EXPERIENCE IN OBTAINING AND USING SHS LIGATURES BASED ON CHROMIUM NITRIDES FOR SMELTING STAINLESS STEEL

A brief overview of the current global production of stainless steels is provided. It is shown that in China, the leading producer of stainless steel, the share of nitrogen-containing stainless metal smelting in 2023 exceeded 30% and amounted to 11.5 million tons. For alloying such metal with nitrogen, chromium nitride-based ligatures are in demand – nitrided metallic chromium and nitrided ferrochrome. This paper presents the experience of obtaining low-carbon chromium-based ligatures with an increased nitrogen content using the SHS method. The design of a special flow-through SHS reactor is proposed and a technology for nitriding aluminothermic chromium and ferrochrome powders with a particle size of up to 400 μm in a reacting gas flow is developed. As a result of the experimental studies, the fundamental possibility of their nitriding in the co-combustion mode was established and the dependences of the combustion rate and nitrogen content in the synthesis products on the pressure and flow rate of the reacting gas were revealed. Tests of the synthesized high-nitrogen ferrochrome were conducted during the experimental smelting of duplex steel UNS S32750 (Super Duplex 25Cr) under the conditions of the Zlatoust Metallurgical Plant. The results of the pilot industrial smelting of the metal showed that the developed alloying material provides a stable nitrogen concentration in the metal, within 0.28–0.30 mass %, with the actual nitrogen absorption by the steel melt of 82–86%.

self-propagating high-temperature synthesis (SHS), stainless nitrogen-containing steel, chromium nitride-based master alloys, combustion synthesis, nitrided ferrochrome, flow-through SHS reactor, synthesis products, duplex steel