EN 1.8550 (34CrAlNi7-10) Nitriding Steel
EN 1.8550 steel is an alloy steel formulated for primary forming into wrought products. Cited properties are appropriate for the quenched and tempered condition. 1.8550 is the EN numeric designation for this material. 34CrAlNi7-10 is the EN chemical designation.
It has a moderately low melting temperature among EN wrought alloy steels. In addition, it has a moderately high electrical conductivity and a moderately low thermal conductivity.
The graph bars on the material properties cards below compare EN 1.8550 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
300
Elastic (Young's, Tensile) Modulus
190 GPa 27 x 106 psi
Elongation at Break
11 %
Fatigue Strength
470 MPa 68 x 103 psi
Impact Strength: V-Notched Charpy
34 J 25 ft-lb
Poisson's Ratio
0.29
Shear Modulus
73 GPa 11 x 106 psi
Shear Strength
600 MPa 87 x 103 psi
Tensile Strength: Ultimate (UTS)
1000 MPa 150 x 103 psi
Tensile Strength: Yield (Proof)
760 MPa 110 x 103 psi
Thermal Properties
Latent Heat of Fusion
250 J/g
Maximum Temperature: Mechanical
440 °C 820 °F
Melting Completion (Liquidus)
1450 °C 2640 °F
Melting Onset (Solidus)
1410 °C 2570 °F
Specific Heat Capacity
480 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)
8.8 % IACS
Otherwise Unclassified Properties
Base Metal Price
3.4 % relative
Density
7.8 g/cm3 490 lb/ft3
Embodied Carbon
1.7 kg CO2/kg material
Embodied Energy
23 MJ/kg 9.8 x 103 BTU/lb
Embodied Water
67 L/kg 8.0 gal/lb
Common Calculations
PREN (Pitting Resistance)
2.3
Resilience: Ultimate (Unit Rupture Work)
100 MJ/m3
Resilience: Unit (Modulus of Resilience)
1550 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
36 points
Strength to Weight: Bending
29 points
Thermal Diffusivity
11 mm2/s
Thermal Shock Resistance
29 points
Alloy Composition
Among alloy steels, the composition of EN 1.8550 steel is notable for including aluminum (Al) and nickel (Ni). Aluminum is used to control grain size and to deoxidize. Deoxidizing is required to control the effects of some other alloying elements. Nickel is used to improve mechanical properties, and to make the alloy easier to heat treat.
| Fe | 94.4 to 96.3 | |
| Cr | 1.5 to 1.8 | |
| Ni | 0.85 to 1.2 | |
| Al | 0.8 to 1.2 | |
| Mn | 0.4 to 0.7 | |
| C | 0.3 to 0.37 | |
| Si | 0 to 0.4 | |
| Mo | 0.15 to 0.25 | |
| 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