ELECTRON BEAM WELDING OF TUNGSTEN AND ODS ALLOYS

The weldability of advanced heat resistant ODS metallic materials in combination with other materials is a prior requirement for their wider use in industry energy production. A special case is formed by the requirements of the International Thermonuclear Experimental Reactor (ITER) construction, where tungsten alloy needs to be incorporated in weld joint. Due to heating during conventional welding, the microstructure and properties of the resulting weld joints are affected and the joints often become the weakest point of the structure. The electron beam welding with its reduced heat affected zone size may be an answer in this as it is one of the few techniques able to melt tungsten. The presented article is focused on thorough metallographic evaluation of the structure of heterogeneous electron beam welds which combine stabilized tungsten alloy WL10 with MA956 ferritic ODS steel. EB welded joints were evaluated by light and analytical electron microscopy including EDS analyses in the as-welded. Mechanical properties were evaluated by microhardness profiles. Achieving an appropriate structure of such welds and correct welding parameters are crucial aspects for future successful application of similar joints.