I recently tried TIG welding on a shifter console out of a sideshifter. It is made out of some sort of cast aluminum alloy. It is not magnesuim and I doublechecked by trying to burn shavings.. they just melt.
When attempting to weld it using argon gas, AC, and a pure tungsten electrode, it just foams up from the inside out and turns into a bubbly black mess as soon as it melts. Does this just mean it's unweldable, or is there some way to do it?
I have experience welding cast aluminum, I've welded an intake manifold and a water pump, and they both came out fine. It must be something special about the material this part is made of.
Full Version: Hard to weld aluminum alloys
QUOTE(bondo @ Apr 19 2006, 01:25 PM) 
I recently tried TIG welding on a shifter console out of a sideshifter. It is made out of some sort of cast aluminum alloy. It is not magnesuim and I doublechecked by trying to burn shavings.. they just melt.
When attempting to weld it using argon gas, AC, and a pure tungsten electrode, it just foams up from the inside out and turns into a bubbly black mess as soon as it melts. Does this just mean it's unweldable, or is there some way to do it?
I have experience welding cast aluminum, I've welded an intake manifold and a water pump, and they both came out fine. It must be something special about the material this part is made of.
First off you need to get it EXTREMELY clean. As you know tigging requires the metal to be alot cleaner than mig or stick. On older aluminum and especially cast, or anything associated with grease the part should be cleaned, heated in an oven cleaned again heated again 3-4 times to boil out anything that may have been "absorbed" into the part. Sounds like to me you have alot of impurities in there, or it is has a low aluminum content and is mostly mag or something else. As for the cleaning use brake cleaner and a heavy scrub brush. Brake cleaner is the least likely to be absorb and cause more problems. Also keep an eye on your tungsten to make sure it doesn't get dirty. You don't have to touch the surface to contaminate it. Fumes from what you are werking on will latch onto a hot tip in a second!
QUOTE(scotty b @ Apr 19 2006, 05:06 PM)
QUOTE(bondo @ Apr 19 2006, 01:25 PM)
I recently tried TIG welding on a shifter console out of a sideshifter. It is made out of some sort of cast aluminum alloy. It is not magnesuim and I doublechecked by trying to burn shavings.. they just melt.
When attempting to weld it using argon gas, AC, and a pure tungsten electrode, it just foams up from the inside out and turns into a bubbly black mess as soon as it melts. Does this just mean it's unweldable, or is there some way to do it?
I have experience welding cast aluminum, I've welded an intake manifold and a water pump, and they both came out fine. It must be something special about the material this part is made of.
First off you need to get it EXTREMELY clean. As you know tigging requires the metal to be alot cleaner than mig or stick. On older aluminum and especially cast, or anything associated with grease the part should be cleaned, heated in an oven cleaned again heated again 3-4 times to boil out anything that may have been "absorbed" into the part. Sounds like to me you have alot of impurities in there, or it is has a low aluminum content and is mostly mag or something else. As for the cleaning use brake cleaner and a heavy scrub brush. Brake cleaner is the least likely to be absorb and cause more problems. Also keep an eye on your tungsten to make sure it doesn't get dirty. You don't have to touch the surface to contaminate it. Fumes from what you are werking on will latch onto a hot tip in a second!
This was on a surface that I had sanded about 1/16th off of to get a "clean" surface for welding.. and I wire brushed it seconds before starting. That's about as clean as it gets without baking it to cook off impurities. It doesn't seem like a very pourous material, it actually looks less pourous than the water pump I sucessfully welded. The color of the metal and density are about the same too. It could be part magnesium, but isn't that weldable too? I was able to melt aluminum rod into the puddle and it melted in, but the bubbly crap was still there.
Does anyone know what percentage magnesium it takes for a magnesium-aluminum alloy to become flammable?
You need to preheat the part first. Heat it to 350 degrees before you try and weld it. This will help tremendously and yes you will still have to deal with the impurities, but it it will weld much better.
Good Thread starting here guys... more "practical" tips for welding aluminum?
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