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).
| Fe | 94.7 to 96.5 | |
| Cr | 2.8 to 3.3 | |
| Mn | 0.4 to 0.7 | |
| Mo | 0.3 to 0.5 | |
| C | 0.28 to 0.35 | |
| Si | 0 to 0.4 | |
| Ni | 0 to 0.3 | |
| S | 0 to 0.035 | |
| 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