My first attempt at OA welding aluminum


I have finally had the time to try welding two pieces of aluminum using my OA setup. The pieces were 100x70x6 mm and I tried to butt weld these pieces.

I had ordered the oerlikon F14 (F LH-1) powdered flux, which I mixed with rain water so that I had a white cream. I used a stainless steel wire brush to clean the edges of the aluminum pieces. I then applied the flux to the weld area. Then I started the flame using a number 3 tip and adjusted a carburizing flame. But when I started to heat the weld area, the area quickly got covered with a black coating (carbon?) When I applied the aluminum rod (covered with flux as well), it melted, but it ended up being a ball of melted aluminum and didn't adhere to the base metal. It just kept rolling around the base metal. The base metal also melted at the joint, but not so much.

Now, one thing I am confused about is whether I was doing aluminum welding or aluminum brazing. Either one would work for me, but I think brazing would be easier. Do the plain aluminum rods and the above flux work for brazing? Should I have adjusted a neutral flame instead? Maybe my heat was too much and I just burned the flux.

Any help about what could be wrong appreciated...

Reply to
Timur Aydin
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I have gone over the information in this link:

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========================================================= A good example of how aluminum reacts when heated can be seen if you place a small piece of sheet aluminum on a welding table and heat it with a neutral flame. Hold the flame perpendicular to the surface of the sheet and bring the tip of the inner cone almost in contact with the metal. Observe that almost without warning the metal suddenly melts and runs away, leav- ing a hole in the sheet. Now repeat the operation with the torch held at an angle of about 30 degrees to the plane of the surface. With a little practice, you will be able to melt the surface metal without forming a hole. Now try moving the flame slowly along the surface of the sheet, melting a small puddle. Observe how quickly the puddle solidifies when the flame is removed. Continue this practice until you are able to control the melting. When you have mastered this, proceed by practicing actual welding. =========================================================

Should this exercise be done without applying flux?

Reply to
Timur Aydin

Adjust the flame to Neutral, you don't want a carburizing flame on aluminum. The reason for the troubles you had are the excess carbon from the flame.

Reply to
Steve W.

maybe this will be some help.

I went to the osh kosh air show thing once and they had some guy doing flame aluminum welding trying to sell some equipment. It was fast and I recall he said you clean up after not before like in tig. He had an aerosol can of magnesium cleaner for mag wheels to clean up with.

I went home and attempted to do the same. Initially I bought some flux It is probably somewhere. Later I came across a bunch of coated electrodes for stick welding and now if I do any aluminum welding that is what I use. It takes a while to get going and then it goes real fast I suppose if you aren't holding the flame in the right direction it won't go fast in the right direction. The fumes are awful. If you have ever seen these salesmen for low temp rods that poke holes in beer cans and fix them with a propane torch that stuff you kind of have to scrape the rod into the metal to get it going that might help. I have a box of some eutectic product I think is very similar but it is hard to have real confidence in it. Maybe if I used flux I would have more confidence. Since I have tig capability I rarely use flame however one repair I did makes me think the weld is more flexible for repeated flexing than tig and 4043.


Reply to

I've not done gas welding of aluminium in awhile but I always recall the flux was so deliquescent that you could just leave it for a short while, 30 minutes or so in the UK, and it would absorb enough water from the atmosphere to dissolve itself and a rinse afterwards to be safe.

Must try it again over the weekend as I have all the stuff still. One thing I never seemed to have an issue with was seeing the weld, I recall the flux went water clear when upto temperature and I never had problems with glare from the flux when using normal goggles.

Regarding aluminium brazing, I think 4047 alloy is suitable for this when a higher melting point parent metal is used. The 4047 alloy being a eutectic composition, or near, and melting significantly below many common aluminium alloys that you might want to join.

Reply to
David Billington

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