摘要
某型飞机在修理过程中发现一颗M6×30的35CrMnSiA紧固螺钉发生了断裂现象,影响了飞机使用安全。对断裂紧固螺钉进行了化学成分、宏微观断口、显微组织以及力学性能等验证与分析,确定螺钉断裂形式为疲劳断裂,且不存在材料冶金缺陷、热处理缺陷及加工缺陷,初步推断螺纹的车加工方式可能是裂纹产生的主要原因。随后对滚丝加工成型的同材质螺钉进行疲劳性能验证,选择与断裂紧固螺钉同批次材料和除螺纹滚丝成型外相同加工工艺,重新生产的紧固螺钉进行拉-拉疲劳试验比对分析。每种加工方式选取3个平行试样,试验方法为GJB715.30A—2002《紧固件试验方法 拉伸疲劳》,试验结果表明:滚丝成型螺钉疲劳寿命达到50万次未见破坏,而车加工螺纹疲劳寿命5.02万次时螺纹就发生了断裂,断口与服役断裂紧固螺钉断口相似。滚丝成型螺钉疲劳性能远优于螺纹车加工成型螺钉,最终确定螺纹车加工方式是导致螺钉断裂的主要原因。为消除后续隐患,建议完善螺钉成型工艺方法,停用该批次螺钉。研究结果为螺钉的优选、工艺方法的改善提供了依据,对提升飞机使用安全具有重要意义。
A breakage phenomenon of a M6×3035CrMnSiA fastening screw is found in the process of repair at a certain type of an aircraft.This case affecting the use safety of the aircraft,the chemical composition,macro and micro fracture,microstructure and mechanical properties of the broken fastening screw are verified and analyzed.The fracture form of the screw is confirmed as fatigue fracture,and there are no metallurgical defects,heat treatment defects and processing defects.The main reasons for the crack are preliminarily inferred by the machining mode of the screw.Subsequently,the fatigue performance of screws with the same material formed by screw rolling is verified.The same batch of materials as the broken fastening screws and the same processing technology except screw rolling are selected to conduct a comparative analysis of pull-pull fatigue test for the reproduced fastening screws.Three parallel samples are selected for each processing method,and the test method is GJB 715.30A—2002[Fastener Test Method for Tensile Fatigue].The test results showed that The fatigue life of the rolling screw reaches 500,000 times without any damage,while the thread fracture occurs when the fatigue life of the machining thread is 50200 times,and the fracture is similar to the fracture of the fastening screw in service.The fatigue performance of the screw formed by rolling wire is much better than that of the screw made by thread turning.In order to eliminate the follow-up risks,the paper suggests to improve the screw forming process and stop using this batch of screws.The research results provide a basis for the optimization of screw and the improvement of technological method,and are of great significance for the improvement of aircraft safety.
作者
王春净
许永春
赵常振
WANG Chunjing;XU Yongchun;ZHAO Changzhen(Aviation Maintenance NCO School,Air Force Engineering University,Xinyang 464000,Henan,China;Henan Aerospace Precision Machining CO.,Ltd,Xinyang 464000,Henan,China)
出处
《空军工程大学学报》
CSCD
北大核心
2022年第5期108-111,共4页
Journal of Air Force Engineering University
