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Spherical roller bearings heat treatment improperly what will happen?
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| Time：2016.11.01 News Sources：Shandong Xinkaite bearing Co.,Ltd. Views：
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Spherical roller bearings with two rows of rollers, the main radial load, but also can withstand any direction of the axial load. Has a high radial load capacity, especially for heavy duty or vibration load, but can not afford pure axial load. This type of bearing outer ring raceway is spherical, so the aligning performance is good, to compensate for coaxial error. But according to the technical staff said that if the self-aligning roller bearing heat treatment will have some impact, but in the end aligning roller bearing heat treatment improper what will happen, let us take this issue together to learn more about it!
1. Spherical roller bearings heat treatment deformation
Bearing parts in the heat treatment, there are thermal stress and tissue stress, the internal stress can be superimposed or partially offset each other, is complex and varied, because it can with the heating temperature, heating rate, cooling, cooling rate, part shape And the size of the change, so heat treatment deformation is inevitable. Understanding and mastering the law of its changes can make the deformation of bearing parts (such as ring oval, size, etc.) placed in a controllable range, is conducive to production. Of course, a mechanical impact during the heat treatment also causes deformation of the part, but such deformation can be reduced and avoided with improved operation.
2. Spherical roller bearings overheating
From the bearing parts rough mouth can be observed after quenching the microstructure of overheating. However, to determine the extent of overheating, the microstructure must be observed. If GCr15 steel in the quenching of coarse needle-like martensite, compared with the quenched superheat organization. May be due to the quenching temperature is too high or too long heat insulation time caused by the overall overheating; may also be due to the original organization of serious banded carbide, in the two low-carbon zone between the formation of local martensite needle thick, Resulting in local overheating. The residual austenite in the superheated tissue increases, and the dimensional stability decreases. As the quenched tissue overheating, the steel crystal thick, will lead to decreased toughness of parts, lower impact resistance, bearing life is reduced.
3. Spherical roller bearings less heat
Quenching temperature is too low or poor cooling will produce more than the standard in the microstructure of the organization of the body of torsite, known as the under-heated organization, which makes the hardness decreased abrasion abruptly reduced bearing life.
4. Spherical roller bearings soft spots
As the lack of heating, poor cooling, quenching improper operation and other reasons caused by the phenomenon of the local bearing parts hardness is not enough hardened soft spots known as the phenomenon. Bearing master WeChat: 2966884113 it as surface decarburization can cause the same surface wear resistance and fatigue strength of a serious decline.
5. Spherical roller bearing surface decarburization
Bearing parts in the heat treatment process, if it is heated in the oxidizing medium, the surface oxidation will occur on the surface of the carbon content of parts decreased, resulting in surface decarburization. The depth of the decarburized layer on the surface exceeds the final machined residual and the part is discarded. Determination of surface decarburization depth in the metallographic examination can be metallographic and micro-hardness method.
6. Spherical roller bearings quenching cracks
Bearing parts in the quenching process due to internal stress caused by the crack, said quenching cracks. The causes of this crack are as follows: the quenching temperature is too high or too fast cooling, thermal stress and metal mass changes in the volume of the stress is greater than the steels anti-breaking strength; work surface defects (such as surface micro-cracks or (Such as slag, severe non-metallic inclusions, white spots, shrinkage porosity, etc.) in the formation of stress concentration during quenching; serious surface decarburization and carbide segregation; parts quenched after the lack of tempering Or not timely tempering; in front of the process caused by cold punch stress is too large, forging folding, deep turning marks, sharp edges and other oil groove.
In short, the cause of quenching cracks may be due to one or more of the above factors, the existence of internal stress is the main reason for the formation of quenching cracks.
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