Flow Behavior and Solute Distribution in the Second Cooling Zone of Continuous Casting of GCr15 Bearing Steel Regulated by Combined Magnetic Fields

Abstract

GCr15 bearing steel is prone to center segregation and center crack during continuous casting, which is caused by irregular flow behavior and uneven distribution of solute. In this article, two-stage combined magnetic fields of high-frequency and low-current and low-frequency and high-current are used to regulate the flow behavior of 30% solid phase ratio and 60% solid phase ratio in the secondary cooling zone, respectively. The distribution of solute in the final solidified structure can be homogenized by the fine control of macroscopic flow and microscopic inter-dendrite flow under the combined magnetic field. The results show that the rotational flow of molten steel is accelerated with lower solidification rate by the first stage of electromagnetic stirring. Therefore, the solute concentration in the liquid phase increases with the increase of magnetic induction intensity. In the second stage of electromagnetic stirring, the dendrites are broken by micromagnetohydrodynamic effect and the solute segregation decreases.