Susceptibility of 420 martensitic stainless steel to cracking in hydrogen sulfide/carbon dioxide/chloride environments.

摘要

The purpose of this study was to determine the effect of tempering temperature, P{dollar}sb{lcub}rm Hsb{lcub}2{rcub}S{rcub}{dollar} and P{dollar}sb{lcub}rm CO{lcub}sb 2{rcub}{rcub}{dollar} on sulfide stress corrosion (SSC) cracking and/or stress corrosion cracking (SCC) resistance of AISI 420 martensitic stainless steel. Slow strain rate tests were used to evaluate the SSC and/or SCC susceptibility at 22{dollar}spcirc{dollar}C in 0.5% acetic acid--5% NaCl solutions saturated with N{dollar}sb2{dollar}, with 90%H{dollar}sb2{dollar}S/10%CO{dollar}sb2{dollar}, with 50%H{dollar}sb2{dollar}S/50%CO{dollar}sb2{dollar}, with 10%H{dollar}sb2{dollar}S/90%CO{dollar}sb2{dollar} and with 100%CO{dollar}sb2{dollar}.; It was found that the susceptibility to SSC and/or SCC is strongly affected by tempering temperature. Tempering at 750{dollar}spcirc{dollar}C produces the most favourable microstructure for SSC resistance, that is a well-recovered substructure with fine carbides. Moreover, the predominant intergranular cracking of (0.38%C) 420 steel was directly related to the precipitation of the closely spaced carbide particles along the prior austenite grain boundaries.; Regardless of the tempering temperature, high susceptibility to SSC was evidenced in H{dollar}sb2{dollar}S-containing solutions, where above 10% H{dollar}sb2{dollar}S the degree of susceptibility is only slightly dependent on the H{dollar}sb2{dollar}S concentration. The addition of CO{dollar}sb2{dollar} to H{dollar}sb2{dollar}S-containing solutions does not affect the acidity of the solutions, but it slightly lowers the aggressiveness of the test solutions. (Abstract shortened by UMI.)