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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.

Iron (Fe) 98 to 98.9
Manganese (Mn) 0.9 to 1.2
Carbon (C) 0.16 to 0.2
Silicon (Si) 0 to 0.3
Copper (Cu) 0 to 0.25
Phosphorus (P) 0 to 0.025
Sulfur (S) 0 to 0.025
Boron (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