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本文研究了Al—Zn—Cu—Mg及Al—Mg—Cu在氯化物水溶液中用慢应变速率方法得到的应力腐蚀开裂的扫描电镜断口形貌。结果发现两种铝合金在氯化物水溶液中的应力腐蚀开裂断口复盖着—层腐蚀产物,这层腐蚀产物可以呈现不同的扫描电镜断口形貌,如类似解理的“平滑”形貌,“龟裂泥巴状”形貌等等。遮盖了应力腐蚀开裂固有的真实形貌;应力腐蚀开裂固有的真实形貌是相同的,呈典型的沿晶开裂形貌,盖有腐蚀产物层的形貌则取决于介质pH和电位。因此,应该根据铝合金应力腐蚀开裂固有的真实扫描电镜断口形貌来鉴别铝合金的应力腐蚀。将断口进行化学去膜处理可以得到铝合金应力腐蚀开裂的固有的真实的扫描电镜断口形貌。
In this paper, the fracture morphology of stress corrosion cracking of Al-Zn-Cu-Mg and Al-Mg-Cu in chloride aqueous solution was studied by slow strain rate method. The results show that the stress corrosion cracking of the two aluminum alloys in chloride aqueous solution is covered with a layer of corrosion products that exhibit different SEM morphology such as a “smooth” morphology similar to cleavage and “ Cracked mud-like ”morphology and so on. The true appearance of stress corrosion cracking is covered by the actual appearance of stress corrosion cracking. The intrinsic appearance of stress corrosion cracking is the same, typical of the intergranular crack morphology. The morphology of the corrosion product layer depends on the pH and potential of the medium. Therefore, the stress corrosion cracking of aluminum alloy should be identified according to the fracture morphology of the real scanning electron microscope inherent in stress corrosion cracking of aluminum alloy. The fracture of the chemical de-filming process can get the inherent stress corrosion cracking of aluminum alloy rupture morphology of the SEM.