复合析出强化超高强度钢20Co14Ni12Cr2MoAl的动态再结晶行为

Dynamic recrystallization behavior of combined precipitation strengthening 20Co14Ni12Cr2MoAl ultrahigh strength steel

通过Gleeble-3800热力模拟试验机采用高温轴向压缩试验,在温度为850-1150℃,应变速率为0.01-10 s-（-1）的条件下,对一种碳化物和金属间化合物复合析出硬化超高强度20Co14Ni12Cr2Mo Al钢的高温变形及动态再结晶行为进行了研究。结果表明,试验钢流变应力和峰值应变随着变形温度的升高和应变速率的降低而减小;随着变形速率的提高,其发生完全动态再结晶的温度也逐渐升高。当变形速率为10 s-（-1）时,其变形温度高于1050℃,才能发生完全动态再结晶;完全动态再结晶晶粒的平均尺寸随着Zener-Hollomon参数的增加而减小,试验钢完全动态再结晶晶粒尺寸与Z参数之间的关系模型为：D_（DRX）=2.644×10-4·Z-（-0.119）,并建立了该钢的动态再结晶状态图;试验钢的热变形激活能Q值为449.20 k J/mol。

The hot compression deformation behavior and dynamic recrystallization behavior for a combined precipitation strengthening ultrahigh strength 20Co14Ni12Cr2Mo Al steel with M2C carbides andβ-Ni Al intermetallics were investigated by using Gleeble-3800 simulator at the temperature range of 850℃to 1150℃and at the strain rate of 0.01-10 s-（-1）.The corresponding flow curves were determined and the hot deformed microstructures were observed.The results show that the flow stress and peak strain increase with increasing strain rate or decreasing deformation temperature.The temperature of full dynamic recrystallization increases with the strain rate rising.When the strain rate is 10 s-（-1）the deformation temperature is beyond 1050℃full dynamic recrystallization can occur.The size of fully dynamic recrystallization grains decreases with Zener-Hollomon parameter rising.The relationship formula（D（DRX）=2.644×10-4·Z-（-0.119））between the size of dynamic recrystallization grains and Zener-Hollomon parameter is obtained.The hot deformation activation energy Q of20Co14Ni12Cr2Mo Al steel is 449.20 k J/mol and the state diagram of dynamic recrystallization of experimental steel is derived based on the experiments.