The effect of preheating on velocity of volumetric change and liquid flow rate is analyzed to develop a model for solidification cracking in successive laser weld pulses in 2024 aluminum alloy. It is shown that the lower tendency for solidification cracking with preheating can be attributed to the lower velocity of volumetric change but not the feeding rate. It is also shown there is a strong tendency for solidification crack propagation through the fusion lines between the consecutive weld spots where there is already a crack present at the fusion line. This observation can be attributed to the higher local strain rate and lower feeding rate.
