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利用微合金析出物与临界晶粒尺寸的定量关系,研究了Si含量较高的中碳Nb微合金钢在不同加热温度下的奥氏体晶粒长大规律。结果表明,随着加热温度的升高,试验钢中奥氏体晶粒逐渐长大,当温度高于1100℃时,晶粒开始粗化。由经验模型可得,随着温度的升高,析出相的体积分数逐渐减少,而颗粒半径逐渐增大,由于二者的共同作用导致了奥氏体晶粒在高于1100℃时迅速粗化;在实验的基础上,得到了适用于试验钢的晶粒长大模型。
Based on the quantitative relationship between the micro-alloy precipitates and the critical grain size, the regularity of austenite grain growth at medium heating temperatures was investigated for medium carbon Nb microalloyed steels with high Si content. The results show that as the heating temperature increases, the austenite grains in the test steel gradually grow up. When the temperature is higher than 1100 ℃, the grains begin to coarsen. From the empirical model, as the temperature increases, the volume fraction of precipitated phase decreases and the radius of the particles increases gradually. As a result of the combination of the two, the austenite grains rapidly coarsen above 1100 ℃ On the basis of the experiment, the grain growth model for the test steel was obtained.