Stainless steel crystal structure

  1. Hi,
    I'm looking for a simple s.s crystal unit cell structure and can't find it anywhere.
    I understand that stainless steel is a very general word and takes many forms and has many different types, but isn't there a standard type that people use in the industry and ususlay talk about when they use the word "stainless steel" like 316L which I've seen a lot..
     
  2. jcsd
  3. DrClaude

    DrClaude 2,148
    Science Advisor
    Homework Helper

    Hi tau, welcome to PF!

    Stainless steel is an alloy, and therefore does not have a simple crystal structure. Your question is a bit like asking what the chemical structure of a salt water molecule is.

    For further reading, I suggest http://chemistry.about.com/cs/metalsandalloys/a/aa071201a.htm
     
  4. maybe you're the one who should do some reading: :-)
    http://www.holland-hills.com/saltwaterchlorine.html
    anyway, I know that the lattice information of Iron exists for the different forms that iron takes in different types of steel depending on its carbon content. I'm really searching for some kind of coordinates for performing simulations of stainless steel.
     
  5. Astronuc

    Staff: Mentor

    There are different types or grades of stainless steel for which the microstructure depends on the composition, including carbon content.

    The three main groups are austenitic, ferritic and martensitic, and duplex combinations of these, e.g., austenitic-ferritic, ferritic-martensitic.

    Austenitic steels have a predominant fcc structure, or γ-phase.

    Ferritic is bcc (α or δ) structure.

    Martensitics have a distorted tetragonal structure.

    The microstructures depends on temperature at which the heat is quenched and quench rate.

    http://www.keytometals.com/page.aspx?ID=CheckArticle&site=kts&NM=153

    There are also cementite, bainite, and pearlite.
     
    Last edited: Jun 12, 2014
  6. DrClaude

    DrClaude 2,148
    Science Advisor
    Homework Helper

    Sorry, but a cute picture from the site of a vendor of pool equipment doesn't pass muster on PF :smile:

    My point is that there is no "molecule of salt water," there are going to be solvated ions here and there in the solution, but no fundamental unit.

    Again, the problem is that there is no base crystal stucture to s.s. You wont have a uniform crystal structure throughout the metal.

    Here are some technical papers which deal with the subject of calculating the properties of stainless steel:
    http://iopscience.iop.org/0965-0393/17/2/025010/
    http://iopscience.iop.org/0965-0393/19/8/085008/
    http://www.nature.com/nmat/journal/v2/n1/abs/nmat790.html
     
  7. heehee... I was kidding. I'm a master student in chemical engineering :-)
    I will look at what you've posted,
    Astronuc I know that, but the crystal structure that is given is always for the Iron alone and I was wandering can simulations be made for SS.
     
  8. What do you mean by "for iron alone"?
    Stainless steel is an alloy, the iron and chromium form a single crystalline structure (substitutional solid solution). The carbon atoms I believe are in the interstices of the lattice.
    See solid solutions and alloys for more details.
     
  9. SteamKing

    SteamKing 8,620
    Staff Emeritus
    Science Advisor
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    'wander' - walk or move in a leisurely, casual, or aimless way.

    'wonder' - to think or speculate curiously.
     
  10. As stated above Steel is an alloy. C, Cr, Mo, ....etc. can dissolve in iron or form precipitates. If they dissolve they can do this on interstitial or substitutional sites, also they may order or disorder, they may segregate to grain boundaries, dislocations,.....
    Alloy theory is a vast topic. You may need to read more into it. But there is no such simple thing as the crystal structure of stainless steel.
     
  11. DrDu

    DrDu 4,114
    Science Advisor

    As far as I remember, stainless steel contains lots of chromium, so that a thin sheet of chromium oxide forms on it's surface which hinders further corrosion.
    So, it is a surface effect. The crystal structure of the bulk won't differ much from other highly alloyed steels.
     
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