Regeneration method for degraded metal material

Sensitized regions of austenite stainless steels, as a material for equipments, and an agent-embrittled portions in a ferrite phase of two-phase stainless steel are estimated by nondestructive testing upon inspection of a nuclear power plant. Then, Cr membranes are formed on the sensitized regions and the agent-embrittled portions by Cr-plating, a vacuum vapor deposition or a press-bonding. The sensitized regions and the aging-embrittled portions having the Cr membranes applied thereon are heated by laser beams. With such procedures, Cr atoms in the Cr membranes are diffused in the Cr-depleting layer of the sensitized regions and the aging-embrittled portions. As a result, sensitization on the surface of the sensitized regions is restored, so that stress corrosion crackings are less caused. In addition, occurrence of cracks on the aging-embrittled portions is reduced to restore the strength of the materials on the surface. Accordingly, there is no more necessary to replace the equipment materials, thereby enabling to prolong service life of them. (I.N.)