Degassing of molten aluminum A356 alloy using ultrasonic vibration

This article addresses ultrasonic degassing in aluminum A356 alloy. An experimental setup has been built for the degassing of aluminum using ultrasonic vibration at a frequency of 20 kHz and vibration intensities up to 1500 W. Ultrasonic degassing has been tested in different volumes of aluminum melt for various processing temperatures and durations. The efficiency of degassing is evaluated by a density measurement for reduced pressure samples. Experimental results indicate that a steady-state hydrogen concentration can be obtained within a few minutes of ultrasonic vibration, regardless of the initial hydrogen concentration in the melt. The dynamics of hydrogen evolution as a function of processing time, melt temperature, and initial hydrogen concentration have been investigated. The mechanism of ultrasonic degassing is discussed. It is suggested that ultrasonic vibration can be used to reduce porosity formation in aluminum alloys. Published by Elsevier B.V