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Determining Carbon Versus Stainless Steel

Dear Sirs:

I utilize many different materials in my shop and sometimes have a difficult time in determining the material.

If I have a Martensitic Stainless Steel, the material will be magnetic, similar to a carbon steel. I know that I can subject those same materials to moisture to see if one corrodes, but that's relatively destructive for my normal applications.

Are there any non-destructive methods for determining what a material is?

Thanks!

Tom Beyreis
OEM Manufacturer - Wheeling, Illinois, USA
2005

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First of two simultaneous responses -- 2005

Yes there are several methods.

You can get portable X ray flourescence machines at a significant cost which would give you a breakdown of the metallic elements. A cheaper option is to look into electrospot testing. This may leave a very small mark on the surface but is an order of magnitude cheaper.
Koslow Scientific Testing Instruments [a finishing.com supporting advertiser] supply various kits depending on how many elements you want to check for.

Ciaron Murphy
Aerospace - South Wales, UK

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Second of two simultaneous responses --

Dear Mr. Beyreis,

You can cut a sample from the lot and test the material using an optical emission spectrometer. It will provide the complete chemical composition of the material.

T.S.N. Sankara Narayanan
- Chennai, Tamilnadu, India
(ed.note: The good doctor offers a fascinating blog, "Advancement in Science" )
2005

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Tom, if ALL you want to do is distinguish martensitic stainless steels, like 416 and 440C, from carbon or alloy steel, then a simple copper sulphate ⇦ on eBay or Amazon [affil link] test will do. We use about 20% by weight copper sulphate. A quick swab, and the carbon/alloy steels show a dark or coppery color, while the stainless steel is untouched. Keep a known sample handy for comparison, but it's still a striking difference.

Lee Gearhart
metallurgist - E. Aurora, New York
2005

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