Metal finishing Q&As since 1989

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Stainless steel questions for school research

2003

I am a school student from Wallingford School in south east England and I need some information on metals for my school project. Can you please answer these questions. What's the difference between 301 stainless steel and 440 stainless steel? Does the higher the number mean that the quality increases or vice versa? what are these metals used for? which one is more durable? if you can't answer my questions can you please give me a link to a website where I my questions can be answer or where I can find metal information.

Thank you in advance,

Greg B.
- Wallingford, England

The issue of corrosion resistance and other engineering properties is much too complicated to allow for any kind of simple numbering system where the "quality increases or vice versa" with higher alloy numbers.

Your library will most likely have something similar to the ASM Metals Handbook, which will list all of the ingredients and many of the properties for the various stainless steels.

Asking for "the difference" between these two stainless steels is a bit like asking the difference between a northern pike and a sea robin. There is the somewhat obvious answer that 301 is a nickel-bearing stainless while 440 is a nickel-free stainless, just as a pike is a freshwater fish while a sea robin is a saltwater fish, but the answer can be as misleading as it is informative. As a very general rule, 3xx stainless is used for chemical resistance and 4xx is used for things like stainless steel tableware.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

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Greg, "difference" is difficult, because I don't know whether you want to know the difference in composition (301 has about 8% nickel, low carbon, while 440 (A? B? or C?) has no added nickel, and .3 to 1 % carbon) or something else. 301 is austenitic, until it is cold worked, then becomes martensitic like a heat treated 440.

Rather than have me type a long exposition, let me send you to one of the better guides to stainless steel that I've found on the internet, courtesy of an australian steel distributor, of all things. Go to http://www.atlas-steels.com.au/techinfo/index.html for Atlas Steel Australia's useful technical information pages.

Good luck in your studies!

Lee Gearhart
metallurgist - E. Aurora, New York
2003