Effect of Nonisothermal Annealing on Microstructure and Mechanical Properties of Al–Mg Alloy

The impact of nonisothermal annealing on the microstructure and mechanical properties of continuously cast and rolled Al–Mg alloys is investigated. The microstructure and mechanical properties of the alloy after nonisothermal annealing at 360, 380, and 400 °C are compared with those of isothermally annealed samples at the same temperatures. The analysis encompasses the quantity and size of precipitates, dislocation density, microstructure, and mechanical properties of the annealed alloy. The results show that the nonisothermal annealing involved in the experiments enhances the resistance of the alloys to annealing softening, and the nonisothermal annealed alloys are significantly stronger compared to the isothermally annealed alloys. Peak tensile strength (317.88 ± 1.19 MPa) and peak hardness (81.3 HV) are observed at 380 °C. Transmission electron microscopy (TEM) identifies the primary precipitates as β‐Al 3 Mg 2 , Mg 5 Si 6 , and Al 6 (Fe Mn). Quantitative analysis reveals that nonisothermal annealing promotes the formation of more finely dispersed precipitates. The alloy's enhanced strength can be attributed to the combined effects of dispersion strengthening, grain refinement, and dislocation strengthening. This study holds significant implications for improving the annealing process of Al–Mg alloys.