Columnar to equiaxed transition during directionally solidifying GCr18Mo steel affected by thermoelectric magnetic force under an axial static magnetic field

Abstract

The effects of an axial static magnetic field (ASMF) on the columnar to equiaxed transition (CET) during directionally solidifying GCr18Mo steel were investigated by experiment and numerical simulation. Experimental results show that the CET has been promoted by the increases of the magnetic field intensity and temperature gradient and the decrease of the growth speed. The corresponding numerical simulations verify that a thermoelectric magnetic convection in the melts and a thermoelectric magnetic force acting on the secondary dendrite neck are produced by the interaction between ASMF and a thermoelectric current. Compared the experimental results with the numerical simulations, the mechanism for the CET with ASMF demonstrates that the application of ASMF contributes to the transport of the fragments in the melts and detachment of dendritic side arms. Based on these results, we propose a process window for the CET of GCr18Mo steel with ASMF.