Analysis Of Surface Damage Behavior And Scuffing Failure Mechanism Of M50 Steel

M50 steel as high temperature and high speed bearing steel,is mainly used in the field of aeroengine.Its heat-resistant temperature of 315 ?,is the second generation of bearing steel.In the high-speed contact with metal friction,under high-speed heavy load conditions,the surface gluing failure is an important form of M50 bearing steel damage.Although foreign scholars have proposed some criteria for the failure of gluing failure,but it does not fully reflect the essence of gluing failure.Through the high-speed sliding experiment,this paper simulates the critical reference of the bearing failure in the high speed,heavy load and high temperature service.The micro-deformation behavior of the surface of the material is studied,and the mechanism of the formation and movement of the surface defects and the interaction between the microscopic defects and the grain boundary and the second phase particle are explained.And guide the application of M50 bearing steel engineering to prevent the failure caused by the failure of the glue.When the speed is low,scuffing is difficult to occur even under heavy load conditions;When the roll ratio increases,the relative sliding speed of the surface increases,the surface heat increases,it's more prone to cause scuffing.Lubricants mainly play a role in isolating the surface and heat dissipation.When the oil supply is insufficient or the oil temperature is high,the surface heating is accelerated and the scuffing is easy to happen at the time of heavy load.Under high temperature lubrication,the contact temperature can not be cooled as soon as possible.The ultimate load is lower than room temperature lubrication.When the scuffing occurs,there are many kinds of failure forms such as high plastic strain,shear instability,phase change,transfer,chemical reaction and mechanical mixing.Rapid surface of the existence of serious block and strip of avulsion and cracks,slow surface mainly for the serious adhesion and plastic deformation marksUnder the condition of dynamic and complex contact between the mechanical and thermal effects,the microstructure of the M50 surface of the scuffing injury is obviously changed.M50 bearing surface generated by the high temperature caused by a variety of phase changes,such as austenitizing,tempering effect.The main stress and shear stress of the contact area make the M50 surface plastic deformation and grain refinement.Under the combined action of stress and thermal effect,the surface forms a very brittle hardened layer.After the surface modification of the nitrogen ion implantation process,the surface hardness of the M50 steel is obviously improved,and the compressive stress is introduced into the surface to enhance the anti-gluing ability of the M50 bearing steel.After the nitrogen ion implantation,the plasticized damage zone has no plastic rheological layer,and the surface layer is less prone to temper softening.