Abstract: Influence of intermediate annealing on microstructure and mechanical properties of the cold rolled AlMgSiCu aluminum alloy sheet was studied by using tensile testing machine, TEM and XRD. The results indicate that the strength has no obvious change after 300 ℃×2 h and 400 ℃×2 h intermediate annealing. The n and r values increase with intermediate annealing temperature increasing, which arrives respectively 0.286 and 0.623 after annealing at 400 ℃ for 2 h, and recrystallization occurs and most grains are equiaxed after 400 ℃×2 h intermediate annealing. Three types of secondary phases are in the matrix: AlFeMnSi particles of about 1 μm in size, long rod AlMgSiCu phases of 0.1 μm in width and globular Si particles. The long rod AlMgSiCu phase first precipitates and then re-dissolves with the increase of intermediate temperature. The volume fraction of Brass{011}<211> texture and S{123}<634> texture of the alloy without intermediate annealing is the highest, and reaches 13.9% and 25.7%, respectively. After 400 ℃×2 h intermediate annealing, the texture in the specimen is mainly 24.3% of Cube{001}<100> type, with 10.5% of r-Cube type (both in volume fraction).

Key words: AlMgSiCu aluminum alloy, microstructure, properties, intermediate annealing, texture