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Will brushed stainless rust more easily
June 24, 2011
I would like to know if brushed stainless steel offers less rust protection due to the nature of the sanding process. My limited understanding is that the sanding process provides microscopic grooves in which water dirt and debris can take hold and form rust. I would appreciate your comments on this.
regards
Steve
Buyer - Vernon Hills, Illinois, USA
July 6, 2011
What ever you do, follow with a passivate, better yet electropolish, these processes counter steel contamination.... avoid steel contamination at all cost. repeat, avoid steel contamnation at all cost.... can't use SS wire brushes they deteriorate as steel.
It is my belief/understanding that if you are processing your parts in a near perfect steel free environment, you can skip the passivate/electropolish.... I wouldn't take the chance. you have to know exactly what you are doing. Welding?... those blue zones are chromium deplete, have to remove these. Have to understand why you can't use SS wire brushes.
A smooth finish would be optimal, but a brushed finish is fine in most cases, but the one place that even brushed SS can be troublesome would be a seaside dock railing where crevice/crack corrosion could be a long term issue. You better be specific about the grade of 300 series SS too .... don't use unknown flea market stuff.
If you are working steel free clean, passivate. otherwise work as steel free clean as you can and electropolish. one last thing - avoid steel contamination!!!
Sheet Metal Fab - Everett Washington
Your understanding is correct. If mechanical finishing leaves tears, shards and debris behind, it can promote corrosion. How severe the problem might be depends on the damage on a microscopic scale.
If you have access to a good microscope, take a look at the surface at 1000X. If it looks like a plowed field, you may have a problem.
The best surface for corrosion resistance is one which is featureless at 1000X and then passivated or electropolished.
Jeffrey Holmes, CEF
Spartanburg, South Carolina
July 6, 2011
July 8, 2011
I got all excited about steel contamination - your question specifically, from my experience with a recent project that went sour, and took a lot of research to remedy ...
Yes brushed SS is more susceptible to corrosion than smooth SS. but, it is my understanding that if the parts are processed correctly, with a strong argument for electropolishing, a brushed surface will be very durable. The one exception would be a salt water environment, like a seaside dock railing. The crack/crevice corrosion could be a long term problem, not something that rusts up in 2 days, but 2 years.
Good material, proper processing, not in a corrosive environment... brushed SS is durable. Steel contaminated brushed SS will rust in hours when exposed to salt water air. I can vouch for that as fact.
Sheet Metal Fab - Everett Washington USA
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