NSK bearing steel imports because is the characteristics of the requirements of the quality of the smelting than general industrial steel stricter than, such as steel of chemical composition and purity, organization and structure uniformity, etc.
First, strict chemical components
General NSK bearing steel imports 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. Only to strictly control the NSK bearing steel imports of the chemical composition of the content, just can be through the heat treatment process satisfied import bearings performance NSK organization and hardness.
Second, the strict requirement of high precision size
The rolling bearing steel demand higher dimensional accuracy, this is because most NSK bearing parts imports are through pressure molding. In order to save raw material and improve labor productivity, most NSK bearings imported to forming rings forging, 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, and thus can not guarantee NSK bearing parts imports of product quality, also easy to cause the manufacturing equipment damage.
Third, especially strict pure degree requirements
The purity of the steel is to point to in the steel with impurity of amount, purity, the higher the steel non-metal inclusions less. Bearing steel of oxide, Portland and other harmful impurities content and NSK bearings imported early fatigue peel, NSK import bearing life reduce has the very big relations. Especially the brittleness impurities hardest, because in the machining process from easy to metal substrate was peeling off, the serious influence NSK bearings after finishing the import appearance quality.
Fourth, the 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, harmfulness and brittle inclusion the same. Reduce the network carbide steel impact toughness, and make the organization is not even, quenching easily when deformation and cracking. Ribbon carbide influence annealing and quenching and tempering organization contact fatigue strength.
Fifth, external defects and internal defects special strict requirements
NSK bearing steel imports of concerned, external 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, NSK bearing performance and life of the imports have great influence, NSK bearing material specification imported specified not be allowed the defects.
Sixth, especially strict carbide inhomogeneity requirements
NSK import bearing steel, if appear serious uneven distribution of carbon dioxide, the heat treatment processing process in just easy to cause the organization and the uneven hardness, steel organization would not uniformity to contact fatigue strength have a major influence.
The seventh, especially strict appearance decarburization layer requirements
NSK bearing material specification import steel decarburization layer appearance has strict regulation, if appearance decarburization layer does not accord with a standard provisions of the range, and in the process of before heat treatment and no clear away all the, the heat treatment in quenching process is likely to occur in the quenching cracking, causing the abandonment of parts.
8 and other requirements
Bearing steel material specifications of bearing steel smelting method, oxygen content, annealing hardness, fracture, remaining elements, sparks inspection, delivery status, logo, etc have strict requirements.
Other News:
High quality NSK bearing the smelting of imported material requirements
Conflicts between supply and demand of the endorsement steel mill ＂to＂
Bearing steel smelting quality basic requirements
Experts say six months at any time the bounce of the endorsement may
Maximize NTN import the service life of the bearings
INA plastic bearing noise test methods
Steel exports than expected the price is possible
North Korea says the military already aimed at South Korea and media won't apolo
