Effect of refining slag on non-metallic inclusions in high manganese steel

      In order to research the effect of refining slag on non-metallic inclusions in high manganese steel,the effect of the MgO-SiO2-

Al2O3-CaO refining slag on non-metallic inclusions in the Fe-xMn high manganese steel(x=10%,20%)was studied by slag/steel 

equilibrium experiments.The results show that there are two types of inclusions in the high manganese steel without top slag,MnO 

and MnO-Al2O3.After the addition of the refining slag,the inclusions transformed to three main types,which were MnO,MnO-SiO2 

and MnO-Al2O3-MgO.Among them,the MnO-SiO2 type shares the majority of the total inclusions.According to the result analyzed 

by the ASPEX scanning electron microscopy,the main component of inclusions in the master high manganese steel is MnO,with 

the mass percent above 95%,and the mass percent of Al2O3 about 4%.After reacting with the refining slag,the mass percent of 

MnO in the inclusions decreases,while that of SiO2 and MgO increases,especially SiO2 increases significantly.The hermodynamic 

calculation results show that the Gibbs free energy change of both reactions(4[Al]+3(SiO2)=2(Al2O3)+3[Si]and 2[Mn]+

(SiO2)=2(MnO)+[Si])between the slag and the molten steel is much less than zero.It indicates that under present experimental 

conditions,SiO2 in the slag can be reduced by[Al]and[Mn]in the molten steel to supply[Si],which then reacts with[O]in the molten 

steel,leading the SiO2 content in the inclusions.