[AT] Spam> welding aluminum

[Steve W.]

John Hall wrote:
> Not tractor related but it's 60 years old. Need some advice welding cast 
> alum. Appears to be good quality casting--no sign of porosity. The guy 
> trying to weld the part for me slightly preheated the part and then started 
> Tig welding. About 5 seconds after he would stop, the weld would crack. 
> After he welded and let the part cool for 2 hours I could pull it apart by 
> hand. Besides the hairline cracks the weld looked great--no signs of 
> contamination or air pockets. Oh yeah the parts had been degreased and then 
> bead blasted.
> 
> Any suggestions?
> 
> John Hall 
> 

Cast aluminum can be a real PIA to weld. You need to know the exact 
alloy. Even then it is touchy if it is the wrong type of alloy. You have 
to heat the part up hot enough to stop shrinkage from cracking the weld. 
While you weld you keep the aluminum at that temperature. Then once you 
finish the weld you need to keep it warm and SLOWLY cool it. Just about 
like cast iron. If this isn't a stressed part you might be able to use 
one of those low temperature aluminum solder type items to repair it.

-- 
Steve W.