Day 3 kicked off with a lecture on AC welding on aluminum and magnesium. We only practiced on aluminum, but the techniques and machine setup are similar between the two materials. Both materials form oxides on their surface that melt at much higher temperatures than the parent metal underneath. These oxides need to be removed while welding, and the electrode positive half-cycle of the alternating current is what breaks them up. We discussed the AC balance on the machine and the pros and cons of more cleaning action (balance towards more electrode positive) and more penetration (balance towards more electrode negative). We also discussed the frequency of the AC cycle, and how a higher running frequency results in a tighter arc and deeper penetration. It's amazing all of the technology that goes into AC welding and the resulting flexibility the adjustments provide. I made quite a mess of some nice coupons of 6061, but I was having fun doing it. I also did a few more tubing samples towards the end of the day.
Butt weld
Added a T joint
Lap welds
Started getting out of hand. See that big puff of black? Yeah, I hit the tungsten with the filler rod.
Edge weld
Outside corner
Trying to get into a tight spot. Well, maybe a tight spot for a beginner. Note the
TIG Finger Heat Shield in the background. Very handy.
Tubing attempt #4
Tubing attempt #5
Tubing attempt #6
Tubing attempt #8
That's about it for day 3. I've been adding more photos to the Photobucket gallery
HERE. Thanks for reading!
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