(1. 西南交通大学 材料科学与工程学院，成都 610031；
2. 北京科技大学 材料科学与工程学院 特种陶瓷粉末冶金研究所，北京 100083)
摘 要: 在变形温度为1 050~1 140 ℃、应变速率为0.01~10 s−1和变形率为50%的条件下，采用Gleeble−1500热模拟机研究喷射成形FGH95合金的热压缩变形行为。结果表明：在合金热压缩变形初始阶段，流变应力随应变的增加迅速增大，达到峰值应力后逐渐减小，呈现明显的动态软化特征；合金流变应力随变形温度的升高和应变速率的降低而显著减小；应变速率为0.1~10 s−1时，合金峰值应变随温度升高而减小，并趋于平稳；而应变速率为0.01 s−1时，合金峰值应变在1 100 ℃出现极大值。考虑变形量对合金热压缩流变行为的影响，引入包含应变量的四次多项式函数对双曲正弦修正的Arrhenius方程进行改进，改进后的本构方程的流变应力预测值与实验值吻合较好，平均相对误差为3.64%。
关键字: 喷射成形FGH95；高温合金；流变应力；本构方程
（1. School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu 610031, China;
2. Institute of Special Ceramics and Powder Metallurgy, School of Materials Science and Engineering,
University of Science and Technology Beijing, Beijing 100083, China）
Abstract:In order to study the workability and establish the flow stress constitutive equation for spray-forming FGH95 superalloy, the hot compressive deformation behavior of the superalloy was investigated on Gleeble−1500 thermal simulator at the temperature range from 1 050 ℃ to 1 140 ℃, strain rate range from 0.01 to 10 s−1 and deformation rate of 50%. The results show that, during the hot compression deformation of spray-forming FGH95 superalloy, the flow stress increases quickly with the strain increasing and then reaches a peak, then decreases to steady value, and the characteristics of dynamic softening are observed. The flow stress of superalloy significantly decreases with the temperature increasing and the strain rate decreasing. The peak strain of superalloy reduces with the temperature increasing, and gradually stabilizing in strain rate range from 0.1 s−1 to 10 s−1. However, the peak strain of superalloy reaches maximum value at strain rate of 0.01 s−1 and at 1 100 ℃.Considering the impact of deformation on the flow behavior, modified Arrhenius equation of hyperbolic sine was improved by introducing 4th order polynomial function of strain. The predicted flow stress by the developed constitutive equation agrees well with the experimental results, and the average relative error is 3.64%.
Key words: spray-forming FGH95; superalloy; flow stress; constitutive equation
