Simulation of microstructure evolution process in the melt pool formed by laser cladding with a multi-scale model

Abstract

The microstructure directly determines the alloys’ mechanical performance, therefore understanding the microstructure evolution process is essential to controlling the cladding layer’s mechanical performance. A multiscale model in three dimensions is developed to evaluate the complicated microstructure evolution in the melt pool formed during the laser cladding process. The model consists of two parts: the FVM to calculate the evolution of the melt pool at the macroscopic scale, and the simulation of the solidification of grains at the microscopic scale by the CA. The high consistency with the experimental results proves the accuracy of the multiscale model in three dimensions. Using the developed model, the solid-liquid phase transformation process of the whole melt pool is studied and the impact of the variations of scanning speed on the microstructure is analyzed. The grain size decreases and the “laser-grain angle” increases with an increase in scanning speed. This study explains the evolution of the microstructure, which helps to customize the cladding layer’s microstructure.