During the production of theprofile, the medium frequency induction furnace can be used for smelting. The number of graphite balls can be increased through multiple inoculation and spheroidizing treatment. Generally, the inoculant used is 75SiFe or silicon strontium, and the spheroidizing agent is FeSiMg6RE2. The centrifugal casting machine is used for pouring. After pouring, the required ductile iron profile is formed by air cooling to room temperature; According to the size requirements of the piston, the ductile iron pipe profiles are processed into the piston head, that is, half of the cooling oil passages are processed in advance at the piston head, and the machining allowance for the remaining surfaces is recommended to be 3-5 mm; The nodular cast iron bar is processed into the piston skirt, that is, the piston skirt is processed in advance. The other half of the cooling oil duct and the inner cavity of the skirt are processed into the finished size according to the design requirements of the drawing. The machining allowance for the remaining surfaces is recommended to be 3-5 mm.
Under the (Leica DM2500M) optical microscope, observe the metallographic structure of the piston head and skirt semi-finished products. The nodularity is greater than 95%, the graphite ball diameter is less than 0.06mm (ball diameter size is 6-8), as shown in Figure 1, and the ferrite content is greater than 90%, as shown in Figure 2 and Figure 3; The hardness is 150-200HBW, the as cast strength is ≥ 600MPa, and the elongation is greater than 7%.