Understanding the strength increment of Al-Zn-Mg-Cu aluminum alloys by enhanced solution-treatment (EST)

Enhanced solution-treatment (EST) tends to increase the strength of aluminum alloys by increasing the solute concentrations due to the sufficient dissolution of soluble constituents. However, results of spray-formed 7055 Al-Zn-Mg-Cu alloy indicate that the strength increment occurs only in hot-extruded alloy not in cold-rolled one and is related to increasing the average Taylor factor (MA) instead of the solute concentrations. The increased MA of hot-extruded alloy is attributed to the transformation of some S texture grains into the Copper texture ones with increasing the solution-treating temperature, whereas recrystallization and grain growth of cold-rolled alloy exerts little effect on the MA.