The invention discloses a compound inoculant used for producing D-type
graphite cast iron, which is characterized in that the weight percents of the constituents are as follows:
magnesium 1.0-4.0,
rare earth 4.0-8.0,
titanium 4.0-9.0, aluminum 1.5-3.0, stibium 0.5-2.0,
calcium 2.0-5.0,
barium 1.0-4.0,
silicon 35-50 and the balance of iron. When the compound inoculant is employed to carry out
inoculation on the melted iron with
high carbon equivalent, the obtained
graphite in the
cast iron is the D-type
graphite. The mechanical properties of castings are high, the tensile strength reaches over 250MPa and the compactness is good. The melted iron has
high carbon equivalent, thus greatly improving the
casting properties of alloys, reducing the
residual stress of the castings, contributing to good size stability and enhancing the
machinability of the castings. The multiple compound inoculant adopts
ladle bottom pouring process, namely, the compound inoculant is placed on the bottom of a
ladle, then the melted iron is injected and the compound inoculant is continuously melted and absorbed in the process of melted
iron injection, thereby reaching the satisfactory
inoculation effect, therefore, the method is simple and the use is convenient.