Bearing material and direction of development of heat treatment

1, improved smelting technology to enhance steel cleanliness and uniformity

Compared with the industrialized countries, China Although the oxygen content of bearing steel is close to the advanced level, but the inclusions and carbide size and distribution uniformity and composition uniformity and there is still a large gap between the foreign, such as the large-size The inclusions and carbides are more basic ingredients such as non-uniform formation of black and white areas, resulting in congenital deficiency bearing part quality, a serious impact on bearing life,ReliableAnd consistency.

In addition, the rolling contact surface of large-size inclusions in existence also seriously reduce the surface accuracy, increase the bearing noise. To this end, the bearings industry should consult with the metallurgical industry, metallurgical industry led to further reduce the oxygen content, based on the conduct casting solidification, rolling technology, inclusions control and detection techniques, such as improved continuous casting when the electromagnetic stirring, to increase the size of billet and strengthen high-temperature diffusion annealing, to enhance the inclusions and carbide size and distribution uniformity.

Second, the development and promotion of new steel grades to meet the requirements of the different bearing

As the host of small, lightweight,SpeedOriented, bearing the use ofEnvironmentMore diverse demands on the bearings increasing stringency of the existing steel our country can not meet or can not fully meet the requirements of the host of the bearing end, new materials should be actively pursued the development and promotion. Such as the development of large-size bearings used in high-hardenability of steel, heavy and clean lubrication conditions or under conditions of small lightweight steel bearings for use in polluted conditions, for use with high-carbon steel and carburization bearing steel, quasi-high-temperature ( Operating temperature 200 ¡æ below) under the conditions and special conditions with the bearing steel bearings used in steel (stainless steel, high temperature steel).

3, heat treatment and promotion of new technology

1. Bainite hardening

Austempering deal with the bearing due to the impact toughness is good, the surface compressive stress, both sets of cracks within the assembly, or the use of the process of coat ribs off blocks, the tendency within the set of fragmentation are greatly reduced, and can be lower edge of roller stress concentration. Therefore, bearing upon isothermal quenching than conventional quenching the average life expectancy and reliability improved significantly. The process is widely used in railway bearings, rolling mill bearings and bearings for use in special operating conditions. The process as compared with other life extension measures, process simple and low cost. In recent years, China has developed a new special steels GCr18Mo bainite hardening of steel, in order to promote bainite hardening in the large-sized bearing parts on the application. In view of the many advantages of the process, it is recommended the use of harsh conditions (large impact load, poor lubrication, etc.) or require high reliability of the bearings and promotion efforts, and further in-depth study of the wear resistance of bainitic treatment and fatigue life.

2. Surface carbonitriding

Luoyang Bearing Research Institute had carried out the 20th century, 80 years bearing steel quenching martensite stress research, through high-carbon chromium bearing steel parts with special quenching after carbonitriding and improve the surface of residual austenite content, improve the surface stress state, greatly increased the gearbox carbonitriding, but without compromising on the basis of improving the surface hardness of the surface retained austenite content in order to improve lubrication of bearings in polluted conditions, the fatigue life and reliability.

4, Surface Modification Technology

Through appropriate surface treatment to improve surface properties in order to meet the special conditions of the bearing performance requirements. Such as the use of vapor deposition technology in the diamond-coated bearings roll Road friction coating can be achieved, the effect of wear and greatly improve the wear life of bearings and precision to maintain performance, bearing in home appliances, computer hard drives bearing in promoting the application; using thermal coating technology in the bearings outside the out-group cylinder coated with alumina ceramic materials, can improve bearing performance of electrical insulation to prevent electrical injury and improve motor bearing life and reliability; in the bearing part surface or deposition of sulfide M0S2 antifriction lubricating effect can be achieved.