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From AZo Journal of Materials Online
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www.azom.com]
Austenitic Grades
All austenitic grades have very low magnetic permeabilities and hence show almost no response to a magnet when in the annealed condition; the situation is, however, far less clear when these steels have been cold worked by wire drawing, rolling or even centreless grinding, shot blasting or heavy polishing. After substantial cold working Grade 304 may exhibit quite strong response to a magnet, whereas Grades 310 and 316 will in most instances still be almost totally non-responsive.
The change in magnetic response is due to atomic lattice straining and formation of martensite. In general, the higher the nickel to chromium ratio the more stable is the austenitic structure and the less magnetic response that will be induced by cold work. Magnetic response can therefore be used as a method for sorting grades of stainless steel, but considerable caution needs to be exercised.
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From the Stainless Steel Information Center Website
[
www.ssina.com]
4. What is the difference between 304 and 316 stainless steel?
Answer: 304 contains 18% chromium and 8% nickel. 316 contains 16% chromium, 10% nickel and 2% molybdenum. The "moly" is added to help resist corrosion to chlorides (like sea water and de-icing salts) See "Stainless Steel for Coastal and Salt Corrosion Applications" for more information.
5. Is stainless steel magnetic?
Answer: There are several "types" of stainless steel. The 300 series (which contains nickel) is NOT magnetic. The 400 series (which just contains chromium and no nickel) ARE magnetic.
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Festus
Edited 1 time(s). Last edit at 11/13/2008 10:40AM by Festus.
