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pitting in aluminum weld

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  • pitting in aluminum weld

    Hello, I have been having a few issues with aluminum lately, the worst being pitting in the weld, that has been driving me nuts. All of these issues only happen with a newer welder that I bought. THe welder in question is a 250 Snycrowave (sn# lg480049l). T weld looks ok on the outside, a little grainy and dull, but the bead is filled will gas pockets that only come out when ground down. Material is 6061 or cast mold plate, I am using both 4043 and 5056 and have the same issues. thicknesses vary from 1/4 to up to 4" thick. some times I pre heat sometimes not. I have tried pure, thoriated and ceriated and have the same issues. I like to weld hot, but very my amps as needed with the pedal. Filler and base materials cleaned with acetone and SS brush or scotch brite pad. Attached is a picture of the pitting.

    I will try to make a sample tomorrow with more accurate info for amperage, material, cleaning, rod, ect with a before and after grinding.

  • #2
    here is a mold plate that got filled, and then scrapped because of all the pitting issues.
    Attached Files

    Comment


    • #3
      Is the new welder near a door or window??

      could you be getting a breeze blowing off some of your argon coverage??

      How many CFH Argon are you running??

      Comment


      • #4
        Possibly contaminated gas? Try changing out the gas cylinder and see if the problem goes away.

        Comment


        • #5
          THe welder, is not in a area where there is air flow, I have no issues with contamination welding steel/stainless. I have tried multiple CFH for 12 to 20. I suppose it could be a gas issue, but I have never been able to make this machine weld like my older 250 snyc. I have never had pitting, but the weld has been grainy and dull, no matter what I do with ac balance and filler.

          Comment


          • #6
            Originally posted by Whetstone View Post
            THe welder, is not in a area where there is air flow, I have no issues with contamination welding steel/stainless. I have tried multiple CFH for 12 to 20. I suppose it could be a gas issue, but I have never been able to make this machine weld like my older 250 snyc. I have never had pitting, but the weld has been grainy and dull, no matter what I do with ac balance and filler.
            Porosity in aluminum is caused by one thing and one thing only: Hydrogen.

            There are many causes for the trapped hydrogen but the machine is not one of them. Neither is the type of tungsten used.

            Griff

            Comment


            • #7
              Where would hydrogen be coming from? Not enough pre-heat?

              Comment


              • #8
                I've had contaminated gas weld fine on steel, stainless ect but on aluminum it really gets nasty. Just change the bottle out and try another test piece.

                Comment


                • #9
                  I just did a little bit of goggleing, and it says that hydrogen comes from water vapor or grease. In the case of the mold plate it was definitely hot, especially by the time I got through half of it. I cleaned both the mold and rod with SS brush/scotch brite and acetone. The only place grease could be coming from is my gloves, which some times handle dirty steel. Generally I like to have two pairs of gloves, but am running on one pair now.

                  While I am not blaming these issues on the welder I have never been able to make it produce satisfactory aluminum welds.

                  attached are some recent welds that are also grainy and dull, but dont have the porosity issues (material is 1/4 x 2 6061)
                  Attached Files

                  Comment


                  • #10
                    Originally posted by Whetstone View Post
                    Where would hydrogen be coming from? Not enough pre-heat?
                    Here is a MILLER video on the subject of "Aluminum Porosity"

                    it's Causes and how to avoid/minimize it...

                    http://www.youtube.com/watch?v=Yu3BtdERmFM

                    By Tony Anderson, Head of Aluminum Technology Miller/ITW
                    Last edited by H80N; 09-17-2013, 05:51 AM.

                    Comment


                    • #11
                      pitting in aluminum weld

                      Awesome vid!!!!thx

                      Comment


                      • #12
                        Originally posted by jrscgsr View Post
                        I've had contaminated gas weld fine on steel, stainless ect but on aluminum it really gets nasty. Just change the bottle out and try another test piece.
                        Same here.

                        Griff

                        Comment


                        • #13
                          Originally posted by Whetstone View Post
                          I just did a little bit of goggleing, and it says that hydrogen comes from water vapor or grease. In the case of the mold plate it was definitely hot, especially by the time I got through half of it. I cleaned both the mold and rod with SS brush/scotch brite and acetone. The only place grease could be coming from is my gloves, which some times handle dirty steel. Generally I like to have two pairs of gloves, but am running on one pair now.

                          While I am not blaming these issues on the welder I have never been able to make it produce satisfactory aluminum welds.

                          attached are some recent welds that are also grainy and dull, but dont have the porosity issues (material is 1/4 x 2 6061)
                          The pic you posted shows contamination in the bead. That is the "pepper" looking specs and the black soot at the start of the bead.

                          Hydrogen can come from" just about" anything that isn't aluminum, argon or helium. Not just grease or water vapor.

                          Griff

                          ps
                          Let us know how much argon is left in the bottle in use
                          Last edited by griff01; 09-16-2013, 07:03 PM. Reason: ps

                          Comment


                          • #14
                            Okay, So it sounds like your blaming the welder.

                            The way your post reads is that you have welded these before without a problem and the only difference was the welder.

                            Tig welding 4" thick aluminum should be difficult with a 250 amp welder, what does it measure the other way.
                            If you preheat to 400 F. then Okay.

                            You also mentioned that you were grinding on it which can cause contamination from the grinding wheel ( I'm not sure if they call broken off pieces of grinding wheel, HYDROGEN )

                            Is there something that may have soaked into this particular casting like oil.

                            What are they used for.

                            Is your argon turned up to high.

                            Is your cup the same size as the last one.

                            Is your cup dirty.

                            These are some possibilities.

                            Comment


                            • #15
                              porosity in cast mold plate?

                              Originally posted by Whetstone View Post
                              Hello, I have been having a few issues with aluminum lately, the worst being pitting in the weld, that has been driving me nuts. All of these issues only happen with a newer welder that I bought. THe welder in question is a 250 Snycrowave (sn# lg480049l). T weld looks ok on the outside, a little grainy and dull, but the bead is filled will gas pockets that only come out when ground down. ........
                              1-If you're watching the puddle in action--normally one can see porosity forming, bubbling, coming up thru and around the puddle.

                              2-The cast mold plate pic you posted looks like classic--just below the parent mold surface--fine, casting porosity--inherent to the casting.
                              In 'normal' AL castings--porosity is ever present. (High end, investment castings have limited to zip porosity.) Trying to boil out and fill myriad, scattered casting subsurface porosity is an exercise in futility.....if the goal is zero porosity after machining.

                              3-If you're getting porosity on wrought AL, then it's time to consider the usual suspects.

                              4-Grabbing whatever type of filler rod to weld whatever type of AL
                              can create other problems you don't need. Suggest studying what Alcotech recommends--despite the recco's of board pundits.

                              5-Ditto the previous comments on preheating.

                              Comment

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