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ASTM A232 Chromium-Vanadium Spring Steel

ASTM A232 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 A232 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

1040 MPa 150 x 103 psi

Poisson's Ratio

0.29

Reduction in Area

46 %

Shear Modulus

73 GPa 11 x 106 psi

Shear Strength

1090 MPa 160 x 103 psi

Tensile Strength: Ultimate (UTS)

1790 MPa 260 x 103 psi

Tensile Strength: Yield (Proof)

1610 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)

250 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 A232 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.

Iron (Fe) 96.8 to 97.7
Chromium (Cr) 0.8 to 1.1
Manganese (Mn) 0.7 to 0.9
Carbon (C) 0.48 to 0.53
Silicon (Si) 0.15 to 0.35
Vanadium (V) 0.15 to 0.3
Sulfur (S) 0 to 0.035
Phosphorus (P) 0 to 0.020

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

Followup Questions

Similar Alloys

Further Reading

ASTM A232: Standard Specification for Chromium-Vanadium Alloy Steel Valve Spring Quality 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

Steels: Processing, Structure, and Performance, 2nd ed., George Krauss, 2015