The effect of hot deformation on α-phase precipitation during the subsequent heat treatment, as well as the mechanical properties of TB18 Ti-alloy, was investigated. Results show that the round bar obtained by the dual-phase field forging of the cast ingot exhibits uniform composition distribution on its cross-section. However, various degrees of deformation are detected at different positions on the cross-section, which is attributed to the characteristics of the forging process. Under the forging condition, the microstructure is mainly composed of β-phase matrix and coarsened discontinuous primary α-phases. After solution and following artificial aging treatment, the primary α-phases disappear, while needle-like secondary α-phases precipitate in the matrix. Additionally, dispersed white zones are observed in the samples after aging, which are analyzed to be the precipitation-free zones of secondary α-phase. Despite a uniform compositional distribution among various regions, these dispersed white zones exhibit higher content and larger size in the positions that have undergone lower forging deformation. It indicates that the insufficient forging deformation inhibits the precipitation of the secondary α-phase, ultimately resulting in the lower strengthening effect by heat treatment. Thus, consistent with the characteristics of the forging process, a periodic variation of sample in strength is detected along the circumferential direction of the forged round bar.