扭转弹簧镉脆断裂失效分析

Failure Analysis of Spiral Spring Cadmium Embrittlement Fracture

镀镉的扭转弹簧在装配时发生断裂。采用了能谱分析、金相分析和扫描电镜分析等手段,对弹簧断口进行了宏观和微观分析。结果表明,绕制过程中残余在弹簧中的拉应力以及在除氢过程超温,致使大量的镉渗入到晶格之间,进而导致晶格之间结合力降低且脆化。在外力作用下,导致沿晶脆性断裂。

It was found that a kind of cadmium plated spiral s pr ings fractured frequently during assembly.Macroscopic and microscopic investiga tion and analysis of the fractured spring were made with the use of measures of metallography,EDS and SEM.The results indicate that residual stress exists in the spring on the winding process of the spring and a large amount of cadmium at oms penetrate into the gaps between lattices of the spring substrate as temperat ure exceeds the prescribed value during the dehydrogen process of the spring aft er cadmium plating.These lead to cadmium embrittlement fracture along crystal b oundaries of the spring substrate under the action of an external force.