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  1. #1
    Lumbee's Avatar
    Lumbee is offline Plastic
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    ...hey guys, didn't get much help in class, so thought I would post here. I'm taking machining classes at night at the local tech school, and our stock room as all kinds of unknown crap scattered in it. I'm wondering if there is an easy way to identify mild/machine steel. I was using the magnetic base on my indicator, thinking that if the magnet would stick to it, that that was mild steel. However after doing this test on a piece, then starting to machine it, I found the piece was not mild steel after all. Any info appreciated...

  2. #2
    Old Bill is offline Hot Rolled
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    The best way is to stamp, not magic marker, the metal before it is placed in storage. Making an expensive part from the wrong material is unwise.
    There is always spark testing which is a shot in th dark at best. Old Bill

  3. #3
    acutron is offline Aluminum
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    Your teacher should know the spark test.

  4. #4
    SND
    SND is offline Diamond
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    Stainless is quite easy to identify by the outside finish of it, although it can be harder to tell which grade it is but a few things can get you close. 303 stainless is quite magnetic, so is the 400series. 304 is slightly magnetic but you'd definitely know its not mild steel.

    So if it was magnetic, but wasn't mild steel, what was it? Tool steel? 400series SS? something else?

  5. #5
    L Vanice is online now Diamond
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    I use Precision Brand Tool Black, similar to cold blue for guns, to tell magnetic stainless from non-stainless steel. A magnet will easily tell non-magnetic stainless. The chemical will leave a black stain that will not rub off if the steel is not stainless.

    Larry

  6. #6
    wippin' boy is offline Diamond
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    put a know piece of mild steel on the bench next to a piece of know stainless

    nick 'em both with a grinder
    you'll see the differance

  7. #7
    Lumbee's Avatar
    Lumbee is offline Plastic
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    ...thanx for the info guys, the spark test with a know peice of mild is probably the way to go around class...

  8. #8
    shanman's Avatar
    shanman is offline Aluminum
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    303 stainless is quite magnetic
    Weird.. not any of the 303 we buy. I've seen it SLIGHTLY magnetic before....but I've gotten that out by using a de-magnitizer or drawing it back a little in a heat treat oven.

    Maybe we just get a different composition or something...

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