The tension-compression asymmetry including the yielding and strain hardening asymmetry of a commercially pure titanium (CP-Ti) at room temperature was studied using uniaxial tensile and compressive tests. The deformation twinning modes responsible for the tension-compression asymmetry were analyzed using the electron back scattered diffraction technology. The CP-Ti exhibits a strong tension-compression asymmetry in yielding and strain hardening. The prismatic 〈a〉 slip is the most easiest to activate either for tension or compression. The deformation twinning mode can be characterized by the secondary $\left\{10\overline{1}2\right\}$ twin variants in primary $\left\{11\overline{2}2\right\}$ twins for tension and the secondary $\left\{11\overline{2}2\right\}$ twin variants in primary $\left\{10\overline{1}2\right\}$ twins for compression. The secondary twin variants are the dominated twinning modes whether for tension or compression, determining the final yielding behavior of the titanium. The stress required to activate the secondary extension twins in tension is larger than that to activate the secondary contraction twins in compression, leading to the tension-compression asymmetry in yielding. The strain hardening enhancement of the CP-Ti is a result of the combination of the Hall-Petch hardening by grain refinement and texture hardening by lattice re-orientation both resulting from the deformation twinning. The stronger effect of these two hardening mechanisms on compression than on tension leads to the tension-compression asymmetry in strain hardening.

使用单轴拉伸和压缩试验研究了室温下商业纯钛（CP-Ti）的拉伸压缩不对称性，包括屈服和应变硬化不对称性。使用电子反向散射衍射技术分析了造成拉伸-压缩不对称的变形孪生模式。CP-Ti在屈服和应变硬化方面表现出很强的拉伸-压缩不对称性。棱柱形<a>滑条最容易激活以产生拉力或压缩力。变形孪生模式的特征在于次级$\left\{10\overline{\mathrm{1个}}\mathrm{2个}\right\}$ 初级的双变体 $\left\{11\overline{\mathrm{2个}}\mathrm{2个}\right\}$ 双胞胎的紧张和次级 $\left\{11\overline{\mathrm{2个}}\mathrm{2个}\right\}$ 初级的双变体 $\left\{10\overline{\mathrm{1个}}\mathrm{2个}\right\}$双胞胎的压缩。次生孪生变体是主导的孪生模式，无论是拉伸还是压缩，决定了钛的最终屈服行为。激活次级拉伸孪晶所需的应力大于激活次级压缩孪晶所需的应力，从而导致屈服中的拉伸-压缩不对称。CP-Ti的应变硬化增强是变形孪晶导致的通过晶粒细化进行的Hall-Petch硬化和通过晶格重新取向进行的纹理硬化的结合。这两种硬化机制对压缩的影响大于对张力的影响，导致应变硬化中的拉压不对称性。