硫含量对重轨钢中非金属夹杂物的影响

摘要：实际生产过程中由于原料和操作控制不精确，钢中硫含量和非金属夹杂物波动较大，严重影响钢的洁净度。为了准确控制重轨钢中硫化锰等非金属夹杂物的尺寸、形态和数量，在实验室开展了硫含量对重轨钢中非金属夹杂物的影响研究。钢中硫质量分数增至70×10-6、110×10-6、140×10-6后随炉冷却，采用全自动夹杂物分析仪对钢中非金属夹杂物进行统计，获得了硫含量与钢中非金属夹杂物成分、尺寸、形态和数量的关系。结果表明，钢中夹杂物大部分为以氧化物为形核核心的复合型MnS；随着硫含量的升高，复合型MnS、MnO-SiO2和MgO-Al2O3-SiO2-CaO型夹杂增多，CaO-SiO2和MgO-CaO-SiO2夹杂减少；夹杂物平均尺寸随硫含量的升高而增大，且不同尺寸的夹杂物均有所增加，尺寸为2~10μm增多最明显；硫质量分数为(70~140)×10-6的钢液凝固过程液相中都能单独析出MnS，且硫含量越高，MnS析出越早，含量越多。

Effect of sulfur content on non metallic inclusions of heavy rail steel

Abstract：Due to the inaccurate control of raw materials and operation in the actual production process, the sulfur content and non-metallic inclusions in the steel fluctuate greatly, which seriously affects the cleanliness of steel. To accurately control the size, shape and quantity of non-metallic inclusions such as manganese sulfide in heavy rail steel, the effect of sulfur content on non-metallic inclusions in heavy rail steel was studied in the laboratory. To investigate the changes of the number and morphology of non-metallic inclusions in steel under different sulfur contents, the sulfur content of test steel was increased to 70×10-6, 110×10-6 and 140×10-6, respectively. During the experiment, the test steel was heated and melted in a tubular furnace according to a certain heating rule, and then cooled naturally in the furnace. Subsequently, the non metallic inclusions in steel were scanned by automatic inclusions analyzer, and the relationship between sulfur content and the composition, size, form and quantity of non-metallic inclusions in steel was obtained. The results indicate that most of the inclusions in the steel are composite MnS with oxides as nucleating cores. With the increase of sulfur content, the quantity density of composite MnS, MnO-SiO2 and MgO-Al2O3-SiO2-CaO inclusions increase, while the CaO-SiO2 and MgO-CaO-SiO2 inclusions decrease. The average size of inclusions increases with the increase of sulfur content, and the number of inclusions with different sizes also increases, especially for inclusions with sizes of 2-10μm which increase obviously. During solidification, MnS can be separated from molten steel with sulfur content of (70-140)×10-6. In addition, the higher the sulfur content is, the earlier MnS inclusions precipitate and the more the MnS content is.