A comprehensive study on solidification (hot) cracking in austenitic stainless steel welds from a microstructural approach

The present work evaluates solidification cracks in stainless steel welds that have been produced on a laboratory scale by carrying out a detailed EBSD (electron backscattered diffraction) investigation. The welding speed presented a near-linear relationship with the susceptibility to cracking. A wide range of microstructures were generated by varying the welding speed. The cracks were predominantly transgranular type and mainly propagated through grains with lower Taylor factors. These cracks were accompanied by a strong presence of a localized strain field (high local misorientation), which was observed by a higher presence of low angle grain boundaries (LAGBs). A correlation was found between the local in-grain misorientation and the crack sensitivity. With increased thermal tensile strains, certain LAGBs transformed into HAGBs to accommodate the strain and that resulted in the formation of strain-free grains. The elastic stored energy estimated from EBSD also showed an increase with the local misorientation.