Effect of M-EMS on Carbon Segregation of Gear Steel Round Bar Rolled from Rectangular Bloom

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.