Oxidation mechanisms of a Cr[sbnd]Si alloyed coating-free press-hardened steel under simulated press hardening conditions

Abstract

Press-hardened steel (PHS) undergoes severe high-temperature oxidation after press hardening, which significantly degrades surface quality and increases manufacturing cost. This work reports the mechanism by which a coating-free PHS (CF-PHS) with the simultaneous presence of Cr, Si, and Mn alloying elements achieves excellent high-temperature oxidation resistance. It is found that Si and Mn in the CF-PHS promote the formation of a continuous Cr2O3 layer with good protective effect, thereby improving high-temperature oxidation resistance, during the press hardening. Moreover, the continuous amorphous SiO2 layer formed at the oxide scale/matrix interface and the Mn-rich oxides that improve the compactness of the scale further enhance the oxidation resistance of the CF-PHS.