| Element | % |
|---|---|
| Carbon (C) | 3.5–3.8 |
| Silicon (Si) | 2.2–2.7 |
| Manganese (Mn) | ≤0.5 |
| Magnesium (Mg) | 0.03–0.05 |
| Property | Value |
|---|---|
| Tensile strength | 552 MPa (80 ksi) min |
| Yield strength | 379 MPa (55 ksi) min |
| Elongation | 6% min |
| Hardness | 187–255 HB |
Density: 7.1 g/cm³ · Heat treatment: As-cast or normalized to develop a pearlitic matrix for higher strength.
| Standard | Equivalent grade |
|---|---|
| EN / ISO | EN-GJS-550-5 |
| GB | QT550-5 |
| JIS | FCD550 |
| DIN (old) | GGG55 |
Equivalents by nominal class — confirm exact chemistry & spec for critical parts.
It is a higher-strength pearlitic ductile iron for gears, crankshafts and heavily loaded machinery where strength and wear resistance matter more than maximum ductility.