Microstructural Evolution of a Cold Roll-Bonded Multi-Layer Complex Aluminum Sheet with Annealing

A cold roll-bonding process using AA1050, AA5052 and AA6061 alloy sheets is performed without lubrication. The roll-bonded specimen is a multi-layer complex aluminum alloy sheet in which the AA1050, AA5052 and AA6061 sheets are alternately stacked. The microstructural evolution with the increase of annealing temperature for the roll-bonded aluminum sheet is investigated in detail. The roll-bonded aluminum sheet shows a typical deformation structure in which the grains are elongated in the rolling direction over all regions. However, microstructural evolution of the annealed specimen is different depending on the type of material, resulting in a heterogeneous microstructure in the thickness direction of the layered aluminum sheet. Complete recrystallization occurs at 250 ℃ in the AA5052 region, which is lower by 100K than that of the AA1050 region. Variation of the misorientation angle distribution and texture development with increase of annealing temperature also differ depending on the type of material. Differences of microstructural evolution between aluminum alloys with increase of annealing temperature can be mainly explained in terms of amounts of impurities and initial grain size.