一种Cr-Mo-Ni系贝氏体钢的动态再结晶行为

Dynamic recrystallization behavior of Cr-Mo-Ni bainitic steel

采用Gleeble-1500D热模拟实验机进行热压缩实验,研究一种Cr-Mo-Ni系贝氏体钢在变形温度为850～1150℃和应变速率为0.01～10 s^-1条件下的动态再结晶行为。结果表明,试验钢中添加合金元素Cr、Mo、Ni,由于固溶原子拖曳及析出物的钉扎作用,显著抑制动态再结晶;动态再结晶开始时间与变形温度的关系曲线（RTT曲线）分析表明,变形温度降低及变形速率加快均延长动态再结晶开始时间tc,温度补偿应变速率因子（Z因子）变大,愈难发生动态再结晶软化;通过线性回归计算了动态再结晶激活能Q,建立了形变Z因子模型,并回归了峰值应力、峰值应变、临界应变与Z因子的关系式,最后利用Avrami方程和应力-应变曲线建立了Cr-Mo-Ni系贝氏体钢的动态再结晶动力学模型。

The dynamic recrystallization behavior of a Cr-Mo-Ni bainitic steel during hot compression deformation was investigated at 850-1150 ℃ and strain rate of 0. 01-10 s^- 1on a Gleeble-1500 D thermo-simulation machine. The results show that the addition of microalloy elements such as Cr,Mo and Ni produces a retardation of dynamic recrystallization under the action of solid solution drawing and precipitate pinning. Based on the analysis of RTT（ Recrystallization-Temperature-Time） curve,as the deformation temperature decreases and strain rate increases,the start time of dynamic recrystallization extends and Z parameter increases,and softening caused by dynamic recrystallization is more difficult. The deformation activation energy Q is evaluated by linear regression analysis. Zener-Hollomon parameter model and mathematical models between peak stress, critical strain and Z parameter are set up. Finally dynamic recrystallization kinetics model is developed for Cr-Mo-Ni bainitic steel by using Avrami equation and stress-strain curves.