EVOLUTION OF TEXTURE AND MICROSTRUCTURE IN A THERMOMECHANICALLY PROCESSED AL-LI-CU-MG ALLOY

The development of texture and microstructure in a thermomechanically processed quaternary Al-Li-Cu-Mg alloy has been investigated. Textures on both the surface (1/8 thickness (T)) and midthickness levels of sp ecimens were measured using the conventional pole figure as well as th e orientation distribution function (ODF) method. Microstructural char acterization was carried out with the help of optical microscopy and t ransmission electron microscopy (TEM). The processing schedule involve d hot cross rolling, followed by several stages of cold rolling (CR) w ith intermediate solution treatments (STs). A marked through-thickness texture inhomogeneity developed in the processed sheets during the co urse of thermo mechanical treatment (TMT). In general, the texture pro duced at the midthickness level was 2 to 3 times sharper than the text ure at the surface. The alloy, after hot cross rolling, showed nearly equally strong Bs {110} [112] and Bs/S {168} [211] components at midth ickness. After three cycles of cold rolling (CR) and solution treatmen ts (STs), the overall texture intensity came down by a factor of nearl y 2. The final processed sheet material showed a moderately strong Bs and a predominant S {123} [634] component at midthickness. Solution tr eatments did not produce much change in the texture of the cold-rolled materials. Microstructural evidence indicated extensive recovery and, at best, partial recrystallization of the deformed structure. No sign ificant effect of second-phase particles in texture development was no ticed.