Effect of artificial ageing on strength and ductility of an Al-Cu-Mg-Mn alloy subjected to solutionizing and room-temperature rolling

Abstract

In order to expand the appilication of age-hardenable aluminum alloys, simultaneous improvement of strength and ductility is always desired. In this work, the effect of ageing at 140 °C on tensile properties, microstructures and fractographies of an Al-Cu-Mg-Mn (AA 2024) alloy subjected to solutionizing at 490 °C followed by water quenching and room-temperature rolling with 80% thickness reduction was studied. Tensile results show that both the strength and elongation of the alloy increase first and then decrease during ageing, which leads to the simultaneous improvement of strength and ductility. Microstructural analyses indicate that both the strength and ductility change with the precipitation of S″ and S precipitates and decrease in dislocation density, but not with the grain and texture characteristics. The fractographies occupied by the dimples with the decreasing diameters are due to the removal of precipitation free zones (PFZs) and the increasing S precipitates during ageing.