LAUSR

Adopting effective measures to promote the columnar to equiaxed transition (CET) during the solidification stage of steel have attracted much attention.1–3) Among the methods of promoting CET,4–7) stirring of the melt by time-varying magnetic fields is particularly attractive due to the completely contactless feature and flexible tailoring of the magnetic fields themselves.8–11) The flow induced by the melt stirring can penetrate the mushy zone, remelt the dendrite arms and decrease the temperature gradient in the melts, thus favoring the CET.12) In contrast to the time-varying magnetic fields, static magnetic fields are always used to suppress the flow due to the braking effect of the Lorentz force.13) Based on the Seebeck effect, however, a thermoelectric magnetic convection (TEMC) can be induced in the mushy zone under the static magnetic field.14) It is attributed to a thermoelectric magnetic force (TEMF) acting on the melts. The TEMF results from interaction between the thermoelectric current (TEC) near the liquid/solid interface and the applied static magnetic field. On the other hand, the TEMF imposed on dendrites and equiaxed grains breaks the dendrites and drives the motion of dendrite fragments and equiaxed grains in the mushy zone.15–17) Obviously, above-mentioned effects result in a promotion of the CET.18) Therefore, the CET Columnar to Equiaxed Transition during Directionally Solidifying GCr18Mo Steel Affected by Thermoelectric Magnetic Force under an Axial Static Magnetic Field