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EN 1.8515 (31CrMo12) Nitriding Steel

EN 1.8515 steel is an alloy steel formulated for primary forming into wrought products. Cited properties are appropriate for the quenched and tempered condition. 1.8515 is the EN numeric designation for this material. 31CrMo12 is the EN chemical designation.

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

The graph bars on the material properties cards below compare EN 1.8515 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

340

Elastic (Young's, Tensile) Modulus

190 GPa 27 x 106 psi

Elongation at Break

11 %

Fatigue Strength

580 MPa 84 x 103 psi

Impact Strength: V-Notched Charpy

29 J 21 ft-lb

Poisson's Ratio

0.29

Shear Modulus

74 GPa 11 x 106 psi

Shear Strength

680 MPa 98 x 103 psi

Tensile Strength: Ultimate (UTS)

1130 MPa 160 x 103 psi

Tensile Strength: Yield (Proof)

940 MPa 140 x 103 psi

Thermal Properties

Latent Heat of Fusion

250 J/g

Maximum Temperature: Mechanical

470 °C 880 °F

Melting Completion (Liquidus)

1460 °C 2660 °F

Melting Onset (Solidus)

1420 °C 2580 °F

Specific Heat Capacity

470 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

40 W/m-K 23 BTU/h-ft-°F

Thermal Expansion

13 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

7.6 % IACS

Electrical Conductivity: Equal Weight (Specific)

8.7 % IACS

Otherwise Unclassified Properties

Base Metal Price

3.5 % relative

Density

7.8 g/cm3 490 lb/ft3

Embodied Carbon

1.6 kg CO2/kg material

Embodied Energy

22 MJ/kg 9.4 x 103 BTU/lb

Embodied Water

60 L/kg 7.2 gal/lb

Common Calculations

PREN (Pitting Resistance)

4.4

Resilience: Ultimate (Unit Rupture Work)

120 MJ/m3

Resilience: Unit (Modulus of Resilience)

2310 kJ/m3

Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

40 points

Strength to Weight: Bending

31 points

Thermal Diffusivity

11 mm2/s

Thermal Shock Resistance

33 points

Alloy Composition

Among alloy steels, the composition of EN 1.8515 steel is notable for containing a comparatively high amount of chromium (Cr). Chromium is used to improve corrosion resistance and most mechanical properties (particularly at higher temperatures).

Iron (Fe) 94.7 to 96.5
Chromium (Cr) 2.8 to 3.3
Manganese (Mn) 0.4 to 0.7
Molybdenum (Mo) 0.3 to 0.5
Carbon (C) 0.28 to 0.35
Silicon (Si) 0 to 0.4
Nickel (Ni) 0 to 0.3
Sulfur (S) 0 to 0.035
Phosphorus (P) 0 to 0.025

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

ISO 683-5: Heat treatable steels, alloy steels and free-cutting steels - Part 5: Nitriding steels

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