Numerical analysis of the weldability of superalloys

When manufacturing fusion welds, the potential exists for defects to be introduced. The possibilities include the formation of a centreline grain boundary, interdendritic microporosity, constitutional liquation and solidification cracking. In this paper, numerical analysis is carried out in order to predict the processing conditions necessary to cause the occurrence of these phenomena. Although the models developed are of general applicability, their behaviour is examined particularly with respect to the tungsten–inert gas (TIG) welding of the nickel-based superalloy IN718. Weldability maps are presented, on which the conditions for successful processing are identified.