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How to weld tool steel

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  • How to weld tool steel

    In addition to having to weld 1" cast iron as I have said in my previous post, I must also weld two 1/4" plates of air-hardening tool steel together. I have no experience welding tool steel, how does one go about it? Can I use any welding process with it? Do I need special filler rod for it? Any help is greatly appreciated.

  • #2
    As I understand it, when you weld high-carbon tool steel, carbon from the parent metal can migrate into the weld puddle. As a result, when the puddle freezes, the weld metal (which is then high-carbon steel) gets super hard, just as if you had heated and quenched it. This can be a problem because internal shrinkage stresses can cause cracking in the hard (and not ductile) weldment.

    Again, as I understand it (which ain't that great) the ways around this are to use preheat and postheat (so the weld doesn't get "quenched" so much, or if it does, it gets "normalized" by the slow cooling) or to use a ductile filler like ER310, or to braze rather than weld the joint.

    I'm sure others understand it better than me and if I'm wrong hopefully somebody will set you straight.

    Comment


    • #3
      Follow-Up

      One more thing -

      Since you're talking about using air-hardening (as opposed to oil-hardening, water-hardening or brine-hardening) steel, you will probably want to let it cool really SLOWLY after you preheat, weld and postheat it, to prevent it from cracking due to excessive hardening.

      One way to do that is to drop it into a big metal bucket of dry wood ashes after you weld and postheat it ... and then let it cool down overnight. The slower and more evenly it cools, the less chance there is of cracking, I think.

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      • #4
        Go buy some Royal 220m electrodes at your LWS and your in the money. My LWS sells it in 1lb tubes for about 30$

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        • #5
          try this link http://www.weldreality.com/toolsteelsS.htm

          Comment


          • #6
            I welded AH tool steel for almost 15 years everyday and this is what i used Crown Alloys AH-20 http://www.crownalloys.com/TechSheet...ew_Warning.pdf . Now if the edges aren't going to be sharpened use the Crown Royal 220M as Rezeppa mentioned. I did a little preheat with the torch until the water comes out then start welding. Peen after every pass...Bob

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            • #7
              Water don't come out of steel. If you heat, depending on environmental conditions at the time --- dew point, etc.,,,, you will see water. It's coming out of the air, not the steel. You ever squeeze a piece of steel, get water squirting out???

              Comment


              • #8
                Originally posted by foreverAstudent View Post
                In addition to having to weld 1" cast iron as I have said in my previous post, I must also weld two 1/4" plates of air-hardening tool steel together. I have no experience welding tool steel, how does one go about it? Can I use any welding process with it? Do I need special filler rod for it? Any help is greatly appreciated.
                I'm sure your teacher/professor covered this topic. Didn't you take notes??? If not, your best bet would be to consult with one of your fellow students,,, one who wasn't sleeping/smoking dope during that particular lecture.

                Comment


                • #9
                  Originally posted by JSFAB View Post
                  Water don't come out of steel. If you heat, depending on environmental conditions at the time --- dew point, etc.,,,, you will see water. It's coming out of the air, not the steel. You ever squeeze a piece of steel, get water squirting out???
                  Yup you are right...Bob

                  Comment


                  • #10
                    You never mentioned if it was in the annealed or hardened state. If the joint area isn't doing any work (trimming, forming), preheat to 500-600*f, weld with 7018, peen often (best with an air hammer) & let cool in still air. Only if it were a really large weldment would I post heat.

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                    • #11
                      I have a few Certanium 718 rods. Had them so long I have forgotten what they were used for . Would they work for this . From what I see on line looks like they might.

                      Comment


                      • #12
                        Originally posted by grumpycricket View Post
                        You never mentioned if it was in the annealed or hardened state. If the joint area isn't doing any work (trimming, forming), preheat to 500-600*f, weld with 7018, peen often (best with an air hammer) & let cool in still air. Only if it were a really large weldment would I post heat.
                        I agree with this. never a problem

                        Comment


                        • #13
                          I weld Tool Steel all the time and find myself using Certanium or Euctectic (Castolin) Tool Steel rods. In most cases when to preheat, post heat, anealing, hardening all depend on how much weld you need to lay down and what the weld will be doing as well as the parent material. Always try to know what tool steel you are welding on. A good book to look into is called "Heat Treatment, Selection, And Application of Tool Steels". by Bill Bryson. It's a Modern Machine Shop Publication. There is an excellent chapter in it (Chapter 17) on Welding Tool Steels towards the back of the book.

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