H13钢相变规律及其模具的真空热处理数值模拟

以H13钢热作模具真空淬火热处理组织演化预测数值模拟为目的,采用DIL805L热膨胀仪对H13热作模具钢进行连续冷却相变试验,结合显微组织和硬度绘制H13钢的连续冷却转变曲线(CCT曲线)。研究了不同冷速对试样显微组织和硬度的影响,对Koistinen-Marburger方程中相变因子进行拟合,研究了H13钢的相变规律。结果表明,马氏体转变的临界冷速为1 ℃/s,Ms点为335 ℃,随着冷速增大,试样硬度直至增大到660 HV。将拟合后的马氏体相变方程通过二次开发手段导入有限元软件中开展数值模拟计算,计算结果显示H13钢模具不同取样点处马氏体体积分数为90%,可认为真空气淬后H13钢模具的组织为马氏体和残留奥氏体。

Phase transformation law of H13 steel and numerical simulation of vacuum heat treatment for dies

Aiming at numerical simulation for microstructure evolution predicting of H13 hot work steel dies in vacuum quenching heat treatment, continuous cooling phase transformation tests were performed on the H13 steel by using DIL805L thermal dilatometer, and the continuous cooling transformation curve (CCT curve) of the H13 steel was plotted by combining microstructure and hardness results. The effect of different cooling rate on microstructure and hardness of the specimens was studied, and the phase transformation factors in the Koistinen-Marburger equation were fitted to investigate the phase transformation law of the H13 steel. The results show that the critical cooling rate of martensite transformation is 1 ℃/s, the Ms point is 335 ℃, and with the increase of cooling rate, the hardness of the specimen increases to 660 HV. By importing the fitted martensitic phase transformation equation into finite element software by secondary development means to carry out numerical simulation calculation, the results show that the volume fraction of martensite at different sampling points of H13 steel die is 90%. It can be considered that the microstructure of H13 steel die after vacuum gas quenching is martensite and retained austenite.