Characteristics, NSK Bearings Steel smelting quality requirements are much stricter than the average industrial steel such as steel, chemical composition, purity, organization and structure uniformity.
 
First, the strict chemical composition requirements
 
General NSK Bearings 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. Only by strict control of the content of the chemical composition of NSK Bearings Steel, only through thermal disposal processes to meet the performance of NSK Bearings microstructure and hardness.
 
Second, the size requirements of the stringent precision
 
The rolling bearing steel require high dimensional accuracy, this is because most of NSK Bearings parts go through pressure molding. In order to save raw materials and improve labor productivity, the vast majority of NSK Bearings ferrule must be forged to shape, 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, which can not guarantee the product quality of the parts of NSK Bearings, are likely to cause damage to manufacturing equipment.
 
Third, in particular the strict purity requirements
 
The purity of the steel is refers to the steel of impurities, the higher the purity, non-metallic inclusions in steel, the less. Oxides, silicates, and other harmful impurities in bearing steel and NSK Bearings early fatigue spalling, NSK imported bearings reduced life have a great relationship. Brittle impurities harm, easily peeling off from the metal substrate in the process, seriously affecting the appearance of quality after the finishing of the NSK Bearings.
 
Fourth, the organizational requirements of a strict low magnification microscopy (high power)
 
Low magnification of the bearing steel refers to the generally loose, center porosity and Annealing of flat analysis, microscopy (high power) organizations, including steel, carbide mesh, ribbon and liquid analysis and so on. Carbide liquation hard and brittle, the dangers of brittle inclusions the same.
 
Carbide network to reduce the impact toughness, and uneven quenching are susceptible to deformation and cracking. The ribbon carbides affect the annealing and quenching and tempering the organization and contact fatigue strength.
 
Fifth, external defects and internal defects are particularly stringent requirements
 
NSK Bearings steel, external 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 the machining of bearings, NSK import bearing performance and life have a great impact, NSK imported bearing specification clear that these defects are not allowed.
 
Sixth, the particularly stringent requirements carbide of
 
NSK Bearings in steel, if there is serious carbide uneven distribution of thermal disposal process, it is easy to cause non-uniform microstructure and hardness, the inhomogeneity of the steel had a greater influence on the contact fatigue strength.
 
Seventh, the particularly strict appearance decarburized layer requirements
 
NSK Bearings specification has strict rules decarburized layer of steel appearance, if the appearance of decarburized layer does not meet the standard requirements in the heat treatment process before its all cleared, and then quenching in the heat disposal process is prone to quenching cracks, resulting in scrapped parts.
 
Eighth, the other requirements
 
The material specification of the bearing steel bearing steel smelting, oxygen content, annealing hardness, fracture, and the remaining elements, spark test, delivery status, logos and other stringent requirements.



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