为阐明应变速率对GH690高温合金热变形特性的影响,采用Gleeble-3800热力模拟试验机,通过变形温度范围为1000~1200°C、应变速率范围为0.001~10 s~(-1)的等温热压缩实验研究了该合金的热变形行为。结果表明:流变应力对应变速率变化敏感,动态再结晶是主要的软化机制;0.1 s~(-1)是1000°C热变形过程中的临界应变速率。绝热温升使得动态再结晶过程与应变速率密切相关;应变速率对热变形过程中的非连续动态再结晶和连续动态再结晶具有显著影响;孪晶可促进动态再结晶形核,Σ3~n(n=1,2,3)晶界在中等应变速率0.1 s~(-1)条件下含量较低。 In order to clarify the effect of strain rate on the thermal deformation characteristics of GH690 superalloy, the Gleeble-3800 thermomechanical simulator was used to simulate the thermal deformation of GH690 superalloy. The deformation temperature range was 1000-1200 ° C and the strain rate range was 0.001-10 s -1 Thermal compression experiments were carried out to study the thermal deformation behavior of the alloy. The results show that the flow stress is sensitive to the change of strain rate and the dynamic recrystallization is the main softening mechanism. The critical strain rate of 0.1 s ~ (-1) at 1000 ° C is the critical strain rate. The adiabatic temperature rise makes the dynamic recrystallization process closely related to the strain rate. The strain rate has a significant influence on the non-continuous dynamic recrystallization and continuous dynamic recrystallization in the hot deformation process. The twins can promote the dynamic recrystallization nucleation. Σ3 ~ n ( n = 1, 2, 3) grain boundaries are low at the medium strain rate of 0.1 s ~ (-1).