钢板连续移动感应淬火温度场数值模拟及实验研究

Numerical Simulation and Experiment Research on the Temperature Field of Continual Induction Hardening for a Steel Plate

目的通过数值模拟,研究电源频率、电流密度、钢板移动速度对感应淬火过程中钢板温度场的影响规律,为实际应用中的参数选取提供参考。方法利用ANSYS APDL语言建立钢板连续移动感应淬火过程的有限元计算模型,对不同工艺参数下的钢板温度场进行数值模拟。以优化后的工艺参数对20 mm厚的40Cr钢板进行感应淬火实验,利用热电偶对钢板关键点温度进行测量,通过金相显微镜和显微硬度计对淬火后的钢板进行微观组织和硬度分析。结果钢板关键点温度计算结果与测量结果的最大误差率约为4%,表明该模型具有较高的计算精度。不同工艺参数下钢板温度场的分析结果表明:电源频率越高,电流密度越大,则加热速度越快,且随着电源频率的升高,高温区深度先增大后减小;而电流密度越大,钢板移动速度越慢,则高温区深度越大。钢板淬火后,其厚度方向上的微观组织基本上分为三个区:相变硬化区、热影响过渡区和未相变区。相变硬化区组织为细小的针状马氏体,最高硬度达700HV,淬硬层深度约6 mm;热影响过渡区中马氏体逐渐减少;未相变区仍保持原始珠光体和铁素体组织。结论模拟计算结果与实验结果基本吻合,可用来指导实际应用中的参数选取。

The work aims to investigate the effects of power frequency,current intensity and steel plate moving speed on temperature field of the steel plate during induction hardening by numerical simulation,to provide a reference for the selection of parameters in practical application.The finite element calculation model of continual induction hardening process for steel plate was established by ANSYS APDL language to simulate the temperature field of steel plate under different process parameters numerically.The induction hardening experiment was carried out to 20 mm thick 40Cr steel plate with optimized process parameters.The temperature of key point on the steel plate was measured by a thermocouple.The microstructure and hardness of quenched steel plate were analyzed by metallographic microscope and microhardness tester.The maximum error rate between the calculation results and the measurement results of key point temperature was about 4%,which indicated that the model had high calculation accuracy.The analysis results of the temperature field under different process parameters showed that:the higher the power frequency and current density were,the faster the heating speed was.With the increase of power frequency,the depth of high temperature region increased at first and then decreased.As the current density increased and the moving speed of steel plate decreased,the depth of high temperature region became large.The microstructure in thickness direction of steel plate after quenching was basically divided into three regions:phase transformation hardening region,heat affected transitional region and untransformed region.The microstructure of phase transformation hardening region was fine acicular martensite with the highest hardness of 700HV,and the depth of hardened layer was about 6 mm.The martensite in heat affected transitional region decreased gradually,while untransformed region was still original pearlite and ferrite.All the simulation results coincide with experimental results well,which can be used to guide the selection of parameters in practical application.