Laser Beam Welding of aluminum alloys

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The present investigation was mainly concerned with characteristics of autogeneous laser butt welding of 2 mm thickness nonheat treatable AA5052-H12, AA5083-H12 and 2 mm, 3 mmthickness heat treatable AA6061-T6 aluminum alloys. The effect of laser welding parameters,surface cleaning, filler wire addition, and backing strip on quality of laser welded joints was clarifiedusing 5 kW CO 2 laser machine.It was found that all the investigated alloys showed tendencies for porosity and solidification cracking,particularly, at high welding speed ( ≥ 4 m/min). Porosity was prevented by accurate cleaning of thebase metal prior to welding and optimizing the flow rate of argon shielding gas. Solidification crackingwas avoided through two different approaches. The first one is based on the a ... ddition of filler metalas reported in other research works. The other new approach is concerned with autogeneouswelding using a backing strip from the same base metal, and this could be applicable in production.Preventing solidification cracking in both cases was related mainly to a considerable decrease in thestress concentration at the weld metal center as a result of improving the fusion zone profile.The implementation of the new approach could help in producing weldments with a better quality dueto the absence of the filler metal, which is known as a source for hydrogen-related porosity. It canalso have a positive economic aspect concerning the manufacturing cost since welding is donewithout the addition of filler metal. Not only quality and economic positive aspects could beachieved, but also high productivity is another feature since high quality autogeneous weldments wereproduced with high welding speed, 6 m/min. Hardness measurements and tensile test of AA6061 alloy welds indicated a remarkable softening of the fusion zone due to dissolution of the strengthening precipitates, and this was recovered by aging treatment after welding. For alloys AA5052 and AA5083, softening of the fusion zone due to theloss of its work-hardened condition was much less in comparison with AA6061 alloy.

Date: 2023-04-10     hits: 486    Return