Shchukin V.G.   Popov V.N.  

Numerical investigation of melting and solidification processes in modified surface layers of metal at induction heating

Reporter: Shchukin V.G.

One of the perspective ways to improve the operational properties of parts of machines during induction treatment of their surfaces is the modification of the melt by specially prepared nanoscale particles of refractory compounds (carbides, nitrides, carbonitrides, etc.). This approach allows us to increase the number of crystallization centers and to grind the structural components of the solidified metal, and the resulting high dispersity and homogeneity of crystalline grains favorably affect the quality of the treated surfaces.
    3D numerical simulation of thermophysical processes in the modification of the surface layer of metal in a moving substrate was carried out. It is assumed that the surface of the substrate is covered with a layer of specially prepared nanoscale particles of the refractory compound, which, penetrating into the melt, are uniformly distributed in it. The possibility of applying a high-frequency electromagnetic field of high power for heating and melting a metal (iron) for the purpose of its subsequent modification is investigated. The distribution of electromagnetic energy in a metal is described by empirical formulas. Melting of the metal is considered in the Stefan approximation, and upon solidification it is assumed that all nanoparticles serve as centers for volume-sequential crystallization.
     Calculations were carried out with the following parameters: specific power p0= 35 and 40
kW/cm2 at a frequency f = 440 and 1200 kHz, substrate velocity V = 0.5-2.5 cm/s, nanoparticle concentration Np = 2.0·109 cm-3. Based on the results obtained in a quasi-stationary formulation, the distribution of the temperature field, the dimensions of the melting and crystallization zones, the change in the solid fraction in the two-phase zone, the area of the treated substrate surface, depending on the speed of its movement and induction heating characteristics were estimated.

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