Characterization of Al–Li 2099 extrusions and the influence of fiber texture on the anisotropy of static mechanical properties

Abstract

The development of aluminum–lithium alloys for aerospace applications requires a thorough understanding of how processing and product geometry impact their microstructure, texture and mechanical properties. The anisotropy of the mechanical properties is in part related to the deformation texture formed during thermo-mechanical processing. In this study, two different extrusions of Al–Li 2099 T83 were characterized, a cylindrical extrusion and an integrally stiffened panel (ISP). A decrease of tensile properties was observed from the longitudinal direction to the transverse direction with a minimum in the 45° direction, the magnitude of which depends on the location in the extrusions. The 〈111〉 fiber texture is prominent in most locations of the extrusion with a smaller intensity of the 〈100〉 component. Rolling textures were observed in two locations of the ISP that have a larger cross sectional aspect ratio. Variations of strength and anisotropy as a function of location in the extrusion correlate well with the intensity of the 〈111〉 fiber texture. On the other hand, our findings show an absence of correlation between the Taylor factor and the anisotropy. These results suggest that strength anisotropy may be controlled by the volume fraction of T1 precipitates that could itself be related to the intensity of the 〈111〉 fiber texture.