鋭敏化SUS304ステンレス鋼の応力腐食割れ抑制に及ぼす紫外線照射強度の影響

Abstract

The effect of irradiation of ultra-violet(UV) light on stress corrosion cracking(SCC) behavior for sensitized SUS304 stainless steel in a deaerated 10−3 kmol·m−3 NaCl solution at 368 K has been investigated by using a slow strain rate testing(SSRT) apparatus with a dynamic observation system. The UV light, whose range of wavelength was from 250 to 400 nm, was emitted by a mercury lamp, and was irradiated to the specimen through the test solution. In order to change an intensity of the UV light, some neutral density filters were set in front of the quartz glass window on the cell. A potential of −200 mVAg⁄AgCl was applied to the specimen before and during SSRT, and the UV light was irradiated up to the strain showing almost the yield stress. It was obvious that the SCC initiation was inhibited by the UV light irradiation to the specimen during SSRT. Crack initiation frequency varied with the light intensity, and an optimum intensity range existed for inhibiting crack initiation completely. On the other hand, the crack propagation rate showed almost no dependence on the irradiation conditions. In the case that the UV light was irradiated to the shielding material mounted in front of the specimen, a lot of cracks were initiated on the specimen, similar to the case without irradiation. This fact indicates that the SCC is not influenced by the solution chemistry altered by the UV light irradiation.