18CrNiMo7-6钢渗碳仿真扩散系数模型的研究-《郑州大学学报(工学版)》

文章信息/Info

Title:: Study on Diffusion Coefficient of Carburizing Process Simulation of 18CrNiMo7-6 Steel

Author(s):: Qin Shengwei; Zhang Yufang; Zhang stick; Zhengzhou University Anti-fatigue Manufacturing Technology Henan Engineering Laboratory

Keywords:: DEFORM-HT software; 18CrNiMo7-6 steel; Carburizing simulation; Diffusion coefficient; alloy element; carbide

摘要:: 基于 DEFORM-HT软件，对18CrNiMo7-6 钢的气体渗碳工艺进行数值模拟：研究了两种不同的扩散系数模型对合金钢渗碳过程的影响，即考虑温度、碳原子的模型 D(T,C)和考虑温度、合金元素、碳原子的模型 D(T,M,C)并对3种不同渗碳层深度的渗碳工艺进行数值仿真以及试验验证。用机械剥层法测量３种渗碳工艺的碳含量沿深度的分布，并与仿真结果进行对比，发现采用 D(T,M,C)模型的仿真精确度更高；但当渗层深度达到4ｍｍ时，表层碳含量的试验结果与模拟相差较大，这是由于Cr、Mo等元素在长时间渗碳过程中与碳原子结合形成大量的碳化物，进而降低了碳原子的扩散系数，同时也导致试样的表层碳含量达到1.0％，高于渗碳工艺最后一段的环境碳势 0.8％。

Abstract:: Based on DEFORM-HT software, the gas carburizing process of 18CrNiMo7-6 steel was numerically simulated: the influence of two different diffusion coefficient models on the carburizing process of alloy steel was studied, that is, the model D(T, C) and the model D(T, M, C) considering temperature, alloy elements, and carbon atoms; and numerical simulation and experimental verification of three carburizing processes with different carburizing layer depths. The distribution of carbon content along the depth of the three carburizing processes was measured by the mechanical stripping method, and compared with the simulation results, it was found that the simulation accuracy of the D(T,M,C) model was higher; but when the carburizing layer depth reached When the thickness is 4 mm, the test results of the surface carbon content are quite different from the simulation, which is because elements such as Cr and Mo combine with carbon atoms to form a large number of carbides during the long-term carburizing process, which reduces the diffusion coefficient of carbon atoms. At the same time, the surface carbon content of the sample reached 1.0%, which was higher than the ambient carbon potential of 0.8% in the last stage of the carburizing process.