The heat treatment to ensure the final performance of the product is called finished product heat treatment, including finished product annealing, solution treatment, quenching, natural aging and artificial aging; in addition, graded aging and deformation heat treatment processes have also been developed. Aging treatment not only improves the mechanical properties of the product, but also improves the stress corrosion resistance and fracture toughness of the product. The transfer time from solution heating to before quenching should generally be controlled within 30 seconds.
The cooling rate of quenching must not only ensure that a supersaturated solid solution is obtained, but also avoid excessive quenching stress and bending deformation of the product. Coils and sheets are annealed in box furnaces, pit furnaces, vertical plate continuous annealing furnaces or air-cushion continuous annealing furnaces with strong circulation ventilation. The new furnaces use protective atmosphere. Quenching is generally heated in a salt bath, and the new process uses an air cushion type continuous quenching furnace for quenching.
