Stainless 309S (UNS S30908) is a 23Cr-13Ni austenitic heat-resistant grade with carbon ≤ 0.08%. It resists oxidation and retains strength below 1000 °C and is widely used for furnace parts, automotive exhaust manifolds and as a buttering layer when joining dissimilar steels (carbon to stainless).
As a manufacturer and global exporter of special alloys since 2012, Shanghai Hangbo Alloy Group Co., Ltd. supplies Stainless Steel 309S as round bars (φ2–600 mm, up to 12 m), plates & sheets (0.5–100 mm thick, up to 2500 mm wide), seamless tubes & pipes (φ6–630 mm OD, 0.5–40 mm wall), welding wire & coils (1.0–5.0 mm), forgings & rolled rings (up to 7500 kg, 3500 mm OD) — all with EN 10204 3.1 certified material test reports.
Stainless Steel 309S Chemical Composition (wt%)
| Element | Content (wt%) | Element | Content (wt%) |
|---|---|---|---|
| Fe (铁) | Balance | Si (硅) | ≤ 1.00 |
| Cr (铬) | 22.0–24.0 | C (碳) | ≤ 0.080 |
| Ni (镍) | 12.0–15.0 | P (磷) | ≤ 0.045 |
| Mn (锰) | ≤ 2.00 | S (硫) | ≤ 0.030 |
Stainless Steel 309S Mechanical Properties
| Property | Value |
|---|---|
| Tensile strength (Rm) | ≥ 515 MPa |
| Yield strength (Rp0.2) | ≥ 205 MPa |
| Elongation (A) | ≥ 40 % |
| Hardness | ≤ 217 HB |
| Density | 7.98 g/cm³ |
| Melting range | 1398–1454 °C |
| Thermal conductivity | 15.6 W/m·K |
| Young's modulus | 200 GPa |
| Max service temperature | 1000 °C (continuous oxidation) |
Key Advantages
- 23Cr-13Ni — oxidation resistant to about 1000 °C
- Common buttering layer for dissimilar steel welds (carbon to stainless)
- Good formability and weldability
- Better than 304/310 in sulphidising high-temperature atmospheres
Relevant Standards
- ASTM A276
- ASTM A240
- ASTM A312
- UNS S30908
Typical Applications
- Automotive exhaust manifolds and catalyst housings
- Boiler burners and furnace structural parts
- Transition layer in carbon-to-stainless clad plate
- Annealing covers and heat-treat furnace internals
- Cement and glass industry heat-resistant parts
Why Buy from Hangbo Alloy?
- Factory-direct manufacturer — founded 2012, headquartered in Shanghai Songjiang
- Full product range — bar, plate, sheet, strip, tube, forging, welding wire, flanges and machined parts
- Certified quality — ISO 9001:2015, GB/T 19001-2016, GJB 9001C-2017, EN 10204 3.1 mill test certificates with third-party inspection (SGS / BV / TUV) available on request
- Complete mill documentation — chemical analysis, mechanical test, ultrasonic test (UT), hardness and grain-size reports with every shipment
Contact Us — Shanghai Hangbo Alloy Group Co., Ltd.
Shanghai Hangbo Alloy Group Co., Ltd.
📍 4F, Building 22, No. 85 Mingnan Road, Songjiang District, Shanghai 201613, China
📞 Tel / WhatsApp: +86 15618279078
✉️ Email: demi@nickel-alloy.com
🕒 Available 24 hours a day, 7 days a week — enquiries answered around the clock.
Send your drawing or enquiry (grade, form, size, quantity, standard) for a same-day quotation.
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Frequently asked questions
Can 309S filler metal replace 304/316 welding wire?
Not as a direct replacement. 309S's high Cr/Ni tolerates the higher heat input of dissimilar joining (carbon steel to stainless or stainless to heat-resistant steel) and is the preferred buttering and transition layer. When used to weld 304 or 316 base metal, the deposit chemistry far exceeds the parent, producing high residual stress and a different CTE, and the cost is unjustified. For same-grade welds use 308L (for 304 base) or 316L (for 316 base).
What forms and sizes are available?
We supply Stainless Steel 309S as round bars (φ2–600 mm, up to 12 m), plates & sheets (0.5–100 mm thick, up to 2500 mm wide), seamless tubes & pipes (φ6–630 mm OD, 0.5–40 mm wall), welding wire & coils (1.0–5.0 mm), forgings & rolled rings (up to 7500 kg, 3500 mm OD). Custom lengths, tolerances and machining to drawing are available on request.
What is the MOQ and lead time?
MOQ is flexible — trial orders from a single piece are welcome. Stock sizes ship in 3–7 days; custom forgings and machined parts typically 15–35 days depending on quantity and process.
Can you provide third-party inspection and shipping to my port?
Yes. SGS / BV / TUV or your nominated inspector can witness all tests before shipment. Full export documentation is provided, and we ship worldwide by sea or air on FOB, CIF or DDP terms.