Hydrogen fracture maps for sheared-edge-controlled hydrogen-delayed fracture of 1180 MPa advanced high-strength steels

Abstract Hydrogen-induced delayed fracture (HIDF) of 1180 MPa martensite (MS), dual-phase (DP), quenching and partitioning (Q&P) advanced high-strength steels was studied using shear-cut U-bend specimens. Fracture maps identified the conditions that caused HIDF. HIDF initiation was largely independent of the bending strain, and was controlled by the sheared edge, creating the critical mount of plastic strain damage required for HIDF. A hydrogen enhanced plasticity (HEP) mechanism caused HIDF. Differing responses to HIDF of the three steels was related to how the microstructures interacted with the stress and strains introduced by shearing. Exploratory work indicated that shear burr arrangement had little influence.