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Annealing hard spots??

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  • Annealing hard spots??

    Is there a simple way for me to soften the hard area where my weld is, to make filing and finishing afterward a little easier.

    I'm welding 1018 steel with an oxy/acetelene set-up.

    Anything easy like say, after it cools, heat with MAPP gas for a bit and let it cool back down by itself??

    Thank you,


  • #2
    If it's practical you could heat the whole part bright red and then pack it in ashes or some other type of insulater to let it cool slowly in order to aneal it.



    • #3
      Your idea of localized heating ought to work, I think; "dull red" ought to be sufficient. Dave's onto a key point, too, letting it cool s l o w l y. Since you don't have an exotic alloy here it's probably not too critical, but if you can slow down the cooling rate it may help the cause.
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      • #4

        In case you aren't aware, the heating and cooling cycle with cause that area to shrink.


        • #5
          With mild steel you should not have a hard weld. The problem comes from steel being produced mostly from scrap these days so that most hot rolled "mild" steel actually has significant chrome, nickel and other elements in it which cause it to be hardenable. Really clean "mild" steel or "low carbon" steel has to be specially ordered. If the weld is really hard to the point that it can't be filed I would suspect that you accidently got hold of some high carbon steel or other alloy. If it is just "harder" then local heating to a red heat and just still air cooling will soften it. Heating the whole part is a nice thing to do but may be a lot of trouble if the part is large. The very slow cooling by covering the part with insulation is usually only used on cast iron or other very sensitive materials. Lime is the traditional insulating material. You can buy lime at masonry supply stores. A "lime box" is a standard item at places that do a lot of repair welding on cast iron.


          • #6
            Working where they make (oops.. made) the 90% of rotors for cars. (Wheyland foundry chattanooga Tn).. well I had to duck and run under the line while it was running. I understand why my rotors shake the steering wheel.. During shake out, they leave sand on places on the rotor, it cools unevenly, cleaned, sent off to manufacturer to shave and box. NO heat treatment. Hard spots are common..

            YEP, heat treating the next ones Like Dave said.. in my furnace till red, then in ash till cool.

            shake shake at 120 plus is not a good thing. I don't drive that fast these days in my hotrods, but I used to.

            [This message has been edited by ibewgypsie (edited 06-12-2003).]


            • #7
              Are you quenching your work after you weld? Usually what I do if I don't want a hard weld is to let the piece cool slowly in a bucket of vermiculite, however this wouldn't work on large pieces, and is also no good if you are short on time. Other than that you can just anneal the whole thing afterwords like others have said.
              Have you thought about buying an angle grinder? That would save you a lot of time and you wouldn't have to worry about a hard weld.


              • #8
                Thanks all...I will use your suggestions to find what works best for me....they're all very helpful.

                I don't quench afterward and the pieces are not very big, (tattoo machine frames) so I think I can use the ashes, or vermiculite....not sand huh?

                I have an angle grinder, and I DO use a bench grinder to bring it down a bit, but I do a lot of finish shaping and smoothing, and you can feel the file just glide over the weld area before it bites into the softer part.

                Again, thank you all,




                • #9
                  What kind of filler rod are you using. If you use a alloy filler rod you can get hard spots. Make sure that the filler rod is low carbon.