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ASTM Grade 20 (ISO Grade 150, EN-JL 1020) Grey Cast Iron

Grade 20 grey cast iron is a type of grey cast iron. It is furnished in the as-fabricated (no temper or treatment) condition. It has the lowest strength compared to the other variants of grey cast iron.

Mechanical Properties

Graph bars compare grade 20 grey cast iron to other iron alloys (top) and the entire database (bottom).

Brinell Hardness


Compressive (Crushing) Strength

570 MPa 83 x 103 psi

Elastic (Young's, Tensile) Modulus

82 GPa 12 x 106 psi

Elongation at Break

0.52 %

Fatigue Strength (Endurance Limit)

69 MPa 10 x 103 psi

Fracture Toughness

10 MPa-m1/2 9100 psi-in1/2

Modulus of Resilience (Unit Resilience)

59 kJ/m3

Poisson's Ratio


Shear Strength

180 MPa 26 x 103 psi

Strength to Weight Ratio

35 kN-m/kg

Tensile Strength: Ultimate (UTS)

150 MPa 22 x 103 psi

Tensile Strength: Yield (Proof)

98 MPa 14 x 103 psi

Other Material Properties


7.2 g/cm3 450 lb/ft3

Melting Onset (Solidus)

1180 °C 2150 °F

Thermal Conductivity

46 W/m-K 27 BTU/h-ft-°F

Thermal Expansion

11 µm/m-K

Followup Questions

Further Reading

ASTM A48: Standard Specification for Gray Iron Castings

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

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