Effect of Heating Rates and Solid Solution Time on Microstructure and Properties of Hot-Pressed 7085 Aluminum Alloy

The present study aimed to investigate the effects of heating rates and solid solution time on the microstructure and properties of hot-pressed 7085 aluminum alloy This was achieved through various tests, including metallographic analysis, hardness and conductivity tests, X-ray diffraction (XRD) analysis, electron backscatter diffraction (EBSD) scanning test, and corrosion test. The results revealed that the tensile strength of the alloy was enhanced by a slow heating rate (3.6°C/h) and a short holding time (470°C × 2 h) during the solution treatment, up to the maximum tensile strength of 585.74 MPa. On the other hand, rapid heating rate (180°C/h) and short holding time (470°C × 2 h) increased the elongation of the alloy, with a maximum value of 16.94%. This increase in elongation can be attributed to the occurrence of recovery during the slow heating rate, which transformed numerous dislocations into low-angle grain boundaries, thereby strengthening the effect of dislocations and low-angle grain boundaries. Besides, an increase in holding time resulted in increased recrystallization of the alloy, which weakened the dislocation and low-angle grain boundary strengthening. Furthermore, the study found that the heating rate and solution time did not have a significant impact on the hardness and electrical conductivity of the alloy. The maximum intergranular corrosion depth recorded was 86.72 mm, and the corrosion resistance of the alloy was improved through a solution treatment involving the rapid heating rate and long-time holding. Finally, the study observed that the exfoliation corrosion resistance of the alloys after different solution treatments was similar, with all being rated as P grade.