Effect of Magnetic-Controlled Electroslag Remelting on Solidification Microstructure and Mechanical Properties of M2 High-speed Steel

Abstract

In this paper， a transverse static magnetic field was applied in the electroslag remelting （ESR） process of M2 high-speed steel. The effects of superimposed transverse static magnetic field on the solidification structure， inclusions and mechanical properties of M2 high speed steel were investigated by methods of optical microscope， scanning electron microscope and metal inclusion analyzer.The results show that the solidification microstructure of M2 ESR ingot is improved after the application of transverse static magnetic field， and the grain growth angle decreases from 52.03° to 21.99°. The depth of molten pool is reduced from 44.2 mm to 18.8 mm. The eutectic carbides are refined from coarse network to fine eutectic carbides. At the same time， the efficiency of inclusions removal is improved， and the number of inclusions in the 4 mm2 detection area is reduced to 1 064 compared to 2 119 without the magnetic field. In addition， hardness uniformity is improved in both transverse and longitudinal sections of the electroslag ingot. The analysis shows that the change of the morphology and grain growth angle of the metal pool under the transverse static magnetic field is due to the periodic electromagnetic oscillation effect on the droplet transformation characteristics， which causes the metal droplet to be broken in the low process and makes the temperature distribution in the molten pool more uniform， leading to the shallow flattening of the metal pool. In the electroslag remelting process， the transverse magnetic field reduces the local solidification time by the way of shallow flat melting pool， thus inhibiting the dynamic conditions of the growth of eutectic carbides and obtaining finer eutectic carbides. In terms of inclusions， the transverse static magnetic field can promote the removal of inclusions in the three phases of liquid film layer， droplet and pool.

Keywords

• magnetic-controlled electroslag remelting； transverse static magnetic； m2 high-speed steel； solidification structure； eutectic carbide； inclusion； uniformity of hardness