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通过对钢轨A类非金属夹杂进行不同深度、不同位置的取样检测,发现钢轨A类非金属夹杂评级结果存在一定偶然性。以U75V为例进一步采用Factsage热力学数值模拟及析出热力学理论对MnS非金属夹杂的析出过程进行分析;结合连铸过程钢液冷却凝固特性及实际统计、检测结果对MnS非金属夹杂的析出进行验证,最终得出MnS析出于钢液近乎完全凝固,且主要由于S、Mn偏析形成微区高溶质浓度而析出。以降低钢液氧、氮含量为基础,降低钢液硫含量、夹杂变性处理及铸坯内部质量优化可以抑制MnS非金属夹杂的析出及轧制形变。
Through a series of non-metallic inclusions in the rail at different depths and locations, it is found that there is some chance that the non-metallic inclusions of rail type A will be graded. Taking U75V as an example, Factsage thermodynamic numerical simulation and precipitation thermodynamics theory were used to analyze the precipitation process of MnS non-metallic inclusions. Combining the characteristics of solidification and solidification of molten steel during the continuous casting process, the test results verify the nonmetallic inclusions in MnS, The results show that the precipitation of MnS almost completely solidifies in the molten steel, and precipitates mainly due to the segregation of S and Mn to form high solute concentration in the micro-zone. In order to reduce the content of oxygen and nitrogen in molten steel, the content of sulfur in the molten steel can be decreased, the inclusion heterogeneity and the internal quality optimization of slab can restrain the precipitation of non-metallic MnS inclusions and the rolling deformation.