Microstructure Analysis of the Limited Strain Hardening in Metastable β Titanium Alloy with Equiaxed Grain

Metastable β titanium alloy usually exhibits limited work hardening and high yield-to-strength ratio which is detrimental to aerospace application. In this paper, a systematic research on the weak work hardening and microstructure evolution of metastable β titanium alloy Ti-5Al-4Zr-7Mo-8V was performed. Dislocation density, microstructure evolution and slip behavior under different tensile strains were investigated by XRD, EBSD and TEM. The results indicated that the maximum work-hardening rate after yielding point was only 638 MPa which was lower than the true stress. The total dislocation density increased slightly with the increase in the plastic deformation from 2.7 × 10 14 to 8.3 × 10 14 m −2 . The density of geometrically necessary dislocations increased from 2.5 × 10 14 m −2 at 3