不同加载模式下析出强化CuNiSi合金的疲劳裂纹扩展行为
Fatigue Crack Growth Behaviour of Precipitate-Strengthened CuNiSi Alloy under Different Loading Modes.
作者信息
Yang Bing, Li Yifan, Qin Yahang, Zhang Jiwang, Feng Bo, Liao Zhen, Xiao Shoune, Yang Guangwu, Zhu Tao
机构信息
State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, China.
出版信息
Materials (Basel). 2020 May 12;13(10):2228. doi: 10.3390/ma13102228.
In this study, fatigue crack tests of CuNiSi alloys using the replica technique under symmetrical tensile-compression loading, and rotational-bending loading were carried out with the same nominal stress amplitude. Observation and analysis results indicate that under different load types, the cracks display a trend of slow initiation growth and then rapid growth. The critical point is identified at the approximate value of 0.8 of the fatigue life fraction, and the crack growth rate of the sample under tensile-compression load is approximately an order of magnitude higher than that under rotational-bending load, resulting in the average life of the former being significantly shorter than the latter. Combining the observation results of the fractographical analysis and the surface-etched sample replica film, it can be seen that whether it is a tensile-compression load or a rotational-bending load, cracks mainly propagate in intergranular mode after initiation.
在本研究中，对CuNiSi合金进行了疲劳裂纹试验，采用复型技术，在对称拉伸-压缩加载和旋转弯曲加载下，以相同的名义应力幅值进行。观察和分析结果表明，在不同载荷类型下，裂纹呈现出先缓慢萌生扩展然后快速扩展的趋势。在疲劳寿命分数约为0.8的近似值处确定了临界点，拉伸-压缩载荷下试样的裂纹扩展速率比旋转弯曲载荷下的大约高一个数量级，导致前者的平均寿命明显短于后者。结合断口分析和表面蚀刻试样复型膜的观察结果可以看出，无论是拉伸-压缩载荷还是旋转弯曲载荷，裂纹萌生后主要沿晶界模式扩展。
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