Hou Jia-Peng, Wang Qiang, Yang Hua-Jie, Wu Xi-Mao, Li Chun-He, Zhang Zhe-Feng, Li Xiao-Wu
Department of Materials Physics and Chemistry, School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China.
Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China.
Materials (Basel). 2016 Sep 8;9(9):764. doi: 10.3390/ma9090764.
Fatigue properties and cracking behavior of cold-drawn commercially pure aluminum wires (CPAWs) widely used as the overhead transmission conductors were investigated. It was found that the fracture surface of the CPAWs shows an obvious four-stage fracture characteristic, i.e., crack initiation, planar crack propagation, 45°-inclined crack propagation and final rapid fracture. The crack growth mechanisms for the CPAWs were found quite different from those for the conventional coarse-grained materials. The cracks in the CPAWs firstly grow along the grain boundaries (Stage I crack growth), and then grow along the plane of maximum shear stress during the last stage of cycling (Stage II crack growth), leading to the distinctive fracture surfaces, i.e., the granular surface in the planar crack propagation region and the coarse fatigue striations in the 45°-inclined crack propagation region. The grain boundary migration was observed in the fatigued CPAWs. The increase in fatigue load enhances the dislocation recovery, increases the grain boundary migration rate, and thus promotes the occurrence of softening and damage localization up to the final failure.
对广泛用作架空输电导线的冷拉工业纯铝线（CPAW）的疲劳性能和开裂行为进行了研究。发现CPAW的断口呈现出明显的四阶段断裂特征，即裂纹萌生、平面裂纹扩展、45°倾斜裂纹扩展和最终快速断裂。发现CPAW的裂纹扩展机制与传统粗晶材料的裂纹扩展机制有很大不同。CPAW中的裂纹首先沿晶界扩展（阶段I裂纹扩展），然后在循环的最后阶段沿最大剪应力平面扩展（阶段II裂纹扩展），导致独特的断口，即平面裂纹扩展区域的颗粒状表面和45°倾斜裂纹扩展区域的粗大疲劳条纹。在疲劳的CPAW中观察到了晶界迁移。疲劳载荷的增加增强了位错恢复，提高了晶界迁移率，从而促进了软化和损伤局部化的发生，直至最终失效。
