9th ECCC European Continuous Casting Conference – ECCC 2017

As grain refinement can bring the substantial improvement of mechanical properties of as-cast and further rolled materials by reduction of segregation during solidification. Many studies, therefore, have been reported on grain refinement of as-cast structure by formation of inclusions based on so-called Oxide Metallurgy. However, there are also many problems in Oxide Metallurgy in terms of process controlling: Steel making process should be overloaded by increase of overheat in steel melt, the applicable steel grades are limited, and there exists a high possibility of nozzle clogging. In order to overcome these limitations, in this work, inoculant alloys were directly injected in molten steel in lab scale. It should be emphasized that any kinds of diverse inclusions could be utilized as the candidate of inoculants by direct inoculation method. Inoculant alloys were prepared by mechanically alloying steel powders with inoculants which have lower disregistry (lattice misfit parameter) with each other, followed by heat treatment and rolling in order to remove moisture and holes inside. The experiment was carried out by using 1kg-scale solidification simulator. Then, solidified as-cast steels were analyzed by using various kinds of analyzing devices in order to verify the grain refinement effect. It was observed by SEM-EDS that various kinds of inclusions were made. Also, the effectiveness of refiners was confirmed by EBSD and OM.