Effect of Rare Earth on the Occurrence Characteristics of Inclusions in High-strength Wheel Steel
The effects of rare earth on the type and size distribution of inclusions in high-strength wheel steel were investi-gated by high temperature simulation experiment and thermodynamic analysis,and the occurrence characteristics of inclusions in rare earth treated steel was compared with the traditional calcium treated.The results show that the inclusions in aluminum deoxidized wheel steel after calcium treatment are mainly Al2O3,MnS,(Mn,Ca)S and CaO-Al2O3,and Al2O3-(Mn,Ca)S and CaO-Al2O3-CaS wrapped composite inclusions.Compared with calcium-treated steel,the content of A12O3 inclusions in wheel steel after rare earth treatment is reduced,MnS and(Ca,Mn)S nearly spherical inclusions of Ce2O3 and Ce2O2S were formed,and the size of inclusions decreased significantly.With the increase of rare earth content[w(Ce)=0.0160％～0.0250％],the proportion of inclusions ≤5 μm increased from 91.0％to 99.8％,and the effect of rare earth refining inclu-sions was remarkable.In addition,the thermodynamic analysis shows that,with the increase of w(Ce)in wheel steel from 0 to 0.0300％,the change rule of main inclusions in molten steel is Al2O3→CeAlO3→Ce2O3→Ce2O2S at 1600 ℃.The modifi-cation of Al2O3 inclusions in steel can be realized by rare earth treatment,and the formation of MnS inclusions during solidifi-cation can be effectively suppressed,resulting in Ce2O2S and Ce2O3 inclusions.
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