Baotou Steel is one of the main production bases of heavy rail steel in China and large size nonmetallic in-clusions are the bottleneck restricting improvement of quality of heavy rail steel.In this paper,the control technology for superfine dispersion of inclusions in heavy rail steel with magnesium is developed based on the physicochemical and metal-lurgical properties of magnesium.The comparative analysis between industrial tests of magnesium modification and tradi-tional process showed that the inclusions in heavy rail steel such as MnS and CaO-Al2O3-SiO2 were transformed into small size composite inclusions of MgO·Al2O3 and MnS,density of inclusions on vertical and horizontal observation planes and intermediate vertical observation plane of the rail were increased from 17 mm-2,21 mm-2 and 18 mm-2 to 22 mm-2,29 mm-2 and25 mm-2 respectively,while equivalent diameters were decreased from 2.7 μm,2.6 μm and 2.4 μm to 2.3 μm,2.4 μm and 2.3 μm respectively as well as proportion of area of inclusions were decreased from 0.017％,0.016％and 0.014％to 0.013％,0.014％and 0.012％respectively after magnesium modification.Moreover,the non-metallic inclusions in steel are rated as Grade A(0.5,0.5),Grade B(0.5,0.5),Grade C(1.0,0.5),Grade D(0.5,0.5)and Grade Ds(0)according to Method A as well as rated as 2.78 according to Method K.The inclusions of heavy rail steel after magnesium modification could meet the standard requirements.
维普
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