Modeling of non-stationary solidification processes of the modified metal during induction heating

Abstract

Numerical simulation of thermophysical processes is carried out when the surface layer of a two-component metal (Fe-C) substrate is modified by refractory nanoscale particles when heated by a moving inductor in a non- stationary three-dimensional setting. Heating and melting of metal occurs when an induction high-frequency electromagnetic field (1200 kHz) is applied to its surface through a rectangular area. The distribution of electromagnetic energy on the surface of the substrate is uniform, and inside it is described by empirical formulas. We postulate in the model that the metal nanoscale particles are uniformly distributed in the melt. The boundary of the melting region is determined in the Stefan approximation, and the boundaries of the solidification region are defined according to Kolmogorov's theory of metal crystallization. The growth of the solid phase occurs on the surface of nanoparticles when the melt is undercooled. The model of non-equilibrium crystallization of the basic component of the alloy includes accounting for the dependence of the liquidus temperature on the concentration of dissolved carbon in the melt up to the eutectic point according to the non-equilibrium lever rule. In the simulation process, the temperature field distributions close to quasi-stationary, the size of the melting and crystallization zones, the kinetics of solid phase growth, and the change in the concentration of the alloying component in the solidifying metal were determined, consistent with the value of undercooling of the melt in the two-phase zone. The influence of the initial temperature of the substrate material on the shape of the molten pool and crystallization zones is considered. It is shown that an increase in the initial temperature of the substrate, which leads to a decrease in temperature gradients in the processing zone and, as a result, to a slowdown in the crystallization process, can serve as one of the ways to regulate the structure of the surface layer.