U720Li合金高温变形行为及变形机理研究

对U720Li合金的高温变形行为进行了系统的研究。通过对该合金高温变形过程中力学行为特征及组织演变规律的分析与计算,得出了不同应变速率、不同变形温度下应变速率敏感性指数m值、变形激活能Q值和晶粒指数P值的变化规律。分别绘制动态材料模型热加工图及包含位错数量的U720Li合金高温变形机理图。应用动态DMM热加工图分析了合金的适合加工区间。运用U720Li合金高温变形机理图,根据不同温度下U720Li合金柏氏矢量补偿的晶粒尺寸、模量补偿的应力值预报了该合金的高温变形机理。

Elevated Temperature Compression Deformation and Deformation Mechanisms in U720Li Superalloy

The hot compression deformation of U720Li superalloy was investigated systematically. Through by the analysis and the calculation of the mechanical behavior and the microstructure evolution during hot compression deformation, the variation of strain rate sensitivity exponent m, activation energy Q and grain size exponent P values at different strain rates and different temperatures were obtained. The hot processing map based on dynamic materials modeling was drawn while high-temperature deformation mechanism maps incorporating dislocations inside grains were obtained. The processing map was used to analyze the hot deformation behavior and to determine processing instability regime and appropriate processing regimes. Within appropriate processing regime, based on the elevated temperature deformation mechanism maps, the Burgers vector compensated grain size, the modulus compensated stress and the dislocation quantities of U720Li superalloy at different temperatures, the hot deformation mechanisms were elucidated.