Regards, everyone. At the moment I'm trying to develop a GMAW procedure to spot weld two overlapped 1/8'' AISI 1020 sheets. The upper sheet has a 5 mm diameter hole, in whose center the wire is positioned. How could I start trying (parameters, pre and post gas shielding, welding time, etc...). I could already notice in preliminar tries that either intern or extern central cavity (by the way, what would be the technical term for that?) is very difficult to get over.

Thanks a lot.