The effect of off-axis thermomechanical processing on the mechanical behavior of textured 2095 Al–Li alloy

This investigation was conducted to study the influence of off-axis deformation in the thermomechanical processing on the properties of Al–Li 2095 HT72 alloy sheet. The thermomechanical processing involved several stages. First, the as-received hot rolled sheet was solution heat treated at 510°C for 30 min. Samples were then cut from the sheet and stretched off-axis at 0, 30, 60 and 90° angles (stretch axis) to the original rolling direction. All the specimens were then aged at 180°C for 24 h. Tensile coupons were then machined from each of these aged samples at 0, 30, 45, 60 and 90° (tensile axis) to the rolling direction, then tested to failure. The crystallographic texture and tensile properties of the processed samples were evaluated, and were compared to the solution heat-treated material. In the solution heat-treated condition, the material was highly textured with a very strong Brass component. Off-axis stretch followed by aging had little or no effect on the texture development of the solution heat-treated material. Upon testing, samples with stretch axis at 0° showed pronounced mechanical anisotropy; specimens tested at 45° showed about 40% drop in tensile and yield strength values when compared to those tested at 0°. However, stretching along 60° or 90° directions minimized mechanical anisotropy. The texture characteristics of all tested samples were determined and related to the changes in the mechanical properties. An attempt was made to correlate the data with some texture theories. Analysis of the results and normalization based on the Taylor’s factor showed that that crystallographic texture contributes only partly to the total mechanical anisotropy.