<p>This work aims to investigate the influence of deformation on the microstructure evolution during subsequent slow cooling of near β titanium alloys, as this influence governs mechanical properties and is therefore critical for optimizing the thermomechanical process, yet remains insufficiently explored. The α phase precipitation and the β phase evolution were systematically examined through a series of hot compression experiments conducted on TC18 titanium alloy in the α + β phase region, followed by controlled slow cooling and microstructure characterization using scanning electron microscopy and transmission electron microscopy. The results reveal that the secondary α phase (α_S) precipitates sequentially at the boundaries and interiors of β grains during slow cooling, with the latter accounting for approximately 83% of the total precipitation. The αS precipitation behavior is primarily governed by the supersaturation of β phase, which increases with increasing deformation temperature and decreasing strain rate. Notably, higher precipitation occurs under the condition of high strain rate (1&#xa0;s^− 1) with small strain (0.22). This is because limited post-dynamic recrystallization during slow cooling allows more than 86% of deformation-induced dislocations to be retained, thereby promoting α_S precipitation. To describe the combined effects of the supersaturation and dislocation on the α_S precipitation under varying deformation conditions, a predictive model was established based on the non-isothermal phase transformation kinetics, achieving an average absolute relative error of 9% for α_S fraction prediction. These findings provide a theoretical foundation for the α_S precipitation behavior after hot deformation and offer valuable insights for optimizing the thermomechanical process.</p>