Phase-Field Investigation of Solidification Cracking Probability During Laser Beam Welding

This study investigates the thermo-chemical factors contributing to solidification cracking probability during dendritic solidification of austenitic stainless steels, focusing on a quaternary (Fe-C-Cr-Ni) alloy configuration. Additionally, the model investigates the influence of local morphology, temperature distribution, dendrite orientation and micro-segregation on stress and strain localization. Thermal expansion coefficient is considered at near solidification temperature to reach a better prediction of local mechanical behaviour. By analysing the impact of these local variables on crack formation susceptibility in the inter-dendritic region, this research aims to enhance the understanding of the process-structure-property relationship during austenitic stainless steel solidification. The findings reveal that the dendritic structure under variable local thermo-chemical and process induced orientation conditions has a notable effect on the local mechanical behaviour. It is observed that the local stress-strain peaks increase when highly misoriented dendrites with a substantial difference in local concentrations coalesce in the centre of the weld seam. Thermal contractions play a vital role and produce maximum eigenstrain in the centre of the seam, which adds up to enhance the probability of solidification cracking.