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研究了含Nb高碳钢在高温均热阶段Nb对奥氏体晶粒生长的影响。结果表明,含Nb高碳钢在高温阶段的晶粒生长有两个阶段,奥氏体化温度低于临界温度Tc≈1150℃时,为缓慢增长阶段,奥氏体晶粒尺寸的变化很小,当奥氏体化温度高于Tc时,为快速生长阶段,晶粒直径随温度增加十分迅速;含Nb钢奥氏体晶粒快速长大的起始温度与弥散在基体中铌碳氮析出相数量有关,由高温阶段溶解于奥氏体中Nb数量所决定;奥氏体异常晶粒生长的临界析出粒径为一定值,不取决于加热前的析出状态。
The effect of Nb on the austenite grain growth of Nb-containing high carbon steels during high temperature soaking stage was studied. The results show that the grain growth of Nb-containing high carbon steels in high temperature has two stages. When the austenitizing temperature is lower than the critical temperature Tc≈1150 ℃, the grain size of austenite changes little at slow growth stage , When the austenitizing temperature is higher than Tc, the grain size increases rapidly with temperature for the rapid growth stage; the initial temperature at which the austenite grain grows rapidly in the Nb-containing steel and the precipitation temperature of the niobium carbonitride dispersed in the matrix The amount of phase is determined by the amount of Nb dissolved in the austenite in the high temperature stage. The critical precipitated grain size of the austenite anomalous grain growth is a certain value and does not depend on the precipitation state before heating.