Welding Aluminum, GTAW
Welding Aluminum, GTAW
(OP)
I am helping a friend repair some aluminum racks that hold donuts. I am using 4043 Aluminum filler that is 3/32 dia. Base metal is .125 thick channel. 3/32 Dia Tungsten that is 2% Thorium. Tonight I am changing to Lanthanated. I grind away the oxide layer with a disk grinder, Al-oxide paper. I am welding with AC, high frequency on continuous, straight Argon 15 CFH. I can't seem to get the bead to flow and look nice. It balls up and looks sooty like the end of a cigarette. Contamination is high prior to me cleaning, oxide as well as food particles. I am also questioning whether I am cleaning enough. The racks do have other areas that were welded so I know it is a weldable alloy. Help??





RE: Welding Aluminum, GTAW
http://www.alcotec.com/psdiff.pdf
http://www.alcotec.com/psgtaw.pdf
RE: Welding Aluminum, GTAW
RE: Welding Aluminum, GTAW
RE: Welding Aluminum, GTAW
Are you using welding grade Argon? If not do so. You may also wish to increase your gas cup size and increase Argon flow rate.
RE: Welding Aluminum, GTAW
Capntom, take a look to this site: www.alcotec.com/atras.htm
Good luck !
RE: Welding Aluminum, GTAW
RE: Welding Aluminum, GTAW
You are trying to remove aluminum oxide. Don't use aluminum oxide to remove the same. You will imbed the oxide into the surface on which you are trying to weld. Aluminum oxide has a melting point greater than 3200 degrees F while that of the base metal is on the order of 1200 to 1400 degrees F. Use silicon carbide as one alternative to aluminum oxide abrasives. Carbide rotary files (burrs) are also an alternative to consider. You will want to use a "Vixen" type that is made for soft materials such as aluminum, copper, or brass.
Be sure to degrease the aluminum with a solvent such as acetone followed by 90% isopropyl alcohol. Follow the degreasing by removing the oxide before welding. Be sure you clean all your tools with solvent before using them to clean the aluminum. Do not handle the filler metal, base metals, etc. with your bare hands. The oils in your skin will cause porosity.
I agree with one of the other respondents that you should be using pure or zirconiated tungsten when welding with AC.
Best regards - Al
RE: Welding Aluminum, GTAW
RE: Welding Aluminum, GTAW
How big of a powers source are you useing? whats your ac balance? These are imortant to take note to. .125 isnt that thick so you should be ablet to turn up your cleaning action which will help to get rid of oxides. grinding isnt probably the way to go with cleaning it. try useing scotch bright buffing pads on a 4-1/2 or 5" grinder. that cleanes it up pretty nice and leaves a smooth finish much easier to wirebrush off remaining oxides. for best results wire brush just before you weld. and if you really need to just run a arc arcross the join once with no filler and wire brush right after. the cleaning action will break up crud on the surface. note that changing the ac balance to more cleaning you are putting more heat on your tungsten so you should use non pure electodes. Thoriated is good but gets jagged, and it also has some health risks. lanthanated is my favorite and it balls ok.
Hope that helped
RE: Welding Aluminum, GTAW
RE: Welding Aluminum, GTAW
Anyhow this is what I found.
1.Clean your parts with acetone
2.Heat them good and hot with a torch,cook all the nasties out.
3.SS wirebrush,perhaps grind, and solvent clean again,per post of gtaw.
4.Use Zirconiated tungsten,ball on a piece of clean copper.
5.Use helium
If you grind,your welding supply store will have special wheels for Al. If you draw black smoke,grind out,reheat and clean again.
Free donuts/coffee are required.