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Sample records for alloys laser welded

  1. Underwater laser beam welding of Alloy 690

    International Nuclear Information System (INIS)

    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)

  2. Laser Welding of TC-1 Titanium Alloy

    Institute of Scientific and Technical Information of China (English)

    Hanbin DU; Lunji HU; Xiyuan HU; Jianhua LIU

    2003-01-01

    The technology of CO2 laser welding and joint properties of titanium alloy were investigated. The problem of moltenpool protection was resolved by designing a shielding trailer and a special clamp. Joints with silvery appearance wereobtained, which have no pore and crack. In addition, the welding speed could reach 3 m/min for the plate of 1.5 mmthickness being penetrated. The reason of the porosity formation in partial penetration joints is that the keyholescan be easily cut apart in the radial direction, which makes the gas enclosed in the molten pool. The surface oxideof specimens can not affect the porosity formation in welds directly.

  3. Laser Welding Dissimilar Reflective Alloys

    Science.gov (United States)

    Mccay, M. H.; Gopinathan, S.; Kahlen, F.; Speigel, L.

    1993-01-01

    This project, jointly sponsored by Rocketdyne and CSTAR, involves the development of laser joining of materials which have heretofore been impractical to bond. Of particular interest are joints between stainless steel and copper and also aluminum 6061 to aluminum 2219. CSTAR has a unique opportunity in this area since both the process and development and diagnostics are of interest to industry. Initial results using the pulse tailored laser welding technique developed in CLA for joining crack sensitive materials have proven promising for the aluminum joints based upon metallurgical and electronic microprobe analysis. A declaration of success requires additional mechanical testing. A CW technique has been applied to the stainless-copper joining with some preliminary success. These joints are of significant interest for aeronautics and rocket propulsion applications and the project is expected to continue.

  4. Welding of titanium alloy by different types of lasers

    OpenAIRE

    A. Lisiecki

    2012-01-01

    Purpose: of this paper was focused on comparing the welding modes during laser welding of butt joints of titanium alloy Ti6Al4V sheets 1.5 and 2.0 mm thick with direct diode laser and Disk solid state laser.Design/methodology/approach: Bead-on-plate welds were produced at different parameters of laser welding, different welding speed, different output laser power resulted in different heat input of laser welding process. The test welds were investigated by visual test, metallographic observat...

  5. Welding of titanium alloy by different types of lasers

    Directory of Open Access Journals (Sweden)

    A. Lisiecki

    2012-12-01

    Full Text Available Purpose: of this paper was focused on comparing the welding modes during laser welding of butt joints of titanium alloy Ti6Al4V sheets 1.5 and 2.0 mm thick with direct diode laser and Disk solid state laser.Design/methodology/approach: Bead-on-plate welds were produced at different parameters of laser welding, different welding speed, different output laser power resulted in different heat input of laser welding process. The test welds were investigated by visual test, metallographic observations including macro and microstructure analysis. Additionally mechanical test were carried out such as tensile tests and technological bending test of the joints. The influence of basic laser welding parameters on the penetration depth, shape of fusion zone, width of welds and width of heat affected zones were studied. Additionally the phenomena of laser heating and melting of the welded sheets were analyzed.Findings: It was found that the mechanism of HPDL laser welding of titanium alloy differs distinctly from the mechanism of Disk laser welding. The test welds produced by HPDL laser were high quality. Welds produced by the Disk laser are characterized by a columnar shape of fusion zones, very narrow with narrow and fine structure heat affected zone.Research limitations/implications: In further investigations of laser welding of titanium alloys applying the key-hole welding mode a special care must be taken to the shielding of the weld zone and protection the weld pool and weld metal against the harmful gases from air atmosphere.Practical implications: Results of investigations presented in this paper may be applied directly for welding high quality butt joints of titanium alloy with the HPDL laser. In a case of laser welding with the Disk laser practical application requires further study, especially concentrated on the effectiveness of gas protection of the welding area including the key-hole, weld pool and surrounding regions of metal

  6. Effect of laser characteristics on the weld shape and properties of penetration laser weld of BT20 titanium alloy

    Institute of Scientific and Technical Information of China (English)

    陈俐; 巩水利; 姚伟; 胡伦骥

    2004-01-01

    The laser beam welding of BT20 titanium alloy was conducted to investigate the weld shape, microstructures and properties. The full penetration weld characteristics produced by CO2 laser and by YAG laser were compared. The results show that the full penetration weld of YAG laser welding closes to "X" shape, and weld of CO2 laser welding is "nail-head" shape. Those result from special heating mode of laser deep penetration welding. The tension strength of CO2 laser and YAG laser joints equal to that of the base metal, but the former has better ductility. All welds consist mainly of the acicular α phase and a few β phase in microstructure. The dendritic crystal of CO2 laser weld is a little finer than YAG laser weld. According the research CO2 laser is better than YAG laser for welding of BT20 titanium alloy.

  7. Laser welding of AZ61 magnesium-based alloys

    Institute of Scientific and Technical Information of China (English)

    Wang Hongying; Li Zhijun; Zhang Yihui

    2006-01-01

    Laser welding of AZ61 magnesium alloys was carried out asing a CO2 laser weldingexperimental system.The welding properties of AZ61 sheets with different thickness were investigated.The effect of processing parameters including laser power, welding speed and protection gas flow was researched.The results show that laser power and welding speed have large effect on the weld width and joint dimensions.Protection gas flow has relatively slight effect on the weld width.The property test of three typical joints indicates that microhardness and tensile strength in weld zone are higher than that of AZ61 base metal.Joints with good appearance and excellent mechanical properties can be produced using CO2 laser welding method.The microstructure with small grains in weld zone is believed to be responsible for the excellent mechanical properties of AZ61 joints.

  8. 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.

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

    OpenAIRE

    Watanabe, Ikuya; Wallace, Cameron

    2008-01-01

    The objective of this study was to investigate the joint properties between cast gold alloys and Co-Cr alloy laser-welded by Nd:YAG laser. Cast plates were fabricated from three types of gold alloys (Type IV, Type II and low-gold) and a Co-Cr alloy. Each gold alloy was laser-welded to Co-Cr using a dental laser-welding machine. Homogeneously-welded and non-welded control specimens were also prepared. Tensile testing was conducted and data were statistically analyzed using ANOVA. The homogeneo...

  10. Effect of Laser Welding Parameters on Formation of NiTi Shape Memory Alloy Welds

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2014-01-01

    Full Text Available In this work experimental trials of welding of NiTi flat plates with 2.0 mm thickness were conducted using a 4.5 kW continuous wave (CW Nd:YAG laser. The influences of laser output power, welding speed, defocus amount and side-blow shielding gas flow rate on the morphology, welding depth and width, and quality of the welded seam were investigated. Meanwhile, the effects of heat input on the mechanical and functional properties of welded joints were studied. The results show that laser welding can take better formation in NiTi alloys. The matching curves with laser power and welding speed affecting different formation of welds were experimentally acquired, which can provide references for laser welding and engineering application of NiTi alloy. The heat input has obvious effects on the ultimate tensile strength (UTS and shape memory behavior of the welded joints.

  11. Comparative study on welding characteristics of laser-additional current hybrid welded T-joint of aluminium and titanium alloy

    OpenAIRE

    Zhang Xinge; Li Liqun; Chen Yanbin; Zhu Xiaocui; Li Yansheng; Guo Xinjian

    2015-01-01

    In order to improve the properties of laser overlap welded T-joint, laser-additional current hybrid welding process is put forward. In this paper, the welding characteristics of laser-additional current hybrid welded aluminum and titanium alloy T-joint were conducted and compared. The weld width at faying surface increase, which results in tensile shear load increasing compared with those of laser welding for both aluminum and titanium alloy, but the effect of current on aluminum alloy is mor...

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

    International Nuclear Information System (INIS)

    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 CO2 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)

  13. Hybrid laser-TIG welding, laser beam welding and gas tungsten arc welding of AZ31B magnesium alloy

    International Nuclear Information System (INIS)

    Welding of AZ31B magnesium alloy was carried out using hybrid laser-TIG (LATIG) welding, laser beam welding (LBW) and gas tungsten arc (TIG) welding. The weldability and microstructure of magnesium AZ31B alloy welded using LATIG, LBW and TIG were investigated by OM and EMPA. The experimental results showed that the welding speed of LATIG was higher than that of TIG, which was caught up with LBW. Besides, the penetration of LATIG doubles that of TIG, and was four times that of LBW. In addition, arc stability was improved in hybrid of laser-TIG welding compared with using the TIG welding alone, especially at high welding speed and under low TIG current. It was found that the heat affect zone of joint was only observed in TIG welding, and the size of grains in it was evidently coarse. In fusion zone, the equiaxed grains exist, whose size was the smallest welded by LBW, and was the largest by TIG welding. It was also found that Mg concentration of the fusion zone was lower than that of the base one by EPMA in three welding processes

  14. Comparative study on welding characteristics of laser-additional current hybrid welded T-joint of aluminium and titanium alloy

    Directory of Open Access Journals (Sweden)

    Zhang Xinge

    2015-01-01

    Full Text Available In order to improve the properties of laser overlap welded T-joint, laser-additional current hybrid welding process is put forward. In this paper, the welding characteristics of laser-additional current hybrid welded aluminum and titanium alloy T-joint were conducted and compared. The weld width at faying surface increase, which results in tensile shear load increasing compared with those of laser welding for both aluminum and titanium alloy, but the effect of current on aluminum alloy is more obvious. The porosity defect within the laser-additional current hybrid welded joint sharply reduces compared with that within laser welding. The tensile shear load of aluminum alloy and titanium alloy hybrid welded joints respectively increase 21% and 15%. The effects of additional current on welding characteristics of aluminum alloy and titanium alloy are compared and analyzed.

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

    Science.gov (United States)

    Watanabe, Ikuya; Wallace, Cameron

    2008-01-01

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

  16. Mechanical strength of laser-welded cobalt-chromium alloy.

    Science.gov (United States)

    Baba, N; Watanabe, I; Liu, J; Atsuta, M

    2004-05-15

    The purpose of this study was to investigate the effect of the output energy of laser welding and welding methods on the joint strength of cobalt-chromium (Co-Cr) alloy. Two types of cast Co-Cr plates were prepared, and transverse sections were made at the center of the plate. The cut surfaces were butted against one another, and the joints welded with a laser-welding machine at several levels of output energy with the use of two methods. The fracture force required to break specimens was determined by means of tensile testing. For the 0.5-mm-thick specimens, the force required to break the 0.5-mm laser-welded specimens at currents of 270 and 300 A was not statistically different (p > 0.05) from the results for the nonwelded control specimens. The force required to break the 1.0-mm specimens double-welded at a current of 270 A was the highest value among the 1.0-mm laser-welded specimens. The results suggested that laser welding under the appropriate conditions improved the joint strength of cobalt- chromium alloy. PMID:15116400

  17. Development of laser welding techniques for vanadium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Strain, R.V.; Leong, K.H.; Smith, D.L. [Argonne National Laboratory, IL (United States)

    1996-10-01

    Laser welding is potentially advantageous because of its flexibility and the reduced amount of material affected by the weld. Bead-on-plate and butt welds were previously performed to depths of about 4 mm with a 6-kW CO{sub 2} laser on V-4%Cr-4%Ti and V-5%Cr-5%Ti alloys. These welds were made at a speed of 0.042 m/s using argon purging at a flow rate of 2.8 m{sup 3}/s. The purge was distributed with a diffuser nozzle aimed just behind the laser beam during the welding operation. The fusion zones of welds made under these conditions consisted of very fine, needle-shaped grains and were also harder than the bulk metal (230-270 dph, compared to {approx}180 dph for the bulk metal). A limited number of impact tests showed that the as-welded ductile-brittle transition temperatures (DBTT) was above room temperature, but heat treatment at 1000{degrees}C for 1 h in vacuum reduced the DBTT to <{minus}25{degrees}C. Activities during this reporting period focused on improvements in the purging system and determination of the effect of welding speed on welds. A 2-kW continuous YAG laser at Lumonics Corp. in Livonia, MI, was used to make 34 test welds for this study.

  18. 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.

  19. Alloying element vaporization during laser spot welding of stainless steel

    International Nuclear Information System (INIS)

    Alloying element loss from the weld pool during laser spot welding of stainless steel was investigated experimentally and theoretically. The experimental work involved determination of work-piece weight loss and metal vapour composition for various welding conditions. The transient temperature and velocity fields in the weld pool were numerically simulated. The vaporization rates of the alloying elements were modelled using the computed temperature profiles. The fusion zone geometry could be predicted from the transient heat transfer and fluid flow model for various welding conditions. The laser power and the pulse duration were the most important variables in determining the transient temperature profiles. The velocity of the liquid metal in the weld pool increased with time during heating and convection played an increasingly important role in the heat transfer. The peak temperature and velocity increased significantly with laser power density and pulse duration. At very high power densities, the computed temperatures were higher than the boiling point of 304 stainless steel. As a result, evaporation of alloying elements was caused by both the total pressure and the concentration gradients. The calculations showed that the vaporization occurred mainly from a small region under the laser beam where the temperatures were very high. The computed vapour loss was found to be lower than the measured mass loss because of the ejection of tiny metal droplets owing to the recoil force exerted by the metal vapours. The ejection of metal droplets has been predicted by computations and verified by experiments

  20. Finite element simulation of magnesium alloys laser beam welding

    OpenAIRE

    BELHADJ, Asma; BESSROUR, Jamel; MASSE, Jean-Eric; BOUHAFS, Mahmoud; Barrallier, Laurent

    2010-01-01

    In this paper, a three-dimensional finite element model is developed to simulate thermal history magnesium-based alloys during laser beam welding. Space-time temperature distributions in weldments are predicted from the beginning of welding to the final cooling. The finite element calculations were performed using Cast3M code with which the heat equation is solved considering a non-linear transient behaviour. The applied loading is a moving heat source that depends on process parameters such ...

  1. Laser welding of an advanced rapidly-solidified titanium alloy

    Science.gov (United States)

    Baeslack, W. A., III; Chiang, S.; Albright, C. A.

    1990-06-01

    The laser weldability of a complex RS titanium alloy containing yttrium is investigated by evaluating comparatively the microstructures, mechanical properties, and fracture characteristics of the base metal and the rapidly solidified weld fusion zone. To prevent atmospheric contamination the specimen was enclosed in a helium-purged plastic bag during the welding process. After welding, the coupons were sectioned transverse to the laser beam direction of traverse, epoxy mounted, polished down to 0.05 micron SiO2 and etched with Kroll's reagent for examination utilizing light and SEM and energy-dispersive X-ray analysis. Results indicate that laser welding is effective in producing a fine fusion zone dispersoid structure in the RS Ti composite.

  2. Prevention of microcracking by REM addition to alloy 690 filler metal in laser clad welds

    International Nuclear Information System (INIS)

    Effect of REM addition to alloy 690 filler metal on microcracking prevention was verified in laser clad welding. Laser clad welding on alloy 132 weld metal or type 316L stainless steel was conducted using the five different filler metals of alloy 690 varying the La content. Ductility-dip crack occurred in laser clad welding when La-free alloy 690 filler metal was applied. Solidification and liquation cracks occurred contrarily in the laser cladding weld metal when the 0.07mass%La containing filler metal was applied. In case of laser clad welding on alloy 132 weld metal and type 316L stainless steel, the ductility-dip cracking susceptibility decreased, and solidification/liquation cracking susceptibilities increased with increasing the La content in the weld metal. The relation among the microcracking susceptibility, the (P+S) and La contents in every weld pass of the laser clad welding was investigated. Ductility-dip cracks occurred in the compositional range (atomic ratio) of La/(P+S) 0.99(on alloy 132 weld metal), >0.90 (on type 316L stainless steel), while any cracks did not occur at La/(P+S) being between 0.21-0.99 (on alloy 132 weld metal) 0.10-0.90 (on type 316L stainless steel). Laser clad welding test on type 316L stainless steel using alloy 690 filler metal containing the optimum La content verified that any microcracks did not occurred in the laser clad welding metal. (author)

  3. A Review: Welding Of Dissimilar Metal Alloys by Laser Beam Welding & Friction Stir Welding Techniques

    Directory of Open Access Journals (Sweden)

    Ms. Deepika Harwani

    2014-12-01

    Full Text Available Welding of dissimilar metals has attracted attention of the researchers worldwide, owing to its many advantages and challenges. There is no denial in the fact that dissimilar welded joints offer more flexibility in the design and production of the commercial and industrial components. Many welding techniques have been analyzed to join dissimilar metal combinations. The objective of this paper is to review two such techniques – Laser welding and Friction stir welding. Laser beam welding, a high power density and low energy-input process, employs a laser beam to produce welds of dissimilar materials. Friction stir welding, a solid-state joining process, is also successfully used in dissimilar welding applications like aerospace and ship building industries. This paper summarizes the trends and advances of these two welding processes in the field of dissimilar welding. Future aspects of the study are also discussed.

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

    International Nuclear Information System (INIS)

    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'' (Mg2Si) 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

  5. A Review: Welding Of Dissimilar Metal Alloys by Laser Beam Welding & Friction Stir Welding Techniques

    OpenAIRE

    Ms. Deepika Harwani; Mr. Kapil Banker

    2014-01-01

    Welding of dissimilar metals has attracted attention of the researchers worldwide, owing to its many advantages and challenges. There is no denial in the fact that dissimilar welded joints offer more flexibility in the design and production of the commercial and industrial components. Many welding techniques have been analyzed to join dissimilar metal combinations. The objective of this paper is to review two such techniques – Laser welding and Friction stir welding. Laser beam we...

  6. Structure and properties of welded joints under laser and arc welding of Zr-2.5%Nb alloy

    International Nuclear Information System (INIS)

    Laser welding was used for improving plasticity of welded joints of Zr-2.5%Nb compositions. It is noted that laser welding of Zr-2.5%Nb alloy at 100-120 m/h rate allows to produce joints featuring high quality, high strength and plasticity of welds whose bend angel equals 160-180 deg. Corrosion resistance of joints in sulphuric, nitric and acetic acids is at the level of basic metal resistance. Decrease of weld width, heat contribution and chemical inhomogeneity of weld metal and HAZ under laser welding conditions reduces the tendency of weld joints to intercrystal corrosion in a 70% solution of sulphuric acid

  7. CO2 and diode laser welding of AZ31 magnesium alloy

    International Nuclear Information System (INIS)

    Magnesium alloys are being increasingly used in automotive and aerospace structures. Laser welding is an important joining method in such applications. There are several kinds of industrial lasers available at present, including the conventional CO2 and Nd:YAG lasers as well as recently available high power diode lasers. A 1.5 kW diode laser and a 2 kW CO2 laser are used in the present study for the welding of AZ31 alloys. It is found that different welding modes exist, i.e., keyhole welding with the CO2 laser and conduction welding with both the CO2 and the diode lasers. This paper characterizes welds in both welding modes. The effect of beam spot size on the weld quality is analyzed. The laser processing parameters are optimized to obtain welds with minimum defects

  8. 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.

  9. Study on the effect of welding current during laser beam-resistance seam welding of aluminum alloy 5052

    Institute of Scientific and Technical Information of China (English)

    Li Yongqiang; Zhao Xihua; Zhao He; Cao Haipeng; Zhao Huanling

    2008-01-01

    The effect of welding current on the weld shape and tensile shear load during laser beam-resistance seam welding (LB-RSW) of aluminum alloy 5052 is studied. Experimental results show that the penetration depth, weld width,tensile shear load and the ratio of penetration depth to weld width of LB-RSW are bigger than those of laser beam welding(LBW) under the same conditions and the former three parameters increase as welding current rises. The weld shape of LB-RSW below 5 kA welding current is nearly the same as that of LBW. The weld morphology is protuberant under the condition of 5 kA welding current and 0.8 m/min welding speed. Furthermore, the microstructure of the weld seam of LB-RSW is coarser than that of LBW.

  10. Laser welding of thin-walled constructions made of titanium alloys along laser cut

    International Nuclear Information System (INIS)

    OT4 titanium alloy samples 0.3-0.4 mm thick were used in welding and cutting experiments. It is shown that the quality of laser beam cutting of thin-well titanium alloys satisfier the current requirements for assembly of workpieces (without mechining of their edges) and strength properties of joints, produced by the subsequent welding, are close to the properties of the basic material

  11. Effects of conventional welding and laser welding on the tensile strength, ultimate tensile strength and surface characteristics of two cobalt-chromium alloys: a comparative study.

    Science.gov (United States)

    Madhan Kumar, Seenivasan; Sethumadhava, Jayesh Raghavendra; Anand Kumar, Vaidyanathan; Manita, Grover

    2012-06-01

    The purpose of this study was to evaluate the efficacy of laser welding and conventional welding on the tensile strength and ultimate tensile strength of the cobalt-chromium alloy. Samples were prepared with two commercially available cobalt-chromium alloys (Wironium plus and Diadur alloy). The samples were sectioned and the broken fragments were joined using Conventional and Laser welding techniques. The welded joints were subjected to tensile and ultimate tensile strength testing; and scanning electron microscope to evaluate the surface characteristics at the welded site. Both on laser welding as well as on conventional welding technique, Diadur alloy samples showed lesser values when tested for tensile and ultimate tensile strength when compared to Wironium alloy samples. Under the scanning electron microscope, the laser welded joints show uniform welding and continuous molt pool all over the surface with less porosity than the conventionally welded joints. Laser welding is an advantageous method of connecting or repairing cast metal prosthetic frameworks. PMID:23858281

  12. Joint performance of CO2 laser beam welding 5083-H321 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    Qi Junfeng; Zhang Dongyun; Xiao Rongshi; Chen Kai; Zuo Tiechuan

    2007-01-01

    Laser beam welding of aluminum alloys is expected to offer good mechanical properties of welded joints. In this experimental work reported, CO2 laser beam autogenous welding and wire feed welding are conducted on 4mm thick 5083-H321 aluminum alloy sheets at different welding variables. The mechanical properties and microstructure characteristics of the welds are evaluated through tensile tests, micro-hardness tests, optical microscopy and scanning electron microscopy (SEM). Experimental results indicate that both the tensile strength and hardness of laser beam welds are affected by the constitution of filler material, except the yield strength. The soften region of laser beam welds is not in the heat-affected zone (HAZ). The tensile fracture of laser beam welded specimens takes place in the weld zone and close to the weld boundary because of different filler materials. Some pores are found on the fracture face, including hydrogen porosities and blow holes, but these pores have no influence on the tensile strength of laser beam welds. Tensile strength values of laser beam welds with filler wire are up to 345.57MPa, 93% of base material values, and yield strengths of laser beam welds are equivalent to those of base metal (264.50MPa).

  13. Microstructures and properties of laser welding joint of super-eutectic ZA alloy

    International Nuclear Information System (INIS)

    Highlights: ► It is a new process for the forming of ZA alloy via laser welding. ► A good joint by pulsed laser welding has been achieved successfully. ► It may be applied other non-ferrous alloys in various engineering applications. -- Abstract: In this paper, we describe the experimental laser welding of ZA alloy. The formation of the weld demonstrated that pulsed laser welding for ZA alloy was more effective than continuous laser welding. The characteristics of microstructures and properties of the ZA alloy’s bond area welded by pulsed laser were investigated using an optical microscope, X-Ray Diffractometer (referred to as XRD) and other methodologies. The applicable technological parameters include welding speed of 0.9 m/min, pulsed laser power of 1.8 kW, impulse period of 3 ms and duty cycle of 3:4. The average micro-hardness of the laser welding seam zone is higher than that of the ZA alloy substrate, which is as high as 183HV. The microstructures in the weld consist of primary η phase (the white dendritic structure), β phase (the black block distribution around η phase), and eutectic phases (β + η) (platy layer). The average strength of the joints is 119 MPa, 70% of that of the base metal.

  14. Welding of cobalt-based amorphous alloys with Nd: YAG laser

    International Nuclear Information System (INIS)

    The paper describes the results concerning the investigation of the welding of cobalt-based amorphous alloys with Nd:YAG laser. Five alloys with different chemical structure and dimensions in shape of amorphous metal foils were welded. The quality of the welded joints were tested by using a microstructure analysis with an optical microscope and SEM, when the metal graphic structure, the chemical structure and the microhardness of the welded joints were tested as well. (Author)

  15. A study on the porosity of CO2 laser welding of titanium alloy

    Institute of Scientific and Technical Information of China (English)

    Chen Li; Hu Lunji; Gong Shuili

    2006-01-01

    The CO2 laser welding of BT20 titanium alloy and Ti-23Al-17Nb titanium aluminide was conducted to investigate into the porosity in titanium alloy weld. The results show that there are two sorts of porosities observed in welds of titanium alloy laser welding based on the microscopic characteristics of the porosities. One is the metallurgical porosity with round and smooth inner wall, which results from the surface contamination. The other is the processing porosity with irregular and rough inner wall that displays the trace of the pool flowing, which results from the ruffle on the keyhole wall gathering together locally and closing down the gas in the keyhole into bubbles because of the keyhole fluctuating. The CO2 laser welding could break down easily the surface oxide film and produce little metallurgical porosity, but produces easily processing porosity when partial penetration or unstable-full penetration laser welding is conducted, which always occurs in the center of weld.

  16. CO2 laser beam welding of AM60 magnesium-based alloy

    OpenAIRE

    BELHADJ, Asma; MASSE, Jean-Eric; Barrallier, Laurent; BOUHAFS, Mahmoud; BESSROUR, Jamel

    2010-01-01

    Magnesium alloys have a 33% lower density than aluminum alloys, whereas they exhibit the same mechanical characteristics. Their application increases in many economic sectors, in particular, in aeronautic and automotive industries. Nevertheless, their assembly with welding techniques still remains to be developed. In this paper, we present a CO2 laser welding investigation of AM60 magnesium-based alloy. Welding parameters range is determinate for the joining of 3 mm thickness sheets. The effe...

  17. Procedure development of laser welding of V-4Cr-4Ti alloy

    International Nuclear Information System (INIS)

    V-4Cr-4Ti alloy is selected as the structure material for the first wall/blanket in a fusion power reactor. A systematic study was conducted to develop a laser welding procedure for fabrication of vanadium alloy for the first wall/blanket systems. A 1.6 kW pulsed Nd:YAG laser with fiber optic beam delivery was used to carry out the bead-on-plate welding on 4 mm thick V-4Cr-4Ti plates. The process parameters, such as laser schedule power settings, beam travel speed, and welding atmosphere control, and their effects on weld quality, such as weld depth, porosity, and oxygen uptake were studied. Results from metallurgical characterization of the welds are presented. An innovative laser welding procedure has been developed to obtain deep penetration, defect-free, and oxygen contamination-free welds

  18. Electrochemical behavior of YAG laser-welded NiTi shape memory alloy

    Institute of Scientific and Technical Information of China (English)

    YAN Xiao-jun; YANG Da-zhi; LIU Xiao-peng

    2006-01-01

    Electrochemical behaviors of laser-welded Ti-50.6%Ni(mole fraction) shape memory alloy and the base metal in 0.9% NaCl solution were investigated by electrochemical techniques as corrosion potential measurement, linear and potentiodynamic polarization. The results indicate that the laser-welded NiTi alloy is less susceptible to pitting and crevice corrosion than the base metal, which is demonstrated by the increase in polarization resistance(Rp) and pitting potential(ψpit) and decrease in corrosion current density(Jcorr) and mean difference between ψpit and ψprot values. It is confirmed by scanning electron microscope micrographs that pits could be observed on the surface of base metal but not on the surface of laser-welded alloy after potentiodynamic tests. An improvement of corrosion resistance of laser-welded NiTi alloy could be attributed to almost complete dissolution of inclusions upon laser welding.

  19. Study on arc and laser powers in the hybrid welding of AA5754 Al-alloy

    International Nuclear Information System (INIS)

    Highlights: • 5754 Al-alloy weldability with a hybrid welding source was assessed. • Weld porosity sensitiveness to laser and arc powers was demonstrated. • Microstructure, residual stress and the mechanical properties were evaluated. • The best levels of welding parameters were given in the investigated range. - Abstract: In this paper a new generation of fiber laser assisted by a MIG source was used to weld AA5754-H111 aluminum alloy in 3 mm thick butt configuration. The effects of laser and arc powers on the weld geometry and properties were studied. Weld geometry and porosity were measured. The microstructure was investigated by optical microscope and Vickers micro-hardness was taken. The residual stress close to the heat affected zone was measured by the incremental hole-drilling method. Eventually, the tensile test was conducted in order to compare the mechanical properties of the weld with those of the parent metal. For the first time the sensitiveness of the hybrid welding of the 5754 aluminum alloy to the arc and laser powers was demonstrated. Higher laser power favored the stability of the process and provided good structural and geometrical properties of the weld. Further investigation can be performed in order to optimize the weld soundness and the energy efficiency of hybrid welding an aluminum alloy using a fiber laser

  20. High Power Laser Welding. [of stainless steel and titanium alloy structures

    Science.gov (United States)

    Banas, C. M.

    1972-01-01

    A review of recent developments in high power, carbon dixoide laser welding is presented. Deep penetration welding in stainless steel to 0.5-in. thick, high speed welding in thin gage rimmed steel and gas shielded welding in Ti-6Al-4V alloy are described. The effects of laser power, power density, focusing optics, gas-shielding techniques, material properties and weld speed on weld quality and penetration are discussed. It is shown that laser welding performance in thin materials is comparable to that of electron beams. It is further shown that high quality welds, as evidenced by NDT, mechanical and metal-lographic tests, can be achieved. The potential of the laser for industrial welding applications is indicated.

  1. Prediction of microcracking in laser overly welds of alloy 690 to type 316L stainless steel

    International Nuclear Information System (INIS)

    The occurrence of ductility-dip crack in the laser overlay welds of alloy 690 to type 316L stainless steel was predicted by the mechanical and metallurgical approaches. Ductility-dip temperature ranges (DTRs) of alloy 690 laser overlay welds were estimated by Varestraint test during GTA welding. The grain boundary segregation of impurity elements such as P and S was numerically analyzed based on the non-equilibrium cosegregation theory when the welding speed and the amounts of P and S in the weld metal were varied. In accordance with the repression approximation between the DTR and the calculated grain boundary concentrations of P and S, the DTRs of alloy 690 were computed in laser overlay welding. The estimated DTR in laser overlay welds was reduced with an increase in welding speed and with a decrease in the amounts of P and S in the weld metal. Ductility-dip cracking in laser overlay welds was predicted by the plastic strain-temperature curve intersected the DTR. The plastic strain in laser overlay welding was numerically analyzed using the thermo elasto-plastic finite element method. The plastic strain-temperature curve in laser overlay welds intersected the DTR at decreased welding speed and increased (P+S) content in the weld metal. The predicted results of ductility-dip cracking in laser overlay welds were approximately consistent with experiment results. It follows that ductility-dip cracking in laser overlay welds could be successfully predicted based on the estimated DTR from grain boundary segregation analysis combined with the computed plastic strain by FEM analysis. (author)

  2. Welding of Mo-Based Alloy Using Electron Beam and Laser-GTAW Hybrid Welding Techniques

    Science.gov (United States)

    Chatterjee, Anjan; Kumar, Santosh; Tewari, Raghvendra; Dey, Gautam Kumar

    2016-03-01

    In the current study, welding of TZM (molybdenum-based alloy) plates in square-butt configuration was carried out using electron beam and laser-GTAW hybrid power sources. Microstructures of weld joint containing three zones—parent metal, heat-affected zone, and fusion zone—were clearly identified when examined through optical and scanning electron microscopy. The weld joints were found to be sound with very wide fusion and heat-affected zones. The microstructure of the fusion zone was coarse-grained. as-solidified microstructure, while the microstructure of heat-affected zone was the recrystallized microstructure with reduction in grain size as distance from the fusion line increased. Microhardness profile using Vickers hardness tester was obtained across the weld region, and the tensile properties of the weld joints were evaluated by performing room temperature tensile test and fracture was examined using scanning electron microscope. Joint coefficient of the weld joints were ~40 to 45 pct of that of the parent metals with nonmeasurable tensile ductility with predominantly transgranular mode of fracture indicating weakness along the grain boundary. Detailed orientation imaging and transmission electron microscopy were carried out to understand the most dominating factor in introducing weld joint brittleness.

  3. 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

    2016-07-01

    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.

  4. Infrared temperature measurement and interference analysis of magnesium alloys in hybrid laser-TIG welding process

    Energy Technology Data Exchange (ETDEWEB)

    Huang, R.-S. [State Key Laboratory of Materials Modification and School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Liu, L.-M. [State Key Laboratory of Materials Modification and School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)]. E-mail: liulm@dlut.edu.cn; Song, G. [State Key Laboratory of Materials Modification and School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)

    2007-02-25

    Infrared (IR) temperature measurement, as a convenient, non-contact method for making temperature field measurements, has been widely used in the fields of welding, but the problem of interference from radiant reflection is a complicating factor in applying IR temperature sensing to welding. The object of this research is to make a deep understand about the formation of interference, explore a new method to eliminate the interfering radiation during laser-TIG hybrid welding of magnesium alloys and to obtain the distribution of temperature field accurately. The experimental results showed that the interferences caused by radiant specular reflection of arc light, ceramic nozzle, electrode and laser nozzle were transferred out of welding seam while the IR thermography system was placed perpendicularly to welding seam. And the welding temperature distribution captured by IR termography system which had been calibrated by thermocouple was reliable by using this method in hybrid laser-TIG welding process of AZ31B magnesium alloy.

  5. Welding And Cutting A Nickel Alloy By Laser

    Science.gov (United States)

    Banas, C. M.

    1990-01-01

    Technique effective and energy-efficient. Report describes evaluation of laser welding and cutting of Inconel(R) 718. Notes that electron-beam welding processes developed for In-718, but difficult to use on large or complex structures. Cutting of In-718 by laser fast and produces only narrow kerf. Cut edge requires dressing, to endure fatigue.

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

    Science.gov (United States)

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

    2005-12-01

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

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

    International Nuclear Information System (INIS)

    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

  8. Investigation of the corrosion behaviour of laser-TIG hybrid welded Mg alloys

    International Nuclear Information System (INIS)

    The paper presents the corrosion behaviour of the laser-tungsten inert gas welded Mg alloy. The effects of microstructure variations of Mg alloy joint on the corrosion behaviour and reliabilities of joint are investigated. The results demonstrate that the effects of some weld defects and precipitated phases on the corrosion behaviour of weld joint are very little, and corrosion resistance of joint is predominantly influenced by grain refinement or interactions of grain refinement and continued net-shaped β phases. Moreover, the corrosion resistance of weld joints and welding mode (butt and lap joint) keep a close relation, which must not be ignored.

  9. Effects of Conventional Welding and Laser Welding on the Tensile Strength, Ultimate Tensile Strength and Surface Characteristics of Two Cobalt–Chromium Alloys: A Comparative Study

    OpenAIRE

    Madhan Kumar, Seenivasan; Sethumadhava, Jayesh Raghavendra; Anand Kumar, Vaidyanathan; Manita, Grover

    2012-01-01

    The purpose of this study was to evaluate the efficacy of laser welding and conventional welding on the tensile strength and ultimate tensile strength of the cobalt–chromium alloy. Samples were prepared with two commercially available cobalt–chromium alloys (Wironium plus and Diadur alloy). The samples were sectioned and the broken fragments were joined using Conventional and Laser welding techniques. The welded joints were subjected to tensile and ultimate tensile strength testing; and scann...

  10. High-power laser and arc welding of thorium-doped iridium alloys

    International Nuclear Information System (INIS)

    The arc and laser weldabilities of two Ir-0.3% W alloys containing 60 and 200 wt ppM Th have been investigated. The Ir-.03% W alloy containing 200 wt ppM Th is severely prone to hot cracking during gas tungsten-arc welding. Weld metal cracking results from the combined effects of heat-affected zone liquation cracking and solidification cracking. Scanning electron microscopic analysis of the fractured surface revealed patches of low-melting eutectic. The cracking is influenced to a great extent by the fusion zone microstructure and thorium content. The alloy has been welded with a continuous-wave high-power CO2 laser system with beam power ranging from 5 to 10 kW and welding speeds of 8 to 25 mm/s. Successful laser welds without hot cracking have been obtained in this particular alloy. This is attributable to the highly concentrated heat source available in the laser beam and the refinement in fusion zone microstructure obtained during laser welding. Efforts to refine the fusion zone structure during gas tungsten-arc welding of Ir-0.3 % W alloy containing 60 wt ppM Th were partially successful. Here transverse arc oscillation during gas tungsten-arc welding refines the fusion zone structure to a certain extent. However, microstructural analysis of this alloy's laser welds indicates further refinement in the fusion zone microstructure than in that from the gas tungsten-arc process using arc oscillations. The fusion zone structure of the laser weld is a strong function of welding speed

  11. Development of a technology for laser welding of the 1424 aluminum alloy with a high strength of the welded joint

    Science.gov (United States)

    Annin, B. D.; Fomin, V. M.; Karpov, E. V.; Malikov, A. G.; Orishich, A. M.; Cherepanov, A. N.

    2015-11-01

    Results of an experimental study of properties of joints obtained by using different regimes of laser welding of the 1424 alloy (Al-Mg-Li) are reported. The strength and structure of the welded joints are determined. The influence of various types of welded joint straining on its strength is studied. It is demonstrated that the joint strength increases in the case of plastic straining.

  12. Laser-welded V-Cr-Ti alloys: Microstructural and mechanical properties

    International Nuclear Information System (INIS)

    A systematic study has been initiated to examine the use of lasers to weld sheet materials of V-Cr-Ti alloys and to characterize the microstructural and mechanical properties of the laser-welded materials. In addition, several post-welding heat treatments are being applied to the welded samples to evaluate their benefits, if any, to the structure and properties of the weldments. Hardness measurements are made across the welded regions of different samples to evaluate differences in the characteristics of various weldments

  13. Laser-welded V-Cr-Ti alloys: Microstructural and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Smith, D.L.; Sanders, P.G.; Leong, K.H. [Argonne National Lab., IL (United States)

    1998-03-01

    A systematic study has been initiated to examine the use of lasers to weld sheet materials of V-Cr-Ti alloys and to characterize the microstructural and mechanical properties of the laser-welded materials. In addition, several post-welding heat treatments are being applied to the welded samples to evaluate their benefits, if any, to the structure and properties of the weldments. Hardness measurements are made across the welded regions of different samples to evaluate differences in the characteristics of various weldments.

  14. INVESTIGATION OF LASER BEAM WELDING PROCESS OF AZ61 MAGNESIUM-BASED ALLOY

    Institute of Scientific and Technical Information of China (English)

    H.Y. Wang; Z.J. Li

    2006-01-01

    Laser welding process of AZ61 magnesium alloys is investigated using a special CO2 laser experimental system. The effect of processing parameters including laser power, welding speed,and protection gas flow at the top and bottom is researched The results show that an ideal weld bead can be formed by choosing the processing parameters properly. An optimized parameter range is obtained by a large number of experiments. Among them, laser power and welding speed are the two main parameters that determine the weld width and dimensions. The protect gas flow rate has a slight effect on the weld width, but it directly effects the surface color of the weld. The test results for typical welds indicate that the microhardness and tensile strength of the weld zone are better than that of the base metal. A fine-grained weld region has been observed and no obvious heat-affected zone is found. The weld zone mainly consists of small α-Mg phase, (α +Al12Mg17), and other eutectic phases. The small grains and the eutectic phases in the joint are believed to play an important role in the increase of the strength of welds for AZ61 magnesium alloys.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ishak, M., E-mail: mahadzir@ump.edu.my [University Malaysia Pahang, Faculty of Mechanical Engineering, 26600 Pekan, Pahang Darul Makmur (Malaysia); Maekawa, K., E-mail: mae@mx.ibaraki.ac.jp [Ibaraki University, Faculty of Engineering, Department of Mechanical Engineering, 4-12-1 Nakanarusawa, Hitachi, Ibaraki 316-8511 (Japan); Yamasaki, K., E-mail: kyama@mx.ibaraki.ac.jp [Ibaraki University, Faculty of Engineering, Department of Mechanical Engineering, 4-12-1 Nakanarusawa, Hitachi, Ibaraki 316-8511 (Japan)

    2012-02-28

    Highlights: Black-Right-Pointing-Pointer Ag nanoparticles are used as insert material for welding Mg alloy with laser. Black-Right-Pointing-Pointer We examine the microstructure and mechanical properties of welded Mg alloys. Black-Right-Pointing-Pointer Nananoparticle promote grain refinement to the weld structure. Black-Right-Pointing-Pointer 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.

  16. CO2 laser welding of aluminum alloys at high speeds up to 20 m/min

    Science.gov (United States)

    Takahashi, Kunimitsu; Kumagai, Mikio; Katayama, Seiji; Matsunawa, Akira

    2003-03-01

    CO2 laser welding of thin aluminum sheets was performed at welding speeds of up to 20 m/min to investigate the weldability, weld pool dynamics and mechanical properties of the weld bead of aluminum alloys. High-speed camera observation of weld areas showed that the thickness of the keyhole-front-face decreased to 100 μm under high-speed welding conditions and the weld pool became unstable. The focal length was optimized to increase the spot power density and thereby easily melt the aluminum sheets. Using a 76-mm focal length lens, which corresponds to 11 MW/cm2 power density, we obtained a keyhole mode weld bead with a depth of 1.3 mm at 20 m/min welding speed at 2 kW laser power. It was also possible to reduce the heat affected zone (HAZ) width to only 1.6 mm when the welding speed was 20 m/min. The HAZ width decreased as welding speed was increased. The tensile strength test of A6N01 weld beads showed that the fracture strength increased as the welding speed was increased up to 16 m/min, probably because the soft region of weld specimens was decreased. On the other hand, solidification cracks formed in the weld bead center at higher speeds, resulting in decreased strength.

  17. Mechanisms of the porosity formation during the fiber laser lap welding of aluminium alloy

    Directory of Open Access Journals (Sweden)

    J. Wang

    2015-10-01

    Full Text Available When joining the aluminum alloys, one of the biggest challenges is the formation of porosity, which deteriorates mechanical properties of welds. In this study, the lap welding was conducted on an aluminum alloy 5754 metal sheets with a thickness of 2 mm. The effects of various laser welding parameters on the weld quality were investigated. The porosity content was measured by X-ray inspections. The key is to control the solidification duration of molten pool. When the solidification duration of molten pool is large enough, more bubbles can escape from the molten pool and less remain as porosity.

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

    Science.gov (United States)

    Martukanitz, R. P.; Jan. R.

    1996-01-01

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

  19. Electron beam welding and laser welding of steam generator tubes made of alloy 800

    International Nuclear Information System (INIS)

    The electron beam welding conditions are optimized for different thermal cycles and chemical compositions of the fusion zone. The metallurgical and mechanical properties of the joints are described and compared with the properties of laser and TIG welds

  20. Microstructure and superplasticity of laser welded Ti-6Al-4V alloy

    International Nuclear Information System (INIS)

    In this paper laser beam welding (LBW) was used to join Ti-6Al-4V alloy as a pre-forming operation before superplastic deformation (SPF) process. Superplastic deformation behavior of laser welded Ti-6Al-4V alloy was investigated. The results indicated that the welded Ti-6Al-4V alloy had good superplasticity when deformed at temperature range of 870-920 oC and strain rate range of 10-3-10-2 s-1, and the elongation was 233-397%. The microstructure observation indicated that dynamic recrystallization happened in the weld bead, and the acicular structure of weld bead was transforming into equiaxed grains during tensile process.

  1. Mechanism of laser welding on dissimilar metals between stainless steel and W-Cu alloy

    Institute of Scientific and Technical Information of China (English)

    Kai Chen; Zhiyong Wang; Rongshi Xiao; Tiechuan Zuo

    2006-01-01

    @@ CO2 laser is employed to join a piece of powder metallurgical material (PMM) to a stainless steel in butt joint welding mode. The powder Ni35, as a filler powder, is used. The weld metal comes from three parts of stainless steel, powder Ni35, and Cu in W-Cu PMM. It is indicated that some parts of the W-Cu base metal are heated by laser and the metal Cu at the width of 0.06-0.12 mm from the edge is melted into the melting pool in the laser welding process. The formation of firm weld joint is just because that the melting liquid metal could fill the position occupied by metal Cu and surround the metal W granules fully. The analysis results indicate that the mechanism of the laser welding for stainless steel and W-Cu alloy is a special mode of fusion-brazing welding.

  2. Effects on mechanical properties in electron beam welding of TC4 alloy by laser shock processing

    Institute of Scientific and Technical Information of China (English)

    LU Jinzhong; ZHANG Yongkang; KONG Dejun; REN Xudong; GE Tao; ZOU Shikun

    2007-01-01

    The surface of TC4 titanium alloy welding line by electron beam welding (EBW) was processed by high power Q-switched and repetition-rate Nd: glass laser. Effects of laser power and spot diameter on residual stress and microhardness of the TC4 alloy welding line by laser shock processing (LSP) have been analyzed. Results show that residual stresses almost do not change as laser poweris 45.9 J,spot diameter is φ9 mm; While laser power is 45.9 J, spot diameter less than φ3 mm, the distribution of residual stress in welding line occurs obvious variation, which residual stress increase obviously with spot diameter decrease. When power density is bigger than 1.8×1010W/cm2, residual stresses of electron beam welding line occur change by LSP,which improve obviously residual stress distribution; while laser power is bigger than 1.2×1010W/cm2, the surface micro-hardness of electron beam welding line occurs change by LSP, which improve obviously micro-hardness distribution. Mechanical properties of TC4 titanium alloy welding line will be improved by LSP, which provides experimental foundation for further controlling the distributions of residual stress and micro-hardness during laser shock processing.

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

    OpenAIRE

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

    2013-01-01

    Friction Stir Welding (FSW) is a solid-state joining process; i.e., no melting occurs. The welding process is promoted by the rotation and translation of an axis-symmetric non-consumable tool along the weld centerline. Thus, the FSW process is performed at much lower temperatures than conventional fusion welding, nevertheless it has some disadvantages. Laser Assisted Friction Stir Welding (LAFSW) is a combination in which the FSW is the dominant welding process and the laser pre-heats the we...

  4. Microstructure and hot tearing of 6000 series aluminium alloys laser welds

    OpenAIRE

    Fabregue, Damien

    2004-01-01

    There has been a rapid growth in the use of the laser welding process due to its higher productivity rate compared to conventional processes. However its development in the field of aluminium alloys has been limited due to the presence of solidification defects (e.g. porosity, hot cracking). This study is focused on the understanding of the problem of hot cracking during welding. Numerous welding tests were done under different conditions, followed by microstructural examinations so as to und...

  5. Investigation of the technology of laser welding of aluminum alloy 1424

    Science.gov (United States)

    Annin, B. D.; Fomin, V. M.; Antipov, V. V.; Ioda, E. N.; Karpov, E. V.; Malikov, A. G.; Orishich, A. M.; Cherepanov, A. N.

    2015-12-01

    In this study, certain technological variants of the laser welding of alloy 1424 of the Al-Mg-Li-Zr system are considered with the purpose of obtaining the durability level of the welded joint, which is close to that of the basic metal. It is shown that, in the case of using various types of plastic deformation of the welded joint, its durability can be increased considerably to 0.85-0.95 from that of the basic metal.

  6. Simulation of YAG pulse laser welding of titanium alloy (TA6V)

    OpenAIRE

    Robert, Yannick

    2007-01-01

    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, precipitation...) and modifies the mechanical properties. Thermomechanical modelling has thus to be established for the welding of TA6V. In this study, we ...

  7. Effect of Laser Welding Parameters on Formation of NiTi Shape Memory Alloy Welds

    OpenAIRE

    Wei Wang(College of William and Mary); Xiaohong Yang; Hongguang Li; Fuzhong Cong; Yongbing Liu

    2014-01-01

    In this work experimental trials of welding of NiTi flat plates with 2.0 mm thickness were conducted using a 4.5 kW continuous wave (CW) Nd:YAG laser. The influences of laser output power, welding speed, defocus amount and side-blow shielding gas flow rate on the morphology, welding depth and width, and quality of the welded seam were investigated. Meanwhile, the effects of heat input on the mechanical and functional properties of welded joints were studied. The results show that laser weldin...

  8. Improvements of welding characteristics of aluminum alloys with YAG laser and TIG arc hybrid system

    Science.gov (United States)

    Fujinaga, Shigeki; Ohashi, Ryoji; Katayama, Seiji; Matsunawa, Akira

    2003-03-01

    In high power YAG laser welding of steels, a rectangularly modulated beam with high peak power is usually used to get deep penetration. On the other hand, many spatters and solidification cracks are generated when some aluminum alloys are welded with a rectangularly modulated beam because of its high heat conductivity, high reflectivity, low surface tension, large contraction, wide solidification temperature range, etc. Therefore, a properly modulated beam or a continuous beam is usually used in aluminum alloy welding, although the penetration depth is shallow. In this research, sinusoidal wave or rectangularly modulated wave of YAG laser combined with TIG arc was tried to improve the weldability of A6061 aluminum alloy. As a result, when TIG arc was superimposed behind the YAG laser beam, deeply penetrated weld beads with good surface appearances were produced without spatter losses and cracks.

  9. A study of laser and electron beam welding of Nb-1Zr-0.1C alloy

    International Nuclear Information System (INIS)

    The Nb-1Zr-0.1C alloy is one of the most promising refractory metal alloys, having an excellent combination of high temperature properties and is suitable for several structural applications in the proposed Compact High Temperature Reactor (CHTR). The application calls for the welding of this alloy to itself in different shapes and sizes. Due to reactive nature of this alloy proper precautions are necessary during its welding. In comparison to the conventional welding processes, the high energy density sources like, laser and electron beam which can produce deep penetrations with narrow heat affected zones are more suitable techniques to weld the components of this Nb-alloy. A systematic study was conducted for the development of laser and electron beam welding of the Nb-1Zr-0.1C alloy. The specimens of this alloy were welded using both processes in bead on plate and butt joint configuration by systematically varying the process parameters like power, travel speed and welding atmosphere and their effects on the weld quality, such as visual appearance of weld, depth and width of the weld, weld defects like crack, porosity, etc. were studied. The metallurgical characterization (optical and electron microscopic examination) of the weld joints produced by both techniques and the microhardness profile across the width of welds was also studied. The detailed results of the optimization of welding parameters and the characterization of the weld joints are discussed in this paper. (author)

  10. Laser-welded V-Cr-Ti alloys: Microstructure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Smith, D.L.; Xu, Z.; Leong, K.H. [Argonne National Lab., IL (United States)

    1998-09-01

    A systematic study has been in progress at Argonne National Laboratory to examine the use of YaG or CO{sub 2} lasers to weld sheet materials of V-Cr-Ti alloys and to characterize the microstructural and mechanical properties of the laser-welded materials. In addition, several postwelding heat treatments are being applied to the welded samples to evaluate their benefits, if any, to the structure and properties of the weldments. Hardness measurements are made across the welded regions of different samples to evaluate differences in the characteristics of various weldments. Several weldments were used to fabricate specimens for four-point bend tests. Several additional weldments were made with a YaG laser; here, the emphasis was on determining the optimal weld parameters to achieve deep penetration in the welds. A preliminary assessment was then made of the weldments on the basis of microstructure, hardness profiles, and defects.

  11. Laser-welded V-Cr-Ti alloys: Microstructure and mechanical properties

    International Nuclear Information System (INIS)

    A systematic study has been in progress at Argonne National Laboratory to examine the use of YaG or CO2 lasers to weld sheet materials of V-Cr-Ti alloys and to characterize the microstructural and mechanical properties of the laser-welded materials. In addition, several postwelding heat treatments are being applied to the welded samples to evaluate their benefits, if any, to the structure and properties of the weldments. Hardness measurements are made across the welded regions of different samples to evaluate differences in the characteristics of various weldments. Several weldments were used to fabricate specimens for four-point bend tests. Several additional weldments were made with a YaG laser; here, the emphasis was on determining the optimal weld parameters to achieve deep penetration in the welds. A preliminary assessment was then made of the weldments on the basis of microstructure, hardness profiles, and defects

  12. Laser welding of TiNi shape memory alloy and stainless steel using Ni interlayer

    International Nuclear Information System (INIS)

    Highlights: ► Laser welding was achieved using Ni interlayer between TiNi SMA and stainless steel. ► Ni interlayer thickness has great effects on joint microstructure and properties. ► Increasing Ni interlayer thickness results in increasing γ-Fe phase in weld metals. ► Excessive addition of Ni results in forming more TiNi3 and pores in the weld metals. ► Suitable Ni interlayer thickness improves the joint quality. -- Abstract: Laser welding of TiNi shape memory alloy wire to stainless steel wire using Ni interlayer was investigated. The results indicated that the Ni interlayer thickness had great effects on the chemical composition, microstructure, gas-pore susceptibility and mechanical properties of laser-welded joints. With an increase of Ni interlayer thickness, the weld Ni content increased and the joint properties increased due to decreasing brittle intermetallic compounds (TiFe2 and TiCr2). The joint fracture occurred in the fusion zone with a brittle intermetallic compound layer. The tensile strength and elongation of the joints reached the maximum values (372 MPa and 4.4%) when weld Ni content was 47.25 wt.%. Further increasing weld Ni content resulted in decreasing the joint properties because of forming more TiNi3 phase, gas-pores and shrinkage cavities in the weld metals. It is necessary to select suitable Ni interlayer thickness (weld composition) for improving the mechanical properties of laser-welded joints.

  13. 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. PMID:27222751

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

    Science.gov (United States)

    Oyyaravelu, Ramachandran; Kuppan, Palaniyandi; Arivazhagan, Natarajan

    2016-01-01

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

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

    International Nuclear Information System (INIS)

    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)

  16. Effect of power distribution on the weld quality during hybrid laser welding of an Al-Mg alloy

    Science.gov (United States)

    Leo, P.; Renna, G.; Casalino, G.; Olabi, A. G.

    2015-10-01

    This paper treats of the analysis of the effect of arc and laser powers on the quality of the arc assisted fiber laser welding of an Al-Mg alloy in the butt configuration. Grain size, weld geometry defects, porosity, and magnesium loss were measured. Magnesium content of the fused zone decreased as the laser power increased while the porosity increased with laser power. Microhardness profiles and tensile properties were explained on the basis of the joint microstructure and defects and related to the power distribution. The porosity level and Mg content in the fused zone affected both tensile strength and ductility. The power distribution that stabilized the welding process and minimize the weld porosity was defined.

  17. Investigation on pulsed Nd:YAG laser welding of 49Ni–Fe soft magnetic alloy

    International Nuclear Information System (INIS)

    Highlights: ► In high temperature gradients, grains are oblong and coarse. ► Pulse overlap, duration time and focused beam diameter reduces penetration depth. ► Pulsed frequency increases heat input and decreases the penetration depth. ► Hot cracks produced due to weld pool shape and heat input induced during welding. ► Peak power density and pulse frequency determines weld crater and porosity. -- Abstract: Laser welding is one of the most popular methods for joining hot crack sensitive alloys and thin materials because of its low heat input and high heat intensity. In this study, a Nd:YAG pulsed micro laser machine with maximum 6 J pulse energy was used for joining 49Ni–Fe soft magnetic alloy. Welding of samples was carried out autogenously by changing the pulse duration, focused beam diameter, voltage, frequency and welding speed. All samples were bead on plate welded. Scanning electron microscopy (SEM), optical microscopy and microhardness measurements were used for survey of results. Results show that weld bead size and grain size increase with voltage and heat input increase with pulse frequency. However, weld penetration depth and weld craters reduce with pulse frequency. The study shows that the average peak power density and pulse frequency are two important parameters that results in the formation of weld crater and porosity in the weld zone. Formation of hot cracks in the weld metal depends on the weld pool shape. Cylindrical weld pools are sensitive to hot cracks. Therefore, in order to reduce hot cracks in the weld bead, it is necessary to decrease voltage and increase pulse duration time, focused beam diameter and pulse frequency.

  18. Laser welding of AZ31B magnesium alloy to Zn-coated steel

    International Nuclear Information System (INIS)

    Highlights: ► Magnesium alloy was successfully laser welded to Zn-coated steel. ► The joint strength exceeded 6000 N on a 25 mm wide specimen. ► A 450 nm thick layer of Fe3Al was uniformly formed on the steel surface. -- Abstract: The characteristics of laser lap welding of AZ31B magnesium alloy to Zn-coated steel were investigated. Welding was difficult when the laser beam was irradiated onto the AZ31B alloy and the processing parameters were set to obtain a keyhole welding mode. The difference in the physical properties between the two materials resulted in unstable welding process particularly when the laser beam penetrated into the steel specimen and a keyhole was formed therein. By switching to a conduction mode, the process stability was improved and successful welding could be achieved because the liquid metal film remained unbroken and the laser beam did not penetrate into the material. A 25 mm wide joint failed in tensile shear testing at loads exceeding 6000 N. This high joint strength was attributed to the formation of a 450 nm thick layer of Fe3Al intermetallic compound on the steel surface as a result of the interaction between Al from the AZ31B alloy and Fe. The presence of Zn-coating layer was essential to eliminate the negative effects of oxides on the joining process.

  19. Temporal pulse shaping: a key parameter for the laser welding of dental alloys.

    Science.gov (United States)

    Bertrand, Caroline; Poulon-Quintin, Angeline

    2015-07-01

    This study aims to describe the effect of pulse shaping on the prevention of internal defects during laser welding for two dental alloys mainly used in prosthetic dentistry. Single spot, weld beads, and welds with 80 % overlapping were performed on Co-Cr-Mo and Pd-Ag-Sn cast plates with a pulsed neodymium-doped yttrium aluminum garnet (Nd:YAG) laser. A specific welding procedure using adapted parameters to each alloy was completed. All the possibilities for pulse shaping were tested: (1) the square pulse shape as a default setting, (2) a rising edge slope for gradual heating, (3) a falling edge slope to slow the cooling process, and (4) a combination of rising and falling edges. The optimization of the pulse shape is supposed to produce defect-free welds (crack, pores, voids). Cross-section SEM observations and Vickers microhardness measurements were made. Pd-Ag-Sn was highly sensitive to hot cracking, and Co-Cr-Mo was more sensitive to voids and small porosities (sometimes combined with cracks). Using a slow cooling ramp allowed a better control on the solidification process for those two alloys always preventing internal defects. A rapid slope should be preferred for Co-Cr-Mo alloys due to its low-laser beam reflectivity. On the opposite, for Pd-Ag-Sn alloy, a slow rising slope should be preferred because this alloy has a high-laser beam reflectivity. PMID:24913424

  20. Low Speed Laser Welding of Aluminium Alloys Using Single-Mode Fiber Lasers

    OpenAIRE

    Tu, Jay; Paleocrassas, Alexander

    2010-01-01

    In this chapter, topics related to extending fiber laser welding of aluminium in the low speed range were discussed. General topics, such as the properties of aluminium and welding defects, review of high speed laser welding of aluminium, and fiber laser characteristics and optical setups for safety, were first reviewed. Recent research results on the modelling and validation of laser welding of aluminium, experimental characterization of low speed welding processes, and the instability pheno...

  1. Effects of welding speed on the microstructures and mechanical properties of laser welded AZ61 magnesium alloy joints

    International Nuclear Information System (INIS)

    In this paper, the effects of welding speed on the microstructures and mechanical properties of laser welded AZ61 magnesium alloy plates were investigated by microstructural observations, microhardness tests and tensile tests. The results show that the microstructure in the fusion zone consisted of fine α-Mg equiaxed dendrite crystals and dispersed β-Mg17Al12 particles. With an increase in welding speed, the sizes of α-Mg grains and β-Mg17Al12 particles in the fusion zone decreased and the volume fraction of β-Mg17Al12 particles increased. The ultimate tensile strength, yield strength and elongation of welded joint increased when the welding speed increased from 1800 mm min−1 to 2800 mm min−1. In addition, the average hardness value of fusion zone and heat-affected zone increased with the increase in welding speed

  2. Effects of welding speed on the microstructures and mechanical properties of laser welded AZ61 magnesium alloy joints

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Jun, E-mail: shenjun@cqu.edu.cn; Wen, Libiao; Li, Yang; Min, Dong

    2013-08-20

    In this paper, the effects of welding speed on the microstructures and mechanical properties of laser welded AZ61 magnesium alloy plates were investigated by microstructural observations, microhardness tests and tensile tests. The results show that the microstructure in the fusion zone consisted of fine α-Mg equiaxed dendrite crystals and dispersed β-Mg{sub 17}Al{sub 12} particles. With an increase in welding speed, the sizes of α-Mg grains and β-Mg{sub 17}Al{sub 12} particles in the fusion zone decreased and the volume fraction of β-Mg{sub 17}Al{sub 12} particles increased. The ultimate tensile strength, yield strength and elongation of welded joint increased when the welding speed increased from 1800 mm min{sup −1} to 2800 mm min{sup −1}. In addition, the average hardness value of fusion zone and heat-affected zone increased with the increase in welding speed.

  3. Microstructural and mechanical characterization of laser beam welded AA6056 Al-alloy

    International Nuclear Information System (INIS)

    Highlights: → High quality joints were obtained in laser beam welding of 6056 Al-alloy using AlSi12 filler wire. → A decrease in the strength of HAZ due to overaging was detected. → The strength of the FZ was restored to the level of the HAZ by using Si-containing filler wire. → Intergranular crack propagation was detected in the TL-welded specimens. → The presence of porosity retards the crack propagation provided that they are small in size. - Abstract: Laser beam welding is considered to be a suitable joining process for high speed, low distortion, and high quality fabrication of aircraft structures manufactured from aluminum alloys, which are mainly preferred due to their favourable properties, such as high strength to weight ratio, ease of forming and high thermal and electrical conductivity. However, the laser beam welding of 6000 series aluminum alloys may exhibit a tendency to solidification cracking, and porosity may be a major problem unless appropriate welding parameters and filler metal are employed. In this study, the microstructural aspects and mechanical properties of laser beam welded new generation aluminum alloy, namely 6056, developed especially for aircraft structures, are investigated. A continuous wave CO2 laser using AlSi12 filler wire was employed. A detailed microstructural examination of the weld region was carried out by Scanning Electron Microscopy (SEM). Standard tensile and microflat tensile specimens extracted from the welded plates were tested at room temperature for the determination of general and local mechanical properties of the welded joints. Extensive microhardness measurements were also conducted. Crack growth mechanisms of the joints produced were also determined by conducting fatigue tests under various stress ratios (i.e., 0.1 ≤ R ≤ 0.7).

  4. Characterisation of texture in Ti-6246 alloy fibre laser welds using Electron Backscattered Diffraction (EBSD)

    International Nuclear Information System (INIS)

    In this study, fibre laser welds of alloy Ti-6%Al-2%Sn-4%Zr-6%Mo have been characterised. It has been found that although the microstructure of the welds is important in predicting properties, it is not enough to simply characterise the welds based on the microstructure, as crystallographic texturing is also important in determining mechanical properties. The texturing of the fibre laser welds is being characterized using EBSD mapping, with light microscopy to characterize the microstructure. This has been carried out for a weld that has been heat treated for 3 hours at 550 deg. C. At this temperature, relaxation of residual stress will occur, but changes to the microstructure will be minimal. It is planned that EBSD will now be carried out on the as received sample, and the results will be presented, along with a comparison with the heat treated weld

  5. Microstructure and tensile properties of laser beam welded Ti–22Al–27Nb alloys

    International Nuclear Information System (INIS)

    Highlights: ► A well-quality joint is obtained by laser beam welding Ti–22Al–27Nb alloys. ► The weld metal only consists of B2 phase. ► The tensile strength of the joints is 94% of the base metal at room temperature. ► Limited number of O phase slip systems causes the ductility loss at 650 °C. - Abstract: Ti–22Al–27Nb alloys were welded using the laser beam welding process. The microstructure characterization and the tensile properties of the laser beam welded joints were investigated. The experimental results showed that a well-quality joint could be obtained using laser beam welding method. The fusion zone of the welded joint was composed of B2 phase. The tensile strength of the joints at room temperature was basically comparable to that of the base metal and the tensile ductility of the joints achieved 56% of the base metal. The average tensile strength of the welded joints at 650 °C was tested to be about 733 MPa, with the elongation of 2.93%

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

    Institute of Scientific and Technical Information of China (English)

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

    2009-01-01

    The influence of welding parameters on mechanical properties and microstructure of the welds of laser-TIG double-side welded 5A06 aluminum alloy was investigated. The results show that the weld cross-sectional shape has an intimate relation with the mechanical properties and microstructure of the welds. The symmetrical "X" cross-section possesses a relatively higher tensile strength and elongation than the others, about 91% and 58% of those of base metal, respectively. The good weld profiles and free defects are responsible for the improvement of tensile properties. Due to low hardness of the fusion zone, this region is the weakest area in the tensile test and much easier to fracture. The loss of Mg element is responsible for the decrease of mechanical properties of the joints. The microstructure of "X" cross-section has an obvious difference along the direction of weld depth, and that of the "H" cross-section is consistent and coarse.

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

    International Nuclear Information System (INIS)

    Research highlights: → Ti-Al-Zr-Fe titanium alloy sheets were welded by LBW and LAMIG methods. → LAMIG welded joints have better combination of strength and ductility. → LAMIG welding is proved to be feasible for the production of titanium sheet joints. - Abstract: Ti-Al-Zr-Fe titanium alloy sheets with thickness of 4 mm were welded using laser beam welding (LBW) and laser-MIG hybrid welding (LAMIG) methods. To investigate the influence of the methods difference on the joint properties, optical microscope observation, microhardness measurement and mechanical tests were conducted. Experimental results show that the sheets can be welded at a high speed of 1.8 m/min and power of 8 kW, with no defects such as, surface oxidation, porosity, cracks and lack of penetration in the welding seam. In addition, all tensile test specimens fractured at the parent metal. Compared with the LBW, the LAMIG welding method can produce joints with higher ductility, due to the improvement of seam formation and lower microhardness by employing a low strength TA-10 welding wire. It can be concluded that LAMIG is much more feasible for welding the Ti-Al-Zr-Fe titanium alloy sheets.

  8. Microstructure and properties of welds between 5754 Al alloys and AZ31 Mg alloys using a Yb:YAG laser

    Science.gov (United States)

    Bannour, Sana; Autric, Michel; Masse, Jean-Eric; Mattei, Simone; Mhiri, Hatem

    2015-02-01

    Dissimilar laser beam welding between A5754 Al alloys and AZ31 Mg alloys with the plate thickness of 2 mm was investigated. Complex flow pattern characterized by a large volume of intermetallic compounds Al12Mg17 and Al3Mg2 is formed in the fusion zone. Microhardness measurement of the dissimilar welds presents an uneven distribution due to the complicated microstructure of the weld, and the maximum value of microhardness in the fusion zone is much higher than of the base materials.

  9. Microstructure and properties of welds between 5754 Al alloys and AZ31 Mg alloys using a Yb:YAG laser

    OpenAIRE

    BANNOUR, Sana; Autric, Michel; MASSE, Jean-Eric; MATTEÏ, Simone; Mhiri, Hatem

    2014-01-01

    Dissimilar laser beam welding between A5754 Al alloy and AZ31 Mg alloy with the plate thickness of 2 mm was investigated. Complex flow pattern characterized by a large volume of intermetallic compounds Al12Mg17 and Al3Mg2 is formed in the fusion zone. Microhardness measurement of the dissimilar welds presents an uneven distribution due to the complicated microstructure of the weld, and the maximum value of microhardness in the fusion zone is much higher than of the base materials.

  10. Welding of refractory alloys

    International Nuclear Information System (INIS)

    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

  11. The influence of heat treatment on the properties of laser welded Al-Li alloy

    International Nuclear Information System (INIS)

    An Al-Li-Cu-Mg-Zr alloy was welded with CO2 laser to produce full-penetration, single pass butt welds. Initial YS of 487 MPa for unwelded material decreased to 268 MPa after laser welding as well as the measured elongation decreased from 17.48% to 3.7% respectively. The postweld heat treatment consisting of solutionizing at 550 oC for 2 h and/or artificial aging at 150, 175, 200 and 225oC for 2, 4, 8, 16 and 32 h were performed to improve the properties of welded material. Studies by optical, scanning and transmission electron microscopes were provided in: as-welded, as-heat-treated and as-deformed states to show the microstructural changes with postweld heat treatment. (author)

  12. High power fiber laser arc hybrid welding of AZ31B magnesium alloy

    International Nuclear Information System (INIS)

    Highlights: ► Fiber laser–metal inert gas arc hybrid welding of AZ31B Mg alloy was developed. ► The maximum tensile strength efficiency of 5 mm thick welds is up to 109%. ► Grain size of fusion zone and width of PMZ both increase with heat input. ► Hall–Petch relationship between microhardness and grain size is obtained. ► Strength difference between 5 mm and 8 mm thick welds is summarized and discussed. -- Abstract: High power fiber laser–metal inert gas arc hybrid welding of AZ31B magnesium alloy was studied. The fusion zone consisted of hexagonal dendrites, where the secondary particle of Al8Mn5 was found at the center of dendrite as a nucleus. Within hybrid weld, the arc zone had coarser grain size and wider partial melted zone compared with the laser zone. The tensile results showed the maximum strength efficiency of 5 mm thick welds was up to 109%, while that of 8 mm thick welds was only 88%. The fracture surface represented a ductile–brittle mixed pattern characterized by dimples and quasi-cleavages. On the fracture surface some metallurgical defects of porosity and MgO inclusions around with secondary cracks were observed. Meanwhile, a strong link between the joint strength and weld porosity were demonstrated by experimental results, whose relevant mechanism was discussed by the laser–arc interaction during hybrid welding.

  13. The fatigue life of a cobalt-chromium alloy after laser welding.

    Science.gov (United States)

    Al-Bayaa, Nabil Jalal Ahmad; Clark, Robert K F; Juszczyk, Andrzej S; Radford, David R

    2011-03-01

    The aim of this study was to investigate the fatigue life of laser welded joints in a commercially available cast cobalt-chromium alloy. Twenty rod shaped specimens (40 mm x 1.5 mm) were cast and sand blasted. Ten specimens were used as controls and the remaining ten were sectioned and repaired using a pulsed Nd: YAG laser welder. All specimens were subjected to fatigue testing (30N - 2Hz) in a controlled environment. A statistically significant difference in median fatigue life was found between as-cast and laser welded specimens (p < 0.001). Consequently, the technique may not be appropriate for repairing cobalt chromium clasps on removable partial dentures. Scanning electron microscopy indicated the presence of cracks, pores and constriction of the outer surface in the welded specimens despite 70% penetration of the weld. PMID:21528682

  14. A comparative study of pulsed Nd:YAG laser welding and TIG welding of thin Ti6Al4V titanium alloy plate

    International Nuclear Information System (INIS)

    This paper reports on a study aiming at comparing properties of the Ti6Al4V titanium alloy joints between pulsed Nd:YAG laser welding and traditional fusion welding. To achieve the research purpose, Ti6Al4V titanium alloy plates with a thickness of 0.8 mm were welded using pulsed Nd:YAG laser beam welding (LBW) and gas tungsten arc welding (TIG), respectively. Residual distortions, weld geometry, microstructure and mechanical properties of the joints produced with LBW and TIG welding were compared. During the tensile test, with the aid of a high speed infrared camera, evolution of the plastic strain within tensile specimens corresponding to LBW and TIG welding were recorded and analyzed. Compared with the TIG, the welded joint by LBW has the characters of small overall residual distortion, fine microstructure, narrow heat-affected zone (HAZ), high Vickers hardness. LBW welding method can produce joints with higher strength and ductility. It can be concluded that Pulsed Nd:YAG laser welding is much more suitable for welding the thin Ti6Al4V titanium alloy plate than TIG welding.

  15. A comparative study of pulsed Nd:YAG laser welding and TIG welding of thin Ti6Al4V titanium alloy plate

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Xiao-Long [State Key Laboratory of Mechanical Behavior for Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Zhang, Lin-Jie, E-mail: zhanglinjie@mail.xjtu.edu.cn [State Key Laboratory of Mechanical Behavior for Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Liu, Jing; Zhang, Jian-Xun [State Key Laboratory of Mechanical Behavior for Materials, Xi' an Jiaotong University, Xi' an 710049 (China)

    2013-01-01

    This paper reports on a study aiming at comparing properties of the Ti6Al4V titanium alloy joints between pulsed Nd:YAG laser welding and traditional fusion welding. To achieve the research purpose, Ti6Al4V titanium alloy plates with a thickness of 0.8 mm were welded using pulsed Nd:YAG laser beam welding (LBW) and gas tungsten arc welding (TIG), respectively. Residual distortions, weld geometry, microstructure and mechanical properties of the joints produced with LBW and TIG welding were compared. During the tensile test, with the aid of a high speed infrared camera, evolution of the plastic strain within tensile specimens corresponding to LBW and TIG welding were recorded and analyzed. Compared with the TIG, the welded joint by LBW has the characters of small overall residual distortion, fine microstructure, narrow heat-affected zone (HAZ), high Vickers hardness. LBW welding method can produce joints with higher strength and ductility. It can be concluded that Pulsed Nd:YAG laser welding is much more suitable for welding the thin Ti6Al4V titanium alloy plate than TIG welding.

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

    International Nuclear Information System (INIS)

    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.

  17. Superplastic solid state welding steel and copper alloy based on laser quenching of steel surface

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ke-ke; HAN Cai-xia; QUAN Shu-li; CHENG Guang-hui; YANG Jie; YANG Yun-lin

    2005-01-01

    Based on the feasibility of isothermal superplastic solid state welding of steel and copper alloy, the welded surface of steel surface was ultra-fined through laser quenching, and then the welding process tests between different base metals of 40Cr and QCr0.5 were made under the condition of non vacuum and non shield gas. The experimental results show that, with the sample surface of steel after laser quenching and that of copper alloy carefully cleaned, and under the pre-pressed stress of 56.6 -84.9 MPa, at the welding temperature of 750 -800 ℃ and at initial strain rate of (2.5 - 7.5) × 10-4 s-1 , the solid state welding can be finished in 120 - 180 s so that the strength of the joint is up to that of QCr0.5 base metal and the expansion rate of the joint does not exceed 6%. The plastic deformation of the joint was further analysed. The superplastic deformation of the copper alloy occurs in welding process and the deformation of steel are little.

  18. Microstructure and mechanical properties of wrought magnesium alloy AZ31B welded by laser-TIG hybrid

    Institute of Scientific and Technical Information of China (English)

    刘黎明; 宋刚; 王继锋; 梁国俐

    2004-01-01

    The laser-TIG hybrid welding was mainly used to weld the wrought magnesium alloy AZ31B. The technical characteristics of laser-TIG hybrid welding process was investigated and the interactional mechanism between laser and arc was discussed, at the same time the microstructure and mechanical properties of the wrought magnesium alloy AZ31B using laser-TIG hybrid welding were analyzed by optical microscope, EPMA, SEM, tensile machine, hardness machine. The experimental results show that the presence of laser beam boosts up the stability of the arc during high speed welding and augments the penetration of weld; the crystal grains of magnesium alloy weld are fine without porosity and cracks in the best welding criterion and the microstructure of HAZ does not become coarse obviously. The elements profile analysis reveals that Mg content in the weld is lower than that of the base metal, but Al content is higher slightly. Under this experimental condition, the wrought magnesium alloy AZ31B joint can be achieved using laser-TIG hybrid process and the tensile strength of the joint is equivalent to that of the base metal.

  19. Effect of laser irradiation conditions on the laser welding strength of cobalt-chromium and gold alloys.

    Science.gov (United States)

    Kikuchi, Hisaji; Kurotani, Tomoko; Kaketani, Masahiro; Hiraguchi, Hisako; Hirose, Hideharu; Yoneyama, Takayuki

    2011-09-01

    Using tensile tests, this study investigated differences in the welding strength of casts of cobalt-chromium and gold alloys resulting from changes in the voltage and pulse duration in order to clarify the optimum conditions of laser irradiation for achieving favorable welding strength. Laser irradiation was performed at voltages of 150 V and 170 V with pulse durations of 4, 8, and 12 ms. For cobalt-chromium and gold alloys, it was found that a good welding strength could be achieved using a voltage of 170 V, a pulse duration of 8 ms, and a spot diameter of 0.5 mm. However, when the power density was set higher than this, defects tended to occur, suggesting the need for care when establishing welding conditions. PMID:21959656

  20. Characterization and formation mechanism of laser-welded Mg and Al alloys using Ti interlayer

    International Nuclear Information System (INIS)

    Ti was used as an interlayer to join Mg and Al alloys by fiber laser welding. The formation of Mg–Al intermetallic compounds could be totally suppressed and the interfacial layer was composed of Al3Ti and small amounts of Al18Ti2Mg3. The mechanism of interfacial layer formation was attributed to the thermodynamic behavior of the formation of intermetallic compounds in Al–Mg–Ti ternary system and to precise control of the laser power.

  1. Study of laser and electron beam welding of Nb-1Zr-0.1C and TZM alloys

    International Nuclear Information System (INIS)

    The refractory metal alloys Nb-1Zr-0.1C and TZM (0.5 Ti-0.08 Zr-0.04 C) having an excellent combination of high temperature properties; which makes them suitable for structural applications in advanced nuclear reactors operating at high temperature.The applications of these alloys call for their welding in different forms and shapes. Due to their high melting point, thermal conductivity and reactive nature; welding of these alloys is challenging and difficult task. The high energy density welding techniques like laser and electron beam (EB) capable of producing deep penetration welds with minimal heat affected zone (HAZ) are more suitable for welding of these alloys. Both the techniques had some advantages and limitations which need to be studied. The autogeneous laser (Nd:YAG) and EB welds in bead-on-plate (BOP) and butt joint configuration were produced on sheets of Nb-1Zr-0.1C and TZM alloy by systematically varying the process parameters. The laser and EB welds produced on sheets of Nb-1Zr-0.1C alloy were subjected to optical and electron microscopic examination and were characterized in detailed by studying their weld profiles, optical and SEM micrographs of the weld zone and HAZ

  2. MIG welding and laser welding of die castings with welded profiles in aluminium alloys; Soudage MIG et soudage laser de pieces moulees sous pression avec des profils corroyes en alliages d'aluminium

    Energy Technology Data Exchange (ETDEWEB)

    Wiesner, S.; Rethmeier, M.; Wohlfahrt, H. [Brunswick Univ. Technique, Institut de Soudure (Germany)

    2003-11-01

    The welding of die castings offers a new perspective for the realization of complex structures of weak mass. For this reason, the use of die castings assembled by welding is currently a theme of research in the automotive industry. The welding of die castings is the most appropriate method for aluminium alloys. The MIG welding (metal inert gas welding) and TIG welding (tungsten inert gas welding) can be used for die castings with a lower gas amount. The use of laser welding is possible in the case where the process of die casting is optimized for the realization of castings with a very low gas amount. The laser-TIG welding is a method which has very specific advantages for die castings in aluminium alloys. The researches which are currently in progress reveal the very important influence of the type of aluminium alloy on the weldability of die castings. The alloys as AlSi seem to be better appropriate than the AlMg alloys for obtaining weldings of high qualities for die castings. (O.M.)

  3. Microstructures and mechanical property of laser butt welding of titanium alloy to stainless steel

    International Nuclear Information System (INIS)

    Highlights: • The laser direct butt welding of titanium alloy to stainless steel is realized. • The interfacial microstructures of the joints are confirmed. • The weldability is better when laser beam is offset toward titanium than steel. • The highest tensile strength of the joint reaches to 150 MPa. - Abstract: Laser butt welding of titanium alloy to stainless steel was performed. The effect of laser-beam offsetting on microstructural characteristics and fracture behavior of the joint was investigated. It was found that when the laser beam is offset toward the stainless steel side, it results in a more durable joint. The intermetallic compounds have a uniform thickness along the interface and can be divided into two layers. One consists of FeTi + α-Ti, and other consists of FeTi + Fe2Ti + Ti5Fe17Cr5. When laser beam is offset by 0 mm and 0.3 mm toward the titanium alloy side, the joints fracture spontaneously after welding. Durable joining is achieved only when the laser beam is offset by 0.6 mm toward the titanium alloy. From the top to the bottom of the joint, the thickness of intermetallic compounds continuously decreases and the following interfacial structures are found: FeAl + α-Ti/Fe2Ti + Ti5Fe17Cr5, FeAl + α-Ti/FeTi + Fe2Ti + Ti5Fe17Cr5 and FeAl + α-Ti, in that order. The tensile strength of the joint is higher when the laser beam is offset toward the stainless steel than toward the titanium alloy, the highest observed value being 150 MPa. The fracture of the joint occurs along the interface between two adjacent intermetallic layers

  4. Development of temper bead welding by under water laser welding

    International Nuclear Information System (INIS)

    Toshiba has developed temper bead welding by under water laser welding as SCC counter measure for aged components in PWR and BWR nuclear power plants. Temper bead welding by under water laser welding technique recovers toughness of low alloy steel reactor vessel by employing proper the number of cladding layers and their welding conditions. In this report, some evaluation results of material characteristics of temper bead welded low alloy steel are presented. (author)

  5. Numerical Analysis of Welding Residual Stress and Distortion in Laser+GMAW Hybrid Welding of Aluminum Alloy T-Joint

    Institute of Scientific and Technical Information of China (English)

    Guoxiang XU; Chuansong WU; Xuezhou MA; Xuyou WANG

    2013-01-01

    A 3-D finite element model is developed to predict the temperature field and thermally induced residual stress and distortion in laser+GMAW hybrid welding of 6061-T6 aluminum alloy T-joint.And the characteristics of residual stress distribution and deformation are numerically investigated.In the simulation,the heat source model takes into account the effect of joint geometric shape and welding torch slant on the heat flux distribution and a sequentially coupled thermo-mechanical method is used.The calculated results show that higher residual stress is distributed in and surround the weld zone.Its peak value is very close to the yield strength of base metal.Besides,a large deformation appears in the middle and rear part of the weldment.

  6. Laser-welded vs soldered nonprecious alloy dental bridges: a comparative study.

    Science.gov (United States)

    Apotheker, H; Nishimura, I; Seerattan, C

    1984-01-01

    The high cost of gold alloy has caused the dental profession to begin substituting nonprecious alloy for the framework in porcelain fused to metal bridges. Especially in long-span bridges it may be advantageous to make multiple castings and then join them for a better fit. As opposed to the highly successful soldering of gold, soldered nonprecious alloy bridges have a great failure rate in the mouth. Removal of and remaking of the bridges is thus the result. This study compares nonprecious units that have been laser-welded with those conventionally soldered. Seven identical bridges of three units were cast in a popular alloy composed of 74-78% nickel, 12-15% chromium, 4-6% molybdenum, and 1.8% maximum beryllium. One served as a control, while the remaining six were all cut in the same place. Of these, three were soldered with a gas oxygen torch. The other three were welded with a Nd-YAG laser. Better and stronger joints unlikely to fracture in the mouth were found with the laser-welded specimen. PMID:6147733

  7. Characteristics of plasma plume in fiber laser welding of aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Ming; Chen, Cong; Hu, Ming; Guo, Lianbo; Wang, Zemin, E-mail: zmwang@mail.hust.edu.cn; Zeng, Xiaoyan

    2015-01-30

    Highlights: • Spectroscopic properties of fiber laser induced Al plasma plume are measured. • The plume is usually a metal vapor dominated weakly ionized plasma. • The plume is a strongly ionized plasma after laser power is higher than 5 kW. • Plasma shielding effect must be considered after laser power reaches 5 kW. • Plasma shielding effect is dominated by inverse bremsstrahlung absorption. - Abstract: To understand the laser–matter interaction in fiber laser welding of aluminum alloys, the effects of laser power on the characteristics of fiber laser induced plasma plume were studied by emission spectroscopic analysis firstly. The plasma characteristic parameters including electron temperature, electron density, ionization degree, and inverse bremsstrahlung linear absorption coefficient were computed according to the spectral data. It was found that the laser power of 5 kW is a turning point. After the laser power reaches 5 kW, the plume changes from a metal vapor dominated weakly ionized plasma to a strongly ionized plasma. The corresponding phenomena are the dramatic increase of the value of characteristic parameters and the appearance of strong plasma shielding effect. The calculation of effective laser power density demonstrated that the plasma shielding effect is dominated by inverse bremsstrahlung absorption. The finding suggested the plasma shielding effect must be considered in fiber laser welding of aluminum alloys, rather than is ignored as claimed in previous view.

  8. Characteristics of plasma plume in fiber laser welding of aluminum alloy

    International Nuclear Information System (INIS)

    Highlights: • Spectroscopic properties of fiber laser induced Al plasma plume are measured. • The plume is usually a metal vapor dominated weakly ionized plasma. • The plume is a strongly ionized plasma after laser power is higher than 5 kW. • Plasma shielding effect must be considered after laser power reaches 5 kW. • Plasma shielding effect is dominated by inverse bremsstrahlung absorption. - Abstract: To understand the laser–matter interaction in fiber laser welding of aluminum alloys, the effects of laser power on the characteristics of fiber laser induced plasma plume were studied by emission spectroscopic analysis firstly. The plasma characteristic parameters including electron temperature, electron density, ionization degree, and inverse bremsstrahlung linear absorption coefficient were computed according to the spectral data. It was found that the laser power of 5 kW is a turning point. After the laser power reaches 5 kW, the plume changes from a metal vapor dominated weakly ionized plasma to a strongly ionized plasma. The corresponding phenomena are the dramatic increase of the value of characteristic parameters and the appearance of strong plasma shielding effect. The calculation of effective laser power density demonstrated that the plasma shielding effect is dominated by inverse bremsstrahlung absorption. The finding suggested the plasma shielding effect must be considered in fiber laser welding of aluminum alloys, rather than is ignored as claimed in previous view

  9. Alloying element losses in pulsed Nd : YAG laser welding of stainless steel 316

    International Nuclear Information System (INIS)

    Experimental studies of pulsed laser welding of stainless steel 316 in keyhole mode were done to examine a vaporization model based on the kinetic theory of gases and the thermodynamic laws. Undesirable loss of volatile elements affects the weld metal composition and properties. The profile of the keyhole was simulated as a function of time from a 'hydrodynamic' physical model. The power density and pulse duration were the main investigated variables. The model predicts that loss of alloying elements increases at higher peak powers and longer pulse durations. Accordingly, the concentrations of iron, chromium, nickel and manganese were determined in the weld pool by means of the proton-induced x-ray emission and energy dispersive x-ray/wavelength dispersive x-ray analysis. It was shown that the composition alteration, predicted by the model due to varying laser parameters, accords well with the corresponding experimental data.

  10. Hybrid laser-arc welding

    DEFF Research Database (Denmark)

    Hybrid laser-arc welding (HLAW) is a combination of laser welding with arc welding that overcomes many of the shortfalls of both processes. This important book gives a comprehensive account of hybrid laser-arc welding technology and applications. The first part of the book reviews...... the characteristics of the process, including the properties of joints produced by hybrid laser-arc welding and ways of assessing weld quality. Part II discusses applications of the process to such metals as magnesium alloys, aluminium and steel as well as the use of hybrid laser-arc welding in such sectors as ship...... 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...

  11. Development and application of high-precision laser welding technology for manufacturing Ti alloy frames of glasses

    International Nuclear Information System (INIS)

    The research and development efforts of the high precision laser welding technology for manufacturing titanium alloy frames of glasses. For this purpose, laser welding device with the high beam quality is designed and fabricated, which consists of a optical fiber transmission part, a welding monitoring part and a welding controller. The welding nozzle and holding fixtures for manufacturing titanium and shape memory alloy frames of glasses. Titanium and shape memory alloy frames of glasses to be developed were experimentally manufactured by utilizing the laser welding using the optical fiber of GI 400 μm. As a result, the seam welding with the bead width of 0.3 mm or less and the weld penetration of 0.3-0.4mm could be accomplished. The fundamental technology was established through design of welding jigs with a variety of configurations and adequate welding conditions. Also, for the purpose to enable the companies participating in this project to commercialize the developed technology acceleratedly, a training program for the engineers belonging to such companies was conducted along with the technology transfer through joint experiments with the engineers. (author)

  12. 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 ...

  13. Porosity evolution in aluminum alloy 2024 bop and butt defocused welding by Yb-YAG disk laser

    OpenAIRE

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

    2011-01-01

    In many industrial applications, in order to obtain good results in laser welding processes, it may not be sufficient to use a focused beam on the upper surface, so a defocused beam is required instead. This study aims to investigate which advantages a defocused beam may offer in welding aluminum alloy 2024 using Yb:YAG disk laser. A characterization of laser beam geometry is preliminary necessary, in order to correlate bead features and effective specific energy provided. Porosity content de...

  14. Direct observation of keyhole plasma characteristics in deep penetration laser welding of aluminum alloy 6016

    International Nuclear Information System (INIS)

    Deep penetration laser welding is associated with violent plasma generation which consists of metal vapour, ionized ions and electrons. The plasma resides both outside and inside the keyhole, known as the plasma plume and keyhole plasma, respectively. Plasma plumes have been studied extensively due to the convenience of observing them. However, very little work has been carried out on the investigation of keyhole plasmas. In this paper, a novel experimental set-up is designed to observe the keyhole plasma directly in CW and PW deep penetration laser welding of aluminum alloy 6016. Then on the basis of the experimentally obtained spectra, the electron temperature distribution of the keyhole plasma both in the radial and depth directions of the keyhole is calculated, and the effects of processing parameters such as laser power, welding velocity and defocus on the keyhole plasma temperature are studied. The results show that the electron temperature of the keyhole plasma both in the radial and depth directions is not uniformly distributed. The temperature increases as the laser power increases, decreases as the welding velocity increases and decreases as the location of the laser beam focal point is moved from within to above the keyhole. (paper)

  15. Hot cracking in Al-Mg-Si alloy laser welding - operating parameters and their effects

    International Nuclear Information System (INIS)

    Hot cracking is a phenomenon that frequently occurs in the laser welding of some 'special' alloys, such as the aluminium-magnesium-silicon type. Each occurrence of this phenomenon needs to be studied in itself, taking into account not only the individual, but also the interactive, influences of the various parameters. The advantage of using laser beams in welding processes lies in the speeds that can be reached. The disadvantage, however, is that, owing to the high cooling rates characteristic of the interaction between the laser beam and the material, the welding speed itself becomes a cause of hot cracking. The aim of this paper is to see how this disadvantage may be eliminated. We consider what the most important parameters may be, relating to tensile strength and the quantity of cracks produced, that might influence the presence or absence of hot cracking. The most influential factors in avoiding hot cracking are the welding speed and wire parameters. Also important is welding stability, as instability generates cracks. We can then determine a technological window, useful for industrial applications, which takes into account the values of these influential factors and stability

  16. Laser Welding Characterization of Kovar and Stainless Steel Alloys as Suitable Materials for Components of Photonic Devices Packaging

    International Nuclear Information System (INIS)

    The weldability of Kovar and stainless steel alloys by Nd:YAG laser beam is studied through changing of some laser beam parameters. It has been found that there is a suitable interaction of the pulsed laser beam of low power laser pulse with both the two alloys. The change of thermophysical properties with absorbed energy from the laser pulse is discussed in this paper which reports the suitability of both Kovar and stainless steel 304 as the base materials for photonic devices packaging. We used laser weld system (LW4000S from Newport) which employs Nd:YAG laser system with two simultaneous beams output for packaging 980 nm high power laser module. Results of changing both laser spot weld width and penetration depth with changing both the pulse peak power density, pulse energy and pulse duration show that there are good linear relationships between laser pulse energy or peak power density and pulse duration with laser spot weld dimensions( both laser spot weld width and penetration depth). Therefore we concluded that there should be an optimization for both the pulse peak power and pulse duration to give a suitable aspect ratio (laser spot width to penetration depth) for achieving the desired welds with suitable penetration depth and small spot width. This is to reduce the heat affected zone (HAZ) which affects the sensitive optical components. An optimum value of the power density in the order of 105 w/cm2 found to be suitable to induce melting in the welded joints without vaporization. The desired ratio can also be optimized by changing the focus position on the target material as illustrated from our measurements. A theoretical model is developed to simulate the temperature distribution during the laser pulse heating and predict the penetration depth inside the material. Samples have been investigated using SEM with EDS. The metallographic measurements on the weld spot show a suitable weld yield with reasonable weld width to depth ratio.

  17. 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.

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

    International Nuclear Information System (INIS)

    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 (Tm), 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.

  19. Hybrid laser-Metal Inert Gas welding of Al–Mg–Si alloy joints: Microstructure and mechanical properties

    International Nuclear Information System (INIS)

    Highlights: • Microstructure and mechanical properties of the welded joint have been investigated. • Reasons for the strength loss of the welded joint have been discussed. • The distribution of strengthening elements has been obtained using synchroton radiation X-rays. - Abstract: Hybrid fiber laser-Metal Inert Gas (MIG) welding is an advanced joining technology that is increasingly employed in the modern industry. In this paper, hybrid fiber laser-MIG welding was applied to join 5 mm thick AA6005-T5 alloy used in the carbody of high-speed railway vehicles. The mechanical properties of the hybrid welded joints were investigated. The results showed that the hybrid welded joints have more excellent mechanical properties than that of the MIG joints. However, there is still strength loss in the hybrid welded joins comparing with the base metal. The reason for the loss of the strength was studied from the aspects of microstructure and vaporization of strengthening elements

  20. 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.

  1. Superplastic deformation mechanism and mechanical behavior of a laser-welded Ti–6Al–4V alloy joint

    International Nuclear Information System (INIS)

    Highlights: ► The laser-welded joint was found to have good superplasticity. ► The deformation accompanied the globularizationglobularization of as-welded microstructure. ► The globularizationglobularization was governed by phase change and grain boundary sliding. - Abstract: The mechanical behavior and superplastic deformation mechanism of a laser-welded Ti–6Al–4V alloy joint were investigated. Uniaxial tensile tests were performed on welded specimens at 870–920 °C temperature and 10−3 to 10−1 s−1 strain rate. The microstructural evolution of the weld zone was observed under the strains of 43%, 143%, 229%, and 387%. The laser-welded joint was found to have good superplasticity under a suitable strain rate; the highest joint elongation reached 397%. Superplastic deformation in the weld zone accompanied the globularization of the as-welded microstructure. Continuous globularization ensured a good superplasticity of the laser-welded joint. As a major cause of the globularization of lamellar structures in the weld zone, the stress activated the diffusion of Al atoms by changing the chemical potential at the boundaries of the α phase. Consequently, α → β phase transformation occurred. The globularization of the as-weld microstructures was considered to be governed by this transformation and the development of grain boundary sliding.

  2. Hybrid laser/arc welding of advanced high strength steel to aluminum alloy by using structural transition insert

    International Nuclear Information System (INIS)

    Highlights: • A concept welding procedure was presented for joining dissimilar alloys. • Controlling of temperature improved mechanical properties. • Microstructure analysis showed presence of tempered martensite. • Optimum stand-off distance caused stability of molten pool. - Abstract: The present investigation is related to the development of the welding procedure of the hybrid laser/arc welding (HLAW) in joining thick dissimilar materials. The HLAW was applied to join aluminum alloy (AA6061) to an advanced high strength steel (AHSS) where an explosively welded transition joint, TRICLAD®, was used as an intermediate structural insert between the thick plates of the aluminum alloy and AHSS. The welds were characterized by an optical microscope, scanning electron microscope (SEM), tensile test, charged coupled device (CCD) camera, and microhardness measurement. The groove angle was optimized for the welding process based on the allowed amount of heat input along the TRICLAD® interface generated by an explosive welding. The weld was fractured in the heat affected zone of the aluminum side in the tensile test. The microhardness was shown that the temperature variation caused minor softening in the heat affected zone satisfying the requirement that the width of the softened heat affected zone in the steel side falls within 15.9 mm far away from the weld centerline. The microstructure analysis showed the presence of tempered martensite at the vicinity of the weld area, which it was a cause of softening in the heat affected zone

  3. Joining mechanism of Ti/Al dissimilar alloys during laser welding-brazing process

    International Nuclear Information System (INIS)

    Research highlights: → The microstructures of interfacial zones were confirmed in detail by transmission electron microscope (TEM). Interfacial reaction layers of brazing joint were composed of α-Ti, nanosize granular Ti7Al5Si12 and serration-shaped TiAl3. For the first time, obvious stacking fault structure in intermetallic phase TiAl3 was found when the thickness of the reaction layer was very thin (approximately below 1 μm). → Metallurgical characteristics for laser welding-brazing process in the environment of far from equilibrium was expounded by microstructures of the joints, the characteristics of thermal process and element diffusion behavior. - Abstract: Joining mechanism of Ti/Al dissimilar alloys was investigated during laser welding-brazing process with automated wire feed. The microstructures of fusion welding and brazing zones were analysed in details by transmission electron microscope (TEM). It was found that microstructures of fusion welding zone consist of α-Al grains and ternary near-eutectic structure with α-Al, Si and Mg2Si. Interfacial reaction layers of brazing joint were composed of α-Ti, nanosize granular Ti7Al5Si12 and serration-shaped TiAl3. For the first time, apparent stacking fault structure in intermetallic phase TiAl3 was found when the thickness of the reaction layer was very thin (approximately less than 1 μm). Furthermore, crystallization behavior of fusion zone and mechanism of interfacial reaction were discussed in details.

  4. Experimental investigation on dissimilar pulsed Nd:YAG laser welding of AISI 420 stainless steel to kovar alloy

    International Nuclear Information System (INIS)

    Highlights: • Austenite solidification morphology is cellular affected by temperature gradient. • Epitaxial growth region was produced in the fusion boundary of kovar side. • Precipitation of M23C6 carbides in ferrite grain boundary increased 420 HAZ hardness. • At high temperature gradient, columnar grains created in 420 fusion side. • Chemical compositions variations, grains morphologies alter welds vickers hardness. - Abstract: This paper presents the results of an investigation on autogeneous laser welding of AISI 420 stainless steel to kovar alloy using a 100 W pulsed Nd:YAG laser. The joints had a circular geometry and butt welded. The joints were examined by optical microscope for cracks, pores and for determining the weld geometry. The microstructure of the weld and the heat affected zones were investigatedby scanning electron microscope. The austenitic microstructure was achieved in the weld. The morphology of weld zone solidification was basically cellural, being influenced by the temperature gradient. It was found that the start of solidification in the kovar side of weld zone occurred by means of epitaxial growth. When the temperature gradient was high, the columnar grains were created in the fusion boundary of 420 stainless steel side toward weld zone. Measurements taken by X-ray spectrometry for dispersion of the energy in the weld zone indicated a significantly heterogeneous distribution of chromium element. The variations in chemical compositions and grains morphologies significantly alter the Vickers microhardness values in the weld zone

  5. Deformation Behavior of Laser Welds in High Temperature Oxidation Resistant Fe-Cr-Al Alloys for Fuel Cladding Applications

    Energy Technology Data Exchange (ETDEWEB)

    Field, Kevin G [ORNL; Gussev, Maxim N [ORNL; Yamamoto, Yukinori [ORNL; Snead, Lance Lewis [ORNL

    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 of three model alloys in a range of Fe-(13-17.5)Cr-(3-4.4)Al in weight percent with a minor addition of yttrium using laser-welding techniques. A detailed study on the mechanical performance of bead-on-plate welds has been carried out to determine the performance of welds as a function of alloy composition. Laser welding resulted in a defect free weld devoid of cracking or inclusions for all alloys studied. 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. No significant correlation was found between the deformation behavior/mechanical performance of welds and the level of Cr or Al in the alloy ranges studied.

  6. Process Optimization of Dual-Laser Beam Welding of Advanced Al-Li Alloys Through Hot Cracking Susceptibility Modeling

    Science.gov (United States)

    Tian, Yingtao; Robson, Joseph D.; Riekehr, Stefan; Kashaev, Nikolai; Wang, Li; Lowe, Tristan; Karanika, Alexandra

    2016-07-01

    Laser welding of advanced Al-Li alloys has been developed to meet the increasing demand for light-weight and high-strength aerospace structures. However, welding of high-strength Al-Li alloys can be problematic due to the tendency for hot cracking. Finding suitable welding parameters and filler material for this combination currently requires extensive and costly trial and error experimentation. The present work describes a novel coupled model to predict hot crack susceptibility (HCS) in Al-Li welds. Such a model can be used to shortcut the weld development process. The coupled model combines finite element process simulation with a two-level HCS model. The finite element process model predicts thermal field data for the subsequent HCS hot cracking prediction. The model can be used to predict the influences of filler wire composition and welding parameters on HCS. The modeling results have been validated by comparing predictions with results from fully instrumented laser welds performed under a range of process parameters and analyzed using high-resolution X-ray tomography to identify weld defects. It is shown that the model is capable of accurately predicting the thermal field around the weld and the trend of HCS as a function of process parameters.

  7. Effect of filler wire on the joint properties of AZ31 magnesium alloys using CO2 laser welding

    Institute of Scientific and Technical Information of China (English)

    Wang Hongying; Li Zhijun

    2007-01-01

    Laser welding with filler wire of AZ31 magnesium alloys is investigated using a CO2 laser experimental system. The effect of three different filler wires on the joint properties is researched. The results show that the weld appearance can be effectively improved when using laser welding with filler wire. The microhardness and tensile strength of joints are almost the same as those of the base metal when ER AZ31 or ER AZ61 wire is adopted. However, when the filler wire of ER 5356 aluminum alloy is used, the mechanical properties of joints become worse. For ER AZ31 and ER AZ61 filler wires, the microstructure of weld zone shows small dendrite grains. In comparison, for ER 5356 filler wire, the weld shows a structure of snowy dendrites and many intermetallic compounds and eutectic phases distribute in the dendrites. These intermetallic constituents with low melting point increase the tendency of hot crack and result in fragile joint properties. Therefore, ER AZ31 and ER AZ61 wire are more suitable filler material than ER 5356 for CO2 laser welding of AZ31 magnesium alloys.

  8. Experimental Investigations on Pulsed Nd:YAG Laser Welding of C17300 Copper-Beryllium and 49Ni-Fe Soft Magnetic Alloys

    International Nuclear Information System (INIS)

    Copper-beryllium and soft magnetic alloys must be joined in electrical and electro-mechanical applications. There is a high difference in melting temperatures of these alloys which cause to make the joining process very difficult. In addition, copper-beryllium alloys are of age hardenable alloys and precipitations can brittle the weld. 49Ni-Fe alloy is very hot crack sensitive. Moreover, these alloys have different heat transfer coefficients and reflection of laser beam in laser welding process. Therefore, the control of welding parameters on the formation of adequate weld puddle composition is very difficult. Laser welding is an advanced technique for joining of dissimilar materials since it can precisely control and adjust the welding parameters. In this study, a 100W Nd:YAG pulsed laser machine was used for joining 49Ni-Fe soft magnetic to C17300 copper-beryllium alloys. Welding of samples was carried out autogenously by changing the pulse duration, diameter of beam, welding speed, voltage and frequency. The spacing between samples was set to almost zero. The ample were butt welded. It was required to apply high voltage in this study due to high reflection coefficient of copper alloys. Metallography, SEM analysis, XRD and microhardness measurement was used for survey of results. The results show that the weld strength depends upon the chemical composition of the joints. To change the wells composition and heat input of the welds, it was attempted to deviate the laser focus away from the weld centerline. The best strength was achieved by deviation of the laser beam away about 0.1mm from the weld centerline. The result shows no intermetallic compounds if the laser beam is deviated away from the joint.

  9. Experimental Investigations on Pulsed Nd:YAG Laser Welding of C17300 Copper-Beryllium and 49Ni-Fe Soft Magnetic Alloys

    Science.gov (United States)

    Mousavi, S. A. A. Akbari; Ebrahimzadeh, H.

    2011-01-01

    Copper-beryllium and soft magnetic alloys must be joined in electrical and electro-mechanical applications. There is a high difference in melting temperatures of these alloys which cause to make the joining process very difficult. In addition, copper-beryllium alloys are of age hardenable alloys and precipitations can brittle the weld. 49Ni-Fe alloy is very hot crack sensitive. Moreover, these alloys have different heat transfer coefficients and reflection of laser beam in laser welding process. Therefore, the control of welding parameters on the formation of adequate weld puddle composition is very difficult. Laser welding is an advanced technique for joining of dissimilar materials since it can precisely control and adjust the welding parameters. In this study, a 100W Nd:YAG pulsed laser machine was used for joining 49Ni-Fe soft magnetic to C17300 copper-beryllium alloys. Welding of samples was carried out autogenously by changing the pulse duration, diameter of beam, welding speed, voltage and frequency. The spacing between samples was set to almost zero. The ample were butt welded. It was required to apply high voltage in this study due to high reflection coefficient of copper alloys. Metallography, SEM analysis, XRD and microhardness measurement was used for survey of results. The results show that the weld strength depends upon the chemical composition of the joints. To change the wells composition and heat input of the welds, it was attempted to deviate the laser focus away from the weld centerline. The best strength was achieved by deviation of the laser beam away about 0.1mm from the weld centerline. The result shows no intermetallic compounds if the laser beam is deviated away from the joint.

  10. Gravitational effects on weld pool shape and microstructural evolution during gas tungsten arc and laser beam welding on 304 stainless steel, nickel, and aluminum-4 wt.% copper alloy

    Science.gov (United States)

    Kang, Namhyun

    The objective of the present work was to investigate effects of gravitational (acceleration) level and orientation on Ni 200 alloy (99.5% Ni purity), 304 stainless steel, and Al-4 wt.% Cu alloy during gas tungsten arc welding (GTAW) and laser beam welding (LBW). Main characterization was focused on the weld pool shape, microstructure, and solute distribution as a function of gravitational level and orientation. The welds were divided into two classes, i.e., 'stable' and 'unstable' welds, in view of the variation of weld pool shape as a function of gravitational level and orientation. In general, higher arc current and translational GTAW produced more significant effects of gravitational orientation on the weld pool shape than the case of lower arc current and spot welding. Cross-sectional area (CSA) was a secondary factor in determining the stability of weld pool shape. For the 'stable' weld of 304 stainless steel GTAW, the II-U weld showed less convexity in the pool bottom and more depression of the free surface, therefore producing deeper penetration (10--20%) than the case of II-D weld. The II-D weld of 304 stainless steel showed 31% deeper penetration, 28% narrower width, and more hemispherical shape of the weld pool than the case of II-U weld. For GTAW on 304 stainless steel, gravitational level variation from low gravity (LG ≈ 1.2 go) to high gravity (HG ≈ 1.8 go) caused 10% increase in width and 10% decrease in depth while maintaining the overall weld pool volume. Furthermore, LBW on 304 stainless steels showed mostly constant shape of weld pool as a function of gravitational orientation. GTAW on Ni showed similar trends of weld pool shape compared with GTAW on 304 stainless steel, i.e., the weld pool became unstable by showing more penetration in the II-D weld for slower arc translational velocity (V a) and larger weld pool size. However, the Ni weld pool shape had greater stability of the weld pool shape with respect to the gravitational orientation

  11. Two- and three-dimensional characterizations of hot tears in a Al-Mg-Si alloy laser weld

    International Nuclear Information System (INIS)

    Hot tears in 6xxx aluminium alloy laser welds are characterized. They are shown to be intergranular, originating from fracture of liquid films without plasticity of the surrounding grains. The hot tear initiates on both sides of the fusion zone, follows the liquid films between the columnar grains of the weld line and then propagates around the equiaxed grains of the fusion zone centre. By using three-dimensional X-ray tomography, the exact shape of the hot tears has been visualized

  12. Fusion welding of Fe-added lap joints between AZ31B magnesium alloy and 6061 aluminum alloy by hybrid laser-tungsten inert gas welding technique

    International Nuclear Information System (INIS)

    Highlights: → Hybrid Laser-TIG fusion welding technique was used for joining Mg to Al alloys. → Laser defocusing amount determined penetration depth inside Al alloy of joints. → The addition of Fe interlayer suppressed Mg-Al intermetallics greatly in joints. → A maximum joint strength with optimum thickness of Fe interlayer was obtained. → Excessive addition of Fe interlayer was adverse for the strength improvement. -- Abstract: AZ31B magnesium alloy and 6061-T6 aluminum alloy were lap joined together with the addition of Fe interlayer by fusion welding of hybrid laser-tungsten inert gas (TIG) technique. The influence of location of laser focal spot (LFS) on joint penetration depth and that of the depth on joint strength were investigated. The results showed that when the LFS was just on the surface of Al plate, the deepest penetration could be obtained, which contributed to the improvement of shear strength of Fe-added joints, but not to the elevation of the strength of Mg/Al direct joints. The addition of Fe interlayer suppressed massive production of Mg-Al intermetallics but produced Fe-Al intermetallics in the fusion zone of the joints, whose micro-hardness was extremely high and was also adverse for the enhancement of joint shear strength. The effect of Fe-interlayer thickness on the joint shear strength was also examined, and the maximum shear strength of Fe-added joint could achieve 100 MPa with 0.13 mm thick Fe interlayer. The fracture modes of 0.07 and 0.13 mm Fe-interlayer-added joints were both quasi-cleavage, while those of direct and 0.22 mm interlayer-added joints were completely cleavage. The theoretical shear strength of the Fe-added joints was also discussed.

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

    Energy Technology Data Exchange (ETDEWEB)

    Field, Kevin G., E-mail: fieldkg@ornl.gov; Gussev, Maxim N., E-mail: gussevmn@ornl.gov; Yamamoto, Yukinori, E-mail: yamamotoy@ornl.gov; Snead, Lance L., E-mail: sneadll@ornl.gov

    2014-11-15

    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.

  14. Effect of Initial Microstructure on the Performance of 6XXX Al-alloy Laser Welds: A Computational Study

    Science.gov (United States)

    Samaras, Spiros N.

    2016-05-01

    Laser welding (LW) offers an attractive joining technique for Al-alloys. The performance of laser welds usually suffers from mechanical strength degradation in the heat-affected zone (HAZ). In the present study, the effect of the initial-aged microstructure on the post-welded state of 6XXX Al-alloys laser welds was examined via computational modeling techniques. A well-established and detailed precipitation model was used, coupled with a strength model. The influence of the main process variables for aging heat treatment (time and temperature) and LW (power and speed) on the mechanical integrity of weld joints and specifically in the yield strength profile in the HAZ was analyzed. Also, a simple method for the prediction of the width of HAZ is provided. It is concluded that more coarsened microstructures show better performance (compared with the aged state) due to lower degradation of mechanical strength and narrower width of HAZ on the post-welded state. This study provides a method for the selection of the appropriate process parameters for aging and LW of 6XXX Al-alloys.

  15. Effect of welding wires on microstructure and mechanical properties of 2A12 aluminum alloy in CO2 laser-MIG hybrid welding

    International Nuclear Information System (INIS)

    This paper represented the effect of welding wires on microstructure and mechanical properties of 2A12 aluminum alloy in CO2 laser-metal inter gas (MIG) hybrid welding. Plates of 2A12 aluminum alloy were welded by ER4043 and ER2319 welding wires, respectively. Full penetration joints without any defects were produced. The X-ray diffraction was used to analyze the phase composition, while the scanning electron microscopy (SEM) was conducted to study the microstructure, segregation behaviors of major alloying elements and the eutectics formed at dendrite boundaries in the joints. The results showed that silicon and copper were concentrated at the dendrite boundaries and α-Al + Si + Al2Cu + Mg2Si eutectic was formed if the ER4043 welding wire was used. However, only copper was concentrated at the dendrite boundaries and α-Al + θ eutectic was formed by ER2319 welding wire. Finally, the tensile tests were performed and the fracture surfaces were analyzed. The results showed that the joint efficiency by ER2319 and ER4043 welding wires reached up to 78% and 69%, respectively. Coarse dimples and voids had been observed in the fractographs. The joints showed a transgranular type failure.

  16. 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.

  17. Alloying elemental change of SS-316 and Al-5754 during laser welding using real time laser induced breakdown spectroscopy (LIBS) accompanied by EDX and PIXE microanalysis

    Science.gov (United States)

    Jandaghi, M.; Parvin, P.; Torkamany, M. J.; Sabbaghzadeh, J.

    Experimental studies of pulsed laser welding of stainless steel 316 in keyhole mode was done to examine a vaporization model based on the kinetic theory of gases and the thermodynamic laws. A long pulsed Nd:YAG laser with variable duration of 1-12 ms and 9-17 Gw/cm2 was employed. The undesirable loss of volatile elements affects on the weld metal compositions and the alloy properties. The model predicts that the loss of alloying elements strongly takes place at higher peak powers and longer pulse durations. On the other hand, the model shows the rapid migration of Mn and Cr based on the pressure and concentration gradients from the molten pool. Accordingly, the concentrations of iron, chromium, nickel and manganese were determined in the weld pool by means of the energy dispersive x-ray analysis (EDX) and proton induced X ray characteristics (PIXE) microanalysis. The change of weld metal composition of aluminium alloy 5754 in keyhole mode laser welding, was investigated using the model and was supported by the successive measurements. The model predicts that the concentration of magnesium in the weld metal decreases, while the aluminium concentration increases. Moreover, the real time concentrations of aluminium and magnesium elements in the weld metal were determined by laser induced breakdown spectroscopy (LIBS) at different conditions. We conclude that variation of the Al to Mg concentration ratio is negligible with various laser power densities while it is strongly correlated to the pulse duration.

  18. Laser-Arc Hybrid Welding of Dissimilar Titanium Alloy and Stainless Steel Using Copper Wire

    Science.gov (United States)

    Gao, Ming; Chen, Cong; Wang, Lei; Wang, Zemin; Zeng, Xiaoyan

    2015-05-01

    Laser-arc hybrid welding with Cu3Si filler wire was employed to join dissimilar Ti6Al4V titanium alloy and AISI316 stainless steel (316SS). The effects of welding parameters on bead shape, microstructure, mechanical properties, and fracture behavior were investigated in detail. The results show that cross-weld tensile strength of the joints is up to 212 MPa. In the joint, obvious nonuniformity of the microstructure is found in the fusion zone (FZ) and at the interfaces from the top to the bottom, which could be improved by increasing heat input. For the homogeneous joint, the FZ is characterized by Fe67- x Si x Ti33 dendrites spreading on α-Cu matrix, and the two interfaces of 316SS/FZ and FZ/Ti6Al4V are characterized by a bamboo-like 316SS layer and a CuTi2 layer, respectively. All the tensile samples fractured in the hardest CuTi2 layer at Ti6Al4V side of the joints. The fracture surface is characterized by river pattern revealing brittle cleavage fracture. The bead formation mechanisms were discussed according to the melt flow and the thermodynamic calculation.

  19. Laser welding of NiTi shape memory alloy wires and tubes for multi-functional design applications

    Science.gov (United States)

    Zeng, Zhi; Yang, Mao; Oliveira, João Pedro; Song, Di; Peng, Bei

    2016-08-01

    Welding and joining of NiTi shape memory alloys is essential for their integration into an increasing variety of applications. Almost all manufacturers and a significant number of researchers focus their investigation on welding NiTi, which can present both pseudoelasticity (PE) and shape memory effect. Integration of these materials would provide increased flexibility in terms of smart design, in particular for multi-functional systems. The current work investigates the mechanical, physical and phase transformation properties of similar (base materials (BMs) with the same composition) and dissimilar (BMs with different compositions) NiTi welded shape memory wires. The similar and dissimilar welded joints were successfully achieved by laser welding, which can reach up to 88.4% and 67.5% of the wire BM ductility. The joint break force of the similar and dissimilar joints were of 77.2% and 71.4% of the wire BM, respectively. Moreover, laser welding was found to effectively preserve the PE on the similar welded structures. The residual plastic strain variation of the dissimilar welded specimens at different temperatures during the cycling test may be helpful for design of multi-functional or flexible monolithic structures.

  20. Elucidation of laser welding phenomena and factors affecting weld penetration and welding defects

    Science.gov (United States)

    Katayama, Seiji; Kawahito, Yousuke; Mizutani, Masami

    The behavior and effect of a plasma plume on the weld penetration are greatly different between CO2 laser welding and YAG, disk or fiber laser welding. The effects of the power and the power density on the weld penetration are elucidated. Spattering leading to the formation of underfilled weld beads is controlled by inclining the laser beam. Porosity is formed from bubbles generated from the tip of the keyhole at low welding speed or from the middle part of the keyhole at high laser power density. Cracking easily occurs in pulsed spot welding of aluminum alloys.

  1. Nickel-based alloy/austenitic stainless steel dissimilar weld properties prediction on asymmetric distribution of laser energy

    Science.gov (United States)

    Zhou, Siyu; Ma, Guangyi; Chai, Dongsheng; Niu, Fangyong; Dong, Jinfei; Wu, Dongjiang; Zou, Helin

    2016-07-01

    A properties prediction method of Nickel-based alloy (C-276)/austenitic stainless steel (304) dissimilar weld was proposed and validated based on the asymmetric distribution of laser energy. Via the dilution level DC-276 (the ratio of the melted C-276 alloy), the relations between the weld properties and the energy offset ratio EC-276 (the ratio of the irradiated energy on the C-276 alloy) were built, and the effects of EC-276 on the microstructure, mechanical properties and corrosion resistance of dissimilar welds were analyzed. The element distribution Cweld and EC-276 accorded with the lever rule due to the strong convention of the molten pool. Based on the lever rule, it could be predicted that the microstructure mostly consists of γ phase in each weld, the δ-ferrite phase formation was inhibited and the intermetallic phase (P, μ) formation was promoted with the increase of EC-276. The ultimate tensile strength σb of the weld joint could be predicted by the monotonically increasing cubic polynomial model stemming from the strengthening of elements Mo and W. The corrosion potential U, corrosion current density I in the active region and EC-276 also met the cubic polynomial equations, and the corrosion resistance of the dissimilar weld was enhanced with the increasing EC-276, mainly because the element Mo could help form a steady passive film which will resist the Cl- ingress.

  2. Fatigue crack growth behaviour of gas tungsten arc, electron beam and laser beam welded Ti-6Al-4V alloy

    International Nuclear Information System (INIS)

    Highlights: → The available data focus on stress ratio, microstructure and residual stress on crack growth. → No literature available on fatigue behaviour of GTAW, LBW and EBW joints of Ti-Al-4V alloys. → This study compares the fatigue crack growth rate of GTAW, LBW and EBW joints of Ti-6Al-4V alloy. -- Abstract: The present investigation is aimed to evaluate fatigue crack growth parameters of gas tungsten arc, electron beam and laser beam welded Ti-6Al-4V titanium alloy for assessing the remaining service lives of existing structure by fracture mechanics approach. Center cracked tensile specimens were tested using a 100 kN servo hydraulic controlled fatigue testing machine under constant amplitude uniaxial tensile load. Crack growth curves were plotted and crack growth parameters (exponent and intercept) were evaluated. Fatigue crack growth behavior of welds was correlated with mechanical properties and microstructural characteristics of welds. Of the three joints, the joint fabricated by laser beam welding exhibited higher fatigue crack growth resistance due to the presence of fine lamellar microstructure in the weld metal.

  3. A Recent Welding Technique: Laser Welding

    OpenAIRE

    ATİK, Dt.Ezgi; CİĞER, Prof. Dr. Semra

    2013-01-01

    Welding is a process that joins two adjacent metal surfaces with or without using filling material. The latest laser welding technique is a technology based on using infrared light spectrum. Laser welding has numerous advantages considering other conventional welding options used in dentistry and because of these reasons laser welding is used widely. When searching the literature in concern with laser welding, it is observed that this technique is compared with other conventional welding meth...

  4. Microstructure and mechanical properties of newly developed aluminum–lithium alloy 2A97 welded by fiber laser

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Banglong [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials Ministry of Education, Shandong University, Jinan 250061 (China); Qin, Guoliang, E-mail: glqin@sdu.edu.cn [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials Ministry of Education, Shandong University, Jinan 250061 (China); Meng, Xiangmeng; Ji, Yang; Zou, Yong [Key Laboratory for Liquid–Solid Structural Evolution and Processing of Materials Ministry of Education, Shandong University, Jinan 250061 (China); Lei, Zhen [Harbin Welding Institute, Harbin 150028 (China)

    2014-11-03

    The newly developed aluminum–lithium alloy 2A97 was for the first time joined by laser beam welding in order to meet the ever-increased long-term requirements of aerospace, aviation and armament industries. The weld appearance, microstructure, solute segregation, precipitate behavior, and their relationships with mechanical properties of welded joints were investigated. Sound joints with no crack and a few small porosities are obtained under appropriate heat inputs. As a result of heterogeneous nucleation involving the effect of Zr and Li, a non-dendritic equiaxed zone forms between partially melted zone and fusion zone. The crystal morphologies in fusion zone vary from columnar dendrite to equiaxed dendrite, with the increase of constitutional supercooling. Solute segregation leads to the variations of Cu content in grain interior and boundary, as well as the weak ability of re-precipitation of fusion zone. Most precipitates in the base metal dissolve during welding, and fusion zone contains a decreased quantity of δ′, β′, θ′, and T{sub 1}. The ultimate tensile strength of laser welded joints is 83.4% of that of the base metal, and can meet the application requirements from related industries, but the ductility still needs to be improved. Welding defects and loss of solid solution/precipitation hardened structure lead to the degradation of mechanical properties. Tensile fracture occurs in weld with the brittle intergranular dominated mode and premature failure occurs and extends in the equiaxed zone.

  5. Dissimilar laser welding of NiTi shape memory alloy and copper

    Science.gov (United States)

    Zeng, Z.; Panton, B.; Oliveira, J. P.; Han, A.; Zhou, Y. N.

    2015-12-01

    This work is the first investigation of joining NiTi and copper. The successful Nd:YAG laser welding of NiTi to copper achieved in this work enables new methods of connecting shape memory alloys to electro-mechanical systems. Joints made with an optimum peak power of 2.2 kW accommodated pseudoelastic deformation of NiTi, proving their use with high strength actuators. Fracture occurred through the cross section of these defect-free joints. A lower peak power of 1.8 kW created weak joints with limited weld penetration of the copper sheet. This lack of bonding resulted in fracture occurring across the small disconnected joint areas. Joints made with a higher peak power of 2.6 kW had significant cracking in the fusion zone. Two regions of distinct Cu composition were found in the fusion zone, and cracking occurred at the interface between these regions because of their different physical properties. Failure initiated at this cracking and propagated through the fusion zone that had been embrittled by mixing with over 20 at.% Cu.

  6. Laser welding in space

    Science.gov (United States)

    Kaukler, W. F.; Workman, G. L.

    1991-01-01

    Autogenous welds in 304 stainless steel were performed by Nd-YAG laser heating in a simulated space environment. Simulation consists of welding on the NASA KC-135 aircraft to produce the microgravity and by containing the specimen in a vacuum chamber. Experimental results show that the microgravity welds are stronger, harder in the fusion zone, have deeper penetration and have a rougher surface rippling of the weld pool than one-g welds. To perform laser welding in space, a solar-pumped laser concept that significantly increases the laser conversion efficiency and makes welding viable despite the limited power availability of spacecraft is proposed.

  7. Tensile and fatigue properties of fiber laser welded high strength low alloy and DP980 dual-phase steel joints

    International Nuclear Information System (INIS)

    Highlights: ► A high joint efficiency of 94–96% and 96–97% is achieved for HSLA and DP980 joints. ► A distinctive “suspension bridge”-like hardness profile appears after laser welding. ► While HAZ-softening takes place in the DP980 joints, it is absent in the HSLA joints. ► Fatigue resistance is susceptible to the presence of weld concavity and soft zone. ► Fatigue crack initiation occurs mainly at weld concavity at lower stress levels. -- Abstract: The study was aimed at evaluating the microstructure and mechanical properties of high-speed fiber laser welded high strength low alloy (HSLA) and DP980 dual-phase steel joints with varying weld geometries. Fusion zone (FZ) consisted of martensitic structure, and heat-affected zone (HAZ) contained newly-formed martensite in both steels and partially tempered martensite in DP980. While HAZ-softening was present in DP980, it was absent in HSLA. A distinctive “suspension bridge”-like hardness profile with the FZ hardness as a “pylon” appeared in the fiber laser welded joints. Both HSLA and DP980 joints showed a superior tensile strength, with a joint efficiency of 94–96% and 96–97%, respectively, despite a reduced elongation in DP980 joints. Fatigue strength was higher in DP980 joints than in HSLA joints at higher stress amplitudes, but had no obvious difference at lower stress amplitudes. DP980 multiple linear welds exhibited a larger scatter and lower fatigue strength. Fatigue failure of HSLA joints occurred in the base metal at a stress amplitude above 250 MPa, and at weld concavity at a lower stress amplitude below 250 MPa. Fatigue crack in DP980 joints initiated predominantly from the weld concavity at both high and low levels of stress amplitudes.

  8. Microstructural characterization of laser and electron beam (EB) welds of Nb-1Zr-0.1C alloy

    International Nuclear Information System (INIS)

    Nb-1wt%Zr-0.1wt%C alloy is being considered for the structural applications in proposed Compact High Temperature Reactor (CHTR) on account of its excellent combination of high temperature properties. The applications of this alloy calls for welding, which is a difficult task due to its reactive nature, higher thermal conductivity and melting point. The high energy density techniques like laser and electron beam were employed to produce the welds on sheets of Nb-alloy at various processing parameters in bead-on-plate and square butt joint configurations. The weld joints produced were characterized by studying their optical, Scanning Electron Microscopy (SEM) and Electron Back Scattering Diffraction (EBSD) micro-graphs. The SEM micrograph of EB fusion zone along with the heat affected zone (HAZ) and the base region were studied and abrupt changes in the grain morphology were found in each zone. The fusion zone shows larger grains indicating the rapid grain growth after solidification, whereas the HAZ shows relatively smaller size of the grains but still much larger than the base zone. The SEM micrograph of central part of the same butt weld shows clear grain boundaries with a large variation in the grain size (45-82 micrometer) in the weld region. The heat affected zone (HAZ) and base metal showed fine carbide precipitates along the grain boundaries, whereas carbides were found dissolved in the weld zone. The EBSD micrograph of electron beam fusion zone describing the grain orientation in the weld region are described. The micro-hardness profile across the width of welds was also studied. The detailed results of all these studies are described in this paper. (author)

  9. Study of the structure and properties of laser-welded joints of the Al-Mg-Li alloy

    Science.gov (United States)

    Pugacheva, N. B.; Antenorova, N. P.; Senaeva, E. I.

    2015-12-01

    The macro- and microstructures, the distribution of chemical elements and of the values of the microhardness over the width of the zones of remelting and heat-affected zone have been studied after the laser welding of sheets of an Al-Mg-Li alloy. It has been shown that the material of the zone of remelting (1.2 mm thick) represents in itself finely dispersed misoriented dendrites, in the primary branches of which particles of the strengthening δ' phase (Al3Li) with dimensions of no more than 10 nm and in the interdendrite spaces, dispersed particles of the S phase (Al2MgLi and FeAl2) have been revealed. The hardness of the material of the zone of remelting was 108-123 HV 0.05; the hardness of the basic alloy, 150-162 HV 0.05. In the heat-affected zones of thickness 2 mm, the primary recrystallization occurred only in a narrow zone directly at the boundary with the weld. The strength of the welded junction was 470-490 MPa, which corresponds to the regulated degree of strength of the aluminum alloys of this class. The relative elongation of the material of the weld proved to be considerably less than that in the alloy matrix because of the microporosity of the weld material. It is shown that the convective stirring of the melt in the welding pool upon the laser welding made it possible to avoid the appearance of macroscopic defects, but on the microlevel there are observed micropores in the form of spheres with dimensions of 5-50 μm. The solidification of the alloy occurred in such a way that the dendrites had time to grow around the gas bubbles prior to their collapse, forming a sufficiently strong carcass. Inside the dendritic carcass, there have been revealed coarse inclusions (to 200 μm) that consist of oxides (Al2O3, Fe2O3, MgO, SiO2, CaO), of an iron-based alloy, and of the host aluminum alloy.

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

    International Nuclear Information System (INIS)

    Research highlights: → A dendritic cellular structure was formed in the weld fusion zone (WFZ) and caused alloying element segregation. → The precipitation of intermetallic phases and the formation of galvanic corrosion couplings contribute to the improving pitting susceptibility in the WFZ. → 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.

  11. Laser welding of thin foil nickel–titanium shape memory alloy

    OpenAIRE

    Chan, Chi Wai; Man, H.C.

    2011-01-01

    In this study, two L27 Taguchi experiments were carried out to study the effect of fibre laser welding parameters and their interactions upon the weld bead aspect ratio of nickel–titanium thin foil. The optimum parameters to produce full penetrated weld with the largest aspect ratio and desirable microstructure were successfully obtained by the Taguchi experimental design. The corrosion property of the optimized NiTi weld in Hank’s solution at 37.5 °C was studied and compared with the as-rece...

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

    International Nuclear Information System (INIS)

    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

  13. Deformation behaviour of laser-welded tube blank of TA15 Ti-alloy for gas forming at elevated temperature

    Directory of Open Access Journals (Sweden)

    Wang Kehuan

    2015-01-01

    Full Text Available Deformation behaviour of laser-welded tube blank of TA15 Ti-alloy at elevated temperature was investigated by both hot tensile tests and high pressure gas forming(HPGF. The hot tensile tests were carried out with four different specimens at 800 ∘C with an initial strain rate of 1.00×10−2 s−1 and HPGF test was performed at 800 ∘C with a constant pressure of 9.5MPa. The tensile results show that base material with equiaxed microstructure exhibited good formability and grain boundary sliding (GBS accompanied with dynamic recrystallization (DRV was the main deformation mechanism. However, because the weld bead has coarse columnar grains with fine acicular α′ in the β matrix, when the loading direction is parallel with the weld bead, the fine acicular α′ transformed into thicker α lamella and the aspect ratio decreased greatly, and voids formed along the initial coarse β grain boundaries. When the loading direction is vertical with the weld bead, the welded materials deformed little and the lamella structure thickened obviously after deformation. HPGF tests demonstrate that the laser-welded TA15 tube had a very good formability at 800 ∘C, and the maximum bulging ratio was as high as 77.4%.

  14. Computerized simulation of YAG pulse laser welding of titanium alloy (TA6V): experimental characterization and modelling of the thermomechanical aspects of this process

    International Nuclear Information System (INIS)

    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)

  15. Effect of Nd:YAG laser welding on microstructure and hardness of an Al–Li based alloy

    International Nuclear Information System (INIS)

    Butt joints of 3.0 mm thick sheets of an Al–Li based alloy have been produced using Nd:YAG laser welding without filler metals. The hardness distribution and microstructure of the alloy and welded joints were investigated. The changes in the grain shapes, grain orientations, microtexture, and precipitates of the fusion zone were analyzed using optical microscope, electron back scattered diffraction (EBSD) and transmission electron microscopy (TEM). The results show that Nd:YAG laser welding leads to a change of the microhardness, grain shape, grain orientations, and a disappearance of the microtexture and precipitates. A narrow band of EQZ along the fusion boundary and a predominantly equiaxed dendritic structure are developed in the fusion zone. The formation of the predominately equiaxed dendritic grains is due to a heterogeneous nucleation mechanism aided by equilibrium A13Zr phases as well as the growth of pre-existing nuclei created by dendrite fragmentation, or by grain detachment resulted from Nd:YAG laser welding processes. In addition, Nd:YAG laser welding produces lower Vickers hardness than that of the base metal due to the decrease in the in quantity of δ′ precipitates in the fusion zone. - Graphical Abstract: The grain shapes, grain orientations, microtexture, and precipitates of the solidified fusion zone were investigated and compared with the base metal using optical microscope, electron back scattered diffraction (EBSD) and transmission electron microscope (TEM). EBSD orientation map of laser welded joint in 5A90 alloys is presented in Fig. 3. It clearly shows that a narrow band EQZ along the fusion boundary and the predominantly equiaxed grains have been developed in the fusion zone of 5A90 alloys. Also, it is clear that the microstructure of the base metal is characterized by laminated grains with preferred orientations, whereas the fusion zone is predominately equiaxed grains in different colors having random orientations. Highlights:

  16. Laser Welding in Electronic Packaging

    Science.gov (United States)

    2000-01-01

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

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

    International Nuclear Information System (INIS)

    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 (104–107 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 107 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

  18. Use of LMA-1 laser microanalyzer for investigation of joint welds of high-alloy steels

    International Nuclear Information System (INIS)

    A method for quantitative local analysis of steels with the use of LMA-1 laser microanalyzer has been developed. The method has been used for investigation of the distribution of Cr, Ni, Mn, Si, and Ti elements in welded joints of 10Kh20N7T steel. It is shown that the chemical composition of the microareas of the joint is inhomogeneous, which may cause cracking in the welds

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

    OpenAIRE

    Muchiar, Ir.; Yoshida, S.; Widiastuti, R.; Kusnovo, A.; Takahashi, K; Sato, S.

    1996-01-01

    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 ...

  20. Microstructure and mechanical properties of laser-arc hybrid welding joint of GH909 alloy

    Science.gov (United States)

    Liu, Ting; Yan, Fei; Liu, Sang; Li, Ruoyang; Wang, Chunming; Hu, Xiyuan

    2016-06-01

    In this paper, laser-arc hybrid welding of 10 mm thick low-thermal-expansion superalloy GH909 components was carried out to obtain a joint with good performance. This investigation was conducted using an optical microscope, scanning electron microscope, energy diffraction spectrum and other methodologies. The results showed that weld joints with a desirable wineglass-shaped weld profile can be obtained employing appropriate process parameters. The different grains in between the upper central seam and the bottom seam were associated with the temperature gradient, the pool's flow and the welding thermal cycle. MC-type carbides and eutectic phases (γ+Laves) were produced at grain boundaries due to the component segregation during the welding process. In addition, γ‧ strengthening phase presented in the interior of grains, which kept a coherent relationship with the matrix. The lowest hardness value occurred in the weld center, which indicated that it was the weakest section in the whole joint. The average tensile strength of the joints reached to 632.90 MPa, nearly 76.84% of the base metal. The fracture analysis revealed that the fracture mode of the joint was ductile fracture and the main reason for joint failure was as a result of the occurrence of porosities produced in the weld during the welding process.

  1. Microstructure and fatigue properties of fiber laser welded dissimilar joints between high strength low alloy and dual-phase steels

    International Nuclear Information System (INIS)

    Highlights: • A high joint efficiency of over 97% is achieved in HSLA–DP980 dissimilar joints. • While a soft zone occurs on the DP980 side, it is absent on the HSLA side. • Inside the fusion zone two hardness sub-regions are observed. • Fatigue limit of dissimilar joints is equivalent to that of HSLA similar joints. • Fatigue failure occurs mainly at weld concavity at lower cyclic stress levels. - Abstract: The aim of this study was to evaluation the microstructure and fatigue properties of welded joints made with fiber laser welding (FLW) on a high strength low alloy (HSLA) and dual-phase (DP980, UTS ⩾ 980 MPa) steel in similar and dissimilar material combinations. The fusion zone (FZ) consisted of martensite, and the heat affected zone (HAZ) contained some newly formed martensite and partially tempered martensite on the DP980 steel side. A characteristic asymmetric hardness profile across the dissimilar HSLA–DP980 welded joint was observed. While a soft zone occurred on the DP980 side, it was absent on the HSLA side. Inside the FZ two hardness sub-regions were observed due to the difference in the alloying elements between two steels along with the fast cooling during FLW. The presence of soft zone on the DP980 side had no effect on the tensile properties, since the lowest hardness value in the soft zone was still higher than that of the HSLA base metal (BM). A joint efficiency of 97–100% was achieved with respect to the HSLA. The strain to failure of the dissimilar HSLA–DP980 welded joints was significantly (∼threefold) higher than that of the similar DP980–DP980 welded joints. Although the fatigue strength of the dissimilar HSLA–DP980 welded joints was lower than that of DP980–DP980 welded joints, it was equivalent to that of HSLA–HSLA welded joints. Failure occurred in the BM on the HSLA side in the tensile tests and fatigue tests at high cyclic stress levels, where yielding occurred. At the intermediate and lower cyclic stress

  2. Laser Seam welding method

    International Nuclear Information System (INIS)

    The present invention provides a laser seam welding method for welding spacers to be used in nuclear fuel assemblies at a stable quality. Namely, the laser seam welding method comprises irradiating, while moving, laser beams to a portion to be welded. In this case, data of the shapes and characteristics of the portion to be welded are inputted to restrict the range of the welding of the portion to be welded. The power, moving speed, distance to a focal point and energy of the laser beams are controlled in the midway of the range for the welding. Then, a welding nugget having a shape defined to a portion to be welded can be formed thereby enabling to keep the portion to be welded to stable quality. As a result, failed welding can be eliminated, and strength of joint can be guaranteed. In addition, auxiliary products of portions to be welded, for example, springs are not failed by laser beams. As a result, satisfactory spacers can be provided. (I.S.)

  3. Bringing Pulsed Laser Welding into Production

    DEFF Research Database (Denmark)

    Olsen, Flemmming Ove

    1996-01-01

    In this paper, some research and develop-ment activities within pulsed laser welding technology at the Tech-nical University of Denmark will be described. The laser group at the Insti-tute for Manufacturing Technology has nearly 20 years of experience in laser materials process-ing. Inter......-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...... activities concerning the weldability of high alloyed austenitic stainless steels for mass production industry applying industrial lasers for fine welding will be described. Studies on hot cracking sensitivity of high alloyed austenitic stainless steel applying both ND-YAG-lasers and CO2-lasers has been...

  4. Laser welding in space

    International Nuclear Information System (INIS)

    This paper reports on the design and construction, as well as typical results from performing low gravity laser welding experiments on NASA's KC-135 aircraft flying parabolic maneuvers to simulate low gravity. Results of the experiments are reported and some new concepts regarding the implementation of laser technology suitable for laser welding in space are presented

  5. Slow strain rate stress corrosion cracking behaviour of as-welded and plasma electrolytic oxidation treated AZ31HP magnesium alloy autogenous laser beam weldment

    International Nuclear Information System (INIS)

    The joining of a thin section AZ31HP magnesium alloy was accomplished by laser beam welding in the autogenous mode using a Nd-YAG laser system. Micro hardness evaluation and slow strain rate tensile (SSRT) tests in air revealed that the weld metal had near-matching mechanical properties corresponding to that of the parent alloy. However, in terms of stress corrosion cracking (SCC) resistance as assessed by SSRT tests in ASTM D1384 solution, the weldment was found to have higher susceptibility compared to the parent alloy. The fracture in the weld metal/fusion boundary/HAZ interface suggested that the failure was due to the grain coarsening at the very narrow heat affected zone. The resistance to SCC of the parent alloy and the weldment specimens was found to improve slightly by the application of plasma electrolytic oxidation (PEO) coating from a silicate based electrolyte.

  6. Welding by laser beam

    International Nuclear Information System (INIS)

    A laser which does not require a vacuum and the beam from which can be projected over a distance without loss of power is sited outside a welding zone and the beam projected through a replaceable laser transparent window. The window is designed and shaped to facilitate access of the beam of workpiece items to be welded in containment. Either the workpiece or the laser beam may be moved during welding. (author)

  7. Pulsed YAG laser spot welding under microgravity

    Science.gov (United States)

    Katayama, Seiji; Tanaka, Koji; Mizutani, Masami; Matsunawa, Akira

    2000-02-01

    With the objectives of obtaining a fundamental knowledge of laser welding technology inside and outside the spacecraft in space, pulsed YAG laser spot welding was performed on the metal plates in Ar gas atmosphere or a vacuum in the falling microgravity apparatus equipped with the fiber-delivered laser focusing optics. The influence of gravity or microgravity on penetration and welding defect formation was further clarified by comparing the welds made in the normal flat and overhead positions. Almost all results of weld penetration and defect formation under microgravity were similar to those under normal gravity except the welding result of aluminum alloy A5083 subjected to the high power density laser, and were between normal gravity and overhead position welding results. Welding in a vacuum was characterized by the formation of a narrower and cone-shaped bottom in any alloy weld. Porosity was easily formed in any deeply penetrated weld metal under high power density welding with a rectangular pulse-shaped laser, and could be reduced by utilizing pulse-controlled laser even under microgravity.

  8. Deformation behaviour of laser-welded tube blank of TA15 Ti-alloy for gas forming at elevated temperature

    OpenAIRE

    Wang Kehuan; Liu Gang; Yuan Shijian

    2015-01-01

    Deformation behaviour of laser-welded tube blank of TA15 Ti-alloy at elevated temperature was investigated by both hot tensile tests and high pressure gas forming(HPGF). The hot tensile tests were carried out with four different specimens at 800 ∘C with an initial strain rate of 1.00×10−2 s−1 and HPGF test was performed at 800 ∘C with a constant pressure of 9.5MPa. The tensile results show that base material with equiaxed microstructure exhibited good formability and grain boundary sliding (G...

  9. Effect of laser parameters on arc behavior of laser-TIG double-side welding for aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    Miao Yugang; Li Liqun; Zhang Xinge; Chen Yanbin; Wu Lin

    2010-01-01

    The influence of laser parameters on arc behavior of laser-TIG double-side welding was investigated by utilizing CCD sensor and image processing methods. It was found that arc images had an obvious transformation from laser preheating to laser plasma ejected from the keyhole bottom, resulting in the phenomena of arc column convergence and arc root constriction. The attraction phenomenon of the laser and the arc is also found in laser-TIG double-side welding. More noteworthy is that the behavior of arc attraction or constriction became much obvious at a lower current or laser plasma ejected from the keyhole bottom. The decrease in arc voltage had a certain relation with the improvement of arc stability.

  10. Laser-tungsten inert gas hybrid welding of dissimilar metals AZ31B Mg alloys to Zn coated steel

    International Nuclear Information System (INIS)

    Highlights: ► Successful joining Mg to Zn coated steel using laser-TIG hybrid welding. ► Metallurgical bonding was achieved at the Mg/Zn coated steel interface. ► Influence of laser power on joining Mg to Zn coated steel was investigated. ► Newly formed Fe3Al phase improved the interfacial bonding and joint strength. ► The role of Zn coating in joining Mg to steel was clarified. - Abstract: Laser-tungsten inert gas (TIG) hybrid welding has been developed for joining Mg alloys to Zn coated steel in a lap joint configuration. The joint could not be produced in laser or arc welding only, while acceptable joints without obvious defects were obtained with a relatively wide processing window in the hybrid process. Two reaction layers were observed to form at the interface and were identified as Mg–Zn eutectic structure (α-Mg + MgZn) and Fe3Al phase by TEM analysis. In some cases, Al6Mn phase also formed adjacent to the Fe–Al reaction layer. The tensile-shear strength attained the maximum value of 68 MPa, representing 52.3% joint efficiency relative to Mg base metal. The element Al from AZ31B Mg alloys diffused to the liquid/solid interface and then reacted with the elements from steel, such as Fe and Mn, contributing to the metallurgical bonding at the interface. The weak bonding between Mg–Zn reaction layer and newly formed Fe–Al layer resulted in the interfacial failure

  11. Combination of laser keyhole and conduction welding: Dissimilar laser welding of niobium and Ti-6Al-4V

    Science.gov (United States)

    Torkamany, M. J.; Malek Ghaini, F.; Poursalehi, R.; Kaplan, A. F. H.

    2016-04-01

    Pulsed Nd:YAG laser welding of pure niobium plate to titanium alloy Ti-6Al-4V sheet in butt joint is studied regarding the laser/metal interaction modes. To obtain the optimized process parameters in dissimilar welding of Ti-6Al-4V/Nb, the melting ratio of laser beam energy for each weld counterpart is evaluated experimentally. Different laser welding modes of keyhole and conduction are predicted regarding the absorbed energy from the similar laser pulses on each weld counterpart. Laser keyhole and conduction welding were observed simultaneously through direct visualization of laser interaction with dissimilar metals using High Speed Imaging (HSI) system.

  12. Welding of Prosthetic Alloys

    OpenAIRE

    Wojciechowska M.; Wołowiec E.; Klimek L.

    2015-01-01

    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 asses...

  13. Microstructure evolution and mechanical properties investigation of Al-6%Cu alloy laser and GTA welds; Untersuchung der Mikrostrukturentwicklung und der mechanischen Eigenschaften von Laser- und WIG-Schweissnaehten einer Al-6%Cu-Legierung

    Energy Technology Data Exchange (ETDEWEB)

    Talari, Mahesh Kumar [Universiti Teknologi MARA, Shah Alam (Malaysia). Faculty of Applied Sciences; Babu, Nagumothu Kishore [Singpaore Institute of Manufacturing Technology, Singapore (Singapore). Joining Technology Group

    2013-10-01

    Microstructural development, post-weld ageing response and mechanical properties of gas tungsten arc and CO{sub 2} laser welded Al-6%Cu (AA2219) alloy were investigated in the present study. The fusion zone of laser weld consists of three parts: the fine grains in the middle part, the columnar zone and equiaxed zone adjacent to fusion boundary. In contrast, fusion zone of gas tungsten arc weld consists of two parts: the columnar zone in the middle part and the equiaxed zone adjacent to fusion boundary. The size of the equiaxed grains in the fusion zone was the least in the laser welds when compared to gas tungsten arc welds. Laser welds have exhibited higher hardness, post weld ageing response, yield strength, ductility and fatigue strength when compared with gas tungsten arc welds. Fine equiaxed grain morphology and discontinues eutectic distribution in the laser weld fusion zone could be attributed to the improved tensile and fatigue properties of laser welded samples. 'Thermal pinning effect', due to non isothermal conditions, has arrested grain growth in heat affected zone in spite of temperatures close to the melting point of aluminum in heat affected zone. (orig.)

  14. Spectral characteristics of arc plasma during laser-arc double-sided welding for aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    Kezhao Zhang; Zhenglong Lei; Xianglong Wang; Yanbin Chen; Yaobang Zhao

    2015-01-01

    In laser-arc double-sided welding,the spectral characteristics of the arc plasma are calculated and analyzed by spectroscopic diagnosis.The results show that,compared with conventional tungsten inert gas (TIG) welding,the introduction of a laser changes the physical characteristics of the arc plasma regardless of whether laser plasma penetration takes place,and that the influence of the laser mainly affects the near-anode region of the arc.When the laser power is relatively low,the arc column tends to compress,and the arc spectral characteristics show no significant difference.When the arc root constricts,compared with pure TIG arc,the electron density increases by ~2.7 times and the electron temperature decreases by ~3000 K.When the arc column expands,the intensities of spectral lines of both the metal and Ar atoms are the strongest.But it is also observed that the electron density reduces,whereas there is no obvious decrease of electron temperature.

  15. Nd:YAG laser welding of aerospace grade ZE41A magnesium alloy: Modeling and experimental investigations

    International Nuclear Information System (INIS)

    Keyhole formation as well as the geometry of weld profiles during Nd:YAG laser welding of ZE41A-T5 were studied through combining various models and concepts. The results indicated that weld width and fusion area decrease with increasing welding speed. In the case of partially penetrated welding, penetration depth decreases with increasing welding speed. Also, the model predicted that excessive decrease in laser power or increase in defocusing distance decreases surface power density, thereby changing the welding mode from fully penetrated keyhole, to partially penetrated keyhole, and then to the conduction mode. The predicted conditions for keyhole stability and welding modes as well as the weld profiles for various processing conditions were validated by some selected welding experiments. These experiments included studying the effects of welding speed, laser power, joint gap and laser defocusing on the weld geometry of 2- and 6-mm butt joints or bead-on-plates of ZE41A-T5 sand castings using a continuous wave 4 kW Nd:YAG laser system and 1.6-mm EZ33A-T5 filler wire. Good agreements were found between the model predictions and experimental results indicating the validity of the assumptions made for the development of the model

  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. Impact property of low-activation vanadium alloy after laser welding and heavy neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Nagasaka, Takuya, E-mail: nagasaka@nifs.ac.jp [National Institute for Fusion Science, Toki, Gifu (Japan); The Graduate University for Advanced Studies, Toki, Gifu (Japan); Muroga, Takeo [National Institute for Fusion Science, Toki, Gifu (Japan); The Graduate University for Advanced Studies, Toki, Gifu (Japan); Watanabe, Hideo [Research Institute for Applied Mechanics, Kyushu University, Kasuga (Japan); Miyazawa, Takeshi [The Graduate University for Advanced Studies, Toki, Gifu (Japan); Yamazaki, Masanori [International Research Center for Nuclear Materials Science, Institute for Materials Research, Tohoku University, Oarai, Ibaraki (Japan); Shinozaki, Kenji [Department of Mechanical System Engineering, Graduate School of Engineering, Hiroshima University, Higashi Hiroshima (Japan)

    2013-11-15

    Weld specimens of the reference low activation vanadium alloy, NIFS-HEAT-2, were irradiated up to a neutron fluence of 1.5 × 10{sup 25} n m{sup −2} (E > 0.1 MeV) (1.2 dpa) at 670 K and 1.3 × 10{sup 26} n m{sup −2} (5.3 dpa) at 720 K in the JOYO reactor in Japan. The base metal exhibited superior irradiation resistance with the ductile-to-brittle transition temperature (DBTT) much lower than room temperature (RT) for both irradiation conditions. The weld metal kept the DBTT below RT after the 1.2 dpa irradiation; however, it showed enhanced irradiation embrittlement with much higher DBTT than RT after the 5.3 dpa irradiation. The high DBTT for the weld metal was effectively recovered by a post-irradiation annealing at 873 K for 1 h. Mechanisms of the irradiation embrittlement and its recovery are discussed, based on characterization of the radiation defects and irradiation-induced precipitation.

  18. In vitro mesenchymal stem cell responses on laser-welded NiTi alloy.

    Science.gov (United States)

    Chan, C W; Hussain, I; Waugh, D G; Lawrence, J; Man, H C

    2013-04-01

    The biocompatibility of NiTi after laser welding was studied by examining the in vitro (mesenchymal stem cell) MSC responses at different sets of time varying from early (4 to 12h) to intermediate phases (1 and 4 days) of cell culture. The effects of physical (surface roughness and topography) and chemical (surface Ti/Ni ratio) changes as a consequence of laser welding in different regions (WZ, HAZ, and BM) on the cell morphology and cell coverage were studied. The results in this research indicated that the morphology of MSCs was affected primarily by the topographical factors in the WZ: the well-defined and directional dendritic pattern and the presence of deeper grooves. The morphology of MSCs was not significantly modulated by surface roughness. Despite the possible initial Ni release in the medium during the cell culture, no toxic effect seemed to cause to MSCs as evidenced by the success of adhesion and spreading of the cells onto different regions in the laser weldment. The good biocompatibility of the NiTi laser weldment has been firstly reported in this study. PMID:23827581

  19. Numerical Investigation of Keyhole Shape during CO2 Laser Welding of 5456 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    JOSEPH .I. ACHEBO

    2010-06-01

    Full Text Available This paper takes a close look at the keyhole shape forming process as well as the effect thermal heat flow has on weld penetration depth. Laser heat input is one of the main determinants of keyhole formation, weld penetration, and fusion morphology. In this study, it was found that the dominant solute transport in the weldpool is driven by convection with a maximum velocity of 1.57 m/s, above the value of 1.0m/s reported by other investigators. This further confirms the turbulent nature of the flow in the weldpool. The droplet shape in the keyhole was found to be conical. The fusion depth and width were calculated to be 1.04mm and 4.26mm respectively. These values were compared with reported values of other investigators and the results were within acceptable ranges.

  20. One-sided laser beam welding of autogenous T-joints for 6013-T4 aluminium alloy

    International Nuclear Information System (INIS)

    Highlights: • We report autogenous T-joints of the 6013-T4 produced by one-sided laser welding. • It is investigated the influence of the process parameters on the weld features. • Beam focal positioning on the sample is a critical parameter in the weld quality. • Tensile strength has some dependence with sheet rolling direction jointed by laser. - Abstract: Autogenous T-joints for aluminium skin-stringer component performed by one-sided laser beam welding process was conducted using a high power Yb-fiber laser. The influence of the shielding gas, seam angle, beam focal position, and beam positioning relative to weld centerline were investigated regarding to weld microstructural features. The joint mechanical behavior was evaluated concerning to the sheet rolling directions. It was observed that a precise control of the process parameters enabled to obtain weld beads with acceptable dimensional and geometric characteristics and minimizing weld defects. Helium shielding gas produced higher aspect ratio welds than those with pure argon. Although, pores were observed in the fusion zone, they represented only about 5% of the weld bead area. The optimal beam positioning should remain up to 0.2 mm relative to junction line, for seam angles between 10° and 15°. The weld mechanical behavior depended on the sheet rolling direction. Joint efficiency up to 85% were obtained after hoop tensile tests when the weld bead longitudinal-section was perpendicular to skin rolling direction and parallel to the stringer rolling direction

  1. Laser Welding of High Strength Steels

    OpenAIRE

    Guo, Wei

    2016-01-01

    S960 and S700 are two types of high strength low alloy steels (minimum yield strengths at 960 MPa and 700 MPa, respectively) developed recently by Tata Steel. These steels are typically used in heavy lifting equipment. This research examines the feasibility and characteristics of single pass autogenous laser welding (ALW), multi-pass ultra-narrow gap laser welding (NGLW) of 8 mm thick S960 and 13 mm thick S700 high strength low alloy (HSLA) steels and compared the characteristics of the welds...

  2. 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 a

  3. 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.

  4. 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.

  5. Laser welding of venotomies.

    Science.gov (United States)

    White, R A; Abergel, R P; Klein, S R; Kopchok, G; Dwyer, R M; Uitto, J

    1986-08-01

    We investigated the histologic and biochemical effects of carbon dioxide and neodymium (Nd)-YAG laser welding on the healing of venotomies. Ten canine femoral venotomies 2 cm in length were approximated and welded with 10 600-nm wavelength, 1-W power over 20 to 25 s for CO2 laser, and 1060-nm wavelength, 1-W power over 30 to 40 s for Nd-YAG laser. On removal at one to three weeks, all veins (4/4 welded by CO2 and 6/6 by Nd-YAG) were patent without hematomas. Histologic and biochemical analyses of the venous tissues demonstrated active healing at the venotomy sites. We conclude that the CO2 and Nd-YAG lasers can be used successfully to weld venotomies and may provide an alternative to conventional suture techniques for repair of vascular lesions. PMID:3089196

  6. UNDERSTANDING POROSITY FORMATION AND PREVENTION WHEN WELDING TITANIUM ALLOYS WITH 1 μm WAVELENGTH LASER BEAMS

    OpenAIRE

    Blackburn, Jonathan

    2011-01-01

    Keyhole laser welding is a joining technology characterised by the high focussed power density applied to the workpiece, facilitating deep penetration at high processing speeds. High aspect-ratio welds produced using this process invariably have narrow heat-affected-zones and minimal thermal distortion compared with traditional arc welding processes. Furthermore, the ability to process out of vacuum and the easy robotic manipulation of fibre optically delivered 1μm wavelength laser beams, all...

  7. Laser spot welding of electronic micro parts

    Science.gov (United States)

    Ostendorf, Andreas; Temme, Thorsten; Zeadan, Jeihad

    2004-10-01

    This paper deals with parameter optimization and online monitoring of laser spot welding (LSW). Using Nd:YAG laser, a wide range of experiments regarding the welding process have been carried out for both successful and failed welds. The typical failures appearing during packaging of surface mounted devices (SMDs) on flexible printed circuits (FPC) include gaps, a loss of connection between the welded components, and damage of the printed circuit boards. A flip-flop device called SO16 and lead frames as two components of widely used SMDs were packaged on FPCs in the experiments. The reproducibility of the weld quality for SO16 (FeNi) is greater than for lead frames (CuFe2P); this points out the difficulties appearing during copper or copper alloy welding. However, a correlation between the weld quality and the detected emission signals recorded during the weld process has been found for both components. The detected signals of the optical process emission for successful welds depict identical characterisics which are divided into three relevant signal phases. Changes in the signal characteristics, especially in these phases, imply information about the weld quality. While monitoring the welding processes for both components are possible, the detected signals for SO16 are less sensitive to process variations compared to those for lead frames. Based on spectral analysis, the intensity of the detected emission due to SO16 welding is slightly higher than the intensity due to lead frames welding.

  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...... in the weld causing expulsion of the melt pool. Trailing beams were applied to melt additional material and ensure a melt pool. The method showed good results for increasing tolerances to impurities and reduction of scrapped parts from blowouts during laser welding....

  9. Laser welding engineering

    International Nuclear Information System (INIS)

    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

  10. Observation of changes in the metallurgical characteristics of Ni-Cr alloys using Nd:YAG laser welding.

    Science.gov (United States)

    Hong, Mh; Choi, Sm

    2014-01-01

    This study aimed to determine the effect of hardness change according to penetration depth in the laser fusing zone and observed the correlation of the microstructure as an Nd:YAG laser was irradiated to Ni-Cr alloy for dental use by setting the spot diameter size to various conditions. In all groups, the hardness depth profiles in the laser fusing zone and heat-affected zone (HAZ) had larger values than those of the base metal. In addition, the hardness values in places beyond the fusing zone and the HAZ were measured as being quantitatively lower. The observation result of the diffusion of the constituent elements and microstructure using field emission scanning electron microscopy, energy-dispersive spectroscopy, and electron probe microanalyzer showed that the fusing zone revealed a much finer dendritic form than the base metal due to the self-quenching effect after welding, while no change in constituent elements was found although some evaporation of the main elements was observed. In addition, Mo- and Si-combined intermetallic compounds were formed on the interdendritic area. Through this study, the laser fusing zone had better hardenability due to the intermetallic compound and grain refinement effect. PMID:25342985

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

    Science.gov (United States)

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

    2015-11-01

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

  12. Understanding metal vaporizaiton from laser welding.

    Energy Technology Data Exchange (ETDEWEB)

    DebRoy, Tarasankar (The Pennsylvania State University, University Park, PA); Fuerschbach, Phillip William; He, Xiuli (The Pennsylvania State University, University Park, PA); Norris, Jerome T.

    2003-09-01

    The production of metal vapor as a consequence of high intensity laser irradiation is a serious concern in laser welding. Despite the widespread use of lasers in manufacturing, little fundamental understanding of laser/material interaction in the weld pool exists. Laser welding experiments on 304 stainless steel have been completed which have advanced our fundamental understanding of the magnitude and the parameter dependence of metal vaporization in laser spot welding. Calculations using a three-dimensional, transient, numerical model were used to compare with the experimental results. Convection played a very important role in the heat transfer especially towards the end of the laser pulse. The peak temperatures and velocities increased significantly with the laser power density. The liquid flow is mainly driven by the surface tension and to a much less extent, by the buoyancy force. Heat transfer by conduction is important when the liquid velocity is small at the beginning of the pulse and during weld pool solidification. The effective temperature determined from the vapor composition was found to be close to the numerically computed peak temperature at the weld pool surface. At very high power densities, the computed temperatures at the weld pool surface were found to be higher than the boiling point of 304 stainless steel. As a result, vaporization of alloying elements resulted from both total pressure and concentration gradients. The calculations showed that the vaporization was concentrated in a small region under the laser beam where the temperature was very high.

  13. Weldability during the laser lap welding of Al 5052 sheets

    OpenAIRE

    J.-K. Kim; H.-S. Lim; J.-H. Cho; C.-H. Kim

    2008-01-01

    Purpose: The paper presents the effect of the laser welding parameters of the laser focal position, the weldingspeed and the laser output power on the weldability of Al the 5052 alloy during laser lap welding.Design/methodology/approach: Lap welding is conducted on an Al 5052 plate with a thickness of 1 mm.After welding, the bead surfaces and cross sections were evaluated with various laser welding parameters. Thedegree of porosity was also examined by X-ray transmission testing.Findings: The...

  14. Friction Stir Welding of Aluminum Alloys

    Institute of Scientific and Technical Information of China (English)

    FU Zhi-hong; HE Di-qiu; WANG Hong

    2004-01-01

    Friction stir welding(FSW), a new solid-state welding technology invited in the early 1990s,enables us weld aluminum alloys and titanium alloys etc. The processing of FSW, the microstructure in FSW alloysand the factors influencing weld quality are introduced. The complex factors affecting the properties are researched.

  15. Dissimilar joining of galvanized high-strength steel to aluminum alloy in a zero-gap lap joint configuration by two-pass laser welding

    International Nuclear Information System (INIS)

    Highlights: • Defect-free two-pass laser partially penetrated lap joint of galvanized steel to aluminum was achieved. • The thickness of the Al-rich intermetallic compounds could be controlled by optimal parameters. • The dynamic behavior of the molten pool and keyhole were monitored by a high speed charge-coupled device camera. • The presence of zinc in the intermetallic compounds could improve the strength of the lap joints. - Abstract: A welding procedure based on using two-pass laser scans is introduced for dissimilar joining of overlapped galvanized high-strength dual-phase (DP) steel DP590 to aluminum alloy (AA) 6061 sheets. The first pass is based on a defocused laser spot that scans across the top of the two overlapped sheets and heats the zinc coating at the faying surface to be melted and partially vaporized, while the second pass is executed with a focused laser spot in order to perform the welding. Completely defect-free galvanized steel to aluminum lap joints were obtained by using this two-pass laser welding procedure. An on-line machine vision system was applied to monitor the keyhole dynamics during the laser welding process. An energy-dispersive X-ray spectroscopy (EDS) was carried out to determine the atomic percent of zinc, aluminum, and iron in the galvanized steel to aluminum lap joints. Mechanical testing and micro-hardness test were conducted to evaluate the mechanical properties of the galvanized steel to aluminum lap joints. The experimental results showed that the lap joint of galvanized steel to aluminum obtained by the two-pass laser welding approach had a higher failure value than those joints obtained when the zinc at the faying surface was mechanically removed under the same welding speed and laser power

  16. Microgalvanic corrosion of laser-welded HSLA steels

    OpenAIRE

    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 at different microstructures of the weld, HAZ and the parent metal. Different microstructural substructures exhibit different electrochemical characteristics, potentially leading to microgalvanic co...

  17. Simulation of the elastic deformation of laser-welded joints of an austenitic corrosion-resistant steel and a titanium alloy with an intermediate copper insert

    Science.gov (United States)

    Pugacheva, N. B.; Myasnikova, M. V.; Michurov, N. S.

    2016-02-01

    The macro- and microstructures and the distribution of elements and of the values of the microhardness and contact modulus of elasticity along the height and width of the weld metal and heat-affected zone of austenitic corrosion-resistant 12Kh18N10T steel (Russian analog of AISI 321) and titanium alloy VT1-0 (Grade 2) with an intermediate copper insert have been studied after laser welding under different conditions. The structural inhomogeneity of the joint obtained according to one of the regimes selected has been shown: the material of the welded joint represents a supersaturated solid solution of Fe, Ni, Cr, and Ti in the crystal lattice of copper with a uniformly distributed particles of intermetallic compounds Ti(Fe,Cr) and TiCu3. At the boundaries with steel and with the titanium alloy, diffusion zones with thicknesses of 0.1-0.2 mm are formed that represent supersaturated solid solutions based on iron and titanium. The strength of such a joint was 474 MPa, which corresponds to the level of strength of the titanium alloy. A numerical simulation of the mechanical behavior of welded joints upon the elastic tension-compression has been performed taking into account their structural state, which makes it possible to determine the amplitude values of the deformations of the material of the weld.

  18. Study on laser beam welding technology for nuclear power plants

    International Nuclear Information System (INIS)

    Laser beam welding is one of the jointing processes by irradiating laser beam on the material surface locally and widely used at various industrial fields. Toshiba has developed various laser-based maintenance and repair technologies and already applied them to several existing nuclear power plants. Laser cladding is a technique to weld the corrosion resistant metal onto a substrate surface by feeding filler wire to improve the corrosion resistance. Temper-bead welding is the heat input process to provide the desired microstructure properties of welded low alloy steels without post weld heat treatment, by inducing proper heat cycle during laser welding. Both laser welding technologies would be performed underwater by blowing the shielding gas for creating the local dry area. In this report, some evaluation results of material characteristics by temper-bead welding to target at Reactor Coolant System nozzle of PWR are presented. (author)

  19. Development of multifunction laser welding head (1). Evaluation of under water laser welding with multifunction laser welding head

    International Nuclear Information System (INIS)

    Multifunction laser welding head has been developed. The head is able to perform not only underwater laser welding as repair, but also laser peening as preventive maintenance and laser ultrasonic testing as inspection. Laser transmission test with multifunction laser welding head and optical fiber was carried out. The result showed that laser power needed for welding was transmitted without any damage to them. Under water laser welding onto EDM slits with this welding head was carried out. EDM slits were sealed by deposited weld metal. It was confirmed that multifunction laser welding head was applied to under water laser welding. (author)

  20. Study of Mechanical Properties of AZ91 Magnesium Alloy Welded by Laser Process Taking into Account the Anisotropy Microhardness and Residual Stresses by X-Ray Diffraction

    Science.gov (United States)

    Kouadri, A.; Barrallier, L.

    2011-07-01

    The objective of this investigation was to study the mechanical properties of a magnesium alloy welded by a CO2 laser. Residual stresses were measured by X-ray diffraction. They were calculated by the classic sin2 ψ method in the isotropic zones by using the orientation distribution function (ODF) in the textured zones. The results demonstrated that laser welding results in the formation of several different zones with different microstructural and mechanical properties. Welding principally leads to a reduction in grain size and a new distribution of phases. The most remarkable observation was that of a superficial layer on the surface of the welded zone. This layer has a marked crystallographic texture, a reduction in the level of aluminum, and an elevated microhardness. These characteristics disappear at a depth of 200 μm under the welded zone. These modifications can be explained by the nature of the solidification, which occurs under nonequilibrium conditions resulting in an equiaxial columnar transition. This transition is evident also within the profile of residual tensile stresses, which are at their maximum at the interface between the superficial layer and the rest of the welded zone. These results are explained by the anisotropic properties of the textured layer in relation to the plasticity.

  1. Laser welding of cylindrical parts

    OpenAIRE

    Närhi-Ratkovskaia, Olga

    2011-01-01

    The purpose of this paper is to conduct the laser welding work of the cylindrical parts, particularly fuel filters, according to the safety instructions. The welding was followed by the additional test for a gas resistance of filters. The topic was commissioned by the company Laserplus Oy, located in Hämeenlinna. The aim of the project on laser welding of filters was to find out optimum parameters for the company’s welding. Optimum parameters include the minimum laser power with optimum ...

  2. Building A Simulation Model For The Prediction Of Temperature Distribution In Pulsed Laser Spot Welding Of Dissimilar Low Carbon Steel 1020 To Aluminum Alloy 6061

    International Nuclear Information System (INIS)

    This paper describes the development of a computer model used to analyze the heat flow during pulsed Nd: YAG laser spot welding of dissimilar metal; low carbon steel (1020) to aluminum alloy (6061). The model is built using ANSYS FLUENT 3.6 software where almost all the environments simulated to be similar to the experimental environments. A simulation analysis was implemented based on conduction heat transfer out of the key hole where no melting occurs. The effect of laser power and pulse duration was studied.Three peak powers 1, 1.66 and 2.5 kW were varied during pulsed laser spot welding (keeping the energy constant), also the effect of two pulse durations 4 and 8 ms (with constant peak power), on the transient temperature distribution and weld pool dimension were predicated using the present simulation. It was found that the present simulation model can give an indication for choosing the suitable laser parameters (i.e. pulse durations, peak power and interaction time required) during pulsed laser spot welding of dissimilar metals.

  3. Underwater YAG laser welding technique

    International Nuclear Information System (INIS)

    When planning preventive maintenance of reactor components using welding, it is necessary to consider special environments such as narrow space or difficult accessibility while minimizing exposure to radiation in the reactor pressure vessel. Toshiba has developed an underwater neodymium: yttrium-aluminum-garnet (Nd: YAG) laser welding technique. The features of this welding technique are low-heat-input welding and compact welding machine dimensions for welding in narrow spaces. This paper provides a summary of the new welding technique as a reliable welding technology. (author)

  4. 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

  5. Microstructure and Mechanical Properties of Laser-Welded Joints of Ti-22Al-25Nb/TA15 Dissimilar Titanium Alloys

    Science.gov (United States)

    Li, Dalong; Hu, Shengsun; Shen, Junqi; Zhang, Hao; Bu, Xianzheng

    2016-05-01

    Laser beam welding (LBW) was applied to join 1-mm-thick dissimilar titanium alloys, Ti-22Al-25Nb (at.%) and TA15, and the microstructure and mechanical properties of the welded joints were systematically analyzed. Defect-free joints were obtained, and the fusion zone mainly consisted of B2 and martensitic α' phases because of the uneven distribution of the β phase stabilizer and rapid cooling rate of LBW. The phase compositions of the heat-affected zone varied with the different thermal cycles during the welding process. The different microstructures of the dissimilar titanium alloys led to an unsymmetrical hardness profile, with the welded seam exhibiting the lowest value of 271 HV. In room-temperature tensile tests, the fractures all occurred preferentially in the fusion zone. The strengths of the joints were close to those of the base metal but with prominently decreasing ductility. In tensile tests performed at 550 °C, all the joints fractured in the TA15 base metal, and the strength and plasticity of the welds were equivalent to those of the TA15 base metal.

  6. THE INFLUENCE OF SCREW TYPE, ALLOY AND CYLINDER POSITION ON THE MARGINAL FIT OF IMPLANT FRAMEWORKS BEFORE AND AFTER LASER WELDING

    Science.gov (United States)

    Castilio, Daniela; Pedreira, Ana Paula Ribeiro do Vale; Rossetti, Paulo Henrique Orlato; Rossetti, Leylha Maria Nunes; Bonachela, Wellington Cardoso

    2006-01-01

    Misfit at the abutment-prosthetic cylinder interface can cause loss of preload, leading to loosening or fracture of gold and titanium screws. Objectives: To evaluate the influence of screw type, alloy, and cylinder position on marginal fit of implant frameworks before and after laser welding. Methods: After Estheticone-like abutments were screwed to the implants, thirty plastic prosthetic cylinders were mounted and waxed-up to fifteen cylindrical bars. Each specimen had three interconnected prosthetic components. Five specimens were one-piece cast in titanium and five in cobalt-chromium alloy. On each specimen, tests were conducted with hexagonal titanium and slotted gold screws separately, performing a total of thirty tested screws. Measurements at the interfaces were performed using an optical microscope with 5 μm accuracy. After sectioning, specimens were laser welded and new measurements were obtained. Data were submitted to a four-way ANOVA and Tukey's multiple comparisons test (α =0.05). Results: Slotted and hexagonal screws did not present significant differences regarding to the fit of cylinders cast in titanium, either in one-piece casting framework or after laser welding. When slotted and hexagonal screws were tested on the cobalt-chromium specimens, statistically significant differences were found for the one-piece casting condition, with the slotted screws presenting better fit (24.13μm) than the hexagonal screws (27.93 μm). Besides, no statistically significant differences were found after laser welding. Conclusions: 1) The use of different metal alloys do exert influence on the marginal fit, 2) The slotted and hexagonal screws play the exclusive role of fixing the prosthesis, and did not improve the fit of cylinders, and 3) cylinder position did not affect marginal fit values. PMID:19089035

  7. Position welding using disk laser-GMA hybrid welding

    OpenAIRE

    C.-H. Kim; H.-S. Lim; J.-K. Kim

    2008-01-01

    Purpose: Position welding technology was developed by using disk laser-GMA hybrid welding in this research.Design/methodology/approach: The effect of hybrid welding parameters such as the shielding gas composition and laser-arc interspacing distance were investigated for the bead-on-plate welding. The pipe girth welding was implemented and the adequate arc welding parameters were selected according to the welding position from a flat position to an overhead position.Findings: The optimized sh...

  8. Position welding using disk laser-GMA hybrid welding

    Directory of Open Access Journals (Sweden)

    C.-H. Kim

    2008-05-01

    Full Text Available Purpose: Position welding technology was developed by using disk laser-GMA hybrid welding in this research.Design/methodology/approach: The effect of hybrid welding parameters such as the shielding gas composition and laser-arc interspacing distance were investigated for the bead-on-plate welding. The pipe girth welding was implemented and the adequate arc welding parameters were selected according to the welding position from a flat position to an overhead position.Findings: The optimized shielding gas composition and laser-arc interspacing distance for disk laser-GMA hybrid welding were 80% Ar- 20% CO2 and 2mm, respectively for the bead-on-plate welding. The sound welds could be achieved even in the pipe girth welding, but the proper joint shape should be prepared.Research limitations/implications: The laser-arc hybrid welding was implemented for pipe girth welding as a kind of 3-dimensional laser welding and the process parameters could be optimized according to the various target materials and sizes.Practical implications: The optimized process parameters for the disk laser-arc hybrid welding can extend the application of the laser hybrid welding technology.Originality/value: This research showed the possibility of the disk laser-GMA hybrid welding as new pipe girth welding technique. The behaviour of molten pool and droplet transfer could enhance understanding of the hybrid welding.

  9. New Technology In Laser Welding Of Thin Filaments

    Science.gov (United States)

    Li, Yongzeng; Zhang, Qiu'e.; Ma, Shulin; Li, Yongda; Tian, Fenggui

    1987-01-01

    It is difficult to get a good welding spot and nearly impossible to weld a 10 micron diameter filament (e.g. NiCr) onto a foreign workpiece over 1000 times larger in size. In this paper we introduce the laser powder-covered welding technique. The first step is to laser- weld a metal powder onto a small area of interest of a larger-sized workpiece. This changes the nature of the larger-sized material. The second step is to position the thin filament in contact with the larger workpiece and to apply the pulsed laser so a round and smooth welding spot forms. This should form a good alloy combination. This welding technique has a high success rate for welding minute electrical heat source, independent of the material of the larger workpiece. This technique also solves the problems of unstable quality in tin welding, burrs in pressure welding, and eliminates the problem of welding flux corrosion. This same technique is applied to the laser-welding of a super-thin piece to a foreign workpiece, where the welding spot forms a "micro-rivet': In the paper we present specific conditions required, the analysis data of the welding quality and the specific structure of the laser-welding workstation.

  10. Comparative evaluation of tungsten inert gas and laser beam welding of AA5083-H321

    Indian Academy of Sciences (India)

    K Subbaiah; M Geetha; B Shanmugarajan; S R Koteswara Rao

    2012-10-01

    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 size of the fusion zone and heat affected zone compared to tungsten inert gas welding process. High speed LB welding and fast heating and cooling of LB welding process hinders grain growth compared to TIG welding process. The effect of vapourization of volatile alloying elements is also considered. It seems that magnesium evaporation is relatively less in LB welding compared to TIG welding. Tensile testing of the welded joints revealed that LB welding results in superior mechanical properties. It is concluded that LB welding process is more suitable to join AA5083-H321.

  11. 激光焊接新型钴铬合金的力学性能%Mechanical study of laser welded new Co-Cr alloy

    Institute of Scientific and Technical Information of China (English)

    梁锐英; 赵艳萍; 温黎明; 白宇宏; 吴文慧; 徐艳丽; 孟贺

    2011-01-01

    BACKGROUND: There are no reports on laser welding about a kind of Co-Cr alloys, which do not include Ni and Be nowadays.OBJECTIVE: To apply laser welding technique to prepare a new Co -Cr alloy in order to provide welding parameters for clinicapplication.METHODS: Sixty plastic plate patterns (0.5 mm×6 mm×30 mm) were casted from new Co-Cr alloy. All the plates were randomlydivided into 6 groups, one as control group, and the others as examination group. The plates of examination group wereperpendicularly cut at the center of the plates. After the cut halves we re fixed in a jig, they were laser welded using a NG:YAGlaser at a several level output energy in increments of 30 V from 220 to 340 V. The spot diameter and pulse duration employedwas 0.6 mm and 10 ms. Uncut specimens served as the non-welded control specimens. Tensile testing was conducted and thebreaking force was recorded and the data was statistically analyzed.RESULTS AND CONCLUSION: The tensile strength of laser welding New Co -Cr alloys increased with the electric voltage. Theelongation increased with the electric voltage at the electric voltage lower than 280 V, but showed contrary trend when the electricvoltage higher than 280 V. The tensile strength and elongation was (679.94±46.87) MPa and (5.91±0.38)% respectively at theoptimized welding parameters. The tensile strength and elongation of laser welded New Co -Cr alloy under the optimizedparameters (280 V, 10 ms, spot diameter 0.6 mm) can be satisfied with the clinical requirement.%背景:新型钴铬合金为一种不含镍和铍等有害成分的齿科合金材料,但关于其激光焊接的研究尚未见报道.目的:分析新型钴铬合金的激光焊接参数,优选激光焊接电压条件.方法:铸造0.5 mm×6 mm×30 mm的新型钴铬合金试件60个,将试件分成6组.1组作为对照组;5组试件从中间断开,进行激光焊接,光斑直径设定为0.6 mm,脉冲持续时间10 ms,电压分别为220,250,280,310,340 V,焊后进行

  12. 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...

  13. Effects of Weaving Laser on Weld Microstructure and Crack for Al 6k21-T4 Alloy

    Institute of Scientific and Technical Information of China (English)

    B.H. Kim; N.Y. Kang; W.T. Oh; C.H. Kim; J.H. Kim; Y.S. Kim; Y.H. Park

    2011-01-01

    For Al 6k21-T4 overlap weld joint, the shear-tensile strength by using the weaving laser was improved as compared to the case of linear laser. For the specimen of low strength, the porosity was distributed continuously along the intersection between the plates and fusion line. However, for the optimized welding condition, large oval-shaped porosities were located only in the advancing track of the concave part. Therefore, the continuity of cracks and porosities played a key role to determine the strength. And, the weaving width was also the important parameter to control the strength. Furthermore, the concave part had more significant hot and cold cracking in the weld and heat-affected zone (HAZ), respectively, than the convex part.

  14. Development of underwater welding with high power YAG laser

    International Nuclear Information System (INIS)

    Due to its compact size and use of optical fibers, the high-powered (about 4 kW) YAG laser can be used for underwater welding in tight spaces, making it highly suitable for applications in repair welding in Reactor Pressure vessels, RPV and RPV internals in operational nuclear power plants. Stable welding beads were attained with type 304 stainless steels and inconel alloys as the welding metals using the simple sealed method YAG laser welding both in a shallow water tank and in a pressure chamber up to 0.4 MPa pressurized atmosphere. (author)

  15. Alloy 800 welding experience at UKAEA Springfields

    International Nuclear Information System (INIS)

    Investigatins into the welding of alloy 800 at the Reactor Fuel Element Laboratories, Springfields, commenced about three years ago following an extended development programme on tube to tube plate welding of low alloy and stainless steels for the Prototype Fast Reactor. The techniques and approach developed for critical fuel element welding applications had proved equally suitable for the precision welding requirements on the much heavier sections of heat exchangers. It had been demonstrated that the same control of weld quality and profile could be achieved with consistency and the permissible range of critical parameters could be readily defined. Because of this, development work was continued to include other materials, such as alloy 800, which might be of potential use. The tungsten inert gas (T.I.G.) arc welding process is used, and the equipment, including the control system, is described. Tube to tube-plate welding, and tube to tube butt welding, are discussed. (author)

  16. Dissimilar laser welding of AISI 316L stainless steel to Ti6–Al4–6V alloy via pure vanadium interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Tomashchuk, I., E-mail: iryna.tomashchuk@u-bourgogne.fr; Grevey, D.; Sallamand, P.

    2015-01-12

    Successful continuous laser joining of AISI 316L stainless steel with Ti6Al4V titanium alloy through pure vanadium interlayer has been performed. Three welding configurations were tested: one-pass welding involving all three materials and two pass and double spot welding involving creation of two melted zones separated by remaining solid vanadium. For the most relevant welds, the investigation of microstructure, phase content and mechanical properties has been carried out. In case of formation of a single melted zone, the insertion of steel elements into V-based solid solution embrittles the weld. In case of creation of two separated melted zones, the mechanical resistance of the junction is determined by annealing of remaining vanadium interlayer, which can be witnessed by observing the increase of grain size and decrease of UTS. The two pass configuration allows attain highest mechanical resistance: 367 MPa or 92% of UTS of annealed vanadium. Double spot configuration produces excessive heat supply to vanadium interlayer, which results in important decrease of tensile strength down to 72% of UTS of annealed vanadium. It was found that undesirable σ phase which forms between Fe and V is not created during the laser welding process because of high cooling rates. However, the zones whose composition corresponds to σ homogeneity range are crack-susceptible, so the best choice is to reduce the V content in steel/vanadium melted zone below σ phase formation limit. In the same time, the proportion between V and Ti in Ti6Al4V/vanadium melted zones does not influence mechanical properties as these elements form ideal solid solution.

  17. Dissimilar laser welding of AISI 316L stainless steel to Ti6–Al4–6V alloy via pure vanadium interlayer

    International Nuclear Information System (INIS)

    Successful continuous laser joining of AISI 316L stainless steel with Ti6Al4V titanium alloy through pure vanadium interlayer has been performed. Three welding configurations were tested: one-pass welding involving all three materials and two pass and double spot welding involving creation of two melted zones separated by remaining solid vanadium. For the most relevant welds, the investigation of microstructure, phase content and mechanical properties has been carried out. In case of formation of a single melted zone, the insertion of steel elements into V-based solid solution embrittles the weld. In case of creation of two separated melted zones, the mechanical resistance of the junction is determined by annealing of remaining vanadium interlayer, which can be witnessed by observing the increase of grain size and decrease of UTS. The two pass configuration allows attain highest mechanical resistance: 367 MPa or 92% of UTS of annealed vanadium. Double spot configuration produces excessive heat supply to vanadium interlayer, which results in important decrease of tensile strength down to 72% of UTS of annealed vanadium. It was found that undesirable σ phase which forms between Fe and V is not created during the laser welding process because of high cooling rates. However, the zones whose composition corresponds to σ homogeneity range are crack-susceptible, so the best choice is to reduce the V content in steel/vanadium melted zone below σ phase formation limit. In the same time, the proportion between V and Ti in Ti6Al4V/vanadium melted zones does not influence mechanical properties as these elements form ideal solid solution

  18. Industrial laser welding evaluation study

    Science.gov (United States)

    Hella, R.; Locke, E.; Ream, S.

    1974-01-01

    High power laser welding was evaluated for fabricating space vehicle boosters. This evaluation was made for 1/4 in. and 1/2 in. aluminum (2219) and 1/4 in. and 1/2 in. D6AC steel. The Avco HPL 10 kW industrial laser was used to perform the evaluation. The objective has been achieved through the completion of the following technical tasks: (1) parameter study to optimize welding and material parameters; (2) preparation of welded panels for MSFC evaluation; and (3) demonstration of the repeatability of laser welding equipment. In addition, the design concept for a laser welding system capable of welding large space vehicle boosters has been developed.

  19. The Effects of Welding Parameters on the Mechanical Properties on Laser Welding of AA2024

    OpenAIRE

    Adnan Akkurt; Aydın Şık; İsmail Ovalı

    2012-01-01

    In this study, the effects of laser welding parameters on the mechanical properties of AA2024 aluminum parts jointed with laser welding were investigated in the laser welding process this has been started using on joint of aluminum alloy. The reason preferring of AA2024 is that aluminum material has been widely used in aerospace and manufacturing industry. Laser power (kW), laser intensity (kW/mm2) and Pulse energy (j) were selectedas process parameters. For this reason, all samples were clas...

  20. Fatigue resistance of titanium laser and hybrid welded joints

    International Nuclear Information System (INIS)

    This paper presents a detailed study on fatigue strength of welded joints made of two titanium alloys, grade 2 and grade 5, and welded by laser or hybrid process. Fatigue strength curves obtained for each alloy and each welding technique are compared in terms of safety factors with fatigue design curves of welded joints provided by standards. Material and welding process effects on fatigue strength are discussed; the influence of the weld seam geometry is assessed by evaluating the fatigue strength reduction factor. This parameter is computed by using the Volumetric Method of the Notch Fracture Mechanics and defined as the ratio of the effective stress and the gross stress. Effective stress is defined on the weld toe stress distribution by the minimum of relative stress gradient method. Distribution of opening stress at weld toe is analysed also with the finite element analysis.

  1. Laser welding of a tube

    International Nuclear Information System (INIS)

    For sleeving PWR steam generator tubes, the welding laser work is made under protection of a primary gas going out by the crossing window of the laser and under a secondary gas flowing axially through the head and the tube

  2. Laser welding of thermoplastic materials.

    Science.gov (United States)

    Chipperfield, F A; Jones, I A

    2001-06-01

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

  3. 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

  4. Integrated sensors for robotic laser welding

    OpenAIRE

    Iakovou, D.; Aarts, R.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 well as the quality of the welding result. In this paper the focus is on seam tracking. It is difficult to measure three-dimensional parameters of a ream during a robotic laser welding task, espec...

  5. Peculiarities of weld crystallization in the process of laser welding

    International Nuclear Information System (INIS)

    The effect of the process of laser welding of 08Kh18N10T steel on weld formation and crystallization is investigated. It is shown that at vsub(weld.) >= 40 m/h the lower sinked part of the weldpool stretched along the weld axis is crystallized quickly. Improvement in hot cracking resistance of weld metal in the process of laser welding results from the additional feeding with a liquid metal of the crystallizing part of the weldpool

  6. Dissimilar welding of WC-Co cemented carbide to Ni42Fe50.9C0.6Mn3.5Nb3 invar alloy by laser-tungsten inert gas hybrid welding

    International Nuclear Information System (INIS)

    Dissimilar welding between cemented carbide and invar alloy was carried out using CO2 laser beam and argon arc as heat sources. η Phase was formed near WC-Co/weld interface and precipitations in the fracture were discovered. In order to disclose the microstructure and mechanical property, firstly, η phase's morphology and composition at interface were investigated using backscattered electron imaging (BEI); and element diffusion across heat affected zone near WC-Co/weld interface was further studied. Secondly, bend strength values of butt joint with different welding parameters were tested by four-point bend strength experiment. Finally, WC migration mechanism was further discussed and the bend strength was measured. The results showed: (1) microstructures consisted of columnar crystals, cellular crystals, eutectic structure and fir-tree crystal and dendritic crystals. The columnar crystals were surrounded by lots of fir-tree crystals. (2) WC migration was driven by stirring effects of welds, high pressure of molten materials and ionized shielding gas, interface reaction and surface tension. (3) η Phases dispersion did not decrease bend strength of butt joint. And the maximum bend strength was 1493.56 MPa, which was attributed to NbC precipitations featured with super-fine fir-tree.

  7. Laser welding of tailored blanks

    International Nuclear Information System (INIS)

    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 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 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

  8. Elucidation of phenomena in high-power fiber laser welding and development of prevention procedures of welding defects

    Science.gov (United States)

    Katayama, Seiji; Kawahito, Yousuke

    2009-02-01

    Fiber lasers have been receiving considerable attention because of their advantages of high power, high beam quality and high efficiency, and are expected as one of the desirable heat sources for high-speed and deep-penetration welding. In our researches, therefore, the effects of laser powers and their densities on the weld penetration and the formation of sound welds were investigated in welding of Type 304 austenitic stainless steel, A5052 aluminum alloy or high strength steel plates with four laser beams of about 0.12 to 1 mm in focused spot diameter, and their welding phenomena were observed with high-speed video cameras and X-ray transmission real-time imaging system. It was found that the laser power density exerted a remarkable effect on the increase in weld penetration at higher welding speeds, but on the other hand at low welding speeds deeper-penetration welds could be produced at higher power. Laser-induced plume behavior and its effect on weld penetration, and the mechanisms of spattering, underfilling, porosity and humping were elucidated, sound welds without welding defects could be produced under the improved welding conditions. In addition, importance of the development of focusing optics and the removal of a plume during remote welding will be emphasized in terms of the stable production of constant deep-penetration welds and the reduction in welding defects in high power laser welding.

  9. 工艺参数对激光焊接镁合金气孔率的影响%Effect of Laser Welding Parameters on Porosity Rate in Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    郭彦兵; 童彦刚; 贺晓娜; 邓彩萍

    2011-01-01

    采用CO2激光器对挤压成型的镁合金板材AZ31B进行平板拼焊,对不同焊接参数条件下焊缝的气孔率进行分析,从而弄清了激光焊接参数对其气孔率的影响,为进一步研究降低镁合金激光焊的气孔率奠定了基础.%The CO2 laser weld was carried out on AZ31B extruded alloy.The effects of laser welding parameters on the porosity rate in laser beads were studied under different experimental method.The study lays down a solid foundation for reducing the porosity rate of magnesium alloy in laser welding.

  10. Welding of gamma titanium aluminide alloys

    Science.gov (United States)

    Smashey, Russell W. (Inventor); Kelly, Thomas J. (Inventor); Snyder, John H. (Inventor); Sheranko, Ronald L. (Inventor)

    1998-01-01

    An article made of a gamma titanium aluminide alloy is welded, as for example in the weld repair of surface cracks, by removing foreign matter from the area to be welded, first stress relieving the article, cooling the entire article to a welding temperature of from about 1000.degree. F. to about 1400.degree. F., welding a preselected region in an inert atmosphere at the welding temperature, and second stress relieving the article. Welding is preferably accomplished by striking an arc in the preselected region so as to locally melt the alloy in the preselected region, providing a filler metal having the same composition as the gamma titanium aluminide alloy of the article, and feeding the filler metal into the arc so that the filler metal is melted and fused with the article to form a weldment upon solidification.

  11. 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. PMID:20437262

  12. Development of automatic laser welding system

    International Nuclear Information System (INIS)

    Laser are a new production tool for high speed and low distortion welding and applications to automatic welding lines are increasing. IHI has long experience of laser processing for the preservation of nuclear power plants, welding of airplane engines and so on. Moreover, YAG laser oscillators and various kinds of hardware have been developed for laser welding and automation. Combining these welding technologies and laser hardware technologies produce the automatic laser welding system. In this paper, the component technologies are described, including combined optics intended to improve welding stability, laser oscillators, monitoring system, seam tracking system and so on. (author)

  13. Sensor integration for robotic laser welding processes

    NARCIS (Netherlands)

    Iakovou, Dimitrios; Aarts, Ronald; Meijer, Johan

    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,

  14. Electron beam, laser beam and plasma arc welding studies

    Science.gov (United States)

    Banas, C. M.

    1974-01-01

    This program was undertaken as an initial step in establishing an evaluation framework which would permit a priori selection of advanced welding processes for specific applications. To this end, a direct comparison of laser beam, electron beam and arc welding of Ti-6Al-4V alloy was undertaken. Ti-6Al-4V was selected for use in view of its established welding characteristics and its importance in aerospace applications.

  15. 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...

  16. Weldability during the laser lap welding of Al 5052 sheets

    Directory of Open Access Journals (Sweden)

    J.-K. Kim

    2008-06-01

    Full Text Available Purpose: The paper presents the effect of the laser welding parameters of the laser focal position, the weldingspeed and the laser output power on the weldability of Al the 5052 alloy during laser lap welding.Design/methodology/approach: Lap welding is conducted on an Al 5052 plate with a thickness of 1 mm.After welding, the bead surfaces and cross sections were evaluated with various laser welding parameters. Thedegree of porosity was also examined by X-ray transmission testing.Findings: The influences of the focal point, the laser power and the welding speed on the formation of bead andon the degree of porosity were experimentally investigated. The bead quality was improved when the beam wasdefocused compared to when it was focused on the surface. It was found that the porosity decreased when the heatinput is lowered, except when the lower plate is not melted.Research limitations/implications: Various types of aluminium alloys, such as sheet, extrusion and castingtypes, are used industrially in diverse combinations. Therefore, it is necessary to evaluate the weldabilities ofthese materials. This research is limited to Al 5052 alloys at present plans are underway to expand it to variousaluminium based alloys.Practical implications: Automotive industries are continuously increasing their use of aluminium alloys inmanufacturing. The results of this research can be referred to by the automotive industry as a basic technique.Originality/value: This research shows the influence of different welding parameters on the weldability duringthe lap welding of Al 5052 Al alloy. The results are based on the extensive experiments.

  17. Picosecond laser welding of optical to metal components

    Science.gov (United States)

    Carter, Richard M.; Troughton, Michael; Chen, Jinanyong; Elder, Ian; Thomson, Robert R.; Lamb, Robert A.; Esser, M. J. Daniel; Hand, Duncan P.

    2016-03-01

    We report on practical, industrially relevant, welding of optical components to themselves and aluminum alloy components. Weld formation is achieved through the tight focusing of a 5.9ps, 400kHz Trumpf laser operating at 1030nm. By selecting suitable surface preparation, clamping and laser parameters, the plasma can be confined, even with comparatively rough surfaces, by exploiting the melt properties of the glass. The short interaction time allows for a permanent weld to form between the two materials with heating limited to a region ~300 µm across. Practical application of these weld structures is typically limited due to the induced stress within the glass and, critically, the issues surrounding post-weld thermal expansion. We report on the measured strength of the weld, with a particular emphasis on laser parameters and surface preparation.

  18. Monitoring of solidification crack propagation mechanism in pulsed laser welding of 6082 aluminum

    Science.gov (United States)

    von Witzendorff, P.; Kaierle, S.; Suttmann, O.; Overmeyer, L.

    2016-03-01

    Pulsed laser sources with pulse durations in the millisecond regime can be used for spot welding and seam welding of aluminum. Seam welds are generally produced with several overlapping spot welds. Hot cracking has its origin in the solidification process of individual spot welds which determines the cracking morphology along the seam welding. This study used a monitoring unit to capture the crack geometry within individual spot welds during seam welding to investigate the conditions for initiation, propagation and healing (re-melting) of solidification cracking within overlapping pulsed laser welds. The results suggest that small crack radii and high crack angles with respect to welding direction are favorable conditions for crack healing which leads to crack-free seam welds. Optimized pulse shapes were used to produce butt welds of 0.5 mm thick 6082 aluminum alloys. Tensile tests were performed to investigate the mechanical strength in the as-welded condition.

  19. The Effects of Welding Parameters on the Mechanical Properties on Laser Welding of AA2024

    Directory of Open Access Journals (Sweden)

    Adnan Akkurt

    2012-01-01

    Full Text Available In this study, the effects of laser welding parameters on the mechanical properties of AA2024 aluminum parts jointed with laser welding were investigated in the laser welding process this has been started using on joint of aluminum alloy. The reason preferring of AA2024 is that aluminum material has been widely used in aerospace and manufacturing industry. Laser power (kW, laser intensity (kW/mm2 and Pulse energy (j were selectedas process parameters. For this reason, all samples were classified for three groups and different parameter was compared in every group. Microstructure characterization, micro hardness measuring and tensile test were carried out in order to understand the effects of welding parameters on mechanical properties. Experimental study showed that the optimum mechanical properties were obtained on first group samples. Heat effected zoneis widen with increasing of laser power and this result causes the negative effects on mechanical properties.

  20. Inverter DC resistance spot welding of magnesium alloy AZ31

    OpenAIRE

    Hwang, I. S.; D. C. Kim; Kang, M. J.

    2011-01-01

    Purpose: The welding lobes of AC resistance spot welding and inverter DC resistance spot welding for the magnesium alloy sheet AZ31 were compared and analyzed.Design/methodology/approach: Using the welding lobe in terms of electrode force, weld time, and weld current which are process variables of the resistance spot welding, optimal welding conditions were determined. The lower limit of the range of the optimal welding condition was decided by minimum shear tension strength for the magnesium...

  1. 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)

  2. Laser spot welding of cobalt-based amorphous metal foils

    International Nuclear Information System (INIS)

    The results concerning weldability of amorphous alloy (VAC 6025F) in shape of foils and the quality of laser-spot welded joints are presented in this paper. The aim of the research was the production of a high quality welding joint, by preserving the amorphous structure. The quality of the joint was tested by shear strength analysis and microhardness measuring. The metallographic studies were made by using optical microscope and SEM. The results show that (1) overlapped Co based amorphous metals foils can be welded with high-quality by a pulsed Nd: YAG-Laser, but only within a very narrow laser parameter window; (2) the laser welded spots show comparably high strength as the basic material; (3) the structure of the welded spot remains amorphous, so that the same characteristics as the base material can be achieved. (author)

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

    DEFF Research Database (Denmark)

    Juhl, Thomas Winther; Olsen, Flemming Ove

    2003-01-01

    given. Results from the solidification rate measurements had high variations. They do not show an expected correlation between the crack resistance and the solidification rate. The employment of pulsed seam welds is assessed not to be usable in the present measurement method. From evaluation of several......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...... crack tests, the Weeter spot weld test has been chosen to form a basis for the development of a practicable method to select specific alloys for welding applications. A new test, the Groove weld test was developed, which has reduced the time consumption and lightened the analysis effort considerably...

  4. Experimental study on activating welding for aluminum alloys

    Institute of Scientific and Technical Information of China (English)

    Huang Yong; Fan Ding

    2005-01-01

    TIG welding and EB welding for aluminum alloy 3003 were carried out to study the effects of activating flux on weld penetration of activating welding for aluminum alloys. SiO2 was used as the activating flux. It is found that, SiO2 can increase the weld penetration and decrease the weld width of FBTIG when the flux gap is small. For A-TIG welding and EB welding with focused mode, the weld penetrations and the weld widths increase simultaneously. SiO2 has little effect on the weld penetration and weld width of EB welding with defocused mode. It is believed that, change of surface tension temperature gradient is not the main mechanism of SiO2 improving weld penetration of activating welding for aluminum alloys.

  5. Etude expérimentale du soudage par laser YAG de l'alliage base nickel Hastelloy X Experimental study of YAG laser welding of nickel base alloy Hastelloy X

    Directory of Open Access Journals (Sweden)

    Graneix Jérémie

    2013-11-01

    Full Text Available Le procédé de soudage laser YAG est envisagé pour remplacer le procédé de soudage TIG manuel pour la réalisation de pièces de turboréacteur en alliage nickel-chrome-molybdène Hastelloy X. Cette étude expérimentale a permis de définir un domaine de soudabilité de cet alliage répondant aux critères spécifiques du secteur aéronautique. The YAG laser welding process is contemplated to replace the manual TIG welding process for the production of parts of turbojet in Hastelloy X. This experimental study has identified the field of weldability of this alloy to meet the specific requirements of the aerospace industry.

  6. Diffusion welding of commercial titanium alloys

    International Nuclear Information System (INIS)

    The weldability is studied of several industrial titanium alloys variously combined one to another in vacuum diffusion welding. Experimental results have been analyzed with reference to a model of electron localization. It is shown that the weldability is best in pairs, in which the electron exchange is conducive to electron localization, whereas the optimum temperatures of welding are those which enhance electron localization

  7. 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.

  8. Influence of component geometry and alloying elements on the welding characteristicsof steels for laser welding. Final report; Einfluss der Bauteilgeometrie und der Legierungselemente auf die Schweisseignung von Staehlen zum Laserstrahlschweissen. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Cramer, H.

    2002-01-01

    The project investigated the laser welding characteristics as well as the influence of welding parameters and weld geometry on the weld quality and mechanical characteristics of multiphase steels and higher-alloyed carbon steels. The investigated steels, i.e. the multiphase steels DP 500-03 (s=1.6 mm), DP 600 Z 140 (s=1.0 mm), DP-K 35/60 (s=1.6 mm) and TRIP 800 (s=1.2 mm) had crack-free welds with high strength and good deformation characteristics in the investigated parameter range (variation of energy, focus position, working gas, component geometry). The maximum hardness was 430 HV2 for DP 500-03, 420 HV2 for DP 600 Z 140, 430 HV2 for DP-K 34/60, and 580 HV2 for TRIP 800. Equally good results were obtained with high-alloy chromium steels, i.e. X20Cr13 and X46Cr13. Both steels were welded crack-free, with a maximum hardness of 690 HV2 in both cases. The tempered steel 51CrV4 was not weldable crack-free with the investigated parameters and geometries. (orig.) [German] Das Forschungsvorhaben untersucht die Laserstrahlschweisseignung sowie den Einfluss der Schweissparameter und der Nahtgeometrie auf die Nahtguete und die mechanischen Eigenschaften bei Mehrphasenstaehlen und hoeherkohlenstoffhaltigen, legierten Staehlen. Die vorliegenden Mehrphasenstaehle DP 500-03 (s=1,6 mm), DP 600 Z 140 (s=1,0 mm), DP-K 35/60 (s=1,6 mm) und TRIP 800 (s=1,2 mm) weisen im untersuchten Parameterbereich (Variation der Streckenenergie, der Fokuslage, des Arbeitsgases, der Bauteilgeometrie) trotz hoher Maximalhaerten rissfreie Laserstrahlschweissnaehte mit guten Festigkeits- und Verformungseigenschaften auf. Die Maximalhaerten liegen beim DP 500-03 bei 430 HV2, beim DP 600 Z 140 bei 420 HV2, der DP-K 34/60 bei 430 HV2 und beim TRIP 800 bei 580 HV2. Auch die hochlegierten Chromstaehle X20Cr13 und X46Cr13 koennen mit hohen Nahtgueten (Bewertungsgruppe B) und guten Festigkeitseigenschaften (die im Streubereich des Grundwerkstoffes liegen) rissfrei laserstrahlgeschweisst werden (I

  9. Refractory metal welding using a 3.3 kW diode pumped Nd:YAG laser.

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, R. W. (Robert W.); Piltch, M. S. (Martin S.); Nemec, R. B. (Ronald B.); Milewski, J. O. (John O.)

    2001-01-01

    Recent developments in multi-kilowatt continuous wave lasers allow fiber optic delivery to high-purity controlled atmosphere chambers and challenge electron beam welding with improvements in cost, complexity, beam quality and flexibility. Questions remain with respect to the performance of these lasers for refractory alloy welding regarding damaging back reflections, laser-plume interactions, and sufficiency of beam intensity and coupled energy. System performance for the welding of various refractory metal alloys and comparisons to electron beam welds will be presented.

  10. Investigation on fracture toughness of laser beam welded steels

    International Nuclear Information System (INIS)

    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 CO2 laser process. Microhardness measurements were conducted to determine the hardness profiles of the joints. Flat micro-tensile 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 strength 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.)

  11. Investigation of Laser Parameters in Silicon Pulsed Laser Conduction Welding

    Science.gov (United States)

    Shayganmanesh, Mahdi; Khoshnoud, Afsaneh

    2016-03-01

    In this paper, laser welding of silicon in conduction mode is investigated numerically. In this study, the effects of laser beam characteristics on the welding have been studied. In order to model the welding process, heat conduction equation is solved numerically and laser beam energy is considered as a boundary condition. Time depended heat conduction equation is used in our calculations to model pulsed laser welding. Thermo-physical and optical properties of the material are considered to be temperature dependent in our calculations. Effects of spatial and temporal laser beam parameters such as laser beam spot size, laser beam quality, laser beam polarization, laser incident angle, laser pulse energy, laser pulse width, pulse repetition frequency and welding speed on the welding characteristics are assessed. The results show that how the temperature dependent thermo-physical and optical parameters of the material are important in laser welding modeling. Also the results show how the parameters of the laser beam influence the welding characteristics.

  12. Properties of welded joints produced by a high power laser beam

    International Nuclear Information System (INIS)

    Bending, tensile and impact tests are carried out using two low-alloy steels to find possibilities of CO2 high power laser application for welding steel with through penetration. It is shown that welding with 20KW beam at the velocity of 90 m/h gives the possibility to weld 8-15 mm thick plates possessing satisfactory mechanical properties. It is pointed out, that in spite of the martensite presence in weld metal and heat affected zone, a weld has the strength no less than the basic metal. Impact strength values of laser welded joints are higher than those of submerged arc welded joints

  13. Defects elimination during neodymium laser welding of low thickness samples

    International Nuclear Information System (INIS)

    The YAG pulsed LASER welding concern small sized samples, generally austenitic steels or zircaloy. Above samples are parts of a nuclear prototype combustible elements as parts of irradiation systems, or instrument sensors of the mentioned systems. The welding configuration is merely of a complex form. In general, the observed welding bead failures are gas pockets of a spherical configuration (zirconium and its alloys), internal welding microcracks in the melted area, or even a thermally area debasement (austenitic steels with low ferrite content). (author). 5 refs., 13 figs., 1 tab

  14. 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.

  15. Review of laser hybrid welding

    DEFF Research Database (Denmark)

    Bagger, Claus

    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....

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-01-15

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

  17. 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.

  18. Friction welding of Zr - 2.5 % Nb alloy tubes

    International Nuclear Information System (INIS)

    Investigation results of friction welding for Zr - 2.5 % Nb alloy tubes (dimension 88 x 4 mm) are given. These tubes are manufactured through thermomechanical processing. Optimal welding conditions are defined. Thermal processes at tubes welding are calculated

  19. Sensor integration for robotic laser welding processes

    OpenAIRE

    Iakovou, Dimitrios; Aarts, Ronald; Meijer, Johan

    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, a separate sensory system is required. The use of separate sensory systems leads to heavy and bulky tools, in contrast to compact and light sensory systems that are needed to reach sufficient accu...

  20. A study on the influence of ultrasonic processing on microstructure during laser welding phases

    Science.gov (United States)

    Liu, H. D.; Hu, F. Y.; Cui, A. Y.; Li, H. B.

    2015-12-01

    This paper proposes new welding technology that combines ultrasonic processing across different phases based on laser welding (UPPLW) and laser processing technology. The welding experiment used a 1.5 mm thick titanium alloy. The specimen was made metallographically prepared and the microstructural grain size of the welded joint was rated by metallurgical processing software, verifying that this new process can refine grains and improve joint properties.

  1. Study on laser beam welding technology for nuclear power plants title

    International Nuclear Information System (INIS)

    Laser beam welding is one of the jointing processes by irradiating laser beam on the material surface locally and widely used at various industrial fields. Toshiba has developed various laser-based maintenance and repair technologies and already applied them to several existing nuclear power plants. Laser cladding is a technique to weld the corrosion resistant metal onto a substrate surface by feeding filler wire to improve the corrosion resistance. Temper-bead welding is the heat input process to provide the desired microstructure properties of welded low alloy steels without post weld heat treatment, by inducing proper heat cycle during laser welding. Both laser welding technologies would be performed underwater by blowing the shielding gas for creating the local dry area. In this report, some evaluation results of material characteristics by temper-bead welding to target at Reactor Coolant System nozzle of PWR are presented. (author)

  2. Porosity reduction in Nd-YAG laser welding of stainless steel and inconel alloy by using a pulsed wave

    International Nuclear Information System (INIS)

    This study investigates the influence of the Nd-YAG laser power wave mode on the porosity and mechanical properties of SUS 304L and inconel 690 weldments. Initially, a rectangular laser power waveform is specified. The output is then progressively changed from a pulsed wave mode to a continuous wave mode by reducing the value of ΔP (ΔP = Pp-Pb, where Pp is the peak power and Pb is the base power) to zero. Bead-on-plate (BOP) and butt welding are performed at a constant mean output power (1.7 kW). The BOP results demonstrate that the depth/width (D/W) ratio of both materials increases with ΔP and attains a maximum value when full penetration just occurs. The D/W ratio and the travel speed for full penetration are higher for SUS 304L than for inconel 690. In butt-welds of inconel 690 and SUS 304L, the porosity ratio decreases from 7.1% to 0.5% and from 2.1% to 0.5%, respectively, as ΔP increases from 0 to 2780 W. Therefore, the tensile strength and percentage elongation are enhanced significantly in inconel 690. The degree of porosity reduction in inconel 690 exceeds that of SUS 304L. This suggests that the viscosity of the molten inconel 690 metal is higher than that of SUS 304L. Consequently, the effect of porosity reduction due to the increase in molten metal fluidity caused by increasing ΔP is greater for inconel 690 than for SUS 304L

  3. 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.

  4. Al-Mg系铝合金脉冲激光焊接性能影响因素分析%Affecting factors of pulse laser welding property of Al-Mg series aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    张继祥; 刘凤芝; 高波; 殷筱依; 杨泮

    2015-01-01

    In order to study effect of aluminum surface state and welding processing on the properties of welding joints , the process of laser welding Al-Mg series aluminum alloy with Nd∶YAG laser was analyzed in theory and verified in experiments .The experimental results of the characteristics of welding joints were obtained .The results show that welding process of untreated sample and alkali corrosion surface treatment sample are not stable while welding process of anodizing treatment sample is stable and hole effect is formed stably .Weld seam penetration and depth-to-width ratio are all improved effectively by the aid of anodizing, double welding and powder filling welding .The tensile strength of the weld seam of anodizing sample , double-sided welding sample and powder filling welding sample increases more than 1 times and powder filling welding sample of Al-0.05Si has the highest tensile strength .Hardness of all surface treatment samples is improved and the effect of phosphoric acid anodizing is the best.Hardness of weld seam and fusion zone is improved through double welding .Central hardness of powder filling weld is lower while hardness of fusion zone increases obviously .Hardness of heat affected zone of double welding and powder filling welding is lower than hardness of single side welding .The results show that anodic oxidation surface treatment and double-sided welding technology can improve the property of laser welding of Al-Mg series aluminum alloy effectively .%为了研究铝合金表面状态和焊接工艺方法对焊接接头性能的影响,采用Nd∶YAG脉冲激光器对Al-Mg系铝合金激光焊接方法进行了理论分析和实验验证,得到了焊接接头性能实验结果。结果表明,原始表面和碱蚀表面处理的试样焊接过程不稳定,阳极氧化试样焊接中形成了稳定的小孔效应,焊接过程较稳定;阳极氧化、两面焊、填粉焊都能有效提高焊缝熔深和深宽比

  5. 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.

  6. MIG (metal inert gas) and laser beam welding of aluminium die castings with wrought aluminium profiles; Soudage MIG et soudage laser de pieces moulees sous pression avec des profils corroyes en alliages d'aluminium

    Energy Technology Data Exchange (ETDEWEB)

    Wiesner, S.; Rethmeier, M.; Wohlfart, H. [Universite Technique de Brunswick, Institut de Soudure (Germany)

    2003-10-01

    The applicability of different welding techniques to the welding of aluminium die castings, particularly used in automobile engineering, is discussed and experimental results from welding trials of some of these processes are reported. The advantages and disadvantages of using pressure welding, beam welding and gas shielded arc welding techniques to weld aluminium die castings are discussed. Results from welding trials carried out on a number of ductile AlSi and AlMg alloys using MIG and laser welding techniques are reported. Laser-TIG welding was also investigated as an alternative to laser welding with its inherent problems. (authors)

  7. Friction stir welding of 6061 aluminium alloy

    International Nuclear Information System (INIS)

    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

  8. End plug welding of PFBR fuel tubes with a 2.5 kW CW CO2 laser

    International Nuclear Information System (INIS)

    The end plug weld of the fuel tube of 500 MWe Prototype Fast Breeder Reactor (PFBR) involves dissimilar welding of alloy D9 (a 15Cr-15Ni-2Mo stainless steel) fuel clad tube with end plug made of AISI 316 M stainless steel. Being a non-contact process, laser welding does not generate active wastes in the form of used electrodes and defects like tungsten inclusions are completely eliminated. Completely austenitic mode of solidification associated with alloy D9 (due to its low Creq/Nieq ratio ≅ 1) makes this alloy particularly susceptible to solidification cracking. The present paper presents correlation of the microstructure of laser welds with welding parameters. The study demonstrated that sound end welds of PFBR fuel tube with crack resistant microstructure can be obtained by optimizing laser welding parameters, proper positioning of focused laser beam and ramping of laser power during welding. (author)

  9. 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...

  10. Laser welding of plastics: theory and experiments

    Science.gov (United States)

    Atanasov, Peter A.

    1995-10-01

    The process of laser welding of plastics is studied theoretically and experimentally. Welding of cylindrical parts made from polycarbonate and polypropylene is presented as examples. A good correspondence between theoretical and experimental results is found. Some practical aspects of laser welding of plastics are given.

  11. 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.

  12. Transmission laser welding of plastics

    Science.gov (United States)

    Hilton, Paul A.; Jones, I. A.; Kennish, Y.

    2003-03-01

    The use of lasers for welding plastics was demonstrated in the early 1970s. However, it was not until late in the 1990s that production applications started to be considered widely. This followed the broad realization that by selection of a suitable combination of radiation wavelength and plastics additives, to control light transmission and absorption, heat could be generated at the joint of a pre-assembled part without melting its outer surfaces. It is of added benefit that the window of transmission for an unpigmented and unfilled plastic typically covers the wavelengths delivered by small and cost effective diode lasers. Recent developments in the transmission laser welding process for plastics are discussed, including methods for the generation of welds between two clear plastics, application of similar techniques to the joining of thermoplastic textiles and new equipment, able to heat a complete joint and assist in the sealing of assemblies where the joint surfaces are not particuarly smooth. An analytical heat flow model for the welding of clear plastics is shown in use for selecting process parameters.

  13. Development of technique for laser welding of biological tissues using laser welding device and nanocomposite solder.

    Science.gov (United States)

    Gerasimenko, A; Ichcitidze, L; Podgaetsky, V; Ryabkin, D; Pyankov, E; Saveliev, M; Selishchev, S

    2015-08-01

    The laser device for welding of biological tissues has been developed involving quality control and temperature stabilization of weld seam. Laser nanocomposite solder applied onto a wound to be weld has been used. Physicochemical properties of the nanocomposite solder have been elucidated. The nature of the tissue-organizing nanoscaffold has been analyzed at the site of biotissue welding. PMID:26738200

  14. Laser welding of advanced high strength steels

    OpenAIRE

    Ahmed, Essam Ahmed Ali

    2011-01-01

    This research work focuses on characterization of CO2 laser beam welding (LBW) of dual phase (DP) and transformation induced plasticity (TRIP) steel sheets based on experimental, numerical simulation and statistical modeling approaches. The experimental work aimed to investigate the welding induced-microstructures, hardness, tensile properties and formability limit of laser welding butt joints of DP/DP, TRIP/TRIP and DP/TRIP steel sheets under different welding speeds. The effects of shieldin...

  15. YAG laser welding with surface activating flux

    Institute of Scientific and Technical Information of China (English)

    樊丁; 张瑞华; 田中学; 中田一博; 牛尾诚夫

    2003-01-01

    YAG laser welding with surface activating flux has been investigated, and the influencing factors and mechanism are discussed. The results show that both surface activating flux and surface active element S have fantastic effects on the YAG laser weld shape, that is to obviously increase the weld penetration and D/W ratio in various welding conditions. The mechanism is thought to be the change of weld pool surface tension temperature coefficient, thus, the change of fluid flow pattern in weld pool due to the flux.

  16. Development of porosity prevention procedures during laser welding

    Science.gov (United States)

    Katayama, Seiji; Mizutani, Masami; Matsunawa, Akira

    2003-03-01

    High power CO2, YAG and LD-pumped solid-state lasers have been developed to produce a deep penetration type of high-quality, high-performance and high-speed weld joints. However, porosity is easily formed in such deep keyhole-type weld beads. The authors have developed microfocused X-ray transmission imaging system, and revealed keyhole behavior and porosity formation mechanism in high power laser welding. This paper will describe a summary of porosity formation mechanism and prevention procedures during cw laser welding of aluminum alloys. Especially, many bubbles were formed by the evaporation of the metals from the bottom tip of the keyhole and flowed upwards according to the liquid flow near the solid-liquid interface inside the molten pool. The majority of them were trapped and captured at the solidifying front of the weld beads, leading to the formation of porosity. Moreover, it was revealed that the shielding gas was chiefly included in the porosity. Main melt flows were observed as a function of welding speed. As the speed was increased, vapor plume was ejected from the keyhole inlet more and more normal to the plate surface, and consequently induced the upward flow of the keyhole-surrounding liquid. On the basis of the above knowledge, full penetration welding, properly pulse-modulated laser welding, vacuum or low pressure welding, welding using the tornado nozzle, very low or high speed welding, and so on were investigated, and it was consequently confirmed that these procedures were beneficial to the reduction in porosity.

  17. Adaptive Control for Partial- and Full-Penetration Spot Welding of Aluminum Alloy Sheets

    Science.gov (United States)

    Kawahito, Yousuke; Katayama, Seiji

    A new procedure of in-process monitoring and adaptive control for stable formation of laser spot lap welds has been developed with the objectives of producing sound partial- and full-penetration welds without through-holes and swell in A3003 aluminum alloy sheets, respectively. In the case of the formation of partial-penetration welds, the reflected laser beam and the radiated heat from the welding area were effectively utilized as in-process monitoring signals in detecting melting and though-hole formation in the upper sheet during laser irradiation. Laser pulse duration and peak power were controlled at every 0.15 ms interval during spot welding on the basis of the heat radiation signal detecting the though-hole. In the full-penetration welds, spot welding was performed at low laser power density to reduce the swell of joint part. Then the concavity level of a weld fusion zone increased remarkably with an increase in the pulse duration. Therefore, the laser pulse duration was controlled at 0.15 ms intervals on the basis of the total intensity of heat radiation so as to produce a satisfactory spot weld fusion zone. As a result, fully penetrated welds of desirable sizes with the reduced swells were consistently produced in all 20 samples. These results proved the effectiveness of in-process monitoring and the availability of adaptive control.

  18. Evolution of a Laser Hybrid Welding Map

    Science.gov (United States)

    Kaplan, Alexander F. H.; Frostevarg, Jan; Ilar, Torbjörn; Bang, Hee-Seon; Bang, Han-Sur

    Laser arc hybrid welding combines the advantages but also the complex physical mechanisms of gas metal arc welding and laser keyhole welding. From manifold mainly experimental but also theoretical research results a map with versatile functions was initiated for the first time. The purpose is to survey the overall context and to facilitate navigation to the various phenomena that are shown through case studies accompanied by theoretical explanations and guidelines for optimization. Though not complete, the map enables systematic and graphical navigation to relevant publications. Based on a fundamental structure of the map, which was decided early, it is inherently extendable in the future by adding existing and new knowledge, also from other research groups, enabling evolution. The fundament of the map structure comprises gouge thickness, joint type and metal grade, in coherence with product and weld designers' starting points. The next hierarchy level of the map offers options in the joint type as well as in hybrid welding techniques. The latter contains techniques like double-sided welding, pulse shaping management of the arc or laser, CMT arcs, tandem arcs, or remelting of undercuts. In addition to laser-arc hybrid welding, other hybrid laser techniques like multilayer hot-wire laser welding of narrow gaps or hybrid laser friction stir welding can be taken into account. At the other end of the hierarchy, the map offers via a database-like archive electronic navigation to research results like weld macrographs, high speed imaging or numerical simulation results of the welding process.

  19. Macrostructural and microstructural features of 1 000 MPa grade TRIP steel joint by CO2 laser welding

    Institute of Scientific and Technical Information of China (English)

    Wang Wenquan; Sun Daqian; Kang Chungyun

    2008-01-01

    Bead-on-plate CO2 laser welding of 1 000 MPa grade transformation induced plasticity (TRIP) steel was conducted under different welding powers, welding speeds and shield gases. The macrostructural and microstructural features of the welded joint were investigated. The increase of welding speed reduced the width of the weld bead and the porosities in the weld bead resulting from the different flow mode of melted metal in weld pool. The decrease of welding power or use of shield gas of helium also contributed to the reduction of porosity in the weld bead due to the alleviation of induced plasma formation, thus stabilizing the keyhole. The porosity formation intimately correlated with the evaporation of alloy element Mn in the base metal. The laser welded metal had same martensite microstructure as that of water-quenched base metal. The welding parameters which increased cooling rate all led to fine microstructures of the weld bead.

  20. Corrosion Control of Friction Stir Welded AA2024-T351 Aluminium Alloys

    OpenAIRE

    Younes, Yousif Younes Abo

    2010-01-01

    Friction stir welding (FSW) is a modern solid state welding technique developed at thewelding institute (TWI) in 1991. The joining is achieved by heat generation, materialsoftening and plastic deformation following the travelling of non-consumable pin throughthe gap between the two workpieces to be joined.In present study, joining of AA 2024-T3 aluminium alloy, is achieved by FSW. Theinfluence of the FSW on the alloy microstructure and corrosion behaviour is determined.The effect of laser sur...

  1. 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....

  2. Linear Anomaly in Welded 2219-T87 Aluminum Alloy

    Science.gov (United States)

    Jemian, Wartan A.

    1987-01-01

    Study of causes and significance of two types of linear anomalies sometimes appearing in radiographs of welds described in preliminary report. Manifested as light or dark linear features parallel to weld line in radiograph of weld. Contains diagrams and descriptions of phenomena occurring during welding process. Includes microdensitometer traces from x-radiographs of actual welds and from computer simulations based calculation of x-ray transmission through assumed weld structures. Concludes anomalies not unique to 2219-T87 aluminum alloy.

  3. Laser processing of metals and alloys

    International Nuclear Information System (INIS)

    Laser, due to its high degree of coherence can produce powder density in the range of 103-1011 W/mm2. 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

  4. Microstructure evolution in Nd:YAG laser-welded (Zr53Cu30Ni9Al8)Si0.5 bulk metallic glass alloy

    International Nuclear Information System (INIS)

    To generate a rapid welding thermal cycle for a (Zr53Cu30Ni9Al8)Si0.5 bulk metallic glass (BMG) weld, the Nd:YAG pulse laser welding process with pre-selected welding variables is used in this study. The microstructure development and crystallization behavior in the weld fusion zone (WFZ) and the heat-affected zone (HAZ) are investigated by scanning electron microscopy (SEM), micro-area X-ray diffractometry (XRD) and transmission electron microscopy (TEM). From the results, it is observed that the HAZ is liable to crystallize, although no crystallization occurs within the WFZ. The spherical type crystalline phases (with a particle size of 20-200 nm) observed in the HAZ, which are rich in Zr, Cu and Ni, result in a change of chemical composition in this region. Furthermore, if the particle size in the crystallized area is greater than 50 nm, cracks may form.

  5. Techniques for laser welding polymeric devices.

    Science.gov (United States)

    Jones, I A

    2003-04-01

    Recent advances in laser techniques mean that lasers are now being considered as an alternative to vibration, ultrasonic, dielectric, hot plate or hot bar welding, and adhesive bonding of plastics. The techniques required to put laser welding methods into practice are described for medical devices, tubular systems, films and synthetic fabrics. PMID:12789697

  6. Comparison Between Keyhole Weld Model and Laser Welding Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Wood, B C; Palmer, T A; Elmer, J W

    2002-09-23

    A series of laser welds were performed using a high-power diode-pumped continuous-wave Nd:YAG laser welder. In a previous study, the experimental results of those welds were examined, and the effects that changes in incident power and various welding parameters had on weld geometry were investigated. In this report, the fusion zones of the laser welds are compared with those predicted from a laser keyhole weld simulation model for stainless steels (304L and 21-6-9), vanadium, and tantalum. The calculated keyhole depths for the vanadium and 304L stainless steel samples fit the experimental data to within acceptable error, demonstrating the predictive power of numerical simulation for welds in these two materials. Calculations for the tantalum and 21-6-9 stainless steel were a poorer match to the experimental values. Accuracy in materials properties proved extremely important in predicting weld behavior, as minor changes in certain properties had a significant effect on calculated keyhole depth. For each of the materials tested, the correlation between simulated and experimental keyhole depths deviated as the laser power was increased. Using the model as a simulation tool, we conclude that the optical absorptivity of the material is the most influential factor in determining the keyhole depth. Future work will be performed to further investigate these effects and to develop a better match between the model and the experimental results for 21-6-9 stainless steel and tantalum.

  7. Effect of sulfur on weld geometry in pulsed laser welds

    International Nuclear Information System (INIS)

    The primary goal of the present study was to determine whether compositional differences in a surface active element in austenitic stainless steel can alter the geometry of pulsed laser welds. Clearly, much less time is available during pulse laser welding for convection cells to form and influence heat transfer. A two-dimensional heat-transfer code has been developed for pulsed Nd:YAG laser welding that only incorporates heat transfer by conduction for the molten metal. For fluences that do not result in significant evaporation, this code generally yields good predictions of weld geometries, if appropriate corrections are made for surface absorptivity. At higher fluences, significant differences are found between predicted and observed weld pool shapes. This study is a portion of a larger program to determine the causes of these differences. Earlier work has produced direct experimental evidence that convection cells can develop during pulsed laser welding. However, experimental evidence that convection is present during welding is not sufficient to indicate whether convection is a dominant heat transfer mechanism. More recently, modeling of transient two-dimensional Marangoni flow in a pulsed laser weld pool was attempted

  8. Laser welding in a reduced gravity environment

    Science.gov (United States)

    Workman, Gary L.; Kaukler, William F.

    1992-01-01

    Preliminary results on the effects of reduced gravity on laser welding of stainless steel and other materials are reported. Laser welding experiments using a low power (10-18 watts) Nd-YAG laser have been performed on the NASA KC-135, which flies parabolic maneuvers to simulate reduced gravity conditions. Experiments on 0.005-0.010 inch thick stainless steel samples displayed a pronounced change in weld bead width, depth of penetration and surface ripple with changes in gravity level.

  9. Fibre laser welding of dissimilar materials

    OpenAIRE

    Chen, Hui-Chi

    2010-01-01

    Joining technology has played an important role in manufacturing since the industrial revolution. Welding methods are under constant development in response to real demands. Laser welding is considered an effective joining method that can provide high quality and cost effective results to bring economical benefits to industry. Nowadays, fibre lasers have the capability to fill some of the roles of the CO2 and Nd:YAG lasers in industrial welding applications because of their excellent characte...

  10. Laser Shock Processing of Metal Sheet and Welded Joints

    Institute of Scientific and Technical Information of China (English)

    ZOU Shi-kun; TAN Yong-sheng; ZHANG Xiao-bin; LIU Fang-jun

    2004-01-01

    In order to study the application of laser shock processing(LSP) as a post weld treatment technology and a strengthening technology, a series experiments and analysis were taken in this paper. The hardness of the laser shock processed zone of Al-Li alloy was measured, and the microstructure and mechanical properties of the welded joints of the Ni-based superalloy GH30 and the Austenitic stainless steel 1Cr18Ni9Ti were compared with those without LSP in this paper. The results showed that the size of strengthened zone was similar to that of laser spot and strengthened layer was about 1mm deep, and the high intense dislocations and twins produced in the shocked zone. Plastic strain also gained surface residual compress stress, which is benefit for the fatigue properties of welded zones. In this test, the surface hardness of welding zone of the superalloy GH30 improved obviously and tensile strength increased by 12%, but the improvement of fatigue life was not obvious; Martensite phase is formed in plasma welding 1Cr18Ni9Ti, which reduced the effect of strain deformation martensite induced by laser shock processing, but the surface residual compress stress gained by laser shock processing can obviously improve the fatigue life of 1Cr1 8Ni9Ti welded joints.

  11. Laser Shock Processing of Metal Sheet and Welded Joints

    Institute of Scientific and Technical Information of China (English)

    ZOUShi-kun; TANYong-sheng; ZHANGXiao-bin; LIUFang-jun

    2004-01-01

    In order to study the application of laser shock processing(LSP) as a post weld treatment technology and a strengthening technology, a series experiments and analysis were taken in this paper. The hardness of the laser shock processed zone of A1-Li alloy was measured, and the microstructure and mechanical properties of the welded joints of the Ni-based superalloy GH30 and the Austenitic stainless steel 1Crl8Ni9Ti were compared with those without LSP in this paper. The results showed that the size of strengthened zone was similar to that of laser spot and strengthened layer was about lmm deep, and the high intense dislocations and twins produced in the shocked zone. Plastic strain also gained surface residual compress stress, which is benefit for the fatigue properties of welded zones. In this test, the surface hardness of welding zone of the superalloy GH30 improved obviously and tensile strength increased by 12%, but the improvement of fatigue life was not obvious; Martensite phase is formed in plasma welding 1Crl8Ni9Ti, which reduced the effect of strain deformation martensite induced by laser shock processing, but the surface residual compress stress gained by laser shock processing can obviously improve the fatigue life of 1Crl 8Ni9Ti welded joints.

  12. Study on DC welding parameters of Al-alloy shaping based on arc-welding robot

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The Al-alloy arc-welding shaping system based on arc-welding robot is established, and the Al-alloy shaping manufacture is realized with the DC (direct current) gas metal arc welding (GMAW). The research indicates that the metal transfer type of DC GMAW, heat input and the initial temperature of the workpiece greatly affect the Al-alloy shaping based on arc welding robot. On the penetration, the weld width and the reinforcement, the influence of welding parameters is analyzed by generalized regression neural network (GRNN) fitting.

  13. Optimization of Fiber Laser Welding of DP980 Steels Using RSM to Improve Weld Properties for Formability

    Science.gov (United States)

    Bandyopadhyay, K.; Panda, S. K.; Saha, P.

    2016-06-01

    The effect of laser parameters on weld quality is a critical laboratory study before implementation of newly developed high-strength dual-phase steels in fabrication of auto-bodies. In present work, dual-phase steels having tensile strength of 980 MPa (DP980) were welded using different welding speeds by Yb-fiber laser source to fabricate similar material combinations laser-welded blanks (LWBs). The weld zone microhardness, microstructure, and formability of DP980 LWBs were compared with those of the DP600 and micro-alloyed interstitial free high-strength steel (IFHS) LWBs. It was found that the formation of soft zone at the outer side of the HAZ was responsible for significant reduction in formability of DP980 LWBs due to strain localization and premature failure. Hence, response surface methodology based on Box-Behnken design was implemented to establish a mathematical model which could correlate the influence of laser process parameters such as power, welding speed, and focal position on weld quality in terms of aspect ratio of fusion zone, width of the soft zone, and surface roughness of weld to improve formability. The model was successfully implemented to optimize the laser parameters, and approximately 13.58% improvement in Erichsen cup height was achieved due to complete weld penetration with simultaneous 67% reduction in soft zone width and 55% reduction in softening. However, the failure was still observed to occur in the soft zone propagating parallel to weld in radial direction.

  14. 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)

    Research highlights: → AZ31 LBW fusion zone results in Mg17(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.

  15. 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...

  16. Welding of transparent polymers using femtosecond laser

    Science.gov (United States)

    Roth, Gian-Luca; Rung, Stefan; Hellmann, Ralf

    2016-02-01

    Based on nonlinear absorption, we report on laser welding of cycloolefin copolymers without any additional absorption layer employing infrared femtosecond laser. To the best of our knowledge, this is the first report of ultrashort laser welding of this material class, revealing a remarkable high processing speed of 20 mm/s in a single pass mode. Using a 1028 nm laser having a pulse duration of 220 fs at a repetition rate of 571 kHz leads to a welding seam width between 38 and 137 μm, depending on the applied laser average power. The welded joint is characterized by a maximum shear strength of 40 MPa. The experimental results are compared to those reported for femtosecond laser welding of PMMA and to those published for using a Thulium fiber laser.

  17. Single-sided laser beam welding of a dissimilar AA2024–AA7050 T-joint

    International Nuclear Information System (INIS)

    Highlights: • Single-sided laser beam welding of a dissimilar AA2024–AA7050 T-joint was realised. • For this purpose a fibre laser with high power and a large beam diameter was used. • Porosity-free weld seams with low penetration into the skin material were achieved. • The mechanical properties are comparable to that of double-sided welded T-joints. - Abstract: In the aircraft industry double-sided laser beam welding of skin–stringer joints is an approved method for producing defect-free welds. But due to limited accessibility – as for the welding of skin–clip joints – the applicability of this method is limited. Therefore single-sided laser beam welding of T-joints becomes necessary. This also implies a reduction of the manufacturing effort. However, the main obstacle for the use of single-sided welding of T-joints is the occurrence of weld defects. An additional complexity represents the combination of dissimilar and hard-to-weld aluminium alloys – like Al–Cu and Al–Zn alloys. These alloys offer a high strength-to-density ratio, but are also associated with distinct weldability problems especially for fusion welding techniques like laser beam welding. The present study demonstrates how to overcome the weldability problems during single-sided laser beam welding of a dissimilar T-joint made of AA2024 and AA7050. For this purpose a high-power fibre laser with a large beam diameter is used. Important welding parameters are identified and adjusted for achieving defect-free welds. The obtained joints are compared to double-sided welded joints made of typical aircraft aluminium alloys. In this regard single-sided welded joints showed the expected differing weld seam appearance, but comparable mechanical properties

  18. Laser welding of micro plastic parts

    Science.gov (United States)

    Haberstroh, E.; Hoffmann, W.-M.

    2007-02-01

    Most welding processes for plastics do not meet the demands of micro technology and thus cannot be applied in this innovative industrial sector. One of the few techniques which are applicable in this sector is the laser transmission welding, which has distinctive advantages like low mechanical and thermal load of the joining parts. This makes the laser particularly suitable for the welding of micro plastics parts. Thereby, contour welding is a process variant of laser transmission welding enabling the welding of complex and even three-dimensional weld contours. But so far it has not yet been applied for welding plastics parts of micro scale in the industrial practice. Recent research at the Institute of Plastics Processing (IKV) at the RWTH Aachen University shows the feasibility of this process to weld small and complex micro parts. Good mechanical properties can be achieved. However, it is necessary to apply measures to reduce the formation of flash. Moreover, it can be shown that there is a strong influence of some material parameters on the laser welding process so that some plastics are more suitable than others for the contour welding in micro technology.

  19. 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. PMID:25595723

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

    International Nuclear Information System (INIS)

    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

  1. Mechanism of laser beam welding for SiCP/6063Al composite

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The laser beam welding technique was used to process SiC particles /6063Al alloy matrix composite, the influence of laser power and welding speed on the properties of joint was studied. Decreasing the laser beam power with same welding speed can make the quantity and size of Al4C3 decreased, and the interactive mechanism of the reinforcing particles and the matrix in the joint and the causes for joint strength reduction were analyzed.Increasing welding speed properly can improve the distribution of energy and restrain the interfacial reaction in the molten pool, and measures for improving were proposed.

  2. Induction heat treatment of laser welds

    DEFF Research Database (Denmark)

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

    2003-01-01

    the laser beam as close as possible. After welding, the samples were quality assessed according to ISO 13.919-1 and tested for hardness. The metallurgical phases are analysed and briefly described. A comparison between purely laser welded samples and induction heat-treated laser welded samples is made....... The temperature measurements show that, with the chosen mechanical set-up of laser and induction coil, it is difficult to obtain a quick increase to around 300º C, the temperatures required for efficient heat-treatment with the induction coil alone. Despite this, a reduction in the hardness values of...... both GA260 and CMn were recorded when laser welded samples were induction heat-treated. The reduction was 6 to 8 % for GA260 and 41 to 45 % for CMn, respectively. GA260 displays a ferrite structure in basic and welded form, whereas CMn, with ten times more carbon, shows a ferrite and bainite structure...

  3. A study of the mechanism of laser welding defects in low thermal expansion superalloy GH909

    International Nuclear Information System (INIS)

    In this paper, we describe experimental laser welding of low-thermal-expansion superalloy GH909. The main welding defects of GH909 by laser in the weld are liquation cracks and porosities, including hydrogen and carbon monoxide porosity. The forming mechanism of laser welding defects was investigated. This investigation was conducted using an optical microscope, scanning electron microscope, energy diffraction spectrum, X-ray diffractometer and other methodologies. The results demonstrated that porosities appearing in the central weld were related to incomplete removal of oxide film on the surface of the welding samples. The porosities produced by these bubbles were formed as a result of residual hydrogen or oxygenium in the weld. These elements failed to escape from the weld since laser welding has both a rapid welding speed and cooling rate. The emerging crack in the heat affected zone is a liquation crack and extends along the grain boundary as a result of composition segregation. Laves–Ni2Ti phase with low melting point is a harmful phase, and the stress causes grain boundaries to liquefy, migrate and even crack. Removing the oxides on the surface of the samples before welding and carefully controlling technological parameters can reduce welding defects and improve formation of the GH909 alloy weld. - Highlights: ► It is a new process for the forming of GH909 alloy via laser welding. ► The forming mechanism of laser welding defects in GH909 has been studied. ► It may be a means to improve the efficiency of aircraft engine production

  4. Influence of the Overlapping Factor and Welding Speed on T-Joint Welding of Ti6Al4V and Inconel 600 Using Low-Power Fiber Laser

    OpenAIRE

    Shamini Janasekaran; Ai Wen Tan; Farazila Yusof; Mohd Hamdi Abdul Shukor

    2016-01-01

    Double-sided laser beam welding of skin-stringer joints is an established method for many applications. However, in certain cases with limited accessibility, single-sided laser beam joining is considered. In the present study, single-sided welding of titanium alloy Ti6Al4V and nickel-based alloy Inconel 600 in a T-joint configuration was carried out using continuous-wave (CW), low-power Ytterbium (Yb)-fiber laser. The influence of the overlapping factor and welding speed of the laser beam on ...

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

    Science.gov (United States)

    Looney, Alan

    1991-01-01

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

  6. A Parametric Analysis of CO2 Laser Heat Absorption Profile of 5083 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    JOSEPH .I. ACHEBO

    2010-06-01

    Full Text Available Aluminum alloys are amongst the most difficult everyday metals that can be welded using the laser welding process. For this reason, high power density lasers are needed to weld these alloys because they require higher thermal diffusivity to form a key hole than would be needed for other metals such as steel. This means that more heat wouldhave to be applied while welding aluminum alloys than would be needed to weld steel to achieve a satisfactory coupling effect. The heat input generated from laser welding is affected by the absorptivity coefficient, the welding speed and the time spent. Once the optimum heat input is attained, it is expected to create less heat distortion, its energy is more concentrated within the weld area and deep weld penetration is achieved. Determining optimum values of welding parameters would lead to acceptable weld quality. In this study, the heat absorption profile of a CO2 laser welding of 5083 aluminum alloy was investigated using the models proposed by Bramson in 1968 and Okon et al in 2002. The 4mm thick aluminum alloy investigated was as received from the vendors. The calculated laser beam absorptivity coefficient, irradiance and boiling temperature were 0.12, 2.3 x 106 Wcm-2 and 2482oC respectively. These calculated values compared well with reported values in other literature.

  7. Laser welding of Ti40Zr25Ni3Cu12Be20 bulk metallic glass

    International Nuclear Information System (INIS)

    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).

  8. Shedding Light on Laser Welding [poster

    OpenAIRE

    Aalderink, B.J.; Aarts, R.G.K.M.; Jonker, J.B.; Meijer, J.

    2005-01-01

    Nd:YAG laser welding is often used in industry to obtain high quality joints. This however does not mean that monitoring or control of this process is common practice. A few commercial products are available but none of these systems can be used for monitoring the laser welding process of aluminium. Within the NIMR project Multivariable melt pool control for double spot laser welding a monitoring system is developed based on a CMOS camera which is suited for the observation of Nd:YAG laser we...

  9. Recent progress on gas tungsten arc welding of vanadium alloys

    International Nuclear Information System (INIS)

    This is a progress report on a continuing research project to acquire a fundamental understanding of the metallurgical processes in the welding of vanadium alloys. It also has the goal of developing techniques for welding structural vanadium alloys. The alloy V-4Cr-4Ti is used as a representative alloy of the group; it is also the prime candidate vanadium alloy for the U.S. Fusion Program at the present time. However, other alloys of this class were used in the research as necessary. The present work focuses on recent findings of hydrogen embrittlement found in vanadium alloy welds. It was concluded that the atmosphere in the inert gas glove box was insufficient for welding 6mm thick vanadium alloy plates

  10. Study on Laser Welding of Al Composite

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effects of laser welding parameter on strength of welded joints were studied. The mechanism for loss of joint strength was analyzed. It was pointed out that an important factor affecting joint strength is the reaction between matrix and reinforced phase. On the basis of this, the concept of critical Si activity α[si]min was proposed. Using appropriate welding parameters and Si activity, high quality laser welded joints in an aluminum matrix composite SiCw/6061A1 can be successfully obtained.

  11. Laser tissue welding: a urological surgeon's perspective.

    Science.gov (United States)

    Poppas, D P; Scherr, D S

    1998-07-01

    Laser tissue welding has proven its efficacy in the laboratory setting when compared with more traditional modalities of tissue reapproximation. In the clinical environment, several areas including urethral reconstructive surgery have shown great promise. Several technological advancements including solder development, chromophore enhancement and temperature control have improved upon the welding process and have added more precision and reproducibility to the technique. The current potential applications for laser welding in urology are numerous. On a molecular level, growth factor supplementation has certain potential in improving upon weld site healing and wound strength. Laparoscopic surgery with its need for less cumbersome modes of tissue closure is a field that will greatly benefit from the technology of laser tissue welding. Surgical specialties outside of urology are also participating in developing the field of laser welding. In particular, cardiothoracic surgery, otolaryngology, plastic surgery, neurosurgery among others, have utilized the concept of laser tissue welding. There are many ares that have potential use for laser welding that have yet to be explored. Further investigation will likely reveal more applications for this valuable technology. PMID:9873775

  12. In-situ weld-alloying plasma arc welding of SiCp/Al MMC

    Institute of Scientific and Technical Information of China (English)

    LEI Yu-cheng; YUAN Wei-jin; CHEN Xi-zhang; ZHU Fei; CHENG Xiao-nong

    2007-01-01

    Plasma arc welding was used to join SiCp/Al composite with titanium as alloying filler material. Microstructure of the weld was characterized by an optical microscope. The results show that the harmful needle-like phase Al4C3 is completely eliminated in the weld of SiCp/Al metal matrix composite(MMC) by in-situ weld-alloying/plasma arc welding with titanium as the alloying element. The wetting property between reinforced phase and Al matrix is improved, a stable weld puddle is gotten and a novel composite-material welded joint reinforced by TiN, AlN and TiC is produced. And the tensile-strength and malleability of the welded joints are improved effectively because of the use of titanium.

  13. Experimental investigation of laser beam welding of explosion-welded steel/aluminum structural transition joints

    International Nuclear Information System (INIS)

    The steel/aluminum structural transition joints are widely used in shipbuilding industry due to the advantages of joining these two materials with important weight savings while exploiting their best properties. The use of laser welding to strongly connect components made of Fe and Al alloys as base materials with Fe/Al structural transition joints is very attractive. The authors report results achieved during the laser welding of these particular joints with the scope to evaluate effects of the laser-induced thermal loads on the integrity of the Fe/Al bond interface, from metallurgical and mechanical points of view. The increase of both inter-metallic film thickness and extension were detected as a result of the laser beam induced heat on the Fe/Al bond interface. These increases did not cause severe reductions of the mechanical resistance of the investigated structural transition joint.

  14. Polyethylene welding by pulsed visible laser irradiation

    International Nuclear Information System (INIS)

    Laser welding of plastics is a relatively new process that induces locally a fast polymer heating. For most applications, the process involves directing a pulsed beam of visible light at the weld joint by going through one of the two parts. This is commonly referred to as 'through transmission visible laser welding'. In this technique, the monochromatic visible light source uses a power ns pulsed laser in order to irradiate the joint through one part and the light is absorbed in the vicinity of the other part. In order to evaluate the mechanical resistance of the welded joint, mass quadrupole spectrometry, surface profilometry, microscopy techniques and mechanical shear tests were employed. The welding effect was investigated as a function of the laser irradiation time, nature of the polyethylene materials and temperature.

  15. 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.

  16. An initial study on welding procedure using tandem MIG welding of high strength aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    林三宝; 刚铁; 杨春利; 崔洪波

    2004-01-01

    The high-speed camera system and data acquisition system of welding parameters were created in tandem MIG welding of high strength aluminum alloy. The experiments were carried out in order to obtain the photos of droplet transfer under different welding parameters in pulsed mode. The droplet transfer mode of "one pulse one droplet" becomes the preferred selection during welding process because of its stable procedure and sound weld form. The parameter ranges for corresponding transfer mode were experimentally achieved, among which the stable droplet transfer mode of "one pulse one droplet" can be realized. These efforts brave the way for control weld heat input and weld formation in the future.

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

    Science.gov (United States)

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

    1993-01-01

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

  18. Sensor-guided robotic laser welding

    OpenAIRE

    Graaf, de, Joost

    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 beamcan be fulfilled using seam-tracking sensors. This thesis describes how such sensors can be integrated in a robotic laser welding system for automatic teaching of the seam trajectory, but also to co...

  19. Variable-Polarity Plasma Arc Welding Of Alloy 2219

    Science.gov (United States)

    Walsh, Daniel W.; Nunes, Arthur C., Jr.

    1989-01-01

    Report presents results of study of variable-polarity plasma arc (VPPA) welding of aluminum alloy 2219. Consists of two parts: Examination of effects of microsegregation and transient weld stress on macrosegregation in weld pool and, electrical characterization of straight- and reverse-polarity portions of arc cycle.

  20. Embrittlement of welds produced by pulsed laser welding

    International Nuclear Information System (INIS)

    Welding through radiation of Nd:Yag laser is characterized by hard thermal deformation cycle under action of which the microstructure changes are obtained. These changes exert considerable influence on the mechanical properties. Experimentally investigated the influence of multipulse action on the butt weld strength at static tension. It was found that by increasing multiplicity equalled to increasing of overlapping factor the destroying stresses are decreased up to some

  1. 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. PMID:25322246

  2. Tensile strength and elongation of laser-welded Ti and Ti-6AL-7NB.

    Science.gov (United States)

    Watanabe, Ikuya; Topham, D Scott

    2004-10-15

    This study established data demonstrating the possible laser-welded strengths of cast Ti and Ti-6Al-7Nb and compared them to those of two dental-casting alloys. Cast plates of Ti, Ti-6Al-7Nb, gold, and Co-Cr alloy were prepared. After polishing the surfaces to be welded, two plates were abutted and welded using an Nd:YAG laser at a pulse duration of 10 ms, spot diameter of 1 mm, and voltage of 200 V. Five specimens were prepared for each metal by welding either three or five spots unilaterally or bilaterally. The fracture load and percent elongation were measured at a crosshead speed of 1.0 mm/min. The bilaterally welded specimens performed significantly greater than unilaterally welded specimens in both fracture load and elongation whether they were welded with three or five spots per side. The bilaterally welded Ti and Ti-6Al-7Nb specimens were nearly as strong as their corresponding control specimens, whereas the gold and Co-Cr specimens were approximately half as strong. When a large proportion of the cross-sectional area of the joint is laser welded, the strength of the laser-welded portion of the cast Ti and Ti-6Al-7Nb may approach or equal that of the nonwelded metal frameworks. PMID:15368227

  3. Laser strobe weld pool vision for robotic arc welding

    International Nuclear Information System (INIS)

    This paper describes continuing work in arc light suppression in the viewing of weld pool via a stroboscopic video system. In addition to refining the basic technique, the system has been extended in ways that will enhance its applicability to robotics and the adaptive control of welding processes, as well as provide a general diagnostic tool for welding production and research. In summary, the stroboscopic video technique uses a night vision image intensifier tube to gate video image with the illumination of the weld pool area supplied by a very strong repetitively pulsed light source such as a xenon flash lamp or a laser. Although the average optical power of illuminator is much lower than that of the arc, the peak power is much greater and the gated image almost completely suppresses the light of the arc. The image is then focused into a CCD camera whose video output is conventional and can be viewed in real time, analyzed line-by-line, or recorded on a standard video cassette recorder. The present work has branched in several directions. Two laser illumination sources have been developed. One is a pulsed ultraviolet laser with substantially more peak power than the xenon lamp, used for illuminating the rather difficult video environment found in the high-current GMA welding of aluminum plate. This laser has been mated with an optical fiber which delivers its light to the welding torch, a technique amenable to robotic applications. The other laser illumination source is based on infrared laser diodes; while much less powerful than other pulsed lasers, they are cheap, compact, rugged, and require little auxiliary equipment to operate

  4. The Advantage of Sensor Sealing Laser Welding

    Institute of Scientific and Technical Information of China (English)

    YAN Yezhi; XU yu

    2007-01-01

    @@ Laser Welding Inevitably Applied in Sen sor Production Certain kinds of sensors such as pressure sensor,temperature sensor, optic-electronic sensor etc. utilize welding seal according to different application environment. With precision components and IC which is isolated by inert gas inside, these sensors should be sealed and able to resist the pressure. So the welding process must avoid distortion and harm to the components and IC.

  5. 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...... norms. The paper describes the results obtained, showing significant productivity improvements and good weld qualities applying laser hybrid welding....

  6. Temper-bead repair-welding of neutron-irradiated reactor (pressure) vessel by low-heat-input TIG and YAG laser welding

    International Nuclear Information System (INIS)

    Weldability in neutron-irradiated low alloy steel for reactor (pressure) vessel has been studied by temper-bead repair-welding of low-heat-input TIG and YAG laser welding. A low alloy steel and its weld, and stainless steel clad and nickel (Ni)-based alloy clad were irradiated in a materials test reactor (LVR-15, Czech Republic) up to 1.4 x 1024 n/m2 (>1 MeV) at 290degC, which approximately corresponds to the maximum neutron fluence of 60-year-operation plants' vessels. The He concentration in the irradiated specimens was estimated to be up to 12.9 appm. The repair-welding was carried out by TIG and YAG laser welding at a heat input from 0.06 to 0.86 MJ/m. The mechanical tests of tensile, impact, side bend and hardness were carried out after the repair-welding. Cracks were not observed in the irradiated low alloy steel and its weld by temper-bead repair-welding. Small porosities were formed in the first and second layers of the repair-welds of low alloy steel (base metal). However, only a few porosities were found in the repair-welds of the weld of low alloy steel. From the results of mechanical tests, the repair-welding could be done in the irradiated weld of low alloy steel containing a He concentration up to 12.9 appm, although repair-welding could be done in base metal of low alloy steel containing up to only 1.7 appmHe. On the other hand, cracks occurred in the heat affected zones of stainless steel and Ni-based alloy clads by repair-welding, except by YAG laser repair-welding at a heat input of 0.06 MJ/m in stainless steel clad containing 1.7 appmHe. Based on these results, the determination processes were proposed for optimum parameters of repair-welding of low alloy steel and clad used for reactor (pressure) vessel. (author)

  7. Numerical simulation of temperature field in deep penetration laser welding of 5A06 aluminum cylinder

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Deep penetration laser welding temperature field of 5A06 aluminum alloy canister structure was simulated using the surface-body combination heat source model by ANSYS, which was made up of Gauss surface heat source model and Gauss revolved body heat source model. Convection, radiation and conduction were all considered during the simulation process. The thermal cycle curves of the points both on the shell outer surface and in the seam thickness direction were calculated. Simulated results agreed well with the experiment results. It concluded that the surface-body combination heat source model was fit for the temperature field simulation of deep penetration laser welding of the aluminum alloy canister structure. This method was proved to be an efficient way to predict the shape and dimension of welded joint for deep penetration laser welding of the aluminum alloy canister structure.

  8. Laser welding control by monitoring of plasma

    Science.gov (United States)

    Chmelickova, Hana; Sebestova, Hana; Havelkova, Martina; Rihakova, Lenka; Nozka, Libor

    2013-04-01

    Deep penetration welding is a typical industrial application of high power lasers, where plasma can be generated above the keyhole. Thanks to the plasma plume presence welding process can be controlled on-line by means of the plasma intensity measurements. Various on-line monitoring methods have been developed in research centers all over the world. Goal of them is to enable promptly operator action to avoid enormous economical looses if un-expected defect is detected. Our laboratory was participated in project CLET - "Closed loop control of the laser welding process through the measurement of plasma" as a responsible partner for developed system testing both in the laboratory with pulsed Nd:YAG laser and in the real welding facility with high power continual CO2 laser. Control system is based on the electron temperature computation from the relative intensities of couple of emission lines belong to certain metal ion present in plasma plume. Our experiment was realized using Ocean Optics HR2000+ spectrometer within the stainless steel tube longitudinal welding. Several couples of emission lines were tested to acquire a good signal at actual welding conditions. Then power calibration was made to obtain the electron temperature dependence on increasing power. Samples were prepared for microanalysis and measured by laser confocal scanning microscope to find optimal power range for full penetrations achieving without thermal distortion of the tube or weld humping. Numerical model of the remelted area cross section was made to display temperature distribution dependence on increasing power.

  9. Development of underwater laser beam welding equipment

    International Nuclear Information System (INIS)

    Toshiba has developed various laser-based maintenance and repair technologies and already applied to nuclear power plants. Laser beam welding technology has been developed as an SCC countermeasure for aged components in PWRs and BWRs. This technology can also be used underwater by blowing shielding gas for creating a local dry area. This welding equipment has damage detecting function of optical elements such as windows and optical fiber cables, and the laser beam spot position and diameter can be adjusted. These designs have improved safety and welding quality. In this report, the outline of the underwater laser beam welding for Reactor Coolant System nozzles of PWRs are presented, especially focused on the device configurations. (author)

  10. Polyethylene welding by pulsed visible laser irradiation

    Science.gov (United States)

    Torrisi, L.; Caridi, F.; Visco, A. M.; Campo, N.

    2011-01-01

    Laser welding of plastics is a relatively new process that induces locally a fast polymer heating. For most applications, the process involves directing a pulsed beam of visible light at the weld joint by going through one of the two parts. This is commonly referred to as “through transmission visible laser welding”. In this technique, the monochromatic visible light source uses a power ns pulsed laser in order to irradiate the joint through one part and the light is absorbed in the vicinity of the other part. In order to evaluate the mechanical resistance of the welded joint, mass quadrupole spectrometry, surface profilometry, microscopy techniques and mechanical shear tests were employed. The welding effect was investigated as a function of the laser irradiation time, nature of the polyethylene materials and temperature.

  11. Study of laser welding of copper sheets

    Directory of Open Access Journals (Sweden)

    A. Klimpel

    2007-01-01

    Full Text Available 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, to establish the optimum parameters of high power diode laser autogenous welding process.Findings: It was shown that there is very narrow range of optimum HPDL autogenous welding parameters ofshort seam beads and fillet welds of lap joints of oxygen-free copper sheets 1,0 [mm] parameters. It was provedthat high power diode laser (HPDL autogenous welded lap joints provide mechanical properties on the levelof parent material.Practical implications: It is possible to produce high quality short seam bead and fillet weld lap joints ofoxygen-free copper sheets 1.0 [mm] thick. It was proved that high power diode laser (HPDL autogenous weldedlap joints provide mechanical properties on the level of parent material.Originality/value: The optimum HPDL autogenous welding parameters of short seam beads and fillet weldsof lap joints of oxygen-free copper sheets 1.0 [mm] parameters makes possible to produce high quality laserautogenous welded lap joints of copper sheets 1.0 [mm] thick.

  12. Welding nickel alloys for highly corrosive media and/or high temperature

    International Nuclear Information System (INIS)

    The paper reviews the main nickel alloys used in chemical and nuclear industry, corrosion resistance, welding problems, welding process and precautions during welding operation for corrosion resistance of welded joints. 2 figs., 3 tabl., 6 refs

  13. Beam alignment system for laser welding system

    International Nuclear Information System (INIS)

    The patent describes a beam alignment system for laser welding work pieces, such as fuel rod grids for nuclear fuel assemblies. The apparatus for performing various laser-machining comprises a beam alignment system including alignment target means, as well as means for emitting, directing and focusing the laser beam. (U.K.)

  14. Development of welding consumables for wet underwater welding of high-alloy corrosion-resistant steel

    OpenAIRE

    Kakhovskyi, Yurij; Kakhovskyi, Mykola

    2015-01-01

    This paper discusses a technology of mechanized wet underwater welding of high-alloy corrosion-resistance steel. The main aim of the investigation is development of self-shielded flux-cored wire for wet underwater welding for the first time in the world practice. A mathematical method of experiment design was used for determination of quantity and quality characteristics. Besides, quantitive and qualitative indices of welding-technological characteristics such as weld metal gas saturation, st...

  15. Laser Welding of Ultra-Fine Grained Steel SS400

    Institute of Scientific and Technical Information of China (English)

    PENG Yun; TIAN Zhi-ling; CHEN Wu-zhu; WANG Cheng; BAO Gang

    2003-01-01

    The effects of laser welding on microstructure and mechanical properties of ultra-fine grained steel SS400 were studied. The plasma arc welding and MAG welding were conducted to make a comparison between these weldings and laser welding. The coarse grain heat-affected zone (HAZ) of laser welding was simulated using thermomechanical simulation machine, and the impact toughness was tested. The deep penetration laser welding produces weld of large depth and narrow width. The weld metal and HAZ of laser welding was heated and then cooled rapidly. The prior austenite grain size of coarse grain HAZ is 1/10 of that for arc welding. For laser welding, the toughness of weld metal is higher than that of base metal, and the toughness of the coarse grain HAZ of laser welding is on a level with that of base metal. Matching lower laser power with lower welding speed, the hardening tendency of the weld metal and the coarse grain HAZ can be decreased. There is no softened zone. The tensile strength of welded joint formed by laser is higher than that of base metal. The joint has good bending ductility.

  16. Hybrid Laser-Arc Welding Tanks Steels

    Science.gov (United States)

    Turichin, G.; Tsibulskiy, I.; Kuznetsov, M.; Akhmetov, A.; Klimova-Korsmik, O.

    2016-04-01

    The results investigate hybrid laser-arc welding of high strength steels using design responsible metallic construction and the highest strength body of vehicles. Welds from modern high strength steels grade Hardox 400, Hardox 450, Armox 600T and AB were created. High power fiber laser LS-15 with output 15 kW and arc rectifier VDU - 1500 DC were used in the experiment. Results of the metallographic research and mechanical tests are presented.

  17. STUDY ON SHAPE RECOVERY TEMPERATURE OF TiNi ALLOY LASER WELD JOINT%TiNi合金激光焊接接头形状恢复温度的研究

    Institute of Scientific and Technical Information of China (English)

    杨成功; 单际国; 任家烈

    2012-01-01

    In order to control the shape memory function of TiNi alloy weld joint, it is necessary to clarify the effect of the three different parts (weld metal, heat-affected zone (HAZ) and base metal) on the shape recovery temperatures of the whole weld joint, but few reports are available on this aspect. In this work, the microstructure in the HAZ was studied by Gleeble thermal-simulation test. Phase transformation temperatures of weld joint, weld metal, HAZ and base metal were measured by differential thermal analysis. The inverse phase transformation temperature was analyzed. The microstructure, distribution of precipitation and crystal structure were investigated by using OM, SEM and XRD. The weld joint shows the similar shape recovery ratio to the base metal, but the shape recovery temperature range is significantly different. The start recovery temperature of the weld joint is lower about 40 ℃ than that of the base metal. Both of the austenite start temperature (As) and finish temperature (Af) of the weld metal and HAZ vary much compared with the base metal. The change in the weld metal is attributed to the fusion-solidification process, in which the preferred crystal orientation is lost. The newly formed precipitation phases show a small size and an uneven distribution. The change in the HAZ refers to the drop of As and Af, which is possibly caused by the solution of minor precipitation phase in the matrix. The As and Af of the laser weld joint are quite the same as those of the weld metal for TiNi shape memory alloy, which indicates that the key to guarantee the shape memory function lies in controlling the phase transformation temperatures of the weld metal.%利用热模拟试样模拟TiNi合金激光焊接接头焊缝热影响区,对焊接接头、焊缝金属、模拟热影响区和母材的相变温度进行差热分析,研究了焊接接头与其它三者逆相变温度的关系,并利用OM,SEM和XRD对母材、热影响区和焊缝金属的组织、析出

  18. Laser welding of dissimilar metals with pulsed Nd:YAG laser

    International Nuclear Information System (INIS)

    An autogenous laser welding of dissimilar materials involving AISI 304 and AISI 420 stainless steels and Inconel 600 nickel alloy was investigated in this research. These materials have been extensively used in industry and their welding with laser is fairly covered by literature. Hence, the aim of this investigation was to study the laser welding features between any two of these materials when using a Nd:YAG pulsed laser. The main parameter studied was the focus beam positioning; it was placed exactly on the joint and also dislocated to both directions. The laser and optical beam parameters were chosen to achieve a good weld with total penetration. The purpose in the use of an asymmetric focus displacement was to compensate for dissimilarity in the physical and metallurgical properties of the materials being joined. The x-ray spectrometry by energy dispersion (EDX) carried out in the melting zone showed a homogeneous distribution in the main elements that yielded a good compatibility between the microhardness and the value of the modulus of elasticity when compared to the parent materials. Optical microscopy pictures showed a typical keyhole weld with total penetration, free of pores and cracks; these defects were only observed in the join between AISI 420 and Inconel 600 alloy. Phase diagrams were obtained to the formed materials in the melted pool; they showed a good agreement with microhardness and metallographic analysis. Tensile strength measurements confirmed the quality of the welds giving high values of efficiency which reached to 100% in the case of AISI 304 and AISI 420 welding. In the presentation of the work, the first chapter gives an introduction to laser welding technology emphasizing its importance and possibilities; it is also pointed out the main applications and demands ill joining these materials. The main theoretical aspects involved in laser welding technique as well as a comparison with conventional welding methods are presented in chapter

  19. Twinning in weld HAZ of ZK21 commercial magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The microstructure and properties of Mg ZK21 laser beam weld without filler were researched using optical microscopy (OM), electron microscopy and mechanical test. The results show that the fracture strain of the joints after laser beam welding reduces by about 10.7% at room temperature. By means of laser beam welding, the fusion zones contain tensile RS, while the base material far away from the fusion line is under balancing compressive RS. The microstructm-es of the weld were characterized by a narrow heat affected zone and twins. Significant { 10-12 } tension twins occur in the weld HAZ during laser welding processing. Due to the influence of temperature field and stress on morphologies, most of twins form twinning bands, which are nearly parallel to the welding direction.

  20. A comparison of the physics of Gas Tungsten Arc Welding (GTAW), Electron Beam Welding (EBW), and Laser Beam Welding (LBW)

    Science.gov (United States)

    Nunes, A. C., Jr.

    1985-01-01

    The physics governing the applicability and limitations of gas tungsten arc (GTA), electron beam (EB), and laser beam (LB) welding are compared. An appendix on the selection of laser welding systems is included.

  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. NARROW GAP LASER WELDING OF THICK SECTION STAINLESS STEEL

    OpenAIRE

    2012-01-01

    Laser welding of metals typically has a weld penetration of 1-2 mm/kW laser power. Therefore laser welding of thick section materials would require very high power lasers. In this paper we report an investigation into multi-pass laser welding of 316L stainless steel sheets of 5-10 mm thickness, based on narrow gap (1.5 mm) approach using a 1 kW single mode fibre laser. A filler wire of 316L with a 0.8 mm diameter was used in the welding process. The integrity of the weld, microstructure and h...

  3. Yb–YAG laser offset welding of AA5754 and T40 butt joint

    OpenAIRE

    Casalino, Giuseppe; MORTELLO, Michelangelo; PEYRE, Patrice

    2015-01-01

    In this work, a 5754 Al alloy and T40 were joined in butt configuration by focusing a fiber laser onto the titanium side, close to the weld centerline (offset). The keyhole was made entirely of titanium, and the fusion of the aluminum was achieved by heat conduction. Neither filler metal nor chamfering was necessary to produce a sound, dissimilar weld. The assembly was free from porosity and spatter defects. The mechanical properties were satisfactory. The energy input, the laser offset, and ...

  4. The influence of screw type, alloy and cylinder position on the marginal fit of implant frameworks before and after laser welding Influência do tipo de parafuso, liga e da posição do cilindro na adaptação marginal das infra-estruturas sob implantes antes e após a soldagem a laser

    OpenAIRE

    Daniela Castilio; Ana Paula Ribeiro do Vale Pedreira; Paulo Henrique Orlato Rossetti; Leylha Maria Nunes Rossetti; Wellington Cardoso Bonachela

    2006-01-01

    Misfit at the abutment-prosthetic cylinder interface can cause loss of preload, leading to loosening or fracture of gold and titanium screws. OBJECTIVES: To evaluate the influence of screw type, alloy, and cylinder position on marginal fit of implant frameworks before and after laser welding. METHODS: After Estheticone-like abutments were screwed to the implants, thirty plastic prosthetic cylinders were mounted and waxed-up to fifteen cylindrical bars. Each specimen had three interconnected p...

  5. System design of welding dynamic displacement measurement using laser ESPI

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on the advantages of electronic speckle pattern interferometry(ESPI), such as non-contact, high precision, strong parasitic light resistance, and full-field measurement, a system for measuring welding dynamic displacement fields using ESPI was designed. The system consists of a 70mW He-Ne laser source, an optical path system, a computer-assisted frame grabber and a processing system. By measuring dynamic displacement fields on one LY2 aluminum alloy plate during an argon arc point welding, it can be proved that using ESPI to measure welding dynamic displacement fields is fully feasible, and this method can offer a solid experimental base for the structure mechanics.

  6. Multi-physical Simulation of Laser Welding

    Science.gov (United States)

    Vázquez, Rodrigo Gómez; Koch, Holger M.; Otto, Andreas

    Laser welding is a highly demanded technology for manufacturing of body parts in the automotive industry. Application of powerful multi-physical simulation models permits detailed investigation of the laser process avoiding intricate experimental setups and procedures. Features like the degree of power coupling, keyhole evolution or currents inside the melt pool can be analyzed easily. The implementation of complex physical phenomena, like multi-reflection absorption provides insight into process characteristics under selectable conditions and yields essential information concerning the driving mechanisms. The implementation of additional physical models e. g. for diffusion discloses new potential for investigating welding of dissimilar materials. In this paper we present a computational study of laser welding for different conditions. Applied to a real case model predictions show good agreement with experimental results. Initial tests including species diffusion during welding of dissimilar materials are also presented.

  7. 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...... 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 at...... distances of 0, 2 and 4 mm away from the virtual weld line for the induction heating process and at distances of 2 and 4 mm for the laser welding with induction heating process. For practical reasons during performance of these laboratory experiments, the induction coil was placed below the sheets, trailing...

  8. 超高强度钢与低合金钢的激光搭接焊性能%Laser lap-welding performance of ultra-high strength steel and micro-alloy steel

    Institute of Scientific and Technical Information of China (English)

    谷诤巍; 于思彬; 韩立军; 孟佳; 徐虹

    2012-01-01

    Based on experiments of Yb: YAG laser welding of quenched ultra-high strength steel (UHSS) EN10292TL4225 and micro alloy steel H340LAD, the effects of welding parameters on welding quality were analyzed. Microstruetures of the joints were observed using the laser confocal scanning microscopy. The tensile-shear strength and the hardness distribution of the welded joint were tested, and the microstructure of the fracture surface was analyzed by SEM (HITACHS-4300). The test results showed that the obtained joint using the optimized parameter is characterized by good mierostructure and mechanical property, the quality meets the actual need of production.%采用Yb:YAG激光器对超高强度钢EN10292TL4225和低合金钢H340LAD进行了激光焊接试验,分析了不同焊接参数对接头质量的影响。利用光学显微镜观察了接头的微观组织,并通过硬度测试及拉剪试验对接头的力学性能进行了测试,最后采用扫描电镜(SEM,HITACHS-4300)对拉伸断口进行了研究。结果表明,采用优化的焊接参数获得的接头具有良好的接头组织和力学性能,焊接质量能够满足实际生产中的需要。

  9. Influence of the Overlapping Factor and Welding Speed on T-Joint Welding of Ti6Al4V and Inconel 600 Using Low-Power Fiber Laser

    Directory of Open Access Journals (Sweden)

    Shamini Janasekaran

    2016-06-01

    Full Text Available Double-sided laser beam welding of skin-stringer joints is an established method for many applications. However, in certain cases with limited accessibility, single-sided laser beam joining is considered. In the present study, single-sided welding of titanium alloy Ti6Al4V and nickel-based alloy Inconel 600 in a T-joint configuration was carried out using continuous-wave (CW, low-power Ytterbium (Yb-fiber laser. The influence of the overlapping factor and welding speed of the laser beam on weld morphology and properties was investigated using scanning electron microscopy (SEM and X-ray diffraction (XRD, respectively. XRD analysis revealed the presence of intermetallic layers containing NiTi and NiTi2 at the skin-stringer joint. The strength of the joints was evaluated using pull testing, while the hardness of the joints was analyzed using Vickers hardness measurement at the base metal (BM, fusion zone (FZ and heat-affected zone (HAZ. The results showed that the highest force needed to break the samples apart was approximately 150 N at a laser welding power of 250 W, welding speed of 40 mm/s and overlapping factor of 50%. During low-power single-sided laser welding, the properties of the T-joints were affected by the overlapping factor and laser welding speed.

  10. LASER NET SHAPE WELDING OF STEELS

    OpenAIRE

    Eghlio, Ramadan Mahmoud

    2012-01-01

    Laser technologies have made distinguished contributions to modern industry. These have typically been realised through the important role played by lasers in the advancement of manufacturing technology in many areas such as welding, which has become an important joining technique and thus promoted the use of lasers in a wide variety of applications in the oil, gas, aerospace, aircraft, automotive, electronics and medical industries.A detailed review of previous work in the use of lasers for ...

  11. Investigation of Optimum Geometry of Bottom End Cap Welding Using Nd:YAG Laser (I)

    International Nuclear Information System (INIS)

    Various welding processes are now available for end cap closure of nuclear fuel element such as gas tungsten arc welding (GTAW), magnetic resistance welding and Nd:YAG laser beam welding (LBW). Even though the resistance and GTAW processes are widely used for manufacturing commercial fuel elements, they cannot be recommended for precise end cap welding of fuel elements due to the complexity of tungsten electrode alignment, wide heat affected zone (HAZ) and concave shapes and large heat input for thin cladding tubes. Therefore, Nd:YAG LBW using optical fiber transmission was selected for bottom end cap welding using HT9 alloy cladding tube. To establish LBW process, and satisfy the requirements of weld quality, preliminary experiments for optimizing welding conditions which had test specimens using bottom end cap to cladding tube were performed. This paper describes the experimental results of the LB welded specimens using bottom end caps, along with the measurements of weld profiles and metallographic examinations. Furthermore, the effect of undercut depth and penetration depth after bottom end cap welding was also investigated by changing laser welding parameters and various dimensional configurations

  12. Dissimilar pulsed Nd:YAG laser welding of pure niobium to Ti–6Al–4V

    International Nuclear Information System (INIS)

    Highlights: • Pulsed Nd:YAG laser welding of Ti–6Al–4V/Nb sheets was carried out successfully. • Laser beam alignment relative to dissimilar joint interface has crucial role. • In tensile testing of as welded sample failure occurred outside the weld in Nb side. - Abstract: Dissimilar butt welding of pure niobium plate to the titanium alloy Ti–6Al–4V sheet using a pulsed Nd:YAG laser is performed. Effects of laser pulse energy, duration and repetition rates on the melt profile on both sides of the weld line were investigated. Considering the thermo-physical properties of the two base metals, variation of the weld profiles on different sides of the weld line is discussed. Through optimization of the process parameters a sound weld with full penetration along the dissimilar interface was obtained. However, islands of Ti rich and Nb rich phases were identified in the weld metal. Tensile strength of the welded joints matched that of the weaker base metal i.e. niobium and the specimens broke outside the fusion line

  13. Weld pool flows during initial stages of keyhole formation in laser welding

    International Nuclear Information System (INIS)

    Weld pool transport phenomena during the transition from conduction-mode laser spot welding to keyhole laser spot welding of titanium were studied by numerical simulation. A range of laser powers were simulated and temperature dependent evaporation recoil pressure and cooling were applied as boundary conditions on the weld pool surface. Simulation results predicted a complex time-varying flow pattern during weld pool development. The surface-normal flow at the weld pool centre oscillated between upwards and downwards during the simulation time due to interaction of competing effects of evaporation recoil and surface tension pressures and laser heating and evaporation cooling. The results show that the laser weld pool flow dynamics play a key role during the transition from conduction-mode laser welding to keyhole welding.

  14. Comparative study on CO2 laser overlap welding and resistance spot welding for galvanized steel

    International Nuclear Information System (INIS)

    Highlights: ► Laser welding and resistance welding are respectively researched on galvanized steel. ► The characteristics of the two kinds of welding methods are systematically analyzed. ► Laser welding joint have much more compact structures and smaller heat-affected zones. ► The tensile-shear performance of laser weld joint is superior under certain condition. ► Laser welding test pieces has greater resistance to deformation and corrosion. -- Abstract: The CO2 laser overlap welding and the resistance spot welding are respectively investigated on DC56D galvanized steel used for auto body. The characteristics of the two types of welding methods are systematically analyzed in terms of the weld molding, tensile-shear performance, microstructure, hardness, and corrosion resistance of welding joint. The results show that, the fusion widths of the upper and lower surface are almost the same for the resistance welding joint, and the weld nugget is surrounded by the heat-affected zone. While the laser welding joint belongs to deep penetration welding, the weld fusion width presents wide at the top and narrow at the bottom, and the heat-affected zone is situated on both sides of the weld pool. Compared with resistance spot welding joint, laser welding joints have much more ultrafine microstructures, much smaller heat-affected zones, as well as greater resistance to deformation and corrosion. In addition, the tensile-shear performance of laser weld joints is superior to that of resistance welding joints under certain conditions.

  15. Study on heat efficiency of laser-TIG double-side welding

    Institute of Scientific and Technical Information of China (English)

    Miao Yugang; Li Liqun; Chen Yanbin; Wu Lin

    2008-01-01

    A series of laser-TIG double-side welding experiments for aluminum alloys were carried out to investigate the heat efficiency of the process. The melting efficiency was introduced to evaluate quantitatively the degree of the mutual effect of the laser and the arc. The results showed that the melting efficiency of laser-TIG double-side welding exceeded the sum of the laser and the arc taken separately. With the increase of heat input, the weld depth and melting efficiency of the laser and the arc were increased significantly. This, in fact, implies the strong mutual effect of the laser and the arc as heat sources joined simultaneously in the process. Comparatively, the higher efficiency of the laser constituent of heat sources plays the main role in the increase of the process efficiency. The phenomena of arc column convergence, increased laser absorptivity and the formation of heat accumulation region are the causes of the improvement of heat efficiency.

  16. Microstructures in laser welded high strength steels

    Science.gov (United States)

    Rizzi, P.; Bellingeri, S.; Massimino, F.; Baldissin, D.; Battezzati, L.

    2009-01-01

    In this work, the effect of laser welding on the microstructure was studied for three Advanced High Strength Steels: transformation induced plasticity steel (TRIP), dual phase steel (DP) and martensitic steel. Two sheets of the same steel were laser welded and a microstructural study was performed by optical microscopy, scanning electron microscopy and X-ray diffraction. For all samples the welded zone was constituted by martensite and the heat affected zone shows a continuous change in microstructure depending on temperatures reached and on the different cooling rates. The change in mechanical properties in the welded area was followed by Vickers micro-hardness measurements. Quasi binary phase diagrams were calculated and, according to position of T0 lines, it was deduced that austenite is the primary phase forming during rapid solidification for all steels.

  17. Microstructures in laser welded high strength steels

    International Nuclear Information System (INIS)

    In this work, the effect of laser welding on the microstructure was studied for three Advanced High Strength Steels: transformation induced plasticity steel (TRIP), dual phase steel (DP) and martensitic steel. Two sheets of the same steel were laser welded and a microstructural study was performed by optical microscopy, scanning electron microscopy and X-ray diffraction. For all samples the welded zone was constituted by martensite and the heat affected zone shows a continuous change in microstructure depending on temperatures reached and on the different cooling rates. The change in mechanical properties in the welded area was followed by Vickers micro-hardness measurements. Quasi binary phase diagrams were calculated and, according to position of T0 lines, it was deduced that austenite is the primary phase forming during rapid solidification for all steels.

  18. Infrared measurement and simulation of magnesium alloy welding temperature field

    Institute of Scientific and Technical Information of China (English)

    LIU; Liming; CHI; Mingsheng; HUANG; Ruisheng; SONG; Gang

    2005-01-01

    The welding temperature field of magnesium alloy AZ31 welded by TIG was measured with the uncooled infrared (IR) thermal imaging technology. The variables in the mathematic mode of welding temperature fields were revised by IR temperature data. Based on the results of simulation, the loss of temperature fields caused by arc interfered was compensated, and a whole temperature field was achieved, which provided a precise and powerful foundation for the investigation of microstructure of the joints.

  19. Feasibility of underwater friction stir welding of hardenable alloy steel

    OpenAIRE

    Overfield, Norman E.

    2010-01-01

    Approved for public release; distribution is unlimited The objective of this thesis is to determine whether friction stir welding (FSW) is a feasible welding process for steels in an underwater environment. Specific benefits would be underwater weld repairs on steel alloy piping systems and/or structures, and crack repairs on control surfaces of submarines without the need for strict environment controls or in the submarine's case, for drydocking. A single tool made of polycrystaline cub...

  20. Welding with brilliant lasers: prospects and limitations

    Science.gov (United States)

    Kittel, Sonja; Dausinger, Friedrich

    2010-02-01

    Now that high brightness laser sources featuring high output power are commercially available, extremely small focal diameters and high power densities permit laser welding with a high aspect ratio at low heat input. With regard to an increase in productivity this implies a deeper weld depth at a higher feed rate and hence at a shorter processing time. In this research, a modular optical system generates focal diameters from 195 μm down to 15 μm for the purpose of identifying the prospects and limitations of the application of high brightness beam sources in laser welding. Metallographical analysis and observation using a high speed camera give information about the weld seam geometry and weld pool dynamics. Thus, the influence of minimizing focal diameters on process stability is evaluated: From the correlation of longitudinal cross-sections and high speed camera observation, an interrelationship between spiking and keyhole breakdown results. In dependence of the particular spot size and the beam quality of the laser source a new processing range arises. These observations are traced back to theoretical beam properties and a fundamental thesis about the applicability of a high brightness laser is derived. Eventually it shows that a small beam diameter is most advantageous for micro application.

  1. Prospect of Friction Stir Welding in Automobile TWB Production as Alternative of Laser Welding

    OpenAIRE

    Shahriyar, Mohammed Hasan

    2012-01-01

    In some situation, commonly used welding processes (Laser and Seam welding) in car industry do not produce mechanically acceptable Tailor Welded Blanks (TWB). The present work explores whether the Friction Stir welding (FSW) can overcome three major drawbacks of Laser welding process to produce TWB for car industry. It is identified that some types of Aluminum to Aluminum joints, some combinations of High Strength Steels (HSS) to HSS joints and Steel to Aluminum joints are troublesome to prod...

  2. Development of laser weld monitoring system for PWR space grid

    International Nuclear Information System (INIS)

    The laser welding monitoring system was developed to inspect PWR space grid welding for KNFC. The demands for this optical monitoring system were applied to Q.C. and process control in space grid welding. The thermal radiation signal from weld pool can be get the variation of weld pool size. The weld pool size and depth are verified by analyzed wavelength signals from weld pool. Applied this monitoring system in space grid weld, improved the weld productivity. (author). 4 refs., 5 tabs., 31 figs

  3. Texture of welded joints of commercial titanum alloys

    International Nuclear Information System (INIS)

    The effect of welding upon the texture of the α-phase in sheets of commercial VT-1-0, VT-5-1, OT-4 and VT-14 alloys was studied with a view of using the effect of texture strengthening. The stability of the weld texture with respect to annealing was investigated by the method of plotting direct and reverse pole figures. It was found that welding results in radical changes of texture in the weld area, this being one of the causes of the inhomogeneity in the mechanical properties of welds. The mechanisms of texture formation in the thermal effect zone are an oriented phase transformation in the regions adjoining the fusion areas and α-phase recrystallization processes in the regions at a greater distance from the weld where the temperature of heating to welding is lower than the polymorphic transformation point. When welded items from α-alloys are annealed, the single-component texture of the base metal is retained; by contrast, new orientations nucleate in multi-component textures in disoriented initial texture. The presence of an appreciable number of disperse hydrides in α-alloys or martensitic β-phase stabilizes the alloy texture irrespective of the latter's type

  4. Cracking in electron beam welding of low alloy steels

    International Nuclear Information System (INIS)

    The study of the cracking in electron beam welding of low alloy steel plates (steel ASTM-A387 gr 22) of high thickness shows that the welding speed to be the essential parameter. A low speed improves the resistance to cracking. The low segregation obtained with this process minimizes the effect of impurities

  5. Electron beam welding of dissimilar heat resistant alloys

    International Nuclear Information System (INIS)

    To the welding of the different heat resistant materials for high temperature gas-cooled reactors, electron beam welding was applied, and the high temperature strength of the weld metal was examined as it is necessary for evaluating the welded joints. As the results, the high temperature strength of the weld metal of Hastelloy X and 2.25 Cr-1Mo steel at 500 degC and that of Hastelloy X and SUS316 at 600 degC showed the nearly intermediate values of both parent materials in both cases. Accordingly, when the high temperature strength of electron beam welded metals is evaluated, it is considered that by evaluating at least with the value of a lower strength parent metal, sufficient safety is ensured. In this study, the electron beam welded joints of typical different heat resistant alloys were made, and the tesile strength, creep rupture strength and low cycle fatique strength of the weld metals at high temperature were determined to compare with those of parent alloys. The tested alloys, welding method and high temperature tests are reported. (Koko, I.)

  6. Use of laser cutting and welding in nuclear industry

    International Nuclear Information System (INIS)

    General data on peculiarities of laser welding and cutting procedure are reviewed. Specific examples of laser application for fuel assembly production and reprocessing, for welding of heat exchangers and pipelines etc are considered to show the advantages of the technique. A series of patents, dealing with laser cutting and welding is being discussed

  7. 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. PMID:10730969

  8. Development of techniques for welding V Cr Ti alloys

    Science.gov (United States)

    Grossbeck, M. L.; King, J. F.; Alexander, D. J.; Rice, P. M.; Goodwin, G. M.

    1998-10-01

    Welding vanadium alloys is complicated by interstitial impurity introduction and redistribution at elevated temperatures. Gas tungsten arc (GTA) welding, which will probably be required for the fabrication of large tokamak structures, must be done in a glove box environment. Welds were evaluated by Charpy testing. GTA welds could be made with a ductile to brittle transition temperature (DBTT) of 50°C with a post-weld heat treatment (PWHT) or by using a heated Ti getter system on the glove box to reduce interstitial contamination. Titanium-O,N,C precipitates in the fusion zone were found to transform to a more oxygen-rich phase during a PWHT of 950°C/2 h. Hydrogen was found to promote cleavage cracking following welding in cases where the atmosphere was contaminated. Grain size and microstructure also affected weld embrittlement.

  9. Laser welded sleeving - a proven technology for steam generator life enhancement

    International Nuclear Information System (INIS)

    Laser welded sleeving was performed for the first time in the United States in April 1992 at the J.M. Farley Nuclear Plant Unit 2. In all, 68 tube support plate sleeves and 30 tubesheet sleeves were installed in two steam generators. This was followed by a larger sleeving campaign in the plant's Unit 1 steam generators in October 1992 when 148 tube support plate sleeves and 46 tubesheet sleeves were installed in three steam generators. The successful implementation of this new technology at Farley provides the industry with a field proven and effective option to repair steam generator tubes and maintain operating plant performance. The laser welding was performed using a fiber optic delivery system to transmit light energy from a pulsed solid state laser located outside containment to the weld head which could be positioned remotely in the tubesheet and as high as the sixth support plate in the steam generator. The sleeve material was thermally treated Alloy 690 (UNS 06690). The joint design was a partial penetration, autogenous weld. All free-span welds, namely the support plate sleeve welds and the tubesheet sleeve upper weld, were thermally stress relieved to enhance stress corrosion life. Those welds were also required to pass a stringent ultrasonic test examination. All the processes for laser welded sleeving were performed remotely using the Westinghouse steam generator service robot, ROSA III. The Farley campaigns showed that laser welded sleeving offers a high degree of process control not found with other methods and produces welds that can be fully inspected by ultrasonic examination. They also demonstrated the field hardiness of the sophisticated laser welding system. 5 figs

  10. Welding characteristics in different laser-TIG hybrid manners

    Institute of Scientific and Technical Information of China (English)

    陈彦宾; 雷正龙; 李俐群; 吴林

    2004-01-01

    An experiment for determining the laser-TIG hybrid welding characteristics was carried out in three kinds of hybrid methods: CO2 laser-TIG coaxial hybrid, CO2 laser-TIG paraxial hybrid and Nd: YAG laser-TIG paraxial hybrid. The experimental results indicate that hybrid welding has two welding mechanisms in CO2 laser-TIG hybrid welding: deep penetration welding and heat conduction welding. As the effect of the laser-induced keyhole, the arc root is condensed, the current density and penetration depth increase significantly, the welding characteristic is apt to deep penetration welding. When current increases to some degree, the keyhole induced by laser disappears, which produces a shallow penetration and wide bead. The weld exhibits heat conduction welding characteristics. Furthermore, the arc images and weld bead cross-sections of three kinds of hybrid manners were also compared and analyzed at different welding currents, which established the foundation for understanding the welding characteristics of laser-TIG hybrid welding comprehensively.

  11. Bead-on-plate weldability of Al 5052 alloy using a disk laser

    Directory of Open Access Journals (Sweden)

    J.-K. Kim

    2008-06-01

    Full Text Available Purpose: The paper presents the effect of the laser welding parameters of the laser focal position and beam angle on the weldability of an Al 5052 thick plate using a 4kW disk laser.Design/methodology/approach: Bead-on-plate welding was conducted on a 10mm-thick Al 5052 plate. Aspects of the bead, including the bead surface and cross sections, were evaluated with various laser welding parameters. The porosity formation was also examined in an X-ray transmission tests.Findings: Although the penetration depth decreased as the focal point moves away from the surface, the appearance of the bead improved and the porosity decreased. The weldability according to the inclination angle of the laser beam was also investigated. It was found that a forward inclination of the laser beam (when the inclination angle is an acute angle could enhance the weldability compared with a backward inclination.Research limitations/implications: The results of the thick plate BOP welding experiments can be expanded to optimizing the Al alloy welding of thin sheets.Practical implications: It is applicable as a ground technique for the laser welding of aluminium alloy to increase the productivity and quality using the recently developed disk laser.Originality/value: The outcome of the research shows the influence of the welding parameters on weldability aspects in disk laser welding of an Al alloy.

  12. 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.

  13. Argon laser-welded arteriovenous anastomoses.

    Science.gov (United States)

    White, R A; Kopchok, G; Donayre, C; White, G; Lyons, R; Fujitani, R; Klein, S R; Uitto, J

    1987-11-01

    This study compared the healing of laser-welded and sutured canine femoral arteriovenous anastomoses. Arteriovenous fistulas 2 cm in length were created bilaterally in the femoral vessels of 10 dogs and were studied at 1 (n = 2), 2 (n = 2), 4 (n = 3), and 8 (n = 3) weeks. In each animal, one anastomosis (control) was closed with running 6-0 polypropylene sutures, and the contralateral anastomosis (experimental) was sealed with an argon laser (0.5 watt, 4 minutes of exposure, 1830 J/cm2/1 cm length of anastomosis). At removal all experimental anastomoses were patent without hematomas, aneurysms, or luminal narrowing. Histologic examination at 4 weeks revealed that laser-welded anastomoses had less inflammatory response and almost normal collagen and elastin reorientation. At 8 weeks sutured anastomoses had significant intimal hyperplasia whereas laser repairs had normal luminal architecture. Tensile strength and collagen production, measured by the synthesis of hydroxyproline and the steady-state levels of type I and type III procollagen messenger ribonucleic acids, at the anastomoses and in adjacent vein and artery specimens were similar in sutured and laser-welded repairs at 2, 4, and 8 weeks. We conclude that argon laser welding of anastomoses is an acceptable alternative to suture techniques, with the advantage of improved healing without foreign body response and possible diminished intimal hyperplasia at the anastomotic line. PMID:3312648

  14. Effect of Stress Mitigation on Precipitation Kinetics of Alloy 22 Welds

    Energy Technology Data Exchange (ETDEWEB)

    El-Dasher, B S; Torres, S G

    2005-01-26

    Understanding the phase stability of Alloy 22 (N06022) is important since the precipitation of tetrahedrally close-packed (TCP) phases over time has been known to adversely affect corrosion and mechanical properties. Prior observations have shown that these phases precipitate during the welding process. After welding, residual stresses due to the solidification and cooling from temperature remain. When the weld cannot be stress-relieved by solution annealing, the application of commercially available stress-mitigation processes such as low plasticity burnishing (LPB) and laser shock peening (LSP) may be used to produce near-surface compressive stresses. This study involved examination of cross-sectional samples of aged 1.25 inch thick welds of Alloy 22 plates using electron backscatter diffraction (EBSD) for TCP identification and micrograph analysis for TCP quantification. Precipitation in both the as-welded and LSP weld was observed primarily in inter-dendritic regions whilst precipitation in the LPB weld was in both inter- and intra-dendritic regions.

  15. Surface roughness and friction coefficient in peened friction stir welded 2195 aluminum alloy

    International Nuclear Information System (INIS)

    The tribological properties of friction stir welded 2195 aluminum alloy joints were investigated for several laser- and shot-peened specimens. The first portion of this study assessed the surface roughness changes at different regions of the weld resulting from the various peening processes and included an atomic force microscopy (AFM) study to reveal fine structures. The second portion investigated the friction characteristics for various conditions when slid against a 440C ball slider. Shot peening resulted in significant surface roughness when compared to the unpeened and laser-peened samples. The initial friction for all types of specimens was highly variable. However, long-term friction was shown to be lowest for samples with no peening treatment. Laser peening caused the friction to increase slightly. The shot peening process on the other hand resulted in an increase of the long-term friction effects on both sides of the weld.

  16. Friction stir welding of copper alloys

    Institute of Scientific and Technical Information of China (English)

    Liu Shuhua; Liu Meng; Wang Deqing; Xu Zhenyue

    2007-01-01

    Copper plates,brass plates and copper/brass plates were friction stir welded with various parameters. Experimental results show that the microstructure of the weld is characterized by its much finer grains as contrasted with the coarse grains of parent materials and the heat-affected zones are very narrow. The microhardness of the copper weld is a little higher than that of parent plate. The microhardness of brass weld is about 25% higher than that of parent material. The tensile strength of copper joints increases with increasing welding speed in the test range. The range of parameters to obtain good welds for copper is much wider than that for brass. When different materials were welded, the position of copper plate before welding affected the quality of FSW joints. If the copper plate was put on the advancing side of weld, the good quality of weld could be got under proper parameters.

  17. 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.

  18. Forming Tests for Laser Welded Blanks

    DEFF Research Database (Denmark)

    Bagger, Claus; Olsen, Flemming Ove; Rasmussen, Mads

    1998-01-01

    Ratio test (LDR)Tensile testBulge testMarziniak testPractical examples obtained for laser welded blanks are shown. In combination, tensile tests and the Bulge test can form the so-called Forming Limiting Curves and examples of curves obtained from laser welded blanks are shown.......In this paper different means for testing the formability of new material combinations used as tailored blanks in the automotive industry are presented. The following forming techniques will be described and their benefits and drawbacks presented :Limiting Dome Height test (LDH)Limiting Drawing...

  19. Dependence of fracture toughness of molybdenum laser welds on processing parameters and in-situ oxygen gettering

    International Nuclear Information System (INIS)

    Fracture toughness properties have been determined for laser welds in different grades of molybdenum. The fracture toughness of welds in sintered molybdenum was consistently less than the fracture toughness of welds in vacuum arc remelted molybdenum. These differences cannot be attributed to oxygen content, since the oxygen level was nominally the same for all grades of molybdenum examined in this program. Alloy additions of titanium by means of physically deposited coatings significantly improved the fracture toughness of welds in sintered molybdenum, whereas titanium additions to welds in vacuum arc remelted molybdenum decreased the fracture toughness slightly. Pulsed laser welds exhibited fine columnar structures and, in the case of sintered molybdenum, superior fracture toughness when compared with continuous wave laser welds. 6 figures, 3 tables

  20. Keyhole formation and its characteristics in laser welding mode transition

    Institute of Scientific and Technical Information of China (English)

    Qin Guoliang; Gao Jinqiang; Lin Shangyang

    2010-01-01

    Keyhole is the most important characteristic for laser deep penetration welding, and its formation indicates the beginning of laser deep penetration welding mode. The keyhole developing process was analyzed and the keyhole formation time was calculated according to welding speed and the length of weld bead formed in the keyhole formation process. The results showed that the keyhole forms in 40-70 ms at different rate of change of laser power. In laser deep penetration welding process, the variation of light intensity radiated by laser induced plasma can identify the keyhole formation, but it can not be used to estimate the keyhole formation time because of delay effect.

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

    OpenAIRE

    Ohashi, T.; Liu, G.

    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...

  2. Digital Laser Welding System for Automobile Side Panel

    OpenAIRE

    Park, Hong-Seok; Choi, Hung-Won

    2010-01-01

    The laser as economical and flexible tool has established a solid ground in industrial manufacturing area. Specially at welding BIW (Body In White) in automobile industry, the importance of it has been increased due to the technological characteristics such as high process speed, slim seam and good capability of automation and so on. For application of laser welding technique, welding principle and influential factors were investigated based on the analysis of laser welding processes. With th...

  3. Laser droplet welding of zinc coated steel sheets

    OpenAIRE

    Jerič, Anže; Grabec, Igor; Govekar, Edvard

    2015-01-01

    The weldability of zinc coated steel sheets is often compromised by weld seam defects caused by rapid zinc vaporisation and burned-off zinc. Owing to this, welded seams usually remain unprotected from corrosion and are accompanied by undesirable porosity. In this paper, the laser droplet generation process and its application to laser droplet welding of zinc coated steel sheets are described. The influences of laser droplet generation and welding process control parameters on the properties o...

  4. Differences between Laser and Arc Welding of HSS Steels

    Science.gov (United States)

    Němeček, Stanislav; Mužík, Tomáš; Míšek, Michal

    Conventional welding processes often fail to provide adequate joints in high strength steels with multiphase microstructures. One of the promising techniques is laser beam welding: working without filler metal and with sufficient capacity for automotive and transportation industry (where the amount of AHSS steels increases each year, as well as the length of laser welds). The paper compares microstructures and properties of HSS (high strength steel) joints made by MAG (Metal Active Gas) and laser welding. The effects of main welding parameters (heat input, welding speed and others) are studied on multiphase TRIP 900 steel tubes and martensitic sheets DOCOL 1200, advanced materials for seat frames and other automotive components. Whereas the strength of conventional welds is significantly impaired, laser welding leaves strength of the base material nearly unaffected. As the nature of fracture changes during loading and depending on the welding method, failure mechanisms upon cross tension tests have been studied as well.

  5. Laser welding of polymers using high-power diode lasers

    Science.gov (United States)

    Bachmann, Friedrich G.; Russek, Ulrich A.

    2003-09-01

    Laser welding of polymers using high power diode lasers offers specific process advantages over conventional technologies, such as short process times while providing optically and qualitatively valuable weld seams, contactless yielding of the joining energy, absence of process induced vibrations, imposing minimal thermal stress and avoiding particle generation. Furthermore this method exhibits high integration capabilities and automatization potential. Moreover, because of the current favorable cost development within the high power diode laser market laser welding of polymers has become more and more an industrially accepted joining method. This novel technology permits both, reliable high quality joining of mechanically and electronically highly sensitive micro components and hermetic sealing of macro components. There are different welding strategies available, which are adaptable to the current application. Within the frame of this discourse scientific and also application oriented results concerning laser transmission welding of polymers using preferably diode lasers are presented. Besides the used laser systems the fundamental process strategies as well as decisive process parameters are illustrated. The importance of optical, thermal and mechanical properties is discussed. Applications at real technical components will be presented, demonstrating the industrial implementation capability and the advantages of a novel technology.

  6. Analysis of Laser-Induced Plume During Disk Laser Welding at Different Speeds

    Science.gov (United States)

    Wang, Teng; Gao, Xiangdong; Katayama, Seiji

    2013-08-01

    During high power disk laser welding, the high-speed photography was used to measure the dynamic images of the laser-induced plume at different laser welding speeds. Various plume features (area, height and brightness) were extracted from the images by the color space clustering algorithm. Combined with observation on the surface and the cross sections of welding samples, the effect of welding speed on welding stability was analyzed. From the experimental results, it was found that these features of plume could reflect the welding state. Thus changes of the plume features corresponded to different welding speeds, which was helpful for monitoring the laser welding stability.

  7. Analysis of Laser-Induced Plume During Disk Laser Welding at Different Speeds

    International Nuclear Information System (INIS)

    During high power disk laser welding, the high-speed photography was used to measure the dynamic images of the laser-induced plume at different laser welding speeds. Various plume features (area, height and brightness) were extracted from the images by the color space clustering algorithm. Combined with observation on the surface and the cross sections of welding samples, the effect of welding speed on welding stability was analyzed. From the experimental results, it was found that these features of plume could reflect the welding state. Thus changes of the plume features corresponded to different welding speeds, which was helpful for monitoring the laser welding stability. (plasma technology)

  8. MODEL OF LASER-TIG HYBRID WELDING HEAT SOURCE

    Institute of Scientific and Technical Information of China (English)

    Chen Yanbin; Li Liqun; Feng Xiaosong; Fang Junfei

    2004-01-01

    The welding mechanism of laser-TIG hybrid welding process is analyzed. With the variation of arc current, the welding process is divided into two patterns: deep-penetration welding and heat conductive welding. The heat flow model of hybrid welding is presented. As to deep-penetration welding, the heat source includes a surface heat flux and a volume heat flux. The heat source of heat conductive welding is composed of two Gaussian distribute surface heat sources. With this heat source model, a temperature field is calculated. The finite element code MARC is employed for this purpose. The calculation results show a good agreement with the experimental data.

  9. Joint properties of dissimilar Al6061-T6 aluminum alloy/Ti–6%Al–4%V titanium alloy by gas tungsten arc welding assisted hybrid friction stir welding

    International Nuclear Information System (INIS)

    Highlights: • Hybrid friction stir welding for Al alloy and Ti alloy joint has been carried out. • Mechanical strength of dissimilar joint by HFSW and FSW has been compared. • Microstructure of dissimilar joint by HFSW and FSW has been compared. - Abstract: Hybrid friction stir butt welding of Al6061-T6 aluminum alloy plate to Ti–6%Al–4%V titanium alloy plate with satisfactory acceptable joint strength was successfully achieved using preceding gas tungsten arc welding (GTAW) preheating heat source of the Ti alloy plate surface. Hybrid friction stir welding (HFSW) joints were welded completely without any unwelded zone resulting from smooth material flow by equally distributed temperature both in Al alloy side and Ti alloy side using GTAW assistance for preheating the Ti alloy plate unlike friction stir welding (FSW) joints. The ultimate tensile strength was approximately 91% in HFSW welds by that of the Al alloy base metal, which was 24% higher than that of FSW welds without GTAW under same welding condition. Notably, it was found that elongation in HFSW welds increased significantly compared with that of FSW welds, which resulted in improved joint strength. The ductile fracture was the main fracture mode in tensile test of HFSW welds

  10. Improvements of the welding performance of plasma arcs by a superimposed fibre laser beam

    Science.gov (United States)

    Mahrle, Achim; Rose, Sascha; Schnick, Michael; Pinder, Thomas; Beyer, Eckhard; Füssel, Uwe

    2012-03-01

    Details and results of experimental investigations of a laser-supported plasma arc welding process are presented. The particular feature of the realized experimental set-up is the coaxial arrangement of a single-mode fibre laser beam through a hollow tungsten electrode in combination with a modified plasma welding torch. The analysis of the welding capabilities of the combined laser-arc source comprises high-speed video recordings of the arc shape and size, corresponding simultaneous measurements of the arc voltage as well as an evaluation of the resultant weld seam geometries. Results of welding trials on different types of steel and aluminum alloys are discussed. The corresponding investigations reveal that a fibre laser beam with a wavelength of 1.07 microns can have a crucial impact on the arc and welding characteristics for both categories of materials even at very low laser power output levels. Beneficial effects are especially observed with high welding speeds. In that particular case the arc root and therefore arc column can be substantially stabilized and guided by the laser-induced hot spot.

  11. Second Phase Precipitation in As-Welded and Solution Annealed Alloy 22 Welds

    Energy Technology Data Exchange (ETDEWEB)

    El-Dasher, B S; Torres, S G

    2005-01-12

    The precipitation characteristics of tetrahedrally close-packed (TCP) phases during the welding and the subsequent solution annealing process of Alloy 22 1 1/2 inch thick plate double-U prototypical welds are investigated. Electron backscatter diffraction (EBSD) was used to provide large scale microstructural observation of the weld cross section, and scanning electron microscopy (SEM) was used to map the location of the TCP phases. Analysis shows that TCP precipitation occurs congruent to the weld passes, with the solution annealing reducing the sizes of coarser precipitates.

  12. Latest Progress in Performance and Understanding of Laser Welding

    Science.gov (United States)

    Katayama, Seiji; Kawahito, Yousuke; Mizutani, Masami

    This paper describes a variety of fundamental research results of laser welding which the authors have recently performed. The behavior and characteristics of a laser-induced plume were elucidated. Especially, in remote welding with a fiber laser, the effect of a tall plume leading to shallow weld was interpreted by considering the interaction of an incident laser beam against the zone of a low refractive index from the Mickelson interferometer results. The laser absorption in the plate was higher in the case of a smaller focused beam of fiber laser, lower welding speed and higher power, and the reason was interpreted by considering the size and location of a keyhole inlet and a beam spot. High power tandem laser beams could produce deep penetration, and laser welding in vacuum was developed for production of deeply penetrated welds. Laser direct joining was also developed for joining of metal to plastic or CFRP.

  13. Welding phenomena of aluminum-copper alloy in electron beam welding

    Energy Technology Data Exchange (ETDEWEB)

    Nogi, K.; Sumi, Y.; Aoki, Y.; Yamamoto, T.; Fujii, H. [Osaka Univ., Ibaraki (Japan). Joining and Welding Res. Inst.

    2000-07-01

    Electron beam welding of an aluminum-copper alloy (2219) was performed using a small-sized electron beam welding apparatus under microgravity and in a high vacuum. The effect of gravity on various welding phenomena and the effect of the aluminum oxide film on the formation of bubbles were investigated. A much flatter weld bead is formed in the microgravity environment than in the terrestrial environment. When an aluminum alloy is exposed to atomic oxygen, the thickness of the aluminum oxide film increases and porosity after welding also increases. It is thought that the porosity is formed by the Al{sub 2}O gas through the reaction between Al{sub 2}O{sub 3} and Al. (orig.)

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

    Science.gov (United States)

    Florea, Radu Stefanel

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

  15. On the Choice of Tool Material in Friction Stir Welding of Titanium Alloys

    OpenAIRE

    Settineri, Luca

    2012-01-01

    Friction Stir Welding (FSW) is a solid state welding process patented in 1991 by TWI; initially adopted to weld aluminum alloys, is now being successfully used also for magnesium alloys, copper and steels. The wide diffusion the process is having is due to the possibility to weld both materials traditionally considered difficult to be welded or "unweldable" by traditional fusion welding processes due to peculiar thermal and chemical material properties, and complex geometries as sandwich stru...

  16. Joining of high temperature refractory alloys by electron beam welding technique

    International Nuclear Information System (INIS)

    High temperature refractory alloys, due to their high melting point and poor oxidation resistance, need a special welding technique which is capable of melting and simultaneously joining them without being contaminated by interstitial impurities. In the present study, joining of TZM alloy was studied by electron beam welding (EBW) technique. Welding parameters such as accelerating voltage, current and speed of welding were varied to achieve good quality weld joint. Optical characterization and microhardness evaluation were carried out on the weld material. (author)

  17. Comparison of joining efficiency and residual stresses in laser and laser hybrid welding

    OpenAIRE

    Suder, Wojciech; Ganguly, Supriyo; Williams, Stewart W.; Paradowska, A.M; Colegrove, Paul A.

    2011-01-01

    Laser welding is a high energy density process, which can produce welds with less energy input and thereby lower residual stress generation compared to arc welding processes. However, the narrow beam dimension makes it extremely sensitive in terms of fit up tolerance. This causes a problem in achieving high quality welds. Laser with arc hybrid process overcomes such issues. In this paper, longitudinal residual strains were compared for autogenous laser welding and laser/TIG ...

  18. 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

  19. Improvement of Weld Quality Using a Weaving Beam in Laser Welding

    Institute of Scientific and Technical Information of China (English)

    Xudong ZHANG; Wuzhu CHEN; Gang BAO; Lin ZHAO

    2004-01-01

    This paper describes a way to improve the weld quality through suppressing the porosity formation and restraining the growth of columnar grains by using a weaving beam in laser welding. The experimental results show that the N2 porosity of beamweaving laser welding low carbon steel can be remarkably reduced with increasing weaving frequency, and porosity can be eliminated when the weaving amplitude is only 0.5 mm; and the Ar porosity in the weld metal is decreased with increasing weaving frequency and amplitude when the welding speed is higher than 0.5 m/min. The beam-weaving laser welding of ultrafine grained steel has been investigated. The experimental results show that beam-weaving laser welding with appropriate amplitude and frequency can partly restrain the growth of the columnar grain and improve the tensile strength of the weld metal.

  20. NUMERICAL SIMULATION OF CONTROLLING IN TITANIUM ALLOY SHEETS WELDING RESIDUAL STRESS BY TRAILING PEENING

    Institute of Scientific and Technical Information of China (English)

    X.S. Liu; H. Y. Fang; W.L. Xu; Z.B. Dong; D.Y. Yu

    2004-01-01

    It is a promising and new technology to apply welding with trailing peening to control welding stress and distortion of titanium alloy. Numerical simulation of conventional welding and welding with trailing peening of the titanium alloy sheet is carried out,using nonlinear finite element theory and the engineering analysis software MARC.The result shows that welding with trailing peening technology reduces longitudinal residual stress in welding joint effectively, and it is more effective to reduce residual stress to peen the weld than to peen the weld toe. It is a effective result that other technology and method used in welding can never achieved.

  1. Microstructures of nickel-base alloy dissimilar metal welds

    OpenAIRE

    Mouginot, Roman; Hänninen, Hannu

    2013-01-01

    Dissimilar metal welds (DMWs) between low-alloy steels (LAS), stainless steels (SS) and nickel-base alloys are very important in the design of conventional and nuclear power plants (NPPs). They help to reach better performances for high temperature environment but they can promote premature failure of components. Failure is often related to cracking in the heat affected zone of base materials. In this study, a literature review was conducted concerning the behavior of Inconel Ni-base alloy...

  2. 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).

  3. Neutron diffraction studies of welds of aerospace aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Martukanitz, R.P.; Howell, P.R. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering; Payzant, E.A.; Spooner, S.; Hubbard, C.R. [Oak Ridge National Lab., TN (United States)

    1996-10-01

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

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

    International Nuclear Information System (INIS)

    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.

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

    International Nuclear Information System (INIS)

    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

  6. 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.

  7. Effects of relative positioning of energy sources on weld integrity for hybrid laser arc welding

    Science.gov (United States)

    Liu, Shuangyu; Li, Yanqing; Liu, Fengde; Zhang, Hong; Ding, Hongtao

    2016-06-01

    This study is concerned with the effects of laser and arc arrangement on weld integrity for the hybrid laser arc welding processes. Experiments were conducted for a high-strength steel using a 4 kW Nd: YAG laser and a metal active gas (MAG) welding facility under two configurations of arc-laser hybrid welding (ALHW) and laser-arc hybrid welding (LAHW). Metallographic analysis and mechanical testing were performed to evaluate the weld integrity in terms of weld bead geometry, microstructure and mechanical properties. The morphology of the weld bead cross-section was studied and the typical macrostructure of the weld beads appeared to be cone-shaped and cocktail cup-shaped under ALHW and LAHW configurations, respectively. The weld integrity attributes of microstructure, phase constituents and microhardness were analyzed for different weld regions. The tensile and impact tests were performed and fracture surface morphology was analyzed by scanning electron microscope. The study showed that ALHW produced joints with a better weld shape and a more uniform microstructure of lath martensite, while LAHW weld had a heterogeneous structure of lath martensite and austenite.

  8. Modeling corrosion behavior of gas tungsten arc welded titanium alloy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The pitting corrosion characteristics of pulse TIG welded Ti-6Al-4V titanium alloy in marine environment were explained.Besides the rapid advance of titanium metallurgy, this is also due to the successful solution of problems associated with the development of titanium alloy welding. The preferred welding process of titanium alloy is frequently gas tungsten arc(GTA) welding due to its comparatively easier applicability and better economy. In the case of single pass GTA welding of thinner section of this alloy, the pulsed current has been found beneficial due to its advantages over the conventional continuous current process. The benefit of the process is utilized to obtain better quality titanium weldments. Four factors, five levels, central composite, rotatable design matrix are used to optimize the required number of experiments. The mathematical models have been developed by response surface method(RSM). The results reveal that the titanium alloy can form a protective scale in marine environment and is resistant to pitting corrosion. Experimental results are provided to illustrate the proposed approach.

  9. 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.

  10. Seam tracking for laser welding with an industrial robot

    OpenAIRE

    Römer, G.R.B.E.; Amerongen, van, W.E.; Jonker, J.B.; Regtien, P.P.L.

    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 for laser welding. These problems can be solved by applying sensors, which measure the location of the seam in real-time. This paper describes the integration and performance of a commercial seam t...

  11. Device for internal laser welding of tubular elements

    International Nuclear Information System (INIS)

    During the welding, the position of the returning mirror of the laser beam is on the order of a transducer in support on the tubular element to be welded. Application for sleeving PWR steam generator tubes

  12. Effect of alloying elements on tendency to reversible temper brittleness of low alloy welds

    International Nuclear Information System (INIS)

    Results of assessing the role of impurity and alloying elements contained in multicomponent (Cr-Ni-Mo system) weld in development of embrittlement during decelerated cooling after tempering to treat for stress-relieve are given as well as of establishing basic concentration and time-temperature regularities of this process. Cr-Mn-Ni-Mo system wires were used in experiments. Quantitative relation between temperature level of transition to brittle state of welds and elements contents affecting embrittlement has been determined. Parametric dependence revealed permits to assess with high confidence cold resistance of Cr-Ni-Mo welds at this stage of choosing the weld material composition, welding and thermal treatment conditions

  13. 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.

  14. Influence of shielding gas composition on weld profile in pulsed Nd:YAG laser welding of low carbon steel

    OpenAIRE

    Jokar, M.; F MalekGhaini; M J Torkamany; Sheikhi, M.

    2014-01-01

    Weld area and weld depth/width ratio can be considered to be of the most important geometrical factors in pulsed laser welding. The effects of carbon dioxide and oxygen additions to the argon shielding gas on the weld properties in pulsed laser welding of low carbon steel is investigated. Presence of carbon dioxide and oxygen up to 10 and 15 percent respectively decreases the weld geometrical factors. But, at higher levels of additions, the weld geometrical factors will increase. It is observ...

  15. Vascular Welding Using The Argon Laser

    Science.gov (United States)

    White, Rodney A.; Donayre, Carlos; Kopchok, George; White, Geoffrey; Abergel, R. Patrick; Lyons, Richard; Klein, Stanley; Dwyer, Richard; Uitto, Jouni

    1987-03-01

    This study compared the histology, biochemistry, and tensile strength of laser welded and sutured canine venotomies, arteriotomies and arteriovenous fistulas. Bilateral femoral, carotid or jugular vessels were studied with one repair (control) closed with interrupted 6-0 polypropylene sutures, and the contralatral repair (experimental) welded with the argon laser. Specimens were examined at weekly intervals from 1 to 4 weeks for each type of repair and evaluated histologically by hematoxylineosin, elastin and trichrome stains, biochemically by the formation of [3H] hyaroxyproline as an index of collagen synthesis, ana mechanically by tensile strength determinations. At removal, all experimental closures were patent without hematomas, aneurysms or luminal dilatation. Histologic and biochemical examination and tensile strength determinations suggest that laser welaing may be an alternative to sutures for repair of large diameter venotomies, arteriotomies and arteriovenous fistulas, as they heal comparable to suture repairs up to 4 weeks postoperatively.

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

    Science.gov (United States)

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

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

  17. Influence of flux and sulfur on YAG laser welding

    Institute of Scientific and Technical Information of China (English)

    K Nakata; D Fan; M Tanaka; M Ushio

    2003-01-01

    The influence of flux and sulfur content on YAG laser welding has been investigated, and the influencing factors and mechanism were discussed. The results show that both surface activating flux and surface active element S have fantastic effects on the YAG laser weld shape, that is to obviously increase the weld penetration and D/W ratio in various welding conditions. The mechanism is thought to be the change of surface tension temperature coefficient in weld pool, thus, the change of fluid flow paten in weld pool due to the flux and sulfur.

  18. The filler powders laser welding of ODS ferritic steels

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Shenyong, E-mail: s_y_liang@126.com; Lei, Yucheng; Zhu, Qiang

    2015-01-15

    Laser welding was performed on Oxide Dispersion Strengthened (ODS) ferritic steel with the self-designed filler powders. The filler powders were added to weld metal to produce nano-particles (Y–M–O and TiC), submicron particles (Y–M–O) and dislocation rings. The generated particles were evenly distributed in the weld metal and their forming mechanism and behavior were analyzed. The results of the tests showed that the nano-particles, submicron particles and dislocation rings were able to improve the micro-hardness and tensile strength of welded joint, and the filler powders laser welding was an effective welding method of ODS ferritic steel.

  19. 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

  20. 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 with....... With the addition of a plasma arc, the hardness could overall be reduced to between 200 and 220 HV1, i.e. about 27 percent. In the seam middle, the reduction was 36 percent....

  1. Etude expérimentale du soudage par laser YAG de l'alliage base nickel Hastelloy X Experimental study of YAG laser welding of nickel base alloy Hastelloy X

    OpenAIRE

    Graneix Jérémie; Beguin Jean-Denis; Pardeilhan François; Masri Talal; Alexis Joël

    2013-01-01

    Le procédé de soudage laser YAG est envisagé pour remplacer le procédé de soudage TIG manuel pour la réalisation de pièces de turboréacteur en alliage nickel-chrome-molybdène Hastelloy X. Cette étude expérimentale a permis de définir un domaine de soudabilité de cet alliage répondant aux critères spécifiques du secteur aéronautique. The YAG laser welding process is contemplated to replace the manual TIG welding process for the production of parts of turbojet in Hastelloy X. This experimental...

  2. Liquid metal expulsion during laser spot welding of 304 stainless steel

    International Nuclear Information System (INIS)

    During laser spot welding of many metals and alloys, the peak temperatures on the weld pool surface are very high and often exceed the boiling points of materials. In such situations, the equilibrium pressure on the weld pool surface is higher than the atmospheric pressure and the escaping vapour exerts a large recoil force on the weld pool surface. As a consequence, the molten metal may be expelled from the weld pool surface. The liquid metal expulsion has been examined both experimentally and theoretically for the laser spot welding of 304 stainless steel. The ejected metal droplets were collected on the inner surface of an open ended quartz tube which was mounted perpendicular to the sample surface and co-axial with the laser beam. The size range of the ejected particles was determined by examining the interior surface of the tube after the experiments. The temperature distribution, free surface profile of the weld pool and the initiation time for liquid metal expulsion were computed based on a three-dimensional transient heat transfer and fluid flow model. By comparing the vapour recoil force with the surface tension force at the periphery of the liquid pool, the model predicted whether liquid metal expulsion would take place under different welding conditions. Expulsion of the weld metal was also correlated with the depression of the liquid metal in the middle of the weld pool due to the recoil force of the vapourized material. Higher laser power density and longer pulse duration significantly increased liquid metal expulsion during spot welding

  3. 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...

  4. 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

    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......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...... 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...

  5. In vitro NIR laser tissue welding of porcine ocular tissues

    Science.gov (United States)

    Rosen, Richard B.; Savage, Howard E.; Halder, Rabindra K.; Kartazayeu, Uladzimir; McCormick, Steven A.; Katz, Alvin; Perry, Henry D.; Alfano, Robert R.

    2005-04-01

    In this study, 72 different combinations of laser welding parameters were compared for their effectiveness in welding ocular tissue. The laser employed in the welding system was a near infrared (NIR) erbium fiber laser with a wavelength of 1.455 μm . The laser system used a motorized translational stage and shutter to control the laser exposure of the tissue being welded. The emission wavelength of the laser in the NIR range corresponds to one of the lesser absorption bands of water. Parameters of the laser welding system that could be changed to allow a more effective distribution of the laser energy and therefore management of thermal energy included: the number and kinds of intricate offset patterns of light on or around the incision, the number of lines per pattern, the power level, the speed of the laser beam movement over the tissues, the spot size, dwell time and the focus plane of the light beam in the tissue. Histopathology was used as an endpoint indication of the effects that the various sets of welding parameters had on the welded tissues. Standard Hematoxylin and Eosin stain and Sirius Red F3B (Direct Red 80) in combination with polarization microscopy were used to stain and visualize the welded ocular tissue. Paradoxically, the best cornea welds quantified using histopathology occurred with fluence of 4,500 mJ/cm2 or less while the corneal welds exhibiting the strongest tensile strengths, but most tissue damage had a delivered fluence above 7,000 mJ/cm2. The best histological representatives of welded corneas had an average delivered fluence of 2,687 mJ/cm2 and an irradiance of 14 W/cm2. Using the properly determined parameters, the NIR erbium fiber welding system provided full thickness welds without the requirement of extrinsic dyes, chromophores, or solders. The NIR laser system with the appropriately developed parameters can be used effectively to weld ocular tissues.

  6. Interface reaction in aluminium matrix composite at laser welding

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Interface reaction of SiCw/6061Al aluminium matrix composite subjected to laser welding was studied. It is pointed out that the main reason for bad weldability of the material is concerned with the interface reaction during the welding. Effects of welding parameters on interface reaction were also investigated. The results show that the interface bonding state can be improved by laser beam, and the main welding parameter affecting the strength of weld is laser output power. The smaller the output power, the lower the extent of interface reaction and the better the mechanical properties.

  7. High-speed laser welding of plastic films

    Science.gov (United States)

    Coelho, J. P.; Abreu, M. A.; Pires, M. C.

    2000-10-01

    Laser welding of plastic materials has a large field of applications in the packaging industry provided that it can compete, in quality and productivity, with currently used industrial methods. Welding of white and transparent thin films of polypropylene and polyethylene of low and high density at high speeds of 20 m s -1 using a CO 2 laser has been studied experimentally.` The weld process has been characterised by the specific energy required for each thickness, kind of plastic and the resistance of the weld seam. The influence of the dimensions of the laser beam spot on weld strength has also been analysed.

  8. Welding development for V-Cr-Ti alloys

    Energy Technology Data Exchange (ETDEWEB)

    King, J.F.; Goodwin, G.M.; Alexander, D.J. [Oak Ridge National Lab., TN (United States)

    1995-04-01

    A vanadium structure, cooled with helium, is a favored concept for an advanced breeding blanket for fusion systems. The objective of this task is to develop the metallurgical and technological base for the welding of thick sections of V-Cr-Ti. The subsize Charpy test results for electron beam weld metal from the V-5Cr-5Ti alloy has shown significant improvement in Charpy fracture energy compared to both gas tungsten arc weld metal and the base metal itself. These results are preliminary, however, and additional confirmation testing and analysis will be required to explain this improvement in properties.

  9. Friction Stir Welding of Al 5052 with Al 6061 Alloys

    OpenAIRE

    Kumbhar, N. T.; Bhanumurthy, K.

    2012-01-01

    Friction stir welding (FSW), a solid-state joining technique, is being extensively used in similar as well as dissimilar joining of Al, Mg, Cu, Ti, and their alloys. In the present study, friction stir welding of two aluminium alloys—AA6061 and AA5052—was carried out at various combinations of tool rotation speeds and tool traverse speeds. The transverse cross-section of the weld was used for optical as well as electron microscopy observations. The microstructural studies were used to get an ...

  10. Fiber laser welding of AISI 304 stainless steel plates

    International Nuclear Information System (INIS)

    Compared with conventional lasers, fiber laser welding is characterized by high melting efficiency, deferent keyhole modes and power density characteristics, which could affect the heat and melt flow of the molten pool during welding. The objective of the present work was to study the fiber laser weldability of 5 mm thick AISI 304 austenitic stainless steel plates; therefore, bead-on-plate welding was exploited on AISI 304 stainless steel plates with different laser powers, welding speeds, defocused distances with different types of shielding gas and their effects on the weld zone geometry and properties and final solidification microstructure at room temperature. Laser power, welding speed and defocused distance have a great effect on the bead appearance and weld zone shape while almost no significant effect on both the type of microstructure and mechanical properties of welds. The microstructure of all laser welds was always austenitic including about 3-5 % ferrite. However, the lower the laser power and/or the higher the welding speed, the finer solidification structure, primary ferrite or mixed-mode solidification resulted in crack-free welds. (author)

  11. Moiré method analysis for tensile strain field of 2024 aluminum alloy welded joint

    Institute of Scientific and Technical Information of China (English)

    徐文立; 魏艳红; 刘雪松; 方洪渊; 赵敏; 田锡唐

    2003-01-01

    Using experimental mechanics method of moiré analysis, strain field distributions of 2024 aluminum alloy welded joints under different conditions were investigated. The results show that moiré stripes of welded joint without trailing peening just before fracture are not only few and scattered but also uneven, and the stress mainly concentrates on the poor position-welded toes during the tensioning process with the relatively poor mechanical properties of welded joints; When the method of welding with trailing peening is adopted, moiré stripes of welded joint just before fracture are relatively thick and even due to the strengthening welded toes during the welding process, and fracture position transfers from the welded toes to weld, at the same time the mechanical properties of welded joints are improved greatly than conventional welding which can show that the technology of trailing peening is effective to strengthen welded joints of aluminum alloy with high strength.

  12. Modelling of laser welding of flat parts using the modifying nanopowders

    Science.gov (United States)

    Cherepanov, A. N.; Shapeev, V. P.

    2013-06-01

    A mathematical model is formulated to describe thermophysical processes at laser welding of metal plates for the case when the modifying nanoparticles of refractory compounds have been introduced in the weld pool (the nanopowder seed cultrure fermenters — NSCF). Specially prepared nanoparticles of refractory compounds serve the crystallization centers that is they are in fact the exogenous primers, on the surface of which the individual clusters are grouped. Owing to this, one can control the process of the crystallization of the alloy and the formation of its structure and, consequently, the joint weld properties. As an example, we present the results of computing the butt welding of two plates of aluminum alloy and steel. Computed and experimental data are compared.

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

    OpenAIRE

    Enrico Lertora; Chiara Mandolfino; Carla Gambaro

    2014-01-01

    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 kin...

  14. Development of underwater welding with high power YAG laser

    International Nuclear Information System (INIS)

    Underwater YAG laser welding technology has been developed by IHI. Use of optical fiber for the YAG laser welding system provides accessibility to distant or confined repair work sites. The welding system is also applicable to repair welding of reactor pressure vessels (RPV) and the internal structures of these vessels. Stable underwater welding was successfully performed using the center gas shielding method at a water pressure up to 0.4 MPa. No defects were found in welds by radiographic testing. Bead width and penetration depth became wider and shallower with increasing water pressure, respectively. The cooling rate of YAG laser welding was measured and proved to be higher than that of TIG welding. (author)

  15. Development of underwater welding with a high power YAG laser

    International Nuclear Information System (INIS)

    Underwater YAG laser welding technology has been developed by IHI. Use of optical fiber for the YAG laser welding system provides accessibility to distant or confined repair work sites. The welding system is also applicable to repair welding of reactor pressure vessels (RPV) and the internal structures of these vessels. Stable underwater welding was successfully performed using the center gas shielding method at a water pressure up to 0.4 MPa. No defects were found in welds by radiographic testing. Bead width and penetration depth became wider and shallower with increasing water pressure, respectively. The cooling rate of YAG laser welding was measured and proved to be higher than that of TIG welding. (author)

  16. Laser penetration spike welding: a welding tool enabling novel process and design opportunities

    Science.gov (United States)

    Dijken, Durandus K.; Hoving, Willem; De Hosson, J. Th. M.

    2002-06-01

    A novel method for laser welding for sheet metal. is presented. This laser spike welding method is capable of bridging large gaps between sheet metal plates. Novel constructions can be designed and manufactured. Examples are light weight metal epoxy multi-layers and constructions having additional strength with respect to rigidity and impact resistance. Its capability to bridge large gaps allows higher dimensional tolerances in production. The required laser systems are commercially available and are easily implemented in existing production lines. The lasers are highly reliable, the resulting spike welds are quickly realized and the cost price per weld is very low.

  17. Cold cracks in the welding of alloy-treated steels

    International Nuclear Information System (INIS)

    Cold shortness is one of the most frequent causes of failure when alloy-treated steels are welded. It occurs in different forms, but distinguishes itself by the fact that its appearance is directly associated with the welding process and exhibits predominantly an intercrystalline form which shows a typical formation especially under a raster electron microscope. The purpose of this paper is to describe experience of the subject of cold shortness of alloy-treated steels, to explain the appearances of these cold cracks in their various forms, to elucidate the causes of the occurrence of such cracks and to postulate possible remedial measures. (orig.)

  18. Cold cracks in the welding of alloy-treated steels

    Energy Technology Data Exchange (ETDEWEB)

    Cerjak, H.; Breckwoldt, E.; Loehberg, R.; Schmidt, J.; Papouschek, F.

    1982-04-01

    Cold shortness is one of the most frequent causes of failure when alloy-treated steels are welded. It occurs in different forms, but distinguishes itself by the fact that its appearance is directly associated with the welding process and exhibits predominantly an intercrystalline form which shows a typical formation especially under a raster electron microscope. The purpose of this paper is to describe experience of the subject of cold shortness of alloy-treated steels, to explain the appearances of these cold cracks in their various forms, to elucidate the causes of the occurrence of such cracks and to postulate possible remedial measures.

  19. Comparative study of evolution of residual stress state by local mechanical tensioning and laser processing of ferritic and austenitic structural steel welds.

    OpenAIRE

    Sule, Jibrin; Ganguly, Supriyo; Coules, Harry E; Pirling, T.

    2015-01-01

    Complex thermal stresses generated in welded structures are undesirable but inevitable in fusion welding. The presence of residual stresses can be detrimental to the integrity of a welded joint. In this research, redistribution of residual stress magnitude and profile was studied and compared in two multi-pass welded structural alloys (API X100 and 304L stainless steel) after cold rolling and laser processing. The residual stress field was studied by neutron diffraction using the SALSA strain...

  20. Study on CO2 laser weldability of Fe-Mn-Si shape memory alloy

    Science.gov (United States)

    Zhou, Chaoyu; Lin, Chengxin; Liu, Linlin

    2012-04-01

    In this study, a cross-flow laser with maximum out power of 5kW was applied to the welding of Fe-Mn-Si shape memory alloys (SMA). The optimal welding processing parameters of 1mm thick Fe-Mn-Si SMA were established by orthogonal experiment. With the optimal processing parameters, power 1600W, welding speed 2.2m/min, defocusing distance 0.6mm, the tensile strength of the welded joint can achieve 93.5% of the base material, and the weld undercut and reinforcement transfer smoothly on the surface of the welding seam and the cross-section of the welding seam morphology presents "X" shape. The fracture appears in the weld fusion zone, so this area is weak during the laser welding. By the metallographic observation, the weld center structure is small equated, and the region of fusion zone is thick cellular crystal that decreases the strength of the welded joint, and the X-ray diffraction (XRD) test proves that the laser welding promotes the grain refinement. The micro-hardness analysis shows that the hardness of the fusion zone is lower than the other area clearly which is also associated to the weld structure. By the fracture scanning electron microscope (SEM) analysis, it is found that the fracture of Fe-Mn-Si SMA shows many small dimples with the optimal parameters, and the result is accorded with the base material which belongs to plastic fracture.

  1. Equalization of Ti-6Al-4 V alloy welded joint by scanning electron beam welding

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The equalization of Ti-6Al-4V alloy welded joint with base metal on corrosion resistance, strength and ductility was studied. The solidification microstructure is transformed from 650 μm columnar grains to 100 μm equiaxed grains by scanning electron beam welding. The anodic polarization curve of 150 μm equiaxed grains coincides with that of base metal. Equal corrosion resistance between weld metal and base metal was ob tained. Uniform microstructure and solutedistribution are the basis of equalization. Corrosion rate of weld with 150 μm equiaxed grains is the lowest, 2.45 times lower than that of 650 μm columnar grains. Weld strength is 98% as much as that of base metal, yield-strength ratio is 99.5%, which is 3.6% higher than that of base metal.

  2. Electrochemical Testing of Gas Tungsten Arc Welded and Reduced Pressure Electron Beam Welded Alloy 22

    International Nuclear Information System (INIS)

    Alloy 22 (N06022) is the material selected for the fabrication of the outer shell of the nuclear waste containers for the Yucca Mountain high-level nuclear waste repository site. A key technical issue in the Yucca Mountain waste package program has been the integrity of container weld joints. The currently selected welding process for fabricating and sealing the containers is the traditional gas tungsten arc welding (GTAW) or TIG method. An appealing faster alternative technique is reduced pressure electron beam (RPEB) welding. Standard electrochemical tests were carried on GTAW and RPEB welds as well as on base metal to determine their relative corrosion behavior in SCW at 90 C (alkaline), 1 M HCl at 60 C (acidic) and 1 M NaCl at 90 C (neutral) solutions. Results show that for all practical purposes, the three tested materials had the electrochemical behavior in the three tested solutions

  3. Corrosion Characteristics of Welding Zones by Laser and TIG Welding of 304 Stainless Steel

    International Nuclear Information System (INIS)

    Two types of welding methods were performed on austenitic 304 stainless steel: laser welding and TIG welding. The differences of the corrosion characteristics of the welded zones from the two welding methods were investigated with electrochemical methods, such as measurement of the corrosion potential, polarization curves, cyclic voltammogram, etc. The vickers hardness of all laser-welded zones (WM: weld Metal, HAZ: Heat Affected Zone, BM: Base Metal) was relatively higher while their corrosion current densities exhibited a comparatively lower value than those which were TIG welded. In particular, the corrosion current density of the TIG-welded HAZ had the highest value among all other welding zones, which suggests that chromium depletion due to the formation of chromium carbide occurs in the HAZ, which is in the sensitization temperature range, thus it can easily be corroded with an active anode. Intergrenular corrosion was also observed at the TIG-welded HAZ and WM zones. Consequently, we can see that corrosion resistance of all austenitic 304 stainless steel welding zones can be improved via the use of laser welding

  4. CHARACTERISTICS OF DROPLET TRANSFER IN CO2 LASER-MIG HYBRID WELDING WITH SHORT-CIRCUITING MODE

    Institute of Scientific and Technical Information of China (English)

    LEI Zhenglong; CHEN Yanbin; LI Liqun; WU Lin

    2006-01-01

    LF6 aluminum alloy plates with 4.5 mm thickness are welded in this experiment. Welding is carried out by using the CO2 laser-MIG paraxial hybrid welding in flat position. The experimental results indicate that the inherent droplet transfer cycle time of conventional MIG arc is changed due to the interaction between CO2 laser beam and MIG arc in the short-circuiting mode of laser-MIG hybrid welding. Because of the preheating action of CO2 laser to electrode and base material, the droplet transfer frequency of MIG arc is increased in the hybrid welding process. When laser power is increased to a certain degree, the droplet transfer frequency is decreased due to the effect of laser-induced keyhole. Furthermore, through analyzing the MIG welding current and arc voltage waveforms and the characteristics of droplet transfer in the hybrid welding process, the effect of laser energy and the action point between laser beam and arc on the frequency of droplet transfer and weld appearance is investigated in details.

  5. Laser beam welding of high-nitrogen-containing austenitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Iamboliev, T.; Zumbilev, A. (Technical Univ. of Plovidiv (Bulgaria)); Christov, S.; Kalev, L. (Bulgarian Academy of Science, Sofia (Bulgaria)); Ianev, V. (Optical Technology Inst., Plovdiv (Bulgaria)); Stang, R.G. (Univ. of Washington, Seattle, WA (United States). Dept. of Materials Science and Engineering)

    1999-07-01

    A continuous wave CO[sub 2] laser was used to weld 2- and 6-mm-high nitrogen-containing stainless steel plates with a composition of 18% Cr-0.6% N-12% Mn. A study of the weld properties revealed that defect-free welds were produced. The N content in the porosity-free welds was in the range of 70--78% of the N content in the base metal using Ar shielding and 77--88% when N was used as a shielding gas. The microstructure of the weld metal was fully austenitic. The yield strength joint efficiency was 83--87% and ductility was in the range of 88--92% compared to the base metal values. It is proposed that the degradation of the mechanical properties is due to the decrease in N in the weld metal. The intergranular corrosion resistance was studied after sensitization and immersion in boiling sulfuric acid and lactic acid. The corrosion resistance of the welds, for the alloy studied, was almost equal to that for a conventional stainless alloy 18% Cr-10% Ni-0.6% Ti in the as-welded condition. After sensitizing, the corrosion resistance was reduced.

  6. Laser welding of stainless steel and manufacturing industrial components

    International Nuclear Information System (INIS)

    Both conduction and key-hole laser welding processes are used for industrial manufacturing of stainless steel components, however laser is highly competitive against arc or plasma welding methods only in key-hole processes. The advantages of using laser in conduction model are only limited to the very low thickness sheets. (author)

  7. Seam tracking for laser welding with an industrial robot

    NARCIS (Netherlands)

    Römer, G.R.B.E.; Amerongen, van J.; Jonker, J.B.; Regtien, P.P.L.

    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

  8. CO2 laser welding of AISI 321stainless steel

    International Nuclear Information System (INIS)

    CO2 laser welding of AISI 321austenitic stainless steel has been carried out. Bead on plate welds on 2 mm thick steel were performed with 450W CO2 laser at speeds ranging from 200 to 900 mm/min. It was observed that weld depth and width was decreased with increasing the speed at constant laser power. Butt welds on different sheet thickness of 1, 2 and 2.5 mm were performed with laser power of 450 W and at speed 750, 275 and 175 mm/min, respectively. The microstructures of the welded joints and the heat affected zones (HAZ) were examined by optical microscopy and SEM. The austenite/delta ferrite microstructure was reported in the welded zone. The microhardness and tensile strength of the welded joints were measured and found almost similar to base metal due to austenitic nature of steel

  9. Electrical potential difference during laser welding

    Science.gov (United States)

    Zohm, H.; Ambrosy, G.; Lackner, K.

    2015-01-01

    We present a new model for the generation of thermoelectric currents during laser welding, taking into account sheath effects at both contact points as well as the potential drop within the quasi-neutral plasma generated by the laser. We show that the model is in good agreement with experimentally measured electric potential difference between the hot and the cold parts of the welded workpiece. In particular, all three elements of the model are needed to correctly reproduce the sign of the measured voltage difference. The mechanism proposed relies on the temperature dependence of the electron flux from the plasma to the workpiece and hence does not need thermoemission from the workpiece surface to explain the experimentally observed sign and magnitude of the potential drop.

  10. Study of fundamental parameters in hybrid laser welding

    OpenAIRE

    Suder, Wojciech

    2011-01-01

    This thesis undertakes a study of laser welding in terms of basic laser material interaction parameters. This includes power density, interaction time and specific point energy. A detailed study of the correlation between the laser material interaction parameters and the observed weld bead profiles is carried out. The results show that the power density and the specific point energy control the depth of penetration, whilst the interaction time controls the weld width. These parameters uniquel...

  11. Influence of aluminium alloy type on dissimilar friction stir lap welding of aluminium to copper

    OpenAIRE

    Galvão, I; Verdera, D; Gesto, D; Loureiro, A.; Rodrigues, D. M.

    2013-01-01

    A heat-treatable (AA 6082) and a non-heat treatable (AA 5083) aluminium alloys were friction stir lap welded to copper using the same welding parameters. Macro and microscopic analysis of the welds enabled to detect important differences in welding results, according to the aluminium alloy type. Whereas important internal defects, resulting from ineffective materials mixing, were detected for the AA 5083/copper welds, a relatively uniform material mixing was detected in the AA 6082/copper wel...

  12. On the Mechanisms for Martensite Formation in YAG Laser Welded Austenitic NiTi

    Science.gov (United States)

    Oliveira, J. P.; Braz Fernandes, F. M.; Miranda, R. M.; Schell, N.

    2016-03-01

    Extensive work has been reported on the microstructure of laser-welded NiTi alloys either superelastic or with shape memory effect, motivated by the fact that the microstructure affects the functional properties. However, some effects of laser beam/material interaction with these alloys have not yet been discussed. This paper aims to discuss the mechanisms for the occurrence of martensite in the heat-affected zone and in the fusion zone at room temperature, while the base material is fully austenitic. For this purpose, synchrotron radiation was used together with a simple thermal analytic mathematical model. Two distinct mechanisms are proposed for the presence of martensite in different zones of a weld, which affects the mechanical and functional behavior of a welded component.

  13. Optimization of friction stir welding parameters for improved corrosion resistance of AA2219 aluminum alloy joints

    OpenAIRE

    G. Rambabu; D. Balaji Naik; C.H. Venkata Rao; K. Srinivasa Rao; G. Madhusudan Reddy

    2015-01-01

    The aluminium alloy AA2219 (Al–Cu–Mg alloy) is widely used in the fabrication of lightweight structures with high strength-to-weight ratio and good corrosion resistance. Welding is main fabrication method of AA2219 alloy for manufacturing various engineering components. Friction stir welding (FSW) is a recently developed solid state welding process to overcome the problems encountered in fusion welding. This process uses a non-consumable tool to generate frictional heat on the abutting surfac...

  14. Laser welding of stainless steel tubes

    Czech Academy of Sciences Publication Activity Database

    Chmelíčková, Hana; Lapšanská, Hana; Hiklová, Helena; Havelková, Martina

    Olomouc: Palacky University, 2010 - (Šmíd, P.; Horváth, P.; Hrabovský, M.), s. 107-114 ISBN 978-80-244-2533-7. [International Scientific Conference Experimental Stress Analysis 2010 /48./. Velké Losiny (CZ), 31.05.2010-03.06.2010] R&D Projects: GA AV ČR KAN301370701 Institutional research plan: CEZ:AV0Z10100522 Keywords : laser * welding * tubes * process parameters Subject RIV: BH - Optics, Masers, Lasers http://ean2010.upol.cz/site_cs/

  15. Plasma bursts in deep penetration laser welding

    Czech Academy of Sciences Publication Activity Database

    Mrňa, Libor; Šarbort, Martin

    Amsterdam: Elsevier, 2014, s. 1-1436. ISSN 1875-3892. [LANE 2014. International Conference on Photonic Technolgies /8./. Fürth (DE), 08.09.2014-11.09.2014] R&D Projects: GA MŠk ED0017/01/01; GA MŠk(CZ) LO1212; GA MŠk EE2.4.31.0016; GA MPO 2A-3TP1/113 Institutional support: RVO:68081731 Keywords : laser welding * plasma bursts * intensity oscillations * frequency analysis Subject RIV: BH - Optics, Masers, Lasers

  16. TEMPORARILY ALLOYING TITANIUM TO FACILITATE FRICTION STIR WELDING

    Energy Technology Data Exchange (ETDEWEB)

    Hovanski, Yuri

    2009-05-06

    While historically hydrogen has been considered an impurity in titanium, when used as a temporary alloying agent it promotes beneficial changes to material properties that increase the hot-workability of the metal. This technique known as thermohydrogen processing was used to temporarily alloy hydrogen with commercially pure titanium sheet as a means of facilitating the friction stir welding process. Specific alloying parameters were developed to increase the overall hydrogen content of the titanium sheet ranging from commercially pure to 30 atomic percent. Each sheet was evaluated to determine the effect of the hydrogen content on process loads and tool deformation during the plunge phase of the friction stir welding process. Two materials, H-13 tool steel and pure tungsten, were used to fabricate friction stir welding tools that were plunged into each of the thermohydrogen processed titanium sheets. Tool wear was characterized and variations in machine loads were quantified for each tool material and weld metal combination. Thermohydrogen processing was shown to beneficially lower plunge forces and stabilize machine torques at specific hydrogen concentrations. The resulting effects of hydrogen addition to titanium metal undergoing the friction stir welding process are compared with modifications in titanium properties documented in modern literature. Such comparative analysis is used to explain the variance in resulting process loads as a function of the initial hydrogen concentration of the titanium.

  17. Some studies on weld bead geometries for laser spot welding process using finite element analysis

    International Nuclear Information System (INIS)

    Highlights: → In this study, a 2 kW Nd:YAG laser welding system is used to conduct laser spot welding trials. → The size and shape of the laser spot weld is predicted using finite element simulation. → The heat input is assumed to be a three-dimensional conical Gaussian heat source. → The result highlights the effect of beam incident angle on laser spot welds. → The achieved results of numerical simulation are almost identical with a real weldment. -- Abstract: Nd:YAG laser beam welding is a high power density welding process which has the capability to focus the beam to a very small spot diameter of about 0.4 mm. It has favorable characteristics namely, low heat input, narrow heat affected zone and lower distortions, as compared to conventional welding processes. In this study, finite element method (FEM) is applied for predicting the weld bead geometry i.e. bead length (BL), bead width (BW) and depth of penetration (DP) in laser spot welding of AISI 304 stainless steel sheet of thickness 2.5 mm. The input parameters of laser spot welding such as beam power, incident angle of the beam and beam exposure time are varied for conducting experimental trials and numerical simulations. Temperature-dependent thermal properties of AISI 304 stainless steel, the effect of latent heat of fusion, and the convective and radiative aspects of boundary conditions are considered while developing the finite element model. The heat input to the developed model is assumed to be a three-dimensional conical Gaussian heat source. Finite-element simulations of laser spot welding were carried out by using Ansys Parametric Design Language (APDL) available in finite-element code, ANSYS. The results of the numerical analysis provide the shape of the weld beads for different ranges of laser input parameters that are subsequently compared with the results obtained through experimentation and it is found that they are in good agreement.

  18. Effects of Different R ratios on Fatigue Crack Growth in Laser Peened Friction Stir Welds

    Science.gov (United States)

    Hatamleh, Omar; Hackel, Lloyd; Forth, Scott

    2007-01-01

    The influence of laser peening on the fatigue crack growth behavior of friction stir welded (FSW) Aluminum Alloy (AA) 7075-T7351 sheets was investigated. The surface modification resulting from the peening process on the fatigue crack growth of FSW was assessed for two different R ratios. The investigation indicated a significant decrease in fatigue crack growth rates resulting from using laser shock peening compared with unpeened, welded and unwelded specimens. The slower fatigue crack growth rate was attributed to the compressive residual stresses induced by the peening.

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

    Institute of Scientific and Technical Information of China (English)

    Yanbin Chen; Zhenglong Lei; Liqun Li; Lin Wu

    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 thedroplet 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 stablehybrid welding, and the frequency of droplet transfer and the penetration depth increase significantly.

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

    International Nuclear Information System (INIS)

    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)

  1. 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.

  2. 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.

  3. Impact properties and hardening behavior of laser and electron-beam welds of V-4Cr-4Ti

    Energy Technology Data Exchange (ETDEWEB)

    Chung, H.M.; Strain, R.V.; Tsai, H.C.; Park, J.H.; Smith, D.L. [Argonne National Lab., IL (United States)

    1996-10-01

    The authors are conducting a program to develop an optimal laser welding procedure that can be applied to large-scale fusion-reactor structural components to be fabricated from vanadium-base alloys. Results of initial investigation of mechanical properties and hardening behavior of laser and electron-beam (EB) welds of the production-scale heat of V-4Cr-4Ti (500-kg Heat 832665) in as-welded and postwelding heat-treated (PWHT) conditions are presented in this paper. The laser weld was produced in air using a 6-kW continuous CO{sub 2} laser at a welding speed of {approx}45 mm/s. Microhardness of the laser welds was somewhat higher than that of the base metal, which was annealed at a nominal temperature of {approx}1050{degrees}C for 2 h in the factory. In spite of the moderate hardening, ductile-brittle transition temperatures (DBTTs) of the initial laser ({approx}80{degrees}C) and EB ({approx}30{degrees}C) welds were significantly higher than that of the base metal ({approx}{minus}170{degrees}C). However, excellent impact properties, with DBTT < {minus}80{degrees}C and similar to those of the base metal, could be restored in both the laser and EB welds by postwelding annealing at 1000{degrees}C for 1 h in vacuum.

  4. Fully automitized welding with laser sensing; Laser sensor ni yoru yosetsu no kanzen jidoka

    Energy Technology Data Exchange (ETDEWEB)

    Uota, K.; Ashida, Y.; Bowaro, J.

    1998-05-01

    This paper introduces a laser vision system developed by Servo Robot Corporation, and examples of application of the system. This laser vision system consists of a laser sensor camera, a controller and software. The laser sensor camera measures contour, features, position and direction of an object by using an optical triangulation technology. The camera head has a special optical system in which the laser sensor is not subjected to influence of welding arc, where air cooling is performed on heat generated by the arc. The software package, USER-2000, performs two-dimensional visual indication on the contour and strength, indication of image processing results, setting of transmission velocity, and installation of VISUS, ADAP, TRAC-2000 and ROBO-2000. The laser vision system is combined with powerful application software, and applied to different welding methods, such as MIG welding, MAG welding, laser welding (using CO2 laser and YAG laser), submerged arc welding, and TIG welding. 12 figs., 1 tab.

  5. TIG welding phenomenon and properties of welds in welding atmospheres with various oxygen and nitrogen partial pressures. Pt. 1. Study on welding of zirconium alloy tubing. 3

    International Nuclear Information System (INIS)

    The purpose of this study is to investigate the influence of extremely low levels of oxygen and nitrogen partial pressure, PO2 and PN2 in 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 PO2 and PN2, 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 observed at welding in ≤4.1 Pa of PO2, a significant arc voltage drop with increase of PN2 is observed at welding in 0.4-16.9 Pa of PN2, and oxygen appears to inhibit this arc voltage drop. The surface of weld metal and heat affected zone (HAZ) in the atmosphere of 0.1 Pa of PO2 and 0.4 Pa of PN2 remains bright. The surface discoloration is observable slightly on weld metal and HAZ in the atmosphere of 1.1 Pa of PO2, and with increase of PO2 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 PN2 ≤ 16.9 Pa with 0.1 Pa of PO2. The nitrogen content [N] in the weld metal increases linearly with increase of √PN2, 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 the weld metal increases linearly with increase of √PO2 and shows same relations as [N], although the values of [O] in the weld metals fluctuate more than [N]. (author)

  6. 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

    In this article, laboratory tests are demonstrated that systematically accesses the critical gap distance when welding CMn 2.13 mm steel with a 2.6 kW CO2 laser, combined with a MIG energy source. In the work, the welding speed is varied at gap distances from 0 to 0.8 mm such that the limits 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...

  7. Towards real time diagnostics of Hybrid Welding Laser/GMAW

    Energy Technology Data Exchange (ETDEWEB)

    McJunkin, T. R.; Kunerth, D. C.; Nichol, C. I. [Idaho National Laboratory, Idaho Falls, ID 83415-3570 (United States); Todorov, E.; Levesque, S. [Edison Welding Institute, Columbus, OH (United States)

    2014-02-18

    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.

  8. 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.

  9. Joining of Cu-Mg-Mn Aluminum Alloy with Linear Friction Welding

    Directory of Open Access Journals (Sweden)

    A. Medvedev

    2014-07-01

    Full Text Available Al-Cu-Mg-Mn alloy samples were joined together with linear friction welding in two conditions, as is, without pretreatment, and after etching the welding interface. The effect of the welding interface condition was evaluated based on microstructure analysis, microhardness and tensile testing at room temperature. Also, the temperature distribution during welding was estimated with an analytical one-dimensional heat conduction model of the welding process and welding process data

  10. Effects of high frequency current in welding aluminum alloy 6061

    Science.gov (United States)

    Fish, R. E.

    1968-01-01

    Uncontrolled high frequency current causes cracking in the heat-affected zone of aluminum alloy 6061 weldments during tungsten inert gas ac welding. Cracking developed when an improperly adjusted superimposed high frequency current was agitating the semimolten metal in the areas of grain boundary.

  11. Study of residual stress simulation of laser welding

    International Nuclear Information System (INIS)

    In this study, simple heat source model was applied in heat transfer and residual stress analyses of laser welding. The mechanism of laser welding is too complicated for temperature distribution to be obtained. Various heat input models have been proposed to describe the laser weld profiles, thermal absorption characteristics, and temperature distributions. In the first place, we have selected one of the models, the combination of a point and a line heat sources. Despite the model's simplicity, it is able to describe a laser weld profile. Single pass laser weld joint was made with high power CO2 laser welding in order to obtain weld profiles and residual stress distributions. These data were applied to examine the results of the analyses. In the heat transfer analysis, almost the same weld profile was able to be obtained. Additionally, welding residual stress analysis was carried out based on these data. As a result, residual stress distributions near the weld metal were almost the same as measured ones. (author)

  12. Process Analysis of Titanium Laser Welding%钛合金激光焊接工艺分析

    Institute of Scientific and Technical Information of China (English)

    王中林

    2012-01-01

    钛合金广泛应用于工业生产,TC系列钛合金是其中应用最广的一种.以TC系列钛合金作为典型,对其进行激光焊接性能分析,并针对焊接性能开展激光焊接工艺分析,对TC系列及其他类型钛合金激光焊接加工具有一定现实指导意义.%Titanium alloys are widely used in industrial production, the TC series of titanium alloy is one of the most widely used materials. Titanium as a typical TC series, start from the structure of matter, and then its performance analysis of laser welding, laser welding technology and welding performance to carry out with some guidance and practical significance for TC series and other types of titanium laser welding process.

  13. Weld embrittlement in a silicide-coated tantalum alloy

    International Nuclear Information System (INIS)

    Certain weld configurations of Ta-10W alloy can become severely embrittled after a silicide coating procedure. The source of this embrittlement is shown to be a result of pronounced carbide precipitation at grain boundaries in the fusion zones of the weld. The source of carbon is the nitrocellulose lacquer that is contained in the slurry of metal powders used to provide the silicide coating. In certain weld configurations, the nitrocellulose can flash ahead of the remainder of the coating mixture, and the carbon constituent can diffuse down grain boundaries in subsequent thermal treatments. It is demonstrated that this embrittlement can be avoided if lacquers other than nitrocellulose are used or if weld configurations containing tight-fitting overlaps are avoided. The possible role of hydrogen embrittlement is also discussed. (author)

  14. X-ray residual stress measurement on weld metal of nickel based alloy

    International Nuclear Information System (INIS)

    Residual stress on the weld metal of nickel based alloy was evaluated through x-ray diffraction and metallurgical study of the microstructure. Weld metal specimens were prepared from Alloy182 (JIS DNiCrFe-3) and Alloy132 (JIS DNiCrFe-1J) deposited on a steel plate. X-ray diffraction results show a strong [100] preferred orientation nearly normal to the surface of the weld metal. Crystallographic consideration predicts that dominant 311 diffractions appear around 25.2 and 72.5 degrees of ψ angle. For each diffraction, the peak shift was measured at the ψ angle showing the maximum diffraction intensity, using the side-inclination method (ψ-goniometer method) with a Mn x-ray tube and a PSPC (position sensitive proportional counter). The residual stress was determined by the peak shifts according to the two tilt method. The x-ray stress constant, K, on Alloy182 was determined experimentally. The depth profile of the residual stress was measured on the ground specimens with and without laser peening. Tensile residual stress due to the grinding work is observed in the surface layer of the unpeened specimen; however it changes to compressive after laser peening. The overall behavior of the depth profile of laser peened material agrees well with that of Alloy600 base metal measured in the previous studies, where the compressive residual stress with several hundred MPa at the surface gradually decreases and reaches to around 0 MPa at the depth of about 1 mm. (author)

  15. Fatigue life estimation of ultrasonic spot welded Mg alloy joints

    International Nuclear Information System (INIS)

    Highlights: • Fatigue life test of USWed similar Mg alloy was investigated. • USW joints exhibited a superior fatigue life compared with other welding processes. • Life prediction model agreed fairly well with the obtained experimental results. • The fatigue failure mode changed with decreasing cyclic load level. - Abstract: Lightweight magnesium alloys are increasingly used in automotive and other transportation industries for weight reduction and fuel efficiency improvement. The structural application of magnesium components requires proper welding and fatigue resistance to guarantee their durability and safety. The objective of this investigation was to identify failure mode and estimate fatigue life of ultrasonic spot welded (USWed) lap joints of an AZ31B-H24 magnesium alloy. It was observed that the solid-state USWed joints exhibited a superior fatigue life compared with other welding processes. Fatigue failure mode changed from interfacial failure to transverse-through-thickness crack growth with decreasing cyclic load level, depending on the welding energy. Fatigue crack initiation and propagation occurred from both the notch tip inside the faying surface and the edge of sonotrode indentation-footprints due to the presence of stress concentration. A life prediction model for the spot welded lap joints developed by Newman and Dowling was adopted to estimate the fatigue lives of the USWed magnesium alloy joints. The fatigue life estimation, based on the fatigue crack growth model with the global and local stress intensity factors as a function of kink length and the experimentally determined kink angle, agreed fairly well with the obtained experimental results

  16. Dynamic process of angular distortion between aluminum and titanium alloys with TIG welding

    Institute of Scientific and Technical Information of China (English)

    WANG Rui; LIANG Zhen-xin; ZHANG Jian-xun

    2008-01-01

    The dynamic process of welding angular distortion in the overlaying welding of 5A12 aluminum alloy and BT20 titanium alloy was investigated. Information of dynamic distortion was got via self-made welding dynamic measuring system. Research results show that the characteristics of dynamic distortions at various positions of the plate edge parallel to the weld of 5A12 and BT20 alloy are different. Comparison between 5A12 and BT20 alloy shows that transverse shrinkage and downward longitudinal bending are main factors influencing the dynamic angular distortion processes of 5A12 and BT20 alloy under welding heat input of 0.32 kJ/mm. The angular distortion of 5A12 alloy is completely inversed with welding heat input increasing to 0.4 kJ/mm, and the position of weld center and buckling distortion become the primary factors.

  17. Three thermal analysis models for laser, GMAW-P and Iaser+GMAW-P hybrid welding

    Institute of Scientific and Technical Information of China (English)

    XU Guoxiang; WU Chuansong; QIN Guoliang; WANG Xuyou; LIN Shangyang

    2009-01-01

    The temperature fields and the weld pool geometries for laser + GMA W-P hybrid welding, laser welding and pulsed gas metal arc welding (GMAW-P) are numerically simulated in quasi-steady state by using the developed heat source models, respectively. The calculated weld cross-sections of the three types of welding processes agree well with their respective measured results. Through comparison, it is found that the temperature distribution of laser+ GMAW-P hybrid welding possesses the advantages of those in both laser and GMA W-P welding processes so that the improvement of welding productivity and weld quality are ensured.

  18. Microstructure and mechanical properties of high-strength TC11 titanium alloy joints welded by laser beam%TC11高强钛合金激光焊接接头的显微组织与力学性能

    Institute of Scientific and Technical Information of China (English)

    虞鸿江; 范如意; 黄坚; 潘丽华; 王勇

    2015-01-01

    采用光纤激光进行TC11钛合金对接焊接,分析焊接接头的显微组织和力学性能。结果表明,TC11钛合金焊缝为α′马氏体组织,从母材至熔合线组织由α+β逐渐向α′转变;随着热输入量的增加,焊缝柱状晶尺寸变大,马氏体分布更加密集交错,同时热影响区宽度增加,粗晶区晶粒尺寸变大;2 mm厚TC11钛合金在焊接速度2.0 m/min、激光功率2.8~3.2 kW的工艺参数下得到的焊缝成形良好;焊缝硬度高于母材硬度,并随热输入量的增加而增大;焊接接头抗拉强度达到母材的97%以上,塑性明显下降,低于母材的50%,焊缝断口形貌为低塑性沿晶断裂特征。%The titanium alloy TC11 was welded by fiber laser beam, the microstructure and mechanical properties of the laser welded TC11 joints with different welding parameters were studied. The results show that the microstructure of weld metal consists ofα′ martensite.From the base metal to fusion line, the microstructure evolves fromα+β phase toα′ phase. With increasing the heat input, the size of columnar dendrites increases, the distribution ofα′ martensite becomes more dispersive, the width of HAZ and grain size in coarse grain zone increase. Under the welding speed of 2.0 m/min and laser power of 2.8−3.2 kW, the sound welds of 2 mm thick TC11 alloy were obtained. The hardness of the weld increases with increasing the heat input. The tensile strength of welded joints reaches at least 97% of that of the base metal, while the plasticity decreases significantly. The fracture topography of welded joints shows brittle fracture character.

  19. Laser welding of plastics transparent to near-infrared radiation

    Science.gov (United States)

    Sato, Kimitoshi; Kurosaki, Yasuo; Saito, Takushi; Satoh, Isao

    2002-06-01

    This paper deals with a development of laser welding of colored plastics. Welding of thermoplastics using near-IR lasers has been seen in wide industrial application. Most of thermoplastics are transparent to near-IR laser. Particular characteristic of near-IR laser radiation has the ability to heat the interface between the transparent part and absorbent one colored with pigments. However, it is difficult to weld a pair of transparent materials by a laser beam, since there is no absorption region within them. In this paper, the influence of near-IR transparent plastics on the yield strength of their weldments has been studied: various colored plastics transparent to diode laser radiation were tested as the welding material. The heat transfer within a welding system was also analyzed and assessed the appropriate absorptivity and transmittance of overlapping colored plastic.

  20. Laser Welding Of Contoured Thin-Wall Housings

    Science.gov (United States)

    Spiegel, Lyle B.; Oleksiak, Carl E.

    1991-01-01

    Superalloy parts joined with less distortion. Carbon dioxide laser beam directed by optics in numerically controlled robot arm welds shell-type turbopump housings having complicated shapes. 5-kW laser, following single programmed three-dimensional pass, produces high-quality, full-penetration weld pass in age-hardenable nickel superalloy. Operator easily programs robot by using teaching pendant to track weld joint and keeps laser focused on workpiece while following contour of shell. Shells welded in rapid succession, with minimal change in setup for each.

  1. Temperature field simulation of laser-TIG hybrid welding

    Institute of Scientific and Technical Information of China (English)

    陈彦宾; 李俐群; 方俊飞; 封小松; 吴林

    2003-01-01

    The three-dimensional transient temperature distribution of laser-TIG hybrid welding was analyzed and simulated numerically. Calculations were based on a finite element model, in which the physical process of hybrid welding was studied and the coupling effect of the laser and arc in the hybrid process was fully considered. The temperature fields and weld cross-sections of the typical welding parameters are obtained using present model. The calculation results show that the model can indicate the relationship of energy match between laser and arc to joints cross-sections objectively, and the simulation results are well agreed with the experimental results.

  2. Ultrashort pulsed fiber laser welding and sealing of transparent materials.

    Science.gov (United States)

    Huang, Huan; Yang, Lih-Mei; Liu, Jian

    2012-05-20

    In this paper, methods of welding and sealing optically transparent materials using an ultrashort pulsed (USP) fiber laser are demonstrated which overcome the limit of small area welding of optical materials. First, the interaction of USP fiber laser radiation inside glass was studied and single line welding results with different laser parameters were investigated. Then multiline scanning was used to obtain successful area bonding. Finally, complete four-edge sealing of fused silica substrates with a USP laser was demonstrated and the hermetic seal was confirmed by water immersion test. This laser microwelding technique can be extended to various applications in the semiconductor industry and precision optic manufacturing. PMID:22614601

  3. Research on CMT welding of nickel-based alloy with stainless steel

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Cold Metal Transfer (CMT) welding technique is a new welding technique introduced by Fronius company. CMT welding of nickel-based alloy with stainless steel was carried out using CuSi3 filler wire in this paper. Effects of welding parameters, including welding current, welding speed, etc, on weld surface appearance were tested. Microstructure and mechanical properties of CMT weld were studied. The results show that the thickness of interface reaction layer of the nickel-based alloy is 14.3μm, which is only 4.33% of base material. The weld is made up of two phases,α-copper and iron-based solid solution. Rupture occurs initially at the welded seam near the edge of stainless steel in shear test. The maximum shear strength of the CuSi3 welded joint is 184.9MPa.

  4. Laser diode transmission welding of polypropylene: Geometrical and microstructure characterisation of weld

    International Nuclear Information System (INIS)

    This study concerns the welding of polypropylene with diode laser using the overlap joint method. The influence of process parameters, both the laser power (20-40 W) and the welding speed (3-6 mm/s) on the geometry and the microstructure of the weld zone were investigated. The objective of this work is to evaluate the effects of selected welding parameters on the seam geometry, defects and material crystallinity. The out coming results help with the choice of the welding parameters that can satisfy the demands of users and consumers with respect of good quality and safety of the process. Microscopic observations performed on the cross section of the joining area reveal that the increase of the laser power and the decrease of the scanning speed lead to a larger volume of the weld zone with a more important depth penetration. The geometry of the weld zone is elliptic. Microscopic Fourier transform infrared (FTIR) spectroscopy method shows that diode laser welding induces thermal degradation of the polypropylene by random chain scissions. An increase of the crystallinity along the cross section of the welding joint was observed with a maximum reached in the centre of the weld zone. Some process parameters produced the occurrence of a void due to the thermal decomposition and the vaporisation of the polypropylene.

  5. A study on laser welding deformation of 304 stainless steel

    International Nuclear Information System (INIS)

    In heavy industries, 304 austenitic stainless steel is the most popular material which is used for nuclear equipment, chemical vessels, vacuum vessels and so on. On the fabrication, not only a joint quality but also severe dimensional accuracy is required. To keep dimensional accuracy, considerable cost and efforts are requested, because the welding deformation of austenitic stainless steel is deeply depended on the physical properties of material itself. To decrease welding deformation, big jigs or water cooling method are commonly used which lead to the high cost. In general, the fusion welding by high energy density heat source results in less distortion. Today, laser welding technology has grown up to the stage that enables to weld thick plate with small deformation. The researches of welding deformation have been conducted intensively, but they are mainly concerned for arc welding, and studies for laser welding are very few. In this report, the authors will show the test results of deformation behavior in laser welding of 304 stainless steel. Also, they will discuss the deformation behavior comparing to that in arc welding. The main results of this study are as follows. 1. The angular distortion of laser welding can be unified by heat input parameter (Hp) which is used for arc welding deformation. 2. The angular distortion are same under the condition of Hp3 in spite of different welding method, however under the condition of Hp>6-9 J/mm3 the angular distortion is quite different depending on the power density of welding method. 3. Pure angular distortion seemed to complete just after welding, but following longitudinal distortion took place for long period. 4. The critical value of longitudinal distortion can be estimated from heat input parameter. The transverse deformation can be also estimated by heat input parameter. (author)

  6. Electrochemical Testing of Gas Tungsten ARC Welded and Reduced Pressure Electron Beam Welded Alloy 22

    Energy Technology Data Exchange (ETDEWEB)

    S. Daniel Day; Frank M.G. Wong; Steven R. Gordon; Lana L. Wong; Raul B. Rebak

    2006-05-08

    Alloy 22 (N06022) is the material selected for the fabrication of the outer shell of the nuclear waste containers for the Yucca Mountain high-level nuclear waste repository site. A key technical issue in the waste package program has been the integrity of the container weld joints. The currently selected welding process for fabricating and sealing the containers is the traditional gas tungsten arc welding (GTAW) or TIC method. An appealing faster alternative technique is reduced pressure electron beam (RPEB) welding. It was of interest to compare the corrosion properties of specimens prepared using both types of welding techniques. Standard electrochemical tests were carried on GTAW and RPEB welds as well as on base metal (non-welded) to determine their relative corrosion behavior in simulated concentrated water (SCW) at 90 C (alkaline), 1 M HCI at 60 C (acidic) and 1 M NaCl at 90 C (neutral) solutions. Results show that for all practical purposes, the three tested materials had the same electrochemical behavior in the three tested electrolytes.

  7. Electrochemical Testing of Gas Tungsten Arc Welded and Reduced Pressure Electron Beam Welded Alloy 22

    International Nuclear Information System (INIS)

    Alloy 22 (N06022) is the material selected for the fabrication of the outer shell of the nuclear waste containers for the Yucca Mountain high-level nuclear waste repository site. A key technical issue in the waste package program has been the integrity of the container weld joints. The currently selected welding process for fabricating and sealing the containers is the traditional gas tungsten arc welding (GTAW) or TIG method. An appealing faster alternative technique is reduced pressure electron beam (RPEB) welding. It was of interest to compare the corrosion properties of specimens prepared using both types of welding techniques. Standard electrochemical tests were carried on GTAW and RPEB welds as well as on base metal (non-welded) to determine their relative corrosion behavior in simulated concentrated water (SCW) at 90 C (alkaline), 1 M HCl at 60 C (acidic) and 1 M NaCl at 90 C (neutral) solutions. Results show that for all practical purposes, the three tested materials had the same electrochemical behavior in the three tested electrolytes

  8. Adaptive feedback beam shaping of the CO2 welding laser

    Czech Academy of Sciences Publication Activity Database

    Jedlička, Petr; Mrňa, L.; Šarbort, M.; Řeřucha, Šimon

    Bellingham: SPIE, 2010, 77890V: 1-8. ISBN 978-0-8194-8285-3. [Laser Beam Shaping XI. San Diego (US), 02.08.2010] R&D Projects: GA MPO 2A-3TP1/113 Institutional research plan: CEZ:AV0Z20650511 Keywords : laser beam welding * adaptive optics * laser welding control * light emission monitoring Subject RIV: BH - Optics, Masers, Lasers

  9. Butt-welding Residual Stress of Heat Treatable Aluminum Alloys

    Institute of Scientific and Technical Information of China (English)

    C.M. Cheng

    2007-01-01

    This study, taking three types of aluminum alloys 2024-T351, 6061-T6 and 7075-T6 as experimental materials, conducted single V-groove GTAW (gas tungsten arc welding) butt-welding to analyze and compare the magnitude and differences of residual stress in the three aluminum alloys at different single V-groove angles and in restrained or unrestrained conditions. The results show that the larger the grooving angle of butt joint, the higher the residual tensile stress. Too small grooving angle will lead to dramatic differences due to the amount of welding bead filler metal and pre-set joint geometry. Therefore, only an appropriate grooving angle can reduce residual stress. While welding, weldment in restrained condition will lead to a larger residual stress. Also, a residual stress will arise from the restraint position. The ultimate residual stress of weldment is determined by material yield strength at equilibrium temperature. The higher the yield strength at equilibrium temperature, the higher the material residual stress. Because of its larger thermal conductivity, aluminum alloy test specimens have small temperature differential. Therefore, the residual tensile stress of all materials is lower than their yield strength.

  10. A comparative study on fiber laser and CO2 laser welding of Inconel 617

    International Nuclear Information System (INIS)

    Highlights: • The difference change of weld bead geometry occurs in fiber and CO2 laser welding. • The melting efficiency in fiber laser and CO2 laser welding is analyzed. • Secondary dendrite arm spacing and cooling rate in two laser weldings is studied. • The second phase in two laser welding with different heat input is investigated. - Abstract: A comparative study on the influence of fiber laser welding (FLW) and CO2 laser welding (CLW) on the weld bead geometry and the microstructure of fusion zone (FZ) of Inconel 617 was investigated. In CLW joints, the weld bead geometry is Y-type shape. In FLW joints, the weld bead geometry transforms from Y-type to I-type with the decrease of the heat input. The minimum heat input required to achieve the full penetration of the weldment in FLW is lower than the CLW. The melting efficiency in FLW is higher than that in CLW. From the top to the root regions, the secondary dendrite arm spacing (SDAS) in fiber laser welded FZ undergoes a smaller change than that in CO2 laser welded FZ. The elements of Ti, Mo, Cr and Co segregate into the interdendritic regions both in FLW and CLW process. The second phases in CLW with the highest input of 360 J/mm are much larger and more than ones in FLW with the highest heat input of 210.5 J/mm

  11. Development of multifunction laser welding head (3). Surface inspection technique by laser-ultrasonics

    International Nuclear Information System (INIS)

    Multifunction laser welding head has been developed. The head is able to perform not only underwater laser welding as repair, but also laser peening as preventive maintenance and laser ultrasonic testing as inspection. For inspection with multifunction laser welding head, a new method of visualized weld defects in water by laser-ultrasonics has developed. To detect and visualize a surface of weld metal with welding bead, the authors have developed a new detection method by leaky wave induced by interaction with surface acoustic waves and defects. Furthermore, developing Synthetic Aperture Focus Technique (SAFT) for visualized inspection surface 2-dimensionally, we achieve the inspection result alike Penetrant Testing (PT) despite underwater environment with multifunction laser welding head. (author)

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

    International Nuclear Information System (INIS)

    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)

  13. Inspection of thick welded joints using laser-ultrasonic SAFT.

    Science.gov (United States)

    Lévesque, D; Asaumi, Y; Lord, M; Bescond, C; Hatanaka, H; Tagami, M; Monchalin, J-P

    2016-07-01

    The detection of defects in thick butt joints in the early phase of multi-pass arc welding would be very valuable to reduce cost and time in the necessity of reworking. As a non-contact method, the laser-ultrasonic technique (LUT) has the potential for the automated inspection of welds, ultimately online during manufacturing. In this study, testing has been carried out using LUT combined with the synthetic aperture focusing technique (SAFT) on 25 and 50mm thick butt welded joints of steel both completed and partially welded. EDM slits of 2 or 3mm height were inserted at different depths in the multi-pass welding process to simulate a lack of fusion. Line scans transverse to the weld are performed with the generation and detection laser spots superimposed directly on the surface of the weld bead. A CCD line camera is used to simultaneously acquire the surface profile for correction in the SAFT processing. All artificial defects but also real defects are visualized in the investigated thick butt weld specimens, either completed or partially welded after a given number of passes. The results obtained clearly show the potential of using the LUT with SAFT for the automated inspection of arc welds or hybrid laser-arc welds during manufacturing. PMID:27062646

  14. Friction Stir Welding of a Thick Al-Zn-Mg Alloy Plate

    Science.gov (United States)

    Buchibabu, V.; Reddy, G. M.; Kulkarni, D.; De, A.

    2016-03-01

    Al-Zn-Mg alloys are widely used as structural materials due to high strength-to-weight ratio and impact toughness. As fusion welds in these alloys commonly face hot cracking and macro porosity, friction stir welding is increasingly becoming the preferred recourse. We report here a detailed experimental study on friction stir welding of a specific Al-Zn-Mg alloy with its chemical compositions close to AA7039. The effect of tool rotational speed and welding speed on the weld profile, joint microstructure, and mechanical properties is studied extensively. The results show sound weld profiles and joint properties within the selected range of process conditions. Within the selected range of welding conditions, the welds made at a tool rotational speed of 350 rpm and welding speed of 3 mm/s have showed joint structure, tensile, and impact toughness properties fairly close to that of the base material.

  15. Laser welding control by monitoring of plasma

    Czech Academy of Sciences Publication Activity Database

    Chmelíčková, Hana; Šebestová, Hana; Havelková, Martina; Řiháková, Lenka; Nožka, Libor

    Bellingham : SPIE, 2013 - (Lehmann, P.; Osten, W.; Albertazzi, A.), "87882P-1"-"87882P-8" ISBN 978-0-8194-9604-1. ISSN 0277-786X. - (Proceedings of SPIE. 8788). [Optical Measurement Systems for Industrial Inspection /8./. Munich (DE), 13.05.2013-16.05.2013] R&D Projects: GA TA ČR TA01010517 Institutional support: RVO:68378271 Keywords : laser welding * on-line monitoring * defect detection * parameters control * temperature distribution * confocal microscope Subject RIV: JB - Sensors, Measurment, Regulation

  16. Picosecond laser welding of similar and dissimilar materials.

    Science.gov (United States)

    Carter, Richard M; Chen, Jianyong; Shephard, Jonathan D; Thomson, Robert R; Hand, Duncan P

    2014-07-01

    We report picosecond laser welding of similar and dissimilar materials based on plasma formation induced by a tightly focused beam from a 1030 nm, 10 ps, 400 kHz laser system. Specifically, we demonstrate the welding of fused silica, borosilicate, and sapphire to a range of materials including borosilicate, fused silica, silicon, copper, aluminum, and stainless steel. Dissimilar material welding of glass to aluminum and stainless steel has not been previously reported. Analysis of the borosilicate-to-borosilicate weld strength compares well to those obtained using similar welding systems based on femtosecond lasers. There is, however, a strong requirement to prepare surfaces to a high (10-60 nm Ra) flatness to ensure a successful weld. PMID:25089985

  17. Microstructure and Mechanical Properties of Friction Welding Joints with Dissimilar Titanium Alloys

    OpenAIRE

    Yingping Ji; Sujun Wu; Dalong Zhao

    2016-01-01

    Titanium alloys, which are important in aerospace application, offer different properties via changing alloys. As design complexity and service demands increase, dissimilar welding of the titanium alloys becomes a particular interest. Linear friction welding (LFW) is a relatively novel bond technique and has been successfully applied for joining titanium alloys. In this paper, dissimilar joints with Ti-6Al-4V and Ti-5Al-2Sn-2Zr-4Mo-4Cr alloys were produced by LFW process. Microstructure was s...

  18. 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....

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

    International Nuclear Information System (INIS)

    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

  20. Modeling of transport phenomena during laser welding process

    Science.gov (United States)

    Zhou, Jun

    This dissertation, consisting of three papers, presents the results of research investigations on laser welding of zinc-coated steel sheets and three-dimensional laser keyhole welding by numerical analysis. In the first paper, the mathematical model and numerical techniques are developed to simulate the keyhole formation, zinc vapor formation and zinc vapor escaping processes. In the study, the keyhole is used as an effective way to vent the high-pressure zinc vapor generated at the interface between the two zinc-coated metal sheets. The interaction between the weld pool and the escaping zinc vapor is investigated. It is the first comprehensive mathematical model for laser welding of zinc-coated steel sheets. In the second paper, the aforementioned model is employed to study the defect formation mechanisms in laser welding of zinc-coated steel sheets. Welding defects, such as voids at the root of welded metal, the undercut on the top surface and the bubbles trapped in the weld pool are simulated. The reasons causing these welding defects are given through the studies of the zinc vapor-weld pool interaction and the fluid flow and heat transfer during the keyhole collapse and metal solidification processes. In the third paper, the aforementioned stationary 2-D model is extended to modeling a 3-D moving laser keyhole welding process. The heat transfer and fluid flow in the welding pool around the keyhole are calculated. Also, the laser induced plasma inside the keyhole due to the Inverse Bremsstrahlung absorption is considered to calculate the temperature distribution inside the keyhole. Energy distribution inside the keyhole is computed by considering the Fresnel absorption and multiple reflections phenomena.