Combined effect of hydrogen embrittlement and corrosion on the cracking behaviour of C110 low alloy steel in O2-contaminated H2S environment

The cracking behavior of sulfide stress cracking resistant C110 steel in O2-contaminated H2S environment was investigated by cracking and corrosion simulation tests. With the increase of O2 partial pressure, the cracking susceptibility and corrosion rate of C110 steel significantly increased. The O2 ingress affects the whole cracking behaviour involving a multi-stage process: the oxidation reactions of H2S, the corrosion reactions on the metal surface and the degradation and cracking of martensitic multiscale boundaries. The cracking mechanism of C110 steel in H2S and O2-containing environment is attributed to the combined effect of hydrogen embrittlement and anodic dissolution. [Display omitted] •Cracking susceptibility and corrosion rate of C110 steel significantly increase with the increase of O2 partial pressure.•The ingress of O2 into H2S-containing solution induces oxidation reactions of H2S.•Dissolution and oxidation of mackinawite result in the formation of porous corrosion product films.•Cracking mechanism is attributed to the combined effect of hydrogen embrittlement and anodic dissolution.