An annealing process for treatment of an aluminum alloy of AA5XXX series which comprises steps of annealing the aluminum alloy at a first temperature of from about 350° C. to about 450° C. by a rate of temperature increase from about 0.1° C./s to about 0.5° C./s; and cooling down the annealed aluminum alloy to a temperature below 50° C. Aluminum alloys of the AA5XXX series treated by the annealing process of the present invention are also provided.