Heat treatment of bearing parts

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To determine exactly the extent of overheating must observe the microstructure. If coarse acicular martensite in GCr15 steel quenching organizations, compared with quenching overheating organizations. Formation may be due to the qu enching temperature or heated the insulation too long caused the comprehensive overheating; may also be due to the original organization banded carbide serious between the two belts.thrust roller bearings
Quenching cracks bearing parts in the quenching process due to internal stress of the formed crack said quenching cracks. This crack: quenching temperature or cooling too quickly, the organizations stress is greater than the volume change of the thermal stress and metal quality steel fracture resistance; original work surface defects (such as surface micro-cracks or scratches) or steel internal defects (such as slag, serious non-metallic inclusions, white point, residual shrinkage, etc.) quenching the formation of stress concentration and serious; bearing surface decarburization and carbide segregation; Quenching back inadequate or not timely tempering fire; too much stress to the previous process caused by cold punching, forging folding depth of the turning marks, oil groove sharp edges and corners. In short, the reasons causing quenching cracks may be one or more of the above factors, the presence of the internal stress is to form the main reason for the quenching cracks. Quenching cracks deep, slender, straight fracture, fracture surface oxidation color. It on the bearing rings often cracking; straightness of longitudinal cracks or annular shape of the S-shaped on the bearing balls,
Bearing parts in the heat treating process, if it is heated in an oxidizing medium, bearing surface oxidation occurs so that the decrease in the carbon mass fraction of the surface of the part, causing surface decarburization. Surface decarburized layer deeper than the final processing of the stay will make parts scrapped. Determination of surface decarburization depth available in metallographic method metallographic examination and microhardness method. Surface layer microhardne ss distribution curve measurement method prevail, do arbitration Criterion. Common quality defects of bearing parts after heat treatment: quenching microstructure overheating, due to thermal quenching cracks, hardness is not enough, heat treatment distortion, surface decarburization soft spot, bearing maintenance and repair methods. Overheating can be observed from the bearing parts rough port after quenching microstructure overheating.
The importance of the bearing, which means when it is damaged, can cause equipment downtime, so this type of bearing temperature probe should preferably be retrofitted. Under normal circumstances, the bearing just lubrication or re-lubrication after there will be a natural temperature rise and lasted one to two days.slewing bearing manufacturers
Typically, the working temperature above 150 ° bearings known as high-temperature bearings, chromium bearing steel its hardness to a sharp decline in the temperature exceeds 150 °, dimensional instability, so that the bearing is not working properly. Bearing working temperature of 150 ° to 350 °, if the rings and rolling elements still use ordinary carbon chromium bearing steel manufacturing, must be tempered special bearing parts, should generally be higher than the operating temperature 50 ° tempering. After processing by the above requirements tempering of bearing steel, at the operating temperature under normal use. But tempered hardness decreased, reduced bearing life. When the bearing operating temperature higher than 350 °, you must be using a high temperature bearing steel manufacturing.
Bearing temperature reasons:
A, bearing lubricant quality not the high viscosity of the lubricant;
2, institutions tight assembly, lack of space;
3, the bearing assembly is tight;
4, the bearing seat on the shaft or shell rotation;ball bearing companies
5, the bearing load is too large;
6, the bearing retainer or rolling element fragmentation.