405 stainless steel plate (UNS S40500 / AISI 405) remains a cost-effective option in the 400-series family for welded fabrications in non-severe corrosive environments; typical 2025 bulk FOB prices from Chinese mills range roughly US$1.1–3.5 per kg depending on thickness, finish and order size, while spot retail/market prices in North America and Europe are higher after processing, freight and duties.

What is 405 stainless steel?

We refer to "405" as the SAE/AISI type that is most commonly represented by UNS S40500 (sometimes seen as EN 1.4003 / X2CrNi12 in European notation). It sits inside the 400-series family and is used where good weldability with acceptable corrosion resistance is required. 405 is often specified in plate, sheet and strip for fabrications that cannot be annealed after welding.

Chemical composition and microstructure

405 is a chromium-bearing steel with chromium levels typically near 12% and low carbon; minor nickel additions (trace to ~1%) appear in some spec variants. Typical ranges and tabulated compositions are documented in industry datasheets and material libraries. The alloy is normally ferritic (non-austenitic) and often supplied in an annealed condition that gives good ductility for forming and welding.

Key takeaway for material selection: chromium content gives a passive film and the low carbon helps avoid excessive sensitization; the ferritic structure means magnetic behaviour and a different response to heat treatment than austenitic grades.

Mechanical & physical properties (practical numbers)

In annealed condition 405 typically shows moderate strength and reasonable elongation. Typical values reported by materials databases and manufacturer datasheets include:

• Density: ~7.78–7.8 g/cm³.

• Tensile strength (annealed): on the order of 400–500 MPa (varies with supplier).

• Yield strength: commonly in the 200–300 MPa band.

• Elongation: usually high enough for plate forming operations (20%+ in many datasheets).

These numbers make 405 suitable for light-to-moderate structural use, brackets, flanges and welded enclosures where very high corrosion resistance is not required.

Corrosion resistance and operating environment

405's corrosion resistance is modest compared with 300-series stainless steels. Chromium near 12% creates a passive layer, but the material is more vulnerable to pitting and crevice corrosion in chloride-rich environments and to high-temperature oxidation if the correct finish or alloy variant is not chosen. For design decisions, industry modules and guidance on corrosion behaviour explain the link between chromium content, passive film stability and environmental exposure.

In practice we specify 405 only for atmospheres or process streams where corrosion stress is low to moderate — e.g., interior partitions, annealing boxes, quench racks, steam nozzle supports — not for marine or acidic process services.

Fabrication: welding, forming and heat treatment

We prefer 405 for welded fabrications because it is designed to be usable in the as-welded condition — unlike some ferritic/martensitic grades that harden or crack during welding. Shielded fusion and resistance welding methods are commonly recommended; post-weld anneal may improve ductility where needed. 405 can also be heat-hardened under controlled cycles for specific mechanical requirements.

Machinability is generally acceptable for typical plate operations; however the ferritic matrix behaves differently from austenitic grades (different tool speeds and feeds). We advise discussing machining allowances with your contract shop when tight tolerances are critical.

Typical uses and why specifiers choose 405

Common uses we see:

• Quenching racks, annealing boxes, furnace components.

• Structural panels/partitions in industrial equipment that require weldability.

• Low-to-moderate corrosion environments where cost efficiency is important.

The selling point is cost-to-performance: adequate corrosion resistance for many dry or low-chloride environments with superior weldability versus some other 400 series options.

How price is formed (what moves the number)

Multiple factors determine the final plate price:

• Raw material costs (Fe, Cr, Ni): nickel and chromium commodity prices are the largest inputs to stainless costs.

• Form & thickness: cold-rolled thin plate and fine surface finishes cost more than hot-rolled industrial plate.

• Surface finish: 2B, BA, NO.4, mirror — each step adds cost.

• Order size (MOQ): single sheets vs. tonnage orders — unit price drops with volume.

• Processing (cutting, levelling, slitting): added machining increases landed cost.

• Logistics, duties and local taxes: region to region these can materially shift the buyer price.

• Lead time & market tightness: mills’ spot inventories or embargoes create premiums.

We always recommend quoting to include thickness, width, length, surface finish and certification requirements to avoid surprises.

8 — 2025 global price comparison (representative ranges)

Below is a practical table we prepare for tendering and market planning. These are indicative ranges for bulk plate (FOB mill for Chinese supply, and approximate landed/retail bands elsewhere). Prices change daily — use these for planning and ask suppliers for live quotes.

Sources for mill/market listings: several China-based supplier boards and B2B marketplaces show 405 plate entries around US$1.09/kg and up depending on MOQ and finish; Alibaba listings corroborate a broad band depending on thickness and lot size. Use these ranges for budgeting; confirm live quotes for procurement.

How to interpret the table: the lower bound commonly requires large tonnage and a simple hot-rolled finish. If you require cold-rolled, high-polish, tight flatness or certified traceability (mill test certs to ASTM/EN), expect the right side of the range.

Stock sizes, finishes and tolerances that change price

Common stock sizes: 1000×2000 mm, 1219×2438 mm, 1500×3000 mm, 1500×6000 mm — plate thicknesses from 0.3 mm (thin) to 10 mm+ (hot-rolled). Typical finishes: 2B, BA, No.4, hairline and 8K mirror. Heavy finishing or special tolerances add to processing time and cost. Manufacturer product pages from large mills list the exact size grids and finish options.

Standards & certifications to request (we always include these)

When you buy plate specify the standard and documentation you require. Common references:

• ASTM A240 / ASME SA-240 (plate/sheet standards) for general stainless plate.

• UNS S40500 or EN 1.4003 / X2CrNi12 for material designation.

• Mill Test Certificate (3.1/3.2) where required, plus surface finish and thickness certificates.

Insist on clear specification in the purchase order to avoid grade mixups (405 vs austenitic 304/316 or martensitic 410, which have different costs and application envelopes).

Substitutes: when to pick something else

Choose a higher-grade stainless if you need chloride resistance, higher oxidation resistance or food-grade corrosion protection. Typical alternatives:

• 304 / 304L — when corrosion resistance for humid/food service is needed (higher cost).

• 430 — decorative ferritic with different forming properties (cost similar, but different corrosion tolerance).

• 410 / 420 — martensitic grades for higher wear resistance (can be heat treated but less weldable).

We weigh performance vs cost: avoid underspecifying 405 for chloride-rich or marine exposures.

Market drivers & risk factors for 2025–2026

Key influences on the price of 405 plate in 2025:

• Chromium and nickel commodity moves. Nickel is especially volatile; even small global supply swings affect stainless pricing.

• Mill capacity & scrap availability. Mill maintenance or scrap shortages can cause short-term premiums.

• Freight rates & trade policy. Shipping costs and duties materially alter landed cost per kg for importers.

• Demand from adjacent sectors (automotive, refinery turnarounds). Large procurement programs create temporary demand spikes.

Procurement teams should lock price exposure or include ARRs (annual rolling rates) for large projects.

Buying checklist — what we require before we quote

When you request a quote, include:

• Grade & standard (e.g., 405 / UNS S40500 / ASTM A240)

• Thickness, width, length and tolerance class

• Surface finish required (2B, BA, NO.4, mirror)

• Quantity (kg or tons) and delivery terms (FOB, CIF, DAP)

• Required certificates (MTC 3.1 / 3.2, PMI test, PMI report)

• Any heat treatment requirements or certifications for welding

Supplying these avoids back-and-forth and ensures an apples-to-apples comparison.

Practical examples from our procurement files

From recent RFQs we handled, large lots (≥10 tons) of hot-rolled 405 plate in China with 2B finish quoted near the lower end of the FOB band, while small orders (≤1 ton) with BA finish or cut-to-size saw unit prices 40–150% higher after cutting and packing. Mill minimum order quantities and cutting fees drive up small-lot prices.

FAQs

Q1: Is 405 a good choice for outdoor architectural panels?
Short answer: usually not the best. For sheltered, dry conditions it can work, but for coastal or high-humidity exposure we recommend a higher chromium or an austenitic grade like 304/316 instead.

Q2: Can 405 be used for food contact surfaces?
No — 405 is not a typical food-grade alloy. For food or beverage contact we specify 304/316 with appropriate surface finish and certification.

Q3: How do I reduce cost when ordering 405 plate?
Order larger tonnages, accept hot-rolled finishes, standard widths and avoid tight flatness/finish tolerances. Consolidating requirements into single purchase orders reduces per-kg processing and handling fees.

Q4: Which tests should I request on the certificate?
At minimum request chemical composition and mechanical test results on a Mill Test Certificate (MTC). For critical parts add PMI or lab spectro verification and hardness tests when heat treatment is involved.

Q5: If I need better corrosion resistance but similar cost, what can I consider?
Consider 430 or some stabilized ferritic grades if your environment is mildly corrosive but doesn’t require the expense of 304/316. Otherwise evaluate coatings or passivation treatments — those can sometimes be more cost-effective than a full material upgrade.