Microstructures and mechanical properties of a modified high-C–Cr bearing steel with nano-scaled bainite

TLDR: The microstructures and mechanical properties of a novel bainitic bearing steel subjected to austenitizing at 950°C for 40min followed by low-temperature austempering at 200°c for 2h, 6h, 12h and 72h were studied in this paper.

Abstract: The microstructures and mechanical properties of a novel bainitic bearing steel subjected to austenitizing at 950 °C for 40 min followed by low-temperature austempering at 200 °C for 2 h, 6 h, 12 h and 72 h were studied Nano-bainite microstructure with bainitic ferrite plate thickness about 50±15 nm was obtained by austempering at 200 °C for 6 h, 12 h and 72 h Besides nano-scaled bainitic ferrite plates, there were small amount of retained austenite and undissolved carbides in the microstructure The volume fraction of retained austenite is 72% in the samples austempered at 200 °C for 72 h The ultimate tensile strength of samples austempered at 200 °C for 72 h reaches 2373 MPa, which is superior to the sample austempered at 200 °C for 2 h, whose microstructure is almost full martensite The weight loss values are 00100 g and 00273 g for samples austempered for 72 h and 2 h respectively and the wear resistance of the sample austempered for 72 h is about 17 times higher than that for 2 h Because of the excellent strength and wear resistance of the low-temperature bainite, this low-temperature austempering could be a potential technology for manufacturing bearings