中文摘要：

选取热轧退火态的工业纯钛（CP-Ti）板材为研究对象,采用通道夹角Φ=135°的模具,在室温下进行CP-Ti板状试样1~8道次等径弯曲通道变形（ECAP）,利用金相显微镜（OM）和透射电镜（TEM）观察并分析了纯钛板材在不同道次变形后的组织演变过程。通过力学性能测试实验,分析了X,Y,Z面硬度的变化过程,研究了ECAP变形对CP-Ti力学性能的影响规律。结果表明：CP-Ti板材经过ECAP变形,晶粒逐渐拉长,组织位错大量增加,出现板条状组织;8道次ECAP变形后CP-Ti板材的晶粒明显细化,晶粒尺寸由原始的57.000μm细化到0.668μm;随着挤压道次的增加,组织位错逐渐消失,小角度晶界逐渐转变为大角度晶界,晶粒越来越细,最终达到纳米级别。CP-Ti板材1道次ECAP变形后硬度变化程度最大,X,Y,Z面的硬度增幅分别达32.6%,33.8%和32.9%;随着道次增加,8道次ECAP变形后,力学性能显著提高,X,Y,Z面的硬度最终达到1910,1943和1911 MPa。

英文摘要：

Hot-rolled annealed commercially pure titanium （CP-Ti） plate samples were processed by equal channel angular pressing （ECAP） for 1 -8 passes via route C at room temperature using a channel angle of φ = 135°. The microstrueture evolution of CP-Ti plate after different pass deformations was studied according to optical microscopy （OM） and transmission electron microscopy （TEM） observation and analysis. The hardness changes of X, Y, Z planes and the influence of ECAP deformation on mechanical properties of CP-Ti plates were investigated by mechanical properties test. The results showed that after ECAP deformation, the grains of CP-Ti plates were increasingly elongated, the dislocation density increased rapidly, and the banded structure of shear were activated; the grains of CP-Ti plates were obviously refined after 8 passes of ECAP deformation, which changed from the original value of 57. 000 to 0. 668 μm; with the number of passes increasing, the dislocations gradually disappeared, the low-angle grain boundary gradually trans- formed into high-angle grain boundary, the grain size was increasingly fine and ultimately reached nanometer level. The microhardness change of CP-Ti plates was the maximum after 1 pass, and the hardness values of X,Y,Z planes increased by 32.6% , 33.8% and 32. 9% , respectively; with the increase of passes, the mechanical properties of CP-Ti plates was significantly improved after 8 passes of ECAP deformation, and the hardness values of X,Y,Z planes were ultimately up to 1910, 1943 and 1911 MPa.