In-situ EBSD-DIC simulation of microstructure evolution of aluminum alloy welds

A comprehensive understanding of the dynamic evolution of weld microstructure under external loads can provide key insights for high-performance laser welding. A novel in-situ EBSD-DIC simulation method is introduced to study the microstructure evolution of laser welded aluminum alloys under uniaxial tensile action. An advanced crystal plastic finite element model (CPFEM) is developed, which combines the real microstructure, grain orientation and grain size effects. The results show that the dislocation density in columnar grain zone is higher than that in equiaxed grain zone. The continuous accumulation of dislocations in the columnar region results in a high work-hardening rate. This high work hardening rate enhances the plastic deformation capacity of the columnar crystal region, resulting in local strain concentration. Columnar zones are more prone to fracture because the high-strain region is a potential fracture site. In addition, low Angle grain boundary (LAGBs) is one of the reasons that the dislocation density of the columnar grain zone is higher than that of equiaxed grain zone during tensile process, which is conducive to dislocation slip of columnar grains. This study is a fundamental innovation in simulating the microstructure evolution of laser welding. This marks a major breakthrough in simulating the evolution of crystallographic features such as grain orientation, microstress and strain and dislocation density under external loads. This work can further provide practical guidance for “microstructure characteristics - mechanical property regulation”.