Effects of solidification structure on MnS in heavy rail steel bloom
The sizes and microstructures of MnS at different positions of the heavy rail steel bloom were measured by electro-chemical etching and Aspex scanning,and the effect of solidification structure on MnS was studied.The results show that when the solidification structure transforms from mixed-crystal to coarse equiaxed grain,the quantitative proportion of MnS particles with the size range of 3-5 μm de-creases,and the quantitative proportion of particles with sizes larger than 10 μm increases significantly.While the distance from the narrow surface of the bloom changed from 40 mm to 100 mm,the solidific-ation structure transformed more obviously,and the larger increment of the quantitative proportion of MnS particles with sizes over 10 μm was obtained:if the solidification structure transformed obviously,the quantitative proportion was increased by 48.02％,and if the solidification structure did not trans-form,the quantitative proportion was increased by 0.31％.It means MnS particles can be refined by ad-opting processes to shorten the local solidification time,such as strengthening cooling during continu-ous casting.
heavy rail steelcontinuous casting billetsolidification structureMnS
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