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Cast Iron/Steel Welding (repairing a crack)

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  • Cast Iron/Steel Welding (repairing a crack)

    I need some help with repairing a crack on one of our tractors. The location is on the steering gear box, its Holder A55 an articulated steered tractor (meaning the front half of the tractor turns. The tractor is German Made and from the Mid 70's I would assume it cast iron. I attached a photo of the location, its on one of the stiffening ribs. Its been like like this for quite sometime, maybe 20years or so, and finally my uncle wants to do something about it. We don;t believe its under pressue, its just houses the gears for the steering, kinda like a differential or transmission.

    I figure we will have to tear it all down and remove the housing off the tractor. What would you recommend for welding, stick or tig? And what type of rod/filler? The crack wraps around the rib, and is about 1-1/4 to 1-1/2" long.
    Attached Files

  • #2
    Crown alloys 255 would be my choice if its cast iron with a stick welder...Bob
    Bob Wright

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    • #3
      ENiFe-Cl

      If Crown's 255 is unavailable in your area, Lincoln's Softweld 55 or Harris Welco 65 are popular alternatives.
      "Bonne journe'e mes amis"

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      • #4
        Ni-Rod 55 would be our choice.
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        • #5
          Thanks guys, I will have to make a call tomorrow and see whats available, are these all stick rods? And can any of these be welded "cold" where I do not have to preheat? Or is it still better to preheat? What size rod and amperage would you recommend?

          Lastly, if they are not available what about a filler for tig?

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          • #6
            Ni- rod 55 is a stick rod. If ground out properly Very little preheat is necessaty. Keep the welds short & above all don't let it cool too quickly.
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            • #7
              The Crown 255 is little preheat also. I just take the chill off then start welding...Bob
              Bob Wright

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              • #8
                I 100% guarantee you that will crack once welded. Your going to super heat the area that is welded which will make it expand but the surrounding material won't let the metal expand so it than thickens slightly instead and than cools down it will shrink and you will get a crack beside the welded area. You can weld cast iron if it is the end or edge of a peice but in the middle of a piece it will crack. To repair it you should use a drilled and tapped pinning system for repairing the crack.
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                • #9
                  Originally posted by jrscgsr View Post
                  I 100% guarantee you that will crack once welded.
                  We all might as well sell our welders now ...Bob
                  Bob Wright

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                  • #10
                    Cast Iron Repairs

                    Originally posted by jrscgsr View Post
                    I 100% guarantee you that will crack once welded. Your going to super heat the area that is welded which will make it expand but the surrounding material won't let the metal expand so it than thickens slightly instead and than cools down it will shrink and you will get a crack beside the welded area. You can weld cast iron if it is the end or edge of a peice but in the middle of a piece it will crack. To repair it you should use a drilled and tapped pinning system for repairing the crack.
                    Drilling and pinning is not always possible, due to the location and nature of the cracks. Proper pre-heat (500-1200F), slow cooling, low currents and short welds are the key.

                    Many have made welding of cast iron to sound "mysterious." Once the material properties are understood and how castings are made, successful repairs can be made.

                    Gray cast iron (most common) has a high carbon content of 2%-4%. When the castings are formed, they are allowed to cool SLOWLY. As it cools, the carbon becomes a flaky form of graphite, giving the "gray" color and some of it's properties.

                    When it is welded, part of the "gray iron" is melted and an area adjacent to the weld area is rasied above "critical" temperature (1450F).

                    Now, here's the "secret:" If, the cooling of the heat-affected zone and the weld is faster than when the original was made, then highly brittle, crack-sensitive area(s) form.

                    Proper pre-heating slows the absorption rate during the welding process, subsequently preventing rapid cooling of the same area(s).

                    Here's some rod sizes and current settings:

                    NiFe-Cl (Softweld 55)

                    3/32" 40-65 DC 50-65 AC

                    1/8" 70-95 DC 80-95 AC

                    5/32" 100-135 DC 110-135 AC

                    These 55 Ni rods are very common, usually sold by the pound,($25-$30)

                    Good luck and keep us posted

                    Dave
                    "Bonne journe'e mes amis"

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                    • #11
                      Originally posted by jrscgsr View Post
                      I 100% guarantee you that will crack once welded. Your going to super heat the area that is welded which will make it expand but the surrounding material won't let the metal expand so it than thickens slightly instead and than cools down it will shrink and you will get a crack beside the welded area. You can weld cast iron if it is the end or edge of a peice but in the middle of a piece it will crack. To repair it you should use a drilled and tapped pinning system for repairing the crack.
                      Wow! I didn't know that!

                      I guess all the exhaust manifolds that were cracked in the middle, which I welded up, need to be removed and thrown away.

                      Griff

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                      • #12
                        Leave it alone! if it has been cracked for 20 years it is fine. You are likely going to do more damage to the part, which is obviously stable and not leaking than leaving it in service. At most would braze over if it was leaking fluid. If you insist on tearing it out and stipping the gears out of it, then one of the nickle 55 rods would be fine.

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                        • #13
                          If you do end up welding it then pay attention to what folks are saying about 'cooling slowly' , I would stuff some fiberglass insulation in side of it and then roll it up in some more and then let it cool on its own, it will be fine.
                          I have found post heat or retarded cooling to be more effective in preventing cracks, but a little preheat never hurt, when you weld with a stick welder just make short arc contacts 1-3 seconds, don't try to be a hero and weld the whole thing at once. I have used ni-rod with much success but I'm sure the others that were mentioned are equally as good.
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                          • #14
                            Cast iron/steel weld repairing crack

                            I have used ni rod 55 for my repairs very succesfully,follow directions for preheat and cooldown very very slowly. Hopefiully the part is off the tractor and will be welded in the flat position.Personally I would cut open the crack with a carbide burr and braze the piece (off the tractor).I don't like the looks of the high stress area (gusset near crack).Also I see some suspicious casting defects ,three pin holes in paint surface upper left.Don't forget to drill a very small hole at end of crack to halt further cracking.Welding is fun. MrH

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                            • #15
                              MrH, Those pins holes are actually on a steel angle bracket were the controls for the hydraulics mount, then bolted to the steering shaft, nothing to do with the steering box. I will have to get some pics of the whole setup next time I am there to give you a better idea of what I am dealing with.

                              If any wants to look up Holder A55 tractors, the part is located below the steering wheel, it appears to be just a gear box housing, little to no pressure inside, but when running full lock, or if the fluid level is up it leaks like crazy, need to add oil every so often.

                              If we were to braze what would is recommended?

                              I am trying to find a replacement piece just in case something happens, or better yet install it and keep the cracked one as a spare.... But so far no luck on the part...

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