1.4467 super duplex forgings

What 1.4467 means, and why you cannot order against it alone

European steel material numbers, the Werkstoffnummer system, identify an alloy rather than a purchase specification. Numbers in the 1.44xx block cover stainless steels, and the austenitic-ferritic (duplex) grades sit between 1.4362 and 1.4507. 1.4467 is used commercially inside that block for the 25Cr-7Ni-4Mo-N super duplex composition, the same alloy that carries the number 1.4410 in EN 10088-1 and EN 10088-3.

The distinction matters at the moment a certificate is issued. A material number on its own states no composition window, no heat-treatment requirement, no mechanical minima and no acceptance criteria. Those live in a product standard. For this alloy the product standards are EN 10088-3 (bars, rods and sections), EN 10250-4 (open-die forgings in stainless steel), EN 10222-5 and EN 10272 (forgings and bars for pressure purposes), and ASTM A182/A182M Grade F53 (forged flanges, fittings and valve parts). None of them lists 1.4467.

If 1.4467 came from a drawing or a client specification

Older national standards, company standards and translated specifications sometimes carry numbers that are no longer in the current EN tables, or that belong to a cast rather than a wrought grade. Two checks settle it quickly:

1. Find the source document. The standard number and revision printed next to the material number tells us whether the requirement is wrought or cast, and which composition window applies.
2. Check whether the part is forged or cast. Cast super duplex of similar chemistry is covered by ASTM A890/A995 Grade 5A (CE3MN, J93404) and by the G-prefixed EN numbers. A casting specification cannot be satisfied by a forging, and the reverse is also true.

Send the document with the enquiry and the forging will be made and certified to it. Where no document exists, the default route is ASTM A182 F53 for valve, flange and fitting forgings, and EN 10250-4 with grade 1.4410 for general open-die work.

Cross-reference: what 1.4467 maps to

The designations below all describe the 25Cr-7Ni-4Mo-N super duplex alloy. They are not interchangeable as specifications, because each standard sets its own limits. A mill or forge working to one can normally certify to the others, provided the heat falls inside both windows.

The closest commercial alternative is 1.4501 / S32760 (F55, Zeron 100), which adds copper and tungsten. One class below sits A182 F51 (2205 / 1.4462). The full datasheet for this alloy is on the 1.4410 / S32750 page, covering composition limits side by side, physical properties, temperature windows and impact requirements.

Composition and properties in brief

Buyers cite either EN 10088-3 (as 1.4410) or ASTM A182 (as F53). The two windows differ in three places: ASTM caps manganese and silicon more tightly, allows molybdenum up to 5.0 %, and limits copper, while EN allows nitrogen up to 0.35 %.

Impact toughness

Charpy V-notch testing is not a base requirement of A182 for F53, but offshore and subsea purchase specifications almost always add it. Testing at −46 °C is the usual requirement, with acceptance stated as a minimum average of 45 J over three specimens and no single value below 35 J. State the test temperature, specimen orientation and acceptance values in the enquiry, because they affect the forging and quenching route rather than being added at the end.

Physical behaviour and service limits

Density is 7.80 g/cm³, modulus of elasticity about 200 GPa, thermal conductivity about 15 W/(m·K) and mean thermal expansion about 13 × 10⁻⁶ K⁻¹. Conductivity is higher and expansion lower than in 316L, so large duplex fabrications distort less. The ferrite phase makes the alloy ferromagnetic: a magnet sticking to a super duplex forging is normal and says nothing about whether the grade is correct. Continuous service is normally limited to about 300 °C because of 475 °C embrittlement, and to about −50 °C at the low end.

What to put on the purchase order

Naming 1.4467 alone leaves the acceptance criteria undefined, which is where receiving-inspection disputes start. Name one governing specification and add the six items below. Quotations are normally returned within two working days when they are all present.

Forging and heat treatment of 25-7-4 super duplex

Super duplex has a narrow hot-working window and two temperature ranges that must not be held. The manufacturing route follows from that, and it is the reason super duplex forgings cost more than austenitic ones of the same size.

Forging practice

• Soak the ingot or billet uniformly. Minimum soaking temperature is about 1050 °C, so the core reaches working temperature before the surface overheats.
• Work between 1230 °C and 1025 °C. The window is roughly half as wide as for carbon steel.
• Reheat rather than continue working. Duplex has low hot strength and a narrow window, so heavy open-die work is taken in several heats.
• Never air cool from forging heat. Every forging is solution annealed after the last blow.

Solution annealing, quench and the real size limit

Heat to 1040 to 1120 °C, hold until the section has equalised, then water quench. ASTM A182 requires solution treatment at not less than 1025 °C with liquid quenching and cooling below 260 °C. Heavy sections have to reach the quench tank without delay.

Re-heat-treatment after thermal work

A forging that has been welded, flame cut, hot straightened or stress relieved after solution annealing will normally have precipitated intermetallic phase. Corrosion resistance drops while tensile testing still passes, so the fault is usually found in service rather than at inspection. Any thermal operation after the final anneal calls for re-solution-annealing and re-quenching.

Machining and cold work

25-7-4 super duplex is difficult to machine. Compared with 316/316L, cutting speeds have to be reduced by roughly half with coated carbide tooling, while feeds are reduced only slightly, because light feeds cause work-hardening and rubbing. Rigid setups, sharp cutting edges and generous coolant are necessary. Severe or complex cold forming calls for an intermediate solution anneal, and duplex grades need a more generous bend radius than austenitic grades. After heat treatment, pickling and passivation restore the surface oxide and the full corrosion resistance.

Forgings produced in 1.4467 super duplex

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory. Parts are made to customer drawing or specification rather than supplied from a catalogue of standard sizes.

Plant envelope

Melting, testing and certification

This plant melts its own steel. Most forging suppliers in China buy billet; here the route starts at the furnace, which in super duplex matters more than in most grades. Nitrogen is both a strengthening element and, at sixteen times its weight fraction, the largest single term in the PREN equation. Nitrogen control at the melt stage therefore decides whether the heat reaches PREN 40.

Melting route

Super duplex runs through the electric arc furnace, is refined in a ladle furnace and decarburised under vacuum (EAF + LF + VOD), with ESR remelting available where the specification or the section size calls for it. Maximum heat size is 60 tonnes. Because melting is on site, the certificate traces a part back to its melt number rather than stopping at a purchased billet certificate.

Non-destructive and destructive testing

• Ultrasonic examination to EN 10228-4, SEP 1921 or ASTM A388, to the acceptance class stated in your order. EN 10228-4 is the part written for austenitic and austenitic-ferritic stainless forgings; EN 10228-3 covers ferritic and martensitic steels and does not apply here.
• Liquid penetrant and magnetic particle examination of machined surfaces where specified.
• Tensile, hardness and Charpy V-notch impact testing on test material representing the heat and the heat-treatment lot, commonly at −46 °C for offshore and subsea work.
• Ferrite content by metallographic point count to ASTM E562. Purchase specifications commonly require 35 to 55 % ferrite for forgings.
• Detrimental intermetallic phase detection to ASTM A923, by Method A metallographic screening, Method B impact testing or Method C ferric chloride corrosion testing.
• Pitting corrosion testing to ASTM G48 Method A, commonly at 50 °C for 24 h with no pitting at 20× magnification.
• Positive material identification on finished parts where required.

Chemistry, tensile, impact, hardness, ultrasonic, magnetic particle and metallography are run in the on-site laboratory. ASTM A262, G28, G48 and A923 testing and impact testing below −60 °C are placed with an accredited third-party laboratory and reported alongside the mill certificate. State these requirements at enquiry stage so they are scheduled before shipment.

Approvals and documentation

Where 1.4467 sits against neighbouring grades

The usual question is whether the step up from 2205 is justified. The pitting resistance equivalent number is the standard first check for chloride service:

PREN = %Cr + 3.3 × %Mo + 16 × %N

At the nominal composition of 25 Cr, 4.0 Mo and 0.28 N this gives 25.0 + 13.2 + 4.48 = 42.7. The super duplex class is conventionally defined as PREN of at least 40, and mills supplying offshore work normally target 41 to 43.

Selection notes

• Moving up from 2205 is normal where chlorides exceed roughly 1,000 ppm above 40 °C, where the duty is seawater or produced water, where NACE MR0175 / ISO 15156 service requires PREN above 40, or where strength governs section size.
• 25-7-4 or 1.4501. Mechanically and in most chloride media the two are equivalent. The copper and tungsten in 1.4501 are preferred by some specifications for acid-bearing and severe seawater service. In practice the project specification or the approved vendor list decides, not the metallurgy.
• 904L or a nickel alloy remains the better choice where service is above 300 °C, below −50 °C, or dominated by strong reducing acids rather than by chlorides. Duplex grades are not suited to those conditions.

Applications

• Offshore oil and gas. Wellhead and christmas-tree components, manifold blocks, subsea housings, riser and flowline flanges, valve blocks, produced-water and seawater-injection parts.
• Valves and pumps. Bodies, bonnets, seat rings, stems, discs and shafts for ball, gate, globe, check and plug valves in chloride duty.
• Seawater desalination. High-pressure pump parts, energy-recovery components, reverse-osmosis piping and vessel forgings in concentrated brine.
• Heat exchangers and pressure vessels. Tube sheets, nozzles, closure heads and covers in chloride-bearing cooling and process water.
• Marine propulsion. Propeller shafts, pump shafts, tie bars, ballast and fire-fighting system components.
• Chemical, petrochemical and urea plant. Agitator shafts, centrifugal separator parts, chemical tanker cargo system components, highly stressed parts in corrosive service.
• Pulp and paper. Digester and liquor-tank components, bleach-plant equipment.
• Power and flue-gas desulphurisation. Absorber internals, cooling-water and service-water systems, low-pressure compressor components.

Frequently asked questions

Supplier and contact

Related grades

• 1.4410 / S32750 full datasheet
• A182-F53
• A182-F55 / 1.4501
• A182-F51 / 2205
• 1.4462
• A182-F44 / 254 SMO
• A182-F61
• 904L
• Sanicro 28
• Nitronic 50
• Inconel 625
• All stainless grades