EN 10088-2 X2CrMoTi29-4 1.4592 Stainless Steel Plate

EN 10088-2 X2CrMoTi29-4 1.4592 stainless steel plate is a ferritic flat product supplied to EN 10088-2, the European standard for stainless steel sheet, plate and strip for general purposes. X2CrMoTi29-4 is the most highly alloyed ferritic in the standard, a so-called super-ferritic: 28.0 – 30.0 % chromium, 3.5 – 4.5 % molybdenum, carbon no more than 0.025 % and nitrogen no more than 0.045 %, stabilised with titanium. This combination gives pitting and crevice corrosion resistance in seawater and brines that is far beyond standard ferritic and austenitic grades, without nickel. It also gives the highest strength of the ferritics in the standard. EN 10088-2 covers the grade as cold rolled strip and sheet up to 8 mm, and in practice it is used mainly as thin strip for welded tubes.

SHH STEEL works as a steel sourcing partner with long-term relationships with Chinese stainless mills that roll super-ferritic strip for welded condenser and heat-exchanger tubing. 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 1.4592 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 X2CrMoTi29-4 sheet and plate from China, and how SHH STEEL deals with each of them.

1.4592 is an EN 10088-2 grade; it does not appear in the ferritic table of EN 10028-7:2016. In American specifications the close counterpart is UNS S44735, often called 29-4C, in ASTM A240 and in the tube standards for condenser and heat-exchanger tubing. In China, GB/T 4237 022Cr29Mo4NbTi S12963 plate is the related grade in GB/T 4237 and GB/T 3280.

Because the molybdenum and stabilisation rules differ slightly, many heats can meet both EN and ASTM limits, but not all. SHH STEEL checks the analysis against each standard named on the drawing before quoting.

Super-ferritics need very low carbon and nitrogen and clean melting, typically through vacuum or argon-oxygen refining, and only a small number of mills produce them. This is a rare grade, and SHH STEEL confirms mill capability, available gauges and test data with the mill before quoting.

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 1.4592 chemical composition below is the cast (heat) analysis from EN 10088-2:2014 Table 3. Values are percentages by mass; a single figure is a maximum.

The phosphorus and sulphur limits, 0.030 % and 0.010 %, are tighter than for most ferritics, reflecting the clean steelmaking the grade needs. With 0.015 % carbon and 0.020 % nitrogen, the titanium minimum would be 4 × 0.035 + 0.15 = 0.29 %. EN 10088-2 allows stabilisation by titanium, niobium or zirconium in combination according to atomic mass equivalence. SHH STEEL checks the stabilising elements, carbon and nitrogen on every certificate as part of the 1.4592 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. How a tolerance applies to the calculated titanium minimum should be confirmed in the contract if a product analysis is ordered.

The 1.4592 mechanical properties below are the room-temperature values for the annealed condition in EN 10088-2:2014 Table 9. Only the cold rolled product form is listed for this special grade.

Elongation is measured on an 80 mm gauge length below 3 mm thickness and on a proportional gauge length (5.65√S0) from 3 mm upwards. For bigger sizes the values are to be agreed at the time of enquiry and order. Table 9 records resistance to intergranular corrosion (tested to EN ISO 3651-2) as “yes” in both the delivery and the welded condition.

A minimum proof strength of 430 MPa is about double that of EN 10088-2 1.4513 plate and well above austenitic 316L, which allows thinner tube walls. The other side is toughness: super-ferritics have a ductile-to-brittle transition that rises with thickness, which is the main reason they are used in thin gauges. SHH STEEL can add hardness, bend or impact tests on request.

Minimum 0.2 % proof strength at elevated temperature (EN 10088-2 Table 14, +A)

No value is given at 400 °C. High-chromium, high-molybdenum ferritics are prone to 475 °C embrittlement and to sigma and chi phases, so long service above about 300 °C is generally avoided.

X2CrMoTi29-4 plate and sheet are delivered in the annealed condition (+A). EN 10088-2 Table A.3 gives the guideline temperatures:

Annealing at 900 – 1 000 °C, followed by rapid cooling, is the highest annealing range of the ferritics in EN 10088-2. Rapid cooling is essential: slow cooling through the range of roughly 550 – 950 °C can form sigma and chi phases and severely reduce toughness and corrosion resistance. This is why heat treatment of super-ferritic strip is left to the mill and is rarely repeated by fabricators.

As with all 17 % chromium and higher ferritics, long exposure around 400 – 550 °C can cause 475 °C embrittlement, prolonged exposure at higher temperatures can form sigma phase, and over-heating coarsens the grain. These effects are general knowledge for the grade family rather than EN 10088-2 requirements. The Annex A temperatures are guidelines; actual furnace settings are chosen by the mill, and we check that the annealed condition is stated on each certificate.

The values below are room-temperature reference figures for X2CrMoTi29-4 1.4592, taken from the physical-property table in Euro Inox, Stainless Steel: Tables of Technical Properties (Materials and Applications Series, Volume 5). They are suitable for design estimates and weight calculation; where a figure is critical, use EN 10088-1 itself.

These approximate figures come from published datasheets, which do not fully agree for this grade; for design, use EN 10088-1 or the mill datasheet. Low thermal expansion and a thermal conductivity higher than that of austenitic grades are useful in condenser and heat-exchanger tubes, together with the high strength that allows thin walls.

The pitting resistance equivalent number (PREN = Cr + 3.3 Mo) of 1.4592 is roughly 40 – 45, in the range of super-austenitic and super-duplex grades and far above 316L (about 24) or 1.4521. This gives very good resistance to pitting and crevice corrosion in seawater, brackish water and many brines, and, as a ferritic, practical immunity to chloride stress corrosion cracking. Titanium stabilisation keeps welds resistant to intergranular corrosion.

In seawater service the alternatives are super-duplex grades such as EN 10028-7 1.4410 super duplex plate, super-austenitic grades or titanium. Standard duplex EN 10028-7 1.4462 duplex plate is lower in corrosion resistance and needs checking for warm seawater. The figures and guidance here are general and not part of EN 10088-2.

A specific caution for ferritic stainless steels in seawater systems is hydrogen embrittlement if the material is over-protected cathodically or coupled to very active metals. Designers should take this into account when using 1.4592 tubes with carbon steel or zinc anodes.

1.4592 can be welded by TIG, plasma and laser processes, and welded tube is the main product. Weld quality depends above all on preventing pick-up of carbon, nitrogen, oxygen and hydrogen, which quickly reduce toughness.

• Use high-purity argon shielding and backing, with trailing shields where possible; contamination makes the weld brittle.
• Keep heat input low and do not preheat; avoid slow cooling.
• Weld autogenously for tube, or use a matching super-ferritic filler; nickel-alloy fillers are sometimes used for tube-to-tubesheet welds.
• Clean surfaces thoroughly before welding to remove oil, marking ink and moisture.
• Qualify the procedure with bend tests, as the margin for error is small.

These points reflect industry practice for super-ferritic 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.

In the annealed condition 1.4592 ferritic sheet and strip form well enough for tube making, but its toughness falls as thickness increases, so bending of thicker sheet should be done carefully and preferably slightly warm, around 20 – 100 °C, in cold conditions. Shearing and punching should be done with sharp tools and adequate clearance to avoid edge cracks.

Machining is comparable to other stabilised ferritic grades and easier than for austenitic steels; the hard titanium or niobium carbonitrides that stabilise the steel can wear tools a little faster, so sharp tools and steady feeds are recommended. Punching and drilling of thin sheet is routine.

We run our own workshop next to the warehouse, so 1.4592 can be delivered as slit coil, cut-to-length sheets, laser-cut blanks or bent parts instead of raw mill sizes. Details are on our steel cutting services and bending and forming services pages. Protective film can be applied for visible or deep-drawn parts.

Because EN 10088-2 lists 1.4592 only as cold rolled strip and sheet, and toughness limits thicker sections, the supply range is thin gauge.

Tube making needs narrow width tolerance, low camber and crack-free edges, so state these with the EN ISO 9445 thickness class.

SHH STEEL can supply 1.4592 cold rolled sheet and strip in the sizes a qualified mill can roll, and slit coil to tube-mill widths, subject to mill confirmation. Hot rolled plate in this grade is not covered by EN 10088-2.

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.

For condenser and heat-exchanger tubing, surface cleanliness is as important as finish. Contamination such as embedded iron can start corrosion in seawater, so state packing and handling requirements, and SHH STEEL will protect edges and surfaces during slitting and packing.

Buyers looking for a 29-4C super ferritic equivalent in EN terms will be offered 1.4592. The American and Chinese grades are close, while Japan has no direct counterpart.

As a 1.4592 equivalent, UNS S44735 is the practical match. Some cross-reference tables list UNS S44700 (29-4) instead; in ASTM A240 that grade has extra-low carbon and nitrogen (C ≤ 0.010 %, N ≤ 0.020 %, C + N ≤ 0.025 %), nickel ≤ 0.15 % and no titanium requirement, so it is a related rather than identical grade. UNS S44800 (29-4-2) adds 2.00 – 2.50 % nickel and is further away still. Do not confuse either with lower-molybdenum high-chromium grades such as GB/T 4237 008Cr27Mo S12791 plate. SHH STEEL compares the limits for each drawing.

1.4592 vs 1.4521, duplex and 316L

Compared with EN 10088-2 1.4521 plate (444 type), 1.4592 has about 11 % more chromium and twice the molybdenum, moving it from potable-water service into seawater service. Compared with ASTM A240 Type 316L sheet and plate it is much stronger and far more resistant to chlorides, but less tough and limited to thin gauges. Compared with super-duplex, it is nickel-free and has high thermal conductivity, but it is less tough and is used mainly as thin strip and tube.

Typical applications of 1.4592 ferritic plate and strip include:

• Seawater-cooled power plant condenser tubes
• Heat exchanger tubing for brackish and seawater cooling
• Desalination plant heat-exchange parts
• Chemical and process heat exchangers handling chloride brines
• Tube-sheet cladding and baffles in thin gauge
• Flue gas desulphurisation and other chloride-bearing environments, case by case

1.4592 does not appear in EN 10028-7:2016, so pressure-equipment use has to be qualified by other routes. Tubes are normally made to tube standards, and the strip order should reference the tube standard’s requirements where relevant.

Because this is a niche grade, SHH STEEL recommends sharing the full tube or equipment specification at enquiry, so the mill can confirm melting route, gauge and test requirements before quoting.

Most problems with 1.4592 come from its rarity, from substitution with lower-alloyed grades, and from toughness and welding issues.

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 1.4592 order is supported by documents and checks that make the material traceable to the heat:

• Cast analysis with carbon, nitrogen and titanium minimum checked
• Tensile test on the annealed strip: Rp0.2, Rm and A
• Intergranular corrosion test to EN ISO 3651-2 when ordered; pitting tests such as ASTM G48 by agreement
• Bend or impact tests when agreed
• 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 heat-exchanger 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 t cold rolled strip, 0.7 mm × 1 000 mm coil, EN 10088-2, steel X2CrMoTi29-4 (1.4592), process route 2B, 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 1.4592 is a rare super-ferritic grade, melting slots are limited and the schedule is confirmed for each 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 1.4592 and related high-alloy 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 1.4592 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 X2CrMoTi29-4 1.4592 is the 29 % chromium, 4 % molybdenum super-ferritic of the standard, used mainly as thin strip for seawater-cooled condenser and heat-exchanger tubing, and a rare grade that few mills produce. 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.