Study of hydrogenation kinetics influence on sulfide stress corrosion cracking of shipbuilding-steels

The hydrogenation kinetics and the mechanisms of sulfide corrosion cracking of long-term operated pipe shipbuilding 15KhSND and D32 steels were evaluated. With the increase of the service life, these steels were intensively hydrogenated from the inner surface of the pipe, and the concentration of hydrogen exceeded 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 was 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 sulfide cracking in the NACE environment hydrogenation of the samples increases dramatically (approximately 2–3 times), which causes severe embrittlement (an increase of metal microhardness) and the crack growth resistance decrease.