Questions on butt welding 6061 aluminum

admin

I have acquired a few pieces of 6061 aluminum for practice. http://weldingweb.com/vbb/showthread.php...aluminum-scrapI tried welding one of these approx 8mm (5/16) thick prepared the same way as I would a steel joint (60 degrees bevel, 4mm gap, 1mm land).It seems I cannot get ANY penetration even at maximum amperage (230A in my case which is kind of borderline). I have tried various settings frequency and balance wise with no success. The filler simply balls up on the back of the root without fusing with the bevel edges.No pics available as I cut out the welds.The only thing that I have not tried (and I probably thing is the correct thing to do) is to use no gap and 3-4mm land.Am I correct in my guess on what to do? I am quite experienced with welding all types of materials but not aluminum. I have no problem with aluminum fillet welds or thin butt welds but I need some help with this.
Reply:To add a few more information.Tungsten 2% Ceriated 2.4mm (3/32)Argon flow rate tried from 6 to 10 lpm (ca. 12 to 20 cfh)Gas lens used with cup sizes 5,6 & 7Welding position PA (flat).If you need any more information let me know.I have searched Jody's video but I could not find any video on thicker material. All I could find were for 3-4mm material with a square butt preparation.Last edited by taz00; 06-18-2014 at 11:01 AM.
Reply:At 200+ amps my machine starts melting the end off a 3/32" thoriated tungsten and spitting it into the weld.(I have an old transformer machine with no adjustments for positive/negative)With my machine in mind, here's me shootin' from the hip.Frequency I have almost no experience with (mine is fixed at 60Hz for example).Lots of negative for penetration.1/8" tungsten, #7 or #8 cup.Tungsten ground very blunt for deeper penetration (see pics) arc wander and arc starting should not be an issue at 230 amps anyway.And/or you could try a double bevel.Good luck Dave J.Beware of false knowledge; it is more dangerous than ignorance. ~George Bernard Shaw~ Syncro 350Invertec v250-sThermal Arc 161 and 300MM210DialarcTried being normal once, didn't take....I think it was a Tuesday.
Reply:Thanks.I have an inverter and 3/32 tungsten can operate without spitting for a short period.It even has a setting which is called mixed TIG in which it alternates from AC to DC which I also tried but in this case did not make a big difference.Off course extended welding at these currents would require the use of a bigger tungsten and probably a water cooled torch.I could double bevel it but this is not my intention. It is not some repair I have to make just practice material.Maybe a better way of expressing my question would be:When butt welding thick aluminum plates to you prepare them with a V bevel and a gap in the root like you would with steel or do you prepare the edges with a V but a thick land with no gap?
Reply:I'm an amateur, but bevel seems good. When I hold a long arc I don't get good penetration. A tight arc I expect is easier for a younger person than me, though I seldom dip because I shake, usually it's when the filler does something unpredictable, or the hoses are caught on something. I swear by the TIG finger from Jody. I wish he offered a whole glove/gloves. The closer to the tip of the tungsten I can hold the torch the more precise. Full coverage of gas is critical. Wash it into the joint. I see people laying the torch too flat. Nearly perpendicular works best. Stay focused on the leading edge of liquid, as the wet puddle forms a horseshoe move the torch back a bit and dab filler. Dave's chart is a revelation to me. It seems counter intuitive. I had always assumed a needle like point would pinpoint the arc. I will try this soon. It's all too easy to ride too far back on the puddle, that doesn't give good penetration. turn up your frequency to 150, balance at 75% It should work.