Bearing steel quality requirements of the basic requirements of rolling bearings (35 class spherical roller bearings) life and reliability of the bearing steel with a large degree of quality is closely related to the smelting. Due to the characteristics of bearing steel, the quality of smelting requirements than the general industrial steel to be much more stringent, such as steel chemical composition, purity, organization and uniformity.
First, the strict requirements of the chemical composition of the general bearing steel is mainly high-carbon chromium bearing steel, that is about 1% carbon content, adding about 1.5% of chromium, and contains a small amount of manganese, silicon element over eutectoid steel. Chromium can improve the heat treatment performance, improve the hardenability, uniformity of the organization, tempering stability, but also can improve the anti-rust properties of steel and grinding performance. But when the chromium content exceeds 1.65%, after quenching will increase the steel in the high-carbon chromium bearing steel in the chromium content is generally controlled in less than 1,65% of the retained austenite, reduce hardness and dimensional stability, increase the carbide is not Uniformity, reduce the impact toughness and fatigue strength of steel. Only by strictly controlling the chemical composition of the bearing steel can the heat treatment process be obtained to meet the bearing properties of the organization and hardness.
Second, the high-precision size requirements Rolling bearing steel requirements Steel size accuracy is high, this is because most of the bearing parts have to be pressure forming. In order to save material and improve labor productivity, the vast majority of bearing rings are through forging molding, steel ball is cold heading or hot rolling molding, small size of the roller is also cold heading forming. If the steel size accuracy is not high, it can not accurately calculate the size and weight of the material, but can not guarantee the quality of bearing parts, but also easily lead to damage to equipment and mold.
Third, particularly stringent surface defects and internal defects requirements For bearing steel, surface defects include cracks, slag, burrs, scarring, scale, etc., internal defects include shrinkage, bubbles, white spots, severe loose and segregation Wait. These defects for the bearing processing, bearing performance and life have a great impact in the bearing material standard clearly does not allow these defects.http://www.bhsbearings.com/