Low-cycle fatigue properties before/after cold expansion under multiple conditions were comparatively researched. The results showed the fatigue cycles of the cold-expanded specimens are more than doubled compared to the original, and the fatigue gain decreased as the stress increased. Surface smoothing, surface compressive residual stress field, and cold work-hardened structure with the sub-grain refinement were recognized as the main reasons for increasing the initiation life. The relatively stable compressive residual stress under 400 °C aging and 820 MPa/RT limited the crack propagation, making the width of the fatigue band and the crack propagation speed of cold-expanded specimen smaller than hole-reamed at the same depth.

对比研究了多种工况下冷胀前后的低周疲劳性能。结果表明，冷扩试样的疲劳循环次数比原来增加了一倍以上，并且疲劳增益随着应力的增加而减小。表面光洁度、表面压缩残余应力场和具有亚晶粒细化的冷加工硬化结构被认为是提高起始寿命的主要原因。400℃时效和820MPa/RT下相对稳定的残余压应力限制了裂纹扩展，使得冷扩试样的疲劳带宽度和裂纹扩展速度小于相同深度的扩孔试样。