ステンレス鋼の孔食電位測定法と孔食電位に影響を及ぼす二,三の環境因子の検討

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Pretreatment methods were studies on measuring the pitting potentials free from crevice corrosion, and it has been recognized that the pitting potentials of some stainless steels can be measured with reproducibility and ease by anodic oxidation method in H2SO4 solution.On the effect of a few environmental factors on the pitting potentials, the following results have been obtained:(1) The pitting potential is also shifted to more noble values by presence of SO42- in the case of ferritic stainless steels similar to austenitic stainless steels.(2) Values of pitting potentials (EX-) are linear with logarithm of Cl- concentration (CX-), following the equation:EX-=blogCX-+a(3) The effect of various halogen ions on the pitting potentials is different in various stainless steels.SUS304, 430; (noble) I->Br->Cl- (less noble)SUS316, 26Cr-1Mo; (noble) Cl->Br- (less noble)(4) The correlation between immersion pitting tests and anodic pitting tests is recognized. and the pitting potential obtained by using the anodic oxidation method becomes a guide to predict the resistance to pitting corrosion.