EN 1.7272 (31CrMoB2-1) Boron Steel
EN 1.7272 steel is an alloy steel formulated for primary forming into wrought products. 1.7272 is the EN numeric designation for this material. 31CrMoB2-1 is the EN chemical designation.
It has a moderately low embodied energy among EN wrought alloy steels. In addition, it has a moderately low electrical conductivity and a moderately low base cost.
The properties of EN 1.7272 steel include four common variations. This page shows summary ranges across all of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare EN 1.7272 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
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)
490 to 1650 MPa 71 to 240 x 103 psi
Thermal Properties
Latent Heat of Fusion
250 J/g
Maximum Temperature: Mechanical
410 °C 770 °F
Melting Completion (Liquidus)
1460 °C 2660 °F
Melting Onset (Solidus)
1420 °C 2590 °F
Specific Heat Capacity
470 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
45 W/m-K 26 BTU/h-ft-°F
Thermal Expansion
13 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
7.2 % IACS
Electrical Conductivity: Equal Weight (Specific)
8.3 % IACS
Otherwise Unclassified Properties
Base Metal Price
2.2 % relative
Density
7.8 g/cm3 490 lb/ft3
Embodied Carbon
1.5 kg CO2/kg material
Embodied Energy
19 MJ/kg 8.3 x 103 BTU/lb
Embodied Water
49 L/kg 5.9 gal/lb
Common Calculations
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
17 to 59 points
Strength to Weight: Bending
18 to 40 points
Thermal Diffusivity
12 mm2/s
Thermal Shock Resistance
14 to 48 points
Alloy Composition
Among alloy steels, the composition of EN 1.7272 steel is notable for containing a comparatively high amount of manganese (Mn) and including boron (B). Manganese is used to improve hardenability, hot workability, and surface quality. There is some loss of ductility and weldability, however. Boron is used to improve hardenability. It has a substantial effect when added in even tiny amounts.
| Fe | 97.2 to 98.3 | |
| Mn | 0.9 to 1.2 | |
| Cr | 0.4 to 0.55 | |
| C | 0.28 to 0.33 | |
| Si | 0 to 0.3 | |
| Mo | 0.1 to 0.15 | |
| Cu | 0 to 0.25 | |
| P | 0 to 0.025 | |
| S | 0 to 0.025 | |
| B | 0.00080 to 0.0050 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
Boron in Steel, S. K. Banerji and J. E. Morral (editors), 1980
EN 10263-4: Steel rod, bars and wire for cold heading and cold extrusion - Part 4: Technical delivery conditions for steels for quenching and tempering
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