PDA

View Full Version : Gas Welding Aluminum . . . . .



Markopolo
03-21-2004, 12:30 AM
OK, I waited a long time to say this, because I wanted to make absolutely sure I couldn't do it....

"You cannot oxy-acetylene weld aluminum" !

I've tried and tried....different size tips, different filler rods, different fluxes, ....ALWAYS CRAP ! !

I can braze it beautifully, using Aladdin 3 in 1, or HTS 2000, or even plan ol' 4043.....and I can stick weld it nice too, (with Eutectic-Castolin 4021)......

But when I try to gas-weld it........BLAH ! ! ! (it just crumples into a heap). :angry:

motordoctor
03-21-2004, 01:24 AM
http://www.tinmantech.com/html/faq__why_gas_over_tig_.html

Brainfarth
03-22-2004, 02:14 AM
What about Jesse James and his first episode? Wasn't he working aluminum tanks with gas?

Rocky D
03-22-2004, 02:20 PM
Originally posted by Markopolo
OK, I waited a long time to say this, because I wanted to make absolutely sure I couldn't do it....

"You cannot oxy-acetylene weld aluminum" !

I've tried and tried....different size tips, different filler rods, different fluxes, ....ALWAYS CRAP ! !

I can braze it beautifully, using Aladdin 3 in 1, or HTS 2000, or even plan ol' 4043.....and I can stick weld it nice too, (with Eutectic-Castolin 4021)......

But when I try to gas-weld it........BLAH ! ! ! (it just crumples into a heap). :angry:
You can oxy/ acetylene weld aluminum. It needs to be clean, and fluxed. The rod needs to have flux on it also. You can use aluminum arc rod for filler, too. It is difficult due to the brightness of the flux burning, and you can't really see when it becomes hot enough to dip the rod. When you finally get it hot enough to dip, then go like a bat out of hades. Keep the rod in the puddle. It takes a lot of practice, perseverance and patience. One you get it, tho, it's easy.

Markopolo
03-22-2004, 05:19 PM
Thanks Rocky.....I'll keep trying.... *sigh*

Franz
03-22-2004, 06:16 PM
Marko, are you sure you'r trying to weld one of the aluminum alloys that is gas weldable?

Markopolo
03-22-2004, 06:36 PM
Franz, I have NO idea what alloy it is. It's the stock you can buy at hardware stores.....angle, flat bar, rod......that stuff.

I'm using Welco #10 flux.

Franz
03-22-2004, 06:55 PM
Marko, I'd certainly deferr to the Herbivor's expertise on aluminum, but I'm wondering if you aren't starting with an alloy that can't be O/A welded.
You can always use the tried & true Herbivor methods of joining it though, either rivet it or glue it.

Markopolo
03-22-2004, 07:19 PM
DAMN IT FRANZ . . .where's yer' sense of adventure ?

ANYONE can glue or rivet.....If someone out there is telling me that Aluminum can be O/A welded, I'm gonna' make it my personal mission to figure out how to do it !

Markopolo
03-22-2004, 09:09 PM
Rocky D....(or anyone else that knows)....You said I could use Aluminum stick electrode as filler for gas welding.......

Do I break the flux off and use only the bare metal, or should I leave the flux on and use "as is" ?

Rocky D
03-22-2004, 09:16 PM
Originally posted by Markopolo
Rocky D....(or anyone else that knows)....You said I could use Aluminum stick electrode as filler for gas welding.......

Do I break the flux off and use only the bare metal, or should I leave the flux on and use "as is" ?

Yeah, you can use it...leave the flux on.

enlpck
03-22-2004, 09:42 PM
I will make a guess, based on what is available in both the local HW stores and the Orange place, that the material you have is 6061. This is quite a common alloy for bar and angle, as it has good strength, cuts and machines easily, and is weldable. Doesn't bend real sharp without cracking, tho. Often in the T6 condition (full heat reated) so loses some strength when welded. None of the references I have at home indicate if it is gas weldable or not, but it is arc weldable, even by me (I rarely weld Al and am at best sufficient).

Markopolo
03-22-2004, 10:08 PM
Thanks enlpck.......I can arc weld it quite nicely with stick.
I don't have a tig, and when I went to my welding guy and asked if I could do it with my hh135, he started talking about spool guns, different gas, yada, yada, yada.........$$$$$$
(I figure he needed to make a boat payment).

This latest little tag i'm on is trying to weld it with oxy/acetylene.

I've heard it CAN be !.....my mission: TO LEARN HOW TO DO IT !

When I'm old and cantankerous, and "newbies" say "it can't be done"...I want to be the one to say: "Yes it can... ya' just gotta' know how" !

Rocky D
03-23-2004, 11:40 AM
Marko. how thick is this stuff you're tryig to weld? Oxy Acetylene works real good on 14ga and thinner.

morpheus
03-23-2004, 12:38 PM
Originally posted by Brainfarth
What about Jesse James and his first episode? Wasn't he working aluminum tanks with gas?

that was steel

OlPilot
03-23-2004, 02:40 PM
Guys, the weldable aluminum alloys are 1100, 2219, 3003, 5052, 5083, 5086, 5454, 5456, 6061, 6063, 7005 and 7039.

For the least cracking tendancy use 4043 filler with 1100, 2319 filler with 2219, 4043 filler with 3003, 5356 filler with 5052, 5083, 5086, 5454, and 5456, 4043 filler with 6061 and 6063 and 5356 with 7005 and 7039.

About the higher strength aircraft alloys - 2024 contains copper and 7075 contains zinc and neither are weldable. (Yeah, you can weld 2024 and 7075, but they'll crack the minute you turn your back.) 6061 is a lower strength aircraft alloy and welds well. 2219 is a neat material. It's used for jet engine nose cowl lip skins because of its superior resistance to cracking from anti-ice heat cycling. It does eventually crack however, and I've Tig'd many a catapillar with 2319 over a nose cowl crack on wing. Not wild about the procedure, however since there was no good way to get gas to the backside, but the FAA won't let you fly with a crack, so it was more of an interim "get out of Dodge" repair pending lip skin replacement

All this brings up the inevitable question - what alloy do I have? About the only sure way I know is to use an eddy current tester borrowed from the NDI guys. Set up on the IACS (International Annealed Copper Scale), it'll read different conductivity for different aluminum alloys. Even there, the readings will be close for similar alloys, so some interpretation is required.

Most of the hardware store aluminum sold is of the cheaper 30XX or 50XX series and therefore weldable. I doubt that they stock 6061 because it's more expensive. You won't find non-weldable aircraft grade 2024 or 7075 there either, for the same reason.

bomberz1qr20
03-23-2004, 03:20 PM
OlPilot, you're probably the one to ask...

What is the "weldable" difference between 7005 alu and 6061? What I understand is that 6061 is weldable, but needs heat treatment afterwards to gain back it's pre-weld strength. I've been told 7005 does not need this.

These are the two most common alu alloys used in bicycle frame construction these days.

The whole heat treating thing is a bit of a mystery to me, care to comment?

Markopolo
03-23-2004, 07:25 PM
Rocky....I'm practicing on 1/8" flat. Last night I actually DID it !
The weld looked crappy, but survived the bend-test ! I got 100% penetration (almost had a little burn-through).
I think if I keep at it, I'll get it. I used an aluminum stick electrode for filler. One more thing: You weren't bulls#itting when you said: "Go like Hell" ! !

bomberz1qr20
03-23-2004, 08:12 PM
Originally posted by Markopolo
Rocky....I'm practicing on 1/8" flat. Last night I actually DID it !
The weld looked crappy, but survived the bend-test ! I got 100% penetration (almost had a little burn-through).
I think if I keep at it, I'll get it. I used an aluminum stick electrode for filler. One more thing: You weren't bulls#itting when you said: "Go like Hell" ! !

A guy in class tried last night. What a waste of aluminum that was!

:rolleyes:

I may try one of these days.

Markopolo
03-23-2004, 08:50 PM
Bomberz . . . .It AIN'T easy, especially if you're used to working on steel. A few night's ago, I would have said: "It's just not going to happen"....but with the encouragment I got on this site from everybody (especially rocky d)....... I'm going to keep at it until I get it....or they send the wagon for me....whichever comes first !

I'm bound and determined to gas weld aluminum ! :blob4:

Franz
03-23-2004, 10:53 PM
Marco, when last that was practiced commonly, during WW II, since acetelene was rationed and prioritized to ship building, the fuel gas used for aluminum welding on aircraft parts was hydrogen.
Now, if you want to have some fun, swing by the welding supply store, and tell them you're looking for a hydrogen/ox torch cause you want to weld aluminum.
If there ain't an old fart there, things ought to get interesting.

OlPilot
03-23-2004, 11:22 PM
Yeah, and while you're at the welding supply store, tell 'em you want some helium for your heliarc torch. That's sure to make 'em think you're Franz's and my age!

enlpck
03-23-2004, 11:52 PM
OlPilot:

the Al bar I've picked up locally has all been 6061 (mill marked as such) but I was just supposing the angle was as well, as it isn't marked. Any idea which is more ikely? Any compatability issues welding the 3000 or 5000 series to 6061 if (well, when) the need comes up? what fille would be appropriate?

Franz
03-24-2004, 12:08 AM
OP there are a couple supply houses here that I call from time to time and ask about Heliarc, just for the hell of it. It generally takes them a few minutes till they tell me their computer doesn't show that, or that they don't carry the Heliarc brand.
Dang kids here have no idea what the hell Heliarc is now, but a few of the smarter ones have heard of helium/argon mix.

OlPilot
03-24-2004, 01:16 AM
Enlpck, I'll double check my notes tomorrow afternoon when I get back to work, but I think you would be reasonably safe with 4043 filler.

Bomberz, I'll also check my heat treat and AL notes. Some of these AL alloys naturally age after welding and recover much of their original properties in the HAZ. Other don't.

Franz, I've heerd tell that the old timey Heliarc welders talked funny - sorta' like Donald Duck - after welding for awhile in the flat position. May just be an old weldor's tale.

Brainfarth
03-24-2004, 04:56 PM
On motorcycle maina(jesse james first show) he was annealing aluminum for his tanks and gas welding them. Motorcycle maina 2 is when he started using steel tanks.

Franz
03-24-2004, 05:52 PM
Originally posted by Brainfarth
On motorcycle maina(jesse james first show) he was annealing aluminum for his tanks and gas welding them. Motorcycle maina 2 is when he started using steel tanks.
I was actually paying attention on the first show, and what he was doing was brazing the aluminum tank.

OlPilot
03-24-2004, 07:40 PM
Gas welding aluminum is a neat thing to do just to prove it can be done when your tig machine is broke. The disadvantages are:

1. An active welding flux is required to clean and protect the aluminum from oxidation.

2. Welding speeds are slower.

3. Heat affected zones are wider.

4. Weld metal solidification rates are slower, increasing the possibility of hot cracking.

5. The gas flame offers no surface cleaning action.

6. Welds are likely to contain a larger numbers of discontinuities.

7. Distortion of the weldment is greater.

Acetylene is best, hydrogen will work with thin sheet. But remember, the flux residues are corrosive to aluminum in the presence of water. Probably the best way to clean is to immerse the weldment in a 10% solution of sulfuric acid at room temperature for 20 - 30 minutes then rinse thoroughly with hot water. Steam cleaning works also.

OlPilot
03-25-2004, 05:13 PM
Bomberz, both 6061 and 7005 are heat treatable Al alloys. 7005 is stronger by roughly a factor of two. Use 5356 filler exclusively with 7005. For bicycle frames, I assume we are generally talking about tubing. Heat treatable alloys develop improved strength by solution heat treating in a salt (not sodium chloride) bath solution then quenching followed by either artificially or natural aging. During fusion welding, the elevated temperatures in the heat affected zone will overage the heat treated metal, softening it somewhat. But the additional metal added in the bead usually compensates for the loss of properties.

The big concern is weld cracking. This can usually be prevented by welding with a filler that has a higher alloy content than the base metal. As an example, 6061 has a normal silicon content of .6% and is extremely crack sensitive when welded with 6061 filler. By using 4043 filler, with a 5% silicon content and a lower melt point, the filler will remain more plastic than the base metal and it will yield during cooling to relieve the stresses that cause cracking. Again, it's another tradeoff because if you wanted to heat treat the assembly afterward, the 4043, being a non-heat treatable alloy, won't gain a thing in strength. If you need maxium strength with 6061, use 5356 filler. It's not heat-treatable either, but it is stronger than 4043, although not as forgiving in regard to cracks.

Combining alloys that contain magnesium or copper with each other should be avoided. Don't use 5XXX filler with 2XXX base metal and vice-versa or you'll be in crack city.

Most aluminum alloys come with an alphanumeric designator after the alloy designation which designates the temper and process. For example, T1, T5 and T10 below could apply to extrusions. Cold working of sheet may be done through rollers to increase strength. Various post-process temperatures are used to artificially age AL, which also increases strength. Natural aging is done at room temperature (24-48 hrs.) I'll list those designators here for everyone's benefit.

F - As fabricated
O - Annealed
H1 - Strain hardened only
H2 - Strain hardened and partially annealed
H3 - Strain hardened and thermally stabilized
W - Solution heat treated
T1 - Cooled from an elevated temperature shaping process and naturally aged
T2 - Cooled from an elevated temperature process, cold worked , and naturally aged
T3 - Solution heat treated, cold worked and naturally aged
T4 - Solution heat treated and naturally aged
T5 - Cooled from an elevated temperature shaping process and artificially aged
T6 - Solution heat treated then articicially aged
T7 - Solution heat treated and stabilized
T8 - Solution heat treated, cold worked then artificially aged
T9 - Solution heat treated, artificially aged and then cold worked
T10 - Cooled from an elevated temperature shaping process, cold worked and then artifically aged.

bomberz1qr20
03-25-2004, 05:56 PM
Mr. Pilot, I thank you.

Supercharged S10
06-12-2004, 11:52 AM
very interesting