EN 1.6368 (15NiCuMoNb5-6-4) Nickel Steel
EN 1.6368 steel is an alloy steel formulated for primary forming into wrought products. 1.6368 is the EN numeric designation for this material. 15NiCuMoNb5-6-4 is the EN chemical designation.
It has a moderately high density among EN wrought alloy steels. In addition, it has a moderately low thermal conductivity and a moderately high base cost.
The properties of EN 1.6368 steel include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare EN 1.6368 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
200 to 210
Elastic (Young's, Tensile) Modulus
190 GPa 27 x 106 psi
Elongation at Break
18 %
Fatigue Strength
310 to 330 MPa 45 to 48 x 103 psi
Impact Strength: V-Notched Charpy
43 to 46 J 32 to 34 ft-lb
Poisson's Ratio
0.29
Shear Modulus
73 GPa 11 x 106 psi
Shear Strength
410 to 430 MPa 59 to 62 x 103 psi
Tensile Strength: Ultimate (UTS)
660 to 690 MPa 96 to 99 x 103 psi
Tensile Strength: Yield (Proof)
460 to 490 MPa 67 to 71 x 103 psi
Thermal Properties
Latent Heat of Fusion
250 J/g
Maximum Temperature: Mechanical
410 °C 770 °F
Melting Completion (Liquidus)
1460 °C 2660 °F
Melting Onset (Solidus)
1420 °C 2580 °F
Specific Heat Capacity
470 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
40 W/m-K 23 BTU/h-ft-°F
Thermal Expansion
13 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
7.5 % IACS
Electrical Conductivity: Equal Weight (Specific)
8.6 % IACS
Otherwise Unclassified Properties
Base Metal Price
3.4 % relative
Density
7.9 g/cm3 490 lb/ft3
Embodied Carbon
1.7 kg CO2/kg material
Embodied Energy
22 MJ/kg 9.4 x 103 BTU/lb
Embodied Water
53 L/kg 6.3 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
110 MJ/m3
Resilience: Unit (Modulus of Resilience)
580 to 650 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
23 to 24 points
Strength to Weight: Bending
21 to 22 points
Thermal Diffusivity
11 mm2/s
Thermal Shock Resistance
20 points
Alloy Composition
Among alloy steels, the composition of EN 1.6368 steel is notable for including niobium (Nb) and nitrogen (N). Niobium is primarily used to improve yield strength. Nitrogen has a substantial strengthening effect, but may contribute to strain aging unless the steel is deoxidized with aluminum.
| Fe | 95.1 to 97.2 | |
| Ni | 1.0 to 1.3 | |
| Mn | 0.8 to 1.2 | |
| Cu | 0.5 to 0.8 | |
| Si | 0.25 to 0.5 | |
| Mo | 0.25 to 0.5 | |
| Cr | 0 to 0.3 | |
| C | 0 to 0.17 | |
| Nb | 0.015 to 0.045 | |
| Al | 0.015 to 0.040 | |
| P | 0 to 0.025 | |
| N | 0 to 0.020 | |
| S | 0 to 0.010 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
EN 10028-2: Flat products made of steels for pressure purposes - Part 2: Non-alloy and alloy steels with specified elevated temperature properties
EN 10216-2: Seamless steel tubes for pressure purposes - Technical delivery conditions - Part 2: Non-alloy and alloy steel tubes with specified elevated temperature properties
Creep-Resistant Steels, Fujio Abe et al. (editors), 2008
Pressure Vessels: External Pressure Technology, 2nd ed., Carl T. F. Ross, 2011
ASM Specialty Handbook: Carbon and Alloy Steels, J. R. Davis (editor), 1996
Manufacture and Uses of Alloy Steels, Henry D. Hibbard, 2005
Ferrous Materials: Steel and Cast Iron, Hans Berns and Werner Theisen, 2008
Steels: Processing, Structure, and Performance, 2nd ed., George Krauss, 2015