Sandy looking alum tig welds.

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I have recently been learning tig. My steel welds are good but I am now trying to learn alum tig so I can build a ladder rack for my new truck. My welds seem to have a frosty look and look like someone sprinkled sand on them. Some more than others. The stack of dimes look also seems less defined. I seem to remember seeing examples of a lot better alum tig welds than I have been getting and want to improve mine.My instructor had a stroke and the sub has been less than helpful. The " Just play with the heat and you'll get a feel for it" has been the responces so far in last weeks class. Here's what I have been trying with little or no luck. Using a synrowave 200 set to ac max 150 ampFoot petal at about 75% +/-.balance from 3 to 7 I see some difference in cleaning on the edges but no change in the sand. Better cleaning on 3 than 7Gas lens vs regular cup, Not noticing alot of difference in the weld, I can tell when I have the tungsun out of the gas flow however with the std cup on corners.100% argon at between 25-30 cfhTungestons 3/32 cerated (orange) with a medium point, 3/32 pure tungstun (green) balled, 1/8" cerated (orange) with a medium point, 1/8" pure tungstun (green) balledFiller 4043 3/32 and 1/8"Base 1/8" 6061 and a 5 series 1/8" dimond plate ( I can't remember the exact # 5456 I think)Prep on base cleaned with scotchbrite pad, SS wire brush and no cleaning.Prep on rod scotchbrite, wiped with acetone, and no cleaning.I don't seem to have as much control over the puddle size as I did with steel. I could get a puddle from 3/16"w to 3/8" + in steel. In alum I either can't get the toes to melt in or I melt the crapout of it. Welds that look close to right seem to be about 3/8" wide. I seem to be able to get a slightly narrower puddle with the 1/8" cerated tungston but not to a great extent.I also have available in tungstuns 1/16" green and blue, 3/32" red, black and blue, 1/8" red, black, and blue. I have no idea what the black and blue ones are I was given them with some other welding stuff in the past.I do seem to get a somewhat better bead by useing a circular torch motion with my dipping. However I have had some turn out sort of ok when I didn't.Any help suggestions would be appreciated. My last class for the term is on thursday nite and I would like to narrow down my options so that I can try and get the most out of my substitute instructor before I have to go it alone this summer. I want to eliminate as many variables as posible and concentrate on what the problems might be.here's some pictsThanks.Last edited by DSW; 04-14-2008 at 06:16 PM.
Reply:They look good to me.  Try going a little faster.  Maybe twice as fast as you would on steel.  Use the heat.  Run it hot enough that the filler cools the puddle.I don't know about the sand look.  Do you change your tungsten as soon as you contaminate it?  It doesn't matter which color tungsten, It doesn't seem to have any effect on my welds.In the last picture you have too much  cleaning.Dimes don't mean much to me, those are nice looking welds.David Real world weldin.  When I grow up I want to be a tig weldor.
Reply:IMO, you are running your beads too hot.  Try running them a little cooler, and dipping a little less often.  In my little bit of experience, the sandy look can be from too much heat. What you want to do is establish a puddle, dip your filler in a bit, move ahead about 1/4-1/3 the width of the bead, dip again and so on.  That will lead to a more defined stack of dimes.  The more filler you put in, the more it cools your puddle, but also try using a little less foot pedal (or move faster)Also, don't forget to fill in your craters or you will get cracking.  It is a good idea to fill your craters even on practice beads just so it becomes habit.Last edited by weldrwomn; 04-14-2008 at 08:21 PM.
Reply:The grainy appearance is down to the silicon in 4043 in combination with too much heat. Dropping the machine to 120A or so will improve pedal resolution.No need for circles/weaves or anything like that for 1/8" Al. You shouldn't need the torch to 'melt the toes in'- add sufficient filler to the puddle to reinforce it, not so much that it spills overProbably the pictures but it looks like the weld's cracked along the toes in places
Reply:flip your plates over, take a look and see if your burning up the back side of the plate.  You should have a heat signature line, but it should not be crumpled up looking (hard to describe)  The backside of the plate should not have any sort of burn through marks.  If it does your running too hot.1/8" filler is a little heavy in my opinion, stick with the 3/32" and either move faster or turn your machine down.The way i tig weld is i set the machines amperage to the MAX i want, not just an arbitrary number.  When i start i floor the pedal and as i move along i back the pedal off as the peice heats up.  This will help you control your heat alot easier, and will end up giving you better control over the puddle.Id also turn the gas down, 25 is way high for what your doing, id use around 15 cubic feet.  when you start having to pay for your own gas you will understand why.  excess gas flow can also create turbulence and actually induce the atmosphere into the puddle, that doesnt look like what is going on here, but just good to know info.anyways hope that helped a little
Reply:I find that typical in 4043 filler. I see almost none of the sand look with 5356 filler.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:I had the same problem with the sand grains when I started aluminum.  I found I got better results when I wiped with acetone after brushing the aluminum with a ss brush.Build a Barstool Racer at BarFlyRacers.com!
Reply:Thanks for all the suggestions. I hope to have some time tonight to play with the machine. I'll try and post some picts later in the week or early next.