Abstract

A coupled temperature-microstructure model was developed in order to simulate the evolution of the microstructure in the heat-affected zone during two-pass gas-metal arc welding. The model is developed to serve the steel industry’s need to evaluate the weldability of new steel grades. Heat transfer and heat input models were used for modelling the arc welding and the temperature changes in the heat-affected zone. A microstructure model was fully coupled with the temperature model, including latent heat of transformation as well as the dependence of thermophysical properties on temperature and phase fractions. The microstructure model simulates phase transformations and grain growth including a simplified model for the effect of fine particles. The modeled temperature paths are in good agreement with the measured ones. The final phase fractions and grain size distribution obtained from the model correspond to the actual microstructure and the model predicts the shapes of the heat-affected zone and fusion zone with relatively good accuracy.