The inluence of processing variables on the ultrasonic degassing of molten AlSi9Cu3 aluminium alloy

Abstract

The effect of high intensity ultrasound on the degassing of AlSi9Cu3 alloy using the novelMMM(Multi-frequency Multimode Modulated) technology was studied. Different ultrasonic parameters (power and frequency), melt temperature and processing times were tested and their influence on the degassing efficiency evaluated. RPT (Reduced Pressure Test) was used to evaluate the hydrogen content in the alloys and the samples porosity level and density. For the experimental conditions used in this research, it was found that ultrasonic frequency has no influence on the hydrogen removal rate that, in turn, strongly depends on the ultrasonic power, the processing time and the melt temperature. The experimental results suggest that the MMM ultrasonic technology is an important improvement to the fixed-frequency ultrasonic systems by significantly decreasing the processing time to achieve a quasi-equilibrium hydrogen concentration in aluminium melts