Regarding M2 high-speed steel continuous-cast billets,the carbide’s size,distribution,and morphology not only directly influence subsequent processes like rolling,but also exert a significant impact on the performance and quality of the final product.A thermal simulation test machine is utilized in this study for dendritic growth in continuous cast billets to explore the effect of pulse magneto-oscillation （PMO） solidification refinement technology on the carbide precipitation and growth process in M2 high-speed steel billets.The possibility and conditions for using PMO technology to improve the carbides in continuous cast M2 high-speed steel are also discussed.The thermal simulation results indicate that PMO can refine the solidification microstructure.Under peak current conditions of0,120,240,and 360 KIA,the secondary dendrite arm spacing at the solidification end decreased by 3.08,3.83,and 6.91μm,respectively.At the same time,the macro-distribution of C,W,and Cr elements became more uniform.The thermal simulation quenching tests show that PMO technology can effectively reduce the area fraction of carbides and decrease the size of carbide network intersections.The lowest carbide area fraction was observed at360 KIA,while the smallest carbide network intersection size was found at 240 KIA.Thermodynamic calculations indicate that without PMO treatment,the solid-phase fraction of Mo2C and W2C precipitated at the solid-liquid interface was 0.921 and 0.972,respectively.With PMO treatment,the precipitated solid phase fractions of Mo2C and W2C at the solid-liquid interface reach 0.931 and 0.988 respectively,while the morphology of M2C（M=Mo/W） transitions from lamellar to fibrous-like structure.On the one hand,PMO treatment refines the solidification microstructure and weakens element enrichment,and on the other hand,it lowers the carbide precipitation temperature.These two effects result in smaller carbides.
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