sub 2} laser welding of aluminum alloys 6063, 6061 and 6013 of 1.8 mm thickness are being presented. CO{sub 2} lasers with 1.5, 3 and 5 kW output power were employed. The effect of laser power, beam travel speed, focal depth shielding gas, surface preparation on weld geometrical characteristics (depth of penetration and width of HAZ) as well as weld quality (microhardness and internal defects) is discussed. Optimum welding conditions were determined for the alloy 6063 where for certain values of heat input weld defects such as pores, hot cracking and partial penetration were eliminated. Modeling work is underway to predict the microstructural evolution and resulting hardness profiles in the HAZ. (orig.)

  6. Laser welding of Ti-Ni type shape memory alloy

    International Nuclear Information System (INIS)

    Hirose, Akio; Araki, Takao; Uchihara, Masato; Honda, Keizoh; Kondoh, Mitsuaki.

    1990-01-01

    The present study was undertaken to apply the laser welding to the joining of a shape memory alloy. Butt welding of a Ti-Ni type shape memory alloy was performed using 10 kW CO 2 laser. The laser welded specimens showed successfully the shape memory effect and super elasticity. These properties were approximately identical with those of the base metal. The change in super elasticity of the welded specimen during tension cycling was investigated. Significant changes in stress-strain curves and residual strain were not observed in the laser welded specimen after the 50-time cyclic test. The weld metal exhibited the celler dendrite. It was revealed by electron diffraction analysis that the phase of the weld metal was the TiNi phase of B2 structure which is the same as the parent phase of base metal and oxide inclusions crystallized at the dendrite boundary. However, oxygen contamination in the weld metal by laser welding did not occur because there was almost no difference in oxygen content between the base metal and the weld metal. The transformation temperatures of the weld metal were almost the same as those of the base metal. From these results, laser welding is applicable to the joining of the Ti-Ni type shape memory alloy. As the application of laser welding to new shape memory devices, the multiplex shape memory device of welded Ti-50.5 at % Ni and Ti-51.0 at % Ni was produced. The device showed two-stage shape memory effects due to the difference in transformation temperature between the two shape memory alloys. (author)

  7. Cracking susceptibility of aluminum alloys during laser welding

    Directory of Open Access Journals (Sweden)

    Lara Abbaschian

    2003-06-01

    Full Text Available The influence of laser parameters in welding aluminum alloys was studied in order to reduce hot cracking. The extension of cracks at the welding surface was used as a cracking susceptibility (CS index. It has been shown that the CS changes with changing welding velocity for binary Al-Cu alloys. In general, the CS index increased until a maximum velocity and then dropped to zero, generating a typical lambda-curve. This curve is due to two different mechanisms: 1 the refinement of porosities with increasing velocity and 2 the changes in the liquid fraction due to decreasing microsegregation with increasing velocities.

  8. Laser Welding of BTi-6431S High Temperature Titanium Alloy

    Directory of Open Access Journals (Sweden)

    Zhi Zeng

    2017-11-01

    Full Text Available A new type of high temperature titanium alloy, BTi-6431S, has recently become the focus of attention as a potential material for aircraft engine applications, which could be used up to 700 °C. Pulsed laser welding was used to butt join the BTi-6431S titanium alloy in order to understand the feasibility of using fusion-based welding techniques on this material. The effect of laser energy on the microstructure and mechanical properties of the joints was investigated. The microstructural features of the joints were characterized by means of microscopy and X-ray diffraction. Tensile testing was conducted at both room temperature and high temperature to simulate potential service conditions. The results show that the microstructure of the laser welded joints consists of primary α phase and needle α’ phase, while the microstructure of the heat affected zone consists of α, β, and needle α’ phases. The tensile strength of the welded joints at room temperature was similar to that of the base material, despite a reduction in the maximum elongation was observed. This was related to the unfavorable microstructure in the welded joints. Nonetheless, based on these results, it is suggested that laser welding is a promising joining technique for the new BTi-6431S titanium alloy for aerospace applications.

  9. Laser beam welding and friction stir welding of 6013-T6 aluminium alloy sheet

    International Nuclear Information System (INIS)

    Braun, R.; Dalle Donne, C.; Staniek, G.

    2000-01-01

    Butt welds of 1.6 mm thick 6013-T6 sheet were produced using laser beam welding and friction stir welding processes. Employing the former joining technique, filler powders of the alloys Al-5%Mg and Al-12%Si were used. Microstructure, hardness profiles, tensile properties and the corrosion behaviour of the welds in the as-welded condition were investigated. The hardness in the weld zone was lower compared to that of the base material in the peak-aged temper. Hardness minima were measured in the fusion zone and in the thermomechanically affected zone for laser beam welded and friction stir welded joints, respectively. Metallographic and fractographic examinations revealed pores in the fusion zone of the laser beam welds. Porosity was higher in welds made using the filler alloy Al-5%Mg than using the filler metal Al-12%Si. Transmission electron microscopy indicated that the β '' (Mg 2 Si) hardening precipitates were dissolved in the weld zone due to the heat input of the joining processes. Joint efficiencies achieved for laser beam welds depended upon the filler powders, being about 60 and 80% using the alloys Al-5%Mg and Al-12%Si, respectively. Strength of the friction stir weld approached over 80% of the ultimate tensile strength of the 6013-T6 base material. Fracture occurred in the region of hardness minima unless defects in the weld zone led to premature failure. The heat input during welding did not cause a degradation of the corrosion behaviour of the welds, as found in continuous immersion tests in an aqueous chloride-peroxide solution. In contrast to the 6013-T6 parent material, the weld zone was not sensitive to intergranular corrosion. Alternate immersion tests in 3.5% NaCl solution indicated high stress corrosion cracking resistance of the joints. For laser beam welded sheet, the weld zone of alternately immersed specimens suffered severe degradation by pitting and intergranular corrosion, which may be associated with galvanic coupling of filler metal and

  10. Analysis and Comparison of Friction Stir Welding and Laser Assisted Friction Stir Welding of Aluminum Alloy.

    Science.gov (United States)

    Campanelli, Sabina Luisa; Casalino, Giuseppe; Casavola, Caterina; Moramarco, Vincenzo

    2013-12-18

    Friction Stir Welding (FSW) is a solid-state joining process; i.e. , no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. Laser Assisted Friction Stir Welding (LAFSW) is a combination in which the FSW is the dominant welding process and the laser pre-heats the weld. In this work FSW and LAFSW tests were conducted on 6 mm thick 5754H111 aluminum alloy plates in butt joint configuration. LAFSW is studied firstly to demonstrate the weldability of aluminum alloy using that technique. Secondly, process parameters, such as laser power and temperature gradient are investigated in order to evaluate changes in microstructure, micro-hardness, residual stress, and tensile properties. Once the possibility to achieve sound weld using LAFSW is demonstrated, it will be possible to explore the benefits for tool wear, higher welding speeds, and lower clamping force.

  11. Analysis and Comparison of Friction Stir Welding and Laser Assisted Friction Stir Welding of Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Sabina Luisa Campanelli

    2013-12-01

    Full Text Available Friction Stir Welding (FSW is a solid-state joining process; i.e., no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. Laser Assisted Friction Stir Welding (LAFSW is a combination in which the FSW is the dominant welding process and the laser pre-heats the weld. In this work FSW and LAFSW tests were conducted on 6 mm thick 5754H111 aluminum alloy plates in butt joint configuration. LAFSW is studied firstly to demonstrate the weldability of aluminum alloy using that technique. Secondly, process parameters, such as laser power and temperature gradient are investigated in order to evaluate changes in microstructure, micro-hardness, residual stress, and tensile properties. Once the possibility to achieve sound weld using LAFSW is demonstrated, it will be possible to explore the benefits for tool wear, higher welding speeds, and lower clamping force.

  12. Fiber Lasers Application for Welding of Titanium Alloys With 16 mm Thickness

    Science.gov (United States)

    Evtihiev, N. N.; Grezev, N. V.; Markushov, Y. V.; Murzakov, M. A.

    2016-09-01

    This article illustrates the use of fiber laser welding of a titanium alloy with 16 mm thickness. The basic advantages of the laser welding process over the traditional methods of arc welding of titanium are demonstrated. Destructive testing of welds was performed to confirm the quality of the welding. The results of the static tensile tests, static bending and toughness at room temperature are presented. All tests confirmed the high quality of the welded joint.

  13. Tensile strength of laser welded cobalt-chromium alloy with and without an argon atmosphere.

    Science.gov (United States)

    Tartari, Anna; Clark, Robert K F; Juszczyk, Andrzej S; Radford, David R

    2010-06-01

    The tensile strength and depth of weld of two cobalt chromium alloys before and after laser welding with and without an argon gas atmosphere were investigated. Using two cobalt chromium alloys, rod shaped specimens (5 cm x 1.5 mm) were cast. Specimens were sand blasted, sectioned and welded with a pulsed Nd: YAG laser welding machine and tested in tension using an Instron universal testing machine. A statistically significant difference in tensile strength was observed between the two alloys. The tensile strength of specimens following laser welding was significantly less than the unwelded controls. Scanning electron microscopy showed that the micro-structure of the cast alloy was altered in the region of the weld. No statistically significant difference was found between specimens welded with or without an argon atmosphere.

  14. Studies on post weld heat treatment of dissimilar aluminum alloys by laser beam welding technique

    Science.gov (United States)

    Srinivas, B.; Krishna, N. Murali; Cheepu, Muralimohan; Sivaprasad, K.; Muthupandi, V.

    2018-03-01

    The present study mainly focuses on post weld heat treatment (PWHT) of AA5083 and AA6061 alloys by joining these using laser beam welding at three different laser power and two different beam spot sizes and three different welding speeds. Effects of these parameters on microstructural and mechanical properties like hardness, tensile strength were studied at PWHT condition and significant changes had been observed. The PWHT used was artificial aging technique. The microstructural observations revealed that there was a appreciable changes were taken place in the grain size. The microhardness observations proven that the change in the hardness profile in AA6061 was appreciable than in the AA5083. The tensile strength of 246 MPa was recorded as highest. The fractured surfaces observed are predominantly ductile in nature.

  15. Weld Bead Size, Microstructure and Corrosion Behavior of Zirconium Alloys Joints Welded by Pulsed Laser Spot Welding

    Science.gov (United States)

    Cai, Chuang; Li, Liqun; Tao, Wang; Peng, Genchen; Wang, Xian

    2016-09-01

    Pulsed laser spot welding of intersection points of zirconium alloys straps was performed. Weld bead size, microstructure and the corrosion behavior of weld bead were investigated. With the increasing laser peak power or number of shots, the weld width of the beads increased, the protrusion decreased and the dimple increased with further increase in heat input. The fusion zone consisted of a mixture of αZr and residual βZr phases. After annealing treatment, βNb and Zr(Fe, Nb)2 second phase particles were precipitated inter- and intragranular of αZr grains adequately. The oxide thickness of annealed weld bead was about 3.90 μm, decreased by about 18.1% relative to the 4.76 μm of as-welded specimen corroded at 400 °C and 10.3 MPa for 20 days. The corrosion resistance of annealed specimen was better than that of as-welded specimen, since the second phase particles exerted better corrosion resistance, and the content of Nb in βZr and the fraction of βZr decreased after the annealing treatment.

  16. Pore formation during C.W.Nd: YAG laser welding of aluminum alloys for automotive applications

    International Nuclear Information System (INIS)

    Pastor, M.; Zhao, H.; DebRoy, T.

    2000-01-01

    Pore formation is an important concern in laser welding of automotive aluminum alloys. This paper investigates the influence of the laser beam defocusing on pore formation during continuous wave Nd:YAG laser welding of aluminum automotive alloys 5182 and 5754. It was found that the instability of the keyhole during welding was a dominant cause of pore formation while hydrogen rejection played an insignificant role. The defocusing of the laser beam greatly affected the stability of the keyhole. Finally, the mechanism of the collapse of the keyhole and pore formation is proposed. (Author) 45 refs

  17. Experimental Investigation on Electric Current-Aided Laser Stake Welding of Aluminum Alloy T-Joints

    Directory of Open Access Journals (Sweden)

    Xinge Zhang

    2017-11-01

    Full Text Available In the present study, aluminum alloy T-joints were welded using the laser stake-welding process. In order to improve the welding quality of the T-joints, an external electric current was used to aid the laser stake-welding process. The effects of the process parameters on the weld morphology, mechanical properties, and microstructure of the welded joints were analyzed and discussed in detail. The results indicate that the aided electric current should be no greater than a certain maximum value. Upon increasing the aided electric current, the weld width at the skin and stringer faying surface obviously increased, but there was an insignificant change in the penetration depth. Furthermore, the electric current and pressing force should be chosen to produce an expected weld width at the faying surface, whereas the laser power and welding speed should be primarily considered to obtain an optimal penetration depth. The tensile shear specimens failed across the faying surface or failed in the weld zone of the skin. The specimens that failed in the weld of the skin could resist a higher tensile shear load compared with specimens that failed across the faying surface. The microstructural observations and microhardness results demonstrated that the tensile shear load capacity of the aluminum alloy welded T-joint was mainly determined by the weld width at the faying surface.

  18. Research on the microstructure and properties of laser-MIG hybrid welded joint of Invar alloy

    Science.gov (United States)

    Zhan, Xiaohong; Zhang, Dan; Wei, Yanhong; Wang, Yuhua

    2017-12-01

    In order to solve the problem of large deformation, low production efficiency and high tendency of hot cracking in welding 19.05 mm thick plates of Fe36Ni Invar alloy, laser-MIG hybrid multi-layer welding technique (LMHMW) has been developed. To investigate the influence of different welding parameters on the joint properties, optical microscope observation, SEM, EDS and microhardness measurement were conducted. Experimental results illustrated that different matching of welding parameters significantly affected the depth-to-width ratio, formation of defects and HAZ width. Besides, weld zone were consisted of two regions according to the different grain shape. The region near center of weld seam (region 1) was columnar dendrite induced by laser, while the region far away from weld seam center (region 2) was cellular dendrite which was mainly caused by MIG arc. The peak value of microhardness appeared at the center of weld seam since the grains in region 1 were relatively fine, and the lowest hardness value was obtained in HAZ. In addition, results showed that the sheets can be welded at optimum process parameters, with few defects such as, surface oxidation, porosity, cracks and lack of penetration in the welding seam: laser power of backing weld P = 5500 W, welding current I = 240 A, welding speed v = 1 m/min. laser power of filling weld P = 2000 W, welding current I = 220 A, welding speed v = 0.35 m/min. laser power of cosmetic weld P = 2000 W, welding current I = 300 A, welding speed v = 0.35 m/min.

  19. The characteristics of laser welded magnesium alloy using silver nanoparticles as insert material

    International Nuclear Information System (INIS)

    Ishak, M.; Maekawa, K.; Yamasaki, K.

    2012-01-01

    Highlights: ► Ag nanoparticles are used as insert material for welding Mg alloy with laser. ► We examine the microstructure and mechanical properties of welded Mg alloys. ► Nananoparticle promote grain refinement to the weld structure. ► Finer nanoparticle produces high weld efficiency and mechanical properties. - Abstract: This paper describes the characteristics of the laser welding of thin-sheet magnesium alloys using silver (Ag) nanoparticles as an insert material. The experiment was conducted using nanoparticles with 5 nm and 100 nm diameters that were welded with a Nd:YAG laser. The microstructure and mechanical properties of the specimens welded using inserts with different sizes of nanoparticles and without an insert material, were examined. Electron probe micro-analyzer (EPMA) analysis was conducted to confirm the existence of Ag in the welded area. The introduction of the Ag nanoparticle insert promoted large area of fine grain and broadened the acceptable range of scanning speed parameters compared to welds without an insert. Welds with 5 nm nanoparticles yielded the highest fracture load of up to 818 N while the lowest fracture load was found for weld specimens with 100 nm nanoparticles. This lower fracture load was due to larger voids and a smaller throat length, which contributed to a lower fracture load when using larger nanoparticles.

  20. Effect of Travel Speed and Beam Focus on Porosity in Alloy 690 Laser Welds

    Science.gov (United States)

    Tucker, Julie D.; Nolan, Terrance K.; Martin, Anthony J.; Young, George A.

    2012-12-01

    Advances in laser welding technology, including fiber optic delivery and high power density, are increasing the applicability of this joining technique. The inherent benefits of laser welding include small heat-affected zones, minimal distortion, and limited susceptibility to cracking. These advantages are of special interest to next-generation nuclear power systems where welding solute-rich alloys is expected to increase. Alloy 690 (A690) is an advanced corrosion-resistant structural material used in many replacement components and in construction of new commercial power plants. However, the application of A690 is hindered by its difficult weldability using conventional arc welding, and laser welding is a promising alternate. This work studies the effects of travel speed and beam focus on porosity formation in partial penetration, autogenous A690 laser welds. Porosity has been characterized by light optical microscopy and x-ray computed tomography to quantify its percent volume in the welds. This work describes the tradeoff between weld penetration and defect density as a function of beam defocus and travel speed. Additionally, the role of shield gas in porosity formation is discussed to provide a mitigation strategy for A690 laser welding. A process map is provided that shows the optimal combinations of travel speed and beam defocus to minimize porosity and maximize weld penetration at a laser power of 4 kW.

  1. Effect of fiber laser parameters on laser welded AZ31B Magnesium alloys

    Directory of Open Access Journals (Sweden)

    Mat Salleh Naqiuddin

    2017-01-01

    Full Text Available Recently, the usage of Magnesium (Mg alloys has been hugely applied in the industrial application such as in automotive, marine, and electronic due to its advantages of recyclability and lightweight. This alloys required low heat input to be weld since it is easily evaporated due to the Magnesium Oxide (MgO at the surface and it also possesses lower melting point compared to steel. Laser welding is more convenient to weld Mg alloys due to its high power and lower heat input. AZ31B was selected since it has strong mechanical properties among others Mg alloys due to the major alloying elements; Aluminium (Al and Zinc (Zn. Low power fiber laser machine with wavelength of 900 nm was used in this experiment. The intention of this work was to investigate the effect of low power fiber laser parameters and effect of shielding gas on weld penetration and microstructure. Another aim in this work was to produce the joint for this thin sheets metal. Penetration depth and microstructure evaluation were emphasized in the analysis section. Bead-on-Plate (BOP and laser lap welding was conducted on AZ31B with thicknesses of 1.0 mm and 0.6 mm for feasibility study using pulsed wave (PW mode. Defocusing features was used in order to find better focal position, which has less occurrence of evaporation (underfill. The effect of different angle of irradiation was also investigated. Two types of shielding gases, Argon (Ar and Nitrogen (N2 were used in order to study the effect of shielding gas. Lastly, the effect of pulsed energy on penetration types and depth of BOP welded samples was investigated. Focus point was found at focal length of 156 mm with 393.75 μm. For BOP experiment, higher pulsed energy used contributes to melt through defect. Meanwhile, Ns shielding gas proved to be better shielding gas in laser welding the AZ31B. Higher angle of irradiation could reduce the underfill defect. Fillet Lap joint of similar metal was successfully done where 2.0 J of

  2. Disk laser welding of metal alloys for aerospace

    OpenAIRE

    Alfieri, Vittorio

    2013-01-01

    2011 - 2012 Laser welding is the logical processing solution to accomplish different needs. Improvements at the design stage are actually aimed to remove any mechanical fastening, thus moving towards a technology which would not increase the joint thickness; moreover, a number of benefits in comparison with conventional welding methods are provided when considering laser beams, since deep penetration is achieved and the energy is effectively used where needed, thus melting t...

  3. Laser welding of SSM Cast A356 aluminium alloy processed with CSIR-Rheo technology

    CSIR Research Space (South Africa)

    Akhter, R

    2006-01-01

    Full Text Available Samples of aluminium alloy A356 were manufactured by Semi Solid Metals HPDC technology, developed recently in CSIR, Pretoria. They were butt welded in as cast conditions using as Nd: YAG laser. The best metal and weld microstructure were presented...

  4. Process Parameter Optimization for Wobbling Laser Spot Welding of Ti6Al4V Alloy

    Science.gov (United States)

    Vakili-Farahani, F.; Lungershausen, J.; Wasmer, K.

    Laser beam welding (LBW) coupled with "wobble effect" (fast oscillation of the laser beam) is very promising for high precision micro-joining industry. For this process, similarly to the conventional LBW, the laser welding process parameters play a very significant role in determining the quality of a weld joint. Consequently, four process parameters (laser power, wobble frequency, number of rotations within a single laser pulse and focused position) and 5 responses (penetration, width, heat affected zone (HAZ), area of the fusion zone, area of HAZ and hardness) were investigated for spot welding of Ti6Al4V alloy (grade 5) using a design of experiments (DoE) approach. This paper presents experimental results showing the effects of variating the considered most important process parameters on the spot weld quality of Ti6Al4V alloy. Semi-empirical mathematical models were developed to correlate laser welding parameters to each of the measured weld responses. Adequacies of the models were then examined by various methods such as ANOVA. These models not only allows a better understanding of the wobble laser welding process and predict the process performance but also determines optimal process parameters. Therefore, optimal combination of process parameters was determined considering certain quality criteria set.

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

    OpenAIRE

    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 la...

  6. Strain signatures associated to the formation of hot cracks during laser beam welding of aluminum alloys

    Science.gov (United States)

    Hagenlocher, Christian; Stritt, Peter; Weber, Rudolf; Graf, Thomas

    2018-01-01

    The local surface displacement during the laser beam welding process of MgSi alloyed aluminum sheets (AA6014) in overlap configuration was optically determined near the weld seam by means of digital correlation of images recorded with a high-speed video camera. The analysis allowed the time- and space-resolved determination of the plane strain in the immediate vicinity of the solidification zone behind the weld pool. The observations revealed characteristic signatures in the temporal evolution of the strain that are related to the formation of centerline cracks in laser beam welding.

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

    Science.gov (United States)

    Oyyaravelu, Ramachandran; Kuppan, Palaniyandi; Arivazhagan, Natarajan

    2016-05-01

    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.

  8. Microstructural examination of Zr-2.5%Nb alloy welds made by pulsed Nd:YAG laser and TIG welding technique

    International Nuclear Information System (INIS)

    Bhatt, R.B.; Varma, P.V.S.; Panakkal, J.P.; Srivastava, D.; Dey, G.K.

    2009-01-01

    The paper describes the weld microstructure of Zr-2.5%Nb alloy material. Bead on plate welds were made using pulsed Nd:YAG laser and TIG welding technique at different parameters. These welds were characterized at macro and microstructural level. Weld pools of Pulsed Laser and TIG welds were not resolved by optical microscopy. SEM too did not reveal much. Orientation imaging microscopy could reveal the presence of fine martensite. It was observed that microstructure is very sensitive to welding parameters. Microhardness studies suggested formation of martensite in the weld pool. It was also observed that laser welds had very sharp weld pool boundary as compared to TIG welds. Variation in microhardness of the weldment is seen and is influenced by overlapping of weld spots causing thermal treatment of previously deposited spots. (author)

  9. Influence of Welding Parameters on Weld Formation and Microstructure of Dual-Laser Beams Welded T-Joint of Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    Min Li

    2011-01-01

    Full Text Available This paper focused on the welding 1.8 mm thick 6061 aluminum alloy plates in T-joint form using dual lasers that introduced by a Nd: YAG laser and a CO2 laser with 4043 aluminum filler wire. The effects of welding parameters on the T-joint weld appearance, microstructure and the joint mechanical properties were studied systematically, The influence of welding parameters included the distance between two laser beams, welding speed, laser power and the laser beam offset toward the stringer. The weld appearance, microstructure, hardness of the joint were evaluated by optical microscope and micro-hardness test. A monotonic quasi-static tensile test was conducted by a self-made clamping device to obtain the tensile property of welded joints. At the optimized parameters, the welded T-joint showed good weld appearance without macro defects; the micro hardness of welds ranged from 75 to 85 HV0.3, and the tensile strength was about 254 MPa with the fracture at the heat affected zone on the stringer side.

  10. Plasma plume induced during laser welding of Magnesium alloys

    International Nuclear Information System (INIS)

    Hoffman, J.; Szymanski, Z.; Azharonok, V.

    2005-01-01

    The laser welding process is influenced by the plasma produced by laser irradiation. When the pressure of the metal vapour reaches 1 atm and the plasma temperature is 10-15 kK then the electron density is about 2-3x10 23 m -3 . Under these conditions the absorption coefficient can reach several cm -1 . This means that dense plasma over the keyhole can block the laser radiation within the path of a few millimetres. Knowledge of plasma parameters helps to control technological process. The emission spectra were registered during laser welding of magnesium alloy using of a CCD camera connected to a spectrograph of focal length 1.3 m. The entrance slit of the spectrograph was perpendicular to the metal surface, so that successive tracks of the detector recorded the radiation from the plasma slices situated at different distances (heights) from the metal surface. The space-averaged electron densities are determined from the Stark broadening of the 5528.41 A Mg I spectral line and 4481.16 A Mg II line. The Stark widths of magnesium lines are taken from other paper. It has been found that the plasma density reaches 1x10 23 m -3 . Experimentally measured line broadening is obtained from the profiles of the spectral lines integrated along the line of sight (plasma diameter) and does not correspond to the maximum plasma density. Since the plasma is non-uniform, both the electron densities and temperatures obtained from spatially integrated line profiles are lower than their maximum values in the plasma centre. This effect is much stronger for the atomic line because its intensity reaches the maximum on the plasma periphery while the maximum intensity of the ionic line originates from the plasma centre. Therefore, the absorption of the laser beam evaluated from the space-averaged plasma parameters is underestimated. To find the maximum plasma density and temperature the radial temperature distribution in the plasma plume has to be reproduced. This has been done numerically by

  11. A Comparative Study on the Laser Welding of Ti6Al4V Alloy Sheets in Flat and Horizontal Positions

    Directory of Open Access Journals (Sweden)

    Baohua Chang

    2017-04-01

    Full Text Available Laser welding has been increasingly utilized to manufacture a variety of components thanks to its high quality and speed. For components with complex shapes, the welding position needs be continuously adjusted during laser welding, which makes it necessary to know the effects of the welding position on the quality of the laser welds. In this paper, the weld quality under two (flat and horizontal welding positions were studied comparatively in the laser welding of Ti6Al4V titanium alloy, in terms of weld profiles, process porosity, and static tensile strengths. Results show that the flat welding position led to better weld profiles, less process porosity than that of the horizontal welding position, which resulted from the different actions of gravity on the molten weld metals and the different escape routes for pores under different welding positions. Although undercuts showed no association with the fracture positions and tensile strengths of the welds, too much porosity in horizontal laser welds led to significant decreases in the strengths and specific elongations of welds. Higher laser powers and travel speeds were recommended, for both flat and horizontal welding positions, to reduce weld porosity and improve mechanical properties.

  12. Laser Overlap Welding of Zinc-coated Steel on Aluminum Alloy

    Science.gov (United States)

    Kashani, Hamed Tasalloti; Kah, Paul; Martikainen, Jukka

    Local reinforcement of aluminum with laser welded patches of zinc-coated steel can effectively contribute to crashworthiness, durability and weight reduction of car body. However, the weld between Zn-coated steel and aluminum is commonly susceptible to defects such as spatter, cavity and crack. The vaporization of Zn is commonly known as the main source of instability in the weld pool and cavity formation, especially in a lap joint configuration. Cracks are mainly due to the brittle intermetallic compounds growing at the weld interface of aluminum and steel. This study provides a review on the main metallurgical and mechanical concerns regarding laser overlap welding of Zn-coated steel on Al-alloy and the methods used by researchers to avoid the weld defects related to the vaporization of Zn and the poor metallurgical compatibility between steel and aluminum.

  13. X-ray online detection for laser welding T-joint of Al-Li alloy

    Science.gov (United States)

    Zhan, Xiaohong; Bu, Xing; Qin, Tao; Yu, Haisong; Chen, Jie; Wei, Yanhong

    2017-05-01

    In order to detect weld defects in laser welding T-joint of Al-Li alloy, a real-time X-ray image system is set up for quality inspection. Experiments on real-time radiography procedure of the weldment are conducted by using this system. Twin fillet welding seam radiographic arrangement is designed according to the structural characteristics of the weldment. The critical parameters including magnification times, focal length, tube current and tube voltage are studied to acquire high quality weld images. Through the theoretical and data analysis, optimum parameters are settled and expected digital images are captured, which is conductive to automatic defect detection.

  14. Numerical Simulations on the Laser Spot Welding of Zirconium Alloy Endplate for Nuclear Fuel Bundle Assembly

    Science.gov (United States)

    Satyanarayana, G.; Narayana, K. L.; Boggarapu, Nageswara Rao

    2018-03-01

    In the nuclear industry, a critical welding process is joining of an end plate to a fuel rod to form a fuel bundle. Literature on zirconium welding in such a critical operation is limited. A CFD model is developed and performed for the three-dimensional non-linear thermo-fluid analysis incorporating buoyancy and Marnangoni stress and specifying temperature dependent properties to predict weld geometry and temperature field in and around the melt pool of laser spot during welding of a zirconium alloy E110 endplate with a fuel rod. Using this method, it is possible to estimate the weld pool dimensions for the specified laser power and laser-on-time. The temperature profiles will estimate the HAZ and microstructure. The adequacy of generic nature of the model is validated with existing experimental data.

  15. Numerical Simulations on the Laser Spot Welding of Zirconium Alloy Endplate for Nuclear Fuel Bundle Assembly

    Science.gov (United States)

    Satyanarayana, G.; Narayana, K. L.; Boggarapu, Nageswara Rao

    2018-01-01

    In the nuclear industry, a critical welding process is joining of an end plate to a fuel rod to form a fuel bundle. Literature on zirconium welding in such a critical operation is limited. A CFD model is developed and performed for the three-dimensional non-linear thermo-fluid analysis incorporating buoyancy and Marnangoni stress and specifying temperature dependent properties to predict weld geometry and temperature field in and around the melt pool of laser spot during welding of a zirconium alloy E110 endplate with a fuel rod. Using this method, it is possible to estimate the weld pool dimensions for the specified laser power and laser-on-time. The temperature profiles will estimate the HAZ and microstructure. The adequacy of generic nature of the model is validated with existing experimental data.

  16. Welding of refractory alloys

    International Nuclear Information System (INIS)

    Lessmann, G.G.

    1984-01-01

    This review primarily summarizes welding evaluations supported by NASA-Lewis Research Center in the 1960s. A literature search run in preparation for this review indicates that more recent work is modest by comparison. Hence, this review restates these accomplishments briefly and addresses opportunities which have evolved in welding technology (such as lasers) in the intervening decade. Emphasis in this review is given to tantalum- and niobium-base alloys. Considerable work was also done to assure that a consistent comparison was made with tungsten. A wide variety of candidate alloys derived primarily from developments directed at aircraft propulsion applications were available. Early efforts by NASA were directed at screening studies to select promising structural alloys for the space power application. This objective required fine tuning of welding procedures, e.g., the demonstration of stringent standards for control of welding atmosphere to assure good corrosion resistance in liquid alkali metals. 16 figures, 6 tables

  17. Comparison of the passivity between cast alloy and laser-welded titanium overdenture bars.

    Science.gov (United States)

    Paiva, Jose; Givan, Daniel A; Broome, James C; Lemons, Jack E; McCracken, Michael S

    2009-12-01

    The purpose of this study was to investigate the fit of cast alloy overdenture and laser-welded titanium-alloy bars by measuring induced strain upon tightening of the bars on a master cast as well as a function of screw tightening sequence. Four implant analogs were secured into Type IV dental stone to simulate a mandibular edentulous patient cast, and two groups of four overdenture bars were fabricated. Group I was four cast alloy bars and Group II was four laser-welded titanium bars. The cast alloy bars included Au-Ag-Pd, Pd-Ag-Au, Au-Ag-Cu-Pd, and Ag-Pd-Cu-Au, while the laser-welded bars were all Ti-Al-V alloy. Bars were made from the same master cast, were torqued into place, and the total strain in the bars was measured through five strain gauges bonded to the bar between the implants. Each bar was placed and torqued 27 times to 30 Ncm per screw using three tightening sequences. Data were processed through a strain amplifier and analyzed by computer using StrainSmart software. Data were analyzed by ANOVA and Tukey's post hoc test. Significant differences were found between alloy types. Laser-welded titanium bars tended to have lower strains than corresponding cast bars, although the Au-Ag-Pd bar was not significantly different. The magnitudes of total strain were the least when first tightening the ends of the bar. The passivity of implant overdenture bars was evaluated using total strain of the bar when tightening. Selecting a high modulus of elasticity cast alloy or use of laser-welded bar design resulted in the lowest average strain magnitudes. While the effect of screw tightening sequence was minimal, tightening the distal ends first demonstrated the lowest strain, and hence the best passivity.

  18. Process stabilization by dual focus laser welding of aluminum alloys for car body

    Science.gov (United States)

    Shibata, Kimihiro; Iwase, Takakuni; Sakamoto, Hiroki; Dausinger, Friedrich H.; Hohenberger, Bernd; Mueller, Matthias; Matsunawa, Akira; Seto, Naoki

    2003-09-01

    Aluminum alloys were welded using dual focus beams formed with two Nd:YAG lasers with the aim of obtaining a stable welding process. The relationship between the configuration of the spot beams and the quality of the weld beads was investigated using X-ray and high-speed camera observations. The number of pores was clearly related to the ratio of the keyhole depth to the keyhole opening. A larger keyhole opening and/or a shallower keyhole depth resulted in a smaller number of pores caused by instability of the weld pool. Based on the investigation, a car body component was welded with a dual focus beam system. The results show that aluminum car body panels can be welded stably at high speed with little distortion under optimum conditions.

  19. Research on the welding process of aluminum alloy based on high power fiber laser

    Science.gov (United States)

    Zhang, Jian; Zhang, Wei; Pan, Xiaoming; Huang, Shanshi; Liu, Wenwen

    2017-08-01

    To research the formation and variation principle of the weld seam and molten pool for aluminum alloy high power fiber laser welding, the welding experiments for 5052 aluminum alloy were carried out. The influences of laser power, scanning velocity and protection gas on the welding process were systematically researched. The results show that with the increase of power and scanning velocity, the depth to width ratio first increases and then decreases. The ratio reaches the maximum value at 2.6 KW and 30 mm/s, respectively. When the power located at 2.6 KW to 2.8 KW or the velocity located at 25 mm/s to 30 mm/s, stable deep penetration welding can be obtained. The weld seam shows relative flat appearance and the molten pool presents typical "T shape" topography. Moreover, the protection gas also influences the appearance of the weld seam. Using the independently designed fixture, the quality of the weld seam can be well improved.

  20. Microstructure and mechanical properties of friction stir welded and laser welded high entropy alloy CrMnFeCoNi

    Science.gov (United States)

    Jo, Min-Gu; Kim, Han-Jin; Kang, Minjung; Madakashira, Phaniraj P.; Park, Eun Soo; Suh, Jin-Yoo; Kim, Dong-Ik; Hong, Sung-Tae; Han, Heung Nam

    2018-01-01

    The high entropy alloy CrMnFeCoNi has been shown to have promising structural properties. For a new alloy to be used in a structural application it should be weldable. In the present study, friction stir welding (FSW) and laser welding (LW) techniques were used to butt weld thin plates of CrMnFeCoNi. The microstructure, chemical homogeneity and mechanical behavior of the welds were characterized and compared with the base metal. The tensile stress-strain behavior of the welded specimens were reasonable when compared with that of the base metal. FSW refined the grain size in the weld region by a factor of ˜14 when compared with the base metal. High-angle annular dark field transmission electron microscopy in combination with energy dispersive X-ray spectroscopy showed chemical inhomogeneity between dendritic and interdendritic regions in the fusion zone of LW. Large fluctuations in composition (up to 15 at%) did not change the crystal structure in the fusion zone. Hardness measurements were carried out in the weld cross section and discussed in view of the grain size, low angle grain boundaries and twin boundaries in FSW specimens and the dendritic microstructure in LW specimens.

  1. Texture characterisation of hexagonal metals: Magnesium AZ91 alloy, welded by laser processing

    International Nuclear Information System (INIS)

    Kouadri, A.; Barrallier, L.

    2006-01-01

    Cooled and cast magnesium AZ91 alloy was welded using a CO 2 laser. The changes in the microstructure were analysed by optical and scanning electron microscopy and X-ray diffraction. Modification of the anisotropic properties was evaluated by the characterization of the texture in the base metal, in the core of the welded zone and in the welded zone close to the surface. In the two former zones, we have not observed a texture. Laser welding only leads to a change of the grain size and a disappearance of the eutectic phase. By contrast, in the welded zone close to the surface, the laser process leads both to a finer microstructure, to a loss of the Al-content and to the presence of several texture components. In this zone, our results showed that these textures are on pyramidal {101-bar 1} and prismatic {101-bar 0} planes. Much of the explanation for such texture rests with the fact that during the laser welding, material solidifies in strong non-equilibrium conditions. The kinetics of the nucleation and the growth are partly controlled by the high-rise and high fall of the temperature and the power produced by the laser process. The nature of the texture has been explained by the presence of a columnar to equiaxed transition in the welded zone

  2. Metallurgical characterization of pulsed current gas tungsten arc, friction stir and laser beam welded AZ31B magnesium alloy joints

    International Nuclear Information System (INIS)

    Padmanaban, G.; Balasubramanian, V.

    2011-01-01

    This paper reports the influences of welding processes such as friction stir welding (FSW), laser beam welding (LBW) and pulsed current gas tungsten arc welding (PCGTAW) on mechanical and metallurgical properties of AZ31B magnesium alloy. Optical microscopy, scanning electron microscopy, transmission electron microscopy and X-Ray diffraction technique were used to evaluate the metallurgical characteristics of welded joints. LBW joints exhibited superior tensile properties compared to FSW and PCGTAW joints due to the formation of finer grains in weld region, higher fusion zone hardness, the absence of heat affected zone, presence of uniformly distributed finer precipitates in weld region.

  3. The porosity formation mechanism in the laser-MIG hybrid welded joint of Invar alloy

    Science.gov (United States)

    Zhan, Xiaohong; Gao, Qiyu; Gu, Cheng; Sun, Weihua; Chen, Jicheng; Wei, Yanhong

    2017-10-01

    The porosity formation mechanism in the laser-metal inter gas (MIG) multi-layer hybrid welded (HW) joint of 19.05 mm thick Invar alloy is investigated. The microstructure characteristics and energy dispersive spectroscopy (EDS) are analyzed. The phase identification was conducted by the X-ray diffractometer (XRD). Experimental results show that the generation of porosity is caused by the relatively low laser power in the root pass and low current in the cover pass. It is also indicated that the microstructures of the welded joints are mainly observed to be columnar crystal and equiaxial crystal, which are closely related to the porosity formation. The EDS results show that oxygen content is significantly high in the inner wall of the porosity. The XRD results indicate that the BM and the WB of laser-MIG HW all are composed of Fe0.64Ni0.36 and γ-(Fe,Ni). When the weld pool is cooled quickly, [NiO] [FeO] and [MnO] are formed that react on C to generate CO/CO2 gases. The porosity of laser-MIG HW for Invar alloy is oxygen pore. The root source of metallurgy porosity formation is that the dissolved gases are hard to escape sufficiently and thus exist in the weld pool. Furthermore, 99.99% pure Argon is recommended as protective gas in the laser-MIG HW of Invar alloy.

  4. Effect of laser pulse on alternative current arc discharge during laser-arc hybrid welding of magnesium alloy

    Science.gov (United States)

    Chen, Minghua; Xin, Lijun; Zhou, Qi; He, Lijia; Wu, Fufa

    2018-01-01

    The coupling effect between a laser and arc plasma was studied in situations in which the laser acts at the positive and negative waveforms of the arc discharge during the laser-arc hybrid welding of magnesium alloy. Using the methods of direct observation, high speed imaging, and spectral analysis, the surface status of weld seams, weld penetration depths, plasma behavior, and spectral characteristics of welding plasma were investigated, respectively. Results show that, as compared with the laser pulse acting at the negative waveform of the arc plasma discharge, a better weld seam formation can be achieved when the laser pulse acts at the positive waveform of the arc discharge. At the same time, the radiation intensity of Mg atoms in the arc plasma increases significantly. However, the weld penetration depth is weaker. The findings show that when the laser pulse is acting at the negative waveform of the arc plasma discharge, the position of the arc plasma discharge on the workpiece can be restrained by the laser action point, which improves the energy density of the welding arc.

  5. Design of Laser Welding Parameters for Joining Ti Grade 2 and AW 5754 Aluminium Alloys Using Numerical Simulation

    Directory of Open Access Journals (Sweden)

    Mária Behúlová

    2017-01-01

    Full Text Available Joining of dissimilar Al-Ti alloys is very interesting from the point of view of weight reduction of components and structures in automotive or aerospace industries. In the dependence on cooling rate and chemical composition, rapid solidification of Al-Ti alloys during laser welding can lead to the formation of metastable phases and brittle intermetallic compounds that generally reduce the quality of produced weld joints. The paper deals with design and testing of welding parameters for preparation of weld joints of two sheets with different thicknesses from titanium Grade 2 and AW 5754 aluminium alloy. Temperature fields developed during the formation of Al-Ti butt joints were investigated by numerical simulation in ANSYS software. The influence of laser welding parameters including the laser power and laser beam offset on the temperature distribution and weld joint formation was studied. The results of numerical simulation were verified by experimental temperature measurement during laser beam welding applying the TruDisk 4002 disk laser. The microstructure of produced weld joints was assessed by light microscopy and scanning electron microscopy. EDX analysis was applied to determine the change in chemical composition across weld joints. Mechanical properties of weld joints were evaluated using tensile tests and Vickers microhardness measurements.

  6. Morphology, microstructure, and mechanical properties of laser-welded joints in GH909 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chunming; Cai, Yuanzheng; Hu, Chongjing; Zhang, Xiong; Yan, Fei; Hu, Xiyuan [Huazhong University of Science and Technology, Wuhan (China)

    2017-05-15

    The experimental laser welding of GH909 alloy was conducted in this study. The morphology, microstructure, and mechanical properties of laser-welded joints were analyzed by scanning electron microscopy, energy diffraction spectroscopy, and other techniques. Results revealed that the microstructure of the welded joints mainly consisted of tiny cellular structures, dendritic structures, and equiaxed crystals. Pores appeared in the interdendritic regions because of the insufficient local feeding of molten metal during solidification. Nb segregation in the heat-affected zone caused liquation cracking, whereas C segregation further induced the formation of carbide precipitates along the grain boundaries during the welding thermal cycle. The instability of the keyhole significantly promoted the escape of the metal vapor/plasma from the hole; as a result, porosity defects formed in the weld. The average tensile strength of the test joints was 756 MPa, which is 93.1 % of that of the base metal. The average microhardness of the weld zone (250 HV) was higher than that of the GH909 alloy substrate (208 HV), peaking at 267 HV. Microcracks appeared along the grain boundaries, proving that the grain boundaries were the weakest areas in the joint.

  7. Aluminium alloys welding with high-power Nd:YAG lasers

    International Nuclear Information System (INIS)

    Garcia Orza, J.A.

    1998-01-01

    Aluminium alloys have good mechanical properties (high strength-to-weight ratio, corrosion resistance) and good workability. their applications are growing up, specially in the transportation industry. Weldability is however poorer than in other materials; recent advances in high power YAG laser are the key to obtain good appearance welds and higher penetration, at industrial production rates. Results of the combination of high power YAG beams with small fiber diameters and specific filler wires are presented. It is also characterized the air bone particulate material, by-product of the laser process: emission rates, size distribution and chemical composition are given for several aluminium alloys. (Author) 6 refs

  8. Fusion zone microstructure of laser beam welded directionally solidified Ni3Al-base alloy IC6

    International Nuclear Information System (INIS)

    Ding, R.G.; Ojo, O.A.; Chaturvedi, M.C.

    2006-01-01

    The fusion zone microstructure of laser welded alloy IC6 was examined. Extensive weld-metal cracking was observed to be closely associated with non-equilibrium eutectic-type microconstituents identified as consisting of γ, γ' and NiMo (Y) phases. Their formation has been related to modification of primary solidification path due to reduced solutal microsegregation

  9. Corrosion properties of Nd:YAG laser-GMA hybrid welded AA6061 Al alloy and its microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Daquan; Li Jin [Department of Environmental Engineering, Shanghai University of Electric Power, Shanghai 200090 (China); Joo, Hyung Goun [Stress Analysis and Failure Design Laboratory, School of Mechanical Engineering, Yonsei University, 134, Shinchon-dong, Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Lee, Kang Yong [Stress Analysis and Failure Design Laboratory, School of Mechanical Engineering, Yonsei University, 134, Shinchon-dong, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)], E-mail: KYL2813@yonsei.ac.kr

    2009-06-15

    The paper presents the corrosion behaviour of the Nd:YAG laser-gas metal arc (GMA) welds of AA6061-T6 alloy. The laser-GMA hybrid welding enhances the corrosion susceptibility of AA6061 alloy. The surface morphology observation and composition analysis were investigated by the scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) spectroscopy. An increasing of the precipitate phase is observed in the weld fusion zone (WFZ). The WFZ suffers more severe pitting and cracks are associated with pitting. It is proposed that the increased precipitate phase increases the galvanic corrosion couples and results in the aggravation of pitting and cracking in the WFZ.

  10. Microstructure and corrosion properties of diode laser melted friction stir weld of aluminum alloy 2024 T351

    International Nuclear Information System (INIS)

    Kalita, Samar Jyoti

    2011-01-01

    Friction stir welding is a promising solid state joining process for high strength aluminum alloys. Though friction stir welding eliminates the problems of fusion welding as it is performed below melting temperature (T m ), it creates severe plastic deformation. Friction stir welds of some aluminum alloys exhibit relatively poor corrosion resistance. This research enhanced the corrosion properties of such welds through diode laser surface melting. A friction stir weld of aluminum alloy 2024 T351 was laser melted using a 1 kW diode laser. The melt-depth and microstructure were investigated using optical and scanning electron microscopy. The melt zone exhibited epitaxially grown columnar grains. At the interface between the melted and the un-melted zone, a thick planar boundary was observed. Energy dispersive spectroscopy analyzed the redistribution of elemental composition. The corrosion properties of the laser melted and native welds were studied in aqueous 0.5 M sodium chloride solution using open circuit potential and cyclic potentiodynamic polarization. The results show noticeable increase in the pit nucleation resistance (390 mV) after the laser surface treatment. The repassivation potential was nobler to the corrosion potential after the laser treatment, which confirmed that the resistance to pit growth was improved.

  11. Microstructure and corrosion properties of diode laser melted friction stir weld of aluminum alloy 2024 T351

    Energy Technology Data Exchange (ETDEWEB)

    Kalita, Samar Jyoti, E-mail: Samar.Kalita@und.nodak.edu [Engineered Surfaces Center, School of Engineering and Mines, University of North Dakota, Grand Forks, ND (United States)

    2011-02-15

    Friction stir welding is a promising solid state joining process for high strength aluminum alloys. Though friction stir welding eliminates the problems of fusion welding as it is performed below melting temperature (T{sub m}), it creates severe plastic deformation. Friction stir welds of some aluminum alloys exhibit relatively poor corrosion resistance. This research enhanced the corrosion properties of such welds through diode laser surface melting. A friction stir weld of aluminum alloy 2024 T351 was laser melted using a 1 kW diode laser. The melt-depth and microstructure were investigated using optical and scanning electron microscopy. The melt zone exhibited epitaxially grown columnar grains. At the interface between the melted and the un-melted zone, a thick planar boundary was observed. Energy dispersive spectroscopy analyzed the redistribution of elemental composition. The corrosion properties of the laser melted and native welds were studied in aqueous 0.5 M sodium chloride solution using open circuit potential and cyclic potentiodynamic polarization. The results show noticeable increase in the pit nucleation resistance (390 mV) after the laser surface treatment. The repassivation potential was nobler to the corrosion potential after the laser treatment, which confirmed that the resistance to pit growth was improved.

  12. Microstructure and Tensile Behavior of Laser Arc Hybrid Welded Dissimilar Al and Ti Alloys

    Directory of Open Access Journals (Sweden)

    Ming Gao

    2014-02-01

    Full Text Available Fiber laser-cold metal transfer arc hybrid welding was developed to welding-braze dissimilar Al and Ti alloys in butt configuration. Microstructure, interface properties, tensile behavior, and their relationships were investigated in detail. The results show the cross-weld tensile strength of the joints is up to 213 MPa, 95.5% of same Al weld. The optimal range of heat input for accepted joints was obtained as 83–98 J·mm−1. Within this range, the joint is stronger than 200 MPa and fractures in weld metal, or else, it becomes weaker and fractures at the intermetallic compounds (IMCs layer. The IMCs layer of an accepted joint is usually thin and continuous, which is about 1μm-thick and only consists of TiAl2 due to fast solidification rate. However, the IMCs layer at the top corner of fusion zone/Ti substrate is easily thickened with increasing heat input. This thickened IMCs layer consists of a wide TiAl3 layer close to FZ and a thin TiAl2 layer close to Ti substrate. Furthermore, both bead shape formation and interface growth were discussed by laser-arc interaction and melt flow. Tensile behavior was summarized by interface properties.

  13. Microscopic Analysis of Welded Dental Alloys

    OpenAIRE

    S. Porojan; L. Sandu; F. Topalâ

    2011-01-01

    Microplasma welding is a less expensive alternative to laser welding in dental technology. The aim of the study was to highlight discontinuities present in the microplasma welded joints of dental base metal alloys by visual analysis. Five base metal alloys designated for fixed prostheses manufacture were selected for the experiments. Using these plates, preliminary tests were conducted by microplasma welding in butt joint configuration, without filler material, bilaterall...

  14. Assessment of The Cracking Properties of Stainless Steel Alloys and their Usability for Laser Welding in Production

    DEFF Research Database (Denmark)

    Juhl, Thomas Winther

    2001-01-01

    Methods to assess stainless steel alloys’ cracking properties and usability for laser welding has been studied. Also tests to assess alloys’ susceptibility to hot cracking has been conducted. Among these is the so-called Weeter test which assesses the alloy by executing a number of spot welds...... to provoke cracking in the alloy. In this work the Weeter test has been modified and changed in order to develop a faster and easier test also applicable to small specimens. The new test, called a Groove test differs from the Weeter test by its procedure in which linear seam welds are conducted instead...... of spot welds. The Groove test has the advantage of an easier microscopy and analysis in the welds. Results from crack tests was partly confirmed by predictions made on the basis of the alloy’s constituents and solidification growth rate....

  15. The effect of laser surface melting on microstructure and corrosion behavior of friction stir welded aluminum alloy 2219

    Science.gov (United States)

    Ma, Shengchong; Zhao, Yong; Zou, Jiasheng; Yan, Keng; Liu, Chuan

    2017-11-01

    This study aimed to explore the electrochemical properties and microstructure of friction stir welds to understand the correlation between their properties and processing. Friction stir welding is a promising solid-state joining process for high-strength aluminum alloys (AA). Although friction stir welding (FSW) eliminates the problems of fusion welding due to the fact that it is performed below Tm, it causes severe plastic deformation in the material. Some AA welded by FSW exhibit relatively poor corrosion resistance. In this research, the corrosion resistance of such welds was enhanced through laser surface melting. A friction stir weld of AA 2219 was laser melted. The melt depth and microstructure were observed using optical and scanning electron microscopy. The melt zone exhibited epitaxially grown columnar grains. The redistribution of elemental composition was analyzed using energy-dispersive spectroscopy. The anticorrosion properties of both laser-melted and original welds were studied in aqueous 3.5% NaCl solution using cyclic potentiodynamic polarization. The results indicated a noticeable increase in the pitting corrosion resistance after the laser treatment on the surface. The repassivation potential was nobler than the corrosion potential after the laser treatment, confirming that the resistance to pitting growth improved.

  16. Application of slip-band visualization technique to tensile analysis of laser-welded aluminum alloy

    Science.gov (United States)

    Muchiar, -; Yoshida, Sanichiro J.; Widiastuti, Rini; Kusnowo, A.; Takahashi, Kunimitsu; Sato, Shunichi

    1997-03-01

    Recently we have developed a new optical interferometric technique capable of visualizing slip band occurring in a deforming solid-state object. In this work we applied this technique to a tensile analysis of laser-welded aluminum plate samples, and successfully revealed stress concentration that shows strong relationships with the tensile strength and the fracture mechanism. We believe that this method is a new, convenient way to analyze the deformation characteristics of welded objects and evaluate the quality of welding. The analysis has been made for several types of aluminum alloys under various welding conditions, and has shown the following general results. When the penetration is deep, a slip band starts appearing at the fusion zone in an early stage of the elastic region of the strain-stress curve and stays there till the sample fractures at that point. When the penetration is shallow, a slip band appears only after the yield point and moves vigorously over the whole surface of the sample till a late stage of plastic deformation when the slip band stays at the fusion zone where the sample eventually fractures. When the penetration depth is medium, some intermediate situation of the above two extreme cases is observed.

  17. Local zone-wise elastic-plastic constitutive parameters of Laser-welded aluminium alloy 6061 using digital image correlation

    Science.gov (United States)

    Bai, Ruixiang; Wei, Yuepeng; Lei, Zhenkun; Jiang, Hao; Tao, Wang; Yan, Cheng; Li, Xiaolei

    2018-02-01

    The mechanical properties of aluminium alloys can be affected by the local high temperature in laser welding. In this paper, an inversion identification method of local zone-wise elastic-plastic constitutive parameters for laser welding of aluminium alloy 6061 was proposed based on full-field optical measurement data using digital image correlation (DIC). Three regions, i.e., the fusion zone, heat-affected zone, and base zone, of the laser-welded joint were distinguished by means of microstructure optical observation and micrometer hardness measurement. The stress data were obtained using a laser-welded specimen via a uniaxial tensile test. Meanwhile, the local strain data of the laser-welded specimen were obtained by the DIC technique. Thus, the stress-strain relationship for different local regions was established. Finally, the constitutive parameters of the Ramberg-Osgood model were identified by least-square fitting to the experimental stress-strain data. Experimental results revealed that the mechanical properties of the local zones of the welded joints clearly weakened, and these results are consistent with the results of the hardness measurement.

  18. Deformation behavior of laser welds in high temperature oxidation resistant Fe-Cr-Al alloys for fuel cladding applications

    Science.gov (United States)

    Field, Kevin G.; Gussev, Maxim N.; Yamamoto, Yukinori; Snead, Lance L.

    2014-11-01

    Ferritic-structured Fe-Cr-Al alloys are being developed and show promise as oxidation resistant accident tolerant light water reactor fuel cladding. This study focuses on investigating the weldability and post-weld mechanical behavior of three model alloys in a range of Fe-(13-17.5)Cr-(3-4.4)Al (wt.%) with a minor addition of yttrium using modern laser-welding techniques. A detailed study on the mechanical performance of bead-on-plate welds using sub-sized, flat dog-bone tensile specimens and digital image correlation (DIC) has been carried out to determine the performance of welds as a function of alloy composition. Results indicated a reduction in the yield strength within the fusion zone compared to the base metal. Yield strength reduction was found to be primarily constrained to the fusion zone due to grain coarsening with a less severe reduction in the heat affected zone. For all proposed alloys, laser welding resulted in a defect free weld devoid of cracking or inclusions.

  19. Laser beam welding of NiTi-shape memory alloys; Laserstrahl-Schweissen von NiTi-Formgedaechtnislegierungen

    Energy Technology Data Exchange (ETDEWEB)

    Haas, T.

    1996-04-01

    Using a Nd:YAG laser, the weldability of binary nickel-titanium shape memory alloys containing 50.0 and 48.5 at.-% Ti respectively was investigated. By tensile tests within a temperature range of -80 C to +200 C the mechanical properties of the laser welded joints were examined. Changes in the transformation behaviour were detected by calorimetric measurements (DSC method). The stress-strain behaviour was attributed to the microstructure of the welds, revealed by optical microscopy and transmission electron microscopy (TEM). Using a scanning electron microscope (SEM), the mechanisms of failure were examined. Joints of the martensitic Ti-rich alloy were brittle, showing an ultimate tensile strength of 600 MPa, corresponding to half of the value of the base material. The reduction in strength was explained by the formation of Ti{sub 2}Ni precipitations along grain boundaries in the weld. Since the welds still exhibited twin deformation, pseudoplastic strains of 7% were achieved. Ultimate strength data showed a very low scatter. Therefore it was possible to use the shape memory effect up to a strain of 6% without failure. After a total elongation to 6% strain, the laser welded joints showed a free recovery with an amnesia of 0.3%. The shape memory effect was shown to be retained in the laser welded joints. 154 refs.

  20. The Numerical and Experimental Investigation of the Multi-layer Laser-MIG Hybrid Welding for Fe36Ni Invar Alloy

    Science.gov (United States)

    Zhan, Xiaohong; Liu, Yun; Ou, Wenmin; Gu, Cheng; Wei, Yanhong

    2015-12-01

    Numerical and experimental investigations of multi-layer laser-MIG hybrid welding for Fe36Ni Invar alloy were presented in this paper. The multi-layer laser-MIG hybrid welding experiments with different parameters were conducted for the 19.5-mm-thick Invar plates. A finite element (FE) model was established to predict the temperature field, residual stress, and deformation distribution during and after welding. A plane-conical combined heat source model was used to simulate the laser-MIG hybrid welding process. Different numbers of welding layers were chosen to study the effect of welding layer on the temperature field, residual stress, and deformation distribution. It was found that the maximum residual stress of Invar plates after laser-MIG hybrid welding is 300 MPa and maximum deformation is 0.4 mm, so that laser-MIG hybrid welding can be used in actual manufacture of Invar moulds.

  1. Correlation of Weld Appearance with Microstructure and Mechanical Properties of 2024-T4 Aluminum Alloy Welded by Fiber Laser with Filler Wire

    Directory of Open Access Journals (Sweden)

    XU Fei

    2017-11-01

    Full Text Available Two typical cross-section of welds, including nail shape and near X shape, are obtained in the process of fiber laser welding 2024-T4 Al alloy with filler wire. The correlations of the two weld appearances and other elements (such as microstructure, microhardness, and joint's tensile properties were analyzed. The results show that the weld with near X shape cross-section during the welding process is more stable than that with nail shape cross-section, and the welding spatter of the former is smaller than that of the latter. The microstructure of the weld zone is columnar grains and equiaxed grains, the columnar grains are formed near the fusion line and growing along the vertical direction of the fusion line, the equiaxed grains are distributed in the center of the weld zone. The secondary dendrite of the grains in the center of the weld with nail shape cross-section grows better, and gradually forms to equiaxed dendrite, while the grains size of the weld with near X shape cross-section is relatively finer, exhibiting equiaxed cellular grain. Compared with the joint with nail shape cross-section of the weld, the joint with near X shape cross-section of the weld have some different characteristics, the precipitation strengthening phase θ(Al2Cu content in weld zone of the latter is more than that of the former, the average microhardness value of the weld zone of the latter is higher than that of the former, the softening phenomenon of heat affect zone (HAZ of the latter is weaker than that of the former, and the joint's tensile strength and plasticity of the latter are lower than that of the former slightly.

  2. Heat affected zone microfissuring in a laser beam welded directionally solidified Ni3Al-base alloy

    International Nuclear Information System (INIS)

    Ojo, O.A.; Ding, R.G.; Chaturvedi, M.C.

    2006-01-01

    The laser beam weld heat affected zone (HAZ) microstructure of a newly developed aerospace alloy, IC 6, was examined. HAZ microfissuring was observed and found to be associated with grain boundary liquation facilitated by subsolidus eutectic-type transformation of the alloy's major phase, γ' precipitates, and interfacial melting of M 6 C-type carbide and (Mo 2 Ni)B 2 -type boride particles

  3. Statistical analysis of process parameters to eliminate hot cracking of fiber laser welded aluminum alloy

    Science.gov (United States)

    Wang, Jin; Wang, Hui-Ping; Wang, Xiaojie; Cui, Haichao; Lu, Fenggui

    2015-03-01

    This paper investigates hot cracking rate in Al fiber laser welding under various process conditions and performs corresponding process optimization. First, effects of welding process parameters such as distance between welding center line and its closest trim edge, laser power and welding speed on hot cracking rate were investigated experimentally with response surface methodology (RSM). The hot cracking rate in the paper is defined as ratio of hot cracking length over the total weld seam length. Based on the experimental results following Box-Behnken design, a prediction model for the hot cracking rate was developed using a second order polynomial function considering only two factor interaction. The initial prediction result indicated that the established model could predict the hot cracking rate adequately within the range of welding parameters being used. The model was then used to optimize welding parameters to achieve cracking-free welds.

  4. Numerical simulation of spatter formation during fiber laser welding of 5083 aluminum alloy at full penetration condition

    Science.gov (United States)

    Wu, Dongsheng; Hua, Xueming; Huang, Lijin; Zhao, Jiang

    2018-03-01

    The droplet escape condition in laser welding is established in this paper. A three-dimensional numerical model is developed to study the weld pool convection and spatter formation at full penetration during the fiber laser welding of 5083 aluminum alloy. It is found that when laser power is 9 kW, the bottom of the keyhole is dynamically opened and closed. When the bottom of the keyhole is closed, the molten metal at the bottom of the back keyhole wall flows upwards along the fusion line. When the bottom of the keyhole is opened, few spatters can be seen around the keyhole at the top surface, two flow patterns exists in the rear part of the keyhole: a portion of molten metal flows upwards along the fusion line, other portion of molten metal flows to the bottom of the keyhole, which promote the spatter formation at the bottom of the keyhole rear wall.

  5. Structural state and geometric representation of a laser-welded joint between corrosion-resistant steel and titanium alloy with copper insert

    Science.gov (United States)

    Michurov, N. S.; Veretennikova, I. A.; Pugacheva, N. B.; Smirnova, E. O.

    2017-12-01

    The paper shows a characteristic structure of a welded joint between titanium alloy and corrosion-resistant steel, with a copper insert, produced by carbon dioxide laser welding. In the formation of the joint, the materials being welded are dissolved and mixed in the copper interlayer. The material of the welded joint is an oversaturated solid solution of Fe, Ni, Cr and Ti in the copper lattice with distributed TiFe, Ti(Fe, Cr)2 and CuTi2 intermetallic particles. A 10-150 µm thick diffusion zone with an altered chemical composition appears at the boundary with the steel, and a 50- 100 µm thick zone of the kind is formed at the boundary with the titanium alloy. The phase composition is determined and recrystallization maps at the boundaries of the welded joint are obtained. A geometric representation of a laser welded joint between titanium alloy and corrosion-resistant steel with a copper insert is constructed.

  6. Effect of laser-arc hybrid welding on fracture and corrosion behaviour of AA6061-T6 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Daquan, E-mail: zhdq@sh163.net [Department of Environmental Engineering, Shanghai University of Electric Power, Shanghai 200090 (China); Jin Xin; Gao Lixin [Department of Environmental Engineering, Shanghai University of Electric Power, Shanghai 200090 (China); Joo, Hyung Goun [Stress Analysis and Failure Design Laboratory, School of Mechanical Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Lee, Kang Yong, E-mail: KYL2813@yonsei.ac.kr [Stress Analysis and Failure Design Laboratory, School of Mechanical Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)

    2011-03-15

    Research highlights: {yields} A dendritic cellular structure was formed in the weld fusion zone (WFZ) and caused alloying element segregation. {yields} The precipitation of intermetallic phases and the formation of galvanic corrosion couplings contribute to the improving pitting susceptibility in the WFZ. {yields} The intergranular corrosion nucleates on pit walls and spreads from them. - Abstract: The welding condition of the hybrid laser-gas metal arc (GMA) welding for AA6061-T6 alloy was optimized by tensile test. Formability performance was checked by the bend test. Fractographic analysis indicates a large number of fine ductile type voids in the fracture surface. The microstructure measurements exhibit a dendritic cellular structure in the weld fusion zone (WFZ) and a partially melted zone adjacent to the fusion boundaries. The corrosion behaviour of the weldment and the base alloy were investigated by weight-loss test in nitric acid solution. The WFZ suffers more severe pitting than the rest regions in the weldment. It shows that corrosion cracking is owing to the precipitation of intermetallic phases and the formation of galvanic corrosion couplings in the weldment of AA6061-T6 alloy.

  7. Electron beam welding and laser welding of FRAGEMA fuel assembly components

    International Nuclear Information System (INIS)

    Couturier, J.M.; Etellin, B.; Duthoo, B.; Wache, C.; Taillandier, T.

    1988-01-01

    Neutron balance and activity of the primary coolant circuit are improved in PWR if inconel 718 is replaced by a zirconium alloy for fuel element grids. This paper examines laser welding and EB welding of these zirconium alloy grids [fr

  8. Effects of mechanical heterogeneity on the tensile and fatigue behaviours in a laser-arc hybrid welded aluminium alloy joint

    International Nuclear Information System (INIS)

    He, Chao; Huang, Chongxiang; Liu, Yongjie; Li, Jiukai; Wang, Qingyuan

    2015-01-01

    Highlights: • Full field strain evolution was characterized using DIC method in fatigue test. • The differences of fatigue failure mechanism between HAZ and FZ were discussed. • Porosity in FZ significantly influenced high cycle fatigue behaviours of the weld. - Abstract: The effects of mechanical heterogeneity on the tensile and high cycle fatigue (10 4 –10 7 cycles) properties were investigated for laser-arc hybrid welded aluminium alloy joints. Tensile–tensile cyclic loading with a stress ratio of 0.1 was applied in a direction perpendicular to the weld direction for up to 10 7 cycles. The local mechanical properties in the tensile test and the accumulated plastic strain in the fatigue test throughout the weld’s different regions were characterized using a digital image correlation technique. The tensile results indicated heterogeneous tensile properties throughout the different regions of the aluminium welded joint, and the heat affected zone was the weakest region in which the strain localized. In the fatigue test, the accumulated plastic strain evolutions in different subzones of the weld were analyzed, and slip bands could be clearly observed in the heat affected zone. A transition of fatigue failure locations from the heat affected zone caused by accumulated plastic strain to the fusion zone induced by fatigue crack at pores could be observed under different cyclic stress levels. The welding porosity in the fusion zone significantly influences the high cycle fatigue behaviour

  9. Effects of laser shock peening on stress corrosion behavior of 7075 aluminum alloy laser welded joints

    Energy Technology Data Exchange (ETDEWEB)

    Wang, J.T., E-mail: jiasqq1225@126.com [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); School of Materials Engineering, Jiangsu University of Technology, Changzhou 213001 (China); Zhang, Y.K. [School of Mechanical Engineering, Jiangsu University, Zhenjiang 212013 (China); School of Mechanical Engineering, Southeast University, Nanjing 211189 (China); Chen, J.F.; Zhou, J.Y.; Ge, M.Z.; Lu, Y.L.; Li, X.L. [School of Materials Engineering, Jiangsu University of Technology, Changzhou 213001 (China)

    2015-10-28

    7075 aluminum alloy weldments were processed by an intensive process known as laser shock peening (LSP), meanwhile its stress corrosion behaviors were observed by scanning electron microscopy (SEM) and slow strain rate tensile (SSRT) tests. Results showed that the effect of LSP on corrosion behavior of the joint was fairly useful and obvious. With LSP, the elongation, time of fracture and static toughness after the SSRT test were improved by 11.13%, 20% and 100%, respectively. At the same time, the location of the fracture also changed. LSP led to a transition of the fracture type from transgranular to intergranular The reasons for these enhancements of the joint on corrosion behavior were caused by microstructure, residual stress, micro-hardness, and fracture appearance.

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

    Science.gov (United States)

    Harooni, Masoud

    It is advantageous for the transportation industry to use lightweight components in the structure in order to save mass and reduce CO2 emissions. One of the lightest structural metals, magnesium, fulfills the need for mass reduction within the automotive industry. Many of the body structure components in the automotive industry are assembled using joining processes such as fusion welding. Furthermore, laser welding offers a low heat impact, high process rate, joining method which is becoming increasingly popular as the cost for laser systems continues to decrease. However, there is a limited body of work investigating the laser welding of magnesium and therefore, in the current study, different techniques and methods for laser welding of magnesium alloys are numerically and experimentally studied in order to optimize process parameters to achieve high quality welds. A feasibility study was designed in order to study the effect of various laser welding process parameters (such as laser power levels and welding speeds) on weld quality. Three regression models were developed to find the best fit model that relates process parameters to the shear load of the weld. Furthermore, to understand the effect of laser welding parameters on temperature distribution in laser welding of AZ31B magnesium alloy, a numerical model was developed. A rotary Gaussian volumetric body heat source was applied in this study to obtain the temperature history during the laser welding process. Cross-sectional views of the weld beads, temperature history recorded by thermocouples, and temperature history recorded by infrared camera were used to validate the numerical model. In order to study the real-time dynamic behavior of the molten pool and the keyhole during the welding process, a high speed charge-coupled device (CCD) assisted with a green laser as an illumination source was used. In order to observe the presence of pores, prior studies destructively evaluated the weld bead however; in the

  11. The welding characteristics of Fe-based shape memory alloys

    International Nuclear Information System (INIS)

    Lin, H.C.; Lin, K.M.; Chuang, Y.C.; Chen, F.H.

    2000-01-01

    After TIG and laser welding, the microstructure, shape memory effect and chemical corrosion resistance of Fe-30Mn-6Si and Fe-30Mn-6Si-5Cr shape memory alloys have been investigated. Experimental results show that the welded zones exhibit dendrite structures. The as-welded alloys still have an excellent shape memory effect. The corrosion resistance of welded zones is found to be worse than that of the base-material for both Fe-30Mn-6Si and Fe-30Mn-6Si-5Cr alloys. The degradation of corrosion resistance is more obvious for laser-welded zone than that for TIG-welded zone. After annealing treatment of 1100 C x 2h for these welded alloys, the dendrite structures in the welded zones disappear and the corrosion resistance is improved. (orig.)

  12. Correlation between corrosion resistance properties and thermal cycles experienced by gas tungsten arc welding and laser beam welding Alloy 690 butt weldments

    International Nuclear Information System (INIS)

    Lee, H T; Wu, J L

    2009-01-01

    This study investigates the correlation between the thermal cycles experienced by Alloy 690 weldments fabricated using gas tungsten arc welding (GTAW) and laser beam welding (LBW) processes, and their corresponding corrosion resistance properties. The corrosion resistance of the weldments is evaluated using a U-bend stress corrosion test in which the specimens are immersed in a boiling, acid solution for 240 h. The experimental results reveal that the LBW inputs significantly less heat to the weldment than the GTAW, and therefore yields a far faster cooling rate. Moreover, the corrosion tests show that in the GTAW specimen, intergranular corrosion (IGC) occurs in both the fusion zone (FZ) and the heat affected zone (HAZ). By contrast, the LBW specimen shows no obvious signs of IGC.

  13. Modelling of fluid flow phenomenon in laser+GMAW hybrid welding of aluminum alloy considering three phase coupling and arc plasma shear stress

    Science.gov (United States)

    Xu, Guoxiang; Li, Pengfei; Cao, Qingnan; Hu, Qingxian; Gu, Xiaoyan; Du, Baoshuai

    2018-03-01

    The present study aims to develop a unified three dimensional numerical model for fiber laser+GMAW hybrid welding, which is used to study the fluid flow phenomena in hybrid welding of aluminum alloy and the influence of laser power on weld pool dynamic behavior. This model takes into account the coupling of gas, liquid and metal phases. Laser heat input is described using a cone heat source model with changing peak power density, its height being determined based on the keyhole size. Arc heat input is modeled as a double ellipsoid heat source. The arc plasma flow and droplet transfer are simulated through the two simplified models. The temperature and velocity fields for different laser powers are calculated. The computed results are in general agreement with the experimental data. Both the peak and average values of fluid flow velocity during hybrid welding are much higher than those of GMAW. At a low level of laser power, both the arc force and droplet impingement force play a relatively large role on fluid flow in the hybrid welding. Keyhole depth always oscillates within a range. With an increase in laser power, the weld pool behavior becomes more complex. An anti-clockwise vortex is generated and the stability of keyhole depth is improved. Besides, the effects of laser power on different driving forces of fluid flow in weld pool are also discussed.

  14. Laser weld jig

    Science.gov (United States)

    Van Blarigan, Peter; Haupt, David L.

    1982-01-01

    A system is provided for welding a workpiece (10, FIG. 1) along a predetermined weld line (12) that may be of irregular shape, which includes the step of forming a lip (32) on the workpiece to extend parallel to the weld line, and moving the workpiece by engaging the lip between a pair of rotatable members (34, 36). Rotation of one of the members at a constant speed, causes the workpiece to move so that all points on the weld line sequentially pass a fixed point in space (17) at a constant speed, so that a laser welding beam can be directed at that fixed point to form a weld along the weld line. The workpiece can include a reuseable jig (24) forming the lip, and with the jig constructed to detachably hold parts (22, 20) to be welded at a position wherein the weld line of the parts extends parallel to the lip on the jig.

  15. Laser Assisted Plasma Arc Welding

    Energy Technology Data Exchange (ETDEWEB)

    FUERSCHBACH,PHILLIP W.

    1999-10-05

    Experiments have been performed using a coaxial end-effecter to combine a focused laser beam and a plasma arc. The device employs a hollow tungsten electrode, a focusing lens, and conventional plasma arc torch nozzles to co-locate the focused beam and arc on the workpiece. Plasma arc nozzles were selected to protect the electrode from laser generated metal vapor. The project goal is to develop an improved fusion welding process that exhibits both absorption robustness and deep penetration for small scale (< 1.5 mm thickness) applications. On aluminum alloys 6061 and 6111, the hybrid process has been shown to eliminate hot cracking in the fusion zone. Fusion zone dimensions for both stainless steel and aluminum were found to be wider than characteristic laser welds, and deeper than characteristic plasma arc welds.

  16. Laser forming and welding processes

    CERN Document Server

    Yilbas, Bekir Sami; Shuja, Shahzada Zaman

    2013-01-01

    This book introduces model studies and experimental results associated with laser forming and welding such as laser induced bending, welding of sheet metals, and related practical applications. The book provides insight into the physical processes involved with laser forming and welding. The analytical study covers the formulation of laser induced bending while the model study demonstrates the simulation of bending and welding processes using the finite element method. Analytical and numerical solutions for laser forming and welding problems are provided.

  17. Comparison of the mechanical solidity of soldered and differently laser welded test specimens from a Palladium based alloy before and after six months of chemical stress.

    OpenAIRE

    Heintzenberg, Katja Ulrike

    2010-01-01

    The submitted study is about the comparison of the mechanical solidity of soldered and differently laser welded test specimens from a Palladium based alloy before and after six months of chemical stress. By vacuum-pressure-technique 80 DIN meeting test specimens have been produced from the Palladium alloy BegoPal® 300. 3 of the 10 series originated from five times cast reused metal, the remaining from pure new metal. After visual check of the test specimen...

  18. Characterization of friction stir welded joints of the aluminium alloy AA 2024-T3 by laser extensometry; Reibruehrschweissungen aus Aluminium charakterisieren. Lokale Dehnungsmessung mit Laserextensometer

    Energy Technology Data Exchange (ETDEWEB)

    Biallas, G. [Paderborn Univ. (Germany). Lehrstuhl fuer Werkstoffkunde; Dalle Donne, C. [DLR Deutsches Zentrum fuer Luft- und Raumfahrt e.V., Koeln (Germany). Inst. fuer Werkstoff-Forschung

    2000-07-01

    Friction stir welding (FSW) is a simple, clean and innovative solid state joining process for light metals. In contrast to conventional welding, FSW is performed at temperatures below the melting point. Therefore, detrimental microstructural changes and cracking during the solidification of the weld pool are avoided. Within certain limits, the excellent mechanical properties of friction stir welds are further improved by an increase of the welding or transverse speed. This is shown by localized strain measurements during tensile tests of friction stir welded sheet material of the aluminium alloy AA 2024-T3. The local strains are measured in the welding region and in the heat affected zone by a laser extensometer. It turned out that the increase in strength with increasing weld speed has to be related to the more homogeneous strain distribution in the welding region and heat affected zone. (orig.) [German] Das Reibruehrschweissen oder Friction Stir Welding (FSW) ist ein einfaches und sauberes Fuegeverfahren fuer Leichtmetalle. Im Gegensatz zu konventionellen Schmelz-Schweissverfahren erfolgt der FSW-Prozess bei Temperaturen unterhalb des Schmelzpunktes von Leichtmetalllegierungen, was Gefuegeveraenderungen und Rissbildungen beim Erstarren der Schmelze vermeidet. Die guten mechanischen Eigenschaften reibruehrgeschweisster Verbindungen lassen sich durch eine Erhoehung des Vorschubs weiter verbessern, wie Zugversuche an geschweissten Blechen der Aluminiumlegierung AA 2024-T3 zeigen. Ueber lokale Dehnungsmessungen im Nahtbereich wird mit dem Laserextensometer nachgewiesen, dass die Ursache der gleichzeitigen Zunahme von Festigkeit und Verformbarkeit in einem homogenen Verformungszustand liegt. (orig.)

  19. Microgalvanic corrosion of laser-welded HSLA steels

    NARCIS (Netherlands)

    Looi, Y.M.

    2008-01-01

    Laser welding of galvanized high strength low alloy (HSLA) steels leads to the evaporation of zinc at the weld and the formation of a heat-affected-zone (HAZ). High heat input due to welding generates macro galvanic coupling between the weld and the parent metal as well as micro galvanic corrosion

  20. Laser Welding in Space

    Science.gov (United States)

    Workman, Gary L.; Kaukler, William F.

    1989-01-01

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

  1. Welding of Prosthetic Alloys

    Directory of Open Access Journals (Sweden)

    Wojciechowska M.

    2015-04-01

    Full Text Available This paper presents the techniques of joining metal denture elements, used in prosthetic dentistry: the traditional soldering technique with a gas burner and a new technique of welding with a laser beam; the aim of the study was to make a comparative assessment of the quality of the joints in view of the possibility of applying them in prosthetic structures. Fractographic examinations were conducted along with tensile strength and impact strength tests, and the quality of the joints was assessed compared to the solid metal. The experiments have shown that the metal elements used to make dentures, joined by the technique which employs a laser beam, have better strength properties than those achieved with a gas burner.

  2. Neutral polypropylene laser welding

    Science.gov (United States)

    Mandolfino, Chiara; Lertora, Enrico; Gambaro, Carla

    2016-10-01

    The joining of polymeric materials is a technology used in many industrial applications, from transport to telecommunications and the medical sector. A new technology for the joining of polymers is the laser welding process. In particular, fibre laser welding is a flexible technology which allows high process speed and the realization of good quality joints. Despite its application becoming more widespread in the production of assemblies of high precision, the application of laser technology for the welding of polymers has not been the subject of many studies up to now. This study focused on the welding of neutral polypropylene. The window process parameter was identified, without the use of additives to increase radiation absorption, and a mechanical characterization was conducted in order to evaluate the quality of the joints realized.

  3. Laser welding engineering

    International Nuclear Information System (INIS)

    Bhieh, N. M.; El Eesawi, M. E.; Hashkel, A. E.

    2007-01-01

    Laser welding was in its early life used mainly for unusual applications where no other welding process would be suitable that was twenty five years ago. Today, laser welding is a fully developed part of the metal working industry, routinely producing welds for common items such as cigarette lighters, which springs, motor/transformer lamination, hermetic seals, battery and pacemaker cans and hybrid circuit packages. Yet very few manufacturing engineering have seriously considers employing lasers in their own operations. Why? There are many reasons, but a main one must be not acquainted with the operation and capabilities of a laser system. Other reasons, such as a relatively high initial cost and a concern about using lasers in the manufacturing environment, also are frequently cited, and the complexity of the component and flexibility of the light delivery system. Laser welding could be used in place of many different standard processes, such as resistance (spot or seam), submerged arc, RF induction, high-frequency resistance, ultrasonic and electronic and electron-beam. while each of these techniques has established an independent function in the manufacturing world, the flexible laser welding approach will operate efficiently and economically in many different applications. Its flexibility will even permit the welding system to be used for other machining function, such as drilling, scribing, sealing and serializing. In this article, we will look at how laser welding works and what benefits it can offer to manufacturing engineers. Some industry observers state that there are already 2,000 laser machine tools being used for cutting, welding and drilling and that the number could reach 30,000 over the next 15 years as manufacturing engineers become more aware of the capabilities of lasers [1). While most laser applications are dedicated to one product or process that involves high-volume, long-run manufacturing, the flexibility of a laser to supply energy to hard

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

    Science.gov (United States)

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

    2013-12-01

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

  5. Fiber Laser Welding-Brazing Characteristics of Dissimilar Metals AZ31B Mg Alloys to Copper with Mg-Based Filler

    Science.gov (United States)

    Zhao, Xiaoye; Tan, Caiwang; Meng, Shenghao; Chen, Bo; Song, Xiaoguo; Li, Liqun; Feng, Jicai

    2018-03-01

    Fiber laser welding-brazing of 1-mm-thick AZ31B Mg alloys to 1.5-mm-thick copper (T2) with Mg-based filler was performed in a lap configuration. The weld appearance, interfacial microstructure and mechanical properties were investigated with different heat inputs. The results indicated that processing windows for optimizing appropriate welding parameters were relatively narrow in this case. Visually acceptable joints with certain strength were achieved at appropriate welding parameters. The maximum tensile-shear fracture load of laser-welded-brazed Mg/Cu joint could reach 1730 N at the laser power of 1200 W, representing 64.1% joint efficiency relative to AZ31Mg base metal. The eutectic structure (α-Mg + Mg2Cu) and Mg-Cu intermetallic compound was observed at the Mg/Cu interface, and Mg-Al-Cu ternary intermetallic compound were identified between intermetallics and eutectic structure at high heat input. All the joints fractured at the Mg-Cu interface. However, the fracture mode was found to differ. For laser power of 1200 W, the surface was characterized by tearing edge, while that with poor joint strength was almost dominated by smooth surface or flat tear pattern.

  6. Experimental and numerical investigation of temperature distribution and melt pool geometry during pulsed laser welding of Ti6Al4V alloy

    Science.gov (United States)

    Akbari, Mohammad; Saedodin, Seyfolah; Toghraie, Davood; Shoja-Razavi, Reza; Kowsari, Farshad

    2014-07-01

    This paper reports on a numerical and experimental investigation of laser welding of titanium alloy (Ti6Al4V) for modeling the temperature distribution to predict the heat affected zone (HAZ), depth and width of the molten pool. This is a transient three-dimensional problem in which, because of simplicity, the weld pool surface is considered flat. The complex physical phenomenon causing the formation of keyhole has not been considered. The temperature histories of welding process were studied. It was observed that the finite volume thermal model was in good agreement with the experimental data. Also, we predicted the temperature as a function of distance at different laser welding speeds and saw that at each welding speed, the temperature profile was decreased sharply in points close to the laser beam center, and then decreased slightly in the far region from the laser beam center. The model prediction error was found to be in the 2-17% range with most numerical values falling within 7% of the experimental values.

  7. Fiber Laser Welding-Brazing Characteristics of Dissimilar Metals AZ31B Mg Alloys to Copper with Mg-Based Filler

    Science.gov (United States)

    Zhao, Xiaoye; Tan, Caiwang; Meng, Shenghao; Chen, Bo; Song, Xiaoguo; Li, Liqun; Feng, Jicai

    2018-02-01

    Fiber laser welding-brazing of 1-mm-thick AZ31B Mg alloys to 1.5-mm-thick copper (T2) with Mg-based filler was performed in a lap configuration. The weld appearance, interfacial microstructure and mechanical properties were investigated with different heat inputs. The results indicated that processing windows for optimizing appropriate welding parameters were relatively narrow in this case. Visually acceptable joints with certain strength were achieved at appropriate welding parameters. The maximum tensile-shear fracture load of laser-welded-brazed Mg/Cu joint could reach 1730 N at the laser power of 1200 W, representing 64.1% joint efficiency relative to AZ31Mg base metal. The eutectic structure (α-Mg + Mg2Cu) and Mg-Cu intermetallic compound was observed at the Mg/Cu interface, and Mg-Al-Cu ternary intermetallic compound were identified between intermetallics and eutectic structure at high heat input. All the joints fractured at the Mg-Cu interface. However, the fracture mode was found to differ. For laser power of 1200 W, the surface was characterized by tearing edge, while that with poor joint strength was almost dominated by smooth surface or flat tear pattern.

  8. Multispot fiber laser welding

    DEFF Research Database (Denmark)

    Schutt Hansen, Klaus

    This dissertation presents work and results achieved in the field of multi beam fiber laser welding. The project has had a practical approach, in which simulations and modelling have been kept at a minimum. Different methods to produce spot patterns with high power single mode fiber lasers have...... been examined and evaluated. It is found that both diamond turned DOE’s in zinc sulphide and multilevel etched DOE’s (Diffractive Optical Elements) in fused silica have a good performance. Welding with multiple beams in a butt joint configuration has been tested. Results are presented, showing it has...

  9. Welding shape memory alloys with NdYAG lasers Soldadura de ligas de memória de forma com laser Nd-YAG

    Directory of Open Access Journals (Sweden)

    Luisa Quintino

    2012-09-01

    Full Text Available The demand of emerging joining techniques for shape memory alloys (SMA has become of great importance, as their functional properties namely shape memory effect (SME and superelasticity (SE present unique solutions for state-of-the-art applications. Welding of SMAs is a challenge due to the risk of reduced mechanical performance after laser processing. The wider application of these alloys in various sectors as aerospace, medical or electronic industry is hindered by the limitations in its processing. The need to weld SMAs to other materials is pressing for applications in the above referred sectors. In dissimilar joints the need to understand materials behavior is even more challenging since base materials have different physical properties leading to different heat flow, convection processes and residual stress distribution. The chemical composition across the weld pool varies and intermetallic compounds are formed. Research detailing the effects of laser processing on NiTi is essential to overcome many of these challenges. The objectives of the current study are to analyze the effects of laser welding in the weld shape of both similar and dissimilar joints of NiTi to stainless steel and titanium alloys.A procura de técnicas de ligação para ligas de memória de forma tem-se revetido de importância crescente, devido ao desenvolvimento de aplicações deste material com particulares propriedades de memória de forma e superelasticidade. A soldadura de ligas de memória de forma é um desafio devido ao risco de emporbrecimento das propriedades mecânicas depois do processamento laser. A aplicação alargarda destas ligas em vários sectores como o aeroespacial, medico ou electrónico é prejudicado pelas limitações de processamento. A necessidade de soldar ligas de memória de forma a outros materiais é premente para estes sectores. Em juntas dissimilares, o entendimento do comportamento dos materaias é um desafio ainda maior uma vez que

  10. Investigation and Optimization of Disk-Laser Welding of 1 mm Thick Ti-6Al-4V Titanium Alloy Sheets

    Directory of Open Access Journals (Sweden)

    Fabrizia Caiazzo

    2015-01-01

    Full Text Available Ti-6Al-4V joints are employed in nuclear engineering, civil industry, military, and space vehicles. Laser beam welding has been proven to be promising, thanks to increased penetration depth and reduction of possible defects of the welding bead; moreover, a smaller grain size in the fusion zone is better in comparison to either TIG or plasma arc welding, thus providing an increase in tensile strength of any welded structures. In this frame, the regression models for a number of crucial responses are discussed in this paper. The study has been conducted on 1 mm thick Ti-6Al-4V plates in square butt welding configuration; a disk-laser source has been used. A three-level Box-Behnken experimental design is considered. An optimum condition is then suggested via numerical optimization with the response surface method using desirability functions with proper weights and importance of constraints. Eventually, Vickers microhardness testing has been conducted to discuss structural changes in fusion and heat affected zone due to welding thermal cycles.

  11. Laser welding of sheet metals

    Science.gov (United States)

    Xie, Jian

    Laser welding of sheet metals is an important application of high power lasers, and has many advantages over conventional welding techniques. Laser welding has a great potential to replace other welding technique in the car-body manufacturing because of high laser weld quality and relatively low manufacturing cost associated with the laser technique. However, a few problems related to the laser welding of sheet metals limit its applications in industries. To have a better understanding of the welding process, laser welding experimental studies and theoretical analysis are necessary. Temperature-dependent absorptivities of various metals are obtained theoretically for COsb2, COIL (Chemical Oxygen-Iodine Laser) and Nd:YAG lasers. It is found that the absorptivities for COIL and Nd:YAG lasers are 2.84 and 3.16 times higher than for the COsb2 laser, and the absorptivity increases with increasing temperature of the metals. Surface roughness and oxide films can enhance the absorption significantly. The reflectivity of as-received steel sheets decreases from 65-80% to 30-40% with surface oxide films for COsb2 lasers. Laser welding experiments show that the tensile strengths of the weld metals are higher than the base metals. For samples with surface oxide films, the oxygen concentration in the weld metals is found to be higher than in the specimens without oxidation, and the toughness of the weld metals is degraded. When steel powders are added to bridge the gap between two sheets, the oxygen content in the weld metals decreases and the toughness increases. A mathematical model is developed for the melt depth due to a stationary laser beam. The model results show that the melt depth increases rapidly with time at the beginning of laser irradiation and then increases slowly. Also, the melt depth is found to increase rapidly with laser intensities and then increases slowly for higher intensity. The average rate of melting and the times to reach the melting and boiling

  12. Coaxial monitoring of keyhole during Yb:YAG laser welding

    Science.gov (United States)

    Kim, Cheol-Hee; Ahn, Do-Chang

    2012-09-01

    In laser remote welding using a scanner, high-speed welding can be achieved by using a 6-axial robot and a galvanometric mirror. In this system, because the laser projection point changes depending on the mirror's position, coaxial monitoring is required to track welding phenomena. This paper presents coaxial monitoring of the keyhole generated by an Yb:YAG laser beam during laser lap welding of steel and Al sheets. A coaxial image camera and a coaxial illumination laser are integrated into the proposed monitoring system. The areas of the keyhole and the full penetration hole were calculated by image processing, and their behaviours were investigated under various welding conditions. The keyhole was monitored using various band-pass filters and a coaxial illumination laser. Adequate filters were suggested for steel and Al alloy welding.

  13. Laser weld jig. [Patent application

    Science.gov (United States)

    Van Blarigan, P.; Haupt, D.L.

    1980-12-05

    A system is provided for welding a workpiece along a predetermined weld line that may be of irregular shape, which includes the step of forming a lip on the workpiece to extend parallel to the weld line, and moving the workpiece by engaging the lip between a pair of rotatable members. Rotation of one of the members at a constant speed, causes the workpiece to move so that all points on the weld line sequentially pass a fixed point in space at a constant speed, so that a laser welding beam can be directed at that fixed point to form a weld along the weld line. The workpiece can include a reusable jig forming the lip, and with the jig constructed to detachably hold parts to be welded at a position wherein the weld line of the parts extends parallel to the lip on the jig.

  14. Effects of Surface Alloying and Laser Beam Treatment on the Microstructure and Wear Behaviour of Surfaces Modified Using Submerged Metal Arc Welding

    Directory of Open Access Journals (Sweden)

    Regita BENDIKIENE

    2016-05-01

    Full Text Available In this study, the effects of surface alloying of cheap plain carbon steel using submerged metal arc technique and subsequent laser beam treatment on the microstructure and wear behaviour of surfaced layers were studied. This method is the cheapest one to obtain high alloyed coatings, because there is no need to apply complex technologies of powder making (metal powder is spread on the surface of base metal or inserted into the flux, it is enough to grind, granulate and blend additional materials. On the other hand, strengthening of superficial layers of alloys by thermal laser radiation is one of the applications of laser. Surface is strengthened by concentrated laser beam focused into teeny area (from section of mm till some mm. Teeny area of metal heat up rapidly and when heat is drain to the inner metal layers giving strengthening effect. Steel surface during this treatment exceeds critical temperatures, if there is a need to strengthen deeper portions of the base metal it is possible even to fuse superficial layer. The results presented in this paper are based on micro-structural and micro-chemical analyses of the surfaced and laser beam treated surfaces and are supported by analyses of the hardness, the wear resistance and resultant microstructures. Due to the usage of waste raw materials a significant improvement (~ 30 % in wear resistance was achieved. The maximum achieved hardness of surfaced layer was 62 HRC, it can be compared with high alloyed conventional steel grade. Wear properties of overlays with additional laser beam treatment showed that weight loss of these layers was ~10 % lower compared with overlays after welding; consequently it is possible to replace high alloyed conventional steel grades forming new surfaces or restoring worn machine elements and tools.DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7621

  15. Laser welding of tailored blanks

    International Nuclear Information System (INIS)

    Pecas, P.; Gouveia, H.; Quintino, L.; Olsen, F.O.

    1998-01-01

    Laser welding has an increasing role in the automotive industry, namely on the sub-assemblies manufacturing. Several sheet-shape parts are laser welded, on a dissimilar combination of thicknesses and materials, and are afterwards formed (stamped) being transformed in a vehicle body component. In this paper low carbon CO 2 laser welding, on the thicknesses of 1,25 and 0.75 mm, formability investigation is described. There will be a description of how the laser welded blanks behave in different forming tests, and the influence of misalignment and undercut on the formability. The quality is evaluated by measuring the limit strain and limit effective strain for the laser welded sheets and the base material, which will be presented in a forming limit diagram. (Author) 14 refs

  16. Study of Gravity Effects on Titanium Laser Welding in the Vertical Position

    Directory of Open Access Journals (Sweden)

    Baohua Chang

    2017-09-01

    Full Text Available To obtain satisfactory welds in positional laser beam welding, it is necessary to know how process parameters will influence the quality of welds in different welding positions. In this study, the titanium alloy Ti6Al4V sheets were laser welded in two vertical welding positions (vertical up and vertical down, and the appearance, porosity, strength, and ductility of the laser joints were evaluated. Results show that undercuts of the vertical up welds were greater than that of vertical down welds, while the porosity contents were much higher in vertical down welds than that in vertical up welds. When welding with a higher heat input, the vertical up welding position resulted in poor weld profiles (undercuts and burn-through holes, whereas the vertical down welding position led to excessive porosity contents in welds. Both severe undercut and excessive porosity were detrimental to the tensile properties of the welds. Weld appearance was improved and porosity contents were reduced by using a lower heat input, achieving better weld quality. Therefore, it is suggested that process parameter settings with relatively high laser powers and welding speeds, which can result in lower heat inputs, are used when laser welding the Ti6Al4V titanium alloys vertically.

  17. Intraoral laser welding: ultrastructural and mechanical analysis to compare laboratory laser and dental laser.

    Science.gov (United States)

    Fornaini, Carlo; Passaretti, Francesca; Villa, Elena; Rocca, Jean-Paul; Merigo, Elisabetta; Vescovi, Paolo; Meleti, Marco; Manfredi, Maddalena; Nammour, Samir

    2011-07-01

    The Nd:YAG laser has been used since 1970 in dental laboratories to weld metals on dental prostheses. Recently in several clinical cases, we have suggested that the Nd:YAG laser device commonly utilized in the dental office could be used to repair broken fixed, removable and orthodontic prostheses and to weld metals directly in the mouth. The aim of this work was to evaluate, using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and dynamic mechanical analysis (DMA), the quality of the weld and its mechanical strength, comparing a device normally used in dental laboratory and a device normally used in the dental office for oral surgery, the same as that described for intraoral welding. Metal plates of a Co-Cr-Mo dental alloy and steel orthodontic wires were subjected to four welding procedures: welding without filler metal using the laboratory laser, welding with filler metal using the laboratory laser, welding without filler metal using the office laser, and welding with filler metal using the office laser. The welded materials were then analysed by SEM, EDS and DMA. SEM analysis did not show significant differences between the samples although the plates welded using the office laser without filler metal showed a greater number of fissures than the other samples. EDS microanalysis of the welding zone showed a homogeneous composition of the metals. Mechanical tests showed similar elastic behaviours of the samples, with minimal differences between the samples welded with the two devices. No wire broke even under the maximum force applied by the analyser. This study seems to demonstrate that the welds produced using the office Nd:YAG laser device and the laboratory Nd:YAG laser device, as analysed by SEM, EDS and DMA, showed minimal and nonsignificant differences, although these findings need to be confirmed using a greater number of samples.

  18. Double-sided laser beam welded T-joints for aluminum-lithium alloy aircraft fuselage panels: Effects of filler elements on microstructure and mechanical properties

    Science.gov (United States)

    Han, Bing; Tao, Wang; Chen, Yanbin; Li, Hao

    2017-08-01

    In the current work, T-joints consisting of 2.0 mm thick 2060-T8/2099-T83 aluminum-lithium alloys for aircraft fuselage panels have been fabricated by double-sided fiber laser beam welding with different filler wires. A new type wire CW3 (Al-6.2Cu-5.4Si) was studied and compared with conventional wire AA4047 (Al-12Si) mainly on microstructure and mechanical properties. It was found that the main combined function of Al-6.2%Cu-5.4%Si in CW3 resulted in considerable improvements especially on intergranular strength, hot cracking susceptibility and hoop tensile properties. Typical non-dendritic equiaxed zone (EQZ) was observed along welds' fusion boundary. Hot cracks and fractures during the load were always located within the EQZ, however, this typical zone could be restrained by CW3, effectively. Furthermore, changing of the main intergranular precipitated phase within the EQZ from T phase by AA4047 to T2 phase by CW3 also resulted in developments on microscopic intergranular reinforcement and macroscopic hoop tensile properties. In addition, bridging caused by richer substructure dendrites within CW3 weld's columnar zone resulted in much lower hot cracking susceptibility of the whole weld than AA4047.

  19. Assessment of Hot Crack Properties of Laser Welded Stainless Steel

    DEFF Research Database (Denmark)

    Juhl, Thomas Winther; Olsen, Flemming Ove

    2003-01-01

    Crack testing concerning small and fast solidifying laser welds in austenitic stainless steel has been studied. A set of methods has been applied to investigate alloy properties, including (1) Application of known information to predict solidification phases, (2) Weld metal solidification rate me...

  20. The microstructure and mechanical properties of a welded molybdenum alloy

    International Nuclear Information System (INIS)

    Wadsworth, J.; Morse, G.R.; Chewey, P.M.

    1983-01-01

    Wrought Ti-Zr-Mo (TZM) alloy has been welded using electron beam, laser and tungsten-inert gas welding techniques. The microstructure, tensile properties and fracture surfaces of these welded samples have been examined. Although the welds have been found to be defect free, a disparity in grain size leading to large strength differences exists between the weld and parent metal. Tensile tests have revealed that fusion zone strengths are typical of those expected for the grain size in the weld metal. However, brittle behavior is also always observed, with fracture initiating at grain boundaries and propagating by intergranular and cleavage modes. Auger electron spectroscopy analysis has eliminated oxygen or other interstitial elements as sources of grain boundary embrittlement. It is proposed that brittle behavior is a result of local high strain rates in the weld zone. These local high strain rates arise from the strength difference between the wrought parent metal and the weld metal as a result of the strong grain size dependence of TZM. It is shown that, either by reducing the strain rate of testing or by removing the grain size difference between the parent and weld metals by heat treatment, significant ductility can in fact be achieved in tensile-tested butt-welded TZM. Thus, it is proposed that TZM welds are not inherently brittle as had commonly been believed. (Auth.)

  1. Sensor integration for robotic laser welding processes

    NARCIS (Netherlands)

    Iakovou, D.; Aarts, Ronald G.K.M.; Meijer, J.; Ostendorf, A; Hoult, A.; Lu, Y.

    2005-01-01

    The use of robotic laser welding is increasing among industrial applications, because of its ability to weld objects in three dimensions. Robotic laser welding involves three sub-processes: seam detection and tracking, welding process control, and weld seam inspection. Usually, for each sub-process,

  2. Integrated sensors for robotic laser welding

    NARCIS (Netherlands)

    Iakovou, D.; Aarts, Ronald G.K.M.; Meijer, J.; Beyer, E.; Dausinger, F; Ostendorf, A; Otto, A.

    2005-01-01

    A welding head is under development with integrated sensory systems for robotic laser welding applications. Robotic laser welding requires sensory systems that are capable to accurately guide the welding head over a seam in three-dimensional space and provide information about the welding process as

  3. Fundamental Laser Welding Process Investigations

    DEFF Research Database (Denmark)

    Bagger, Claus; Olsen, Flemming Ove

    1998-01-01

    In a number of systematic laboratory investigations the fundamental behavior of the laser welding process was analyzed by the use of normal video (30 Hz), high speed video (100 and 400 Hz) and photo diodes. Sensors were positioned to monitor the welding process from both the top side and the rear...... side of the specimen.Special attention has been given to the dynamic nature of the laser welding process, especially during unstable welding conditions. In one series of experiments, the stability of the process has been varied by changing the gap distance in lap welding. In another series...... video pictures (400 Hz), a clear impact on the seam characteristics has been identified when a hump occurs.Finally, a clear correlation between the position of the focus point, the resultant process type and the corresponding signal intensity and signal variation has been found for sheets welded...

  4. Metals welding by using laser

    International Nuclear Information System (INIS)

    Al-Qaisy, R.A.W.

    1991-01-01

    In the present work, same welding ''conduction limited type'' under atmospheric conditions was performed using pulsed Ng:YAG laser to weld; low carbon steel (LCS), stainless steel (304) (SUS304), stainless steel (303) (SUS303), and brass. Microstructure of welded zone, heat affected zone (HAZ), and the laser energy on penetration depth and effective diameter were studied. Tensile test, micro-hardness, and surface roughness of welded and parent metals were also dealt with. Melting efficiency was worked out and an under vacuum seam welding of low carbon steel has been accomplished. Finally spot welding of aluminium tungsten, and platinium wires were employed using different layer energies. 34 tabs.; 82 figs.; 51 refs.; 1 app

  5. Friction Stir Welding of Steel Alloys

    Science.gov (United States)

    Ding, R. Jeffrey; Munafo, Paul M. (Technical Monitor)

    2001-01-01

    The friction stir welding process has been developed primarily for the welding of aluminum alloys. Other higher melting allows such, as steels are much more difficult to join. Special attention must be given to pin tool material selection and welding techniques. This paper addresses the joining of steels and other high melting point materials using the friction stir welding process. Pin tool material and welding parameters will be presented. Mechanical properties of weldments will also be presented. Significance: There are many applications for the friction stir welding process other than low melting aluminum alloys. The FSW process can be expanded for use with high melting alloys in the pressure vessel, railroad and ship building industries.

  6. METHOD AND SYSTEM FOR LASER WELDING

    DEFF Research Database (Denmark)

    2008-01-01

    The invention relates to laser welding of at least two adjacent, abutting or overlapping work pieces in a welding direction using multiple laser beams guided to a welding region, wherein at least two of the multiple laser beams are coupled into the welding region so as to form a melt and at least...

  7. Hybrid laser-arc welding

    DEFF Research Database (Denmark)

    building and the automotive industry. With its distinguished editor and international team of contributors, Hybrid laser-arc welding, will be a valuable source of reference for all those using this important welding technology. Professor Flemming Ove Olsen works in the Department of Manufacturing...

  8. Effect of Pre/Post T6 Heat Treatment on the Mechanical Properties of Laser Welded SSM Cast A356 Aluminium Alloy

    CSIR Research Space (South Africa)

    Akhter, R

    2007-02-01

    Full Text Available HT) were butt welded, using an Nd: YAG laser. In another experiment, as cast welded samples were heat treated to T6 condition (post HT). The base metal and weld microstructures were presented. The effect of heat treatments on microstructure...

  9. Polyimide weld bonding for titanium alloy joints

    Science.gov (United States)

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

    1974-01-01

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

  10. Weld pool control in ND: YAG laser Welding

    NARCIS (Netherlands)

    Postma, S.

    2003-01-01

    During laser welding small parameter variations can result in defects and loss of quality in the weld. An important quality in Tailor Made Blanks is the weld depth. In this thesis a number of feedback control strategies are developed to control the weld depth on-line.

  11. Fundamental Laser Welding Process Investigations

    DEFF Research Database (Denmark)

    Bagger, Claus; Olsen, Flemming Ove

    1998-01-01

    In a number of systematic laboratory investigations the fundamental behavior of the laser welding process was analyzed by the use of normal video (30 Hz), high speed video (100 and 400 Hz) and photo diodes. Sensors were positioned to monitor the welding process from both the top side and the rear...... side of the specimen.Special attention has been given to the dynamic nature of the laser welding process, especially during unstable welding conditions. In one series of experiments, the stability of the process has been varied by changing the gap distance in lap welding. In another series...... of normal video and high speed video (100 Hz) can not reveal any instability in the process when humping occurs. Contrary to this, photo diode signals (sampled at 3 kHz) clearly indicate a characteristic signal when humps occur.When the seam area and seam width have manually been measured on high speed...

  12. Computerized simulation of YAG pulse laser welding of titanium alloy (TA6V): experimental characterization and modelling of the thermomechanical aspects of this process; Simulation numerique du soudage du TA6V par laser YAG impulsionnel: caracterisation experimentale et modelisation des aspects thermomecanique associees a ce procede

    Energy Technology Data Exchange (ETDEWEB)

    Robert, Y

    2007-09-15

    This work is a part of study which goal is to realize a computer modelling of the thermomechanical phenomena occurring during the YAG pulse laser welding of titanium alloy (TA6V). The filet welding has different heterogeneities (microstructural and mechanical). In fact, the temperature causes microstructural changes (phase transformations, precipitations) and modifies the mechanical properties. Thermomechanical modelling has thus to be established for the welding of TA6V. (author)

  13. Laser welding of fused quartz

    Science.gov (United States)

    Piltch, Martin S.; Carpenter, Robert W.; Archer, III, McIlwaine

    2003-06-10

    Refractory materials, such as fused quartz plates and rods are welded using a heat source, such as a high power continuous wave carbon dioxide laser. The radiation is optimized through a process of varying the power, the focus, and the feed rates of the laser such that full penetration welds may be accomplished. The process of optimization varies the characteristic wavelengths of the laser until the radiation is almost completely absorbed by the refractory material, thereby leading to a very rapid heating of the material to the melting point. This optimization naturally occurs when a carbon dioxide laser is used to weld quartz. As such this method of quartz welding creates a minimum sized heat-affected zone. Furthermore, the welding apparatus and process requires a ventilation system to carry away the silicon oxides that are produced during the welding process to avoid the deposition of the silicon oxides on the surface of the quartz plates or the contamination of the welds with the silicon oxides.

  14. MODELLING AND CHARACTERIZATION OF LASER WELDED INCOLOY 800 HT JOINTS

    Directory of Open Access Journals (Sweden)

    Sathiya Paulraj

    2016-06-01

    Full Text Available This study aims at finding the effect of laser welding speed on incoloy 800 HT. This alloy is one of the potential materials for Generation IV nuclear plants. Laser welding has several advantages over arc welding such as low fusion zone, low heat input and concentrated heat intensity. Three different welding speeds were chosen and CO2 laser welding was performed. 2D modeling and simulation were done using ANSYS 15 to find out the temperature distribution at different welding speeds and it was found that an increase in the welding speed decreased the temperature. Mechanical properties such as tensile strength, toughness and hardness were evaluated. The effect of welding speed on metallurgical characteristics was studied using optical microscopy (OM, Scanning Electron Microscopy (SEM with EDS, X-Ray Diffraction (XRD technique and fractographic analysis. From the results it was found that high welding speed (1400 mm/min decreased the joint strength. The M23C6 and Ni3Ti carbides were formed in a discrete chain and in a globular form along the grain boundaries of the weld region which increased the strength of the grain boundaries. Fractographic evaluations of the tested specimens for welding speed (1000 and 1200 mm/min showed deep and wide dimples indicating ductile failures.

  15. Investigation on fracture toughness of laser beam welded steels

    Energy Technology Data Exchange (ETDEWEB)

    Riekehr, S.; Cam, G.; Santos, J.F. dos; Kocak, M. [GKSS-Forschungszentrum Geesthacht GmbH (Germany); Klein, R.M.; Fischer, R. [Thyssen Laser-Technik GmbH, Aachen (Germany)

    1999-11-01

    Laser beam welding is currently used in the welding of a variety of structural materials including hot and cold rolled steels, high strength low alloy and stainless steels, aluminium and titanium alloys, refractory and high temperature alloys and dissimilar materials. This high power density welding process has unique advantages of cost effectiveness, low distortion, high welding speed, easy automation, deep penetration, narrow bead width, and narrow HAZ compared to the conventional fusion welding processes. However, there is a need to understand the deformation and fracture properties of laser beam weld joints in order to use this cost effective process for fabrication of structural components fully. In the present study, an austenitic stainless steel, X5CrNi18 10 (1.4301) and a ferritic structural steel, RSt37-2 (1.0038), with a thickness of 4 mm were welded by 5 kW CO{sub 2} laser process. Microhardness measurements were conducted to determine the hardness profiles of the joints. Flat microtensile specimens were extracted from the base metal, fusion zone, and heat affected zone of ferritic joint to determine the mechanical property variation across the joint and the strength mismatch ratio between the base metal and the fusion zone. Moreover, fracture mechanics specimens were extracted from the joints and tested at room temperature to determine fracture toughness, Crack Tip Opening Displacement (CTOD), of the laser beam welded specimens. The effect of the weld region strenght mis-matching on the fracture toughness of the joints have been evaluated. Crack initiation, crack growth and crack deviation processes have also been examined. These results were used to explain the influence of mechanical heterogeneity of the weld region on fracture behaviour. This work is a part of the ongoing Brite-Euram project Assessment of Quality of Power Beam Weld Joints (ASPOW). (orig.)

  16. Microstructure characteristics of laser MIG hybrid welded mild steel

    Science.gov (United States)

    Gao, Ming; Zeng, Xiaoyan; Yan, Jun; Hu, Qianwu

    2008-07-01

    To deepen the understanding of laser-arc hybrid welding, the weld shape and microstructure characteristics of laser-metal inert gas hybrid welded mild steel were analyzed. The results showed typical hybrid weld could be classified as two parts: the wide upper zone and the narrow nether zone, which were defined as arc zone and laser zone, respectively. In the hybrid weld, the microstructure, alloy element distribution and microhardness all have evident difference between laser zone and arc zone. The microstructure of arc zone consists of coarse columnar dendrite and fine acicular dendrite between the columnar dendrites, but that of laser zone is composed of fine equiaxed dendrite in weld center and columnar dendrite around the equiaxed dendrite. Compared to arc zone, laser zone has finer grain size, higher microhardness, smaller alloy element content in the fusion zone and narrower heat affected zone. The discussions demonstrated that the observed difference was caused by the difference of temperature gradient, crystallizing and the effects of arc pressure on the molten pool between laser zone and arc zone.

  17. Mechanical properties of friction stir welded aluminum alloys 5083 and 5383

    Directory of Open Access Journals (Sweden)

    Jeom Kee Paik

    2009-09-01

    Full Text Available The use of high-strength aluminum alloys is increasing in shipbuilding industry, particularly for the design and construction of war ships, littoral surface craft and combat ships, and fast passenger ships. While various welding methods are used today to fabricate aluminum ship structures, namely gas metallic arc welding (GMAW, laser welding and friction stir welding (FSW, FSW technology has been recognized to have many advantages for the construction of aluminum structures, as it is a low-cost welding process. In the present study, mechanical properties of friction stir welded aluminum alloys are examined experimentally. Tensile testing is undertaken on dog-bone type test specimen for aluminum alloys 5083 and 5383. The test specimen includes friction stir welded material between identical alloys and also dissimilar alloys, as well as unwelded (base alloys. Mechanical properties of fusion welded aluminum alloys are also tested and compared with those of friction stir welded alloys. The insights developed from the present study are documented together with details of the test database. Part of the present study was obtained from the Ship Structure Committee project SR-1454 (Paik, 2009, jointly funded by its member agencies.

  18. Mechanical Properties of Friction Stir Welded Aluminum Alloys 5083 and 5383

    Science.gov (United States)

    Paik, Jeoom Kee

    2009-09-01

    The use of high-strength aluminum alloys is increasing in shipbuilding industry, particularly for the design and construction of war ships, littoral surface craft and combat ships, and fast passenger ships. While various welding methods are used today to fabricate aluminum ship structures, namely gas metallic arc welding (GMAW), laser welding and friction stir welding (FSW), FSW technology has been recognized to have many advantages for the construction of aluminum structures, as it is a low-cost welding process. In the present study, mechanical properties of friction stir welded aluminum alloys are examined experimentally. Tensile testing is undertaken on dog-bone type test specimen for aluminum alloys 5083 and 5383. The test specimen includes friction stir welded material between identical alloys and also dissimilar alloys, as well as unwelded (base) alloys. Mechanical properties of fusion welded aluminum alloys are also tested and compared with those of friction stir welded alloys. The insights developed from the present study are documented together with details of the test database. Part of the present study was obtained from the Ship Structure Committee project SR-1454 (Paik, 2009), jointly funded by its member agencies

  19. Laser based spot weld characterization

    Science.gov (United States)

    Jonietz, Florian; Myrach, Philipp; Rethmeier, Michael; Suwala, Hubert; Ziegler, Mathias

    2016-02-01

    Spot welding is one of the most important joining technologies, especially in the automotive industry. Hitherto, the quality of spot welded joints is tested mainly by random destructive tests. A nondestructive testing technique offers the benefit of cost reduction of the testing procedure and optimization of the fabrication process, because every joint could be examined. This would lead to a reduced number of spot welded joints, as redundancies could be avoided. In the procedure described here, the spot welded joint between two zinc-coated steel sheets (HX340LAD+Z100MB or HC340LA+ZE 50/50) is heated optically on one side. Laser radiation and flash light are used as heat sources. The melted zone, the so called "weld nugget" provides the mechanical stability of the connection, but also constitutes a thermal bridge between the sheets. Due to the better thermal contact, the spot welded joint reveals a thermal behavior different from the surrounding material, where the heat transfer between the two sheets is much lower. The difference in the transient thermal behavior is measured with time resolved thermography. Hence, the size of the thermal contact between the two sheets is determined, which is directly correlated to the size of the weld nugget, indicating the quality of the spot weld. The method performs well in transmission with laser radiation and flash light. With laser radiation, it works even in reflection geometry, thus offering the possibility of testing with just one-sided accessibility. By using heating with collimated laser radiation, not only contact-free, but also remote testing is feasible. A further convenience compared to similar thermographic approaches is the applicability on bare steel sheets without any optical coating for emissivity correction. For this purpose, a proper way of emissivity correction was established.

  20. Review of laser hybrid welding

    DEFF Research Database (Denmark)

    Bagger, Claus

    2004-01-01

    In this artucle an overview og the hybrid welding process is given. After a short historic overview, a review of the fundamental phenomenon taking place when a laser (CO2 or Nd:YAG) interacts in the same molten pool as a more conventional source of energy, e.g. tungsten in-active gas, plasma......, or metal inactive gas/metal active gas.This is followed by reports of how the many process parameters governing the hybrid welding process can be set and how the choice of secondary energy source, shielding gas, etc. can affect the overall welding process....

  1. Friction Pull Plug Welding in Aluminum Alloys

    Science.gov (United States)

    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.

  2. Bringing Pulsed Laser Welding into Production

    DEFF Research Database (Denmark)

    Olsen, Flemmming Ove

    1996-01-01

    performed and is currently in progress in collaboration with a major Danish company, who currently is applying laser welding in several production lines. Furthermore some case stories from development work on laser welding for industri-al production will be described. One case story describes a current...... production of hermetic weld seams produced on radiator thermostats applying pulsed laser welding. This application has now been running in several years. 2 laser systems are currently welding each serving two welding stations. Another case story is describing a high precision assembly technique of a product......-nationally the group is mostly known for its contri-butions to the development of the laser cutting process, but further it has been active within laser welding, both in assisting industry in bringing laser welding into production in several cases and in performing fundamental R & D. In this paper some research...

  3. [Cytotoxicitic detection of laser welding between NiTi shape memory alloy and stainless steel in vitro].

    Science.gov (United States)

    Yu, Wenwen; Zhang, Chao; Zhang, Bing; Liu, Jiming; Sun, Xinhua

    2014-04-01

    To investigate the cytotoxicity of laser-welded nickel titanium (NiTi) and stainless steel composite archwire. The NiTi and stainless steel composite archwire (CoAW) laser-welded with pure copper inrerplayer was studied with methyl thiazolyl tetrazolium (MTT) test in vitro. The cytotoxicity of CoAW was compared with stainless steel archwire and NiTi archwire. Two tests were carried out. Test 1: the immersed solution of CoAW was diluted to five grades (50%, 40%, 30%, 20%, 10%). The cytotoxicity in vitro of these agents was assayed on murine fibroblast cell L929 line with MTT test at 24 and 48 hours. Test 2: the immeresed solution of CoAW, NiTi archwires and stainless steel archwires was diluted to four grads (100%, 75%, 50%, 25%). The cytotoxity of three kinds of material was compared at 48 hours. The results of all samples revealed level 0-1 cytotoxicity. In test 1, the same grade solution optical density (except 20%) at 24 hours was statistically lower than at 48 hours. In test 2, the optical density of CoAW solution (1.964 ± 0.122, 2.084 ± 0.056, 2.056 ± 0.071, 2.096 ± 0.050) was statistically lower than the same grade solution of stainless steel archwire (2.168 ± 0.091, 2.227 ± 0.160, 2.302 ± 0.052, 2.301 ± 0.060) and NiTi archwire (2.138 ± 0.105, 2.262 ± 0.050, 2.271 ± 0.082, 2.294 ± 0.056) (P NiTi archwires. However, CoAW belonged to secure rang of material toxicity reaction.

  4. Corrosion Properties of Laser Welded Stainless Steel

    DEFF Research Database (Denmark)

    Weldingh, Jakob; Olsen, Flemmming Ove

    1997-01-01

    In this paper the corrosion properties of laser welded AISI 316L stainless steel are examined. A number of different welds has been performed to test the influence of the weld parameters of the resulting corrosion properties. It has been chosen to use the potential independent critical pitting...... temperature (CPT) test as corrosion test. The following welding parameters are varied: Welding speed, lsser power, focus point position and laser operation mode (CW or pulsed)....

  5. Microstructure evolution in the fusion zone of laser-welded Mg–Gd–Y–Zr alloy during solution and aging treatment

    International Nuclear Information System (INIS)

    Wang, Lyuyuan; Huang, Jian; Dong, Jie; Feng, Kai; Wu, Yixiong; Chu, Paul K.

    2016-01-01

    The microstructure evolution in the fusion zone of laser-welded Mg-Gd-Y-Zr alloy during solution and aging treatment is investigated. The morphology of the Mg 24 (Gd,Y) 5 in the divorced eutectic at the grain boundary transforms from a continuous network to disconnected and fragmentized islands and then to spheroidal particles before complete dissolution during the solution treatment at 430 °C. During the subsequent aging treatment at 225 °C, the precipitation sequence in the fusion zone follows the order of supersaturated solid solution (SSSS) → βʺ(D0 19 ) → βʹ(cbco) → β 1 (fcc) → β(fcc). High-density precipitates are present at the original grain boundaries of the fusion zone from the welded structure but there are less precipitates in the interior of the original grains. The grain growth during the solution treatment at 430 °C comprises the slowly increasing stage, rapidly increasing stage, and stable stage. The network-distributed Mg 24 (Gd,Y) 5 impedes migration of the grain boundaries, restricts grain growth in the first slowly increasing stage, and segregation of zirconium near the grain boundaries also affects migration of the grain boundaries. - Highlights: •Different quantities of precipitates are present at different location of grain. •The network-distributed Mg 24 (Gd,Y) 5 restricts grain growth. •Segregation of Zr affects migration of grain boundaries.

  6. Repairing method of fixed partial prostheses in dentistry: laser welding

    Science.gov (United States)

    Negrutiu, Meda L.; Sinescu, Cosmin; Cozarov, Dalibor; Culea, Laurentiu; Rominu, Mihai; Pop, Daniela M.

    2008-02-01

    Laser Welding is an advantageous method of connecting or repairing metal prosthetic frameworks because there are fewer effects of heating on the area surrounding the spot to be welded, and no further procedures, such as those used for conventional soldering, are necessary. Laser welding has been increasingly applied for fabricating the metal frameworks of prostheses and for other procedures, such as recovering the metal ridge and cusp, blocking holes on the occlusal surfaces after excess occlusal adjustment, thickening the metal framework, or adding contact points after excess grinding and adjusting of the crown margins. The objective of this study are represented by investigation and evaluation of three types of soldering compare to laser welding. The method is represented by the laser welding with a pulsed Nd-Yag Laser equipment. Other joints were produced, using three different soldering techniques. These joining areas were investigated for their quality and their corrosion properties. Corrosion attack was confirmed by electron microscopy. The investigations confirm the quality of laser welding. The investigated different laser welding methods revealed minimal corrosion and offers clear-cut advantages compared to the other soldering methods. Dental alloys are subjected to functional influences in the oral cavity and interact with the intraoral enviroment.

  7. Laser welding of tailored blanks

    Directory of Open Access Journals (Sweden)

    Peças, P.

    1998-04-01

    Full Text Available Laser welding has an incrising role in the automotive industry, namely on the sub-assemblies manufacturing. Several sheet-shape parts are laser welded, on a dissimilar combination of thicknesses and materials, and are afterwards formed (stamped being transformed in a vehicle body component. In this paper low carbon CO2 laser welding, on the thicknesses of 1,25 and 0,75 mm, formability investigation is described. There will be a description of how the laser welded blanks behave in different forming tests, and the influence of misalignment and undercut on the formibility. The quality is evaluated by measuring the limit strain and limit effective strain for the laser welded sheets and the base material, which will be presented in a forming limit diagram.

    A soldadura laser assume um papel cada vez mais importante na indústria automóvel, principalmente para a fabricação de sub-conjuntos constituídos por varias partes de chapa de diferentes espessuras (e diferentes materiais, que depois de estampados constituem um componente para integrar num veículo. Descreve-se neste artigo o trabalho de investigação de enformabilidade de chapa de ac.o de baixo carbono soldada por laser de CO2, nas espessuras de 1,25 e 0,75 mm. Apresenta-se uma descrição do comportamento das chapas soldadas por laser em diferentes testes de enformação, e a influência dos defeitos das soldaduras (desalinhamento e queda do banho-undercut no comportamento à enformação. A qualidade é avaliada pela medição da extensão limite e da extensão limite efectiva no material base e no material soldado, que serão representadas num diagrama de limite de enformabilidade.

  8. Friction stir welding of 6061 aluminium alloy

    International Nuclear Information System (INIS)

    Abdel Rahman, M.A.M.S.

    2009-01-01

    6061 AA (Al-Mg-Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to-weight ratio and good corrosion resistance such as marine frames, pipelines, storage tanks, and aircraft components [1]. It is also used for the manufacturing of fuel elements in the nuclear research reactors. Compared to many of the fusion welding processes that are routinely used for joining structural alloys, friction stir welding (FSW) is a solid state joining process in which the material that is being welded is not melted and recast [2]. The welding parameters such as tool rotational speed, welding traverse speed, and tool profile play a major role in deciding the weld quality. Several FSW tools (differ from each other in pin angle, shoulder diameter, and shoulder concavity) have been used to fabricate a number of joints in order to obtain a tool with which a sound weld can be produced. It was found that the FSW tool with tapered cone pin, concave shoulder, and shoulder diameter equal to four times the welded plate thickness is suitable to produce a sound weld. The effect of the traverse speed on the global and local tensile properties of friction stir welded joints has been investigated in the 6061-T6 AA. The global tensile properties of the FSW joints were improved with increasing the traverse speed at constant rotation rate. It is found that the global tensile strength of the FSW joint is limited by the local tensile strength of the nearest region to the weld center at which the cross section is composed mainly of the HAZ. The effect of the initial butt surface on the formation of the zigzag line on the tensile properties of the welds was examined by using three types of welding samples differ in the preparation of the initial butt surface. The first type of samples welded without removing the oxide layer from the initial butt surface (uncleaned butt surfaces joint). In the second type of samples the oxide layer was removed from

  9. Modified section method for laser-welding of ill-fitting cp Ti and Ni-Cr alloy one-piece cast implant-supported frameworks.

    Science.gov (United States)

    Tiossi, R; Falcão-Filho, H; Aguiar Júnior, F A; Rodrigues, R C; Mattos, M da G; Ribeiro, R F

    2010-05-01

    This study aimed to verify the effect of modified section method and laser-welding on the accuracy of fit of ill-fitting commercially pure titanium (cp Ti) and Ni-Cr alloy one-piece cast frameworks. Two sets of similar implant-supported frameworks were constructed. Both groups of six 3-unit implant-supported fixed partial dentures were cast as one-piece [I: Ni-Cr (control) and II: cp Ti] and evaluated for passive fitting in an optical microscope with both screws tightened and with only one screw tightened. All frameworks were then sectioned in the diagonal axis at the pontic region (III: Ni-Cr and IV: cp Ti). Sectioned frameworks were positioned in the matrix (10-Ncm torque) and laser-welded. Passive fitting was evaluated for the second time. Data were submitted to anova and Tukey-Kramer honestly significant difference tests (P one-piece cp Ti group II showed significantly higher misfit values (27.57 +/- 5.06 microm) than other groups (I: 11.19 +/- 2.54 microm, III: 12.88 +/- 2.93 microm, IV: 13.77 +/- 1.51 microm) (P one-piece (I: 58.66 +/- 14.30 microm) was significantly different from cp Ti group after diagonal section (IV: 27.51 +/- 8.28 microm) (P 0.05). Results showed that diagonally sectioning ill-fitting cp Ti frameworks lowers misfit levels of prosthetic implant-supported frameworks and also improves passivity levels of the same frameworks when compared to one-piece cast structures.

  10. Ultrasonic inspection of AA6013 laser welded joints

    Directory of Open Access Journals (Sweden)

    Adriano Passini

    2011-09-01

    Full Text Available Interest in laser beam welding for aerospace applications is continuously growing, mainly for aluminum alloys. The joints quality is usually assessed by non-destructive inspection (NDI. In this work, bead on plate laser welds on 1.6 mm thick AA6013 alloy sheets, using a 2 kW Yb-fiber laser were obtained and inspected by pulse/echo ultrasonic phased-array technique. Good and poor quality welds were inspected in order to verify the limits of inspection, comparing also to X-ray radiography and metallographic inspections. The results showed that ultrasonic phased array technique was able to identify the presence of grouped porosity, through the attenuation of the amplitude of the echo signal. This attenuation is attributed to the scattering of the waves caused by micro pores, with individual size below the resolution limit of the equipment, but when grouped, can cause a perceptive effect on the reflection spectra.

  11. Laser-GMA Hybrid Pipe Welding System

    National Research Council Canada - National Science Library

    Reutzel, Edward W; Kern, Ludwig; Sullivan, Michael J; Tressler, Jay F; Avalos, Juan

    2007-01-01

    The combination of laser welding with conventional gas metal arc welding technology offers substantial increases in production rate of joining pipe through single-pass joining compared to multi-pass...

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

    International Nuclear Information System (INIS)

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

    2013-01-01

    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. (paper)

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

    Science.gov (United States)

    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.

  14. Laser processing of metals and alloys

    International Nuclear Information System (INIS)

    Goswami, G.L.; Kumar, Dilip; Roy, P.R.

    1988-01-01

    Laser, due to its high degree of coherence can produce powder density in the range of 10 3 -10 11 W/mm 2 . This high power density of the laser beam enables it to be utilized for many industrial applications, e.g. welding, cutting, drilling, surface treatment, etc. Laser processing of materials has many advantages, e.g. good quality product at high processing speed, least heat affected zone, minimum distortion, etc. In addition, the same laser system can be utilized for different applications, a very cost effective factor for any industry. Therefore laser has been adopted for processing of different materials for a wide range of applications and is now replacing conventional materials processing techniques on commercial merits with several economic and metallurgical advantages. Applications of laser to process materials of different thicknesses varying from 0.1 mm to 100 mm have demonstrat ed its capability as an important manufacturing tool for engineering industries. While lasers have most widely been utilized in welding, cutting and drilling they have also found applications in surface treatment of metals and alloys, e.g. transfor mation hardening and annealing. More recently, there has been significant amount of research being undertaken in laser glazing, laser surface alloying and laser cladding for obtaining improved surface properties. This report reviews the stat us of laser processing of metals and alloys emphasising its metallurgical aspects a nd deals with the different laser processes like welding, cutting, drilling and surface treatment highlighting the types and choice of laser and its interaction with metals and alloys and the applications of these processes. (author). 93 refs., 32 figs., 7 tables

  15. Laser welding closed-loop power control

    DEFF Research Database (Denmark)

    Bagger, Claus; Olsen, Flemming Ove

    2003-01-01

    A closed-loop control system is developed to maintain an even seam width on the root side of a laser weld by continually controlling the output laser power of a 1500 W CO2 laser.......A closed-loop control system is developed to maintain an even seam width on the root side of a laser weld by continually controlling the output laser power of a 1500 W CO2 laser....

  16. Filler metal alloy for welding cast nickel aluminide alloys

    Science.gov (United States)

    Santella, Michael L.; Sikka, Vinod K.

    1998-01-01

    A filler metal alloy used as a filler for welding east nickel aluminide alloys contains from about 15 to about 17 wt. % chromium, from about 4 to about 5 wt. % aluminum, equal to or less than about 1.5 wt. % molybdenum, from about 1 to about 4.5 wt. % zirconium, equal to or less than about 0.01 wt. % yttrium, equal to or less than about 0.01 wt. % boron and the balance nickel. The filler metal alloy is made by melting and casting techniques such as are melting the components of the filler metal alloy and east in copper chill molds.

  17. Welding the four most popular aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    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.

  18. Factors affecting weld root morphology in laser keyhole welding

    Science.gov (United States)

    Frostevarg, Jan

    2018-02-01

    Welding production efficiency is usually optimised if full penetration can be achieved in a single pass. Techniques such as electron and laser beam welding offer deep high speed keyhole welding, especially since multi-kilowatt lasers became available. However, there are limitations for these techniques when considering weld imperfections such as weld cap undercuts, interior porosity or humps at the root. The thickness of sheets during full penetration welding is practically limited by these root humps. The mechanisms behind root morphology formation are not yet satisfactory understood. In this paper root humping is studied by reviewing previous studies and findings and also by sample examination and process observation by high speed imaging. Different process regimes governing root quality are presented, categorized and explained. Even though this study mainly covers laser beam and laser arc hybrid welding, the presented findings can generally be applied full penetration welding in medium to thick sheets, especially the discussion of surface tension effects. As a final result of this analysis, a map of methods to optimise weld root topology is presented.

  19. Texture evolution in Nd:YAG-laser welds of AZ31 magnesium alloy hot rolled sheets and its influence on mechanical properties

    International Nuclear Information System (INIS)

    Commin, Lorelei; Dumont, Myriam; Rotinat, Rene; Pierron, Fabrice; Masse, Jean-Eric; Barrallier, Laurent

    2011-01-01

    Research highlights: → AZ31 LBW fusion zone results in Mg 17 (Al-Zn) 12 precipitation, twins formation and {0 0 2} texture modification. → The mechanical properties were reduced after LBW but the fracture occurred in the base metal. → The mechanical properties were reduced after LBW but the fracture occurred in the base metal. → A recovery of elongation and UTS can be achieved by a 300 deg. C/1 h heat treatment. The texture evolution is mainly responsible for the yield strength reduction in the fusion zone. - Abstract: AZ31 hot rolled magnesium alloy presents a strong basal texture. Using laser beam welding (LBW) as a joining process induces high temperature gradients leading to major texture changes. Electron back scattered diffraction (EBSD) was used to study the texture evolution, and tensile tests coupled with speckle interferometry were performed to understand its influence on mechanical properties. The random texture obtained in the LBW fusion zone is mainly responsible for the yield strength reduction.

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

    Science.gov (United States)

    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.

  1. Mechanical and electrochemical characteristics with welding materials in robotic MIG welding of dissimilar Al alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seong Jong; Han, Min Su; Woo, Yong Bin [Mokpo Maritime Univ., Mokpo (Korea, Republic of)

    2013-05-15

    In this study, mechanical and electrochemical characteristics with welding material in MIG welded with ROBOT for dissimilar Al alloys were investigated using various experiment methods. The MIG welding by ROBOT with ER5183 and ER5556 for the 5456-H116 and 6061-T6 Al alloy were carried out. The hardness of welding zone was lower than that of base metal. In electrochemical experiment, ER5183 welding material presented excellent characteristics. The yield strength and maximum tensile strength in welding with welding material of ER5183 presented lower value than those of ER5556. The elongation and time-to-fracture showed the opposite results.

  2. Deflection load characteristics of laser-welded orthodontic wires.

    Science.gov (United States)

    Watanabe, Etsuko; Stigall, Garrett; Elshahawy, Waleed; Watanabe, Ikuya

    2012-07-01

    To compare the deflection load characteristics of homogeneous and heterogeneous joints made by laser welding using various types of orthodontic wires. Four kinds of straight orthodontic rectangular wires (0.017 inch × 0.025 inch) were used: stainless-steel (SS), cobalt-chromium-nickel (Co-Cr-Ni), beta-titanium alloy (β-Ti), and nickel-titanium (Ni-Ti). Homogeneous and heterogeneous end-to-end joints (12 mm long each) were made by Nd:YAG laser welding. Two types of welding methods were used: two-point welding and four-point welding. Nonwelded wires were also used as a control. Deflection load (N) was measured by conducting the three-point bending test. The data (n  =  5) were statistically analyzed using analysis of variance/Tukey test (P wires measured were as follows: SS: 21.7 ± 0.8 N; Co-Cr-Ni: 20.0 ± 0.3 N; β-Ti: 13.9 ± 1.3 N; and Ni-Ti: 6.6 ± 0.4 N. All of the homogeneously welded specimens showed lower deflection loads compared to corresponding control wires and exhibited higher deflection loads compared to heterogeneously welded combinations. For homogeneous combinations, Co-Cr-Ni/Co-Cr-Ni showed a significantly (P wires provide a deflection load that is comparable to that of homogeneously welded orthodontic wires.

  3. Studies on CO2-laser Hybrid-Welding of Copper

    DEFF Research Database (Denmark)

    Nielsen, Jakob Skov; Olsen, Flemming Ove; Bagger, Claus

    2005-01-01

    CO2-laser welding of copper is known to be difficult due to the high heat conductivity of the material and the high reflectivity of copper at the wavelength of the CO2-laser light. THis paper presents a study of laser welding of copper, applying laser hybrid welding. Welding was performed...... as a hybrid CO2-laser and GTAW welding process in 2 mm pure copper sheets. The purpose was to identify maximum welding speeds for the three independent welding processes, i.e. GTAW alone, laser alone and combined processes. After welding, representative welds were quality assesed according to inernational...

  4. Laser welding and collagen crosslinks

    Energy Technology Data Exchange (ETDEWEB)

    Reiser, K.M.; Last, J.A. [California Univ., Davis, CA (United States). Dept. of Medicine; Small, W. IV; Maitland, D.J.; Heredia, N.J.; Da Silva, L.B.; Matthews, D.L. [Lawrence Livermore National Lab., CA (United States)

    1997-02-20

    Strength and stability of laser-welded tissue may be influenced, in part, by effects of laser exposure on collagen crosslinking. We therefore studied effects of diode laser exposure (805 nm, 1-8 watts, 30 seconds) + indocyanine green dye (ICG) on calf tail tendon collagen crosslinks. Effect of ICG dye alone on crosslink content prior to laser exposure was investigated; unexpectedly, we found that ICG-treated tissue had significantly increased DHLNL and OHP, but not HLNL. Laser exposure after ICG application reduced elevated DHLNL and OHP crosslink content down to their native levels. The monohydroxylated crosslink HLNL was inversely correlated with laser output (p<0.01 by linear regression analysis). DHLNL content was highly correlated with content of its maturational product, OHP, suggesting that precursor-product relations are maintained. We conclude that: (1)ICG alone induces DHLNL and OHP crosslink formation; (2)subsequent laser exposure reduces the ICG-induced crosslinks down to native levels; (3)excessive diode laser exposure destroys normally occurring HLNL crosslinks.

  5. Joining characteristics of titanium-based orthodontic wires connected by laser and electrical welding methods.

    Science.gov (United States)

    Matsunaga, Junko; Watanabe, Ikuya; Nakao, Noriko; Watanabe, Etsuko; Elshahawy, Waleed; Yoshida, Noriaki

    2015-01-01

    This study investigated the possibility of electrical and laser welding to connect titanium-based alloy (beta-titanium and nickel-titanium) wires and stainless-steel or cobalt-chromium alloy wires for fabrication of combination arch-wires. Four kinds of straight orthodontic rectangular wires (0.017 × 0.025 inch) were used: stainless-steel (S-S), cobalt-chromium (Co-Cr), beta-titanium alloy (β-Ti), and nickel-titanium (Ni-Ti). Homogeneous and heterogeneous end-to-end joints (15 mm long each) were made by electrical welding and laser welding. Non-welded wires (30 mm long) were also used as a control. Maximum loads at fracture (N) and elongation (%) were measured by conducting tensile test. The data (n = 10) were statistically analyzed using analysis of variance/Tukey test (P < 0.05).The S-S/S-S and Co-Cr/Co-Cr specimens showed significantly higher values of the maximum load (ML) at fracture and elongation (EL) than those of the Ni-Ti/Ni-Ti and β-Ti/β-Ti specimens for electrical welding and those of the S-S/S-S and Co-Cr/Co-Cr specimens welded by laser. On the other hand, the laser-welded Ni-Ti/Ni-Ti and β-Ti/β-Ti specimens exhibited higher values of the ML and EL compared to those of the corresponding specimens welded by electrical method. In the heterogeneously welded combinations, the electrically welded Ni-Ti/S-S, β-Ti/S-S and β-Ti/Co-Cr specimens showed significantly (P < 0.05) higher ML and EL than those of the corresponding specimens welded by laser. Electrical welding exhibited the higher values of maximum load at fracture and elongation for heterogeneously welded combinations than laser-welding.

  6. Corrosion Resistant Cladding by YAG Laser Welding in Underwater Environment

    International Nuclear Information System (INIS)

    Tsutomi Kochi; Toshio Kojima; Suemi Hirata; Ichiro Morita; Katsura Ohwaki

    2002-01-01

    It is known that stress-corrosion cracking (SCC) will occur in nickel-base alloys used in Reactor Pressure Vessel (RPV) and Internals of nuclear power plants. A SCC sensitivity has been evaluated by IHI in each part of RPV and Internals. There are several water level instrumentation nozzles installed in domestic BWR RPV. In water level instrumentation nozzles, 182 type nickel-base alloys were used for the welding joint to RPV. It is estimated the SCC potential is high in this joint because of a higher residual stress than the yield strength (about 400 MPa). This report will describe a preventive maintenance method to these nozzles Heat Affected Zone (HAZ) and welds by a corrosion resistant cladding (CRC) by YAG Laser in underwater environment (without draining a reactor water). There are many kinds of countermeasures for SCC, for example, Induction Heating Stress Improvement (IHSI), Mechanical Stress Improvement Process (MSIP) and so on. A YAG laser CRC is one of them. In this technology a laser beam is used for heat source and irradiated through an optical fiber to a base metal and SCC resistant material is used for welding wires. After cladding the HAZ and welds are coated by the corrosion resistant materials so their surfaces are improved. A CRC by gas tungsten arc welding (GTAW) in an air environment had been developed and already applied to a couple of operating plants (16 Nozzles). This method was of course good but it spent much time to perform because of an installation of some water-proof working boxes to make a TIG-weldability environment. CRC by YAG laser welding in underwater environment has superior features comparing to this conventional TIG method as follows. At the viewpoint of underwater environment, (1) an outage term reduction (no drainage water). (2) a radioactive exposure dose reduction for personnel. At that of YAG laser welding, (1) A narrower HAZ. (2) A smaller distortion. (3) A few cladding layers. A YAG laser CRC test in underwater

  7. Corrosion Behavior of Arc Weld and Friction Stir Weld in Al 6061-T6 Alloys

    International Nuclear Information System (INIS)

    Yoon, Byoung Hyun; Kim, Heung Ju; Chang, Woong Seong; Kweon, Young Gak

    2006-01-01

    For the evaluation of corrosion resistance of Al 6061-T6 Alloy, Tafel method and immersion test was performed with Friction Stir Weld(FSW) and Gas Metal Arc Weld(GMAW). The Tafel and immersion test results indicated that GMA weld was severely attacked compared with those of friction stir weld. It may be mainly due to the galvanic corrosion mechanism act on the GMA weld

  8. Laser welding of Ti40Zr25Ni3Cu12Be20 bulk metallic glass

    International Nuclear Information System (INIS)

    Wang, G.; Huang, Y.J.; Shagiev, M.; Shen, J.

    2012-01-01

    Highlights: ► Laser welding is introduced to weld Ti-based bulk metallic glass. ► No crystallization and defects are observed in the joint. ► The sound joint exhibits a high tensile strength of 1650 MPa, 93% of the base alloy. ► The mechanism of successful welding is discussed by means of numerical simulations. - Abstract: Ti-based bulk metallic glass (BMG) plates have been successfully welded together by laser welding process. The tensile strength of the welded sample reaches up to 93% of the base material. Based on calculations and numerical simulations, the mechanism of successful welding of the BMG has been discussed in terms of the thermal history of weld fusion zone (WFZ) and heat affected zone (HAZ).

  9. Development of Technology and Equipment of the Automated Laser Welding for Manufacturing Heat Exchanger Details of Marine Engines

    Directory of Open Access Journals (Sweden)

    Shelyagin, V.D.

    2014-09-01

    Full Text Available Based on the developed automated laser welding technology for flat tubes of copper-nickel alloys laser welding complex technological equipment, which can be applied on the enterprises of machine building, aerospace, shipbuilding and automobile industries, was designed and created. To control the integrity of welded flat tubes a technique, which consists in testing sample pressure and finding defective sections by laser interferometry in the automated mode, was developed. Specialized welding head was designed and manufactured for the industrial use of the developed laser welding technology.

  10. Neutron diffraction studies of laser welding residual stresses

    Science.gov (United States)

    Petrov, Peter I.; Bokuchava, Gizo D.; Papushkin, Igor V.; Genchev, Gancho; Doynov, Nikolay; Michailov, Vesselin G.; Ormanova, Maria A.

    2016-01-01

    The residual stress and microstrain distribution induced by laser beam welding of the low-alloyed C45 steel plate was investigated using high-resolution time-of-flight (TOF) neutron diffraction. The neutron diffraction experiments were performed on FSD diffractometer at the IBR-2 pulsed reactor in FLNP JINR (Dubna, Russia). The experiments have shown that the residual stress distribution across weld seam exhibit typical alternating sign character as it was observed in our previous studies. The residual stress level is varying in the range from -60 MPa to 450 MPa. At the same time, the microstrain level exhibits sharp maxima at weld seam position with maximal level of 4.8·10-3. The obtained experimental results are in good agreement with FEM calculations according to the STAAZ model. The provided numerical model validated with measured data enables to study the influence of different conditions and process parameters on the development of residual welding stresses.

  11. The corrosion resistance of composite arch wire laser-welded by NiTi shape memory alloy and stainless steel wires with Cu interlayer in artificial saliva with protein.

    Science.gov (United States)

    Zhang, Chao; Sun, Xinhua; Hou, Xu; Li, Hongmei; Sun, Daqian

    2013-01-01

    In this paper, the corrosion resistance of laser-welded composite arch wire (CoAW) with Cu interlayer between NiTi shape memory alloy and stainless steel wire in artificial saliva with different concentrations of protein was studied. It was found that protein addition had a significant influence on the corrosion behavior of CoAW. Low concentration of protein caused the corrosion resistance of CoAW decrease in electrochemical corrosion and immersion corrosion tests. High concentration of protein could reduce this effect.

  12. The Corrosion Resistance of Composite Arch Wire Laser-Welded By NiTi Shape Memory Alloy and Stainless Steel Wires with Cu Interlayer in Artificial Saliva with Protein

    Science.gov (United States)

    Zhang, Chao; Sun, Xinhua; Hou, Xu; Li, Hongmei; Sun, Daqian

    2013-01-01

    In this paper, the corrosion resistance of laser-welded composite arch wire (CoAW) with Cu interlayer between NiTi shape memory alloy and stainless steel wire in artificial saliva with different concentrations of protein was studied. It was found that protein addition had a significant influence on the corrosion behavior of CoAW. Low concentration of protein caused the corrosion resistance of CoAW decrease in electrochemical corrosion and immersion corrosion tests. High concentration of protein could reduce this effect. PMID:23801895

  13. Laser welding and post weld treatment of modified 9Cr-1MoVNb steel.

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Z. (Nuclear Engineering Division)

    2012-04-03

    Laser welding and post weld laser treatment of modified 9Cr-1MoVNb steels (Grade P91) were performed in this preliminary study to investigate the feasibility of using laser welding process as a potential alternative to arc welding methods for solving the Type IV cracking problem in P91 steel welds. The mechanical and metallurgical testing of the pulsed Nd:YAG laser-welded samples shows the following conclusions: (1) both bead-on-plate and circumferential butt welds made by a pulsed Nd:YAG laser show good welds that are free of microcracks and porosity. The narrow heat affected zone has a homogeneous grain structure without conventional soft hardness zone where the Type IV cracking occurs in conventional arc welds. (2) The laser weld tests also show that the same laser welder has the potential to be used as a multi-function tool for weld surface remelting, glazing or post weld tempering to reduce the weld surface defects and to increase the cracking resistance and toughness of the welds. (3) The Vicker hardness of laser welds in the weld and heat affected zone was 420-500 HV with peak hardness in the HAZ compared to 240 HV of base metal. Post weld laser treatment was able to slightly reduce the peak hardness and smooth the hardness profile, but failed to bring the hardness down to below 300 HV due to insufficient time at temperature and too fast cooling rate after the time. Though optimal hardness of weld made by laser is to be determined for best weld strength, methods to achieve the post weld laser treatment temperature, time at the temperature and slow cooling rate need to be developed. (4) Mechanical testing of the laser weld and post weld laser treated samples need to be performed to evaluate the effects of laser post treatments such as surface remelting, glazing, re-hardening, or tempering on the strength of the welds.

  14. Numerical simulation of the laser welding process for the prediction of temperature distribution on welded aluminium aircraft components

    Science.gov (United States)

    Tsirkas, S. A.

    2018-03-01

    The present investigation is focused to the modelling of the temperature field in aluminium aircraft components welded by a CO2 laser. A three-dimensional finite element model has been developed to simulate the laser welding process and predict the temperature distribution in T-joint laser welded plates with fillet material. The simulation of the laser beam welding process was performed using a nonlinear heat transfer analysis, based on a keyhole formation model analysis. The model employs the technique of element ;birth and death; in order to simulate the weld fillet. Various phenomena associated with welding like temperature dependent material properties and heat losses through convection and radiation were accounted for in the model. The materials considered were 6056-T78 and 6013-T4 aluminium alloys, commonly used for aircraft components. The temperature distribution during laser welding process has been calculated numerically and validated by experimental measurements on different locations of the welded structure. The numerical results are in good agreement with the experimental measurements.

  15. Femtosecond fiber laser welding of dissimilar metals.

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kuchuk, Yatsenko, S.I.; Cherednichok, V.T.; Semenov, L.A. (E.O. Paton Electric Welding Inst., Kiev (Ukraine))

    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.

  17. Friction stir spot welding of dissimilar aluminium alloys

    International Nuclear Information System (INIS)

    Bozkurt, Yahya

    2016-01-01

    Friction stir spot welding (FSSW) has been proposed as an effective technology to spot weld the so-called “difficult to be welded” metal alloys such as thin sheets aluminum alloys and dissimilar materials. FSSW is derived from friction stir welding technology, its principle benefit being low cost joining, lower welding temperature and shorter welding time than conventional welding methods. In this study, dissimilar AlMg 3 and AlCu 4 Mg 1 aluminium alloy plates were FSSWed by offsetting the low strength sheet on upper side of the weld. The effects of tool rotation speed on the microstructure, lap shear fracture load (LSFL), microhardness and fracture features of the weld are investigated by constant welding parameters. The maximum LSFL was obtained by increasing the tool rotational speed. However, the joints exhibited pull-out nugget fracture mode under lap shear tensile testing conditions. The largest completely bonded zone was observed as 5.86 mm which was narrower at the opposite position of the joint. Key words: friction stir spot welding, aluminium alloys, mechanical properties, dissimilar joint, welding parameters

  18. Laser Peening for Mitigation of Stress Corrosion Cracking at Welds in Marine Aluminum

    Science.gov (United States)

    2011-06-01

    and propagate in other alloys systems, such as austenitic Alloys 600, 800, and AISI type 304 stainless steel. Potential zones of susceptibility for...MITIGATION OF STRESS CORROSION CRACKING AT WELDS IN MARINE ALUMINUM by Heather R. Mattern June 2011 Thesis Advisor: Luke N. Brewer...REPORT TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE Laser Peening for Mitigation of Stress Corrosion Cracking at Welds in Marine

  19. Plasma Arc Augmented CO2 laser welding

    DEFF Research Database (Denmark)

    Bagger, Claus; Andersen, Mikkel; Frederiksen, Niels

    2001-01-01

    In order to reduce the hardness of laser beam welded 2.13 mm medium strength steel CMn 250, a plasma arc has been used simultaneously with a 2.6 kW CO2 laser source. In a number of systematic laboratory tests, the plasma arc current, plasma gas flow and distance to the laser source were varied...

  20. Reliability of copper based alloys for electric resistance spot welding

    International Nuclear Information System (INIS)

    Jovanovicj, M.; Mihajlovicj, A.; Sherbedzhija, B.

    1977-01-01

    Durability of copper based alloys (B-5 and B-6) for electric resistance spot-welding was examined. The total amount of Be, Ni and Zr was up to 2 and 1 wt.% respectively. Good durability and satisfactory quality of welded spots were obtained in previous laboratory experiments carried out on the fixed spot-welding machine of an industrial type (only B-5 alloy was examined). Electrodes made of both B-5 and B-6 alloy were tested on spot-welding grips and fixed spot-welding machines in Tvornica automobila Sarajevo (TAS). The obtained results suggest that the durability of electrodes made of B-5 and B-6 alloys is more than twice better than of that used in TAS

  1. Laser welding of copper and aluminium battery interconnections

    Science.gov (United States)

    De Bono, Paola; Blackburn, Jon

    2015-07-01

    The adoption of lithium-ion and/or super-capacitor battery technologies is a current hot topic in the automotive industry. For both battery types, the terminals and busbars are manufactured from copper (Cu) and/or aluminium-based (Al-based) alloys, as a result of their high electrical and thermal conductivities. Laser welding is considered an attractive process to industry due to its easy automotability, high processing speed and highly repeatable cost-effective processing. However, laser welding of Cu-Cu and Al-Al joints presents several difficulties due to the high surface reflectivity at infrared (IR) wavelengths. This behaviour becomes even more critical when processing thin sheets and foils.This paper summarises recent work performed to develop laser welding techniques suitable for monometallic joining of Cu-Cu and Al-Al electrical interconnections. Laser welding of multiple overlapped foils (with thickness in the range of 17μm-100μm) were investigated.

  2. Study of laser welding of copper sheets

    OpenAIRE

    A. Klimpel; A. Rzeźnikiewicz; Ł. Janik

    2007-01-01

    Purpose: Purpose of this research is to study laser autogenous welding process of short seam beads and filletwelds of lap joints of oxygen-free copper sheets 1.0 [mm] thick. On the bases of results of quality assessment itwas proved that high power diode laser (HPDL) welded lap joints of copper sheet provide mechanical propertieson the level of parent material.Design/methodology/approach: Short seam beads and fillet welds of lap joints of oxygen-free copper sheets 1,0[mm] thick were tested, t...

  3. Influence of Welding Process and Post Weld Heat Treatment on Microstructure and Pitting Corrosion Behavior of Dissimilar Aluminium Alloy Welds

    Science.gov (United States)

    Venkata Ramana, V. S. N.; Mohammed, Raffi; Madhusudhan Reddy, G.; Srinivasa Rao, K.

    2018-03-01

    Welding of dissimilar Aluminum alloy welds is becoming important in aerospace, shipbuilding and defence applications. In the present work, an attempt has been made to weld dissimilar aluminium alloys using conventional gas tungsten arc welding (GTAW) and friction stir welding (FSW) processes. An attempt was also made to study the effect of post weld heat treatment (T4 condition) on microstructure and pitting corrosion behaviour of these welds. Results of the present investigation established the differences in microstructures of the base metals in T4 condition and in annealed conditions. It is evident that the thickness of the PMZ is relatively more on AA2014 side than that of AA6061 side. In FS welds, lamellar like shear bands are well noticed on the top of the stir zone. The concentration profile of dissimilar friction stir weld in T4 condition revealed that no diffusion has taken place at the interface. Poor Hardness is observed in all regions of FS welds compared to that of GTA welds. Pitting corrosion resistance of the dissimilar FS welds in all regions was improved by post weld heat treatment.

  4. Investigate The Effect Of Welding Parameters On Mechanical Properties During The Welding Of Al-6061 Alloy

    Directory of Open Access Journals (Sweden)

    Rajendra Prasad

    2017-10-01

    Full Text Available Friction welding is a solid state welding technique which is being used in recent times to weld similar as well as dissimilar metals for getting defect free weld. Many combinations like low carbon to stainless steel austenitic to ferrite stainless steel aluminium to copper and titanium to aluminium or steel have been tried out by various solid state welding processes with quite good results. In the present work the 3 level full factorial design has been employed to investigate the effect of welding parameters on tensile strength toughness and heat generation during the welding of Al-6061 alloy. Mathematical relationships between friction welding parameters and mechanical properties like heat generation tensile strength and toughness have also been developed. An attempt has also been made to examine the fracture surfaces of test specimens using SEM. It has been found that welding speed is the most significant parameter thats affect the heat generation tensile strength and toughness. it has been found that tensile strength and toughness during welding increases with increased in welding speed while tensile strength and toughness initially increased as the welding time increases after that it decreased with increase in welding time. The difference in weight of alloying elements can be clearly seen by analyzing spectrum of elements.

  5. Hybrid Laser-Arc Welding of the High-Strength Shipbuilding Steels: Equipment and Technology

    Science.gov (United States)

    Turichin, G.; Kuznetsov, M.; Tsibulskiy, I.; Firsova, A.

    Hybrid laser-arc welding (HLAW) allows getting weld joints with thickness up to 35 mm for one pass, provide good quality formation of joints, minimal thermal deformations, the productivity in 10 times more in comparison with arc welding. In addition, replacement arc welding to the HLAW allows economizing filler materials, shielding gas and consumable electricity more than 4 times. Therefore, HLAW is actually technology for basic engineering branches and especially for shipbuilding. The Institute of Laser and Welding Technologies (ILWT) developed laser and hybrid laser-arc welding technologies for different type of steels and alloys including high-strength shipbuilding steels. Also ILWT produced portal and robotic systems for HLAW process realization. Portal system for hybrid laser-arc welding of panels with dimensions 6x6 m using at the manufacturing of flat curvilinear sections in the shipbuilding is depicted in the article. Results of experimental researches of the hybrid laser-arc welding parameters influence on the formation and mechanical properties of weld joint are described at the publication also. Experimental part was made with using of the portal system.

  6. Polymer welding with lasers: chances and hurdles

    Science.gov (United States)

    Bachmann, Friedrich G.

    2002-02-01

    Polymer welding with lasers has been demonstrated already several years ago, using preferably CO2 and Nd:YAG lasers; however, it did not become a big market so far, which is commonly accepted to be due to cost reasons and the size of the laser systems. With the appearance of the efficient, reliable, extremely compact and easy to integrate high power diode lasers, this technology undergoes a renaissance and first application in industrial manufacturing environment have been reported. However, our experience has also shown, that technological hurdles still exclude certain applications and limit the technology to certain configurations. This is, since additionally to the material parameters of the polymer for conventional welding, e.g. melting resp. glass temperature, decomposition temperature, thermal expansion coefficient etc. for the laser weld of course optical parameters play a key role.

  7. Comparison of Welding Residual Stresses of Hybrid Laser-Arc Welding and Submerged Arc Welding in Offshore Steel Structures

    DEFF Research Database (Denmark)

    Andreassen, Michael Joachim; Yu, Zhenzhen; Liu, Stephen

    2016-01-01

    In the offshore industry, welding-induced distortion and tensile residual stresses have become a major concern in relation to the structural integrity of a welded structure. Particularly, the continuous increase in size of welded plates and joints needs special attention concerning welding induced...... are hybrid laser-arc welding (HLAW) and submerged arc welding (SAW). Both welding methods are applied for a full penetration butt-weld of 10 mm thick plates made of thermomechanically hot-rolled, low-carbon, fine-grain S355ML grade steel used in offshore steel structures. The welding residual stress state...

  8. Inline Repair of Blowouts During Laser Welding

    Science.gov (United States)

    Hansen, K. S.; Olsen, F. O.; Kristiansen, M.; Madsen, O.

    In a current laser welding production process of components of stainless steel, a butt joint configuration may lead to failures in the form of blowouts, causing an unacceptable welding quality. A study to improve the laser welding process was performed with the aim of solving the problem by designing a suitable pattern of multiple small laser spots rather than a single spot in the process zone. The blowouts in the process are provoked by introducing small amounts of zinc powder in the butt joint. When the laser heats up the zinc, this rapidly evaporates and expands, leaving the melt pool to be blown away locally. Multiple spot pattern designs are tested. Spot patterns are produced by applying diffractive optics to a beam from a single mode fiber laser. Results from welding while applying spot patterns both with and without trailing spots are presented. Data showing the power ratio between a trailing spot and two main spots as a function of spot distance is also presented. The results of the study show that applying multiple spots in the welding process may improve the process stability when welding materials with small impurities in the form of zinc particles.

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

    Science.gov (United States)

    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.

  10. Effect of joint design and welding type on the flexural strength and weld penetration of Ti-6Al-4V alloy bars.

    Science.gov (United States)

    Simamoto Júnior, Paulo Cézar; Resende Novais, Veridiana; Rodrigues Machado, Asbel; Soares, Carlos José; Araújo Raposo, Luís Henrique

    2015-05-01

    Framework longevity is a key factor for the success of complete-arch prostheses and commonly depends on the welding methods. However, no consensus has been reached on the joint design and welding type for improving framework resistance. The purpose of this study was to assess the effect of different joint designs and welding methods with tungsten inert gas (TIG) or laser to join titanium alloy bars (Ti-6Al-4V). Seventy titanium alloy bar specimens were prepared (3.18 mm in diameter × 40.0 mm in length) and divided into 7 groups (n=10): the C-control group consisting of intact specimens without joints and the remaining 6 groups consisting of specimens sectioned perpendicular to the long-axis and rejoined using an I-, X30-, or X45-shaped joint design with TIG welding (TI, TX30, and TX45) or laser welding (LI, LX30, and LX45). The specimens were tested with 3-point bending. The fracture surfaces were first evaluated with stereomicroscopy to measure the weld penetration area and then analyzed with scanning electron microscopy (SEM). The data were statistically analyzed with 2-way ANOVA and the Tukey post hoc test, 1-way ANOVA and the Dunnett test, and the Pearson correlation test (α=.05). Specimens from the X30 and X45 groups showed higher flexural strength (Ppenetration area in the X45 group, either for laser or TIG welding. SEM analysis showed more pores at the fracture surfaces of the laser specimens. Fracture surfaces indicative of regions of increased ductility were detected for the TIG specimens. TIG welding resulted in higher flexural strength for the joined titanium specimens than laser welding. For both welding methods, X30- and X45-shaped joint designs resulted in higher flexural strength and welding penetration than the I-shaped joint design. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  11. Laser welding, cutting and surface treatment

    International Nuclear Information System (INIS)

    Crafer, R.C.

    1984-01-01

    Fourteen articles cover a wide range of laser applications in welding, cutting and surface treatment. Future trends are covered as well as specific applications in shipbuilding, the manufacture of heart pacemakers, in the electronics industry, in automobile production and in the aeroengine industry. Safety with industrial lasers and the measurement of laser beam parameters are also included. One article on 'Lasers in the Nuclear Industry' is indexed separately. (U.K.)

  12. Sensor-guided robotic laser welding

    NARCIS (Netherlands)

    de Graaf, M.W.

    2007-01-01

    Robotic laserwelding is a promising joining technique for welding of continuous seams in 3D products. High quality joints can be realised provided that the manipulation of the laser beam and the product tolerances meet strict criteria. The requirements for the positioning accuracy of the laser

  13. A study of the weldability and weld related microstructure of cabot alloy 214

    Science.gov (United States)

    Cieslak, M. J.; Stephens, J. J.; Carr, M. J.

    1988-03-01

    The weldability and weld metal microstructure of Cabot Alloy 214 have been investigated with a variety of experimental and analytical techniques. These include Varestraint hot crack testing, hot ductility testing, pulsed Nd:YAG laser welding, scanning and analytical electron microscopy, electron microprobe analysis, and X-ray diffraction. A heat of Alloy 214 containing intentionally alloyed B (0.003 wt pct) and Zr (0.07 wt pct) was much more sensitive to both fusion zone hot cracking as quantified by the Varestraint test and to simulated heat-affected-zone (HAZ) cracking as quantified by hot ductility testing than a heat of Alloy 214 containing no intentionally added B (0.0002 wt pct) or Zr (0.02 wt pct). Scanning electron microscopy of the high B and Zr alloy showed the presence of dendritically-shaped, Zr-rich constituents in interdendritic regions in the gas-tungsten-arc (GTA) welds. Electron microprobe analysis of these welds revealed a segregation pattern of Cr, Al, Mn, and Zr enrichment in interdendritic regions and Ni and Fe enrichment in dendrite core regions. Analytical electron microscopy revealed the presence of ZrX (X = B, C, N, O), M23C6, and γ' in the fusion zone of GTA weld specimens, γ' was also found in the as-received base metal and in the GTA weld HAZ. X-ray diffraction analysis of extractions from the high B and Zr GTA weld metal also indicated the presence of a ZrX-type constituent. The results of this study are in qualitative agreement with earlier work performed on alloys such as NIMONIC 90 and INCONEL 718∗ relative to the detrimental effect of B and Zr additions on fusion zone and HAZ hot cracking susceptibility.

  14. Contribution to Numerical Simulation of Laser Welding

    Science.gov (United States)

    Turňa, Milan; Taraba, Bohumil; Ambrož, Petr; Sahul, Miroslav

    Contribution deals with numerical simulation of thermal and stress fields in welding tubes made of austenitic stainless CrNi steel type AISI 304 with a pulsed Nd:YAG laser. Process simulation was realised by use of ANSYS 10 software. Experiments were aimed at solution of asymptotic, standard and the so-called shell model. Thermally dependent properties of AISI 304 steel were considered. Thermal fields developed in the course of welding process and also shape of weld pool were assessed. Contribution is aimed at simulation of technological welding process with input parameters regarding the thermal and strain task and comparison of attained results with real experiment. The achieved results of numerical simulation were almost identical with a real weldment thermally affected by welding process.

  15. Nanoindentation of Electropolished FeCrAl Alloy Welds

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, Jordan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Aydogan, Eda [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mara, Nathan Allan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Maloy, Stuart Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-13

    The present report summarizes Berkovich nanoindentation modulus and hardness measurements on two candidate FeCrAl alloys (C35M and C37M) on as-received (AR) and welded samples. In addition, spherical nanoindentation stress-strain measurements were performed on individual grains to provide further information and demonstrate the applicability of these protocols to mechanically characterizing welds in FeCrAl alloys. The indentation results are compared against the reported tensile properties for these alloys to provide relationships between nanoindentation and tensile tests and insight into weldsoftening for these FeCrAl alloys. Hardness measurements revealed weld-softening for both alloys in good agreement with tensile test results. C35M showed a larger reduction in hardness at the weld center from the AR material compared to C37M; this is also consistent with tensile tests. In general, nanohardness was shown to be a good predictor of tensile yield strength and ultimate tensile stress for FeCrAl alloys. Spherical nanoindentation measurements revealed that the fusion zone (FZ) + heat affected zone (HAZ) has a very low defect density typical of well-annealed metals as indicated by the frequent pop-in events. Spherical nanoindentation yield strength, Berkovich hardness, and tensile yield strength measurements on the welded material all show that the C37M welded material has a higher strength than C35M welded material. From the comparison of nanoindentation and tensile tests, EBSD microstructure analysis, and information on the processing history, it can be deduced that the primary driver for weld-softening is a change in the defect structure at the grain-scale between the AR and welded material. These measurements serve as baseline data for utilizing nanoindentation for studying the effects of radiation damage on these alloys.

  16. Structure formation of 5083 alloy during friction stir welding

    Science.gov (United States)

    Zaikina, A. A.; Kolubaev, A. V.; Sizova, O. V.; Ivanov, K. V.; Filippov, A. V.; Kolubaev, E. A.

    2017-12-01

    This paper provides a comparative study of structures obtained by friction stir welding and sliding friction of 5083 Al alloy. Optical and electron microscopy reveals identical fine-grained structures with a grain size of ˜5 µm both in the weld nugget zone and subsurface layer in friction independently of the initial grain size of the alloy. It has been suggested that the grain boundary sliding is responsible for the specific material flow pattern in both techniques considered.

  17. Laser Welding-Brazing of Immiscible AZ31B Mg and Ti-6Al-4V Alloys Using an Electrodeposited Cu Interlayer

    Science.gov (United States)

    Zhang, Zequn; Tan, Caiwang; Wang, Gang; Chen, Bo; Song, Xiaoguo; Zhao, Hongyun; Li, Liqun; Feng, Jicai

    2018-03-01

    Metallurgical bonding between immiscible system AZ31B magnesium (Mg) and Ti-6Al-4V titanium (Ti) was achieved by adding Cu interlayer using laser welding-brazing process. Effect of the laser power on microstructure evolution and mechanical properties of Mg/Cu-coated Ti joints was studied. Visually acceptable joints were obtained at the range of 1300 to 1500 W. The brazed interface was divided into three parts due to temperature gradient: direct irradiation zone, intermediate zone and seam head zone. Ti3Al phase was produced along the interface at the direct irradiation zone. Ti-Al reaction layer grew slightly with the increase in laser power. A small amount of Ti2(Cu,Al) interfacial compounds formed at the intermediate zone and the ( α-Mg + Mg2Cu) eutectic structure dispersed in the fusion zone instead of gathering when increasing the laser power at this zone. At the seam head zone, Mg-Cu eutectic structure was produced in large quantities under all cases. Joint strength first increased and then decreased with the variation of the laser power. The maximum fracture load of Mg/Cu-coated Ti joint reached 2314 N at the laser power of 1300 W, representing 85.7% joint efficiency when compared with Mg base metal. All specimens fractured at the interface. The feature of fracture surface at the laser power of 1100 W was characterized by overall smooth surface. Obvious tear ridge and Ti3Al particles were observed at the fracture surface with increase in laser power. It suggested atomic diffusion was accelerated with more heat input giving rise to the enhanced interfacial reaction and metallurgical bonding in direct irradiation zone, which determined the mechanical properties of the joint.

  18. Welding of Thin Steel Plates by Hybrid Welding Process Combined TIG Arc with YAG Laser

    Science.gov (United States)

    Kim, Taewon; Suga, Yasuo; Koike, Takashi

    TIG arc welding and laser welding are used widely in the world. However, these welding processes have some advantages and problems respectively. In order to improve problems and make use of advantages of the arc welding and the laser welding processes, hybrid welding process combined the TIG arc with the YAG laser was studied. Especially, the suitable welding conditions for thin steel plate welding were investigated to obtain sound weld with beautiful surface and back beads but without weld defects. As a result, it was confirmed that the shot position of the laser beam is very important to obtain sound welds in hybrid welding. Therefore, a new intelligent system to monitor the welding area using vision sensor is constructed. Furthermore, control system to shot the laser beam to a selected position in molten pool, which is formed by TIG arc, is constructed. As a result of welding experiments using these systems, it is confirmed that the hybrid welding process and the control system are effective on the stable welding of thin stainless steel plates.

  19. Cryogen spray cooling during laser tissue welding.

    Science.gov (United States)

    Fried, N M; Walsh, J T

    2000-03-01

    Cryogen cooling during laser tissue welding was explored as a means of reducing lateral thermal damage near the tissue surface and shortening operative time. Two centimetre long full-thickness incisions were made on the epilated backs of guinea pigs, in vivo. India ink was applied to the incision edges then clamps were used to appose the edges. A 4 mm diameter beam of 16 W, continuous-wave, 1.06 microm, Nd:YAG laser radiation was scanned over the incisions, producing approximately 100 ms pulses. There was a delay of 2 s between scans. The total irradiation time was varied from 1-2 min. Cryogen was delivered to the weld site through a solenoid valve in spurt durations of 20, 60 and 100 ms. The time between spurts was either 2 or 4 s, corresponding to one spurt every one or two laser scans. Histology and tensile strength measurements were used to evaluate laser welds. Total irradiation times were reduced from 10 min without surface cooling to under 1 min with surface cooling. The thermal denaturation profile showed less denaturation in the papillary dermis than in the mid-dermis. Welds created using optimized irradiation and cooling parameters had significantly higher tensile strengths (1.7 +/- 0.4 kg cm(-2)) than measured in the control studies without cryogen cooling (1.0 +/- 0.2 kg cm(-2)) (p laser welding results in increased weld strengths while reducing thermal damage and operative times. Long-term studies will be necessary to determine weld strengths and the amount of scarring during wound healing.

  20. Studies on corrosion protection of laser hybrid welded AISI 316 by laser remelting

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove; Ambat, Rajan; Rasmussen, A.J.

    2005-01-01

    Unlike in autogenous laser welding, hybrid laser welding of stainless steel could introduce grain boundary carbides due to low cooling rates. Formation of grain boundary carbides leads to reduced corrosion properties. Studies have initially been carried out on hybrid laser welding and subsequent ...... regain the corrosion resistance by desensitization.......Unlike in autogenous laser welding, hybrid laser welding of stainless steel could introduce grain boundary carbides due to low cooling rates. Formation of grain boundary carbides leads to reduced corrosion properties. Studies have initially been carried out on hybrid laser welding and subsequent...... laser surface melting on microstructure and corrosion behaviour of AISI 316L welds. Welding and laser treatment parameters were varied. General corrosion behaviour of the weld and laser treated surface was characterised using a gel visualization test. The local electrochemistry of the weld and laser...

  1. Interaction mechanism in hybrid laser arc welding

    OpenAIRE

    Mahrle, Achim; Rose, Sascha; Lohse, Martin; Beyer, Eckhard; Füssel, Uwe

    2014-01-01

    Achievable benefits in hybrid laser-arc welding are closely related to suitable parameter settings. Basic optimizations consequently need a profound understanding of the relevance of involved interaction mechanisms. These are however differently evaluated and discussed in literature. This paper gives an overview on the most popular hypotheses in the field of laser-arc processing. The importance of direct interactions between laser radiation and arc plasma as well as the role of metal evaporat...

  2. Fusion Welding of AerMet 100 Alloy

    Energy Technology Data Exchange (ETDEWEB)

    ENGLEHART, DAVID A.; MICHAEL, JOSEPH R.; NOVOTNY, PAUL M.; ROBINO, CHARLES V.

    1999-08-01

    A database of mechanical properties for weldment fusion and heat-affected zones was established for AerMet{reg_sign}100 alloy, and a study of the welding metallurgy of the alloy was conducted. The properties database was developed for a matrix of weld processes (electron beam and gas-tungsten arc) welding parameters (heat inputs) and post-weld heat treatment (PWHT) conditions. In order to insure commercial utility and acceptance, the matrix was commensurate with commercial welding technology and practice. Second, the mechanical properties were correlated with fundamental understanding of microstructure and microstructural evolution in this alloy. Finally, assessments of optimal weld process/PWHT combinations for cotildent application of the alloy in probable service conditions were made. The database of weldment mechanical properties demonstrated that a wide range of properties can be obtained in welds in this alloy. In addition, it was demonstrated that acceptable welds, some with near base metal properties, could be produced from several different initial heat treatments. This capability provides a means for defining process parameters and PWHT's to achieve appropriate properties for different applications, and provides useful flexibility in design and manufacturing. The database also indicated that an important region in welds is the softened region which develops in the heat-affected zone (HAZ) and analysis within the welding metallurgy studies indicated that the development of this region is governed by a complex interaction of precipitate overaging and austenite formation. Models and experimental data were therefore developed to describe overaging and austenite formation during thermal cycling. These models and experimental data can be applied to essentially any thermal cycle, and provide a basis for predicting the evolution of microstructure and properties during thermal processing.

  3. Fatigue behaviour of post weld heat treated electron beam welded AA2219 aluminium alloy joints

    International Nuclear Information System (INIS)

    Malarvizhi, S.; Raghukandan, K.; Viswanathan, N.

    2008-01-01

    This paper reports the effect of post weld heat treatment on fatigue behaviour of electron beam welded AA2219 aluminium alloy. An attempt has been made to enhance the fatigue strength of the electron beam welded joints through post weld heat treatment methods such as solution treatment, artificial aging, solution treatment and artificial aging. Electron beam welding machine with 100 kV capacity has been used to fabricate the square butt joints. Servo hydraulic controlled fatigue testing machine with a capacity of 100 kN has been used to evaluate the fatigue life of the welded joints. Of the three post weld heat treated joints, the solution treated and aged joints are enduring higher number of cycles under the action of cyclic loads

  4. Numerical Simulation Of The Laser Welding

    Directory of Open Access Journals (Sweden)

    Aleksander Siwek

    2008-01-01

    Full Text Available The model takes into consideration thermophysical and metallurgical properties of theremelting steel, laser beam parameters and boundary conditions of the process. As a resultof heating the material, in the area of laser beam operation a weld pool is being created,whose shape and size depends on convection caused by the Marangoni force. The directionof the liquid stream depends on the temperature gradient on the surface and on the chemicalcomposition as well. The model created allows to predict the weld pool shape depending onmaterial properties, beam parameters, and boundary conditions of the sample.

  5. Lateral extrusion of tailor welded aluminum alloy pipes with a lost core of low temperature melting alloy

    OpenAIRE

    T. Ohashi; G. Liu

    2009-01-01

    Purpose: In this paper, the authors employ tailor welded aluminum alloy pipes for lateral extrusion process with a lost core to perform a hollow light-weight-part.Design/methodology/approach: The pipe is welded longitudinally by YAG-laser. “The lateral extrusion process with a lost core (LELC)” consists of lateral extrusion of pipes with a soluble solid core, called the “lost core”, which serves as a plastic mandrel. The process proceeds as follows. First, the pipe cavity is filled with the l...

  6. Laser Welding of Ship Steel

    National Research Council Canada - National Science Library

    Brayton, W. C; Banas, C. M; Peters, G. T

    1979-01-01

    ... joint cleanliness and fitup conditions. In the current program, welds were formed between surfaces with nonperfect fitup, between plasma-cut surfaces, between surfaces deliberately mismatched to provide a varging joint gap and under out...

  7. Effect of heat treatment on the properties of laser-beam welded rheo-cast F357 aluminum

    CSIR Research Space (South Africa)

    Theron, M

    2012-02-01

    Full Text Available Semi-solid metal rheo-cast F357 aluminum plates were joined by autogenous Nd:YAG laser welding and were welded in either the as-cast (F) condition, T4 temper or T6 temper condition. The weldability of this age-hardenable Al–7%Si–0.6%Mg casting alloy...

  8. A Survey on Friction Stir Welding Of Dissimilar Magnesium Alloys

    Science.gov (United States)

    Unnikrishnan, M. A.; Raja, Dhas. J. Edwin

    2017-10-01

    There is a consistent demand for superior materials in every industry. The areas on demand are automobile and aerospace sectors in major.. The most commonly used material in these fields is Aluminium.Though it possess all the properties up to some extent constant demand is pushing for alternate materials. Dissimilar alloys have been a relatively new approach towards these fields.. Friction stir welding dissimilar alloys is a big leap in Automobile sector. In this paper a detailed review of Friction stir welding of Dissimilar Magnesium alloys has been done. This work will serve as a reference to subsequent researchers.

  9. Properties and Microstructure of Laser Welded VM12-SHC Steel Pipes Joints

    OpenAIRE

    Skrzypczyk A.; Danielewski H.

    2016-01-01

    Paper presents results of microstructure and tests of welded joints of new generation VM12-SHC martensitic steel using high power CO2 laser (LBW method) with bifocal welding head. VM12-SHC is dedicated to energetic installation material, designed to replace currently used. High content of chromium and others alloying elements improve its resistance and strength characteristic. Use of VM12-SHC steel for production of the superheaters, heating chambers and walls in steam boilers resulted in var...

  10. Laser welding of polypropylene using two different sources

    Science.gov (United States)

    Mandolfino, Chiara; Brabazon, Dermot; McCarthy, Éanna; Lertora, Enrico; Gambaro, Carla; Ahad, Inam Ul

    2017-10-01

    In this paper, laser weldability of neutral polypropylene has been investigated using fibre and carbon dioxide lasers. A design of experiment (DoE) was conducted in order to establish the influence of the main working parameters on the welding strength of the two types of laser. The welded samples were characterized by carrying out visual and microscopic inspection for the welding morphology and cross-section, and by distinguishing the tensile strength. The resulting weld quality was investigated by means of optical microscopy at weld cross-sections. The tensile strength of butt-welded materials was measured and compared to that of a corresponding bulk material.

  11. Gas-tungsten arc welding of aluminum alloys

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    1972-01-01

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

  13. Closing the weld gap with laser/mig hybrid welding process

    DEFF Research Database (Denmark)

    Bagger, Claus; Olsen, Flemming Ove; Wiwe, Bjarne David

    2003-01-01

    for obtaining sound welds are identified. The welds are quality assessed according to ISO 13.919-1 and EN25817, transversal hardness measurements are made and the heat input to the workpiece is calculated. The results show that the critical gap is 0.1 mm for a laser weld alone. With hybrid welding, this can...... be increased to 0.6 mm, even at a welding speed of 3.5 m/min. The maximum welding speed with the hybrid process is comparable to laser welding alone, 4.5 m/min. The measured hardness is comparable to MIG welding, and this corresponds to a 33 percent reduction compared to laser welding alone. The heat input...

  14. Applications of robotics in laser welding

    NARCIS (Netherlands)

    de Graaf, M.W.; Aarts, Ronald G.K.M.; Katayama, Seiji

    2013-01-01

    This chapter describes how seam-tracking sensors can be integrated in a robotic laser welding system for automatic teaching of the seam trajectory as well as for correcting small errors from a pre-defined seam trajectory. Calibration procedures are required to derive accurate transformations of

  15. Micro and nanohardness testing of laser welds

    Czech Academy of Sciences Publication Activity Database

    Šebestová, H.; Čtvrtlík, Radim; Chmelíčková, H.; Tomáštík, J.

    2014-01-01

    Roč. 15, č. 3 (2014), s. 247-253 ISSN 1454-9069 R&D Projects: GA TA ČR TA01010517 Institutional support: RVO:68378271 Keywords : Vickers microhardness * depth sensing indentation * laser welding Subject RIV: JP - Industrial Processing Impact factor: 1.658, year: 2014

  16. Interpretation of aluminum-alloy weld radiography

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

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

  18. Recent Developments in Friction Stir Welding of Al-alloys

    Science.gov (United States)

    Çam, Gürel; Mistikoglu, Selcuk

    2014-06-01

    The diversity and never-ending desire for a better life standard result in a continuous development of the existing manufacturing technologies. In line with these developments in the existing production technologies the demand for more complex products increases, which also stimulates new approaches in production routes of such products, e.g., novel welding procedures. For instance, the friction stir welding (FSW) technology, developed for joining difficult-to-weld Al-alloys, has been implemented by industry in manufacturing of several products. There are also numerous attempts to apply this method to other materials beyond Al-alloys. However, the process has not yet been implemented by industry for joining these materials with the exception of some limited applications. The microstructures and mechanical properties of friction stir welded Al-alloys existing in the open literature will be discussed in detail in this review. The correlations between weld parameters used during FSW and the microstructures evolved in the weld region and thus mechanical properties of the joints produced will be highlighted. However, the modeling studies, material flow, texture formation and developments in tool design are out of the scope of this work as well as the other variants of this technology, such as friction stir spot welding (FSSW).

  19. GAP WIDTH STUDY IN LASER BUTT-WELDING

    DEFF Research Database (Denmark)

    Gong, Hui; Olsen, Flemming Ove

    In this paper the maximum allowable gap width in laser butt-welding is intensively studied. The gap width study (GWS) is performed on the material of SST of W1.4401 (AISI 316) under various welding conditions, which are the gap width : 0.00-0.50 mm, the welding speed : 0.5-2.0 m/min, the laser...

  20. Technology of welding aluminum alloys-III

    Science.gov (United States)

    Harrison, J. R.; Kor, L. J.; Oleksiak, C. E.

    1978-01-01

    Control of porosity in weld beads was major objective in development of aluminum welding program. Porosity, most difficult defect to control, is caused by hydrogen gas unable to escape during solidification. Hard tooling allows hotter bead than free-fall tooling so hydrogen bubbles can boil out instead of forming pores. Welding position, moisture, and cleanliness are other important factors in control of porosity.

  1. Mechanical behaviour of Nd:YAG laser welded superelastic NiTi

    International Nuclear Information System (INIS)

    Vieira, L. Alberty; Fernandes, F.M. Braz; Miranda, R.M.; Silva, R.J.C.; Quintino, L.; Cuesta, A.; Ocana, J.L.

    2011-01-01

    Highlights: → The main innovations claimed are: understand rolling direction effect on mechanical cycling of laser welded NiTi. → Functionality confirmed by stabilization of hysteretic response up to 8% strain. → Welds tensile cycled exhibited superior functional mechanical behaviour. → For applied stresses of 50 MPa below UTS the joints showed superelastic behaviour. - Abstract: Joining techniques for shape memory alloys (SMA) has become of great interest, as their functional properties, namely shape memory effect (SME) and superelasticity (SE), present unique solutions for state-of-the-art applications, although limited results concerning mechanical properties are reported. This paper reports experimental work performed with Nd:YAG continuous wave laser welding of superelastic cold-rolled plates of NiTi 1 mm thick. The mechanical behaviour was evaluated by means of tensile tests performed both to failure and to cycling. The superelastic behaviour of the welded joints was observed for applied stresses close to about 50 MPa below the ultimate tensile strength of the welds. The functionality was confirmed by analyzing the stabilization of the mechanical hysteretic response to strain levels up to 8%. For tensile cycling involving strain levels larger than 6%, welded specimens were found to exhibit superior functional mechanical behaviour presenting larger recoverable strain levels. The fracture surfaces were observed by scanning electron microscopy (SEM) and the effect of the rolling direction on mechanical properties was evaluated and discussed, reinforcing the importance of joint design when laser welding these alloys.

  2. Mechanical behaviour of Nd:YAG laser welded superelastic NiTi

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, L. Alberty [UNIDEMI, Departamento de Engenharia Mecanica e Industrial, Faculdade de Ciencias e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Fernandes, F.M. Braz [CENIMAT/I3N, Departamento de Ciencias dos Materiais, Faculdade de Ciencias e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Miranda, R.M., E-mail: rmiranda@fct.unl.pt [UNIDEMI, Departamento de Engenharia Mecanica e Industrial, Faculdade de Ciencias e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Silva, R.J.C. [CENIMAT/I3N, Departamento de Ciencias dos Materiais, Faculdade de Ciencias e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Quintino, L. [IDMEC, Instituto de Engenharia Mecanica, Av. Rovisco Pais, 1200 Lisboa (Portugal); Cuesta, A.; Ocana, J.L. [Centro Laser UPM, Universidad Politecnica de Madrid, Edificio ' La Arboleda' , Ctra. Valencia, km 7,300, Campus Sur UPM, 28031 Madrid (Spain)

    2011-06-25

    Highlights: {yields} The main innovations claimed are: understand rolling direction effect on mechanical cycling of laser welded NiTi. {yields} Functionality confirmed by stabilization of hysteretic response up to 8% strain. {yields} Welds tensile cycled exhibited superior functional mechanical behaviour. {yields} For applied stresses of 50 MPa below UTS the joints showed superelastic behaviour. - Abstract: Joining techniques for shape memory alloys (SMA) has become of great interest, as their functional properties, namely shape memory effect (SME) and superelasticity (SE), present unique solutions for state-of-the-art applications, although limited results concerning mechanical properties are reported. This paper reports experimental work performed with Nd:YAG continuous wave laser welding of superelastic cold-rolled plates of NiTi 1 mm thick. The mechanical behaviour was evaluated by means of tensile tests performed both to failure and to cycling. The superelastic behaviour of the welded joints was observed for applied stresses close to about 50 MPa below the ultimate tensile strength of the welds. The functionality was confirmed by analyzing the stabilization of the mechanical hysteretic response to strain levels up to 8%. For tensile cycling involving strain levels larger than 6%, welded specimens were found to exhibit superior functional mechanical behaviour presenting larger recoverable strain levels. The fracture surfaces were observed by scanning electron microscopy (SEM) and the effect of the rolling direction on mechanical properties was evaluated and discussed, reinforcing the importance of joint design when laser welding these alloys.

  3. Laser weld process monitoring and control using chromatic filtering of thermal radiation from a weld pool

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Cheol Jung; Kim, Min Suk; Baik, Sung Hoon; Chung, Chin Man

    2000-06-01

    The application of high power Nd: YAG lasers for precision welding in industry has been growing quite fast these days in diverse areas such as the automobile, the electronics and the aerospace industries. These diverse applications also require the new developments for the precise control and the reliable process monitoring. Due to the hostile environment in laser welding, a remote monitoring is required. The present development relates in general to weld process monitoring techniques, and more particularly to improved methods and apparatus for real-time monitoring of thermal radiation of a weld pool to monitor a size variation and a focus shift of the weld pool for weld process control, utilizing the chromatic aberration of focusing lens or lenses. The monitoring technique of the size variation and the focus shift of a weld pool is developed by using the chromatic filtering of the thermal radiation from a weld pool. The monitoring of weld pool size variation can also be used to monitor the weld depth in a laser welding. Furthermore, the monitoring of the size variation of a weld pool is independent of the focus shift of a weld pool and the monitoring of the focus shift of a weld pool is independent of the size variation of a weld pool.

  4. Laser weld process monitoring and control using chromatic filtering of thermal radiation from a weld pool

    International Nuclear Information System (INIS)

    Kim, Cheol Jung; Kim, Min Suk; Baik, Sung Hoon; Chung, Chin Man

    2000-06-01

    The application of high power Nd: YAG lasers for precision welding in industry has been growing quite fast these days in diverse areas such as the automobile, the electronics and the aerospace industries. These diverse applications also require the new developments for the precise control and the reliable process monitoring. Due to the hostile environment in laser welding, a remote monitoring is required. The present development relates in general to weld process monitoring techniques, and more particularly to improved methods and apparatus for real-time monitoring of thermal radiation of a weld pool to monitor a size variation and a focus shift of the weld pool for weld process control, utilizing the chromatic aberration of focusing lens or lenses. The monitoring technique of the size variation and the focus shift of a weld pool is developed by using the chromatic filtering of the thermal radiation from a weld pool. The monitoring of weld pool size variation can also be used to monitor the weld depth in a laser welding. Furthermore, the monitoring of the size variation of a weld pool is independent of the focus shift of a weld pool and the monitoring of the focus shift of a weld pool is independent of the size variation of a weld pool

  5. The microstructure and hardness changes of neutron irradiated weld joint of vanadium alloy

    Science.gov (United States)

    Watanabe, H.; Yoshida, N.; Nagasaka, T.; Muroga, T.

    2011-10-01

    Effects of neutron irradiation on YAG laser welded V-4Cr-4Ti alloy were irradiated in High Flux Isotope Reactor (HFIR). The samples were irradiated in Li environment at 723 K and 873 K up to the dose of 3.7 dpa. After the irradiation, the microstructure and Vickers hardness of the welded samples were compared of the base metal, which were simultaneously irradiated at the same irradiation cycle. At 723 K, very high density of dislocations was formed. But prominent Ti(CON) formation, which was commonly observed in He gas and vacuum environment condition, was not detected

  6. A Review of Dissimilar Welding Techniques for Magnesium Alloys to Aluminum Alloys

    Science.gov (United States)

    Liu, Liming; Ren, Daxin; Liu, Fei

    2014-01-01

    Welding of dissimilar magnesium alloys and aluminum alloys is an important issue because of their increasing applications in industries. In this document, the research and progress of a variety of welding techniques for joining dissimilar Mg alloys and Al alloys are reviewed from different perspectives. Welding of dissimilar Mg and Al is challenging due to the formation of brittle intermetallic compound (IMC) such as Mg17Al12 and Mg2Al3. In order to increase the joint strength, three main research approaches were used to eliminate or reduce the Mg-Al intermetallic reaction layer. First, solid state welding techniques which have a low welding temperature were used to reduce the IMCs. Second, IMC variety and distribution were controlled to avoid the degradation of the joining strength in fusion welding. Third, techniques which have relatively controllable reaction time and energy were used to eliminate the IMCs. Some important processing parameters and their effects on weld quality are discussed, and the microstructure and metallurgical reaction are described. Mechanical properties of welds such as hardness, tensile, shear and fatigue strength are discussed. The aim of the report is to review the recent progress in the welding of dissimilar Mg and Al to provide a basis for follow-up research. PMID:28788646

  7. A Review of Dissimilar Welding Techniques for Magnesium Alloys to Aluminum Alloys

    Directory of Open Access Journals (Sweden)

    Liming Liu

    2014-05-01

    Full Text Available Welding of dissimilar magnesium alloys and aluminum alloys is an important issue because of their increasing applications in industries. In this document, the research and progress of a variety of welding techniques for joining dissimilar Mg alloys and Al alloys are reviewed from different perspectives. Welding of dissimilar Mg and Al is challenging due to the formation of brittle intermetallic compound (IMC such as Mg17Al12 and Mg2Al3. In order to increase the joint strength, three main research approaches were used to eliminate or reduce the Mg-Al intermetallic reaction layer. First, solid state welding techniques which have a low welding temperature were used to reduce the IMCs. Second, IMC variety and distribution were controlled to avoid the degradation of the joining strength in fusion welding. Third, techniques which have relatively controllable reaction time and energy were used to eliminate the IMCs. Some important processing parameters and their effects on weld quality are discussed, and the microstructure and metallurgical reaction are described. Mechanical properties of welds such as hardness, tensile, shear and fatigue strength are discussed. The aim of the report is to review the recent progress in the welding of dissimilar Mg and Al to provide a basis for follow-up research.

  8. Numerical simulation and experimental investigation of laser dissimilar welding of carbon steel and austenitic stainless steel

    Science.gov (United States)

    Nekouie Esfahani, M. R.; Coupland, J.; Marimuthu, S.

    2015-07-01

    This study reports an experimental and numerical investigation on controlling the microstructure and brittle phase formation during laser dissimilar welding of carbon steel to austenitic stainless steel. The significance of alloying composition and cooling rate were experimentally investigated. The investigation revealed that above a certain specific point energy the material within the melt pool is well mixed and the laser beam position can be used to control the mechanical properties of the joint. The heat-affected zone within the high-carbon steel has significantly higher hardness than the weld area, which severely undermines the weld quality. A sequentially coupled thermo-metallurgical model was developed to investigate various heat-treatment methodology and subsequently control the microstructure of the HAZ. Strategies to control the composition leading to dramatic changes in hardness, microstructure and service performance of the dissimilar laser welded fusion zone are discussed.

  9. Microstructure and Mechanical Properties of an Ultrasonic Spot Welded Aluminum Alloy: The Effect of Welding Energy.

    Science.gov (United States)

    Peng, He; Chen, Daolun; Jiang, Xianquan

    2017-04-25

    The aim of this study is to evaluate the microstructures, tensile lap shear strength, and fatigue resistance of 6022-T43 aluminum alloy joints welded via a solid-state welding technique-ultrasonic spot welding (USW)-at different energy levels. An ultra-fine necklace-like equiaxed grain structure is observed along the weld line due to the occurrence of dynamic crystallization, with smaller grain sizes at lower levels of welding energy. The tensile lap shear strength, failure energy, and critical stress intensity of the welded joints first increase, reach their maximum values, and then decrease with increasing welding energy. The tensile lap shear failure mode changes from interfacial fracture at lower energy levels, to nugget pull-out at intermediate optimal energy levels, and to transverse through-thickness (TTT) crack growth at higher energy levels. The fatigue life is longer for the joints welded at an energy of 1400 J than 2000 J at higher cyclic loading levels. The fatigue failure mode changes from nugget pull-out to TTT crack growth with decreasing cyclic loading for the joints welded at 1400 J, while TTT crack growth mode remains at all cyclic loading levels for the joints welded at 2000 J. Fatigue crack basically initiates from the nugget edge, and propagates with "river-flow" patterns and characteristic fatigue striations.

  10. Microstructure and Mechanical Properties of an Ultrasonic Spot Welded Aluminum Alloy: The Effect of Welding Energy

    Directory of Open Access Journals (Sweden)

    He Peng

    2017-04-01

    Full Text Available The aim of this study is to evaluate the microstructures, tensile lap shear strength, and fatigue resistance of 6022-T43 aluminum alloy joints welded via a solid-state welding technique–ultrasonic spot welding (USW–at different energy levels. An ultra-fine necklace-like equiaxed grain structure is observed along the weld line due to the occurrence of dynamic crystallization, with smaller grain sizes at lower levels of welding energy. The tensile lap shear strength, failure energy, and critical stress intensity of the welded joints first increase, reach their maximum values, and then decrease with increasing welding energy. The tensile lap shear failure mode changes from interfacial fracture at lower energy levels, to nugget pull-out at intermediate optimal energy levels, and to transverse through-thickness (TTT crack growth at higher energy levels. The fatigue life is longer for the joints welded at an energy of 1400 J than 2000 J at higher cyclic loading levels. The fatigue failure mode changes from nugget pull-out to TTT crack growth with decreasing cyclic loading for the joints welded at 1400 J, while TTT crack growth mode remains at all cyclic loading levels for the joints welded at 2000 J. Fatigue crack basically initiates from the nugget edge, and propagates with “river-flow” patterns and characteristic fatigue striations.

  11. Electric pulse treatment of welded joint of aluminum alloy

    Directory of Open Access Journals (Sweden)

    A.A. Mitiaev

    2013-08-01

    Full Text Available Purpose. Explanation of the redistribution effect of residual strengthes after electric pulse treatment of ark welding seam of the aluminum alloy. Methodology. Alloy on the basis of aluminium of АК8М3 type served as the research material. As a result of mechanical treatment of the ingots after alloy crystallization the plates with 10 mm thickness were obtained. After edge preparation the elements, which are being connected were butt welded using the technology of semiautomatic argon arc welding by the electrode with a diameter of 3 mm of AK-5 alloy. Metal structure of the welded joint was examined under the light microscope at a magnification of 200 and under the scanning electronic microscope «JSM-6360 LA». The Rockwell hardness (HRF was used as a strength characteristic of alloy. Hardness measuring of the phase constituents (microhardness was carried out using the device PМТ-3, with the indenter loadings 5 and 10 g. The crystalline structure parameters of alloy (dislocation density, second kind of the crystalline grid distortion and the scale of coherent scattering regions were determined using the methods of X-ray structural analysis. Electric pulse treatment (ET was carried out on the special equipment in the conditions of the DS enterprise using two modes A and В. Findings. On the basis of researches the previously obtained microhardness redistribution effect in the area of welded connection after ET was confirmed. As a result of use of the indicated treatment it was determined not only the reduction of microhardness gradient but also the simultaneous hardening effect in the certain thermal affected areas near the welding seam. During study of chemical composition of phase constituents it was discovered, that the structural changes of alloy as a result of ET first of all are caused by the redistribution of chemical elements, which form the connections themselves. By the nature of the influence the indicated treatment can be

  12. Resistance Element Welding of Magnesium Alloy/austenitic Stainless Steel

    Science.gov (United States)

    Manladan, S. M.; Yusof, F.; Ramesh, S.; Zhang, Y.; Luo, Z.; Ling, Z.

    2017-09-01

    Multi-material design is increasingly applied in the automotive and aerospace industries to reduce weight, improve crash-worthiness, and reduce environmental pollution. In the present study, a novel variant of resistance spot welding technique, known as resistance element welding was used to join AZ31 Mg alloy to 316 L austenitic stainless steel. The microstructure and mechanical properties of the joints were evaluated. It was found that the nugget consisted of two zones, including a peripheral fusion zone on the stainless steel side and the main fusion zone. The tensile shear properties of the joints are superior to those obtained by traditional resistance spot welding.

  13. Laser penetration spike welding : A microlaser welding technique enabling novel product designs and constructions

    NARCIS (Netherlands)

    Dijken, D.K; Hoving, W.; de Hosson, J.T.M.

    A novel method for laser penetration microspot welding of sheet metal is presented. With this so called "laser spike-welding," large gap tolerances are allowed. Depending on the ratio of laser spot radius to top plate thickness, gaps of 100% of the top layer thickness and more can be bridged. With

  14. Studies on corrosion protection of laser hybrid welded AISI 316 by laser remelting

    DEFF Research Database (Denmark)

    Olsen, Flemming Ove; Ambat, Rajan; Rasmussen, A.J.

    2005-01-01

    Unlike in autogenous laser welding, hybrid laser welding of stainless steel could introduce grain boundary carbides due to low cooling rates. Formation of grain boundary carbides leads to reduced corrosion properties. Studies have initially been carried out on hybrid laser welding and subsequent...... laser surface melting on microstructure and corrosion behaviour of AISI 316L welds. Welding and laser treatment parameters were varied. General corrosion behaviour of the weld and laser treated surface was characterised using a gel visualization test. The local electrochemistry of the weld and laser...... treated surface was investigated using a novel micro electrochemical technique with a tip resolution of ~1 mm. Results show that hybrid laser welding of 316L has increased corrosion susceptibility probably as a result of grain boundary carbide formation. However a suitable post laser treatment could...

  15. Energy Losses Estimation During Pulsed-Laser Seam Welding

    Science.gov (United States)

    Sebestova, Hana; Havelkova, Martina; Chmelickova, Hana

    2014-06-01

    The finite-element tool SYSWELD (ESI Group, Paris, France) was adapted to simulate pulsed-laser seam welding. Besides temperature field distribution, one of the possible outputs of the welding simulation is the amount of absorbed power necessary to melt the required material volume including energy losses. Comparing absorbed or melting energy with applied laser energy, welding efficiencies can be calculated. This article presents achieved results of welding efficiency estimation based on the assimilation both experimental and simulation output data of the pulsed Nd:YAG laser bead on plate welding of 0.6-mm-thick AISI 304 stainless steel sheets using different beam powers.

  16. Enhancing the Ductility of Laser-Welded Copper-Aluminum Connections by using Adapted Filler Materials

    Science.gov (United States)

    Weigl, M.; Albert, F.; Schmidt, M.

    Laser micro welding of direct copper-aluminum connections typically leads to the formation of intermetallic phases and an embrittlement of the metal joints. By means of adapted filler materials it is possible to reduce the brittle phases and thereby enhance the ductility of these dissimilar connections. As the element silicon features quite a well compatibility with copper and aluminum, filler materials based on Al-Si and Cu-Si alloys are used in the current research studies. In contrast to direct Cu-Al welds, the aluminum filler alloy AlSi12 effectuates a more uniform element mixture and a significantly enhanced ductility.

  17. Fatigue behaviour of GMAW welded aluminium alloy AA7020

    OpenAIRE

    Bloem, Carlos; Salvador Moya, Mª Dolores; Amigó, Vicente; Vicente-Escuder, Ángel

    2009-01-01

    [EN] The aim of this investigation is to evaluate the influence on fatigue behaviour of the finishing of the bulge in a welded aluminium zinc magnesium alloy AA7020. It was determined that total or partial elimination of the bulge has very little influence on its behaviour, giving a very similar result on both cases, where one is better than the other by only 3%. Bloem, C.; Salvador Moya, MD.; Amigó, V.; Vicente-Escuder, Á. (2009). Fatigue behaviour of GMAW welded aluminium alloy AA7020. W...

  18. Temperature measurements during laser skin welding

    Science.gov (United States)

    Fried, Nathaniel M.; Choi, Bernard; Welch, Ashley J.; Walsh, Joseph T., Jr.

    1999-06-01

    A thermal camera was used to measure surface temperatures during laser skin welding to provide feedback for optimization of the laser parameters. Two-cm-long, full- thickness incisions were made in guinea pig skin. India ink was used as an absorber. Continuous-wave, 1.06-μm, Nd:YAG laser radiation was scanned over the incisions, producing a pulse duration of approximately 100 ms. Cooling durations between scans of 1.6, 4.0, and 8.0 s were studied with total operation times of 3, 5, and 10 min, respectively. A laser spot diameter of 5 mm was used with the power constant at 10 W. Thermal images were obtained at 30 frames per second with a thermal camera detecting 3.5 micrometers radiation. Surface temperatures were recorded at 0, 1, and 6 mm from the center line of the incision. Cooling durations between scans of 1.6 s and 4.0 s in vitro resulted in temperatures at the weld site remaining above ~65°C for prolonged periods of time. Cooling durations between scans as long as 8.0 s were sufficient both in vitro and in vivo to prevent a significant rise in baseline temperatures at the weld site over time.

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

    Science.gov (United States)

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

    1993-05-01

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

  20. Seam tracking for laser welding with an industrial robot

    NARCIS (Netherlands)

    Römer, Gerardus Richardus, Bernardus, Engelina; van Amerongen, J.; Jonker, Jan B.; Jonker, J.B.; Regtien, Paulus P.L.; Regtien, P.

    2001-01-01

    Because of their construction and flexibility, industrial robots are suitable to be used, with a laser source and an optical fiber, for laser welding of 3D products. However, the positioning accuracy of robots are insufficient for laser welding. Also the product and clamping tolerances are too wide

  1. Development of Weld Overlay System for Dissimilar Metal Alloy 82/182 Butt Welds

    Energy Technology Data Exchange (ETDEWEB)

    Park, K. S.; Byeon, J. G.; Kim, Y. J. [Doosan Heavy Industries and Construction Co., Ltd., Changwon (Korea, Republic of)

    2008-10-15

    As a result of the alloy 600 PWSCC(Primary Water Stress Corrosion Cracking), leak in the dissimilar welds in pressurizer nozzle was discovered recently in several US plants and the advanced companies had developed repair techniques. 2 or 3 years from now, more than half of the nuclear power plants in the country will be operated more than 20 years. Therefore, we need to develop repair techniques of dissimilar welds in pressurizer nozzle. With above backgrounds, we have developed a Prototype of Repair System for dissimilar welds in pressurizer nozzle.

  2. Fiber laser welding of nickel based superalloy Inconel 625

    Science.gov (United States)

    Janicki, Damian M.

    2013-01-01

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

  3. The investigation of typical welding defects for 5456 aluminum alloy friction stir welds

    International Nuclear Information System (INIS)

    Chen Huabin; Yan Keng; Lin Tao; Chen Shanben; Jiang Chengyu; Zhao Yong

    2006-01-01

    The external factors on the friction stir welding defects are so abundant that the experiments of friction stir welding were conducted for 5456 aluminum alloy. With the changes of the tool tilt angle and material condition, defects can be generated. These defects can be conventional ones (lack of penetration or voids), or lazy S, which are unique to friction stir welding. However, the origin of the defects remains an area of uncertainty. In this study, an attempt has been made to investigate the formation of these defects. The typical welding defects of friction stir welding joint for 5456 aluminum alloy were analyzed and discussed, respectively, by using optical microscopy (OM), energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscope (SEM). The microscopic examination of the nugget zone and fracture location of the weld confirms that the tilt angle can change the plastic material flow patterns in the stir zone and accordingly control the weld properties. In addition, the oxide layer from the initial butt surface during FSW is dispersed at the grain boundary. These A1 2 O 3 particles are actually the major cause of failure of the joint

  4. Welding with high power fiber lasers - A preliminary study

    International Nuclear Information System (INIS)

    Quintino, L.; Costa, A.; Miranda, R.; Yapp, D.; Kumar, V.; Kong, C.J.

    2007-01-01

    The new generation of high power fiber lasers presents several benefits for industrial purposes, namely high power with low beam divergence, flexible beam delivery, low maintenance costs, high efficiency and compact size. This paper presents a brief review of the development of high power lasers, and presents initial data on welding of API 5L: X100 pipeline steel with an 8 kW fiber laser. Weld bead geometry was evaluated and transition between conduction and deep penetration welding modes was investigated

  5. Laser surface alloying of aluminium-transition metal alloys

    International Nuclear Information System (INIS)

    Almeida, A.; Vilar, R.

    1998-01-01

    Laser surface alloying has been used as a tool to produce hard and corrosion resistant Al-transition metal (TM) alloys. Cr and Mo are particularly interesting alloying elements to produce stable high-strength alloys because they present low diffusion coefficients and solid solubility in Al. To produce Al-TM surface alloys a two-step laser process was developed: firstly, the material is alloyed using low scanning speed and secondly, the microstructure is modified by a refinement step. This process was used in the production of Al-Cr, Al-Mo and Al-Mo and Al-Nb surface alloys by alloying Cr, Mo or Nb powder into an Al and 7175 Al alloy substrate using a CO 2 laser . This paper presents a review of the work that has been developed at Instituto Superior Tecnico on laser alloying of Al-TM alloy, over the last years. (Author) 16 refs

  6. Recent Developments and Research Progress on Friction Stir Welding of Titanium Alloys: An Overview

    Science.gov (United States)

    Karna, Sivaji; Cheepu, Muralimohan; Venkateswarulu, D.; Srikanth, V.

    2018-03-01

    Titanium and its alloys are joined by various welding processes. However, Fusion welding of titanium alloys resulted solidification problems like porosity, segregation and columnar grains. The problems occurred in conventional welding processes can be resolved using a solid state welding i.e. friction stir welding. Aluminium and Magnesium alloys were welded by friction stir welding. However alloys used for high temperature applications such as titanium alloys and steels are arduous to weld using friction stir welding process because of tool limitations. Present paper summarises the studies on joining of Titanium alloys using friction stir welding with different tool materials. Selection of tool material and effect of welding conditions on mechanical and microstructure properties of weldments were also reported. Major advantage with friction stir welding is, we can control the welding temperature above or below β-transus temperature by optimizing the process parameters. Stir zone in below beta transus condition consists of bi-modal microstructure and microstructure in above β-transus condition has large prior β- grains and α/β laths present in the grain. Welding experiments conducted below β- transus condition has better mechanical properties than welding at above β-transus condition. Hardness and tensile properties of weldments are correlated with the stir zone microstructure.

  7. Microhardness Testing of Aluminum Alloy Welds

    Science.gov (United States)

    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

  8. Effects of Friction Stir Welding Speed on AA2195 alloy

    Directory of Open Access Journals (Sweden)

    Lee Ho-Sung

    2016-01-01

    Full Text Available The application of friction stir welding (FSW to aerospace has grown rapidly due to the high efficiency and environmental friendly nature of the process. FSW is achieved by plastic flow of frictionally heated material in solid state and offers many advantages of avoiding hot cracking and limiting component distortion. Recently low density, high modulus and high strength AA2195 are used as substitute for conventional aluminum alloys since the weight saving is critical in aerospace applications. One of the problems for this alloy is weld metal porosity formation leading to hot cracking. Combination of FSW and AA2195 provides synergy effect to improve mechanical properties and weight saving of aerospace structure such as cryogenic fuel tanks for launch systems. The objective of this paper is to investigate the effect of friction stir welding speed on mechanical and microstructural properties of AA2195. The friction stir welded materials were joined with four different tool rotation speeds (350~800 rpm and five welding speeds (120~360 mm/min, which are the two prime welding parameters in this process.

  9. Measurement of Laser Weld Temperatures for 3D Model Input

    Energy Technology Data Exchange (ETDEWEB)

    Dagel, Daryl [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Grossetete, Grant [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Maccallum, Danny O. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-10-01

    Laser welding is a key joining process used extensively in the manufacture and assembly of critical components for several weapons systems. Sandia National Laboratories advances the understanding of the laser welding process through coupled experimentation and modeling. This report summarizes the experimental portion of the research program, which focused on measuring temperatures and thermal history of laser welds on steel plates. To increase confidence in measurement accuracy, researchers utilized multiple complementary techniques to acquire temperatures during laser welding. This data serves as input to and validation of 3D laser welding models aimed at predicting microstructure and the formation of defects and their impact on weld-joint reliability, a crucial step in rapid prototyping of weapons components.

  10. Laser welding of maraging steel rocket motor casing

    CSIR Research Space (South Africa)

    Van Rooyen, C

    2009-11-01

    Full Text Available This presentation looks at the experimental procedure and results of laser welding of maraging steel rocker motor casing. It concludes that a fracture occurred in weld metal of autogenous welding and that a fracture occurred in base material when...

  11. Development of Deep Penetration Welding Technology with High Brightness Laser under Vacuum

    Science.gov (United States)

    Katayama, Seiji; Yohei, Abe; Mizutani, Masami; Kawahito, Yousuke

    The authors have developed a new chamber for laser welding under the low vacuum conditions achieved by using rotary pumps. High-power disk laser bead-on-plate welding was performed on Type 304 stainless steel or A5052 aluminium alloy plate at the powers of 10, 16 and 26 kW at various welding speeds under low vacuum. The sound welds of more than 50 and 70 mm in penetration depth could be produced in Type 304 at the pressure of 0.1 kPa, the speed of 0.3 m/min and the power of 16 kW and 26 kW, respectively. Similar penetration was achieved in A 5052 aluminum alloy. Welding phenomena under low vacuum were also understood by observing the behavior of a keyhole inlet, a molten pool, melt flows and a plume ejected from a keyhole through high speed video cameras. Low interaction between a laser beam and a plume under low vacuum was confirmed by using probe laser beam method.

  12. Application of YAG laser processing in underwater welding and cutting

    International Nuclear Information System (INIS)

    Ohwaki, Katsura; Morita, Ichiro; Kojima, Toshio; Sato, Shuichi

    2002-01-01

    The high-power YAG laser is a new fabrication tool. The laser torch is easy to combine with complex with complex mechanics because of beam delivery through optical fiber. A direct underwater laser welding technology has been developed and applied to the preservation, maintenance and removal of nuclear power plants. For subdividing or removing operations for retirement of plants, the laser cutting properties were confirmed to allow a maximum cutting thickness of 80 mm. For repairing inner surface of stainless steel tanks, an underwater laser welding system using a remote-controlled robot was developed and the high quality of underwater laser welding was confirmed. (author)

  13. Characterization the microstructure of pulsed Nd:YAG welding method in low frequencies; correlation with tensile and fracture behavior in laser-welded nitinol joints

    Science.gov (United States)

    Shojaei Zoeram, Ali; Rahmani, Aida; Asghar Akbari Mousavi, Seyed Ali

    2017-05-01

    The precise controllability of heat input in pulsed Nd:YAG welding method provided by two additional parameters, frequency and pulse duration, has made this method very promising for welding of alloys sensitive to heat input. The poor weldability of Ti-rich nitinol as a result of the formation of Ti2Ni IMC has deprived us of the unique properties of this alloy. In this study, to intensify solidification rate during welding of Ti-rich nitinol, pulsed Nd:YAG laser beam in low frequency was employed in addition to the employment of a copper substrate. Specific microstructure produced in this condition was characterized and the effects of this microstructure on tensile and fracture behavior of samples welded by two different procedures, full penetration and double-sided method with halved penetration depth for each side were investigated. The investigations revealed although the combination of low frequencies, the use of a high thermal conductor substrate and double-sided method eliminated intergranular fracture and increased tensile strength, the particular microstructure, built in the pulsed welding method in low frequencies, results to the formation of the longitudinal cracks during the first stages of tensile test at weld centerline. This degrades tensile strength of welded samples compared to base metal. The results showed samples welded in double-sided method performed much better than samples welded in full penetration mode.

  14. Research on effect of HAZ to butt weld of small diameter titanium alloy pipe

    International Nuclear Information System (INIS)

    Song Yiyang; Zhu Yonghui; Pan Xiaodong

    2014-01-01

    Four groups of welding experiments between new and weld with heat-affected zone (HAZ) have been done by using titanium alloy pipes (φ8 mm). This paper analyzed the width of the HAZ in small kind titanium alloy pipe butt weld, analyzed the difference of performance on dimensions, microstructure, hardness and tensile strength. The result shows that the performance of weld with HAZ is equivalence as the new weld, and it satisfied all the technical index. The conclusion of this paper is valuable for other small diameter titanium alloy pipe butt weld. (authors)

  15. Strength of laser welded joints of polypropylene composites

    Science.gov (United States)

    Votrubec, V.; Hisem, P.; Vinšová, L.; Lukášová, V.

    2017-11-01

    This paper deals with experimental tests of laser welded polypropylene composites. Polymers, such as polypropylene, are often filled with fibres in order to increase their mechanical properties. The welding procedure can also influence material properties nearby weld joints. Therefore the strength of weld joints is lower than strength of primary materials. This effect is proved by realized shear tests. Polymer specimens were filled with 20 % and 40 % of glass fibres and all possible combinations of specimens were welded for experiments. There is also discussed influence of volume fraction of glass fibres in polypropylene on the strength of weld joint.

  16. Towards Real Time Diagnostics of Hybrid Welding Laser/GMAW

    Energy Technology Data Exchange (ETDEWEB)

    Timothy Mcjunkin; Dennis C. Kunerth; Corrie Nichol; Evgueni Todorov; Steve Levesque; Feng Yu; Robert Danna Couch

    2013-07-01

    Methods are currently being developed towards a more robust system real time feedback in the high throughput process combining laser welding with gas metal arc welding. A combination of ultrasonic, eddy current, electronic monitoring, and visual techniques are being applied to the welding process. Initial simulation and bench top evaluation of proposed real time techniques on weld samples are presented along with the concepts to apply the techniques concurrently to the weld process. Consideration for the eventual code acceptance of the methods and system are also being researched as a component of this project. The goal is to detect defects or precursors to defects and correct when possible during the weld process.

  17. Analysis of weld solidification cracking in cast nickel aluminide alloys

    International Nuclear Information System (INIS)

    Santella, M.L.; Feng, Z.

    1995-01-01

    A study of the response of several nickel aluminide alloys to SigmaJig testing was done to examine their weld solidification cracking behavior and the effect of Zr concentration. The alloys were based on the Ni-8Al-7.7Cr-1.5Mo-0.003B wt% composition and contained Zr concentrations of 3, 4.5, and 6 wt%. Vacuum induction melted ingots with a diameter of 2.7 in and weight about 18 lb were made of each alloy, and were used to make 2 x 2 x 0.030 in specimens for the Sigmajig test. The gas tungsten arc welds were made at travel speeds of 10, 20, and 30 ipm with heat inputs of 2--2.5 kJ/in. When an arc was established before traveling onto the test specimen centerline cracking was always observed. This problem was overcome by initiating the arc directly on the specimens. Using this approach, the 3 wt% Zr alloy withstood an applied stress of 24 ksi without cracking at a welding speed of 10 ipm. This alloy cracked at 4 ksi applied at 20 ipm, and with no applied load at 30 ipm. Only limited testing was done on the remaining alloys, but the results indicate that resistance to solidification cracking increases with Zr concentration. Zirconium has limited solid solubility and segregates strongly to interdendritic regions during solidification where it forms a Ni solid solution-Ni 5 Zr eutectic. The volume fraction of the eutectic increases with Zr concentration. The solidification cracking behavior of these alloys is consistent with phenomenological theory, and is discussed in this context. The results from SigmaJig testing are analyzed using finite element modeling of the development of mechanical strains during solidification of welds. Experimental data from the test substantially agree with recent analysis results

  18. Residual and operating stresses in welded Alloy 600 penetrations

    International Nuclear Information System (INIS)

    Hunt, E.S.; Gross, D.J.; Pathania, R.

    1995-01-01

    An elastic-plastic finite element model has been developed for calculating residual and operating stresses in Alloy 600 penetrations which are installed in pressure vessel shells by J-groove welds. The welding process is simulated by multiple passes of heat input with heat transfer into the adjacent parts during welding and cooling. Analysis results are presented for CRDM nozzles, pressurizer instrument nozzles and pressurizer heater sleeves. The effect of several key variables such as nozzle material yield strength, angle of the nozzle relative to the vessel shell, weld size, presence of counterbores, etc. are explored. Results of the modelling are correlated with field and laboratory data. Application of the stress analysis results to PWSCC predictive modeling is discussed. (author). 6 refs, 12 figs, 2 tabs

  19. Effect of welding speed on microstructural evolution and mechanical properties of laser welded-brazed Al/brass dissimilar joints

    Science.gov (United States)

    Zhou, L.; Luo, L. Y.; Tan, C. W.; Li, Z. Y.; Song, X. G.; Zhao, H. Y.; Huang, Y. X.; Feng, J. C.

    2018-01-01

    Laser welding-brazing process was developed for joining 5052 aluminum alloy and H62 brass in butt configuration with Zn-15%Al filler. Effect of welding speed on microstructural characteristics and mechanical properties of joints were investigated. Acceptable joints without obvious defect were obtained with the welding speed of 0.5-0.6 m/min, while lower and higher welding speed caused excessive back reinforcement and cracking, respectively. Three reaction layers were observed at welding speed of 0.3 m/min, which were Al4.2Cu3.2Zn0.7 (τ‧)/Al4Cu9/CuZn from weld seam side to brass side; while at welding speed of 0.4-0.6 m/min, two layers Al4.2Cu3.2Zn0.7 and CuZn formed. The thickness of interfacial reaction layers increased with the decrease of welding speed, but varied little at different interfacial positions from top to bottom in one joint. Tensile test results indicated that the maximum joint tensile strength of 128 MPa was obtained at 0.5 m/min, which was 55.7% of that of Al base metal. All the joints fractured along the weld seam/brass interface. Some differences were found regarding fracture locations with three and two reaction layers. The joint fractured between Al4Cu9 and τ‧ IMC layer when the interface had three layers, while the crack occurred between CuZn and τ‧ phase in the case of two layers.

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

    Science.gov (United States)

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

    2016-11-01

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

  1. Initial Development in Joining of ODS Alloys Using Friction Stir Welding

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Weiju [ORNL; Feng, Zhili [ORNL

    2007-08-01

    Solid-state welding of oxide-dispersion-strengthened (ODS) alloy MA956 sheets using friction stir welding (FSW) was investigated. Butt weld was successfully produced. The weld and base metals were characterized using optical microscopy, scanning electronic microscopy, transmission electronic microscopy, and energy dispersion x-ray spectrum. Microhardness mapping was also conducted over the weld region. Analyses indicate that the distribution of the strengthening oxides was preserved in the weld. Decrease in microhardness of the weld was observed but was insignificant. The preliminary results seem to confirm the envisioned feasibility of FSW application to ODS alloy joining. For application to Gen IV nuclear reactor heat exchanger, further investigation is suggested.

  2. Laser welded steel sandwich panel bridge deck development : finite element analysis and stake weld strength tests.

    Science.gov (United States)

    2009-09-01

    This report summarizes the analysis of laser welded steel sandwich panels for use in bridge structures and : static testing of laser stake welded lap shear coupons. Steel sandwich panels consist of two face sheets : connected by a relatively low-dens...

  3. Development of laser beam welding transverse-varestraint test for assessment of solidification cracking susceptibility in laser welds

    Science.gov (United States)

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

    2015-05-01

    In order to quantitatively evaluate the solidification cracking susceptibility in laser welds of type 310S stainless steel, a transverse-Varestraint testing system using a laser beam welding apparatus was newly constructed. The timing-synchronization between the laser oscillator, welding robot and hydraulic pressure devices was established by employing high-speed camera observations together with electrical signal control among the three components. Moreover, the yoke-drop time measured by the camera was used to prevent underestimation of the crack length. The laser beam melt-run welding used a variable welding speed from 10.0 to 40.0 mm/s, while the gas tungsten arc welding varied the welding speed from 1.67 to 5.00 mm/s. As the welding speed increased from 1.67 to 40.0mm/s, the solidification brittle temperature range of type 310S stainless steel welds was reduced from 146 to 120 K. It follows that employing the laser beam welding process mitigates the solidification cracking susceptibility for type 310S stainless steel welds.

  4. CHARACTERIZATION OF DEFECTS IN ALLOY 152, 52 AND 52M WELDS

    International Nuclear Information System (INIS)

    Bruemmer, Stephen M.; Toloczko, Mychailo B.; Olszta, Matthew J.; Seffens, Rob J.; Efsing, Pal G.

    2009-01-01

    Defect distributions have been documented by optical metallography, scanning electron microscopy and electron backscatter diffraction in alloy 152 and 52 mockups welds, alloy 52 and 52M overlay mockups and an alloy 52M inlay. Primary defects were small cracks at grain boundaries except for more extensive cracking in the dilution zone of an alloy 52 overlay on 304SS. Detailed characterizations of the dilution zone cracks were performed by analytical transmission electron microscopy identifying grain boundary titanium-nitride precipitation associated with the intergranular separations. I. INTRODUCTION Weldments continue to be a primary location of stress-corrosion cracking (SCC) in light-water reactor systems. While problems related to heat-affected-zone (HAZ) sensitization and intergranular (IG) SCC of austenitic stainless alloys in boiling-water reactors (BWRs) have been significantly reduced, SCC has now been observed in HAZs of non-sensitized materials and in dissimilar metal welds where Ni-base alloy weld metals are used. IGSCC in weld metals has been observed in both BWRs and pressurized water reactors (PWRs) with recent examples for PWR pressure vessel penetrations producing the most concern. This has led to the replacement of alloy 600/182/82 welds with higher Cr, more corrosion-resistant replacement materials (alloy 690/152/52/52M). Complicating this issue has been a known susceptibility to cracking during welding [1-7] of these weld metals. There is a critical need for an improved understanding of the weld metal metallurgy and defect formation in Ni-base alloy welds to effectively assess long-term performance. A series of macroscopic to microscopic examinations were performed on available mockup welds made with alloy 52 or alloy 152 plus selected overlay and inlay mockups. The intent was to expand our understanding of weld metal structures in simulated LWR service components with a focus on as-welded defects. Microstructural features, defect distributions

  5. CHARACTERIZATION OF DEFECTS IN ALLOY 152, 52 AND 52M WELDS

    Energy Technology Data Exchange (ETDEWEB)

    Bruemmer, Stephen M.; Toloczko, Mychailo B.; Olszta, Matthew J.; Seffens, Rob J.; Efsing, Pal G.

    2009-08-27

    Defect distributions have been documented by optical metallography, scanning electron microscopy and electron backscatter diffraction in alloy 152 and 52 mockups welds, alloy 52 and 52M overlay mockups and an alloy 52M inlay. Primary defects were small cracks at grain boundaries except for more extensive cracking in the dilution zone of an alloy 52 overlay on 304SS. Detailed characterizations of the dilution zone cracks were performed by analytical transmission electron microscopy identifying grain boundary titanium-nitride precipitation associated with the intergranular separations. I. INTRODUCTION Weldments continue to be a primary location of stress-corrosion cracking (SCC) in light-water reactor systems. While problems related to heat-affected-zone (HAZ) sensitization and intergranular (IG) SCC of austenitic stainless alloys in boiling-water reactors (BWRs) have been significantly reduced, SCC has now been observed in HAZs of non-sensitized materials and in dissimilar metal welds where Ni-base alloy weld metals are used. IGSCC in weld metals has been observed in both BWRs and pressurized water reactors (PWRs) with recent examples for PWR pressure vessel penetrations producing the most concern. This has led to the replacement of alloy 600/182/82 welds with higher Cr, more corrosion-resistant replacement materials (alloy 690/152/52/52M). Complicating this issue has been a known susceptibility to cracking during welding [1-7] of these weld metals. There is a critical need for an improved understanding of the weld metal metallurgy and defect formation in Ni-base alloy welds to effectively assess long-term performance. A series of macroscopic to microscopic examinations were performed on available mockup welds made with alloy 52 or alloy 152 plus selected overlay and inlay mockups. The intent was to expand our understanding of weld metal structures in simulated LWR service components with a focus on as-welded defects. Microstructural features, defect distributions

  6. Pre-Industry-Optimisation of the Laser Welding Process

    DEFF Research Database (Denmark)

    Gong, Hui

    phenomena of the laser welding process including the behaviour of the keyhole and plume, and the correlation between the adjustable process parameters: laser power, welding speed, focal point position, gas parameters etc. and the characteristics describing the quality of the weld: seam depth and width......) is generated by the self-learning mechanism - the neural network. The optimisation procedure is completed with the welding process being carried out by adjusting the focus of the laser beam to the OFPP. The self-learning focus control system, employing the off-line trained neural network to generate the OFPPs......This dissertation documents the investigations into on-line monitoring the CO2 laser welding process and optimising the process parameters for achieving high quality welds. The requirements for realisation of an on-line control system are, first of all, a clear understanding of the dynamic...

  7. Service experience with alloy 182 butt welds, and the weld overlay mitigation process

    Energy Technology Data Exchange (ETDEWEB)

    Bamford, W.; Elder, G.G.; Perdue, R.; Newton, B. [Westinghouse Electric Co., Madison, Pennsylvania (United States)

    2007-07-01

    Alloy 182/82 welds have been in service in operating PWR plants for over thirty years, accumulating over 600 reactor years service to date. Early years of service were extremely reliable, but since about 1990, these welds have suffered frequent cracking resulting from primary water stress corrosion cracking. This paper will provide an update to the service experience to date, and describe the industry reaction to the issue, which was to encourage mitigation with application of mitigative weld overlays. Also described will be the issues which beset the industry when it began to apply overlays, using guidelines and requirements which had previously been used only for emergency repairs. These include inflexible NDE requirements, very strict acceptance criteria, and welding process issues. With time, these issues are being dealt with effectively, and this paper provides the details of how progress was made. (author)

  8. Microstructural evolution in friction stir welding of nanostructured ODS alloys

    International Nuclear Information System (INIS)

    Chen, C.-L.; Tatlock, G.J.; Jones, A.R.

    2010-01-01

    Nanostructured oxide dispersion strengthened (ODS) Fe-based alloys manufactured by mechanical alloying (MA) are generally considered to be promising candidate materials for high-temperature applications up to at least 1100 o C because of their excellent creep strength and good oxidation resistance. However, a key issue with these alloys is the difficulty in using fusion welding techniques to join components due to oxide particle agglomeration and loss in the weld zone and the disruption and discontinuity in the grain structure introduced at the bond. In this study, the evolution of microstructure has been comprehensively studied in friction stir welds in a ferritic ODS alloy. Initially, electron backscattering diffraction (EBSD) was used to analyze the grain orientation, the grain boundary geometries and recrystallization behaviour. It suggested that deformation heterogeneities were introduced during the friction stirring process which facilitated the onset of recrystallization. Transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) were used to observe the effects of the friction stir welding (FSW) process on the grain structure and the distribution of Y 2 O 3 and other particles in the metal substrates in the FSW and adjacent regions, after the alloys had been recrystallized at temperatures up to 1380 o C for 1 h in air. The results show that fine-equiaxed grains and a uniform distribution of oxide particles were present in the friction stirred region but that the grain boundaries in the parent metal were pinned by particles. Friction stirring appeared to release these boundaries and allowed secondary recrystallization to occur after further heat treatment. The FSW process appears to be a promising technique for joining ferritic ODS alloys in the form of sheet and tube.

  9. Finite element simulation of laser transmission welding of dissimilar ...

    African Journals Online (AJOL)

    Now-a-days, metal to plastic micro-welding is of great interest in the field of biomedical and electronics applications. Laser transmission welding (LTW) has emerged as the most suitable technique for such applications. In this paper, a three-dimensional finite element (FE) thermal model is developed to simulate the laser ...

  10. Laser power coupling efficiency in conduction and keyhole welding ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    The paper also discusses effect of microstructure on the cracking susceptibility of laser welds. Keywords. Laser welding; coupling efficiency; conduction loss, austenitic ... A list of symbols is given at the end of the paper. 383 ... is the sheet thickness, and α, K and Tm are the thermal diffusivity, thermal conductivity and.

  11. Impact toughness of laser alloyed aluminium AA1200 alloys

    CSIR Research Space (South Africa)

    Mabhali, Luyolo AB

    2013-08-01

    Full Text Available Laser surface alloying of aluminium AA1200 was performed with a 4kW Nd:YAG laser and impact resistance of the alloys was investigated. The alloying powders were a mixture of Ni, Ti and SiC in different proportions. Surfaces reinforced...

  12. Welding of Aluminum Alloys to Steels: An Overview

    Science.gov (United States)

    2013-08-01

    51] in which the bimetal wires can be roll welded Al/ Steel strips and the welding is a kind of tricky process to have similar metals joined together...Al 1060) and steel (1Cr18Ni9Ti) were joined together using the vacuum furnace and A-Si alloy as the strip layer. The interface of the joints showed...also greatly appreciated. References [1] A. Kelkar, R. Roth, J. Clark, Automobile bodies: can aluminum be an economical alternative to steel ? , JOM

  13. Analysis and validation of laser spot weld-induced distortion

    Energy Technology Data Exchange (ETDEWEB)

    Knorovsky, G.A.; Kanouff, M.P.; Maccallum, D.O.; Fuerschbach, P.W.

    1999-12-09

    Laser spot welding is an ideal process for joining small parts with tight tolerances on weld size, location, and distortion, particularly those with near-by heat sensitive features. It is also key to understanding the overlapping laser spot seam welding process. Rather than attempting to simulate the laser beam-to-part coupling (particularly if a keyhole occurs), it was measured by calorimetry. This data was then used to calculate the thermal and structural response of a laser spot welded SS304 disk using the finite element method. Five combinations of process parameter values were studied. Calculations were compared to experimental data for temperature and distortion profiles measured by thermocouples and surface profiling. Results are discussed in terms of experimental and modeling factors. The authors then suggest appropriate parameters for laser spot welding.

  14. Laser-welded ureteral anastomoses: experimental studies with three techniques.

    Science.gov (United States)

    Gürpinar, T; Gürer, S; Kattan, M W; Wang, L; Griffith, D P

    1996-01-01

    Tissue welding with laser energy is a new technique for reconstructive surgery. The potential advantages of laser welding are (a) lack of foreign body reaction, (b) decreased operative time, (c) less tissue manipulation, and (d) effective union of tissues equivalent to sutured anastomoses. We have performed ureteral anastomoses in adult mongrel dogs using a KTP 532 nm laser at an intensity of 1.4 W. Multiple "spot welds" of 1-s duration were utilized in a single layer anastomosis. Laser-welded anastomoses were performed with and without protein solder (33% and 50% human albumin) and were compared to sutured anastomoses. The laser-welded anastomoses required less operative time and provided bursting pressure levels similar to those of traditional sutured anastomoses. There was no advantage or disadvantage to the addition of human albumin as a solder in these experimental studies.

  15. Laser beam-plasma plume interaction during laser welding

    Science.gov (United States)

    Hoffman, Jacek; Moscicki, Tomasz; Szymanski, Zygmunt

    2003-10-01

    Laser welding process is unstable because the keyhole wall performs oscillations which results in the oscillations of plasma plume over the keyhole mouth. The characteristic frequencies are equal to 0.5-4 kHz. Since plasma plume absorbs and refracts laser radiation, plasma oscillations modulate the laser beam before it reaches the workpiece. In this work temporary electron densities and temperatures are determined in the peaks of plasma bursts during welding with a continuous wave CO2 laser. It has been found that during strong bursts the plasma plume over the keyhole consists of metal vapour only, being not diluted by the shielding gas. As expected the values of electron density are about two times higher in peaks than their time-averaged values. Since the plasma absorption coefficient scales as ~N2e/T3/2 (for CO2 laser radiation) the results show that the power of the laser beam reaching the metal surface is modulated by the plasma plume oscillations. The attenuation factor equals 4-6% of the laser power but it is expected that it is doubled by the refraction effect. The results, together with the analysis of the colour pictures from streak camera, allow also interpretation of the dynamics of the plasma plume.

  16. Induction heat treatment of laser welds

    DEFF Research Database (Denmark)

    Bagger, Claus; Olsen, Flemming Ove; Sørensen, Joakim Ilsing

    2003-01-01

    In this paper, a new approach based on induction heat-treatment of flat laser welded sheets is presented. With this new concept, the ductility of high strength steels GA260 with a thickness of 1.8 mm and CMn with a thickness of 2.13 mm is believed to be improved by prolonging the cooling time from...... 750º to 450º C. Initially, a simple analytical model was used to calculate the ideal energy contributions from a CO2 high power laser source together with an induction heat source such that the temperature can be kept at 600º C for 2.5 seconds. This knowledge was then used for the design...... of an induction coil. A number of systematic laboratory tests were then performed in order to study the effects of the coil on bead-on-plate laser welded samples. In these tests, important parameters such as coil current and distance between coil and sample were varied. Temperature measurements were made...

  17. STRESS CORROSION CRACKING OF ALLOY 152 WELD BUTTER NEAR THE LOW ALLOY STEEL INTERFACE

    Energy Technology Data Exchange (ETDEWEB)

    Alexandreanu, Bogdan; Chen, Yiren; Natesan, Ken; Shack, William J.

    2015-01-01

    The objective of this work was to obtain SCC growth data in Alloy 152 weld butter near the interface with Low Alloy Steel (LAS), which is a region where some dilution of Cr was expected to have occurred, thus presumably exhibiting an increased SCC-susceptibility vs. the bulk of the weld. The LAS piece used in this application was Alloy 533-Gr B from the Midland reactor lower head, and the Alloy 152 weld butter received a prototypical Post Weld Heat Treatment (PWHT) prior to joining by Alloy 152 to an Alloy 690 piece according to a procedure qualified to ASME IX. The compact tension specimens for SCC testing were aligned in the first layer of the Alloy 152 butter. The experimental approach based on tracking environmental enhancement vs. location was successful in identifying SCC-susceptible locations, and SCC rates ranging from 10-12 m/s to as high as 10-10 m/s were measured. The post-test examination of the specimens found that the fracture had the intergranular/interdendritic appearance typical of welds, and that the propagation was arrested wherever an intersection with the LAS occurred. The large range of SCC rates measured does not appear to correlate well with the local concentration of Cr (approx. 25% at the SCC locations), and, in fact, low Cr (20%) – high Fe “streaks” seemed to slow/arrest crack propagation. In short, simple “Cr dilution” does not seem to fully account for the “SCC-susceptible” microstructure that yielded the 10-10 m/s growth rate in this weld.

  18. Development of underwater YAG laser repair welding robots for tanks

    International Nuclear Information System (INIS)

    Miwa, Yasuhiro; Satoh, Syuichi; Ito, Kosuke; Kochi, Tsutomu; Kojima, Toshio; Ohwaki, Katsura; Morita, Ichiro

    1999-01-01

    A remote-controlled repair welding robot which uses YAG laser welding technology in underwater environment was developed. This is an underwater robot technology combined with a laser welding technology. This report will describe the structure and performance of this robot, and the welding test results. The repair welding robot consists of two parts. The one is driving equipment, and the other is welding unit. It can swim in the tank, move around the tank wall, and stay on the welding area. After that it starts YAG laser repair welding. The target of this technology is inner surface repair of some tanks made of austenitic stainless steel, for example RW (Radioactive Waste) tanks. A degradation by General Corrosion and so on might be occurred at inner surface of these tanks in BWR type nuclear power plants. If the damaged area is wide, repair welding works are done. Some workers go into the tank and set up scaffolding after full drainage. In many cases it spends too much time for draining water and repair welding preparation. If the repair welding works can be done in underwater environment, the outage period will be reduced. This is a great advantage. (author)

  19. Microstructure change and shape memory characteristics in welded Fe-28Mn-6Si-5Cr-0.53Nb-0.06C alloy

    International Nuclear Information System (INIS)

    Dong, Z.Z.; Sawaguchi, T.; Kajiwara, S.; Kikuchi, T.; Kim, S.H.; Lee, G.C.

    2006-01-01

    In the present study, an Fe-28Mn-6Si-5Cr-0.53Nb-0.06C (mass%) alloy was employed to investigate the influence of laser beam welding (LBW), electron beam welding (EBW) and tungsten-insert gas welding (TIGW) on shape memory properties. This alloy was recently found to exhibit very good shape memory effect with simple thermomechanical treatments without so-called the 'training'. After homogenizing heating at 1470 K for 10 h, two different treatments were performed: (a) 14% rolled at 870 K followed by aging at 1070 K for 10 min and then welded, (b) first welded and then extended 10% at room temperature, followed by aging at 1070 K for 10 min. The results show that the shape recovery of the alloy was slightly different depending on welding method. The shape recoveries for the samples treated in (a) by LBW, EBW and TIGW were 90%, 87%, 81% and those for the samples treated in (b) were 86%, 84% and 79%, respectively. After welding, the alloy still possesses very high shape recovery stress of about 250 MPa for the samples treated in (a). High strength of the weld zone is due to the dendrite structure with very fine columnar grains. All of these results on welding will make a wide industry application of the Fe-Mn-Si based SMAs in the near future

  20. Development of laser beam welding for the lip seal configuration

    International Nuclear Information System (INIS)

    Yadav, Ashish; Joshi, Jaydeep; Singh, Dhananjay Kumar; Natu, Harshad; Rotti, Chandramouli; Bandyopadhyay, Mainak; Chakraborty, Arun

    2015-01-01

    Highlights: • Laser welding parameter optimization for required weld penetration. • Parametric study of actual scenarios like air gap, plate & beam misalignment. • Destructive and non-destructive examination of the welds and He-leak testing. - Abstract: A vacuum seal using the lip sealing technique is emerging as the most likely choice for fusion devices, to comply with the requirement of maintainability. The welding technology considered for lip sealing is laser welding, due to the attributes of small spot diameter, low concentrated heat input, high precision and penetration. To establish the process, an experiment has been conducted on a sample size of 150 mm × 50 mm having thickness of 2 mm, material AISI304L to assess the dependence of beam parameters like, laser power, speed and focusing distance on penetration and quality of weld joint. Further, the assessment of the effect of welding set-up variables like air-gap between plates, plate misalignment, and laser beam misalignment on the weld quality is also required. This paper presents the results of this experimental study and also the plan for developing a large (∼10 m) size laser welded seal, that simulates, appropriately, the configuration required in large dimension fusion devices.

  1. Development of laser beam welding for the lip seal configuration

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Ashish, E-mail: ashish.yadav@iter-india.org [ITER-India, Institute for Plasma Research, Sector 25, Gandhinagar 382016, Gujarat (India); Joshi, Jaydeep; Singh, Dhananjay Kumar [ITER-India, Institute for Plasma Research, Sector 25, Gandhinagar 382016, Gujarat (India); Natu, Harshad [Magod Laser Machining Pvt. Ltd., KIADB Ind. Area, Jigani, Anekal Taluk, Bengaluru 560105 (India); Rotti, Chandramouli; Bandyopadhyay, Mainak; Chakraborty, Arun [ITER-India, Institute for Plasma Research, Sector 25, Gandhinagar 382016, Gujarat (India)

    2015-10-15

    Highlights: • Laser welding parameter optimization for required weld penetration. • Parametric study of actual scenarios like air gap, plate & beam misalignment. • Destructive and non-destructive examination of the welds and He-leak testing. - Abstract: A vacuum seal using the lip sealing technique is emerging as the most likely choice for fusion devices, to comply with the requirement of maintainability. The welding technology considered for lip sealing is laser welding, due to the attributes of small spot diameter, low concentrated heat input, high precision and penetration. To establish the process, an experiment has been conducted on a sample size of 150 mm × 50 mm having thickness of 2 mm, material AISI304L to assess the dependence of beam parameters like, laser power, speed and focusing distance on penetration and quality of weld joint. Further, the assessment of the effect of welding set-up variables like air-gap between plates, plate misalignment, and laser beam misalignment on the weld quality is also required. This paper presents the results of this experimental study and also the plan for developing a large (∼10 m) size laser welded seal, that simulates, appropriately, the configuration required in large dimension fusion devices.

  2. Concurrent laser welding and annealing exploiting robotically manipulated optical fibers

    Science.gov (United States)

    Abdullah, Hussein A.; Siddiqui, Rafiq A.

    2002-12-01

    Present investigation reports on the effects of incorporating pre- and post-heating on the mechanical properties of laser-welded joints, in normal air condition. Two common types of steels, i.e. mild steel, and stainless steel were welded with Lumonic's MS 830 Nd 3+:YAG laser machine, with an output capacity of 400 W. Due to the low integrated energy input required for laser welded joints, the welded region are often cooled too rapidly via conduction to the surrounding material and atmosphere, which leads to hardness discontinuities in the fusion and heat affected zone. The effects of in-process laser annealing on the mechanical properties and microstructure of laser-welded joints are important in any manufacturing operation. To improve the poor weld characteristics, this work investigates the use of automated dual-beam delivery system to implement a pre- or post-heating technique, simultaneously with the welding process. The results show that proper selection of the control parameters for the pre- or post-heating can reduce the hardness of the weld significantly and improve the welded joints mechanical properties, such as higher tensile strength and better durability.

  3. Hybrid laser arc welding: State-of-art review

    Science.gov (United States)

    Acherjee, Bappa

    2018-02-01

    Hybrid laser arc welding simultaneously utilizes the arc welding and the laser welding, in a common interaction zone. The synergic effects of laser beam and eclectic arc in the same weld pool results in an increase of welding speed and penetration depth along with the enhancement of gap bridging capability and process stability. This paper presents the current status of this hybrid technique in terms of research, developments and applications. Effort is made to present a comprehensive technical know-how about this process through a systematic review of research articles, industrial catalogues, technical notes, etc. In the introductory part of the review, an overview of the hybrid laser arc welding is presented, including operation principle, process requirements, historical developments, benefits and drawbacks of the process. This is followed by a detailed discussion on control parameters those govern the performance of hybrid laser arc welding process. Thereafter, a report of improvements of performance and weld qualities achieved by using hybrid welding process is presented based on review of several research papers. The succeeding sections furnish the examples of industrial applications and the concluding remarks.

  4. Role of arc mode in laser-metal active gas arc hybrid welding of mild steel

    International Nuclear Information System (INIS)

    Li, Geng; Zhang, Chen; Gao, Ming; Zeng, Xiaoyan

    2014-01-01

    Highlights: • Pulsed arc is more effective to improve the stability of laser-arc hybrid welding. • LCHW has the highest fraction of acicular ferrite and high-angle grain boundaries. • Grain refinement depends on effective current of the arc. • LSHW has the most apparent vestige of texture components. • The microstructure and microtexture formation mechanisms were summarized. - Abstract: Arc mode plays an important role in joint characterizations of arc welding, but it has been seldom considered in laser-arc hybrid welding. This paper investigated the role of arc mode on laser-metal active gas (MAG) arc hybrid welding of mild steel. Three arc modes were employed, which were cold metal transfer (CMT), pulsed spray arc and standard short circuiting arc. Microtexture of the joints were observed and measured via electron back scattering diffraction (EBSD) system to reveal the effect of arc mode on microstructure. Mechanical properties of the joints were evaluated by tensile and Charpy V-notch impact tests. It was found that both the stability and mechanical properties of laser-CMT hybrid welding (LCHW) is the best, while those of laser-standard short circuiting arc welding (LSHW) is the worst. OM and EBSD results showed that the fraction of acicular ferrite and high-angle grain boundaries in fusion zone decreases gradually in the sequence of LCHW, laser-pulsed spray arc welding and LSHW, while the mean grain size increases gradually. Finally, the microstructure formation mechanisms and the relationship between microstructure and mechanical properties were summarized by the loss of alloying element and the stirring effect in molten pool

  5. Laser Welding of Sub-assemblies before Forming

    DEFF Research Database (Denmark)

    Rasmussen, Mads; Olsen, Flemmming Ove; Pecas, Paulo

    1996-01-01

    This paper describes some experimental investigations of the formability of CO2-laser-welded 0.75 mm and 1.25 mm low carbon steel. There will be a description of how the laser welded blanks behave in different forming tests, and the influene of misalignment and undercut on the formability....... The quality is evalutated by measuring the imit strain and the limit effective strain for the laser welded sheets and the base material. These strains will be presented in a forming limit diagram (FLD). Finally the formability of the laser sheets is compared to that of the base materials....

  6. Hybrid laser arc welding of a used fuel container

    Energy Technology Data Exchange (ETDEWEB)

    Boyle, C. [Nuclear Waste Management Organization (NWMO), Toronto, Ontario (Canada); Martel, P. [Novika Solutions, La Pocatiere, Quebec (Canada)

    2015-09-15

    The Nuclear Waste Management Organization (NWMO) has designed a novel Used Fuel Container (UFC) optimized for CANDU used nuclear fuel. The Mark II container is constructed of nuclear grade pipe for the body and capped with hemi-spherical heads. The head-to-shell joint fit-up features an integral backing designed for external pressure, eliminating the need for a full penetration closure weld. The NWMO and Novika Solutions have developed a partial penetration, single pass Hybrid Laser Axe Weld (HLAW) closure welding process requiring no post-weld heat treatment. This paper will discuss the joint design, HLAW process, associated welding equipment, and prototype container fabrication. (author)

  7. Effect of weld morphology on mechanical response and failure of friction stir welds in a naturally aged aluminium alloy

    International Nuclear Information System (INIS)

    Imam, Murshid; Biswas, Kajal; Racherla, Vikranth

    2013-01-01

    Highlights: ► Friction stir welds of AA 6063-T4 are obtained using three tool pin profiles. ► Signature of weld defects in mechanical response of welds is investigated. ► Correlation between peak temperatures in HAZs and their hardness is studied. ► Reasons for strengthening of WNZ and softening of HAZs are found using TEM and XRD. ► A FEM model for the weld zone is developed and validated. -- Abstract: Friction stir butt welds in 6063-T4 aluminium alloy were obtained using square and two tapered tool pin profiles. Tensile tests at 0°, 45°, and 90° to the weld line, hardness contours in the weld cross-section, temperatures in the heat affected zones, cross-sectional macrographs, transmission electron micrographs, and X-ray diffraction studies were used to characterize the welds. In transverse weld specimen, tunnel defects appearing at higher weld speeds for tapered pin profiles, were found to result in mechanical instabilities, i.e. sharp drops in load–displacement curves, much before macroscopic necking occured. Further, in comparison to the base metal, a marked reduction in ductility was observed even in transverse specimen with defect free welds. Hardness contours in the weld cross-section suggest that loss in ductility is due to significant softening in heat affected zone on the retreating side. Transmission electron microscopy images demonstrate that while recovery and overaging are responsible for softening in the heat affected zone, grain size refinement from dynamic recrystallization is responsible for strengthening of the weld nugget zone. X-ray diffraction studies in the three weld zones: weld nugget zone, heat affected zone, and the base metal corroborate these findings. A weld zone model, for use in forming simulations on friction stir welded plates of naturally aged aluminium alloys, was proposed based on mechanical characterization tests. The model was validated using finite element analysis.

  8. Effect of rhenium on the structure and properties of the weld metal of a molybdenum alloy

    Science.gov (United States)

    Dyachenko, V. V.; Morozov, B. P.; Tylkina, M. A.; Savitskiy, Y. M.; Nikishanov, V. V.

    1984-01-01

    The structure and properties of welds made in molybdenum alloy VM-1 as a function of rhenium concentrations in the weld metal were studied. Rhenium was introduced into the weld using rhenium wire and tape or wires of Mo-47Re and Mo-52Re alloys. The properties of the weld metal were studied by means of metallographic techniques, electron microscopy, X-ray analysis, and autoradiography. The plasticity of the weld metal sharply was found to increase with increasing concentration of rhenium up to 50%. During welding, a decarburization process was observed which was more pronounced at higher concentrations of rhenium.

  9. Friction Welding of Aluminium and Aluminium Alloys with Steel

    Directory of Open Access Journals (Sweden)

    Andrzej Ambroziak

    2014-01-01

    Full Text Available The paper presents our actual knowledge and experience in joining dissimilar materials with the use of friction welding method. The joints of aluminium and aluminium alloys with the different types of steel were studied. The structural effects occurring during the welding process were described. The mechanical properties using, for example, (i microhardness measurements, (ii tensile tests, (iii bending tests, and (iv shearing tests were determined. In order to obtain high-quality joints the influence of different configurations of the process such as (i changing the geometry of bonding surface, (ii using the interlayer, or (iii heat treatment was analyzed. Finally, the issues related to the selection of optimal parameters of friction welding process were also investigated.

  10. Mechanical Behaviour Investigation Of Aluminium Alloy Tailor Welded Blank Developed By Using Friction Stir Welding Technique

    Science.gov (United States)

    Dwi Anggono, Agus; Sugito, Bibit; Hariyanto, Agus; Subroto; Sarjito

    2017-10-01

    The objective on the research was to investigate the mechanical properties and microstructure of tailor welded blank (TWB) made from AA6061-T6 and AA1100 using friction stir welding (FSW) process. Due to the dissimilar mechanical properties of the two aluminium alloys, microhardness test was conducted to measure the hardness distribution across the weld nugget. The mixing of two distinct materials was influenced by tool rotation speed. Therefore, microstructure analysis was carried out to investigate the grain size and shape. The grain size of AA6061-T6 has increased in the heat affected zone (HAZ) while for AA1100 has decreased. In the weld nugget, it has found a hook defects in the dissimilar aluminium joining. By using monotonic tensile load, the different weld line direction was observed with the expansion in tool rotation. The joints failure were consistently on the area of AA1100 series. Furthermore, two specimens were investigated, one through the dissimilar aluminium and the other through similiar material. Inspection of the weld nugget hardness was shown that nonhomogen material intermixing during the stiring process as confirmed by microhardness measurement.

  11. Assisting Gas Optimization in CO2 Laser Welding

    DEFF Research Database (Denmark)

    Gong, Hui; Olsen, Flemming Ove

    1996-01-01

    are applied with three different flow rates for each of the gases. A number of systematic laboratory experiments is carried out by employing various experimental designs, 33 and 32 Factorial Design. In the experiments a CO2 laser is used to weld thin sheets of mild steel. The welding specimens are evaluated....... The relations between the gas parameters and signal frequencies are studied. Finally the relationships of the gas parameters and weld characteristics are studied. The possibility of using photo diode signals in controlling the gas parameters is discussed.KeywordsCO2 laser welding, assisting gas parameters...

  12. TIG welding phenomenon and properties of welds in welding atmospheres with various oxygen and nitrogen partial pressures. Pt. 2. Study on welding of zirconium alloy tubing. 5

    International Nuclear Information System (INIS)

    Komuro, Kojiro; Mishima, Teruaki; Kurosawa, Satoshi; Tsuboi, Hajime

    1994-01-01

    The purpose of this study is to investigate the influence of extremely low levels of oxygen and nitrogen partial pressure, P O2 and P N2 in pressurized TIG welding atmospheres on the welding phenomenon and properties of welds of zirconium alloy tubing. In TIG welding of Zircaloy-2 tubing in welding atmospheres with various P O2 and P N2 in total pressure (P T ) of 0.32 MPa (optionally 0.55 MPa), the arc voltages were measured and the properties of welds (surface discoloration, oxygen and nitrogen contents) were examined. Although definite arc voltage change is not observable at welding in ≤12.9 Pa of P O2 and 15.6-67.2 Pa of P O2+N2 (P O2 /P N2 =1/4), a tendency of arc voltage drop with increase of P N2 is observed at welding in 13.1-53.0 Pa of P N2 (P O2 =0.3 Pa). The surface of weld metal and heat affected zone (HAZ) in the atmosphere of 0.3 Pa of P O2 and 1.3 Pa of P N2 remains bright. The surface discoloration is observable slightly on weld metal and HAZ in the atmosphere of 3.4 Pa of P O2 , and with increase of P O2 the initial straw color becomes darker until it gets partially blue. No surface discoloration is observable on weld metals and HAZ in the atmospheres of P N2 ≤ 53.0 Pa with 0.3 Pa of P O2 . The nitrogen content [N] in the weld metal increases linearly with increase of √P N2 , and the increasing rate of [N] in inner part of weld metal is lower than that of [N] in outer part. The oxygen content [O] in outer part of weld metal increases linearly with increase of √P O2 and shows same relations as [N] although the values of [O] in the weld metals fluctuate more than [N]. The increasing rates of [N] and [O] in the weld metal under P T =0.32 MPa are lower than that of [N] and [O] in the weld metal under P T =0.10 MPa which is reported in Report 3. (author)

  13. Overview of welding of oxide dispersion strengthened (ODS) alloys for advanced nuclear reactor applications

    International Nuclear Information System (INIS)

    Kalvala, Prasad Rao; Raja, K.S.; Misra, Manoranjan; Tache, Ricard A.

    2009-01-01

    Oxide dispersion strengthened (ODS) alloys are very promising materials for Generation IV reactors with a potential to be used at elevated temperatures under severe neutron exposure environment. Welding of the ODS alloys is an understudied problem. In this paper, an overview of welding of the ODS alloys useful for advanced nuclear reactor applications is presented. The microstructural changes and the resultant mechanical properties obtained by various solid state welding processes are reviewed. Based on our results on PM2000, an approach for future work on welding of the ODS alloys is suggested. (author)

  14. Impact toughness of laser surface alloyed Aluminium

    CSIR Research Space (South Africa)

    Mabhali, Luyolo AB

    2012-03-01

    Full Text Available Laser surface alloying of aluminium AA1200 was performed with a 4kW Nd:YAG laser and the impact resistance of the alloys was investigated. The alloying powders were a mixture of Ni, Ti and SiC in different proportions. Surfaces reinforced...

  15. A novel weld seam detection method for space weld seam of narrow butt joint in laser welding

    Science.gov (United States)

    Shao, Wen Jun; Huang, Yu; Zhang, Yong

    2018-02-01

    Structured light measurement is widely used for weld seam detection owing to its high measurement precision and robust. However, there is nearly no geometrical deformation of the stripe projected onto weld face, whose seam width is less than 0.1 mm and without misalignment. So, it's very difficult to ensure an exact retrieval of the seam feature. This issue is raised as laser welding for butt joint of thin metal plate is widely applied. Moreover, measurement for the seam width, seam center and the normal vector of the weld face at the same time during welding process is of great importance to the welding quality but rarely reported. Consequently, a seam measurement method based on vision sensor for space weld seam of narrow butt joint is proposed in this article. Three laser stripes with different wave length are project on the weldment, in which two red laser stripes are designed and used to measure the three dimensional profile of the weld face by the principle of optical triangulation, and the third green laser stripe is used as light source to measure the edge and the centerline of the seam by the principle of passive vision sensor. The corresponding image process algorithm is proposed to extract the centerline of the red laser stripes as well as the seam feature. All these three laser stripes are captured and processed in a single image so that the three dimensional position of the space weld seam can be obtained simultaneously. Finally, the result of experiment reveals that the proposed method can meet the precision demand of space narrow butt joint.

  16. Laser welding of 3 mm thick laser-cut AISI 304 stainless steel sheet

    Science.gov (United States)

    Kumar, Harish; Ganesh, P.; Kaul, Rakesh; Rao, B. Tirumala; Tiwari, Pragya; Nath, A. K.; Brajpuriya, Ranjeet; Chaudhari, S. M.

    2006-02-01

    The objective of the present work was to study the laser weldability of laser-cut 3 mm thick AISI 304 austenitic stainless steel sheet (using oxygen as an assist gas). For minimizing heat input during laser cutting, which is an important factor influencing the thickness of the oxide layer on the cut surface, laser cutting was performed in pulsed mode. The results of the study demonstrated that although the laser welding of laser-cut specimens did not result in the formation of weld defects, the resultant laser weldments exhibited reduced ductility with respect to base metal and bead-on-plate laser weldments. Laser-cut and laser-welded specimens also displayed higher notch sensitivity than the base metal. However, laser-cut and laser-welded specimens still possessed enough ductility to pass guided bend tests.

  17. Heat input effect of friction stir welding on aluminium alloy AA 6061-T6 welded joint

    Directory of Open Access Journals (Sweden)

    Sedmak Aleksandar

    2016-01-01

    Full Text Available This paper deals with the heat input and maximum temperature developed during friction stir welding with different parameters. Aluminium alloy (AA 6061-T6 has been used for experimental and numerical analysis. Experimental analysis is based on temperature measurements by using infrared camera, whereas numerical analysis was based on empirical expressions and finite element method. Different types of defects have been observed in respect to different levels of heat input.

  18. Laser Beam Oscillation Strategies for Fillet Welds in Lap Joints

    Science.gov (United States)

    Müller, Alexander; Goecke, Sven-F.; Sievi, Pravin; Albert, Florian; Rethmeier, Michael

    Laser beam oscillation opens up new possibilities of influencing the welding process in terms of compensation of tolerances and reduction of process emissions that occur in industrial applications, such as in body-in-white manufacturing. The approaches are to adapt the melt pool width in order to generate sufficient melt volume or to influence melt pool dynamics, e.g. for a better degassing. Welding results are highly dependent on the natural frequency of the melt pool, the used spot diameter and the oscillation speed of the laser beam. The conducted investigations with an oscillated 300 μm laser spot show that oscillation strategies, which are adjusted to the joining situation improve welding result for zero-gap welding as well as for bridging gaps to approximately 0.8 mm. However, a complex set of parameters has to be considered in order to generate proper welding results. This work puts emphasize on introducing them.

  19. Thermal and molecular investigation of laser tissue welding

    Energy Technology Data Exchange (ETDEWEB)

    Small, W., IV

    1998-06-01

    Despite the growing number of successful animal and human trials, the exact mechanisms of laser tissue welding remain unknown. Furthermore, the effects of laser heating on tissue on the molecular scale are not fully understood. To address these issues, a multi-front attack oil both extrinsic (solder/patch mediated) and intrinsic (laser only) tissue welding was launched using two-color infrared thermometry, computer modeling, weld strength assessment, biochemical assays, and vibrational spectroscopy. The coupling of experimentally measured surface temperatures with the predictive numerical simulations provided insight into the sub-surface dynamics of the laser tissue welding process. Quantification of the acute strength of the welds following the welding procedure enabled comparison among trials during an experiment, with previous experiments, and with other studies in the literature. The acute weld integrity also provided an indication of tile probability of long-term success. Molecular effects induced In the tissue by laser irradiation were investigated by measuring tile concentrations of specific collagen covalent crosslinks and characterizing the Fourier-Transform infrared (FTIR) spectra before and after the laser exposure.

  20. Diffractive beam shaping for enhanced laser polymer welding

    Science.gov (United States)

    Rauschenberger, J.; Vogler, D.; Raab, C.; Gubler, U.

    2015-03-01

    Laser welding of polymers increasingly finds application in a large number of industries such as medical technology, automotive, consumer electronics, textiles or packaging. More and more, it replaces other welding technologies for polymers, e. g. hot-plate, vibration or ultrasonic welding. At the same rate, demands on the quality of the weld, the flexibility of the production system and on processing speed have increased. Traditionally, diode lasers were employed for plastic welding with flat-top beam profiles. With the advent of fiber lasers with excellent beam quality, the possibility to modify and optimize the beam profile by beam-shaping elements has opened. Diffractive optical elements (DOE) can play a crucial role in optimizing the laser intensity profile towards the optimal M-shape beam for enhanced weld seam quality. We present results on significantly improved weld seam width constancy and enlarged process windows compared to Gaussian or flat-top beam profiles. Configurations in which the laser beam diameter and shape can be adapted and optimized without changing or aligning the laser, fiber-optic cable or optical head are shown.

  1. Characteristics of Resistance Spot Welded Ti6Al4V Titanium Alloy Sheets

    Directory of Open Access Journals (Sweden)

    Xinge Zhang

    2017-10-01

    Full Text Available Ti6Al4V titanium alloy is applied extensively in the aviation, aerospace, jet engine, and marine industries owing to its strength-to-weight ratio, excellent high-temperature properties and corrosion resistance. In order to extend the application range, investigations on welding characteristics of Ti6Al4V alloy using more welding methods are required. In the present study, Ti6Al4V alloy sheets were joined using resistance spot welding, and the weld nugget formation, mechanical properties (including tensile strength and hardness, and microstructure features of the resistance spot-welded joints were analyzed and evaluated. The visible indentations on the weld nugget surfaces caused by the electrode force and the surface expulsion were severe due to the high welding current. The weld nugget width at the sheets’ faying surface was mainly affected by the welding current and welding time, and the welded joint height at weld nugget center was chiefly associated with electrode force. The maximum tensile load of welded joint was up to 14.3 kN in the pullout failure mode. The hardness of the weld nugget was the highest because of the coarse acicular α′ structure, and the hardness of the heat-affected zone increased in comparison to the base metal due to the transformation of the β phase to some fine acicular α′ phase.

  2. Effect of friction stir welding and post-weld heat treatment on a nanostructured ferritic alloy

    International Nuclear Information System (INIS)

    Mazumder, B.; Yu, X.; Edmondson, P.D.; Parish, C.M.; Miller, M.K.; Meyer, H.M.; Feng, Z.

    2016-01-01

    Nanostructured ferritic alloys (NFAs) are new generation materials for use in high temperature energy systems, such as nuclear fission or fusion reactors. However, joining these materials is a concern, as their unique microstructure is destroyed by traditional liquid-state welding methods. The microstructural evolution of a friction stir welded 14YWT NFA was investigated by atom probe tomography, before and after a post-weld heat treatment (PWHT) at 1123K. The particle size, number density, elemental composition, and morphology of the titanium-yttrium-oxygen-enriched nanoclusters (NCs) in the stir and thermally-affected zones were studied and compared with the base metal. No statistical difference in the size of the NCs was observed in any of these conditions. After the PWHT, increases in the number density and the oxygen enrichment in the NCs were observed. Therefore, these new results provide additional supporting evidence that friction stir welding appears to be a viable joining technique for NFAs, as the microstructural parameters of the NCs are not strongly affected, in contrast to traditional welding techniques.

  3. Effect of friction stir welding and post-weld heat treatment on a nanostructured ferritic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Mazumder, B., E-mail: mazumderb@ornl.gov [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Yu, X.; Edmondson, P.D.; Parish, C.M. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Miller, M.K. [Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Meyer, H.M.; Feng, Z. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2016-02-15

    Nanostructured ferritic alloys (NFAs) are new generation materials for use in high temperature energy systems, such as nuclear fission or fusion reactors. However, joining these materials is a concern, as their unique microstructure is destroyed by traditional liquid-state welding methods. The microstructural evolution of a friction stir welded 14YWT NFA was investigated by atom probe tomography, before and after a post-weld heat treatment (PWHT) at 1123K. The particle size, number density, elemental composition, and morphology of the titanium-yttrium-oxygen-enriched nanoclusters (NCs) in the stir and thermally-affected zones were studied and compared with the base metal. No statistical difference in the size of the NCs was observed in any of these conditions. After the PWHT, increases in the number density and the oxygen enrichment in the NCs were observed. Therefore, these new results provide additional supporting evidence that friction stir welding appears to be a viable joining technique for NFAs, as the microstructural parameters of the NCs are not strongly affected, in contrast to traditional welding techniques.

  4. Aluminum Welding: Out-of-Position Welding of 5000 Series Aluminum Alloys Using Pulse GMAW Power Sources

    Science.gov (United States)

    1984-01-01

    ALUMINIUM ALLOY SHEET: .063 INCH THICKNESS; ER 5356 ALUMINUM...QQ-A-200/5 QQ-A-200/4 ALUMINUM ALLOY COMPOSITION 5083 5086 5052 5456 5454 5052 5456 5454 5086 5083 TYPE OF MATERIAL Plate & Sheet Plate & Sheet Plate...Shapes, Tube, Wire 4.2 Filler Metals Filler wire alloys with the following for welding aluminum shall be in accordance chart: Base Alloy 5052 5083

  5. Melt pool vorticity in deep penetration laser material welding

    Indian Academy of Sciences (India)

    In the present study, the vorticity of melt motion in the keyhole and weld pool has been evaluated in case of high power CO2 laser beam welding. The circulation of vorticity is obtained as a function of Reynolds number for a given keyhole volume which is linked to Mach number variation. The shear stress and thermal fluxes ...

  6. Melt pool vorticity in deep penetration laser material welding

    Indian Academy of Sciences (India)

    bility of stationary laser weld keyholes have been investigated using numerical simulation. The effect of ... with a high aspect ratio and this is the most advantageous feature of welding by high-energy- density beams. .... Cg is a gas flow parameter, Cg (Re) in equation (4) depends on the Reynolds number Re = rkhvl vg.

  7. CFD-based model for melt flow in laser beam welding of aluminium with coaxial magnetic field

    Science.gov (United States)

    Gatzen, M.; Tang, Z.

    The use of magnetic fields to influence weld bead shape and dilution in laser welding of aluminium alloys was recently suggested. For the case of laser welding of hot-cracking sensitive aluminium alloys with silicon-containing filler wire it was already demonstrated that applying alternating magnetic fields has an impact on the dilution of silicon in the melt pool, yielding sufficient silicon content throughout the weld to suppress hot-cracking. This is due to the changed melt flow condition resulting from induced magnetic volume forces. In this paper, a CFD-based model will be presented that was used to numerically calculate the resulting velocity field for laser beam welding of aluminium with external applied magnetic fields. The model includes temperaturedepending material properties, surface tension and buoyancy. The inhomogeneous magnetic flux density distribution implemented in this model has been derived from Hall sensor probes of a welding head prototype used for experimental investigations. It is shown that a steady magnetic field applied coaxially to the laser beam will affect the direction of melt flow and can be described as an inhomogeneous electromagnetic break.

  8. Effect of tool shape and welding parameters on mechanical properties and microstructure of dissimilar friction stir welded aluminium alloys

    Directory of Open Access Journals (Sweden)

    Chetan Aneja

    2016-07-01

    Full Text Available In the present experimental study, dissimilar aluminum alloy AA5083 and AA6082 were friction stir welded by varying tool shape, welding speed and rotary speed of the tool in order to investigate the effect of varying tool shape and welding parameters on the mechanical properties as well as microstructure. The friction stir welding (FSW process parameters have great influence on heat input per unit length of weld. The outcomes of experimental study prove that mechanical properties increases with decreasing welding speed. Furthermore mechanical properties were also found to improve as the rotary speed increases and the same phenomenon was found to happen while using straight cylindrical threaded pin profile tool. The microstructure of the dissimilar joints revealed that at low welding speeds, the improved material mixing was observed. The similar phenomenon was found to happen at higher rotational speeds using straight cylindrical threaded tool.

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

    Science.gov (United States)

    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. Low-cycle fatigue of welded joints of alloy AMg5

    International Nuclear Information System (INIS)

    Modestova, R.V.; Borisenko, V.A.; Parfenova, I.N.; Stepanov, S.V.

    1986-01-01

    The authors study the low-cycle fatigue of welded joints of aluminum alloy AMg5 in order to determine the cyclic strength coefficient of welded seams. Tests were carried out on cylindrical specimens of the parent metal, welded specimens, and models of welded vessels. The average values of mechanical properties of the specimens and the parent metal are shown. It is shown that when designing welded vessels of aluminum alloy AMg5, the permissible amplitudes of conventional compressive stresses are recommended to be determined as the lower of the two values calculated using the equations presented

  11. Sensor development and integration for robotized laser welding

    NARCIS (Netherlands)

    Iakovou, D.

    2009-01-01

    Laser welding requires fast and accurate positioning of the laser beam over the seam trajectory. The task of accurate positioning of the laser tools is performed by robotic systems. It is therefore necessary to teach the robot the path it has to follow. Seam teaching is implemented in several ways:

  12. Energy losses estimation during pulsed-laser seam welding

    Czech Academy of Sciences Publication Activity Database

    Šebestová, Hana; Havelková, M.; Chmelíčková, H.

    2014-01-01

    Roč. 45, č. 3 (2014), s. 1116-1121 ISSN 1073-5615 R&D Projects: GA MŠk(CZ) LG13007 Institutional support: RVO:68378271 Keywords : laser welding * pulsed-laser * Nd:YAG laser Subject RIV: JP - Industrial Processing Impact factor: 1.461, year: 2014

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

    Science.gov (United States)

    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.

  14. Thermal and molecular investigation of laser tissue welding

    Science.gov (United States)

    Small, Ward, IV

    Despite the growing number of successful animal and human trials, the exact mechanisms of laser tissue welding remain unknown. Furthermore, the effects of laser heating on tissue on the molecular scale are not fully understood. To address these issues, a multi-front attack on both extrinsic (solder/patch mediated) and intrinsic (laser only) tissue welding was launched using two-color infrared thermometry, computer modeling, weld strength assessment, biochemical assays, and vibrational spectroscopy. The coupling of experimentally measured surface temperatures with the predictive numerical simulations provided insight into the sub surface dynamics of the laser tissue welding process. Quantification of the acute strength of the welds following the welding procedure enabled comparison among trials during an experiment, with previous experiments, and with other studies in the literature. The acute weld integrity also provided an indication of the probability of long-term success. Molecular effects induced in the tissue by laser irradiation were investigated by measuring the concentrations of specific collagen covalent crosslinks and measuring the infrared absorption spectra before and after the laser exposure. This investigation yielded results pertaining to both the methods and mechanisms of laser tissue welding. The combination of two-color infrared thermometry to obtain accurate surface temperatures free from emissivity bias and computer modeling illustrated the importance of including evaporation in the simulations, which effectively serves as an inherent cooling mechanism during laser irradiation. Moreover, the hydration state predicted by the model was useful in assessing the role of electrostatic versus covalent bonding in the fusion. These tools also helped elicit differences between dye- enhanced liquid solders and solid-matrix patches in laser-assisted tissue welding, demonstrating the significance of repeatable energy delivery. Surprisingly, covalent bonds

  15. Study of Dissimilar Welding AA6061 Aluminium Alloy and AZ31B Magnesium Alloy with ER5356 Filler Using Friction Stir Welding

    Science.gov (United States)

    Mahamud, M. I. I.; Ishak, M.; Halil, A. M.

    2017-09-01

    This paper is to study of dissimilar welding AA6061 aluminium alloy and AZ31B magnesium alloy with ER5356 filler using friction stir welding. 2 mm thick plates of aluminium and magnesium were used. Friction stir welding operations were performed at different rotation and travel speeds and used the fixed tilt angle which is 3°. The rotation speeds varied from 800 to 1100 rpm, and the travel speed varied from 80 to 100 mm/min. In the range rotation speed of 800 to 1000 rpm and welding speed of 80 to 100 mm/min there are no defect at the weld. Tensile test show the higher tensile strength is 198 MPa and the welding efficiency is about 76%.

  16. Crack growth rates of nickel alloy welds in a PWR environment.

    Energy Technology Data Exchange (ETDEWEB)

    Alexandreanu, B.; Chopra, O. K.; Shack, W. J.; Energy Technology

    2006-05-31

    In light water reactors (LWRs), vessel internal components made of nickel-base alloys are susceptible to environmentally assisted cracking. A better understanding of the causes and mechanisms of this cracking may permit less conservative estimates of damage accumulation and requirements on inspection intervals. A program is being conducted at Argonne National Laboratory to evaluate the resistance of Ni alloys and their welds to environmentally assisted cracking in simulated LWR coolant environments. This report presents crack growth rate (CGR) results for Alloy 182 shielded-metal-arc weld metal in a simulated pressurized water reactor (PWR) environment at 320 C. Crack growth tests were conducted on 1-T compact tension specimens with different weld orientations from both double-J and deep-groove welds. The results indicate little or no environmental enhancement of fatigue CGRs of Alloy 182 weld metal in the PWR environment. The CGRs of Alloy 182 in the PWR environment are a factor of {approx}5 higher than those of Alloy 600 in air under the same loading conditions. The stress corrosion cracking for the Alloy 182 weld is close to the average behavior of Alloy 600 in the PWR environment. The weld orientation was found to have a profound effect on the magnitude of crack growth: cracking was found to propagate faster along the dendrites than across them. The existing CGR data for Ni-alloy weld metals have been compiled and evaluated to establish the effects of key material, loading, and environmental parameters on CGRs in PWR environments. The results from the present study are compared with the existing CGR data for Ni-alloy welds to determine the relative susceptibility of the specific Ni-alloy weld to environmentally enhanced cracking.

  17. Diffusion Welding of Alloys for Molten Salt Service - Status Report

    Energy Technology Data Exchange (ETDEWEB)

    Denis Clark; Ronald Mizia

    2012-05-01

    The present work is concerned with heat exchanger development for molten salt service, including the proposed molten salt reactor (MSR), a homogeneous reactor in which the fuel is dissolved in a circulating fluid of molten salt. It is an outgrowth of recent work done under the Next Generation Nuclear Plant (NGNP) program; what the two reactor systems have in common is an inherently safe nuclear plant with a high outlet temperature that is useful for process heat as well as more conventional generation The NGNP program was tasked with investigating the application of a new generation of nuclear power plants to a variety of energy needs. One baseline reactor design for this program is a high temperature, gas-cooled reactor (HTGR), which provides many options for energy use. These might include the conventional Rankine cycle (steam turbine) generation of electricity, but also other methods: for example, Brayton cycle (gas turbine) electrical generation, and the direct use of the high temperatures characteristic of HTGR output for process heat in the chemical industry. Such process heat is currently generated by burning fossil fuels, and is a major contributor to the carbon footprint of the chemical and petrochemical industries. The HTGR, based on graphite fuel elements, can produce very high output temperatures; ideally, temperatures of 900 C or even greater, which has significant energy advantages. Such temperatures are, of course, at the frontiers of materials limitations, at the upper end of the performance envelope of the metallic materials for which robust construction codes exist, and within the realm of ceramic materials, the fabrication and joining of which, on the scale of large energy systems, are at an earlier stage of development. A considerable amount of work was done in the diffusion welding of materials of interest for HTGR service with alloys such as 617 and 800H. The MSR output temperature is also materials limited, and is projected at about 700 C

  18. Diffusion Welding of Alloys for Molten Salt Service - Status Report

    Energy Technology Data Exchange (ETDEWEB)

    Denis Clark; Ronald Mizia; Piyush Sabharwall

    2012-09-01

    The present work is concerned with heat exchanger development for molten salt service, including the proposed molten salt reactor (MSR), a homogeneous reactor in which the fuel is dissolved in a circulating fluid of molten salt. It is an outgrowth of recent work done under the Next Generation Nuclear Plant (NGNP) program; what the two reactor systems have in common is an inherently safe nuclear plant with a high outlet temperature that is useful for process heat as well as more conventional generation The NGNP program was tasked with investigating the application of a new generation of nuclear power plants to a variety of energy needs. One baseline reactor design for this program is a high temperature, gas-cooled reactor (HTGR), which provides many options for energy use. These might include the conventional Rankine cycle (steam turbine) generation of electricity, but also other methods: for example, Brayton cycle (gas turbine) electrical generation, and the direct use of the high temperatures characteristic of HTGR output for process heat in the chemical industry. Such process heat is currently generated by burning fossil fuels, and is a major contributor to the carbon footprint of the chemical and petrochemical industries. The HTGR, based on graphite fuel elements, can produce very high output temperatures; ideally, temperatures of 900 °C or even greater, which has significant energy advantages. Such temperatures are, of course, at the frontiers of materials limitations, at the upper end of the performance envelope of the metallic materials for which robust construction codes exist, and within the realm of ceramic materials, the fabrication and joining of which, on the scale of large energy systems, are at an earlier stage of development. A considerable amount of work was done in the diffusion welding of materials of interest for HTGR service with alloys such as 617 and 800H. The MSR output temperature is also materials limited, and is projected at about 700

  19. The Evolution of Microstructures and the Properties of Bulk Metallic Glass with Consubstantial Composition Laser Welding

    Directory of Open Access Journals (Sweden)

    Pingjun Tao

    2016-09-01

    Full Text Available A Zr55Cu30Ni5Al10 plate-like bulk metallic glass (BMG was prepared using copper mold suction casting. Additionally, alloy powders with the same nominal composition were synthesized. The alloy powders were welded or melted to the cleaned surface of the BMG with a laser beam acceleration voltage of 60 kV, a beam current range from 60 to 100 mA, a welding speed of 60 mm/s, as well as an impulse width of 3.0 ms. The effect of consubstantial composition welding on the microstructures and properties was investigated. The molten and subsequently solidified metallic mixtures remain an amorphous structure, but the enthalpy of the welded or melted position varies due to the combination of the micro-structural relaxation and nano-crystals precipitated during the energy inputs. The surface layers of the BMG can be significantly intensified after welding processes; however, the heat-affected zones (HAZs exhibit a slight degradation in mechanical properties with respect to the BMG matrix. This study has important reference value for specialists working on the promotion of applications of BMGs.

  20. Laser-Beam Welding Impact on the Deformation Properties of Stainless Steels When Used for Automotive Applications

    Directory of Open Access Journals (Sweden)

    Evin Emil

    2016-09-01

    Full Text Available Materials other than standard and advanced high strength steels are remarkable for the thin-walled structures of the car-body in recent years in order to safety enhancement, weight and emission reduction, corrosion resistance improvement. Thus, there are presented in the paper the deformation properties of laser welded austenitic AISI 304 and ferritic AISI 430 stainless steels compared to these one measured for the high strength low alloyed steel H220PD. The properties were researched by tensile test and 3-point bending test with fixed ends on specimens made of basic material and laser welded one. The specimens were welded by solid state fiber laser YLS-5000 in longitudinal direction (the load direction. The deformation properties such as strength, stiffness and deformation work were evaluated and compared. The strength and stiffness were calculated from tensile test results and the deformation work was calculated from both, tensile test and 3-point bending test results. There has been found only minor effect of laser welding to the deformation properties for high strength low alloyed steel H220PD and austenitic stainless steel AISI 304. Otherwise, the laser welding strongly influenced the deformation work of the ferritic stainless steel AISI 430 as well as the elongation at tensile test.

  1. Mechanical Behaviour of Inconel 718 Thin-Walled Laser Welded Components for Aircraft Engines

    Directory of Open Access Journals (Sweden)

    Enrico Lertora

    2014-01-01

    Full Text Available Nickel alloys are very important in many aerospace applications, especially to manufacture gas turbines and aero engine components, where high strength and temperature resistance are necessary. These kinds of alloys have to be welded with high energy density processes, in order to preserve their high mechanical properties. In this work, CO2 laser overlap joints between Inconel 718 sheets of limited thickness in the absence of postweld heat treatment were made. The main application of this kind of joint is the manufacturing of a helicopter engine component. In particular the aim was to obtain a specific cross section geometry, necessary to overcome the mechanical stresses found in these working conditions without failure. Static and dynamic tests were performed to assess the welds and the parent material fatigue life behaviour. Furthermore, the life trend was identified. This research pointed out that a full joint shape control is possible by choosing proper welding parameters and that the laser beam process allows the maintenance of high tensile strength and ductility of Inconel 718 but caused many liquation microcracks in the heat affected zone (HAZ. In spite of these microcracks, the fatigue behaviour of the overlap welds complies with the technical specifications required by the application.

  2. Innovative Technology of Mechanized Wet Underwater Welding of High-Alloy Corrosion Resistant Steel

    Directory of Open Access Journals (Sweden)

    Kakhovskyi, M.Yu.

    2015-07-01

    Full Text Available The results of the practice of welding-repair technology using self-shielded flux-cored wire for wet underwater welding of high-alloy stainless steels type 18-10 are presented. The application of the technology allows reducing human participation in welding process under the extreme conditions. The practical value of the technology consists in the possibility of welding-repair works directly under water without any additional assembly works.

  3. Fracture toughness of welded joints of a high strength low alloy steel

    International Nuclear Information System (INIS)

    Veiga, S.M.B. da; Bastian, F.L.; Pope, A.M.

    1985-10-01

    The fracture toughness of the different regions of welded joints of a high strength low alloy steel, Niocor 2, was evaluated at different temperatures and compared with the toughness of the base metal. The studied regions were: the weld metal, fusion boundary and heat affected zone. The welding process used was the manual metal arc. It is shown that the weld metal region has the highest toughness values. (Author) [pt

  4. An ultrasonic non-destructive testing method for the measurement of weld width in laser welding of stainless steel

    Science.gov (United States)

    Zhang, Bo; Liu, Fang; Liu, Chang; Li, Jingming; Zhang, Baojun; Zhou, Qingxiang; Han, Xiaohui; Zhao, Yang

    2017-10-01

    In order to inspect welding defects of the laser welding of stainless steel, the piezoelectric bimorph focusing method is presented, the non-destructive testing system is setup. The cutting part of the laser weld sample is used to measure the welding width by metallography and the non-destructive testing system. The results show that the welding width is unevenly distributed, the relation between the ultrasonic signal amplitude and metallography is showed a good linearity, which means the ultrasonic signal amplitude can be used to measure the welding width.

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

    Science.gov (United States)

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

    2013-02-01

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

  6. Laser transmission welding of themoplastic tubes and plates using laser refraction

    Science.gov (United States)

    Ramachandramoorthy, Rajaprakash

    Laser transmission welding is a method of joining plastics, which benefits from the infrared transparency in majority of thermoplastics. During the process, a laser beam passes through the laser transparent part and hits the laser absorbent part, which has been made absorbent using additives such as carbon black. The absorbed laser energy is then converted into heat and in turn welds the interface of the two parts by melting the polymer. In the current work, a new refraction technique of laser transmission welding is used to weld nylon plates to nylon tubes with carbon black. For the laser to refract, an angle was machined into the laser transparent nylon plates adjacent to the weld interface. Effect of different laser properties such as laser speed, number of laser rotations and laser power were studied on the quality of welding in terms of better finish and strength. The strength of these welds was assessed using a new tensile test fixture. Subsequently, the weld seam width was found from the tensile tested samples by analyzing the weld interface using vernier and transmission light microscopy. These tensile test results were then normalized using the weld seam area to obtain the tensile stress. The results showed the samples could withstand more tensile stress with an increase in laser power and rotation, excluding the samples which had decomposition due to excessive laser power. Also, the material property changes at the weld interface due to laser welding were characterized using a nanoindenter, for which small square samples were carved out of the weld interface and cold mounted. The results show that the modulus and hardness of nylon decreases right at the interface of the weld. In order to find the reason why there is a decline in the above mentioned mechanical properties, differential scanning calorimetry (DSC) testing was done to find possible changes in crystallinity, as decreasing modulus in semi-crystalline polymers is usually a result of decreasing

  7. Joining characteristics of orthodontic wires with laser welding.

    Science.gov (United States)

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

    2008-01-01

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

  8. The influence of shielding gas in hybrid LASER MIG welding

    Science.gov (United States)

    Tani, Giovanni; Campana, Giampaolo; Fortunato, Alessandro; Ascari, Alessandro

    2007-07-01

    Hybrid LASER-GMAW welding technique has been recently studied and developed in order to meet the needs of modern welding industries. The two sources involved in this process play, in fact, a complementary role: fast welding speed, deep bead penetration and high energy concentration can be achieved through the LASER beam, while gap bridgeability and cost-effectiveness are typical of the GMAW process. Particularly interesting, in this context, is the CO 2 LASER-MIG welding which differs from the Nd:YAG LASER-MIG technique for the high powers that can be exploited and for the good power/cost ratio of the process. This paper is a part of a wide study on the hybrid CO 2 LASER-MIG welding and investigates the influence of the shielding gas both on the stability of the process and on the dimensional characteristics of the weld bead. Two different parameters have been taken into consideration in order to develop this analysis: the shielding gas composition and the shielding gas flow. The experiment, performed on AISI 304 stainless steel plates, has been planned exploiting design of experiment techniques. The results have been analyzed through a statistical approach in order to determine the real influence of each parameter on the overall process.

  9. A study of electron beam welding of Mo based TZM alloy

    International Nuclear Information System (INIS)

    Chakraborty, S.P.; Krishnamurthy, N.

    2013-12-01

    Mo based TZM alloy is one of the most promising refractory alloy having several unique high temperature properties suitable for structural applications in the new generation advanced nuclear reactors. However, this alloy easily picks up interstitial impurities such as N 2 , H 2 and C from air during welding due to its reactive nature. High melting point of TZM alloy also restricts use of conventional welding technique for welding. Hence, Electron beam welding (EBW) technique with its deep penetration power to produce narrow heat affected zones under high vacuum was employed to overcome the above welding constraints by conducting a systematic study using both processes of bead on plate and butt joint configuration. Uniform and defect free weld joints were produced. Weld joints were subjected to optical characterization, chemical homogeneity analysis and microhardness profile study across the width of welds. Improved grain structure with equiaxed grains was obtained in the weld zone as compared to fibrous base structure. Original chemical composition was retained in the weld zone. The detailed results are described in this report. (author)

  10. A fundamental study on the structural integrity of magnesium alloys joined by friction stir welding

    Science.gov (United States)

    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

  11. Investigation of the structure and properties of a composite insert applied at laser welding of steel with titanium

    Science.gov (United States)

    Pugacheva, N. B.; Cherepanov, A. N.; Orishich, A. M.; Malikov, A. G.; Drozdov, V. O.; Mali, V. I.; Senaeva, E. I.

    2017-10-01

    Production of welded bimetallic structures of titanium and steel using a laser beam is a very urgent and important task in the shipbuilding, airspace and power engineering. Laser welding using an intermediate insert is one of the ways to solve this problem. In this paper, we present the results of experimental studies of formation of the structure and properties of composite insert, obtained by explosion welding, after its application at laser welding steel with titanium. A study of a four-layer composite insert obtained by explosion welding showed that it has no brittle intermetallic phases and defects in the form of cracks and pores. The boundaries between the plates to be welded in the composite insert have a characteristic wavy structure with narrow zones of mutual diffusion penetration of elements of the adjacent metals. It is established that the strength of the composite insert is comparable with the maximum strength of Grade 4 alloy, and the destruction of the product during the tensile tests in most cases occurred along the weakest component of the composite insert, i.e. the copper layer, whose strength was significantly increased due to the hardening that took place in the explosion welding.

  12. Effect of Post Weld Heat Treatment on Corrosion Behavior of AA2014 Aluminum – Copper Alloy Electron Beam Welds

    Science.gov (United States)

    Venkata Ramana, V. S. N.; Mohammed, Raffi; Madhusudhan Reddy, G.; Srinivasa Rao, K.

    2018-03-01

    The present work pertains to the study of corrosion behavior of aluminum alloy electron beam welds. The aluminium alloy used in the present study is copper containing AA2014 alloy. Electron Beam Welding (EBW) was used to weld the alloys in annealed (O) condition. Microstructural changes across the welds were recorded and the effect of post weld heat treatment (PWHT) in T4 (Solutionized and naturally aged) condition on pitting corrosion resistance was studied. A software based PAR basic electrochemical system was used for potentio-dynamic polarization tests. From the study it is observed that weld in O condition is prone to more liquation than that of PWHT condition. This may be attributed to re-melting and solidification of excess eutectic present in the O condition of the base metal. It was also observed that slightly higher hardness values are recorded in O condition than that of PWHT condition. The pitting corrosion resistance of the PMZ/HAZ in PWHT condition is better than that of O condition. This is attributed to copper segregation at the grain boundaries of PMZ in O condition.

  13. An efficient method of spot welding Aluminium alloys with induction preheating

    Directory of Open Access Journals (Sweden)

    Jawad Saleem

    2016-12-01

    Full Text Available Steel has been the material of choice for automobile manufacturers. In the recent years material such as aluminium and its alloys are taking over the market because of their light weight. The use of aluminium, in automobile manufacturing can result in overall fuel efficiency. Spot welding aluminium alloys require higher electric power and less welding time as compared to steel. Welding guns that can produce an electric current which is approximately 2 to 3 times higher, as compared to steel are required for spot welding aluminium. An efficient method of spot welding Aluminium alloys with the preheating process has been proposed in this paper. Preheating Aluminium sheet before spot welding reduces the thermal and electrical resistance which brings down the electric current requirement to spot weld Aluminium structures. Both spot welding and induction preheating process have been modelled in this paper. The test results of the preheating process have also been verified with practical heating trials. The preheating is performed on-the-fly in advance to spot welding process. The results show that spot welding Al 6082 after preheating up to 200 oC, the output current requirements to make the spot weld are reduced by 22%.

  14. Experimental Evaluation and Characterization of Electron Beam Welding of 2219 AL-Alloy

    Directory of Open Access Journals (Sweden)

    Mohamed Sobih

    2016-01-01

    Full Text Available Aiming to reduce the weight of components, thus allowing a profit in terms of energy saving, automotive industry as well as aircraft industry extensively uses aluminum alloys. The most widely used joining technology in aircraft industry is riveting, while welding seems to be used in the car industry in the case of aluminum alloys. However, welding technology is characterized by many defects, such as gas porosity; oxide inclusions; solidification cracking (hot tearing; and reduced strength in both the weld and the heat affected zones which could limit its development. Many techniques are used for aluminum alloys welding, among them is electron beam welding (EBW, which has unique advantages over other traditional fusion welding methods due to high-energy density, deep penetration, large depth-to-width ratio, and small heat affected zone. The welding parameters that yield to optimal weld joint have been previously obtained. These optimal parameters were validated by welding a specimen using these parameters. To evaluate this optimal weld joint, complete, microstructural observations and characterization have been carried out using scanning electron microscopy, optical microscopy, and energy dispersive X-ray analysis. This evaluation leads to description and quantification of the solidification process within this weld joint.

  15. Effect of Local Post Weld Heat Treatment on Tensile Properties in Friction Stir Welded 2219-O Al Alloy

    Science.gov (United States)

    Chu, Guannan; Sun, Lei; Lin, Caiyuan; Lin, Yanli

    2017-11-01

    To improve the formability of the aluminum alloy welds and overcome the size limitation of the bulk post weld heat treatment (BPWHT) on large size friction stir welded joints, a local post weld heat treatment method (LPWHT) was proposed. In this method, the resistance heating as the moving heat source is adopted to only heat the weld seam. The temperature field of LPWHT and its influence on the mechanical properties and formability of FSW 2219-O Al alloy joints was investigated. The evaluation of the tensile properties of FSW samples was also examined by mapping the global and local strain distribution using the digital image correlation methodology. The results indicated that the formability was improved greatly after LPWHT, while the hardness distribution of the FSW joint was homogenized. The maximum elongation can reach 1.4 times that of as-welded joints with increase the strength and the strain of the nugget zone increased from 3 to 8% when annealing at 300 °C. The heterogeneity on the tensile deformation of the as-welded joints was improved by the nugget zone showing large local strain value and the reason was given according to the dimple fracture characteristics at different annealing temperatures. The tensile strength and elongation of LPWHT can reach 93.3 and 96.1% of the BPWHT, respectively. Thus, the LPWHT can be advantageous compared to the BPWHT for large size welds.

  16. Corrosion behavior of friction stir welded AZ31B Mg alloy - Al6063 alloy joint

    Directory of Open Access Journals (Sweden)

    B. Ratna Sunil

    2016-12-01

    Full Text Available In the present work, AZ31B Mg alloy and Al6063 alloy-rolled sheets were successfully joined by friction stir welding. Microstructural studies revealed a sound joint with good mechanical mixing of both the alloys at the nugget zone. Corrosion performance of the joint was assessed by immersing in 3.5% NaCl solution for different intervals of time and the corrosion rate was calculated. The joint has undergone severe corrosion attack compared with both the base materials (AZ31B and Al6063 alloys. The predominant corrosion mechanism behind the high corrosion rate of the joint was found to be high galvanic corrosion. From the results, it can be suggested that the severe corrosion of dissimilar Mg–Al joints must be considered as a valid input while designing structures intended to work in corroding environment.

  17. Laser power coupling efficiency in conduction and keyhole welding ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Materials. Park, OH: Am. Soc. Metals). Vitek J M, David S A 1983 Metall. Trans. A14: 1833–1843. Xie J, Kar A 1997 Laser welding of cold-rolled steel sheets. Proc. Laser Mater. Process. Conf.,. ICALEO 97 (eds.) R Fabbro, A Kar, A Matsunawa (Orlando, ...

  18. Comparative studies on ultrasonic, friction, laser and resistance pressure welding of NiTi shape memory alloys with high-alloy steels. Final report; Vergleichende Untersuchungen zum Ultraschall-, Reib-, Laserstrahl- und Widerstandspressschweissen von NiTi-Shape-Memory-Metall mit hochlegierten Staehlen. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Zuckschwerdt, K.

    2000-04-01

    The suitability of different welding techniques for welding of NiTi shape memory alloys with high-alloy steel (C12CrNi17-7, X5CrNiNb19-9, X20Cr13) was investigated. The quality of the welds was analyzed using mechanical-technological, fractographic, metallographic and electron microscopy analysis. [German] Ziel dieses Forschungsvorhabens ist es, die Eignung der einzelnen Schweissverfahren fuer das Fuegen von NiTi-Formgedaechtnislegierungen mit hochlegiertem Stahl (X12CrNi17-7, X5CrNiNb19-9, X20Cr13) darzustellen und zu beurteilen. Die Qualitaet der Fuegeverbindungen wird mit Hilfe mechanisch-technologischer, fraktographischer, metallographischer und elektronenmikroskopischer Untersuchungen bewertet.

  19. A higher chromium weld overlay alloy for waterwalls and superheaters

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Larry; Clark, Gregg [ThyssenKrupp VDM USA, Inc., Tipton, IN (United States)

    2009-08-15

    The use of corrosion resistant weld overlay materials has proven to be a very effective method to extend the life of boiler tubes in coal-fired boilers. In order to properly select the best material as a weld overlay, the demands placed upon the material need to be understood. The required material properties for a weld overlay can change with boiler design (such as once-through versus drum boilers), tube function (evaporator versus superheater tubes), and for various regions within the boiler (such as elevation or proximity to over-fire air ports). Material properties that need to be considered include the physical, mechanical, and corrosion properties, as well as the cost and ease of fabrication. The score card in some of these areas has been less than desired for certain weld overlay materials. Nonetheless, there are usually multiple material choices that will work in most cases. When multiple choices are available, asset owners will generally select the material with the most experience. Since its introduction in 2003, Alloy 33 has continued to gain positive experience as a weld overlay in coal-fired boilers and is therefore gaining acceptance within the industry. In the furnace region where combustion occurs, the waterwall tubes are exposed to high heat inputs along with corrosive combustion gases and deposits. These conditions can cause rapid corrosion by a mixed sulfidation/oxidation mechanism. The corrosion rates increase further if low NOx combustion practices are used, since this causes a reducing atmosphere that forms more corrosive sulfur species such as H{sub 2}S gases and FeS deposits. The corrosion rates increase with tube metal temperatures, which are controlled by the local tube pressure as well as the operating practices (i.e. heat flux rates). In the highest pressure units that operate above the water triple point (supercritical plants) cracking can sometimes also be an issue. This cracking is caused by a corrosion fatigue mechanism and is

  20. Rotary Friction Welding of Weight Heavy Alloy with Wrought AlMg3 Alloy for Subcaliber Ammunition

    Directory of Open Access Journals (Sweden)

    Olgierd Janusz Goroch

    2017-12-01

    Full Text Available The results of studies concerning friction welding of Weight Heavy Alloy (WHA with AlMg3 alloy are presented. The friction welding of density 17,5 Mg/m3 with aluminum alloy showed that it is possible to reach the joints with the strength exceeding the yield strength of wrought AlMg3 alloy. This strength looks to be promising from point of view of condition which have to be fulfilled in case of armor subcaliber ammunition, where WHA rods play the role Kinetic Energy Penetrators and aluminum is used for projectile ballistic cup.

  1. Corrosion behaviour of laser-cleaned AA7024 aluminium alloy

    Science.gov (United States)

    Zhang, F. D.; Liu, H.; Suebka, C.; Liu, Y. X.; Liu, Z.; Guo, W.; Cheng, Y. M.; Zhang, S. L.; Li, L.

    2018-03-01

    Laser cleaning has been considered as a promising technique for the preparation of aluminium alloy surfaces prior to joining and welding and has been practically used in the automotive industry. The process is based on laser ablation to remove surface contaminations and aluminium oxides. However the change of surface chemistry and oxide status may affect corrosion behaviour of aluminium alloys. Until now, no work has been reported on the corrosion characteristics of laser cleaned metallic surfaces. In this study, we investigated the corrosion behaviour of laser-cleaned AA7024-T4 aluminium alloy using potentiodynamic polarisation, electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET). The results showed that the laser-cleaned surface exhibited higher corrosion resistance in 3.5 wt.% NaCl solution than as-received hot-rolled alloy, with significant increase in impedance and decrease in capacitance, while SVET revealed that the active anodic points appeared on the as-received surface were not presented on the laser-cleaned surfaces. Such corrosion behaviours were correlated to the change of surface oxide status measured by glow discharge optical emission spectrometry (GDOES) and X-ray photoelectron spectroscopy (XPS). It was suggested that the removal of the original less protective oxide layer consisting of MgO and MgAl2O4 on the as-received surfaces and the newly formed more protective oxide layer containing mainly Al2O3 and MgO by laser cleaning were responsible for the improvement of the corrosion performance.

  2. Evaluation of the AISI 904L Alloy Weld Overlays Obtained by GMAW and Electro-Slag Welding Processes

    Science.gov (United States)

    Jorge, Jorge C. F.; Meira, O. G.; Madalena, F. C. A.; de Souza, L. F. G.; Araujo, L. S.; Mendes, M. C.

    2017-05-01

    The use of superaustenitic stainless steels (SASS) as an overlay replacement for nickel-based alloys can be an interesting alternative for the oil and gas industries, due to its lower cost, when compared to superalloys. Usually, the deposition is made with several welding passes by using conventional arc welding processes, such as gas tungsten arc welding (GTAW) or gas metal arc welding (GMAW) processes. In this respect, electro-slag welding (ESW), which promotes high heat inputs and low dilution of the welds, can also be attractive for this application, as it provides a higher productivity, once only one layer is needed for the deposition of the minimum thickness required. The present work evaluates the behavior of an AISI 904L SASS weld overlay deposited on a carbon steel ASTM A516 Grade 70 by ESW and GMAW processes. Both as-welded and heat-treated conditions were evaluated and compared. A multipass welding by GMAW process with three layers and 48 passes was performed on 12.5 × 200 × 250 mm steel plates with average welding energy of 1.0 kJ/mm. For ESW process, only one layer was deposited on 50 × 400 × 400 mm steel plates with average welding energy of 11.7 kJ/mm. After welding, a post-weld heat treatment (PWHT) at 620 °C for 10 h was performed in half of the steel plate, in order to allow the comparison between this condition and the as-welded one. For both processes, the austenitic microstructure of the weld deposits was characterized by optical microscopy and scanning electron microscopy with electron backscatter diffraction. A low proportion of secondary phases were observed in all conditions, and the PWHT did not promote significant changes on the hardness profile. Martensite for GMAW process and bainite for ESW process were the microstructural constituents observed at the coarse grain heat-affected zone, due to the different cooling rates. For ESW process, no evidences of partially diluted zones were found. As a consequence of the microstructural

  3. Fracture Behaviour of Nickel-Titanium Laser Welded Joints

    Science.gov (United States)

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

    2009-08-01

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

  4. Laser surface alloying on aluminum and its alloys: A review

    Science.gov (United States)

    Chi, Yiming; Gu, Guochao; Yu, Huijun; Chen, Chuanzhong

    2018-01-01

    Aluminum and its alloys have been widely used in aerospace, automotive and transportation industries owing to their excellent properties such as high specific strength, good ductility and light weight. Surface modification is of crucial importance to the surface properties of aluminum and its alloys since high coefficient of friction, wear characteristics and low hardness have limited their long term performance. Laser surface alloying is one of the most effective methods of producing proper microstructure by means of non-equilibrium solidification which results from rapid heating and cooling. In this paper, the influence of different processing parameters, such as laser power and scanning velocity is discussed. The developments of various material systems including ceramics, metals or alloys, and metal matrix composites (MMCs) are reviewed. The microstructure, hardness, wear properties and other behaviors of laser treated layer are analyzed. Besides, the existing problems during laser surface treatment and the corresponding solutions are elucidated and the future developments are predicted.

  5. The use of electromagnetic body forces to enhance the quality of laser welds

    Science.gov (United States)

    Ambrosy, Guenter; Berger, P.; Huegel, H.; Lindenau, D.

    2003-11-01

    The use of electromagnetic body forces in laser beam welding of aluminum alloys is a new method to shape the geometry and to enhance the quality of the weld seams. In this new approach, electromagnetic volume forces are utilized by applying magnetic fields and electric currents of various origins. Acting in the liquid metal, they directly affect the flow field and can lead to favourable conditions for the melt dynamics and energy coupling. Numerous welds with full and partial penetration using both CO2 and Nd:YAG lasers demonstrate that this method directly influences the seam geometry and top-bead topography as well as the penetration depth and the evolution of pores and cracks. In the case of full penetration, it is also possible to lift or to lower the weld pool. The method, therefore, can be used to shape the geometry and to enhance the quality of the weld seam. Depending on the orientation of an external magnetic field, significant impacts are achieved in CO2 welding, even without an external current: the shape of the cross-sectional area can be increased of up to 50% and also the seam width is changed. Whereas for such conditions with Nd:YAG lasers no significant effect could be observed, it turned out that, when an external electric current is applied, similar effects are present with both wavelengths. In further investigations, the effect of electromagnetic body forces resulting from the interaction of an external current and its self-induced magnetic field was studied. Hereby, the current was fed into the workpiece via a tungsten electrode or a filler wire. The resulting phenomena are the same independent from wavelength and means of current feed.

  6. Ultrasonic Spot Welding of a Rare-Earth Containing ZEK100 Magnesium Alloy: Effect of Welding Energy

    Science.gov (United States)

    Macwan, A.; Chen, D. L.

    2016-04-01

    Ultrasonic spot welding was used to join a low rare-earth containing ZEK100 Mg alloy at different levels of welding energy, and tensile lap shear tests were conducted to evaluate the failure strength in relation to the microstructural changes. It was observed that dynamic recrystallization occurred in the nugget zone; the grain size increased and microhardness decreased with increasing welding energy arising from the increasing interface temperature and strain rate. The weld interface experienced severe plastic deformation at a high strain rate from ~500 to ~2100 s-1 with increasing welding energy from 500 to 2000 J. A relationship between grain size and Zener-Hollomon parameter, and a Hall-Petch-type relationship between microhardness and grain size were established. The tensile lap shear strength and failure energy were observed to first increase with increasing welding energy, reach the maximum values at 1500 J, and then decrease with a further increase in the welding energy. The samples welded at a welding energy ≤1500 J exhibited an interfacial failure mode, while nugget pull-out occurred in the samples welded at a welding energy above 1500 J. The fracture surfaces showed typical shear failure. Low-temperature tests at 233 K (-40 °C) showed no significant effect on the strength and failure mode of joints welded at the optimal welding energy of 1500 J. Elevated temperature tests at 453 K (180 °C) revealed a lower failure load but a higher failure energy due to the increased deformability, and showed a mixed mode of partial interfacial failure and partial nugget pull-out.

  7. Systematic investigation of the fatigue performance of a friction stir welded low alloy steel

    International Nuclear Information System (INIS)

    Toumpis, Athanasios; Galloway, Alexander; Molter, Lars; Polezhayeva, Helena

    2015-01-01

    Highlights: • The fatigue behaviour of a friction stir welded low alloy steel has been assessed. • The welds’ fatigue lives outperform the International Institute of Welding’s recommendations for fusion welds. • The slow weld exhibits the best fatigue performance of the investigated welds. • Fracture surface analysis shows that minor embedded flaws do not offer crack initiation sites. • Process-related surface breaking flaws have a significant effect on the fatigue life. - Abstract: A comprehensive fatigue performance assessment of friction stir welded DH36 steel has been undertaken to address the relevant knowledge gap for this process on low alloy steel. A detailed set of experimental procedures specific to friction stir welding has been put forward, and the consequent study extensively examined the weld microstructure and hardness in support of the tensile and fatigue testing. The effect of varying welding parameters was also investigated. Microstructural observations have been correlated to the weldments’ fatigue behaviour. The typical fatigue performance of friction stir welded steel plates has been established, exhibiting fatigue lives well above the weld detail class of the International Institute of Welding even for tests at 90% of yield strength, irrespective of minor instances of surface breaking flaws which have been identified. An understanding of the manner in which these flaws impact on the fatigue performance has been established, concluding that surface breaking irregularities such as these produced by the tool shoulder’s features on the weld top surface can be the dominant factor for crack initiation under fatigue loading

  8. Modal testing and finite element model updating of laser spot welds

    Energy Technology Data Exchange (ETDEWEB)

    Husain, N Abu; Khodaparast, H Haddad; Snaylam, A; James, S; Sharp, M; Dearden, G; Ouyang, H, E-mail: h.ouyang@liverpool.ac.u [Department of Engineering, Harrison Hughes Building, University of Liverpool, L69 3GH (United Kingdom)

    2009-08-01

    Spot welds are used extensively in automotive engineering. One of the latest manufacturing techniques for producing spot welds is Laser Welding. Finite element (FE) modelling of laser welds for dynamic analysis is a research issue because of the complexity and uncertainty of the welds and thus formed structures. In this work, FE model of the welds is developed by employing CWELD element in NASTRAN and its feasibility for representing laser spot welds is investigated. The FE model is updated based on the measured modal data of hat-plate structures and cast as a structural minimisation problem by the application of NASTRAN codes.

  9. Stress-induced birefringence control in femtosecond laser glass welding

    Science.gov (United States)

    Gstalter, M.; Chabrol, G.; Bahouka, A.; Serreau, L.; Heitz, J.-L.; Taupier, G.; Dorkenoo, K.-D.; Rehspringer, J.-L.; Lecler, S.

    2017-11-01

    Glass welding by femtosecond laser pulses causes microscopic structural modifications, affecting the refractive index due to residual stress. Locally induced birefringence is studied by photoelasticimetry using a polarized light microscope. The study is performed on borosilicate thin glass plates using an industrial femtosecond laser generating 300 fs pulses at 500 kHz, with a 100 mm focusing length F-theta lens allowing fast welding. For low-energy deposition, the principal birefringence axes are determined to be homogenous along the seam and perpendicular and parallel to the laser scanning direction. Tensile stress is induced in the laser scanning direction by the welding seams. The induced birefringence is determined to be equivalent for in-volume irradiated track and welding seams. An inhomogeneity of the birefringence within the seam is observed for the first time at high-energy deposition. The distribution of the birefringence can be controlled with the laser scanning patterns. The amount of residual stress is measured by compensating the local birefringence. The birefringence Δ n is estimated at 2.4 × 10^{-4}, corresponding to a residual stress amount around 59 MPa. The influence of the welding geometry is also illustrated.

  10. Upgrading weld quality of a friction stir welded aluminum alloys AMG6

    Science.gov (United States)

    Chernykh, I. K.; Vasil'ev, E. V.; Matuzko, E. N.; Krivonos, E. V.

    2018-01-01

    In the course of introduction of FSW technology into the industry there is a keen interest in this process; there are issues such as how does joining take place, what is the structure of the joint, and where there are dangerous zones. The objective of this research is to obtain information about the structure of the joint, what are the temperatures that arise during the joining, what strength is apply to the tool when joining the material, what tensile strength of joint, and where fracture tended to occur. Specimens were produced at different modes of welding at a tool rotation speed of 315 to 625 rpm and tool travel speed of 40 to 125 mm/min. During the experiment, the strength applied to the tool was measured, which reached 800016000 N (Fz) and 400-1400 N (Fx) and the temperature on the surface of the tool, which is in the range 250-400°C. Before the welding process the tool was heated to a temperature in the range of 100-250 degrees, but the tensile strength is not had a tangible impact. The tensile strength is about 80 % of that of the aluminum alloy base metal tensile strength, and fracture tended is occur not at the line of joint but follow the shape of the tool. In the transverse cross section of a FSW material there is a microstructural regions such as weld nugget, thermomechanically affected zone and heat-affected zone with parent material.

  11. Elucidation of high-power fibre laser welding phenomena of stainless steel and effect of factors on weld geometry

    International Nuclear Information System (INIS)

    Kawahito, Yousuke; Mizutani, Masami; Katayama, Seiji

    2007-01-01

    The fibre laser has been receiving great attention due to its advantages of high efficiency, high power and high beam quality, and is expected to be one of the most desirable heat sources for high-speed and deep-penetration welding. In this study, therefore, in bead-on-plate welding of Type 304 stainless steel plates with 6 kW fibre laser, the effects of laser power, power density and welding speed on the formation of sound welds were investigated with four laser beams of 130, 200, 360 and 560 μm in spot diameter, and their welding phenomena were clarified with high-speed video cameras and an x-ray transmission real-time imaging system. The weld beads showed a keyhole type of penetration at any diameter, and the maximum penetration of 11 mm in depth was obtained at 130 μm spot diameter and 0.6 m min -1 welding speed. It was found that the laser power density exerted a remarkable effect on the increase in weld penetration at higher welding speeds, and sound partially penetrated welds without welding defects such as porosity, underfilling or humping could be produced at wide process windows of welding speeds between 4.5 and 10 m min -1 with fibre laser beams of 360 μm or 560 μm in spot diameter. The high-speed video observation pictures and the x-ray images of the welding phenomena at 6 m min -1 welding speed and 360 μm spot diameter show that a sound weld bead was formed owing to a long molten pool suppressing and accommodating spattering and a stable keyhole generating no bubbles from the tip, respectively

  12. Damage Tolerance Assessment of Friction Pull Plug Welds in an Aluminum Alloy

    Science.gov (United States)

    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.

  13. Influence of shielding gas pressure on welding characteristics in CO2 laser-MIG hybrid welding process

    Science.gov (United States)

    Chen, Yanbin; Lei, Zhenglong; Li, Liqun; Wu, Lin

    2006-01-01

    The droplet transfer behavior and weld characteristics have been investigated under different pressures of shielding gas in CO2 laser and metal inert/active gas (laser-MIG) hybrid welding process. The experimental results indicate that the inherent droplet transfer frequency and stable welding range of conventional MIG arc are changed due to the interaction between CO2 laser beam and MIG arc in laser-MIG hybrid welding process, and the shielding gas pressure has a crucial effect on welding characteristics. When the pressure of shielding gas is low in comparison with MIG welding, the frequency of droplet transfer decreases, and the droplet transfer becomes unstable in laser-MIG hybrid welding. So the penetration depth decreases, which shows the characteristic of unstable hybrid welding. However, when the pressure of shielding gas increases to a critical value, the hybrid welding characteristic is changed from unstable hybrid welding to stable hybrid welding, and the frequency of droplet transfer and the penetration depth increase significantly.

  14. Optimization of welding parameters of Ti6Al4V alloy using electron beam

    Directory of Open Access Journals (Sweden)

    Petr Havlík

    2016-06-01

    Full Text Available Titanium alloys and their weld joints find wide application, in particular in the aircraft, automotive and chemical industries, because of their outstanding specific strength and corrosion resistance. The high reactivity of these alloys and the strong degradation effect of elements contained in the atmosphere (H, N and O make it necessary for these alloys to be welded in protective atmospheres or in vacuum. From this viewpoint, Electron Beam Welding is an advantageous welding technology, especially in large series production. In the literature, there is sufficient information about the effect of the basic welding parameters, namely accelerating voltage, current and welding speed, on the properties of welded joints. In the paper, the effects of the spot diameter and beam focusing on the penetration depth and the weld shape in the Ti6Al4V alloy are studied. The results obtained are complemented by an analysis of the microstructure and microhardness measurements across the welds.

  15. Corrosion behavior of Al6061 alloy weldment produced by friction stir welding process

    Directory of Open Access Journals (Sweden)

    Farhad Gharavi

    2015-07-01

    Full Text Available In this work, the corrosion behavior of welded lap joints of AA6061-T6 aluminum alloy produced by friction stir welding process has been investigated. Corrosion properties of welded lap joints were studied by cyclic polarization and electrochemical impedance spectroscopy tests. All tests were performed in an aerated 0.6 mol L−1 NaCl aqueous solution with pH = 6.5 at a temperature of 30 °C to characterize corrosion morphology and realize corrosion features of weld regions as opposed to the parent alloy. The microstructure of weld nugget (WN, heated affected zone (HAZ, and parent alloy were analyzed using scanning electron microscopy and energy dispersive spectroscopy. The experimental results indicated that the welding process has a major effect on the corrosion resistance, which possibly associated to the break-down and dissolution of intermetallic particles. It is supposed that an increasing in intermetallic distributed throughout the matrix of weld regions increases the galvanic corrosion couples. Furthermore, by decreasing the grain size in the weld regions, the susceptibility to corrosion is enhanced. The pitting corrosion and intergranular attack are the dominant corrosion types in the weld regions and the parent alloy.

  16. Structure of Ti-6Al-4V nanostructured titanium alloy joint obtained by resistance spot welding

    Science.gov (United States)

    Klimenov, V. A.; Kurgan, K. A.; Chumaevskii, A. V.; Klopotov, A. A.; Gnyusov, S. F.

    2016-01-01

    The structure of weld joints of the titanium alloy Ti-6Al-4V in the initial ultrafine-grained state, obtained by resistance spot welding, is studied using the optical and scanning electron microscopy method and the X-ray structure analysis. The carried out studies show the relationship of the metal structure in the weld zone with main joint zones. The structure in the core zone and the heat affected zone is represented by finely dispersed grains of needle-shaped martensite, differently oriented in these zones. The change in the microhardness in the longitudinal section of the weld joint clearly correlates with structural changes during welding.

  17. Structure of Ti-6Al-4V nanostructured titanium alloy joint obtained by resistance spot welding

    Energy Technology Data Exchange (ETDEWEB)

    Klimenov, V. A., E-mail: klimenov@tpu.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); National Research Tomsk Polytechnic University, 30 Lenin Av., Tomsk, 634050 (Russian Federation); Kurgan, K. A., E-mail: kirill-k2.777@mail.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); Chumaevskii, A. V., E-mail: tch7av@gmail.com [Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Sciences, 2/4 Akademicheskii pr., Tomsk, 634021 (Russian Federation); Klopotov, A. A., E-mail: klopotovaa@tsuab.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); National Research Tomsk State University, 36 Lenin Ave., Tomsk, 634050 (Russian Federation); Gnyusov, S. F., E-mail: gnusov@rambler.ru [National Research Tomsk Polytechnic University, 30 Lenin Av., Tomsk, 634050 (Russian Federation)

    2016-01-15

    The structure of weld joints of the titanium alloy Ti-6Al-4V in the initial ultrafine-grained state, obtained by resistance spot welding, is studied using the optical and scanning electron microscopy method and the X-ray structure analysis. The carried out studies show the relationship of the metal structure in the weld zone with main joint zones. The structure in the core zone and the heat affected zone is represented by finely dispersed grains of needle-shaped martensite, differently oriented in these zones. The change in the microhardness in the longitudinal section of the weld joint clearly correlates with structural changes during welding.

  18. Subminiature eddy-current transducers designed to study welded joints of titanium alloys

    Science.gov (United States)

    Malikov, V. N.; Dmitriev, S. F.; Katasonov, A. O.; Sagalakov, A. M.; Ishkov, A. V.

    2017-12-01

    Eddy current transducers (ECT) are used to construct a sensor for investigating titanium sheets connected by a welded joint. The paper provides key technical information about the eddy current transducer used and describes the procedure of measurements that makes it possible to control defects in welded joints of titanium alloys. It is capable of automatically changing the filtering cutoff frequency and operating frequency of the device. Experiments were conducted on welded VT1-0 titanium plates. The paper contains the results of these measurements. The dependence data facilitates the assessment of the quality of the welded joints and helps make an educated conclusion about welding quality.

  19. The high frequency characteristics of laser reflection and visible light during solid state disk laser welding

    International Nuclear Information System (INIS)

    Gao, Xiangdong; You, Deyong; Katayama, Seiji

    2015-01-01

    Optical properties are related to weld quality during laser welding. Visible light radiation generated from optical-induced plasma and laser reflection is considered a key element reflecting weld quality. An in-depth analysis of the high-frequency component of optical signals is conducted. A combination of a photoelectric sensor and an optical filter helped to obtain visible light reflection and laser reflection in the welding process. Two groups of optical signals were sampled at a high sampling rate (250 kHz) using an oscilloscope. Frequencies in the ranges 1–10 kHz and 10–125 kHz were investigated respectively. Experimental results showed that there was an obvious correlation between the high-frequency signal and the laser power, while the high-frequency signal was not sensitive to changes in welding speed. In particular, when the defocus position was changed, only a high frequency of the visible light signal was observed, while the high frequency of the laser reflection signal remained unchanged. The basic correlation between optical features and welding status during the laser welding process is specified, which helps to provide a new research focus for investigating the stability of welding status. (letter)

  20. Seam gap bridging of laser based processes for the welding of aluminium sheets for industrial applications

    NARCIS (Netherlands)

    Aalderink, B.J.; Aalderink, Benno; Pathiraj, B.; Aarts, Ronald G.K.M.

    2010-01-01

    Laser welding has a large potential for the production of tailor welded blanks in the automotive industry, due to the low heat input and deep penetration. However, due to the small laser spot and melt pool, laser-based welding processes in general have a low tolerance for seam gaps. In this paper,

  1. Effect of Nd:YAG laser parameters on the penetration depth of a representative Ni-Cr dental casting alloy.

    Science.gov (United States)

    Al Jabbari, Youssef S; Koutsoukis, Theodoros; Barmpagadaki, Xanthoula; El-Danaf, Ehab A; Fournelle, Raymond A; Zinelis, Spiros

    2015-02-01

    The effects of voltage and laser beam (spot) diameter on the penetration depth during laser beam welding in a representative nickel-chromium (Ni-Cr) dental alloy were the subject of this study. The cast alloy specimens were butted against each other and laser welded at their interface using various voltages (160-390 V) and spot diameters (0.2-1.8 mm) and a constant pulse duration of 10 ms. After welding, the laser beam penetration depths in the alloy were measured. The results were plotted and were statistically analyzed with a two-way ANOVA, employing voltage and spot diameter as the discriminating variables and using Holm-Sidak post hoc method (a = 0.05). The maximum penetration depth was 4.7 mm. The penetration depth increased as the spot diameter decreased at a fixed voltage and increased as the voltage increased at a fixed spot diameter. Varying the parameters of voltage and laser spot diameter significantly affected the depth of penetration of the dental cast Ni-Cr alloy. The penetration depth of laser-welded Ni-Cr dental alloys can be accurately adjusted based on the aforementioned results, leading to successfully joined/repaired dental restorations, saving manufacturing time, reducing final cost, and enhancing the longevity of dental prostheses.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-10-25

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

  3. Mechanical properties and microstructures of the welded union of steel micro-alloyed to niobium

    International Nuclear Information System (INIS)

    Bejar-Gomez, L; Medina-Flores, A; Bedolla-Jacuinde, A; Alfonso, I; Saavedra, M

    2006-01-01

    Experimental structural steel was used for this work, produced by welding and thermo-mechanical treatment, micro-alloyed with niobium and developed for structural applications. Its carbon content was 0.06 and niobium 0.03 weight %. This material was welded by electrical arc and manually by coated electrode, since it is a widely used application. The chemical composition of the steel, its resistance, the selection of the supporting material, and the position of the welding were taken into consideration. The welded union includes all the parts involved with the welding such as the welding metal or support, the thermally affected zone and the base material with no affects. The metallurgy for each part is associated with the type of material, with the welding process applied and with its procedure. This work analyzes the mechanical properties of the welded union of a steel micro-alloyed with niobium, and also studies the microstructure of the union in the sediment metal, in the thermally affected zone and in the base material. The importance of this work lies in establishing the facility or difficulty of an experimental steel micro-alloyed with niobium, containing 0.06% carbon, to avoid outlining or cracking in the welded union. Another basic aspect was to valuate the mechanical properties of the base metal and of the sediment, reinforcing the study with an analysis of the hardness profiles and of the microstructures found in the parts of the welded union (CW)

  4. Study of post-weld heat treatment cracking of Nickel base super alloy (Udimet 520) in gas tungsten arc welding method

    International Nuclear Information System (INIS)

    Kokabi, A. H.; Nematzadeh, F.

    2003-01-01

    In this paper, the mechanism and the cause and the ways for eliminating the decrease of post-weld heat treatment cracking in welding of Nickel base super alloy (Udimet 520) in gas tungsten arc welding method has been studied. For this study, X-ray diffraction machine and quantometery has been used. Increasing of Al, Ti percentage and residual stress are the main causes of cracking post-weld heat treatment. The results from quantometery tests demonstrate that decreasing tendency to post-weld heat treatment cracking is due to the decrease of Al, Ti percentage of welding. Result of X-ray diffraction tests show the tendency toward increasing of post-weld heat treatment cracking for existing of strenghed residual stresses. Finally, it is illustrated that alloy welding Udimet 520 in Ti G method is not sensitive to post-weld heat treatment cracking

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

    Directory of Open Access Journals (Sweden)

    C. Fornaini

    2012-01-01

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

  6. Microstructure of Friction Stir Welded AlSi9Mg Cast with 5083 and 2017A Wrought Aluminum Alloys

    Science.gov (United States)

    Hamilton, C.; Kopyściański, M.; Dymek, S.; Węglowska, A.; Pietras, A.

    2018-03-01

    Wrought aluminum alloys 5083 and 2017A were each joined with cast aluminum alloy AlSi9Mg through friction stir welding in butt weld configurations. For each material system, the wrought and cast alloy positions, i.e., the advancing side or the retreating side, were exchanged between welding trials. The produced weldments were free from cracks and discontinuities. For each alloy configuration, a well-defined nugget comprised of alternating bands of the welded alloys characterized the microstructure. The degree of mixing, however, strongly depended on which wrought alloy was present and on its position during processing. In all cases, the cast AlSi9Mg alloy dominated the weld center regardless of its position during welding. Electron backscattered diffraction analysis showed that the grain size in both alloys (bands) constituting the nugget was similar and that the majority of grain boundaries exhibited a high angle character (20°-60°). Regardless of the alloy, however, all grains were elongated along the direction of the material plastic flow during welding. A numerical simulation of the joining process visualized the material flow patterns and temperature distribution and helped to rationalize the microstructural observations. The hardness profiles across the weld reflected the microstructure formed during welding and correlated well with the temperature changes predicted by the numerical model. Tensile specimens consistently fractured in the cast alloy near the weld nugget.

  7. Studies on Mechanical Alloying of Copper-Tungsten Carbide Composite for Spot Welding Electrode

    Science.gov (United States)

    Zuhailawati, H.; Jamaludin, S. B.

    2009-12-01

    This article presents a study on the properties and performance of copper-based composite reinforced with recycled tungsten carbide powder as spot welding electrode. The copper-tungsten carbide composite electrode was prepared by mechanical alloying and powder forging before being machined into truncated cone-face geometry. The welding operation was conducted on galvanized steel using a pedestal-type spot welding machine. Composites with higher density and electrical conductivity were obtained after mechanical alloying for shorter time. In contrast, a higher hardness is shown in the composite, which was mechanically alloyed to longer time. The strength of the welded steel coupon was found to increase with decreasing milling time due to an increase in density and electrical conductivity. The wear behavior of the composite revealed that the deformation of the spot weld electrode increased with increasing milling time.

  8. Influence of Alloy and Solidification Parameters on Grain Refinement in Aluminum Weld Metal due to Inoculation

    Energy Technology Data Exchange (ETDEWEB)

    Schempp, Philipp [BAM, Germany; Tang, Z. [BIAS, Germany; Cross, Carl E. [Los Alamos National Laboratory; Seefeld, T. [BIAS, Germany; Pittner, A. [BAM, Germany; Rethmeier, M. [BAM, Germany

    2012-06-28

    The goals are: (1) Establish how much Ti/B grain refiner is need to completely refine aluminum weld metal for different alloys and different welding conditions; (2) Characterize how alloy composition and solidification parameters affect weld metal grain refinement; and (3) Apply relevant theory to understand observed behavior. Conclusions are: (1) additions of Ti/B grain refiner to weld metal in Alloys 1050, 5083, and 6082 resulted in significant grain refinement; (2) grain refinement was more effective in GTAW than LBW, resulting in finer grains at lower Ti content - reason is limited time available for equiaxed grain growth in LBW (inability to occlude columnar grain growth); (3) welding travel speed did not markedly affect grain size within GTAW and LBW clusters; and (4) application of Hunt CET analysis showed experimental G to be on the order of the critical G{sub CET}; G{sub CET} was consistently higher for GTAW than for LBW.

  9. Study on laser welding of austenitic stainless steel by varying incident angle of pulsed laser beam

    Science.gov (United States)

    Kumar, Nikhil; Mukherjee, Manidipto; Bandyopadhyay, Asish

    2017-09-01

    In the present work, AISI 304 stainless steel sheets are laser welded in butt joint configuration using a robotic control 600 W pulsed Nd:YAG laser system. The objective of the work is of twofold. Firstly, the study aims to find out the effect of incident angle on the weld pool geometry, microstructure and tensile property of the welded joints. Secondly, a set of experiments are conducted, according to response surface design, to investigate the effects of process parameters, namely, incident angle of laser beam, laser power and welding speed, on ultimate tensile strength by developing a second order polynomial equation. Study with three different incident angle of laser beam 89.7 deg, 85.5 deg and 83 deg has been presented in this work. It is observed that the weld pool geometry has been significantly altered with the deviation in incident angle. The weld pool shape at the top surface has been altered from semispherical or nearly spherical shape to tear drop shape with decrease in incident angle. Simultaneously, planer, fine columnar dendritic and coarse columnar dendritic structures have been observed at 89.7 deg, 85.5 deg and 83 deg incident angle respectively. Weld metals with 85.5 deg incident angle has higher fraction of carbide and δ-ferrite precipitation in the austenitic matrix compared to other weld conditions. Hence, weld metal of 85.5 deg incident angle achieved higher micro-hardness of ∼280 HV and tensile strength of 579.26 MPa followed by 89.7 deg and 83 deg incident angle welds. Furthermore, the predicted maximum value of ultimate tensile strength of 580.50 MPa has been achieved for 85.95 deg incident angle using the developed equation where other two optimum parameter settings have been obtained as laser power of 455.52 W and welding speed of 4.95 mm/s. This observation has been satisfactorily validated by three confirmatory tests.

  10. Effect of tool rotational speed and penetration depth on dissimilar aluminum alloys friction stir spot welds

    Directory of Open Access Journals (Sweden)

    Joaquín M. Piccini

    2017-03-01

    Full Text Available In the last years, the automotive industry is looking for the use of aluminum parts in replace of steel parts in order to reduce the vehicles weight. These parts have to be joined, for instance, by welding processes. The more common welding process in the automotive industry is the Resistance Spot Welding (RSW technique. However, RSW of aluminum alloys has many disadvantages. Regarding this situation, a variant of the Friction Stir Welding process called Friction Stir Spot Welding (FSSW has been developed, showing a strong impact in welding of aluminum alloys and dissimilar materials in thin sheets. Process parameters affect the characteristics of the welded joints. However, the information available on this topic is scarce, particularly for dissimilar joints and thin sheets. The aim of this work was to study the effect of the rotational speed and the tool penetration depth on the characteristics of dissimilar FSS welded joints. Defects free joints have been achieved with higher mechanical properties than the ones reported. The maximum fracture load was 5800 N. It was observed that the effective joint length of the welded spots increased with the tool penetration depth, meanwhile the fracture load increased and then decreased. Finally, welding at 1200 RPM produced welded joints with lower mechanical properties than the ones achieved at 680 and 903 RPM.

  11. Influence of Yb:YAG Laser Beam Parameters on Haynes 188 Weld Fusion Zone Microstructure and Mechanical Properties

    Science.gov (United States)

    Graneix, Jérémie; Beguin, Jean-Denis; Alexis, Joël; Masri, Talal

    2017-08-01

    The weldability of 1.2 mm thick Haynes 188 alloy sheets by a disk Yb:YAG laser welding was examined. Butt joints were made, and the influence of parameters such as power, size, and shape of the spot, welding speed, and gas flow has been investigated. Based on an iconographic correlation approach, optimum process parameters were determined. Depending on the distribution of the power density (circular or annular), acceptable welds were obtained. Powers greater than 1700 W, welding speeds higher than 3.8 m mm-1, and spot sizes between 160 and 320 μm were needed in the circular (small fiber) configuration. By comparison, the annular (large fiber) configuration required a power as high as 2500 W, and a welding speed less than 3.8 m min-1. The mechanical properties of the welds depended on their shape and microstructure, which in turn depended on the welding conditions. The content of carbides, the proportion of areas consisting of cellular and dendritic substructures, and the size of these substructures were used to explain the welded joint mechanical properties.

  12. Friction stir welding of dissimilar AA2024 and AA7075 aluminum alloys

    International Nuclear Information System (INIS)

    Khodir, Saad Ahmed; Shibayanagi, Toshiya

    2008-01-01

    The present study focuses on the microstructure and mechanical properties of dissimilar joints of 2024-T3 Al alloy to 7075-T6 Al alloy produced by friction stir welding. Effects of welding speed and fixed location of base metals on microstructures, hardness distributions, and tensile properties of the welded joints were investigated. SEM-EDS analysis revealed that the stir zone contains a mixed structure and onion ring pattern with a periodic change of grain size as well as a heterogeneous distribution of alloying elements. The maximum tensile strength of 423.0 MPa was achieved for the joint produced at welding speed of 1.67 mm/s when 2024 Al alloy was located on the advancing side

  13. Thermal Stir Welding of High Strength and High Temperature Alloys for Aerospace Applications, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The Keystone and MSU team propose to demonstrate the feasibility of solid-state joining high strength and temperature alloys utilizing the Thermal Stir Welding...

  14. Special Features of Induction Annealing of Friction Stir Welded Joints of Medium-Alloy Steels

    Science.gov (United States)

    Priymak, E. Yu.; Stepanchukova, A. V.; Bashirova, E. V.; Fot, A. P.; Firsova, N. V.

    2018-01-01

    Welded joints of medium-alloy steels XJY750 and 40KhN2MA are studied in the initial condition and after different variants of annealing. Special features of the phase transformations occurring in the welded steels are determined. Optimum modes of annealing are recommended for the studied welded joints of drill pipes, which provide a high level of mechanical properties including the case of impact loading.

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

    International Nuclear Information System (INIS)

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

    2008-01-01

    High strength aluminium alloys (Al-Zn-Mg-Cu alloys) have gathered wide acceptance in the fabrication of light weight structures requiring high strength-to weight ratio, such as transportable bridge girders, military vehicles, road tankers and railway transport systems. The preferred welding processes of high strength aluminium alloy are frequently gas tungsten arc welding (GTAW) process and gas metal arc welding (GMAW) process due 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 6 mm thickness have been used as the base material for preparing single pass 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 aluminium 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. Fatigue properties of the welded joints have been evaluated by conducting fatigue test using rotary bending fatigue testing machine. Current pulsing leads to relatively finer and more equi-axed grain structure in gas tungsten arc (GTA) and gas metal arc (GMA) welds. In contrast, conventional continuous current welding resulted in predominantly columnar grain structures. Grain refinement is accompanied by an increase in fatigue life and endurance limit

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

    OpenAIRE

    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...

  17. Comparative evaluation of tungsten inert gas and laser beam ...

    Indian Academy of Sciences (India)

    In this study, the bead-on-plate welds were made on AA5083-H321 alloy plates using both tungsten inert gas (TIG) welding and laser beam (LB) welding processes to study the enhancement of mechanical properties such as weld yield strength and hardness. The low heat input of laser beam welding effectively reduced the ...

  18. Comparative evaluation of tungsten inert gas and laser beam ...

    Indian Academy of Sciences (India)

    Abstract. In this study, the bead-on-plate welds were made on AA5083-H321 alloy plates using both tungsten inert gas (TIG) welding and laser beam (LB) welding pro- cesses to study the enhancement of mechanical properties such as weld yield strength and hardness. The low heat input of laser beam welding effectively ...

  19. Diode Lasers used in Plastic Welding and Selective Laser Soldering - Applications and Products

    Science.gov (United States)

    Reinl, S.

    Aside from conventional welding methods, laser welding of plastics has established itself as a proven bonding method. The component-conserving and clean process offers numerous advantages and enables welding of sensitive assemblies in automotive, electronic, medical, human care, food packaging and consumer electronics markets. Diode lasers are established since years within plastic welding applications. Also, soft soldering using laser radiation is becoming more and more significant in the field of direct diode laser applications. Fast power controllability combined with a contactless temperature measurement to minimize thermal damage make the diode laser an ideal tool for this application. These advantages come in to full effect when soldering of increasingly small parts in temperature sensitive environments is necessary.

  20. Stress corrosion crack initiation of alloy 182 weld metal in primary coolant - Influence of chemical composition

    Energy Technology Data Exchange (ETDEWEB)

    Calonne, O.; Foucault, M.; Steltzlen, F. [AREVA (France); Amzallag, C. [EDF SEPTEN (France)

    2011-07-01

    Nickel-base alloys 182 and 82 have been used extensively for dissimilar metal welds. Typical applications are the J-groove welds of alloy 600 vessel head penetrations, pressurizer penetrations, heater sleeves and bottom mounted instrumented nozzles as well as some safe end butt welds. While the overall performance of these weld metals has been good, during the last decade, an increasing number of cases of stress corrosion cracking of Alloy 182 weld metal have been reported in PWRs. In this context, the role of weld defects has to be examined. Their contribution in the crack initiation mechanism requires laboratory investigations with small scale characterizations. In this study, the influence of both alloy composition and weld defects on PWSCC (Stress Corrosion Cracking in Primary Water) initiation was investigated using U-bend specimens in simulated primary water at 320 C. The main results are the following: -) the chemical compositions of the weld deposits leading to a large propensity to hot cracking are not the most susceptible to PWSCC initiation, -) macroscopically, superficial defects did not evolve during successive exposures. They can be included in large corrosion cracks but their role as 'precursors' is not yet established. (authors)

  1. Mechanical properties of weldings by electron beams on alloy 8090 (CP 271)

    International Nuclear Information System (INIS)

    Le Poac, P.; Nomine, A.M.; Miannay, D.

    1987-06-01

    Weldings by electron beams got on rings in alloy 8090 in the T4 and T6 state are mechanically tested in traction in the original state of welding or after a thermal processing of 12 hours at 210 0 C [fr

  2. Structure and Corrosion Resistance of Welded Joints of Alloy 1151 in Marine Atmosphere

    Science.gov (United States)

    Bakulo, A. V.; Yakushin, B. F.; Puchkov, Yu. A.

    2017-07-01

    The corrosion behavior of joints formed by TIG and IMIG welding from clad sheets of heat-hardenable aluminum alloy 1151 of the Al - Cu - Mg system is studied. The corrosion tests are performed in an aqueous solution of NaCl in a salt-spray chamber. The welded joints are subjected to a metallographic analysis.

  3. Strain hardening and damage in 6xxx series aluminum alloy friction stir welds

    DEFF Research Database (Denmark)

    Simar, Aude; Nielsen, Kim Lau; de Meester, Bruno

    2010-01-01

    A friction stir weld in 6005A-T6 aluminum alloy has been prepared and analyzed by micro-hardness measurements, tensile testing and scanning electron microscopy (SEM). The locations of the various weld zones were determined by micro-hardness indentation measurements. The flow behavior of the vario...

  4. Comparative evaluation of tungsten inert gas and laser beam ...

    Indian Academy of Sciences (India)

    - cluded that LB welding process is more suitable to join AA5083-H321. Keywords. Aluminum alloys; laser beam welding; mechanical properties; vapourization. 1. Introduction. Aluminum and its alloys are widely used in the transportation, ...

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  7. Electron-beam welding of thorium-doped iridium alloy sheets

    International Nuclear Information System (INIS)

    David, S.A.; Liu, C.T.; Hudson, J.D.

    1979-04-01

    Modified iridium alloys containing 100 ppM Th were found to be very susceptible to hot-cracking during gas tungsten-arc and electron-beam welding. However, the electron-beam welding process showed greater promise of success in welding these alloys, in particular Ir--0.3% W doped with 200 ppM Th and 50 ppM Al. The weldability of this particular alloy was extremely sensitive to the welding parameters, such as beam focus condition and welding speed, and the resulting fusion zone structure. At low speed successful electron-beam welds were made over a narrow range of beam focus conditions. However, at high speeds successful welds can be made over an extended range of focus conditions. The fusion zone grain structure is a strong function of welding speed and focus condition, as well. In the welds that showed hot-cracking, a region of positive segregation of thorium was identified at the fusion boundary. This highly thorium-segregated region seems to act as a potential source for the nucleation of a liquation crack, which later grows as a centerline crack

  8. Laser welding parameters for manufacturing iridium-192 (Ir-192) source

    International Nuclear Information System (INIS)

    Anung Pujiyanto; Moch Subechi; Hotman Lubis; Diandono KY

    2013-01-01

    Number of cervical cancer patients in Indonesia is growing every year. One of cervical cancer treatment was fairly effective use brachytherapy treatment with radioisotope sources of iridium-192. Manufacturing of iridium sources for brachytherapy can be done by incorporating the iridium-192 into stainless steel microcapsules then welding using laser welder which the quality of the welding of iridium source (Ir-192) was determined by the welding parameters such as full power, energy frequency, average power and speed. Based on the result of leakage test using pressure -20 inch Hg and tensile test 2.5 bar showed the welding parameters III and IV did not have leakage and damaged. So that parameters III and IV are recommended to be applied to Ir-192 HDR's source. (author)

  9. Microstructural evolution and properties of friction stir welded aluminium alloy AA2219

    International Nuclear Information System (INIS)

    Gupta, R. K.; Biju, S.; Ghosh, B. R.; Sinha, P. P.

    2007-01-01

    Low weld strength of fusion welded joints of aluminium alloy AA2219 is a concern in fabrication of pressure vessels and is attributable to the presence of weld defects, as well as various metallurgical factors. Friction stir welding (FSW), being a solid state joining process has obvious advantages over fusion welding. Results of preliminary FSW experiments conducted on 10 mm thick plate using a particular tool configuration are presented here. Microscopic studies show the presence of very fine equiaxed recrystallised grain at the weld nugget and a flow pattern of grains due to heavy deformation in defect-free weld coupons. Mechanical properties are correlated with the microstructure and process variables. Fractographic analysis complements the observations of optical microscopy and mechanical properties

  10. Effect of Welding Parameters on Microstructure and Mechanical Properties of Cast Fe-40Al Alloy

    Directory of Open Access Journals (Sweden)

    Osman Torun

    2016-09-01

    Full Text Available Friction welding of cast Fe-40Al alloy was carried out at 1000 rmp for various friction times, friction pressures, and forging pressures. The microstructures of the interface of welded samples were analyzed by optical and scanning electron microscopy (SEM. Micrographs demonstrated that excellent welding formed continuously along the interface, except for samples welded for 3 s. Chemical compositions of the interface of the friction welded samples and of the fractured surface of all the specimens were determined using energy dispersive spectroscopy (EDS. After the welding process, shear tests were applied to the welded samples to determine the shear strength of joints. Test results indicated that the maximum shear strength was 469.5 MPa.

  11. Low Alloy Steel Structures After Welding with Micro-Jet Cooling

    Directory of Open Access Journals (Sweden)

    Węgrzyn T.

    2017-03-01

    Full Text Available The paper focuses on low alloy steel after innovate welding method with micro-jet cooling. Weld metal deposit (WMD was carried out for welding and for MIG and MAG welding with micro-jet cooling. This method is very promising mainly due to the high amount of AF (acicular ferrite and low amount of MAC (self-tempered martensite, retained austenite, carbide phases in WMD. That structure corresponds with very good mechanical properties, ie. high impact toughness of welds at low temperature. Micro-jet cooling after welding can find serious application in automotive industry very soon. Until that moment only argon, helium and nitrogen were tested as micro-jet gases. In that paper first time various gas mixtures (gas mixtures Ar-CO2 were tested for micro-jet cooling after welding.

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  13. Sensor based robot laser welding - based on feed forward and gain sceduling algorithms

    DEFF Research Database (Denmark)

    Andersen, Henrik John

    2001-01-01

    A real-time control system forlaser welding of thick steel plates are developed and tested in a industrial environment. The robotic execution of the laser welding process is based on measure weld joint geometry and impirically established welding procedures. The influence of industrial production...... environment and manufacturing tolerences of the workpieces are evaluated....

  14. Refurbishment of damaged tools using the combination of GTAW and laser beam welding

    Directory of Open Access Journals (Sweden)

    J. Tušek

    2014-10-01

    Full Text Available This paper presents the use of two welding processes for the refurbishment of damaged industrial tools. In the first part the problem is presented followed by the comparison of GTAW and laser welding in terms of repair welding of damaged tools. The macrosections of the welds show the difference between both welding processes in repairing of damaged tools. At the conclusion the main findings are presented. In many cases it is useful to use both welding processes in order to achieve better weld quality and to make welding more economical. The order of the technology used depends on the tool material, the use of the tool and the tool damage.

  15. Effect of Heat Input During Disk Laser Bead-On-Plate Welding of Thermomechanically Rolled Steel on Penetration Characteristics and Porosity Formation in the Weld Metal

    Directory of Open Access Journals (Sweden)

    Lisiecki A.

    2016-03-01

    Full Text Available The paper presents a detailed analysis of the influence of heat input during laser bead-on-plate welding of 5.0 mm thick plates of S700MC steel by modern Disk laser on the mechanism of steel penetration, shape and depth of penetration, and also on tendency to weld porosity formation. Based on the investigations performed in a wide range of laser welding parameters the relationship between laser power and welding speed, thus heat input, required for full penetration was determined. Additionally the relationship between the laser welding parameters and weld quality was determined.

  16. Laser Welding Of Finned Tubes Made Of Austenitic Steels

    Directory of Open Access Journals (Sweden)

    Stolecki M.

    2015-09-01

    Full Text Available This paper describes the technology of welding of finned tubes made of the X5CrNi1810 (1.4301 austenitic steel, developed at Energoinstal SA, allowing one to get high quality joints that meet the requirements of the classification societies (PN-EN 15614, and at the same time to significantly reduce the manufacturing costs. The authors described an automatic technological line equipped with a Trumph disc laser and a tube production technological process. To assess the quality of the joints, one performed metallographic examinations, hardness measurements and a technological attempt to rupture the fin. Analysis of the results proved that the laser-welded finned tubes were performed correctly and that the welded joints had shown no imperfections.

  17. Laser welded versus resistance spot welded bone implants: analysis of the thermal increase and strength.

    Science.gov (United States)

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

    2014-01-01

    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. 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. 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). 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.

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

    Directory of Open Access Journals (Sweden)

    Carlo Fornaini

    2014-01-01

    Full Text Available 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.

  19. Thin-Sheet zinc-coated and carbon steels laser welding

    International Nuclear Information System (INIS)

    Pecas, P.; Gouveia, H.; Quintino, L.

    1998-01-01

    This paper describes the results of a research on CO 2 laser welding of thin-sheet carbon steels (Zinc-coated and uncoated), at several thicknesses combinations. Laser welding has an high potential to be applied on sub-assemblies welding before forming to the automotive industry-tailored blanks. The welding process is studied through the analysis of parameters optimization, metallurgical quality and induced distortions by the welding process. The clamping system and the gas protection system developed are fully described. These systems allow the minimization of common thin-sheet laser welding defects like misalignment, and zinc-coated laser welding defects like porous and zinc ventilation. The laser welding quality is accessed by DIN 8563 standard, and by tensile, microhardness and corrosion test. (Author) 8 refs

  20. Effect of the overlapping factor on the microstructure and mechanical properties of pulsed Nd:YAG laser welded Ti6Al4V sheets

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Xiao-Long; Liu, Jing; Zhang, Lin-Jie, E-mail: zhanglinjie@mail.xjtu.edu.cn; Zhang, Jian-Xun

    2014-07-01

    The effect of the overlapping factor on the microstructures and mechanical properties of pulsed Nd:YAG laser welded Ti6Al4V alloy sheets was investigated by microstructural observations, microhardness tests, tensile tests and fatigue tests. A microstructural examination shows that by increasing the overlapping factor, the grains in the fusion zone become coarser, and the width of the heat affected zone increases. As overlapping factor increases, the width of region composed completely of martensite α′ and the secondary α phase in the heat affected zone increases, consequently the gradient of microstructure along the direction from the fusion zone to base metal decreases, so does the gradient of microhardness. The results of tensile and fatigue tests reveal that the joints made using medium overlapping factor exhibit better mechanical properties than those welded with low and high overlapping factors. Based on the experimental results, it can be stated that a sound weld of Ti6Al4V alloy can be obtained if an appropriate overlapping factor is used. - Highlights: • The weld quality of Ti6Al4V alloy under various overlapping factors was assessed. • Tensile and fatigue tests were conducted with as-welded specimen. • Localized strain across the weld was measured using DIC photogrammetry system. • A sound weld of Ti6Al4V alloy is obtained by using right overlapping factor.

  1. Properties and Microstructure of Laser Welded VM12-SHC Steel Pipes Joints

    Directory of Open Access Journals (Sweden)

    Skrzypczyk A.

    2016-06-01

    Full Text Available Paper presents results of microstructure and tests of welded joints of new generation VM12-SHC martensitic steel using high power CO2 laser (LBW method with bifocal welding head. VM12-SHC is dedicated to energetic installation material, designed to replace currently used. High content of chromium and others alloying elements improve its resistance and strength characteristic. Use of VM12-SHC steel for production of the superheaters, heating chambers and walls in steam boilers resulted in various weldability researches. In article are presented results of destructive and non-destructive tests. For destructive: static bending and Vickers hardness tests, and for non-destructive: VT, RT, UT, micro and macroscopic tests were performed.

  2. Blue-Light Hazard From Gas Metal Arc Welding of Aluminum Alloys.

    Science.gov (United States)

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

    2017-10-01

    The objective was to quantify the blue-light hazard from gas metal arc welding (GMAW) of aluminum alloys. The exposure level is expected to depend on the welding conditions. Therefore, it is important to identify the blue-light hazard under various welding conditions. We experimentally conducted GMAW of aluminum alloys under various welding conditions and measured the spectral radiance of the arcs. The effective blue-light radiance, which the American Conference of Governmental Industrial Hygienists has defined to quantify the exposure level of blue light, was calculated from the measured spectral radiance. The maximum acceptable exposure duration per 10000 s for this effective blue-light radiance was calculated. The effective blue-light radiance measured in this study was in the range of 2.9-20.0 W cm-2·sr. The corresponding maximum acceptable exposure duration per 10000 s was only 5.0-34 s, so it is hazardous to view the welding arc. The effective blue-light radiance was higher at higher welding currents than at lower welding currents, when pulsed welding currents were used rather than steady welding currents, and when magnesium was included in the welding materials. It is very hazardous to view the arcs in GMAW of aluminum alloys. Welders and their helpers should use appropriate eye protection in arc-welding operations. They should also avoid direct light exposure when starting an arc-welding operation. © The Author 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

  3. Microstructure and properties of friction stir butt-welded AZ31 magnesium alloy

    International Nuclear Information System (INIS)

    Wang Xunhong; Wang Kuaishe

    2006-01-01

    Friction stir welding (FSW) is a relatively new joining technique particularly for magnesium and aluminum alloys that are difficult to fusion weld. In this paper, an excellent friction stir weld of AZ31 magnesium alloy was obtained at proper parameter. In the friction stir zone (FSZ), the microstructure of the base material (BM) is replaced by fine grains and small particles of intermetallic compounds. The average microhardness of the friction stir zone is higher than that of the base material. The maximum tensile strength of joint can reach 93% that of the base material. And the failure locations are almost at the heating affected zone

  4. Polyethylene laser welding based on optical absorption variations

    Science.gov (United States)

    Galtieri, G.; Visco, A.; Nocita, D.; Torrisi, L.; Ceccio, G.; Scolaro, C.

    2016-04-01

    Polymeric materials, both pure and containing nanostructures, can be prepared as thin sheets in order to produce joints with an interface between an optically transparent sheet and an optically absorbent substrate to be welded by infrared pulsed laser irradiation. The Laser Transmission Welding (LTW) technique has been successfully applied in order to join two or more thermoplastic polymeric sheets that must have a similar chemical composition. In this research work, polymeric joints of Ultra High Molecular Weight Polyethylene sheets were realized, characterized and welded. Some polymer sheets were doped, at different concentrations, with carbon nano-particles absorbent the laser radiation. A pulsed laser operating in the wavelength region 532 nm with intensity of the order of 109 Watt/cm2 was employed to be transmitted by the transparent polymer and to be absorbed by the carbon enriched surface. At the interface of the two polymers the released energy induces melting, that is assisted by pressure, producing a fast and resistant welding zone. Mechanical and optical characterizations and surface analyses are presented and discussed.

  5. Laser welding of a beryllium/tantalum collimator

    International Nuclear Information System (INIS)

    Lingenfelter, A.C.; Anglin, C.D.

    1985-01-01

    This report describes the methods utilized in the fabrication of a collimator from 0.001 inch thick beryllium and tantalum foil. The laser welding process proved to be an acceptable method for joining the beryllium in a standing edge joint configuration

  6. Critical Gap distance in Laser Butt-welding

    DEFF Research Database (Denmark)

    Bagger, Claus; Olsen, Flemming Ove

    When butt-welding metal sheets with high power lasers the gap distance between the sheets determine the final quality of the seam. In a number of systematic laboratory experiments the critical gap distance that results in sound beads is identified. By grinding the edges of the sheets, a number of...

  7. Modeling of the Thermal Behavior of Metals During Welding Laser ...

    African Journals Online (AJOL)

    The temperature distribution in the workpiece can be determined from the heat equation which expresses the energy balance. This is a parabolic differential equation and for resolution we applied the finite difference method using the implicit scheme. Keywords: Laser Welding, Metal, Finite differences, temperature profile.

  8. Melt pool vorticity in deep penetration laser material welding

    Indian Academy of Sciences (India)

    this value, convective heat transfer indicates melting and evaporation occurring in the weld pool during laser ... while surface tension and hydrostatic pressure help to retain the melt in the keyhole cavity in this high .... so does the strength of the shock wave and the Mach angle becomes increasingly narrow. As the melt flow ...

  9. Effect of post-weld aging treatment on mechanical properties of Tungsten Inert Gas welded low thickness 7075 aluminium alloy joints

    International Nuclear Information System (INIS)

    Temmar, M.; Hadji, M.; Sahraoui, T.

    2011-01-01

    Highlights: → The effects of post-weld aging treatment on the properties of joints is studied. → The post-weld aging treatment increases the tensile strength of TIG welded joints. → The strengthening is due to a balance of dissolution, reversion and precipitation. → Simple post-weld aging at 140 o C enhances the properties of the welded joints. -- Abstract: This paper reports the influence of post-weld aging treatment on the microstructure, tensile strength, hardness and Charpy impact energy of weld joints low thickness 7075 T6 aluminium alloy welded by Tungsten Inert Gas (TIG). Hot cracking occurs in aluminium welds when high levels of thermal stress and solidification shrinkage are present while the weld is undergoing various degrees of solidification. Weld fusion zones typically exhibit microstructure modifications because of the thermal conditions during weld metal solidification. This often results in low weld mechanical properties and low resistance to hot cracking. It has been observed that the mechanical properties are very sensitive to microstructure of weld metal. Simple post-weld aging treatment at 140 o C applied to the joints is found to be beneficial to enhance the mechanical properties of the welded joints. Correlations between microstructures and mechanical properties were discussed.

  10. Design, implementation and testing of a fuzzy control scheme for laser welding

    NARCIS (Netherlands)

    Jauregui Becker, Juan Manuel; Aalderink, B.J.; Aalderink, Benno; Aarts, Ronald G.K.M.; Olde Benneker, Jeroen; Meijer, J.

    2008-01-01

    A fuzzy logic controller (FLC) scheme has been developed for laser welding. Process light emissions are measured and combined to determine the current status of the welding process. If the process is not in a desired welding state, the FLC will adapt the laser power. The FLC has been demonstrated

  11. Influence of Post Weld Heat Treatment on Strength of Three Aluminum Alloys Used in Light Poles

    Directory of Open Access Journals (Sweden)

    Craig C. Menzemer

    2016-03-01

    Full Text Available The conjoint influence of welding and artificial aging on mechanical properties were investigated for extrusions of aluminum alloy 6063, 6061, and 6005A. Uniaxial tensile tests were conducted on the aluminum alloys 6063-T4, 6061-T4, and 6005A-T1 in both the as-received (AR and as-welded (AW conditions. Tensile tests were also conducted on the AR and AW alloys, subsequent to artificial aging. The welding process used was gas metal arc (GMAW with spray transfer using 120–220 A of current at 22 V. The artificial aging used was a precipitation heat treatment for 6 h at 182 °C (360 °F. Tensile tests revealed the welded aluminum alloys to have lower strength, both for yield and ultimate tensile strength, when compared to the as-received un-welded counterpart. The beneficial influence of post weld heat treatment (PWHT on strength and ductility is presented and discussed in terms of current design provisions for welded aluminum light pole structures.

  12. Microstructure and Mechanical Properties of TIG Weld Joint of ZM5 Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    QIN Ren-yao

    2016-06-01

    Full Text Available The ZM5 magnesium alloy plates were welded by TIG welding method. The microstructural characteristics and mechanical properties of ZM5 magnesium alloy joint were studied by optical microscopy, microhardness and tensile testers. The results show that the TIG weld joint of ZM5 magnesium alloy is composed of heat affected zone, partially melted zone and weld metal. The heat affected zone is consisted of primary α-Mg phase and eutectic phase that is composed of eutectic α-Mg and eutectic β-Mg17Al12 phase and mainly precipitated at grain boundaries. In the partially melted zone, the eutectic phase is not only increasingly precipitated at grain boundaries, but also dispersed in grains, and the growth of the β-Mg17Al12 phase is obviously observed. The microstructure in the weld is the typical dendritic morphology. The dendrites are considered as primary α-Mg phase, and the interdendritic regions are α+β eutectic phase. The difference in the microstructure of the heat affected zone, partially melted zone and weld results in their various microhardness values, and leads to the smaller tensile strength and ductility in the ZM5 alloy weld joint than parent metal.

  13. Resistance Spot Welding of Aluminum Alloy to Steel with Transition Material - From Process to Performance

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.; Shao, H; Kimchi, Menachem; Menachem Kimchi and Wanda Newman

    2004-05-11

    This paper summarizes work to date on resistance spot welding (RSW) of aluminum alloy to mild steel from process development to performance evaluation. A cold-rolled strip material is introduced as a transition material to aid the resistance welding process. The optimal welding parameters and electrode selections were established using a combination of experimental and analytical approaches. The mechanical behaviors of welded samples was evaluated using static and dynamic strength tests and cyclic fatigue tests. A statistical analysis was also performed to analyze the effect of different failure modes on the sample's peak load and energy absorption.

  14. Microstructural evolution during friction stir welding of AlSi1MgMn alloy

    Directory of Open Access Journals (Sweden)

    M. Janjić

    2012-01-01

    Full Text Available This paper provides the research of the infl uence of geometric and kinematic parameters on the microstructure and mechanical properties of welded joint of aluminum alloy AlSi1MgMn (6082-T6 obtained through the Friction Stir Welding (FSW process. The experiment parameters were welding speed, rotation speed, angle of pin slope, pin diameter and shoulder diameter. On the obtained welded workpieces the dynamic testing on the impact toughness, and determination of microstructural zones were carried out.

  15. Laser transmission welding of long glass fiber reinforced thermoplastics

    Science.gov (United States)

    van der Straeten, Kira; Engelmann, Christoph; Olowinsky, Alexander; Gillner, Arnold

    2015-03-01

    Joining fiber reinforced polymers is an important topic for lightweight construction. Since classical laser transmission welding techniques for polymers have been studied and established in industry for many years joint-strengths within the range of the base material can be achieved. Until now these processes are only used for unfilled and short glass fiber-reinforced thermoplastics using laser absorbing and laser transparent matrices. This knowledge is now transferred to joining long glass fiber reinforced PA6 with high fiber contents without any adhesive additives. As the polymer matrix and glass fibers increase the scattering of the laser beam inside the material, their optical properties, changing with material thickness and fiber content, influence the welding process and require high power lasers. In this article the influence of these material properties (fiber content, material thickness) and the welding parameters like joining speed, laser power and clamping pressure are researched and discussed in detail. The process is also investigated regarding its limitations. Additionally the gap bridging ability of the process is shown in relation to material properties and joining speed.

  16. Design of welding parameters for laser welding of thin-walled stainless steel tubes using numerical simulation

    Science.gov (United States)

    Nagy, M.; Behúlová, M.

    2017-11-01

    Nowadays, the laser technology is used in a wide spectrum of applications, especially in engineering, electronics, medicine, automotive, aeronautic or military industries. In the field of mechanical engineering, the laser technology reaches the biggest increase in the automotive industry, mainly due to the introduction of automation utilizing 5-axial movements. Modelling and numerical simulation of laser welding processes has been exploited with many advantages for the investigation of physical principles and complex phenomena connected with this joining technology. The paper is focused on the application of numerical simulation to the design of welding parameters for the circumferential laser welding of thin-walled exhaust pipes from theAISI 304 steel for automotive industry. Using the developed and experimentally verified simulation model for laser welding of tubes, the influence of welding parameters including the laser velocity from 30 mm.s-1 to 60 mm.s-1 and the laser power from 500 W to 1200 W on the temperature fields and dimensions of fusion zone was investigated using the program code ANSYS. Based on obtained results, the welding schedule for the laser beam welding of thin-walled tubes from the AISI 304 steel was suggested.

  17. Friction Stir Welding of three dissimilar aluminium alloy used in aeronautics industry

    Science.gov (United States)

    Boşneag, A.; Constantin, M. A.; Niţu, E.; Iordache, M.

    2017-10-01

    Friction Stir Welding (FSW) is an innovative solid-state joining process. This process was, in first time, develop to join the similar aluminum plates but now the technology can be used to weld a large area of materials similar or dissimilar. Taking these into account FSW process, for dissimilar materials are increasingly required, more than traditional arc welding, in industrial environment. More than that FSW is used in aeronautics industry because of very good result and very good weldability between aluminum alloy used at building of airplanes, where the body of airplane are 20% aluminum alloy and this percent can be increaser in future. In this paper is presented an experimental study which includes welding three dissimilar aluminum alloy, with different properties, used in aeronautics industry, this materials are: AA 2024, AA6061 and AA7075. After welding with different parameters, the welding join and welding process will be analyzed considering process temperature, process vertical force, and roughnessof welding seams, visual aspect and microhardness.

  18. Braze Welding TIG of Titanium and Aluminium Alloy Type Al – Mg

    Directory of Open Access Journals (Sweden)

    Winiowski A.

    2016-03-01

    Full Text Available The article presents the course and the results of technological tests related to TIG-based arc braze welding of titanium and AW-5754 (AlMg3 aluminium alloy. The tests involved the use of an aluminium filler metal (Al99.5 and two filler metals based on Al-Si alloys (AlSi5 and AlSi12. Braze welded joints underwent tensile tests, metallographic examinations using a light microscope as well as structural examinations involving the use of a scanning electron microscope and an X-ray energy dispersive spectrometer (EDS. The highest strength and quality of welds was obtained when the Al99.5 filler metal was used in a braze welding process. The tests enabled the development of the most convenient braze welding conditions and parameters.

  19. Development of liquid-nitrogen-cooling friction stir spot welding for AZ31 magnesium alloy joints

    Science.gov (United States)

    Wu, Dong; Shen, Jun; Zhou, Meng-bing; Cheng, Liang; Sang, Jia-xing

    2017-10-01

    A liquid-nitrogen-cooling friction stir spot welding (C-FSSW) technology was developed for welding AZ31 magnesium alloy sheets. The liquid-nitrogen cooling degraded the deformability of the welded materials such that the width of interfacial cracks increased with increasing cooling time. The grain size of the stirred zone (SZ) and the heat-affected zone (HAZ) of the C-FSSW-welded joints decreased, whereas that of the thermomechanically affected zone (TMAZ) increased with increasing cooling time. The maximum tensile shear load of the C-FSSW-welded joints welded with a cooling time of 5 or 7 s was larger than that of the friction stir spot welding (FSSW)-welded joint, and the tensile shear load decreased with increasing cooling time. The microhardness of the C-FSSW-welded joints was greater than that of the FSSW-welded joint. Moreover, the microhardness of the SZ and the HAZ of the C-FSSW-welded joints increased, whereas that of the TMAZ decreased, with increasing cooling time.

  20. Laser alloyed Al-Ni-Fe coatings

    CSIR Research Space (South Africa)

    Pityana, SL

    2008-10-01

    Full Text Available The aim of this work was to produce crack-free thin surface layers consisting of binary (Al-Ni, Al-Fe) and ternary (Al-Ni-Fe) intermetallic phases by means of a high power laser beam. The laser surface alloying was carried out by melting Fe and Ni...

  1. Laser Brazing of High Temperature Braze Alloy

    Science.gov (United States)

    Gao, Y. P.; Seaman, R. F.; McQuillan, T. J.; Martiens, R. F.

    2000-01-01

    The Space Shuttle Main Engine (SSME) consists of 1080 conical tubes, which are furnace brazed themselves, manifolds, and surrounding structural jacket making almost four miles of braze joints. Subsequent furnace braze cycles are performed due to localized braze voids between the coolant tubes. SSME nozzle experiences extremely high heat flux (180 mW/sq m) during hot fire. Braze voids between coolant tubes may result in hot combustion gas escape causing jacket bulges. The nozzle can be disqualified for flight or result in mission failure if the braze voids exceed the limits. Localized braze processes were considered to eliminate braze voids, however, damage to the parent materials often prohibited use of such process. Being the only manned flight reusable rocket engine, it has stringent requirement on the braze process. Poor braze quality or damage to the parent materials limits the nozzle service life. The objective of this study was to develop a laser brazing process to provide quality, localized braze joints without adverse affect on the parent materials. Gold (Au-Cu-Ni-Pd-Mn) based high temperature braze alloys were used in both powder and wire form. Thin section iron base superalloy A286 tube was used as substrate materials. Different Laser Systems including CO2 (10.6 micrometers, 1kW), ND:YAG (1.06 micrometers, 4kW). and direct diode laser (808nm. 150W) were investigated for brazing process. The laser process variables including wavelength. laser power, travel speed and angle of inclination were optimized according to bead geometry and braze alloy wetting at minimum heat input level, The properties of laser brazing were compared to that of furnace brazing. Microhardness profiles were used for braze joint property comparison between laser and furnace brazing. The cooling rate of laser brazing was compared to furnace brazing based on secondary dendritic arm spacing, Both optical and Scanning Electron Microscope (SEM) were used to evaluate the microstructures of

  2. Spot Welding of 6061 Aluminum Alloy by Friction Stir Spot Welding Process

    Directory of Open Access Journals (Sweden)

    M. A. Tashkandi

    2017-06-01

    Full Text Available This study was focused on the effect of welding parameters on the lap-shear fracture load of the welded joints prepared by friction stir spot welding. Four different weld parameters were analyzed: rotational speed, dwell time, pin length and shoulder size of the welding tool. It was found that the lap-shear fracture load increases with an increase of the welding parameters to a limited value and decreases with further increase. The strong welded joints failed under nugget-pull out fracture.

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

    Science.gov (United States)

    Unt, Anna; Poutiainen, Ilkka; Salminen, Antti

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

  4. Effect of process parameters on mechanical properties of friction stir spot welded magnesium to aluminum alloys

    International Nuclear Information System (INIS)

    Rao, H.M.; Yuan, W.; Badarinarayan, H.

    2015-01-01

    Highlights: • Lap-shear failure load of ∼2.5 kN was achieved in dissimilar Mg to Al spot welds. • Failure load depends on both welding geometrical features and IMCs formation. • Thin and discontinuous IMCs formed in stir zone are beneficial for weld strength. • Low heat input and good material mixing/interlocking is essential for high strength. - Abstract: Friction stir spot welding was applied to dissimilar cast magnesium (Mg) alloy AM60B and wrought aluminum (Al) alloy 6022-T4 under various welding conditions. The influence of tool rotation rate and shoulder plunge depth on lap-shear failure load was examined. Welds were made at four different tool rotation rates of 1000, 1500, 2000 and 2500 revolution per minute (rpm) and various tool shoulder plunge depths from 0 mm to 0.9 mm. The cross section of each weld exhibited the formation of intermetallic compounds (IMCs) in the stir zone. An increase in tool rotation rate decreased the width of the stir zone and resulted in lower lap-shear failure loads. The stir zone width increased and interlocking of IMCs was observed with an increase in tool shoulder plunge depth at 1000 rpm. High lap-shear failure loads were achieved in welds having a large stir zone width with formation of discontinuous IMCs at the tip of the interfacial hook. An average lap-shear failure load of 2.5 kN was achieved for welds made at 1000 rpm and 0.9 mm shoulder plunge. The present study suggests that the mechanical properties of friction stir spot welded dissimilar alloys are greatly influenced by the stir zone width, interfacial hooks and IMCs which are all weld process dependent

  5. Stress corrosion cracking of alloy 182 weld in a PWR water environment

    International Nuclear Information System (INIS)

    Lima, Luciana Iglesias Lourenco; Schvartzman, Monica Maria de Abreu Mendonca; Quinan, Marco Antonio Dutra; Soares, Antonio Edicleto Gomes; Piva, Stephano P.T.

    2011-01-01

    The weld used to connect two different metals is known as dissimilar metal welds (DMW). In the nuclear power plant, this weld is used to join stainless steel nipples to low alloy carbon steel components on the nuclear pressurized water reactor (PWR). In most cases, nickel alloys are used to joint these materials. These alloys are known to accommodate the differences in composition and thermal expansion of the two materials. The stress corrosion cracking (SCC) is a phenomenon that occurs in nuclear power plants metallic components where susceptibility materials are subjected to the simultaneously effect of mechanical stress and an aggressive media with different compositions. SCC is one of degradation process that gradually introduces damage of components, change their characteristics with the operation time. The nickel alloy 600, and their weld metals (nickel alloys 82 and 182), originally selected due to its high corrosion resistance, it exhibit after long operation period (20 years), susceptibility to the SCC. This study presents a comparative work between the SCC in the Alloy 182 filler metal weld in two different temperatures (303 deg C and 325 deg C) in primary water. The susceptibility to stress corrosion cracking was assessed using the slow strain rate tensile (SSRT) test. The results of the SSRT tests indicated that SCC is a thermally-activated mechanism and that brittle fracture caused by the corrosion process was observed at 325 deg C. (author)

  6. Amorphization by friction welding between 5052 aluminum alloy and 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Fukumoto, S.; Tsubakino, H.; Okita, K.; Aritoshi, M.; Tomita, T.

    2000-04-14

    The joining of dissimilar metals such as aluminum/stainless steel is a very important technique. In the case of fusion welding of an Fe-Al system, excess formation of brittle intermetallic compounds degrades the joint. Since friction welding is one of the solid-state bonding procedures, few intermetallic compounds are formed at the weld interface. However, in the Al-Fe system, the solid solubility is almost nil, so some intermetallic compounds will be formed in spite of the friction welding. In the present study, microstructure of the friction weld interface between Al-Mg alloy and austenitic stainless steel was investigated by high resolution transmission electron microscopy and the mechanism of friction welding was examined.

  7. Advanced Testing Techniques to Measure the PWSCC Resistance of Alloy 690 and its Weld Metals

    Energy Technology Data Exchange (ETDEWEB)

    P.Andreson

    2004-10-01

    Wrought Alloy 600 and its weld metals (Alloy 182 and Alloy 82) were originally used in pressurized water reactors (PWRs) due to the material's inherent resistance to general corrosion in a number of aggressive environments and because of a coefficient of thermal expansion that is very close to that of low alloy and carbon steel. Over the last thirty years, stress corrosion cracking in PWR primary water (PWSCC) has been observed in numerous Alloy 600 component items and associated welds, sometimes after relatively long incubation times. The occurrence of PWSCC has been responsible for significant downtime and replacement power costs. As part of an ongoing, comprehensive program involving utilities, reactor vendors and engineering/research organizations, this report will help to ensure that corrosion degradation of nickel-base alloys does not limit service life and that full benefit can be obtained from improved designs for both replacement components and new reactors.

  8. Microstructural Characteristic of Dissimilar Welded Components (AISI 430 Ferritic-AISI 304 Austenitic Stainless Steels) by CO2 Laser Beam Welding (LBW)

    OpenAIRE

    CALIGULU, Ugur; DIKBAS, Halil; TASKIN, Mustafa

    2012-01-01

    In this study, microstructural characteristic of dissimilar welded components (AISI 430 ferritic-AISI 304 austenitic stainless steels) by CO2 laser beam welding (LBW) was investigated. Laser beam welding experiments were carried out under argon and helium atmospheres at 2000 and 2500 W heat inputs and 100-200-300 cm/min. welding speeds. The microstructures of the welded joints and the heat affected zones (HAZ) were examined by optical microscopy, SEM, EDS and XRD analysis. The tensile strengt...

  9. Microstructural Characteristic of Dissimilar Welded Components (AISI 430 Ferritic-AISI 304 Austenitic Stainless Steels) by CO2 Laser Beam Welding (LBW)

    OpenAIRE

    ÇALIGÜLÜ, Uğur; CALIGULU, Ugur; DIKBAS, Halil; TASKIN, Mustafa

    2010-01-01

    In this study, microstructural characteristic of dissimilar welded components (AISI 430 ferritic-AISI 304 austenitic stainless steels) by CO2 laser beam welding (LBW) was investigated. Laser beam welding experiments were carried out under argon and helium atmospheres at 2000 and 2500 W heat inputs and 100-200-300 cm/min. welding speeds. The microstructures of the welded joints and the heat affected zones (HAZ) were examined by optical microscopy, SEM, EDS and XRD analysis. The tensile strengt...

  10. Influence of laser beam incidence angle on laser lap welding quality of galvanized steels

    Science.gov (United States)

    Mei, Lifang; Yan, Dongbing; Chen, Genyu; Wang, Zhenhui; Chen, Shuixuan

    2017-11-01

    Based on the characteristics of laser welded structural parts of auto bodies, the influence of variation in laser beam incidence angle on the lap welding performance of galvanized auto-body sheets was studied. Lap welding tests were carried out on the galvanized sheets for auto-body application at different laser beam incidence angles by using the optimal welding parameters obtained through orthogonal experiment. The effects of incidence angle variation on seam appearance, cross-sectional shape, joint mechanical properties and microstructure of weldments were analyzed. In addition, the main factors influencing the value of incidence angle were investigated. According to the results, the weld seams had a good appearance as well as a fine, and uniform microstructure when the laser beam incidence angle was smaller than the critical incidence angle, and thus they could withstand great tensile and shear loads. Moreover, all tensile-shear specimens were fractured in the base material zone. When the laser beam incidence angle was larger than the critical incidence angle, defects like shrinkage and collapse tended to emerge, thereby resulting in the deteriorated weldability of specimens. Meanwhile, factors like the type and thickness of sheet, weld width as well as inter-sheet gap all had a certain effect on the value of laser beam incidence angle. When the sheet thickness was small and the weld width was narrow, the laser beam incidence angle could be increased appropriately. At the same time, small changes in the inter-sheet gap could greatly impact the value of incidence angle. When the inter-sheet gap was small, the laser beam incidence angle should not be too large.

  11. UNS S32750 super duplex steel welding using pulsed Nd:YAG laser

    International Nuclear Information System (INIS)

    Francini, O.D.; Andrade, G.G.; Clemente, M.S.; Gallego, J.; Ventrella, V.A.

    2016-01-01

    Laser is a flexible and powerful tool with many relevant applications in industry, mainly in the welding area. Lasers today provide the welding industry technical solutions to many problems. This work studied the weld metal obtained by pulsed laser welding of Nd: YAG super duplex stainless steel UNS S32750 employed in the oil and natural gas, analyzing the influence of high cooling rate, due to the laser process, the swing phase ferrite / austenite. Were performed weld beads in butt joint with different repetition rates. The different microstructures were obtained by optical microscopy and scanning electron microscopy. The results showed that the effect of varying the welding energy of Nd: YAG laser on the volume fractions of the phases ferrite/austenite in the weld metal was its ferritization and low austenite amount on the grain boundary. (author)

  12. Development of an auto-welding system for CRD nozzle repair welds using a 3D laser vision sensor

    International Nuclear Information System (INIS)

    Park, K.; Kim, Y.; Byeon, J.; Sung, K.; Yeom, C.; Rhee, S.

    2007-01-01

    A control rod device (CRD) nozzle attaches to the hemispherical surface of a reactor head with J-groove welding. Primary water stress corrosion cracking (PWSCC) causes degradation in these welds, which requires that these defect areas be repaired. To perform this repair welding automatically on a complicated weld groove shape, an auto-welding system was developed incorporating a laser vision sensor that measures the 3-dimensional (3D) shape of the groove and a weld-path creation program that calculates the weld-path parameters. Welding trials with a J-groove workpiece were performed to establish a basis for developing this auto-welding system. Because the reactor head is placed on a lay down support, the outer-most region of the CRD nozzle has restricted access. Due to this tight space, several parameters of the design, such as size, weight and movement of the auto-welding system, had to be carefully considered. The cross section of the J-groove weld is basically an oval shape where the included angle of the J-groove ranges from 0 to 57 degrees. To measure the complex shape, we used double lasers coupled to a single charge coupled device (CCD) camera. We then developed a program to generate the weld-path parameters using the measured 3D shape as a basis. The program has the ability to determine the first and final welding positions and to calculate all weld-path parameters. An optimized image-processing algorithm was applied to resolve noise interference and diffused reflection of the joint surfaces. The auto-welding system is composed of a 4-axis manipulator, gas tungsten arc welding (GTAW) power supply, an optimized designed and manufactured GTAW torch and a 3D laser vision sensor. Through welding trials with 0 and 38-degree included-angle workpieces with both J-groove and U-groove weld, the performance of this auto-welding system was qualified for field application

  13. Medium- and high-pressure gauges and transducers produced by laser welding technology

    Science.gov (United States)

    Daurelio, Giuseppe; Nenci, Fabio; Cinquepalmi, Massimo; Chita, Giuseppe

    1998-07-01

    Industrial manufacturers produce many types of pressure gauges and transducers according to the applications, for gas or liquid, for high-medium and low pressure ranges. Nowadays the current production technology generally prefers to weld by micro TIG source the metallic corrugated membranes to the gauge or transducer bodies for the products, operating on the low pressure or medium pressure ranges. For the other ones, operating to high pressure range, generally the two components of the transducers are both threaded only and threaded and then circularly welded by micro TIG for the other higher range, till to 1000 bar. In this work the products, operating on the approximately equals 30 divided by 200 bar, are considered. These, when assembled on industrial plants, as an outcome of a non-correct operating sequence, give a 'shifted' electrical signal. This is due to a shift of the 'zero electrical signal' that unbalances the electrical bridge - thin layer sensor - that is the sensitive part of the product. Moreover, for the same problem, often some mechanical settlings of the transducer happen during the first pressure semi-components, with an increasing of the product manufacturing costs. In light of all this, the above referred, in this work the whole transducer has been re-designed according to the specific laser welding technology requirements. On the new product no threaded parts exist but only a circular laser welding with a full penetration depth about 2.5 divided by 3 mm high. Three different alloys have been tested according to the applications and the mechanical properties requested to the transducer. By using a 1.5 KW CO2 laser system many different working parameters have been evaluated for correlating laser parameters to the penetration depths, crown wides, interaction laser-materia times, mechanical and metallurgical properties. Moreover during the laser welding process the measurements of the maximum temperature, reached by the transducer top, has been

  14. The effect of advanced ultrasonic forging on fatigue fracture mechanisms of welded Ti-6A1-4V alloy

    Science.gov (United States)

    Smirnova, A.; Pochivalov, Yu.; Panin, V.; Panin, S.; Eremin, A.; Gorbunov, A.

    2017-12-01

    The current study is devoted to application of advanced postwelding ultrasonic forging to joints formed by laser welding of Ti-6A1-4V alloy in order to enhance their mechanical properties and fatigue durability. Low cycle fatigue tests were performed via digital image correlation technique used to obtain strain fields and in situ characterization of deformation, crack growth and fracture. Fracture surfaces were studied by SEM analysis accompanied with calculation of fracture patterns percentage. The fatigue tests demonstrate the high increase in the number of cycles until fracture (from 17 000 to 32 000 cycles) which could be explained by high ductility of welded material after treatment. This leads to lower fatigue crack growth rate due to higher energy dissipation. The obtained effect is attributable only for small cracks on micro-/mesoscales and fails to play a significant role for macro cracks.

  15. Emission of nanoparticles during friction stir welding (FSW) of aluminium alloys.

    Science.gov (United States)

    Gomes, J F; Miranda, R M; Santos, T J; Carvalho, P A

    2014-01-01

    Friction stir welding (FSW) is now well established as a welding process capable of joining some different types of metallic materials, as it was (1) found to be a reliable and economical way of producing high quality welds, and (2) considered a "clean" welding process that does not involve fusion of metal, as is the case with other traditional welding processes. The aim of this study was to determine whether the emission of particles during FSW in the nanorange of the most commonly used aluminum (Al) alloys, AA 5083 and AA 6082, originated from the Al alloy itself due to friction of the welding tool against the item that was being welded. Another goal was to measure Al alloys in the alveolar deposited surface area during FSW. Nanoparticles dimensions were predominantly in the 40- and 70-nm range. This study demonstrated that microparticles were also emitted during FSW but due to tool wear. However, the biological relevance and toxic manifestations of these microparticles remain to be determined.

  16. Joining of Aluminium Alloy and Steel by Laser Assisted Reactive Wetting

    Science.gov (United States)

    Liedl, Gerhard; Vázquez, Rodrigo Gómez; Murzin, Serguei P.

    2017-12-01

    Compounds of dissimilar materials, like aluminium and steel offer an interesting opportunity for the automotive industry to reduce the weight of a car body. Thermal joining of aluminium and steel leads to the formation of brittle intermetallic compounds, which negatively affects the properties of the welded joint. Amongst others, growth of such intermetallic compounds depends on maximum temperature and on the time at certain temperatures. Laser welding with its narrow well seam and its fast heating and cooling cycles provides an excellent opportunity to obtain an ultrathin diffusion zone. Joining of sheet metal DC01 with aluminium alloy AW6016 has been chosen for research. The performed experimental studies showed that by a variation of the beam power and scanning speed it is possible to obtain an ultrathin diffusion zone with narrow intermetallic interlayers. With the aim of supporting further investigation of laser welding of the respective and other dissimilar pairings a multi-physical simulation model has been developed.

  17. Effects of different dentin thicknesses and air cooling on pulpal temperature rise during laser welding.

    Science.gov (United States)

    Secilmis, Asli; Bulbul, Mehmet; Sari, Tugrul; Usumez, Aslihan

    2013-01-01

    The neodymium/yttrium-aluminum-garnet (Nd/YAG) laser has been suggested to repair broken prostheses in the mouth. This study investigated the effects of different dentin thicknesses and air cooling on pulpal temperature rise during laser welding. Three intact human maxillary molars were prepared for full-veneer crown. For each tooth, dentin thicknesses in mesiobuccal cusp was 2, 3, or 4 mm. Twenty dies were duplicated from each of the prepared teeth. For metal copings with 0.5-mm thickness, wax patterns were prepared with dip wax technique directly onto each of dies. All patterns were sprued and invested. The castings were made using a nickel-chromium alloy (Nicromed Premium, Neodontics). A hole with 0.5-mm diameter was prepared on the mesiobuccal cusp of each crown. The Nd/YAG laser (9.85 W; 1 Hz repetition rate; fluence, 1.230 J/cm(2); Fidelis Plus 3, Fotona) was used for welding with or without air cooling (n = 10). The temperature rise was measured in pulpal chamber with a J-type thermocouple wire that was connected to a data logger. Differences between start and highest temperature reading were taken, and temperature rise values were compared using two-way analysis of variance and Tukey's honestly significant difference tests (α = .05). Pulpal temperature rise varied significantly depending on the dentin thickness and air cooling (p cooling group induced significantly the highest temperature increases. There were no significant differences between 2- and 3-mm dentin thicknesses groups (p > 0.05); however, pulpal temperature rise was the lowest for 4-mm dentin thickness group (p cooling was used in 2-mm dentin thickness group. Laser welding on base metal castings with Nd/YAG laser can be applied with air cooling to avoid temperature rises known to adversely affect pulpal health when dentin thickness is 2 or 3 mm.

  18. Predicting tensile strength of friction stir welded AA6061 aluminium alloy joints by a mathematical model

    International Nuclear Information System (INIS)

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

    2009-01-01

    AA6061 aluminium alloy (Al-Mg-Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to weight ratio and good corrosion resistance. Compared to the fusion welding processes that are routinely used for joining structural aluminium alloys, 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 tool pin profile play a major role in deciding the joint strength. An attempt has been made to develop a mathematical model to predict tensile strength of the friction stir welded AA6061 aluminium alloy by incorporating FSW process parameters. Four factors, five levels central composite design has been used to minimize number of experimental conditions. Response surface method (RSM) has been used to develop the model. Statistical tools such as analysis of variance (ANOVA), student's t-test, correlation co-efficient etc. have been used to validate the developed model. The developed mathematical model can be effectively used to predict the tensile strength of FSW joints at 95% confidence level

  19. Analysis of Pulsed Laser Welding Parameters Effect on Weld Geometry of 316L Stainless Steel using DOE

    Directory of Open Access Journals (Sweden)

    M. R. Pakmanesh

    2018-03-01

    Full Text Available In the present study, the optimization of pulsed Nd:YAG laser welding parameters was done on a lap-joint of a 316L stainless steel foil in order to predict the weld geometry through response surface methodology. For this purpose, the effects of laser power, pulse duration, and frequency were investigated. By presenting a second-order polynomial, the above-mentioned statistical method was managed to be well employed to evaluate the effect of welding parameters on weld width. The results showed that the weld width at the upper, middle and lower surfaces of weld cross section increases by increasing pulse durationand laser power; however, the effects of these parameters on the mentioned levels are different. The effect of pulse duration in the models of weld upper, middle and lower widths was calculated as 76, 73 and 68%, respectively. Moreover, the effect of power on theses widths was determined as 18, 24 and 28%, respectively. Finally, by superimposing these models, optimum conditions were obtained to attain a full penetration weld and the weld with no defects.

  20. Microstructure and mechanical properties of GTAW welded joints of AA6105 aluminum alloy

    Directory of Open Access Journals (Sweden)

    Minerva Dorta-Almenara

    2016-09-01

    Full Text Available Gas Tungsten Arc Welding (GTAW is one of the most used methods to weld aluminum. This work investigates the influence of welding parameters on the microstructure and mechanical properties of GTAW welded AA6105 aluminum alloy joints. AA6105 alloy plates with different percent values of cold work were joined by GTAW, using various combinations of welding current and speed. The fusion zone, in which the effects of cold work have disappeared, and the heat affected zone of the welded samples were examined under optical and scanning electron microscopes, additionally, mechanical tests and measures of Vickers microhardness were performed. Results showed dendritic morphology with solute micro- and macrosegregation in the fusion zone, which is favored by the constitutional supercooling when heat input increases. When heat input increased and welding speed increased or remained constant, greater segregation was obtained, whereas welding speed decrease produced a coarser microstructure. In the heat affected zone recrystallization, dissolution, and coarsening of precipitates occurred, which led to variations in hardness and strength.

  1. Laser polishing of additive manufactured Ti alloys

    Science.gov (United States)

    Ma, C. P.; Guan, Y. C.; Zhou, W.

    2017-06-01

    Laser-based additive manufacturing has attracted much attention as a promising 3D printing method for metallic components in recent years. However, surface roughness of additive manufactured components has been considered as a challenge to achieve high performance. In this work, we demonstrate the capability of fiber laser in polishing rough surface of additive manufactured Ti-based alloys as Ti-6Al-4V and TC11. Both as-received surface and laser-polished surfaces as well as cross-section subsurfaces were analyzed carefully by White-Light Interference, Confocal Microscope, Focus Ion Beam, Scanning Electron Microscopy, Energy Dispersive Spectrometer, and X-ray Diffraction. Results revealed that as-received Ti-based alloys with surface roughness more than 5 μm could be reduce to less than 1 μm through laser polishing process. Moreover, microstructure, microhardness and wear resistance of laser-polished zone was investigated in order to examine the thermal effect of laser polishing processing on the substrate of additive manufactured Ti alloys. This proof-of-concept process has the potential to effectively improve the surface roughness of additive manufactured metallic alloy by local polishing method without damage to the substrate.

  2. Control of Porosity and Spatter in Laser Welding of Thick AlMg5 Parts Using High-Speed Imaging and Optical Microscopy

    Directory of Open Access Journals (Sweden)

    Andrei C. Popescu

    2017-10-01

    Full Text Available We report on a feedback mechanism for rapid identification of optimal laser parameters during welding of AlMg5 coupons using real-time monitoring by high-speed imaging. The purpose was to constrain the liquid movement in the groove in order to obtain pore-free welds in this otherwise difficult-to-weld alloy. High-speed imaging of the welding process via an optical microscope allowed for recording at millimeter level, providing new information on liquid-metal dynamics during laser irradiation as well as plausible explanations for spatter occurrence and pores formation. The pore formation and especially the position of these pores had to be controlled in order to weld 3 mm thick samples. By tuning both laser power and pulse duration, pores were aligned on a single line, at the bottom of the weld. A laser pass of reduced power on that side was then sufficient for removing all pores and providing a suitable weld.

  3. Microstructure and pitting corrosion of armor grade AA7075 aluminum alloy friction stir weld nugget zone – Effect of post weld heat treatment and addition of boron carbide

    Directory of Open Access Journals (Sweden)

    P. Vijaya Kumar

    2015-06-01

    Full Text Available Friction stir welding (FSW of high strength aluminum alloys has been emerged as an alternative joining technique to avoid the problems during fusion welding. In recent times FSW is being used for armor grade AA7075 aluminum alloy in defense, aerospace and marine applications where it has to serve in non uniform loading and corrosive environments. Even though friction stir welds of AA7075 alloy possess better mechanical properties but suffer from poor corrosion resistance. The present work involves use of retrogression and reaging (RRA post weld heat treatment to improve the corrosion resistance of welded joints of aluminum alloys. An attempt also has been made to change the chemical composition of the weld nugget by adding B4C nano particles with the aid of the FSW on a specially prepared base metal plate in butt position. The effects of peak aged condition (T6, RRA and addition of B4C nano particles on microstructure, hardness and pitting corrosion of nugget zone of the friction stir welds of AA7075 alloy have been studied. Even though RRA improved the pitting corrosion resistance, its hardness was slightly lost. Significant improvement in pitting corrosion resistance was achieved with addition of boron carbide powder and post weld heat treatment of RRA.

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

    Science.gov (United States)

    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.

  5. 75 FR 44763 - Certain Circular Welded Non-Alloy Steel Pipe From Mexico; Extension of Time Limit for Preliminary...

    Science.gov (United States)

    2010-07-29

    ... welded non- alloy steel pipe from Mexico. We also received review requests on November 30, 2009, from companies Tuberia Nacional, S.A. de C.V.'s (TUNA), Mueller Comercial de Mexico, S. de R.L. de C.V. (Mueller... International Trade Administration Certain Circular Welded Non-Alloy Steel Pipe From Mexico; Extension of Time...

  6. Influences of Laser Spot Welding on Magnetic Property of a Sintered NdFeB Magnet

    Directory of Open Access Journals (Sweden)

    Baohua Chang

    2016-08-01

    Full Text Available Laser welding has been considered as a promising method to join sintered NdFeB permanent magnets thanks to its high precision and productivity. However, the influences of laser welding on the magnetic property of NdFeB are still not clear. In the present paper, the effects of laser power on the remanence (Br were experimentally investigated in laser spot welding of a NdFeB magnet (N48H. Results show that the Br decreased with the increase of laser power. For the same welding parameters, the Br of magnets, that were magnetized before welding, were much lower than that of magnets that were magnetized after welding. The decrease in Br of magnets after laser welding resulted from the changes in microstructures and, in turn, the deterioration of magnetic properties in the nugget and the heat affected zone (HAZ in a laser weld. It is recommended that the dimensions of nuggets and HAZ in laser welds of a NdFeB permanent magnet should be as small as possible, and the magnets should be welded before being magnetized in order to achieve a better magnetic performance in practical engineering applications.

  7. Non-destructive Magnetic Evaluation of Laser Weld Quality in Hot Rolled Coils

    Science.gov (United States)

    Mohapatra, J. N.; Chakradhar, I.; Rao, K. R. C.; Rao, V. V. L.; Kaza, Marutiram

    2015-06-01

    Weld quality evaluation was conducted on laser welded thin sectsions (2 mm) of hot-rolled (HR) low-carbon steel coils during cold rolling process. The analysis revealed that the poor welds consisting of the weld defects like incomplete fusion, cluster of porosity, and large difference in hardness between the weld zone and base metal were responsible for the weld failures. Experiments were conducted by varying the welding parameters; laser power and welding speed to optimize the parameters for minimizing the weld defects. The optimized weld process parameters have helped elimination of weld defects and the results are verified with microscopy and microhardness measurements. As destructive evaluation techniques are time consuming and not always permitted in industrial applications, attempts have been made in the present investigation for the utilization of suitable non-destructive techniques for the evaluation of weld quality. Non-destructive magnetic techniques of magnetic hysteresis loop and magnetic Barkhausen emissions were used in the present investigation to establish possible correlations of magnetic properties across the weld seam with the mechanical property (microhardness) for evaluation of weld quality. It is inferred that the magnetic properties of coercivity and inverse of root mean square voltage can be effectively utilized to determine weld quality in HR steel coils.

  8. Effect of microstructure on properties of friction stir welded Inconel Alloy 600

    International Nuclear Information System (INIS)

    Sato, Y.S.; Arkom, P.; Kokawa, H.; Nelson, T.W.; Steel, R.J.

    2008-01-01

    Friction stir welding (FSW) has been widely used to metals with moderate melting temperatures, primarily Al alloys. Recently, tool materials that withstand high stresses and temperatures necessary for FSW of materials with high melting temperatures have been developed. In the present study, polycrystalline cubic boron nitride (PCBN) tool was used for partially penetrated FSW of Inconel Alloy 600, and a defect-free weld was successfully produced. Microstructural characteristics, mechanical and corrosion properties in the weld were examined. The weld had better mechanical properties than the base material due to formation of fine grain structure in the stir zone, but exhibited slightly the lower corrosion resistance in a part of the stir zone and heat-affected zone (HAZ)

  9. Control of surface defects on plasma-MIG hybrid welds in cryogenic aluminum alloys

    Directory of Open Access Journals (Sweden)

    Hee-Keun Lee

    2015-07-01

    Full Text Available 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.

  10. Microstructure and Mechanical Properties of Laser Welded Joints of DZ125L and IN718 Nickel Base Superalloys

    Science.gov (United States)

    Liang, Taosha; Wang, Lei; Liu, Yang; Song, Xiu

    2018-03-01

    The microstructure and mechanical properties of the laser welded joint of DZ125L and IN718 nickel base superalloys were investigated. The results show that the fusion zone (FZ) mainly consists of fine dendrite structure with fine γ', Laves phases and MC carbides inhomogeneously distributed. The high welding temperature induces the partial dissolution of γ' in the heat-affected zone (HAZ) of DZ125L and liquation of grain boundaries in both of the HAZs. After post-weld heat treatment (PWHT), fine γ″ and γ' phases precipitate in the FZ, IN718 HAZ and IN718 base metal (BM), and fine γ' precipitate in the γ channel of the HAZ and BM of DZ125L. With tensile testing, the joints after PWHT show higher strengths than that of the weaker DZ125L alloy. Plastic deformation mainly concentrates in the weaker DZ125L and the joint finally fails in the DZ125L BM.

  11. Investigation on Microstructure and Mechanical Properties of Continuous and Pulsed Current Gas Tungsten Arc Welded alloy 600

    Science.gov (United States)

    Srikanth, A.; Manikandan, M.

    2018-02-01

    The present study investigates the microstructure and mechanical properties of joints fabricated by Continuous and pulsed current gas tungsten arc welded alloy 600. Welding was done by autogenous mode. The macro examination was carried out to evaluate the welding defects in the weld joints. Optical and Scanning Electron Microscope (SEM) were performed to assess the microstructural changes in the fusion zone. Energy Dispersive Spectroscopy (EDS) analysis was carried to evaluate the microsegregation of alloying elements in the fusion zone. The tensile test was conducted to assess the strength of the weld joints. The results show that no welding defects were observed in the fusion zones of Continuous and Pulsed current Gas Tungsten Arc Welding. The refined microstructure was found in the pulsed current compared to continuous current mode. Microsegregation was not noticed in the weld grain boundary of continuous and pulsed current mode. The pulsed current shows improved mechanical properties compared to the continuous current mode.

  12. Welding of Nb micro-alloyed steel by the submerged arc process using Brazilian consumables

    International Nuclear Information System (INIS)

    Scotti, A.; Quites, A.M.

    1982-01-01

    A set of procedures was established for welding of Nb micro-alloyed steel by the submerged arc process, using national consumables, in order to simultaneously achieve a more economic welding and better mechanical properties. From all the wire-flux combinations the better were the correspondent to AWS F84ED1, F74EM12K and F84EH14, the last being the best. (Author) [pt

  13. The Optimization of Process Parameters and Microstructural Characterization of Fiber Laser Welded Dissimilar HSLA and MART Steel Joints

    Directory of Open Access Journals (Sweden)

    Celalettin Yuce

    2016-10-01

    Full Text Available Nowadays, environmental impact, safety and fuel efficiency are fundamental issues for the automotive industry. These objectives are met by using a combination of different types of steels in the auto bodies. Therefore, it is important to have an understanding of how dissimilar materials behave when they are welded. This paper presents the process parameters’ optimization procedure of fiber laser welded dissimilar high strength low alloy (HSLA and martensitic steel (MART steel using a Taguchi approach. The influence of laser power, welding speed and focal position on the mechanical and microstructural properties of the joints was determined. The optimum parameters for the maximum tensile load-minimum heat input were predicted, and the individual significance of parameters on the response was evaluated by ANOVA results. The optimum levels of the process parameters were defined. Furthermore, microstructural examination and microhardness measurements of the selected welds were conducted. The samples of the dissimilar joints showed a remarkable microstructural change from nearly fully martensitic in the weld bead to the unchanged microstructure in the base metals. The heat affected zone (HAZ region of joints was divided into five subzones. The fusion zone resulted in an important hardness increase, but the formation of a soft zone in the HAZ region.

  14. Comparison of Plasma, Metal Inactive Gas (MIG) and Tungsten Inactive Gas (TIG) Processes for Laser Hybrid Welding (302)

    DEFF Research Database (Denmark)

    Bagger, Claus; Olsen, Flemming Ove

    2003-01-01

    source, ignition and running torch stability, weld phase transformation and change in ductility and overall weld quality are described. The results show that all three processes can successfully be integrated with a CO2 laser beam for hybrid welding. Due to the pilot arc in plasma welding, this process......, the MIG process is more difficult to control than laser/plasma and laser/TIG processes. All three types of secondary heat sources enable an increased ductility of the weld as compared to pure laser welding when welding 1.8 mm GA 260 with a TIG torch and 2.13 mm CMn steel with a plasma arc or MIG...

  15. Fatigue and creep crack growth behaviour at high temperatures for weld metals of Alloy 800 and Alloy 617

    International Nuclear Information System (INIS)

    Roedig, M.; Choudhary, B.K.

    1993-01-01

    High temperature fatigue crack growth (FCG) and creep crack growth (CCG) experiments have been conducted in air on weld metal, heat affected zone (HAZ) and base metal of the austenitic Alloy 800 and the nickel base Alloy 617. Tests were performed on specimens machined from pipes, in the temperature range 550-900 deg. C. The crack propagation mode was examined. At all temperatures and for both materials, FCG of base metal was found to be the highest, whereas the weld metal exhibited the lowest FCG rate. The FCG rate in the HAZ was found to lie in between of those observed for base and weld metal. The crack propagation mode remained transgranular in base metal and transdendritic in weld metal at all temperatures. CCG behaviour could be described using the energy rate integral C*. Base metal and weld metal exhibited similar CCG rate at same C*. The crack propagation mode under CCG condition was found to be intergranular in base metal and HAZ and interdendritic in the weld metal. (author)

  16. Welding Residual Stress Analysis and Fatigue Strength Assessment at Elevated Temperature for Multi-pass Dissimilar Material Weld Between Alloy 617 and P92 Steel

    Science.gov (United States)

    Lee, Juhwa; Hwang, Jeongho; Bae, Dongho

    2018-03-01

    In this paper, welding residual stress analysis and fatigue strength assessment were performed at elevated temperature for multi-pass dissimilar material weld between Alloy 617 and P92 steel, which are used in thermal power plant. Multi-pass welding between Alloy 617 and P92 steel was performed under optimized welding condition determined from repeated pre-test welding. In particular, for improving dissimilar material weld-ability, the buttering welding technique was applied on the P92 steel side before multi-pass welding. Welding residual stress distribution at the dissimilar material weld joint was numerically analyzed by using the finite element method, and compared with experimental results which were obtained by the hole-drilling method. Additionally, fatigue strength of dissimilar material weld joint was assessed at the room temperature (R.T), 300, 500, and 700 °C. In finite element analysis results, numerical peak values; longitudinal (410 MPa), transverse (345 MPa) were higher than those of experiments; longitudinal (298 MPa), transverse (245 MPa). There are quantitatively big differences between numerical and experimental results, due to some assumption about the thermal conductivity, specific heat, effects of enforced convection of the molten pool, dilution, and volume change during phase transformation caused by actual shield gas. The low fatigue limit at R.T, 300 °C, 500 °C and 700 °C was assessed to be 368, 276, 173 and 137 MPa respectively.

  17. Microstructures and mechanical properties of magnesium alloy and stainless steel weld-joint made by friction stir lap welding

    International Nuclear Information System (INIS)

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

    2012-01-01

    Highlights: → Friction stir lap welding technology with cutting pin was successfully employed to form lap joint of magnesium and steel. → The cutting pin made the lower steel participate in deformation and the interface was no longer flat. → A saw-toothed structure formed due to a mechanical mixing of the magnesium and steel was found at the interface. → A high-strength joint was produced which fractured in the magnesium side. -- Abstract: Friction stir lap welding was conducted on soft/hard metals. A welding tool was designed with a cutting pin of rotary burr made of tungsten carbide, which makes the stirring pin possible to penetrate and cut the surface layer of the hard metal. Magnesium alloy AZ31 and stainless steel SUS302 were chosen as soft/hard base metals. The structures of the joining interface were analyzed by scanning electron microscopy (SEM). The joining strength was evaluated by tensile shear test. The results showed that flower-like interfacial morphologies were presented with steel flashes and scraps, which formed bonding mechanisms of nail effect by long steel flashes, zipper effect by saw-tooth structure and metallurgical bonding. The shear strength of the lap joint falls around the shear strength of butt joint of friction stir welded magnesium alloy.

  18. Diffusion Bonding and Post-Weld Heat Treatment of Extruded AZ91 Magnesium Alloys

    Directory of Open Access Journals (Sweden)

    Fei LIN

    2015-11-01

    Full Text Available The grain size of as-extruded AZ91 magnesium alloys was refined to 12.31 μm from 21.41 μm by recrystallization annealing. The vacuum diffusion welding of as-annealed AZ91 magnesium alloys was researched. The results showed that the maximum shear strength of joints reached 64.70 MPa in the situation of 10 MPa bonding pressure, 18 Pa vacuum degree, 470 °C bonding temperature and 90 min bonding time; both bonding temperature and time are the main influence factors on as-extruded AZ91 magnesium alloys diffusion welding. Then the diffusion welded specimens were annealed, and the shear strength of joints was further improved to 76.93 MPa.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9699

  19. Grain structure and solidification cracking in oscillated arc welds of 5052 aluminum alloy

    Science.gov (United States)

    Kou, S.; Le, Y.

    1985-07-01

    The effect of arc oscillation on grain structure and solidification cracking in GTA welds of 5052 aluminum alloy was investigated using a four-pole magnetic arc oscillator and a modified fish-bone crack test. Two different mechanisms of crack reduction were identified: one in the low frequency range of arc oscillation and the other in the high frequency range. The former was the alteration of the orientation of columnar grains, while the latter was grain refining. Neither mechanism was operative in the intermediate frequency range and solidification cracking was severe, especially when the amplitude of arc oscillation was small. Alteration of grain orientation was obtained in welds made with transverse and circular arc oscillations, but not longitudinal arc oscillation. Grain refining, on the other hand, was achieved in welds made with all three types of arc oscillation patterns. The differences between the response of alloy 5052 to arc oscillation and that of alloy 2014 observed previously were discussed.

  20. Effects of Nd:YAG laser pulse frequency on the surface treatment of Ti 6Al 4V alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gursel, Ali [International University of Sarajevo (Bosnia and Herzegovina). Dept. of Mechanical Engineering

    2016-07-01

    The desirable properties of titanium and titanium alloys, including excellent corrosion resistance, high strength to weight ratio and high operating temperature, have led to their successful application in various fields such as the medical and aerospace industries. Among the reliable treatment techniques, laser welding can provide significant advantages for the titanium alloys because of its precision, rapid processing capability and ability to control the welding parameters and their effects. The morphology and the quality of pulsed seam welds are directly or synergistically influenced by the Nd:YAG laser parameters of pulse shape, energy, duration, travel speed, peak power and frequency of repetition. In this study, a 1.5 mm thick Ti-6Al-4V alloy sheet surface was treated by SigmaLaser {sup registered} 300 Nd:YAG pulsed laser. The influence of the pulse frequency on seam morphology and surface effects was then investigated. The seam and surface quality were characterized in terms of weld morphology and microhardness. The results showed that, for Nd:YAG laser seams used for surface treatment, pulse repetition was more effective on the cooling rate than had been expected.

  1. Hardening and welding with high-power diode lasers

    Science.gov (United States)

    Ehlers, Bodo; Herfurth, Hans-Joachim; Heinemann, Stefan

    2000-03-01

    Commercially available high power diode lasers (HPDLs) with output powers of up to 6 kW have been recognized as an interesting tool for industrial applications. In certain fields of application they offer many advantages over Nd:YAG and CO2 lasers because of their low maintenance, compact design and low capital costs. Examples of successful industrial implementation of HPDLs include plastic welding, surface hardening and heat conduction welding of stainless steel and aluminum. The joining of plastics with an HPDL offers the advantages of producing a weld seam with high strength, high consistency and superior appearance. One example is the keyless entry system introduced with the Mercedes E-class where the microelectronic circuits are embedded in a plastic housing. Other applications include instrument panels, cell phones, headlights and tail lights. Applications in the field of surface treatment of metals profit from the HPDL's inherent line-shaped focus and the homogeneous intensity distribution across this focus. An HPDL system is used within the industry to harden rails for coordinate measurement machines. This system contains a customized zoom optic to focus the laser light onto the rails. With the addition of a temperature control, even complex shapes can be hardened with a constant depth and minimum distortion.

  2. Material Characterization of Dissimilar Friction Stir Spot Welded Aluminium and Copper Alloy

    Science.gov (United States)

    Sanusi, K. O.; Akinlabi, E. T.

    2017-08-01

    In this research study, material characterization of dissimilar friction stir spot welded Aluminium and Copper was evaluated. Rotational speeds of 800 rpm and transverse speeds of 50 mm/min, 150 mm/min and 250 mm/min were used. The total numbers of samples evaluated were nine altogether. The spot welds were characterised by microstructure characterization using optical microscope (OEM) and scanning electron microscopy technique (SEM) by observing the evolution of the microstructure across the weld’s cross-section. lap-shear test of the of the spot weld specimens were also done. From the results, it shows that welding of metals and alloys using Friction stir spot welding is appropriate and can be use in industrial applications.

  3. Microstructure and mechanical characterization of friction stir welded high strength low alloy steels

    International Nuclear Information System (INIS)

    Ramesh, R.; Dinaharan, I.; Kumar, Ravi; Akinlabi, E.T.

    2017-01-01

    Friction stir welding (FSW) is a promising technique to join HSLA steels without the problems encountered during fusion based welding processes. In the present work, 3 mm thick HSLA plates were successfully welded using FSW. A tool made of tungsten-rhenium alloy was used in this work. The relationship between microstructure and tensile strength was studied under various welding conditions i.e. change in traverse speed (57–97 mm/min). The microstructure of the weld nugget revealed the presence of upper bainite and fine ferrite phases. The amount of upper bainite reduced with increase in traverse speed. EBSD images showed a reducing trend for grain size. The details of hardness, tensile strength and bending test were reported.

  4. Effect of linear energy on the properties of an AL alloy in DPMIG welding

    Science.gov (United States)

    Liao, Tianfa; Jin, Li; Xue, Jiaxiang

    2018-01-01

    The effect of different linear energy parameters on the DPMIG welding performance of AA1060 aluminium alloy is studied in this paper. The stability of the welding process is verified with a Labview electrical signal acquisition system, and the microstructure and tensile properties of the welded joint are studied via optical microscopy, scanning electron microscopy and electrical tensile tests. The test results show that the welding process for the DPMIG methods stable and that the weld beads appear as scales. Tensile strength results indicate that, with increasing linear energy, the tensile strength first increases and then decreases. The tensile strength of the joint is maximized when the linear energy is 120.5 J / mm-1.

  5. Mechanical evaluation of linear friction welds in titanium alloys through indentation experiments

    International Nuclear Information System (INIS)

    Corzo, M.; Casals, O.; Alcala, J.; Mateo, A.; Anglada, M.

    2005-01-01

    This article shows the results of a project that focuses on the characterization of the weld interface region of dissimilar joints between titanium alloys for aeronautical applications, specifically Ti-6Al-2Sn-4Zr-6Mo with Ti-6Al-4V, and Ti-6Al-2Sn-4Zr-6Mo with Ti-6Al-2Sn-4Zr-2Mo. The uniaxial flow stress and hardening response of the material containing the weld were analyzed following the finite elements simulations and mathematical formulations to correlate hardness and the amount of pile-up and sinking-in phenomena around sharp indenters with uniaxial mechanical properties. This allows to accurately stablishing the influence that welding process has on the mechanical response of the parts. Tests performed on these friction-welded specimens showed that the fine grained microstructures in the welds exhibited better properties than the base materials. (Author) 12 refs

  6. A simplified design of clamping system and fixtures for friction stir welding of aluminium alloys

    Directory of Open Access Journals (Sweden)

    Mohammed. M. Hasan

    2015-12-01

    Full Text Available Sound friction stir welds could be attained by using an active design of backing/clamping system with a proper selection of the welding parameters. This work presented a simplified design of fixtures and backing plates to be used for friction stir welding of aluminum alloys. The test-rig was constructed to prevent dispersal or lifting of the specimens throughout the joining process and to ensure uniform distribution of temperature along the plates. The workpieces were subjected to uniform lateral and vertical pressures by means of bolts and nuts. Compound backing plates and pressure bars with additional side plates were included to increase the heat sink. Several coupons of dissimilar aluminum alloys AA7075 and AA6061 were joined to inspect the validity of this design. The tests showed promising results with defects-free welds, good strength and smooth surface finish without geometric imperfection and gap creation between the welded specimens. Efficiency of the joint reached its maximum value of about 82% with respect to the ultimate strength of the AA6061 alloy at 1100 rpm rotation speed and 300 mm/min feed. These results encourage using and improving the present design for future studies of friction stir welding.

  7. Fatigue crack growth resistance of gas tungsten arc, electron beam and friction stir welded joints of AA2219 aluminium alloy

    International Nuclear Information System (INIS)

    Malarvizhi, S.; Balasubramanian, V.

    2011-01-01

    AA2219 aluminium alloy square butt joints without filler metal addition were fabricated using gas tungsten arc welding (GTAW), electron beam welding (EBW) and friction stir welding (FSW) processes. The effect of three welding processes on fatigue crack growth behaviour is reported in this paper. Transverse tensile properties of the welded joints were evaluated. Microstructure analysis was also carried out using optical and electron microscopes. It was found that the FSW joints are exhibiting superior fatigue crack growth resistance compared to EBW and GTAW joints. This was mainly due to the formation of very fine, dynamically recrystallised grains and uniform distribution of fine precipitates in the weld region.

  8. Numerical analysis of laser welding with consideration analytical methods of determining phase transformations and mechanical properties of welded joint

    Directory of Open Access Journals (Sweden)

    Piekarska Wiesława

    2018-01-01

    Full Text Available The numerical analysis of laser welding process with consideration analytical methods determining phase transformations and mechanical properties of welded joints are presents in this paper. The analytical CCT diagram and final structural composition of S355 steel are presented. The empirical relations presents in paper are determined by chemical compositions investigated steel and cooling rate between temperatures 800-500°C (t8/5. Phase composition and mechanical properties each of structures of steel in weld and heat affected zone (HAZ are determined on the basis of analytical methods. Laser welded flat is used in numerical simulations in ABAQUS. Mathematical modes of volumetric welding source are used in the calculations. Temperature fields, shape and size of melting zone for selected points in the cross-section of the joint are determined on the basis of thermal cycles obtained numerical.

  9. Development of automatic pre-tracking system for fillet weld based on laser trigonometry

    Science.gov (United States)

    Shen, Xiaoqin; Yu, Fusheng

    2005-01-01

    In this paper, an automatic fillet weld pre-tracking system for welding the work piece of lorry back boards with several bend in haul automobile is developed basing on laser trigonometry. The optical measuring head based on laser-PSD trigonometry is used as position sensor. It is placed in front of the traveling direction of welding wire to get the distances from welding wire to the two side boards of the welding lines, upper board and bottom board of the fillet weld respectively. A chip of AT89S52 is used as the micro controller in this system. The AC servomotors, ball-screws and straight guide rails constitute the sliding table to take welding wire move. The laser-PSD sensors pass through the vertical board, upper board and bottom board of the fillet weld when welding wire moves and then get the distance. The laser-PSD sensors output the analog signals. After A/D conversion, the digital signal is input into AT89S52 and calculated. Then the information of the position and lateral deviation of the welding wire when welding a certain position are gotten to control welding wires. So the weld pre-tracking for welding the work piece with long distance and large bend in haul automobile is realized. The position information is input into EEPROM to be saved for short time after handled by AT89S52. The information is as the welding position information as well as the speed adjusting data of the welding wire when it welds the several bend of the work piece. The practice indicates that this system has high pre-tracking precision, good anti-disturb ability, excellent reliability, easy operating ability and good adaptability to the field of production.

  10. The effects of dynamic load on behaviour of welded joint A-387 Gr. 11 alloyed steel

    Directory of Open Access Journals (Sweden)

    O. Popović

    2013-01-01

    Full Text Available The in-service behaviour of alloyed steel A-387 Gr. 11 Class 1, for pressure vessels, used for high temperature applications, depends on the properties of its welded joint, with parent metal (BM, heat-affected-zone (HAZ and weld metal (WM, as constituents. Charpy testing of BM, WM and HAZ, together with, determination of the parameters of fatigue-crack growth and fatigue threshold ΔKth was used, in order to understand, how heterogeneity of structure and different mechanical properties of welded joint constituents affect on crack initiation and propagation.

  11. Structural Phase Evolution in Ultrasonic-Assisted Friction Stir Welded 2195 Aluminum Alloy Joints

    Science.gov (United States)

    Eliseev, A. A.; Fortuna, S. V.; Kalashnikova, T. A.; Chumaevskii, A. V.; Kolubaev, E. A.

    2017-10-01

    The authors examined the structural and phase state of fixed joints produced by method of friction stir welding (FSW) and ultrasonic-assisted friction stir welding (UAFSW) from extruded profile of aluminum alloy AA2195. In order to identify the role of ultrasonic application in the course of welding, such characteristics, as volume fraction and average size of secondary particles are compared in the base material and stir zones of FSW and UAFSW joints. By applying the methods of SEM and TEM analysis, researchers established the complex character of phase transitions as a result of ultrasonic application.

  12. Microstructure and microtexture studies of a friction stir welded Al 6061 alloy

    International Nuclear Information System (INIS)

    Kumbhar, N.T.; Tewari, R.; Dey, G.K.; Bhanumurthy, K.; Sahoo, S.K.; Samajdar, I.

    2009-01-01

    Friction stir welding is a solid state joining technique used extensively for the joining of various metals and alloys and also has been applied to the joining of steels. The friction stir welding of Al and its alloys has been extensively delt with over a period exceeding the last decade and a half due to its numerous advantages over other conventional fusion welding techniques in terms of weld quality, efficiency, cost effectiveness etc. to name a few. This technique is being increasingly seeked by industries in mass production/engineering such as the railways, marine and aerospace industries. The friction stir welding of a precipitation hardened Al 6061 alloy plates of 6 mm. thickness was performed at various tool rotation speeds and tool traverse speeds with a constant tilt of 3 deg using a high strength steel (HSS) tool of appropriate dimensions. The cross section of the weld perpendicular to the welding direction was analyzed for a detailed microstructural investigation using electron probe microanalysis, orientation imaging microscopy and transmission electron microscopy. Various microstructural changes are observed in the various regions of the friction stir welded AA 6061. The nugget region which is highly deformed is characterized by the dissolution and reprecipitation of the coarse precipitates, grain size refinement and recrystallization. The adjoining regions near the nugget viz the thermomechanically affected zone (TMAZ) and the heat affected zone (HAZ) also show heterogeneous microstructure in terms of grain size and precipitation which is mainly attributed to the heating cycle experienced during welding. This heterogeneity is also evident from the plot of microhardness distribution across the cross section of the weld region. However, the electron probe microanalysis studies do not show any significant pickup of oxygen in the weld interior as compared to a little oxygen pickup upto 30 μm from the top surface. Further, using orientation imaging

  13. Inertia and friction welding of aluminum alloy 1100 to type 316 stainless steel

    International Nuclear Information System (INIS)

    Perkins, M.A.

    1979-01-01

    The inertia and friction-welding processes were evaluated for joining aluminum alloy 1100-H14 and Type 316 vacuum-induction melted, vacuum-arc remelted (VIM VAR) stainless steel. While both processes consistently produced joints in which the strength exceeded the strength of the aluminum base metal, 100 percent bonding was not reliably achieved with inertia welding. The deficiency points out the need for development of nondestructive testing techniques for this type of joint. Additionally, solid-state volume diffusion did not appear to be a satisfactory explanation for the inertia and friction-welding bonding mechanism

  14. Microstructure and Salt Fog Corrosion Behavior of AA2219 Friction-Stir-Welded Aluminum Alloy

    Science.gov (United States)

    Srinivasa Rao, G.; Subba Rao, V. V.; Rao, S. R. K.

    2017-07-01

    Plates (8.1-mm-thick) from aluminum alloy AA2219-T87 are studied after friction stir welding. The plates are subjected to salt fog corrosion tests according to ASTM B117 at different pH values and different spraying times. The regions affected by corrosion are studied in different zones of welded joints by the methods of optical and transmission electron microscopy. The corrosion resistance is determined in acid, basic and neutral solutions. The resistances of the base metal and of the zones of welded joints are compared.

  15. Single-pulse Conduction Limited Laser Welding Using A Diffractive Optical Element

    Science.gov (United States)

    Kong, C. Y.; Bolut, M.; Sundqvist, J.; Kaplan, A. F. H.; Assunção, E.; Quintino, L.; Blackburn, J.

    Conduction limited laser welding is commonly used in electronic and battery applications, where a high width-to-depth ratio weld is desirable. A laser beam with Gaussian or top-hat distributions is often used to produce conduction limited spot welds. Both these energy distributions result in a higher proportion of the laser beam energy being introduced towards the centre of the welded spot and consequently, a reduced penetration weld towards the circumference of the beam spot. The use of diffractive optical elements to tailor the energy distribution of the laser beam has been evaluated. An incident laser beam with an energy distribution in the shape of a ring or C-shape was projected onto the material, which results in heat propagating towards the centre, producing a shallow weld with a consistent depth of penetration across the entire overlapped joint. The results confirmed a corresponding thermal model which predicted an even distribution of heat at the joint interface.

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

    Science.gov (United States)

    Zadpoor, Amir Abbas; Sinke, Jos

    2011-01-01

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

  17. Friction stir welding (FSW process of copper alloys

    Directory of Open Access Journals (Sweden)

    M. Miličić

    2016-01-01

    Full Text Available The present paper analyzes the structure of the weld joint of technically pure copper, which is realized using friction stir welding (FSW. The mechanism of thermo-mechanical processes of the FSW method has been identified and a correlation between the weld zone and its microstructure established. Parameters of the FSW welding technology influencing the zone of the seam material and the mechanical properties of the resulting joint were analyzed. The physical joining consists of intense mixing the base material along the joint line in the “doughy” phase. Substantial plastic deformations immediately beneath the frontal surface of tool provide fine-grained structure and a good quality joint. The optimum shape of the tool and the optimum welding regime (pressure force, rotation speed and the traverse speed of the tool in the heat affected zone enable the achievement of the same mechanical properties as those of the basic material, which justifies its use in welding reliable structures.

  18. Keyhole depth instability in case of CW CO2 laser beam welding of ...

    Indian Academy of Sciences (India)

    gives rise to irregular humps. Keywords. Ambient and under water welding; keyhole collapse; weld depth instabilities; humps. 1. Introduction. The high-power CO2 laser sources with Gaussian beam distribution are currently used for welding of thick stainless steels (Binda et al 2004). In the case of LBW, heat and fluid flow.

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

    Science.gov (United States)

    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.

  20. Application of lap laser welding technology on stainless steel railway vehicles

    Science.gov (United States)

    Wang, Hongxiao; Wang, Chunsheng; He, Guangzhong; Li, Wei; Liu, Liguo

    2016-10-01

    Stainless steel railway vehicles with so many advantages, such as lightweight, antirust, low cost of maintenance and simple manufacturing process, so the production of high level stainless steel railway vehicles has become the development strategy of European, American and other developed nations. The current stainless steel railway vehicles body and structure are usually assembled by resistance spot welding process. The weak points of this process are the poor surface quality and bad airtight due to the pressure of electrodes. In this study, the partial penetration lap laser welding process was investigated to resolve the problems, by controlling the laser to stop at the second plate in the appropriate penetration. The lap laser welding joint of stainless steel railway vehicle car body with partial penetration has higher strength and surface quality than those of resistance spot welding joint. The biggest problem of lap laser welding technology is to find the balance of the strength and surface quality with different penetrations. The mechanism of overlap laser welding of stainless steel, mechanical tests, microstructure analysis, the optimization of welding parameters, analysis of fatigue performance, the design of laser welding stainless steel railway vehicles structure and the development of non-destructive testing technology were systematically studied before lap laser welding process to be applied in manufacture of railway vehicles. The results of the experiments and study show that high-quality surface state and higher fatigue strength can be achieved by the partial penetration overlap laser welding of the side panel structure, and the structure strength of the car body can be higher than the requirements of En12663, the standard of structural requirements of railway vehicles bodies. Our company has produced the stainless steel subway and high way railway vehicles by using overlap laser welding technology. The application of lap laser welding will be a big

  1. Monitoring and Control of the Hybrid Laser-Gas Metal-Arc Welding Process

    Energy Technology Data Exchange (ETDEWEB)

    Kunerth, D. C.; McJunkin, T. R.; Nichol, C. I.; Clark, D.; Todorov, E.; Couch, R. D.; Yu, F.

    2013-07-01

    Methods are currently being developed towards a more robust system real time feedback in the high throughput process combining laser welding with gas metal arc welding. A combination of ultrasonic, eddy current, electronic monitoring, and visual techniques are being applied to the welding process. Initial simulation and bench top evaluation of proposed real time techniques on weld samples are presented along with the concepts to apply the techniques concurrently to the weld process. Consideration for the eventual code acceptance of the methods and system are also being researched as a component of this project. The goal is to detect defects or precursors to defects and correct when possible during the weld process.

  2. Assessment of the effects of heat input on microstructure and mechanical properties in laser beam welded Haynes 188 undermatched joints

    Energy Technology Data Exchange (ETDEWEB)

    Odabas Latin-Small-Letter-Dotless-I , A., E-mail: odabasia@firat.edu.tr [F Latin-Small-Letter-Dotless-I rat University, Faculty of Engineering, Department of Metallurgical and Materials Engineering, 23119 Elaz Latin-Small-Letter-Dotless-I g (Turkey); Uenlue, N.; Goeller, G.; Kayal Latin-Small-Letter-Dotless-I , E.S.; Eruslu, M.N. [Istanbul Technical University, Faculty of Chemical and Metallurgical Engineering, Department of Metallurgical and Materials Engineering, 34469 Maslak, Istanbul (Turkey)

    2013-01-01

    CO{sub 2} laser butt-welding of Co-base superalloy Haynes 188 was performed on 2.1 mm-thick sheets with an average grain size of 21 {mu}m (ASTM no. 8). Nine different heat inputs in the range of 61.3-90.1 J mm{sup -1} were used. The corresponding solidification rates at the weld fusion zone were in the range of 2 Multiplication-Sign 10{sup 3} to 1 Multiplication-Sign 10{sup 4} Degree-Sign C s{sup -1}. The distribution coefficients for the alloying elements in the laser beam welded samples were close to unity. The yield and tensile strengths, the strain hardening exponents, and the strength mismatch ratios decreased with increasing heat input. The corresponding joint efficiencies of the high and low heat input trials were 84% and 93%, respectively. Fractography analysis of the base material and laser beam welded sheets revealed dimple-like ductile fracture characteristics.

  3. Laser Welding Of Stainless Steel By Means Of "Flat-Top" Energy Distribution Beam

    Science.gov (United States)

    Dionoro, G.; Minutolo, F. Memola C.; Tagliaferri, V.

    1989-06-01

    Laser welding of stainless steel AISI 304 and AISI 405 is investigated. Laser source with "flat-top" energy distribution is employed which produces welded joints with similar geometry to other conventional welding techniques. Mechanical properties of the welds are however very similar to those typical of deep penetration processes. Microhardness and bend tests as well as micrograph examinations have been carried out on the welds. The test pieces exhibited good mechanical strength and in particular acceptable ductility. Theoretical considerations based on widely accepted thermal models have also confirmed that the process proceeds at high efficiency energy transfer.

  4. Numerical estimation of temperature field in a laser welded butt joint made of dissimilar materials

    Directory of Open Access Journals (Sweden)

    Saternus Zbigniew

    2018-01-01

    Full Text Available The paper concerns numerical analysis of thermal phenomena occurring in the butt welding of two different materials by a laser beam welding. The temperature distribution for the welded butt-joint is obtained on the basis of numerical simulations performed in the ABAQUS program. Numerical analysis takes into account the thermophysical properties of welded plate made of two different materials. Temperature distribution in analysed joints is obtained on the basis of numerical simulation in Abaqus/Standard solver, which allowed the determination of the geometry of laser welded butt-joint.

  5. Aluminum alloy nanosecond vs femtosecond laser marking

    Indian Academy of Sciences (India)

    Based on the lack of consistent literature publications that analyse the effects of laser marking for traceability on various materials, the present paper proposes a study of the influence of such radiation processing on an aluminum alloy, a vastly used material base within several industry fields. For the novelty impact, ...

  6. Aluminum alloy nanosecond vs femtosecond laser marking

    Indian Academy of Sciences (India)

    Abstract. Based on the lack of consistent literature publications that analyse the effects of laser marking for trace- ability on various materials, the present paper proposes a study of the influence of such radiation processing on an aluminum alloy, a vastly used material base within several industry fields. For the novelty ...

  7. Two-dimensional modeling of conduction-mode laser welding

    International Nuclear Information System (INIS)

    Russo, A.J.

    1984-01-01

    WELD2D is a two-dimensional finite difference computer program suitable for modeling the conduction-mode welding process when the molten weld pool motion can be neglected. The code is currently structured to treat butt-welded geometries in a plane normal to the beam motion so that dissimilar materials may be considered. The surface heat transfer models used in the code include a Gaussian beam or uniform laser source, and a free electron theory reflectance calculation. Temperature-dependent material parameters are used in the reflectance calculation. Measured cold reflection data are used to include surface roughness or oxide effects until melt occurs, after which the surface is assumed to be smooth and clean. Blackbody reradiation and a simple natural convection model are also included in the upper surface boundary condition. Either an implicit or explicit finite-difference representation of the heat conduction equation in an enthalpy form is solved at each time step. This enables phase transition energies to be easily and accurately incorporated into the formulation. Temperature-dependent 9second-order polynominal dependence) thermal conductivities are used in the conduction calculations. Constant values of specific heat are used for each material phase. At present, material properties for six metals are included in the code. These are: aluminium, nickel, steel, molybdenum, copper and silicon

  8. Microstructure Stability During Creep of Friction Stir Welded AA2024-T3 Alloy

    Science.gov (United States)

    Regev, Michael; Rashkovsky, Tal; Cabibbo, Marcello; Spigarelli, Stefano

    2018-01-01

    The poor weldability of the AA2024 aluminum alloy limits its use in industrial applications. Because friction stir welding (FSW) is a non-fusion welding process, it seems to be a promising solution for welding this alloy. In the current study, FSW was applied to butt weld AA2024-T3 aluminum alloy plates. Creep tests were conducted at 250 and at 315 °C on both the parent material and the friction stir welded specimens. The microstructures of the welded and non-welded AA2024-T3 specimens before and after the creep tests were studied and compared. A comprehensive transmission electron microscopy study together with a high-resolution scanning electron microscopy study and energy-dispersive x-ray spectroscopy analysis was conducted to investigate the microstructure stability. The parent material seems to contain two kinds of Cu-rich precipitates—coarse precipitates of a few microns each and uniformly dispersed fine nanosized precipitates. Unlike the parent material, the crept specimens were found to contain the two kinds of precipitates mentioned above together with platelet-like precipitates. In addition, extensive decoration of the grain boundaries with precipitates was clearly observed in the crept specimens. Controlled aging experiments for up to 280 h at the relevant temperatures were conducted on both the parent material and the welded specimens in order to isolate the contribution of exposure to high temperatures to the microstructure changes. TEM study showed the development of dislocation networks into a cellular dislocation structure in the case of the parent metal. Changes in the dislocation structure as a function of the creep strain and the FSW process were recorded. A detailed creep data analysis was conducted, taking into account the instability of the microstructure.

  9. Experience of Application of EBW in Producing Welded VT41 Alloy Drums in the Design of an HPC in an Advanced Engine

    Science.gov (United States)

    Bykov, Yu. G.; Fomichev, E. O.; Kashapov, O. S.; Kyaramyan, K. A.

    2017-12-01

    The conditions of electron-beam welding (EBW) of ring samples made of a VT41 alloy are adjusted to produce large welded joints of this alloy for a high-pressure compressor (HPC) of an advanced engine. The problems of quality control of a welded joint, the level of residual stresses in the near-weld zone, the microstructure of the welded joint, and its properties are considered.

  10. Investigation of Microstructure in Solid State Welded Al-Cu-Li alloy

    Directory of Open Access Journals (Sweden)

    No Kookil

    2016-01-01

    Full Text Available Al-Li alloys have been extensively used in aerospace vehicle structure since the presence of lithium increases the modulus and reduce the density of the alloy. Especially the third generation Al-Cu-Li alloy shows enhanced fracture toughness at cryogenic temperatures so that the alloy has been used on the fuel tank of space launchers, like Super Lightweight External Tank of the Space Shuttle. Since the commercial size of the plate cannot accommodate the large tank size of the launcher, joining several pieces is required. However, lithium is highly reactive and its compounds can decompose with heat from conventional fusion welding and form different types of gases which result in formation of defects. In this study, the microstructure change is investigated after solid state welding process to join the Al-Cu-Li sheets with optical and transmission electron microscopic analysis of precipitates.

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

    Science.gov (United States)

    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.

  12. Low Cycle Fatigue behavior of SMAW welded Alloy28 superaustenitic stainless steel at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Kchaou, Y., E-mail: yacinekchaou@yahoo.fr [Institut Pprime, Département Physique et Mécanique des Matériaux, UPR 3346 CNRS ISAE-ENSMA Université de Poitiers, Téléport 2, 1, avenue Clément Ader, BP 40109, F – 86961 Futuroscope Chasseneuil Cedex (France); Laboratoire de Génie des Matériaux et Environnement (LGME), ENIS, BPW 1173, Sfax (Tunisia); Pelosin, V.; Hénaff, G. [Institut Pprime, Département Physique et Mécanique des Matériaux, UPR 3346 CNRS ISAE-ENSMA Université de Poitiers, Téléport 2, 1, avenue Clément Ader, BP 40109, F – 86961 Futuroscope Chasseneuil Cedex (France); Haddar, N.; Elleuch, K. [Laboratoire de Génie des Matériaux et Environnement (LGME), ENIS, BPW 1173, Sfax (Tunisia)

    2016-01-10

    This paper focused on the study of Low Cycle Fatigue of welded joints of superaustenitic (Alloy28) stainless steels. Chemical composition and microstructure investigation of Base Metal (BM) and Weld Metal (WM) were identified. The results showed that both of composition is fully austenitic with a dendritic microstructure in the WM. Low cycle fatigue tests at different strain levels were performed on Base Metal (BM) and Welded Joint (WJ) specimens with a strain ratio R{sub ε}=−1. The results indicated that the fatigue life of welded joints is lower than the base metal. This is mainly due to the low ductility of the Welded Metal (WM) and the presence of welding defects. Simultaneously, Scanning Electron Microscope (SEM) observations of fractured specimens show that WJ have brittle behavior compared to BM with the presence of several welding defects especially in the crack initiation site. An estimation of the crack growth rate during LCF tests of BM and WJ was performed using distance between striations. The results showed that the crack initiation stage is shorter in the case of WJ compared to BM because of the presence of welding defects in WJ specimens.

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

    International Nuclear Information System (INIS)

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

    1996-01-01

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

  14. Electron-beam weld solidification structures and properties in Al-3Li-X alloys

    Energy Technology Data Exchange (ETDEWEB)

    Bowden, D.M.; Meschter, P.J.

    1984-09-01

    This paper examines the effects of various additions to binary Al-3Li on electron-beam weld solidification structures and tensile properties. These additions include Zr for grain refinement, Mg for solid solution strengthening, Cu for precipitation strengthening, and Co for dispersion strengthening. Aluminum-lithium alloys containing 3 wt% lithium are candidates to replace commercial 2xxx and 7xxx aluminum alloys in structural applications.

  15. Microstructural characterisation of friction stir welding joints of mild steel to Ni-based alloy 625

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, J. [Brazilian Nanotechnology National Laboratory (LNNano), P.O. Box 6192, Campinas, SP (Brazil); University of Campinas (UNICAMP), Campinas, SP (Brazil); Ramirez, A.J., E-mail: ramirezlondono.1@osu.edu [Brazilian Nanotechnology National Laboratory (LNNano), P.O. Box 6192, Campinas, SP (Brazil); University of Campinas (UNICAMP), Campinas, SP (Brazil); Department of Materials Science and Engineering, The Ohio State University — OSU, Columbus, OH 43221 (United States)

    2015-12-15

    In this study, 6-mm-thick mild steel and Ni-based alloy 625 plates were friction stir welded using a tool rotational speed of 300 rpm and a travel speed of 100 mm·min{sup −1}. A microstructural characterisation of the dissimilar butt joint was performed using optical microscopy, scanning and transmission electron microscopy, and energy dispersive X-ray spectroscopy (XEDS). Six different weld zones were found. In the steel, the heat-affected zone (HAZ) was divided into three zones and was composed of ferrite, pearlite colonies with different morphologies, degenerated regions of pearlite and allotriomorphic and Widmanstätten ferrite. The stir zone (SZ) of the steel showed a coarse microstructure consisting of allotriomorphic and Widmanstätten ferrite, degenerate pearlite and MA constituents. In the Ni-based alloy 625, the thermo-mechanically affected zone (TMAZ) showed deformed grains and redistribution of precipitates. In the SZ, the high deformation and temperature produced a recrystallised microstructure, as well as fracture and redistribution of MC precipitates. The M{sub 23}C{sub 6} precipitates, present in the base material, were also redistributed in the stir zone of the Ni-based alloy. TMAZ in the steel and HAZ in the Ni-based alloy could not be identified. The main restorative mechanisms were discontinuous dynamic recrystallisation in the steel, and discontinuous and continuous dynamic recrystallisation in the Ni-based alloy. The interface region between the steel and the Ni-based alloy showed a fcc microstructure with NbC carbides and an average length of 2.0 μm. - Highlights: • Comprehensive microstructural characterisation of dissimilar joints of mild steel to Ni-based alloy • Friction stir welding of joints of mild steel to Ni-based alloy 625 produces sound welds. • The interface region showed deformed and recrystallised fcc grains with NbC carbides and a length of 2.0 μm.

  16. Standard specification for wrought zirconium and zirconium alloy seamless and welded tubes for nuclear service

    International Nuclear Information System (INIS)

    Anon.

    1975-01-01

    Specifications are described for three grades of seamless and welded wrought zirconium and zirconium-alloy tubes for nuclear applications. These grades are designated as reactor grade zirconium R-1, and zirconium-tin alloys RA-1 and RA-2. Basis of purchase, manufacture, inspection, and packaging and marketing are specified. Chemical requirements and mechanical properties specifications are tabulated. Permissible variations in diameter, wall thickness, and ovality measured at any location on the tube are also tabulated

  17. Investigation of defect rate of lap laser welding of stainless steel railway vehicles car body

    Science.gov (United States)

    Wang, Hongxiao

    2015-02-01

    In order to resolve the disadvantages such as poor appearance quality, poor tightness, low efficiency of resistance spot welding of stainless steel rail vehicles, partial penetration lap laser welding process was investigated widely. But due to the limitation of processing technology, there will be local incomplete fusion in the lap laser welding seam. Defect rate is the ratio of the local incomplete fusion length to the weld seam length. The tensile shear strength under different defect rate and its effect on the car body static strength are not clear. It is necessary to find the biggest defect rate by numerical analysis of effects of different defect rates on the laser welding stainless steel rail vehicle body structure strength ,and tests of laser welding shear tensile strength.

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

    Science.gov (United States)

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

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

  19. Integrity and quality assessment applied on laser welded titanium components

    Directory of Open Access Journals (Sweden)

    Wirdelius Håkan

    2014-06-01

    Full Text Available Laser welding of thin titanium components, a critical component of many gas turbine engines, has demonstrated a tendency of generating pores in clusters with a prescribed orientation. These pores, also known as chain porosities, are often of harmless sizes (of 50–100 micrometer as individuals. Though the cluster as such, depending on the distances and orientations in between the pores, may have an impact on the structural integrity. A recently developed algorithm for 3-D positioning of small pore defects in planar geometries using digital X-ray inspection aims at providing 3-D positions of the defects. This could then be used in-line to assess the welding quality in the manufacturing process. This presentation describes the development of a methodology that aims to incorporate non-destructive evaluation with, in this case, structural integrity.

  20. Laser welding of polymers, compatibility and mechanical properties

    DEFF Research Database (Denmark)

    Nielsen, Steen Erik; Strange, Marianne; Kristensen, Jens Klæstrup

    2013-01-01

    with the development of related absorbers added to the polymer materials provide the possibility of joining transparent and non-transparent materials. The automotive industry, the medical device industry and the electronic industry are just some of the areas where the technology is widely implemented....... There is an increasing industrial interest in joining dissimilar polymers. To overcome the challenges involved increased focus is set on the understanding of joining mechanisms, morphology and molecular structure behavior. Also the understanding of resulting mechanical and thermal properties is presently subject...... for research and development. This paper presents some research results related to laser welding of various polymer materials, including weld compatibility investigations related to the joining of different polymers. Theory for bonding mechanisms, strength development, mechanical properties testing and other...

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

    Science.gov (United States)

    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.

  2. Welding.

    Science.gov (United States)

    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…

  3. Effects of Laser Peening, and Shot Peening, on Friction Stir Welding

    Science.gov (United States)

    Hatamleh, Omar; Hackel, Lloyd; Rankin, Jon; Truong, Chanh; Walter, Matt

    2006-01-01

    A viewgraph presentation describing the effects of laser peening and shot peening on friction stir welding is shown. The topics include: 1) Background; 2) Friction Stir Welding (FSW); 3) Microstructure; 4) Laser & Shot Peening; 5) Residual Stresses; 6) Tensile Behavior; 7) Fatigue Life & Surface Roughness; 8) Crack Growth; and 9) Benefits.

  4. Microstructural characterizations and mechanical properties in underwater friction stir welding of aluminum and magnesium dissimilar alloys

    International Nuclear Information System (INIS)

    Zhao, Yong; Lu, Zhengping; Yan, Keng; Huang, Linzhao

    2015-01-01

    Highlights: • Aluminum and magnesium alloys were joined by underwater friction stir welding. • Underwater FSW was conducted to improve properties of joint with lower heat input. • Microstructures and mechanical properties of dissimilar joint were investigated. • Intermetallic compounds developed in the fracture interface were analyzed. • Fracture features of the tensile samples were analyzed. - Abstract: Formation of intermetallic compounds in the stir zone of dissimilar welds affects the mechanical properties of the joints significantly. In order to reduce heat input and control the amount and morphological characteristics of brittle intermetallic compounds underwater friction stir welding of 6013 Al alloy and AZ31 Mg alloy was carried out. Microstructures, mechanical properties, elements distribution, and the fracture surface of the joints were analyzed by optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy, etc. The result shows that sound dissimilar joint with good mechanical properties can be obtained by underwater friction stir welding. Al and Mg alloys were stirred together and undergone the process of recrystallization, forming complex intercalated flow patterns in the stir zone. Tensile strength of the dissimilar joint was up to 152.3 MPa. Maximum hardness (142HV) appeared in the middle of the centerline of the specimen. Intermetallic compounds layer consisting of Al 3 Mg 2 and Mg 17 Al 12 formed in the Al/Mg interface and resulted in the fracture of the joint

  5. Creep Rupture Properties for Base and Weld Metals of Alloy 617

    International Nuclear Information System (INIS)

    Kim, Woo-Gon; Kim, Min-Hwan; Park, Jae-Young; Ekaputra, I. M. W.

    2015-01-01

    The allowable deformation in the welds is also restricted to half the deformation permitted for the base metal, since the ductility of the welds at elevated temperatures is generally low. For a design use, the data of the tensile and creep properties for Alloy 617 WM should be sufficiently provided, and in particular, to develop a design code of Alloy 617 WM. However, the data for the WM are very rare and limited until now, although the data for the BM are available in the ASME draft code case, which was suspended at the end of the 1980s owing to a lack of support and interes. In this report, the creep data for Alloy 617 WM, which was fabricated by a gas tungsten arc welding (GTAW) procedure, were obtained by a series of creep tests at 800 .deg. C, and the creep properties of the WM were compared with those of the BM. The high-temperature creep properties for Alloy 617 WM, fabricated by a gas tungsten arc welding (GTAW) procedure, were investigated by a series of creep tests with different stress levels at 800 .deg. C, and the creep test data for the WM were compared with those of the BM. From the results, it was found that the WM had a slightly longer creep rupture life and lower creep rate than the BM, and a particularly lower rupture elongation. The lower creep rate in the WM was due to the lower rupture elongation than the BM

  6. Surface studies of iridium-alloy grain boundaries associated with weld cracking

    International Nuclear Information System (INIS)

    Mosley, W.C.

    1982-01-01

    Plutonium-238 oxide fuel pellets for the General Purpose Heat Source (GPHS) Radioisotopic Thermoelectric Generators to be used on the NASA Galileo Mission to Jupiter and the International Solar Polar Mission are produced and encapsulated in iridium alloy at the Savannah River Plant (SRP). Underbead cracks occasionally occur in the girth weld on the iridium-alloy-clad vent sets in the region where the gas tungsten arc is quenched. Grain-boundary structures and compositions were characterized by scanning electron microscopy/x-ray energy spectroscopy, electron microprobe analysis and scanning Auger microprobe analysis to determine the cause of weld quench area cracking. Results suggest that weld quench area cracking may be caused by gas porosity or liquation in the grain boundaries

  7. An Experimental Evaluation of Electron Beam Welded Thixoformed 7075 Aluminum Alloy Plate Material

    Directory of Open Access Journals (Sweden)

    Ava Azadi Chegeni

    2017-12-01

    Full Text Available Two plates of thixoformed 7075 aluminum alloy were joined using Electron Beam Welding (EBW. A post-welding-heat treatment (PWHT was performed within the semi-solid temperature range of this alloy at three temperatures, 610, 617 and 628 °C, for 3 min. The microstructural evolution and mechanical properties of EB welded plates, as well as the heat-treated specimens, were investigated in the Base Metal (BM, Heat Affected Zone (HAZ, and Fusion Zone (FZ, using optical microscopy, Scanning Electron Microscopy (SEM, EDX (Energy Dispersive X-ray Analysis, and Vickers hardness test. Results indicated that after EBW, the grain size substantially decreased from 67 µm in both BM and HAZ to 7 µm in the FZ, and a hardness increment was observed in the FZ as compared to the BM and HAZ. Furthermore, the PWHT led to grain coarsening throughout the material, along with a further increase in hardness in the FZ.

  8. Similar and Dissimilar Nd:YAGlaser Welding of NiTi Shape Memory Alloy to AISI 420Stainless Steel

    Directory of Open Access Journals (Sweden)

    Jassim Mohammed Salman Al-Murshdy

    2017-03-01

    Full Text Available Similar NiTi shape memory alloy(SMA plates, 420 Martensitic stainless steelplates and dissimilar NiTi shape memory alloy with Martensiticstainless steel were welded by a pulsed Nd:YAGlaser welding method.The nature microstructure of the base metal (BM, weld zone (WZ, interface and the heat affected zones(HAZ were showedby in a scanning electron microscope (SEM and optical microscope.Vickers hardness tests wasconducted to specifythe properties of the weld. The outcomes showed that the hardness of dissimilar NiTi-Stainless steel (St.St. weld is higher than that in similar NiTi-NiTi and St.St.-St.St. weld.TheMicrostructural examination in both NiTi-St.St. and NiTi-NiTi welds illustrates that the solidification process in the fusion zone changed the kind of plan to the cell type as well as the changes that occur in the cell to dentritic kind of intra- region of the weld through the weld center in the welded sample sides but in the St.St.-St.St. weld showed dendrite microstructure. In this study it is found that the increase of the welding speed leads to a decrease in hardness in all jointsNiTi-NiTi, NiTi-St.St. and St.St.-St.St.

  9. Investigation of Nd:YAG pulsed laser dissimilar welding of AISI 4340 and AISI 316L stainless steels on weld geometry and mechanical properties

    Science.gov (United States)

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

    2017-12-01

    In this paper, laser welding of 316L and AISI 4340 steel is studied. Studies are focused on the effects of laser parameters on the depth and width of the welds. The results show that increasing in pulse energy and frequency will increase the weld depth and the weld width. The calculation of effective peak power density related to the welded joints results in optimum operating welding parameters with full penetration and proper dimensions and strengths. The tensile strength values of the full penetrated weldments are greater than the tensile strength values of AISI 316 base metal. The effects of laser parameters on weld grain size and HAZ size were investigated. The results show that the weld grain size and HAZ size increase with pulse energy and frequency.

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

    Science.gov (United States)

    Mroczka, K; Dutkiewicz, J; Pietras, A

    2010-03-01

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

  11. On the effect of β phase on the microstructure and mechanical properties of friction stir welded commercial brass alloys.

    Science.gov (United States)

    Heidarzadeh, Akbar; Saeid, Tohid

    2015-12-01

    Conventional fusion welding of brass (Cu-Zn) alloys has some difficulties such as evaporation of Zn, toxic behavior of Zn vapor, solidification cracking, distortion, and oxidation [1], [2], [3]. Fortunately, friction stir welding (FSW) has been proved to be a good candidate for joining the brass alloys, which can overcome the fusion welding short comes [4], [5], [6], [7]. The data presented here relates to FSW of the single and double phase brass alloys. The data is the microstructure and mechanical properties of the base metals and joints.

  12. Laser welding of nylon thin films using a pulsed CO2 waveguide laser

    Science.gov (United States)

    Villagomez, R.; Valenzuela, Rogelio; Camacho-Mesa, Roxana B.

    2011-10-01

    In this work, we present an experimental investigation for welding Nylon: Bi-Oriented Polyamide (BOPA) thin films using a CO2 waveguide laser in a pulsed configuration. The material used in this study is Nylon 6, all set in square sheet thin films samples of 100 cm2 with 15 µm thickness. Our optical setup is based on deliver the laser beam all the way through the work piece using X-Y scanning mirrors mounted on galvo-like motors and an f-theta lens with 15 cm focal length and 50 µm focal spot sizes. The fluence (laser energy) is controlled by a pulse signal generator having the possibility to change the pulse repetition rate (PRR) and the pulse width (PW) of the laser beam. Our results show the best weld seam for scanning speeds of 20mm/s and the pulsed laser beam with 2 KHz PRR and 80 µs for the PW time. The scanning speed and trajectory for the welding process are all controlled by a computer in which one can modify the weld parameters. The irradiance at the focal point is set to 1.146 MW/cm2 while the average optical power was set to 22.5W. Our experimental parameters are previously modeled by using COMSOL Multiphysics software were the laser heat source is modeled on the selected material. This model is based on the heat transfer partial differential equation and solved by finite elements procedure. Model results show a perfect agreement with the experiments. Finally, the quality of the welded seam is studied by means of sealed tight and share force critical mechanical test.

  13. Investigation on edge joints of Inconel 625 sheets processed with laser welding

    Science.gov (United States)

    Caiazzo, F.; Alfieri, V.; Cardaropoli, F.; Sergi, V.

    2017-08-01

    Laser welding of Inconel 625 edge joint beads in square groove configuration was investigated. The use of different weld geometries in new aerospace solutions explains research on edge joints. A structured plan was carried out in order to characterize the process defining the influence of laser power and welding speed and to study possible interactions among the governing factors. As weld pool protection is crucial in order to obtain sound joints when processing superalloys, a special glove box for gas supply was designed to upgrade the welding head. Welded joints were characterized referring to bead profile, microstructure and X-rays. It was found that heat input plays an important role as it affects welding stability, porosity content and bead shape. Results suggest operating with low values of heat input to reduce porosity and guarantee stable bead conformation. Furthermore, a decrease in the grain size has been observed as a consequence of decreasing heat input.

  14. High temperature corrosion resistance of candidate nickel-based weld overlay alloys in a low NOx environment

    Energy Technology Data Exchange (ETDEWEB)

    Deacon, R.M.; Du Pont, J.N.; Marder, A.R. [Lehigh University, Bethlehem, PA (United States)

    2007-07-15

    Changes in environmental regulations have led many fossil fuel-fired boiler operators to alter their combustion practices (low NOx, burning), thereby lowering plant emissions. This change has led to unacceptable wastage of carbon and low alloy steel waterwall tubes and expensive shutdowns due to severe corrosion. One favored solution is to weld overlay a more corrosion resistant alloy on top of existing tubes. Two nickel-based alloys developed for such applications were tested alongside the commercially available alloy 622 in a simulated low NOx, environment. Electron probe microanalysis (EPMA) examination of the weld overlays and corrosion scales demonstrated that microsegregation of molybdenum occurred in one of the candidate alloys and alloy 622. This microsegregation had a detrimental effect on the corrosion resistance of these alloys. The candidate alloy with higher chromium concentration, low nominal molybdenum concentration, and corresponding minimum molybdenum segregation, exhibited the best corrosion resistance of the examined alloys.

  15. High temperature corrosion resistance of candidate nickel-based weld overlay alloys in a low NO {sub x} environment

    Energy Technology Data Exchange (ETDEWEB)

    Deacon, R.M. [Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015 (United States)], E-mail: rmd3@lehigh.edu; DuPont, J.N. [Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015 (United States); Marder, A.R. [Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015 (United States)

    2007-07-15

    Changes in environmental regulations have led many fossil fuel-fired boiler operators to alter their combustion practices (low NO {sub x} burning), thereby lowering plant emissions. This change has led to unacceptable wastage of carbon and low alloy steel waterwall tubes and expensive shutdowns due to severe corrosion. One favored solution is to weld overlay a more corrosion resistant alloy on top of existing tubes. Two nickel-based alloys developed for such applications were tested alongside the commercially available alloy 622 in a simulated low NO {sub x} environment. Electron probe microanalysis (EPMA) examination of the weld overlays and corrosion scales demonstrated that microsegregation of molybdenum occurred in one of the candidate alloys and alloy 622. This microsegregation had a detrimental effect on the corrosion resistance of these alloys. The candidate alloy with higher chromium concentration, low nominal molybdenum concentration, and corresponding minimum molybdenum segregation, exhibited the best corrosion resistance of the examined alloys.

  16. Volume gratings and welding of glass/plastic by femtosecond laser direct writing

    Science.gov (United States)

    Watanabe, Wataru

    2018-01-01

    Femtosecond laser direct writing is used to fabricate diffractive optical elements in three dimensions and to weld glass and/or plastic. In this paper, we review volume gratings in plastics and welding of glass/plastic by femtosecond laser direct writing. Volume gratings were embedded inside polymethyl methacrylate (PMMA) by femtosecond laser pulses. The diffraction efficiency of the gratings increased after fabrication and reached the maximum. After an initial slow decrease within first several days after the fabrication, the efficiency increased again. This phenomena was called regeneration of the grating. We also demonstrate welding of PMMA by dendrite pattern using femtosecond laser pulses. Laser pulses are focused at the interface of two PMMA substrates with an air gap and melted materials in laser-irradiated region spread within a gap of the substrates and dendrite morphology of melted PMMA was observed outside the laser irradiated area. Finally, we show welding of glass/plastic and metal.

  17. Microstructure and corrosion behavior of shielded metal arc-welded dissimilar joints comprising duplex stainless steel and low alloy steel

    Science.gov (United States)

    Srinivasan, P. Bala; Muthupandi, V.; Sivan, V.; Srinivasan, P. Bala; Dietzel, W.

    2006-12-01

    This work describes the results of an investigation on a dissimilar weld joint comprising a boiler-grade low alloy steel and duplex stainless steel (DSS). Welds produced by shielded metal arc-welding with two different electrodes (an austenitic and a duplex grade) were examined for their microstructural features and properties. The welds were found to have overmatching mechanical properties. Although the general corrosion resistance of the weld metals was good, their pitting resistance was found to be inferior when compared with the DSS base material.

  18. Tensile behavior of friction stir welded AA 6061-T4 aluminum alloy joints

    International Nuclear Information System (INIS)

    Heidarzadeh, A.; Khodaverdizadeh, H.; Mahmoudi, A.; Nazari, E.

    2012-01-01

    Highlights: ► Range of parameters for defect-free friction stir welded AA 6061-T4 was reached. ► A model was developed for predicting UTS and EL of friction stir welded AA 6061-T4. ► The maximum values of UTS and EL of joints were estimated by developed model. ► The optimum values of FSW process parameters were determined. -- Abstract: In this investigation response surface methodology based on a central composite rotatable design with three parameters, five levels and 20 runs, was used to develop a mathematical model predicting the tensile properties of friction stir welded AA 6061-T4 aluminum alloy joints at 95% confidence level. The three welding parameters considered were tool rotational speed, welding speed and axial force. Analysis of variance was applied to validate the predicted model. Microstructural characterization and fractography of joints were examined using optical and scanning electron microscopes. Also, the effects of the welding parameters on tensile properties of friction stir welded joints were analyzed in detail. The results showed that the optimum parameters to get a maximum of tensile strength were 920 rev/min, 78 mm/min and 7.2 kN, where the maximum of tensile elongation was obtained at 1300 rev/min, 60 mm/min and 8 kN.

  19. Improving Mechanical Properties of PVPPA Welded Joints of 7075 Aluminum Alloy by PWHT

    Directory of Open Access Journals (Sweden)

    Guowei Li

    2018-03-01

    Full Text Available In this study, 7075 aluminum alloy with a thickness of 10 mm was successfully welded with no obvious defects by pulsed variable polarity plasma arc (PVPPA welding. The mechanical properties of PVPPA welded joints have been researched by post weld heat treatment (PWHT. The results indicate that the heat treatment strongly affects the mechanical properties of the welded joints. The tensile strength and the microhardness of the welded joints gradually improved with the increase of the solution temperature. With the increase of the solution time, the tensile strength, and microhardness first dramatically increased and then decreased slightly. The best tensile strength of 537.5 MPa and the microhardness of 143.7 HV were obtained after 490 °C × 80 min + 120 °C × 24 h, and the strength was nearly 91.2% of that of the parent metal, and increased about 35% compared with as-welded. The improvement of strength and microhardness was mainly due to the precipitation of η′ phase.

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

    Directory of Open Access Journals (Sweden)

    Rajendrana C.

    2017-01-01

    Full Text Available 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°.