EN 1.5538 (37MnB5) Boron Steel
EN 1.5538 steel is an alloy steel formulated for primary forming into wrought products. 1.5538 is the EN numeric designation for this material. 37MnB5 is the EN chemical designation.
It has a moderately low embodied energy among EN wrought alloy steels. In addition, it has a very high thermal conductivity and a fairly low base cost.
The properties of EN 1.5538 steel include three 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 1.5538 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
160 to 190
Elastic (Young's, Tensile) Modulus
190 GPa 27 x 106 psi
Poisson's Ratio
0.29
Reduction in Area
64 to 69 %
Shear Modulus
73 GPa 11 x 106 psi
Tensile Strength: Ultimate (UTS)
530 to 1810 MPa 77 to 260 x 103 psi
Thermal Properties
Latent Heat of Fusion
250 J/g
Maximum Temperature: Mechanical
400 °C 760 °F
Melting Completion (Liquidus)
1460 °C 2650 °F
Melting Onset (Solidus)
1420 °C 2580 °F
Specific Heat Capacity
470 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
51 W/m-K 30 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
2.0 % relative
Density
7.8 g/cm3 490 lb/ft3
Embodied Carbon
1.4 kg CO2/kg material
Embodied Energy
19 MJ/kg 8.1 x 103 BTU/lb
Embodied Water
48 L/kg 5.7 gal/lb
Common Calculations
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
19 to 64 points
Strength to Weight: Bending
19 to 42 points
Thermal Diffusivity
14 mm2/s
Thermal Shock Resistance
16 to 53 points
Alloy Composition
Among alloy steels, the composition of EN 1.5538 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 98.5 | |
| Mn | 1.2 to 1.5 | |
| C | 0.35 to 0.4 | |
| Si | 0 to 0.3 | |
| Cr | 0 to 0.3 | |
| 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
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