非调质钢中MnS的析出与长大

摘要：在立式电阻炉内熔化45MnVS钢，分析了水冷和空冷2种冷却方式下试样中MnS的形貌特征，并对试样中MnS的析出与长大进行了热力学和动力学计算。结果表明：水冷试样中MnS的平均尺寸为1.14μm，最大尺寸为7.80μm；空冷试样中MnS的平均尺寸为2.19μm，最大尺寸为8.78μm。钢液凝固过程中，MnS在固相分率达到0.69时析出；在相同固相分率下，水冷试样比空冷试样中MnS的尺寸小。固相分率小于0.97时，S元素为MnS长大的控制元素，固相分率大于0.97时，Mn元素为MnS长大的控制元素。计算所得水冷试样和空冷试样中MnS最终尺寸分别为5.27和9.54μm。

MnS precipitation and growth during solidification of non quenched and tempered steel

The 45MnVS steel was melted in the vertical resistance furnace, and the morphological characteristics of MnS in the samples for two cooling methods, water cooling and air cooling, were analyzed. The thermodynamics and kinetics of precipitation and growth of MnS in those samples were calculated. The results show that the average size of MnS in the water cooled sample is 1.14μm and the maximum size is 7.80μm; and those value in the air cooled sample are 2.19μm and 8.78μm, respectively. During solidification of molten steel, MnS begin to precipitate when the solid fraction reaches 0.69. At the same solid fraction, the size of MnS in the water cooled sample is smaller than that of the air cooled sample. When the solid fraction is less than 0.97, the S element is the controlling element for the growth of MnS, and when the solid phase fraction is more than 0.97, the controlling element is Mn. The calculated final diameters of MnS in the water cooled sample and air cooled sample are 5.27μm and 9.54μm, respectively.