Microstructure analysis of AZ31 magnesium alloy welds using phase-field models

We use phase-field models to characterize the microstructure present in magnesium AZ31 alloy solidified under welding conditions. We focus our attention on the study of the conditions under which a columnar-to-equiaxed transition (CET) is observed in resistance spot welds. Our simulations show how the size and shape of the columnar and equiaxed regions depend on factors such as cooling rate, temperature gradient and the nature of inoculant particles. Our results are compared with experimental observations. In addition, we contrast our findings with predictions from a previously developed steady-state model for the CET.