Characteristics of dissimilar welding of alloy 690 to 304L stainless steel

The object of the present work is to research the dissimilar welding of nickel based 690 alloy and SUS 304L stainless steel using two alternative Inconel filler metals, namely, 82 (I-82) and 52 (I-52). Gas tungsten are welding with identical parameters and procedures was used to carry out single V groove butt welding with six passes in four layers on nickel based alloy 690 and 304L stainless steel. Mechanical and corrosion resistance tests were performed. Metallographical, fractographical, and compositional analysis were used to study filler metal dissimilarities. Mechanical tests show that the I-82 weldment, owing to its denser dendrites and formation of abundant niobium enriched precipitates, has a higher strength and hardness than the I-52 weldment. Rupture occurred in the alloy 690 base metal. In comparison, the I-52 weldment, with coarse dendrites and no niobium enriched precipitates, exhibits superior corrosion resistance to the I-82 weldment but has a lower tensile strength and ruptured in the fusion zone. Microstructural investigation reveals that I-52 is a mixture of cellular dendrites and columnar dendrites whereas I-82 is mainly columnar dendrites with niobium enriched precipitates. STWJ/227.