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Stainless springs are breaking -- is passivation to blame?

We currently use 302 stainless steel springs in a valve that handles gasoline. The spring wire is 0.16" diameter. The springs are actually wetted by the gas. We have experienced occasional breakage and permanent setting of the springs. Would improper or excessive passivation of the spring have a detrimental effect on the spring material? Could the springs become brittle if the passivation process used too high of a concentration of acid or if the parts were immersed in the acid for an excessive time period?

Doug Dye
engineer - Richmond, Virginia, USA
October 13, 2010

I doubt it, but anything is possible. I am not associated with springs, but my guess is that you are inducing a huge amount of stress in the spring in the winding process. I would think that you would do a stress relief cycle before the passivation. Not such a high temperature as to soften the metal. 302 is not particularly oven hardenable, but it will work harden and I think that is your problem

James Watts
- Navarre, Florida
October 14, 2010