This diploma thesis investigated the response of the EN AW-7049A aluminum alloy during hot deformation. The specimens were produced from extruded material. The aim of the work was to determine how deformation temperature and strain rate affect the flow stress and to determine conditions for further hot-working processes, mainly forging. The chemical composition was obtained from the analysis of the investigated batch, while the thermal behavior of the alloy was examined by differential scanning calorimetry (DSC).
Compression tests were carried out on a Gleeble 3500P thermomechanical simulator at deformation temperatures of 300, 350, 400, and 450 °C and strain rates of 0.01, 0.1, 1, and 10 s⁻¹. A total of 16 compression tests were performed using different combinations of deformation temperature and strain rate. Cylindrical specimens with a diameter of 10 mm and a height of 15 mm were used. The specimens were heated at a rate of 3 °C/s, held at the selected temperature for 180 s, and then deformed to a final absolute true strain of |ε| = 1. The results showed that the flow stress decreased with increasing temperature and increased with increasing strain rate. The highest absolute value of true stress was approximately 184 MPa at a deformation temperature of 300 °C and a strain rate of 10 s⁻¹, while the lowest was approximately 36 MPa at 450 °C and 0.01 s⁻¹. For further hot-working processes, such as forging, it would be reasonable to investigate deformation temperatures between 400 and 450 °C and strain rates from 0.1 to 1 s⁻¹. The flow curves were not corrected for friction at the tool–specimen interface and the resulting barreling of the specimens, or for heat generated during deformation and the resulting deformation heating. Therefore, they were used mainly for comparison of the individual thermomechanical conditions.
|
