Effect of Double-Stage Aging on the Microstructure and Properties of 2024 Aluminum Alloy

This study focused on examining the impact of heat treatment on the microstructure, mechanical properties, and corrosion resistance of 2024 aluminum alloy. Various techniques such as OM, XRD, SEM, and TEM were employed for microstructural characterization. The findings revealed that subjecting the alloy to a homogenization process at 493 °C for 18 h led to significant improvement in alloy organization, dissolution of coarse second phase, and enhanced machining and deformation capabilities. Additionally, two-stage aging resulted in a more uniform distribution of precipitated phases, increased density, and the predominant precipitated phase being the reinforced phase S phase (Al₂CuMg). The hardness test and tensile test were conducted, revealing that the alloy achieved 142.1 HV in hardness, 494.4 MPa in tensile strength, and 19.7% in elongation after undergoing a double-stage aging treatment at 110 °C/2 h + 170 °C/8 h. The mechanical properties of the alloy saw significant enhancement as a result. Moreover, corrosion testing revealed that the corrosion resistance of the alloy was significantly improved following the double-stage aging treatment at 110 °C for 2 h and 200 °C for 8 h, resulting in an intergranular corrosion depth of only 101.26 μm, a corrosion potential of − 0.746 V, and a corrosion current density of 4.71 × 10⁻⁶ A cm². Overall, the double-stage aging treatment effectively improved both the mechanical properties and corrosion resistance of the 2024 aluminum alloy.