Metals question - yeah, it's a dumb one....

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Jan 15, 2003
I have a length of 1/4 x 6 inch plate that I can't remember where it came from.

It kinda looks like stainless, kinda shiny and all. But, I would have never knowingly bought stainless.

So, my question is how can I tell if it's stainless steel or regular steel?

It is magnetic, but my web searching has revealed that the magnet test isn't definitive.

Any help?

A little salt water might tell you.

Wipe it down good with laquer thinner or MEK, then throw it outside for a while. Let mother nature tell you, unless you live in a desert.:hillbilly:
Rust is probably the only way...

Since it's relatively dry here in Gilroy, I'll have to use an accelerant. Thanks for the salt-water suggestion.

Hey Phil,
you can spark test it. If its stainless it will have long bright yellow streaks and almost no leaves at the end. If it's mild steel you should see some sparking and more erratic streak length.

Spark test... How would you do that?

Grind on the metal with a bench grinder or side grinder and watch the sparks.
Different metals give off different "signature" patterns of spark patterns and colors.
Is the end painted?

The place I buy my metal from paints the ends of each type of steel.

Blue is one type
Green is another type
Black is another type
White is another

I don't know if it is industry standard or just something they do.
Question, why do you care?

Question, why do you care?


Fair question :D

I want to use it for a t-case mounting plate and frame mounting plates for my cross-member/skidplate. Other parts will definitely be regular steel so I was somewhat concerned about welding two different types of steel together. If it is SS.

If I can weld the two with standard gas shielded MIG wire, then the whole question is indeed moot.

Using the grinder did not even occur to me... :doh:

who cares x2 .... justweldit .... you can weld stainlless with a mig ! the weld wire will rust.. thats it ... sounds like you got a piece of 1018 tool steel ?
who cares x2 .... justweldit .... you can weld stainlless with a mig ! the weld wire will rust.. thats it ... sounds like you got a piece of 1018 tool steel ?

:cool: I will justweldit :D

Could be tool steel I suppose. It has no markings or painted end. Is definitely different than the other plate I typically use. But it just isn't quite like the other pieces of SS I've seen.

I'll post up some results after I play with it this weekend.

yep, stainless glues to mild just fine.
its what i make stuff out a :hillbilly:

I have a 260-300lb chunk of 440 Stainless that has been machined to look like an drive axle.

Do a springover on it :D
It could be a magnetic stainless. What color is the bar? Is it light grey or dark? Does it have really sharp corners? I have my own steel distribution business, and a picture of it would help also. Let me know.
Summit Steel
Oceanside, CA
In the refineries we use a simple copper-sulfate solution to verify removal of stainless steel overlay from Carbon steel base metal. Apply the copper-sulfate and if the metal turns copper/brown it will be carbon steel. If no reaction occurs then you have something else. Here are a few links for your reading pleasure.
Google it and you shouldnt have a problem finding a source for copper-sulfate. As others already stated if it shows some rusting after leaving water on it overnight you most likely have carbon steel. 309 SS filler metals are usually used to weld carbon-stainless base metals
Article: On-site methods for stainless steel grade product sorting

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