Intent: Vibration damping capacity and thermal conductivity (flake graphite) versus tensile ductility, elongation, and impact shock resistance (nodular graphite).
Material Comparison
Compare verified engineering materials side by side with condition-specific mechanical properties.
| Parameter | ASTM A48 Class 30 Gray Cast Iron | ASTM A536 Grade 65-45-12 Ductile Cast Iron |
|---|---|---|
| Material Family | Cast Iron | Cast Iron |
| Subfamily | Gray Cast Iron | Ductile (Nodular) Iron |
| ASTM Designation | A48 Class 30 | A536 Grade 65-45-12 |
| UNS Designation | F12101 | F33100 |
| SAE Designation | J431 G3000 | J434 D4512 |
| Element | ASTM A48 Class 30 Gray Cast Iron | ASTM A536 Grade 65-45-12 Ductile Cast Iron |
|---|---|---|
| C (Carbon) | 3.1 – 3.4% | 3.5 – 3.8% |
| Si (Silicon) | 1.9 – 2.3% | 2.2 – 2.8% |
| Mn (Manganese) | 0.6 – 0.9% | 0.2 – 0.5% |
| P (Phosphorus) | ≤ 0.12% | ≤ 0.05% |
| S (Sulfur) | ≤ 0.15% | ≤ 0.02% |
| Fe (Iron) | — | — |
| Mg (Magnesium) | — | 0.035 – 0.06% |
| Property | ASTM A48 Class 30 Gray Cast Iron | ASTM A536 Grade 65-45-12 Ductile Cast Iron |
|---|---|---|
| Density · TYPICALUnit: g/cm³ | 7.2 g/cm³ | 7.1 g/cm³ |
| Mechanical Parameter | ASTM A48 Class 30 Gray Cast IronAs-Cast (Standard Test Bar B, 30.5 mm diameter) | ASTM A536 Grade 65-45-12 Ductile Cast IronAs-Cast (Standard) |
|---|---|---|
| Poisson Ratio · TYPICALUnit: dimensionless | 0.26 dimensionless | 0.28 dimensionless |
| Property | ASTM A48 Class 30 Gray Cast Iron | ASTM A536 Grade 65-45-12 Ductile Cast Iron |
|---|---|---|
| Electrical Resistivity · TYPICALCategory: ELECTRICAL • Unit: nΩ·m | 680 nΩ·m | 560 nΩ·m |
| Thermal Conductivity · TYPICAL · 20 °CCategory: THERMAL • Unit: W/(m·K) | 48 W/(m·K) | — W/(m·K) |
| Thermal Conductivity · TYPICALCategory: THERMAL • Unit: W/(m·K) | — W/(m·K) | 35 W/(m·K) |
| Specific Heat Capacity · TYPICALCategory: THERMAL • Unit: J/(kg·K) | 480 J/(kg·K) | 470 J/(kg·K) |
| Coefficient of Thermal Expansion · TYPICALCategory: THERMAL • Unit: µm/(m·K) | 11 µm/(m·K) | 11.8 µm/(m·K) |
Machinability: Excellent machinability (~90% relative to C36000 free-cutting brass). Flake graphite acts as internal lubricant and natural chip breaker. Readily turned, milled, and drilled without burr formation.
Weldability: Poor weldability. Arc welding produces brittle martensitic heat-affected zones and crack risks. Recommended repair procedure requires 250°C–350°C (480°F–660°F) preheat, nickel-iron (ENiFe-CI) electrodes, short beads with peening, and slow insulation cooling.
Formability / Cold Working: Non-deformable. Gray cast iron is inherently brittle in tension and cannot be cold or hot deformed.
Heat Treatment & Annealing: Stress relief annealing at 540°C–595°C (1000°F–1100°F) for 1–2 hours eliminates residual casting stresses and prevents distortion. Flame or induction surface hardening can achieve 50–55 HRC on slideways.
Machinability: Very good machinability (~80% relative to C36000 baseline). Low cutting forces, good tool life, and smooth surface finishes.
Weldability: Moderately weldable with qualified procedures. Preheating to 200°C–250°C and nickel-iron (ENiFe-CI) filler wire are required to prevent hard heat-affected zones.
Formability / Cold Working: Limited localized forming (coining, staking) feasible due to 12% elongation.
Heat Treatment & Annealing: Typically utilized in the as-cast condition. Can be full annealed at 870°C for maximum ductility or normalized at 900°C for increased strength.