Best SS for ferric chloride 3

[rysep]

Does anyone know the most resistant stainless steel grade temperatures to ferric chloride ate ambient temeperatures?

 

[hacksaw]

HD polyethylene,tfe or related materials are your best bet

 

[rysep]

Thanks but it must be metal. The material is load bearing and I would really prefer not to use Titanium either.

 

[Metalguy]

What % Fe3Cl? This stuff can crack gold!

 

[rysep]

It will probably vary depending upon our application but most likely less than 1%.

 

[reiser]

I think you're probably going to be looking at nickel alloys. The most commonly available one that might work for your service is C276.

If there is a fair amount of air exposure or other oxidizer, then C-22 will probably work better. I've seen C-22 come out of a 3 day 6% FeCl3 test with mirror finish intact.

If 1% is an occasional maximum, perhaps one of the 6% Mo stainless steels will work (Al6XN, for example). But even 1% FeCl3 has a low enough pH that it will probably challenge this subfamily. I'd really want to see some test exposures before committing to this choice.

Dave

 

[rysep]

Thanks reiser. Test samples will definitely be used before anything is manufactured. FeCl3 is some mean stuff.

 

[mcguire]

You have an application for which there is no shortage of data. ASTM G150 is the test for critical pitting temperature and it uses 10%FeCl3 at increasing temperatures until it reaches a tempature at which pitting occurs. For 316L that temperature ranges from 0C to 20C depending on surface condition, heat chemistry and other variables.
The temperature increases 2C for each 1% chromium and 6.6C for each 1% molybdenum. 0.1% nitrogen gives you 3.2C. Subtract for sulfur and surface abrasion..more complicated. Welding takes 10 to 15C off the rsistance. In effect you can build your own alloy.
Go for a good 10C over the intended use temperature. That says at least 2205, better 2507 or a 6%moly austenitic.

 

[joeswoes]

Yuo need load-bearing, how much ? There are fiberglass composites with higher strength and modulus than ductile iron or stainless steel.

 

[moltenmetal]

If your "structural" application will permit polymer lining, consider it. Ferric chloride is used as an etchant- it's nasty stuff. If not, you're into a high alloy or titanium per the previous poster's recommendations. If it's not a heat transfer surface and the geometry is amenable to lining, there's little sense in choosing a corrosion resistant material if you can choose one which is corrosion-immune.