Aluminium alloy 2024 is one of important heat treatable aluminium alloys with its strength gained from the precipitation hardening. Experiments were conducted on Nd:YAG laser keyhole welding of AA2024(T3) sheet. It was found that the fusion zone of the weld becomes the weakest zone after welding due to the precipitate dissolution. The results obtained from the samples of different welding conditions show, interestingly, that the cooling rates of the welding process have a significant influence on the fusion zone microstructure. Numerical calculations were used to obtain the cooling rates of the welds at the solidification temperature range. The relationships between the solidification rates and the dendritic arm spacing, width of arm branches were examined. It was concluded that the faster the solidification rate in laser welding, the better the weld strength and ductility.

Topics
Lasers, Alloys, Materials heat treatment, Mechanical properties, Welding
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© 2005 Laser Institute of America.
2005
Laser Institute of America
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