AISI 409 Stainless Steel Plate | A240 Type 409 | UNS S40900
What is AISI 409 Stainless Steel?
As a professional China steel mill-Direct Supply and stainless steel plate supplier, SHH STEEL is pleased to present AISI 409 Stainless Steel Plate.
AISI 409 is widely known and searched under many different names and designations, including AISI 409, ASTM A240 Type 409, ASME SA240 Type 409, UNS S40900, 409 stainless steel, 409 stainless steel plate, SUS409, 1.4512, X2CrTi12 and 06Cr11Ti. All these names refer to the same titanium-stabilized 11% chromium ferritic stainless steel.
AISI 409 contains approximately 10.5–11.75% chromium with intentional titanium addition. Titanium combines with carbon and nitrogen to stabilize the grade against intergranular corrosion after welding. Carbon is kept low, so AISI 409 remains ferritic, magnetic and non-hardenable by conventional heat treatment. It offers a cost-effective balance of heat resistance, oxidation resistance and weldability, which is why it became a standard material for automotive exhaust systems.
SHH STEEL supplies AISI 409 as true China steel mill-Direct Supply, sourcing directly from major Chinese stainless steel mills. This model delivers competitive mill pricing, consistent quality, complete heat traceability and reliable delivery. SHH STEEL offers AISI 409 in plate and sheet form across a practical range of thicknesses and surface finishes.
AISI 409 is frequently compared with A240 409L, A240 410, A240 410S, A240 430, A240 439 and A240 441. SHH STEEL provides technical support to help customers choose the most appropriate 400-series grade.
Material Specification
| Specification Element | Requirement | SHH STEEL Compliance |
|---|---|---|
| Grade | AISI 409 / A240 Type 409 / UNS S40900 | Confirmed |
| Related Standards | ASTM A240, ASME SA240, JIS (SUS409), EN 1.4512 | Available |
| Product Form | Plate, Sheet | Available |
| Delivery Condition | Annealed | Standard |
| Thickness Range | 0.4 mm – 50 mm (thicker available on request) | Custom sizes supported |
| Width | Up to 1500–2000 mm | Available |
| Length | Up to 6000–12000 mm or coil / cut-to-length | Available |
| Surface Finish | 2B, No.1, 2D, and others on request | Available |
| Certification | EN 10204 3.1 / Mill Test Certificate | Available |
SHH STEEL can supply dual-certified ASTM A240 / ASME SA240 Type 409 material when required by the project.
Chemical Composition
Typical Chemical Composition of AISI 409 (UNS S40900):
| Element | Content (%) |
|---|---|
| Carbon (C) | ≤ 0.08 |
| Silicon (Si) | ≤ 1.00 |
| Manganese (Mn) | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 |
| Chromium (Cr) | 10.50 – 11.75 |
| Nickel (Ni) | ≤ 0.50 |
| Titanium (Ti) | 6 × (C + N) min – 0.75 max |
| Nitrogen (N) | ≤ 0.03 |
| Iron (Fe) | Balance |
The defining feature of AISI 409 is titanium stabilization in an 11% chromium ferritic base. Titanium ties up carbon and nitrogen, reducing the risk of intergranular corrosion after welding and improving high-temperature scaling behavior in exhaust service. SHH STEEL carefully controls the titanium-to-carbon ratio to keep AISI 409 weldable and stable.
Mechanical Properties
Annealed Condition (typical ASTM A240 values)
| Property | Value |
|---|---|
| Tensile Strength | ≥ 380 MPa (55 ksi) |
| Yield Strength (0.2%) | ≥ 170 MPa (25 ksi) |
| Elongation (in 50 mm) | ≥ 20% |
| Hardness | ≤ 179 HBW |
AISI 409 is supplied annealed, with moderate strength and good formability for stamping, bending and welding. It is magnetic and does not harden by quench and temper. SHH STEEL supplies AISI 409 plate and sheet meeting A240 mechanical limits.
Physical Properties
Density is approximately 7.70–7.75 g/cm³. Melting range is approximately 1480–1530°C.
Material Comparison
| Grade | UNS | Cr (%) | Stabilization | Corrosion / Heat Resistance | Typical Preference |
|---|---|---|---|---|---|
| AISI 409 | S40900 | 10.5–11.75 | Titanium | Good exhaust oxidation | Automotive exhaust and welded 11% Cr |
| AISI 409L | S40903 | 10.5–11.75 | Ti, lower C | Similar, better welding | Low-carbon exhaust / welded service |
| AISI 410S | S41008 | 11.5–13.5 | Low carbon | Moderate | Welded 12% Cr constructions |
| AISI 430 | S43000 | 16–18 | None | Better atmospheric | Decorative / general ferritic |
| AISI 439 | S43035 | 17–19 | Titanium | Better oxidation | Higher-Cr exhaust / welded ferritic |
| AISI 441 | S43932 | 17.5–18.5 | Nb + Ti | Better high-temp strength | Premium exhaust systems |
AISI 409 is the economical ferritic choice for exhaust and mildly oxidizing service. When lower carbon and easier welding are specified, SHH STEEL recommends A240 409L. For higher chromium and better corrosion or oxidation resistance, compare with A240 430, A240 439 and A240 441.
Corrosion Resistance
AISI 409 offers moderate corrosion resistance. Chromium at 10.5–11.75% provides useful oxidation resistance for exhaust gas and mild atmospheres, while titanium stabilization protects welded joints. It is widely used where painted carbon steel is not enough and 304 would be unnecessary cost.
AISI 409 is not intended for aggressive chlorides, marine splash zones or strong acids. In those environments SHH STEEL recommends a240 304, a240 316l or higher-alloy ferritics such as A240 444.
Weldability
AISI 409 has good weldability for a ferritic stainless steel because of titanium stabilization and relatively low carbon. Matching 409 or 409L / 439-type fillers are commonly used for exhaust and fabricated parts.
Heat input should be controlled to limit grain growth in the heat-affected zone. AISI 409 does not air-harden like Type 410. SHH STEEL recommends proper welding procedures and post-weld cleaning for exhaust and process fabrications.
Heat Treatment
AISI 409 is normally supplied in the annealed condition by SHH STEEL.
Annealing restores ductility after cold forming and optimizes corrosion resistance. The grade cannot be hardened by conventional quench and temper. SHH STEEL controls heat treatment so AISI 409 remains formable and weldable.
Surface Finishes
| Finish | Description | Typical Use / Keywords |
|---|---|---|
| 2B | Cold-rolled, annealed, pickled, skin-passed | AISI 409 2B – most common for sheet and thin plate |
| 2D | Cold-rolled, annealed and pickled | AISI 409 2D – forming and exhaust stampings |
| No.1 | Hot-rolled, annealed and pickled | AISI 409 No.1 / A240 409 No.1 – industrial plate |
| Special | Ground or custom finishes | AISI 409 Special – on request |
SHH STEEL regularly supplies AISI 409 in 2B, 2D and No.1 finishes for exhaust and fabrication use.
Tolerances
Dimensional tolerances for AISI 409 Stainless Steel Plate supplied by SHH STEEL generally conform to ASTM A480 practices.
Typical available size range is thickness 0.4 mm – 50 mm, width up to 1500–2000 mm, and length up to 6000–12000 mm or coil/cut-to-length. SHH STEEL provides precise dimensional control and can support tighter tolerances when required.
Equivalent Material Grades
| Grade / Designation | Standard / Region | Notes |
|---|---|---|
| AISI 409 | AISI | Main commercial keyword |
| A240 Type 409 | ASTM A240 / ASME SA240 | Plate specification |
| UNS S40900 | Unified Numbering System | Primary UNS designation |
| 1.4512 / X2CrTi12 | EN (Europe) | European equivalent |
| SUS409 | JIS (Japan) | Japanese equivalent |
| 06Cr11Ti / 0Cr11Ti | GB/T (China) | Chinese equivalents |
| Related 409L / 439 / 441 | Multiple | Low-carbon / higher-Cr variants |
Related grades for comparison include A240 409L, A240 410, A240 410S, A240 430, A240 439 and A240 441.
Applications
AISI 409 is selected for welded, heat-resistant fabrications where cost and oxidation resistance must be balanced. Typical applications of AISI 409 include:
| Industry / Sector | Typical Components / Equipment (with keywords) |
|---|---|
| Automotive Exhaust | AISI 409 exhaust pipes, mufflers, catalytic converter shells |
| Automotive Heat Management | AISI 409 heat shields, resonators and stamped exhaust parts |
| Agricultural & Off-Highway | AISI 409 exhaust and heat-resistant fabrications |
| HVAC & Heating | AISI 409 ducts, housings and welded heat parts |
| General Fabrication | AISI 409 tanks, covers and formed components |
| Industrial Equipment | AISI 409 No.1 plate for welded high-temperature parts |
SHH STEEL supplies AISI 409 for these exhaust and fabrication applications with consistent quality. For related industry solutions, see our equipment manufacturing, machinery industry and construction industry pages. Supporting services include steel cutting services and steel welding services.
Why Choose SHH STEEL
SHH STEEL is a China steel mill-Direct Supply specializing in stainless steel plate and sheet. By working directly with major Chinese stainless steel mills, SHH STEEL supplies AISI 409 with the following advantages:
- Genuine China steel mill-Direct Supply pricing
- Consistent quality and complete heat traceability
- Full Mill Test Certificates (EN 10204 3.1)
- Titanium-stabilized AISI 409 material optimized for exhaust and welded service
- Flexible dimensions and surface finishes (including AISI 409 2B, AISI 409 2D and AISI 409 No.1)
- Technical support for selection among AISI 409, 409L, 430, 439 and 441
- Value-added services including steel cutting services, steel welding services and worldwide shipping service
For more information about our company and full product range, please visit China steel Mill Agent-SHH STEEL.
FAQ
- What are the other common names for AISI 409?AISI 409 is also known as ASTM A240 Type 409, UNS S40900, SUS409, 1.4512, X2CrTi12 and 06Cr11Ti. SHH STEEL can certify the required designation.
- What is the difference between AISI 409 and AISI 409L?Both are titanium-stabilized 11% Cr ferritic grades. 409L has tighter low-carbon control for improved weldability. SHH STEEL recommends 409L when extra-low carbon is specified.
- Is AISI 409 the same as 410?No. 410 is a martensitic grade that can harden after welding. AISI 409 is a titanium-stabilized ferritic grade designed to stay non-hardenable. SHH STEEL supplies both and will confirm the UNS number before production.
- Is AISI 409 magnetic?Yes. AISI 409 is ferritic and remains magnetic in the annealed condition.
- What is the density of AISI 409?Approximately 7.70–7.75 g/cm³. SHH STEEL provides mill certificates confirming chemistry and mechanical properties.
- Can AISI 409 be used outdoors or in marine environments?It is suitable for exhaust and mild atmospheres. For outdoor architectural or marine chloride service, SHH STEEL recommends 430, 439, 444 or 316L.
- oes SHH STEEL supply dual-certified ASTM A240 Type 409 / AISI 409 material?Yes, SHH STEEL commonly supplies dual-certified material upon request.
Conclusion
AISI 409 Stainless Steel Plate is a titanium-stabilized 11% chromium ferritic grade designed for welded exhaust systems and cost-effective heat-resistant fabrications. It is the standard choice when oxidation resistance and formability are required without the cost of 304 or higher-chromium ferritics.
As a professional China steel mill-Direct Supply, SHH STEEL provides high-quality AISI 409 Stainless Steel Plate with competitive pricing, full certification and complete technical support.
Contact SHH STEEL today for stock availability, surface finish options (including AISI 409 2B, AISI 409 2D and AISI 409 No.1), or a competitive quotation.
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