Fe-4Mn-1.5Al-0.5Si-0.2C-0.05Nb中锰钢的热变形行为研究

Research on hot deformation behavior of Fe-4Mn-1.5Al-0.5Si-0.2C-0.05Nb medium Mn steel

针对较高Mn含量会导致中锰钢成本提高、出现偏析而限制其应用的问题,设计了一种能够满足1000 MPa级别性能要求(抗拉强度R_(m)>1000MPa,总伸长率A>30%)的中锰钢,其成分为Fe-4Mn-1.5Al-0.5Si-0.2C-0.05Nb。通过绘制实验钢在不同应变速率和变形温度下的真应力-真应变曲线,并结合组织观察,研究了实验钢的热变形行为,尤其是应变速率和变形温度对实验钢热变形行为的影响规律,并最终获得了实验钢的动态再结晶图和本构方程。结果表明:变形温度的降低和应变速率的提高均会抑制动态再结晶的发生;低应变速率(0.1s^(-1))下的所有样品均会发生完全动态再结晶;中应变速率(1s^(-1))下,变形温度为800℃的样品只发生部分动态再结晶;高应变速率(10s^(-1))下,不发生完全动态再结晶的变形温度扩大至800~950℃;实验钢的本构方程为ε·=e^(44.2234)[sinh(5.61×10^(-3)σ)]^(10.3572)exp-465799/8.314T)。动态再结晶图和本构方程的确定对实际生产中轧制工艺的设计、得到具备优良性能的特定类型的微观组织具有重要意义。

In view of the problems that high Mn content will lead to cost increase and segregation of medium Mn steel and limit its application,a steel that can meet the performance requirements of Rm>1000 MPa grade(the tensile strength Rm>1000 MPa,the total elongation A>30%)is designed,its chemical composition is Fe-4Mn-1.5Al-0.5Si-0.2C-0.05Nb.By drawing the true strain-stress curves of the experimental steel under different strain rates and deformation temperatures,combined with the microstructure observation,the hot deformation behavior of the experimental steel was studied,especially the influence of strain rate and deformation temperature on the hot deformation behavior of the experimental steel.Finally,the dynamic recrystallization diagram and constitutive equation of the experimental steel were obtained.The results show that the decrease of deformation temperature and the increase of strain rate can inhibit the occurrence of dynamic recrystallization.At low strain rate(0.1 s^(-1)),all samples have full dynamic recrystallization.At the medium strain rate(1 s^(-1)),only partial dynamic recrystallization occurs in the samples at the deformation temperature of 800℃.At high strain rate(10 s^(-1)),the deformation temperature without full dynamic recrystallization expands to 800-950℃.The constitutive equation of the experimental steel isε·=e^(44.2234)[sinh(5.61×10^(-3)σ)]^(10.3572)exp-465799/8.314T).The establishment of dynamic recrystallization diagram and constitutive equation is of great significance to the design of rolling process and obtaining specific microstructure with excellent properties in practical production.