Anyone know how to tell if a screw/bolt/nut is stainless steel?

Discussion in 'Off Topic' started by zixxer, Apr 6, 2007.

  1. zixxer

    zixxer Diamond Member

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    curious if anyone knows how to tell if a part is stainless
     
  2. FoBoT

    FoBoT Super Moderator
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    put a magnet on it . most stainless isn't magnetic
     
  3. wedi42

    wedi42 Platinum Member

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    one tip: stainless isn't magnetic
     
  4. brandonbull

    brandonbull Platinum Member

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    that's not true.

    Types of Stainless Steel

    The three main types of stainless steels are austenitic, ferritic, and martensitic. These three types of steels are identified by their microstructure or predominant crystal phase.

    Austenitic:
    Austenitic steels have austenite as their primary phase (face centered cubic crystal). These are alloys containing chromium and nickel (sometimes manganese and nitrogen), structured around the Type 302 composition of iron, 18% chromium, and 8% nickel. Austenitic steels are not hardenable by heat treatment. The most familiar stainless steel is probably Type 304, sometimes called T304 or simply 304. Type 304 surgical stainless steel is an austenitic steel containing 18-20% chromium and 8-10% nickel.

    Ferritic:
    Ferritic steels have ferrite (body centered cubic crystal) as their main phase. These steels contain iron and chromium, based on the Type 430 composition of 17% chromium. Ferritic steel is less ductile than austenitic steel and is not hardenable by heat treatment.

    Martensitic:
    The characteristic orthorhombic martensite microstructure was first observed by German microscopist Adolf Martens around 1890. Martensitic steels are low carbon steels built around the Type 410 composition of iron, 12% chromium, and 0.12% carbon. They may be tempered and hardened. Martensite gives steel great hardness, but it also reduces its toughness and makes it brittle, so few steels are fully hardened.
     
  5. irishScott

    irishScott Lifer

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    Take a steel screw/bolt of identical proportions. Stick each in water and expose to air. See which one rusts first :D
     
  6. bwnv

    bwnv Senior member

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    As a general rule the types that are magnetic are mostly used for cutlery and knives. Nuts and bolts are made of the non-magnetic alloys.
     
  7. MikeyIs4Dcats

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    for the most part if it is stainless it will be stamped as such. If it is not, it likely isn't.
     
  8. radioouman

    radioouman Diamond Member

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    If the screw/bolt/nut is brand new, it will typically have a darker appearance (slightly) than a zinc coated screw/bolt/nut. Galvanized will have a very dull finish.
     
  9. Mxylplyx

    Mxylplyx Diamond Member

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    Pour water on it and wait a few weeks.
     
  10. Azndude51

    Azndude51 Platinum Member

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    UUGGHHH, I just took an exam on this stuff for my materials engineering class, but I got raped on it.
     
  11. 91TTZ

    91TTZ Lifer

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    Just look at it. It's easy to tell.


     
  12. Apex

    Apex Diamond Member

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    However, with respect to the stainless most commonly used in screws, bolts, and nuts, it is true.
     
  13. DrPizza

    DrPizza Administrator Elite Member Goat Whisperer
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    dip it in grapejuice and see if it stains. :p