Effect of cold rolling on the hydrogen induced delayed failure of API X-52 line-pipe steel

Abstract

Hydrogen induced delayed failure of the commercial line pipe steel API X-52 was investigated by static loading tests on cathodically hydrogen charged sheet specimens. Annealed specimens were cold rolled to 10, 30 and 50% reductions in thickness and delayed failure characteristics evaluated. The annealed steel exhibited typical delayed failure behaviour. Cold work alters this behaviour in a complex fashion. The incubation period is reduced or eliminated. The upper critical stress and static fatigue limits were lowered with increasing cold work up to 30 % beyond which they were raised. Scanning electron fractography revealed a micro void coalescence fracture mode in all cases.