(烟台大学 精准材料高等研究院，烟台 264010)
摘 要: 镍基粉末高温合金的变形抗力大、热塑性较差、热加工窗口窄，而且在热加工过程中易产生裂纹和流动不稳定等缺陷。本文采用Gleeble-3500热模拟实验机对挤压态新型镍基粉末高温合金进行热压缩，压缩温度为1050~1150 ℃、应变速率为0.001~1 s-1，压缩真实应变为0.69。基于双曲正弦型Arrhenius函数，计算该合金的热激活能Q、构建本构方程，采用多项式拟合摩擦、温度变化、应变补偿的影响，对应力-应变曲线及本构方程进行修正，绘制能量耗散图和热加工图。结果表明：该合金的热激活能Q为536.36 kJ/mol，其在变形温度为1075~1150 ℃、应变速率为10-3~10-1.5 s-1的条件下有较好的加工性能，但当应变速率为0.001 s-1时，晶粒组织较为粗大，γ′相溶入基体。
关键字: 挤压态镍基粉末高温合金；热变形行为；本构方程；应力应变曲线修正；热加工图
（Institute for Advanced Studies in Precision Materials, Yantai University, Yantai 264010, China）
Abstract:Nickel-based powder superalloys have high deformation resistance, poor thermoplasticity, narrow hot working window, and are prone to crack and flow instability during hot working. In this paper, thermal compression experiments were carried out on the extruded novel nickel-base powder superalloy by Gleeble-3500 thermal simulator, where the compression temperature was 1050-1150 ℃, the strain rate was 0.001-1 s-1 and the true strain was 0.69. Based on the hyperbolic sinusoidal Arrhenius function, the thermal activation energy Q was calculated and the constitutive equation was built, then the stress-strain curve and constitutive equation were modified by combining friction, temperature change and strain compensation by polynomial fitting. The energy dissipation diagrams and hot processing maps were plotted to determine the suitable thermal processing temperature and strain rate. The results show that the thermal activation energy Q is 536.36 kJ/mol, and the alloy has good processing performances at the deformation temperature ranging from 1075 ℃ to 1150 ℃ and the strain rate ranging from 10-3 s-1 to 10-1.5 s-1, but the grain microstructure is coarse and the γ′ phase dissolves into the matrix at the strain rate of 0.001 s-1.
Key words: extruded nickel-base powder superalloy; thermal deformation behavior; constitutive equation; stress-strain curve correction; hot processing map
