ASTM A229 Oil-Tempered Spring Steel
ASTM A229 spring steel is a carbon (non-alloy) steel formulated for primary forming into wrought products. It can have a very high tensile strength and has a moderately low ductility among wrought carbon or non-alloy steels.
The properties of ASTM A229 spring steel include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare ASTM A229 spring steel to: wrought carbon or non-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
490 to 550
Elastic (Young's, Tensile) Modulus
190 GPa 27 x 106 psi
Elongation at Break
14 %
Fatigue Strength
710 to 790 MPa 100 to 110 x 103 psi
Poisson's Ratio
0.29
Shear Modulus
72 GPa 10 x 106 psi
Shear Strength
1020 to 1140 MPa 150 to 170 x 103 psi
Tensile Strength: Ultimate (UTS)
1690 to 1890 MPa 240 to 270 x 103 psi
Tensile Strength: Yield (Proof)
1100 to 1230 MPa 160 to 180 x 103 psi
Thermal Properties
Latent Heat of Fusion
250 J/g
Maximum Temperature: Mechanical
400 °C 750 °F
Melting Completion (Liquidus)
1450 °C 2650 °F
Melting Onset (Solidus)
1410 °C 2570 °F
Specific Heat Capacity
470 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
50 W/m-K 29 BTU/h-ft-°F
Thermal Expansion
12 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
7.2 % IACS
Electrical Conductivity: Equal Weight (Specific)
8.3 % IACS
Otherwise Unclassified Properties
Base Metal Price
1.8 % relative
Density
7.8 g/cm3 490 lb/ft3
Embodied Carbon
1.4 kg CO2/kg material
Embodied Energy
19 MJ/kg 8.0 x 103 BTU/lb
Embodied Water
46 L/kg 5.5 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
200 to 230 MJ/m3
Resilience: Unit (Modulus of Resilience)
3260 to 4080 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
60 to 67 points
Strength to Weight: Bending
40 to 43 points
Thermal Diffusivity
14 mm2/s
Thermal Shock Resistance
54 to 60 points
Alloy Composition
| Fe | 97.5 to 99 | |
| Mn | 0.3 to 1.2 | |
| C | 0.55 to 0.85 | |
| Si | 0.15 to 0.35 | |
| S | 0 to 0.050 | |
| P | 0 to 0.040 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM A229: Standard Specification for Steel Wire, Oil-Tempered for Mechanical Springs
ASM Specialty Handbook: Carbon and Alloy Steels, J. R. Davis (editor), 1996
Ferrous Materials: Steel and Cast Iron, Hans Berns and Werner Theisen, 2008
Steels: Processing, Structure, and Performance, 2nd ed., George Krauss, 2015