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Austempered Ductile Cast Iron

Austempered cast iron is a cast iron. It can have the highest tensile strength among the cast irons in the database.

The properties of austempered cast iron include eight 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 austempered 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

270 to 490

Elastic (Young's, Tensile) Modulus

180 GPa 26 x 106 psi

Elongation at Break

1.1 to 13 %

Poisson's Ratio

0.29

Shear Modulus

62 to 69 GPa 9.0 to 10 x 106 psi

Tensile Strength: Ultimate (UTS)

860 to 1800 MPa 120 to 260 x 103 psi

Tensile Strength: Yield (Proof)

560 to 1460 MPa 81 to 210 x 103 psi

Thermal Properties

Latent Heat of Fusion

280 J/g

Melting Completion (Liquidus)

1380 °C 2520 °F

Melting Onset (Solidus)

1340 °C 2450 °F

Specific Heat Capacity

490 J/kg-K 0.12 BTU/lb-°F

Thermal Conductivity

42 W/m-K 24 BTU/h-ft-°F

Thermal Expansion

13 µm/m-K

Otherwise Unclassified Properties

Base Metal Price

2.9 % relative

Density

7.5 g/cm3 470 lb/ft3

Embodied Carbon

1.8 kg CO2/kg material

Embodied Energy

25 MJ/kg 11 x 103 BTU/lb

Embodied Water

48 L/kg 5.7 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

19 to 95 MJ/m3

Resilience: Unit (Modulus of Resilience)

880 to 3970 kJ/m3

Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

25 points

Strength to Weight: Axial

32 to 66 points

Strength to Weight: Bending

27 to 44 points

Thermal Diffusivity

11 mm2/s

Thermal Shock Resistance

25 to 53 points

Alloy Composition

Iron (Fe) 89.6 to 94
Carbon (C) 3.4 to 3.8
Silicon (Si) 2.3 to 2.7
Nickel (Ni) 0 to 2.0
Copper (Cu) 0 to 0.8
Manganese (Mn) 0.3 to 0.4
Molybdenum (Mo) 0 to 0.3
Chromium (Cr) 0 to 0.1
Vanadium (V) 0 to 0.1
Aluminum (Al) 0 to 0.050
Phosphorus (P) 0 to 0.040
Magnesium (Mg) 0 to 0.040
Selenium (Se) 0 to 0.030
Sulfur (S) 0 to 0.020
Tin (Sn) 0 to 0.020
Arsenic (As) 0 to 0.020

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

Followup Questions

Similar Alloys

Further Reading

ISO 17804: Founding - Ausferritic Spheroidal Graphite Cast Irons - Classification

ASTM A897: Standard Specification for Austempered Ductile Iron Castings

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

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