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

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 degrees C. Compared to the 22MnB5 steel, the CF-PHS exhibits lower weight gain at 1000-1150 degrees C but a higher weight gain at 1200 degrees 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 degrees 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 degrees C deteriorates owing to the melting of Fe2SiO4 at 1200 degrees C, which significantly accelerates the diffusion of Fe2+ and O2-, thus exacerbating the oxidation of CF-PHS. Herein, it is revealed that the superior high-temperature oxidation resistance of a novel Cr-Si-alloyed coating-free press-hardened steel (CF-PHS) compared to 22MnB5 at 1000-1150 degrees C is attributed to the existence of FeCr2O4 and Fe2SiO4. And, the deterioration of oxidation resistance of CF-PHS at 1200 degrees C owes to the melting of Fe2SiO4.image (c) 2023 WILEY-VCH GmbH