接头螺纹咬死失效原因分析

Failure Analysis for Screw Thread of Joint

管路接头在拆除时发生螺纹失效,本文对失效螺纹结构件形貌观察与测量,并对其材质进行硬度检验、金相分析。结果表明,管路接头螺纹发生了咬死,属损坏程度最严重的一类黏着磨损。依据黏着磨损发生的机理,结合螺纹连接结构的装配原理,最终确定选用同一种材料作为摩擦副是导致接头螺纹发生黏着磨损的内因;柱塞接头与螺纹接头间隙过小,导致安装过程中接头螺纹的螺纹齿形受损,产生多余物堆积,造成外套螺母向一侧偏斜是造成此次螺纹副发生咬死的主要原因。

A screw failure was found when the line joints were taken apart. This paper records the results of macroscopic observation, the microscopic observation and measurement, the observation of the screw, and the materi- al tests of the failure part, such as hardness test and metallographic analysis. The results indicated a seizure of the threads on the line joints which originated in an adhesive wear, the type of which causes most severe damage. Com- bined with the assembly mechanism of the screw thread connection, it is concluded that using the same material is the internal cause of the adhesive wear of the line joint. Too little interspaces between the joint which leading the screw thread of the joint broken during installation and the remainders accumulate made the nut deflexion is the main cause of the adhesive wear of the line joint.