Mechanical Properties and Post-forming Microstructure/Properties of 6082 Aluminum Alloy Subjected to Pre-hardening Forming Process

This study focused on investigating the pre-hardening forming (PHF) process, which consists of the following stages: solution treatment, pre-forging, quenching, pre-aging, and final forging. The PHF process combines solution heat treatment and hot forging compared with the conventional forging process. The compression test and finite element simulation of the control arm were evaluated. Based on this, the control arm was successfully tried out, and the mechanical properties and microstructure of the formed parts were carried out. The results show that control arm using the PHF process has good formability, specifically pre-aging at 160 °C for 4 h followed by final forging at 200 °C, resulted in a hardness of 131 HV, surpassing the conventional forging hardness of 114 HV. Additionally, the tensile strength and yield strength were measured as 352 MPa and 331 MPa, respectively, which were higher compared to the conventional forging values of 336 MPa and 312 MPa. At 160 °C for 4 h followed by final forging at 200 °C, the dislocation density in the final forging increased by 165% compared to the pre-aging stage. Furthermore, a dense β″ phase precipitated after pre-aging, indicating that the primary strengthening mechanism of the final forging was dislocation strengthening induced by work hardening.