The Study On Wear Behavior And Mechanism Of Martensite-austenite Dual-phase Microstructure

The wear resistance of steel materials is an important factor which affecting the working efficiency and service life of mechanical products.At present,the wear-resistant steels mainly develop in the direction of high strength and high hardness at home and abroad.However,simply increasing the hardness of the base material limits the improvement of other mechanical properties of the steels and restricts the development of the wear resistant steels.Therefore,the new idea of steel development is to improve the wear resistance of the material without increasing the hardness.Different austenite content and different types of martensite-austenite dual-phase microstructure were designed by deformation-induced and temperature-induced,based on SUS321 austenitic stainless steel.The wear properties and wear mechanism of metastable austenitic steels with different hardness under different wear conditions were studied.The main research content and results are as follows:(1)In view of SUS321 austenitic stainless steel with the austenite content of 97%at room temperature,deformation-induced martensite-austenite dual-phase microstructure and temperature-induced martensite-austenite dual-phase microstructure with different phase percentages were obtained by means of both deformation control and temperature control.(2)The micro structure and mechanical properties of the obtained austenite-martensite dual-phase steel were characterized by XRD,optical microscope,macroscopic hardness tester and tensile tester.The results show that as the degree of deformation increases,the austenite phase change monotonically increases,the hardness value increases monotonically,the tensile strength increases monotonically,and the elongation decreases monotonically.During cryogenic treatment processing,the martensitic transformation is not only a function of temperature,but also a function of time.With the extension of the cryogenic treatment,the martensitic transformation increases,the hardness increases,the tensile strength increases and the elongation decreases.(3)The wear behavior of martensite-austenite dual-phase steel with different percentages induced by deformation-induced and temperature-induced was studied by G65 abrasive wear test.The results show that the content of austenite and martensite in dual-phase steel has a significant effect on the wear resistance of steel.With the gradual reduction of austenite content in dual-phase steel,the wear rate decreases first and then increases.There are residual austenite content ratio of the best wear resistance.And material wear resistance and hardness is not a single linear relationship.Experiments show that it is possible to improve the wear resistance and reduce the wear rate of materials by introducing a certain amount of relatively soft metastable austenite without sacrificing other mechanical properties.(4)The G99 ball-on-disc rotation wear test was used to analyze the wear resistance of different phases of martensite-austenite dual-phase steel during different stages of wear induction.The results show that in the initial stage of wear:the material is in the running-in stage,the wear performance is not stable.The wear resistance of the material is greatly affected by the matrix structure.When in stable wear stage,the wear performance is mainly affected by the metastable austenite.With the gradual reduction of austenite content in dual-phase steel,the wear resistance decreases first and then incr-eases.There is the best proportion of retained austenite with the best wear resistance.The result is in good agreement with that of G65 abrasive wear test.(5)The reasonable and effective analysis of the specific wear mechanism of the material wear surface by scanning electron microscopy,topography and micro-hardness tester:The G65 abrasive wear surface creates a large number of furrows with a certain direction and they are consistent with the wear direction as a whole.Surface wear mechanism is mainly micro-furrow and micro-cutting mechanism.Slight plastic deformation occurs on both sides of the furrow,accompanied by the debris stripping from the worn surface and pit caused by quartz sand The wear process forms a different thickness hardened layer on the worn secondary surface.This is due to the metastable austenite transformation or deformation accumulation during wear process.