Welding consumable selection for 304B4 borated stainless steel

Abstract 304B4 borated stainless steel is used for neutron shielding in intermediate heat exchangers of Indian prototype fast breeder reactor. The weldability of this stainless steel is poor and there is no standard consumable available for welding this steel. In this study, weldability of 304B4 SS weld joint prepared using E308 is evaluated using the spot Varestraint test technique. The weldability of this consumable is compared with other consumables like E309 and boron-added E308BRN. E308 consumable shows lower total crack length (4.5 mm) and maximum crack length (1 mm) values as compared to E309 consumable while joining 304B4 SS after buttering. Mechanical properties of the weldments prepared using E308 and 304B4 filler wire were evaluated and compared with the properties of weldments prepared using E309 and E308BRN. E308 consumable shows higher tensile strength (541 MPa) than E309 weldment (420 MPa). Also, the impact toughness of 308 weld metal (117 J) is higher than E309 weld metal (55 J). Whereas, the 304B4 SS filler wire shows better tensile strength than E308 or E309 weld joints but poor weld metal impact toughness. The study gives a clear guidance for selecting appropriate consumable for welding borated stainless steels based on the final application of the fabricated component.