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EN 1.5535 (23MnB4) Boron Steel

EN 1.5535 steel is an alloy steel formulated for primary forming into wrought products. 1.5535 is the EN numeric designation for this material. 23MnB4 is the EN chemical designation.

It has a moderately low embodied energy among EN wrought alloy steels. In addition, it has a very low base cost and a fairly high thermal conductivity.

The properties of EN 1.5535 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 1.5535 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 22 %

Fatigue Strength

210 to 320 MPa 31 to 47 x 103 psi

Poisson's Ratio

0.29

Reduction in Area

62 to 72 %

Shear Modulus

73 GPa 11 x 106 psi

Shear Strength

320 to 370 MPa 46 to 53 x 103 psi

Tensile Strength: Ultimate (UTS)

450 to 1490 MPa 65 to 220 x 103 psi

Tensile Strength: Yield (Proof)

300 to 500 MPa 44 to 73 x 103 psi

Thermal Properties

Latent Heat of Fusion

250 J/g

Maximum Temperature: Mechanical

400 °C 760 °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

50 W/m-K 29 BTU/h-ft-°F

Thermal Expansion

13 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

7.2 % IACS

Electrical Conductivity: Equal Weight (Specific)

8.2 % 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

48 L/kg 5.7 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

45 to 250 MJ/m3

Resilience: Unit (Modulus of Resilience)

240 to 680 kJ/m3

Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

16 to 53 points

Strength to Weight: Bending

17 to 37 points

Thermal Diffusivity

13 mm2/s

Thermal Shock Resistance

13 to 44 points

Alloy Composition

Among alloy steels, the composition of EN 1.5535 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) 97.6 to 98.9
Manganese (Mn) 0.9 to 1.2
Carbon (C) 0.2 to 0.25
Silicon (Si) 0 to 0.3
Chromium (Cr) 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

EN 10269: Steels and nickel alloys for fasteners with specified elevated and/or low temperature properties

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

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

CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015

Steels: Processing, Structure, and Performance, 2nd ed., George Krauss, 2015