Effect of MgO on crystallization behavior of MnO-SiO2-Al2O3 based inclusions in tire cord steel

Increasingly MgO content in refining slag and molten steel is the major cause of corrosion of refractory materials at slag line during the refining process of Si-Mn deoxidized tire cord steel, the effects on the crystallization behavior of typical MnO-SiO2-Al2O3 based inclusions in tire cord steel were studied. The relation between the formation of high melting point and high hardness inclusions (Al2O3, 3Al2O3 center dot 2SiO2, MgO center dot Al2O3 and 2MgO center dot SiO2) with MnO-SiO2-Al2O3-(0wt.%, 4wt.%, 8wt.%, 12wt.%, 16wt.%) MgO system was verified by ICP, XRD, SEM-EDS and FactSage 8.0. The results indicated that the crystallization temperature of MnO-SiO2-Al2O3 system increases with the increase of MgO content. MgxMn(2-x)SiO4(1 < x < 2) solid solution is the main crystalline phase due to isomorphism. Only a small amount of 2MgO center dot SiO2 which is not enough to cause wire breakage was formed in the trial with the highest MgO content (16wt.%) after the low melting point MnO-SiO2-Al2O3 composition added different MgO content and the other three kinds of inclusions were not produced in the five trials.