The kinetics of hydrogenation and the mechanisms of sulphide corrosion cracking of long-term operated pipe shipbuilding 15KhСND and D32 steels were evaluated. It is found that with the increase of the service life these steels are intensively hydrogenated from the inner surface of the pipe, the concentration of hydrogen exceeds the initial values in 2–2.5 times. The same tendency of microhardness changes in the cross-section of the metal wall of pipes with different service life is observed. Its values in the near-surface layers from the outer side of the pipe increase in 1.5–2 times. With the increase of the stresses during tests under corrosion sulphide cracking in the NACE environment hydrogenation of the samples increases dramatically (in approximately 2–3 times), which causes severe embrittlement (increasing the microhardness of the metal) and a decrease in the crack growth resistance.
Макаренко et al. (Fri,) studied this question.