Ferritic Stainless Steel is a family of chromium-based stainless steels characterized by a body-centered cubic (BCC) ferritic microstructure at all temperatures. These steels contain little to no nickel, making them cost-effective, price-stable, and resistant to nickel market volatility.
With chromium content ranging from 10.5% to 30% and very low carbon levels, ferritic stainless steels offer excellent resistance to oxidation, atmospheric corrosion, and stress corrosion cracking (SCC). They are magnetic, have good thermal conductivity, and low thermal expansion.
Typical Chemical Composition
| Element | Typical Range (%) | Function |
|---|---|---|
| Chromium (Cr) | 10.5 – 30.0 | Corrosion & oxidation resistance |
| Carbon (C) | ≤ 0.08 | Prevents brittleness |
| Nickel (Ni) | ≤ 0.5 | Cost reduction |
| Manganese (Mn) | ≤ 1.0 | Deoxidation |
| Silicon (Si) | ≤ 1.0 | Oxidation resistance |
| Titanium / Niobium | 0.2 – 1.0 | Grain stabilization |
| Iron (Fe) | Balance | Base metal |
Microstructure & Metallurgical Behavior
• Stable ferritic (BCC) structure at all temperatures
• Magnetic in all conditions
• No phase transformation during heating or cooling
• Eliminates risk of martensitic cracking
Modern ferritic grades are stabilized with titanium or niobium to improve weldability, prevent carbide precipitation, and enhance corrosion resistance.
Mechanical Properties
| Property | Typical Range |
|---|---|
| Tensile Strength | 380 – 550 MPa |
| Yield Strength | 230 – 350 MPa |
| Hardness | 150 – 200 HB |
| Elongation | 20 – 30% |
| Density | ~7.7 g/cm³ |
| Modulus of Elasticity | ~200 GPa |
Key Characteristics
Corrosion & Oxidation Resistance
• Protective chromium oxide layer
• Excellent resistance to stress corrosion cracking
Magnetic Properties
• Magnetic in all conditions
• Suitable for induction heating and magnetic applications
Thermal Performance
• Lower thermal expansion than austenitic steels
• Higher thermal conductivity improves heat dissipation
Formability & Weldability
• Good formability in modern low-carbon grades
• Stabilized grades offer improved weldability
Common Ferritic Stainless Steel Grades
| Grade | Key Features |
|---|---|
| 409 | Automotive exhaust systems |
| 430 | General-purpose ferritic stainless steel |
| 439 | Improved weldability & corrosion resistance |
| 441 | High-temperature oxidation resistance |
| 444 | Superior corrosion resistance (Mo-alloyed) |
| 446 | Very high chromium for extreme heat |
Available Forms
✔ Sheets & coils
✔ Plates
✔ Pipes & tubes
✔ Strips & precision strips
✔ Bars, rods & wires
✔ Profiles & custom-cut components
Applications
Automotive: Exhaust systems, manifolds, heat shields
Appliances: Refrigerator panels, washing machine drums, cookware
Architecture: Cladding, roofing, decorative panels, trims
Industrial: Heat exchangers, furnace components, process equipment
Advantages
✔ Lower cost due to minimal nickel
✔ Excellent resistance to stress corrosion cracking
✔ Magnetic properties
✔ Good oxidation resistance at high temperatures
✔ Better thermal stability than austenitic grades
Limitations
⚠ Lower toughness at cryogenic temperatures
⚠ Reduced formability vs austenitic stainless steel
⚠ Lower chloride resistance than 316
⚠ Not heat treatable for hardening
Why Choose Ferritic Stainless Steel
Ferritic stainless steel provides an excellent balance of corrosion resistance, thermal stability, and cost efficiency. It is an ideal choice for automotive, appliance, architectural, and high-temperature applications where durability and performance are required without the cost premium of nickel-rich steels.