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 deforma tion in the thermomechanical processing on the properties of Al-Li 2095 HT7 2 alloy sheet. The thermomechanical processing involved several stages. Fir st, the as-received hot rolled sheet was solution heat treated at 510 degre es C for 30 min. Samples were then cut from the sheet and stretched off-axi s at 0, 30, 60 and 90 degrees angles (stretch axis) to the original rolling direction. All the specimens were then aged at 180 degrees C for 24 h. Ten sile coupons were then machined from each of these aged samples at 0, 30, 4 5, 60 and 90 degrees (tensile axis) to the rolling direction, then tested t o failure. The crystallographic texture and tensile properties of the proce ssed 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 a ging had little or no effect on the texture development of the solution hea t-treated material. Upon testing, samples with stretch axis at 0 degrees sh owed pronounced mechanical anisotropy; specimens tested at 45 degrees showe d about 40% drop in tensile and yield strength values when compared to thos e tested at 0 degrees. However, stretching along 60 degrees or 90 degrees d irections minimized mechanical anisotropy. The texture characteristics of a ll tested samples were determined and related to the changes in the mechani cal 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. (C) 1999 Elsevier Science S.A. All rights reserved.