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通过金相显微镜、透射显微镜以及热力学软件研究了Nb元素在加热过程中对中碳钢奥氏体晶粒长大的影响。结果表明:由于Nb溶质原子的拖曳和含Nb析出物钉扎的综合作用,相同加热条件下含Nb钢的奥氏体晶粒尺寸要小于无Nb钢。随着加热温度的升高,无Nb钢的奥氏体晶粒尺寸基本呈线性增加,含Nb钢在1200℃以下晶粒生长较慢,当加热温度高于1200℃时,由于含Nb析出物的溶解以及生长驱动力突然增加,晶粒生长速度突然提高。
The effects of Nb on the austenite grain growth of medium carbon steel during heating were investigated by metallographic microscope, transmission microscope and thermodynamic software. The results show that the austenite grain size of Nb-containing steels is less than that of Nb-free steels under the same heating conditions due to the combined effect of Nb solute atoms’ drag and Nb-containing precipitates pinning. With the increase of heating temperature, the austenite grain size of Nb-free steel increases linearly. The Nb-containing steel grows slowly at 1200 ℃. When the heating temperature is higher than 1200 ℃, the Nb-containing precipitates The dissolution and growth of a sudden increase in driving force, the grain growth rate suddenly increased.