High‐Temperature Oxidation Behavior of Cr‐Si Alloyed Press‐Hardened Steel in Comparison with 22MnB5 Steel

Abstract

In the present study, a Cr–Si‐alloyed coating‐free press‐hardened steel (CF–PHS) is investigated and compared with the conventional 22MnB5 steel through a 60 min oxidation experiment at 1000–1200 °C. Compared to the 22MnB5 steel, the CF–PHS exhibits lower weight gain at 1000–1150 °C but a higher weight gain at 1200 °C. In the results, using scanning electron microscopy, energy‐dispersive spectroscopy, and X‐ray diffraction, it is revealed that the outer oxide layer of the CF–PHS consisted of Fe2O3 and Fe3O4, while its inner oxide layer is enriched with FeCr2O4 and Fe2SiO4—crucial for the oxidation resistance of the CF–PHS. The outer oxide layer of 22MnB5 comprises Fe2O3, Fe3O4, and FeO, while the inner layer contains low concentrations of Cr and Si. The mechanism of superior high‐temperature oxidation resistance of CF–PHS compared to 22MnB5 at 1000–1150 °C reveals that the existence of FeCr2O4 and Fe2SiO4 inhibits the diffusion of Fe2+ and O2−, effectively hindering the oxidation progress. Moreover, the oxidation resistance of the CF–PHS at 1200 °C deteriorates owing to the melting of Fe2SiO4 at 1200 °C, which significantly accelerates the diffusion of Fe2+ and O2−, thus exacerbating the oxidation of CF–PHS.