Abstract: Grain growth rule of the 2219 aluminum alloy with thickness of 8 mm under different solution treatment parameters was explored, the microstructure evolution was analyzed and the best solution treatment parameters were determined. The 2219 aluminum alloy specimens were heated to different temperatures (525, 535, 545 ℃) and kept for different time (30, 50, 70 min) before water-cooled to room temperature. The grain size of the specimens before and after solution treatment was characterized by using metallographic microscope. The results show that higher solution temperature and longer holding time can lead to more completely solution and larger grain size, which can reach a maximum of 303 μm. However, excessive grain size affects the mechanical properties of the material, resulting in the overall hardness of the material first increases and then decreases, and over-burning occurs. Considering the specimen hardness, the optimal solution treatment parameters for the 2219 aluminum alloy with a thickness of 8 mm is heating to 535 ℃ and holding for 70 min.

Key words: 2219 aluminum alloy, solution treatment, grain size