Manufacture of High-Nitrogen Corrosion-Resistant Steel by an Aluminothermic Method in a High-Pressure Nitrogen Atmosphere

The conditions of aluminothermic synthesis of high-nitrogen Cr-N and Cr-Mn-N steels in a high-pressure nitrogen atmosphere are studied by thermodynamic simulation and metallurgical experiments. Thermodynamic analysis shows that the aluminothermic reduction reactions are incomplete. The most important synthesis parameter is the ratio of the aluminum to the oxygen content in a charge, and its optimum value ensures a compromise between the degree of oxide reduction, the aluminum and oxygen contents in steel (degree of deoxidation), and steel contamination by aluminum nitride. An analysis of experimental heats demonstrates good agreement between the experimental results and the data calculated by a thermodynamic model. As-cast ingots have the structure of nitrogen pearlite, and quenched ingots have an austenitic structure.