Heat Resisting High Manganese Stainless Steel as Reduced Radioactivation Material

The outline of recent study on heat resisting high manganese stainless steel is reviewed. High manganese stainless steel is now focused on a reduced radioactivation material used for first wall of fusion reactor. The substitution of manganese for nickel and that of tungsten for molybdenum are very effective to achieve a reduced level of longterm radioactivity. The concept of reduced activation materials is closely related to the waste management and reactor safety. The beneficial effects of alloying elements, carbon and nitrogen, on γ-phase stability and prevension of σ-phase formation in Fe-Cr-Mn alloy system are shown. High temperature tensile strength and creep properties of Fe-Cr-Mn alloy are also improved by alloying with carbon and nitrogen, and combined addition of tungsten and vanadium to the alloy is shown to be very helpful in increasing creep strength. Characteristic feature of void swelling by neutron irradiation is also discussed in these alloys.