电热合金Cr20 Ni80的热变形行为及热加工图

为了解决Cr20 Ni80电热合金锻造开裂的问题,在Gleeb-1500D热模拟试验机上对该合金进行热压缩试验,研究变形温度为900~1220℃,应变速率为0.001~10 s-1条件下的热变形行为,并根据动态材料模型建立合金的热加工图.合金的真应力-真应变曲线呈现稳态流变特征,峰值应力随变形温度的降低或应变速率的升高而增加；热变形过程中稳态流变应力可用双曲正弦本构方程来描述,其激活能为371.29 kJ·mol-1.根据热加工图确定了热变形流变失稳区及热变形过程的最佳工艺参数,其加工温度为1050~1200℃,应变速率为0.03~0.08 s-1.优化的热加工工艺在生产中得到验证.

Hot deformation behavior and processing maps of Cr20 Ni80 electrothermal alloy

To solve the problem of forging cracks, the hot deformation behavior of Cr20 Ni80 electrothermal alloy was investigated by compression tests on a Gleeble-1500D thermal simulation machine in a temperature range of 900 to 1220℃ and a strain rate of 0. 001 to 10 s-1 . The hot processing map of the alloy was established according to the dynamic materials model ( DMM) . It is found that the true stress-true strain curves have steady-state flow characteristics. The peak stress increases with decreasing deformation temperature or increasing strain rate. The flow behavior is described by a hyperbolic sine constitutive equation, and the activation energy of the alloy is about 371. 29 kJ·mol-1 . Based on the processing map, the process of hot deformation in the temperature range at different strain rates can be attained, of which the optimum hot deformation temperature ranges in 1050-1200℃ and the strain rate is 0. 03-0. 08 s-1 , and the instability zones of flow behavior can also be recognized. The optimal hot-working technology is validated to be successful in production.