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Steel types and properties
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Thread: Steel types and properties

  1. #1

    Steel types and properties

    Hi

    Im sure there will be a page around somewhere but i cant find a good one. Im looking for a page/article etc that goes over all the different steels and which ones rust, patina etc and which ones dont.

    Obviously stainless should not rust or patina but its not entirely clear which carbon steels will patina, im assuming they all rust.

    Thanks

    Alan

  2. #2
    Senior Member stevenStefano's Avatar
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    Gator has a lot on his website about steel and it is very informative. Here is a link to that part of his site and that should get you started with steel. It is pretty confusing sometimes

  3. #3
    I think his website is down, keeps on crashing my IE

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    I didn't have a problem just now with Gator's site but here's the basics. Everything rusts. Generally more chromium means slower to rust. Stainless generally means greater than 13% chromium. I've seen patina form on every knife that contains up to 12% chromium or so but it depends on the user. I don't get any noticeable patina until I get into the single digits in percentage chromium. These percentages are mass ratios. Keep in mind, the heat treatment and the finish also significantly affect stain resistance.

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    One thing to clarify, as far as my understanding, is that patina is rust. The iron in the steel reacts with oxygen in the environment to form iron oxide. The differance between a patina and brown scaled rust is a matter of degree of oxidation.

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    Senior Member mpukas's Avatar
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    Quote Originally Posted by JMJones View Post
    One thing to clarify, as far as my understanding, is that patina is rust. The iron in the steel reacts with oxygen in the environment to form iron oxide. The differance between a patina and brown scaled rust is a matter of degree of oxidation.
    I thought patina was the metal reacting w/ elements in the items it comes in contact with and is not iron oxide? I also thought a patina can prevent minor rust from forming? Please elighten! Cheers! mpp

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    Patina, if I'm not mistaken, is Fe3O4. DrNaka started a thread on knife passivation and there's a lot there on the various iron oxides

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    There is also iron phosphates and iron sulfates, etc.
    Gun blueing is a patina.
    Spike C
    "The Buddha resides as comfortably in the circuits of a digital computer or the gears of a cycle transmission as he does at the top of a mountain."
    Pirsig

  9. #9
    I wrote a steel FAQ once, but it wasn't particularly well received so it may have been poorly written or short on information. Maybe some of my opinions or how I would have explained things have changed since then as well.

  10. #10
    Patina is not rust at all, patina is a layer of protective oxidation and/or corrosion that forms on the surface of a metal, with the property of being self-limiting. Rust is often self-promoting in steel. Basically by the steel reacting with things and forming compounds that are neither steel nor Iron oxide, the metal is coated in a layer of stuff that's already been reacted with, protecting the bare steel beneath.

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