Effect of Periodic Overloads on Short Fatigue Crack Behavior in CuNi2Si Alloy under Rotating Bending Load

Metals

Yahang Qin¹  Bo Feng¹  Tao Zhu¹  Yifan Li¹  Shoune Xiao¹  Bing Yang¹  Guangwu Yang¹ 

[1] State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, China;

关键词: Cu-Ni-Si alloy;    overload;    fatigue crack;    fatigue fracture;   

DOI  :  10.3390/met10091267

来源: DOAJ

【 摘 要 】

In this study, the short fatigue crack behavior in a precipitation-strengthened CuNi₂Si alloy was investigated using a replica technique under rotating bending loads with periodic overloads, an overload ratio of 1.5, and the stress ratio of both was R = −1. The results show that all the fatigue cracks originated from the surface of the specimen and displayed a trend of slow initiation and then rapid propagation. The introduction of overloads significantly reduced the fatigue crack initiation time and the fatigue life of the sample. The average life of the overloaded samples was only 31% that of the constant load samples. For overload specimens, multiple cracks grew at the same time and merged at different stages, causing the crack length to increase instantaneously after they merged, thereby considerably reducing the fatigue life. Fractographical analysis and observation of the surface-etched sample replica film showed that cracks in samples with and without overload both propagated along the grain boundaries.

【 授权许可】

Unknown