Nb对奥氏体→铁素体相变动力学影响的模型

在热模拟实验中,通过奥氏体区不同时间的等温得到具有不同固溶Nb%、相同晶粒尺寸的奥氏体,然后以1~5 K/s冷速冷却至室温获得连续冷却膨胀曲线.在Rios理论推导基础上,开发了一种基于Johnson-M ehl-Avrami-Kolmogorov(JM AK)方程和可加性法则的建模方法.建立了不同固溶Nb%条件下的奥氏体→铁素体相变动力学模型,结果表明,固溶Nb%对指数n没有影响,而动力学参数k随着固溶Nb%的增加而减小,即固溶拖拽效应增强.

Modeling the Effect of Nb on Austenite→Ferrite Phase Transformation Kinetics

In thermal simulation tests， the austenite with the same grain size but different solute Nb% was obtained by holding at austenite region with various times. The dilation curve was recorded when the sample was cooled to room temperature with the cooling rate of 1~5K/s. Originating from Rios’ theoretical deduction， a modeling approach based on the JMAK(Johnson-Mehl-Avrami-Kolmogorov) equation and additivity rule was developed. The kinetic model of austenite to ferrite phase transformation under different solute Nb% was established. The results suggest that the exponential n is not affected by the solute Nb%， whereas the kinetic parameter k decreases with increasing solute Nb% that is an enhanced solute drag effect.