X6CrNiMoTi17-12-2
1.4571
Titanium-stabilized molybdenum-alloyed austenitic stainless steel · EN 10088-1:2023 — list and chemical composition of stainless steels · EN 10088-2:2024 — sheet, plate and strip for general purposes · EN 10088-3:2023 — semi-finished products, bars, rods, wire, sections and bright products for general purposes · EN 10028-7:2016 — stainless flat products for pressure purposes, when applicable
1.4571 is the titanium-stabilized member of the 316 stainless family. Its chromium, nickel and molybdenum provide broadly 316-class corrosion resistance, while titanium binds carbon and improves resistance to sensitization and intergranular corrosion after welding or elevated-temperature exposure. The designation alone does not define a universal property set: mechanical properties, permissible sulfur content, heat treatment, dimensions and testing depend on the applicable EN product standard and delivery condition.
- Mo-alloyed 316-type austenitic stainless stabilized with titaniumGrade concept · Titanium is specified at 5 × C minimum, up to 0.70%.
- Resistance to intergranular corrosion after thermal exposurePrimary selection reason · Particularly relevant where a stabilized grade is required instead of a low-carbon 316L grade.
- Rp0.2 ≥ 220–240 MPa; Rm 520–690 MPaFlat-product strength · EN 10088-2:2024, solution-annealed products; the exact requirement depends on product form and thickness.
- Rp0.2 ≥ 200 MPa; Rm 500–700 MPaLong-product strength · EN 10088-3:2023, hot-worked solution-annealed products up to 160 mm; other dimensional and processing ranges differ.
- Approximately 1020–1120 °CSolution annealing · EN 10088-3 range; EN 10088-2 gives 1030–1110 °C for flat products. Cooling must be sufficiently rapid.
- Not a universal substitute for 316LImportant limitation · Corrosion environment, elevated-temperature requirements, surface finish, product standard and welding consumables can determine the correct choice.
Overview
- Designation system
- EN steel name and European material number
- Product forms
- Hot- and cold-rolled sheet and strip, Plate, Bars and rods, Wire, Sections and bright products, Semi-finished products, Forgings and tubes when ordered to their separate applicable product standards
- Condition
- Solution annealed, normally designated +AT, Hot-worked or cold-processed surface conditions defined by the product standard, Cold-work-hardened conditions where specifically ordered and supported by the applicable product standard
- Density
- 8 kg/dm³ (Representative value at 20 °C; equivalent to approximately 8000 kg/m³.)
Grade definition and standards context
The EN name identifies a high-alloy steel: “X” denotes a high-alloy grade, “6” indicates a nominal carbon level of about 0.06%, and “CrNiMoTi17-12-2” identifies the principal alloying system and approximate chromium, nickel and molybdenum contents, with titanium stabilization. The binding identity is the combination of X6CrNiMoTi17-12-2 and material number 1.4571, interpreted through the applicable product standard.
| Standard | Practical role for 1.4571 |
|---|---|
| EN 10088-1 | Lists the grade, designation and reference chemical composition. It is not a complete purchasing specification. |
| EN 10088-2 | Controls general-purpose hot- and cold-rolled sheet, plate and strip, including delivery condition, surface, mechanical properties and inspection. |
| EN 10088-3 | Controls general-purpose semi-finished products, bars, rods, wire, sections and bright products. Requirements vary with processing route, size and condition. |
| EN 10088-4 and EN 10088-5 | Apply to corrosion-resistant flat and long products specifically intended for construction purposes. |
| EN 10028-7 | Use for pressure-purpose stainless plate and strip. Its mechanical and elevated-temperature data must not be replaced by general-purpose EN 10088 values. |
| Other product standards | Tubes, forgings, pressure bars, fasteners and welding products require their own standards even when the underlying grade is 1.4571. |
An order stating only “1.4571 to EN 10088” is incomplete because EN 10088 is a multipart series.
Composition and titanium stabilization
| Element | Requirement, mass % | Metallurgical significance |
|---|---|---|
| C | ≤ 0.08 | Carbon is controlled by titanium stabilization rather than restricted to the 0.03% maximum used for 316L. |
| Si | ≤ 1.00 | Deoxidizer and residual alloying element. |
| Mn | ≤ 2.00 | Assists steelmaking and austenite stability. |
| P | ≤ 0.045 | Controlled residual element. |
| S | ≤ 0.015 on the EN 10088-1/flat-product basis | Long-product standards can permit different sulfur limits or agreed ranges; verify the applicable product specification. |
| Cr | 16.5–18.5 | Creates and maintains the passive chromium-rich surface film. |
| Ni | 10.5–13.5 | Stabilizes the austenitic structure and supports ductility and corrosion resistance. |
| Mo | 2.00–2.50 | Improves resistance to pitting and crevice corrosion compared with non-molybdenum 304-type grades. |
| Ti | 5 × C to 0.70 | Preferentially forms titanium carbides/carbonitrides, reducing chromium-carbide sensitization. |
Values are cast-analysis limits. Product-analysis tolerances and special sulfur provisions are governed by the applicable product standard.
During prolonged exposure within the sensitization range, unstabilized carbon can combine with chromium at grain boundaries, locally depleting chromium and creating susceptibility to intergranular corrosion. Titanium has a stronger affinity for carbon and preferentially forms stable titanium compounds, preserving chromium in the matrix. Stabilization does not increase the bulk molybdenum-based pitting resistance, and it does not make the grade immune to every form of heat-affected-zone attack.
Delivery condition and mechanical requirements
The normal reference condition is solution annealed, designated +AT. Values must be tied to product form, thickness or diameter, processing route and specimen orientation. Cold-worked strip, wire and bars can have much higher strength and lower ductility and must be ordered by their applicable strength or processing condition rather than assumed to have the solution-annealed properties below.
| Product code and form | Maximum thickness | Rp0.2 min. | Rp1.0 min. | Rm | Elongation min. |
|---|---|---|---|---|---|
| C — cold-rolled strip/sheet | 8 mm | 240 MPa | 270 MPa | 540–690 MPa | 40% |
| H — hot-rolled strip/sheet | 13.5 mm | 220 MPa | 260 MPa | 540–690 MPa | 40% |
| P — hot-rolled plate | 75 mm | 220 MPa | 260 MPa | 520–670 MPa | 40% |
These values are product-form-specific requirements, not universal properties of every 1.4571 product.
| Size range | Hardness max. | Rp0.2 min. | Rp1.0 min. | Rm | Longitudinal elongation min. |
|---|---|---|---|---|---|
| Thickness or diameter ≤ 160 mm | 215 HB | 200 MPa | 235 MPa | 500–700 MPa | 40% |
Requirements change for larger dimensions, transverse specimens, cold-processed products, wire and intentionally cold-work-hardened bars.
Austenitic stainless steels do not exhibit the pronounced ductile-to-brittle transition typical of ferritic steels when solution annealed. Cryogenic suitability nevertheless requires confirmation against the applicable design code, product standard and required toughness testing.
Corrosion behavior and grade selection
In many aqueous environments, 1.4571 provides general corrosion resistance broadly comparable with other 316-family grades. Molybdenum gives a substantial improvement over 304-type stainless steels in moderately chloride-bearing and reducing environments. Actual performance remains controlled by chloride concentration, temperature, acidity, oxidizing potential, deposits, crevices, surface condition and fabrication quality; the grade designation does not establish a universal concentration or temperature limit.
| Mechanism | Practical assessment |
|---|---|
| Intergranular corrosion | Titanium stabilization is the defining advantage. EN product standards identify the grade as resistant in both the delivery and sensitized conditions when the specified criteria are met. |
| Pitting and crevice corrosion | Mo improves resistance over 304, but 1.4571 is not generally adequate for unrestricted seawater or severe hot-chloride crevice service. |
| Chloride stress-corrosion cracking | Like conventional austenitic stainless steels, it can crack under sustained tensile stress in sufficiently aggressive chloride environments, especially as temperature rises. |
| Knife-line attack | A narrow region immediately adjacent to a weld can become susceptible if titanium compounds dissolve during welding and subsequent thermal exposure permits sensitization. This is distinct from ordinary weld decay. |
| General acid corrosion | Performance is medium-specific. The material should be selected from validated corrosion data rather than from the informal label “acid-resistant stainless.” |
Clean fabrication, removal of heat tint and restoration of a contamination-free passive surface are often as important as the nominal grade.
Temperature capability and physical behavior
The stabilized composition retains proof strength better than 316L during elevated-temperature exposure and is commonly selected where post-weld sensitization resistance or elevated-temperature strength matters. This does not create a single allowable service temperature. Pressure equipment must use the temperature-dependent values and allowable stresses from EN 10028-7 and the applicable design code; general-purpose EN 10088 data are not design allowables. Oxidation, creep, cyclic loading, corrosion and weld-metal properties can each impose a different limit.
| Property | Representative value |
|---|---|
| Density | 8.0 kg/dm³ |
| Modulus of elasticity | 200 GPa |
| Thermal conductivity | 15 W/(m·K) |
| Specific heat | 500 J/(kg·K) |
| Electrical resistivity | 0.75 Ω·mm²/m |
| Mean thermal expansion, 20–200 °C | 17.5 × 10⁻⁶ K⁻¹ |
| Mean thermal expansion, 20–400 °C | 18.5 × 10⁻⁶ K⁻¹ |
Representative engineering data, not EN acceptance requirements. Thermal expansion is substantially higher and thermal conductivity lower than for carbon steel.
Heat treatment and fabrication
| Operation | Technical guidance |
|---|---|
| Solution annealing | EN 10088-2 specifies 1030–1110 °C for flat products; EN 10088-3 specifies 1020–1120 °C for long products. Follow with sufficiently rapid cooling to avoid detrimental precipitation. |
| Hardening | The grade cannot be hardened by conventional quench-and-temper heat treatment. Strength increases through cold work. |
| Cold forming | Generally good because of its austenitic ductility, but work hardening and springback require suitable forming allowances and equipment capacity. |
| Machining | Less free-cutting than sulfur-alloyed stainless grades. Rigid setups, sharp positive tooling, adequate feed and effective cooling help avoid work-hardened surfaces and built-up edge. |
| Mechanical polishing | Titanium carbide/carbonitride particles can produce streaking or particle pull-out. The grade can be less satisfactory than 316L where an exceptionally uniform decorative or hygienic mechanical polish is critical. |
| Magnetic response | Normally essentially non-magnetic when solution annealed. Cold work and weld-metal ferrite can produce a measurable magnetic response. |
1.4571 is readily weldable using established austenitic-stainless procedures. For welds requiring stabilized elevated-temperature properties, niobium-stabilized 19 12 3 Nb consumables are normally selected because titanium is difficult to transfer reliably through the welding arc. For primarily aqueous-corrosion service, a 316L-type filler can provide suitable weld-metal corrosion resistance when permitted by the welding procedure and project specification. Heat input, interpass temperature, shielding, joint cleanliness and complete removal of heat tint remain important. Consumable selection and post-weld treatment must follow the qualified welding procedure and applicable construction code.
Specifying and purchasing 1.4571
| Item | What to define |
|---|---|
| Product standard | State the exact part and edition, such as EN 10088-2:2024 or EN 10088-3:2023. Use a pressure, tube, forging or construction standard where applicable. |
| Grade | State both X6CrNiMoTi17-12-2 and 1.4571 to reduce designation ambiguity. |
| Product and dimensions | Define sheet, plate, strip, bar, wire or section together with dimensions, tolerances and edge condition. |
| Delivery condition | Specify +AT or the required hot-worked, cold-processed or cold-work-hardened condition. |
| Surface condition | Specify the EN process route or finish and any roughness, polishing, pickling or passivation requirement. |
| Mechanical requirements | Confirm the applicable thickness or diameter range, test direction and any elevated-temperature or impact requirements. |
| Corrosion testing | Specify intergranular-corrosion testing to the applicable EN ISO 3651-2 method if required by service or project rules. |
| Inspection document | State the required EN 10204 document, commonly type 3.1 when traceable inspection results are needed. |
| Special controls | Identify PMI, ferrite, sulfur, inclusion cleanliness, weldability, pressure-equipment, hygienic-surface or project-specific requirements explicitly. |
Do not accept a certificate showing only “316Ti” without confirming the governing specification. EN 1.4571 and UNS S31635 are closely corresponding designations, but their chemistry rules, product requirements, tests and certification systems are not identical.
Sources
- EN 10088-1:2023 — Stainless steels, Part 1: List of stainless steelsEuropean Committee for Standardization / SIST preview
- BS EN 10088-2:2024 — Technical delivery conditions for sheet, plate and stripBSI
- EN 10088-3:2023 — Technical delivery conditions for semi-finished products, bars, rods, wire, sections and bright productsEuropean Committee for Standardization / SIST preview
- Ambient temperature mechanical properties of austenitic stainless steel flat products to BS EN 10088-2British Stainless Steel Association
- Ambient temperature mechanical properties of austenitic stainless steel long products to BS EN 10088-3British Stainless Steel Association
- Comparison of grades 316 and 316L to 316TiBritish Stainless Steel Association
- Selection of welding consumables for welding stainless steelsBritish Stainless Steel Association
- Stainless Steel: Tables of Technical PropertiesEuro Inox / worldstainless
- Stainless steel grades listed in ISO 15510worldstainless
- Elevated-temperature mechanical properties for stainless steels specified in BS EN 10028-7British Stainless Steel Association
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