What is 1.4535 Stainless Steel?
Jan 27, 2026
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1.4535 stainless steel, commonly known as 309S or UNS S30908, is a high-alloy austenitic stainless steel designed for excellent oxidation resistance and high-temperature strength. With its elevated chromium and nickel content, it is well-suited for continuous service at temperatures up to 1050°C, making it a reliable choice for furnace parts, heat exchangers, and industrial heating equipment.
This high-temperature resistant grade is standardized under major international systems.
| Standard | Equivalent Grade |
|---|---|
| EN (Europe) | 1.4535 |
| ASTM/AISI (USA) | 309S, UNS S30908 |
| JIS (Japan) | SUS309S |
| KS (Korea) | STS309S |
Its composition provides a robust balance of chromium and nickel for stability at high temperatures.
| Element | C | Si | Mn | P | S | Cr | Ni |
|---|---|---|---|---|---|---|---|
| Content (%) | ≤ 0.08 | ≤ 1.0 | ≤ 2.0 | ≤ 0.045 | ≤ 0.03 | 22.0 - 24.0 | 12.0 - 15.0 |
It maintains good mechanical properties across a range of temperatures.
| Property (Room Temp) | Yield Strength (Rp0.2) | Tensile Strength (Rm) | Elongation (A) | Hardness (HB) |
|---|---|---|---|---|
| Typical Value | ≥ 205 MPa | 500 - 750 MPa | ≥ 40% | ≤ 215 |
Key Characteristics and Applications of 1.4535 / 309S
Excellent High-Temperature Oxidation Resistance: Forms a stable chromium oxide layer that protects against scaling and oxidation in continuous service up to 1050°C.
Good Thermal Fatigue Resistance: Performs well under cyclic heating and cooling conditions due to its stable austenitic structure.
Resistance to Sulfur Atmospheres: Holds up better than many other stainless steels in environments containing sulfur compounds.
Primary Applications:
Heat Treatment Furnaces: Radiant tubes, retorts, baskets, and furnace linings.
Chemical Processing: High-temperature reactors, reformer tubes, and pyrolysis equipment.
Power Generation: Boiler components, superheaters, and heat recovery units.
Welding Filler Metal: Often used as an overlay or filler for joining dissimilar metals or for cladding carbon steel.
How does 309S (1.4535) compare to 310S (1.4845) in high-temperature applications?
Both are high-temperature grades, but 310S contains higher chromium and nickel (typically 25% Cr, 20% Ni) compared to 309S (23% Cr, 13% Ni). This gives 310S superior oxidation resistance and a higher maximum continuous service temperature (1150°C vs. 1050°C). 309S is often used as a more cost-effective option for slightly less severe conditions or where thermal cycling is a primary concern.
Is 309S stainless steel suitable for welding?
Yes, 309S is highly weldable using common techniques such as TIG, MIG, and SMAW. Its low carbon content minimizes carbide precipitation in the heat-affected zone, reducing the risk of intergranular corrosion. It is frequently used as a filler material for welding dissimilar metals (e.g., joining stainless to carbon steel) due to its high alloy content and good crack resistance.
Looking for a Reliable Supplier of 1.4535 / 309S Stainless Steel?
GNEE Steel supplies high-temperature grade 309S (1.4535) stainless steel in plate, sheet, pipe, and bar forms, suitable for demanding furnace and process applications. We provide full material traceability and certification to ensure reliable performance. If you have any requirements, please feel free to contact us.
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