ASTM A231 Chromium-Vanadium Spring Steel
ASTM A231 spring steel is an alloy steel formulated for primary forming into wrought products. Cited properties are appropriate for the quenched and tempered condition.
It has a very high tensile strength among wrought alloy steels in the same category. In addition, it has a very low ductility and a fairly high thermal conductivity.
The graph bars on the material properties cards below compare ASTM A231 spring steel to: wrought alloy steels in the same category (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
540
Elastic (Young's, Tensile) Modulus
190 GPa 27 x 106 psi
Elongation at Break
14 %
Fatigue Strength
1000 MPa 150 x 103 psi
Poisson's Ratio
0.29
Reduction in Area
46 %
Shear Modulus
73 GPa 11 x 106 psi
Shear Strength
1080 MPa 160 x 103 psi
Tensile Strength: Ultimate (UTS)
1790 MPa 260 x 103 psi
Tensile Strength: Yield (Proof)
1570 MPa 230 x 103 psi
Thermal Properties
Latent Heat of Fusion
250 J/g
Maximum Temperature: Mechanical
420 °C 790 °F
Melting Completion (Liquidus)
1460 °C 2650 °F
Melting Onset (Solidus)
1410 °C 2580 °F
Specific Heat Capacity
470 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
52 W/m-K 30 BTU/h-ft-°F
Thermal Expansion
13 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
7.3 % IACS
Electrical Conductivity: Equal Weight (Specific)
8.4 % IACS
Otherwise Unclassified Properties
Base Metal Price
2.3 % relative
Density
7.8 g/cm3 490 lb/ft3
Embodied Carbon
2.0 kg CO2/kg material
Embodied Energy
28 MJ/kg 12 x 103 BTU/lb
Embodied Water
51 L/kg 6.1 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
230 MJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
64 points
Strength to Weight: Bending
42 points
Thermal Diffusivity
14 mm2/s
Thermal Shock Resistance
53 points
Alloy Composition
Among alloy steels, the composition of ASTM A231 spring steel is notable for including vanadium (V). Vanadium has a strong hardening effect, but this effect is particularly sensitive to the type of tempering.
| Fe | 96.7 to 97.7 | |
| Cr | 0.8 to 1.1 | |
| Mn | 0.7 to 0.9 | |
| C | 0.48 to 0.53 | |
| Si | 0.15 to 0.35 | |
| V | 0.15 to 0.3 | |
| P | 0 to 0.040 | |
| S | 0 to 0.040 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM A231: Standard Specification for Chromium-Vanadium Alloy Steel Spring Wire
Properties and Selection: Irons, Steels and High Performance Alloys, ASM Handbook vol. 1, ASM International, 1993
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