Research On Thermal Deformation Behavior Of 100Cr6 Bearing Steel

100Cr6 steel is a kind of high carbon chromium bearing steel.After quenching and tempering,due to the uniform composition and microstructure,it has good comprehensive mechanical properties,such as high strength,high hardness,and strong wear resistance etc.Meanwhile,100Cr6 bearing steel has good toughness,good tempering stability,and small heat treatment distortion,so it is widely used in high-speed rail,automobiles,ships and other transportation areas.Therefore,it is very meaningful to study the hot deformation behavior and microstructure of 100Cr6 bearing steel.In this paper,the 100Cr6 bearing steel was subjected to hot compression deformation on the Gleeble-3500 thermal simulation tester.Then the effects of deformation temperature and strain rate on flow stress were studied,and the microstructure of 100Cr6 bearing steel was observed on Optical microscope and scanning electron microscopy.Finally the reasonable hot processing parameters of 100Cr6 bearing steel were obtained,which provide material parameters for forging numerical simulation of bearing steel.The main research contents and results are as follow:1.The hot deformation behavior of 100Cr6 bearing steel,at deformation temperature of 850??1150?,strain rate of 0.01s-1?10s-1 and true strain of 0.7,was studied on the Gleeble-3500 thermal simulation tester.The classical constitutive equation of the bearing steel was obtained,and the thermal deformation activation energy of the bearing steel is 298.832 kJ/mol.In order to broaden the scope of application of the constitutive equation,the Arrhenius hyperbolic constitutive equation with strain compensation was obtained.2.During hot compression deformation,the flow stress of 100Cr6 bearing steel decreases with the increase of deformation temperature at the same strain rate,but increases with the increasing of strain rate at the same deformation temperature.Meanwhile at same low strain rate of 0.1s-1,dynamic recovery of the material occurs at 850? and 950? deformation temperature,but dynamic recrystallization happens at 1050? and 1150.3.Based on the dynamic material model and Prasad instability criterion,the dissipative efficiency values of 100Cr6 bearing steel under different strains were obtained,with a maximum value of 0.44.Then the thermal processing map with strain interval difference of 0.2 was obtained,and the reasonable parameters of the 100Cr6 bearing steel hot deformation were obtained as deformation temperature of 1050?and strain rate of 0.01s-1 by analyzing the map.4.The microstructure of hot-pressed 100Cr6 bearing steel was observed,and the microstructure after high-temperature quenching was mainly quenched martensite +trace residual carbide and trace retained austenite.With the increase of the deformation temperature,the size of the needle-like martensite in the metallographic structure gradually becomes larger.When martensite increases to a certain size,its size tends to be stable.