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EN 1.7729 (20CrMoVTiB4-10) Steel

EN 1.7729 steel is an alloy steel formulated for primary forming into wrought products. Cited properties are appropriate for the quenched and tempered condition. 1.7729 is the EN numeric designation for this material. 20CrMoVTiB4-10 is the EN chemical designation.

It has a very high embodied energy among EN wrought alloy steels. In addition, it has a very high melting temperature and a fairly high base cost.

The graph bars on the material properties cards below compare EN 1.7729 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

270

Elastic (Young's, Tensile) Modulus

190 GPa 27 x 106 psi

Elongation at Break

17 %

Fatigue Strength

500 MPa 73 x 103 psi

Impact Strength: V-Notched Charpy

46 J 34 ft-lb

Poisson's Ratio

0.29

Reduction in Area

56 %

Shear Modulus

73 GPa 11 x 106 psi

Shear Strength

560 MPa 81 x 103 psi

Tensile Strength: Ultimate (UTS)

910 MPa 130 x 103 psi

Tensile Strength: Yield (Proof)

750 MPa 110 x 103 psi

Thermal Properties

Latent Heat of Fusion

250 J/g

Maximum Temperature: Mechanical

430 °C 810 °F

Melting Completion (Liquidus)

1470 °C 2680 °F

Melting Onset (Solidus)

1430 °C 2610 °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

7.6 % IACS

Electrical Conductivity: Equal Weight (Specific)

8.7 % IACS

Otherwise Unclassified Properties

Base Metal Price

3.8 % relative

Density

7.8 g/cm3 490 lb/ft3

Embodied Carbon

3.3 kg CO2/kg material

Embodied Energy

49 MJ/kg 21 x 103 BTU/lb

Embodied Water

59 L/kg 7.0 gal/lb

Common Calculations

PREN (Pitting Resistance)

4.4

Resilience: Ultimate (Unit Rupture Work)

150 MJ/m3

Resilience: Unit (Modulus of Resilience)

1500 kJ/m3

Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

32 points

Strength to Weight: Bending

27 points

Thermal Diffusivity

11 mm2/s

Thermal Shock Resistance

27 points

Alloy Composition

Among alloy steels, the composition of EN 1.7729 steel is notable for including boron (B) and titanium (Ti). Boron is used to improve hardenability. It has a substantial effect when added in even tiny amounts. Titanium is used to broadly improve mechanical properties.

Iron (Fe) 94.8 to 97
Chromium (Cr) 0.9 to 1.2
Molybdenum (Mo) 0.9 to 1.1
Vanadium (V) 0.6 to 0.8
Manganese (Mn) 0.35 to 0.75
Carbon (C) 0.17 to 0.23
Silicon (Si) 0 to 0.4
Titanium (Ti) 0.070 to 0.15
Nickel (Ni) 0 to 0.2
Copper (Cu) 0 to 0.2
Aluminum (Al) 0.015 to 0.080
Phosphorus (P) 0 to 0.020
Tin (Sn) 0 to 0.020
Arsenic (As) 0 to 0.020
Sulfur (S) 0 to 0.015
Boron (B) 0.0010 to 0.010

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

Microstructure of Steels and Cast Irons, Madeleine Durand-Charre, 2004

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