A multi-scale approach to simulate solidification structure evolution and solute segregation in a weld pool

During welding, work-pieces are melted to form a weld pool and are joined upon solidification. The quality of the welded product is largely determined by the solidified microstructure and solute distribution. In recent years phase-field (PF) models have been developed to simulate solidification structure evolution and microsegregation. However many input data for the PF simulations are difficult to measure, including at the nanoscale the solid-liquid interfacial energy and its anisotropy, and at the macroscale the solidification conditions. In this study, an integrated scheme is proposed to resolve the above challenges by linking nanoscale molecular dynamics modelling (MD) and mesoscale front tracking (FT) modelling to the PF modelling. The approach is demonstrated in a case study in which the solidified structures and solute distributions are simulated in the weld pool for Fe-0.3wt. %C steel.