Microstructural evolution of commercially pure titanium(CP-Ti) produced by equal channel angular pressing (ECAP) at room temperature was analyzed with optical microscope and transmitted electron microscope. The experimental results show that the microstructural evolution is divided into three stages according to different evolution mechanisms. The first regime is the dislocation sliding and twinning mechanism when the true strains are ε≤ 1.27. It is proven that the grain size was fined from ～23 μm to ～0.35 μm and shear bands within high density dislocation and twins were formed. The second regime is the dynamic recovery mechanism when the true strains are 1.27 ＜ε＜ 2.54. In this procedure typical subgrain structures with the average grain size ～0.25 μm were formed. The third regime is non-equilibrium subgrain boundary rotating mechanism when the true strains are ε ≥ 2.54. After ECAP for 8 passes at room temperate, a homogeneous array of grains with equiaxed high angle boundaries was produced and the average grain size was measured as ～0.2μm.%在室温下以等径弯曲通道变形(ECAP)技术制备超细晶工业纯钛,利用光学显微镜(OM)和透射电子显微镜(TEM)研究室温ECAP变形纯钛微观组织演变过程,并讨论纯钛室温ECAP变形的显微组织演化机制.结果表明:显微组织演化分为3个不同阶段,分别对应3种不同机制:第一阶段在真应变ε≤1.27时,为位错滑移和孪生交互作用细化机制,形成含有高密度位错和孪晶的板条状组织;第二阶段在真应变量1.27＜ε＜2.54时,为动态回复细化机制,晶粒进一步细化至～0.25μm,形成典型的变形亚晶组织;第三阶段在真应变量ε≥2.54时,为不平衡晶界的转动细化机制,形成平均晶粒尺寸约为0.2μm的等轴状大角度晶界超细晶组织.
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