Product Code: ICAL05_2209

Solidification Rate in Laser Welding and Its Influence on Aluminum Alloy 2024 Weld Quality
Authors:
Bin Hu, Netherlands Institute for Metals Research; Delft Netherlands
I. Richardson, Delft University of Technology; Delft Holland Netherlands
Presented at ICALEO 2005

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 of different thicknesses. 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 thickness show, interestingly, that the cooling rates of the welding process have a significant influence on the fusion zone microstructure. The micro-hardness of welds varied from 70 to 85% in comparison with the base material. Thermo-couple temperature measurements together with numerical calculations were used to obtain the cooling rates of the welds at the solidification temperature range. The relationship between the solidification rates and the dendritic arm spacing, width of arm branches and the micro-hardness were examined. It was concluded that the faster the solidification rate in laser welding, the better the weld strength and ductility.