EN 1.7709 (21CrMoV5-7) Steel
EN 1.7709 steel is an alloy steel formulated for primary forming into wrought products. 1.7709 is the EN numeric designation for this material. 21CrMoV5-7 is the EN chemical designation.
It has a very low thermal conductivity among EN wrought alloy steels. In addition, it has a very high embodied energy and a moderately high base cost.
The properties of EN 1.7709 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 1.7709 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 230
Elastic (Young's, Tensile) Modulus
190 GPa 27 x 106 psi
Poisson's Ratio
0.29
Shear Modulus
73 GPa 11 x 106 psi
Tensile Strength: Ultimate (UTS)
650 to 780 MPa 95 to 110 x 103 psi
Thermal Properties
Latent Heat of Fusion
250 J/g
Maximum Temperature: Mechanical
440 °C 820 °F
Melting Completion (Liquidus)
1470 °C 2670 °F
Melting Onset (Solidus)
1420 °C 2600 °F
Specific Heat Capacity
470 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
33 W/m-K 19 BTU/h-ft-°F
Thermal Expansion
11 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
7.8 g/cm3 490 lb/ft3
Embodied Carbon
2.3 kg CO2/kg material
Embodied Energy
32 MJ/kg 14 x 103 BTU/lb
Embodied Water
56 L/kg 6.7 gal/lb
Common Calculations
PREN (Pitting Resistance)
3.6
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
23 to 27 points
Strength to Weight: Bending
21 to 24 points
Thermal Diffusivity
8.9 mm2/s
Thermal Shock Resistance
22 to 26 points
Alloy Composition
Among alloy steels, the composition of EN 1.7709 steel is notable for including aluminum (Al) and vanadium (V). Aluminum is used to control grain size and to deoxidize. Deoxidizing is required to control the effects of some other alloying elements. Vanadium has a strong hardening effect, but this effect is particularly sensitive to the type of tempering.
| Fe | 95.2 to 97.5 | |
| Cr | 1.2 to 1.5 | |
| Mo | 0.55 to 0.8 | |
| Mn | 0.4 to 0.8 | |
| Ni | 0 to 0.6 | |
| V | 0.2 to 0.35 | |
| C | 0.17 to 0.25 | |
| Si | 0 to 0.4 | |
| S | 0 to 0.030 | |
| Al | 0 to 0.030 | |
| P | 0 to 0.025 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
EN 10269: Steels and nickel alloys for fasteners with specified elevated and/or low temperature properties
Creep-Resistant Steels, Fujio Abe et al. (editors), 2008
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