The influence of hydrogen on 3.5NiCrMoV steel studied using the linearly increasing stress test

The linearly increasing stress test (LIST) was used to study the influence of hydrogen on 3.5NiCrMoV steel in acidified 0.1 M Na2SO4, pH 2 at increasingly negative applied potentials to −1700 mVAg/AgCl. For specimens tested in solution with an applied potential, there were surface cracks in the necked region, but no surface cracks in the uniformly deformed part of the specimen. This implies that there was no influence of hydrogen up to the yield stress of the steel. Hydrogen induced brittle fracture events made a small contribution to the overall ductile fracture, which occurred after the onset of necking.

► There was no influence of hydrogen up to the yield stress.
► Hydrogen cracks occurred only in the necked region of the specimen.
► During final ductile fracture, there were small isolated hydrogen associated brittle fracture events.
► These hydrogen events competed with simultaneously occurring ductile fracture in the necked region.