A Study on the Sulfide Corrosion Cracking of Welded High Strength Steel

At present there are two main theories for sulfide corrosion cracking, namely hydrogen embrittlement mechanism and stress corrosion cracking mechanism.We have studied the relation between sulfide corrosion cracking and hydrogen embrittlement, and discussed on this report about the effect of the hydrogen on sulfide corrosion cracking. The results are as follows.:(1) The cracks in the heat affected zone under the welded bead of mild steel were caused by diffused hydrogen only. It is suggested that sulfide corrosion cracking is caused by hydrogen embrittlement.(2) Absorption of hydrogen from ACOH+sat. H2S solution has a similar tendency to that of cathodic electrolysis in the quantity absorbed and absorptivity.It is suggested therefore that the absorption of hydrogen comes from the same mechanism in both of these instances.(3) Hydrogen sulfide raises hydrogen overvoltage, which accelerates the atomic hydrogen diffusion rate.Accordingly, sulfide corrosion cracking is interpreted as hydrogen embrittlement which is caused by diffused atomic hydrogen.