| This paper mainly studies the evolution of the organization structure of Fe-based materials during vacuum carburization,which is mainly divided into: vacuum tube furnace carburization and electromagnetic induction vacuum carburization.Regarding the carburization of vacuum tube furnaces: Numerical simulation study was conducted on the temperature rise,temperature distribution,phase distribution,grain change,hardness distribution,and stress changes of Fe-based samples,and a numerical model of carburization of vacuum tube furnaces was established.Process optimization provides a theoretical basis;through XRD,OM,SEM,EDS,3D morphology and hardness detection and analysis,combined with numerical simulation and experiments,systematically studied the evolution of Fe-based materials in the process of vacuum carburization.In terms of electromagnetic induction vacuum carburization: In order to obtain the ideal temperature field,three coil structures are designed,and the numerical model of the coil structure and temperature field is established,which provides a theoretical basis for the optimization of the electromagnetic induction heating temperature field;electromagnetic induction vacuum carburization It is an innovative collection of vacuum carburization and electromagnetic induction heating technology,that is a new type of carburization method that generates metal by joule heating through electromagnetic induction on the basis of vacuum carburization.The carburization method can significantly shorten the carburization cycle,and permeable layer structure is excellent.Secondly,for the metal substrate in the chemical heat treatment process,the electromagnetic field will play a beneficial role in promoting the adsorption and diffusion of activated carbon atoms and reducing the surface carbide aggregation.The mechanism of the influence of a variety of heating methods on tissue evolution and performance.In order to further clarify the mechanism of vacuum carburization,this paper,under the support of the National Natural Science Fund Project,used a combination of numerical simulation and experiment to study the evolution and performance of vacuum carburization.The details are as follows:1.Using DT2 steel as the experimental material,the purpose is to exclude the influence of other alloying elements on the vacuum carburizing process.Using DEFORM and JMat Pro software,the thermophysical parameters of DT2 steel and the hardness distribution,carbon concentration distribution,phase distribution,stress distribution and other aspects of the carburizing process of the vacuum tube furnace are studied in depth to analyze the evolution law of the carburizing structure of the vacuum tube furnace.It was found that the carbon concentration showed a zigzag rising curve with time.The carbon concentration of the cross section gradually decreased from the surface layer to the center and decreased to the matrix carbon concentration(0.01 wt%)at 4.5 mm from the surface layer.2.The reliability of the numerical simulation results is verified by the vacuum tube furnace experiment,and the evolution of the carburization structure of the vacuum tube furnace is further studied.The research shows that the numerical simulation results are consistent with the experimental results in hardness,phase distribution and carbon concentration trends,which verifies the reliability of the numerical model;there are obvious strip carbides in the sample cross-section and a large amount of loose block carbides in the surface layer,while infiltration The surface roughness before carbon is 274 nm and the roughness after carburization is 4 ?m.3.In order to obtain a reasonable temperature distribution of the sample for electromagnetic induction vacuum carburization,equal-coil coils,variable-pitch coils and variable-radius coils were designed,and the heating efficiency of the three coil structures and the different current frequencies and under the current density,the variation law of the axial temperature difference and the radial temperature difference of the sample,the reliability of the numerical model is verified by experiment,and the temperature change curve with time is nonlinear change,and the magnetic field density around the coil is dynamic change and variable radius coil reasonable temperature field can be obtained.4.Through the electromagnetic induction vacuum carburization experiment,study the evolution of the structure,and analyze the effect of two heating methods on the carburization structure and performance.The research shows that compared with the carburizing section of the vacuum tube furnace,the sample structure has no obvious strip carbides and the dense carbides formed on the surface have no loose structure.The surface roughness after carburizing is only 2 ?m. |
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