5a02 aluminum alloy is an Al Mg series rust resistant aluminum. Compared with 3A21, 5a02 aluminum alloy has higher strength, especially higher fatigue strength; High plasticity and corrosion resistance, similar to 3A21 in this regard; Heat treatment cannot be strengthened, and resistance welding and atomic hydrogen welding have good weldability. There is a tendency to form crystal cracks during argon arc welding; The alloy has good machinability in both cold work hardening and semi cold work hardening states, but poor machinability in annealing state and can be polished.