Effect of various quenching methods on hydrogen embrittlement resistance of a 2200 MPa press-hardened steel

Hydrogen embrittlement (HE) poses a significant barrier to the application of ultra-high strength press-hardened steels (PHS). This research presents an innovative quenching method that improves HE resistance in PHS. The results show that with the decrease in quenching speed, the sample undergoes self-tempering, and the dislocation density decreases, which leads to a reduction of diffusible hydrogen content. Notably, the sample with a lower fraction of high-angle grain boundaries and random boundaries (Σ > 29) had higher resistance to HE. This is attributed to the high-angle grain boundaries and the random boundaries acting as regions where dislocations accumulate. As hydrogen atoms migrate along these dislocations, they tend to accumulate at these sites, ultimately leading to premature fracture caused by HE. This study delivers novel perspectives on the influence of heat treatment parameters on hydrogen-induced degradation mechanisms, offering valuable guidance for designing robust high-strength steels with improved HE performance.