Mathematical Modeling of Fusion and Solidification in Laser Welding and Evaluation of Hot Cracking Susceptibility

概要

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It is acknowledged that a pulsed laser spot weld is subjected to rapid solidification and fast cooling rates. It is particularly difficult but important to determine various solidification parameters in terms of development of novel microstructure, prevention of welding defects and improvement in mechanical properties. Therefore, in this study, a heat-conduction and solidification model considering the effect of latent heat was developed to provide a reasonably good knowledge of rapid melting and solidification behaviour in such a spot weld. It was confirmed that the latent heat would greatly affect thermal histories during solidification and growth rates of cellular dendrite tips in solidifying weldpool. The model could be utilized to reduce cracking in a laser spot welding of crack susceptible alloys by giving a proper thermal cycle during solidification. The effect of predicted thermal history was verified by experiments and the validity of model was confirmed in conduction mode fusion welding.
大阪大学の論文