aluminum porosity issues

[griff01]

You can also get porous aluminum welds by welding a 70xx high-strength aluminum-zinc alloy such as 7075, which is for all intents and purposes, unweldable. No matter how much you clean it or bake it, it's still got enough zinc to cause serious porosity.

Perhaps the OP ended up getting 7075 instead of 6061 or whatever alloy they specified. They both are available in the dimensions he's working with and you can't visually tell them apart. Maybe it's sourced from China and mislabeled or contaminated with excessive zinc.

A subjective test would be to melt a small chunk of it with an oxidizing flame and look for the tell-tale white soot of zinc oxide as it pops and sputters like overheated brass. A more definitive test would be shooting it with a Niton or running an atomic absorption spectrum on a sample to determine the actual composition.


It's just one possibility.

Could be something as easily missed as a micro crack in a water cooled TIG torch or condensation in the argon supply line, though the latter would be very minor. With proper puddle manipulation, the surface of the puddle can be kept liquid as the root freezes upward, forcing out any potential dissolved hydrogen and giving a visual cue to the cause. If the welds are weak from porosity and contamination despite careful material handling (and it sounds like they handle their material very carefully) and careful puddle control, I'd suspect the alloy.

I'd also try bypassing their preparation process and just give it a good mechanical cleaning and weld a test joint from there (with balance around 70) to rule out contamination from the prep.

Tell Frank he is wrong.

Griff

[Bodybagger]

Porosity in aluminum has only one cause and that is entrapped hydrogen.
Entrapped hydrogen may have many causes, all related to contamination.
Find your contamination and you will find the cause of your troubles.

Griff

You can also get porous aluminum welds by welding a 70xx high-strength aluminum-zinc alloy such as 7075, which is for all intents and purposes, unweldable. No matter how much you clean it or bake it, it's still got enough zinc to cause serious porosity.

Perhaps the OP ended up getting 7075 instead of 6061 or whatever alloy they specified. They both are available in the dimensions he's working with and you can't visually tell them apart. Maybe it's sourced from China and mislabeled or contaminated with excessive zinc.

A subjective test would be to melt a small chunk of it with an oxidizing flame and look for the tell-tale white soot of zinc oxide as it pops and sputters like overheated brass. A more definitive test would be shooting it with a Niton or running an atomic absorption spectrum on a sample to determine the actual composition.

It's just one possibility.

Could be something as easily missed as a micro crack in a water cooled TIG torch or condensation in the argon supply line, though the latter would be very minor. With proper puddle manipulation, the surface of the puddle can be kept liquid as the root freezes upward, forcing out any potential dissolved hydrogen and giving a visual cue to the cause. If the welds are weak from porosity and contamination despite careful material handling (and it sounds like they handle their material very carefully) and careful puddle control, I'd suspect the alloy.

I'd also try bypassing their preparation process and just give it a good mechanical cleaning and weld a test joint from there (with balance around 70) to rule out contamination from the prep.

[TSBWeld]

aluminum porosity issues

How is your filler wire stored? Do you wipe it down with an acetone soaked rag or pull it thru a stainless wire brush before using it? Contaminated filler metal will cross contaminate your weld.

[ajervis82]

aluminum porosity issues

I will do that an let u know the results thanks

[Rhinox]

aluminum porosity issues

do me a favor!
weld one tube, once done brush it all off with either stainless wire brush or stainless wire wheel...and then reweld over it again...no filler this time just use your tig torch over the weld
note: this is just a test
and let me know ..what is the outcome

[FusionKing]

The porosity is across all the sizes we do it's all tube stock. My amperage range is 160 on the .095 wall down to 102 amps on .035 wall

Seriously?
What are your other settings?

[ajervis82]

aluminum porosity issues

The porosity is across all the sizes we do it's all tube stock. My amperage range is 160 on the .095 wall down to 102 amps on .035 wall

[Rhinox]

aluminum porosity issues

you might be just too cold....

[Rhinox]

aluminum porosity issues

and what amp are you running your tig?

[Rhinox]

aluminum porosity issues

what thickness?

[ja baudin]

Make sure your purge gas is pure, clean argon. Maybe try a new or different bottle. Check all your fittings to make sure you don't have a leak which would pulling in atmosphere.

[griff01]

First the parts are cleaned in acids an a etching solution then put in a oven an baked to a set time for complete moisture removal , remove from the oven an put in a sealed bag full of argon. You would think that there is no chance of contamination but it's getting in somewhere where would you start

Pictures will help.

Griff

[ajervis82]

the pre weld process

First the parts are cleaned in acids an a etching solution then put in a oven an baked to a set time for complete moisture removal , remove from the oven an put in a sealed bag full of argon. You would think that there is no chance of contamination but it's getting in somewhere where would you start

[griff01]

Can't get rid of porosity in my aluminum welds. We clean bake an bag the material in argon an still an issue, I'm running a dynasty 350 an most welds are in the 2 g rotating position any Ideas on what else I should try

Porosity in aluminum has only one cause and that is entrapped hydrogen.
Entrapped hydrogen may have many causes, all related to contamination.
Find your contamination and you will find the cause of your troubles.

Griff

[ajervis82]

Can't get rid of porosity in my aluminum welds. We clean bake an bag the material in argon an still an issue, I'm running a dynasty 350 an most welds are in the 2 g rotating position any Ideas on what else I should try