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Q&As since 1989


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Steel vs. stainless steel

I am a sixth grade student doing a science report on metals. Can you please tell me the differences between steel and stainless steel? Do they both rust?

Lisa H.
student - West Palm Beach, Florida, USA
2003

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2003

Steel is basically a purified version of iron with a small and controlled amount of carbon in it. Stainless steel is a generic name for a lot of somewhat different metal alloys, but it usually contains a lot of steel plus substantial amounts of nickel and chromium.

All metals--except precious metals like gold--tarnish, oxidize, or rust. The thing is, when steel oxidizes it forms an obvious and unattractive rust. Further, the rust is not tenacious and self-sealing, it just brushes off, exposing more steel, which also rusts. When stainless steel oxidizes/tarnishes, the corrosion products form a pretty tight cap which does not brush off but stays adherent and prevents continuing corrosion of the stainless steel below. In most cases the oxidation products of stainless steel are not rust colored but more of a clear (because the layer is so thin) to whitish color.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey