Grain Refinement During Directionally Solidifying GCr18Mo Steel at Low Pulling Speeds Under an Axial Static Magnetic Field

Abstract

The present work investigates how axial static magnetic field affects the solidification structure and the solute distribution in directionally solidified GCr18Mo steel. Experimental results show that grain refinement and the columnar to equiaxed transition is enhanced with the increases in the magnetic field intensity (B) and temperature gradient (G) and the decrease in the growth speed. This phenomenon is simultaneously accompanied by more uniformly distributed alloying elements. The corresponding numerical simulations verify a thermoelectric (TE) magnetic convection pattern in the mushy zone due to the interaction between the magnetic field and TE current. The TE magnetic convection in the liquid should be responsible for the motion of dendrite fragments. The TE magnetic force acting on the dendrite is one of the driving forces trigging fragmentation.Keywords GCr18Mo steel Á Grain refinement Á Axial static magnetic field Á Columnar to equiaxed transition Á Thermoelectric magnetic force Acta Metallurgica Sinica (English Letters) (2018) 31:681-691 https://doi.org/10.1007/s40195-017-0691-3( 0123456789().,-volV) (0123456789().,-volV)

Simulation of the Influence of Pulsed Magnetic Field on the Superalloy Melt with the Solid–Liquid Interface in Directional Solidification

“…The PMF may increase the nucleation rate and increase the probability of nucleus survival. It is generally believed that the electromagnetic force, electromagnetic vibration, and forced convection are favorable for grain refinement, such as a direct action of the electromagnetic force on the mushy zone is supposed to break the dendrites into small fragments owing to high shear stress [20][21][22]. However, it is not clear which mechanism dominates.…”

Columnar to Equiaxed Transition during Directionally Solidifying GCr18Mo Steel Affected by Thermoelectric Magnetic Force under an Axial Static Magnetic Field

“…The effect of ASMF on the CET in GCr18Mo steel during directional solidification at low growth speeds (5-20 μm/s) has also been investigated in our previous work. 22) The results have shown that the applied ASMF has enhanced the CET of GCr18Mo steel. However, the mechanism for the CET with ASMF is roughly described from a macro perspective.…”

“…More details regarding the experiment conditions are described in the work. 22) The morphology of the solidification microstructures was observed by optical microscopy (DM 6000M, Leica, Germany). The samples were cut-across the longitudinal section, polished, and etched in saturated solution of picric acid at 80°C.…”

Hot Tearing Susceptibility of AXJ530 Alloy Under Low-Frequency Alternating Magnetic Field

“…However, under the action of the low-frequency alternating magnetic field, the dendritic structure in the alloy was broken to shorten the length of the primary dendrite, which reduced the distance and difficulty of the residual liquid phase to feed. Studies [40,41] have shown that an equiaxed structure is more conducive to the flow of low melting phases between the crystals to eliminate segregation. When the microstructure of the structure tended to be equiaxed, the eutectic phase exhibited a uniform network distribution.…”