NC22DNb Forgings Open-die forged rings, shafts, flanges, discs and bars in Alloy 625, UNS N06625 / W.Nr. 2.4856

Metallurgy

What NC22DNb is used for

Molybdenum and niobium strengthen NC22DNb in solid solution rather than by ageing. A forging therefore reaches full strength straight out of anneal, stays dimensionally stable through machining and welding, and avoids the distortion problems that come with precipitation-hardened nickel alloys.

Corrosion performance comes from 20 to 23 % chromium together with 8 to 10 % molybdenum. Chromium handles oxidising media. Molybdenum handles reducing media and chloride pitting. In practice the grade is specified after a duplex or super-austenitic stainless steel has failed on chloride stress-corrosion cracking, or where one part has to survive seawater and elevated temperature at the same time.

Service temperature runs from cryogenic to about 982 °C (1800 °F). In the annealed condition the grade is TÜV-approved for pressure vessels between −196 °C and 450 °C. Long exposure above roughly 600 °C can precipitate carbides and intermetallics, so sustained high-temperature duty is normally ordered in the solution-annealed Grade 2 condition.

Chemistry

Chemical composition of NC22DNb

Ranges follow ASTM B564 and B446 for UNS N06625. Tightened internal limits, for example reduced carbon or a controlled Nb/Ta ratio, can be agreed at order and recorded on the mill certificate.

Mechanical

Mechanical properties of NC22DNb forgings

Values are specification minimums, not typical results. Actual heat values appear on the EN 10204 certificate. Heavy sections may be tested at a defined location, so state the sampling requirement on the order.

Physical

Physical properties

Process route

Melting, forging and heat treatment

NC22DNb billet is melted by EAF plus VOD and then remelted by ESR. The remelt keeps sulphur and non-metallic inclusions low enough to pass ultrasonic acceptance on heavy sections, and produces a solidification structure that takes open-die reduction without centreline defects.

Heat treatment options

• Grade 1, annealed at roughly 930 to 1040 °C, rapid cool. The standard condition for wet corrosion and pressure vessel service.
• Grade 2, solution annealed at roughly 1090 to 1200 °C. Coarser grain, better creep and high-temperature strength.
• Solution treatment followed by ageing, carried out in sequence where a customer specification calls for it.
• Stress relief up to approximately 870 °C, with the cycle set by section thickness.

Welding

NC22DNb welds readily by GTAW, GMAW and SMAW, in most cases without post-weld heat treatment. Matching filler is ERNiCrMo-3 wire or ENiCrMo-3 electrode to AWS A5.14 and A5.11. The same consumables are used for dissimilar joints and for corrosion-resistant overlay on carbon and low-alloy steel.

Product forms

NC22DNb forged shapes we produce

Every item below is forged to drawing. Near-net shapes cut machining loss, which matters on a grade at this price.

• NC22DNb Forged RingsSeamless rolled & ring-rolled
• NC22DNb Forged ShaftsStraight, stepped, eccentric
• NC22DNb Forged FlangesWN, blind, custom bore
• NC22DNb Forged Discs & DisksSolid and bored
• NC22DNb Forged Round BarsRough turned or black
• NC22DNb Forged Tube SheetsHeat exchanger service
• NC22DNb Sleeves & BushingsBored and honed
• NC22DNb Forged Pipes & TubesHollow forged, seamless
• NC22DNb Valve ComponentsBodies, stems, seat rings
• NC22DNb Nozzles & BlocksForged to print

Capability

Forging size range

Send the drawing and we will confirm the achievable envelope, the forging reduction ratio and the machining allowance before quoting.

Applications

Where NC22DNb forgings are used

Quality assurance

Testing, inspection and certification

• Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388, at the acceptance class you nominate.
• Chemical analysis by spectrometry on the heat, with PMI on the finished piece on request.
• Mechanical testing covering tensile and hardness, plus Charpy impact where specified, including low-temperature impact testing.
• Dimensional inspection against the approved drawing, with a report issued per piece.
• Surface NDT by liquid penetrant examination to ASTM E165 where required.
• Material certificate to EN 10204 3.1, or EN 10204 3.2 with witness by a third-party body such as TÜV, BV, SGS, Lloyd’s Register or DNV.
• Traceability by heat number, hard-stamped or vibro-etched on each piece.

Standards

Standards and specifications

Not every specification applies to every product form. Name the governing specification on your enquiry and we will confirm compliance before accepting the order.

Ordering

Requesting an NC22DNb quotation

1. Send the drawing, or the rough dimensionsPDF, DWG or STEP. If there is no drawing, give OD, ID, height or length, plus the machining allowance you want us to add.
2. State the governing specification and delivery conditionFor example “ASTM B564 UNS N06625 Grade 1, annealed” or “2.4856 to VdTÜV 499”.
3. Name the certificate level and any NDTEN 10204 3.1 or 3.2; ultrasonic acceptance class to EN 10228-3, SEP 1921 or ASTM A388; PMI; NACE MR0175 hardness.
4. Give quantity and required delivery dateQuantity affects billet cut-up efficiency and therefore price. Tell us if the first article is a prototype.
5. Receive the quotationWe reply with price, forging weight, achievable tolerances, heat treatment route and lead time. Lead time depends on billet availability and the heat treatment cycle, and is confirmed on the quotation rather than estimated.

Email sales@steelforgepieces.com or call +86-189-2135-9659.

Questions

Frequently asked questions about NC22DNb

Last reviewed 22 August 2026 by the technical sales department, Jiangyin Jiangnan Metal Co., Ltd. Property data is compiled from published specifications and is given for guidance only. The governing documents are the purchase order specification and the mill certificate supplied with the goods.