Analysis of grain growth in hybrid weld HAZ based on the coupled thermo-fluid model

Accurate calculation of thermal cycles is a prerequisite to model grain growth in the heat-affected zone（HAZ）.To improve the computation precision of thermal field and HAZ geometry,a coupled model of heat transfer and fluid flow is developed for laser+GMAW-P hybrid welding of TCS stainless steel.Utilizing computed temperature fields from the coupled model,the evolution of grain structure in the HAZ of TCS stainless steel in hybrid welding is numerically simulated by using a three dimensional Monte Carlo model.Simulation results show that more accurate HAZ grain structure can be obtained based on the coupled model of fluid flow and heat transfer,and the computed grain size distribution agrees well with the corresponding experimental results.