I have some hand tools made from stainless steel that adhere to a magnet. How can this be?

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This stainless steel rule, which doesnu2019t require extreme corrosion resistance, is magnetic, while none of the stainless steel hardware shown in the background has that quality.

Q:

I sometimes use stainless steel hardware on projects. When I'm not sure if a nut or bolt is stainless, I touch them to a magnet because I've always been told that stainless steel won't stick to a magnet. However, I have some hand tools made from stainless steel that adhere to a magnet. How can this be?
—Tim Koehler, Dubuque, Iowa

A:

Basic carbon steel consists of iron and carbon, Tim, and the iron atoms line up like tiny magnets, adding to the overall magnetism of the steel. Stainless steel also starts with iron and carbon; however, elements, such as chromium, nickel, and molybdenum, are added for corrosion resistance. These additions change how the iron atoms align and reduce or eliminate their natural magnetism.

Stainless steel comes in various alloys to meet differing requirements for corrosion resistance or ease of welding or forming.While the alloys used for marine-grade nuts and bolts aren't magnetic, the alloys used in stainless knife blades or shop tools might well attract a magnet.