Please help me identify my mystery plate.

Hello Everyone.

I found a mystery metal plate. 5/8 thick 18"x36" with a hole in it. At first I hit it with a magnet and it didn't feel like it was sticking so I thought, awesome big piece of Ali. Nope. Went to pick it up and it was super heavy. It weighs about 120#. I took it back to the garage and tried the magnet again and it barely sticks. It kinda looks like galvinized. It looks like it was cut with a plasma cutter. I scratched it and it's shiny. I can't figure it out.

Thank you in advance for your help.

http://dl.dropbox.com/u/6764649/IMG_0355.JPG

http://dl.dropbox.com/u/6764649/IMG_0354.JPG

stainless steel

So still about the same price as Ali?

Thanks Easy

Yes looks like stainless as it shows some sign of rust. A spark test can confirm this if you want to. Did you weigh it or make an estimate? you are very good if you did estimate it as you are not far off :)

Huh, I've never seen SS that thickness before, just the thin sinks and stuff.

ive seen stainless that thick before.. a guy who always bums a smoke from me at my yard brought several of them in. still dont know where it came from, but it is most likely used in commercial construction. the kind that is meant to be load bearing and stand up to the elements as well.... like an outdoor wall panel from an office building or some other crazy designed building.

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Originally Posted by easyrecycle

stainless steel

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agreed

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Originally Posted by Filthy

...but it is most likely used in commercial construction.......

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Thats what it is. As some of you all know..I worked for power plants, I repaired them and or built them, this is SS and could of been used for many things. At power plants we have used them everything from walls to man hole covers that large trucks and or other heavy items would go across. Or as pipe mounts.

How I know this is stainless steel is by the burn cut on the side of the metal. The way it cut is unlike most metals, it has a very small melt drops unlike steel where you can get large globs of slag. The cut was made very slow due to the fact you cant cut it as fast as steel. The metal cant be "Ti" as Ti would have left "burn colors" on the metal...I see none of this and Ti is lighter than stainless steel

Only likely metal...is stainless steel.

That's a cheap grade of stainless or it would not be trying to rust.

Stainless steel will rust in more extreme conditions even high quality. -When exposed to salt for example, this is why for marine applications Monel alloys are used instead.

Another thing...if the stainless steel sheet had steel or other items that will rust..it will help rust the stainless faster.

Stainless steel pipe has to be held up with stainless steel for that reason or the pipe can rust out.

Also if stainless is attached to non rusting metals, this will make the stainless rust faster as well.

Notice how the rust on it is shaped. It tells us that it came from something on it that wasn't stainless. Also notice the rainbow like colors on the cut edges. That is from a plasma cutter. Stainless colors like that when welded correctly too.

This may throw a spanner in the works, but it may be miltary grade compressed alluminium. Used for tank and APC armour. I have had some of it before. Very high carbon content which measn the moleclare deformation of the surface layers can be prone to rust spotting when weathered for an extended period of time, and can store small magnetic feilds..

:)

Yes but this is very heavy so its no AL.

and that doesnt really look like rust to me.. even though it probably is... it looks more like old weathered packaging tape.

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Originally Posted by Filthy

and that doesnt really look like rust to me.. even though it probably is... it looks more like old weathered packaging tape.

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The rust on the surface was from a piece of iron that was sitting on it. But on the edges where it was plasma cut there is rust. I'm going to hit it with a grinder on Monday and see if it sparks.

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Originally Posted by easyrecycle

Yes but this is very heavy so its no AL.

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Compressed (armour) ally is very heavy too, it has a specific gravity almost equal to mild steel :)

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Originally Posted by Torker Man

Compressed (armour) ally is very heavy too, it has a specific gravity almost equal to mild steel :)

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learn something new everyday...but this is something I would love to see and hold with my own hands/eyes

But from the cut on the side of the metal I can tell you its SS by how the burn cut is.

I agree it is most likely SS, but its always interesting to have some new info to consider, don't you think.

Cheers

Plasma or Oxy cutting burns out a lot of the nickle, ending up with low grade SS beside the cut, so it rusts there.
Commonly used SS is in boats etc.

I hit it with a grinder this morning and it sparked about half as much as grinding iron. Definitely not compressed aluminum. Looks like it's stainless steel. Now lets hope the guy at the yard thinks it's stainless.

That is normally a good sign!

I usually just put a magnet to it, if it does not stick its stainless in my book. This is something I was taught. if it does stick its cheap stainless and I usually just put it with my steel and iron.

SS become more magnetic neat a weld or cut zone.

Agreed, definitely stainless steel.