Effect of Mn Content on the Reaction between Fe-xMn (x = 5, 10, 15, and 20 Mass pct) Steel and CaO-SiO2-Al2O3-MgO Slag

Abstract

Medium- and high-Mn steels have excellent properties but are very difficult to be commercially produced because of the high content of some alloy elements. To enhance the understanding of the reaction between medium/high-Mn steel and refining slag which is significantly different from the conventional steels, steel and slag composition and the inclusions were investigated by equilibrium reaction between Fe-xMn (x = 5, 10, 15, and 20 mass pct) and CaO-SiO2-Al2O3-MgO top slag at 1873 K in the laboratory. Furthermore, the effect of Mn content on inclusion transformation and steel cleanliness was also explored. After slag–steel reaction, both contents of MnO in slag and Si in steel increased. Most MnO inclusions in master steel transformed to MnO-SiO2 and MnO-Al2O3-MgO. With the increase in Mn content, the amount share of MnO type inclusions decreased and that of MnO-Al2O3-MgO type increased. In addition, both the number density of observed inclusions and the calculated oxygen content in inclusions increased. Thermodynamic analysis indicates that the composition change of steel and slag and the transformation of inclusions are mainly the consequence of the reaction between Mn in molten steel and SiO2 and MgO in top slag. The dissolved Mn in medium/high-Mn steel presents a strong reactivity.

Effect of Manganese on the Formation Mechanism of Nonmetallic Inclusions in Fe–xMn–7Al–0.7C Lightweight Steel

“…However, few researchers have been able to draw on any systematic research into the Mn content in the Fe–Mn–Al–C steels. [ 14,18–21 ] So far, very little attention has been paid to how Mn content affects inclusions formation and growth in Fe–Mn–Al–C steels, especially under high aluminum content. Park et al [ 14 ] studied the formation of inclusions in Fe–(10–20)Mn–(1–6)Al steels and found that the Mn content increased from 10% to 20%, Al 2 O 3 , MnAl 2 O 4 , oxide core with MnS, and MnS with AlON inclusions increased.…”

“…In addition, thermodynamic calculations pointed out that the AlN‐containing inclusions, during the cooling and solidification of the steel, are formed. Under the condition of top slag, Yu et al [ 20 ] investigated the effect of CaO–SiO 2 –Al 2 O 3 –MgO slag on the solute elements and inclusions in Fe– x Mn ( x = 10 and 20 wt%) steel. It was observed that large‐sized inclusions decreased and steel cleanliness improved greatly after CaO–SiO 2 –Al 2 O 3 –MgO slag was added, under aluminum‐free conditions.…”