ECAP+旋锻变形制备超细晶纯锆的高周疲劳行为  

High-Cycle Fatigue Behavior of the Ultrafine-Grained Commercially Pure Zirconium by ECAP+RS Process

作　　者：杨西荣[1,2] 柳峰 罗雷 冯广海[1] 刘晓燕[1,2] 赵西成[1] Yang Xirong;Liu Feng;Luo Lei;Feng Guanghai;Liu Xiaoyan;Zhao Xicheng(Xi'an University of Architecture and Technology,Xi'an 710055,China;Metallurgical Engineering Technology Research Center of Shaanxi Province,Xi'an 710055,China)

机构地区：[1]西安建筑科技大学,陕西西安710055 [2]陕西省冶金工程技术研究中心,陕西西安710055

出　　处：《稀有金属材料与工程》2019年第8期2609-2615,共7页Rare Metal Materials and Engineering

基　　金：国家自然科学基金（51474170）;陕西省教育厅专项科研计划项目（14JK1391）;陕西省教育厅重点实验室科研计划项目（15JS058)

摘　　要：室温采用等通道变形和旋锻复合工艺制备超细晶工业纯锆。对比研究了超细晶和粗晶工业纯锆拉伸和疲劳性能,并运用SEM对疲劳断口形貌进行观察和分析。结果表明:超细晶工业纯锆的室温抗拉强度明显大于粗晶工业纯锆,延伸率有一定程度地降低。超细晶工业纯锆疲劳性能优于粗晶工业纯锆,其应力幅(σa)与疲劳寿命(Nf)满足σa=750Nf-0.06,疲劳极限σ-1为285 MPa,较粗晶工业纯锆提高了70%。断口分析显示,疲劳裂纹萌生于超细晶工业纯锆的表面,疲劳裂纹扩展区辉纹间距较粗晶工业纯锆细小,疲劳裂纹扩展更为缓慢。Ultrafine-grained commercially pure Zr(UFG Zr) was fabricated by equal channel angular pressing(ECAP) coupled with subsequent rotary swaging(RS). The tensile properties and fatigue behavior of the commercially pure Zr with ultrafine-grained microstructure were investigated, and the results were compared with those of the commercially pure Zr with coarse-grained counterpart. Fracture surfaces were examined to study the fatigue fracture failure mechanism using SEM. The result shows that the ultimate tensile strength of UFG Zr is obviously higher than that of the coarse-grained Zr(CG Zr) at room temperature, while the CG Zr exhibits a higher fracture elongation. The fatigue life of UFG Zr is significant higher than that of CG Zr. The relationship between the applied stress(σa) and cycles to failure(Nf) is determined as:σa=750 Nf-0.06. The conditional fatigue limit of UFG Zr is about 285 MPa, which is improved by 70% compared with that of CG Zr. The fractography analysis reveals that fatigue cracks mainly initiate from the surface of the UFG Zr specimen. The spacing of the fatigue striations of UFG Zr is smaller than that of CG Zr, which indicates that the crack propagation rate of UFG Zr is lower than that of CG Zr.

关 键 词：超细晶纯锆 高周疲劳 疲劳寿命 疲劳断裂 

分 类 号：TG146.414[一般工业技术—材料科学与工程]