Jiaotong university results 丨 new ultra high carbon steel bearing

Jiaotong university results 丨 new ultra high carbon steel bearing 2020 - 01 - 02 ( Qingdao institute of xi 'an jiaotong university) Project introduction after decades of development, China has developed into bearing steel producer, production has been basically can meet the needs of the domestic market. But the quality of the domestic bearing steel with Swedish SKF, Japan still exists certain gaps when compared with advanced manufacturers such as sanyo, mainly is the extension of fatigue life. Attempts to extend the service life of bearing steel mainly include lower oxygen content and improve the cleanliness of steel; The surface modification treatment; And by exploring new heat treatment process to improve the fatigue life of bearing steel. However, through the above methods have a long life is not always able to meet the requirements, especially in the harsh conditions, such as high negative load when using, even more so, so has been have a need to develop a has a longer service life of steel. When the carbon content of steel is greater than zero. After 77% become hypereutectoid steel, hypereutectoid steel in casting state and normalizing, annealing state state of normal tissue is mesh the secondary cementite and pearlite. Cementite of high hardness, good wear resistance, increase the cementite significantly can improve the hardness and wear resistance of materials. But in mesh form is a major cause of lead to steel brittle, in order to reduce the brittleness, avoid more network cementite, the carbon content of bearing steel are generally less than 1. Around zero, higher carbon content will lead to subsequent forging, rolling hard to break large network cementite, will make the performance of the steel brittle. To broken network cementite in rolling and forging process have increased at the same time reduce the deformation temperature, deformation that increasing the process cost, waste of energy. This project puts forward the concept of ultra-high carbon steel bearing, the design and preparation of the carbon content in 1. 20 - 1. 31% ultra-high carbon steel bearing. Product performance advantages under the condition of optimum heat treatment process, the contact fatigue life of ultra-high carbon steel and the Swedish SKF - is a traditional GCr15 steel 3-3 bearing steel 5 times. To improve the performance of the reason: 1, under the condition of the same heat treatment hardness increase 2 - 3 HRC degree. 2, significantly enhanced. In the same heat treatment conditions, the average grain size is 6 of ultra-high carbon steel. 9μ M, while traditional GCr15 and SFK - 3 material grain to 13. 5μ M, refine the grain can improve strength and toughness. 3, resistant to tempering temperature increase. Under the same tempering temperature, hardness 2 - ultra-high carbon steel 3 HRC, so under the condition of the same hardness and tempering temperature can improve 50 - 100 ℃, it can fully release quenching stress. Technical maturity, on the basis of working in the laboratory, the project has carried out the experiment of industrialization, completed the preparation of small batch ultra-high carbon steel bearing, heavy card auto bearing sample processing and bench fatigue experiment of bearing products. Test results and the contact fatigue life of materials laboratory experiment results, at 0. 45 stress ratio under the condition of tested eight times rated life, traditional GCr15 bearing usually at 0. 35 stress ratio under the bench test 3 times lifespan. Has now completed the industrial scale ( 60 tons) Material melting, rolling, entered the stage of machining, after waiting for road test qualified will become a new generation of bearing steel material. The cost of the material GCr15 and its heat treatment process is the same, so no additional cost. After bench test, typical GCr15 bearing steel bearing and bearing material surface quality, surface quality of the new material in good condition, GCr15 bearing steel bearing surface yellowing, show that the bearing surface during operation the instantaneous temperature rises to more than 200 degrees. Project experts 【 Yong-ning liu. （ Institute of materials) 【 The research field 】 1) Phase transformation and mechanical properties of micro/nano materials; 2) A new generation of bearing steel and wear resistant steel research and development; 3) Hydrogen storage material. 4) Carbon nano materials; 5) A new generation of high-capacity lithium-ion batteries and battery technology; 6) Liquid fuel cell catalytic materials and battery technology.