航空发动机管路应力腐蚀断裂分析及防治措施

Analysis and Prevention Measures of Stress Corrosion Fracture of Aeroengine Pipes

针对航空发动机管路断裂故障,对管路故障件进行断口检查分析、结构设计分析、加工制造分析以及强度分析等,识别出管路故障的原因为应力腐蚀断裂,其根本原因为管路材料晶粒度粗大、管路结构位移补偿能力不足产生的应力以及腐蚀环境的共同作用产生晶间裂纹。根据分析结果提出结构优化设计、优化焊接工艺以及增加管路表面涂层等改进设计措施,对各项改进措施开展了强度分析、工艺试验、应力测试试验,以及应力腐蚀试验验证。结果表明:对于刚度较大的短管增加折弯能够降低结构的应力水平;管接嘴的结构形式对焊接局部的应力存在影响,优化接嘴结构可以提高管路整体的承载能力;通过合理的焊接工艺能够控制材料组织晶粒度,降低结构应力腐蚀敏感度;在管路表面增加耐腐蚀涂层是一种有效的防腐蚀方法。

In view of the fracture failure of the aeroengine pipe,the fracture inspection analysis,structural design analysis,manufacturing analysis,and structural strength analysis of the pipe failure were carried out,and the cause of the pipe failure was identified as stress corrosion fracture,the root cause of which is the intergranular crack caused by the interaction of the coarse grain size of the pipe body material,the stress caused by insufficient displacement compensation ability of the pipe structure,and the corrosive environment.According to the analysis results,some measures were put forward,such as structural design optimization,welding process optimization,applying pipe surface coating,etc.Strength analysis,process test,stress testing,and stress corrosion testing were carried out to verify the improvement measures.The results show that the increase in bending of short pipes with larger stiffness can reduce the stress level of the structure.The structural form of a pipe joint influences the local stress of the welding structure.The optimized pipe joint structure can improve the overall bearing capacity of the pipe.Reasonable welding processes can control the grain size of the material structure and reduce the sensitivity of stress corrosion.Adding a corrosion-resistant coating to the pipe surface is an effective anti-corrosion method.