Effect of MgO in low-basicity refining slag on properties of MnO-SiO2-Al2O3 inclusions in tire cord steel

Large-scale non-deformation inclusions in tire cord steel increase the breakage risk, and the Si-Mn deoxidization is used to control the inclusion composition in the plasticized region with a lower melting point. In order to study the influence of the composition change of refining slag due to the erosion at the slag line on the inclusions of MnO-SiO2 system with the low melting point, the silicon-manganese oxide inclusions were synthesized, and steel samples were prepared according to the composition of 82B tire cord steel. No top slag trial and the top slag trials of low basicity refining slag with 0 %, 5 %, 10 % and 20 % MgO content were studied in the MgO crucible at 1600 degrees C (CaO%/SiO2%=1, Al2O3=3%). The properties of typical inclusions in steel were observed using SEM-EDS and automatic statistical. Results showed that [Mg] dissolved by MgO crucible into molten steel in the no-slag test is insufficient to produce Mg-containing inclusions, and MgO-SiO2 inclusions appear in the top slag trials. In general, the MgO content in the top slag has little effect on the silicon manganese oxide inclusions. The top refining slag trial with 0%MgO content indicated that the slag dissolved MgO from the crucible. Appropriate increase of MgO content in refining process is conducive to reducing the corrosion of slag line and extending the service life of MgO-C brick.

Automated summary

Large-scale non-deformation inclusions in tire cord steel increase the breakage risk. Silicon-manganese deoxidation is used to control the inclusion composition in the plasticized region with a lower melting point. The influence of composition change in refining slag on low melting point MnO-SiO2 system inclusions was studied. Experimental results showed that the MgO content in the top slag has little effect on the silicon-manganese oxide inclusions.