1. Structure of nodular cast iron
The material grade of ductile iron castings is QT450-10, the unit weight of ductile iron castings is 3.02kg, and the overall dimension is 185 mm × 74 mm × 163 mm, the structure of nodular cast iron is shown in Figure .
2. Technical requirements for nodular cast iron
The chemical composition requirements are shown in Table . The metallographic structure requires spheroidization rate ≥ 80%, graphite size of 5~8 grades, and the matrix is ferrite+pearlite. Mechanical properties require tensile strength ≥ 450 MPa, yield strength ≥ 280 MPa, elongation ≥ 10%, hardness 143~217 HBW. The internal quality shall be free of shrinkage porosity, shrinkage cavity, crack and porosity. The surface of ductile iron castings shall not have any defects such as sand holes and slag holes that affect the appearance and assembly.
| Element | C | Si | Mn | P | S | Cu |
| Content | 3.3~3.9 | 2.2~3.2 | 0.1~0.4 | ≤0.08 | ≤0.02 | ≤0.2 |