TIG Aluminum contamination

[cbrxx]

Please look at the pictures in the link below. I'm welding 1/4" aluminum with 1/8" 2% Thoriated on AC. The welds seem to get contaminated with the 2% but look cleaner with the pure. Is the tourch suppose to look like photo 1 or is something wrong.

pics of welds

[rangerod]

Contamination

cbrxx


1. The torch cup looks like it is taking more heat than it should take to weld that 1/4" Alum.

2. Does the weld bead surface itself have a fuzzy appperance? If it does you are more than likely using too much heat to create the weld puddle. You can preheat the metal with O/A which you will see lets you create the weld puddle & bead with much less heat. If you do not want to preheat when you strike your arc give the metal time to absorb some of that heat to make it easier to run the bead & get the penetration

3. What type of gas are you using for this process? 100% argon is what I usually use with no problems. If you are using the correct gas then it might be possible that the gas is contaminated, its happened to me in the past. Is there any chance that your gas is being blown away by a breeze?

4. Are you pulling your torch away during the welding process? Keep an eye out for that because if you are pulling away it is difficult to keep the proper gas coverage & heat needed to keep the weld clean

5. What size torch are you using? Make sure your TIG torch is rated for the amps you are pushing.

These are some of the things I would check & watch during the process. I hope some of this helps.

[cbrxx]

I'm using 100% argon and the torch is rated up to 300 amps, i have the post flow set to 12 sec. Its indoors so theres no breeze and i keep the torch over the weld. Is there any sure way i can tell if my gas is contaminated or my filler rods? In the second photo the weld looked like it had pepper on it, if you make the pic full size you can see the flakes all over it.

[Guest]

Aluminum is porous and retains moisture. Preheat the base metal, by blackening it with acetylene, then heat it till the black burns off...then you will be up to welding temperature.

The beads look cold. Also you could have too much gas...AL doesn't need much flow. but I did see your tungsten was black...that could also happen by pulling it away too fast while it was still hot, so it may not mean you didn't have enough.
I noticed you had a point on you tungsten....try it with a ball on the end, by striking an arc on DC reverse polarity, then switch back to AC.

I like to use 1/8" tungsten....I can't tell what size you are using, but it should be at the very least 3/32" 2% thoriatd is Ok, too.

Rangerod gave some good advise, and I hope what I thru in the mix will solve your problem....keep us posted.

Oh, yeah, welcome to the forum!

[Stu Bass]

tig alum. contamination

Could it be the 2% tungston? I thought you were supposed to use only pure Stu

[rangerod]

TIG Aluminum

cbrxx & Stu Bass

We have always used 2% thorated tungsten & not had that problem. If it is not some kind of contamination it more than likely is something in the way you are applying your process. I didn't see how much argon flow you are pushing. Sometimes when you have too much of a gas flow it will create turbulance which allows the weld puddle to get contamination in it. Like Rocky D said you might need to turn the flow down. If there is no breeze I usually will run around 10 cfh if I must I go up from there. Let us know how your adjustment help or hurt your process.

[cbrxx]

I'm using 25 cfm of argon, I'll lower it to 15-20 and try again. Miller recommeds using 2% thoriated on AC aluminum with it tig inverter machines. I think it could be what Rocky said with the preheat, when i tacked the aluminum it left a large black mark around the tack, so would a propane torch be effective at removing the moisture? Is there a specific temp i should preheat too or just above 212 F to burn away the moisture. Thanks for the responses.

[Scott V]

One thing that nobody has talked about is your wave balance.If you jack it too far you do not have enough cleaning,and some off those black spots show up.Try some ziconiated brown tip electrodes also.They work very well with my Inverter tig on ac.3/32 would be plenty of size for .250.Start out with a point,and it will form a very small ball like RockyD said.You do not need to form one with electrode positive.

[chub380]

First what type of alum are you welding? Are you using the standard torch accs. or did you go to gas lenses? Standard lenses I would use about 20cf gas lenses15cf for that particullar applactation. Try using some brand new alum if your just practicing. Clean it with touline or some other chemical cleaner then right before you strick the arc wire brush it with a stainless steel wire brush used only for your alum welding. This is how I would set your machine up if the alum is perfectly clean and is a weldable alloy. Ac High freq impulse on,rmt standard If you want to use your pulser email me and I will give you some settings that work for me. Preflowgas 1/2 second, postflow 15sec, Balance 75-80 [if the alum is clean] ac freq 100-150 [If you want a smaller bead] If you need a larger bead just lower the freq untill you are satisfied. If you are not using your pulser 200amps with your balance set between 75-80 should be more than enough for the 1/4 alum. Now for the tungstens I started with the 2% thoriated with good success I ordered some trimix and for me they seamed to be better for s/s-steels, the trimix was very good for very low amp work on these. I have never used pure on this machine only on my syncrowave. Miller says pure will not work as good ,but I have never tried. Andy from Millers Motorsports says that cerated or lanthanted works best with this machine for all applications, so I have some lanthanated coming I will let you know how it works. I was welding alum last night with some 3/32 thoriated and it works great ,I am not sure if any other tungsten will be any better. You should be able to use the 3/32 tungsten for 1/4 with your invertor. How are you preparing your tungsten? Do you use a dedicated wheel for grinding? For alum I grind to a point then put a small flat on the end [very small] I have found that 3/32 thoriated tunsten works on alum from .035-1/4 with this machine and .020-1/4 on s/s. Everyone seemed to have good advise. Chub

[cbrxx]

I have used pure with this machine and the arc isn't as stable compared to the 2% but the welds i produce with pure are equal or better. I'm useing 1/8" 2% tappered to a flat, but the flat turns into little *****. For a high rez photo of the tip click here . I think the aluminum is 5 or 6 series and I don't have a dedicated wheel for tugsten.

[lranch]

Tip preperation is critical to a clean AL weld. If you have low hours weld time on AL ( or spastic like myself ), prepare several tungsten rods so when you stuff it you can just slap in another one. This is also a good idea if you have alot of beads to run. The extra heat will soon destroy the ball.
On another note: The last time I encountered this problem, that is, not even the Pope could run a "good one", through the process of elimination it turned out to be a leaky torch head. When torch got real warm antifreeze would seep in through a fracture and blacken/contaminate the weld. This never made any difference with steel. However, I too have gotten a gas bottle that was pumped from the mens room. I perfer helium on any AL bigger than scooter parts.
Lastly, I assume most of the members here must have real good jobs (I have three) to afford all this pre/post flow time. Not to mention the high flow rate. All my mighty Hobarts are set at: Preflow=0, Postflow=0, Flow=5.
Once again. Do a good job makin that tip and when you stuff it, make it again (look whos talkin)
Good luck.