Chemical Processing
Heat exchangers, reaction vessels, chemical tanks, and piping for sulfuric acid, phosphoric acid, hydrochloric acid, and chloride-containing process streams. Copper addition specifically benefits reducing acid environments.
Section 01 — Overview
What Exactly Is 1.4529 Steel?
- 1.4529 Steel — Formal Definition
- 1.4529 (X1NiCrMoCuN25-20-7, Alloy 926, UNS N08926) is a high-alloyed super austenitic stainless steel containing 19–21% chromium, 24–26% nickel, 6–7% molybdenum, 0.5–1.5% copper, and 0.15–0.25% nitrogen, with carbon below 0.020%. It achieves a Pitting Resistance Equivalent Number (PREN) consistently greater than 42, classifying it as a super austenitic grade per EN 10088-3.
1.4529 — also designated X1NiCrMoCuN25-20-7, commercially known as Alloy 926, and classified as UNS N08926 under ASTM/UNS standards — is a premium-grade super austenitic stainless steel that bridges the performance gap between conventional austenitic grades such as AISI 316L and more expensive nickel-based superalloys.
When delivered in the solution-annealed condition per EN 10088-3, 1.4529 demonstrates resistance to intercrystalline corrosion, pitting corrosion, crevice corrosion, and stress corrosion cracking across a wide range of aggressive environments — including seawater, high-concentration chloride solutions, sulfuric acid (H₂SO₄), and phosphoric acid (H₃PO₄) in both liquid and gaseous forms.
Key Facts: 1.4529 Steel at a Glance
- PREN consistently greater than 42 — qualifies as super austenitic (threshold: PREN >40)
- Contains 24–26% Ni, 19–21% Cr, 6–7% Mo, 0.5–1.5% Cu, and 0.15–0.25% N
- Non-magnetic in solution-annealed condition (no magnetic permeability issues)
- Classified as a nickel alloy under American standards (UNS N08926) due to Ni >20%
- Carbon below 0.020% — ultra-low for maximum weldability and corrosion resistance
- Copper addition specifically improves resistance to reducing acids (H₂SO₄, H₃PO₄)
- Used in FGD, seawater desalination, oil & gas, chemical processing, and nuclear
- Manufacturer ISO 9001:2015 certified — Jiangsu Liangyi Co., Limited, Jiangyin, China (est. 1997)
Dual classification note: Under ASTM/UNS standards, 1.4529 is classified as a nickel alloy (UNS N08926) due to its nickel content exceeding 20%. Under European standards it is classified as a stainless steel (EN 1.4529). Both are correct — the difference reflects classification methodology, not material identity.
International Standard Designations
| Standard Body | Designation |
|---|---|
| EN / DIN (European) | 1.4529 |
| ISO Full Name | X1NiCrMoCuN25-20-7 |
| ASTM / UNS | UNS N08926 |
| Commercial Name | Alloy 926 |
| API 6A | Compliant forgings available |
| NORSOK M-630 | Approved grade |
| EN 10204 | 3.1 / 3.2 certification |
Why "Super" Austenitic? The PREN Threshold
Standard austenitic grades (304, 316L) have a PREN between 18 and 25. The "super austenitic" classification requires PREN >40. 1.4529 achieves a minimum PREN of 42, typically reaching 44–46.
PREN Formula: PREN = %Cr + 3.3 × %Mo + 16 × %N
For typical 1.4529 chemistry (Cr 20%, Mo 6.5%, N 0.20%):PREN = 20 + 21.45 + 3.2 = 44.65
Jiangsu Liangyi Technical Team — ISO 9001:2015 Certified
Jiangsu Liangyi Co., Limited — 27+ years manufacturing open die forgings and seamless rolled rings in super austenitic and nickel alloy grades for 50+ countries. All data verified against EN 10088-3 and EN 10250-4.
Sourcing 1.4529 steel forgings? Jiangsu Liangyi Co., Limited manufactures custom 1.4529 forged parts and seamless rolled rings to EN 10250-4, ASTM A182, and API 6A requirements, with EN 10204 3.1 mill certificates.
Section 02 — Chemical Data
Chemical Composition of 1.4529 Steel (EN 10088-3)
The following composition complies with EN 10088-3. Actual melt analysis may vary slightly by product form and melting route. All values in weight percent.
| Element | Symbol | Min % | Max % | Typical % | Function in Alloy |
|---|---|---|---|---|---|
| Carbon | C | — | 0.020 | ≤0.015 | Kept ultra-low: prevents carbide precipitation at grain boundaries; maximizes weldability and corrosion resistance |
| Silicon | Si | — | 0.50 | 0.3 | Deoxidant during melting and casting |
| Manganese | Mn | — | 1.00 | 0.8 | Austenite stabilizer; assists in nitrogen solubility |
| Chromium | Cr | 19.0 | 21.0 | 20.0 | Forms passive oxide film; foundation of corrosion resistance; contributes 20 points to PREN |
| Nickel | Ni | 24.0 | 26.0 | 25.0 | Stabilizes austenite; improves SCC resistance; enhances corrosion resistance in reducing acids |
| Molybdenum | Mo | 6.0 | 7.0 | 6.5 | Primary pitting resistance driver (PREN contribution = 3.3 × %Mo = 21.45); fortifies passive film in chloride environments |
| Copper | Cu | 0.50 | 1.50 | 1.0 | Specific enhancement for reducing acid resistance (H₂SO₄, H₃PO₄); key differentiator vs. 254 SMO (1.4547) |
| Nitrogen | N | 0.15 | 0.25 | 0.20 | Boosts PREN by 16 × %N = 3.2; increases tensile strength by solid-solution hardening; stabilizes austenite; improves pitting resistance |
| Phosphorus | P | — | 0.030 | — | Controlled; excess degrades toughness |
| Sulfur | S | — | 0.010 | — | Minimized: MnS inclusions are preferential pitting initiation sites |
Copper addition is intentional and a key differentiator. The 0.5–1.5% Cu in 1.4529 specifically enhances resistance to reducing acids — particularly sulfuric and phosphoric acid — which differentiates 1.4529 from 254 SMO (1.4547). For chemical plants handling H₂SO₄ or H₃PO₄, 1.4529 is often the preferred choice over 254 SMO despite similar PREN values.
Data Sources
- EN 10088-3:2014 — Stainless steels, Part 3: Technical delivery conditions for semi-finished products, bars, rods, wire, sections and bright products of corrosion resisting steels for general purposes. CEN.
- EN 10250-4:2000 — Open die steel forgings for general engineering purposes, Part 4: Stainless steels. CEN.
- ASTM A182/A182M — Standard Specification for Forged or Rolled Alloy and Stainless Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service. ASTM International.
Section 03 — Engineering Data
Mechanical and Physical Properties of 1.4529
Mechanical Properties — Solution Annealed, Room Temperature
| Property | Min. Value | Unit |
|---|---|---|
| Tensile Strength (UTS) | 650 | MPa |
| Yield Strength (Rp0.2) | 295 | MPa |
| Elongation (A₅) | 35 | % |
| Impact Energy (KV, 0°C) | 100 | J |
| Hardness (Brinell) | ≤250 | HBW |
Physical Properties (Approximate, 20°C)
| Property | Value |
|---|---|
| Density | ~8.0 g/cm³ |
| Elastic Modulus | ~195 GPa |
| Thermal Conductivity | ~12 W/(m·K) |
| Thermal Expansion (20–100°C) | ~15.5 ×10⁻⁶ /K |
| Electrical Resistivity | ~1.00 μΩ·m |
| Magnetic Permeability | Non-magnetic |
PREN Comparison — 1.4529 vs. Common Stainless Steel Grades
1.4529 achieves a PREN greater than 42 — surpassing 316L (PREN ~24), SAF 2507 duplex (~42), and 254 SMO (~40). Higher PREN equals greater resistance to pitting corrosion in chloride environments.
316L
24
317LMN
32
SAF 2507
38
254 SMO
40
1.4529 ★
>42
Corrosion Resistance Coverage
Pitting Corrosion
Crevice Corrosion
Stress Corrosion Cracking
Intergranular Corrosion
High-Chloride (19,000+ ppm)
Sulfuric Acid H₂SO₄
Phosphoric Acid H₃PO₄
Seawater Service
FGD Flue Gas
Reducing Acids
The non-magnetic nature of 1.4529 makes it suitable wherever electromagnetic interference is unacceptable — subsea sensors, MRI-adjacent equipment, defense instrumentation, downhole tools, and non-magnetic structural components.
Section 04 — Manufacturing
The Forging Process for 1.4529
Forging 1.4529 demands specialist expertise. Its high alloy content and rapid work-hardening make it significantly more challenging than standard stainless grades. Forged parts deliver superior mechanical integrity over castings or machined bar stock.
01
Steel Melting and Refining
Produced via AOD (Argon Oxygen Decarburization) or VOD (Vacuum Oxygen Decarburization), followed by ESR (Electroslag Remelting) for nuclear and critical applications requiring superior cleanliness and microstructural homogeneity.
02
Billet Heating
Heated uniformly to 1,150–1,180°C. Uniform through-temperature is critical — localized cold spots cause hot tearing in this highly alloyed material.
03
Hot Forging or Ring Rolling
Forging is performed within 1,180°C to 950°C. Open die forging produces shafts, discs, and custom profiles. Ring rolling produces seamless rings for flanges and pressure vessels.
04
Rapid Cooling
Rapid cooling by air or water quenching after forging prevents sigma phase or intermetallic precipitation which would degrade corrosion resistance.
05
Solution Annealing Heat Treatment
Final heat treatment at approximately 1,100–1,150°C followed by rapid water quenching. Restores the fully austenitic microstructure and maximizes corrosion performance per EN 10250-4.
06
NDT and Certification
100% ultrasonic testing (UT), dimensional inspection, and material verification. EN 10204 3.1 certificates issued as standard; EN 10204 3.2 available on request. Third-party inspection by TÜV, Bureau Veritas, or Lloyd's accommodated on request.
07
Precision Machining
The high work-hardening rate requires sharp carbide tooling at controlled feeds and speeds. In-house CNC machining to customer drawings is standard at qualified 1.4529 forging manufacturers.
Applicable Forging Standards for 1.4529
| Standard | Scope |
|---|---|
| EN 10250-4 | Open die steel forgings — stainless steels |
| EN 10088-3 | Stainless steels semi-finished products and bars |
| EN 10272 | Stainless steel bars for pressure purposes |
| ASTM A182 | Forged fittings and flanges for high-temperature service |
| API 6A | Wellhead and Christmas tree equipment |
| NORSOK M-630 | Norwegian oil and gas material data sheets |
| EN 10204 3.1/3.2 | Material inspection and test certificates |
All product forms listed above are available as fully certified X1NiCrMoCuN25-20-7 open die forgings from Jiangsu Liangyi , produced to customer drawings with lead times from 8 to 20 weeks.
Welding 1.4529: Key Guidance
Hot cracking risk: Fully austenitic weld structure increases solidification cracking sensitivity. Use duplex filler metal (e.g. EN 1.4462) or nickel-alloy fillers. Avoid preheating. Keep interpass temperature below 150°C. TIG, MIG, and SAW processes are all applicable.
Available 1.4529 Forged Product Forms
Flanges (WN / SO / BL / RTJ)
Seamless Rolled Rings
Discs and Blanks
Valve Bodies
Pump Shafts
Impellers
Sleeves and Bushings
Pressure Vessel Heads
Custom Open-Die Profiles
Section 05 — End Uses
Industry Applications of 1.4529 Steel
1.4529 (X1NiCrMoCuN25-20-7) is used in nine primary industries: chemical processing, seawater desalination, flue gas desulfurization (FGD), oil and gas, pulp and paper, nuclear power, cryogenic equipment, aerospace, and water treatment — wherever conventional stainless steels fail due to high chloride concentrations, reducing acids, or combined corrosive conditions.
Seawater Desalination
Pump shafts, impellers, valve bodies, and heat exchanger tube sheets. Seawater contains approximately 19,000 ppm chloride ions — requiring PREN greater than 40 for reliable long-term service without pitting failure.
Flue Gas Desulfurization (FGD)
FGD absorber towers, ductwork, spray nozzles, and agitators in coal power plant emissions control. Combined chloride, sulfuric acid, and elevated temperature make 1.4529 the industry-preferred material for FGD wetted components.
Oil and Gas
Subsea valves, wellhead components, manifolds, and offshore process equipment. Meets NORSOK M-630 and API 6A requirements for sour service and high-chloride production environments.
Pulp and Paper
Bleaching equipment, digesters, and piping in contact with chlorine compounds and acidic pulping liquors. Outperforms 316L and standard duplex grades in chlorine dioxide bleaching circuits.
Nuclear and Power Generation
Reactor coolant piping, heat exchangers, and structural components requiring 100% NDT qualification. Material's corrosion resistance and weldability meet stringent demanding nuclear project material and inspection requirements.
Cryogenic Equipment
Fully austenitic microstructure retains excellent toughness at cryogenic temperatures. Reliable impact strength down to −196°C for LNG storage, industrial gas processing, and cryogenic pressure vessels.
Aerospace
Aircraft components, bushings, and fasteners requiring combined corrosion resistance, high strength, and non-magnetic properties. High nitrogen content provides strength without cold working.
Water Treatment
Pumps, valve bodies, and structural components in municipal and industrial water treatment handling aggressive feed waters, chemical dosing streams, and high-salinity brine recovery circuits.
Section 06 — Material Selection Guide
1.4529 vs. Alternative Materials: Full Comparison
Selecting the right alloy requires balancing corrosion performance requirements, mechanical properties, weldability, cost, and supply availability. The following table compares 1.4529 against the most commonly evaluated alternatives.
| Property | 1.4529 (Alloy 926) | 316L | 254 SMO (1.4547) | SAF 2507 (Duplex) | Alloy 625 (Ni-base) |
|---|---|---|---|---|---|
| PREN | >42 | ~24 | ~40 | ~42 | N/A (Ni alloy) |
| Ni Content | ~25% | ~12% | ~18% | ~7% | ~62% |
| Mo Content | ~6.5% | ~2.2% | ~6% | ~4% | ~9% |
| Cu Addition | Yes (~1%) | No | Yes (~0.7%) | No | No |
| Reducing Acid Resistance | Excellent | Fair | Good | Fair | Superior |
| SCC Resistance (Cl⁻) | Excellent | Poor | Excellent | Good | Superior |
| Non-Magnetic | Yes | Yes | Yes | Slightly magnetic | Yes |
| Cryogenic Toughness | Excellent | Excellent | Excellent | Good | Excellent |
| Weldability | Good (care required) | Excellent | Good | Good | Excellent |
| Relative Cost | High | Low | High | High | Very High |
Note: 1.4529 and 254 SMO have similar PREN values, but 1.4529's copper addition provides a meaningful advantage in reducing acid service. 1.4529 can often replace Alloy 625 in chloride-dominated applications at substantially lower cost, making it the preferred material selection when extreme nickel content is not strictly required.
Section 07 — Common Questions
Frequently Asked Questions About 1.4529 Steel
Answers to the most common technical and procurement questions about 1.4529 (X1NiCrMoCuN25-20-7, Alloy 926, UNS N08926) from engineers and buyers worldwide.
Is 1.4529 the same as Alloy 926 and UNS N08926?
Yes. 1.4529 is the European material number (Werkstoffnummer) per the EN system. Alloy 926 is the global commercial name. X1NiCrMoCuN25-20-7 is the ISO/EN compositional designation. UNS N08926 is the American designation per ASTM. All four refer to identical chemistry and properties.
What is the PREN of 1.4529 steel?
1.4529 achieves a PREN consistently greater than 42, typically in the range of 44–46. PREN is calculated as: %Cr + 3.3 × %Mo + 16 × %N. For typical 1.4529 chemistry (Cr 20%, Mo 6.5%, N 0.20%), PREN = 20 + 21.45 + 3.2 = 44.65. A PREN above 40 qualifies a steel as super austenitic. By comparison, 316L achieves approximately PREN 24.
What is the maximum operating temperature for 1.4529?
Avoid 600–900°C where sigma phase precipitation occurs and significantly degrades both mechanical properties and corrosion resistance. Solution annealing at 1,100–1,150°C followed by water quenching dissolves sigma phase. For structural applications above 300°C, consult manufacturer-supplied certified data for the specific heat of material.
Can 1.4529 be used in seawater without coating?
Yes. 1.4529 is engineered for uncoated seawater service. Its PREN greater than 42 and approximately 25% nickel content provide excellent resistance to pitting and crevice corrosion in seawater at approximately 19,000 ppm chloride ions — including stagnant conditions that rapidly corrode 316L stainless steel.
What certifications should 1.4529 forging parts carry?
At minimum: EN 10204 3.1 mill test certificates covering chemical composition, mechanical properties, and heat treatment records. Critical applications require EN 10204 3.2 (third-party witnessed). Additional certifications may include NACE MR0175/ISO 15156 material compliance (upon request), production to API 6A requirements (upon request), third-party inspection is available on request. NDT reports (UT, PT/MT) should accompany each forging lot.
How does 1.4529 compare to 316L in chloride service?
316L (PREN ~24) pits at chloride concentrations of a few hundred ppm at elevated temperatures and stress-corrodes above approximately 60°C. 1.4529 (PREN >42) resists pitting and SCC in seawater exceeding 19,000 ppm chloride ions — service that would fail 316L components within months.
What is the typical lead time for 1.4529 forged parts?
Simple geometries (discs, rings) from available billet: 8–12 weeks including forging, heat treatment, and basic NDT. Complex custom forgings with CNC machining: 14–20 weeks. Nuclear or third-party witness applications may require additional time. Submit complete drawings and technical specifications early to confirm project-specific schedules.
Source 1.4529 Forged Parts
Request 1.4529 Forging Parts from a Certified Manufacturer
Jiangsu Liangyi Co., Limited specializes in 1.4529 / X1NiCrMoCuN25-20-7 open die forging parts and seamless rolled rings — 27+ years manufacturing experience, 50+ countries served. Full-service supply chain: steel melting → forging → heat treatment → precision machining → 100% NDT → EN 10204 3.1 mill certificates (3.2 available on request).
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