CO2 Laser Welding of Aluminum Alloys (No.1)-Welding of Aluminum Alloys using CO2 Laser Beam in combination with MIG Arc.

Abstract

Aluminum alloys were welded using 10 kW CO2 laser system. Combination of TIG or MIG arc welding with laser welding was tried in bead-on-plate welding experiments in which the molten pool formed by arc welding ran ahead of the laser beam . As the results of experiments, combination with MIG-DCEP arc welding was selected. A5083 and A6061 aluminum alloys were welded using A5356 filler wire in bead-on-plate welding in the flat position. It was concluded that combination of MIG arc welding seemed to be promising from the view point of bead formation and increase of absorption of the beam energy . But occurrence of large blow-holes or voids remained an important problem for further research. Key words:Welding, Aluminum alloy, CO2 laser beam, Combination with arc welding, MIG welding, Bead formation IntroductionIndustrial applications of high power beams in welding such as electron beam welding (EBW), CO2 laser beam welding (CO2 LBW) and YAG laser beam welding (YAG LBW) are continuously increasing in many industries. In case of CO2 LBW, development of higher power equipment such as 10 to 25 kW equipment is expected to increase industrial applications of LBW.Laser beam welding of aluminum alloys has been studied for more than several years, but the authors have not heard of a successful industrial application of high power CO2 LBW of a thick plate of aluminum alloys. The authors conducted a preliminary experiment using a 10 kW CO2 laser and experienced several difficulties such as ;(1) Aluminum alloys had a higher reflectivity to the CO2 laser beam than ordinary mild steel. Absorption of the laser beam into solid aluminum was not only low but sometimes erratic, and reflected laser beams caused undesirable damages to optics parts.(2) Bead formation in welding of some aluminum alloys was irregular, and sometimes heavy sputtering occurred.A rough surface bead and deep undercuts were formed.(3) Large blow-holes and weld cracks were found in welding of some aluminum alloys.Combination of inert gas arc welding (TIG or MIG) with high power CO2 LBW in welding of aluminum alloys was tried to overcome these difficulties .The idea of combining LBW with arc welding was not new and was tried by several researchers in the past . N. Abe et al. also reported recently on the effect of laser irradiation on CO2 gas arc welding beads') . But they have not tried welding of aluminum alloys with an intentional help of TIG or MIG arc welding.In the following experiments of welding of aluminum alloys, the authors combined TIG or MIG arc welding with CO2 LBW on the following ideas;') (1) It was reported that molten metal surfaces in general had lower reflectivity than solid metal surfaces').When a CO2 laser beam impinges onto a molten aluminum pool, it is expected that more percentage of the laser beam is absorbed into aluminum and the depth of penetration is increased.(2) It is expected that wetting of the molten metal and the solid base metal is improved and formation of the undercut is suppressed by moving a large molten metal pool fo...

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