Deoxidation capacity of aluminum in ferromanganese carbon-containing melts

Deoxidation (reduction of oxygen concentration dissolved in liquid metal) is an integral part of steel production technology. For obtaining deeply deoxidized metal, mainly aluminum is used at metallurgical enterprises. It should be taken into account that alloying elements of steels and alloys under certain conditions can act as deoxidizing elements, contributing to the complex nature of the deoxidation process. Almost all steels contain manganese in one concentration or another. The study of interaction processes in the Fe – Mn – Al – O – C system at steelmaking temperatures is of applied importance. In this paper, a thermodynamic analysis of the deoxidation ability of aluminum in oxygen-containing iron-manganese melts was carried out. At the same time, influence of carbon on course of the deoxidation process was taken into account. In the study, it is effective to use a technique for constructing the solubility surface of components in metal (SSCM) – a diagram that connects the compositions of liquid metal with the compositions of conjugated non-metallic phases. In the course of this work, oxygen solubility isotherms in the Fe – Mn – O system were calculated for the temperature range of 1550 – 1650 °C. For the Fe – Mn – Al – O – C (1600 °C) system, composite sections of the SSCM were constructed at fixed carbon concentrations in steel [C] = 0; 0.1; 0.4; 0.8 and 1.2 % (hereafter by weight). It is shown that with the simultaneous presence of manganese and aluminum in an oxygen–containing iron-based melt (at industrially significant concentrations [Al] = 0.001 – 0.010 % and [Mn] – less than 1.0 %), aluminum in the liquid metal will act as a deoxidizing agent, and corundum inclusions will be formed as interaction products. Complex deoxidation by aluminum and manganese with the formation of spinel is typical only for manganese-alloyed steels, where the concentration of manganese is more than 1.5 %.