Hydrogen Embrittlement Interactions in Cold-Worked Steel

Effects of cold work on hydrogen (H) transport, H concentration, and H embrittlement (HE) in type 1020 steel (UNS G10200) exposed in a sour environment were examined. Cold work decreased H diffusivity and increased H concentration in the steel. The increase in dislocations as a result of cold work was responsible for the decrease in H diffusivity. The increase in H adsorption coverage on the surface and H trapping from cold work were likely causes for increases in H absorption into the steel. The fracture mode was dependent on specific sensitive locations within the steel that were affected by the cold work. After a steady H damage state occurred in the steel, the fracture toughness decreased with increasing cold work. Sufficiently low values of fracture toughness as a result of embrittlement occurred such that plane strain fracture occurred in relatively thin laboratory specimens.