Influence of different rolling processes on microstructure and strength of the Al–Cu–Li alloy AA2195

Abstract

The influence of different rolling processes on precipitation behaviour, crystallography texture, grain morphology, and their consequent effects on tensile properties for Al–Cu–Li alloy AA2195 was investigated in the present work. The H-T8 samples (hot rolled ​+ ​T8) presented better tensile strength and ductility (with serious strength anisotropy) than the HC-T8 samples (hot rolled ​+ ​cold rolled ​+ ​T8), due to their different microstructures and textures. The higher dislocation density was found in the H-T8 samples, which promoted the nucleation of main strengthening phase T1 in the matrix and suppressed the grain boundary precipitation, resulted in better strength and ductility. The increase of the dynamic recovery (DRV) during hot rolling enhanced the generation of Brass texture, and brought serious strength anisotropy. The cold rolling was performed after the hot-rolling process for the HC-T8 samples which increased deformation energy and resulted in full recrystallization of the deformed microstructure during the following solution treatment. The formation of recrystallized microstructure reduced the dislocation density and the heterogeneous precipitate nucleation positions which limited the strengthening phase precipitation in matrix and accelerated the precipitation along grain boundaries, resulted in fewer T1 precipitates, coarse grain-boundary precipitates (GBPs), and wider precipitate-free zones (PFZs). The localized strain may be concentrated on the grain boundary to induce the dislocation pile-up, breaking of the GBPs, and intergranular fracture during stretching.