Study of the Melting Time of Complex Nickel-Containing Ferroalloys in Liquid Steel

To develop new ferroalloys of a rational composition, data on their physical and chemical characteristics are needed. One of the main characteristics of the alloy, on which the assimilation and distribution of the main elements of ferroalloys in the iron-carbon melt depends, is the duration of its melting. The melting time of complex nickel-containing ferroalloys in liquid steel has been studied using a mathematical model for calculating the melting time developed by researchers from Ural Federal University and Institute of Metallurgy of the Ural branch of the Russian Academy of Sciences. The program allows one to calculate the temperature of a piece of ferroalloy, the thickness of the steel crust being frozen, the size of the piece of alloy and the duration of melting periods depending on the physicochemical and thermalphysic characteristics of ferroalloys. The melting mechanism of ferroalloys determines the time of their melting in liquid steel. Mathematical modeling of the melting of complex nickel ferroalloys containing 10% Ni; 0.5–55.0% Cr; 0.2% C; and 0.2% Si in an iron-carbon melt is performed. It has been established that all the alloys under consideration belong to the group of low-melting ferroalloys and the process of their melting proceeds in three periods. With an increase in the initial size of a piece of ferroalloy from 3 to 100 mm, the melting time increases by a factor of 250–300. It is shown that an increase in the chromium content in the composition of the complex alloy to 37% leads to a decrease in the melting time, and with its further increase to 55%, an increase in the melting time occurs. A decrease in the temperature of the liquid steel bath from 1700 to 1520°C is accompanied by an increase in the duration of melting of complex ferroalloys by 7–8 times. In general, the considered complex nickel ferroalloys are characterized by a much faster melting process in liquid steel compared to standard ferrochromium and ferronickel.