7B04铝合金及其螺接件的微观腐蚀机制及耐久性研究  

Microscopic Corrosion Mechanism and Durability of 7B04 Aluminum Alloy and Its Screw Joint

作　　者：汪凤琴 苏艳[2] 钟勇[2] 左鹏程 庄宁 吴俊升 张博威 WANG Feng-qin;SU Yan;ZHONG Yong;ZUO Peng-cheng;ZHUANG Ning;WU Jun-sheng;ZHANG Bo-wei(Institute for Advanced Materials and Technology,University of Science and Technology Beijing,Beijing 100083,China;Southwest Institute of Technology and Engineering,Chongqing 400039,China)

机构地区：[1]北京科技大学新材料技术研究院,北京100083 [2]西南技术工程研究所,重庆400039

出　　处：《表面技术》2023年第10期181-193,共13页Surface Technology

基　　金：西南技术工程研究所合作基金项目(HDHDW5902020107);国家自然科学基金(51901018);中国科协青年托举人才项目(2019QNRC001);中央高校基本科研业务费(06500119);科技部科技基础资源调查专项资助项目(2019FY101400)。

摘　　要：目的 以飞机结构用7B04高强铝合金及其螺接件为实验对象,通过室内加速腐蚀试验模拟试样在南海海洋大气环境中的环境损伤,并深入分析其微观腐蚀机制与疲劳性能的内在联系。方法 通过数码相机、3D共聚焦显微镜、扫描电子显微镜等手段,研究模拟南海海洋大气环境下7B04铝合金及其螺接件的宏观/微观腐蚀特征,并借助疲劳测试分析经不同腐蚀周期后铝合金试样及螺接件的疲劳寿命。结果 铝合金及其螺接件经室内加速腐蚀试验后发生的腐蚀行为出现了明显差异,7B04铝合金试样表面发生的腐蚀行为以点蚀为主,而螺接件的腐蚀行为更加复杂。其中,远离螺接区域的暴露区的腐蚀情况与铝合金试样一致,在螺接区域发生了明显的缝隙腐蚀。此外,铝合金试样及螺接件随腐蚀周期变化的劣化规律也有所不同,腐蚀使得试样的疲劳性能均不同程度地下降。7B04铝合金疲劳寿命的递减趋势相对平缓,而螺接件在腐蚀进行到第2周期时其疲劳寿命就已降至原始寿命的一半,在腐蚀进行到第4周期时,螺接件的力学性能基本丧失。结论 经腐蚀后,铝合金试样出现了点蚀,且随着时间的延长出现了均匀腐蚀的趋势,疲劳寿命的递减趋势相对平缓。尽管螺接件的过渡区发生了严重腐蚀,但缝隙区诱发的局部腐蚀导致螺接件的受力面积减小,这是造成其疲劳寿命急剧衰减的首要因素。In this work,the 7B04 high-strength aluminum alloy and its screw joints for aircraft structure were selected as the test objects to study the corrosion behavior law in the marine atmospheric environment of the South China Sea under the simulation through indoor accelerated corrosion test.Moreover,the intrinsic correlation between its microscopic corrosion mechanism and fatigue performance was analyzed in depth.The macroscopic and microscopic corrosion characteristics of 7B04 high-strength aluminum alloy and its screw joints in the simulated marine atmosphere environment of the South China Sea were studied by means of digital camera,3D confocal microscope and scanning electron microscope,and the fatigue life of 7B04 high-strength aluminum alloy specimens and screw joints after different cycles of indoor accelerated corrosion was analyzed by fatigue test.The results indicated that the corrosion behavior of 7B04 high-strength aluminum alloy and its screw joints was significantly different after the indoor accelerated corrosion test,and the corrosion behavior of 7B04 high-strength aluminum alloy specimens could be concluded that uniform corrosion and pitting corrosion mainly occurred on the surface,while the corrosion behavior of screw joints was more complex.Therein,the corrosion of 7B04 aluminum alloy screw parts in the exposed area and away from the screw area was consistent with that of aluminum alloy specimens,but obvious crevice corrosion took place near the screw hole area.Owing to the long-term accumulation of corrosive solutions in the transition zone of the screw joint,the severe local thinning was caused on the spot.In addition,the regular of degradation of aluminum alloy specimens and screw joints was also different with the extension of corrosion cycle,and the corrosion made the performance on fatigue of 7B04 high-strength aluminum alloy and its screw joints degrade in varying degrees.The fatigue life of 7B04 aluminum alloy specimen was only reduced by 16.77% after 28 days of indoor accelerated corrosion

关 键 词：7B04铝合金 螺接件 点蚀 缝隙腐蚀 微观机制 疲劳寿命 

分 类 号：TG178[金属学及工艺—金属表面处理]