Metal finishing Q&As since 1989
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Increased Corrosion Protection Options for 316 Stainless Steel
Q. Hello. I have designed a 316L stainless steel bracket and plate to be used on a device that will be deployed in sea water. Although this grade has very good corrosion resistance, additional processing may be required to ensure the product can withstand several months in such a harsh environment. Duplex Stainless Steel (as well as other grades and materials) would be a good material choice, but the costs are prohibitive. Machining is required on the plate, and polishing the surfaces (the plate has many steps and other features) to a recommended finish suitable for corrosion resistance will be costly. I am considering passivation, electropolishing and powder coating as alternatives. My question is "Is powder coating a viable option and how does it compare with passivation and electropolishing in this application? What are the caveats?"
Thanks in advance for any input or advice.
Design Engineer - Broken Arrow, Oklahoma, United States
March 23, 2011
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A. The idea of Powdercoating the 316L components to improve corrosion resistance in seawater does have some merit.
Basically you would be providing a first line barrier coat.
The important things to watch are:
(1) adhesion, where it would be wise to lightly blast the surfaces to obtain a key.
(2) Selection of powder, if UV resistance is not an issue a Fusion bond epoxy would be suitable. If UV resistance is required a thermoplastic powder would be a better choice.
Standard Polyester powders will not do the job you are looking for.
Hope this helps,
Regards,
Bill
Trainer - Salamander Bay, Australia
A. I should also have added: ensure that the blast media you select does not itself contaminate the base metal.
Regards,
Bill
Trainer - Salamander Bay, Australia
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