Verified by Rachel Mayfield, Supply Chain Analyst - August 2026
Grey cast iron (EN-GJL-250 (formerly grade 250)): typical engineering properties at room temperature. These are representative handbook and datasheet values - composition, temper and product form move real figures, so for design work use the supplier's certified datasheet. For quick sizing, comparison and sanity checks, the table below is what you need.
Grey cast iron properties
| Property | Typical value | Unit |
|---|
| Density | 7,100-7,300 | kg/m3 |
| Melting range | 1,150-1,200 C | |
| Thermal conductivity | 46-50 | W/m K |
| Thermal expansion | 10.5-11 | x10-6 /K |
| Specific heat | 460-490 | J/kg K |
| Elastic modulus (E) | 100-110 | GPa |
| Tensile strength | 250 MPa (EN-GJL-250, tension) - far stronger in compression | |
Where grey cast iron is used
Typical applications: machine bases, pump and valve bodies, gearbox housings, brake discs and bearing housings.
What to know before specifying it
Grey iron's graphite flakes make it self-damping (machine tool bases), self-lubricating-ish and easy to cast in complex shapes - and also make it brittle in tension with effectively no elongation. Design it in compression, never shock-load it, and it outlasts everything.