Numerical modeling to understand liquation cracking propensity during laser and laser hybrid welding (I)

Two-dimensional thermal elasto-plastic model was established by finite element method to investigate weld heat-affected zone (HAZ) liquation cracking behavior during laser and laser-gas metal arc (GMA) hybrid welding nickel-based superalloy. Transient temperature, cooling rate, and stress and strain history were used and combined with solidification theory to analyze the mechanism of liquation cracking in the HAZ. Weld cracking mechanical driving force is related to local stress-strain development at the period of solidification, and stress and strain components were correlated along the fusion boundary of weld pool. Strain rate and weld pool geometry were demonstrated during in the stage of solidification process, which provide valuable insight into the quantitative evaluation the tendency of solidification cracking and give well understanding why laser-GMA welding is beneficial for minimizing cracking susceptibility than laser welding.