Bearing steel is mainly used for manufacture of rolling elements of rolling bearings and rings. Due to the bearings should have a long life, low heat, high speed, high precision, high rigidity, low noise, high abrasion resistance and other characteristics, and asked for bearing steel should have: high hardness, even high hardness, high elastic limit, must contact fatigue strength, toughness, a certain degree of hardenability and corrosion in the air lubricant performance. In order to achieve the above performance requirement, chemical composition of bearing steel by uniformity, non-metallic inclusion content and type, carbide particle size and distribution, removal and so demanding. Bearing steel to high quality, high performance and overall direction. Bearing steel of the characteristics and application of environmental groups: high-carbon chromium bearing steel, high temperature bearing carburizing steel, bearing steel, stainless steel and special materials special bearing.
To adapt to the high temperature, high speed, high load, corrosion resistance, resistance to radiation requirements, developed a series of new bearing steel with special properties. In order to reduce the oxygen content in bearing steel, developed a vacuum melting, electroslag remelting, bearing steel smelting, such as electron beam remelting technology. Large quantities of bearing steel smelting electric arc furnace smelting, develop into various types of furnace smelting and refining at the beginning. At present, the furnace +LF/VD or RH+ the beginning of greater than 60 tons + of continuous casting and rolling production of bearing steel in order to achieve the objective of high quality, high efficiency and low energy consumption. In the heat treatment process, from car-hearth furnace, Bell-type annealing furnace developed into continuous controlled atmosphere annealing furnace for heat treatment. At present, for a maximum continuous heat treatment furnace 150m, processing and production of bearing steel ball of tissue stability and uniformity, decarburized layer of small, energy consumption is low.
Since in the 1970 of the 20th century, as economic development and industrial technology, extending the application of bearing and the development of international trade, also contributed to the internationalization of standard bearing steel and new technologies, the development and application of new technology and new equipment, high efficiency, high quality, low cost technology and process equipment came into being. Japan and Germany, which built the high cleanliness degree, high quality bearing steel production, steel production has increased rapidly, quality and generosity to improve fatigue life of steel. Japan and Sweden content of bearing steel production fell to 10ppm. The late 80 's, Japan Sanyo special steel company's advanced level of 5.4ppm, reached the level of vacuum remelted steel.
Contact fatigue life of bearing steel uniformity is very sensitive. Improving cleanliness (reduced content of impurities and inclusions in steel), non-metallic inclusions in steels and carbides evenly distributed small, can increase the contact fatigue life of bearing steel. Bearing steel using State organizations should be distributed evenly tempered Martensitic matrix small carbide particles, such organizations can give the required performance bearing steel. High carbon bearing steel is the main alloying elements are carbon, Silicon, manganese, chromium, vanadium, and so on.
Access to ball organizations is important in the production of bearing steel issues, advanced bearing steel of controlled rolling and controlled cooling is an important production technology. Through rapid cooling after controlled rolling or rolling eliminates network carbide, appropriate preparation organizations available, can shorten the bearing steel with spheroidal annealing time, granular carbides, improving fatigue life. According to the bearing Exchange specialist investigation, in recent years, Russia and Japan controlled rolling at low temperature (~ 800 ℃ below 850 ° c), air cooled with short time annealing after rolling, or complete cancellation of the spheroidizing annealing technology, you can get qualified for bearing steel. 650 ° c temperature processing is also new technology of bearing steel. Eutectoid steel and high carbon steel heat before processing has a fine grain structure or process to form a fine grain, (0.4~0.6) within the melting temperature to a certain strain rates, showing a surplus of plastic. United States Naval Institute (NSP) temperature 650 ° c to 52,100 steel processing test showed that at 650 ° c, really strain 2.5 does not break. Therefore, it is possible to processing instead of the high temperature of 650 ° c temperature and together with spheroidizing annealing process, simplify equipment and processes, energy conservation, improvement of quality is important.
In terms of heat, improving the quality of spheroidizing annealing, access to small, uniform, spherical carbon and reducing annealing time or cancel the spheroidizing annealing process of research in progress, annealing of wire rod production both organizations, will be drawn after 720 ° c ~730 ° c annealing recrystallization annealing 760 ° c instead of organization. To achieve low hardness, ball, no network carbide organization, key to ensure that the Middle drawing area reduction is more than 14% the process efficiency of heat treatment furnace 25%~30%. Continuous spheroidizing annealing heat treatment technologies are the development direction of bearing steel by heat treatment.
All countries in research and development of new type of bearing steel, expand and replace conventional bearing steels. Rapid carburizing steel, by changing the chemical composition to speed up carburizing, carbon content increased by traditional 0.08%~0.20% to around 0.45%, carburizing time up to 7 hours and 30 minutes. Developed high-frequency hardened bearing steel, carbon steel or carbon manganese, chromium in ordinary, to replace ordinary bearing steel by high-frequency hardening, simplifying production processes, reduces costs, and increase service life. Japan Research GCr465, SCM465, 2~4 times higher fatigue life than the SUJ-2. Due to in high temperature, and corrosion, and lubrication conditions bad of environment Xia using bearing more and more, past using of M50 (CrMo4V), and 440C (9Cr18Mo), bearing steel has cannot meet using requirements, needed development processing performance good, and cost low, and fatigue life long, and can for different purpose and uses of bearing with steel, as high temperature carburizing steel M50NiL, and easy processing not rust bearing steel 50X18M and ceramic bearing material,.
GCr15SiMn weaknesses in the steel hardenability low, developed high hardenability and hardenability of bearing steel in China GCr15SiMo, hardened HRC ≥ 60, hardenability J60 ≥ 25mm. GCr15SiMo of contact fatigue life L10, L50 GCr15SiMn raising and 73% respectively, under the same conditions of use, with G015SiMo made of steel bearing service life is twice times the GCr15SiMo steel. In recent years, China has developed to save energy and conserve resources and impact-resistant GCr4 of bearing steel. GCr15, GCr4 shock value had increased 66%~104%, 67% increase in fracture toughness, a 12% increase in contact fatigue life L10. GCr4-steel bearings with high temperature heating surface hardening heat treatment process. Compared with the deep hardening steel GCr15 bearing, GCr4 steel bearing life increased significantly, high-speed trains can be used to overload the bearings.
Bearing steel mainly to the future development of high cleanliness and diversification in both directions. Improve steel cleanliness, especially in reducing oxygen content in steel, you can significantly extend the life of the bearing. Oxygen content by 28ppm down to 5ppm, life can be extended by 1 order of magnitude. In order to extend the life of the bearings, it has for many years been committed to the development and application of refining technology to reduce the oxygen content in steel. Through unremitting efforts, the minimum oxygen content in bearing steel have been reduced from 28ppm in in the 1960 of the 20th century to 90 5ppm. At present, the minimum oxygen content in bearing steel can be controlled at around 10ppm. Bearing environments change request must have the properties of bearing steel variety. As equipment speed of improve, needs associate high temperature with (200 ℃ following) bearing steel (usually used in SUJ2 steel of based Shang improve Si content, and added v and Nb of method to reached anti-softened and stability size of purpose); corrosion application occasions, needs development not rust bearing steel; to simplified technology, should development high frequency quenching bearing steel and short Shi carburizing bearing steel; to meet aviation space of needs, should development high temperature bearing steel.
Other News:
Analysis of bearing steel technology and the future development
The bearing heater composition and working principle
Needle roller bearings to clearance requirements
Sliding bearing technology and applications in the automotive industry
The outer ring of the bearing is separable from
Factors affecting the longevity of angular contact ball bearings
Spherical plain bearing rod end maintenance of focused analysis
Fixed bearing inner ring
