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ASTM A436 Type 2b (L-NiCr 20 3, F41003) Cast Iron

ASTM A436 type 2b is a type of austenitic grey cast iron. Cited properties are appropriate for the stress relieved condition. ASTM A436 Type 2b is the ASTM designation for this material. F41003 is the UNS number. Additionally, the AFNOR (French) designation is FGL Ni20 Cr3.

The graph bars on the material properties cards below compare ASTM A436 type 2b 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


Elastic (Young's, Tensile) Modulus

180 GPa 27 x 106 psi

Elongation at Break

8.5 %

Poisson's Ratio


Shear Modulus

72 GPa 10 x 106 psi

Tensile Strength: Ultimate (UTS)

230 MPa 34 x 103 psi

Tensile Strength: Yield (Proof)

120 MPa 18 x 103 psi

Thermal Properties

Latent Heat of Fusion

290 J/g

Melting Completion (Liquidus)

1390 °C 2540 °F

Melting Onset (Solidus)

1350 °C 2460 °F

Specific Heat Capacity

480 J/kg-K 0.11 BTU/lb-°F

Thermal Expansion

14 µm/m-K

Otherwise Unclassified Properties

Base Metal Price

16 % relative


7.8 g/cm3 490 lb/ft3

Embodied Carbon

3.5 kg CO2/kg material

Embodied Energy

49 MJ/kg 21 x 103 BTU/lb

Embodied Water

100 L/kg 12 gal/lb

Common Calculations

PREN (Pitting Resistance)


Resilience: Ultimate (Unit Rupture Work)

17 MJ/m3

Resilience: Unit (Modulus of Resilience)

41 kJ/m3

Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

8.2 points

Strength to Weight: Bending

11 points

Thermal Shock Resistance

6.5 points

Alloy Composition

Iron (Fe) 64.1 to 77.5
Nickel (Ni) 18 to 22
Chromium (Cr) 3.0 to 6.0
Silicon (Si) 1.0 to 2.8
Carbon (C) 0 to 3.0
Manganese (Mn) 0.5 to 1.5
Copper (Cu) 0 to 0.5
Sulfur (S) 0 to 0.12

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

Followup Questions

Similar Alloys

Further Reading

ASTM A436: Standard Specification for Austenitic Gray Iron Castings

ISO 2892: Austenitic Cast Irons - Classification

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