EN 1.6571 (20NiCrMoS6-4) Steel
EN 1.6571 steel is an alloy steel formulated for primary forming into wrought products. 1.6571 is the EN numeric designation for this material. 20NiCrMoS6-4 is the EN chemical designation.
It has a moderately high density among EN wrought alloy steels. In addition, it has a moderately low thermal conductivity and a moderately high base cost.
The properties of EN 1.6571 steel include four 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 1.6571 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
160 to 190
Elastic (Young's, Tensile) Modulus
190 GPa 27 x 106 psi
Poisson's Ratio
0.29
Shear Modulus
73 GPa 11 x 106 psi
Tensile Strength: Ultimate (UTS)
520 to 1460 MPa 76 to 210 x 103 psi
Thermal Properties
Latent Heat of Fusion
250 J/g
Maximum Temperature: Mechanical
420 °C 790 °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
40 W/m-K 23 BTU/h-ft-°F
Thermal Expansion
13 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
7.5 % IACS
Electrical Conductivity: Equal Weight (Specific)
8.6 % IACS
Otherwise Unclassified Properties
Base Metal Price
3.4 % relative
Density
7.9 g/cm3 490 lb/ft3
Embodied Carbon
1.7 kg CO2/kg material
Embodied Energy
22 MJ/kg 9.4 x 103 BTU/lb
Embodied Water
53 L/kg 6.4 gal/lb
Common Calculations
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
19 to 51 points
Strength to Weight: Bending
18 to 36 points
Thermal Diffusivity
11 mm2/s
Thermal Shock Resistance
15 to 43 points
Alloy Composition
Among alloy steels, the composition of EN 1.6571 steel is notable for including copper (Cu) and nickel (Ni). Copper is used to improve corrosion resistance, and to add at least some degree of precipitation hardenability. Nickel is used to improve mechanical properties, and to make the alloy easier to heat treat.
| Fe | 95.3 to 97.1 | |
| Ni | 1.4 to 1.7 | |
| Cr | 0.6 to 0.9 | |
| Mn | 0.5 to 0.9 | |
| Mo | 0.25 to 0.35 | |
| C | 0.16 to 0.23 | |
| Si | 0 to 0.3 | |
| Cu | 0 to 0.25 | |
| S | 0.020 to 0.040 | |
| P | 0 to 0.025 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
EN 10263-3: Steel rod, bars and wire for cold heading and cold extrusion - Part 3: Technical delivery conditions for case hardening steels
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