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EN 1.6308 (18MnMoNi5-5) Nickel-Molybdenum Steel

EN 1.6308 steel is an alloy steel formulated for primary forming into wrought products. Cited properties are appropriate for the quenched and tempered condition. 1.6308 is the EN numeric designation for this material. 18MnMoNi5-5 is the EN chemical designation.

It has a moderately high density among EN wrought alloy steels. In addition, it has a fairly low thermal conductivity and a moderately low tensile strength.

The graph bars on the material properties cards below compare EN 1.6308 steel to: EN wrought alloy steels (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

180

Elastic (Young's, Tensile) Modulus

190 GPa 27 x 106 psi

Elongation at Break

23 %

Fatigue Strength

320 MPa 47 x 103 psi

Impact Strength: V-Notched Charpy

54 J 40 ft-lb

Poisson's Ratio

0.29

Shear Modulus

73 GPa 11 x 106 psi

Shear Strength

390 MPa 56 x 103 psi

Tensile Strength: Ultimate (UTS)

610 MPa 88 x 103 psi

Tensile Strength: Yield (Proof)

460 MPa 66 x 103 psi

Thermal Properties

Latent Heat of Fusion

250 J/g

Maximum Temperature: Mechanical

410 °C 770 °F

Melting Completion (Liquidus)

1460 °C 2670 °F

Melting Onset (Solidus)

1420 °C 2590 °F

Specific Heat Capacity

470 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

39 W/m-K 22 BTU/h-ft-°F

Thermal Expansion

13 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

7.3 % IACS

Electrical Conductivity: Equal Weight (Specific)

8.4 % IACS

Otherwise Unclassified Properties

Base Metal Price

2.8 % relative

Density

7.9 g/cm3 490 lb/ft3

Embodied Carbon

1.6 kg CO2/kg material

Embodied Energy

22 MJ/kg 9.3 x 103 BTU/lb

Embodied Water

50 L/kg 6.0 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

130 MJ/m3

Resilience: Unit (Modulus of Resilience)

550 kJ/m3

Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

22 points

Strength to Weight: Bending

20 points

Thermal Diffusivity

10 mm2/s

Thermal Shock Resistance

18 points

Alloy Composition

Among alloy steels, the composition of EN 1.6308 steel is notable for containing a comparatively high amount of manganese (Mn). Manganese is used to improve hardenability, hot workability, and surface quality. There is some loss of ductility and weldability, however.

Iron (Fe) 96.4 to 97.9
Manganese (Mn) 1.2 to 1.6
Nickel (Ni) 0.5 to 0.8
Molybdenum (Mo) 0.45 to 0.55
Silicon (Si) 0 to 0.4
Carbon (C) 0 to 0.2
Vanadium (V) 0 to 0.030
Phosphorus (P) 0 to 0.025
Sulfur (S) 0 to 0.015

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

Followup Questions

Similar Alloys

Further Reading

EN 10222-2: Steel forgings for pressure purposes - Part 2: Ferritic and martensitic steels with specified elevated temperature properties

Manufacture and Uses of Alloy Steels, Henry D. Hibbard, 2005

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

Steels: Processing, Structure, and Performance, 2nd ed., George Krauss, 2015