Abstract: Effect of intermediate annealing temperature on microstructure and properties of 4004/3003/4004 three-layer aluminum alloy composite sheet for power batteries of new energy vehicles was studied by means of optical microscope, scanning electron microscope and universal tensile testing machine. The results show that with the increase of annealing temperature, the cladding rate does not change obviously and has small deviation, the composite interface of the composite sheet is clear and straight. The Si particles in the 4004 aluminum alloy layer are fine and dispersed, and the size is 2-4 μm. All the grains of the core material 3003 aluminum alloy layer are recrystallized when the intermediate annealing temperature is 370 ℃. The tensile strength and yield strength of the composite sheet decrease sharply at first and then tend to be stable with the increase of intermediate annealing temperature, but the elongation shows an opposite trend. When the intermediate annealing temperature is 370 ℃, the strength and elongation of the composite sheet begin to be stable, thus 370 ℃ is the optimal intermediate annealing temperature of the composite sheet, at which the tensile strength and yield strength are 137 MPa and 80 MPa respectively and the elongation is 31%.

Key words: intermediate annealing, new energy vehicles, power batteries, aluminum alloy composite sheet, microstructure, properties