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.
| Fe | 94.8 to 97 | |
| Cr | 0.9 to 1.2 | |
| Mo | 0.9 to 1.1 | |
| V | 0.6 to 0.8 | |
| Mn | 0.35 to 0.75 | |
| C | 0.17 to 0.23 | |
| Si | 0 to 0.4 | |
| Ti | 0.070 to 0.15 | |
| Ni | 0 to 0.2 | |
| Cu | 0 to 0.2 | |
| Al | 0.015 to 0.080 | |
| P | 0 to 0.020 | |
| Sn | 0 to 0.020 | |
| As | 0 to 0.020 | |
| S | 0 to 0.015 | |
| 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