電気防食におけるステンレス鋼の防食限界電位の検討

Abstract

The appropriate cathodic protecting potential of the two-phase stainless steel (SUS 329J4L) was investigated in artificial sea water by the constant load method. In the constant load method, the rupturing time was used as an estimation parameter. And then, the constant tensile stress test was able to be carried out at a short time before rupturing by using the estimation parameters of mechanical characteristics. It was found that the hydrogen embrittlement of steel occurred at less noble than potential -0.85V (vs. Ag/AgCl) by the decreasing of elongation and the contraction percentage of area. After the test for 400h test, 0.2% proof strength and tensile strength of steel were increased by embrittling hardening at less noble potential than -0.85V. At the potential occuring hydrogen embrittlement, the fractured surface differed from that at the potential unoccuring embrittlement the observation using scanning electron microscope (SEM), and total length of fracture was correlated with the degree of hydrogen embrittlement.