螺栓底座裂纹分析

本文分析了飞机前襟翼作动筒连接螺栓底座表面裂纹的形成原因。对底座表面裂纹形貌以及渗层组织进行了观察，并且对螺栓的化学成分以及硬度进行了测定。结果表明，螺栓底座的表面裂纹为渗碳层裂纹，该裂纹性质为疲劳裂纹，裂纹起始于微动腐蚀形成的表面点蚀坑。采用显微硬度法检查渗碳层深度为1．2mm，超过了渗碳层深度的设计要求（0．6—1mm）。分析认为，螺栓底座表面裂纹的形成与渗碳层深度超标有关，而微动磨损产生的点蚀坑促进了渗碳层疲劳裂纹的萌生。

Analysis on Surface Cracks of a Bolt Bed

The cause of the surface cracks of a bolt bed was analyzed in this paper. The crack appearances and the structure of the carburized layer were observed ; the chemical composition and hardness of the bolt were determined. The results showed that the cracks occurred in the carburized layer, and they were caused by fatigue. The cracks initiated from the corrosive pits on the surface caused by fretting corrosion. The results of micro-hardness tests showed that the depth of the carburized layer was about 1.2mm, above the design standard（0.6 - 1.0mm）. It was concluded that the formation of the cracks was related to the abnormal depth of the carburized layer, and the corrosive pits promoted the initiation of the cracks.