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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.

Iron (Fe) 93.8 to 95.4
Chromium (Cr) 3.0 to 3.3
Molybdenum (Mo) 0.5 to 0.6
Vanadium (V) 0.45 to 0.55
Manganese (Mn) 0.3 to 0.5
Silicon (Si) 0.15 to 0.35
Carbon (C) 0.17 to 0.23
Nickel (Ni) 0 to 0.3
Copper (Cu) 0 to 0.3
Aluminum (Al) 0 to 0.040
Phosphorus (P) 0 to 0.025
Sulfur (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