Crystallographic texture development in extruded AA 2195 and AA 7075

Abstract

The addition of lithium to high strength aluminum alloys significantly improves specific strength as is the case with AA 2195. However, unlike non-lithium containing alloys, such as AA 7075, lithium containing alloys display anisotropic mechanical properties in low aspect ratio extruded sections. The goal of this study is to elucidate the origins of anisotropy in AA 2195 and to investigate processing methods to control mechanical properties. To this end, both AA 2195 and AA 7075 were systematically extruded over a range of aspect ratios from 2 to 15 while maintaining a constant extrusion ratio. Through crystallographic texture component analysis and the use of a newly proposed parameter termed the “Plate-Like Number”, this study indicates that the Copper texture is primarily responsible for previously observed anisotropic properties of AA 2195. A series of rolling studies analyzed using the Plate-Like Number suggest that a higher initial billet temperature will minimize the Copper texture component and thus reduce the anisotropy in extruded AA 2195.