The basic requirements of the quality of bearing steel smelting

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The rolling bearing life and reliability of a large extent with the bearing steel smelting quality has a close relationship. With the characteristics of bearing steel smelting quality requirements than th e average industrial steel to much more stringent, such as steel, chemical composition, purity, organizations and even.FAG bearing

And so on.
A strict chemical composition requirements

The general bearing steel is high carbon chromium bearing steel, the carbon content of about 1 percent, adding about 1.5% chromium, and contains small amounts of manganese, silicon over-eutectoid steel. Chromium heat treatment performance can be improved to improve the hardenability, even tempering stability, but also can improve the steel.double row bearing

Anti-rust properties and grinding performance. However, when the chromium content exceeds 1.65%, after quenching will increase the residual austenite in the steel, to reduce hardness and dimensional stability, increasing the heterogeneity of the carbide to reduce the im pact toughness and fatigue strength. To this end, high-carbon chromium bearing steel in the chromium content of a

-Like control in less than 1,65%. Only strict control of the chemical composition of bearing steel, can be obtained by heat treatment processes to meet the microstructure and hardness of the bearing performance.

Second, high-precision dimensional requirements

The rolling bearing steel require high dimensional accuracy of steel, this is because most of the bearing parts to go through the pressure molding. In order to save material and to improve labor productivity, most of the bearing rings are forging molding, steel ball after cold heading or hot-rolled molding, small size.tool bearings

The roller is forming after cold heading. If the steel is not high dimensional accuracy, it can not accurately calculate the size and weight of the cutting, but do not guara ntee the quality of the product of the bearing parts are likely to cause damage to the equipment and tooling.

3, in particular the strict purity requirements

The purity of the steel is contained in the non-metallic inclusions in the number of steel purity higher the degree of non-metallic inclusions in steel, the less. Harmful inclusions in bearing steel such as oxides, silicates lead to early bearing fatigue spalling, and significantly reduce the bearing life of the main reasons. Especially

Brittle inclusions most harmful, easy to peel off from the metal substrate in the process down, seriously affecting the surface quality of the bearing parts finishing. Therefore, in order to improve bearing life and reliability, we must reduce the content of inclusions in bearing steel.

Fourth, the organizational requirements of a strict low magnification microscopy (high power)

Low magnification of the bearing steel refers to the ge nerally loose, center porosity and Annealing of flat analysis, microscopy (high power) organizations, including steel, carbide mesh, ribbon and liquid analysis and so on. Hard and brittle carbide liquation, its dangers and brittle inclusions. Carbide network to reduce the impact of the steel

Toughness and uneven quenching easy deformation and cracking. The ribbon carbides affect the annealing and quenching and tempering the organization and contact fatigue strength. Low, the pros and cons of high-powered organization has a great influence on the performance and service life of rolling bearings, so the bearing material standard

Low, high-powered organization has strict requirements.

5, in particular, surface defects and internal defects requires

Bearing steel, surface defects, including cracks, folder slag, burrs, scarring, and the oxide skin, and internal defects including shrinkage, bubble, white spots, severe osteoporosis and seg regation. Processing of these defects on the bearing, the bearing performance and life has a great influence on the bearing material

Expressly provided in the material standard of these defects are not allowed.

6, in particular the stringent requirements carbide of

Bearing steel, if there is serious carbide uneven distribution likely to cause uneven microstructure and hardness in the heat treatment process, the inhomogeneity of the steel had a greater influence on the contact fatigue strength. In addition, serious carbide heterogeneity is also easy to make

Bearing parts in the quench cracks, carbide of also lead to reduced life of bearings in standard bearing materials, are clearly the special requirements of different specifications of steel.

7, in particular, strictly surface decarburized layer requirements

Bearing material standard has strict rules on the steel surface decarburized layer, if the surface dec arburized layer is beyond the scope of the provisions of the standard, in the heat treatment process before its all cleared, the heat treatment and quenching process prone to quenching crack, resulting in

Parts are scrapped.

Eight other requirements

Bearing steel standard bearing steel smelting, oxygen content, annealing hardness, fracture, residual elements, spark test, delivery status, logos, etc. There are strict requirements.