General-purpose flake-graphite cast iron — machine bases, housings, pulleys, gearbox cases. Superb damping and machinability; brittle in tension.
| Property | Typical value |
|---|---|
| Density | 7200 kg/m³ |
| Yield | — (no defined yield — brittle) |
| Tensile | 250–350 MPa |
| Compressive | ~800–1000 MPa |
| Elongation | <1 % |
| Young's E | ~110 GPa (stress-dependent) |
| Hardness | ~180–220 HB |
| CTE | ~11 µm/m·K |
| Thermal cond. | ~46 W/m·K |
| Max service | ~400–450 °C (growth/scaling above ~500 °C) |
| Poisson ν | ~0.26 |
| Shear modulus G | ~40–47 GPa (published torsion data — grey iron E is stress-dependent, do not derive from E) |
| Shear strength | ~290 MPa (EN 1561 typical) |
| Specific heat | ~460 J/kg·K (20–200 °C) |
| Elec. resistivity | ~0.73–0.80 µΩ·m |
| Melting range | ~1130–1250 °C |
| Fatigue (indicative) | ~115–160 MPa (≈0.46 × UTS, EN 1561 bending fatigue) — rotating-bend, polished specimen; indicative only, surface/size/loading factors apply |
Graphite gives short chips, machines dry; hard as-cast skin — take the first cut under it.
Fusion welding risky (brittle white-iron HAZ); Ni-rod repair by specialists, braze preferred.
| System | Designation |
|---|---|
| EN | EN-GJL-250 / EN-JL1040 |
| DIN | GG-25 / 0.6025 |
| ASTM | A48 Class 35B (≈40B) |
| JIS | FC250 |
| BS | BS 1452 Grade 250 |
Equivalents & alternatives: EN-GJL-250 (GG25); ASTM A48 Class 35/40 (near); old BS 1452 Grade 250. Alt: EN-GJS ductile iron (shock loads).
General structural mild steel — sections, plate, weldments. The default for fabrication.
Carbon steelFree-cutting bright mild steel — first choice for high-volume machined parts, studs, fittings.
Carbon steelGeneral bright mild steel bar — weldable, case-hardenable, good all-rounder for machined parts.
Carbon steelMedium-carbon steel — shafts, studs, gears, keys. Through-hardenable to moderate strength.
