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Grey Cast Iron

Grey cast iron is a cast iron. It has the highest thermal conductivity among the cast irons in the database.

The properties of grey cast iron include eleven common variations. This page shows summary ranges across all of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare grey cast iron to: cast irons (top), all iron alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

Mechanical Properties

Brinell Hardness

160 to 300

Compressive (Crushing) Strength

570 to 1290 MPa 83 to 190 x 103 psi

Elastic (Young's, Tensile) Modulus

180 GPa 26 x 106 psi

Elongation at Break

9.6 %

Fatigue Strength

69 to 170 MPa 10 to 25 x 103 psi

Poisson's Ratio

0.29

Shear Modulus

69 GPa 10 x 106 psi

Shear Strength

180 to 610 MPa 26 to 88 x 103 psi

Tensile Strength: Ultimate (UTS)

160 to 450 MPa 23 to 65 x 103 psi

Tensile Strength: Yield (Proof)

98 to 290 MPa 14 to 43 x 103 psi

Thermal Properties

Latent Heat of Fusion

280 J/g

Melting Completion (Liquidus)

1380 °C 2510 °F

Melting Onset (Solidus)

1180 °C 2150 °F

Specific Heat Capacity

490 J/kg-K 0.12 BTU/lb-°F

Thermal Conductivity

46 W/m-K 27 BTU/h-ft-°F

Thermal Expansion

11 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

7.4 % IACS

Electrical Conductivity: Equal Weight (Specific)

8.9 % IACS

Otherwise Unclassified Properties

Base Metal Price

1.9 % relative

Density

7.5 g/cm3 470 lb/ft3

Embodied Carbon

1.5 kg CO2/kg material

Embodied Energy

21 MJ/kg 9.1 x 103 BTU/lb

Embodied Water

44 L/kg 5.2 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

13 to 37 MJ/m3

Resilience: Unit (Modulus of Resilience)

27 to 240 kJ/m3

Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

25 points

Strength to Weight: Axial

5.8 to 17 points

Strength to Weight: Bending

8.7 to 17 points

Thermal Diffusivity

13 mm2/s

Thermal Shock Resistance

6.0 to 17 points

Alloy Composition

Iron (Fe) 92.1 to 93.9
Carbon (C) 3.1 to 3.4
Silicon (Si) 2.5 to 2.8
Manganese (Mn) 0.5 to 0.7
Phosphorus (P) 0 to 0.9
Sulfur (S) 0 to 0.15

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

ISO 185: Grey Cast Irons - Classification

ASTM A48: Standard Specification for Gray Iron Castings

Cast Iron: Physical and Engineering Properties, Harold T. Angus, 1976

Microstructure of Steels and Cast Irons, Madeleine Durand-Charre, 2004

Ferrous Materials: Steel and Cast Iron, Hans Berns and Werner Theisen, 2008

CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015