409 stainless steel plate remains one of the lowest-cost stainless grades in 2025 while delivering the mix of heat resistance, weldability and economy prized by automotive and lightweight industrial applications. Typical market prices in mid-2025 for commercial 409 plate range roughly USD $1,000–$2,200 per metric tonne (≈ $1.0–$2.2 per kg) depending on region, thickness, finish and order size; China and large export mills usually sit at the low end, India mid-range, and North America/Europe carry premiums and additional processing surcharges.

What is 409 stainless steel (definition & brief history)

We treat 409 as a titanium-stabilized ferritic stainless steel originally developed for exhaust and muffler systems where resistance to oxidation at elevated temperature plus low cost are primary requirements. It typically contains about 10.5–11.8% chromium and small amounts of titanium for stabilization; nickel is minimal. The grade appeared in the mid-20th century as a practical alternative to coated carbon steel in automotive exhaust systems.

Chemical composition & standards (UNS / EN / ASTM)

We report the common compositional window used in specifications:

• Chromium (Cr): ~10.5–11.75%

• Carbon (C): ≤ 0.08% (depends on sub-grade)

• Titanium (Ti): added to stabilize carbon and avoid chromium carbide precipitation (typical Ti ≤ 0.75%)

• Nickel (Ni): usually <0.5% (many formulations specify trace Ni only)

• Mn / Si / P / S: kept low per standard practice.

Formal designations and cross-references: UNS S40900, European EN number 1.4512, and commonly produced to plate/sheet specifications such as ASTM A240 (plate/sheet for stainless steel). These standards provide chemical, mechanical and testing requirements commonly requested by OEMs and fabricators.

Key mechanical & physical properties

In typical annealed plate condition we use the following ballpark values (mill data vary by thickness and producer):

• Tensile strength (approx): ~400–550 MPa (depends on temper and thickness)

• Yield (0.2%): ~200–300 MPa

• Elongation: commonly ≥20–25% (in 50 mm gauge)

• Hardness: moderate; easy to form and bend compared with martensitic grades.

Density and thermal expansion are similar to other ferritic steels; thermal conductivity is higher than austenitic grades, which helps in heat-cycling exhaust components. For exact design numbers use the supplier’s mill test report or MatWeb / technical datasheets.

High-temperature performance and oxidation behaviour

We specify that 409 performs well in intermittent exhaust temperatures and offers a thin protective oxide layer in common exhaust atmospheres. It is not a high-alloy, high-nickel heat-resistant alloy; rather it balances economy with acceptable oxidation resistance up to several hundred degrees Celsius. Where continuous high temperatures or aggressive chloride/acid exposure occurs, higher alloyed grades (e.g., 304/316 or dedicated heat-resisting steels) are preferred.

Variants: 409L, 409M and stabilized forms

We highlight common variants you will encounter in procurement:

• 409L: lower carbon, easier to weld, less risk of carbide precipitation — used where welding or post-weld corrosion resistance matters.

• 409M: modified for specific mechanical or forming needs in some markets.

• Stabilized versions (Ti/Nb): additional stabilizers (niobium or controlled Ti) for heavy-section welding, furnace cycles.

Always match the sub-grade to the application and ask the mill for the exact spec (chemical table) — names vary across regions.

Typical applications (why buyers choose 409)

We list the most common uses:

• Automotive exhaust systems (mufflers, pipes, heat shields) — dominant application.

• Heat exchangers for non-aggressive media.

• Light industrial housings, outdoor equipment where low corrosivity and temperature cycles are present.

• Cost-sensitive non-cosmetic parts where surface appearance is not primary.

The combination of low alloy content, reasonable formability and low price keeps 409 widely used where appearance and long-term chloride resistance are not required.

Fabrication: forming, welding, machining guidance

We advise buyers and fabricators:

• Forming: 409 is ductile in the annealed condition and cold-formable; follow standard bend radii from the mill.

• Welding: good weldability (Ti stabilization reduces sensitization). Use filler metals compatible with ferritic base metal when required; preheat and post-weld treatments depend on section thickness.

• Machining: not as free-cutting as austenitics; chip control and speeds should be selected per supplier guidance.

• Surface finishes: hot-rolled (HR), cold-rolled (CR), or 2B/BA finishes are available — specify finish in the PO.

Request weld procedure qualifications and sample welds for critical applications. Supplier mill test reports (MTRs) will list the heat analysis needed for QA/QC.

Corrosion limitations — what to avoid in service

We caution that 409 has limited resistance to chlorides and acidic environments; pitting and crevice corrosion occur in coastal or chemical exposures. It is designed for oxidizing exhaust gases and atmospheric use — not seawater or splashed salt environments without protective measures. If the service includes salt or chemical exposure, choose 304/316 or duplex grades.

Purchasing considerations (plate vs sheet, finish, thickness, MTRs)

When buying 409 plate, we recommend asking for:

• Exact specification (ASTM A240, EN 1.4512, UNS S40900) and sub-grade (409L/409M).

• Thickness and plate tolerance (hot-rolled vs cold-rolled; flatness requirements).

• Surface finish (2B, No.1, NO.8, pickled) and passivation if required.

• Mill test reports (MTRs): chemical, mechanical, heat number traceability.

• Certifications: ISO 9001, third-party inspection if needed.

• Packaging & shipping: protective film, oil coating, palletizing for export.

Specifying the right combination avoids later rejections and hidden costs.

Price drivers in 2025 (what moves 409 plate prices)

We explain the main factors that affect pricing today:

• Raw material prices: While 409 contains little nickel, chromium and ferroalloy costs still move price; LME nickel and ferrochromium swings feed stainless mills’ cost models.

• Steel mill operating rates and scrap availability: Domestic scrap prices and mill loads cause short-term volatility.

• Energy and freight: Gas/electric costs in steelmaking and global freight (containers) dictate export competitiveness.

• Processing and finishing: Cold rolling, annealing, pickling and thickness cutting incur extra costs; small orders pay higher per-unit.

• Regional premiums / tariffs / duties: Import duties or anti-dumping measures can produce large price differences between regions.

We always model quotes on current raw material inputs plus an agreed processing margin to keep bids realistic.

Global price comparison — mid-2025 indicative ranges (plate / sheet, commercial quality)

Note: the ranges below are aggregated from active supplier listings, B2B marketplaces and market price reporting; these are indicative ranges for commonly traded commercial 409 plate (bulk orders). Always request a formal current quote for firm pricing.

How to read the table: ranges overlap — the lower figures represent standard hot-rolled commercial plate purchased in large tonnages directly from mills or traders; the upper figures reflect cut-to-size, cold-rolled, special finish or small-lot orders plus inland freight and duties.

How we (Luokaiwei) price and quote 409 plate — practical checklist for buyers

When preparing a request for quotation (RFQ) we ask for:

• Material standard & grade (e.g., ASTM A240 Type 409 / 409L / UNS S40900).

• Thickness × width × length and tolerance class.

• Finish required (hot-rolled, cold-rolled, 2B, No.1).

• Quantity (tons or pieces) and delivery Incoterm (EXW, FOB, CIF).

• Inspection & test needs (MTR, PMI, third-party inspection).

• Packaging & export documentation (coating, timber packaging, fumigation).

We price based on the latest alloy surcharge inputs, mill availability and lead time; for steady production customers we offer rolling contracts to reduce volatility.

Sustainability and recycling note

We encourage buyers to note that 409 is highly recyclable: ferritic stainless scrap streams are accepted by mills and recycling reduces the primary alloy demand. When comparing life-cycle costs, the recyclability of 409 (and low alloy content) improves its environmental footprint relative to some higher-nickel grades, especially where long life and corrosion resistance are not the prime requirement.

FAQs

Q1 — Is 409 stainless steel “stainless” enough for outdoor use?
Short answer: yes for normal atmospheric exposure and temperature cycles (automotive exhaust, outdoor housings), but no for continuous saline or chemical exposures — choose 304/316 for coastal or chemical service.

Q2 — When should I choose 409L instead of 409?
Choose 409L when you expect heavy welding or require lowered risk of carbide precipitation after welding. 409L has reduced carbon for better post-weld corrosion resistance.

Q3 — How much cheaper is 409 versus 304 or 316?
Pricing depends on market conditions, but 409 typically trades significantly cheaper because it contains little/no nickel and lower chromium. In 2025, 409 pricing bands are generally ~30–60% lower than equivalent 304/316 commodity plate pricing in most markets — exact numbers vary by country and order.

Q4 — What inspection documents should I demand?
At minimum ask for an MTR (mill test report) showing chemical analysis and mechanical test results and the mill heat number. For critical applications require third-party certificates and a full traceability chain to the mill.

Q5 — Can 409 be used for food equipment?
Not generally recommended for food contact where long-term hygiene and corrosion resistance are mandatory; austenitic 300-series (e.g., 304, 316) are standard for food and sanitary equipment.