Welding Tips and Tricks

Hey guys and gals!

Im hoping somebody can help me with mig aluminum plug welds.
I am a collision repair technician that is trying to perfect my aluminum plug welding(something that we don’t commonly do in the trade, lots of rivet/glue applications used instead of plug welding) I am practicing on 3” by 5” 1mm 6061 t6 coupons with an 8mm hole size. I am using a prospot sp5 welder. My problem is that when I destructive test my plug welds, I am having trouble with my weld tearing a hole in the bottom coupon, even with visible penetration on the bottom side. I can get it to tear about 2-3 out of 5 destructive tests. I am by no means a “ticketed” welder, but would like to make sure my welds are good 100% of the time and don’t know what im doing wrong. Any help is appreciated!

so you are laying one coupon over another and plug welding, correct? If I am understanding this correctly, then I am not sure I would expect anything different on a destructive test (assuming you are pulling the two coupons apart somehow). Pictures sure would help a lot.

When you weld aluminum, the heat input from the weld removes the temper from the base metal. If you don't re-heat treat the final welded piece, I would expect the material in the area of the weld (including the weld bead) to be weaker than the non-welded areas. 6061 T-6 if heated enough resorts back to an annealed state.