Research on reaction kinetics between dual-phase steel and refining slag

To investigate the evolution of chemical compositions and inclusions in dual-phase (DP) steel during the secondary refining, the slag/steel kinetics reaction experiments between DP780 and two refining slags, which were the 50% CaO-5% MgO-45% Al 2 O 3 ternary-slag and the 48.5%CaO-4.85%MgO-43.65%Al 2 O 3 -3%SiO 2 quaternary-slag, were carried out in the MgO crucible at 1873 K in the laboratory. The results indicated that the slag/steel reaction was intense within the initial 30 min, resulting in significant variations in chemical compositions of the steel, and the reaction decelerated subsequently. During the slag/steel reaction, the variation trends of steel compositions under both slags were similar. The Al, total O and S contents decreased, while Si and Mg increased. Notably, the variations in Si and Al were more pronounced, while the increase in Mg was smaller in the case of the quaternary-slag. The mass transfer coefficient of Al in the quaternary-slag experiments was higher. The evolution routes of inclusions were slightly different, specifically featuring the later formation and lower fraction of CaO·MgO·Al 2 O 3 inclusions in the quaternary-slag experiments. The above differences under both slags were attributed to the existence of SiO 2 in the quaternary-slag which resulted in a lower reduction potential in system of quaternary-slag compared with the ternary-slag.