Influence of the temperature gradient and the pulling velocity on solidification cracking susceptibility during welding: A phase field study

The influence of the temperature gradient and the pulling velocity on solidification cracking susceptibility (SCS) during welding is studied by simulating the liquid channel evolution with a quantitative phase field model. Increasing the pulling velocity or decreasing the temperature gradient increases the pressure drop from the dendrite tip to the coalescence point, leading to an increase in SCS. Decreasing the primary dendrite arm spacing (PDAS) decreases the permeability of the liquid channel and the liquid channel length at the same time, resulting in a decrease in the pressure drop and SCS when the PDAS is small. Consideration of the PDAS dependency on the temperature gradient and the pulling velocity influences the value of the pressure drop but does not change the tendency of SCS. The conclusions are also valid for an alloy with strong back diffusion. As the temperature gradient and the pulling velocity within the melt pool are controlled by process parameters, the findings from this work provide a theoretical basis to optimize process parameters to avoid solidification cracking. •With increasing temperature gradient or decreasing pulling velocity, solidification cracking susceptibility decreases.•With decreasing dendrite arm spacing, solidification cracking susceptibility decreases.•The dendrite arm spacing decreases with increasing temperature gradient or increasing pulling velocity.•Phase field simulation results support the tendency predicted from analytical models and most welding experiments.