learning tig welding aluminum help

[scard]

Lets see if we can figure this out. I'm teaching myself to tig weld. What I have here is a Miller Dynasty 200DX rig, set: AC, 130A max, HF start, no pulse, 125Hz soft square, 15sec post flow, 70% EP, 15cfm Argon. The tungsten is 2% Ceriated (orange band) 3/32", filler rod is 3/32" ER4043. Material is 6061 aluminum very well cleaned with a whole variety of methods. Hey, we know how to clean aluminum don't we.

Everything is fine and controllable except for the roughness of the filler bead. It is kinda' like as if sand was in the molten pool after the filler was added. This is just a filler issue it seems. If I run a puddle without filler, it is nice and smooth and looks right. When I add this filler, I get this very ugly bumpy finish on the bead. I've tried all different settings on the machine setup, %EP, frequency, amperage, gas flow (all the way up to 20cfm). I've tried all kinds of cleaning methods of the base material, scotchbrite wheel, acid etch, etc... If you know something that I don't, please speak up. Is this filler simply not compatible with 6061? I think more likely I'm just missing something obvious. HELP. You never know, I might want to fabricate an RV part some day if I can build some good skills. My next stop will be a welding forum if the answer doesn't exist in our community.

[rbibb]

I suspect impurities on the base material and/or the rod. 6061 will corrode instantly when exposed to air. I suspect the filler rod does as well. Perhaps some flux formulated correctly for aluminum will help but I'm speculating.

[AlexPeterson]

Scott, are those pictures as welded, no post brushing or cleaning?

I'm far from being proficient, but I too "taught" myself tig welding aluminum (with help from Larry V. and Devin Pierce on the phones/email) . I welded a bunch of 6061 using 4043 rod, and don't recall seeing exactly what you had (unless it had black stuff in it before cleaning for pictures). What was a little tough for me initially were a few things. First, it takes almost no ambient air movement to blow away the gas shield. My ceiling fan lazily turning was messing me up. It would cause corrosion in the work, leaving some of the patterns you show. Second, make sure the tungsten is sucked up into the nozzle as close as possible. Third, don't park the filler rod close to the arc- either put it in the action or get it away. Medium distance seemed to heat it up without shielding. I also changed to a gas lens setup, about 10 bucks. It focuses the gas flow more towards the arc. Don't know how much it helped, but in the end I got reasonably good. Overall most difficult part on my project was trying to balance heat loads to non-symmetrical parts. 130 amps is not much for aluminum. I was welding 1/8" structural tubes and angles, and my 165 amp setup was marginal. I think having a helper with a propane or oxy-acet torch to preheat the weld regions would have helped a lot.

One thing is for sure - after you get reasonably good at aluminum, tig welding steel seems like a joke.

[Don Jones]

....that I use Scott. I just checked and mine is ER4043 rod as well and I do not get the rough beads you are getting. It is an impurity issue. I was told many years ago by an old welder to never clean aluminum for welding with anything but a stainless brush. Have you tried welding some without cleaning it at all? I generally have the best luck if I don't clean unless absolutely necessary. YMMV

[CMW]

Scott,

It looks like an impurity issue. I had very similar looking welds recently using my syncrowave 250. I had to turn the balance way down for maximum cleaning. I know you have much more control of the arc with the dynasty and I think you can adjust both sides of the AC square wave, but maybe not on the 200dx. I would set %EP much lower for more cleaning. If this doesn't work, check out the Millerwelds forum. I think there was some discussion on grainy welds with the 200dx.

Chris

[rocketbob]

Turn your argon down, the welds have that appearance because the argon is cooling the weld puddle too rapidly at the surface. 15 on the flow meter is just a place to start, it will change depending on your welding speed, the size of the cup, and if you're using a gas lens or not. Keep the HF on continuous on aluminum, it helps to stabilize the arc, especially at lower currents. I use 1% lanthanated tungstens (black), since you can use them both on AC and DC.

[Randy]

That Dynasty will do just anything you want, I have one and love it. I have had good results with the factory default settings. If you are not using a gas lens, get one. It may not solve your problem but it will help anyway. The gas lens causes the argon to come out like a fog rather than a stream of gas greatly improving gas coverage. You can generaly use less gas flow when using a gas lens and it allows you to keep the tungsten sticking out of the cup further. I have had the same results you show a few times, and never did determine exactly what it was.

If you are welding and want best strength, you might want to switch to 5356 filler.

Make absolutley sure your argon hose connections are not leaking. They don't usually leak, they suck. A very small leak in a hose will draw atmoshere into the hose and contaminate everything you weld. That could be what you are dealing with.

They say you should not use the 2% thoriated on aluminum, but lots of people do it, apparently with good results.

Are you balling the tungsten or keeping a point? In the old days you simply had to ball it. With these new machines that have so much control of the arc balance and ac wave form etc. you can get away with a pointed tungsten and in some cases it really helps focus the arc where you want it.

That is my .02!

Randy C

[scard]

Originally Posted by AlexPeterson

Scott, are those pictures as welded, no post brushing or cleaning?

I'm far from being proficient, but I too "taught" myself tig welding aluminum (with help from Larry V. and Devin Pierce on the phones/email) . I welded a bunch of 6061 using 4043 rod, and don't recall seeing exactly what you had (unless it had black stuff in it before cleaning for pictures). What was a little tough for me initially were a few things. First, it takes almost no ambient air movement to blow away the gas shield. My ceiling fan lazily turning was messing me up. It would cause corrosion in the work, leaving some of the patterns you show. Second, make sure the tungsten is sucked up into the nozzle as close as possible. Third, don't park the filler rod close to the arc- either put it in the action or get it away. Medium distance seemed to heat it up without shielding. I also changed to a gas lens setup, about 10 bucks. It focuses the gas flow more towards the arc. Don't know how much it helped, but in the end I got reasonably good. Overall most difficult part on my project was trying to balance heat loads to non-symmetrical parts. 130 amps is not much for aluminum. I was welding 1/8" structural tubes and angles, and my 165 amp setup was marginal. I think having a helper with a propane or oxy-acet torch to preheat the weld regions would have helped a lot.

One thing is for sure - after you get reasonably good at aluminum, tig welding steel seems like a joke.

Yep, those pictures are completely untouched after the weld. No brushing or anything. No black stuff in any of my results. They all come out exactly as you see. I only posted two pictures, but have probably 50 different bead tests with different configurations. Yeah, I had thought maybe my shop A/C was an issue, so did plenty of tests with the shop air turned off. No difference. Sounds like I need to try a gas lens. This is definitely not a heat control problem as far as I can tell. I had real skills with oxy-acet at a time before I had even heard of (acceptable) TIG. Not so different in many ways, just better . Thanks so much for your comments.

Originally Posted by Don Jones

....that I use Scott. I just checked and mine is ER4043 rod as well and I do not get the rough beads you are getting. It is an impurity issue. I was told many years ago by an old welder to never clean aluminum for welding with anything but a stainless brush. Have you tried welding some without cleaning it at all? I generally have the best luck if I don't clean unless absolutely necessary. YMMV

Indeed, I have tried welding some base uncleaned. What could be easier . Same exact results. I have not tried a simple stainless steel brush, but I have a hard time figuring how that could be so much better than all the gyrations I've gone through with grinding, scotchbrite wheel, acid etch, MEK, soap & water, etc... To my untrained eye, I agree with you, it looks like impurities. Grrrrr...

Originally Posted by CMW

Scott,

It looks like an impurity issue. I had very similar looking welds recently using my syncrowave 250. I had to turn the balance way down for maximum cleaning. I know you have much more control of the arc with the dynasty and I think you can adjust both sides of the AC square wave, but maybe not on the 200dx. I would set %EP much lower for more cleaning. If this doesn't work, check out the Millerwelds forum. I think there was some discussion on grainy welds with the 200dx.

Chris

Yeah, I've tried the %EP down to about 40%. It gets pretty violent and clearly something isn't right if that is required. I did read those threads on Millerwelds. Didn't get me much further. Thanks for the comments.

Originally Posted by rocketbob

Turn your argon down, the welds have that appearance because the argon is cooling the weld puddle too rapidly at the surface. 15 on the flow meter is just a place to start, it will change depending on your welding speed, the size of the cup, and if you're using a gas lens or not. Keep the HF on continuous on aluminum, it helps to stabilize the arc, especially at lower currents. I use 1% lanthanated tungstens (black), since you can use them both on AC and DC.

Hmm, I've tried gas flow from about 8cfm to about 20cfm in separate tests. No change. I'm not using a gas lens but will very soon clearly. I like the idea of the pool cooling too rapidly. It is definitely an instantaneous operation.

Originally Posted by Randy

That Dynasty will do just anything you want, I have one and love it. I have had good results with the factory default settings. If you are not using a gas lens, get one. It may not solve your problem but it will help anyway. The gas lens causes the argon to come out like a fog rather than a stream of gas greatly improving gas coverage. You can generally use less gas flow when using a gas lens and it allows you to keep the tungsten sticking out of the cup further. I have had the same results you show a few times, and never did determine exactly what it was.

If you are welding and want best strength, you might want to switch to 5356 filler.

Make absolutely sure your argon hose connections are not leaking. They don't usually leak, they suck. A very small leak in a hose will draw atmosphere into the hose and contaminate everything you weld. That could be what you are dealing with.

They say you should not use the 2% thoriated on aluminum, but lots of people do it, apparently with good results.

Are you balling the tungsten or keeping a point? In the old days you simply had to ball it. With these new machines that have so much control of the arc balance and ac wave form etc. you can get away with a pointed tungsten and in some cases it really helps focus the arc where you want it.

That is my .02!

Randy C

I'll double check my hose connections. I'm using a point on the tungsten. Arc seems to be correct and generally stable. I'll get a gas lens and see what happens. I don't care squat about a max strength weld at this point. I'm just looking for a presentable bead . Since you're the first to report the same equipment, you should expect a PM from me in the coming weeks after I try some more tests with a gas lens .


Anybody else??

[Don Jones]

take two pieces of 6061 and overlap them. Then just flow the edge of the top piece onto the bottom without any filler rod and see if you get the same bumps. If you don't I will bet it has something to do with the rod. Bob's suggestion about cooling the puddle too quickly sounds right as well, but if you have tried different flows on the gas, probably not.

Edit: Just re-read your original post. I see you have tried the no filler rod routine. I would try some different rod. By the way, how big is the diameter of the gas cup you are using? If it is too small it could be an issue as well. I seem to remember getting similar results with a too small cup, which wasn't completely surrounding the weld with shielding gas causing contamination???? Mine is about 1/2 inch id.

[scard]

My non-gas lens cup is about 1/2" ID. That is the biggest I have. I did some more tests this morning with gas flow. Higher gas flows do have more of a negative impact, but too low (tried down to about 4cfm) and it clearly isn't enough shield. I'm going to go try to pick up a gas lens this afternoon to see if that fixes my problem.
I also did some more cleaning tests. All the way from a completely unprepared piece to the other extreme. It pretty much doesn't matter with respect to the rough bead.