Texture and anisotropy in Al-Li alloy 2195 plate and near-net-shape extrusions

Abstract

Low density aluminum-lithium (Al-Li) alloys, such as 2195, are candidate materials for reducing the structural weight of cryogenic tanks on launch vehicles. The objective of this investigation was to establish the relationship between mechanical anisotropy, microstructure and texture in a near-net-shape ‘T-stiffened’ extrusion and in two gauges of plate. In both product forms, in-plane properties were measured as a function of orientation to the extrusion/rolling direction; tensile properties in increments of 15° and fracture toughness properties at 0, 45 and 90° to the principal axis. Mechanical behavior was evaluated at two locations in the skin of the extrusion, namely midway between and directly beneath the stiffeners. The microstructures of the plate and extruded product were characterized using cross-polarized light imaging of anodically etched metallographic sections. The textural characteristics were quantified as a function of location within the respective cross-sections using orientation distribution function (ODF) analysis. Tensile and fracture properties were correlated with microstructural and textural characteristics in the 2195 near-net-shape extrusion and compared with plate product.