Effects of hot rolling and heat treatment on the microstructure, mechanical and corrosion properties of Al-xCu-0.5Mg-0.7Si alloy

Abstract

This study systematically investigates the synergistic effects of microalloying, hot rolling processing, and heat treatment on the microstructural evolution, mechanical properties, and corrosion behavior of Al-xCu-0.5Mg-0.7Si (x = 0.5, 1.5, 2.5 wt%) alloys. The results demonstrate that copper content significantly affects the precipitation behavior and phase distribution of the alloys. Increasing the copper content from 0.5 to 2.5 wt% results in a marked increase in the volume fraction of the second phase, which enhances mechanical strength but compromises corrosion resistance. Hot rolling not only refines the grain structure but also promotes directional alignment of the second phases, leading to a 22.9 % improvement in tensile strength. Subsequent T6 heat treatment induces the formation of fine, uniformly distributed Al₂Cu strengthening phases, further enhancing the mechanical properties of the alloy. Notably, the optimized Al-2.5Cu-0.5Mg-0.7Si alloy, after combined hot rolling and T6 treatment, exhibits exceptional mechanical performance with a yield strength of 293.3 MPa, ultimate tensile strength of 366 MPa, Vickers hardness of 522.3 HV, and elongation of 24.4 %. Additionally, its electrochemical corrosion rate is as low as 0.043 mm/y.