It is a kind of high-strength duralumin, which can be strengthened by heat treatment. It has medium plasticity in annealing, hard quenching and hot state, and good spot welding. When gas welding and argon arc welding are used, the aluminum tube tends to form intergranular cracks; The machinability of aluminum tube is good after quenching and cold work hardening, but it is not good in the annealing state.