中文摘要：

采用φ=105°模具在室温下对工业纯锆进行两道次ECAP变形,制备细晶工业纯锆试样。利用Gleeble-3500热模拟机分别对粗晶和细晶工业纯锆进行不同应变速率的室温压缩试验,获得其相应的真应力-真应变曲线,研究粗晶和细晶工业纯锆的压缩变形行为。结果表明：细晶工业纯锆屈服强度高于粗晶;但是由于变形机制的不同导致两者加工硬化能力不同,细晶工业纯锆稳态流变应力低于粗晶;粗晶和细晶工业纯锆的流变应力在变形初期随应变的增加而增大,出现峰值后逐渐趋于平稳,但两者峰值应变相差较大;流变应力随应变速率的增加而增大,呈现正的应变速率敏感性;在室温下,应变速率敏感性指数m值变化较小;SEM结果显示压缩后试样表面除了与压缩轴呈45°的大小不一的裂纹外,还有大量由于剧烈变形而产生的试样表面起伏形貌。与粗晶工业纯锆相比,细晶的应变速率敏感性指数有所升高,且压缩变形后细晶试样表面无明显裂纹,说明细晶工业纯锆具有更好的塑性变形能力。

英文摘要：

Two pass ECAP deformation of commercially pure Zr was carried out at room temperature by using φ = 105°die,and fine-grained zirconium sample was prepared. The compression test of coarse-grained and fine-grained commercially pure Zr were performed on the Gleeble-3500 testing machine at room temperature with different strain rates,and the true stress-true strain curves were obtained and used to study compression deformation behavior. The results show that the yield strength of fine-grained commercially pure Zr is higher than that of coarse-grained commercially pure Zr. But because of the different deformation mechanism leads to different work hardening ability,the finegrained commercially pure Zr steady flow stress is lower than that of the coarse-grained commercially pure Zr. The flow stresses of coarsegrained and fine-grained commercially pure Zr increase with increasing of strain and tend to be constant after a peak value,nerveless the peak strains have a great difference. The flow stress increases with the increase of strain rate and presents positive strain rate sensitivity. However,the strain rate sensitivity changes little at room temperature. It is indicated from SEM that not only cracks with different sizes were found after compression,which inclined the angle of 45° with the compression axis,but also a great number of the surface dimple morphology due to severe deformation. Compared with coarse-grained commercially pure Zr,the strain rate sensitivity index of the fine-grained is increased.And there is no obvious crack on the surface of the fine-grained after compression deformation indicating that the fine-grained commercially pure Zr has better plastic deformation ability.