Solution is a common heat-treatment process for many different families of metals. Stainless steels, aluminum alloys, nickel-based superalloys, titanium alloys, and some copper-based alloys all may require solution annealing.
The purpose of solution annealing is to dissolve any precipitates present in the material, and transform the material at the solution annealing temperature into a single phase structure. At the end of the solution annealing process, the material is rapidly quenched down to room temperature to avoid any precipitation from occurring during cooling through lower temperature ranges. The single phase solution annealed material will be in a soft state after treatment.
The solution annealing treatment is required prior age hardening / precipitation hardening. The single phase microstructure created during solution annealing is required prior to age hardening, such that only the precipitates formed during age hardening will be present in the final product. The composition, size, and quantities of those precipitates formed during aging will determine the final product's hardness, strength, and mechanical properties after aging.
