NC23FeA Forgings Open-die forged rings, shafts, flanges, discs and bars in Alloy 601, UNS N06601 / W.Nr. 2.4851

Metallurgy

What NC23FeA is, and why it is specified

NC23FeA is a designation, not a separate alloy. A drawing calling for NC23FeA and one calling for UNS N06601 buy the same chemistry, set by DIN EN 10095, DIN 17742 and ASTM B166. The grade is strengthened in solid solution, so a forging is at full strength as it comes out of the anneal. There is no ageing cycle to schedule and no ageing distortion to machine out afterwards.

The difference from a plain Ni–Cr grade such as Alloy 600 is the aluminium. Chromium on its own forms a chromia scale that protects well but tends to flake off when a part is heated and cooled again and again. Aluminium builds an alumina-rich layer underneath, and the two together stay keyed to the metal through cycling. That behaviour is why the grade turns up in furnace fixtures, incinerator hardware and exhaust parts rather than in room-temperature structural work.

Carbon is the second control, and it works the opposite way round to most corrosion-resistant grades. EN 10095 sets a minimum of 0.03 %, not only a maximum. The carbides are wanted: together with the coarse grain from a high-temperature anneal, they carry the creep-rupture strength. For a forging that puts the heat treatment record on a level with the chemistry. A ring annealed at 1,000 °C will pass a chemical check and still fail in service.

Specify NC23FeA for oxidising and carburising duty between 550 °C and 1,200 °C, particularly where the part is cycled. Look elsewhere if aqueous or acid corrosion is the problem (NC22DNb / Alloy 625), if creep strength above 900 °C governs (Inconel 617, Haynes 230), or if cost per kilogram decides and an iron-base grade will do the job (Alloy 800HT).

Chemistry

Chemical composition of NC23FeA

The two highlighted rows are the controls that give the grade its high-temperature behaviour. Everything below them is a residual limit. Ranges follow DIN EN 10095 and DIN 17742. ASTM B166 for UNS N06601 gives only a 0.10 % carbon maximum with no minimum, and allows copper to 1.00 %. Tighter internal limits can be agreed at order and recorded on the mill certificate.

Mechanical

Mechanical properties of NC23FeA forgings

The first two rows 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.

Short-time properties at temperature

Creep-rupture strength

Above roughly 550 °C these figures size the part, not the room-temperature tensile values. Note how steeply the curve falls between 700 and 800 °C. If the duty sits near 800 °C under sustained load, check the design against these numbers before settling on NC23FeA.

Physical

Physical properties

Use the density figure to estimate forging weight from a drawing: mass in kilograms equals volume in mm³ multiplied by 8.05 × 10⁻⁶.

Process route

Melting, forging and heat treatment

Our NC23FeA billet is melted by EAF + VOD, with ESR remelting where the specification or the service calls for better cleanliness and less segregation. Heat chemistry is checked against the EN 10095 and ASTM B166 limits before anything is heated, with particular attention to the 1.0 to 1.7 % aluminium window and the 0.03 % carbon minimum.

Hot working

Forged between 1,200 °C and 900 °C on hydraulic presses at a controlled reduction ratio, then cooled quickly. The workpiece goes into a furnace already at working temperature rather than being heated through slowly. Rings are ring-rolled seamless. Heat treatment after hot working restores forming, machining and welding behaviour and brings back creep resistance.

Heat treatment options

• Solution anneal, 1,100 to 1,200 °C, water quenched. The standard delivery condition.
• Creep-optimised anneal, 1,140 to 1,160 °C. Gives grain size ASTM E112 No. 5 or coarser, above 65 µm, which is what carries the creep strength.
• Stabilising treatment, 980 °C for about 3 h. Worth specifying if the part will sit continuously between 600 and 650 °C in service.
• No ageing. The grade is solid-solution strengthened, so a precipitation-hardening cycle does not apply.

Hold time follows section thickness, roughly 50 minutes plus one minute per millimetre above 20 mm. Too short a hold does more damage than too long. Annealing below the range refines the grain and quietly removes the property the material was bought for.

Cleanliness before heating

Sulphur, phosphorus, lead and other low-melting metals attack this alloy during heat treatment. Marking paints, temperature crayons, greases and high-sulphur fuels are the usual sources. Natural gas should carry less than 0.1 % sulphur. We avoid direct flame impingement and any reducing or fluctuating furnace atmosphere.

Machining and welding

Machine in the solution-annealed condition. The alloy work-hardens faster than austenitic stainless steel, so run low cutting speeds with a positive feed, keep the tool engaged, and take a chip deep enough to cut below the work-hardened layer. Welding is straightforward by GTAW, GMAW, plasma, electron beam and SMAW. Common fillers are FM 602 CA (AWS ERNiCrFe-12, UNS N06025) and FM 617 (AWS ERNiCrCoMo-1). Keep heat input low, run stringer beads and hold interpass temperature under 120 °C.

Product forms

NC23FeA forged shapes we produce

Everything below is forged to drawing. Open-die work needs no dies, so there is no tooling charge and no minimum quantity. A single furnace spare is as easy to quote as a production batch.

• NC23FeA Forged RingsSeamless rolled & ring-rolled
• NC23FeA Forged FlangesWN, blind, custom bore
• NC23FeA Forged Discs & DisksSolid and bored
• NC23FeA Forged Round BarsRough turned or black
• NC23FeA Shafts & SpindlesStraight, stepped, eccentric
• NC23FeA Forged Tube SheetsHeat exchanger service
• NC23FeA Sleeves & BushingsBored and honed
• NC23FeA Forged Pipes & TubesHollow forged, seamless
• NC23FeA Retort & Muffle RingsFurnace end rings
• NC23FeA Valve ComponentsBodies, stems, seat rings
• NC23FeA Nozzles & BlocksForged to print
• Custom near-net shapesForged to drawing

Capability

Size and weight capability

Machining allowance is normally 6 to 20 mm per surface depending on section size, unless your drawing says otherwise. Send the drawing and we will confirm the achievable envelope, the forging reduction ratio and the allowance before quoting.

Applications

Where NC23FeA forgings are used

All of these duties share one thing: the part goes up and down through temperature and the scale has to stay put. Where the medium is wet or acidic rather than hot and oxidising, another nickel alloy usually suits better. Tell us the medium at enquiry stage and we will say so.

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, hardness against the 220 HB maximum, and elevated-temperature or stress-rupture testing where specified.
• Grain size to ASTM E112, No. 5 or coarser where creep strength governs.
• Heat treatment record giving actual anneal temperature, hold time and cooling method. On this grade that record is what decides service performance.
• 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 witnessed 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 specification cross-reference

One point to check against your drawing. ASTM B564 is often quoted for Alloy 601 forgings, but UNS N06601 is not in the B564 scope list. Forgings in this grade are usually ordered to ASTM B166, or AMS 5715, together with the drawing, and in Europe to DIN EN 10095. Name the governing specification on the enquiry and we will confirm compliance before accepting the order.

Ordering

How to request an NC23FeA quotation

1. Send the drawing, or the rough dimensionsPDF, DWG or STEP. With no drawing, give OD, ID, height or length, plus the machining allowance you want added.
2. State the governing specification and delivery conditionFor example, NC23FeA / UNS N06601 to ASTM B166, solution annealed, or 2.4851 to DIN EN 10095.
3. Tell us the service temperatureIt changes the heat treatment we recommend. Continuous duty at 600 to 650 °C calls for the 980 °C stabilising treatment. Creep-governed duty calls for the 1,140 to 1,160 °C anneal and a grain size check to ASTM E112.
4. 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, grain size reporting.
5. Give quantity and required delivery dateQuantity affects billet cut-up efficiency and so the price. Say if the first article is a prototype.
6. 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 NC23FeA

Last reviewed 22 August 2026 · Reviewed by the technical sales team, Jiangyin Jiangnan Metal Co., Ltd. · Property data is compiled from DIN EN 10095, DIN 17742, ASTM B166 and published Alloy 601 literature and is given for guidance. The governing documents are the purchase-order specification and the mill certificate issued with the goods.