A Multi-scale Thermomechanical-Solidification Model to Simulate the Transient Force Field Deforming an Aluminum 6061 Semisolid Weld

Formation of hot cracks is strongly affected by the transient force field acting on the semisolid weld-base metal interface. This paper presents a model that numerically simulates such a transient force field as a function of welding parameters. The model consists of two modules: (1) By means of a granular model of solidification, the microstructure of the semisolid area within the weld is reconstructed in three dimensions; (2) Since the transient force field is developed through the mechanical interaction between the semisolid weld and its base metal, the mechanical response of the base metal to the solidification of the weld is then simulated through finite element analysis. The results show that changing welding parameters and welding constraints varies the transient force field. Based on the obtained force fields, a qualitative study is also conducted to predict the susceptibility of various welds to hot cracking.