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Corrosion in Latch Type Solenoid Valve

We are facing problem of corrosion/pitting in the solenoid valve plunger and seat which come into contact with water. We have tried out electroless-nickel plating, wherein the parts losing its magnetic property. The base material being used is SS430. We need suggestions on what type coating/finishing can be applied to get corrosion resistance as well as retaining the magnetic property.

Bhavani Sankar
- Chennai, Tamilnadu, India
2005

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Mr. Bhavani Sankar,

The pitting corrosion is due to the higher concentrations of chloride ions in the water. Stainless steels are highly susceptible to localized corrosion attack in chloride containing environments.

Electroless Ni-P coating offers high corrosion resistance on steel. However, the adhesion of the coating on stainless steel will be poor.

T.S.N. Sankara Narayanan
- Chennai, Tamilnadu, India
(ed.note Nov. 2017: The good doctor has a fascinating blog at https://advancementinscience.wordpress.com)
2005

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I am quite amazed that 1 mill of EN would eliminate the magnetic properties of the 430SS underneath. I suspect that it is more of a reduction than you can live with.

Since EN is out, consider shifting from 430 to 440 SS. It has 1% more chrome and 0.6 % Mo. That is enough Mo to make a major difference in the corrosion resistance of your part. Certainly worth a trial part.


For TSN, SS 430 properly activated and struck with a Woods nickel strike and immediately put into the EN Tank (after a rinse) you should have excellent adhesion. 400 series is a piece of cake vs 300 series. You want difficult, look at Hastelloy or Waspaloy.

James Watts
- Navarre, Florida
2005