Characterisation of solidification cracking in pulsed Nd:YAG laser welding of 2024 aluminium alloy

Aluminium alloy AA2024 is one of the most susceptible alloys to solidification cracking. The influence of Nd:YAG laser welding parameters on cracking severity of AA 2024 alloy was studied. Welding was performed in two modes: single spot welding and overlap spot welding. In single spot welding mode, the formation of columnar zone increases cracking severity in the fusion zone. In overlap spot welding mode, the solidification cracks were characterised as: cracks propagated from previous spot, cracks initiated from the fusion line with the previous spot, and cracks initiated from the fusion line with the base metal. It was established that in comparison there is very limited tendency for initiation of new cracks from the fusion line with the weld metal of a previous spot.