AISI 309S / UNS S30908 3mm Cold Rolled Stainless Steel Sheet 2B Finish For High

AISI 309S (Chinese grade 06Cr23Ni13, UNS S30908) is an austenitic, high-chromium, high-nickel heat-resistant stainless steel. It is a variant of the low-carbon 309 stainless steel, specifically designed for weldability and high-temperature corrosion resistance.

Chemical Composition:
AISI 309S / UNS S30908 is a high-chromium, high-nickel austenitic stainless steel designed for applications requiring good oxidation resistance and performance at elevated temperatures.
Chemical Composition: Cr 22–24%, Ni 12–15%, C ≤0.08%, S ≤0.03%

Key Chemical Composition Features:

• Chromium (Cr): 22–24% — Provides excellent oxidation resistance and helps maintain a protective surface layer at elevated temperatures.
• Nickel (Ni): 12–15% — Stabilizes the austenitic structure and contributes to good high-temperature strength and corrosion resistance.
• Carbon (C): ≤0.08% — Helps maintain good weldability and limits carbide precipitation.
• Silicon (Si): ≤1.00% — Contributes to oxidation resistance.
• Manganese (Mn): ≤2.00% — Supports overall alloy performance and acts as a deoxidizing element.
  
  

Why Is 309S Suitable for High-Temperature Applications?

The combination of high chromium and nickel content gives 309S better oxidation resistance and high-temperature performance than many conventional stainless steel grades such as 304. It is commonly used for industrial furnaces, heat-treatment equipment, furnace components, petrochemical equipment, and high-temperature processing systems.

Heat Resistance:
Heat Resistance: Can withstand repeated heating at 900–980°C; exhibits excellent resistance to oxidation and carburization; high-temperature strength is 30–45% higher than that of 304 stainless steel

• Maximum service temperature: Up to approximately 1000–1100°C (1832–2012°F) in suitable oxidizing environments, depending on service conditions.
• Continuous service: Commonly used at temperatures around 1000°C (1832°F) or below when oxidation resistance is the primary consideration.
• Intermittent service: Can withstand higher temperatures for intermittent exposure, subject to atmosphere, load, thermal cycling, and component geometry.
• Oxidation resistance: Its 22–24% chromium content promotes the formation of a protective chromium-rich oxide layer, while its 12–15% nickel content helps maintain a stable austenitic structure at elevated temperatures.
• Thermal cycling: Offers good resistance to repeated heating and cooling compared with many conventional stainless steel grades.

Typical High-Temperature Applications

309S is widely used for:

• Industrial furnace components
• Heat-treatment equipment
• Furnace linings and supports
• Kiln components
• Heat exchangers
• Petrochemical processing equipment
• High-temperature combustion equipment

Corrosion Resistance:

AISI 309S / UNS S30908 stainless steel sheet offers good corrosion resistance and excellent oxidation resistance, particularly in elevated-temperature and oxidizing environments. Its high chromium content helps form a protective chromium-rich oxide layer, while its nickel content contributes to the stability of the austenitic structure.

Compared with 304 stainless steel, 309S generally provides better high-temperature corrosion resistance and oxidation resistance, making it suitable for applications exposed to heat, combustion gases, and industrial processing atmospheres.

However, 309S stainless steel is sensitive to reducing sulfur-containing environments, especially at elevated temperatures. For applications involving sulfur-rich gases, chlorides, strong acids, or highly corrosive process media, material selection should be based on the actual operating temperature and chemical environment.

Key Corrosion-Resistance Advantages

• Good corrosion resistance in general industrial environments
• Excellent high-temperature oxidation resistance
• Better oxidation resistance than 304 stainless steel
• Good resistance to scaling at elevated temperatures
• Suitable for many oxidizing atmospheres
• Good performance in high-temperature industrial equipment
• High chromium content provides a protective oxide layer
• Suitable for selected petrochemical and thermal-processing applications
  

Mechanical Properties:
Mechanical Properties: Tensile strength ≥515 MPa, yield strength ≥205 MPa, elongation ≥40%, hardness ≤187 HB
AISI 309S / UNS S30908 stainless steel is an austenitic stainless steel that combines good strength, ductility, and toughness with excellent performance in elevated-temperature environments. The following values can be used as typical reference values for a 3mm cold-rolled sheet.

Workability:
Workability: Non-magnetic after solution treatment; exhibits a pronounced tendency for cold work hardening; has good weldability and can be welded using TIG, MIG/MAG, SMAW, and other methods 

AISI 309S / UNS S30908 stainless steel offers good overall workability, making it suitable for a wide range of fabrication and forming operations. In the solution-treated condition, it is generally non-magnetic, although cold working can induce some magnetic response due to deformation-induced microstructural changes.

• Non-magnetic in the solution-treated condition: 309S is generally non-magnetic when properly solution annealed. Cold working may cause a degree of magnetism.
• Pronounced work-hardening tendency: 309S hardens significantly during cold deformation. This should be considered when performing repeated bending, forming, stamping, or machining operations.
• Good cold-forming capability: It can be processed by bending, rolling, forming, and stamping, although greater forming forces and intermediate annealing may be required for severe deformation.
• Good weldability: 309S can be welded using common processes such as TIG (GTAW), MIG/MAG (GMAW), SMAW, and resistance welding.
• Good fabrication performance: It can be cut, sheared, bent, formed, and fabricated using conventional stainless steel processing equipment.
• Machining considerations: Its strong work-hardening tendency requires sharp tooling, appropriate cutting speeds, adequate feed rates, and effective cooling to minimize work hardening and tool wear.
• Hot working: Hot forming can be used for demanding deformation operations, with the working temperature and subsequent heat treatment controlled according to the applicable specification.
• Post-processing: For applications involving significant cold deformation, solution annealing may be considered to restore ductility and reduce deformation-induced stresses.
  
  

  Key Workability Advantages:
  
  Good formability + excellent weldability + strong work-hardening capability + good fabrication performance

  These characteristics make 309S cold rolled stainless steel sheet suitable for furnace components, heat-treatment equipment, petrochemical equipment, heat exchangers, high-temperature processing equipment, and general industrial fabrication.
  
  

  Characteristics of 3mm Cold-Rolled Sheet

  Thickness: Cold-rolled sheet thickness typically ranges from 0.3 to 3.0 mm; 3 mm is considered a relatively thick cold-rolled sheet www.rchbxg.com.
  Surface Finish: Available in 2B (mirror finish), BA, 6K, 8K, HL, No. 4, No. 1, and other surface conditions, suitable for subsequent processing such as stamping, bending, and wire drawing www.rchbxg.com.
  Applications: Suitable for manufacturing components resistant to high temperatures and corrosion, such as heat treatment furnace tubes, furnace chambers, mesh belts, burner components, boiler combustion chamber structural parts, and chemical reactor tube sheets.

1. Excellent High-Temperature Performance

309S stainless steel contains high levels of chromium and nickel, providing excellent resistance to oxidation and good structural stability at elevated temperatures. It is suitable for furnace components, heat-treatment equipment, and other high-temperature applications.

2. Good Oxidation Resistance

The high chromium content helps form a protective oxide layer on the surface, giving 309S good resistance to oxidation during prolonged exposure to elevated temperatures.

3. Good Corrosion Resistance

309S provides good corrosion resistance in many atmospheric and industrial environments, making it suitable for equipment exposed to heat, moisture, and industrial process conditions.

4. Smooth 2B Surface Finish

The 2B finish provides a smooth, uniform surface with good appearance and relatively low surface roughness. It is suitable for applications requiring a clean surface and can also serve as a base for further processing or finishing.

5. Cold-Rolled Dimensional Accuracy

Cold rolling provides better thickness control, dimensional consistency, flatness, and surface quality compared with conventional hot-rolled material.

6. Suitable for Demanding Industrial Applications

The combination of high-temperature oxidation resistance, corrosion resistance, strength, and fabrication performance makes 309S suitable for demanding applications such as industrial furnaces, heat-treatment equipment, petrochemical equipment, and high-temperature processing systems.