钒含量对时速350 km高铁制动盘用Cr-Mo-V钢奥氏体晶粒长大的影响

Effect of V content on austenite grain growth of Cr-Mo-V steel for brake disc of 350 km/h high speed railway

基于Thermo-Calc热力学计算、光学显微镜、透射电镜和奥氏体晶粒长大模型计算,研究了不同V含量(0.13%、0.23%和0.34%)、奥氏体化温度及时间对高铁制动盘Cr-Mo-V钢奥氏体晶粒长大的影响,并分析了不同V含量下试验钢的Beck奥氏体晶粒长大模型与实际晶粒长大的偏差。结果表明,当奥氏体化时间为1 h、奥氏体化温度为950℃时,V含量的变化对晶粒长大没有明显影响;而奥氏体化温度高于950℃,奥氏体晶粒尺寸随着V含量的增加而逐渐减小。试验钢的奥氏体晶粒随着奥氏体化温度的升高逐渐长大,奥氏体化温度在1000℃以下时,晶粒尺寸随着奥氏体化温度的升高缓慢增加,而在1000℃以上,奥氏体晶粒随着奥氏体化温度的升高而急剧长大;相同的奥氏体化温度下,奥氏体晶粒随着奥氏体化时间的增加缓慢长大。利用试验测得的奥氏体晶粒尺寸并结合奥氏体长大动力学理论,计算出0.34%V试验钢晶粒长大动力学模型为■,经验证模型预测的数据与实际偏差很小,模型拟合度较好。

Based on Thermo-Calc thermodynamic calculations,optical microscopy,transmission electron microscopy,and austenite grain growth model calculations,the effects of different V contents (0.13%,0.23%and 0.34%),austenitizing temperature and time on austenite grain growth in Cr-Mo-V high speed railway brake disc test steel were studied.The deviation between the Beck model of grain growth and actual grain growth was analyzed under different V contents.The results show that when the austenitizing time is 1 h and the austenitizing temperature is 950℃,the V content has no obvious effect on the austenite grain growth.Nevertheless,above 950℃,the austenite grain size decreases with the increase of V content.The austenite grain sizes of the tested steel grow gradually with the increase of austenitizing temperature.When the austenitizing temperature is below 1000℃,the grain size increases slowly with the austenitizing temperature increasing,while when the austenitizing temperature is above 1000℃,the austenite grains grows rapidly.At the same austenitizing temperature,the austenite grains grow slowly with the increase of austenitizing time.Based on combination of the measured austenite grain size data and the theory of austenite growth kinetics,the kinetic model of grain growth of 0.34%V steel is calculated to be ■.The predicted data of the model has a small deviation from the experimental data,and a good model fitting.