Dendrite Growth Characteristics and Segregation Control of Bearing Steel Billet with Rotational Electromagnetic Stirring

The effects of rotational electromagnetic stirring (R-EMS) on dendrite growth characteristics and segregation control of bearing steel billet were investigated in continuous casting. The results show that applying R-EMS can promote columnar-equiaxed transition, increase the region of the equiaxed grain from 5 % to 45 %, decrease the secondary dendrite arm spacing (SDAS), and reduce the segregation of both carbon and sulfur. Meanwhile, the fragments of dendrite arms induced by R-EMS are observed. The length of the dendrite fragmentation is approximately 1.5 mm, 7–10 times the SDAS. Some fragments can partially remelt to become effective nuclei, and some fragments survive the solidification process.