Comprehensive optimization of thermo-mechanical processing for AA2024 alloy: Influence on tensile strength, ductility, hardness, and microstructure

This study investigates the optimization of thermo-mechanical processing parameters for AA2024 aluminum alloy, focusing on their effects on elongation at fracture, microhardness, and grain size. The Box-Behnken Design (BBD) was employed to systematically analyze the influence of cold deformation degree, annealing temperature, and holding time on these mechanical and microstructural properties. To validate the newly developed models for elongation, hardness, and grain size, the experimental condition was set to correspond to the condition yielding the maximum ultimate tensile strength (60% cold deformation, 460°C annealing, and 10 min holding time). Regression models were developed and demonstrated high predictive accuracy, with deviations between experimental and predicted values remaining below 5%. Additionally, an alternative processing condition (58.9% cold deformation, 460°C annealing, 18 min holding time) was identified through a multi-objective optimization approach to maximize elongation, minimize grain size, and achieve a target microhardness, with a predicted ultimate tensile strength of 598.5 MPa. These findings provide valuable guidelines for tailoring thermo-mechanical treatments of AA2024, ensuring an optimal balance between strength, ductility, and microstructure refinement for aerospace and structural applications.