Abstract: Variation laws of mechanical properties, electrical conductivity and microstructure of extruded 7C04 aluminum alloy solution treated at 450, 460 and 470 ℃ for 1 h, respectively, and solution treated at 470 ℃ for 0.5, 1 and 2 h, respectively, and aged at 120 ℃ for 18 h were investigated by means of hardness, electrical conductivity, tensile test and microstructure analysis. The results show that when the solution treatment temperature is between 450-470 ℃ and the solution treatment time is 1 h, with the increase of solution treatment temperature, the soluble second phase particles in the aged state alloy gradually dissolve, the strength, elongation and hardness increase, and the electrical conductivity decreases. When the solution treatment temperature is 470 ℃ and the solution treatment time is between 0.5-2 h, with the extension of solution treatment time, the dissolution degree of soluble second phase particles in the aged state alloy increases, reaching a supersaturated state after 1 h. If the solution treatment time is further extended, the number of second phase particles does not change significantly, the strength increases first and then decreases, the elongation and hardness continuously increase, and the electrical conductivity first decreases and then increases. Under the condition of solution treatment at 470 ℃ for 1 h and aging at 120 ℃ for 18 h, the mechanical properties of the alloy can reach a tensile strength of 645.3 MPa, a yield strength of 585.0 MPa, a hardness of 182.53 HV3, and an electrical conductivity of 27.59%IACS.

Key words: 7C04 aluminum alloy, solution treatment, mechanical properties, electric conductivity