Thermal Modeling of Spot Welds

Abstract

Solidification structure and austenite decomposition in some spot welded 0.05% C-0.3% Mn steels have been studied with the aid of a numerical thermal model. The model is a one dimensional finite difference formulation, and accounts for melting, temperature dependent thermal properties, effective heat transfer in the liquid, and contact resistances. The model was used to predict solidification conditions during resolidification of the nugget. These solidification conditions were correlated with the primary dendrite spacing using available primary dendrite spacings modeling. The model was also used to predict cooling rates in the temperature regime for austenite decomposition. These cooling rates were used to interpret the underlying microstructure.