Comparison of hydrogen embrittlement susceptibility of three cathodic protected subsea pipeline steels from a point of view of hydrogen permeation

Revealing the hydrogen permeation behavior in steel is the foundation to analyze hydrogen induced fracture. Herein, slow strain rate tension tests were used to investigate the susceptibility of X70, X80 and X100 steel to hydrogen embrittlement induced by cathodic polarization, and the subsurface hydrogen concentration (C-0) of three steels was accurately determined by two kinds of hydrogen permeation tests. Results showed that the HE index range of ductile-to-brittle transition should be determined by fracture analysis. The C-0 increased in turn from X70, X80 to X100 at any given applied potential, that's why X100 presented the highest hydrogen embrittlement susceptibility.