Rolling bearing's service life and reliability depends on the metallurgical quality of bearing steel have a close relationship. Due to the nature of bearing steel, smelting quality of industrial steel is much more strict than the average, such as the steel's chemical composition, purity, organization and uniformity.
First, strictly the chemical composition requirements
General bearing steel is mainly high-carbon chromium bearing steel, carbon 1%, adding 1. About 5% of chromium, and contains a small amount of hypereutectoid steel of manganese and Silicon. Chrome heat treatment can improve performance, enhance hardenability, tempering organizational uniformity, stability, and improve the properties of steel and grinding performance. But when the chromium content of more than 1. 65%, increase of residual austenite in steel after quenching and lower hardness and dimensional stability, increase the nonuniformity of carbide, reduce the impact toughness and the fatigue strength of steel. To this end, the amount of chromium in high-carbon chromium bearing steel at 1, 65%. Only the strict control of the chemical composition of bearing steel can be obtained through heat treatment processes meet the microstructure and hardness of bearing performance.
Second, its high precision required
Dimensions steel demand steel for rolling bearings with high precision, this is because most of the bearing parts are subject to pressure. To save on materials and enhanced productivity, most bearing ring after forging, steel ball is the result of cold or hot forming, the small size of the rollers are cold forging. If steel dimensional accuracy is not high, it is impossible to accurately calculate the size and weight, and cannot guarantee the quality of bearing parts, or are likely to cause damage to the equipment and tooling.
The three, particularly stringent purity requirements
Refers to the purity of steel containing non-metallic inclusions in steel, high purity, less the non-metallic inclusions in steel. Bearing steel in the oxides, silicates and other harmful inclusions are leading to early fatigue, major causes of decreased bearing life. Brittle inclusion especially harmful, because in the process easily from metal substrate peeling, seriously affecting the surface quality of bearing parts after finishing. Therefore, in order to increase bearing service life and reliability, we must reduce the amount of inclusions in bearing steel.
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