Optimization of Heat Treatment Parameters Based on Microstructure and Mechanical Properties of Direct Thixoforging 2A14 Aluminum Alloy

The standard heat treatment process was suitable for aluminum alloy parts formed by solid forging process, but not for parts formed by thixoforging process. In order to strengthen the mechanical properties via heat treatment of the thixoforged parts, a low temperature and longtime solution treatment method was proposed. The effects of solution temperature, solution time and aging time on the microstructure and mechanical properties of 2A14 thixoforged parts were studied by single variable method, and the optimal heat treatment process parameters were obtained as solution treatment 48 °C × 8 h + artificial aging treatment 160 °C × 8 h. Under this heat treatment conditions, the optimum mechanical properties of the thixoforged 2A14 alloy parts are achieved by average yield strength of 263.5 MPa, average tensile strength of 376.2 MPa and average elongation at break of 17.9%. The aging enhanced precipitation phases were the coherent θ″ and S″ phases and semi-coherent θ′ and S′ phases at nanometer level, in addition, FeMnSi phase with uniform distribution at submicron level also played a good strengthening effect.