Research On Wear Resistance And Fatigue Behavior Of BG800 Bearing Steel

With the development of aerospace technology,bearing steel is required to have high strength and toughness,high surface hardness,high wear resistance and high fatigue resistance.BG800 bearing steel,as a carburized high temperature stainless bearing st eel,can meet the needs of increasingly complex service environments.The complex wear phenomenon and fatigue behavior caused by high alloy content and multiphase structure in steel are analyzed,based on the adjustment of structure and performance,this p aper carries out friction and wear test and rotating bending fatigue test of carburized steel,studying the friction and wear performance of steel,exploring its wear mechanism and wear mode;study the rotating bending fatigue performance of steel,explore the factors affecting the fatigue performance of steel,and reveal the fatigue crack initiation and growth mechanism of steel.The research on the controlled microstructure and performance of carburized high-temperature stainless bearing steel show s that the test steel obtains better comprehensive mechanical properties after proper heat treatment.The tensile strength,yield strength,impact toughness and hardness are 1913MPa,1523MPa,and53J,and 52.1HRC respectively.The microstructure of steel i s lath martensite,retained austenite and M6C and M2C carbides.The size and quantity of M6C and M2C carbides have a significant impact on the properties of steel.The carburized layer depth of friction and wear specimens and fatigue specimens of steel rea ched1.4mm and 0.8mm,respectively,the carbides were mainly M23C6 and M6C,and the surface compressive stress of fatigue specimens reached 408MPa.The friction and wear performance and micro-mechanism test results of carburized high-temperature stainless bearing steel show that:the load force increases,the friction coefficient decreases in the stable wear stage,the wear mode changes from adhesive wear to adhesive wear and M23C6 particle abrasive wear,and the wear volume increases significantly;the sliding speed increases,the wear pattern does not change,and the wear volume increases slowly;the model of wear power consumption and wear volume based on the loading force and sliding speed is established V=2.83 F^{1.5 5}vt.The calculated value of the model i s in good agreement with the experimental test data.As the loading force increases,the wear volume increases exponentially.As the sliding speed increases,the wear volume increases linearly.Rotating bending fatigue test results of carburized high-temperature stainless bearing steel with different surface processing precisions show that the surface processing precision of steel specimens Ra is 1.616?m,the median fatigue strength reaches 913.3MPa,and the main crack initiation method of fatigue fracture is surface defects.And the subsurface carbides started to crack,accounting for 71.4%and28.6%,respectively.The surface machining accuracy of the steel specimens Ra is0.545?m,and the median fatigue strength reaches 1027MPa.The initiation mode of fatigue fracture is mainly internal carbide and surface notch initiation distribution accounting for 70.6%and 23.5%.The number of cycles and the stress intensity factor are related to the characteristic size of surface defects and bearing stress.The shape of deep furrows involves stress concentration and directly affects the number of fatigue cycles.The area of GBF zone is positively correlated with the number of cycles.The lower the stress intensity factor of initiating cracks,the higher the fatigue life.