Study on the inclusion distribution behavior of U71Mn heavy rail steel after rolling
The morphology and distribution of non-metallic inclusions significantly affect the perform-ance of heavy rail steels.This study employed optical microscopy,scanning electron microscopy,a three-dimensional etching instrument for inclusions,and Thermo-calc software to investigate the inclu-sions in U71Mn heavy rail steel produced by a certain factory.The results show that the average equi-valent diameter and aspect ratio of inclusions at the waist of the U71Mn heavy rail steel are the largest,while the number density is the smallest.The inclusion densities in the rail head,waist,and base are 18,12,and 14/mm2,respectively,with the average equivalent diameters of 2.5,2.7,and 2.4 μm,and the av-erage aspect ratios of 7.4,13.3,and 6.4,respectively.The main inclusions in the steel are individual MnS and complex inclusions of CaO·Al2O3·SiO2·MgO.The sizes of MnS at the rail head and base are relatively small,mainly distributed between 10～50 μm.The sizes of MnS inclusions at the rail waist are larger,mostly between 20～80 μm,with several large-sized MnS rolled on the same horizontal line.The complex inclusions of CaO·Al2O3·SiO2·MgO generally appear near-spherical or irregular along the rolling direction.
U71Mn heavy rail steelinclusionsrolling deformationthermodynamic analysis
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