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!

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.

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.

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.