粗大柱状晶纯镍热变形流变应力行为及加工图

采用Gleeble-3500热模拟机，在变形温度为950~1 150 ℃、应变速率为0.001~10 s-1的条件下，研究了粗大柱状晶粒纯镍的热变形行为和加工图.结果表明：热压缩过程中流变应力随应变速率增大而增大，随变形温度降低而增大.流变应力与应变速率、变形温度之间的关系用Zener-Hollomon参数来描述，热变形激活能为312.4 kJ/mol.基于动态材料模型(DMM)热加工图及结合合金相显微组织分析，得到纯镍较优的热加工参数：变形温度为1 060~1 120 ℃，应变速率为0.03~0.20 s-1的蛋形区域.
The hot deformation behavior of pure nickel with coarse, columnar grains at the temperature range of 950~1 150 ℃and the strain rate range of 0.001~10-1 was investigated in the Gleeble-3500 system. The results showed that flow stress increased with the increase of strain rate and decreased with the increase of temperature. The relationship between flow stress and strain rate and temperature was represented by the Zener-Hollomon parameter and the apparent activation energy of 312.4 kJ/mol. The optimum processing parameters were obtained by using processing maps based on the dynamic material model and microstructural observation at the deformation temperature of 1 060~1 120 ℃and the strain rate of 0.03~0.2 s-1.