EN 1.7779 (20CrMoV13-5-5) Chromium Steel
EN 1.7779 steel is an alloy steel formulated for primary forming into wrought products. Cited properties are appropriate for the quenched and tempered condition. 1.7779 is the EN numeric designation for this material. 20CrMoV13-5-5 is the EN chemical designation.
It has a very high embodied energy among EN wrought alloy steels. In addition, it has a fairly low thermal conductivity and a fairly high base cost.
The graph bars on the material properties cards below compare EN 1.7779 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
240
Elastic (Young's, Tensile) Modulus
190 GPa 27 x 106 psi
Elongation at Break
16 %
Fatigue Strength
430 MPa 63 x 103 psi
Impact Strength: V-Notched Charpy
38 J 28 ft-lb
Poisson's Ratio
0.29
Shear Modulus
73 GPa 11 x 106 psi
Shear Strength
500 MPa 72 x 103 psi
Tensile Strength: Ultimate (UTS)
810 MPa 120 x 103 psi
Tensile Strength: Yield (Proof)
660 MPa 96 x 103 psi
Thermal Properties
Latent Heat of Fusion
260 J/g
Maximum Temperature: Mechanical
470 °C 880 °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 23 BTU/h-ft-°F
Thermal Expansion
13 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
7.7 % IACS
Electrical Conductivity: Equal Weight (Specific)
8.9 % IACS
Otherwise Unclassified Properties
Base Metal Price
4.0 % relative
Density
7.8 g/cm3 490 lb/ft3
Embodied Carbon
2.8 kg CO2/kg material
Embodied Energy
41 MJ/kg 18 x 103 BTU/lb
Embodied Water
64 L/kg 7.7 gal/lb
Common Calculations
PREN (Pitting Resistance)
5.0
Resilience: Ultimate (Unit Rupture Work)
120 MJ/m3
Resilience: Unit (Modulus of Resilience)
1150 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
29 points
Strength to Weight: Bending
25 points
Thermal Diffusivity
11 mm2/s
Thermal Shock Resistance
23 points
Alloy Composition
Among alloy steels, the composition of EN 1.7779 steel is notable for containing a comparatively high amount of chromium (Cr) and including aluminum (Al). Chromium is used to improve corrosion resistance and most mechanical properties (particularly at higher temperatures). Aluminum is used to control grain size and to deoxidize. Deoxidizing is required to control the effects of some other alloying elements.
| Fe | 93.8 to 95.4 | |
| Cr | 3.0 to 3.3 | |
| Mo | 0.5 to 0.6 | |
| V | 0.45 to 0.55 | |
| Mn | 0.3 to 0.5 | |
| Si | 0.15 to 0.35 | |
| C | 0.17 to 0.23 | |
| Ni | 0 to 0.3 | |
| Cu | 0 to 0.3 | |
| Al | 0 to 0.040 | |
| P | 0 to 0.025 | |
| S | 0 to 0.010 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
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
Microstructure of Steels and Cast Irons, Madeleine Durand-Charre, 2004
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