摘要：本文以12mm×12mm×85mm的纯钛作为研究对象，通过对纯钛进行等通道挤压（ECAP），研究不同变形道次对显微组织、显微硬度和拉伸性能的影响，以及热稳定性。研究结果表明：轧制态纯钛的显微组织是由等轴晶和孪晶构成，退火态纯钛的显微结构是由均匀等轴晶构成，经过一道次ECAP变形呈现为拉长的晶粒和孪晶。轧制态纯钛的显微硬度是182Hv，退火态纯钛的显微硬度是175.78Hv，经过一道次ECAP变形之后其显微硬度增加到253.5Hv。试样经1道次ECAP变形后，抗拉强度和延伸率分别为744.16MPa和16.87%，而轧制态的纯钛的抗拉强度和延伸率分别是446.42MPa和39.1%，退火态的抗拉强度和延伸率分别是468.35MPa和35.41%。

　　　经过退火处理后（100℃、150℃、200℃、300℃、400℃，1小时），一道次ECAP变形纯钛的硬度在100℃~200℃之间出现明显下降，在200℃之后硬度无太大变化。轧制态和退火态的纯钛在300℃退火之前硬度无大变化，300℃之后硬度略微下降。

关键词：大塑性变形；ECAP；显微组织；显微硬度；热稳定性；拉伸性能

Abstract:Pure titanium with 12 mm × 12 mm × 85 mm was subjected to equal channel angular pressing (ECAP) at different passes, in order to investigate microstructure, microstructure and tensile properties, thermal stability. The results show that the microstructure of the rolled titanium consists of equiaxed grains and twins, the microstructure of annealed titanium consists of the homogeneous equiaxed grains, and grains in pure titanium after 1 ECAP pass were elongated and twinned. Microhardness of rolling titanium is 182Hv, the annealing titanium is 175.78Hv, and the microhardness of the titanium by 1 pass increases to 253.5Hv. After 1 ECAP pass, the tensile strength and elongation of pure titanium is 744.16MPa and 16.87%, respectively, the tensile strength and elongation of rolled titanium is 446.42MPa and 39.1%, and the tensile strength and elongation of annealed titanium is 468.357MPa and 35.41%.   

　　　After the annealing treatment (100℃, 150℃, 200℃, 300℃ and 400℃, 1h), the microhardness of pure titanium annealed at 100℃ after 1 ECAP pass was decreased obviously, the microhardness after annealed at 200℃ has a little change. The microhardness of rolled titanium and annealed titanium before 300℃ annealing treatment has not much change, and it was slightly decreased after 300℃. 

Keywords：Severe plastic deformation; ECAP; microstructure; microhardness; thermal stability; tensile properties