The strength of most metals is significantly influenced by temperature. For ferrous metals (like steel and cast iron), tensile strength typically reaches a maximum around 200°C (400°F). Beyond certain temperature thresholds, a critical material property—the modulus of elasticity (Young's modulus)—begins to decrease gradually, followed by a rapid decline at higher temperatures, indicating severe material degradation.

Strength Reduction Formula

The reduction in strength at elevated temperatures can be calculated using a temperature-dependent strength reduction factor. A simplified formula for calculating the adjusted ultimate tensile strength is:

$\sigma_{u,T} = k_T \cdot \sigma_{u}$

where:

$\sigma_{u,T}$ = Ultimate tensile strength at temperature $T$
$\sigma_{u}$ = Ultimate tensile strength at room temperature
$k_T$ = Strength reduction factor at temperature $T$ (dimensionless, ≤ 1)

Example Application (from source): For copper at 100°C, if the reduction factor $k_T = 0.95$ and the room temperature $\sigma_{u} = 220 \text{ MPa}$ : $\sigma_{u,100°C} = 0.95 \times 220 \text{ MPa} = 209 \text{ MPa}$

Common Metals Affected by Temperature

The following metals and alloys exhibit significant temperature-dependent strength characteristics:

Bronze
Copper
Structural Steel
Cast Steel
Cast Iron
Wrought Iron
Stainless Steel (e.g., 304N)

References

Original Source

Source: engineeringtoolbox.com