Effect of direct alloying of manganese ore–cored wires on the composition and quality of molten steel

Abstract

This research involved investigating the effects of different manganese ore addition methods on the quality of molten steel. From the thermodynamic point of view, when carbon powder, an aluminium block, silicon carbide, ferrosilicon and other reducing agents were added during the refining process, the manganese yield substantially increased at 1550 °C; the reduction abilities of the involved reducing agents were in the following order: aluminium block > silicon > silicon carbide > graphite. For top-slag addition, the mass transfer rate of manganese was lesser in molten steel than in slag, indicating that it was the limiting factor. For nonaluminium deoxidation, the inclusions in high-carbon steel were primarily manganese sulfide (MnS), along with a small amount of silicates. Medium-carbon steel contained small amounts of silicon oxide, magnesium oxide and alumina. In aluminium deoxidation, the inclusions in the involved steel were primarily alumina. The average inclusion size for cored-wire alloying with ferrosilicon as the reducing agent was 2.10 μm, with the inclusion density and manganese yield being 0.10/μm 2 and 93.46%, respectively. This alloying process was found to be optimal for direct alloying of manganese ore.