By means of creep curves measurement and microstructure observation, the influence of three preparing technics ( hot rolling, long-term aging and solution aging) on the microstructure and creep properties of Ti-6Al-4V alloy is investigated. Results show that, under the applied stress of 575 MPa at 400℃ , the hot rolled Ti-6Al-4V alloy displays a shorter creep lifetime about 70h, but after long-term aging and solution + aging, the creep lifetimes of the alloy at the same testing conditions are prolonged to 230h and 548h,respectively. Microstructure of the hot rolled alloy consists of band-like α phase and network αphase. After long-term aging, significant amount of β particles are precipitated in the α phase. After solution + aging, the microstructure of the ahoy consists of the network basket structure with high volume fraction and the equiaxial α phase, which is the main reason of having longer creep lifetimes. During creep, the deformation mechanism of the hot rolled alloy is the dislocation slipping activated in the α phase, while the deformation mechanism of the solution + aging alloy is the < a + c > dislocations of the wavilness activated on the pyramidal planes. As creep goes on, more dislocations in the α phase are concentrated and cause the dynamic recrystallization, which refines the grain size of the alloy. It is the synthetical effect of the network basket structure and the thinner α phase that make the solution + aging alloy have longer creep lifetime and better plasticity.%通过长期时效、固溶+时效处理和蠕变性能测试,研究了处理工艺对热连轧Ti一6Al-4V合金蠕变行为的影响.结果表明,在400℃,575MPa条件下,热连轧态合金有较低的蠕变寿命,经长期时效和亚温固溶时效处理后,合金的蠕变寿命由70h分别提高到230h和548 h.热连轧态Ti-6Al-4V合金的组织结构由类条状α相和网状β相组成;经长期时效处理后,在α相中析出大量粒状α相;而经亚温固溶+时效处理后,合金中形成的高固溶度等轴α相和高体积分数的"网篮"组织,是使合金较大幅度提高蠕变寿命的主要原因.在蠕变期间,热连轧合金的变形机制是α相中发生位错滑移;而固溶+时效处理合金的主要蠕变机制是波浪状〈a+c〉位错发生锥面滑移.随蠕变进行,合金中α相内发生高密度位错的束集,及发生动态再结晶以细化晶粒,其中细小α相和"网篮"组织的共同作用,是使合金具有较高蠕变寿命和较好塑性的主要原因.
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