You seem to have a lot of pores in the welds you need to know what type of copper you have.hello guys, just had a dabble TIG welding some copper, the pieces were bright but not prepared, DCEN, the tip was a 2.4 thoriated, No5 ceramic, 20cfm Argon, max 90 amps. the filler was a piece shaved of the parent strip. The first two pix are a lap joint of 1.5mm thick the second two are a lap joint 0.9mm. front and back. the blow hole is me trying some silicon bronze but not sure of the rods cus i've had em that long the label has faded.
probably get better results with a pristine set up.
Best regards sutty
1. Oxygen free copper (CDA C10200 ) = good for welding no oxygen content
2. Tough pitch copper (CDA C11000) = bad for welding as it can contain up to 500 ppm oxygen