X2CrNiMoN22-5-3
1.4462
Standard duplex (austenitic-ferritic) corrosion-resistant stainless steel · EN 10088-1 — list and chemical composition of stainless steels · EN 10088-2 — sheet, plate and strip for general purposes · EN 10088-3 — semi-finished products, bars, rods, wire, sections and bright products for general purposes
1.4462 is the widely used 22Cr-5Ni-3Mo-N standard duplex stainless steel, commonly called 2205. Its approximately balanced ferrite-austenite structure combines substantially higher proof strength than 300-series austenitic stainless steels with strong resistance to chloride pitting, crevice corrosion and stress-corrosion cracking. Its performance depends critically on product form, solution annealing, phase balance and thermal history; ordering only by the material number is insufficient for demanding pressure, welded, low-temperature, sour-service or chloride applications.
- 21.0–23.0% Cr, 4.5–6.5% Ni, 2.50–3.50% Mo, 0.10–0.22% NDefining chemistry · Cast-analysis limits from EN 10088-1:2023; C ≤0.030%.
- Minimum Rp0.2 commonly 450–500 MPa for solution-annealed productsStrength level · The exact requirement depends on product form, dimensions and governing product standard.
- Standard duplex; nominal PREN around 35Corrosion class · PREN is useful for comparing localized corrosion resistance in chloride media, not for predicting uniform corrosion or defining a universal service limit.
- Ferrite plus austeniteMicrostructure · A near-balanced structure is intended, but EN grade designation alone does not guarantee a specified ferrite range or absence of harmful secondary phases.
- Avoid uncontrolled residence in embrittling temperature rangesThermal limitation · Intermetallic precipitation is a concern roughly between 600 and 1000°C; long-term elevated-temperature use is restricted by applicable design codes.
- “2205” may refer to EN 1.4462, UNS S31803 or UNS S32205Common-name caution · These designations overlap but are not automatically identical; the required product specification and chemistry must be stated.
Overview
- Designation system
- EN steel name and European material number
- Product forms
- Hot-rolled and cold-rolled sheet, plate, coil and strip, Bar, rod, sections and semi-finished products, Seamless and welded tube and pipe under applicable tubular-product standards, Pressure-purpose plate and forgings under applicable product standards, Flanges, fittings and valve components under applicable specifications
- Condition
- Solution annealed, normally designated +AT, Hot-rolled or cold-rolled product-specific delivery conditions, Welded condition under a qualified welding procedure
- Density
- 7.8 g/cm³ (Representative room-temperature value; physical properties are typical rather than grade acceptance requirements.)
Designation and grade definition
The EN name is descriptive. “X” identifies a high-alloy steel; “2” indicates a nominal carbon content near 0.02%; “CrNiMoN22-5-3” identifies the principal alloying system and approximate chromium, nickel and molybdenum contents, with nitrogen intentionally added. The controlling identifier is material number 1.4462 together with the applicable product standard.
EN 10088-1 defines the grade list and chemistry but is not, by itself, a complete purchasing specification. Mechanical properties, dimensions, tolerances, surface condition, inspection and testing come from the product standard.
Chemical composition and corrosion-alloying concept
| Element | Requirement, % by mass | Technical significance |
|---|---|---|
| C | ≤ 0.030 | Low carbon limits carbide-related sensitization during proper processing. |
| Si | ≤ 1.00 | Deoxidation and processing element; excessive levels can affect phase stability. |
| Mn | ≤ 2.00 | Assists processing and nitrogen solubility. |
| P | ≤ 0.035 | Residual limit. |
| S | ≤ 0.015 | Residual limit; inclusions can influence toughness, machinability and localized corrosion. |
| Cr | 21.0–23.0 | Principal passivating element and ferrite former. |
| Ni | 4.5–6.5 | Promotes austenite formation and phase balance. |
| Mo | 2.50–3.50 | Improves pitting and crevice-corrosion resistance. |
| N | 0.10–0.22 | Raises strength, promotes austenite and improves localized corrosion resistance. |
| Fe | Balance | Base metal. |
Product-analysis tolerances, where applicable, are governed by the relevant product standard.
Chromium, molybdenum and nitrogen give 1.4462 appreciably greater localized-corrosion resistance than conventional 304L and generally greater resistance than 316L. The duplex structure also provides much better resistance to chloride stress-corrosion cracking than standard austenitic grades. Nevertheless, resistance remains dependent on chloride concentration, temperature, pH, oxidizing potential, crevices, deposits, surface condition, fabrication quality and residual stress. The designation must not be interpreted as unconditional suitability for seawater, concentrated acids, sour environments or any specified process stream.
Product standards and condition-dependent properties
| Standard | Scope relevant to 1.4462 | Why it matters |
|---|---|---|
| EN 10088-2 | Hot- or cold-rolled sheet, plate and strip for general purposes | Defines product-form-specific delivery conditions and mechanical properties. |
| EN 10088-3 | Semi-finished products, bars, rods, wire, sections and bright products for general purposes | Requirements vary between ordinary annealed products, bright products and dimensional ranges. |
| EN 10028-7 | Stainless flat products for pressure purposes | Use where pressure-equipment plate requirements and elevated-temperature values are required. |
| EN 10216-5 | Seamless stainless steel tubes for pressure purposes | Controls tube manufacture, heat treatment, testing and tube-specific properties. |
| EN 10217-7 | Welded stainless steel tubes for pressure purposes | Adds requirements associated with welded tube production and testing. |
| EN 10222-5 | Stainless steel forgings for pressure purposes | Relevant to pressure flanges, forged fittings and other forged components. |
| EN 10088-4 and EN 10088-5 | Corrosion-resistant stainless products for construction purposes | Use where structural construction and conformity requirements apply. |
A material certificate should identify the actual product specification and edition, not merely EN 10088 or 1.4462.
| Product and applicability | Maximum thickness or diameter | Rp0.2 min. | Rm | Elongation min. |
|---|---|---|---|---|
| EN 10088-2 cold-rolled strip/sheet, C | 8 mm | 500 MPa | 700–950 MPa | 20% |
| EN 10088-2 hot-rolled strip, H | 13.5 mm | 460 MPa | 700–950 MPa | 25% |
| EN 10088-2 hot-rolled quarto plate, P | 75 mm | 460 MPa | 640–840 MPa | 25% |
| EN 10088-3 annealed bar and similar general products | 160 mm | 450 MPa | 650–880 MPa | 25% |
These rows illustrate why a single universal property set must not be assigned to 1.4462. Confirm orientation, specimen definition, impact requirements, dimensional range and the current governing standard. Bright-bar requirements are separate and vary significantly with size.
Cold-worked products can have substantially higher strength than the solution-annealed values shown, but such strength must be specified through an applicable condition or agreed product requirement. It must not be assumed from the grade designation.
Microstructure, heat treatment and service temperature
The useful combination of strength, toughness and corrosion resistance depends on retaining suitable proportions of ferrite and austenite without damaging intermetallic phases, nitrides or carbides. Chemistry is balanced to produce an approximately equal-phase structure after correct solution annealing, but the final balance also depends on section size, forming history, annealing temperature and cooling rate.
| Operation or range | Practical significance |
|---|---|
| Solution annealing | Typically around 1020–1100°C for 2205 products, followed by sufficiently rapid cooling. The exact range and cooling method must follow the applicable product specification or qualified procedure. |
| Approximately 600–1000°C | Sigma and other intermetallic phases can form, reducing toughness and corrosion resistance. Slow cooling and prolonged holding are hazardous. |
| Approximately 350–500°C | Ferrite can undergo 475°C embrittlement during sufficient exposure. |
| Hot forming | Normally followed by solution annealing and rapid cooling unless the qualified production route demonstrably achieves the required properties and corrosion condition. |
| Low-temperature stress relief | Conventional carbon-steel stress-relief cycles can damage duplex stainless steel and should not be applied without a specifically qualified procedure. |
| Continuous elevated-temperature service | Not selected from the grade name alone. Pressure codes commonly restrict standard duplex service to roughly 250–315°C depending on code, product and welded condition. |
Temperature intervals are metallurgical guidance, not acceptance limits or permission to use the material at the stated temperatures.
Unlike fully austenitic stainless steels, duplex grades exhibit a ductile-to-brittle transition at low temperature. General-purpose room-temperature properties therefore do not establish cryogenic suitability. Low-temperature service requires specified impact testing at the design temperature, control of product thickness and orientation, and qualification of weld metal and heat-affected zones.
Fabrication and welding
| Activity | What changes relative to common austenitic stainless steels |
|---|---|
| Cutting and forming | Higher proof strength requires greater machine capacity. Larger springback must be allowed for, and sharp bend radii should be avoided. |
| Cold forming | Feasible, but severe deformation can alter mechanical properties and residual stress. Any need for re-solution annealing depends on deformation, service and product requirements. |
| Machining | Higher strength, work hardening and duplex chip behavior demand rigid setups, sharp positive-geometry tools, controlled feeds and effective cooling. |
| Hot forming | Control the temperature window and avoid slow cooling through precipitation ranges; solution annealing is normally required afterward. |
| Surface handling | Prevent contamination by carbon-steel tooling, grinding debris or iron particles. Remove scale, heat tint and embedded contamination where corrosion performance matters. |
| Magnetism | The ferritic phase makes 1.4462 appreciably magnetic; magnetic response is normal and is not evidence that the material is the wrong grade. |
1.4462 is readily weldable by common arc processes, but duplex welding is controlled primarily to preserve phase balance, toughness and corrosion resistance. Excessively rapid cooling can leave a ferrite-rich heat-affected zone with chromium nitrides; excessive heat input or slow cooling can promote intermetallic precipitation. Welding variables therefore require a qualified WPS rather than direct adoption of procedures developed for 316L.
| Control | Usual practice |
|---|---|
| Filler metal | Over-alloyed 22 9 3 N / ER2209 or E2209 consumables are commonly used to promote adequate weld-metal austenite. |
| Autogenous welding | May produce excessive ferrite or reduced corrosion performance, particularly in thicker or highly restrained joints; qualification is essential. |
| Preheat | Normally avoided. Limited preheat may be used only where justified by the procedure. |
| Interpass temperature | Common guidance limits standard duplex to about 150°C, subject to the qualified procedure and project specification. |
| Heat input | Use a qualified range appropriate to thickness and process; neither indiscriminately low nor high heat input is acceptable. |
| Root shielding | Maintain clean, effective purging and prevent excessive root oxidation. |
| Post-weld heat treatment | Not normally required. If performed, it should be full solution annealing followed by rapid cooling; low-temperature stress relief is unsuitable. |
| Post-weld cleaning | Remove slag, heat tint and contamination by suitable mechanical and/or chemical treatment, followed by thorough cleaning. |
Numerical welding limits are procedure guidance rather than universal grade requirements. Codes, thickness, joint design, process and required impact or corrosion performance may impose narrower ranges.
Inspection and purchasing controls
A technically complete order should begin with the product standard, product form, dimensions and delivery condition, followed by 1.4462 / X2CrNiMoN22-5-3. It should then identify inspection certification, mechanical and impact testing, surface finish, dimensional tolerances, NDT, corrosion testing and any supplementary metallurgical controls required by the service.
| Item | Reason |
|---|---|
| Product specification and edition | Determines properties, heat treatment, permissible dimensions, tolerances and testing. |
| Solution-annealed condition | Confirms that the required duplex microstructure and corrosion condition were restored after manufacture. |
| Inspection document | EN 10204 type 3.1 is common, but the required certificate level is contractual. |
| Actual heat analysis | Needed to verify EN chemistry, any UNS dual certification and any agreed PREN requirement. |
| Mechanical test applicability | Check thickness or diameter range, specimen orientation and whether the stated values apply to the supplied product form. |
| Impact test temperature and orientation | Essential for low-temperature or code-controlled service; room-temperature grade data are insufficient. |
| Ferrite or phase-balance requirement | Specify only when required by the application, fabrication specification or project standard, including method and acceptance range. |
| Intermetallic-phase testing | ASTM A923 or another agreed method may be required for critical duplex products and weld procedure qualification. |
| Pitting-corrosion test | ASTM G48 or a project-specific test may be required; define method, temperature, preparation and acceptance criterion. |
| PMI and traceability | Useful where material mix-up risk is significant, but PMI does not establish heat treatment, nitrogen accurately, phase balance or mechanical compliance. |
| Sour-service qualification | ISO 15156/NACE MR0175 compliance depends on product, condition, hardness, environment and fabrication; the grade designation alone is not approval. |
A certificate stating only “1.4462 / 2205” should not be assumed to satisfy UNS S32205, ASTM A240, ASTM A182 F60, a pressure-equipment specification or a project-specific duplex material data sheet. Each claimed certification must be checked against its own chemistry, heat-treatment, mechanical and testing requirements.
Selection boundaries
1.4462 is commonly selected for process vessels, heat exchangers, piping, tanks, pulp and paper equipment, water-treatment systems, chemical tankers, structural components, shafts, pumps, valves and pressure components where both chloride resistance and high strength are valuable. Higher strength can permit reduced section thickness, but redesign must consider buckling, fatigue, stiffness, weld details, corrosion allowance, code rules and fabrication tolerances rather than simply replacing an austenitic grade at equal geometry.
The grade should not be selected solely from a PREN comparison. More highly alloyed superduplex or superaustenitic materials may be required for warm seawater, severe crevices, highly oxidizing chlorides or other aggressive conditions. Conversely, lean duplex grades may be adequate where strength rather than high localized-corrosion resistance is the main driver. Uniform-corrosion data for the actual chemical environment and temperature remain necessary.
Sources
- DIN EN 10088-1:2024-04 — Stainless steels, Part 1: List of stainless steels; German version EN 10088-1:2023DIN Media
- SIST EN 10088-1:2024 — EN 10088-1:2023 previewSlovenian Institute for Standardization / iTeh
- BS EN 10088-2:2024 — Technical delivery conditions for sheet, plate and stripBSI
- BS EN 10088-3:2023 — Technical delivery conditions for semi-finished products, bars, rods, wire, sections and bright productsBSI
- Duplex Stainless Steelsworldstainless / International Stainless Steel Forum
- Practical Guidelines for the Fabrication of Duplex Stainless SteelsNickel Institute and International Molybdenum Association
- Forta Duplex Stainless Steels Range DatasheetOutokumpu
- SAF 2205 — Seamless tube and pipeAlleima
- ASTM A240/A240M — Stainless steel plate, sheet and strip for pressure vessels and general applicationsASTM International
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