A process for grain boundary engineering of an aluminum alloy of AA5XXX series which includes steps of annealing the aluminum alloy at a first temperature of from about 350° C. to about 450° C.; deforming the annealed aluminum alloy to reduce the thickness by from about 2% to about 20% of the original thickness of the aluminum alloy; heat treating the deformed aluminum alloy at a second temperature from about 450° C. to about 550° C., and optionally sensitizing the heat treated alloy in one or more sensitizing steps. Aluminum alloys of the AA5XXX series treated by the process of the present invention are also provided.