Cr-Mo-V高铁制动盘用钢的奥氏体晶粒长大行为

Austenite grain growth behavior of Cr-Mo-V steel for high speed railway brake disc

研究了在不同加热温度和保温时间下Cr-Mo-V系制动盘用钢的奥氏体晶粒长大行为,并采用光学显微镜以及截距法分析了加热温度和保温时间对钢的奥氏体晶粒尺寸和分布的影响。依据Thermo-Calc热力学计算软件计算了试验钢在400~1600℃范围内的析出相以及析出相的元素组成。结果表明:随着加热温度的升高,奥氏体晶粒尺寸不断增加,在850~900℃范围内,钢的奥氏体晶粒尺寸增长缓慢,晶粒较细小,950℃时奥氏体晶粒出现了异常长大现象,随后奥氏体晶粒快速长大。随着保温时间的延长,奥氏体晶粒尺寸也不断增加,但保温时间对奥氏体晶粒尺寸的影响比奥氏体化温度对奥氏体晶粒的影响小。结合扫描电镜分析,确定了本试验钢晶界处的析出相为V(C,N)。根据Sellars模型,确定了Cr-Mo-V试验钢的晶粒长大模型。

The austenite grain growth behavior of Cr-Mo-V steel for brake disc at different heating temperatures for different holding time was investigated, and optical microscopy and linear intercept method were adopted to study the effects of heating temperature and holding time on austenite grain size and distribution. Based on Thermo-Caic thermodynamic calculation software, the precipitated phases and their compositions were calculated in the range of 400-1600 ℃ for the experimental steel. The results show that the austenite grain size increases with the increase of heating temperature. When the experimental steel is heated in the range of 850-900 ℃, the austenite grain size grows slowly and the grains are relatively small. However, the abnormal grain growth appears at 950 ℃, and with the further increase of the heating temperature, the grain size of austenite grows quickly. It is also found that the austenite grain size grows slowly with the prolonging of the holding time, but the influence on the grain size of austenite caused by holding time is much smaller. With the help of scanning electron microscope analysis, it is confirmed that the precipitates at grain boundaries of the experimental steel are V （ C, N）. According to the Sellars model, the grain growth model of the experimental steel is established.