LFEC and LFEVC of AZ80 magnesium alloy

The effects of a low frequency electromagnetic field and a low frequency electromagnetic vibration field applied during DC casting of AZ80 Mg on microstructures and alloying element distribution in ingots were investigated.The experiments were performed both in absence and in the presence of the magnetic fields.In DC casting,the ingot exhibited coarse microstructure and severe segregation of Al.In the presence of solo low frequency alternating magnetic field,namely LFEC,the grains of the ingot was effectively refined and the segregation of Al was significantly decreased.In LFEVC,namely low frequency electromagnetic vibration casting,the ingot were significantly refined and the segregation was suppressed.With increasing the vibration intensities,the grain refinement and segregation suppression were increased.

Solidification of Al alloys under electromagnetic field

New theories and technology in the electromagnetic field were put forward about DC casting of Al alloys, including the fundamental research works, i.e, effects of the electromagnetic field on solidus and liquidus, macrosegregation of the main alloying elements, microstructures, content of alloying elements in grains and grain size after solidification under electromagnetic field, and also including a new process DC casting under low frequency electromagnetic field(LFEMC), which can refine microstructure, eliminate macrosegregation, increase the content of alloying elements within grains, decrease the residual stress, avoid cracks and improve surface quality, and another new process DC casting under low frequency electromagnetic vibration(LFEVC), which is a high effective method for grain refining.

Parametric Modeling of Electromagnetically Induced Vibration Processes Occurring Within Induction Systems

A continuum based model is presented which identifies a favorable set of operational conditions whereby an effective and efficient electromagnetically induced vibratory motion can proceed within an induction system.Specifically, an analytical assessment is presented for the electromagnetic field and the electromagnetically induced acoustic field, with parametric factors incorporated into the model to permit a normal modes solution for the acoustic field which here is sensitive to the compliance of both the molten metal and the wall,as well as electromagnetic properties of the metal.A parametric analysis is presented which identifies the importance of matching the mechanical impedances of the melt-wall configuration so that the generation of acoustic energy within the melt system can be more effectively utilized.Relatively straight-forward calculations,presented for the acoustic field,may provide a more computationally efficient means for implementing process simulation studies for these systems.

Quasi-Steady Vibratory Motion Within an Inductively Heated Cylindrically-Shaped Liquid Volume

The motion of an inductively heated fluid volume of cylindrical shape is assessed based on time dependent oscillatory components of the Lorentz force.The applications considered include vibratory motion in a channel induction furnace and vibratory motion in an electromagnetically excited direct chill casting.The governing equations for the resulting magnetoacoustic problem are presented with the acoustic field solutions expressed in terms of normal modes. Closed form expressions are developed for the velocity,pressure and phase relationships between the excitation and the response.Calculations are prescribed for the pressure in both the channel furnace and the direct chill casting,with the calculational results from the casting application suggesting that,roughly,a two-fold increase in the effective peak acoustic pressure can be achieved by superimposing on the AC electromagnetic field a DC magnetic field of strength sufficient to match the peak alternating magnetic field.A procedure is also outlined for developing field descriptions of the velocity and pressure which can be effected in a MATLAB environ.