Aluminum Welding Question

I assume you have 75%Co2 and 25% Argon?..............Argon is a shielding gas and inert , while Co2 is active and will react to the aluminum adding heat and probably corrode or contaminate the weld zone.....

I guess the tacks are just temporary and then later your going to go 100% Argon?.......It's not going to look pretty but give it a try...........problem is down the road when you do weld it up permanently you'll have to grind off and clean up around those tack welds.......................take a couple of pieces of aluminum and do a test on the bench..

 

Give it a try.........if it bubbles up the weld.......chances are there may not be much strength to the tack or spot weld....turn down the amperage as the Co2 may burn the aluminum........if you have aluminum welding in your future and have the spool gun......maybe a small bottle of Argon should be considered? Not sure if your current regulator will work? On TIG I use a flowmeter for Argon.

 

The short answer is no. The mix gas you typically use for your steel mig welding is known as C25 gas (ie. 75% / 25% ARGON to CO2). As tarry said, you will be introducing contamination into the weld. It will be in the form of carbon. Your weld will probable be covered with a black oxide. You can test on a piece of scrap material.