Abstract The purpose of this study was to examine weldability of an AA7072-cladded high-strength AA7075-T6 via ultrasonic spot welding, focusing on the influence of welding energy on mechanical properties and failure mechanisms. Defect-free sound joints were achieved with robust bonding and grain refinement via dynamic recrystallization at the weld interface, leading to superior static and fatigue properties. The nominal tensile lap shear strength increased with increasing welding energy, and exceeded AWS D17.2 standards at higher energy levels. Interfacial failure at higher cyclic loads with distinctive elongated shear dimples and fatigue striations and transverse through-thickness failure at lower cyclic loads were observed.

中文翻译：

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复合 7075 铝合金的超声波点焊：强度和疲劳寿命

摘要 本研究的目的是通过超声波点焊检测 AA7072 包覆高强度 AA7075-T6 的可焊性，重点研究焊接能量对机械性能和失效机制的影响。通过焊接界面处的动态再结晶实现牢固的结合和晶粒细化，从而实现了无缺陷的良好接头，从而实现了优异的静态和疲劳性能。名义拉伸搭接剪切强度随着焊接能量的增加而增加，并在更高的能量水平下超过 AWS D17.2 标准。观察到在较高循环载荷下的界面破坏具有独特的细长剪切凹坑和疲劳条纹，并在较低循环载荷下观察到横向全厚度失效。