Phase Dynamic Recrystallization Research Articles

Hot Deformation Mechanisms of an As-Extruded TiAl Alloy with Large Amount of Remnant Lamellae

The hot deformation mechanisms of an as-extruded Ti-44Al-5V-1Cr alloy with a large amount of remnant lamellae were investigated by hot compression tests at temperatures of 900-1250 °C and strain rates of 0.001-1 s−1. The hot processing map of the as-extruded Ti-44Al-5V-1Cr alloy was developed on the basis of dynamic materials modeling and the Prasad criteria. There were four different domains in the hot processing map, according to the efficiency of power dissipation, η. The flow soft and hot deformation mechanisms for different domains were illustrated in the context of microstructural evolution during the process of deformation. As a result, the dynamic recrystallization and superplastic deformation occurred at 1125-1150 °C near 0.001 s−1, and this region is suitable for superplastic forming. The α phase dynamic recrystallization and dynamic recovery occurred at 1250 °C and 0.1 s−1. The existence of small amount of the γ and β phases effectively inhibited the growth of α grains.

Analysis on Phases and Grain Evolution of TC4 Ti-Alloy in Hot Forming in Time and Space Based on Deform-3D

In the hot forging process of TC4 Ti-alloy large die forging two beam, the dynamic recrystallization of α phase and recovery of β phase were happened. Using Deform-3D finite element analysis software, the evolution model of grain and phase is constructed and coupled simulation is carried out, on the foundation of simulation results, the evolution law of α phase dynamic recrystallization and β phase transformation in time and space was obtained, so the optimal control of grain and phase was realized. Thus the performances of TC4 Ti-alloy will be improved and optimized, and all this will provide theoretical basis for the forging of large Ti-alloy components.