The scroll NTN Bearing service life and reliability is largely NTN Bearing steel smelting quality is closely related to. Due to the characteristics of NTN Bearing steel smelting quality requirements are much stricter than the average industrial steel such as steel, chemical composition, purity, organization and uniformity.

1, strict chemical composition requirements
General NTN Bearing steel high carbon chromium NTN 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 rust resistance of steel 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 impact toughness and fatigue strength. To this end, the amount of chromium in high carbon chromium NTN Bearing steel is generally controlled at 1.65%. Only by strict control of NTN Bearing steel chemical composition, can be obtained by heat treatment processes meet the microstructure and hardness of the NTN Bearing performance.

2, high-precision dimensional requirements
Scroll NTN Bearing steel require high dimensional accuracy of steel, this is because most of the NTN Bearing parts go through the pressure molding. In order to save material and to improve labor productivity, the vast majority of NTN bearing rings are forming, after forging the ball is cold heading or hot forming, the small size of the roller is cold heading forming. If the steel is not high dimensional accuracy, it is impossible to accurately calculate the size and weight of the cutting, but can not guarantee the product quality of NTN 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. NTN Bearing steel oxides, silicates, and other harmful inclusions lead to early NTN Bearing fatigue spalling, and significantly reduce the main reason of the NTN bearing life. Brittle inclusions most harmful surface quality, easy to peel off from the metal substrate in the process down, seriously affecting the NTN Bearing parts finishing. Therefore, in order to improve the service life and reliability of the NTN Bearing NTN Bearing steel content of inclusions must be reduced.

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

Low magnification of the NTN Bearing steel is generally loose, the center loose and flat analysis, microscopy (high power) organization including steel annealing organization, carbide mesh ribbon, and fluid analysis. Hard and brittle carbide liquation, its dangers and brittle inclusions. Carbide network to reduce the impact toughness, uneven, and the organization of quenching, easily deformed 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 organizations have a great impact on performance and service life of rolling NTN Bearing NTN Bearing material standards low, high-powered organization has very strict requirements.

5, in particular, surface defects and internal defects requires
NTN 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 segregation.
 
These defects for processing NTN Bearing, NTN bearing performance and life have a great impact, clear regulations do not permit these defects in the material standard of NTN Bearing.

6, in particular the stringent requirements carbide of
NTN 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, the carbide of the NTN bearing parts in the quench cracks, carbide of also lead to reduced life of NTN bearings in NTN Bearing material standards, different specifications of steel there is a clear special requirements.

7, in particular, strictly surface decarburized layer requirements
Decarburized layer on the steel surface in the material standard NTN Bearing strict rules, if the surface decarburized layer beyond the standard specified range, before heat treatment process has not be all removed, the heat treatment and quenching process prone to quenching cracks, resulting in scrapped parts.
Eight other requirements

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




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