AA7075 high-strength aluminum alloy, which has many applications in the aircraft, marine and automobile industries, happens to be susceptible to stress corrosion cracking (SCC) when exposed to corrosive environments, resulting in reduced service life of the components. Inappropriate fabrication processes may augment this behavior. The fabrication of AA7075 components using conventional fusion welding processes may produce defects that include hot cracking and porosity. Friction stir welding (FSW) is a solid-state joining process that can avoid these problems and being widely used for components made of aluminum alloys. Because the joining occurs at a temperature that is lower than the melting point of the material, solidification cracking defects can be eliminated. This study investigates the SCC behavior of FSW AA7075-T651 joints. Horizontal-type SCC test was conducted on circumferential-notched tensile (CNT) specimens exposed to 3.5 wt. % NaCl solutions under various axial stress conditions. The different regions of the fractured specimens, such as the machined notch, SCC region and region of ultimate mechanical failure were analyzed by scanning electron microscopy (SEM) to establish the mechanism of SCC. The threshold stress of parent metal (PM) and stir zone (SZ) of the FSW joint were found to be 242 and 175 MPa, respectively.

中文翻译：

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搅拌摩擦焊接AA7075-T651铝合金接头的搅拌区应力腐蚀开裂行为

AA7075高强度铝合金在飞机，船舶和汽车工业中有许多应用，当暴露在腐蚀性环境中时，很容易受到应力腐蚀开裂（SCC）的影响，从而缩短了组件的使用寿命。不适当的制造过程可能会加剧这种现象。使用常规的熔焊工艺制造AA7075组件可能会产生包括热裂纹和孔隙率在内的缺陷。搅拌摩擦焊（FSW）是一种固态焊接工艺，可以避免这些问题，并广泛用于铝合金制成的部件。因为接合在低于材料的熔点的温度下发生，所以可以消除凝固裂纹缺陷。这项研究调查了FSW AA7075-T651接头的SCC行为。在暴露于3.5 wt。在各种轴向应力条件下的％NaCl溶液。通过扫描电子显微镜（SEM）分析了断裂试样的不同区域，例如加工的缺口，SCC区域和极限机械破坏区域，从而建立了SCC的机理。FSW接头的母材金属（PM）和搅拌区（SZ）的阈值应力分别为242和175 MPa。通过扫描电子显微镜（SEM）分析了SCC区域和最终的机械失效区域，以建立SCC的机理。FSW接头的母材金属（PM）和搅拌区（SZ）的阈值应力分别为242和175 MPa。通过扫描电子显微镜（SEM）分析了SCC的区域和最终的机械失效区域，以建立SCC的机理。FSW接头的母材金属（PM）和搅拌区（SZ）的阈值应力分别为242和175 MPa。