Arc welding of copper. Effect of protective atmosphere on the welding quality

Copper plates of 6 mm thickness were TIG welded with different mixtures of argon and helium : 100 % He, 80 % He - 20 % Ar, 20 % He - 80 % Ar, 100 % Ar . The specimen welded with pure helium and with a gas flow up to 17 l/min d id not show porosities. For pure argon and for argon rich mixtures, porosit ies are observed in the welded zone for a gas flow of 17 l/min. If the flow decreases to 5 l/min, the porosities almost disappear. The tensile strengt h of welded specimens varies between a minimum of 170 MPa, with an atmosphe re of 100 % Ar and a maximum of 216 MPa with 100 % He, corresponding to 73 and 92 %, respectively, of the values of the preheated base metal. it appea rs therefore that are welding of copper is possible, without significant lo oses of mechanical and metallurgical properties with respect to the recryst allized base metal.