A Mechanistic Approach to Sulfide Stress Cracking Resistance of High Strength Octg Steels

Due to the increasing development of offshore applications in recent years, operational equipment used at the seabed is exposed to lower temperatures (about 4ºC) than the ones used in qualification tests. This development has triggered the study of the effect of temperature on SSC susceptibility of High Strength Steels given the reduced cracking resistance observed at lower testing temperatures. Particularly, the influence of temperature on K_ISSC values was considered because there is still no explanation for this dependence. Great amount of work regarding not only the influence of environmental parameters (temperature, H₂S content) on K_ISSC but also the effect of hydrogen sulfide on hydrogen absorption has been performed, though it is difficult to relate both types of approaches. The intention of this work is to try to give some light on the effect of hydrogen sulfide on corrosion and hydrogen insertion in NACE environments, and at the same time, study the effect of hydrogen insertion and transport characteristics on K_ISSC. For this matter, the influence of temperature and hydrogen sulfide on K_ISSC values was studied for 1Cr-0.7Mo High Strength Steels along with the assessment of corrosion rates, absorbed diffusible hydrogen and diffusion coefficient between 10ºC and 60ºC.