铌微合金化对高铁车轮钢奥氏体形核和长大的影响

发布时间：2018-03-30 21:32

  本文选题：车轮钢　切入点：逆相变　出处：《钢铁》2015年07期

【摘要】：针对碳质量分数为0.47%中碳高铁车轮钢,研究了铌微合金化对前驱体为铁素体-珠光体的组织发生奥氏体逆相变的影响。结果表明,铁素体-珠光体钢的逆相变是一个由碳原子扩散控制的过程,奥氏体优先在珠光体内的铁素体与渗碳体(α/Fe3C)片层界面处形核,并且沿平行于珠光体片层方向的长大速率比垂直于珠光体片层方向更快。含铌车轮钢细化的珠光体组织可以提高奥氏体的形核率,有利于细化奥氏体晶粒。随着再加热温度的提高,含铌车轮钢的奥氏体混晶温度(960℃)比不含铌的钢高80℃,因此通过铌微合金化可扩大再加热奥氏体化温度窗口。结合Thermal-Calc热力学计算和透射电镜分析,铌在中碳钢中主要以析出物的形式存在,析出钉扎作用是其细化奥氏体晶粒、推迟混晶现象出现的主要机制。
[Abstract]:The effect of niobium microalloying on the inverse austenitic transformation of the precursor ferrite pearlite was studied for the medium carbon high iron wheel steel with a carbon content of 0.47%. The inverse transformation of ferrite-pearlite steel is a process controlled by the diffusion of carbon atoms. The austenite nucleates at the interface between ferrite and cementite (伪 / Fe _ 3C) lamellar layer. And the growth rate along the direction parallel to the pearlite lamellar is faster than that perpendicular to the pearlite lamellar. The nucleation rate of austenite can be increased by the refinement of pearlite structure of niobium wheel steel. With the increase of reheating temperature, the austenite mixed crystal temperature of the wheel steel containing niobium is 960 鈩，

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