Quantitative influence of solidification path on solute micro-segregation and inclusion precipitation in the solidification process of rail steel

A solute redistribution model, which takes the phase transformation and MnS precipitation during the solidification of rail steel into consideration, was established. The influence of solidification path on solute micro-segregation and inclusion precipitation was quantitatively analyzed. Furthermore, the effects of MnS inclusion precipitation, equilibrium distribution coefficient ( k i ), and back-diffusion coefficient ( β i ) on solute micro-segregation were investigated. The results indicate that the solidification path significantly influences solute micro-segregation and MnS precipitation in the solidification process. When the carbon content ranges from 0.018% to 0.054%, the peritectic transformation occurs at the end of solidification, and the carbon content significantly affects MnS inclusion precipitation and solute micro-segregation. The carbon content influences solute redistribution through the changes in solidification temperature and phase composition, resulting in the variations in k i and β i , which in turn affects solute micro-segregation. The impact of k i on solute micro-segregation is significantly influenced by phase composition, while β i is affected by both temperature and phase composition. There is a competitive relationship between k i and β i concerning solute micro-segregation. The research findings provide a foundation for further elucidating the laws of solute redistribution during the solidification of molten steel, thereby effectively improving the quality of rail steel casting bloom.