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通过理论计算并结合实验研究了低碳Nb微合金钢中NbC析出相与Nb固溶原子共同作用对再结晶后奥氏体晶粒长大的影响.结果表明,Nb的溶质原子拖曳与NbC析出相钉扎共同作用阻碍晶粒长大晶界的迁移,高温时NbC析出相的钉扎起主要作用,Nb的溶质拖曳效应并不明显,而相对低温时Nb拖曳对晶粒长大产生明显地抑制作用,理论计算与实验结果吻合良好;溶质原子拖曳和析出相的钉扎对抑制晶粒长大的效力可以用p因子来表征,当p=0时,以NbC析出的Nb与固溶Nb的量之比达到最优,抑制晶粒长大效果最好,当p>0时,析出相的钉扎能更有效地阻碍晶粒长大,而p<0时,溶质原子的拖曳对抑制晶粒的长大更有效;在常规热轧温度区间或者奥氏体化温度区间内,只有尺寸不大于10 nm的细小的NbC析出相对再结晶后的晶粒长大才能起到较好抑制作用.
The effects of the NbC precipitates and the Nb solid solution atoms on the austenite grain growth in the low carbon Nb microalloyed steel were studied theoretically and experimentally.The results show that the solute atom drag of Nb and the precipitation of NbC Pinning together hinders the migration of grain growth grain boundaries, NbC precipitating phase pinning plays a major role at high temperature, solute drag effect of Nb is not obvious, and relatively low temperature Nb drag grain growth significantly Inhibition, the theoretical calculation is in good agreement with the experimental results. The effect of pinning of solute atoms on precipitation and grain growth inhibiting grain growth can be characterized by p-factor. When p = 0, Nb precipitated with NbC and dissolved Nb , The best effect of the amount of inhibition of grain growth is the best, when p> 0, the precipitation of pinning more effectively hinder the grain growth, and p <0, the solute atom drag inhibition The growth of grains is more effective. In the conventional hot rolling temperature range or austenitizing temperature range, only the size of fine NbC less than 10 nm precipitation relative to the recrystallized grain growth in order to play a better inhibitory effect .