Fine Grains Reduce Cracking Susceptibility During Solidification: Insights from Phase-Field Simulations

Hot cracking is commonly observed in welding and metal additive manufacturing processes. In this work, the effects of grain size on cracking susceptibility during solidification were investigated using two-dimensional phase-field simulations. Al-3.0 wt.% Cu alloy was chosen as an example, and the grain size was controlled by adjusting the primary dendritic arm spacing. It was found that fine grains can significantly reduce liquid channel segregation and facilitate earlier coalescence of adjacent grains to resist cracking. Moreover, the cracking susceptibility indexes were predicted from the microstructurally complex phase-field data, showing good agreement with the simulated liquid channel morphology and segregation. Both the liquid channel characteristics and cracking susceptibility index demonstrated how grain refining reduces cracking susceptibility during solidification in welding and metal additive manufacturing processes.