Microstructure, texture evolution and mechanical properties of VT3-1 titanium alloy processed by multi-pass drawing and subsequent isothermal annealing

Abstract

Microstructure, texture evolution, and mechanical properties of Ti–6Al–1.5Cr–2.5Mo– 0.5Fe–0.3Si (VT3-1) titanium alloy processed by multi-pass drawing and subsequent isothermal annealing were systematically investigated. A fiber-like microstructure is formed after warm drawing at 760◦C with 60% area reduction. After isothermal annealing, the samples deformed to different amounts of area reduction show a similar volume fraction (80%) of α phase, while the sample deformed to 60% exhibits a homogeneous microstructure with a larger grain size (5.8 µm). The major texture component of α phase developed during warm drawing is centered at a position of {φ1 = 10◦, φ = 65◦, φ2 = 0◦ }. The textures for annealed samples are almost along the orientation of original deformation textures and show significant increases in orientation density and volume fraction compared with their deformed states. In addition, for the drawn samples, the ultimate tensile strength increases but the ductility decreases with increasing drawing deformation. A negative slope of yield strength of annealed samples versus grain size (d−1/2) is found due to the difference between texture softening for as-rolled + annealed state and texture hardening for drawn + annealed state. The mechanical properties of annealed samples are found to be strongly dependent on grain size and texture, resulting in the balance of the strength and ductility.