Length change ΔL
mm
— in
Thermal engineering · Material
Steel thermal expansion calculator
Calculate thermal expansion or contraction for steel using an initial coefficient α = 12 × 10⁻⁶ K⁻¹, editable for the actual grade.
Created v1.0
By Thibaut Grzelak, Mechanical Analysis Engineer
02
ExpansionResults
Final length
m
L = L₀ + ΔL
Thermal strain
µε
εth = α · ΔT
Relative change
%
ΔL / L₀
Numerical substitution
—Typical indicative value. Check the grade and project temperature range.
Free expansion, homogeneous material and constant coefficient over the temperature interval. A restrained part requires a thermal-stress calculation.
Reference example
Steel: 2 m length and 40°C temperature change
With α = 12 × 10⁻⁶ K⁻¹, the change is ΔL = 12 × 10⁻⁶ × 2 × 40 = 0.96 mm.
Compare with other materialsFree material expansion
Thermal-expansion formula, coefficient and units
Length change depends on L₀, α and ΔT. For a temperature interval, 1 K and 1 °C have the same magnitude.
Linear-expansion equation
A positive ΔT produces expansion; a negative ΔT produces contraction.
ΔL = α · L₀ · ΔTSteel
With α ≈ 12 × 10⁻⁶ K⁻¹, a 2 m bar heated by 40 K expands by about 0.96 mm.
Aluminum
With α ≈ 23 × 10⁻⁶ K⁻¹, the same case produces about 1.84 mm.
Restrained expansion
Full restraint can create thermal stress that also depends on modulus E.
σth ≈ E · α · ΔT