The effects of heat treatment processing on the microstructures of Ti-6Al-4V alloy are systematically studied. Static globularization behavior of lamellar α phase is found when the alloy is cooled in air or furnace from 950–960 °C (below the β-transus temperature, about 975 °C). Three kinds of microstructures (basket-weave, globular-lamellar, and equiaxed microstructures) are obtained by different heat treatments. The uniaxial tensile tests of the studied alloy with different initial microstructures are conducted at the elevated temperature and different strain rates. It is found that the initial microstructures have obvious effects on the tensile properties and fracture mechanisms. The alloy with basket-weave microstructures exhibits the most obvious work hardening behavior and the highest strength. The alloy with globular-lamellar microstructures has the better ductility than that with basket-weave microstructures. Furthermore, the alloy with equiaxed microstructures has the best ductility, because the equiaxed α phases can delay the formation and coalescence of microvoids. Meanwhile, α phases are elongated, bent and spherized, which contributes to the flow softening during tensile deformation. Especially, the alloy with initial equiaxed microstructures finally transforms to bimodal microstructures after tensile fracture. Additionally, the alloys with three different initial microstructures all show a primary ductile fracture.

系统地研究了热处理工艺对Ti-6Al-4V合金组织的影响。当合金在950-960°C（低于β-转变温度，约975°C）的空气或炉中冷却时，会发现层状α相的静态球化行为。通过不同的热处理可以获得三种组织（篮状组织，球状组织和等轴组织）。在高温和不同应变速率下，对具有不同初始微观结构的合金进行了单轴拉伸试验。发现初始的微观结构对拉伸性能和断裂机理有明显的影响。具有篮式组织的合金表现出最明显的加工硬化行为和最高的强度。具有球状片状微结构的合金比具有篮式组织的合金具有更好的延展性。此外，具有等轴结构的合金具有最佳的延展性，因为等轴α相会延迟微孔的形成和聚结。同时，α相被拉长，弯曲和球形化，这有助于拉伸变形过程中的流动软化。特别是，具有初始等轴组织的合金在拉伸断裂后最终转变为双峰组织。另外，具有三种不同的初始微观结构的合金都显示出原始的延性断裂。因为等轴α相可以延迟微孔的形成和聚结。同时，α相被拉长，弯曲和球形化，这有助于拉伸变形过程中的流动软化。特别是，具有初始等轴组织的合金在拉伸断裂后最终转变为双峰组织。另外，具有三种不同的初始微观结构的合金都显示出原始的延性断裂。因为等轴α相可以延迟微孔的形成和聚结。同时，α相被拉长，弯曲和球形化，这有助于拉伸变形过程中的流动软化。特别是，具有初始等轴组织的合金在拉伸断裂后最终转变为双峰组织。另外，具有三种不同的初始微观结构的合金都显示出原始的延性断裂。