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EN 1.7378 (7CrMoVTiB10-10) Chromium-Molybdenum Steel

EN 1.7378 steel is an alloy steel formulated for primary forming into wrought products. Cited properties are appropriate for the normalized and tempered condition. 1.7378 is the EN numeric designation for this material. 7CrMoVTiB10-10 is the EN chemical designation.

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

The graph bars on the material properties cards below compare EN 1.7378 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

210

Elastic (Young's, Tensile) Modulus

190 GPa 28 x 106 psi

Elongation at Break

17 %

Fatigue Strength

330 MPa 47 x 103 psi

Impact Strength: V-Notched Charpy

38 J 28 ft-lb

Poisson's Ratio

0.29

Shear Modulus

74 GPa 11 x 106 psi

Shear Strength

430 MPa 63 x 103 psi

Tensile Strength: Ultimate (UTS)

700 MPa 100 x 103 psi

Tensile Strength: Yield (Proof)

490 MPa 71 x 103 psi

Thermal Properties

Latent Heat of Fusion

260 J/g

Maximum Temperature: Mechanical

460 °C 860 °F

Melting Completion (Liquidus)

1470 °C 2680 °F

Melting Onset (Solidus)

1430 °C 2600 °F

Specific Heat Capacity

470 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

39 W/m-K 22 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

4.0 % relative

Density

7.8 g/cm3 490 lb/ft3

Embodied Carbon

2.3 kg CO2/kg material

Embodied Energy

33 MJ/kg 14 x 103 BTU/lb

Embodied Water

61 L/kg 7.2 gal/lb

Common Calculations

PREN (Pitting Resistance)

5.8

Resilience: Ultimate (Unit Rupture Work)

110 MJ/m3

Resilience: Unit (Modulus of Resilience)

630 kJ/m3

Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

25 points

Strength to Weight: Bending

22 points

Thermal Diffusivity

10 mm2/s

Thermal Shock Resistance

20 points

Alloy Composition

Among alloy steels, the composition of EN 1.7378 steel is notable for including boron (B) and titanium (Ti). Boron is used to improve hardenability. It has a substantial effect when added in even tiny amounts. Titanium is used to broadly improve mechanical properties.

Iron (Fe) 94.6 to 96.1
Chromium (Cr) 2.2 to 2.6
Molybdenum (Mo) 0.9 to 1.1
Manganese (Mn) 0.3 to 0.7
Silicon (Si) 0.15 to 0.45
Vanadium (V) 0.2 to 0.3
Carbon (C) 0.050 to 0.1
Titanium (Ti) 0.050 to 0.1
Phosphorus (P) 0 to 0.020
Aluminum (Al) 0 to 0.020
Sulfur (S) 0 to 0.010
Nitrogen (N) 0 to 0.010
Boron (B) 0.0015 to 0.0070

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

Followup Questions

Similar Alloys

Further Reading

EN 10216-2: Seamless steel tubes for pressure purposes - Technical delivery conditions - Part 2: Non-alloy and alloy steel tubes with specified elevated temperature properties

Pressure Vessels: External Pressure Technology, 2nd ed., Carl T. F. Ross, 2011

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