Ultrasonic vibrations prior to high pressure die-casting of AA7075
Haghayeghi, A. Heydari, P. Kapranos, “Ultrasonic vibrations prior to high pressure die-casting of AA7075”, Vol.153, 2015, PP.175-178.
The effects of introducing ultrasonic vibrations prior to high pressure die casting have been experimentally investigated. Results suggest reductions of up to 73% in grain size and up to 5% on porosity levels due to cavitation, leading to enhanced structural performance. The typical values of ultimate tensile stress and yield stress increased respectively to 590MPa and 502MPa and elongation improved to 18%. Wetting of the oxides by the collapse of cavitation bubbles along with enhanced degassing appears to be the responsible mechanisms for these property improvements. The effect of relaxation after ultrasonic vibrations examined and results indicates light grain size increase from 68 to 80 µm. Proving ultrasonic treatment above liquidus appears to be a stable phenomenon where its effects remaining active for a considerable time, making the process feasible for industrial scale applications