扭转弹簧断裂原因分析

1.3 mm SWP-B弹簧钢丝生产的扭转弹簧在客户装配前发生断裂,弹簧断口以沿晶断裂为主。分析材料化学成分和组织,对弹簧断口附近和正常组织进行纵截面显微硬度测定,采用扫描电镜对断口进行宏观和微观检查,并用X射线能谱仪对断口进行分析。结果表明:扭转弹簧在电镀锌初期局部产生非正常组织马氏体,由于马氏体存在组织应力,与在酸洗和电镀锌时弹簧基体中的氢造成的内应力相互作用,导致扭转弹簧出现裂纹并滞后断裂。

Fracture cause analysis of torsion spring

The torsion spring made with SWP - B diameter 1.3 mm spring steel wire appeared fracture before consumer as- , fracture take intercrystalline fracture as main. To analyze the mechanical composition and microstructure, sembling the ： the longitudinal section micro-hardness of normal mierostructure near spring fracture was determined, adopting SEM to in- spect macro and micro fracture, and using X-ray energy dispersive spectroscopy（EDS） to analyze the fracture. The result indicated that the torsion spring appeared abnormal microstructure martensite locally at electro-galvanizing initial stage, the interaction between the microstructure stress due to martensite and the inter press due to hydrogen in spring matrix in the course of pickling and electro-galvanizing, leaded to torsion spring appearing crack and delayed fracture.