摘要:
通过对齿轮钢矩形坯轧制大规格圆钢宏观碳偏析的分析, 结合碳含量和低倍组织, 研究了不同结晶器电磁搅拌强度时圆钢的碳偏析行为。结果表明, 结晶器电磁搅拌扩大连铸坯柱状晶/等轴晶转换界面 (CET) 框尺寸, 提高等轴晶率, 但是产生皮下负偏析带, 圆钢的偏析变得明显;结晶器电磁搅拌下, 齿轮钢矩形坯与圆钢从表面到中心呈现“N”形碳偏析, 搅拌强度越大, 偏析幅度越大;圆钢同一圆周上, 搅拌时3/4 R、1/2 R处极差大, 1/4 R处极差小, 不搅拌时则相反。连铸坯的CET区域与圆钢方框偏析有严格的对应性, 说明连铸坯与圆钢的组织与成分存在传承关系。
Abstract:
Effect of different M-EMS strength on carbon segregation of gear steel round bar rolled from rectangular bloom is investigated by analyzing the carbon distribution and etched macro-structure.The results show that the CET rectangle is enlarged and equiaxed crystal rate rises with M-EMS,but a band of negative carbon segregation appears under the surface of round bar and the carbon segregation rectangle is apparent in macrostructure.An N-shaped carbon segregation appears from surface to center of the bloom and round bar under M-EMS and the segregation becomes more intensified with stronger stirring.The carbon difference is large at 3/4 R circle,1/2 R circle and small at 1/4 R circle in same round bar circumference with M-EMS,but reversal without M-EMS.The bloom and round bar are subject to the same carbon segregation rules,and the carbon distribution is strongly related to the etched macrostructure.There is an inherited relation between bloom and round bar in carbon segregation and macrostructure.
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