Abstract: In view of the lower center equiaxed crystal ratio, more serious central carbon segregation, central porosity and shrinkage defected that affected internal quality of 55SiCrA spring steel billet, influence of M-EMS process parameters on magnetic field distribution characteristics was systematically studied in 150mm×150mm billet mould. Moreover, research of the effect of stirring electric current and frequency of mould electromagnetic stirrer（M-MES） on macro solidified structure and central carbon segregation was also carried out by industrial experiments. The experimental results proved that with stirring electric current of M-EMS increasing, central carbon segregation index decreased and center equiaxed crystal ratio rised. There was a non-linear relationship between stirring frequency of mould electromagnetic stirrer（M-MES）and center equiaxed crystal ratio besides central carbon segregation. Center equiaxed crystal ratio increased from 18.5% to 32.5%, central carbon segregation index decreased from 1.23 to 1.04 and the central porosity and corner cracks were eliminated when stirring electric current was 320A and frequency was 3.5Hz. Finally billet internal quality was evidently improved.improved.

Key words: mould electromagnetic stirring, 55SiCrA spring steel, magnetic field characteristics, internal quality