Steel wire rod for bearing steel, manufacturing method of steel wire rod for bearing steel, heat treatment method of steel bearing, steel bearing and soaking method of bearing steel
A heat treatment method of manufacturing high carbon bearing steel having excellent abrasion resistance and fatigue resistance, a steel wire rod for high carbon bearing steel subjected to the heat treatment, a manufacturing method of the steel wire rod, high carbon bearing steel manufactured by the heat treatment and a soaking method of a steel bloom used for manufacturing the steel wire rod. The heat treatment method of bearings includes the steps of: quenching a bearing-shaped steel part containing, by weight, 0.5% to 1.20% carbon and 1.0% to 2.0% silicon; and partitioning the quenched steel part at a temperature ranging from M s −100° C. to M s for at least 10 minutes, where M s represents a temperature at which formation of martensite will start.
1. A steel bearing comprising, by weight, 0.50% to 1.20% carbon, 1.0% to 2.0% silicon, 0.20% to 1.00% manganese, 1.30% to 1.60% chromium, and up to 0.025% phosphorous, up to 0.025% sulfur, and 12 ppm or less of oxygen as impurities, wherein the steel has a microstructure comprising martensite and retained austenite, and the martensite contains no carbides, except for spheroidized carbides.
2. The bearing of claim 1 , wherein the retained austenite comprises an area fraction from 5% to 15%.
3. The bearing of claim 1 , having a surface and a central portion comprising martensite and retained austenite.
4. A steel wire rod for bearings for quenching and partitioning, comprising: by weight, 0.50% to 1.20% carbon, 1.0% to 2.0% silicon, 0.20% to 1.00% manganese, 1.30% to 1.60% chromium and us to 0.025% phosphorous, up to 0.025% sulfur, and 12 ppm or less of oxygen as impurities, wherein coarse carbides formed due to center segregation during casting are removed.
5. The steel wire rod for bearings of claim 4 , further comprising at least one element selected from the group consisting of, by weight, up to 0.1% aluminum, up to 1.0% nickel and up to 1.0% copper.