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Cracks in Aluminum Weld

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  • Cracks in Aluminum Weld

    I've welded up my gas tank, and when I pressurized it up to check for leaks, I split a weld open. I've also noticed that cracks form very easily in other projects with just a bit of applied stress.

    Specs:
    .125" 5052 AL
    4043 filler
    TIG, 100% argon



    Whats going on?

  • #2
    alum. cracks

    hey jpmassy i am not an expert but i would try 6061 with that filler or try
    5051? with 5000series alum. i am sure that someone with more exp. will jump in and we can both learn a new tip! good luck shoprat

    Comment


    • #3
      Lots of good information from alcotec (bought out by esab):

      http://www.alcotec.com/us/en/educati...um-Welding.cfm

      "Alloys possessing from 1% to 2.5% magnesium, such as 3004 and 5052, are very sensitive to cracking when using base alloy filler. Alloys with 3.5% magnesium and more exhibit low sensitivity to weld cracking. The use of a 5% magnesium content filler, such as 5356, to weld 5052 can provide a higher magnesium percentage in the diluted weld metal and reduce sensitivity to weld cracking. The more magnesium an aluminum magnesium alloy contains, the less likely it is to crack; thus, the high magnesium content fillers 5356, 5183, and 5556 are commonly used to weld both wrought and cast aluminum magnesium base alloys."

      Use 5356 next time.

      -dseman

      Comment


      • #4
        I have an overflow tank from canton that cracked just like that

        Comment


        • #5
          Originally posted by jpmassey View Post
          I've welded up my gas tank, and when I pressurized it up to check for leaks, I split a weld open. I've also noticed that cracks form very easily in other projects with just a bit of applied stress.

          Specs:
          .125" 5052 AL
          4043 filler
          TIG, 100% argon



          Whats going on?
          The picture appears to have very little filler and a bunch of contamination.





          Griff

          Comment


          • #6
            I sorta doubt it was just filler that caused your problem. I've welded loads of 5052 with 4043 and not had any problems. It is not your first choice but it does a good enuff job that a crack such as that is not a common occurance.
            I think it is more of a lack of fusion judging from your pic. Looks like maybe moving to slow by the looks and it seems crowned a bit much like filler was added too soon as well. I would strive for more of a keyhole effect myself...That bead will weld with fusion alone. Aluminum will bridge across 2 parts easily without penetrating completely thru unless you make it hot enuff before adding filler and moving forward.
            What does the back side of the weld look like would be the question. I realize it is a tank tho, so you prolly can't see it. I would cut out the weld 100% and crank the heat more and let it get wetter before I moved forward. HTH

            Comment


            • #7
              That may be tearing from the root. Do you have a keyhole in front of your weld puddle while welding?

              Also, are your welds cooling too fast? Have you considered using a little preheat? That sheet of aluminum is an awfully good heat sink for sucking the heat away from the weld rapidly.

              Comment


              • #8
                Originally posted by dseman View Post
                Lots of good information from alcotec (bought out by esab):

                http://www.alcotec.com/us/en/educati...um-Welding.cfm

                "Alloys possessing from 1% to 2.5% magnesium, such as 3004 and 5052, are very sensitive to cracking when using base alloy filler. Alloys with 3.5% magnesium and more exhibit low sensitivity to weld cracking. The use of a 5% magnesium content filler, such as 5356, to weld 5052 can provide a higher magnesium percentage in the diluted weld metal and reduce sensitivity to weld cracking. The more magnesium an aluminum magnesium alloy contains, the less likely it is to crack; thus, the high magnesium content fillers 5356, 5183, and 5556 are commonly used to weld both wrought and cast aluminum magnesium base alloys."

                Use 5356 next time.

                -dseman

                Interesting....thanks for the info.

                Comment


                • #9
                  Originally posted by griff01 View Post
                  The picture appears to have very little filler and a bunch of contamination.





                  Griff
                  I sanded and then SS wire brushed it. The edges are plasma cut, so that probably didn't help.

                  Comment


                  • #10
                    Originally posted by Bodybagger View Post
                    That may be tearing from the root. Do you have a keyhole in front of your weld puddle while welding?

                    Also, are your welds cooling too fast? Have you considered using a little preheat? That sheet of aluminum is an awfully good heat sink for sucking the heat away from the weld rapidly.
                    Hmmm....I might be watching for enough penetration. This is my 1st major AL welding project, so I was excited just not to blow a 1/2" hole in it.

                    I didn't think that preheating was required on such thin material?

                    Comment


                    • #11
                      Originally posted by jpmassey View Post
                      I sanded and then SS wire brushed it. The edges are plasma cut, so that probably didn't help.
                      "Plasma Arc Cutting, Beveling, and Gouging:

                      This process has some limitations and must be carefully controlled. If it is used, it requires the power source to be set (DCEN) along with the use of small orifices to gain high velocity and concentrated heat. Heat affected zones will be crack prone particularly for 2XXX, 6XXX, and 7XXX series alloys and will require 1/8 inch or more of mechanical surface removal before welding. Series 1XXX, 3XXX, and 5XXX alloys are not as crack prone and can generally be welded as cut by this process."

                      From the Link

                      Comment


                      • #12
                        roger that

                        I was gonna say that too. Unless you are using a shielding gas while plasma cutting, you have to remove most of the HAZ because of the high levels of oxidization that occur. Even when you use shielding gas vs. comp air, the oxidization penetrates more than you would think. Also, I would use a 5356 filler on a 50xx series aluminum. It also looks like you might need to use a little more balance to clean the weld better.

                        What machine are you using? What tungsten? Balled or pointed? Pulse?
                        Last edited by Blackbird455; 10-04-2008, 12:00 AM.

                        Comment


                        • #13
                          Originally posted by Blackbird455 View Post
                          I was gonna say that too. Unless you are using a shielding gas while plasma cutting, you have to remove most of the HAZ because of the high levels of oxidization that occur. Even when you use shielding gas vs. comp air, the oxidization penetrates more than you would think. Also, I would use a 5356 filler on a 50xx series aluminum. It also looks like you might need to use a little more balance to clean the weld better.

                          What machine are you using? What tungsten? Balled or pointed? Pulse?
                          Syncrowave 250dx
                          I believe I was using pointed 2% thoriated.
                          No pulse option.

                          Comment


                          • #14
                            Originally posted by griff01 View Post
                            The picture appears to have very little filler and a bunch of contamination.





                            Griff
                            Where?

                            1234567890

                            Comment


                            • #15
                              Uhh....


                              See it now?

                              The little black pepper looking flakes that float on the top of the puddle turn into stuff that looks like that. Also notice that the white "flash" on the outside of the bead is narrow, meaning only a small amount of DCEN in the cycle, balance adjustment might fix it, but like was said before, if it was plasma cut, there is alot of oxide present, and it needs to be removed before welding.
                              Last edited by Blackbird455; 10-04-2008, 10:05 PM.

                              Comment

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