The use of rolling bearing life and reliability to the extent of the bearing steel smelting quality of have a close relationship. Because has the bearing steel characteristics of the requirements of the quality of the smelting than general industrial steel stricter than, such as steel of chemical composition and purity degrees, the organization and the uniformity, etc.
The chemical composition of a strict requirements
General bearing steel is mainly high carbon chromium bearing steel, carbon content is 1%, to about 1.5% of the chrome, and with a small amount of manganese, silicon element of the GuoGongXiGang. Chromium can improve performance, improve its quench-hardening ability, heat treatment, microstructure uniformity, tempering stability, and can improve steel rust resistance and grinding performance. But when chrome content of more than 1.65%, quenching will increase after the steel austenite, reduce hardness and dimension stability, increase the inhomogeneity of the carbide, reduce the impact toughness of the steel and fatigue strength. Therefore, high carbon chromium bearing steel containing cr general control the amount in the,65%1. Only to strictly control the bearing steel, chemical compositions of, can satisfied by heat treatment process performance of the organization and hardness of the bearing.
2 the size of the high precision requirements
The rolling bearing steel demand steel size accuracy is higher, this is because most bearing parts are through pressure molding. In order to save material and improve labor productivity, most bearing rings are after forging forming, steel ball is a cold heading or hot rolling
Forming, small size of the roller is also after cold heading to shape. If the size of the steel precision is not high, can't accurately measured baiting size and weight, but can't guarantee bearing parts product quality, are likely to cause damage to the equipment and mold.
Three special strict pure degree requirements
The degree of purity steel is to point to steel contained in how much of the non-metallic inclusions, pure degree is higher, the steel of the less non-metallic inclusions. Bearing steel of oxide, Portland and other harmful inclusion is lead to bearing early fatigue peel, significantly reduce bearing life main reasons. Especially brittle inclusion hardest, because in the machining process from easy to metal substrate was peeling off, the serious influence bearing parts after finishing the surface quality. Therefore, in order to improve the service life of the bearings and reliability, must reduce bearing steel of inclusion in the content.
Four strict macrostructure and microscopic (at) requirements of the organization
Bearing steel macrostructure refers to the general loose, center loose and flat out, microscopic (at) organizations including the annealing organization, carbide steel mesh, belt, liquid chromatography, etc. Carbide liquid chromatography hard and crispy, the harmfulness of it with the same brittle inclusion. Reduce the network carbide steel impact toughness, and make the organization is not even, in the quenching easily when deformation and cracking. Ribbon carbide influence annealing and quenching and tempering organization contact fatigue strength. At high magnification, the organization of the low quality of the performance of the rolling bearing and have great influence on the service life, so, in bearing material standards of low, at high magnification, the organization has strict requirements.
Five special strict surface defects and internal defects requirements
As for bearing steel, surface defects including cracks, slag inclusion, burr, scarred, oxide skin, internal defects including shrinkage, bubble, white, serious osteoporosis and segregation, etc. These defects for bearing processing, bearing performance and life have great impact in bearing material standard expressly set don't allow appear these defects.
Six special strict carbide inhomogeneity requirements
In bearing steel, if appear serious uneven distribution of carbide, is in the process of heat treatment processing is easy to cause the organization and the uneven hardness, steel organization would not uniformity to contact fatigue strength have a major influence. In addition, serious carbide not uniformity is easy to make bearing parts in the quenching cracks when, carbide inhomogeneity can lead the life span of the bearings reduce so, in bearing material standards, the steel in different specifications are clear special requirements.
Seven special strict surface decarburization layer requirements
In bearing material standard of steel surface in the decarburization layer has strict rules, if the decarburization layer surface beyond the standard provisions of the range, and in the process of before heat treatment and no clear away all the, is in the process of quenching heat treatment is easy to produce the quenching cracking, causing the abandonment of parts.
Eight other requirements
In bearing steel material standard of bearing steel smelting method, oxygen content, annealing hardness, fracture, residual elements, sparks inspection, delivery status, logo, etc have strict requirements.




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