The present study addresses the effect of tensile pre-strain histories on cyclic plastic deformation behaviour of 7050-T6 aluminium alloy. Low-cycle fatigue tests are conducted under fully-reversed conditions, with 8% tensile pre-strain, 4% tensile pre-strain, and 0% tensile pre-strain, at different strain amplitudes. After fatigue testing, fracture surfaces are examined by scanning electron microscopy and transmission electron microscopy to identify the main failure micro-mechanisms associated with the levels of pre-strain and strain amplitude. Microstructure is analysed by X-ray diffraction, transmission electron microscopy, and optical microscopy. The main findings suggest that tensile pre-strain histories are conducive to a reduction in fatigue life. This reduction increases with higher strain amplitudes.

本研究解决了拉伸前应变历史对7050-T6铝合金循环塑性变形行为的影响。在完全反向的条件下进行低周疲劳测试，在不同的应变幅度下，拉伸预应变为8％，拉伸预应变为4％，拉伸预应变为0％。在疲劳测试之后，通过扫描电子显微镜和透射电子显微镜检查断裂表面，以识别与预应变和应变幅度水平相关的主要失效微观机制。通过X射线衍射，透射电子显微镜和光学显微镜分析微观结构。主要发现表明，拉伸前应变的历史有助于减少疲劳寿命。随着较高的应变幅度，该减小增加。