AbstractThe effects of extrusion processing parameters on the mechanical properties of an AA 8090 alloy were monitored using a combination of hardness, tensile, andfracture toughness tests, and using light, transmission electron microscopy, and scanning electron microscopy. It was found that variations in the processing parameters affect the tensile properties to a greater extent in the as extruded condition than in the heat treated condition. In the former, the property changes occur as a result of both variation of grain structure and the solutionising effect during the process. In the latter, the tensile properties are controlled by the precipitation processes that occur, and the toughness remains essentially unaffected by changes in the processing conditions. Improved combinations of strength, ductility, and toughness are achieved when the material is subjected to suitable preaging treatments, which modify the precipitate morphology within the microstructure; the fracture surface characteristics of both tensile and fracture toughness test specimens reflect the microstructural changes.MST/1115