DEVELOPMENT OF TRANSITION-METAL JOINT FOR STEAM-GENERATOR CIRCUIT OF PROTOTYPE FAST BREEDER REACTOR

A transition metal joint between type 304 stainless steel and 2.25Cr-1Mo steel, with Alloy 800 as the transition piece, is being developed for application in the steam generator circuit of the 500 MW prototype fast breeder reactor. As part of this program, the hot cracking susceptibility of Inconel 82/182 and 16-8-2 welding consumables were compared and the microstructure and mechanical properties of butt welds between type 304 stainless steel and Alloy 800, welded by the two consumables, were studied to select the appropriate welding consumables for this joint. It is recommended that 16-8-2 consumable should be used for welding this joint because of its lower microfissuring tendency and reduced mismatch in the coefficient of thermal expansion across the joint, although this would mean a slight adverse effect on the elevated temperature mechanical properties.