低合金铜时效强化钢奥氏体化过程的动力学模型

Kinetic model of austenite grain growth in copper-bearing low alloy strengthening steel

通过高温金相试验,研究了一种船用低合金铜时效强化钢在不同加热温度和保温时间下的奥氏体晶粒长大行为和尺寸分布规律。结果表明:随着加热温度的升高,奥氏体晶粒尺寸逐渐增大,并且在不同的温度区间,奥氏体晶粒具有不同的长大速度。随着保温时间的延长,奥氏体晶粒也逐渐长大,但加热温度越高,奥氏体晶粒长大速度越快。各加热温度及保温时间下奥氏体晶粒尺寸呈对数正态分布,且随着加热温度升高或保温时间延长,对数正态分布曲线峰值横坐标右移,峰值频率下降。通过对试验数据进行回归分析,建立了适用于本钢种的奥氏体晶粒长大的动力学模型,模型计算值与试验值吻合较好,平均相对误差小于5%,所建立的模型具有较高的精准性和可靠性。

The behavior of austenite grain growth process and grain size distribution of copper-bearing low alloy strengthening steel were investigated at different heating temperatures and holding time using the confocal laser scanning microscopy. The results demonstrate that as the heating temperature increases, the austenite grain size gradually increases, and in different temperature ranges, the austenite grains have different growth rates. As the holding time increases, the austenite grains gradually grow, but the higher the heating temperature, the faster the austenite grains grow. The distributions of austenite grain size under different heating temperatures and holding time all exhibit a typical logarithmic normal distribution, whose average peak abscissa and frequency varies with heating temperature or holding time. On the basis of experimental data, a kinetic model for austenite grain growth of the tested steel is established using regression analysis. The results predicted from the kinetic model are in good agreement with the experimental ones, and the average relative errors between them are less than 5%. Therefore, it can be concluded that the established kinetic model has high accuracy and reliability to predict the austenite grain growth of the tested steel.