双轴加载下冷变形Zr-4合金的循环变形行为及其微观机理  

CYCLIC DEFORMATION BEHAVIOR AND MICROSCOPIC MECHANISM OF COLD-WORKED Zr-4 ALLOY UNDER BIAXIAL LOADING

作　　者：王航[1] 丁向东[1] 肖林[1] 孙军[1] 

机构地区：[1]西安交通大学金属材料强度国家重点实验室,西安710049

出　　处：《金属学报》2005年第5期517-522,共6页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目50271052教育部"优秀青年教师资助计划"项目资助

摘　　要：研究了冷变形Zr-4合金在双轴比例和非比例加载下的循环变形行为,结果表明:当循环应变幅较低时,Zr-4合金表现为循环初始硬化随后饱和的特征;随着应变幅提高,初期硬化后,表现为连续循环软化特征;高应变幅下,初期硬化消失,表现为急剧的循环软化.相同等效应变幅下,非比例加载下的Mises循环等效应力明显高于比例加载,表现为非比例附加硬化现象; 相位角30°时,非比例附加硬化程度最高.非比例加载下疲劳寿命低于比例加载.双轴疲劳变形亚结构TEM观察表明:当加载方式由比例加载转化为非比例加载时,疲劳位错结构由拉长的位错条带向位错缠结和位错胞转化,材料内部各向同性强化机理加强是Zr-4合金非比例潜在硬化的原因.Biaxial fatigue behaviors of the Zr-4 alloy under proportional and non-proportional loading with the phase angles of 30 degrees, 60 degrees and 90 degrees were studied. The cyclic Mises stress response curves as a function of the number of cycles consist of the first cyclic hardening and the following saturation stages at lower cyclic strain amplitudes under proportional and non-proportional loading. The initial cyclic hardening is followed by a continuous cyclic softening as cyclic strain amplitude increases. The striking cyclic softening is displayed at high cyclic strain amplitudes. The non-proportional cyclic additional hardening is displayed by the fact that the cyclic Mises stress curves under non-proportional loading lie above that under proportional loading at the same cyclic strain amplitudes. Zr-4 alloy exhibits the highest degree of additional hardening, when the phase angle is 30 degrees and the equivalent strain equals to 0.769%. The biaxial fatigue life decreases as the cyclic strain amplitude increases under proportional and non-proportional loading. The fatigue life under non-proportional loading is less than that under proportional loading at the same equivalent strain amplitudes. Deformation substructure examination by TEM reveals that the dislocation structure tends to form dislocation cells as well as tangle configuration as the loading mode changes from proportional to non-proportional loading. The isotropic hardening mechanism plays an important role in inducing an additional hardening in the cold-worked Zr-4 alloy.

关 键 词：ZR-4合金 比例加载 非比例加载 附加强化 位错 

分 类 号：TG111.2[金属学及工艺—物理冶金]