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Which is the best corrosion protection coating for spring steel?

May 18, 2009

There are people that manufacture pieces in spring steel to be used in very hostile places like shafts for spearfishing equipment. Where uncoated pieces will rust in hours these pieces last for very long time. Manufacturer claims a 500 hour salt spray test in these shafts.

It seems that it is a type of electroplated zinc with some corrosion inhibition agent and some information leads to some automotive industry standards like TOYOTA TSH6524G:2004 Electroplated zinc coating or similar.

Do you know which process can give you these good results in such a demanding application?

Fernando Abello
Plating articles designer & manufacturer - Spain, Europe

Hi, Fernando. What is best for spearfishing equipment will not be what is best for Toyota, and may not be what is best for you. The process always starts by defining the article to be protected, and its environment and its needs -- unfortunately, it can never successfully start with the question "what is the best plating?". Further, salt spray hours are meaningless; salt spray testing is a quality assurance mechanism to predict when a process is going South; it is not a measure of durability in a real-life environment because the corrosion mechanism and corrosion-defense mechanism is different in real life exposures.

If your component is spring steel, you could zinc plate, chromate conversion coat, then electrocoat, and powder coat it for a very corrosion resistant finish. There is also a good chance than a QPQ salt bath nitriding process, or an electroless nickel plating process, or a nickel-chrome plating process could deliver what you want -- depending on whether an organic or inorganic process fits your needs best. Good luck.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
May 19, 2009