AISI/UNS 409 stainless steel coil remains one of the most cost-effective ferritic grades for exhaust and high-temperature service in 2025 — offering good weldability and oxidation resistance at a fraction of the cost of common austenitic grades. Typical market pricing in mid-2025 ranges broadly from ~USD 1,000 to USD 4,000 per metric tonne depending on region, quantity, finish and whether the sheet/coil is aluminized or specialty-treated. For buyers, the single biggest levers on landed cost are raw-material scrap indices and regional supply/demand imbalances; for designers, the trade-offs are lower corrosion resistance compared with 300-series but much better economy for high-temperature applications.
What is 409 stainless steel
We use the term 409 to mean the titanium-stabilized ferritic chromium stainless steel commonly referenced as AISI 409 / UNS S40900 / EN 1.4512 (X2CrTi12). It’s a low-nickel, low-cost ferritic grade with nominal chromium around 10.5–12.5% and titanium added to stabilize carbon/nitrogen against sensitization. The grade was developed for automotive exhaust systems where high temperature oxidation resistance and weldability are required but the highest corrosion resistance is not necessary.
Key mechanical and high-temperature properties
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Corrosion behaviour: Better than plain carbon steel and often similar to low chromium martensitic grades; it will develop a light surface oxide in many atmospheres and is not suited where pitting/crevice corrosion resistance is critical.
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High-temperature scaling: Continuous service up to about 675°C; intermittent exposures to higher temperatures (up to ~815°C) are possible depending on environment.
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Weldability & formability: Generally very good for a ferritic grade; titanium stabilization improves resistance to sensitization in welded HAZ.
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Typical mechanicals (annealed): tensile ~380–550 MPa range, yield ~≥170 MPa and elongation ~20% (manufacturer data vary).
Standards, designations and equivalent names
Common identifiers you’ll see in purchase orders, datasheets and specifications:
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AISI / SAE: 409
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UNS: S40900
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EN / Werkstoff: 1.4512 / X2CrTi12
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ASTM / ASME: often referenced under ASTM A240 / ASME SA-240 for flat-rolled products (confirm spec paragraph for exact subgrade).
When specifying, always give the UNS/AISI and the required finish (cold-rolled 2B, hot-rolled annealed & pickled, aluminized, etc.) plus mechanical limits and test requirements.
Mill forms, finishes and value-adds
We see 409 supplied as:
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Cold-rolled coils (2B/2D finishes) and slit coils for stampings.
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Hot-rolled annealed & pickled (HRAP) coil and sheet for heavier gauges.
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Aluminized (Type-1 hot dip Al coating) commonly used for mufflers to extend life in corrosive road environments.
Finish, coil weight, slit width and surface treatment are common price multipliers: aluminized and specialty surface treatments add a premium.
Typical 2025 applications (why buyers choose 409)
We still see the classic applications:
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Automotive exhaust components (mufflers, resonators, pipes) — the original major market.
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Industrial high-temperature ducting and heat exchangers where cosmetic finish is secondary.
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Cost-sensitive sheet metal parts exposed to hot oxidizing gases.
Because designers value predictable weldability and oxidation resistance at a moderate price, 409 is often the “economy” choice where 304/316 would be over-specified.
What controls the market price in 2025
When we price coils, we monitor several things in real time:
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Ferronickel / scrap and recycled steel indices. Although 409 is low-nickel, general stainless scrap indices and alloy surcharges set base levels.
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Crude energy and freight: energy costs affect mill electricity and melting; ocean freight affects FOB→landed comparisons.
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Regional demand (auto production, replacement markets): OEM orders and automotive production schedules materially alter lead times and premiums.
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Import tariffs and antidumping actions: trade policy drives where buyers source and can create abrupt price differentials.
2025 global price snapshot
Notes: the ranges below reflect typical supplier FOB/EXW offers in mid-2025 for standard cold-rolled or HRAP 409 coil in commercial weights (not specialty aluminized). Prices vary by MOQ, finish, certification and exchange rates. Sources cited per row.
| Region | Typical 2025 price (USD / metric tonne) | Notes / representative source |
|---|---|---|
| China (FOB factory) | ~USD 1,000 – 3,000 / t | Many China coil offers list $1–5/kg depending on surface and MOQ. |
| India (domestic mill / trader) | ~USD 1,500 – 4,000 / t (INR equivalents often quoted) | Indian posted price lists and trader quotes show wide bands depending on quality and finishing. |
| USA (domestic mills / distributors) | ~USD 1,800 – 4,500 / t | U.S. distributor and mill list prices typically carry higher processing/distribution components; tariffs or antidumping may lift landed price. |
| Europe (mill/distributor) | ~USD 2,000 – 4,500 / t | European mills face import pressure from Asia but maintain higher base costs for energy/standing charges. |
| Middle East (regional stockists) | ~USD 1,300 – 3,500 / t | Often sourced from Asian mills with freight adders; specialty treated metal adds margin. |
(Use these ranges as an informed negotiating baseline — always obtain current firm quotes and check lead times.)
Regional notes & practical buying tips
China
China remains the largest supply hub for standard 400-series coils. Typical FOB quotes on online B2B platforms start very low ($1–3/kg) for Brown-box production lots but buyers must confirm chemical certificates, coil ID, and mill traceability. For high volumes we use audited mills and insist on chemical & mechanical reports.
India
Domestic prices are influenced by local scrap, import tariffs, and manufacturer inventories. Indian traders often price in INR per ton slabs; cross-checking with international offers is standard practice.
Europe & USA
Europe and North America can show higher nominal price floors because of energy, environmental compliance and quality assurance overhead. Trade flows (cheap Asian imports) put downward pressure on European mills; U.S. tariffs and antidumping sometimes offer temporary price shelter. When we buy for the U.S., we compare domestic mills vs. imported FOB + duties.
How we (seller / buyer) quote & validate a 409 coil order
When producing a PI/PO or requesting a quote, we (as sellers) include:
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Exact UNS/AISI / EN designation (e.g., UNS S40900 / EN 1.4512).
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Coil weight, width, thickness tolerance, surface finish (2B, 2D, HRAP), edge condition (cut/coil), and any coating (aluminized).
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Testing: chemical analysis (ICP), tensile test, hardness, intergranular corrosion or corrosion resistance report if requested.
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Packing & shipping incoterm (EXW / FOB / CFR / CIF) with clear lead times.
We always require mill test certificates (MTCs) and run incoming inspection (ID stamping, dimensional checks, surface inspection, and reconciliation of chemical & mechanical values).
Manufacturing & processing notes (what engineers should know)
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Welding: 409 welds well with standard stainless fillers when needed; avoid overheating HAZ — titanium stabilizer helps prevent chromium carbide precipitation.
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Forming / stamping: cold-forming is straightforward for typical stamping operations, but springback of ferritic grades differs from austenitics — validate die compensation.
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Heat treatment: 409 is not significantly hardenable by heat treatment; annealing cycles are used for stress relief and to reset properties.
Substitutes, upgrades and selection checklist
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If you need higher corrosion resistance: consider 430 for some uses, but for significant improvement consider 304/304L or 316 (costs rise markedly).
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If high temp oxidation resistance and aluminized surface life is needed: order 409-AL (aluminized) which extends life in muffler conditions.
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If weld HAZ is a concern: specify low-carbon variants (409L) or nickel-modified 409 variants when available.
Selection checklist (we use this in RFQs): required operating temperature, ambient corrosivity (road salt, acidic fumes), cosmetic acceptance, target component life (years), expected quantities / batch sizes, and welding/specification constraints.
FAQs
Q1 — What is a realistic lead time for standard 409 cold-rolled coil?
A: For in-stock coils from distributors: 1–3 weeks depending on slit/pack requirements. For mill direct production: 4–8 weeks is common in 2025, variable with mill backlog and certification needs.
Q2 — Is 409 magnetic?
A: Yes — 409 is a ferritic stainless steel, therefore it is magnetic at room temperature (unlike austenitic 300-series).
Q3 — Can 409 be used outdoors without surface treatment?
A: It will resist oxidation better than mild steel, but in aggressive marine or chloride environments it can develop surface staining or light rust. For outdoor or road-salt exposure, aluminized 409 or higher-chromium grades are recommended.
Q4 — How do I interpret a supplier quote for “409 coil USD X / kg”?
A: Confirm whether the price is FOB, EXW or CIF, the finish (cold/hot born), coil weight, MOQ, and whether surface treatment is included. Small order premiums and ASTM/EN certification typically add cost.
Q5 — Are there common test requirements we should add to the PO?
A: Yes — at minimum: MTC (chemical & mechanical) per the specified standard, ultrasonic or eddy-current surface test for critical components, and witness testing for large orders. If for automotive OEMs, include PPAP / agreed Q-documents as required.
