Room-Temperature Compressive Deformation Behavior of High-Strength Ti-15V-3Al-3Cr-3Sn-1Nb-1Zr Alloy

The characteristics of room-temperature compressive deformation of a new high-strength metastable beta titanium alloy Ti-15V-3Al-3Cr-3Sn-1Nb-1Zr (Ti-26) were investigated using the Gleeble-3800 thermo-mechanical simulator at strain rates of 0.001~0.1 S⁻¹ and height reductions of 20–60%. The results show that discontinuous yielding appears at a strain rate of 0.1 S⁻¹ and a height reduction of 60% from 0.06 true strain to 0.12 true strain. The yield strength was found to be sensitive to the strain rate (0.001~0.1 S⁻¹), while the ultimate strength was just the opposite, but higher strain rates produce a discontinuous yielding phenomenon. With increasing height reductions and strain rates, the initially equiaxial grains evolve into fibrous grains and the larger the height reductions and strain rates are, the more significant the elongation of the beta grains is. For small height reductions, the dominant deformation mechanisms are dislocation slip ({110}〈111〉 slip system) and twinning deformation ({332}〈113〉 twinning system); the grain rotation during the twining deformation process can adjust the crystallographic orientation, relieving stress concentration and stimulating additional slip. At large height reductions, the minor volume fraction of twins are completely engulfed by slip lines, and the dominant deformation mechanism changes to dislocation slip.