2A12铝合金外套螺母裂纹分析及改善

Crack analysis and improvement of 2A12 aluminum alloy outer nut

针对某飞机设备舱氧气导管接头2A12铝合金外套螺母多处发现裂纹的情况,通过裂纹宏观形貌、微观组织的观察,确定裂纹起始部位;通过扫描电镜、能谱分析确定螺母断口表面腐蚀物的化学成分,确定2A12铝合金螺母裂纹的性质属于应力腐蚀裂纹。针对裂纹的产生原因,采取装配连接增加碗形垫、润滑脂以及定力要求,优化气密检漏试剂和清洗要求等方法,降低拉应力,改变腐蚀介质环境,从而减小了裂纹出现的概率。

There are many cracks on 2 A12 aluminum alloy outer nut of oxygen pipe joint in an aircraft equipment cabin. The initial position of the crack was determined by observing the macro morphology and microstructure of the crack. The chemical composition of corrosion products on the fracture surface of 2 A12 aluminum alloy nut was determined by SEM and EDS analysis,and the nature of 2 A12 aluminum alloy nut crack was determined as stress corrosion crack. In view of the causes of cracks,some methods were adopted to reduce the tensile stress and change the corrosive medium environment,so as to reduce the probability of cracks,such as adding bowl shaped pad,grease and fixed force requirements,optimizing air tight leak detection reagent and cleaning requirements.