Titanium is promising for manufacturing high-performance components in aerospace, marine, energy and healthcare. Whether the forming potential of alpha titanium can be excavated under cryogenic and warm working conditions and how the anisotropic plasticity and fracture evolve over a wide temperature range are the premise and basis for accurate control of inhomogeneous deformation of the material and invention of new forming technologies. In tandem with this, the anisotropic plasticity and fracture of alpha titanium sheets over a wide temperature range of -180 to 200 °C were explored regarding behaviors, mechanisms and modeling. 1) From a series of characterization experiments under different temperatures, compared with room temperature, the tension hardening exponent and fracture elongation of the material are increased by 133% and 48% at -180 °C, and by 7% and 50% at 200 °C. The anisotropy and asymmetry in flow stress are decreased with the temperature increasing from -180 to 200 °C, while the fracture displacements present a significant anisotropy over the given temperature range. 2) Via the macro- and micro-observations regarding dislocation, texture, micro-void and fractography and the viscoplastic self-consistent (VPSC) based slip/twinning analysis, at cryogenic temperature, the synergistic effects of slip and twinning make the dislocation motion ability increase and the grains refined. This causes the large strain hardening ability and inhibits the growth of micro-voids, which results in a relatively large fracture elongation. With increasing temperature, the increased slip systems and slip activities suppress the activation of twinning. At warm temperature, the enhanced dislocation motion ability by thermal activation reduces dislocation pile-up and inhibits void initiation, making the fracture elongation increase. 3) By introducing the temperature/strain related interpolation approach and the linear transformation of stress tensor, an integrated modeling framework was proposed, and the evolution of anisotropic yielding-necking-fracture loci with temperature was established. The results indicate that the necking strain limit is significantly improved at cryogenic temperature and the fracture strain limit is dramatically increased at warm temperature.

钛有望用于制造航空航天、海洋、能源和医疗保健领域的高性能部件。α钛在低温和温热工况下的成形潜力能否被挖掘出来，以及在宽温度范围内各向异性塑性和断裂如何演变，是精确控制材料不均匀变形和发明新成形技术的前提和基础。与此同时，对α钛片在-180至200°C的宽温度范围内的各向异性塑性和断裂行为、机制和建模进行了探索。1）从不同温度下的一系列表征实验来看，与室温相比，-180℃时材料的拉伸硬化指数和断裂伸长率分别提高了133%和48%，在 200 °C 时分别为 7% 和 50%。流动应力的各向异性和不对称性随着温度从-180 ℃升高到200 ℃而降低，而裂缝位移在给定温度范围内呈现出显着的各向异性。2）通过对位错、织构、微孔洞和断口的宏观和微观观察以及基于粘塑性自洽（VPSC）的滑移/孪晶分析，在低温下，滑移和孪晶的协同作用使位错运动能力增加，谷物精炼。这导致较大的应变硬化能力并抑制微孔的生长，从而导致较大的断裂伸长率。随着温度的升高，增加的滑移系统和滑移活动抑制了孪晶的激活。在温暖的温度下，通过热激活增强的位错运动能力减少了位错堆积并抑制了空洞的产生，使断裂伸长率增加。3）通过引入温度/应变相关插值方法和应力张量的线性变换，提出了一个综合建模框架，建立了各向异性屈服-颈缩-断裂轨迹随温度的演化。结果表明，低温下颈缩应变极限显着提高，而高温下断裂应变极限显着提高。提出了一个综合建模框架，建立了各向异性屈服-颈缩-断裂轨迹随温度的演变。结果表明，低温下颈缩应变极限显着提高，而高温下断裂应变极限显着提高。提出了一个综合建模框架，建立了各向异性屈服-颈缩-断裂轨迹随温度的演变。结果表明，低温下颈缩应变极限显着提高，而高温下断裂应变极限显着提高。