Search thermal conductivity values for metals and engineering alloys by grade, designation or material family. Compare heat-transfer performance using W/m·K.
Thermal conductivity describes how readily heat moves through a material when a temperature difference exists. It is represented by k or λ and its SI unit is watts per metre-kelvin (W/m·K).
A material with a high thermal conductivity can transfer heat efficiently. Copper and aluminum are therefore widely used in heat exchangers, electrical equipment, heat sinks and other applications where efficient heat removal is important. Materials such as stainless steel and titanium have much lower thermal conductivity and can provide greater thermal resistance.
Thermal conductivity is different from thermal diffusivity. Conductivity describes the ability to conduct heat, while thermal diffusivity also considers density and specific heat capacity and describes how quickly a temperature disturbance spreads through a material.
| Material | Thermal Conductivity | Approx. W/m·K | Heat-Transfer Behavior |
|---|---|---|---|
| Silver | ~429 W/m·K | 429 | Very high |
| Copper | ~401 W/m·K | 401 | Very high |
| Aluminum | ~237 W/m·K | 237 | High |
| Gold | ~318 W/m·K | 318 | High |
| Brass | ~100–130 W/m·K | Varies by alloy | Moderate to high |
| Carbon Steel | ~45–60 W/m·K | Grade dependent | Moderate |
| 304 Stainless Steel | ~16 W/m·K | 16 | Low |
| 316 Stainless Steel | ~14 W/m·K | 14 | Low |
| Titanium Grade 5 | ~6.7 W/m·K | 6.7 | Very low |
| Material Family | Typical Behavior | Engineering Consideration |
|---|---|---|
| Copper | Very high conductivity | Excellent for heat exchangers, heat sinks and electrical components where heat must be moved efficiently. |
| Aluminum | High conductivity | Combines good heat transfer with low density, making it useful for lightweight thermal components. |
| Brass & Bronze | Moderate conductivity | Conductivity varies considerably with alloy composition and is generally below pure copper. |
| Carbon Steel | Moderate conductivity | Thermal conductivity depends on grade, temperature and microstructure. |
| Stainless Steel | Low conductivity | Useful when corrosion resistance and strength are more important than rapid heat transfer. |
| Titanium | Very low conductivity | Useful where high strength-to-weight ratio and corrosion resistance are important. |
| Nickel Alloys | Generally low to moderate | Often selected for high-temperature and corrosion resistance rather than maximum heat transfer. |
Thermal conductivity should not be confused with thermal diffusivity. A material can have relatively high conductivity but also high density and heat capacity, affecting how rapidly its temperature changes.
Thermal diffusivity is calculated from:
α = k / (ρ × Cp)
| Property | Symbol | Unit | What It Describes |
|---|---|---|---|
| Thermal conductivity | k | W/m·K | Ability to conduct heat |
| Density | ρ | kg/m³ | Mass per unit volume |
| Specific heat capacity | Cp | J/kg·K | Energy needed to raise temperature |
| Thermal diffusivity | α | m²/s | Rate at which temperature changes spread |
| Factor | Effect | Why It Matters |
|---|---|---|
| Temperature | Can increase or decrease conductivity depending on material | High-temperature designs should use temperature-specific property data. |
| Alloy composition | Can substantially change conductivity | Pure metals and alloys of the same base metal may have very different thermal properties. |
| Heat treatment | Can alter conductivity | Microstructure and precipitation can influence heat transport. |
| Purity | Impurities often reduce conductivity in pure metals | High-purity copper and other metals can conduct heat more efficiently. |
| Porosity | Generally reduces effective conductivity | Voids interrupt conductive heat paths. |
| Surface/contact condition | Can dominate actual interface heat transfer | Contact resistance can be significant even when bulk conductivity is high. |
Thermal conductivity data is important when designing heat sinks, heat exchangers, radiators, molds, dies, electrical enclosures, engine components, furnace equipment and other systems exposed to temperature gradients.
For a simple one-dimensional steady-state conduction problem, Fourier's law can be expressed as:
Q = kAΔT / L
where Q is heat-transfer rate, k is thermal conductivity, A is cross-sectional area, ΔT is the temperature difference and L is the heat-flow distance. This relationship shows why high-conductivity materials can transfer more heat through the same geometry and temperature difference.
What is thermal conductivity? Thermal conductivity measures how readily heat is conducted through a material. Its SI unit is W/m·K.
Which common metal has the highest thermal conductivity? Silver has extremely high thermal conductivity, followed closely by copper. Copper is much more widely used because it offers excellent thermal performance at substantially lower cost.
Is copper more thermally conductive than aluminum? Yes. Pure copper is generally around 400 W/m·K, while pure aluminum is around 237 W/m·K near room temperature.
Why is aluminum used for heat sinks? Aluminum combines good thermal conductivity with low density, relatively low cost and good manufacturability. These characteristics make it useful for lightweight heat sinks and thermal structures.
Why does stainless steel have low thermal conductivity? Stainless steel's alloying elements and crystal structure result in much lower thermal conductivity than highly conductive metals such as copper and aluminum.
Is titanium a good thermal conductor? No. Titanium has relatively low thermal conductivity. It is generally selected for strength, corrosion resistance and low density rather than rapid heat transfer.
Does temperature affect thermal conductivity? Yes. Thermal conductivity can change significantly with temperature. The relationship depends on the particular metal or alloy.
Does alloying reduce thermal conductivity? Alloying often reduces the thermal conductivity of a pure metal, although the exact effect depends on alloy composition and microstructure.
Is thermal conductivity the same as thermal resistance? No. Conductivity is a material property describing heat conduction. Thermal resistance describes opposition to heat flow through a particular component or thermal path and depends on both material and geometry.
Can these values be used for engineering design? They are useful reference values for material comparison. Final engineering calculations should use temperature-specific data from the applicable material specification or manufacturer because conductivity varies with grade, condition and temperature.