Effect of microstructures and inclusions on hydrogen-induced cracking and blistering of A537 steel

The hydrogen-induced cracking (HIC) and blistering behaviour of A537 steel was investigated by electrochemical hydrogen permeation measurements, electrochemical hydrogen-charging tests, and surface characterisation techniques. The results indicate that at ambient temperatures the diffusivity of hydrogen in A537 steel varies along three perpendicular directions. The diffusivity of hydrogen along the through-surface (S) direction was observed to be lower than that along each of the other two directions. The hydrogen concentration of A537 steel increased with increasing charging current density, which promoted the HIC susceptibility of the A537 steel. HIC initiated primarily at the interface of ferritic/pearlitic bands and nucleated at non-metallic inclusions in the A537 steel.