[3 weelin geezer]

Anyone have any pix of what you end up with if you try to MIG aluminum about 3/16 thick for say....a motorcycle fender using co2? Just got me a 300 cuf tank for use on sheetmetal (steel) but I never tried aluminum on the mig. I tried with flux core :jester: just to see what I get but obviously it only made a mess and a bunch of holes.

 

[chopper5]

:nono: :nono: :nono: dont do it dont even try you need argon or argon / Eh mix

 

[weldgault]

For Aluminum only Argon or Argon/Helium, as chopper said

 

[Brett]

Yes, that is not the right mix but as 3 weelin geezer asked "What does happen ?" if theres CO2 in the mix when doing ally?
It would be good to know , even if its only to recognize if you've hooked up the wrong bottle.

 

[MAC702]

You said you tried flux-cored?

Are you also trying to use a steel wire to weld aluminum?

 

[zapster]

You said you tried flux-cored?

Are you also trying to use a steel wire to weld aluminum?

Ummmm
Yeah...

Whats up with that?:nono:

...zap!

 

[David R]

I can tell you if you use C/25 to tig carbon steel with , the arc is hard to start and crappy. Its useless. Co2 is a reactive gas. You can only tig with inert gases.

David

 

[Ben Wilson]

As an experiment I tried hooking up argon/co2 to the tig on aluminium. I couldn't even get the acr to start, the surface of the aluminium wound up burned and pitted the the tungsten went all nasty and grey.

Just don't do it kids..

 

[mooseye]

I still want to hear if it was flux-core!!!!? On Aluminum?

 

[hotrodder]

Yes, that is not the right mix but as 3 weelin geezer asked "What does happen ?" if theres CO2 in the mix when doing ally?
It would be good to know , even if its only to recognize if you've hooked up the wrong bottle.

CO2 is broken down by the heat of the arc and has a small oxidizing effect.

with the TIG process the tungsten will be oxidized as a result, wrecking both the weld and itself

aluminium oxide is removed (or should be!) before welding. trying to weld it with an oxidizing shielding gas will just oxidize it more- never tried it but i suspect the result would be similar to trying to weld filthy Al at best

only noble shielding gases can be used for welding aluminium- argon, helium or a mix of the two

You can only tig with inert gases.

David

argon/hydrogen mixs (normally 5% H) are often used with TIG- hydrogen's definately not inert.

the small mount of hydrogen gives a reducing atmosphere (improves the quality of the gas shield with respect to oxidation) and a hotter, more constricted arc (improves the welds depth to width ratio). uses are limited though- stainless and nickel alloys mainly i think

 

[David R]

I stand corected.

David

 

[weldgault]

David Nitrogen is also an inert gas and canot be used.

 

[hotrodder]

David Nitrogen is also an inert gas and canot be used.

nitrogen is not inert. the inert (or noble gases) are group 8 of the periodic table- helium, argon, xenon and some others whose names escape me

it is sometimes used in small quantities (around 2% in argon) for welding duplex (not sure whether it's used as a purge/shield or both though)- something about the nitrogen helping stabilise the austenite . i believe it can also be used as a PURGE gas when welding austenitic stainless for certain applications

 

[DesertRider33]

To answer the question-- what results when you try to MIG weld aluminum with an argon/c02 mix gas, is a mess, at least with a 25% c02 mix anyways, in my experience (hooked up the wrong bottle). I've not had occasion to try it with other mixes. It is about like trying to MIG weld steel with a steel wire, without shielding gas. I'm sure most of us know by mistake how that turns out...

 

[Go1lum]

nitrogen is not inert. the inert (or noble gases) are group 8 of the periodic table- helium, argon, xenon and some others whose names escape me

it is sometimes used in small quantities (around 2% in argon) for welding duplex (not sure whether it's used as a purge/shield or both though)- something about the nitrogen helping stabilise the austenite . i believe it can also be used as a PURGE gas when welding austenitic stainless for certain applications

Nitrogen is used in some parts of the world for welding copper alloys. It provides a little more heat to the arc to help compinsate for the great coeffecient of thermal conductivity that copper has.

 

[3 weelin geezer]

You said you tried flux-cored?

Are you also trying to use a steel wire to weld aluminum?

No, I wasn't trying to weld it. As I mentioned in the title: "Welding" in "quotations". I was using up the last few inches of one of those little rolls of wire so it wasn't like it was anything important. Just slapped a piece of ....something on to the vise and proceeded to melt holes in it. Just to see how what would happen to the aluminum, if it would melt together or not. Not. Obviously, steel wire won't adhere to aluminum. I really don't know of anything that will. Made a mess, thats about it.

Its just that I still haven't hooked up the bottle to try it. Never used gas before. Just have experience with stick (home welder mostly), O/A, and flux core 'mig'. Tried a bit of flux core on the stick welder once but it just wouldn't strike an arc. Just kept sticking and burning out the flux or spattering to bits. Doesn't work good even as an emergency filler rod (preferred over coat hangers) either. Almost like a firecracker fuse.

I guess I should have taken that bottle of helium the gas guy almost gave me? Actually, I got this to weld thin steel sheet metal. I was kinda hoping it would work on aluminum too so I can put together some new fenders for an old atc.

 

[pulser]

nitrogen is not inert. the inert (or noble gases) are group 8 of the periodic table- helium, argon, xenon and some others whose names escape me

it is sometimes used in small quantities (around 2% in argon) for welding duplex (not sure whether it's used as a purge/shield or both though)- something about the nitrogen helping stabilise the austenite . i believe it can also be used as a PURGE gas when welding austenitic stainless for certain applications

Yep, good point, nitrogen is an "austenite stabilizer" or "austenite former", and it can greatly affect the balance of austenite and ferrite in duplex SS and other SS.

For austenitic SS, it is often important to try to ensure a minimum ferrite level of 5-10% to help prevent hot cracking, and it is fairly straight forward to predict the ferrite of the weld based on the filler metal and base metal chemistries, but a big unknown factor is amount of nitrogen uptake from the atmosphere into the arc. Different processes such as Stick, MIG, Sub-arc, and TIG tend to pick up different amounts of nitrogen from the air. Even the welder's technique (ong arc, etc.) can affect nitrogen pickup, ferrite content and hot cracking.