An experimental study of deformation mechanism and microstructure evolution during hot deformation of Ti–6Al–2Zr–1Mo–1V alloy

Abstract

a b s t r a c tIsothermal tensile tests have been performed to study the deformation mechanisms and microstructure evolution of Ti-6Al-2Zr-1Mo-1V titanium alloy in the temperature range 750-850°C and strain rate range 0.001-0.1 s À1. The deformation activations have been calculated based on kinetics rate equation to investigate the hot deformation mechanism. Microstructures of deformed samples have been analyzed by electron backscatter diffraction (EBSD) to evaluate the influences of hot deformation parameters on the microstructure evolution and recrystallization mechanism. The results indicate that deformation mechanisms vary with deformation conditions: at medium (800°C) and high (850°C) temperature, the deformation is mainly controlled by the mechanisms of dislocation creep and self-diffusion, respectively. The microstructure globularization mechanisms also depend on deformation temperature: in the temperature range from 750 to 800°C, the high angle grain boundaries are mainly formed via dislocation accumulation or subgrain boundaries sliding and subgrains rotation; while at high temperature of 850°C, recrystallization is the dominant mechanism. Especially, the evolution of the recrystallization mechanism with the deformation temperature is first observed and investigated in TA15 titanium alloy.

Dynamic globularization and restoration mechanism of Ti–5Al–2Sn–2Zr–4Mo–4Cr alloy during isothermal compression

“…Furuhara et al [16] found the CDRX in the b phase of Ti-10V-2Fe-3Al during hot deformation. Moreover, the previous work [17,18] revealed that DRX played an important role in the a phase evolution of Ti-1.5Fe and Ti-6Al-2Zr-1Mo-1V during hot deformation. A few physical models have also been established so as to describe the DRX behavior [19,20].…”

Behavior and modeling of flow softening and ductile damage evolution in hot forming of TA15 alloy sheets

“…Recent researches indicate that the hot deformation mechanisms of titanium alloys, which are generally controlled by thermal activation, are not only influenced by alloying elements and initial microstructure, but also affected by deformation temperature, strain and strain rate [24]. The flow softening mechanism of two-phase titanium alloys varies with deformation conditions as well as initial microstructure.…”

Loading path and microstructure study of Ti-3Al-2.5V tubular components within hot gas forming at 800 °C

“…Simultaneously, some tiny grains (<5 μm) without any LGBS appeared, which means the recrystallization was taken place. The tiny grains are connected with each other, which is termed as "necklace structure," a common result of the thermomechanical processing for two-phase Tialloys [31][32][33]. It should be noted that the schmid factor increased significantly.…”