Stainless Steel 309S (UNS S30908 / EN 1.4833)

Stainless Steel 309S (UNS S30908 / EN 1.4833) – Specifications, Properties and Applications

Stainless Steel 309S (UNS S30908 / EN 1.4833) is the low-carbon version of Stainless Steel 309, specifically developed for applications requiring excellent oxidation resistance, superior heat resistance, and outstanding weldability. The reduced carbon content minimizes carbide precipitation during welding, significantly improving resistance to intergranular corrosion in welded structures.

With its high chromium and nickel content, Stainless Steel 309S offers exceptional performance in high-temperature environments while maintaining excellent corrosion resistance and mechanical strength. It is widely used in industrial furnaces, heat treatment equipment, boilers, heat exchangers, petrochemical plants, refineries, and power generation facilities.

Emirerri Steel supplies Stainless Steel 309S in sheets, plates, coils, pipes, tubes, round bars, flanges, and pipe fittings for customers across Tunisia, Algeria, Morocco, Libya, and global markets.

Key Features of Stainless Steel 309S

• Excellent high-temperature oxidation resistance

• Superior heat resistance

• Low carbon content for improved weldability

• Excellent resistance to intergranular corrosion

• Good corrosion resistance

• Excellent thermal shock resistance

• High chromium and nickel content

• Good fabrication and forming characteristics

• Long service life

• Low maintenance requirements

Stainless Steel 309S Specifications

Equivalent Grades of Stainless Steel 309S

Available Sizes

Plates

• Thickness: 5 mm to 100 mm

• Width: 1000 mm to 2500 mm

• Length: Up to 12000 mm

Sheets

• Thickness: 0.5 mm to 6 mm

• Width: Up to 2000 mm

Pipes & Tubes

• Outside Diameter: 6 mm to 610 mm

• Wall Thickness: 0.5 mm to 40 mm

Round Bars

• Diameter: 6 mm to 500 mm

Stainless Steel 309S Chemical Composition

Stainless Steel 309S Mechanical Properties

Stainless Steel 309S Physical Properties 

Types of Stainless Steel 309S Products

Stainless Steel 309S Plates

Designed for industrial furnaces, boilers, heat treatment equipment, and high-temperature pressure vessels.

Stainless Steel 309S Sheets

Suitable for furnace linings, heat shields, thermal insulation systems, and industrial fabrication.

Stainless Steel 309S Pipes

Used in petrochemical plants, refineries, and high-temperature process piping systems.

Stainless Steel 309S Tubes

Ideal for heat exchangers, superheaters, condensers, and thermal processing equipment.

Stainless Steel 309S Round Bars

Used for shafts, furnace fixtures, fasteners, valves, and machined components exposed to elevated temperatures.

Stainless Steel 309S Flanges & Pipe Fittings

Manufactured for high-temperature piping systems in power plants, chemical processing facilities, and refinery applications.

Corrosion Resistance

Stainless Steel 309S provides excellent resistance to:

• Atmospheric corrosion

• High-temperature oxidation

• Industrial atmospheres

• Organic acids

• Oxidizing gases

• Intergranular corrosion after welding

The low carbon content significantly reduces carbide precipitation during welding, making Grade 309S particularly suitable for welded fabrications operating at elevated temperatures. However, for chloride-rich or marine environments, Stainless Steel 316L generally offers better corrosion resistance.

Heat Resistance

Stainless Steel 309S is specifically engineered for prolonged exposure to elevated temperatures.

Service Temperature

• Continuous Service: Up to approximately 1000°C

• Intermittent Service: Up to approximately 1035°C

Benefits

• Outstanding oxidation resistance

• Excellent scaling resistance

• Superior thermal stability

• Good creep resistance

• Excellent thermal shock resistance

Heat Treatment

Solution Annealing

• Temperature: 1035°C – 1120°C

• Cooling: Rapid air cooling or water quenching

Benefits

• Restores corrosion resistance

• Improves ductility

• Relieves internal stresses

• Optimizes mechanical performance

Stainless Steel 309S cannot be hardened by heat treatment but can be strengthened through cold working.

Welding of Stainless Steel 309S

Grade 309S offers excellent weldability using conventional welding processes.

Recommended Welding Methods

• GTAW (TIG)

• GMAW (MIG)

• SMAW (Shielded Metal Arc Welding)

• SAW (Submerged Arc Welding)

• Resistance Welding

Welding Advantages

• Excellent weld quality

• No preheating normally required

• Reduced risk of intergranular corrosion

• Good resistance to hot cracking

• Reliable high-temperature performance

Post-weld cleaning, pickling, and passivation are recommended to restore the protective oxide layer and maximize corrosion resistance.

Fabrication of Stainless Steel 309S

Machining

• Turning

• Milling

• Drilling

• Threading

Forming

• Cold bending

• Roll forming

• Press forming

• Deep drawing

Cutting

• Laser cutting

• Plasma cutting

• Waterjet cutting

• Mechanical sawing

Surface Finishing

• Pickling

• Passivation

• Mechanical polishing

• Electropolishing

Applications of Stainless Steel 309S

Furnace Industry

• Furnace linings

• Burner components

• Furnace conveyors

• Heat treatment baskets

Petrochemical Industry

• Reactors

• Process piping

• Heat exchangers

• Refinery equipment

Power Generation

• Boilers

• Superheaters

• Steam piping

• Waste heat recovery systems

Chemical Processing

• High-temperature vessels

• Storage tanks

• Processing equipment

Thermal Processing

• Annealing furnaces

• Kilns

• Combustion chambers

• Incinerator components

Industrial Manufacturing

• High-temperature machinery

• Exhaust systems

• Heat-resistant structural components