Progress in the development of reduced activation ferritic-martensitic steels and fabrication technologies in India

The Indian reduced activation ferritic-martensitic (RAFM) steel, meeting the stringent chemical composition requirements with respect to radiologically undesirable elements as well as trace and tramp elements, has been produced by vacuum induction melting followed by vacuum are refining. Also, the optimum combination of normalising and tempering heat treatments was determined. Detailed investigations on the microstructure, including thermodynamic and kinetic features of phase transformations, and tensile, creep and ductile–brittle transition behaviour of this steel indicate that the Indian RAFM steel has the required microstructure, phase stability, creep rupture strength, elevated temperature tensile strength as well as low ductile-to-brittle transition temperature. Systematic investigations have been conducted to optimise the welding parameters to produce crack-free welds using laser and electron beam welding techniques. Salient features associated with materials development, fabrication technologies and characterization of Indian RAFM steels are highlighted.