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  • cracks, cracks, and more cracks

    when you come across a crack in a best case scenario you drill a hole at each end grind it out and weld it up...at least i do. my question is this, what about those cracks you cant access? I do my best to clean them up and grind them out then weld 1 or in most cases multiple passes well past both ends of the crack. Ive had good success with this until recently. I encountered a 10 inch crack on a 3/8 plate. i ground it out and welded 3 passes horizontally with 1/8 6011 at around 100 amps on my trailblazer. I also welded 1 pass on the back side of the plate. crack fixed i thought...wrong. on the front side, 3 pass side, there was a 1 inch crack in my weld. i ground it out and it only appeared to be superficial...but what am i missing? I did weld back side while still hot if i remember right.

    How are you fixing cracks?
    and
    What did i do wrong and how can I fix it?!

    thanks folks

  • #2
    Crack...

    Whatis the application, IE what is cracking.. Need to know to what the item is.
    Kevin
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    • #3
      a frame rail on a trialer...near an axle mount

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      • #4
        6011 is particularly known to not be very ductile.
        7018 would be the rod of choice to fix something that has a crack in it. But that if and only if it should be fixed in the first place. as in should the part be replaced due to fatigue??

        And reading your last post I'd say definitely 7018.
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        • #5
          Your process is good, drill both ends, grind into a V, fill one side, run one on the back, grind both sides flat, that works good for me. 6010/6011 for the first pass and 7018 for the rest should have been fine and not cracked.
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          • #6
            Replace It !

            Hi; Can you cut out the Bad piece and replace it?
            That would be my suggestion, If steel is doing what you say, REPLACE !! .......... Norm
            Also as stated above,,,,,,,,,, E-7018 for sure !!
            www.normsmobilewelding.blogspot.com

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            • #7
              Originally posted by seven 13 View Post
              a frame rail on a trialer...near an axle mount
              I wonder if it wouldn’t be prudent to add some gussets?

              Caution!
              These are "my" views based only on “my” experiences in “my” little bitty world.

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              • #8
                some times a weldment is not enginered correctly, you can weld it and weld it and it still breaks, or the weldment is used far passed its capacity, i would first grind it clean, then grind a v, leave a small gap if possible, tack it together with 7018, weld the back side, then i would grind out the tacks and v until i got 100% penetration, before i weld it out with 7018, i would weld some removeable braces on the repair to keep distorsion to a min. if needed/possible, fill with 7018, then proably some gussets, cuz all i did was bring it back to its (nearly) original condidtion before cracking. pics would help alot, good luck, kevin

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                • #9
                  just thought of something else

                  ive done repairs on things that have been repaired before, some guys just turn up the heat and weld the crack, ive seen heafty welds with cracks and someone just welded the crack with out any prep, that absolutely positively does not work, thats your basic welding 101 tip, but it is still done

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                  • #10
                    Why Did It Crack?

                    The first thing you should do is figure out why it cracked. I will not fix something that is broken till I know why it broke and how I can make it better, Because the next time it cracks they will blame you and your weld.
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                    • #11
                      Remember in welding school textbooks, the drawing of the spoked steel wheel with a broken spoke, and they showed you the places to heat the wheel before you welded the break? I always try to envision how to reduce stresses that might accumulate in a repaired crack or break, pre-heat where it seems useful, stop-drill as you do, and maybe make short, sequenced welds. Other parts of the world call this "practical engineering," though at least in my case it probably involves some dumb luck as well.

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                      • #12
                        Stress...

                        Trailers, frames normally crack due to the stress or vibration of road travel. First be sure the axles are sprung correctly, that the spring move in the hangers (if they are froozen it will keep cracking). Shocks are installed.... I normally v the cracks out and fish plate the crack. Normally the metal is so fatigued that welding the crack only pushes the crack to the side of the weld.
                        Kevin
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                        • #13
                          Originally posted by kcstott View Post
                          6011 is particularly known to not be very ductile.
                          .

                          Lincolns 6011 has as good or just a bit better elongation percentages than their 7018's. So I have to ask, "known" by who?

                          JTMcC.
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                          • #14
                            Performance of some name brands notwithstanding...

                            Typical values of elongation are in the 30% ballpark for most 7018 and 6010/11 rods, so neither one really pulls ahead on that measure of ductility.

                            However, Charpy V-notch values in the mid 30's (ft-lb) are common for 6010/11 while CVN's in the mid 60's are common for 7018.

                            7018's win big in that measure. Not by a few percent, but by almost double.

                            So it would probably be more precise to say that the 6010/11 weld deposit will be more brittle than the 7018 weld deposit.

                            Is ductile the opposite of brittle? It depends on which metric you are using and the context in which you are using it.

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                            • #15
                              Originally posted by Bodybagger View Post
                              Performance of some name brands notwithstanding...

                              Typical values of elongation are in the 30% ballpark for most 7018 and 6010/11 rods, so neither one really pulls ahead on that measure of ductility.

                              However, Charpy V-notch values in the mid 30's (ft-lb) are common for 6010/11 while CVN's in the mid 60's are common for 7018.

                              7018's win big in that measure. Not by a few percent, but by almost double.

                              So it would probably be more precise to say that the 6010/11 weld deposit will be more brittle than the 7018 weld deposit.

                              Is ductile the opposite of brittle? It depends on which metric you are using and the context in which you are using it.
                              Bodybagger;
                              Hi; Probably Not related to the OP's question, but how does
                              SS. - 308L compare to the above Equation on ductility & CVN's ?

                              ........... Norm
                              www.normsmobilewelding.blogspot.com

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