Effect of α phase on high-strain rate deformation behavior of laser melting deposited Ti-6.5Al-1Mo-1V-2Zr titanium alloy

Laser melting deposition (LMD) technology enables the use of complex titanium alloy parts in ballistic applications such as lattice armors and warheads. The effect of the a phase of a LMD Ti-6.5Al-1Mo-1V-2Zr titanium alloy during compression at a high strain rate of 3000 s(-1) was investigated. Various morphologies and textures of the alpha phase of the LMD alloy were obtained by annealing at different temperatures at the beta transus, followed by furnace cooling. It was found that all the alpha phases of the annealed microstructures exhibit two fiber textures, < 2<(1)over bar>(1) over bar0 > alpha and < 16 0 <(16)over bar> 19 > alpha, parallel to the building direction. The reason is that the < 100 > beta directions of the prior-beta grains were parallel to the building direction. Due to a high Schmidt factor, {10 (1) over bar2} twinning occurs in the alpha phases with the < 2<(1)over bar>(1) over bar0 > alpha fiber texture during the high-strain rate deformation. After annealing at 970 degrees C, the volume fraction of the alpha phases with the < 2<(1)over bar>(1) over bar0 > alpha fiber texture increases significantly to 51.4 vol%, which leads to a significant improvement of 14.3% in the uniform ductility strain. Moreover, with an increase in the annealing temperature from 930 degrees C to 970 degrees C, the flow strength of the sample decreases slightly by 2%.