GH625镍基合金高温塑性变形加工图研究

Study on the Processing Map of GH625 Ni-Based Alloy Deformed at High Temperature

摘要:

在Gleeble热模拟机上对GH625合金进行了等温热压缩实验，获得了不同变形条件下该合金的真应力真应变曲线。利用DMM模型构建了GH625合金在不同应变量下的加工图，通过对加工图的分析，可以得到：GH625合金加工图中存在一个功率耗散效率较高的区域，其对应的变形温度为1100~1200 ℃，应变速率为0.01~1.0 s-1，在该变形区域内，合金发生了完全动态再结晶。当功率耗散效率为0.4~0.45时，动态再结晶晶粒细小均匀；在峰值效率0.47时，动态再结晶晶粒出现明显的长大趋势；在低温高应变速率下存在一个较小的流变失稳区，该区域内的动态再结晶晶粒沿绝热剪切带分布。实际生产中工艺参数的制定应尽量选择在完全动态再结晶区内加工，避免在失稳区加工成型。基于GH625合金加工图及微观显微组织分析可得该合金的适宜加工区域为：=0.01~1.0 s-1，T=1100~1200 ℃

Abstract:

The isothermal compression test of GH625 alloy was performed on Gleeble thermal simulator. A series of true stress-strain curves under different deformation conditions were obtained. The processing map of GH625 alloy in different strains was constructed according to DMM model, and the following conclusions can be obtained through the analysis of processing map. There exists an area in the processing map of GH625 alloy where the power dissipation efficiency is higher than that in others areas. The temperature corresponding the area is 1100~1200 ℃ and the strain rate is 0.01~1.0 s-1. In this area the alloy has completed fully dynamic recrystallization. When the power dissipation efficiency is in the range from 0.4 to 0.45, the dynamic recrystallization grains become finer. At the peak efficiency of 0.47, the dynamic recrystallization grains grow up apparently. There exists a small area of rheological instability in the processing map where the temperature is low, while the strain rate is high, and the dynamic recrystallization grains are distributed along the adiabatic shearing edges. The practical parameters of production processing should be chosen in fully dynamic recrystallization area, and the manufacturing in the instability zone should be avoided. According to the comprehensive mechanical properties of high temperature deformation, the microstructure evolution and the processing map of the GH625 alloy, we can get a suitable processing area, which is =0.01~1.0 s-1，T=1100~1200 ℃