航空铝合金原位腐蚀疲劳性能及断裂机理EI北大核心CSCD

为了研究不同腐蚀条件下2024铝合金的疲劳性能,首先设计搭建原位腐蚀疲劳平台,然后分别进行无腐蚀疲劳、预腐蚀疲劳和原位腐蚀疲劳实验,分析不同腐蚀疲劳条件下2024铝合金的疲劳断裂行为,最后利用扫描电镜(SEM)表征宏、微观断口特征,探究失效机理。结果表明:相同腐蚀环境和时间下,预腐蚀和原位腐蚀疲劳寿命分别为无腐蚀疲劳寿命的92%和42%;在原位腐蚀疲劳条件下,滑移带挤入、挤出导致表面粗糙度增加,吸附较多腐蚀介质,加剧蚀坑演化,易于裂纹萌生并形成多个裂纹源。裂纹的连通形成更大尺寸的损伤,并在材料内部快速扩展。预腐蚀和原位腐蚀疲劳试件断口观察到大量脆性疲劳条带,并且原位腐蚀疲劳条带平均间距约为无腐蚀疲劳条带间距的2倍,说明原位腐蚀疲劳条件下裂纹扩展速率更快。

In-situ corrosion fatigue performance and fracture mechanism of aviation aluminum alloy

In order to study the fatigue properties of 2024 aluminum alloy under different corrosion fatigue conditions, First, an in-situ corrosion fatigue platform was established, and then non-corrosion fatigue test, pre-corrosion fatigue test and in-situ corrosion fatigue test were used to comparatively study the fatigue life and fracture mechanism of 2024 aluminum alloy. Scanning electron microscopy(SEM) was used to characterize the macro and micro fracture characteristics and explore the failure mechanism. The results show that the samples with the same corrosion environment and corrosion time, the fatigue life in in-situ corrosion fatigue test and in pre-corrosion fatigue test is 92% and 42% of corrosion fatigue life, respectively. Under the condition of in-situ corrosion fatigue, the squeeze and the extrusion of slip zone leads to the increase of surface roughness, which adsorbs more corrosive medium, exacerbates pit evolution, accelerates the initiation of crack and forms multiple crack sources. The connection of cracks forms a larger size of damage, and rapidly expands inside the material. A lot of brittle fringes are observed in the fracture of the pre-corrosion and in-situ corrosion fatigue test specimens, and the average distance between the fringes under in-situ corrosion fatigue is about two times larger than that under non-corrosion fatigue, indicating the crack propagation rate is faster under the in-situ corrosion fatigue condition.