The Droplet Evolution Trend and Purification Efficiency in ESR Process by Superimposing a Static Magnetic Field

The paper investigated the refinement effect on droplet size of Electroslag Remelting(ESR)Process by superimposing a transverse static magnetic field through physical simulation method.A transparent experimental model is built to visualize the ESR process under magnetic field,especially focusing on the formation and departure process of droplets on electrode tip.The results show that due to the interaction between alternating current and external transverse magnetic field,the resulting electromagnetic oscillation in the molten droplet and slag bath refined droplets remarkably, the higher the magnetic field intensity,the smaller the droplet size.However,there exists a suitable frequency of 10Hz for the current which will achieve an optimal effect of droplet's dispersing and refinement.Based on the theory of electromagnetic separation,a new mechanism of removing nonmetallic inclusions in ESR process is proposed.By a simplified circuit model,the inclusion removal efficiency is calculated and it proves that the refinement of droplets under magnetic field could increase the removal efficiency of nonmetallic inclusions in ESR significantly.

Study on the Electroslag Remelting of Bearing Steel in Static Magnetic Field

The Electroslag Remelting(ESR)Process has been developed quickly in recent years for its productions of excellent metal ingots with high purity,compact structure,homogeneous composition and clean surface.However,some problems in traditional ESR process still exist,for example the nonmetallic inclusions,coarse dendrite crystal and solute segregation in large-scale ESR etc.In this study we combine the ESR process with electromagnetic processing of materials(EPM)process in GCr15 steel under conditions of 400-700 amps current.The microstructure and inclusions analysis showed that,the inner structure of ingots is compact and homogeneous and no remarkable inclusions appear when superimposing static magnetic field simultaneously.Refined branch grain size,homogeneous distribution of solute, decreased concentration of inclusions and impurities and elevated hardness also could be achieved.ESR process under steady magnetic field makes melt pool planer when compared with that without magnetic field,which would be explained by the electromagnetic vibration refined metal melting drops and the temperature field in the pool is uniformity.