<p>In this study, HRB600E rebar was selected as the research object. The effects of Ti content on inclusions, microstructure, and mechanical properties of Ti-containing HRB600E rebar were investigated using techniques such as scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The research aims to provide theoretical guidance for the industrial production of seismic-resistant rebar HRB600E with superior mechanical properties and high corrosion resistance. The results show that as the Ti content in the steel increases, the proportion of TiO₂ in inclusions increases. Meanwhile, the proportions of SiO₂ and MnO in inclusions decrease. Additionally, the number of inclusions increases, while their average size decreases. For HRB600E rebar containing titanium in this study, with the increase of Ti content, the average equivalent circular diameter of grains decreases from 15.61 to 6.82 μm, and the average maximum Feret diameter decreases from 20.92 to 11.14 μm. These findings indicate that within the studied system, increasing Ti content exerts a significant grain-refining effect on HRB600E rebar. Under high-temperature in-situ observation, the average austenite grain size decreases from 160.43 to 101.86 μm before holding, and from 176.50 to 107.36 μm after holding. Correspondingly, the growth rate of austenite grains decreases from 9.97 to 5.94 pct. Increasing Ti content promotes austenite nucleation while inhibiting its growth at high temperatures, which concurrently enhances both the strength and toughness of the HRB600E rebar. The addition of Ti also facilitates the dispersion of non-metallic inclusions in the steel. As Ti content increases, these inclusions tend to become finer and more uniformly dispersed. These combined effects contribute to solid solution strengthening, second-phase strengthening, and grain refinement strengthening. Ultimately, these mechanisms lead to the improvement of the HRB600E rebar’s mechanical properties.</p>