Introduction of innovations in steel smelting for critical castings of freight wagon bogies in order to increase their operational reliability

Abstract

This work is devoted to improving the technological process of the recovery period for melting steel 20GFL with the purpose of increasing the efficiency of metal refining, KCV–60, operational reliability of critical railway castings, and reducing the cost of steel. The advantages of the steel diffusive deoxidation technological process using a dispersed aluminum-containing deoxidizer (RDA) in the production of critical railroad castings have been investigated and revealed. The benefits of steel smelting in an electric arc furnace (EAF 6) were applied to the process. This made it possible to achieve higher steel quality, and improve energy and resource consumption during the technological processes of smelting and casting. The use of the RDA made it possible to effectively deoxidize the metal, increase and stabilize the impact toughness of steel with a sharp notch at negative temperatures, and also reduced the cost of castings. The treatment of steel with the invented deoxidizing mixture made it possible to dramatically increase the efficiency of steel deoxidation compared to other traditional mixtures. The increase is explained by a significantly higher number of reacting particles’ active centers and an increased interphase in the system. The increase in the systems’ interface was caused by the process of stirring slags, which, in turn, was created by the dissociation of carbonates included in the RDA. The average sulfur content during deoxidation with RDA decreased by 23 %, i.e., to 0.0110 % versus 0.0143 % when a regular factory mixture was used. After the treatment of steel with the RDA, the produced casting’s microstructure became more beneficial as well. The pollution index decreased, on average, from 1.853 to 1.472·10–3. The KCV–60 increased by 3 % on average and significantly stabilized, which is vital for the technological process. The uniformity of the KCV–60 has also increased. The coefficient of variation was 32% before the process implementation, whereas it was 14 % after the implementation. The new technological process was introduced at the Rubtsovsk branch of Altayvagon JSC with the economic effect of over 6 million rubles.