In order to stabilize the melting quality of molten iron, the chemical composition shall be selected and strictly controlled as follows: w (C) 3.6%~3.7%, w (Si) 2.55%~2.65%, w (Mn) ≤ 0.2%, w (P) ≤ 0.03%, w (S) 0.008%~0.012%, w (Mg) 0.04%~0.05%.
The spheroidizing method of nodular cast iron adopts the spheroidizing treatment process of the impact method. The 1.1% light rare earth nodularizing agent+1.1% silicon barium inoculant is buried, and the inoculant is covered with silicon steel sheet to prevent the spheroidizing treatment from being advanced. The pouring temperature is (1380 ± 10) ℃. During the pouring of nodular cast iron, 0.15% sulfur oxygen inoculant is used for the stream inoculation treatment.