1.4507 (X2CrNiMoCuN25-6-3 / UNS S32760) Super Duplex Stainless Steel Forging Parts | Jiangsu Liangyi — China Professional Forging Manufacturer

What Is 1.4507 (X2CrNiMoCuN25-6-3) Super Duplex Stainless Steel — And Why Does It Matter for Forgings?

1.4507, designated X2CrNiMoCuN25-6-3 under the EN 10088 European standard and cross-referenced as UNS S32760 in ASTM/ASME specifications, is a premium-grade super duplex stainless steel engineered specifically for environments where standard austenitic grades fail. The "duplex" designation reflects its carefully balanced two-phase microstructure: approximately 50% ferrite and 50% austenite, a ratio that is achieved and locked in during the solution annealing heat treatment at 1,080–1,120 °C followed by rapid water quenching.

What makes this grade genuinely exceptional is not any single property but the simultaneous delivery of three performance pillars that engineers normally have to trade off against one another:

• Superior corrosion resistance: A calculated PREN (Pitting Resistance Equivalent Number) ≥ 40 — the internationally accepted threshold for "super duplex" classification — placing it well above standard duplex grades such as 2205 (PREN ~35) and orders of magnitude above 316L (PREN ~24).
• High mechanical strength: A minimum yield strength of 500 MPa (Rp0.2), nearly twice that of 316L stainless steel (≈ 220 MPa), enabling component wall thickness reduction and significant weight savings without sacrificing structural integrity.
• Practical weldability: Despite the high alloy content, the controlled low carbon (≤ 0.030 wt%) and balanced nitrogen content allow 1.4507 to be welded using qualified procedures without post-weld heat treatment in most applications.

The addition of copper (1.0–2.5 wt%) is a distinguishing feature of the 1.4507 / UNS S32760 grade that is often under-appreciated. Copper specifically improves resistance to non-oxidizing acids — particularly sulfuric acid (H₂SO₄) and phosphoric acid (H₃PO₄) — making 1.4507 the preferred material in chemical processing applications where these media are present, a scenario where even other super duplex grades struggle.

Why forging rather than casting for 1.4507? The answer lies in metallurgy. During the open die forging process the mechanical working of the steel at elevated temperature refines the grain matrix, eliminates cast dendrites and porosity and produces a wrought fibrous grain flow that follows the shape of the component. The result is much higher toughness, better fatigue resistance and more consistent through-thickness mechanical properties than cast equivalents – essential benefits in rotating equipment, pressure vessels and subsea components where failure is not an option.

Understanding PREN ≥ 40: The Engineering Logic Behind Selecting 1.4507

The Pitting Resistance Equivalent Number (PREN) is the industry's standard single-number index for comparing the pitting corrosion resistance of stainless steels in chloride environments. For duplex and super duplex grades, the formula used by EN 10088 and most major international standards is:

Applying this formula to the nominal composition of 1.4507 (X2CrNiMoCuN25-6-3) at typical mid-range values (Cr 25%, Mo 3.5%, N 0.25%) yields:

This numerical exercise reveals why 1.4507's minimum PREN requirement of ≥ 40 is so meaningful: it corresponds to Critical Pitting Temperature (CPT) values typically exceeding 40–50 °C in 6% FeCl₃ test solutions (ASTM G48 Method C), a performance level that is simply unachievable with 316L or standard duplex 2205 in aggressive chloride-containing service environments such as seawater, produced brine, or chloride-laden process streams.

1.4507 vs. 2205 vs. 316L: A Direct Technical Comparison for Material Selection

Engineers’ choice of materials for corrosive service often includes an assessment of 1.4507 (X2CrNiMoCuN25-6-3) versus the industry standard 2205 duplex and the ubiquitous 316L austenitic grade. The following is a list of key differentiators based on EN 10088 and ASTM specifications:

Complete Range of Custom 1.4507 (X2CrNiMoCuN25-6-3) Forged Products

Jiangsu Liangyi Co., Limited, established in 1997, is an ISO 9001:2015 certified China manufacturer of 1.4507 super duplex stainless steel forging parts with over 25 years of specialized experience. Our 80,000 m² production base houses a fully integrated manufacturing chain — from steel billet qualification through open die forging on our 6,000-ton hydraulic press, to solution annealing heat treatment and precision CNC machining — enabling complete material traceability from billet to finished forging. Single-piece weight range: 30 kg to 30 tons.

1.4507 Forged Bars, Rods & Shafts

We supply X2CrNiMoCuN25-6-3 forged round bars, square bars, flat bars, step shafts, flanged shafts, and splined shafts. Unlike mill-rolled bar, our open die forged bars undergo multiple deformation passes with precise reheating intervals, refining grain structure throughout the cross-section. Maximum forging diameter: 2,000 mm. All bars are 100% UT tested to DIN EN 10228-3 or ASTM A388, and supplied with EN 10204 3.1 or 3.2 certificates. Typical applications: valve stems for subsea Christmas trees, pump shafts for corrosive process pumps, drill-collar blanks, structural tie-rods for offshore jacket structures.

1.4507 Seamless Rolled Forged Rings

Using our 1–5 meter radial-axial ring rolling mills combined with the 6,000-ton hydraulic press for initial upsetting and piercing, we produce seamless forged rings from 200 mm to 6,000 mm OD, up to 30 tons per piece. The ring rolling process aligns grain flow circumferentially — the optimal orientation for resisting hoop stresses and cyclic pressure in flanges, valve seat rings, and rotating machine components. Standards: EN 10250-4, ASTM A182 Grade F55, API 6D. Post-machining to final dimensions with surface finish Ra ≤ 1.6 μm available.

1.4507 Hollow Forgings, Shells, Sleeves & Heavy-Wall Pipes

Produced by our mandrel-forging and elongation-over-mandrel processes, our hollow 1.4507 forgings — shells, tubing shells, reactor nozzle forgings, sleeves, and hydraulic cylinder barrels — achieve better bore dimensional accuracy and superior surface quality versus conventional piercing. OD capacity: 3,000 mm. Critical for subsea tubing hanger assemblies, high-pressure wellhead casing spools, and heavy-wall heat exchanger shells in aggressive acid service where through-wall corrosion is the primary failure mode.

1.4507 Forged Discs, Flanged Blanks, Plates & Structural Blocks

Our X2CrNiMoCuN25-6-3 forged discs and flanged blanks — up to 3,000 mm diameter, 20 tons — are forged from individually certified heats and solution-annealed as individual pieces, not cut from bar, ensuring uniform mechanical properties across the full thickness. Applications: tube sheet blanks for heat exchangers, pressure vessel end closures, valve bonnet forgings, and subsea manifold structural blocks. Tolerances to EN 10243-1 Class D standard; tighter tolerances achievable upon drawing review.

1.4507 Precision Valve Body, Ball, Stem & Flow Control Forgings

With 20+ years of specialized experience supplying 1.4507 forged valve components to OEMs and EPC contractors across Europe, North America, and the Middle East, our valve forging portfolio covers the complete range: valve bodies (gate, globe, ball, butterfly, check), trunnion-mounted and floating valve balls, valve bonnets, stems, seat rings, closures, and yokes — bore sizes DN 50 to DN 1200. Standards: API 6A, API 6D, EN 12516-3. Critical forging sequence parameters (die fill, reduction ratio, grain flow orientation relative to pressure-retaining walls) are engineered for each geometry to meet API 598 pressure test requirements. We also supply forged bodies for ultrasonic flow meters, vortex flow meters, venturi cone meters, and multiphase flow meters.

1.4507 Pump Casings, Impellers & Turbomachinery Components

Our 1.4507 forged turbomachinery components — centrifugal pump casings (radially and axially split), open/semi-open/shrouded impellers, pump barrels, wear rings, compressor casings, labyrinth shaft seals, and diffuser rings — are engineered with grain flow patterns optimized for the dominant stress direction in each component. Impeller hydraulic profile tolerances: ±0.1 mm; balance grade: ISO 1940 G2.5; flow-path surface finish: Ra ≤ 3.2 μm standard. Forging-plus-machining eliminates the porosity and hot-tear defects common in cast pump components, which are a leading cause of pump failures in corrosive service.

End-to-End 1.4507 Forging Manufacturing Process — 5 Controlled Steps

Jiangsu Liangyi controls the complete production chain for every 1.4507 forging order in-house. This integrated capability is the foundation of our quality assurance system and enables genuine heat-by-heat material traceability from the original steel melt to the certified component at your port of loading.

Step 1 — Steel Melting, Ingot Qualification & Incoming Inspection

1.4507 super duplex stainless steel presents specific difficulties in the melting: - the high chromium and molybdenum content requires a careful control of the temperature, - the addition of nitrogen (0.20-0.30 wt%) under controlled pressure during the AOD (Argon Oxygen Decarburization) refining to avoid gaseous nitrogen porosity in the solidifying ingot. We work exclusively with qualified steel mills whose melting procedures are validated against our incoming material qualification protocol. For critical nuclear-grade or high-specification orders, electroslag remelting (ESR) of the primary ingot is available to further improve inclusion cleanliness and chemical homogeneity — particularly important for large-diameter bar and disc forgings where through-thickness property uniformity is specified. Every incoming billet is inspected for chemical composition by OES (optical emission spectrometry), dimensional and weight verification, and visual surface condition before any forging work begins.

Step 2 — Controlled Ingot Heating & Open Die Breakdown Forging

The heating schedule before and between forging passes is one of the most consequential process parameters for 1.4507. The steel must be heated above the sigma-phase dissolution temperature (~1,020 °C) to ensure the starting microstructure is free from embrittling intermetallic phases, but not held at temperatures above ~1,280 °C to avoid excessive grain growth. Our furnace management system records and archives the full time-temperature history of every forging heat — this record is included in the final documentation package. Our 6,000-ton hydraulic press applies controlled reduction ratios: typically ≥ 4:1 for bars and shafts, ≥ 6:1 for rings after piercing — sufficient to fully work the ingot cross-section and eliminate residual cast structure.

Step 3 — Seamless Ring Rolling on Radial-Axial Mills

After initial upsetting and piercing on the hydraulic press, ring blanks are transferred hot to our computer-controlled radial-axial ring rolling mills. The axial rolls simultaneously control ring height while the radial rolls reduce wall thickness and expand the diameter. This combination produces a circumferentially oriented wrought fibrous grain structure — fundamentally superior to machined-from-bar rings for applications subjected to cyclic pressure loading and temperature cycling. Ring OD from 200 mm to 6,000 mm; ring height controlled to ±3 mm of nominal as forged.

Step 4 — Solution Annealing Heat Treatment

Solution annealing is the critical final thermal process for 1.4507. Each forging or batch is heated uniformly to 1,080–1,120 °C in our computer-controlled furnaces, held for a calculated soak time (minimum 30 minutes per 25 mm of section thickness), and quenched rapidly in a water tank or with forced water jets. The quench rate through the 900–600 °C range is especially critical: insufficient quench rate in this window allows sigma-phase and chi-phase intermetallic formation, which severely degrades both toughness and corrosion resistance. All furnace time-temperature charts and quench records are archived as part of the permanent quality documentation and available to clients upon request.

Step 5 — CNC Precision Machining & Final Dimensional Inspection

Our in-house CNC facility includes heavy-duty CNC turning centers (max. swing 5,000 mm), CNC horizontal boring mills, CNC vertical turning/milling centers, and deep-hole drilling equipment. We deliver 1.4507 forgings in finish-machined condition to your 2D drawings or 3D CAD models (STEP, IGES, Parasolid), eliminating the need for a separate machining subcontractor. Dimensional inspection is performed by CMM (coordinate measuring machine) for complex 3D geometries, with full inspection reports included in the documentation package. Surface finish capability: Ra 25 μm (rough-machined) to Ra 0.8 μm (fine-turned/ground).

1.4507 (X2CrNiMoCuN25-6-3) Chemical Composition — EN 10088-3 Requirements & the Role of Each Alloying Element

Understanding why each element is present — and what happens when it falls outside the specified range — is essential for procurement engineers and quality managers evaluating 1.4507 forging materials:

At Jiangsu Liangyi, both ladle analysis (heat analysis from the steelmaker) and product analysis (check analysis from finished forgings) are performed and reported in the material test certificate. Our quality system internally targets the tighter ladle values to provide a safety margin against product analysis non-conformance.

1.4507 Forging Heat Treatment Protocol & Full Mechanical Property Data

Solution annealing at 1,080–1,120 °C followed by rapid water quenching is the mandatory delivery condition per EN 10088-3. This heat treatment simultaneously dissolves sigma phase and intermetallic phases, re-establishes the correct ferrite/austenite phase balance, and fully re-dissolves chromium carbides — restoring maximum corrosion resistance and toughness. Guaranteed mechanical properties:

Important temperature service limitation: 1.4507 super duplex stainless steel should not be used in continuous service above approximately 280 °C. Prolonged exposure in the 300–550 °C range promotes precipitation of embrittling sigma and chi intermetallic phases. For cyclic or short-term elevated-temperature exposure below this threshold, 1.4507 performs well. Clients with elevated-temperature design requirements should contact our technical team for a detailed service assessment before final material selection.

International Standards Compliance & 10-Gate Quality Control System

Global Standards for 1.4507 Forging Parts — By Market Region

Our 1.4507 (X2CrNiMoCuN25-6-3) forging parts are manufactured in compliance with the following standards, selected to match the regulatory and project requirements of each global market:

10 Mandatory Quality Gates — Our ISO 9001:2015 Inspection Protocol

Every 1.4507 forging order at Jiangsu Liangyi must pass 10 mandatory quality checkpoints before proceeding to the next production step. This ensures non-conformances are detected at the earliest possible point, before further value is added to a potentially defective component:

• Gate 1 — Incoming Steel Billet Inspection: Full OES chemical analysis of each heat, dimensional and weight verification, visual surface inspection, cross-reference against the steel mill's ladle analysis certificate. Non-conforming heats are rejected before any forging work begins.
• Gate 2 — Furnace Heating Record Verification: The whole heating process of each billet is registered by the automated furnace control. The billet is sent to the forging press after the holding time at target temperature and peak temperature are checked against the approved Forging Procedure Specification (FPS).
• Gate 3 — In-Process Dimensional Check During Forging: At intermediate stages of forging the inspectors measure key dimensions (cross-section, length, step diameters). For multi-pass forgings having reheat cycles a check is made after each reheat pass.
• Gate 4 — Post-Forging Visual & Dimensional Inspection: Full surface visual examination for laps, cold shuts, cracks, and scale pitting. Dimensional check against the forging drawing with documented records.
• Gate 5 — Heat Treatment Record Verification & Post-HT Hardness Check: Solution annealing cycle parameters (target temperature, actual temperature, soak time, quench method) verified from furnace records. Brinell hardness measured on each forging in the heat treatment lot.
• Gate 6 — Chemical Product Analysis: Sample cut from each qualified test piece (QTP) is analyzed by OES for product analysis (check analysis). Results compared against EN 10088-3 composition limits including product analysis tolerances per EN 10088 Annex A.
• Gate 7 — Mechanical Property Testing: Tensile test (Rm, Rp0.2, A5%), Charpy V-notch impact test at specified temperature and hardness tests performed on samples from the qualified test piece – all in our in-house testing laboratory with calibrated instruments maintained under our ISO 9001:2015 quality management system. (If the order requires independent laboratory verification, samples can be sent to a third party accredited laboratory at the client's request.)
• Gate 8 — Non-Destructive Testing (NDT): 100% ultrasonic testing (UT) to EN 10228-3 Quality Level Q3 or ASTM A388. MT or PT on all accessible surfaces per EN 10228-4 or ASTM E709. Radiographic testing (RT) available on request.
• Gate 9 — Final Dimensional & Surface Finish Inspection: Complete dimensional verification against the final drawing with calibrated instruments. Surface roughness measurement where specified. Mark verification per EN 10088-3 or ASTM marking requirements.
• Gate 10 — Document Package Review & Release Authorization: Quality manager reviews the complete documentation package before issuing the EN 10204 3.1 or 3.2 certificate and authorizing shipment. For EN 10204 3.2 orders, the client's nominated inspection agency co-signs at this gate.

Global Industry Applications & Verified Project Case Studies

The following application descriptions and project cases are drawn from Jiangsu Liangyi's actual delivery history across 50+ countries. They are presented to help engineers and procurement managers evaluate whether 1.4507 (X2CrNiMoCuN25-6-3) forging parts from Jiangsu Liangyi are the right fit for their specific project requirements.

Oil & Gas — Onshore & Offshore Wellhead, Subsea, and Sour Service

The Challenge: The combination of H2S (hydrogen sulfide), CO2 (carbon dioxide), produced water containing Cl- (chloride ions) and HPHT (high pressure, high temperature) conditions leads to a “sour service” regime where conventional ferritic steels are susceptible to sulfide stress cracking (SSC), austenitic stainless steels to chloride stress corrosion cracking (Cl-SCC), and only NACE qualified alloys can offer reliable long-term service.

The 1.4507 Advantage: 1.4507 (X2CrNiMoCuN25-6-3) is explicitly listed in NACE MR0175 / ISO 15156-3 Table A.3 as a qualifying material for sour service in the solution-annealed condition, with hardness HRC ≤ 36 (HBW ≤ 340) — a requirement our standard protocol ensures is consistently met. The duplex microstructure inherently confers excellent SSC resistance: the ferritic phase is more resistant to SSC than austenitic steel, while the balanced austenite phase provides the low-temperature toughness that purely ferritic steels lack.

Key 1.4507 forged components supplied by Jiangsu Liangyi for oil & gas service: wellhead Christmas tree valve bodies and bonnets, BOP component forgings, API 6A pressure class 5,000–20,000 psi gate valve bodies, tubing hanger bodies and mandrels, casing hanger forgings, subsea connector hub forgings, subsea choke valve bodies, riser flange forgings, and downhole drilling tool components.

Chemical & Petrochemical Processing — Acid Corrosion, SCC, and Long Service Life

The Challenge: Chemical process plants often involve known corrosive media at defined concentrations and temperatures — concentrated sulfuric acid, wet phosphoric acid, acetic acid, formic acid — that overwhelm the protection capability of standard stainless steels. 316L corrodes at rates that make it commercially unviable in many of these services. The specific combination of high Cr, high Mo, high N, and — critically — 1–2.5% Cu in 1.4507 delivers a step-change in resistance to reducing acid corrosion that is not achievable with grades lacking the copper addition.

The Mechanism: Copper preferentially deposits at active dissolution sites, inhibiting the cathodic hydrogen evolution reaction that drives anodic dissolution, effectively raising the corrosion potential of the steel into the passive range even in strongly reducing acid environments. For H₂SO₄ concentrations in the 10–60 wt% range at temperatures up to 70 °C, and for wet phosphoric acid (28–40 wt% P₂O₅) at process temperatures, 1.4507 demonstrates corrosion rates 5–20× lower than 316L in independent laboratory testing.

Nuclear Power — Safety-Critical Forgings with Full Traceability

The Challenge: Nuclear power applications impose the most stringent requirements on material traceability, qualification, and documentation. Every kilogram of steel in a safety-related nuclear component must be traceable to a specific verified heat, manufactured using a qualified and audited process route, tested by qualified inspectors with calibrated equipment, and documented in a quality dossier accessible for the operational life of the nuclear installation — potentially 60+ years. The primary appeal of 1.4507 in nuclear service is its superior resistance to chloride stress corrosion cracking (Cl-SCC) in boric acid-treated reactor coolant water, combined with its high mechanical strength allowing thinner, lighter component designs.

Offshore Wind Power & Marine Renewable Energy

The Challenge: Offshore wind turbines in the North Sea, Baltic Sea, and other locations operate in a uniquely aggressive environment: continuous seawater exposure, high mechanical cyclic loading from turbine rotation and wave action, and expected lifetimes exceeding 25 years with minimal maintenance. These conditions rule out conventional carbon steel flanges and shaft connections without aggressive cathodic protection and coating systems, pushing designers toward corrosion-resistant alloy (CRA) forgings for structural applications that are difficult to externally protect.

The 1.4507 Advantage: Seawater pitting resistance with CPT > 40 °C (ASTM G48 Method C), combined with the high fatigue strength inherent in the forged duplex microstructure — make 1.4507 technically superior to both 2205 and 316L for offshore wind structural flange applications. Our seamless rolled ring forgings for offshore wind tower flanges are routinely produced with OD from 1,500 mm to 4,500 mm, to EN 10250-4 and DNV material standards, with impact testing at −20 °C standard to cover Arctic and sub-Arctic installation scenarios.

Desalination & Water Treatment — Extreme Chloride Service

The Challenge: Large-scale seawater reverse osmosis (SWRO) desalination plants operate under extreme chloride exposure: seawater at Cl⁻ concentrations of 19,000–35,000 ppm, pressures up to 80 bar for high-pressure pump trains, and expected lifetimes exceeding 25 years without pump casing replacement. This combination makes 316L and even 2205 duplex steel inadequate for high-pressure pump casings and energy recovery device components — applications where 1.4507 has become the specified material of choice.

Note on Project Case Studies: The project cases presented on this page are based on actual deliveries made by Jiangsu Liangyi. Specific numerical data (quantities, capacities, plant outputs) are provided as representative examples. Due to confidentiality obligations we do not identify clients by name. Prospective clients may request general reference information through our sales team.

Why Global Buyers Choose Jiangsu Liangyi for 1.4507 Super Duplex Forging Parts

There are dozens of forging manufacturers in China. The following are the specific, verifiable differentiators that have led clients in 50+ countries to place repeat orders with us over periods spanning 5–20 years:

• Fully Integrated Manufacturing — No Subcontracting of Core Processes: We perform steel billet sourcing and qualification, open die forging, ring rolling, solution annealing heat treatment, CNC machining, and all mechanical and NDT testing within our own 80,000 m² facility. Quality control has direct authority over every value-adding step — there are no "black box" subcontracted operations where non-conformances can develop undetected.
• Large-Section Capability Demonstrated by Actual Delivery Records: Our 6,000-ton hydraulic forging press capability has been demonstrated in actual production of 1.4507 single-piece forgings up to 30 tons, with certified mechanical test results on file. We quote capability based on what we have actually manufactured and delivered — not theoretical equipment nameplate ratings.
• 15+ Years of Dedicated 1.4507 / Super Duplex Specialization: Our forging engineers and heat treatment specialists have built up specific procedural knowledge and archived process parameter records for 1.4507 in 15+ years of continuous production. This is important when clients ask for unusual section geometries, tight PREN minimum specifications or difficult low temperature impact test requirements.
• EN 10204 3.2 Inspection Readiness as a Standard Service: Our quality system is designed to support third-party witnessed inspection routinely, not as an exception. We can set up witnessed inspection appointments with all major international inspection agencies such as BV, SGS, TÜV SÜD, TÜV Rheinland, TÜV Nord, DNV GL, Lloyd's Register (LR), Intertek (ITS) and RINA. At the time of order, the client selects the preferred inspection agency and we work out the scheduling and access to facilitate the witnessing process without affecting the production schedule.
• Competitive Lead Times: Standard 1.4507 forging orders typically complete in 3–6 weeks (simple shapes, standard sizes, available material). Complicate custom forgings with special heat treatment sequences or extensive NDT: 6–10 weeks. We provide detailed production timelines with milestone dates at order confirmation, and keep schedule visibility through weekly progress reports for orders exceeding 10 tons or involving multiple part numbers.
• Full Price Transparency: Our quotations are itemized to cover the forging unit price, heat treatment, mechanical testing, NDT, dimensional inspection, EN 10204 certificate (3.1 or 3.2), surface protection, and freight to named port of loading. There are no subsequent invoices for "extra tests" or "certificate fees" not included in the original quotation.