Hot cracking in laser welding of equiaxed and directionally solidified nickel-based alloy IN792: Experimental and numerical study

In the new sustainability-based scenario emerging in our era, welding, and repairing nickel-based alloys and superalloys play a crucial role in avoiding the replacement of very expensive components. Laser beam welding is an effective technique that can be used for this purpose. However, when considering nickel-based alloys, laser welding is challenging since the integrity of the joints might be compromised by the occurrence of welding cracking. The present work aims to investigate the hot-cracking susceptibility of the Nikel-based alloy Inconel 792, in both equiaxed and directionally solidified forms. For a deep comprehension of the phenomena, a numerical model was developed to complement the experimental results, revealing that a concentration of stresses related to the solidification process of the fusion zone is mitigated by the intrinsic characteristics of the directionally solidified microstructure. Indeed, the issues related to grain boundary liquation in the heat-affected zone and solidification cracks in the fusion zone are aggravated in the equiaxed joint.