Stress corrosion cracking behavior of 35CrMo and 00Cr13Ni5Mo steels in hydrogen sulfide solutions

Stress corrosion cracking (SCC) behavior of 35CrMo low alloy steel and 00Cr13Ni5Mo stainless steel in hydrogen sulfide environment was investigated by using slow-strain-rate test (SSRT), U-bent-specimen immersion test and electrochemincal polarization technique. Both 35CrMo steel and 00Cr13Ni5Mo steel were susceptible to SCC in various H2S solutions, and their SCC susceptibilities reduced with the increase of pH value within 3.0 and 4.5 or the decrease of H2S concentration from saturation to 1000 μg·g^-1. 00Cr13Ni5Mo steel was less susceptible to SCC than 35CrMo steel in each tested H₂S condition, but its SCC susceptibility was affected more evidently by the change of pH value than that of 35CrMo steel. The SCC susceptibility factor of 00Cr13Ni5Mo steel was close to that of 35CrMo steel in solutions with lower pH values, while in solution with a pH value of 4.5, the resistance of 00Cr13Ni5Mo stainless steel to hydrogen sulfide stress corrosion cracking was much higher than that of 35CrMo. It was due to the higher concentration of some anticorrosive elements, such as Cr, in 00Cr13Ni5Mo, that promoted the formation of a more stable passive film, leading to a higher hydrogen induced cracking (HIC) resistance of 00Cr13Ni5Mo than 35CrMo in higher-pH conditions.