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O/T Welding Pit Holes.

June 13 2017 at 3:11 PM
Bart  (Login RATPOISON511)
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What causes pit holes in alum. castings when Tig welding the castings? Thanks for any info. on problem. Bart

 
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Gerry
(Login gerryproctor)
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Usually, contamination.

June 13 2017, 3:56 PM 

Aluminum is particularly fussy about being clean. All metals have a contamination sensitivity.

 
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Dan
(Login 32bantam)
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Aluminum

June 13 2017, 4:13 PM 

Remember to clean the seam every time you stop and keep the gas on the weld until it solidifies. Aluminum and brass oxidize as you weld, if you stop you must prep before starting again. Longer post flow and higher regulator pressure may be needed as with a larger cup. If there is contamination, oil etc. use prepsol then a light acid such as vinegar, neutralize with water. If there are flaws grind the area clean and start over, otherwise you will most likely drag the trash through the whole seam.

Also if the casting is fresh or sand blasted silica is your worst enemy. I've done a few Gobmnt jobs where the castings cost too much to scrap... the only issue in fixing them in house was the boys wouldn't prep the stuff well or weld hot enough to dispell the crud . So we'd stop playing with cars long enough to learn em' and made some pals with access to better and bigger tools.


    
This message has been edited by 32bantam on Jun 13, 2017 4:31 PM


 
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