Ultrasonic Treatment of Melt Metals

Ultrasonic Treatment of Melt Metals

Power ultrasonic treatment of melt metals involves applying ultrasonic vibrations to the melt during or before solidification to control its microstructure and properties. Compared to traditional inoculation modification techniques, this method controls and refines the solidified microstructure. It avoids environmental and material contamination, making it an effective method for obtaining castings with excellent microstructure and properties, and a key approach to unlocking the potential of high-tech materials.

Ultrasonic cavitation leads to the uniform wetting of non-metallic impurities in the melt. These impurities become nucleation sites, the starting point of solidification. Because these nucleation sites occur before the solidification front, dendritic growth is not triggered. Dendritic fracture: Dendritic melting typically begins at the root due to localized temperature rise and segregation. Ultrasonic treatment (UST) generates intense convection (heat transfer via mass motion) and shock waves in the melt, causing the dendritic structure to fracture. Due to localized temperature and compositional changes, convection can promote dendrite breakage and solute concentration. Cavitation shock waves facilitate the cracking of molten roots.

Degassing is another important function of power ultrasound for liquid and semi-solid metals and alloys. Ultrasonic degassing reduces the porosity of metals, resulting in higher material density in the final metal/alloy product. Ultrasonic degassing of metals improves the ultimate tensile strength and ductility of the material. In terms of effectiveness and processing efficiency, industrial power ultrasound systems outperform other commercial degassing methods. Furthermore, the mold filling process is improved due to the relatively low melt viscosity.

Principle: The ultrasonic metal melt processing system consists of two parts: an ultrasonic vibrating component and an ultrasonic generator. The ultrasonic vibrating component generates ultrasonic vibrations—mainly including an ultrasonic transducer, an ultrasonic amplitude transformer, and a tool head—and transmits this vibrational energy into the molten metal.

The transducer converts the input electrical energy into mechanical energy, i.e., ultrasonic waves. This is manifested by the transducer making a longitudinal reciprocating motion, with an amplitude typically in the range of a few micrometers. Such amplitude power density is insufficient and cannot be used directly. The ultrasonic amplitude transformer amplifies the ultrasonic amplitude according to design requirements, isolates the molten metal from heat transfer, and also serves to fix the entire ultrasonic vibration system. The ultrasonic tool head is connected to the amplitude transformer, which transmits the ultrasonic energy vibration to the tool head, which then emits the ultrasonic energy into the molten metal.

During the cooling or vibration pressing process, the molten metal receives ultrasonic waves, causing significant changes in its crystal grain structure, thereby improving various physical properties of the metal.

Functions: Refines metal grains, homogenizes molten metal and alloy composition, significantly improves the strength and fatigue resistance of casting materials, and enhances the overall performance of materials.

Features: The ultrasonic molten metal treatment system does not change existing production equipment and processes, and is easy to install and operate. The ultrasonic molten metal treatment system can be used for ultrasonic treatment of metals, ultrasonic grain refinement, ultrasonic metal solidification, ultrasonic continuous casting, etc.

Applications: Applied to continuous cooling casting fields such as gravity casting and low-pressure casting of light metals—e.g., aluminum alloy and magnesium alloy plate casting, mold casting, etc.