Description
Stainless Steel Grade 409Nb/1.4512 (also known as UNS S40920) is a ferritic stainless steel that contains niobium, which enhances its corrosion resistance, mechanical properties, and weldability. This grade is particularly well-suited for automotive applications, such as exhaust systems, where high temperature oxidation resistance and moderate corrosion resistance are required.
Chemical Composition
Chromium (Cr): 10.5 - 11.7%
Nickel (Ni): ≤ 0.5%
Silicon (Si):≤ 1.0%
Manganese (Mn): ≤ 1.0%
Niobium (Nb): 0.17 - 0.45%
Carbon (C): ≤ 0.03%
Phosphorus (P): ≤ 0.03%
Sulfur (S): ≤ 0.020%
Nitrogen (N): ≤ 0.030%
Iron (Fe): Balance
Mechanical Properties
Tensile Strength: 380 - 450 MPa
Yield Strength: 200 - 280 MPa
Elongation: 20 - 30%
Hardness: ≤ 200 HB
Thermal & Physical Properties
Density: 7.75 g/cm³
Thermal Conductivity: 24.2 W/m•K (at 100°C)
Specific Heat: 460 J/kg•K (at 20°C)
Coefficient of Thermal Expansion: 10.5 µm/m•K (at 20-100°C)
Electrical Resistivity: 0.60 µΩ•m (at 20°C)
Other Designations
UNS:S40920
EN: 1.4512
ASTM: 409
Fabrication and Heat Treatment
Welding: 409Nb/1.4512 stainless steel is weldable using most standard welding techniques. Post-weld annealing is recommended to maintain corrosion resistance and mechanical properties.
Heat Treatment: Annealing should be performed at 790-900°C followed by air cooling.
Forming: This grade can be formed using conventional techniques. However, care should be taken to avoid cracking.
Applications
Automotive: Exhaust systems, catalytic converters, mufflers, tailpipes.
Industrial: Heat exchangers, agricultural equipment, construction materials.
Home Appliances: Kitchen equipment, water heaters, furnace components.
Food Processing: Ideal for components in food processing equipment where high strength and corrosion resistance are essential.
Miscellaneous: Structural applications requiring moderate corrosion resistance and high temperature strength.
Supplied Forms
Bars:
Coils
Pipes
Features
Enhanced Corrosion Resistance: The addition of niobium improves the corrosion resistance compared to standard 409 stainless steel.
Good Oxidation Resistance: Suitable for high-temperature applications up to 675°C.
High Temperature Strength: Maintains strength and stability at high temperatures, making it ideal for exhaust systems and similar applications.
Improved Weldability: Niobium addition helps in reducing grain growth and improving weld quality.
High Strength: Good mechanical properties for structural applications.
Cost-Effective: Lower cost compared to higher alloyed stainless steels while still providing good performance.
