ASTM A228 (SWP-A, K08500) Music Wire
ASTM A228 music wire is a carbon (non-alloy) steel formulated for primary forming into wrought products. Cited properties are appropriate for the cold worked (strain hardened) condition. ASTM A228 is the defining standard for this material. K08500 is the UNS number.
It has the highest tensile strength among wrought carbon or non-alloy steels. In addition, it has a fairly low ductility and a moderately low thermal conductivity.
The graph bars on the material properties cards below compare ASTM A228 music wire 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
710
Elastic (Young's, Tensile) Modulus
190 GPa 27 x 106 psi
Elongation at Break
12 %
Fatigue Strength
1280 MPa 190 x 103 psi
Poisson's Ratio
0.29
Shear Modulus
72 GPa 10 x 106 psi
Shear Strength
1470 MPa 210 x 103 psi
Tensile Strength: Ultimate (UTS)
2450 MPa 360 x 103 psi
Tensile Strength: Yield (Proof)
2050 MPa 300 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
49 W/m-K 28 BTU/h-ft-°F
Thermal Expansion
12 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
7.1 % IACS
Electrical Conductivity: Equal Weight (Specific)
8.2 % 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
45 L/kg 5.4 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
280 MJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
87 points
Strength to Weight: Bending
52 points
Thermal Diffusivity
13 mm2/s
Thermal Shock Resistance
79 points
Alloy Composition
| Fe | 98 to 99 | |
| C | 0.7 to 1.0 | |
| Mn | 0.2 to 0.6 | |
| Si | 0.1 to 0.3 | |
| S | 0 to 0.030 | |
| P | 0 to 0.025 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM A228: Standard Specification for Steel Wire, Music Spring Quality
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