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,Σ3n(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 hot deformation characteristics of GH690 superalloy, the hot deformation behavior of this superalloy was investigated by isothermal compression in the temperature range of 1000?1200 °C and strain rate range of 0.001?10 s?1on a Gleeble?3800 thermo-mechanical simulator. The results reveal that the flow stress is sensitive to the strain rate, and the dynamic recrystallization (DRX) is the principal softening mechanism. The strain rate of 0.1 s?1 is considered to be the critical point during the hot deformation at 1000 °C. The DRX process is closely related to the strain rate due to the adiabatic temperature rise. The strain rate has an important influence on DDRX and CDRX during hot deformation. The nucleation of DRX can be activated by twin boundaries, and there is a lower fraction ofΣ 3n(n=1, 2, 3) boundaries at the intermediate strain rate of 0.1 s?1.
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