EN 10088-2 X1CrNiMoCuN20-18-7 1.4547 Stainless Steel Plate

EN 10088-2 X1CrNiMoCuN20-18-7 1.4547 stainless steel plate is a high-alloy austenitic flat product supplied to EN 10088-2, the European standard for stainless steel sheet, plate and strip for general purposes. X1CrNiMoCuN20-18-7 contains up to 0.020 % carbon, 19.5 – 20.5 % chromium, 17.5 – 18.5 % nickel, 6.0 – 7.0 % molybdenum, 0.18 – 0.25 % nitrogen and 0.50 – 1.00 % copper. It is one of the 6 % molybdenum, or super-austenitic, grades, with less nickel than 1.4529. EN 10088-2 places 1.4547 among its special grades, defined as grades for special use and/or with limited availability. It is listed as cold rolled strip up to 8 mm, continuously hot rolled strip up to 13.5 mm and hot rolled plate up to 75 mm, solution annealed. Table 7 rates it resistant to intergranular corrosion both as delivered and after sensitization.

SHH STEEL works as a steel sourcing partner with long-term relationships with Chinese stainless mills that roll high-alloy austenitic hot rolled plate, coil and cold rolled sheet. For large tonnages, the buyer can contract directly with a suitable mill, with SHH STEEL assisting for a modest service fee and handling follow-up and documents. For small orders we consolidate demand, so that 1 – 5 t lots are placed against genuine mill production instead of stock of unknown origin. Each shipment can be released after third-party inspection by TUV, ABS, BV, DNV, CCS or an agency the buyer nominates, and payment by TT or LC is accepted. The rest of this page covers the technical side of EN 10088-2 1.4547 and the steps we take so that the sheet that arrives is the sheet that was ordered.

The table below lists the concerns buyers raise most often when sourcing EN 10088-2 X1CrNiMoCuN20-18-7 sheet and plate from China, and how SHH STEEL deals with each of them.

1.4547 corresponds to UNS S31254 in ASTM A240 (see AISI 254 SMO (UNS S31254) stainless steel plate); A240 gives this UNS number no type name. The composition is widely sold as 254 SMO, which is a trademark owned by Outokumpu. SHH STEEL orders and certifies by EN steel number and UNS number; a specific producer’s branded product has to be named and agreed in the order. For pressure equipment the grade is ordered to EN 10028-7; see EN 10028-7 1.4547 pressure vessel plate.

Chromium, nickel, nitrogen and copper ranges are the same in EN and ASTM. The difference is molybdenum: ASTM A240-22 caps it at 6.5 %, EN 10088-2 at 7.0 %, so a dual-certified heat needs molybdenum of 6.0 – 6.5 %. SHH STEEL checks this when a buyer needs dual certification.

1.4547 is also listed in EN 10028-7:2016 for pressure purposes. That standard may set its own test and property requirements, which we have not reproduced here.

Edition note: the values on this page are taken from EN 10088-2:2014. A revised edition (EN 10088-2:2024) has since been published. If your contract names the newer edition, SHH STEEL checks the order against that text before production, and any difference is raised at the quotation stage rather than after rolling.

The 1.4547 chemical composition below is the cast (heat) analysis from EN 10088-2:2014 Table 1. Values are percentages by mass; a single figure is a maximum.

The 1.4547 molybdenum of 6.0 – 7.0 % and nitrogen of 0.18 – 0.25 % define the grade, and the chromium and nickel ranges are only 1 % wide. Phosphorus (0.030 %) and sulphur (0.010 %) limits are tighter than for the 300-series grades. SHH STEEL checks molybdenum, nitrogen, chromium and nickel on every certificate as part of the 1.4547 chemical composition review.

Product analysis tolerances (EN 10088-2 Table 5)

A product analysis is a check made on the delivered sheet. It is not mandatory under EN 10088-2; it is carried out when agreed at the time of enquiry and order, and SHH STEEL can arrange it through a partner laboratory. The permissible tolerances on the cast limits are:

Where several product analyses are made on one cast, individual results may exceed the maximum or fall below the minimum, but not both for the same element. Chromium uses ± 0.20 % at the 19.5 % minimum and ± 0.25 % at the 20.5 % maximum, because Table 5 changes band at 20.0 %. If a product analysis is required, it should be stated in the order together with the Table 5 tolerances.

The 1.4547 mechanical properties below are the room-temperature values from EN 10088-2:2014 Table 7 for austenitic steels in the solution annealed condition. Test pieces are transverse; the A80 elongation applies below 3 mm and the proportional elongation A from 3 mm.

Rp1.0 values are for guidance only. For continuously hot rolled products, 20 MPa higher minimum Rp0.2 and 10 MPa higher Rp1.0 may be agreed. For strip in rolling widths below 300 mm tested longitudinally, the minimum proof strength is reduced by 15 MPa and elongation by 5 % (constant gauge) or 2 % (proportional gauge). For bigger sizes than those listed, mechanical values are to be agreed.

Table 7 rates 1.4547 resistance to intergranular corrosion (EN ISO 3651-2) as “yes” in both the delivery condition and the sensitized condition.

Cold worked condition (process route 2H)

EN 10088-2 Tables 19 and 20 list no cold worked (2H) strength levels for 1.4547, so the grade is ordered in the solution annealed condition (+AT). Its nitrogen content already gives an annealed proof strength of 300 MPa for plate.

Minimum proof strength at elevated temperature (EN 10088-2 Table 12, +AT)

EN 10088-2 Table 12 gives values for 1.4547 from 100 °C to 500 °C, for the solution annealed condition (+AT). Alleima’s datasheet for its 254 SMO seamless tube and pipe notes that intermetallic phases precipitate between 600 and 1 000 °C, so the steel should not be held in that range for long periods.

EN 10088-2 Table A.1 gives the following guideline temperatures for 1.4547:

The footnotes to Table A.1 state that with a continuous furnace the upper part of the range is usually preferred or even exceeded, and that the lower end of the range should be aimed at when the heat treatment is part of further processing, because otherwise the mechanical properties may be affected. Solution annealing may be omitted if hot working and cooling achieve the required mechanical properties and resistance to intergranular corrosion.

1.4547 has its own hot forming range in Table A.1, 1 200 – 1 000 °C, instead of the 1 150 – 850 °C used for most austenitic grades, and the solution annealing range of 1 150 – 1 200 °C is among the highest in the table. Alleima’s datasheet for its 254 SMO seamless tube and pipe gives the same 1 150 – 1 200 °C range with water quenching. Material is delivered as +AT.

The values below are approximate reference figures for X1CrNiMoCuN20-18-7 at room temperature, from the worldstainless “Tables of Technical Properties”, which follow EN 10088-1. They are suitable for design estimates and weight calculation; where a figure is critical, use EN 10088-1 itself.

The worldstainless table gives 1.4547 a density of 8.0 g/cm³, a modulus of 195 GPa, a thermal conductivity of 14 W/(m·K) and an electrical resistivity of 0.85 Ω·mm²/m. 1.4547 is not listed in the EN 10088-1 extract by Häuselmann that we use for magnetic behaviour, so the magnetic statement above is the general austenitic one. Alleima’s datasheet for its 254 SMO seamless tube and pipe gives similar figures, including a modulus of 195 GPa at 20 °C.

The Euro Inox fabrication tables we use do not list 1.4547, so the service information here comes from producers. Outokumpu describes the composition as having extremely high resistance to both uniform and localised corrosion, developed for offshore platforms and the pulp and paper industry. Alleima’s datasheet for its 254 SMO seamless tube and pipe reports a PRE of at least 42.5 (PRE = %Cr + 3.3 × %Mo + 16 × %N) and high resistance to stress corrosion cracking. EN 10088-2 Table 7 rates its resistance to intergranular corrosion, tested to EN ISO 3651-2, as “yes” in the delivery condition and “yes” in the sensitized condition.

The other 6 % molybdenum grade in EN 10088-2 is EN 10088-2 1.4529 plate, with 24 – 26 % nickel; the lower-molybdenum high-nickel grade is EN 10088-2 1.4539 plate.

As EN 10088-2 notes, corrosion resistance depends strongly on the environment and cannot always be judged from laboratory tests, so experience with the grade in similar service should be used.

1.4547 is weldable, but as a fully austenitic 6 % molybdenum grade it needs controlled heat input and over-alloyed filler metal.

• Alleima’s datasheet for its 254 SMO seamless tube and pipe rates weldability as good, names TIG as the first choice, and also lists manual metal arc welding.
• It recommends heat input below 1.5 kJ/mm, interpass temperature below 100 °C and a string bead technique.
• It states that nickel alloys with high molybdenum and chromium must be used as filler metals, for example ISO 18274 S Ni 6625 or S Ni 6059 wire and the matching ISO 14172 electrodes.
• EN 10088-2 does not specify welding procedures, and the Euro Inox tables do not cover 1.4547; these are producer guidelines.

These points reflect industry practice for high-alloy austenitic stainless steels rather than requirements of EN 10088-2, which does not specify welding procedures. In the SHH STEEL workshop, blanks and slit strips are cut with clean, burr-free edges so that seam, spot and tube welding run without edge preparation problems.

Alleima’s datasheet for its 254 SMO seamless tube and pipe describes formability as excellent, permitting cold bending to tight radii without annealing. Its higher proof strength than the 316L grades means more forming force and springback, and it advises avoiding abrasion against copper or copper alloys, which can cause cracking during later welding or heat treatment.

Plate is cut by plasma or waterjet, and sheet by laser or shearing. The same datasheet recommends tougher inserts and considerably lower cutting speeds than for 304L and 316L when machining.

We run our own workshop next to the warehouse, so 1.4547 hot rolled plate and X1CrNiMoCuN20-18-7 plate blanks can be delivered cut to size, laser-cut or bent, with protective film on visible surfaces. Details are on our steel cutting services and bending and forming services pages.

1.4547 is listed in EN 10088-2 as cold rolled strip, continuously hot rolled strip and hot rolled plate, all solution annealed; as a special grade, not every size is rolled by every mill.

EN 10088-2 Table 7 gives mechanical values for hot rolled plate up to 75 mm; for bigger sizes the mechanical values shall be agreed at the time of enquiry and order. Under section 6.9 of the standard, EN ISO 18286 normally applies only to individually rolled quarto plate, while continuously rolled material follows EN ISO 9444-2.

SHH STEEL can supply 1.4547 super-austenitic hot rolled plate and 1.4547 cold rolled sheet, in standard sizes or cut to your drawing, after confirming availability with the mill.

Surface finish is ordered by the process route symbols of EN 10088-2 Table 6; trade names from ASTM and JIS are shown for reference. Not every route is available for every grade, and the mill confirms which ones it can supply.

The No.1, No.4 and BA cross-references follow worldstainless and IMOA comparison tables; EN 10088-2 itself defines only the EN symbols, and not every route is available for every grade. Special finishes such as 1J and 2J apply to one surface unless otherwise agreed. No polishability rating is available from the Euro Inox tables for 1.4547.

The usual 1.4547 equivalent, and the answer to most S31254 equivalent enquiries, is UNS S31254 in ASTM A240.

For Chinese pressure vessels the grade is ordered as GB/T 713.7 S31252 pressure vessel plate. A heat at the top of the 1.4547 molybdenum range (above 6.5 %) would not meet ASTM S31254.

1.4547 vs 1.4529 and 1.4539

Compared with 1.4529, 1.4547 has less nickel (17.5 – 18.5 % against 24.0 – 26.0 %) and slightly more nitrogen, with the same 6.0 – 7.0 % molybdenum and 300 MPa plate proof strength; it is listed in strip and sheet as well as plate. Compared with EN 10088-2 1.4539 plate, it has more molybdenum, a nitrogen addition and a higher proof strength (300 against 220 MPa).

Typical applications of 1.4547 plate and sheet named by producers (Outokumpu and Alleima) include:

• Equipment for chlorinated seawater
• Seawater cooling and ballast water systems
• Flue gas cleaning
• Bleaching equipment in the pulp and paper industry
• Heat exchangers, flanges and valves
• Tanks for chemicals with high halide contents

For pressure equipment, 1.4547 plate is ordered to EN 10028-7; for other uses, EN 10088-2 applies.

Buyers choose 1.4547 when 1.4539 or the 317-type grades are not resistant enough to chlorides. SHH STEEL can advise when 1.4529 or a nickel alloy should be compared. For still more nickel and chromium, EN 10088-2 1.4563 plate (26.0 – 28.0 % chromium, 30.0 – 32.0 % nickel, 3.0 – 4.0 % molybdenum) is the related EN 10088-2 grade.

For 1.4547 the main risks are molybdenum or nitrogen below the EN minimums, molybdenum above 6.5 % on ASTM dual-certified orders, and the wrong filler metal.

None of these steps is complicated, but they need to be agreed at the start. When you send an enquiry, tell us which of these points matters most to you, and the order will be built around it.

Every 1.4547 order is supported by documents and checks that make the material traceable to the heat:

• Cast analysis with molybdenum, nitrogen, chromium, nickel and copper checked
• Tensile test (transverse) to Table 7
• Impact test for plate over 10 mm when agreed
• Intergranular corrosion test to EN ISO 3651-2 when agreed
• Thickness, flatness and surface inspection
• Additional checks through our third-party testing service: PMI, dimensional, flatness and surface inspection

If the order does not name an inspection document, EN 10088-2 requires only a test report 2.2. Because this is rarely enough for seawater, flue gas and bleach plant equipment or export work, SHH STEEL supplies an EN 10204 3.1 inspection certificate as standard and a 3.2 certificate when an independent inspector (TUV, ABS, BV, DNV, CCS or an agency you nominate) witnesses testing and countersigns the document.

Ordering example and lead time

Following the pattern of the example in EN 10088-2, a typical order line would read: 4 plates, 8 mm × 1 500 mm × 6 000 mm, EN ISO 18286, EN 10088-2, steel X1CrNiMoCuN20-18-7 (1.4547), process route 1D, inspection certificate 3.1 to EN 10204. Mill production lead time is generally 30 – 40 days from order confirmation, depending on the rolling schedule, the size and the tests requested; because 1.4547 is a special grade, the campaign date should be confirmed at enquiry. Consolidated small lots follow the same mill schedule, and we send progress updates at rolling, testing and packing.

• Mill relationships: long-term cooperation with Chinese stainless mills helps us secure competitive pricing and steadier delivery for 1.4547 and related high-alloy austenitic grades.
• Direct mill contracts: for larger tonnages you can contract directly with a suitable mill, for a modest service fee, while we handle follow-up and documents.
• Order consolidation: 1 – 5 t lots are combined so they can be placed against genuine mill production.
• Own workshop: slitting, cut-to-length, laser cutting, bending and protective film before shipment.
• Inspection and certificates: third-party inspection by TUV, ABS, BV, DNV, CCS or your nominated agency, with EN 10204 3.1 or 3.2 certificates.
• Flexible payment: TT, LC or a combination of both.
• Port logistics: coil and sheet are packed seaworthy with heat-number labels and shipped through our worldwide shipping service, together with other grades if needed.

As a 1.4547 plate supplier SHH STEEL also stocks and sources the wider range of stainless steel sheets and plates, so mixed orders of different stainless grades can travel in one container with one set of paperwork.

EN 10088-2 X1CrNiMoCuN20-18-7 1.4547 is the 6 % molybdenum, nitrogen-alloyed super-austenitic special grade, supplied as hot rolled plate up to 75 mm and cold rolled sheet for seawater, flue gas and bleach plant equipment. Choosing it is the easy part. Getting genuine material that matches the certificate, in the gauge and finish your parts need and on a predictable schedule, is where a sourcing partner earns its place, and that is the work SHH STEEL does every day through long-term mill cooperation, consolidation and its own workshop.

The next step is simple. Send SHH STEEL your drawing, or an enquiry with the quantity, thickness, width, finish and delivery destination, and we will judge whether a direct mill contract or consolidation with processing fits your order better, and quote accordingly. Send your sizes and quantities for a quotation.