中锰钢ART工艺C、Mn元素配分的热力学研究

Thermodynamics of C and Mn element partitioning during austenite reverted transformation in medium manganese steel

利用Thermo-Calc软件对0.1C-7.2Mn中锰钢奥氏体逆转变(Austenite reverted transformation,ART)过程中C、Mn元素配分的热力学过程进行模拟,并根据结果进行了ART工艺的热处理试验。热力学计算和试验结果表明,当退火温度为640℃时,C、Mn在奥氏体中含量均高于680℃时的含量,在配分初始阶段,C在奥氏体中的质量分数迅速达到最高点0.87%,在由Mn元素控制界面移动的过程中,Mn在奥氏体中的质量分数接近10%;C原子配分控制的界面移动平均速率达2.5×10^(-4)m·s^(-1),主导的界面迁移占总迁移距离的46.9%;而由Mn元素配分控制的界面移动速率仅为2.5×10^(-12)m·s^(-1),迁移距离占总迁移距离的53.1%;当试样在640℃保温30 min时,残留奥氏体的体积分数达到36.5%,抗拉强度为1041 MPa,并且强塑积达到24.36 GPa·%。

Thermodynamic process of C and Mn elements partitioning in austenite reverted transformation(ART)process of 0.1 C-7.2 Mn medium manganese steel was simulated by Thermo-Calc software,and the heat treatment experiment of ART process was carried out according to the results.Thermodynamic calculation and experimental results show that when the annealing temperature is 640℃,the content of C and Mn in austenite is higher than that at 680℃.In the initial stage of partitioning,the mass fraction of C in austenite quickly reaches the highest point of 0.87%.In the process of interface movement controlled by Mn element,the mass fraction of Mn in austenite is close to 10%.The average rate of interface movement controlled by C partitioning is 2.5×10^(-4)m·s^(-1),the interface migration controlled by it accounts for 46.9% of the total migration distance.The interface movement rate controlled by Mn partitioning is only 2.5×10^(-12)m·s^(-1),the migration distance accounts for 53.1% of the total migration distance.When the specimen is kept at 640℃ for 30 min,the volume fraction of retained austenite reaches 36.5%,the tensile strength is 1041 MPa,and the product of strength and elongation reaches 24.36 GPa·%.