Effect of axial static magnetic field on cleanliness and microstructure in magnetically controlled electroslag remelted bearing steel

The effect of the axial static magnetic field (ASMF) on cleanliness and microstructure in magnetically controlled electroslag remelted GCr15 bearing steel ingots was investigated experimentally. The results show that a magnetically controlled spin-vibration induced by the interaction of the ASMFs and the remelting current exists at the consumable electrode tip, resulting in thinner liquid melt film and smaller droplets. With the increase in magnetic flux density, the optimization effect of ASMFs on electroslag remelting process increases and reaches the peak with a 40 mT ASMF, then decreases. The cleanliness of the ingots was improved, and the count of inclusions larger than 5 μm was reduced. The microstructure of the ingots processed with a 40 mT ASMF was significantly refined. The depth of the metallic molten pool was reduced from 45.2 to 17.5 mm with the application of 40 mT ASMF. The tensile strength, impact toughness, and Rockwell hardness of the ingots obtained under the 40 mT ASMF were significantly improved. The mechanisms of the spin-vibration occurring at the electrode tip end were interpreted in detail to elucidate the effect of ASMFs.