These are the material constants behind every spring calculation on the site. The
shear modulus G sets the spring rate; the allowable stress (a fraction of
tensile strength) sets how hard the spring can work. Because tensile strength rises as
wire gets thinner — Sᵤₜ(d) = A / d^m — the allowable is given as a percentage
of Sᵤₜ rather than a single number.
| Material | Standard | G — GPa (Mpsi) | E — GPa | Density (kg/m³) | Max static τ | Notes |
|---|---|---|---|---|---|---|
| Music wire | ASTM A228 | 79.3 (11.5) | 207 | 7850 | 45% of Sᵤₜ | Highest tensile strength; best for small-diameter springs. |
| Oil-tempered | ASTM A229 | 77.2 (11.2) | 207 | 7850 | 50% of Sᵤₜ | General-purpose; not for shock or fatigue service. |
| Hard-drawn | ASTM A227 | 77.2 (11.2) | 207 | 7850 | 45% of Sᵤₜ | Lowest cost; general-purpose static service. |
| Chrome silicon | ASTM A401 | 77.2 (11.2) | 207 | 7850 | 50% of Sᵤₜ | High stress; shock, fatigue and moderately elevated temperature. |
| Chrome vanadium | ASTM A232 | 77.2 (11.2) | 207 | 7850 | 50% of Sᵤₜ | Shock loads and moderately elevated temperature. |
| Stainless 302/304 | ASTM A313 | 69 (10) | 193 | 7920 | 35% of Sᵤₜ | Corrosion resistant; lower shear modulus and allowable stress. |
Source: Standard spring-design references (Shigley, Mechanical Engineering Design, Tables 10-4/10-5/10-6; ASTM wire standards). Verify against the governing standard and supplier data for production design.