Grade quotation brief
2304 vs 2205 Stainless Steel
Quote 2304 when measured water chemistry, structural exposure, design calculation and a qualified lean-duplex fabrication route establish sufficient margin. Quote 2205 when the project requires its different molybdenum-nitrogen balance, product availability or controlled service basis. PREN is only a screening index, and neither designation authorizes seawater, brine, wall reduction or substitution without project review.
Quote 2304 where the complete environment, design calculation and qualified fabrication route establish adequate lean-duplex margin. Quote 2205 when the project corrosion basis and code calculation require its different alloy and product route. PREN can organize candidates but cannot approve seawater, brine, a temperature limit or a material change; compare matching forms, tests, weld controls and dated quotations.
Unsure whether 2304 or 2205 matches the operating temperature and chemistry? Send the service conditions with the RFQ. We quote the approved designation, product form and test plan.
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Illustrations identify the compared grade references; they are not photographs of the quoted material or proof of a mill heat.
Decision matrix
Key Differences
Full grade sheets:2304 Stainless Steel/2205 Stainless Steel
| Factor | 2304 | 2205 | Procurement decision |
|---|---|---|---|
| Alloy and PREN | 2304 uses a leaner displayed alloy balance with little or no intentional molybdenum in its summarized chemistry. | 2205 has specified molybdenum and a different nitrogen range, producing a higher PREN screen. | Use PREN to shortlist candidates, then approve against the actual environment and fabrication condition. |
| Localized corrosion | 2304 is evaluated for controlled water, atmospheric and structural exposures with supporting evidence. | 2205 is evaluated where chlorides, crevices or process conditions narrow the accepted 2304 margin. | Provide temperature, chlorides, pH, oxidants, deposits, flow, stagnation and crevice details. |
| Strength and design | 2304 has duplex strength behavior whose values depend on product form, thickness and standard. | 2205 also has designation-specific values and code allowables that cannot be transferred from 2304. | Run the governing code calculation and retain stiffness, fatigue and minimum-fabrication checks. |
| Fabrication and supply | 2304 needs grade-specific solution condition, weld consumables, heat-input controls and availability checks. | 2205 follows its own qualified duplex route and may have a different ecosystem of matching components. | Confirm the entire bill, WPS/PQR, phase or ferrite checks, toughness and inspection before approval. |
Service and production route
Corrosion and Fabrication Boundaries
2304 corrosion screening
- For this 2304 vs 2205 review, The mixed austenitic-ferritic structure provides high strength and improved resistance to chloride pitting and stress-corrosion cracking relative to 304/316-type grades.
- For this 2304 vs 2205 review, PREN is only a screening index. Temperature, crevices, weld phase balance, heat tint, deposits and actual solution chemistry still govern suitability.
2205 corrosion screening
- For this 2304 vs 2205 review, Relative to 304/316-type austenitics, correctly processed 2205 often improves resistance to chloride pitting and chloride stress-corrosion cracking, but warm concentrated chlorides, crevices, deposits, heat tint and unbalanced welds can still initiate attack — do not treat duplex as immune.
- For this 2304 vs 2205 review, PREN is only a screening index derived from Cr, Mo and N chemistry. Temperature, crevices, weld phase balance, heat tint, deposits and actual solution chemistry still govern suitability versus 316L or super duplex 2507.
- For this 2304 vs 2205 review, Review design temperature, shutdown chemistry, cathodic protection interaction (where applicable), drainage and cleaning practice for the actual plate, pipe, bar or angle component before approving 2205 from a grade name alone.
| Operation | 2304 | 2205 |
|---|---|---|
| Welding | Use a qualified duplex procedure with controlled heat input, interpass temperature and filler to maintain phase balance, toughness and corrosion resistance. | Use a qualified duplex procedure with controlled heat input, interpass temperature and filler selection to maintain phase balance, toughness and corrosion resistance. Remove heat tint when the service demands it. Do not copy generic austenitic WPS numbers onto duplex joints. |
| Forming | Higher yield strength increases forming load and springback. Severe cold work may require solution annealing under a qualified route. | Higher yield strength than 304/316 increases forming load and springback on plate, bar and angle. Severe cold work may require solution annealing under a qualified route before corrosion-critical service. |
| Machining | Use rigid equipment, positive feeds and lower cutting speed than common austenitic grades because high strength and work hardening raise cutting load. | Use rigid equipment, positive feeds and lower cutting speed than common austenitic grades because high strength and work hardening raise cutting load; qualify tools on the delivered condition. |
| Heat treatment | Solution anneal and rapid cooling are used to restore the specified duplex structure. Local stress relief can form harmful intermetallic phases and is not a generic remedy. | Solution anneal and rapid cooling restore the specified duplex structure after appropriate fabrication routes. Local stress relief can form harmful intermetallic phases and is not a generic remedy for duplex 2205. |
Reference data
Composition and Mechanical Requirements
Values below come from each grade's displayed reference dataset. Product form, thickness, condition and contracted standard can change the applicable acceptance table.
Chemical composition (wt%)
| Element | 2304 | 2205 |
|---|---|---|
| C | ≤0.030 | ≤0.030 |
| Mn | ≤2.50 | ≤2.00 |
| Si | ≤1.00 | ≤1.00 |
| Cr | 21.5–24.5 | 22.0–23.0 |
| Ni | 3.0–5.5 | 4.5–6.5 |
| Mo | 0.05–0.60 | 3.0–3.5 |
| N | 0.05–0.20 | 0.14–0.20 |
| Cu | 0.05–0.60 | - |
| P | ≤0.040 | ≤0.030 |
| S | ≤0.030 | ≤0.020 |
Mechanical properties
| Property | 2304 | 2205 |
|---|---|---|
| Tensile strength | ≥600 MPa (87 ksi) | ≥655 MPa (95 ksi) |
| Yield strength (0.2%) | ≥400 MPa (58 ksi) | ≥450 MPa (65 ksi) |
| Elongation (50 mm) | ≥25% | ≥25% |
| Hardness | ≤290 HBW | - |
| PREN (screening) | - | typically ≥34 for S32205 chemistry windows |
Quotation workflow
Application Decisions
- For water tanks, provide source and treated water chemistry, disinfectants, temperature, fill cycles, deposits, crevices, cleaning and vapor-zone exposure.
- For bridges and structures, identify coastal or deicing salts, drainage, shelter, weld geometry, fatigue, fire design, finish and maintenance access.
- For process and cooling-water piping, document pressure, chlorides, pH, oxidants, flow, stagnation, deposits, shutdown and upset conditions.
- For marine systems, separate atmospheric, splash, immersed and internal-water zones and require project evidence before either duplex grade is approved.
Quote 2304 when
- Water tanks and structural components with a documented S32304 corrosion and design basis
- Low-alloy duplex projects supported by qualified 2304 welding and toughness procedures
- Equipment where measured chemistry and service history establish adequate localized-corrosion margin
- Orders with confirmed 2304 form, dimensions, matching components, tests and traceability
Quote 2205 when
- Brackish, process or cooling-water duty whose corrosion basis requires an S32205 route
- Pressure or structural designs that use 2205 code data and a qualified duplex fabrication plan
- Crevice-prone equipment supported by service evidence, welding controls and inspection
- Bills of material where approved 2205 pipe, fittings, forgings and consumables are available
Hold point
Do Not Substitute Without Review
- Do not replace 2205 with 2304, or 2304 with 2205, without authorized corrosion, design, welding and product-form review.
- Do not infer seawater, brine or a fixed service-temperature approval from PREN or duplex family name.
- Do not reduce wall or section from a strength table without the applicable product standard and complete design-code calculation.
- Do not transfer a WPS, consumable, heat treatment or phase-balance result between designations without explicit qualification.
Specification boundary
Standards, Temperature and Approval
Product and project approval
ASTM A240/A240M can govern specified duplex flat product and ASTM A789/A790 can govern specified tube or pipe, while bars, fittings, forgings and structural products require other standards. The current contract editions, form, condition, design code, project corrosion basis, welding specification and authorized reviewer control acceptance.
Temperature boundary
This page publishes no universal chloride-temperature boundary for 2304 or 2205. Temperature interacts with chlorides, disinfectants, pH, oxidants, deposits, crevices, flow and shutdown conditions; duplex phase stability and low-temperature toughness also depend on form, thickness, heat treatment and weld qualification.
Commercial comparison
Cost and Availability Factors
Quote 2304 and 2205 on one RFQ with the same product form, dimensions, tests and documents. This page does not represent current stock, price or lead time.
Cost factors
- Current alloy inputs and mill availability for the exact duplex grade, form, condition and dimensions.
- Design section, forming, machining, weld consumables and qualified duplex fabrication hours.
- Solution condition, phase or ferrite checks, impact, corrosion, hardness, PMI, NDE and witness scope.
- Matching components, quantity, mill minimum, packing, freight, Incoterm, schedule and requalification.
Inputs for a like-for-like quotation
- UNS S32304 or S32205, product form, material and dimensional standards, design code and substitution policy.
- Dimensions, pressure or load basis, corrosion allowance, quantity, condition, finish, tolerance and end preparation.
- Chlorides, pH, oxidants, temperature, flow, stagnation, deposits, crevices, cleaning, shutdown and upset chemistry.
- Weld consumable, WPS/PQR, heat input, interpass, heat treatment, phase balance, surface restoration and NDE.
- MTC, heat traceability, PMI, ferrite or phase, impact, corrosion tests, inspection, destination and Incoterm.
Continue the specification
Related Grades, Standards and Applications
Grade references
2205 Duplex Stainless Steel Plate
2205 duplex stainless steel plate to ASTM A240 for chloride, chemical and structural service, supplied solution annealed with cutting, testing and traceability options.
View details →
2205 Duplex Stainless Steel Pipe
2205 duplex ASTM A790 seamless or welded pipe for chloride process, water and offshore duty. Common inquiry range NPS 1/2–24, Sch 10S/40S/80S, with quoted tests and heat traceability.
View details →
2205 Duplex Stainless Steel Round Bar
2205 duplex (S32205) solution-annealed round bar. Common inquiry range 10–250 mm, 3 m / 6 m or cut-to-length, with quoted ferrite and corrosion checks.
View details →
Buyer questions
Frequently Asked Questions
Is 2304 as strong as 2205?
Their displayed duplex strength summaries may overlap in some contexts, but exact minimums and design allowables depend on designation, product standard, form, thickness and condition. Recalculate the component before changing grade or section.
Why does 2205 resist pitting better?
2205 has a different displayed chromium-molybdenum-nitrogen balance and a higher calculated PREN screen. PREN does not include crevice geometry, temperature, welds, oxidants, deposits or surface condition, so project corrosion review remains necessary.
Are the welding controls similar?
Both require duplex-specific control, but one WPS is not automatically qualified for both. Confirm consumable, heat input, interpass, cooling, phase balance, toughness and any corrosion testing against the exact ordered grade and form.
Published by Tsingshan (Shandong) Iron & Steel Co., Ltd..Sources, update policy and technical limitations.
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