316-316L? 1

[bloch2006]

hi friends:
how can i distinguish between 316 and 316L?

best regards

 

[CoryPad]

By measuring the carbon concentration using a suitable method.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[metengr]

Also, keep in mind that there are dual certifications of 304/304L and 316/316L.

 

[EdStainless]

You can tell if it is 316L by measuring the carbon.
To find out if your 316L also qualifys as 316 you need to know the mechanical properties.

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[stanweld]

There are portable optical emmission spectrographic equipment that can readily determine carbon content of the alloy for you.

 

[AstObs]

stanweld, can it also be done by doing simple metallography (i.e. grinding, polishing, etching, and observing under microscope)?

 

[TVP]

No. Austenite has a considerable solubility for carbon, and therefore the carbon is not present as a second phase such as Fe₃C (cementite).

 

[unclesyd]

I have to disagree with TVP as it was very common practice to separate or verify 304 SS and 304L by optical microscopy for many years.
The procedure is to use a mountable sample of 304 and the piece in question and sensitize for 1 hour at 1000°F, mount together, grind and polish, and lightly etch using electrolytic 10% Oxalic.
You then compare the grain boundaries, the 304 SS will have a continuous interconnected, highway network, and the 304L will have interrupted or discontinuous grain boundaries. The difference is normally quite pronounced.
With practice you can bracket the carbon in 304L SS.

 

[unclesyd]

Forgot to add that there are a couple of other test that use the optical microscope than can be use to assist in identifying 304L or whether other material are sensitized.

 

[EdStainless]

If you can cut a smaple and polish it why not shoot a carbon on your Leco? It is faster and definitive. I have taken a WC tool and cut a sliver of metal off of a piece of equipment for C analysis.

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Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[unclesyd]

Not everyone has a Leco.
Normally you can get to a microscope quicker than you can get a carbon analysis.