Ultrasonic Evaluation of the Quality of A356.2 Alloy by Fluxing Treatment

Abstract

Aluminum alloys are often contaminated with non-metallic inclusion particles that react easily with oxygen or moisture, oxidizing to form oxide films. These inclusions and oxides can lead to the formation of porosity as well as significantly reduce the corrosion resistance and mechanical properties of aluminum alloy castings. Fluxing treatment is one of the conventional methods for removing inclusions and oxides from the melt to enhance the quality of aluminum alloy castings.
In this study, we use four covering fluxes in fluxing treatments and investigate the quality of A356.2 alloy. The percentage of porosity is an accepted way to quantitatively evaluate the quality of aluminum alloy castings. In this study, the relative porosity, as represented by the percentage of porosity in A356.2 alloy is evaluated. Nondestructive ultrasonic techniques are adopted to investigate the relative porosity of A356.2 alloy samples produced by the various flux treatments. The relationship between the relative porosity and ultrasonic characteristics, including the ultrasonic velocity and the attenuation coefficient, are determined and compared, and the pore formation and oxide film distribution in the alloy are also discussed.