[AT] Spam> welding aluminum

[John Hall]

 Slowly cooling is what I was thinking, however it was cracking before you 
could get back at it with a torch. I'm thinking it wasn't hot enough, the 
weld didn't seems to be blending with the cast.  Makes me think welding cast 
iron is going to seem easy after this!

John Hall


----- Original Message ----- 
From: "Steve W." <falcon at telenet.net>
To: "Antique tractor email discussion group" <at at lists.antique-tractor.com>
Sent: Monday, September 10, 2007 7:33 PM
Subject: Re: [AT] Spam> welding aluminum


>
>
> 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.
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