[AT] Spam> welding aluminum

[Steve W.]

Oh cast aluminum can cause you to go crazy some times.
The trick on heating is to KEEP the part hot while your welding it. Then 
let it all cool together. The trick is to get the part hot enough 
without it turning into an instant lump! Aluminum conducts heat VERY 
rapidly and cools just as fast. By keeping the part hot while your 
welding it you keep the possible shrinkage at a minimum. Personally if 
the part isn't structural I would likely look at pinning it together 
then using something like AlumiWeld on it.

What is the part your working on?



John Hall wrote:
>  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.

-- 
Steve W.
Near Cooperstown, New York