Wei He, Chao Luan, Chengwei He, Yifeng Guo, Bin Xu, Mingyue Sun
T his study systematically investigates the influence of varying annealing temperatures on the heterogeneous microstructure and mechanical properties of large-scale ring-rolled near-ɑ Ti alloy components. The experimental results demonstrate that heat treatment at approximately 30 °C below the β-phase transformation temperature (T β ) facilitates the formation of a bimodal microstructure, thereby achieving an optimal balance between impact toughness (about 24 % in different direction) and tensile strength (about 10 % in different-direction R p0.2 ). The experiments also reveal that annealing at lower temperatures fails to mitigate impact toughness anisotropy in the initial specimens. Annealing at temperatures near the T β induces tensile strength anisotropy, which is mitigated when the annealing temperature exceeds the T β . This phenomenon is mainly attributable to reduced dislocation density and the alignment of high ɑ s vol/% with the prior β-phase orientation. The prior β T grains influence the crystallographic orientation of the precipitated ɑ s phase planes under conditions of low dislocation density. This promotes a close-packed arrangement along the closely-aligned orientations, which ultimately affects the material's mechanical properties and induces tensile strength anisotropy. These results provide theoretical guidance for reducing the performance anisotropy of Ti6321 alloy ring-rolled components, particularly large-scale titanium alloy ring-rolled products. • Ti6321 achieved a balance between tensile and impact properties, through annealing heat treatment at approximately 30 °C below the β transus temperature. • The impact anisotropy was attributed to grain size differences along different crystallographic orientations. • The formation of tensile anisotropy was caused by texture development. • This study proposes a relatively straightforward and operable method for improving anisotropy in large forgings.