Comparative analysis of as-delivered heat-resistant bearing steels

Abstract

A comparative analysis of the regulatory document requirements and the actual metallurgical quality characteristic values of domestic (8Kh4V9F2-Sh, 8Kh5M3VFB-ID) and foreign (M50 VIM-VAR) as-delivered heat-resistant bearing steels is carried out. The chemical composition, non-metallic inclusions, carbide heterogeneity, carbide morphology and hardness of hot-rolled bars of different diameters are studied. Additionally, the heat resistance is determined. It is established that the best quality (narrow component ranges, less non-metallic inclusions contamination, carbide heterogeneity and hardness) has M50 VIM-VAR steel, the worst quality is 8Kh4V9F2-Sh steel, which meets the most stringent requirements of regulatory documentation for M50 VIM-VAR steel. In bars with a diameter of up to 22 mm, the quality of all steels according to the studied characteristics does not noticeably differ. 8Kh5M3VFB-ID steel has the widest range of carbon and chromium content, the highest hardness, aluminum nitrides and eutectic carbides of the "honeycomb" type are observed. 8Kh4V9F2-Sh steel has the most heat-resistant, which allows its use at higher operating temperatures. The obtained data can be used when choosing a steel grade for bearings of a specific range.