Tig Welding Aluminum Norms

[smithworks]

I am a self taught welder. I have tig welded for over 10 years, mainly steel stainless and silicon bronze. I would consider myself a very good welder. I have recently started working a lot with aluminum and am getting frustrated with what I feel are non satisfactory welds (mainly the presents of porosity).

The thing is that since I am self taught I don't know exactly what you should be able to achieve.

I weld mainly 1/4" 6061/6063 with 4043 filler rod. I have a brand new Dynasty 350.

An example of difficulty I am having is the following:

I am making a frame out of 2.5" 6063 square tubing with .25" wall. I miter the tube and bevel the ends to receive weld so I can grind flush. I use walter grinding discs made for aluminum. After I grind I sand off any burrs, clean with lacquer thinner and then wire brush with dedicated stainless brush. I clamp the frame down to my table and begin to weld. When I first puddle the joint and add a bit of filler rod, if I continue to hold the arc over the puddle it just bubbles. In fact any time I strike an arc and form a weld puddle on Aluminum it will just sit there and bubble. Is this normal? I don't see how it is possible to get a porosity free weld if my puddle is bubbling. I am running straight argon at about 20-25. I am welding at about 250 amps with 1/8" zirconiated tungsten with a gas lens. I have messed with all the setting to no avail.

The other 'is this normal' question I have is: with the afore mentioned settings, how long should my tungsten tip last? I grind them to a truncated point with the flat spot being at least 1/16" in diameter and I only get about 6" of weld before the tip start to deform (starts melting and splitting at tip).

Please help.

Thank you.

[ja baudin]

Use acetone instead of lacquer thinner, thinner may not evaporate away completely contaminating your weld.

[shovelon]

What size cup are you using ? 20-25cfh would take like a #8.

Did you vent your frame so your don't get air pressure buildup inside?

[shovelon]

Sanding the bevel or edges can leave resin residue embedded in the surface. Use a file on it.

Check your backcap to see if it is blocking the gas port in your torch. Check for a crushed collet. Check to see if your gas lense is contaminated. Check you machine gas fittings with bubblecheck.

Try another bottle of gas, clean your gloves, calibrate your flowmeter, and see that the gas line does not have a hole or is pinched.

Keep trying, and you will find the problem.

What are your parameters set at?

[SundownIII]

Just a couple suggestions...

Lose the zirconated tungsten. For AC welding on an inverter, I prefer the 2% Lanthanated. Second choice would be ceriated. The zirconated tungsten performs best on the squarewave machines, in lieu of the pure (green).

Try using 5356 filler vs the 4043. Think you'll have better results. I'd be using 1/8" filler for that job.

Gas flow is fine. Since you haven't experienced problems welding SS, I'm going to assume that there's no problem with covering gas.

As mentioned, a #8 cup will be your best choice here.

As mentioned, acetone vs thinner works better.

Set your balance to about 85%. On new, clean material, that's all the cleaning you'll need.

Aluminum is different than steel. As soon as you get your puddle, add filler and move. By staying in one place you're "cooking" the material. Aluminum likes to be welded hot and fast. Welding hot and fast also reduces the size of the HAZ.

Don't futz with the pulser or the independent amplitude adjustments. The Dynasty will weld that joint just fine without them.

It will take a little time to adjust to aluminum (vs SS and mild steel), but I think the biggest problem you're having is staying in one place too long and cooking (overheating/boiling) your base metal.

Once you get started, and the material starts to build heat, you'll find you need to back off on the amps or your puddle will get too fluid (wide).

Give it another whirl, hot and fast.

[LarryO]

I would also stop using aluminium grinding disks as they also have a tendancy to deposit crap in the Alu.

[go2building]

I prefer a dry band saw for cutting aluminum, The cut off wheels and sanding discs do nothing but contaminate.


Good luck.

I've used aluminum grinding wheels and flap disk sanders to bevel joints and never had a problem with contamination. I've taken AWS cert tests doing the same.
What do you guys use to bevel Joints?


When you brush with stainless steel brush, you should only brush in one direction and not too aggressive, brushing too hard with back and forth motion can imbed contaminants.
Kevin

[Portable Welder]

I use carbides, I'm not saying that I never have but I also have experienced contamination from them.

I'm trying to eliminate any possible problems, Sand blasting has also contaminated parts.

[go2building]

I use carbides, I'm not saying that I never have but I also have experienced contamination from them.

I'm trying to eliminate any possible problems, Sand blasting has also contaminated parts.

Do you use carbide burrs in a die grinder?
Kevin

[Portable Welder]

Yes, I use carbide burrs in a die grinder, Keep in mind its not that I never use a grinder. On heavy things like relining the bed of a gravel train when I'm using my push pull aluminum mig Yes I mainly use a grinder but on more delicate things that are going to be tig welded like a air conditioner line I try to stick with a wire wheel only.