The weldability of low activation Cr-W steels

A series of chromium-tungsten ferritic steels patterned on the chromium-molybdenum alloys, 2 1/4 Cr-1Mo, 9Cr-1MoVNb and 12Cr-1MoVW, were tested for weldability. These steels are being developed as candidates for the first wall and blanket structure of fusion reactors. Use of these materials will minimize the long-term radioactive hazards associated with disposal after service. In these low activation alloys, long half-life elements (Mo and Nb), which become activated during irradiation, are replaced. Autogenous bead-on-plate welds were performed using the gas tungsten arc welding process. Experimental results showed that all welds were free of cracks. Sound welds were achieved in 2 1/4 and 5% Cr-W low activation steels while loss of ductility was observed in 9 and 12% Cr-W steels. This result suggests that post-weld heat treatment is necessary to restore toughness to the 9-12% Cr-W steels. (orig.)