Titanium alloys are widely used in light weight applications such as jet engine fans, where their mechanical performance under a range of loading regimes is important. Titanium alloys are mechanically anisotropic with respect to crystallographic orientation, and remarkably titanium creeps at room temperature. This means that the strain rate sensitivity (SRS) and stress relaxation performance are critical in predicting component life. In this work, we focus on systematically exploring the macroscopic SRS of Grade 1 commercially pure titanium (CP Ti) with varying grain sizes and texture using uniaxial compression. Briefly, we find that Ti samples had positive SRS and samples compressed along the sheet rolling direction (RD) (i.e. soft grains dominant) were less rate sensitive than bars compressed along the sheet normal direction (ND) (i.e. hard grains dominant). We attribute this rate sensitivity to the relative activity of slip and twinning. Within the grain size range of $~317\pm 7\mathrm{\mu }\mathrm{m}$, we observe an increase in the rate sensitivity, where volume fraction of $\left\{10\bar{1}2\right\}<10\bar{1}1>$T1 tensile twins was low, and the twin width at different strain rates were similar. These observations imply that the macroscopic rate sensitivity is controlled by the ensemble behaviour of local deformation processes: the amount of slips accumulated at grain boundaries affects the SRS, which is grain size and texture dependent. We hope that this experimental study motivates mechanistic modelling studies using crystal plasticity, including strain rate sensitivity and twinning, to predict the performance of titanium alloys.

钛合金广泛用于轻型应用中，例如喷气发动机风扇，在这些应用中，钛合金在各种负载条件下的机械性能非常重要。钛合金相对于晶体学取向是机械各向异性的，并且钛在室温下显着地蠕变。这意味着应变率敏感性（SRS）和应力松弛性能对于预测组件寿命至关重要。在这项工作中，我们专注于系统地探索使用单轴压缩的具有变化的晶粒尺寸和织构的1级商用纯钛（CP Ti）的宏观SRS。简而言之，我们发现Ti样品的SRS为正值，而沿薄板轧制方向（RD）压缩的样品（即软晶粒占主导）比对沿薄板法线方向（ND）压缩的钢筋的速率敏感性较低。硬粒占主导地位）。我们将此速率敏感性归因于打滑和孪生的相对活动。在晶粒度范围内$〜317\pm 7\mathrm{\mu }\mathrm{米}$，我们观察到速率灵敏度有所提高，其中体积分数为 $\left\{10\overline{\mathrm{1个}}\mathrm{2个}\right\}<10\overline{\mathrm{1个}}\mathrm{1个}>$T1拉伸孪晶较低，并且在不同应变速率下的孪晶宽度相似。这些观察结果表明，宏观速率敏感性受局部变形过程的整体行为控制：在晶界积累的滑移量会影响SRS，SRS与晶粒尺寸和织构有关。我们希望该实验研究能够激发使用晶体塑性（包括应变速率敏感性和孪晶）的机械建模研究来预测钛合金的性能。