6xxx series is Aluminum alloy which components Al-Si-Mg-Cu. After Solution heat treatment and Quenching, α phase in the matrix alloy change to α+θ . But θ phase do not mix with α phase (Not homogeneous). Artificial Aging is a homogeneous process that equilibium mixture between θ phase and matrix α phase. When matrix is homogeneous, the hardness increases in this alloy. Applications of artificial aging include Fuselage of a civil aircraft, Transport, Truck frames etc. Solution Heat treatment heat work pieces to 550˚C After that, the measurement of hardness and plot the Brinell hardness graph for considering about hardness of Al alloys 6xxx series. From the graph show you about relation between hardness and aging time.