M-EMS搅拌强度对重轨钢均质性及凝固组织的影响

Effects of M-EMS Stirring Intensity on Homogeneity and Dendritic Structure of Rail Steel

试验对比研究连铸M-EMS不同搅拌强度对U75V(RH340)重轨钢均质性的影响。结果表明:无搅拌试验铸坯均质性最优,C元素偏析度极差为0.13～0.20,标准均方差为0.027～0.048;Mn元素偏析度极差为0.04～0.06,标准均方差0.012～0.014,负正偏析交替不明显,最大正偏析集中于铸坯中心区域,铸坯柱状晶发达;强搅拌(380×10^(-4) T)试验铸坯等轴晶比例高,晶粒尺寸小,C元素负正偏析交替明显。强搅拌(380×10^(-4) T)试验铸坯轧制钢轨轨头C元素偏析度极差0.08,弱搅拌(220×10^(-4) T)为0.05,无搅拌为0.03;强搅拌(380×10^(-4) T)试验铸坯轧制钢轨轨腰正偏析区正偏析范围1.01～1.03,弱搅拌(220×10^(-4) T)为1.03～1.05,无搅拌为1.02～1.06。由此提出:取消结晶器电磁搅拌,采用"二冷(凝固末端)电磁搅拌+凝固末端压下"的技术思路,并确定二冷(凝固末端)电磁搅拌安装位置为距离结晶器液面5.0～6.0 m区域。

Comparison experiments were carried out to find out the effects of M-EMS stirring intensity on the homogeneity of rail steel.The results show that homogeneity of bloom which produced without stirring is the best,the range value of carbon segregation degree is 0.13~0.20,the mean square deviation of carbon segregation degree is 0.027~0.048,the range value of manganese segregation degree is 0.04~0.06,the mean square deviation of manganese segregation degree is 0.012~0.014,the alternation of negative and positive segregation is non obvious,the maximum positive segregation area mainly gathered at center area,and columnar crystal is well developed,ratio of equiaxial crystal in bloom is higher which produced with strong stirring intensity(380×10^-4 T),the size of grain is small,the alternation of negative and positive segregation is obvious.The range value of carbon segregation degree in railhead which rolled from bloom that produced with strong stirring intensity(380×10^-4 T)is 0.08,and weak stirring intensity(220×10^-4 T)is 0.05,but non-stirring is 0.03 and it’s the best.The value of positive segregation degree for carbon in rail web which rolled from bloom that produced with strong stirring intensity(380×10^-4 T)is 1.01~1.03 and it’s the best,but weak stirring intensity(220×10^-4 T)is 1.03~1.05,and non-stirring is 1.02~1.06.Based the results,made suggestion to cancel M-EMS and equip F(S)-EMS combine with soft reduction to improve the homogeneity of rail steel,also spotting the install potion of F(S)-EMS by calculate where distance from the liquid steel level in mold is 5.0~6.0 m.