Ultrasonic processing is known to be an efficient means of aluminium melt degassing and structure modification with additional benefits of being economical and environmentally friendly. This paper reports on the kinetics of ultrasonic degassing and regassing of foundry aluminium alloys and on pilot-scale degassing trials. Efficiency of ultrasonic degassing is compared with conventional Ar rotary degassing. Direct measurements of hydrogen concentration in the melt by Foseco Alspek-H probe are used along with reduced-pressure test. The effects of ultrasonic processing on porosity are studied using 3D X-ray tomography.

Ultrasonic processing is known to be an efficient means of aluminium melt degassing with additional benefits of being economical and environment friendly. This paper describes the performance of ultrasonic degassing in preparing melt for low pressure die casting. Efficiency of ultrasonic degassing is compared with conventional Ar rotary degassing, by direct measurements of hydrogen concentration in the melt with a Foseco Alspek-H probe and by reduced-pressure test in different stages of the casting process. Significant reduction in dross formation along with the similar efficiency of hydrogen degassing was shown for ultrasonic degassing as compared with conventional Ar rotary degassing. The mechanical properties, microstructure and porosity level of components produced by low pressure die casting after both degassing techniques are determined. The results show that the components produced after ultrasonic degassing treatment have similar hardness, tensile properties, porosity level and microstructure as the components degassed with conventional Ar rotary degassing.

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