During the operation of rolling bearings, there is point contact or line contact between the bearing rings and rolling elements, which bear concentrated alternating loads (the contact stress can reach up to 5000 MPa and the number of stress alternations can reach hundreds of thousands of times). Under high-speed operation, there is both rolling friction and sliding friction, with occasional impact loads, and the bearings are also subject to corrosion from the atmosphere and lubricants. Therefore, rolling bearings operate under harsh and heavy-duty conditions, and fatigue spalling and wear are their primary failure modes.
1.It shall have high contact fatigue strength, as well as high and uniform hardness and wear resistance, to withstand alternating loads and friction loss.
2.It shall possess high elastic limit and yield strength to prevent excessive plastic deformation of bearing parts under high loads and ensure structural stability.
3.It shall have a certain degree of toughness to enhance the resistance to impact loads and avoid fracture or other damage to the bearings caused by sudden impacts.
4.It shall have good dimensional stability to ensure that precision bearings maintain their high-precision dimensional parameters during long-term storage and use.
5.It shall have a certain corrosion resistance to resist corrosion from the atmosphere and lubricating oil. For bearings working under special conditions, they shall also meet the special performance requirements such as high temperature resistance, low temperature resistance and strong corrosion resistance.
1.Chemical composition design: The mass fraction of carbon is controlled within the range of 0.95%~1.15%. The main alloying elements added to the steel include Cr, Mn, Si, V, Mo and rare earth elements. These alloying elements can effectively improve the hardenability and tempering stability of the steel. After heat treatment, the steel can simultaneously have high strength, high hardness, high wear resistance and excellent contact fatigue strength.
2.High purity requirement: It has strict standards for steel purity, and the aggregation of non-metallic inclusions such as oxides and sulfides in the steel is strictly prohibited. Such inclusions are likely to become the source of fatigue crack initiation, which greatly reduces the service life of bearings.
3.Uniformity of structure and composition: It has extremely high requirements for the uniformity of steel structure and chemical composition. Defects such as uneven carbide distribution, internal porosity and composition segregation will seriously affect the mechanical properties of bearings and significantly shorten their service life.
Baoshan District,
Shanghai, China.
