Research On The Influence Of Q-P-T Process And Thermal Deformation On The Properties Of 40Cr13

40Cr13 is a kind of martensitic stainless steel with high hardness after quenching.It has different strength and toughness combinations at different tempering temperatures.It is mainly used in CNC machine tools,medical equipment and rolling mill wear-resistant sliding plates.Among them,the stainless steel composite wear-resistant sliding plate coating adopts martensitic stainless steel,which has the advantages of high hardness and wear resistance.The current problem is that the hardness is not up to standard.In recent years,around the hardness of martensitic stainless steel is not up to the standard,a lot of research on the preparation process has been carried out,and many results have been obtained.However,currently only a few companies can produce industrialized products,and the development cost is relatively high.Greatly optimized space,there are problems that need to be solved urgently.In recent years,around the hardness of martensitic stainless steel is not up to the standard,a lot of research on the preparation process has been carried out,and many results have been obtained.However,only a few companies can produce industrialized products,and the development cost is relatively high.The greatly optimized space has problems that need to be solved urgently.The basic principle of the quenching-carbon distributiontempering(Q-P-T)process is that during the tempering process,the transfer of carbon atoms makes the retained austenite carbon-rich and stable,and at the same time promotes the precipitation of carbides to further improve the strength of the steel.In this paperthe Q-P-T heat treatment process parameters are changed to realize the control of the microstructure of 40Cr13 steel to ensure the strength and hardness of the material.At the same time,on the basis of the Q-P-T process,high temperature thermal deformation is introduced to simulate the effect of thermal deformation parameters on the microstructure.The experimental research and theoretical basis of the Q-P-T process,and then the experimental research on the method of combining different thermal deformation Q-P-T processes to explore the change law of microstructure and hardness.The main research content and research results of this article are as follows:(1)Through the thermal expansion experiment,the austenite transformation starting temperature of 40Cr13 is 823?,the complete transformation temperature is 890?,and the martensite starting temperature is 375?.The effect of different austenitizing temperatures on the microstructure of 40Cr13 steel is studied.The change.The austenitization process dissolves carbides,which ultimately affects the initial carbon concentration and retained austenite content in the carbon distribution process.The carbides are completely dissolved after being kept at 1100°C for 5 minutes.(2)The influence of the carbon distribution process on the microstructure evolution under different conditions is explored.The structure obtained by the Q-P-T process heat treatment is mainly a large amount of lath martensite,carbon-rich retained austenite and a small amount of carbides.carbon distribution At a temperature of 300?-600?,retained austenite will have a certain carbon-rich phenomenon.The activity of carbon atoms and the holding time of carbon distribution determine the carbon-rich degree of retained austenite and the amount of precipitated carbides.In the test,the strong plastic product obtained by quenching at 200°C and tempering at 400°C for 30 minutes reaches the maximum of23.94GPa·%,and the hardness of the steel reaches HRC60.2.(3)Through the finite element simulation of the high temperature dynamic recrystallization compression process,the influence of different deformation temperatures and deformation amounts on the grain size and recrystallization volume fraction after dynamic recrystallization was analyzed,and the deformation temperature was 950? and the deformation amount was 60%.At this time,the material undergoes complete dynamic recrystallization,the original grain size is between 70 ?m,nd the deformed grain size is about40 ?m.(4)Based on the simulation results,the deformation + Q-P-T heat treatment process experiment was carried out to explore the microstructure changes and mechanical properties analysis of the Q-P-T heat treatment combined with different deformation amounts.The experimental results show that the main structure is the same as the traditional Q-P-T process.The martensite,retained austenite and a small amount of carbides are multi-phase structure,but the austenite grain size is significantly reduced,and the hardness is slightly improved compared to the Q-P-T process.