Microstructure evolution and mechanical properties of Al-Cu-Li alloys with different rolling schedules and subsequent artificial ageing heat treatment

Abstract

Mechanical properties, precipitate microstructures and textures of AA 2195 Al-Cu-Li alloy with different rolling schedules and subsequent artificial ageing heat treatment have been investigated. The highest ultimate tensile strength (UTS) and yield strength (YS) were obtained in a longitudinal direction of the hot-rolled alloy at 280 °C due to a higher number density of the T1 phase and the increased volume fraction of the textures with rolling textures. In contrast, the second highest UTS and YS in the longitudinal direction and the highest UTS and YS in the transverse direction was clarified in the cold-rolled and hot-rolled alloys at 225 °C. This ‘anomalous’ anisotropy can be explained not only by a higher number density of the θ’ phase within fine and equiaxed recrystallized grains but also by grain boundary precipitates at low-angle grain boundaries. Therefore, textures control was suggested to be a useful method to improve mechanical properties in addition to the conventional precipitation strengthening.