# 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 10 ^{6} psi*

Elongation at Break

12 *%*

Fatigue Strength

1280 *MPa* 190 *x 10 ^{3} psi*

Poisson's Ratio

0.29

Shear Modulus

72 *GPa* 10 *x 10 ^{6} psi*

Shear Strength

1470 *MPa* 210 *x 10 ^{3} psi*

Tensile Strength: Ultimate (UTS)

2450 *MPa* 360 *x 10 ^{3} psi*

Tensile Strength: Yield (Proof)

2050 *MPa* 300 *x 10 ^{3} 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/cm ^{3}* 490

*lb/ft*

^{3}Embodied Carbon

1.4 *kg CO _{2}/kg material*

Embodied Energy

19 *MJ/kg* 8.0 *x 10 ^{3} BTU/lb*

Embodied Water

45 *L/kg* 5.4 *gal/lb*

## Common Calculations

Resilience: Ultimate (Unit Rupture Work)

280 *MJ/m ^{3}*

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 *m ^{2}/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