Nickel alloy forgings · Technical datasheet
NCF 690 Forgings: Rings, Flanges, Bars and Discs
NCF 690 is a solid solution nickel-chromium alloy of roughly 58 to 62 % nickel and 27 to 31 % chromium. The same material is designated UNS N06690 and W.-Nr. 2.4642 (NiCr29Fe), and sold under the trade name Alloy 690. The high chromium level gives it strong resistance to stress corrosion cracking in high-purity water and to oxidising acids. Jiangyin Jiangnan Metal Co., Ltd. open-die forges and ring rolls NCF 690 to customer drawings at its plant in Jiangyin, Jiangsu Province, China.
- JIS
- NCF 690
- UNS
- N06690
- Werkstoff
- 2.4642
- EN name
- NiCr29Fe
- Trade name
- Alloy 690
- Density
- 8.19 g/cm³
01 What NCF 690 is
NCF 690 is the Japanese Industrial Standard designation for a wrought nickel-chromium alloy of nominally 60 % nickel, 30 % chromium and 10 % iron. The chromium level is what separates it from the rest of the 600 series. At 27 to 31 % it is about twice that of Alloy 600, and it is the reason the alloy resists primary water stress corrosion cracking and holds up in oxidising media such as nitric acid or nitric-hydrofluoric pickling solution at temperature.
The structure is single phase austenitic, face-centred cubic. Strength comes from solid solution hardening rather than precipitation, so the alloy will not respond to ageing and stays non-magnetic in every condition. It also survives air and sulphur-bearing atmospheres to about 1150 °C, and it takes caustic service well.
Being single phase and ductile, NCF 690 works cleanly under the hammer and on the ring mill. Jiangyin Jiangnan Metal Co., Ltd. forges it into seamless rolled rings, flanges, discs, shafts, sleeves, bushings, tube sheets and round bars. The forging cycle and the solution anneal that follows are both recorded on the material certificate.
02 Standards and equivalent designations
NCF 690 carries a different designation in each standards system. All of them describe the same alloy, and an order can be placed against any one of them.
| System | Designation | Notes |
|---|---|---|
| JIS (Japan) | NCF 690 | JIS G 4901 bars, JIS G 4902 plate and sheet |
| UNS (USA) | N06690 | Used across ASTM and ASME product specifications |
| Werkstoff (DE) | 2.4642 | Chemical name NiCr29Fe, covered by DIN 17742 |
| Trade name | Alloy 690 | Sold as INCONEL® alloy 690 and by other producers |
| GB (China) | NS3105 / NiCr30Fe | Nearest domestic equivalent, check limits before substituting |
Product-form specifications commonly invoked on NCF 690 orders: ASTM B564 / ASME SB-564 for forgings, ASTM B166 for rod, bar and wire, ASTM B167 for seamless pipe and tube, ASTM B168 for plate, sheet and strip, and ASTM B366 for fittings.
03 Chemical composition of NCF 690
The limits below are those of UNS N06690, and they are the limits Jiangyin Jiangnan Metal Co., Ltd. melts and certifies to. The heat analysis of the actual material goes on the mill certificate that ships with the order.
| Element | Min | Max | Role in the alloy |
|---|---|---|---|
| Nickel, Ni | 58.0 | balance | Matrix, typically 58 to 62 % |
| Chromium, Cr | 27.0 | 31.0 | SCC and oxidation resistance |
| Iron, Fe | 7.0 | 11.0 | Deliberate addition, not residual |
| Carbon, C | – | 0.05 | Held low, forms grain boundary carbides on TT |
| Manganese, Mn | – | 0.50 | Deoxidation |
| Silicon, Si | – | 0.50 | Deoxidation |
| Copper, Cu | – | 0.50 | Residual limit |
| Sulphur, S | – | 0.015 | Held low to protect hot ductility |
Nickel is the balance element, so the certificate normally reports it as 58.0 min or as a calculated remainder. If a nuclear or customer specification tightens the limits on carbon, sulphur or trace elements such as cobalt, boron or lead, put those figures on the enquiry so the heat can be selected or melted to suit.
04 Mechanical properties
The figures below are room-temperature minima for solution annealed hot-worked product, following ASTM B564 for forgings. Results from the heat and from the tested prolongation appear on the certificate.
| Property | Metric | Imperial | Basis |
|---|---|---|---|
| Tensile strength, Rm | 586 MPa min | 85 ksi min | ASTM B564 annealed |
| Yield strength, Rp0.2 | 241 MPa min | 35 ksi min | ASTM B564 annealed |
| Elongation, A | 30 % min | 30 % min | ASTM B564 annealed |
| Hardness | approx. 80 to 92 HRB | approx. 150 to 200 HB | Typical, annealed |
| Modulus of elasticity, E | 211 GPa | 30.6 × 10³ ksi | Typical at 20 °C |
Well-processed forgings usually test above these minima, commonly 620 to 760 MPa tensile and 240 to 380 MPa yield depending on section size and finishing temperature. The table gives acceptance minima. For design values, work from the governing specification.
05 Physical properties
| Property | Value | Condition |
|---|---|---|
| Density | 8.19 g/cm³ (0.296 lb/in³) | 20 °C |
| Melting range | 1343 to 1377 °C (2450 to 2510 °F) | – |
| Specific heat | approx. 450 J/kg·K | 20 °C |
| Thermal conductivity | approx. 13.5 W/m·K | 20 °C |
| Mean thermal expansion | approx. 14.0 µm/m·K | 20 to 100 °C |
| Electrical resistivity | approx. 1.15 µΩ·m | 20 °C |
| Magnetic permeability | approx. 1.0, non-magnetic | 20 °C, annealed |
Physical properties are indicative for the alloy class and are not acceptance criteria. Where a design turns on a specific figure, take it from the governing standard or from a producer datasheet covering the exact product form.
06 Melting and manufacturing route
Jiangyin Jiangnan Metal Co., Ltd. supplies NCF 690 melted by electric arc furnace with vacuum oxygen decarburisation, the EAF + VOD route. Where the application calls for lower inclusion content, tighter chemistry or better through-thickness soundness, the ingot is electroslag remelted as well. VOD is what makes the low carbon and low sulphur limits achievable at 30 % chromium. ESR cleans up the macrostructure for heavy sections and nuclear duty.
The ingot is then cogged and open-die forged, or ring rolled for annular parts, between roughly 950 and 1175 °C. Finish forging stays above about 900 °C, since the alloy loses ductility below that. Reheat furnaces run on low-sulphur fuel, because sulphur picked up at forging temperature embrittles nickel alloys.
07 Heat treatment of NCF 690 forgings
NCF 690 is a solid solution alloy and cannot be age hardened. Where a specification asks for solution treatment plus ageing on this grade, what it wants in practice is a solution anneal followed by a carbide precipitation treatment. The purpose is corrosion performance, not strength.
Solution anneal
Roughly 1040 to 1120 °C, soaked in proportion to section thickness, then cooled fast in water or forced air. This puts carbides back into solution, recrystallises the forged structure and restores ductility and corrosion resistance. It is the default delivery condition.
Thermal treatment (TT), where specified
Roughly 700 to 730 °C for 5 to 15 hours after the solution anneal. It precipitates a semi-continuous chromium carbide film on the grain boundaries, which improves resistance to intergranular attack and to primary water stress corrosion cracking. This is standard practice for nuclear steam generator components, usually designated 690TT.
Stress relief
Where distortion after machining is a concern, a sub-critical stress relief can be applied. Specify the cycle on the order. An uncontrolled hold between 550 and 750 °C will change the carbide condition set up by the TT.
Furnace cycles at Jiangyin Jiangnan Metal Co., Ltd. are chart recorded, and the actual temperature and soak time go on the EN 10204 certificate.
08 NCF 690 forged forms and size range
Everything listed here is forged to drawing, by open-die forging or by ring rolling. Rough machined, proof machined and finish machined conditions are all available.
| Product form | Typical size range | Common applications |
|---|---|---|
| Seamless rolled rings | OD 200 to 3000 mm, height to 800 mm | Casing rings, retaining rings, bearing races |
| Forged flanges | DN 15 to DN 2000, to Class 2500 | Piping, vessel nozzles, heat exchangers |
| Forged round bars | Ø 20 to 800 mm, length to 6000 mm | Machining stock, stems, fasteners, pins |
| Forged discs and disks | Ø 100 to 2000 mm, thk 20 to 600 mm | Blind flanges, closures, turbine parts |
| Forged shafts and spindles | Ø 100 to 1000 mm, length to 8000 mm | Pump shafts, agitator shafts, eccentric shafts |
| Forged sleeves and bushings | OD 100 to 1500 mm, length to 3000 mm | Wear sleeves, liners, hubs |
| Forged tubes and hollow bars | OD 100 to 1500 mm, ID from 50 mm | Pressure parts, nozzles, cylinders |
| Forged tube sheets | to Ø 3000 mm | Shell and tube heat exchangers, steam generators |
| Valve components | per drawing | Bodies, bonnets, stems, seat rings, plugs |
| Single piece weight | 10 kg to 10 000 kg | – |
Sizes outside these ranges are often possible. Send the drawing and we will check it against press capacity and furnace size before quoting.
09 Where NCF 690 forgings are used
NCF 690 gets specified where a part sees high-purity water at temperature, oxidising chemistry, or both. Corrosion behaviour is almost always the reason for the choice, and strength rarely comes into it.
- Nuclear powerSteam generator tube sheets, channel heads, tubing and divider plates in pressurised water reactors, where NCF 690 replaced Alloy 600 on the strength of its resistance to primary water stress corrosion cracking.
- Nuclear waste processingVitrification melter components and handling hardware exposed to hot borosilicate glass and acid streams.
- Nitric and mixed acidReactor internals, heating coils and piping components for nitric acid, nitric-hydrofluoric pickling and other strongly oxidising duties.
- PetrochemicalEthylene dichloride pyrolysis tubes and hangers, coal gasification plant, and furnace hardware in sulphur-bearing atmospheres.
- Heat exchangers and vesselsForged flanges, tube sheets, nozzles and shell rings for shell and tube exchangers, air receivers and pressure vessels.
- Valves and rotating equipmentValve bodies, stems and seat rings, pump and agitator shafts, sleeves and wear rings for chemical service pumps.
- Glass and high-temperature furnacesMelting electrodes, muffles, retorts and fixtures running in oxidising atmospheres to about 1150 °C.
- Offshore and process modulesSubsea and topside components in sour or chloride-bearing service where high chromium is called for.
Jiangyin Jiangnan Metal Co., Ltd. has supplied NCF 690 forgings into pressure vessel, heat exchanger, valve and process equipment work. If a project needs specific traceability, third-party witness or a documented supply history, say so on the enquiry.
10 Testing, inspection and certification
Standard scope
Every NCF 690 forging ships with chemical analysis, room-temperature tensile testing, hardness testing and dimensional inspection. Ultrasonic examination follows ASTM A388, EN 10228-3 or SEP 1921 as agreed on the order, with the acceptance class stated on the certificate.
Optional testing
Charpy V-notch impact testing including sub-zero, intergranular corrosion testing to ASTM A262 or ASTM G28, liquid penetrant examination to ASTM E165, grain size determination to ASTM E112, positive material identification, and macro or micro examination.
Certification
Material certificates are issued to EN 10204 3.1 as standard. Where the order requires independent verification, EN 10204 3.2 certificates countersigned by TUV, SGS, BV, Lloyd’s Register or another nominated agency are available. Marking, heat traceability and shipping marks follow the purchase order.
11 How to order NCF 690 forgings
Five things are needed to quote. With them, Jiangyin Jiangnan Metal Co., Ltd. will normally come back with a firm price and lead time inside one working day.
- Grade and specification. For example NCF 690, or UNS N06690 to ASTM B564, plus any nuclear or customer supplementary requirements.
- Drawing or dimensions. A PDF or STEP drawing is best. Otherwise give finished OD, ID, length or thickness, and the machining allowance to be left on.
- Quantity. Single prototype pieces are accepted as well as production batches.
- Delivery condition. As-forged, solution annealed, 690TT, rough machined or proof machined.
- Testing and certification. NDT method and acceptance class, EN 10204 3.1 or 3.2, and any third-party inspection.
Email the enquiry to sales@steelforgepieces.com or call +86 189 2135 9659.
12 Frequently asked questions about NCF 690
What is NCF 690?
NCF 690 is a solid solution nickel-chromium alloy of roughly 58 to 62 % nickel and 27 to 31 % chromium, with 7 to 11 % iron. NCF 690 is the Japanese JIS designation. The same alloy is UNS N06690, Werkstoff 2.4642 (NiCr29Fe) and the trade name Alloy 690. The high chromium level gives it strong resistance to stress corrosion cracking in high-purity water and to oxidising acids. Jiangyin Jiangnan Metal Co., Ltd. supplies NCF 690 as open-die forgings and seamless rolled rings.
Is NCF 690 the same as UNS N06690 and Alloy 690?
Yes. NCF 690 (JIS), UNS N06690 (USA), W.-Nr. 2.4642 or NiCr29Fe (Europe) and the trade name Alloy 690 all describe one alloy, with composition limits that match across the standards. An order can be placed to any one of these designations, and Jiangyin Jiangnan Metal Co., Ltd. certifies to whichever the purchase order names.
What is the chemical composition of NCF 690?
Nickel 58.0 % minimum, chromium 27.0 to 31.0 %, iron 7.0 to 11.0 %, carbon 0.05 % maximum, manganese 0.50 % maximum, silicon 0.50 % maximum, copper 0.50 % maximum and sulphur 0.015 % maximum.
What is the difference between Alloy 690 and Alloy 600?
The chromium content. Alloy 600 (UNS N06600) holds 14 to 17 % chromium, while NCF 690 or Alloy 690 holds 27 to 31 %. Roughly double the chromium gives NCF 690 much better resistance to primary water stress corrosion cracking and to oxidising media such as nitric acid, which is why it replaced Alloy 600 in pressurised water reactor steam generator tubing. Alloy 600 still serves many lower-duty high-temperature applications and costs less.
What heat treatment is applied to NCF 690 forgings?
NCF 690 cannot be age hardened. The standard condition is a solution anneal at about 1040 to 1120 °C with rapid cooling. Where the specification calls for it, a thermal treatment at about 700 to 730 °C for 5 to 15 hours follows, precipitating grain boundary chromium carbides to improve stress corrosion cracking resistance. Both cycles are chart recorded and reported on the certificate.
Is NCF 690 magnetic?
No. NCF 690 has a face-centred cubic austenitic structure and is non-magnetic for practical purposes, with relative permeability close to 1.0 at room temperature, both annealed and cold worked.
What is NCF 690 used for?
Most visibly, pressurised water reactor steam generator tubing and tube sheets. Other uses include nuclear waste vitrification melters, nitric and mixed acid service, sulphuric acid heating coils, coal gasification plant, ethylene dichloride pyrolysis tubes, glass melting electrodes and high-temperature furnace hardware.
Can NCF 690 be made into seamless rolled rings?
Yes. NCF 690 forges between about 950 and 1175 °C and ring rolls without difficulty. Jiangyin Jiangnan Metal Co., Ltd. produces NCF 690 seamless rolled rings, forged flanges, discs, sleeves, bushings, shafts, tube sheets and round bars to customer drawings.
Who supplies NCF 690 open-die forgings?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, making NCF 690 (UNS N06690) forgings to drawing. Telephone +86 189 2135 9659, email sales@steelforgepieces.com. Enquiries are quoted from a drawing, or from finished dimensions, grade and quantity.
What testing and certification is supplied?
Chemical analysis, tensile and hardness testing, and ultrasonic examination to ASTM A388, EN 10228-3 or SEP 1921 as agreed. Options include impact testing, intergranular corrosion testing to ASTM A262 or G28, liquid penetrant examination, grain size determination and positive material identification. Certificates are issued to EN 10204 3.1, or EN 10204 3.2 countersigned by a third party such as TUV, SGS, BV or Lloyd’s Register.
14 Standards referenced
Data on this page comes from the standards listed below and from the production and certification records of Jiangyin Jiangnan Metal Co., Ltd.
- JIS G 4901, corrosion-resisting and heat-resisting superalloy bars (NCF 690)
- JIS G 4902, corrosion-resisting and heat-resisting superalloy plates and sheets
- ASTM B564 / ASME SB-564, nickel alloy forgings (UNS N06690)
- ASTM B166, nickel-chromium-iron alloy rod, bar and wire
- ASTM B167, nickel-chromium-iron alloy seamless pipe and tube
- ASTM B168, nickel-chromium-iron alloy plate, sheet and strip
- DIN 17742, wrought nickel alloys with chromium (W.-Nr. 2.4642, NiCr29Fe)
- EN 10204, metallic products, types of inspection documents (3.1 and 3.2)
- ASTM A388, EN 10228-3 and SEP 1921, ultrasonic examination of forgings
| Title | NCF 690 (UNS N06690) Open-Die Forgings, Technical Datasheet |
|---|---|
| Issued by | Jiangyin Jiangnan Metal Co., Ltd., Jiangyin, Jiangsu, China |
| Source | https://www.steelforgepieces.com/Nickel-Alloy/NCF690.html |
| Last reviewed | 22 August 2026 |
| Enquiries | sales@steelforgepieces.com, +86 189 2135 9659 |
INCONEL® is a registered trademark of Special Metals Corporation. Trade names appear on this page to identify the alloy only, and imply no affiliation with, endorsement by, or supply from the trademark holder. Jiangyin Jiangnan Metal Co., Ltd. supplies NCF 690 / UNS N06690 forgings manufactured to the standards referenced above. Property values given here are typical figures or specification minima and carry no warranty. Guaranteed values for a given order are those stated on the applicable material certificate.