Welding Tips and Tricks

I would like to join some aluminum to a magnesium engine cover. searches have resulted in people saying it will be a very very weak weld and will crack easily. So, can it be brazed with decent strength? aluminum bronze? silicon bronze? Iv'e been tig welding for about 4 yrs, havent tried brazing yet.
thanks for any pointers

I don’t think brazing is going to work. The melting point of Al and Mg is way below that of bronzes and you want the parts to be brazed to be heated so the filler will melt...

KZScott wrote:....can it be brazed with decent strength? aluminum bronze? silicon bronze?....

No. Successfully joining Al to Mg, vis a vis an electrically augmented flame (ie. fusion welding) or oxy-fuel (ie. brazing), has been studied ad nauseam within the automotive/aerospace industry since the 1970s. We've learned through T&E and RD&T that Aluminum and Magnesium "joints" form brittle IMCs (inter metallic compounds) resulting in longitudinal/traverse cracking.

The interface between the Mg and Al joint creates Mg(x)Al(y) IMCs and these intermetallics significantly weaken the bonds. Think of these IMCs as "tramp compounds", a la Sulphur and Phosphorus "tramp elements" in steel. The IMCs do noting positive towards joint integrity.

Attempting to bond an Al to Mg joint is an exercise in futility, unless you plan to use TLP (transient liquid phase) diffusion bonding (heat, pressure, time) with a Zn interface -or- Friction Stir Welding, where the material remain in a plastic state and bonding occurs via heat and pressure. The literature also claims success in using solid state welding processes (e.g. EBW, LBW).

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A cool trick is to TIG weld a 10ga Aluminum "t-joint" using Mg filler instead of Al filler. The joint will 'look good' and the weld line will appear to have good fusion. But, apply a few pounds of rotational resistance and the joint will fall apart in your hands.
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well now i know a cool trick to look like the hulk lol

is there a chance that my mg cover has some aluminum in it? and might weld ok? ive seen that some people claim they have done it if it was an alloy, but pure is exactly as you say and wont work.

i have a damaged one i can try putting some aluminum filler to and see if it has any strength at all after.