Investigation on Effect of Si Addition on the Eutectic Carbides of the As-cast M2 High Speed Steel

The effect of silicon addition on the type and morphology of eutectic carbides in the as-cast M2 high speed steel was investigated by optical microscopy,SEM,XRD and EDS.It is shown that the type and morphology of eutectic carbides remain almost unchanged when 1wt% Si is added to the M2 steel.With the addition of silicon up to 2wt% and 3wt%,the eutectic carbides in the M2 high speed steel change from lamellar-like M2C to herringbone-like M6C,and the M2C eutectoid carbides have disappeared.Silicon is also found to decrease the dentrite spacing of the M2 high speed steel.