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Thermal Conductivity of Stainless Steel Explained & Chart
- John
In-depth study of the thermal conductivity of stainless steel is of great significance for optimizing material selection and improving equipment efficiency. We will discuss the thermal conductivity of stainless steel in detail, analyze the factors that affect thermal conductivity, and the practical application and importance of thermal conductivity. We have also compiled and included the thermal conductivity of common stainless steel grades and other metals to provide you with more intuitive data.
What is Thermal Conductivity?
Thermal conductivity (λ or k) is a measure of how fast heat is transferred through a given material under steady-state heat transfer conditions, and its units are W/(m·℃) or W/(m·K). Thermal conductivity is an important parameter that measures the ability of a material to conduct/transfer heat, with higher thermal conductivity transferring energy faster and vice versa.
What Is the K Value of Stainless Steel?
Stainless steel has a low thermal conductivity of about 15-25W/m·K, and is suitable for applications where low thermal conductivity is required. Thermal conductivity is affected by many factors such as composition, processing and environment, making it flexible and adaptable in different applications.
Factors Affecting the Thermal Conductivity of Stainless Steel
Composition
In stainless steel, an increase in chromium content will significantly reduce its thermal conductivity, while the addition of nickel enhances strength and toughness, but has little effect on the thermal conductivity. In addition, elements such as molybdenum and titanium can also affect the thermal conductivity of stainless steel by adjusting the crystal structure and electronic conduction.
Microstructure
The microstructure of stainless steel, such as austenite, ferrite, martensite, etc., has a direct impact on its thermal conductivity. Austenitic stainless steels (such as 304 and 316) generally have lower thermal conductivity, while ferritic stainless steels (such as 430) have higher thermal conductivity. This is because different crystal structures affect the path and efficiency of heat conduction.
Temperature
Stainless steel’s thermal conductivity varies with temperature rise. Typically, higher temps boost conductivity. For 304 stainless, it’s around 16.2 W/m·K at 100°C and 21.5 W/m·K at 500°C. This is because hotter temps intensify lattice vibrations and electron mobility, enhancing heat transfer.
Processing technology
Cold rolling and hot rolling processes will affect the microstructure of stainless steel and thus affect its thermal conductivity. The cold rolling process usually increases the density and uniformity of the material, resulting in a slight increase in thermal conductivity. In addition, the thermal treatment processes like annealing and quenching affect the thermal conductivity of the material by altering the internal stresses and crystal defects.
Ways to Improve the Thermal Conductivity of Stainless Steel
Despite the inherently low thermal conductivity of stainless steel, there exist various techniques that can effectively enhance it to a certain degree.
Optimizing the microstructure: By adjusting the alloying element content and heat treatment process of stainless steel, its microstructure can be optimized, lattice defects can be reduced, and heat conduction efficiency can be improved.
Adding thermal conductivity enhancement phase: Adding some second phase particles or fibers with high thermal conductivity to stainless steel can form a thermal conductive network and improve the overall thermal conductivity of the material.
Surface modification: Through surface coating, plating or film technology, a layer of material with high thermal conductivity can be formed on the surface of stainless steel, thereby accelerating heat transfer.
Composite material design: Compounding stainless steel with other materials with high thermal conductivity can make full use of the advantages of each material and improve the overall thermal conductivity of the composite material.
Application of Thermal Conductivity of Stainless Steel
Building materials
Stainless steel is widely used in the facades, roofs and interior decoration of buildings. Its low thermal conductivity enables it to provide good insulation in high or low temperature environments, helping buildings save energy. For example, in summer, stainless steel can effectively prevent external heat from entering the room, thereby reducing the frequency of air conditioning use and energy consumption.
Food processing equipment
In food processing, temperature control is crucial. The low thermal conductivity of stainless steel enables it to maintain a relatively stable temperature during high-temperature processing, prevent rapid heat loss, and improve processing efficiency. For example, during the baking process, stainless steel baking pans can spread the heat evenly to have the best baking results by ensuring that the food is evenly heated.
Chemical equipment
Stainless steel is known for its corrosion resistance and low thermal conductivity, and performs well in high-temperature and high-pressure chemical equipment such as reactors, pipelines and tanks. In the petrochemical industry, stainless steel tanks can withstand high temperatures and chemicals, extend equipment life and improve process safety.
Medical equipment
Stainless steel is commonly used to make medical tools such as scalpels, forceps and implants, and it can maintain its shape and function during the sterilization process. Its low thermal conductivity ensures safe use. During surgery, it can quickly adapt to room temperature to prevent patient discomfort.
Automotive Industry
In the automotive industry, the low thermal conductivity of stainless steel enables it to provide good insulation under high temperature conditions, thereby improving the fuel efficiency and safety of the car. For example, stainless steel exhaust pipes can effectively reduce exhaust temperature and protect other body parts from high temperature damage.
Thermal Conductivity of Different Grades of Stainless Steel
What is the thermal conductivity of SS 304?
At room temperature (At 20°C), it is 16.2 W/m·K; at 100°C, it is 16.2 W/m·K; at 300°C, it is 18.4 W/m·K; at 500°C, it is 21.5 W/m·K.
What is the thermal conductivity of SS 316?
At room temperature (At 20°C), it is 16.2 W/m·K; at 100°C, it is 16.2 W/m·K; at 300°C, it is 18.4 W/m·K; at 500°C, it is 21.5 W/m·K.
What is the thermal conductivity of stainless steel 316L?
At room temperature (At 20°C), it is 16.2 W/m·K; at 100°C, it is 16.2 W/m·K; at 300°C, it is 18.4 W/m·K; at 500°C, it is 21.5 W/m·K.
What is thermal conductivity of 17-4 ph stainless steel?
At room temperature (At 20°C), it is 18.3 W/m·K; at 100°C, it is 18.3 W/m·K; at 300°C, it is 20.9 W/m·K; at 500°C, it is 23.0 W/m·K.
Stainless Steel Thermal Conductivity Chart
Below is the thermal conductivity of stainless steel at different temperatures in the annealed condition.
| Grade | 20°C (68°F) | 100°C (212°F) | 300°C (572°F) | 500°C (932°F) |
| / | W/m·K (Btu/ft·h·°F) | W/m·K (Btu/ft·h·°F) | W/m·K (Btu/ft·h·°F) | W/m·K (Btu/ft·h·°F) |
| 304 | 16.2 (9.4) | 16.2 (9.4) | 18.4 (10.6) | 21.5 (12.4) |
| 316 | 16.2 (9.4) | 16.2 (9.4) | 18.4 (10.6) | 21.5 (12.4) |
| 201 | 16.2 (9.4) | 16.2 (9.4) | 18.4 (10.6) | 21.5 (12.4) |
| 202 | 16.2 (9.4) | 16.2 (9.4) | 18.4 (10.6) | 21.6 (12.5) |
| 301 | 16.2 (9.4) | 16.2 (9.4) | 18.4 (10.6) | 21.5 (12.4) |
| 302 | 16.2 (9.4) | 16.2 (9.4) | 18.4 (10.6) | 21.5 (12.4) |
| 303 | 16.2 (9.4) | 16.2 (9.4) | 18.4 (10.6) | 21.5 (12.4) |
| 305 | 16.2 (9.4) | 16.2 (9.4) | 18.4 (10.6) | 21.5 (12.4) |
| 308 | 15.2 (8.8) | 15.2 (8.8) | 17.8 (10.3) | 21.6 (12.5) |
| 309 | 15.6 (9.0) | 15.6 (9.0) | 17.5 (10.1) | 18.7 (10.8) |
| 310 | 14.2 (8.2) | 14.2 (8.2) | 16.5 (9.5) | 18.7 (10.8) |
| 314 | 17.5 (10.1) | 17.5 (10.1) | 19.3 (11.2) | 20.9 (12.1) |
| 317 | 16.2 (9.4) | 16.2 (9.4) | 18.4 (10.6) | 21.5 (12.4) |
| 317L | 14.4 (8.3) | 14.4 (8.3) | 17.2 (9.9) | — |
| 321 | 16.1 (9.3) | 16.1 (9.3) | 18.2 (10.5) | 22.2 (12.8) |
| 347 | 16.1 (9.3) | 16.1 (9.3) | 18.2 (10.5) | 22.2 (12.8) |
| 384 | 16.2 (9.4) | 16.2 (9.4) | 18.4 (10.6) | 21.5 (12.4) |
| 405 | 27.0 (15.6) | 27.0 (15.6) | 29.3 (16.9) | — |
| 410 | 24.9 (14.4) | 24.9 (14.4) | 26.7 (15.5) | 28.7 (16.6) |
| 414 | 24.9 (14.4) | 24.9 (14.4) | 26.7 (15.5) | 28.7 (16.6) |
| 416 | 24.9 (14.4) | 24.9 (14.4) | 26.7 (15.5) | 28.7 (16.6) |
| 420 | 24.9 (14.4) | 24.9 (14.4) | 26.7 (15.5) | — |
| 422 | 23.9 (13.8) | 23.9 (13.8) | 26.1 (15.1) | 27.3 (15.8) |
| 429 | 25.6 (14.8) | 25.6 (14.8) | 27.0 (15.6) | — |
| 430 | 26.1 (15.1) | 26.1 (15.1) | 26.3 (15.2) | 26.3 (15.2) |
| 434 | — | — | 26.3 (15.2) | 26.3 (15.2) |
| 436 | 23.9 (13.8) | 23.9 (13.8) | 25.8 (14.9) | 26.0 (15.0) |
| 440A, 440C | 24.2 (14.0) | 24.2 (14.0) | 25.7 (14.8) | — |
| 17-4 PH | 18.3 (10.6) | 18.3 (10.6) | 20.9 (12.1) | 23.0 (13.1) |
Thermal Conductivity of Stainless Steel vs Aluminum
At room temperature (20°C), the thermal conductivity of 304 stainless steel is 16.2W/m·K, while the thermal conductivity of aluminum is as high as 235W/m·K, which significantly shows that the thermal conductivity of aluminum is much more efficient than that of stainless steel and can transfer heat faster under the same conditions.
Key Differences:
- Stainless steel, with its low thermal conductivity and excellent thermal insulation properties, has become the preferred material for high-temperature applications, and is commonly found in automotive and aircraft engine components, kitchens, and food processing equipment. However, in situations where rapid heat dissipation is required, the heat dissipation efficiency of stainless steel is relatively low.
- The high thermal conductivity of aluminum makes it excellent in applications that require rapid heat dissipation, such as heat sinks for electronic equipment, heat exchangers, and kitchen utensils (such as pots and pans). However, Aluminum is not as mechanically strong or corrosion resistant as stainless steel.
Thermal Conductivity of Stainless Steel vs Titanium
The thermal conductivity of stainless steel (304) and titanium (grade 2) at room temperature (about 20°C) is 16.2 W/m·K and 16.4 W/m·K respectively.
Key Differences:
- Stainless steel generally has a lower thermal conductivity compared to other metals like copper and aluminum, but it is similar to that of titanium.
- Titanium has a slightly higher thermal conductivity at room temperature compared to most stainless steels, but it is still lower compared to metals like aluminum or copper.
Both materials have relatively low thermal conductivity, making them good choices for applications where heat retention is needed, but neither is as efficient at conducting heat compared to other metals like copper.
Thermal Conductivity of Stainless Steel vs Carbon Steel
Thermal conductivity of stainless steel and carbon steel at room temperature (about 20°C) is 15-25 W/m·K and 43-60 W/m·K respectively (depending on the specific grade of carbon steel and stainless steel).
Key Differences:
- Carbon steel generally has a much higher thermal conductivity compared to stainless steel. This means that carbon steel is better at conducting heat, making it more efficient in heat transfer applications.
- Stainless steel is chosen for applications requiring corrosion resistance and strength at the expense of lower thermal conductivity, whereas carbon steel is preferred when heat transfer efficiency is important.
Does Stainless Steel Hold Heat?
Yes, due to its relatively low thermal conductivity, stainless steel is able to maintain temperature well and is widely used in thermal insulation equipment and applications where temperature stability is required, such as kitchen appliances, industrial equipment and piping systems.
Why is Stainless Steel a Poor Thermal Conductor?
Stainless steel is a poor thermal conductor due to its composition and structure.
- High Alloy Content: Elements like chromium, nickel, and molybdenum improve corrosion resistance but reduce heat conduction by disrupting the metal’s lattice structure.
- Crystal Structure: Austenitic stainless steels (e.g., 304, 316) have a face-centered cubic (FCC) structure, less efficient for heat transfer compared to body-centered cubic (BCC) or hexagonal close-packed (HCP) structures.
- Electron Mobility: Fewer free electrons in stainless steel reduce heat conduction compared to metals like copper or aluminum.
- Resistance to Corrosion: The elements that improve corrosion resistance also inhibit heat transfer.
Thermal Conductivity of Metals
| Metal | Thermal Conductivity (W/m·K) | Description and Applications |
| Silver | 429 | Highest thermal conductivity; used in high-end applications like electronic devices and thermal conductors. |
| Copper | 401 | Excellent conductor; used in electrical wiring, heat exchangers, and plumbing. |
| Gold | 318 | Good conductor with resistance to corrosion; used in electronic components and connectors. |
| Aluminum | 237 | High thermal conductivity; used in heat sinks, cookware, and automotive parts. |
| Brass | 109 | Lower conductivity than pure metals; used in decorative items, plumbing fittings, and instruments. |
| Carbon Steel | 54 | Moderate thermal conductivity; used in construction, automotive, and machinery. |
| Iron | 80 | Moderate conductor; used in construction and machinery. |
What Is the Electrical Conductivity of Stainless Steel?
The electrical conductivity of stainless steel is relatively low compared to other metals. Here are typical values for different stainless steel types:
- Austenitic Stainless Steel (e.g., 304, 316): Electrical conductivity is around 1.45-1.55 MS/m (mega siemens per meter), which is about 2-3% of copper’s conductivity.
- Ferritic Stainless Steel (e.g., 430): Slightly higher electrical conductivity, around 1.4-1.7 MS/m.
- Martensitic Stainless Steel (e.g., 410): Electrical conductivity is around 1.25-1.4 MS/m.
Stainless steel’s low electrical conductivity makes it less ideal for applications requiring efficient electricity conduction compared to materials like copper or aluminum.
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