The effect of natural aging by multifunction cavitation (MFC) on the fatigue behaviour of heat-treatable Al-Si7Mg aluminum alloys was examined. Surface observation and plane bending fatigue tests were conducted for the MFC-treated aluminum alloys at a stress ratio, , of −1. The hardness of aluminum alloy without T6 treatment was significantly increased by MFC due to both the work hardening and natural aging. MFC treatment improved the fatigue lives and the fatigue strength at = 10 cycles of aluminum alloys due to the generation of compressive residual stress and increasing the surface hardness; however, surface pits were large enough to easily nucleate an initial fatigue crack. In addition, the fatigue strength at = 10 cycles of MFC-treated aluminum alloys can be estimated considering the residual stress, pit size and surface hardness.

中文翻译：

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多功能空化自然时效对可热处理Al-Si7Mg铝合金平面弯曲疲劳行为的影响及其疲劳强度估算

研究了多功能空化 (MFC) 自然时效对可热处理 Al-Si7Mg 铝合金疲劳行为的影响。对 MFC 处理的铝合金在应力比 为 -1 的条件下进行表面观察和平面弯曲疲劳试验。由于加工硬化和自然时效，未经T6处理的铝合金的硬度通过MFC显着增加。 MFC处理由于产生压缩残余应力并提高表面硬度，提高了铝合金的疲劳寿命和=10次循环时的疲劳强度；然而，表面凹坑足够大，很容易形成初始疲劳裂纹。此外，考虑到残余应力、凹坑尺寸和表面硬度，可以估计经 MFC 处理的铝合金在 = 10 次循环时的疲劳强度。