Role of Vanadium Carbide in Hydrogen Embrittlement of Press-Hardened Steels: Strategy From 1500 to 2000 MPa

This work investigated hydrogen trapping and embrittlement (HE) in two press-hardened steels, 22MnB5 for 1,500 MPa grade 34MnB5V 2000 grade, respectively. Superior to the steel, newly developed steel has an ultimate tensile strength of over without sacrificing ductility due formation vanadium carbides (VCs). Simulated press hardening was applied induced by cathodic charging. Susceptibility HE validated slow strain-rate test. When content high, fractured elastic regime. However, when 0.8–1.0 ppmw, bore much higher stress than before fracture. The behavior thermal desorption analyses. Although steels trapped similar amounts after charging, their mechanisms effective sites were different. In summary, a finer prior austenite grain size pinning effect VCs can also improve toughness steel. Moreover, boundary suppresses occurrence hydrogen-enhanced local plasticity. Microstructural refinement enhanced improves resistance Importantly, correlation between improvement is not significant. Hence, this presents challenge designing irreversible future steels.