HEAT TREATMENT FOR RECYCLING OF EQUIPMENT MADE OF STAINLESS STEEL FOR NUCLEAR POWER USE

摘要

PROBLEM TO BE SOLVED: To return equipment made of stainless steel or its weld zone, deterio rated in toughness, elongation, and fatigue strength after long use in a nuclear reactor water environment, to its initial condition and to attain its recycling. SOLUTION: A precipitation hardening stainless steel or a martensitic stainless steel, each deteriorated in toughness, elongation, and fatigue strength, or the weld zone of the above steels is held at 900 to 1050 deg.C and cooled rapidly by water cooling or forced air cooling. Then, precipitation hardening heat treatment is applied in the case of the precipitation hardening stainless steel at 470 to 630 deg.C, and tempering is applied in the case of the martensitic stainless steel at 500 to 700 deg.C. By this method, toughness, elongation, and fatigue strength can be recovered, and also corrosion resistance can be recovered with respect to the weld zone, and recycling is made possible.