The Study On Microstructure And Properties Of Wear Resistant And Fatigue Of 13Cr4Mo4Ni4V Bearing Steel

The metallographic microscope,SEM,TEM and other characterization methods were used to observe and analyze the microstructure,grain size,carbide and fracture morphology of the test steel in this paper.The heat treatment process was fixed,and the rotation bending fatigue test and the axial tensile compression fatigue test were performed.After carburizing and heat treatment,the structure and properties of the carburized layer were studied.The test steel after carburizing was subjected to wear tests,rotation bending fatigue tests and axial tensile and compression fatigue testsDifferent heat treatment processes were used to study the effect of solution temperature on grain size and the effect of tempering temperature on toughness.The results show that when the solution temperature is equal or lesser than 1070?,the carbides at the grain boundaries are basically insoluble,the volume fraction is 1.93%,the carbides are pinned to the grain boundaries,and the austenite grain growth is not obvious,and the size is within 49?m.When the solution temperature is equal or greater than 1080?,the grain boundary carbides dissolve obviously,and the austenite grains grow rapidly.The tensile strength and impact energy of the test steel is 1522 MPa and 14 J,when the quenching temperature is 1070? and the tempering temperature is 500?,respectively.The tensile strength and impact energy of the test steel is 1360 MPa and 56 J,respectively,when the tempering temperature is 550?.The fretting wear test(stroke 300?m)and the sliding wear test(stroke 700?m)of the test steel after carburizing were respectively performed.In fretting wear,the adhesive wear becomes abrasive wear as the test frequency increases and the contact stress is 2.047 GPa.Fatigue wear occurs at a test frequency of 20 Hz,and the inclusion particles on the surface promote the initiation and expansion of fatigue cracks and cause the substrate to peel off.When the test frequency is 20 Hz,the abrasive wear penetrates through the abrasive wear,and the fatigue wear disappears with the increase of contact stress.In sliding wear,when the contact stress is 2.047 GPa,the wear mechanism changes from slight abrasion to abrasive wear as the sliding speed increases.When the sliding speed is0.028m/s,the adhesive wear becomes abrasive wear as the contact stress increases,and adhesive wear is generated at 2.427 GPa.Under the same test conditions,fretting wear is more severe than sliding wear.Rotating bending fatigue tests were performed on the test steels and carburized test steels,the fatigue strength is 773 MPa and 1300 MPa,respectively,and carburizing treatment effectively improves the fatigue strength of the test steel.Carburizing treatment effectively improves the fatigue strength of steel.The fatigue life is increased with the decrease of the size of the inclusions.Different types of inclusions have different effects on fatigue life,and the Mg-Al spinel has a greater reduction in life than alumina.In addition,in the carburized sample,the inclusions with a size of 44.57?m or more will directly crack,and will not form fish-eyes.The test steels and carburized test steels were subjected to axial tensile and compression fatigue tests and the fatigue strength was 610 MPa.The fatigue life decreases with increasing stress and increases with decreasing inclusion size.The initiation location affects the morphology of the non-carburized area of the core.The core area of the sample is a cleavage fracture when initiation is on the surface,and the core area is a relatively smooth radial morphology with microcracks when initiation is on the core.The carburized layer has higher hardness and lower ductility,resulting in the actual stress of the carburized layer being greater than the test stress,while the actual stress of the core is less than the test stress.The fatigue life of the cracks in the carburized test core is higher.