Research was conducted on the microstructural evolution and ensuing mechanical response from high-pressure torsion (HPT) processing of Ti–6Al–4V alloy in the as-cast and β-forged conditions with and without 0.1 wt% boron addition. The boron addition produces refinement of the prior β grains and the (α+β) colonies and introduces an additional TiB phase but this affects the deformation response and the microstructural evolution only at low strains of 0.5–5 rotations. In the initial condition the orientation of the (α+β) colonies significantly affects the deformation response and leads to differences in substructure formation in both the as-cast and β-forged conditions. This orientation dependence counts on the initial microstructural differences between the unmodified and the boron modified alloys. At higher strains, there is a similar deformation response and microstructure evolution all the alloys. The hardness variation with equivalent strain is similar for the unmodified and boron modified alloys in as-cast and β-forged conditions and represents various deformation regimes in HPT-processing. Strength modelling confirms a simultaneous contribution from microstructural refinement and increased dislocation density towards the hardness increment during HPT processing. Overall, the as-cast and β-forged Ti–6Al–4V-0.1B alloys possess identical deformation response to the β-forged unmodified Ti–6Al–4V alloy in the initial and intermediate stages. At high levels of straining, all alloys respond in an equivalent manner, thus ruling out any possible effects from additional TiB phase or microstructural refinement for the boron-modified alloys.

研究了在添加和不添加 0.1 wt% 硼的铸态和 β 锻造条件下，Ti-6Al-4V 合金的高压扭转 (HPT) 加工的微观结构演变和随后的机械响应。添加硼会细化先前的 β 晶粒和 (α+β) 菌落，并引入额外的 TiB 相，但这仅在 0.5-5 转的低应变下影响变形响应和微观结构演变。在初始条件下，(α+β) 菌落的方向显着影响变形响应，并导致铸态和 β 锻造条件下亚结构形成的差异。这种取向依赖性取决于未改性合金和硼改性合金之间的初始微观结构差异。在更高的应变下，所有合金都有相似的变形响应和微观结构演变。在铸态和 β 锻造条件下，未改性和硼改性合金的硬度随等效应变变化相似，并且代表了 HPT 加工中的各种变形状态。强度建模证实了在 HPT 加工过程中，微观结构细化和位错密度增加对硬度增量的同时贡献。总体而言，铸态和 β-锻造的 Ti-6Al-4V-0.1B 合金在初始和中间阶段具有与 β-锻造未改性 Ti-6Al-4V 合金相同的变形响应。在高应变水平下，所有合金都以相同的方式响应，因此排除了额外的 TiB 相或硼改性合金的微观结构细化的任何可能影响。