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Hardening / Tempering steel

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  • Hardening / Tempering steel

    I have a chunk of 1/2 inch steel that i am using to build a press brake. I ground the edge to a point along the length. I want to harden and temper this pointed edge. can anyone recommend a good procedure that i could do to get a good strong hard edge on the steel? (This photo was taken before i ground the edge.)

    I don't know the grade. it is a piece of rail road scrap i found near the tracks.






  • #2
    You really need to know what sort of steel it is.
    Some steels won't harden at all.

    I don't know how to tell the type or even if it's possible to be certain.
    Mike

    My Dad always said, "If you want people to do things for you on the farm, you have to buy a machine they can sit on that does most of the work."

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    • #3
      [quote=MotorradMike]You really need to know what sort of steel it is.
      Some steels won't harden at all.

      You can heat up a small piece to cherry red and dunk it in oil till it cools, then test it with a file. That will tell you if it's a steel that can be hardened.

      JL.....................

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      • #4
        just a thought

        Wondering if case hardening would be suitable?

        Would it be possible to arc weld the surface with hard-surfacing rod as used on construction earth-moving equipment then re-grind to contour. Never done it, don't know if practical, just a thought.

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        • #5
          Hard surfacing rod may be the best answer. Case hardening is only good for a small amount of depth,usually a few thousanths unless you can take exceptional measures. With a hunk of steel that big,i'd just use the rod.

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          • #6
            He can use spark testing with a grinder to get an idea of high or low carbon content that would suggest whether it can be directly hardened or not. I'd suspect not but you never know till you try. Carburizing case hardening can provide a depth up to .050 or .060 which might be sufficient for his purposes. Other methods such as nitriding are usually limited to a shallower case but a harder surface.
            .
            "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

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            • #7
              I have made a scraper out of a reciprocating saw and the scraper blade is a piece of oil hardening ground stock. Should I temper to a blue color? or should it be harder than that for a scraper blade?
              "Patriotism is the last refuge of a scoundrel"

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              • #8
                Using stick electrode hard-facing rod is probably your most economical solution. You could case harden it, but that would require a large enough oven at 1650F, lots of carbon (Kasenit), and the ability to quench it in a large tank. Hard-facing rod is easily obtained and not very difficult to apply; ask at your local welding supply.

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                • #9
                  Anyone recognize the part's original function?

                  The wear on the outside corner and the square bolt holes hint at a ground engaging tool/skid plate. If so, the material may be AR class material (aka abrasion resistant) and might be more difficult to heat treat than plain old carbon steel. The piece may be inherently harder and tougher than plain steel and might even work harden.
                  Design to 0.0001", measure to 1/32", cut with an axe, grind to fit

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                  • #10
                    He'll need to regrind the edge if he's hard-faced it with welding rod so that would get him what he needs but there will be some work to do after the welding. If he's considering case hardening at all he ought to go to a commercial heat treater and just have it done there unless he already has a furnace big enough for the part. Kasenit would have the advantage that it could be applied just where he needed the hardness rather than all over, but my sense is that it doesn't give as good penetration as the atmosphere furnace or even pack hardening.
                    .
                    "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

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                    • #11
                      Originally posted by camdigger
                      Anyone recognize the part's original function?

                      The wear on the outside corner and the square bolt holes hint at a ground engaging tool/skid plate. If so, the material may be AR class material (aka abrasion resistant) and might be more difficult to heat treat than plain old carbon steel. The piece may be inherently harder and tougher than plain steel and might even work harden.
                      So might be hard or tough enough for the OP's purposes already? That would be a nice piece of luck.
                      .
                      "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

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                      • #12
                        Might, maybe, perhaps.

                        The AR stuff is difficult to drill and difficult to weld as they need pre-heat and often post-heat as well as ductile welds to prevent cracking. That said, they stand up to the rigors of daily life for a front end loader bucket, etc.
                        Design to 0.0001", measure to 1/32", cut with an axe, grind to fit

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                        • #13
                          I finished putting it together. It bent a an old piece of 5/8" flat like butter and it works fine for what i need, so i guess i wont do anything more to it, but i am curious about how to temper anyway. i will post another thread later on how i made it.







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                          • #14
                            these two wouldnt fit.



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                            • #15
                              Looks good Joe.


                              A couple minor suggestions.. Some light springs that slip over the guide rods placed on the guide rod before the upper die is put on will lift the upper die up after the bend, making repeating bends and work in general just a little easier. Here's mine. I never quite got to welding the guides to the upper die. I just slipped them on the guide rods as spacers so the spring would be long enough.


                              The bottom plate looks a bit light for the job it has. In the picture it looks like the edge of the lower die lines up inside the rail of the press table which would subject it to bending. It won't be an issue for light work, but may be when you are working close to the press's capacity.

                              Yours looks better than mine, it has paint.
                              Last edited by camdigger; 10-19-2010, 12:16 PM.
                              Design to 0.0001", measure to 1/32", cut with an axe, grind to fit

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