To the general requirements of rolling bearing steel smelting quality

Smelting quality of rolling bearing steel, such as steel, such as purity, organization and uniformity are higher than general industrial steel requirements. General bearing steel is mainly chromium bearing steel, is around 1% carbon. Join the chrome 1. 5% of manganese, silicon and contains a small amount of eutectoid steel. Chromium in steel, part into solid solution, part of carburizing size carbide (with carbon FeCr） 3C。 Chromium heat treatment can improve performance, increase the hardenability, uniformity, tempering stability. After heat treatment, make steel to obtain high and even hardness, and improve the wear resistance and smooth texture. Chromium also can improve the rust resistance of steel and grinding performance. But when the chromium content in more than 1. 65% when, after quenching can increase the retained austenite in the steel, reduce hardness and dimensional stability, increase the inhomogeneity of carbide lower impact toughness and fatigue strength of steel. Therefore, control the chromium content in general are 1. Less than 65%. Non-metallic inclusion and gas in the steel, can make the early bearing fatigue spalling, will significantly reduce the bearing life. Especially brittle inclusions, the most damage, but also affects surface quality after finishing. So we must reduce the inclusion content in steel and to improve its distribution. In recent years, the popularization of the vacuum degassing steel, it can significantly reduce the non-metallic inclusion and gas content in the steel. Made bearing fatigue life can be enhanced greatly. Steel tissue inhomogeneity is has great effect on contact fatigue strength. The dangers of carbide liquid chromatography were hard and brittle, it is the same as the brittle inclusion. Carbide network to reduce the impact toughness of steel, and the uneven annealing organization, easy to deformation and cracking during quenching. Banded carbide annealing and quenching tempering and contact fatigue strength. After annealing organization shall be the fine carbide spheroidizing organization of uniform distribution, the hardness is HB170 ~ 207, is good for machining and final heat treatment, improve the using state of the fatigue life. To this end, the bearing steel after annealing organization have strict requirements.