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Ways to determine inner hardness of surface induction hardened 4140?

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  • #16
    I have understood that alloys can have pretty unique features in different temps and conditions. There are these age hardened maraging steels and other exotic-ish alloys which heat treatment is dark magic, something like first heated to near MP for a day or two, then slowly cooled to 600, kept there for another day and then re-heated and quenched, or not. And so are their properties.

    Btw, got my real deal 4140QT recently, and machined it. It turned out wonderful, even with my mini lathe and I actually find it more pleasing to work with than normal steel.

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    • #17
      Originally posted by Bented View Post
      Cut a sample then do multiple RH tests ,from the outer surface to the core, this will tell you all that you wish to know.
      Naturally hobbyists will proclaim that most home shops do not have Rockwell Hardness test equipment but you asked the question.

      Any claim by a material manufacturer that you can not measure directly is a 'claim"

      "Any claim by a material manufacturer that you can not measure directly is a 'claim"

      True, but at some point dont you take your manufacturer or supplier at their contract, or word? I mean if you lose trust in everything how do you go forward?


      "]Cut a sample then do multiple RH tests ,from the outer surface to the core, this will tell you all that you wish to know.
      Naturally hobbyists will proclaim that most home shops do not have Rockwell Hardness test equipment but you asked the question."

      Again correct, we dont usually have a way to check the metal. JR

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      • #18
        Originally posted by JRouche View Post


        "Any claim by a material manufacturer that you can not measure directly is a 'claim"

        True, but at some point dont you take your manufacturer or supplier at their contract, or word? I mean if you lose trust in everything how do you go forward?


        Certified material when required, tested by a third party lab, it may be purchased from MCM in small batches.https://www.mcmaster.com/steel-with-...le-lot-number/
        Most any metal supplier will also sell it too you. This comes at additional cost of course.

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        • #19
          Originally posted by Bented View Post
          Cut a sample then do multiple RH tests ,from the outer surface to the core, this will tell you all that you wish to know.

          Naturally hobbyists will proclaim that most home shops do not have Rockwell Hardness test equipment but you asked the question.

          Any claim by a material manufacturer that you can not measure directly is a 'claim"
          Dont ever say Naturally, its a cop out.

          You are discounting the work that people put into that.

          Now then? When you group it like this it bugs me.
          n(

          Naturally hobbyists?? We dont have hardness testers. Maybe we should find some? JR

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          • #20
            In a lab it’s sectioned on a prep cutter ( metallurgical cutting machine) then hardness test centre to skin at whatever increments you fancy, followed by polish and etch, take a peep at Crystal structure skin cut or radial, mount polish and etch also, SEM, scanning probe etc etc
            its worth noting that a round bars chances of being the same chemical analysis from core to skin is about zero, solidification and recrystallisation do funny things defects in billot that crystallise from outside in contain all sorts of defects that can be stretched out for literally kilometres when rolling so the stuff isn’t homogeneous from the outset, you can get some really good stuff or crap in one bar length,
            mark

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