RI利用による鉄鋼の硫化物腐食われに関する研究

Abstract

It has been generally considered that sulfide corrosion cracking of steels is hydrogen embrittlement cracking, but it has not been confirmed clearly. Furthermore, few studies on the behavior of sulfer has been reported.In the present study experiments have been made on the behavior of sulfide in the sulfide corrosion cracking using a radio-isotope of 35S: 80 kg high strength steel, 60 kg high strength steel, APS steel and boiler plate steel were used as specimens. These specimens were immersed in sulfide corrosive solution under stress for a long time. After this treatment, the distributions of 35S in these specimens were investigated by radiometry and an autoradiographic technique.The experimental results are as follows:(1) The more the susceptibility of the specimens to the sulfide corrosion cracking is, the greater the amount of 35S deposit. And 35S diffuses in such specimens more deeply.(2) The distribution of induced crack corresponds almost exactly to that of 35S. Howevre, 35S cannot be detected in some cracks.(3) The influence of stress on the sulfide corrosion cracking was confirmed.(4) It is considered that sulfur diffuses into grain boundaries of steels.It has been conclude that the sulfide corrosion cracking is different from simple hydrogen embrittlement cracking and stress corrosion cracking by anode attacks exerts influence on the sulfide corrosion cracking.From the these points of view, the behavior and the role of sulfur in the sulfide corrosion cracking should be investigated with more keen interest.