| 摘要 |
PROBLEM TO BE SOLVED: To prolong the life of corrosion resistance by forming a coating and covering as thick films and to form the coating and covering layers which are excellent in an adhesion property even if the film thickness is increased. SOLUTION: Austenitic stainless steel is previously formed with intergranular corrosion or stress corrosion crack more deeply than the crystal grain boundaries of a base metal, and the surface thereof is subjected to diffusion coating in order to increase the film thickness of the coating or covering layer and to improve the adhesion property. The surface is otherwise subjected to thermal spraying and plating, then to heat treatment. As a result, the components effective for the corrosion resistance (for example, Cr, Al, Si, or the like) are eventually diffused deeply into the base metal through segments subjected to the occurrence of the intergranular corrosion or stress corrosion crack, and the treatment layers can be applied like wedges to the base metal at the front ends of the intergranular corrosion or stress corrosion crack.
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