Yes, you can, but with some challenges. It is not as easy to weld the 7075 aluminum flat bar as it would for, say, a steel bar. The aluminum alloy has high thermal expansion and electrical conductivity. Given that this material is super hard, a lot of heat is required for melting. It has an extremely high dissociation temperature. This alloy forms an oxide layer quickly, with the melt section being even more prone to this challenge. For the welding process to be effective, one must use argon or any other inert gas cover.