EN 1.5521 (18MnB4) Boron Steel
EN 1.5521 steel is an alloy steel formulated for primary forming into wrought products. 1.5521 is the EN numeric designation for this material. 18MnB4 is the EN chemical designation.
It has a fairly low electrical conductivity among EN wrought alloy steels. In addition, it has a moderately low embodied energy and a very low base cost.
The properties of EN 1.5521 steel include five 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 1.5521 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
130 to 180
Elastic (Young's, Tensile) Modulus
190 GPa 27 x 106 psi
Elongation at Break
11 to 21 %
Fatigue Strength
210 to 310 MPa 31 to 46 x 103 psi
Poisson's Ratio
0.29
Reduction in Area
59 to 72 %
Shear Modulus
73 GPa 11 x 106 psi
Shear Strength
310 to 360 MPa 45 to 52 x 103 psi
Tensile Strength: Ultimate (UTS)
430 to 1390 MPa 62 to 200 x 103 psi
Tensile Strength: Yield (Proof)
300 to 490 MPa 44 to 71 x 103 psi
Thermal Properties
Latent Heat of Fusion
250 J/g
Maximum Temperature: Mechanical
400 °C 750 °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
51 W/m-K 30 BTU/h-ft-°F
Thermal Expansion
13 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
7.1 % IACS
Electrical Conductivity: Equal Weight (Specific)
8.1 % IACS
Otherwise Unclassified Properties
Base Metal Price
1.9 % relative
Density
7.8 g/cm3 490 lb/ft3
Embodied Carbon
1.4 kg CO2/kg material
Embodied Energy
19 MJ/kg 8.0 x 103 BTU/lb
Embodied Water
47 L/kg 5.6 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
44 to 230 MJ/m3
Resilience: Unit (Modulus of Resilience)
250 to 630 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
15 to 49 points
Strength to Weight: Bending
16 to 35 points
Thermal Diffusivity
14 mm2/s
Thermal Shock Resistance
13 to 41 points
Alloy Composition
Among alloy steels, the composition of EN 1.5521 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 | 98 to 98.9 | |
| Mn | 0.9 to 1.2 | |
| C | 0.16 to 0.2 | |
| Si | 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 10263-3: Steel rod, bars and wire for cold heading and cold extrusion - Part 3: Technical delivery conditions for case hardening steels
Microstructure of Steels and Cast Irons, Madeleine Durand-Charre, 2004
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