Improving the Technology of Smelting and Out-of-Furnace Processing of Specialized Converter Steels for the Production of Grinding Balls

The processes and mechanisms of forming the metallurgical quality of grinding balls and their operational characteristics have been studied depending on the parameters of the production of specialized steels in the conditions of oxygen converter production of JSC EVRAZ United West Siberian Metallurgical Combine. The main reasons for the unsatisfactory impact resistance of grinding balls made of steel grades Sh2.1 and Sh2.3 are the presenceof defects of steelmaking origin (floccules, accumulations of non-metallic inclusions, internal discontinuities (pores) and developed chemical heterogeneity). It was determined that a great influence on increasing the impact resistance of grinding balls is exerted by a decrease in the oxygen content in the metal at the outlet into the bucket, a decrease in the sulfur and hydrogen content in the steel after bucket treatment, as well as an increase in the duration of steel purging with inert gas during out-of-furnace treatment on the bucket-furnace unit. The total relative degree of influence of the grinding balls considered for rejection during impact resistance tests is 73 %. Based on the obtained patterns for the conditions of the enterprise under consideration, recommendations have been developed to improve the technological modes of smelting and out-of-furnace processing of steels for the production of grinding balls, the use of which in practice has confirmed their effectiveness. A decrease in the rejection of grinding balls from steel grades Sh2.1 and Sh2.3 during drilling tests was recorded by an average of 3 % due to a decrease in defect formation in the initial continuously cast billets.