New insights into the microstructural evolution of Ti-5Al-5Mo-5V-3Cr alloy during hot working

Abstract

Microstructural features resulting from thermomechanical treatment of the β-metastable Ti-5Al-5Mo-5V-3Cr (Ti-5553) alloy were studied by means of electron backscatter diffraction and X-ray diffraction. The alloy was deformed at 950 °C (β field) and 800 °C (α + β field) with strain rates of 0.001 s−1 and 0.1 s−1 in compression mode up to a compression ratio of 0.5 (true ratio = 0.7). It was concluded that β phase undergoes dynamic recovery both above and below its β-transus temperature, and recovery is more dominant at lower strain rates, which was corroborated by EBSD misorientation measurements. Meanwhile, α phase undergoes not only a process of breakage and globularization, but also decomposition, which contributes to flow softening. The increase in strain rate caused non-uniform recovery at 950 °C and a more intense refinement of α precipitates at 800 °C. Macrotexture evaluation after deformation indicates that β's texture is much stronger than that of α, with its (200) component being the strongest one.