409 Stainless Steel
An 11% chromium titanium-stabilized ferritic stainless, for exhausts
Typical values for the temper in the title
409 is the cheapest common stainless: about 11% chromium, right at the lower limit of "stainless", and stabilized with titanium so it welds without trouble. It does not stay bright (light surface rust appears), but it does not corrode through.
It was built for automotive exhaust systems: resistant to heat and exhaust-gas corrosion, weldable on production lines, and cheap.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | 380-450 MPa | |
| Yield strength Rp0.2 | 170-205 MPa | |
| Elongation A | 20% | |
| Hardness | 130-160 HB | |
| Modulus of elasticity E | 200 GPa | |
| Density ρ | 7.75 g/cm³ | |
| Machinability | 65% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| Cr chromium | 10.5–11.7 | basic corrosion resistance |
| Ti titanium | min 6×(C+N), up to 0.50 | stabilization for welding |
| C carbon | max 0.030 | |
| N nitrogen | max 0.030 | |
| Ni nickel | max 0.50 | |
| Mn manganese | max 1.00 | |
| Si silicon | max 1.00 | |
| Fe iron | balance |
Ranges per ASTM A240 (plate and sheet). PREN values per 3-A and IMOA.
Conditions and heat treatment
Ferritic stainless is not hardened by heat treatment, and it is magnetic in every condition.
| Condition | Properties | When to choose it |
|---|---|---|
| Annealed | relatively soft, magnetic | the normal delivery condition |
| Not hardenable by heat treatment | — | strength is set only by cold work |
| When hot: "475 °C embrittlement" | prolonged exposure at about 400–550 °C lowers ductility | mainly in higher-chromium grades |
Applications
- Automotive exhaust systems
- Mufflers and converter shells
- Parts in moderate heat
- Agricultural containers
- Inexpensive structural parts
Fabrication
Welding
Welds well thanks to titanium stabilization, including on automated production lines.
Forming
Forms well, but less than austenitic stainless, especially in deep drawing.
Corrosion
Almost immune to chloride stress corrosion cracking, an advantage over 304. Pitting resistance depends on chromium and molybdenum.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| 439 | 415-565 / 245 MPa | Good — Ti stabilized | more chromium, more resistant · material page |
| 430 | 450-600 / 275 MPa | Medium — Grain Growth risk | more chromium, not stabilized · material page |
| 321 | 515–620 / 205–310 MPa | Excellent — Ti Stabilized | an austenitic stabilized grade for heat, much more expensive · material page |
Common mistakes
Assuming a magnet that sticks means "fake stainless"
Ferritic stainless is magnetic by nature. Magnetism does not mean the material is not stainless.
Using ferritic grades for prolonged service at about 400–550 °C
In that range the higher-chromium grades become brittle.
Choosing 409 for a part that must stay bright
Over time light surface stains appear. For appearance, 430 or 304.
Equivalents, standards and supply
| EN | 1.4512 |
|---|---|
| DIN | X2CrTi12 |
| ASTM | 409 |
| JIS | SUS409L |
| Standards | ASTM A240 / EN 10088-2 / SAE J405 |
| Forms | plate · strip |
| Producers | Outokumpu · JFE Steel · POSCO · Valbruna |
Learn more
Values are typical and for comparison only. For design, rely on the standard and on the mill certificate. Sources: ASTM A240, ASTM A276 and EN 10088 (composition), producer data sheets, and the METAL HUB materials database.
Updated: October 31, 2026