DC TIG welding aluminum

Date 04-28-2005 04:24

Experience yes, BAD real BAD! Let me clarify it was really ugly, but I did get fusion that held but I would not accept money for it, and who doesn't like money.
Good luck,

By magodley (**)

Date 04-28-2005 12:23

It can be done. It will require Helium gas, DCEN, and keept he rod in the puddle. I'm sure there are others out there who have done this more recently than I have. I learned from Everett Rodgers at Oak Ridge, TN.
Andy

By pipewelder_1999 (****)

Date 04-28-2005 17:53

I have performed this on some electrical enclosures in the field with GTAW DCSP, and Helium. Should be wire brushed RIGHT before welding .

Have a nice day

gerald

By stormee Date 05-12-2005 15:46

Hi. I know this is kind of late but just happened to stumble across your post.
I have welded with DC for a company I contract to on a regular basis. You will need to use Helium and make sure that the material is very clean. I would always brush as well as wipe it down with acetone or equivalant immediately before welding. Also clean the rods that you will be using as this process tends to leave black looking tracks that may or may not brush out if not cleaned enough. The weld is very different from AC as in the look and puddle will be much more contaminated looking and make sure your tungeston is sharp not balled. You can play around with the dip technique and find whats comfy for you. I always dip but when I was first showed how to do it they told me to push the rod. I prefer to dip but like I said you will have to see whats comfy for you as long as the penetration is good.
Feel free to email if you have any questions and I will do what I can to help. Good luck. Also consider pulsing depending on material thickness.

By Jomann61 Date 03-19-2006 04:52

I used to weld torpedo parts and containers here and there with DCSP. It works best on heavier sections and while you will hear people tell you to use straight helium, I found it best to use 15% argon-it starts better and runs a little cleaner. The material MUST BE VERY CLEAN!!!! Also, the puddle won't look like your AC. It is cloudier looking and narrower and much deeper than AC. It penetrates very well despite how it may appear. If you are welding a butt, you can lay your rod down, while still holding it, and just run over it while holding your torch perpendicular to your work with a VERY tight arc. You will have a sooty appearrance after you weld but it will brush off and if you did it right, you will have a weld that looks like a machine did it. This process is MUCH faster than AC on thick parts though I wouldn't rocommend it on anything thinner than 3/16". With little experimentation, you should have great results. This may help someone, some day. JB

By Truta Date 03-21-2007 21:58

Dear friends,
Double-walled thin Aluminum tube, no clearance between walls ( plastic deformation), circular welds at both ends all around the edges ( edge weld without filler). Wall thickness = 2.4 mm, mean diameter 29 mm.
TIG DCEN, Trimix electrode 1.6 mm , 60o, gap 0.8mm linear speed about 4 mm/sec, current 45 A. Pure helium 15-20 cfm, 6mm alumina nozzle.
Two massive copper heat sinks, external and internal, placed 2.4 mm bellow edge.
Trouble : important black soot deposit mainly on the heat sink, about 10 mm wide, but also on the weld bead itself. Soot may be easily removed with a soft brush. Trouble of the trouble is that soot is present on that part of the weld which has to be overlapped for welding completion
How can I get rid of the soot?
Thanks
Calin Truta
trutacs@gmail.com

By aevald

Date 03-21-2007 22:27 Edited 03-21-2007 22:33

Hello Truta, just looking at your post, if I understand it correctly, you've got a double-walled aluminum tube that you are welding the end together, I'm assuming, to fuse the inner and outer tubes together at their ends before you possibly weld this to something else which requires additional welding over the ends that you have previously welded. If this is the case, it sounds to me as if you may have some contamination issues from the manufacturing process related to the double-walled tubing itself. Most likely during the manufacturing process of the tube they are using some sort of metalworking fluids to aid in the production of this material. Possibly a film of the fluid is present between the inner and outer tubes and is boiling out of the joint as the welding is taking place and causing contamination issues. I can't fully picture the situation you are describing, if possible try to clarify a little better. If you are running into contamination due to the situation I have described, it could be very difficult to alleviate this problem because of the tolerances between the inner and outer tube walls. It might require washing these parts in a very hot bath of some sort of cleaner or solvent that would break down this metalworking fluid and then allow it to dry without a residue. After re-reading your post I did notice you are using DCEN current for this. Is there a particular reason for this particular choice? You may have noticed from some of the other posted responses on this thread that the cosmetics from this particular process are somewhat dirty. Hope this will help some. Regards, aevald

By Truta Date 03-22-2007 05:38

Some more details :
Indeed, the ends of the two tubes are to be welded together, but no other weld follows. My concern is for the final stage of the weld, where I have to overlap the first millimeters of the weld, in order to complete a circle weld of 360 deg + 30 deg overlap
The soot starts forming just immediately after welding starts, and its trace is nice and uniform on the heat sinks
The tubes are thoroughly cleaned prior welding in acid mixture, washed and dried in vacuum
I use DCEN with HF start sparkle because I have a suitable machine for this, unfortunately without AC ( Weldlogic AWS 150).
Could it be the quality of the heat sink material?
There are articles on the web, stating that "helium arc generates black soot" with no explanation and with no prophylaxis
Thanks for your patience
Calin Truta

By stormee Date 03-23-2007 01:31

It sounds like you have a contamination problem to start with. I would try to weld a set without using an acid mixture cleaning method. If there is anyway possible you need to just degrease them with some acetone or isopropyl alcohol and scrape the area you will be welding or using some scotchbrite to clean the area. When you use some acid mixtures you will have a risk of the material holding some of the mixture and when heat is applied then you will have some contamination in your weld puddle.
You also mentioned that you are not using a filler. I would watch for cracks if this is the case. When you weld autogenous there is a risk of cracking depending on the type of material you are using.
What type of aluminum are you trying to weld?
If this does not help please email me again and I will see if I cannot find some other suggestions for you.

Gina

By DaveBoyer (*****)

Date 03-23-2007 03:31

If You cut an assembled tube apart after cleaning but before welding how cleen are the tube surfaces where they were in contact? Could there be contaminants or oxides trapped in the joint?