Experimental study and numerical simulation of permanent magnet stirring on solidification of IN718 superalloy under different rotation speeds

Abstract

A novel permanent magnet stirring (PMS) characterized by low power dissipation and high magnetic flux density provides an alternative method for producing IN718 superalloy with uniform microstructure during solidification. In the present work, the electromagnetic force and the molten superalloy flow of PMS under different rotation speeds (0, 75, 150, and 300 rpm) were calculated based on the multi-physics field analysis software Comsol and the flow field software Fluent. The calculated results were validated using the measured magnetic flux densities under different rotation speeds. It was found that the calculated maximum electromagnetic force enhanced from 2.73 to 10.78 kN/m3, and the maximum tangential velocity increased from 0.13 to 0.46 m/s in a diameter of 50 mm molten IN718 ingot when the rotation speeds increased from 75 to 300 rpm. Moreover, the experimental results revealed that the regions of solidification dendrites were broken under the impact of PMS, which were a source of refinement grains and attributed to the uniform distribution of Laves phase (average size decreased from 74.86 to 38.83 µm in the edge) during solidification. In addition, grain refinement and a random distribution of grains decreased texture intensity with the maximum value from 6.124 to 3.828.