409 stainless steel plate
Jan 30, 2026
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Overview and Designations
409 is a ferritic stainless steel stabilized with titanium, designed for high-temperature applications where the corrosion load is moderate. It is one of the most economical stainless grades and is the standard material for automotive exhaust systems. The grade is designated UNS S40900 in ASTM A240, EN 1.4512 (X6CrTi12) in the European system, and SUS409L in the JIS system, with the Chinese designation 022Cr11Ti under GB/T 1220. In many markets 409 costs roughly 30–50% less than 304 or 316L, which makes it attractive for large-volume components.
Chemical Composition and Mechanical Properties
The composition and minimum mechanical properties below are specified for plate in ASTM A240.
| Element | Content |
|---|---|
| C | ≤0.08 |
| Mn | ≤1.00 |
| P | ≤0.045 |
| S | ≤0.030 |
| Si | ≤1.00 |
| Cr | 10.5–11.75 |
| Ni | ≤0.50 |
| Ti | 6 × C minimum, 0.75 maximum |
| N | ≤0.03 |
| Property | Value |
|---|---|
| Tensile strength | 380 MPa |
| Yield strength | 170 MPa |
| Elongation in 2 in | 20% |
The EN equivalent 1.4512 (X6CrTi12) is specified with a lower carbon maximum and a similar titanium stabilization range under EN 10088-2.
Oxidation and Corrosion Behaviour
409 resists oxidation at high temperature and is commonly rated for continuous service up to about 870°C in exhaust and furnace applications. The titanium addition prevents sensitization and intergranular corrosion in welded components. In corrosion terms, however, 409 is a ferritic grade with roughly 11% chromium: it offers far better resistance than carbon steel and good performance in dry or mildly corrosive exhaust condensate, but it is not suitable for chloride-rich or strongly acidic environments where 304 or 316L would be required. The grade is magnetic.
Applications
Automotive exhaust systems dominate the demand: exhaust manifolds, catalytic converter shells, mufflers, tailpipes and heat shields. Other uses include heat exchanger casings, furnace components, agricultural equipment, and structural parts where high-temperature resistance is needed at lower cost than austenitic grades.
Fabrication and Welding
409 is readily formed and welded. MIG and TIG welding with a matching ferritic filler, typically ER409Nb, is standard, and the material welds well in thin gauges used for exhaust components. Control heat input to limit grain growth, which can reduce toughness in the heat-affected zone, and avoid preheat unless the thickness and restraint require it. Because the grade is ferritic, magnetic forming and handling equipment can be used, and the lower yield strength compared with austenitic grades makes it easy to bend and roll.
Frequently Asked Questions
Q1. Is 409 stainless steel magnetic?
Yes. It is a ferritic grade, so it is magnetic in all conditions.
Q2. What is 409 stainless steel used for?
Mainly automotive exhaust systems including manifolds, mufflers and catalytic converter shells, plus heat exchangers, furnace parts and agricultural equipment.
Q3. Can 409 replace 304?
Only where the environment is dry or mildly corrosive and the temperature is high. For chloride or strongly acidic service, 304 or 316L is required.
Q4. What is the difference between 409 and 409L?
409L is a lower-carbon variant that gives improved weldability, commonly used for exhaust tubing; SUS409L is the JIS designation.
Q5. How much cheaper is 409 than 304 or 316L?
Typically about 30–50% less, which is why it dominates cost-sensitive, high-volume exhaust applications.
Q6. Can 409 be welded?
Yes, with MIG or TIG using a matching ferritic filler such as ER409Nb, while controlling heat input to limit grain growth.
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