稀土对含铌钢中NbC在奥氏体区析出热力学的影响

Effect of rare earth on the thermodynamics of NbC precipitation in austenitic of niobium-bearing steel

在微合金元素与稀土相互作用系数的基础上,计算出加入稀土后实验钢中奥氏体区的NbC相应的固溶度积.计算了目标第二相的完全固溶温度,探讨了稀土作用下对奥氏体区目标第二相NbC的溶解行为所产生的影响机理.结果表明:稀土元素Ce和La分别加入钢中,均会使钢中奥氏体区NbC的平衡固溶度有一定提高,在一定程度上提高了NbC在奥氏体区的析出自由能.热力学分析显示,稀土元素对奥氏体区NbC的析出起阻碍作用,使其在奥氏体区的析出得到延缓.

Based on the interaction coefficient between the micro-alloy element and the rare earth,the corresponding solid solubility of NbC in the austenitic region of the experimental steel after adding rare earth was calculated.At the same time,the complete solidification temperature of the second phase of the target was also calculated.Then,the influence mechanism of rare earth on the dissolution behavior of NbC of the second phase of the target in the austenite region was discussed accordingly.The results showed that the addition of rare earth Ce and La lead to the improvement of NbC equilibrium solid solubility in the austenite zone of the experimental steel,and the free energy of NbC’s precipitation in austenitic region was improved to a certain extent.Therefore,from the thermodynamic point of view,the precipitation of NbC in austenitic region was hindered by rare earth elements,and its precipitation was delayed.