How To Knowl If Metal Is Stainless

[old mart]

Copper sulphate solution will leave a copper deposit on iron and steel, but probably not on stainless steel.

[Bob La Londe]

Most stainless I have tried is atleast very lightly magnetic. I use rare earth (neodymium magnets) pressed into mold plates to hold various wire inserts in place for castings. A cheap magnet may have no noticeable magnetic affect, but a good quality neodymium will have enough pull to hold a thin wire in a half wire thickness slot until the mold is closed. There may be some stainless that is zero magnetic, but I have not run across it.

X-ray guns will give you most of the composition of the alloy, but its my understanding that they do not give you any idea of the carbon content.

[mattthemuppet]

you can also do a spark test on a bench grinder. Sometimes that can get you in the right ball park.

[Yondering]

I will go ahead and degrease one,sand it, wet it and check it in a few days. Thanks
Dwight

Testing with cold blue as mentioned above is a much faster and more reliable test. Looking for a little bit of surface rust on a wetted part doesn't tell you for sure, some "stainless" gun barrels rust more than you'd expect. With cold blue, you'll know for sure in less than a minute. If you work on guns, you should have some anyway.

[wombat2go]

I think a magnetic test would be unlikely to show the difference.
A rifle barrel would most likely be of a martensitic stainless steel which has been hardened and back tempered.
The crystal structure of martensite is ferro-magnetic.

An austenitic stainless has a crystal structure which is non ferro-magnetic.
Austenitic stainless is tough, and softer with lower fatigue endurance compared to low-alloy carbon steels.

A complication is that austenitic stainless can become slightly magnetic with work hardening,
for example I have seen roll-formed threaded fasteners of austenitic stainless which attacted a magnet ( weakly).