UNS N07725 / Alloy 725 / W.Nr. 2.4667

UNS N07725 Forgings

Q: What heat treatment is applied to UNS N07725 forgings?

Solution anneal at 1040 C followed by air cooling, then double ageing at 732 C for 8 hours, furnace cool at 56 C per hour to 620 C, hold 8 hours and air cool. This is the recommended cycle for sour gas applications and is the default supply condition at Jiangyin Jiangnan Metal unless the order states otherwise.

Q: At what temperature is alloy 725 forged?

Hot working is carried out between 899 C and 1121 C. The final passes are taken as light reductions in the 899 to 954 C range, and the piece is reheated whenever any part drops below 899 C. Final reduction is 20% minimum for open-die work to avoid a duplex grain structure, and parts are air cooled from the forging temperature rather than quenched.

Q: What sizes of UNS N07725 forgings can Jiangyin Jiangnan Metal supply?

Jiangyin Jiangnan Metal Co., Ltd. forges rolled rings up to about 3000 mm outside diameter, bars from 60 to 800 mm diameter, shafts up to 6000 mm long, and single pieces up to about 10 tonnes, all to customer drawing. Send a drawing to sales@steelforgepieces.com to confirm capability for a specific part.

Q: Can Jiangyin Jiangnan Metal forge UNS N07725 to my drawing?

Yes. All N07725 work is forged to customer drawing rather than sold from stock, and single piece trial orders are accepted for qualification work. Lead time depends on billet availability and section size, and a firm date is confirmed with every quotation. Contact sales@steelforgepieces.com or 0086-189-2135-9659.

Open-die forged rings, flanges, bars, discs, sleeves and shafts in age-hardenable Ni-Cr-Mo-Nb alloy 725 for sour service, subsea and seawater duty.

UNS N07725, also known as Alloy 725, is an age-hardenable nickel-chromium-molybdenum-niobium alloy. It has essentially the same corrosion resistance as alloy 625, with about twice the strength of alloy 625 in the annealed condition. Strength is developed by solution annealing and a two-stage ageing treatment instead of by cold work, so heavy and non-uniform forged sections reach full properties while keeping high ductility and toughness. The alloy is listed in NACE MR0175 / ISO 15156-3 for sour oil and gas service.

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China. We forge UNS N07725 to customer drawing in the form of seamless rolled rings, flanges, round bars, discs, tube sheets, sleeves, bushings and shafts. Forgings are supplied solution annealed and aged, 100% ultrasonically tested, with EN 10204 3.1 or 3.2 certification. Send a drawing to sales@steelforgepieces.com or call 0086-189-2135-9659.

Grade data summaryUNS N07725 rev. 2026-08

Alloy type: Ni-Cr-Mo-NbAge hardenable, gamma double prime
Nickel: 55.0 to 59.0 %Cr 19.0 to 22.5, Mo 7.0 to 9.5
Tensile strength: 1035 MPa min150 ksi, aged condition
Yield 0.2 %: 827 MPa min120 ksi, aged condition
Hardness limit: 43 HRC maxNACE MR0175 sour service
Density: 8.31 g/cm³Melting range 1271 to 1343 °C

Metallurgy

What UNS N07725 is

UNS N07725 is a nickel base superalloy containing nominally 57% nickel, 21% chromium, 8% molybdenum and 3.4% niobium, with a titanium addition of 1.0 to 1.7%. The high nickel and chromium content gives corrosion resistance in both reducing and oxidising environments. The molybdenum content gives resistance to reducing media and a high degree of resistance to pitting and crevice corrosion. The combination of these elements also makes the alloy resistant to hydrogen embrittlement and stress-corrosion cracking.

Strength is developed by precipitation of the gamma double prime phase (Ni₃Nb) during ageing. This is the same strengthening mechanism used in alloy 718, but N07725 carries higher chromium and molybdenum and much lower aluminium, so it retains the corrosion resistance of alloy 625 while reaching roughly twice the strength of annealed 625. Because the strength does not come from cold work, a heavy forged block develops the same properties as a small diameter bar.

Alloy 725 is normally specified where a part must carry high load and also resist hydrogen sulphide, carbon dioxide, chlorides and elemental sulphur at temperature. Common applications are hangers, landing nipples, side pocket mandrels and polished bore receptacles in sour gas wells, and high strength fasteners in seawater service.

Reference

Designations and standards

UNS N07725 equivalents and ordering specifications
UNS number	N07725
Common names	Alloy 725, Inconel 725, Nickelvac 725, Nicrofer 5621
Werkstoff Nr.	2.4667
Bar and wire	ASTM B805
Bar and forging stock	SMC HA91, ASME Code Case 2217
Forgings	ASTM B564 practice for nickel alloy forgings, or to end user specification. Grade coverage varies by edition, so the applicable revision is confirmed at enquiry.
Sour service	NACE MR0175 / ISO 15156-3, 43 HRC maximum
Ultrasonic testing	ASTM A388, EN 10228-3, SEP 1921
Certification	EN 10204 3.1 (mill) or 3.2 (third party: BV, SGS, TUV, DNV, ABS, LR)

Inconel is a registered trademark of Special Metals Corporation. Trade names are listed here for identification only. Material supplied by Jiangyin Jiangnan Metal is certified to the UNS N07725 chemistry and to the customer specification.

Chemistry

Chemical composition of UNS N07725

Composition limits, weight %
Element	Symbol	Weight %
Nickel	Ni	55.0 to 59.0
Chromium	Cr	19.0 to 22.5
Molybdenum	Mo	7.0 to 9.5
Niobium	Nb	2.75 to 4.0
Titanium	Ti	1.0 to 1.7
Aluminium	Al	0.35 max
Manganese	Mn	0.35 max
Silicon	Si	0.20 max
Carbon	C	0.03 max
Phosphorus	P	0.015 max
Sulphur	S	0.010 max
Iron	Fe	Balance

The melting route for our N07725 forging stock is VIM plus ESR, or VIM plus ESR plus VAR where the end use calls for a higher cleanliness level. Double and triple melting keeps sulphur and phosphorus low and gives the segregation control needed for thick sour service sections.

Properties

Mechanical properties

Minimum specified properties, solution annealed and aged

Room temperature acceptance values
Property	Metric	Imperial
Tensile strength	1035 MPa min	150 ksi min
Yield strength, 0.2% offset	827 MPa min	120 ksi min
Elongation in 4D	20 % min	20 % min
Hardness, sour service	43 HRC max	43 HRC max

The 43 HRC limit is the NACE MR0175 / ISO 15156-3 supply hardness ceiling for N07725 in sour service. The ageing cycle is set to keep the forging inside that limit while still meeting the strength minima.

Typical properties of age-hardened bar

Mean values, hot finished rounds 13 to 190 mm diameter
Condition	0.2% YS	UTS	Elong.	Hardness	Charpy V
Annealed	427 MPa	855 MPa	57 %	5 HRC	n/a
Annealed and aged	903 to 917 MPa	1241 MPa	30 to 31 %	36 HRC	92 to 132 J

Alloy 725 holds its strength well as temperature rises. Average high temperature data for annealed and aged rod give a 0.2% yield strength of about 782 MPa at 315 °C and 778 MPa at 538 °C, with elongation above 29% across that range.

Properties

Physical properties

Age-hardened condition
Density	8.31 g/cm³ (0.300 lb/in³)
Melting range	1271 to 1343 °C (2320 to 2449 °F)
Young's modulus at 20 °C	204 GPa (29.6 x 10³ ksi)
Shear modulus at 20 °C	78 GPa
Poisson's ratio	0.31
Mean expansion 20 to 500 °C	14.1 µm/m·°C
Electrical resistivity at 20 °C	1.144 µΩ·m
Magnetic permeability at 15.9 kA/m	less than 1.001

Process

Heat treatment of N07725 forgings

N07725 is strengthened by gamma double prime precipitation during ageing, so the forging is solution annealed first and then double aged. The standard cycle we use for sour service work is set out below.

Standard heat treatment cycle
Step	Parameters
Solution anneal	1040 °C (1900 °F), air cool
First age	732 °C (1350 °F), 8 h
Furnace cool	56 °C/h (100 °F/h) to 620 °C
Second age	620 °C (1150 °F), 8 h, air cool

Air cooling after the solution anneal is preferred to water quenching. Where a component is welded, the best results are obtained by annealing before welding and applying a full solution anneal plus age after welding. Direct ageing of as-welded material gives low impact strength. GTAW and GMAW are the preferred welding processes with 725NDUR type filler metal. Submerged arc and shielded metal arc welding are not recommended.

Works practice

Open-die forging practice for alloy 725

Alloy 725 resists deformation more than most materials during hot working, so it needs adequate press capacity together with close control of temperature and reduction. The sequence we follow is set out below.

Step 1VIM plus ESR billet, certified heat
Step 2Heat to 899 to 1121 °C, short soak
Step 3Open-die forge, 20% minimum final reduction
Step 4Finish light passes at 899 to 954 °C
Step 5Air cool, then solution anneal and double age
Step 6Machine, UT, tensile, hardness, 3.1 certificate

Hot working range is 899 to 1121 °C. The workpiece is reheated whenever any portion falls below 899 °C.
Reductions are kept uniform to avoid a duplex grain structure. Final reduction is 20% minimum for open-die work and 10% minimum for closed-die work.
The last operation is worked with gradually falling temperature and finished with light reduction in the 899 to 954 °C range. This is required to ensure notch ductility after annealing and ageing.
Parts are air cooled from the forging temperature rather than water quenched.
Tools and dies are preheated to 260 °C. Any rupture appearing on the surface of the workpiece is removed at once.

Grain size is reported on the certificate. For heavy sour service sections the target ASTM grain size is agreed with the end user before the first heat, because it affects both the ultrasonic acceptance level and the low temperature impact values.

Capability

UNS N07725 forged products and sizes

We forge N07725 to drawing in the following forms.

Typical size capability, UNS N07725
Form	Size range	Single piece weight
Seamless rolled rings	OD 200 to 3000 mm, height to 1000 mm	20 to 8000 kg
Round bars	Dia. 60 to 800 mm	10 to 6000 kg
Discs and blanks	Dia. 100 to 2500 mm	20 to 8000 kg
Shafts and spindles	Dia. 80 to 900 mm, length to 6000 mm	50 to 10000 kg
Sleeves and bushings	OD 100 to 1500 mm	10 to 4000 kg

Delivery condition can be as forged, rough machined, or finish machined to drawing. The standard supply condition is solution annealed and double aged, unless the order calls for annealed material for later forming.

Quality

Testing and certification

Standard test scope for N07725 forgings
Test	Standard
Chemical analysis	Product and heat analysis, spectrographic plus combustion for C and S
Tensile, room temperature	ASTM E8 / ISO 6892-1
Hardness	ASTM E18, 43 HRC max for sour service
Charpy V-notch impact	ASTM E23, test temperature to order
Ultrasonic testing	ASTM A388, EN 10228-3, SEP 1921, 100% volumetric
Liquid penetrant	ASTM E165 / EN 10228-2
Grain size	ASTM E112
Certificate	EN 10204 3.1, or 3.2 witnessed by BV, SGS, TUV, DNV, ABS or LR

Every forging is traceable to its heat number. The heat number appears on the certificate together with the melting route, the full heat treatment record with furnace charts, and the location and orientation of the test bar.

Applications

Applications for UNS N07725 forgings

Typical service by industry
Industry	Components
Sour oil and gas, downhole	Hangers, landing nipples, side pocket mandrels, polished bore receptacles, packers, completion tools
Subsea and wellhead	Christmas tree bodies, connectors, hubs, tubing hangers, valve blocks and seat rings
Valves and pumps	Valve stems, gate and ball valve components, pump shafts, plungers, chemical pump sleeves
Pressure equipment	Forged flanges, tube sheets, nozzles, shell rings for heat exchangers and air receivers
Marine and seawater	High strength fasteners, studs and shafting resisting pitting and crevice attack in sea water
Power and rotating equipment	Turbine and compressor shafts, gears, spindles, gearbox components
Chemical process	Reactor internals, crystalliser parts, agitator shafts, mixing equipment

In published C-ring testing, alloy 725 showed no cracking in 25% sodium chloride with 0.5% acetic acid and 1 g/l sulphur under 825 kPa hydrogen sulphide, at yield level stress up to about 232 °C. In a 30 day flowing seawater test it showed no crevice corrosion initiation, while annealed alloy 625 was attacked. For these reasons alloy 725 is used in deep sour wells in place of cold worked alloy 625 and alloy 718.

Grade selection

UNS N07725 compared with alloy 718, 625 and 925

Age-hardenable corrosion resistant alloys
Alloy	UNS	Cr / Mo	Strengthening	Main advantage
Alloy 725	N07725	21 / 8	Gamma double prime	Highest corrosion resistance among the age hardened grades, sour service to 43 HRC without cold work
Alloy 718	N07718	19 / 3	Gamma double prime	Lower cost and higher temperature capability, but much lower molybdenum, so it cracks sooner in severe sour environments
Alloy 625	N06625	21 / 9	Solid solution	Similar corrosion resistance at about half the strength unless cold worked, and cold work reduces sour service margin
Alloy 925	N09925	21 / 3	Gamma prime	Lower cost Ni-Fe base for milder sour duty, with less pitting resistance than 725
Alloy 716	N07716	20 / 8	Gamma double prime	Close to 725 and covered by the same ASTM B805 family, so the two are often cross quoted

Alloy 725 is normally specified when the service environment is too severe for alloy 718 and the load case is too high for annealed alloy 625. If the grade has not yet been fixed, send us the service conditions and we will quote the alternatives.

Enquiry

How to order UNS N07725 forgings

Send a drawing or the finished dimensions to sales@steelforgepieces.com. Please include the following so that the enquiry can be priced without further questions.

Drawing or rough dimensions, with the machining allowance you want us to leave
Quantity and required delivery date
Delivery condition: as forged, rough machined or finish machined
Heat treatment condition: annealed, or solution annealed and double aged
Acceptance standard and NDT level, and whether sour service applies
Certificate type: EN 10204 3.1, or 3.2 with the third party you nominate

Email your drawing

Questions

Frequently asked questions

What is UNS N07725?

UNS N07725 is an age-hardenable nickel-chromium-molybdenum-niobium alloy, nominally 57% Ni, 21% Cr, 8% Mo and 3.4% Nb. It has essentially the corrosion resistance of alloy 625 with about twice the strength of alloy 625 in the annealed condition, and it is approved under NACE MR0175 for sour gas wells.

Is UNS N07725 the same as Inconel 725?

Yes. Inconel 725 is the Special Metals trade name for the alloy whose UNS number is N07725. The same material is sold as Alloy 725, Nickelvac 725 and Nicrofer 5621, and carries Werkstoff number 2.4667. All of these refer to the same chemistry.

What is the difference between alloy 725 and alloy 718?

Both are strengthened by gamma double prime ageing. Alloy 725 carries about 8% molybdenum against roughly 3% in alloy 718, along with higher chromium and much lower aluminium. This gives alloy 725 better resistance to pitting, crevice corrosion and sulphide stress cracking. Alloy 718 remains the cheaper choice for high temperature duty in environments that are not sour.

Why choose alloy 725 instead of cold worked alloy 625?

Alloy 625 reaches high strength only through cold work, which cannot be applied uniformly to heavy or non-uniform forged sections and which reduces the sour service margin. In published C-ring testing, cold worked alloy 625 at 1103 MPa yield strength cracked, while age-hardened alloy 725 at a similar strength level did not. Age hardening also keeps ductility and toughness high.

What heat treatment is applied to N07725 forgings?

Solution anneal at 1040 °C followed by air cooling, then double ageing at 732 °C for 8 hours, furnace cool at 56 °C per hour to 620 °C, hold 8 hours and air cool. This is the recommended cycle for sour gas applications and is our default supply condition unless the order states otherwise.

Is UNS N07725 approved for sour service?

Yes. N07725 is listed under NACE MR0175 / ISO 15156-3 for sour oil and gas service, with a maximum supply hardness of 43 HRC. The ageing cycle is set to keep the forging inside that limit while still meeting the 1035 MPa tensile and 827 MPa yield minima.

At what temperature is alloy 725 forged?

Hot working is carried out between 899 °C and 1121 °C. The final passes are taken as light reductions in the 899 to 954 °C range, and the piece is reheated whenever any part drops below 899 °C. Final reduction is 20% minimum for open-die work to avoid a duplex grain structure, and parts are air cooled from the forging temperature rather than quenched.

What sizes of N07725 forgings can Jiangyin Jiangnan Metal supply?

We forge rolled rings up to about 3000 mm outside diameter, bars from 60 to 800 mm diameter, shafts up to 6000 mm long, and single pieces up to about 10 tonnes, all to customer drawing. Send the drawing and we will confirm the exact capability for your part.

What certification comes with the forgings?

EN 10204 3.1 as standard, covering chemistry, mechanical results, heat treatment records and heat traceability. EN 10204 3.2 certificates witnessed by BV, SGS, TUV, DNV, ABS or Lloyd's Register are available on request. Ultrasonic testing is carried out to ASTM A388, EN 10228-3 or SEP 1921.

Can you forge to my drawing, and what is the minimum order?

Yes. All of our N07725 work is forged to customer drawing rather than sold from stock, and single piece trial orders are accepted for qualification work. Lead time depends on billet availability and section size, and a firm date is confirmed with every quotation.

How is alloy 725 welded?

GTAW and GMAW with 725NDUR type filler metal are the preferred processes. Submerged arc and shielded metal arc welding are not recommended. The best results come from annealing the material before welding and giving it a full solution anneal plus age afterwards. Ageing as-welded material without a prior anneal gives low impact values.

Supplier

About the manufacturer

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China, within the Yangtze River delta forging area and close to the port of Shanghai. We forge carbon steel, alloy steel, tool steel, stainless steel and nickel alloys to customer drawing, including seamless rolled rings, flanges, bars, discs, sleeves, shafts and tube sheets, and supply them worldwide with EN 10204 certification.

Company: Jiangyin Jiangnan Metal Co., Ltd., open-die forging factory
Address: No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Phone: 0086-189-2135-9659
Email: sales@steelforgepieces.com
Website: www.steelforgepieces.com
Materials: Nickel alloys, stainless steel, alloy steel, tool steel, carbon steel
Languages: English, Chinese

Document information

Document: UNS N07725 forgings, technical and supply data sheet
Issued by: Engineering department, Jiangyin Jiangnan Metal Co., Ltd.
Revision: 30 August 2026
Reference: https://www.steelforgepieces.com/Nickel-Alloy/UNS-N07725.html

Sources used for the published alloy data:

Special Metals Corporation, technical bulletin for alloy 725, publication SMC-066
ASTM B805, precipitation hardening corrosion resistant nickel alloy bar and wire for downhole oil and gas applications
NACE MR0175 / ISO 15156-3, materials for use in hydrogen sulphide containing environments
ASME Code Case 2217

Size capability and works practice describe production at Jiangyin Jiangnan Metal Co., Ltd. Data is given for guidance and does not form a warranty. Enquiries and corrections to sales@steelforgepieces.com or 0086-189-2135-9659.

All nickel alloy grades we forge