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  • porosity

    Hello Everyone, So I am very new to this sight but need help it seems, So we
    are welding up some round 12ga A1011 sheet metal round tanks here,. they are butt welds as you can see or can't see in pics. With 90/10 gas we were getting pin holes so we tried 92/8 and it was a lot worse and then we went to 85/5 and it is much better, However there is occasionally still some small holes in the weld. The bottom of the tank connects to a 3/8 ring A36 and using the 85/5 gas we are getting very very small holes in this weld, what could be the cause? third pic shows the groove we cut for prep before welding. Any help will be appreciated, Hopperman

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  • #2
    I have a couple of offerings on the matter. Shielding gas flow isn't offering adequate coverage, nozzle size could be to small and with too long of stick out your sucking in air. 26 Volts is in the spray transfer range, 450 seems high for WFS but who's to say if your not there doing? It could also be from the Anti splatter MIG dip? Check for gas leaks, some might suggest a bad gas cylinder (?), or windy shop conditions?
    Me...I lean to think it's a operator issue?
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ID:	597191 But what do I know? What's your gas flow set to, what does the nozzle size offer for coverage, is the tip recessed to compensate for stick out?


    • #3
      Settings seem a skosh high to me as well, but all machines run a bit differently. Those holes look, to me at least, more like a weld settings issue than a gas coverage issue. Or maybe a technique incompatibility. Butt welds like to suck air from the backside too.


      • #4
        Looking again at the pictures, on the one showing the weld groove prep, is that it? I mean, doesn't look like you've done much to remove surface contamination post gouging. Are you grooving it out with a grinder or what?


        • #5
          so thanks for the reply's,
          yea we are using the 1/16'' cutting blades and cutting small groove as shown, though that was just a sample to try to show what we are doing,

          our nozzels are 5/8 opening with a stickout of 5/8 inch including the recessed part. gas is set at 40

          So the tanks are turning and we are at the 4:00 position where we are welding and running downhill, we were running the wire speed at 390 but seemed to smooth out when we turned it up to the 450 mark,


          • #6
            Let me ask a couple more questions of you and then we can have all the cards on the table . Are you welding to a WPS? Are you using .035" wire,
            did this just happen? Was it after a wire change and the gun cable not inserted all he way?
            ER70S-6? Are you doing any prep besides the slit? I'm no expert and there's a few ways to do what your doing, yours is different. 4 oclock seem 2 hours off?
            I'm guessing your issue is one of pulling air up thru the bottom of the weld puddle?
            I'd do a bit more groove to the prep, adjust my parameters and position, I would drop voltage, I would shrink my stick out and adjust wire speed. Is that 40 cfh/ lph/ 40 psi? All that brown suggests a lack of shielding /gas coverage or contamination being brought in thru turbulance?
            The fine splatter on the edges, that's not from spraying. That's higher voltage, lots of stick out and wire speed with a short I think? But something is crackling I'm sure?


            • #7
              I see the groove, but I don't see any other metal prep in that picture. The surface does not look ready to weld to me.


              • #8
                Porosity is caused by a couple things. Lack of shielding or contamination. Contamination comes in many forums. Scale, grease, paint, gouging slag, dirt etc.
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                • #9
                  I think you are missing something in your shielding gas. 85/5 ? What is the other 10% ? Possibly you mean 85/15
                  A pic of the backside welded would be nice.
                  Vertical down spray getting close to overhead?? (4 o'clock).... I'd be more a 10 o'clock uphill guy myself and then work from there. So hard to make suggestions coming in the middle of something without much to go on.
                  Just looking at the line formed by the weld defects suggests something in line with the joint.
                  Could be a hundred things. What was used to cut the parts to fit? Is the wire clean? what is the wire?
                  I would need more pics and know more about conditions. Things have to be prepped NICE for bare wire.

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