Interface and Heat-affected Zone Features of Dissimilar Welds between AISI 310 Austenitic Stainless Steel and Inconel 657

The aim of this paper is to characterize welding of AISI 310 austenitic stainless steel to Inconel 657 for use in oil-refining industries. The welds were produced using four types of filler materials; nickel-based alloys designated as Inconel 82, A, 617, and 310 SS. The interfaces and heat-affected zones were characterized by optical and scanning electron microscopy. Interfaces on the two sides of the joints showed unmixed and heat-affected zones, while a partially melted zone was observed in the interdendritic regions of the HAZ in Inconel 657. The microhardness profile from the base metal to the HAZ exhibited high hardness in the case of Inconel 657 as an indication of α-Cr precipitation in the HAZ of all the filler materials investigated and as the occurrence of precipitation hardening. It was concluded that undesirable regions such as UZ, HAZ, and PMZ have the least average size for Inconel 82 and 310 SS weldments among the weld metals studied.