Abstract

The effect of single overload on the fatigue crack growth in 2024-T3 and 7075-T6 Al alloys was analyzed. Fatigue tests under constant-amplitude loading with overload peak were carried out on V-notched specimens. Fractographic analysis was used as a principal approach to explain the crack growth retardation due to the overload. Scanning electron microscopy (SEM) analyses were conducted on the fractured surface of failed specimens to study the retardation effect. The obtained results show that the overload application generates a plastic zone in both aluminum alloys. The generated plastic zone is three times larger in the case of 2024-T3 compared to 7075-T6, and thus, a significant crack retardation was induced for 2024-T3. The retardation effect due to the overload for 2024-T3 and 7075-T6 lasted for about 10 mm and 1 mm, respectively, from the point of overload application.

中文翻译：

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过载对2024-T3和7075-T6铝合金疲劳裂纹扩展的分形分析

摘要

分析了一次过载对2024-T3和7075-T6铝合金疲劳裂纹扩展的影响。在V形缺口试样上进行了具有超载峰值的等幅载荷下的疲劳试验。分形分析被用作解释由于过载导致的裂纹扩展延迟的主要方法。在失效样品的断裂表面上进行扫描电子显微镜（SEM）分析，以研究延迟效应。获得的结果表明，过载应用在两种铝合金中都产生了塑性区。在2024-T3情况下，生成的塑性区是7075-T6的三倍，因此，对于2024-T3产生了明显的裂纹延迟。2024-T3和7075-T6因过载而产生的延迟效应分别持续了约10 mm和1 mm，