V-Nb-(Ti)微合金化钢奥氏体晶粒长大的动力学

Kinetics of austenite grain growth of V-Nb-(Ti) microalloyed steels

采用金相分析方法研究了V-Nb和V-Nb-Ti微合金化钢在不同加热温度下原始奥氏体晶粒长大的规律,并在此基础上,对其奥氏体晶粒生长动力学方程进行了数学回归分析。结果表明:随奥氏体化温度的升高,两种微合金化钢的奥氏体晶粒尺寸均呈现增加的趋势,其不均匀因子则呈现出先增大后减小的趋势。但V-Nb-Ti微合金化钢的奥氏体晶粒尺寸和不均匀因子的变化趋势均比V-Nb微合金化钢的平缓。V-Nb和V-Nb-Ti微合金化钢的奥氏体晶粒长大动力学方程均符合Beck方程。后者的奥氏体晶粒长大激活能20 kJ/mol稍大于前者19 kJ/mol。

A austenite grain growth behavior of two microalloyed steels,which were microalloyed respectively by V-Nb and V-Nb-Ti,respectively,at different austenizing temperatures were investigated by metallographic observation.The kinetic equations of austenite grain growth were established by regression analysis based on the experiment.The results show that with the increasing of austenitizing temperature,austenite grain sizes of the two microalloyed steels increase,while the uneven factors of the grain size increase first and then decrease.The changing degree of V-Nb-Ti microalloyed steel is smaller than that of V-Nb microalloyed steel in terms of size and uneven factor of the austenite grains.The kinetic equations of grain growth of V-Nb microalloyed steel and V-Nb-Ti microalloyed steel both accord with the Beck equation.The austenite grain growth activation energy of the latter,20 kJ/mol,is slightly higher than that of the former,19 kJ/mol.