细晶态FGH96热成型时的流动行为研究

Flow Behavior Study on Fine-Grain FGH96 P/M Superalloy During Hot Deformation

通过热模拟试验 ,对细晶态FGH96合金的高温流动特性进行了研究 ,分别从宏观和微观上对影响FGH96流动特性的因素 (变形温度、变形速率和变形程度以及Z因子和动态再结晶晶粒尺寸等 )作了系统分析。结果表明 :变形温度、变形速率和变形程度对流动应力和再结晶晶粒尺寸均有不同程度的影响。在此基础上 ,建立了细晶态FGH96合金热成型时的本构模型 ,该模型充分考虑了变形温度、变形速率和变形程度对流动应力的影响 。

The hot deformation behavior of FGH96 superalloy has been characterized in the temperature range of 1050-1100^DDGC and the strain rate range 0.001-0.1 /s by hot compressive simulation experiments on the fine-grain material. From the macroscopic and microscopic views, the correlation between flow stress of FGH96 and influencing factors (such as process parameters-deformation temperature, deformation rate and deformation degree, Zener-Hollomon parameter and grain size) was analyzed systematically. Flow curves show that the material exhibits dynamic recovery and dynamic recrystallization during deformation. The influences of deformation temperature, deformation rate and deformation degree on the flow stress and grain size are different. The deformation degree mainly influences the shape of flow curves. On the basis of systematic analysis and study, a phenomenological constitutive relationship model is established through a mathematical regression by taking the strain as a modification factor. The calculated and experimental values are in good agreement. Therefore, the essential prerequisite is created for the improvement of numerical simulation accuracy and for the rational choice of process parameters for FGH96 superalloy.