Super-Austenitic Stainless Steel · 6Mo · Corrosion Resistant Alloy

Incoloy 926 / UNS N08926 / 1.4529 Forging Parts

🇺🇸 USA

UNS N08926
ASTM B564 · B462

🇪🇺 Europe

1.4529
X1NiCrMoCuN25-20-7

🇩🇪 Germany

DIN 17744
Cronifer® 1925 hMo

🇨🇳 China

NS1402 (similar)
00Cr20Ni25Mo7Cu

📜 Trade names

Incoloy® 25-6MO
Inco® 25-6HN

Published: 12 May 2022 · Last updated: 17 August 2026 · Technically reviewed by the Jiangyin Jiangnan Metal Co., Ltd. Metallurgical Engineering Team, Jiangyin, Jiangsu, China

Incoloy 926 is a super-austenitic stainless steel containing nominally 25% nickel, 20% chromium and 6.5% molybdenum with deliberate copper and nitrogen additions, designated UNS N08926 and EN 1.4529 (X1NiCrMoCuN25-20-7). It belongs to the 6Mo family of chloride-resistant alloys. Its pitting resistance equivalent number (PREN) is approximately 45, which gives a critical pitting temperature of roughly 60–75 °C in the standard ferric chloride test, against about 15–20 °C for 316L. The grade is specified where 316L and 904L pit or crack but a full nickel-base alloy such as Hastelloy C-276 is not economically justified: seawater and brackish-water systems, flue gas desulphurisation scrubbers, pulp and paper bleach plants, desalination plant, phosphoric and sulphuric acid service, and offshore produced-water handling.

Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, manufactures Incoloy 926 in forged form to customer drawings: seamless rolled rings to 2,500 mm outside diameter, forged discs to 1,800 mm diameter, shafts to 8 m length, tube sheets to 2,000 mm, bars from Ø25 mm to Ø500 mm, and single pieces to 8,000 kg. Material is melted by EAF + VOD + ESR, solution annealed at 1100–1150 °C and water quenched, and supplied with EN 10204 3.1 certification as standard. Quotations are issued within 24 hours of receiving a drawing at sales@steelforgepieces.com.

What is Incoloy 926 (UNS N08926)?

Incoloy 926 is a fully austenitic, iron-nickel-chromium-molybdenum stainless steel with nominally 25% nickel, 20% chromium, 6.5% molybdenum, 1% copper and 0.2% nitrogen, balance iron. It is classified as a super-austenitic or 6Mo stainless steel, and because its nickel content exceeds the UNS limit for a stainless steel it carries a nickel-alloy UNS number, N08926, and is bought under nickel-alloy product specifications such as ASTM B564 and ASTM B462 rather than the A182 / A240 stainless series.

Three deliberate alloying decisions explain everything the grade does in service:

• 6–7% molybdenum is what raises the pitting and crevice corrosion resistance far above 316L. Molybdenum stabilises the passive film in the presence of chloride and slows the local acidification inside a pit or crevice once initiation has occurred.
• 24–26% nickel stabilises the austenite so that the high molybdenum and nitrogen can be carried without forming ferrite or excessive intermetallic phase, and it lifts resistance to chloride stress corrosion cracking, which is the failure mode that limits 316L in hot chloride service.
• 0.15–0.25% nitrogen plus 0.5–1.5% copper are the two additions that distinguish the grade from a plain 6Mo austenitic. Nitrogen contributes strongly to pitting resistance (weighted 16× in the PREN formula) and raises yield strength without carbon. Copper improves behaviour in sulphuric and phosphoric acid, which is why the grade appears in phosphate fertiliser plant and pickling-line duty where AL-6XN, containing no copper, is less favoured.

The grade is not age-hardenable. It is supplied and used in the single condition that matters, solution annealed and water quenched, and its strength cannot be raised by heat treatment. This is the most common technical misunderstanding about the alloy, and it comes from confusion with Incoloy 925 (UNS N09925), which is a genuinely age-hardenable grade with a similar number. See 926 versus 925 below.

Incoloy 926 forgings: supplier quick facts

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China, producing alloy 926 (UNS N08926 / EN 1.4529) forged rings, seamless rolled rings, flanges, shafts, discs, sleeves, bushings, tube sheets, valve components and bars to customer drawings.

What Forged Products Are Available in Incoloy 926?

Jiangyin Jiangnan Metal produces alloy 926 through three routes, chosen by geometry and quantity. Open-die forging covers shafts, blocks, tube sheets and large discs, where single-piece size matters more than repeatability. Seamless ring rolling produces rings from 200 mm to 2,500 mm outside diameter and is the normal route for flange blanks, pump and valve housings, and pressure-retaining rings. Near-net-shape forging is used where a die profile removes 30–50% of the rough machining.

The economics of this grade push harder toward near-net-shape than they do for a stainless steel. Alloy 926 costs roughly three times 316L per kilogram and machines at perhaps a third of the rate, so metal removed in the machine shop is expensive twice over. On repeat parts it is usually worth paying for a closer forged profile.

What Are the Equivalent Designations of Incoloy 926?

Engineers reach this grade through at least a dozen names, depending on the standards body, the producer and the decade the drawing was written. Every designation in the table below refers to the same nominal Fe-25Ni-20Cr-6.5Mo-Cu-N chemistry. Jiangyin Jiangnan Metal Co., Ltd. accepts purchase orders under all of them and cross-lists the equivalents on the material certificate.

Incoloy 926 Is Not Incoloy 925, 254 SMO, AL-6XN or F44

More RFQs go wrong on this grade through mistaken identity than through anything technical. Four alloys are routinely confused with it, and in two of the four cases the substitution changes the metallurgy completely.

What Is the Chemical Composition of Incoloy 926?

Incoloy 926 / UNS N08926 contains 19.0–21.0% chromium, 24.0–26.0% nickel, 6.0–7.0% molybdenum, 0.5–1.5% copper and 0.15–0.25% nitrogen, with carbon held to 0.020% maximum and the balance iron (nominally 43–47%). The composition below reflects ASTM B564 / B625 / B649 practice for the grade, which is also the EN 1.4529 range.

Where inside the range matters. Two heats can both certify to N08926 and behave measurably differently. A heat at 6.0% Mo and 0.15% N has a PREN of about 42; a heat at 7.0% Mo and 0.25% N reaches about 48. That six-point spread is the difference between marginal and comfortable in hot chlorinated seawater. Where the service is severe, specify a minimum PREN of 44 on the purchase order and require the calculated value on the certificate. We will select the heat accordingly, and the surcharge, if any, is small compared with a replacement outage.

Our melting practice. Jiangyin Jiangnan Metal Co., Ltd. melts alloy 926 by EAF + VOD followed by ESR (electroslag remelting). VOD gives the low carbon and controlled nitrogen the grade needs; ESR refines the inclusion population, which matters here because sulphide and oxide inclusions are exactly where chloride pits start. VIM + VAR double-vacuum stock can be sourced for critical subsea and nuclear-adjacent work; specify it at RFQ stage since it changes price and lead time. Both ladle and product analysis appear on the EN 10204 certificate.

Corrosion Resistance of Incoloy 926: PREN, CPT and CCT

The PREN of Incoloy 926 is approximately 45 (calculated as %Cr + 3.3 × %Mo + 16 × %N from the nominal 20Cr-6.5Mo-0.20N composition), giving a range of roughly 42–48 across the permitted chemistry. In the standard ferric chloride immersion test to ASTM G48 Method A, this translates to a critical pitting temperature of about 60–75 °C and a critical crevice temperature roughly 20–30 °C lower, typically 35–50 °C.

Those two numbers, not the PREN, are what a design should be checked against. PREN is a linear ranking index derived from chemistry; it takes no account of crevice geometry, surface finish, heat tint, welding, or the oxidising power of the environment. It is useful for choosing which alloys to test and useless as a design criterion on its own.

Other corrosion mechanisms

• Chloride stress corrosion cracking (SCC). The 25% nickel content puts this grade well clear of the composition band where austenitic stainless steels are most susceptible. In practice it resists cracking in hot chloride waters where 316L fails. It is not immune: concentrated chlorides above roughly 150 °C with sustained tensile stress can still crack it.
• Intergranular corrosion. With carbon at 0.020% max, the alloy is resistant to sensitisation in normal welding. That protection disappears if the material is held in the 600–1000 °C range long enough for intermetallic phase to form. See solution annealing and sigma phase. ASTM G28 Method A is the relevant acceptance test.
• Sulphuric acid. The copper addition gives useful resistance in dilute (below roughly 10%) and in concentrated (above roughly 85%) acid at moderate temperature. The intermediate concentration range remains aggressive, as it is for every stainless steel.
• Hydrochloric and hydrofluoric acid. Not a candidate. These require nickel-molybdenum alloys such as Hastelloy B-2 / B-3 or C-276.
• Galvanic coupling. Alloy 926 is a noble, passive material. Coupling it to carbon steel, cast iron or copper alloys in seawater will drive rapid attack of the less noble metal. Insulate the joint or accept the sacrificial loss deliberately.

Where Can Incoloy 926 Be Used? Media and Seawater Service

Alloy 926 is designed for chloride-bearing water and for oxidising acid service at temperatures where 316L and 904L fail. The table below summarises typical suitability. It is a starting point for shortlisting, not a substitute for testing in the actual medium.

What Are the Physical Properties of Incoloy 926?

Data notes. Density, melting range, modulus and the room-temperature expansion coefficient are well established for this chemistry and can be used directly. Values marked "typical" or "≈" vary with heat, section size and measurement method, and should be treated as indicative for screening. Where a physical value is contractually important, state it on the purchase order and we will report the measured result on the certificate.

What Are the Mechanical Properties of Incoloy 926?

In the solution-annealed condition, ASTM B564 requires a minimum tensile strength of 650 MPa (94 ksi), a minimum 0.2% yield strength of 295 MPa (43 ksi), a minimum elongation of 35% and a hardness not exceeding 100 HRB. Typical forged values run comfortably above the minima. The nitrogen content is what gives this grade a yield strength roughly 40% higher than 316L in the same condition, without any carbon penalty.

How Is Incoloy 926 Heat Treated? Solution Annealing and Sigma Phase

Incoloy 926 has exactly one delivery heat treatment: solution anneal at 1100–1150 °C, hold, then quench in water as rapidly as the section allows. There is no ageing, no tempering and no hardening transformation. The purpose of the anneal is to dissolve carbides and intermetallic phases into solid solution, and the purpose of the quench is to get through the precipitation range fast enough that they do not come back.

Why the quench rate governs the whole job

With 6.5% molybdenum, this alloy sits close to the stability limit of single-phase austenite. Hold it anywhere between roughly 600 °C and 1,000 °C and chromium- and molybdenum-rich intermetallics (sigma, chi and Laves phase) precipitate at grain boundaries. Two things happen at once: the boundaries embrittle, and the region beside them is stripped of the molybdenum the alloy was bought for. A heavy forging that is allowed to cool slowly from the annealing temperature can therefore certify to the correct chemistry and still fail a G48 pitting test, because the chemistry is right while the microstructure is not.

This is the single most important practical difference between forging alloy 926 and forging a conventional stainless steel, and it drives the way we handle heavy sections: adequate press capacity so pieces come out of the die hot rather than being worked cold, minimum handling time between furnace and quench tank, and quench-water volume and agitation sized for the section. On sections above roughly 200 mm the achievable cooling rate at mid-thickness becomes the limiting factor on what can be certified. Where that limit is reached, the honest answer is a thinner design, a welded fabrication, or a different alloy, not a certificate with an optimistic quench record on it.

Incoloy 926 vs 316L, 904L, 254 SMO, AL-6XN, Duplex 2507 and C-276

Alloy selection in chloride service is a chain of thresholds: each grade buys a step up in critical crevice temperature, and each step costs money. The table below is the practical selection chart.

The three comparisons that actually come up

Alloy 926 versus 254 SMO. Pitting resistance is effectively the same. The differences are the nickel content (25% against 18%), which gives 926 more margin against chloride stress corrosion cracking, and the specification family: 926 is a nickel alloy bought under ASTM B564 / B462, while 254 SMO is a stainless steel bought under A182 / A240 as F44. If your piping class calls up F44, ordering N08926 is a deviation even though the material is at least as good. Settle that on paper before the ingot is cast.

Alloy 926 versus AL-6XN. Very close in chloride service, with AL-6XN a shade ahead on paper thanks to slightly higher chromium and nitrogen. The separating factor is copper: 926 has 0.5–1.5%, AL-6XN has none. In sulphuric or wet-process phosphoric acid, that copper is worth having. In pure chloride pitting duty, either will do and availability usually decides.

Alloy 926 versus duplex 2507. Not really the same conversation. Duplex 2507 has nearly twice the yield strength, so it wins wherever wall thickness or weight drives cost, and it is cheaper. But it is limited to about 300 °C by 475 °C embrittlement, it is harder to weld well in thick sections, and its performance in acids is weaker. Alloy 926 wins on acids, on temperature range, on cryogenic toughness and on weldability in heavy forged sections.

How Do You Forge, Machine and Weld Incoloy 926?

Forging

Alloy 926 is hot worked from 1,150–1,200 °C with the finishing temperature held above 950 °C. The working window is narrower than for 316L at both ends. Above 1,200 °C there is a risk of incipient melting at interdendritic segregation, particularly in ESR ingot that has not been homogenised; below 950 °C the flow stress climbs steeply and the piece will crack rather than flow.

Two practical consequences follow. First, this alloy needs press capacity, not patience: at equal temperature its flow stress is well above that of carbon or stainless steel, so a press that is marginal for the section will simply not deform the middle of the piece, leaving an unworked as-cast core that no amount of heat treatment will repair. We target a minimum 4:1 forging reduction from the ingot for full recrystallisation. Second, reheats must be planned rather than improvised: every pass that runs cold at the extremities has to be reheated before the next.

For rings, the pierced blank is expanded on a radial-axial mill so grain flow follows the circumference. On flange blanks and pressure-housing rings this matters beyond the usual argument about grain flow, because a rolled ring has no end grain exposed on the sealing face, and exposed end grain is where chloride pitting starts preferentially.

Machining

Machining behaviour is that of a heavily alloyed austenitic: gummy, strongly work-hardening, abrasive on the tool edge and poor at conducting heat away from it. Machinability is roughly 30–40% of 304 and perhaps a fifth of free-machining carbon steel. The rules are the familiar super-austenitic ones, applied strictly:

• Sharp, positive-rake carbide inserts; change at the first sign of edge rounding rather than running them out.
• Turning at roughly 15–30 m/min with coated carbide, feed 0.20–0.40 mm/rev. Slow speed and heavy feed, never the reverse.
• Never dwell in the cut. A tool that stops feeding while in contact glazes and work-hardens a layer that the next pass has to fight through.
• Rigid setups, minimum overhang, generous flood coolant delivered at the edge.
• Peck-drill and clear chips; drilling is where this alloy defeats most shops.
• Leave 3–5 mm of stock on corrosion-critical surfaces so that any work-hardened or contaminated layer is removed at the finish pass.
• Keep carbon-steel contamination away from the surface: separate tooling, no steel brushes, no steel slings on finished faces. Iron smeared on a passive surface is a pit initiation site.

Welding

Alloy 926 welds readily by GTAW, GMAW, SMAW, plasma and submerged arc. There is one rule that governs corrosion performance in the weld, and it is not obvious: do not weld it autogenously or with matching filler for corrosion service. When the alloy solidifies, molybdenum segregates to the interdendritic regions, leaving dendrite cores depleted. A weld of matching composition therefore has patches of lower effective PREN than the parent metal, and those patches pit first.

The standard remedy is an over-alloyed nickel-base filler:

• ERNiCrMo-3 / AWS A5.14 (alloy 625 type): the usual choice for general chloride service.
• ERNiCrMo-4 (C-276 type) or ERNiCrMo-13 (alloy 59 type): where the service is at the limit of the grade, or where the weld will see acid as well as chloride.
• Low heat input, interpass temperature below 150 °C, no preheat, stringer beads rather than wide weave.
• Full-penetration joints with back purge. Crevices from partial-penetration welds are a bigger risk to this alloy than the weld metal itself.
• Remove all heat tint by pickling or mechanical cleaning, then passivate. Heat tint is the most common cause of premature pitting in 6Mo installations, and it is entirely avoidable.
• No PWHT: any hold in the 600–1,000 °C range precipitates intermetallics. If a full re-solution anneal and quench is not possible, weld and leave it as welded.

Where Is Incoloy 926 Used?

Every application below rests on the same proposition: the medium contains chloride, the temperature is above what 316L or 904L will tolerate, and a full nickel-base alloy would cost more than the duty justifies.

Incoloy 926 Production Capability at Jiangyin Jiangnan Metal

Jiangyin Jiangnan Metal Co., Ltd. operates an open-die forging and ring-rolling plant in Jiangyin, Jiangsu Province, China, employing approximately 460 people including 9 senior engineers and 32 intermediate engineers. Alloy 926 is produced on the same equipment as our nickel-alloy and precipitation-hardening stainless range, with dedicated handling to avoid iron contamination of finished surfaces.

Standards, Testing and Certification for Incoloy 926 Forgings

Alloy 926 orders at Jiangyin Jiangnan Metal Co., Ltd. are produced and certified against the specifications below. For forged rings, flanges and shafts the normal combination is ASTM B564 or ASTM B462 for the product, EN 10204 3.1 for the inspection document, and EN 10228-4 for ultrasonic examination.

• UNS N08926
• EN 1.4529
• X1NiCrMoCuN25-20-7
• ASTM B564
• ASTM B462
• ASTM B649
• ASTM B625
• ASTM B677
• EN 10222-5
• EN 10088-3
• EN 10028-7
• EN 10204 3.1 / 3.2
• EN 10228-4 (UT)
• ASTM A388 (UT)
• ASTM E2375 (UT)
• ASTM E165 (PT)
• EN ISO 3452-1 (PT)
• ASTM G48 A / C (CPT)
• ASTM G28 A (IGA)
• ASTM A262 E
• ASTM A380 / A967 (passivation)
• ASME BPVC II-D / VIII-1
• ISO 15156-3 / NACE MR0175
• ISO 9001:2015

What appears on the certificate

• Heat number, with full ladle analysis and product analysis
• Calculated PREN for the delivered heat, from the reported Cr, Mo and N
• Melting route (EAF + VOD + ESR, or VIM + VAR where specified)
• Mechanical results (tensile, 0.2% yield, elongation, reduction of area, hardness) on coupons from the delivered heat, with impact results where ordered
• Heat-treatment record: solution-anneal temperature, hold time, furnace chart reference, transfer time and quench medium
• Ultrasonic examination report to the ordered standard and acceptance class
• Liquid penetrant report where ordered
• Corrosion test results where ordered: ASTM G48 Method A or C critical pitting temperature, ASTM G28 Method A mass loss
• Dimensional inspection report and marking record
• Cross-listed equivalents: UNS N08926 / EN 1.4529 / X1NiCrMoCuN25-20-7
• Statement of pickling and passivation treatment

Quality gates

Every alloy 926 order passes six mandatory hold points at which production cannot continue without QA release: incoming chemistry verification against the ordered PREN minimum, forging temperature and reduction compliance, post-forging ultrasonic examination, heat-treatment chart and quench-record approval, mechanical and corrosion test acceptance, and final NDE plus dimensional inspection. Customer-witnessed hold points are added at no charge. Any out-of-specification finding raises a formal non-conformance report within 24 hours, with root-cause analysis inside five working days and the proposed disposition sent for approval before any rework.

How to Specify an Incoloy 926 Forging Order

This grade carries two specification decisions that most alloys do not: the identity of the alloy has to be pinned down beyond the number 926, and the heat-treatment and quench condition has to be stated explicitly, because that is what determines whether the corrosion resistance you are paying for actually arrives. The eight steps below remove the ambiguity that causes most disputes.

Recommended drawing callout

Top 10 Mistakes When Ordering Incoloy 926 Forgings

1. Writing "926" and meaning 925, or the reverse. N08926 is a corrosion alloy that cannot be hardened; N09925 is an age-hardenable strength alloy with less than half the molybdenum. Confirm which property the design needs before ordering.
2. Accepting a slow-cooled heavy section. Correct chemistry plus a slow cool from the annealing temperature equals intermetallic precipitation and lost corrosion resistance. Require the quench record, and for heavy sections require a G48 test on a coupon from the actual piece.
3. Specifying a stress relief. Every temperature normally used to stress-relieve steel sits inside the precipitation range for this alloy. If distortion must be controlled, the answer is a full re-solution anneal and quench, not a low-temperature hold.
4. Copying "UT per EN 10228-3" from a steel template. Austenitic forgings are examined to EN 10228-4. Specifying the wrong part produces either a meaningless report or an argument at inspection.
5. Requiring magnetic particle inspection. The alloy is non-magnetic; MPI cannot work. Use liquid penetrant.
6. Ordering chemistry without a PREN floor. The permitted range spans PREN 42 to 48. In severe chloride service, specify minimum PREN 44 and require the calculated figure on the certificate.
7. Leaving heat tint on welds. The commonest cause of early pitting in 6Mo installations. Specify pickling and passivation, and inspect for it.
8. Welding with matching filler for corrosion service. Molybdenum segregation leaves depleted dendrite cores. Use an over-alloyed nickel-base filler such as ERNiCrMo-3 or ERNiCrMo-4.
9. Substituting 254 SMO, AL-6XN or 904L without written approval. The first two are close; 904L is not close at all. Where the piping class says F44 (S31254), N08926 is a deviation even though it is at least as corrosion resistant.
10. Ignoring iron contamination in handling and machining. Steel slings, steel brushes and shared tooling smear iron onto a passive surface and start pits. Specify dedicated tooling and non-metallic slings for finished faces.

Glossary

Incoloy 926 / alloy 926

Super-austenitic stainless steel of nominally 25% Ni, 20% Cr, 6.5% Mo with 1% Cu and 0.2% N, balance iron. UNS N08926, EN 1.4529, X1NiCrMoCuN25-20-7.

Super-austenitic stainless steel

A fully austenitic stainless steel alloyed beyond the conventional 300-series limits, typically above 4% molybdenum with high nickel and nitrogen, to resist chloride pitting, crevice corrosion and stress corrosion cracking.

6Mo alloy

Shop shorthand for the family of super-austenitic grades containing approximately 6% molybdenum: N08926, S31254 (254 SMO) and N08367 (AL-6XN).

PREN

Pitting resistance equivalent number, %Cr + 3.3 × %Mo + 16 × %N. A linear ranking index for chloride pitting resistance, approximately 45 for N08926. Not a design criterion.

CPT

Critical pitting temperature. The lowest temperature at which stable pitting occurs in a defined test solution, commonly 6% ferric chloride per ASTM G48 Method A. Roughly 60–75 °C for alloy 926.

CCT

Critical crevice temperature. The same threshold measured with a crevice former attached. Always lower than CPT, and the number that governs gasketed and deposit-covered surfaces.

Chloride stress corrosion cracking

Cracking under the combination of tensile stress, chloride and temperature. The failure mode that limits 316L in hot chloride service, and the reason for the 25% nickel content in this grade.

Sigma, chi and Laves phase

Hard, Cr- and Mo-rich intermetallic phases that precipitate when highly alloyed austenitic steels are held in roughly the 600–1000 °C range. They embrittle grain boundaries and locally strip the molybdenum that provides corrosion resistance.

Solution annealing

Heating to 1100–1150 °C to dissolve carbides and intermetallics, then quenching rapidly in water to retain single-phase austenite. The only delivery heat treatment for this grade.

Heat tint

The oxide film that forms on a weld and its heat-affected zone. It is chromium-depleted underneath and drops the effective critical pitting temperature by 20–30 °C until it is pickled or ground away.

Passivation

Chemical treatment, typically nitric-acid based per ASTM A380 / A967, that removes free iron and restores a uniform chromium-rich oxide film after pickling or machining.

Over-alloyed filler

A weld filler richer in molybdenum than the parent metal (ERNiCrMo-3 or ERNiCrMo-4 for this grade), used to compensate for molybdenum segregation in the solidifying weld pool.

Seamless rolled ring

A ring made by piercing a forged billet and expanding it on a radial-axial ring mill, giving continuous circumferential grain flow and no exposed end grain on the sealing face.

EAF + VOD + ESR

Electric arc furnace melting, vacuum oxygen decarburisation for low carbon and controlled nitrogen, then electroslag remelting to refine inclusions and produce clean forging stock.

EN 10204 3.1 / 3.2

Inspection document types. 3.1 is issued by the manufacturer's independent inspection department; 3.2 is countersigned by a third party nominated by the purchaser.

EN 10228-4

The European standard for ultrasonic testing of austenitic and austenitic-ferritic steel forgings. EN 10228-3, frequently specified in error, covers ferritic and martensitic forgings.

ISO 15156-3 / NACE MR0175

The materials standard for H₂S-containing oil and gas service. It lists highly alloyed austenitic stainless steels with environmental and hardness limits that must be read in the edition in force.

Frequently Asked Questions: Incoloy 926 / UNS N08926

Technical References

Chemistry, corrosion, physical-property and heat-treatment data on this page are drawn from the published standards and engineering references below. Test results reported on our material certificates are independent and traceable to calibrated laboratory equipment.

1. ASTM B564, Standard Specification for Nickel Alloy Forgings, ASTM International, West Conshohocken, PA.
2. ASTM B462, Standard Specification for Forged or Rolled UNS N06030, N06022, N08020 … N08926 Alloy Pipe Flanges, Forged Fittings, and Valves and Parts for Corrosive High-Temperature Service, ASTM International.
3. ASTM B625, Standard Specification for UNS N08925, UNS N08031, UNS N08926 and Other Alloy Plate, Sheet, and Strip, ASTM International.
4. ASTM B649, Standard Specification for Ni-Fe-Cr-Mo-Cu Low-Carbon Alloys Bar and Wire, ASTM International.
5. ASTM B677, Standard Specification for UNS N08904, UNS N08925, UNS N08926 Seamless Pipe and Tube, ASTM International.
6. EN 10088-3, Stainless steels — Technical delivery conditions for semi-finished products, bars, rods, wire, sections and bright products, CEN, Brussels.
7. EN 10222-5, Steel forgings for pressure purposes — Martensitic, austenitic and austenitic-ferritic stainless steels, CEN.
8. EN 10028-7, Flat products made of steels for pressure purposes — Stainless steels, CEN.
9. EN 10204:2004, Metallic products — Types of inspection documents, CEN.
10. EN 10228-4, Non-destructive testing of steel forgings — Part 4: Ultrasonic testing of austenitic and austenitic-ferritic stainless steel forgings, CEN.
11. ASTM G48, Standard Test Methods for Pitting and Crevice Corrosion Resistance of Stainless Steels and Related Alloys by Use of Ferric Chloride Solution, ASTM International.
12. ASTM G28, Standard Test Methods for Detecting Susceptibility to Intergranular Attack in Wrought, Nickel-Rich, Chromium-Bearing Alloys, ASTM International.
13. ASTM A262, Standard Practices for Detecting Susceptibility to Intergranular Attack in Austenitic Stainless Steels, ASTM International.
14. ASTM A380 / ASTM A967, Cleaning, Descaling and Passivation of Stainless Steel Parts, Equipment and Systems, ASTM International.
15. ASTM A388 and ASTM E2375, Ultrasonic examination of steel forgings and of wrought products, ASTM International.
16. ASME Boiler and Pressure Vessel Code, Section II Part B (SB-462, SB-564, SB-649) and Section II Part D (allowable stresses), ASME, New York.
17. ISO 15156-3 / NACE MR0175, Petroleum and natural gas industries — Materials for use in H₂S-containing environments in oil and gas production — Part 3: Cracking-resistant CRAs and other alloys, ISO / AMPP.
18. ASM Handbook, Volume 13B: Corrosion: Materials, ASM International, sections on super-austenitic stainless steels and seawater corrosion.
19. ASM Specialty Handbook: Nickel, Cobalt and Their Alloys, J.R. Davis (ed.), ASM International.
20. Sedriks, A.J., Corrosion of Stainless Steels, 2nd edition, John Wiley & Sons. Covers pitting, crevice corrosion and PREN correlations.
21. Outokumpu Corrosion Handbook, published critical pitting and crevice temperature data for austenitic and duplex grades (comparison data).
22. Special Metals Corporation and VDM Metals published technical datasheets for the 25-6MO / 1925 hMo chemistry (comparison data; trademarks of their respective owners).

Standards cited are the revisions known to us at the time of the last page review. For procurement, always reference the revision in force at the contract date. Comparative corrosion figures for competing grades are drawn from the producers' published literature and are shown for ranking purposes only. All trademarks referenced belong to their respective owners.

Related Grades and Forged Products

• Incoloy 925
• Incoloy 945
• Incoloy 825
• Incoloy 800
• Incoloy 800H
• Inconel 625
• Hastelloy C-276
• Hastelloy C-22
• Alloy 59
• Monel 400
• Stainless steel grades
• Forged & rolled rings
• Forged disks
• Forged tubes
• Forged spindles
• Forged nozzles
• Open die forgings