201 stainless vs. 304 stainless

[dgowans]

We've got a product currently being fabricated out of type 304 stainless. Our supplier is suggesting changing material to type 201 for cost reduction purposes. The document I received on the proposed material looks good for the most part (granted, it's from Allegheny Ludlum), but I'm a little concerned about the slightly lowered corrosion resistance. The document I have is not very quantitative, it just says that type 304 is slightly better as far as crevice corrosion and pitting resistance goes.

The application is an outdoor pole mounted electronics enclosure with a predicted field life of 20+ years. Am I being too picky here? I'm more of a plastics guy, so I thought I'd pose the question here.

Thanks,
Dave Gowans

 

[EdStainless]

If 304 holds up fine then I wouldn't worry about 201. It does have lower corrosion resistance, but it is slight. A good surface finish and passivation and you will never know the difference.
Do you really want to save money? Are you using the lightest gage material practical? Using less metal will save you money even if the price goes down.

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[gieter]

Have a look at this:

url:

http://www.euro-inox.org/pdf/map/paper/Thenew200-series_EN.pdf

 

[dgowans]

Any concerns about the field deployment being in coastal areas such as the SF Bay area or Florida where salt fog will be present?

Thanks again,
Dave Gowans

 

[unclesyd]

We tried using the 200 series SS outdoors at our site, Gulf Coast on a bay, and it wasn't very successful. It was tried both as flange shields and panels.

We also tried it for components around our synthetic fiber process and it failed early on. This was probably due to finish used on the fibers. The finish had both fatty acids and other organics with a PH of around 5.

 

[EdStainless]

201 will requre more care with the surface finish, but it should work fine.
There are 201 samples at Kure Beach for many years. Ask Allegheny to provide costal corrosion data based on the LaQue/Kure Beach exposure.

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Rust never sleeps
Neither should your protection

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