Effects of Environmental Factors on Hydrogen Absorption and Sulfide Stress Cracking Susceptibility of Low Alloy Steel

Abstract

In this study, the sulfide stress cracking (SSC) susceptibility of high-strength low alloy steels was investigated quantitatively. Double cantilever beam tests were used to evaluate the effects of environmental factors, namely pH, H2S partial pressure, and temperature, on the SSC. The corrosion rates and the absorbed diffusible hydrogen concentration were also determined. The critical stress intensity factor (KISSC), which signifies the SSC susceptibility, was mainly affected by the H2S partial pressure and the temperature. Even though the solution pH apparently affected the corrosion rate, the influence of pH on KISSC was small. Considering these results, the environmental contribution in each elementary process of the SSC phenomenon was discussed. The estimated local hydrogen concentration at the crack tip area, which clearly depends on H2S partial pressure and temperature, showed good correlation to the KISSC obtained in various sour conditions.