Contents
Understanding 408 Stainless Steel: A Key Player in the 400 Series
- John
As a member of the 400 series, 408 stainless steel is known for its high-temperature strength. This article will cover key aspects of 408 stainless steel, including its composition, properties, and typical applications.
What is 408 Stainless Steel?
408 stainless steel is a ferritic stainless steel containing around 11% chromium and approximately 0.5% nickel. Known for its heat resistance, 408 is usually used in exhaust systems and heat exchangers. Hot rolling is typically used for processing. Its specific composition offers good oxidation resistance.
408 Stainless Steel Equivalents
| Country/Region | Standard/Specification | Equivalent Grade |
| China | GB/T 1220 | 1Cr11Ti |
| USA | ASTM A240 | UNS S40800 |
| Japan | JIS G4304 | SUS 408 |
408 Stainless Steel Chemical Composition
| Element | C | Si | Mn | P | S | Cr | Ni | Ti |
| wt (%) | ≤0.08 | ≤1.00 | ≤1.00 | ≤0.040 | ≤0.030 | 10.5–11.75 | ≤0.50 | 0.50–0.75 |
408 Stainless Steel Properties
Mechanical Properties
| Property | Typical Value | Typical Value |
| Tensile Strength | 450–600 MPa | 65–87 ksi |
| Yield Strength | ~275 MPa | ~40 ksi |
| Brinell Hardness | ~150 | ~150 |
| Rockwell Hardness | ~75 | ~75 |
| Elongation | ~20% | ~20% |
Physical Properties
| Property | Typical Value | Typical Value |
| Density | 7.75 g/cm³ | 0.280 lb/in³ |
| Melting Point | 1,420–1,460°C | 2,588–2,660°F |
| Thermal Conductivity | 26 W/m·K at 20°C | 15 BTU·ft·hr⁻¹·ft⁻²·°F⁻¹ at 68°F |
| Thermal Expansion | 10.4 µm/m·K (20–100°C) | 5.8 × 10⁻⁶ in/in·°F (68–212°F) |
| Electrical Conductivity | ~1.4 × 10⁶ S/m | ~2.4% IACS |
| Magnetic Properties | Ferromagnetic | Ferromagnetic |
Chemical Properties
- Strong Oxidation Resistance
408 can handle continuous exposure up to 815°C and intermittent exposure up to 870°C. This makes it suitable for high-heat applications.
- Moderate Corrosion Resistance
It performs well in environments where oxidation is the primary concern. It is not ideal for highly corrosive environments, such as acidic or marine conditions.
- Scaling Resistance
Due to its chromium content, 408 stainless steel effectively resists scaling, which prevents surface deterioration at elevated temperatures.
- Carbide Precipitation Resistance
The inclusion of titanium prevents chromium carbide formation. This reduces the risk of intergranular corrosion during welding or extended exposure to elevated temperatures.
408 Stainless Steel Applications
- Automotive
Used in exhaust systems due to its high heat and oxidation resistance.
- Household Appliances
Applied in ovens, refrigerators, and dishwashers for its corrosion resistance.
- Heat Exchangers
Ideal for industrial heat exchangers, offering strong performance at high temperatures.
- Architectural
Used in exterior cladding and structures, valued for its durability and aesthetic appearance.
- Cookware
Employed in pots and pans for its ability to resist heat and discoloration.
408 Stainless Steel Products
| Product | Application | Characteristics |
| Sheets and Plates | Furnace parts, automotive exhaust systems | High heat resistance and durability |
| Bars | Industrial heat exchangers, machinery components | Strength at high temperatures |
| Pipes and Tubes | Power plants, heat transfer applications | Heat and oxidation resistance |
| Forged Components | Automotive and industrial machinery parts | High-temperature performance and strength |
The Pros and Cons of 408 Stainless Steel
Here are the advantages of 408 stainless steel:
- High Heat Resistance: It performs well in high-temperature environments, making it ideal for exhaust systems and heat exchangers.
- Good Oxidation Resistance: It resists oxidation up to 815°C in continuous service and 870°C in intermittent service.
- Cost-Effective: Due to its lower nickel and chromium content, it is more affordable than higher grades like 304.
Here are the disadvantages of 408 stainless steel:
- Lower Corrosion Resistance: It has only moderate corrosion resistance, making it less suitable for highly corrosive environments like marine or chemical processing.
- Limited Cold Workability: Its lower ductility makes it less suitable for extensive cold working.
- Not Hardenable by Heat Treatment: Unlike martensitic grades, it cannot be hardened through heat treatment, limiting its applications where high hardness is required.
408 Stainless Steel Processing
Hot Rolling
- Performed at high temperatures to form sheets, plates, or bars.
- Enhances strength and performance at high temperatures.
Cold Working
- The process involves techniques like cold rolling, bending, or drawing.
- It increases the material’s strength and hardness by restricting dislocation movement, though this reduces ductility.
- After extensive cold working, annealing is often needed to restore ductility and reduce internal stresses.
Heat Treatment
- Anneal at 760–815°C (1400–1500°F) and air cool.
- This helps to restore ductility after cold working and reduces internal stresses that build up during manufacturing.
Machining
- Machining can be done using standard techniques.
- Proper lubrication and tool selection are important to avoid work hardening.
Welding
- Preheat to 149–260°C (300–500°F) to avoid cracking. Post-weld heat treatment is not necessary.
- Common methods: SMAW, GMAW, GTAW.
Surface Finishing
- Surface finishing for 408 stainless steel involves treatments like pickling and passivation.
- It is used to improve surface corrosion resistance. It can also improve appearance and remove impurities.
Other things about 408 Stainless Steel
408 Stainless Steel VS 304
304 is better in corrosion resistance, and 408 withstands higher temperatures. 408 is generally cheaper due to its lower nickel content. 304 is more ductile and easier to cold work.
408 is used in automotive exhaust systems and furnaces. 304 is used in food processing and medical equipment.
About 408 Stainless Steel Price
The price of 408 stainless steel is generally lower than higher-alloyed grades. However, the actual price can vary based on market conditions, supply, demand, and processing costs.
About 400 Series Stainless Steel
The 400 series stainless steel consists of ferritic and martensitic stainless steels. These steels are known for magnetic properties, high strength, and good resistance to corrosion in mild environments. Popular grades include 409, 410, and 430.
Summary
This article provides a comprehensive view of 408 stainless steel, its composition and properties, and its suitability for high-temperature applications like automotive and industrial uses.
At Steel Pro Group, we are committed to providing top-quality stainless steel for high-performance industrial needs. If you are looking for reliable solutions for your projects, please visit our website or contact us for a personalized consultation and quote.
