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采用Gleeble-1500热模拟试验机,对GH625合金进行了以不同变形温度、不同应变速率变形到真应变值为0.7的热压缩试验,以研究其热变形过程的动态再结晶组织演变.利用光学显微镜(OP)和透射电镜(TEM)分析了应变速率对GH625合金热变形过程中的组织演变及动态再结晶形核机制的影响.结果表明:应变速率·ε=10.0s~(-1)时,实际变形温度高于预设温度,产生变形热效应.GH625合金热变形过程的组织演变是一个受应变速率和变形温度控制的过程,在应变速率·ε≤1.0s~(-1)时,GH625合金动态再结晶晶粒的尺寸及体积分数随着应变速率的升高而降低,动态再结晶形核机制是由晶界弓弯的不连续动态再结晶机制和亚晶旋转的连续动态再结晶机制组成;在应变速率·ε=10.0s~(-1)时,由于变形热效应使动态再结晶晶粒的尺寸及体积分数迅速升高,动态再结晶机制则是以弓弯机形核的不连续动态再结晶机制为主.
The hot compressive deformation of GH625 alloy was carried out at different deformation temperature and different strain rate to a true strain of 0.7 by using Gleeble-1500 thermal simulator to study the dynamic recrystallization microstructure of the GH625 alloy during the thermal deformation.Using optical microscope (OP) and transmission electron microscopy (TEM) were used to analyze the effect of strain rate on the microstructure evolution and dynamic recrystallization nucleation during hot deformation of GH625 alloy.The results show that when the strain rate ε = 10.0s -1, The actual deformation temperature is higher than the preset temperature, resulting in deformation heat effect.The microstructure evolution of GH625 alloy during hot deformation is a process controlled by strain rate and deformation temperature.When strain rate ε ≤1.0s -1, GH625 alloy The size and volume fraction of dynamic recrystallization grains decrease with the increase of strain rate. The dynamic recrystallization nucleation mechanism consists of the discontinuous dynamic recrystallization mechanism of grain boundary bowing and the continuous dynamic recrystallization mechanism of subgrain rotation At the strain rate ε = 10.0s -1, the dynamic recrystallization grain size and volume fraction increase rapidly due to the deformation heat effect. The dynamic recrystallization mechanism is based on the discontinuous dynamic again Crystal-based mechanisms.