Rolling bearing parts in the process of actual use, often in the tensile, compression, bending, shear, such as alternating complex stress state and under the condition of high stress value, high speed work long hours.
Choose rolling bearing materials is more appropriate are made, has a great influence on the its using performance and life will be.
Choose materials and the basic method is based on the destruction of the bearing (
Failure)
Form.
Under normal circumstances, the rolling bearing is the main damage form under the action of alternating stress fatigue spalling, and due to the friction and wear, which makes people lose the precision of the bearing, in addition, there is crack, pit, corrosion causes such as bearing abnormal damage.
Therefore, in general, rolling bearing should have high ability to resist plastic deformation, less friction and wear, good rotation accuracy, high dimensional accuracy, good dimensional stability, as well as the long contact fatigue life.
Performance and some of them are jointly decided by the material and heat treatment process.
Thus request manufacture of rolling bearing material after a certain heat treatment process after the following performance.
1 high contact fatigue performance of the rolling bearing during operation, the roller in rolling bearing between the inner and outer ring raceway, the contact part of its periodical alternating load, under the bulls tens or hundreds of thousands of times per minute.
In under the action of repeated periodic alternating stress, contact surface fatigue spalling.
Began to appear after peeling caused increase of bearing vibration, noise, temperature rising, the bearing fatigue damage and cannot be used in the end.
Contact fatigue damage is the main form of rolling bearing damage.
Therefore, for rolling bearing steel should be has high contact fatigue strength.
2 high wear resistance of rolling bearing in normal work, in addition to outside the rolling friction, accompanied by sliding friction.
The sliding friction of the main parts are as follows: the contact area between the rolling element and raceway, the contact area between the rolling element and cage pocket hole, keep the contact area and the guide ring guard, roller end face and ring rim contact area.
Rolling bearing in the existence of the sliding friction inevitably bearing wear parts.
If bearing steel wear resistance is poor, the rolling bearing will prematurely because of wear and tear because the precision of the loss of bearing or bearing rotating precision of the decline and increase the vibration of the bearing, life.
Therefore, requirements of bearing steel with high abrasion resistance.
3 high elastic limit of the rolling bearing is working, due to the contact area between the internal and external ring roller, bearing, especially under high load when the load cases, the contact surface contact stress is large, in order to prevent occur plastic deformation under high contact stress, so that the damaged bearing precision and surface cracks, so should have high elastic limit of bearing steel.
4 suitable hardness hardness, abrasion resistance to contact fatigue life, elastic limit has a very close relationship, so the hardness of rolling bearing is also a direct impact on the service life of rolling bearing, so the hardness is one of the important indexes of rolling bearing.
Rolling bearing hardness is usually according to the style and size of bearing the load, the general characteristics of the bearing size and wall thickness, hardness is too high or too low will affect the service life of bearing.
As we all know, the main failure mode of the rolling bearing contact fatigue damage;
Poor wear resistance or size instability caused by bearing accuracy loss;
Bearing parts lack a certain toughness, in brittle fracture under high impact load and lead to the destruction of the bearing.
Must be according to the actual circumstances of the bearing and to determine the hardness of bearing failure.
Over due to fatigue spalling damage or due to abrasion resistance difference result in the loss bearing accuracy of bearing parts, bearing parts should choose high hardness;
Under high impact load bearing (
For example, rolling mill bearings, bearing part of automobile, etc. )
, decrease the hardness to improve the toughness of the bearing is very necessary.
5 many bearing in the process of using a certain toughness under certain shock load, so the bearing steel has a certain toughness, to ensure the bearing damage due to withstand the shock load.
To bear a larger impact load bearing requirements such as rolling mill bearing, railway bearing material has a relatively high impact toughness and fracture toughness, some of these bearings with bainite hardening, either in carburizing steel, is to ensure that the bearing has good impact resistance performance.
6 good dimension stability of rolling bearing is precision mechanical parts, its precision is measured in microns.
In bearing long-term storage and use process, can't because of bearing parts organization or internal stress changes caused by the bearing size change resulting in accuracy loss of bearing.
Therefore, for bearing steel has good dimensional stability.
7 certain rust resistance because of the production process of rolling bearings is various, production cycle is long, some semi-finished or finished parts need a long time storage before assembly, as a result, the bearing parts in the process of production or easily happened in finished product save certain rust, especially in the moist air.
Therefore, the rolling bearing steel demand has certain rust resistance.
8 good process performance of the rolling bearing in the process of production, the parts need to pass more than cold and hot working process, which requires the bearing steel should have good processing property, such as cold and hot forming performance and machining performance, the performance of grinding, heat treatment performance, etc. , to adapt to the rolling bearing large quantity, high efficiency, low cost and high quality production needs.
In addition, for use under special working condition of bearing steel in addition to the above several basic request, also should have corresponding special performance requirements, such as high temperature resistance, high speed performance, corrosion resistance and non-magnetic.
