Local Induction Melting Combined with Ultrasonic Melt Treatment: A Pilot Study on Porosity, Mechanical Properties, and Energy Efficiency in AlSi12 Castings

Light metal foundries consume large amounts of energy and rely mainly on gas-fired melting, which is inefficient and promotes porosity caused by dissolved hydrogen. This pilot study examines local induction melting combined with ultrasonic melt treatment (UST) as a decentralized and electrified alternative. AlSi12 was cast with varied mold temperature, casting temperature, UST duration and remelted fraction. Porosity was characterized by optical microscopy in 2D and, for a subset of specimens, by X-ray computed tomography in 3D, and the mechanical behavior by tensile testing. An experimentally benchmarked simulation was used to estimate the energy demand for larger batch sizes. Including the energy required for cooling, the measured laboratory efficiency was 7.9% to 14.9%, and the simulation predicts 41.3% for 100 kg, or 48% with a preheated crucible, against 53.1% derived for industrial induction furnaces. Specimens treated with UST showed a lower mean porosity, 0.56% against 2.14% in optical microscopy and 0.153% against 0.367% in computed tomography, where the pore count was 73% lower at almost unchanged pore size. Their mean strain at fracture was 45.5% higher and their mean toughness 53.2% higher, whereas the 4.4% higher mean tensile strength lies within the scatter of the measurements.