某系列飞机中央翼第三墙外置机匣接耳应力腐蚀裂纹的成因与预防

摘要

目的 分析某系列飞机中央翼第三墙外置机匣接耳应力腐蚀裂纹的成因,并进行有针对性的预防.方法 对发生裂纹的接耳进行端口检测,并对应力腐蚀条件和腐蚀环境进行分析.结果 7B04铝合金在Cl-、超过应力腐蚀门槛值的应力和锻件夹杂的共同作用下,在表面氧化膜破裂的酸性环境下发生应力腐蚀.结论 应当改进飞机修理过程中的工艺方法 ,并对接耳设计进行适当的修改.%Objective To analyze the causes for stress corrosion cracking in the accessory gearbox attachment on central wing box′s third wall for a series of aircraft and to propose corresponding precautions. Methods Fracture detection on the external casing attachment and analysis of the stress corrosion conditions and corrosive environments were conducted. Results With the combined action of Cl-, stress that exceeded K1SCC and slag inclusions in the forgings, stress corrosion of the 7B04 aluminium alloy occurred under the acidic condition when the surface oxide film broke. Conclusion The techniques and ways of repairing aircrafts should be improved and moderate modifications on the design of the external casing attachment should be conducted.