EN 1.6311 (20MnMoNi4-5) Molybdenum Steel
EN 1.6311 steel is an alloy steel formulated for primary forming into wrought products. Cited properties are appropriate for the quenched and tempered condition. 1.6311 is the EN numeric designation for this material. 20MnMoNi4-5 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 high base cost.
The graph bars on the material properties cards below compare EN 1.6311 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
Elastic (Young's, Tensile) Modulus
190 GPa 27 x 106 psi
Elongation at Break
19 %
Fatigue Strength
340 MPa 49 x 103 psi
Impact Strength: V-Notched Charpy
51 J 38 ft-lb
Poisson's Ratio
0.29
Shear Modulus
73 GPa 11 x 106 psi
Shear Strength
400 MPa 59 x 103 psi
Tensile Strength: Ultimate (UTS)
650 MPa 94 x 103 psi
Tensile Strength: Yield (Proof)
490 MPa 72 x 103 psi
Thermal Properties
Latent Heat of Fusion
250 J/g
Maximum Temperature: Mechanical
410 °C 780 °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
7.4 % IACS
Electrical Conductivity: Equal Weight (Specific)
8.5 % IACS
Otherwise Unclassified Properties
Base Metal Price
2.9 % 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
51 L/kg 6.1 gal/lb
Common Calculations
PREN (Pitting Resistance)
2.1
Resilience: Ultimate (Unit Rupture Work)
120 MJ/m3
Resilience: Unit (Modulus of Resilience)
650 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
23 points
Strength to Weight: Bending
21 points
Thermal Diffusivity
10 mm2/s
Thermal Shock Resistance
19 points
Alloy Composition
Among alloy steels, the composition of EN 1.6311 steel is notable for containing a comparatively high amount of manganese (Mn) and including nitrogen (N). Manganese is used to improve hardenability, hot workability, and surface quality. There is some loss of ductility and weldability, however. Nitrogen has a substantial strengthening effect, but may contribute to strain aging unless the steel is deoxidized with aluminum.
| Fe | 95.9 to 98 | |
| Mn | 1.0 to 1.5 | |
| Ni | 0.4 to 0.8 | |
| Mo | 0.45 to 0.6 | |
| Cr | 0 to 0.5 | |
| Si | 0 to 0.4 | |
| C | 0.15 to 0.23 | |
| Cu | 0 to 0.2 | |
| P | 0 to 0.035 | |
| S | 0 to 0.035 | |
| V | 0 to 0.020 | |
| N | 0 to 0.012 |
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 10250-3: Open die steel forgings for general engineering purposes - Part 3: Alloy special steels
Pressure Vessels: External Pressure Technology, 2nd ed., Carl T. F. Ross, 2011
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