NCF 750 Forgings: Rings, Flanges, Discs, Shafts and Bars
Open-die forged NCF 750 (Inconel X-750 / UNS N07750 / W.Nr. 2.4669) to JIS G4901, JIS G4902 and ASTM B637.
NCF 750 is a precipitation-hardening nickel-chromium superalloy standardised in JIS G4901 (bar) and JIS G4902 (plate, sheet and strip). It is the Japanese designation for the alloy known internationally as Inconel X-750, UNS N07750 and Werkstoff 2.4669. Ageing precipitates a gamma-prime Ni3(Al,Ti) phase, and that phase carries the load at temperature. Stress-rupture strength stays high and creep rates stay low to 816 °C (1500 °F). Heat-treated material keeps useful strength as far as 980 °C (1800 °F). Resistance to chloride-ion stress-corrosion cracking is good once the part is fully aged. Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory in Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, forges NCF 750 into rings, flanges, discs, shafts, bars, sleeves, bushings, tube sheets and hollow forms, supplied solution treated and aged with EN 10204 3.1 or 3.2 certification.
- Alloy type
- Ni-Cr superalloy, age hardenable
- Nominal composition
- Ni ≥70 / Cr 14-17 / Fe 5-9
- Standards
- JIS G4901, G4902; ASTM B637; AMS 5667, 5668
- Density
- 8.28 g/cm3
- Max. service temp.
- 816 °C under sustained load
- Melting route
- EAF + AOD/VOD + ESR, or VIM + VAR
- Supplied condition
- Solution treated and aged
- Certification
- EN 10204 3.1 or 3.2
Forged and heat treated by Jiangyin Jiangnan Metal Co., Ltd. +86 189 2135 9659 sales@steelforgepieces.com
What is NCF 750?
NCF 750 is the JIS grade designation for a nickel-chromium alloy containing about 70 % nickel and 14 to 17 % chromium, made precipitation hardenable by additions of titanium (2.25 to 2.75 %), aluminium (0.40 to 1.00 %) and niobium plus tantalum (0.70 to 1.20 %). During ageing these elements precipitate as a coherent gamma-prime phase inside the austenitic nickel matrix. Room-temperature yield strength ends up well above that of solid-solution nickel alloys such as Inconel 600. Chromium content stays high enough to keep oxidation resistance.
In the annealed or solution-treated condition NCF 750 is relatively soft and can be machined or formed. The alloy only reaches its final properties after ageing. Forgings are therefore normally rough machined in the solution-treated condition, aged, then finish machined. We supply NCF 750 forgings in either condition, depending on whether the customer intends to age the part after final machining.
Inconel is a registered trademark of Special Metals Corporation. NCF 750 forgings supplied by Jiangyin Jiangnan Metal Co., Ltd. are manufactured to the chemical and mechanical requirements of the JIS, ASTM and AMS specifications listed below. The Inconel X-750 name appears here only to identify the equivalent grade.
NCF 750 equivalent grades and specifications
| System | Designation | Scope / product form |
|---|---|---|
| JIS (Japan) | NCF 750 | G4901 bar and forging stock; G4902 plate, sheet, strip |
| UNS (USA) | N07750 | Unified Numbering System |
| Trade name | Inconel X-750 | Also Alloy X-750, Haynes X-750, Nickel Alloy 750, Pyromet X-750 |
| Werkstoff (DE) | 2.4669 | NiCr15Fe7TiAl |
| ISO | NW7750 | NiCr15Fe7Ti2Al |
| GB (China) | GH4145 / GH145 | Deformed superalloy bar and forging |
| AFNOR (FR) | NC15FeT | n/a |
| ASTM / ASME | B637 / SB-637 | Precipitation-hardening nickel alloy bars, forgings and forging stock |
| AMS | 5667, 5668, 5669, 5670, 5671, 5747 | Bar, rod, forgings and rings in defined heat-treated conditions |
NCF 750 forgings, Inconel X-750 forgings and UNS N07750 forgings are the same material under different specification systems. We certify to whichever designation appears on the purchase order.
NCF 750 chemical composition
| Element | Min | Max | Role in the alloy |
|---|---|---|---|
| Ni (plus Co) | 70.00 | n/a | Matrix, corrosion resistance and phase stability |
| Cr | 14.00 | 17.00 | Oxidation and hot-corrosion resistance |
| Fe | 5.00 | 9.00 | Deliberate addition, lowers cost and aids workability |
| Ti | 2.25 | 2.75 | Gamma-prime former, main strengthener |
| Al | 0.40 | 1.00 | Gamma-prime former, assists oxide-scale adhesion |
| Nb + Ta | 0.70 | 1.20 | Carbide and gamma-prime former, grain-boundary strength |
| C | n/a | 0.08 | Carbide former, controlled to limit grain growth |
| Mn | n/a | 1.00 | Residual and deoxidiser |
| Si | n/a | 0.50 | Residual and deoxidiser |
| Cu | n/a | 0.50 | Residual |
| Co | n/a | 1.00 | Residual, counted within the nickel total |
| S | n/a | 0.015 | Impurity, controlled against hot shortness |
| P | n/a | 0.030 | Impurity |
Sulphur is limited to 0.015 % max under JIS G4902 and to 0.010 % max under ASTM B637. We melt to the tighter 0.010 % limit by default, so that a single heat satisfies both specifications. Phosphorus is not limited by ASTM B637. Heat analysis and product analysis are reported on the mill test certificate supplied with every order.
NCF 750 heat treatment
Properties depend far more on heat treatment than on small variations in chemistry, so the condition has to be stated on the order. ASTM B637 defines three heat-treated types for UNS N07750 bars and forgings.
| Type | Solution treatment | Stabilising | Precipitation hardening | Intended service |
|---|---|---|---|---|
| Type 1 | 1149 ± 14 °C, 2-4 h, AC | 843 ± 14 °C, 24 h, AC | 704 ± 14 °C, 20 h, AC or FC | Above 593 °C. Maximum creep and stress-rupture strength |
| Type 2 | 982 ± 14 °C, 0.5 h min, AC or faster | n/a | 732 ± 14 °C, 8 h, FC to 621 ± 14 °C, hold to 18 h total, AC | Up to 593 °C. Highest room-temperature tensile and yield strength |
| Type 3 | 1079-1121 °C, 1-2 h, AC | n/a | 704 ± 14 °C, 20-24 h, AC | General purpose. Balanced strength and ductility |
AC = air cool, FC = furnace cool. Equivalent AMS cycles: AMS 5667 (equalise 885 °C for 24 h, age 704 °C for 20 h), AMS 5668 (triple treatment, maximum relaxation resistance above 593 °C), AMS 5669 (annealed only, for hardening after final machining). Heat treatment is carried out in our own charted furnaces and recorded against the heat number.
NCF 750 mechanical properties
| Condition | Tensile strength, min | Yield strength (0.2 %), min | Elongation, min | Reduction of area, min | Brinell hardness |
|---|---|---|---|---|---|
| Type 1 | 965 MPa (140 ksi) | 620 MPa (90 ksi) | 8 % | n/a | 262 HBW min |
| Type 2a (d < 63.5 mm) | 1170 MPa (170 ksi) | 790 MPa (115 ksi) | 18 % | 18 % | 302-363 HBW |
| Type 2b (63.5-101.6 mm) | 1170 MPa (170 ksi) | 790 MPa (115 ksi) | 15 % | 15 % | 302-363 HBW |
| Type 3 | 1103-1276 MPa (160-185 ksi) | 689-896 MPa (100-130 ksi) | 20 % | 20 % | 267-363 HBW |
Stress-rupture requirement for Type 1 material supplied solution treated plus aged: no rupture in less than 100 hours at 732 °C under 310 MPa (45 ksi), with at least 5 % elongation. For large disc forgings over 3226 mm2 in cross-section, test specimens are taken tangentially near the centre, or radially, as agreed on the order.
NCF 750 physical properties
| Property | Value | Unit |
|---|---|---|
| Density | 8.28 | g/cm3 |
| Melting range | 1393-1427 | °C (typical) |
| Specific heat capacity | 431 | J/(kg·K) |
| Thermal conductivity | 12.0 | W/(m·K) |
| Mean coefficient of thermal expansion, 20-100 °C | 12.0 × 10-6 | 1/K |
| Electrical resistivity | 122 | µΩ·cm |
| Magnetic response | Non-magnetic in the aged condition | n/a |
Physical property values are typical for the alloy and are given for design guidance. They are not specification requirements and are not reported on the mill certificate.
NCF 750 forged product range and size capability
The table below is the open-die and ring-rolling envelope of our works in Zhouzhuang Town, Jiangyin. Sizes outside this range can often still be produced by flame cutting from a larger forged block. Send the drawing and we will confirm.
| Forged form | Size range | Typical tolerance | Common use |
|---|---|---|---|
| Seamless rolled rings | OD 200-3000 mm, wall 20-400 mm, height 600 mm max | +6/-0 mm on machining allowance | Turbine casings, retaining rings, bearing races |
| Forged flanges | OD up to 2500 mm | To ASME B16.5, B16.47 or drawing | Pressure vessels, heat exchangers, piping |
| Forged discs and blanks | OD up to 2000 mm, thickness up to 500 mm | +6/-0 mm | Turbine wheels, valve discs, blind flanges |
| Forged round bar | Dia. 50-800 mm, length up to 6000 mm | Black, rough turned or peeled | Fastener stock, machining stock |
| Forged shafts and spindles | Dia. 80-800 mm, length up to 8000 mm | Stepped, to drawing | Pump and compressor rotors, eccentric shafts |
| Sleeves and bushings | OD up to 1200 mm, bored | +4/-0 mm | Subsea equipment, wear parts |
| Tube sheets | Dia. up to 2500 mm | To TEMA or drawing | Shell-and-tube heat exchangers |
| Hollow forgings and forged pipe | OD up to 1200 mm, trepanned or mandrel forged | To drawing | Nozzles, cylinders, valve bodies |
| Single-piece weight | 5 kg to 5000 kg | n/a | n/a |
Minimum order quantity is one piece for parts machined to drawing. Typical lead time for NCF 750 forgings is 30 to 45 days from drawing approval, subject to raw-material availability.
How NCF 750 forgings are manufactured
- Melting. EAF with AOD or VOD refining, followed by electroslag remelting (ESR), for general industrial work. Vacuum induction melting plus vacuum arc remelting (VIM + VAR) where aerospace or nuclear cleanliness levels are specified.
- Homogenisation and cogging. The ingot is soaked and cogged down to break up the as-cast structure. NCF 750 has a narrow hot-working window. Forging runs between roughly 1150 °C and 950 °C with reheats, because the alloy work-hardens quickly and will crack if it is finished cold.
- Open-die forging or ring rolling. Upsetting, drawing out, punching and mandrel expansion on a radial-axial ring mill bring the piece to near-net shape.
- Solution treatment and ageing. To ASTM B637 Type 1, 2 or 3, or to the AMS cycle named on the order.
- Rough machining and inspection. Dimensional check, hardness survey and ultrasonic examination, then final machining if the part is ordered finish machined.
Open-die forging aligns the grain flow with the part contour instead of cutting through it. In a rolled ring the fibre follows the circumference, which raises tangential fatigue and stress-rupture performance. In a gamma-prime strengthened alloy running near 700 °C, that is usually what limits the design.
Testing, inspection and certification
- Chemical analysis. Heat analysis and, on request, product analysis by spectrometer.
- Mechanical testing. Tensile, 0.2 % proof, elongation, reduction of area and Brinell hardness. Charpy V-notch and stress-rupture testing when specified.
- Ultrasonic examination. To EN 10228-3, SEP 1921, ASTM A388 or ASTM A745, acceptance class as stated on the order.
- Surface NDT. Liquid penetrant to ASTM E165. NCF 750 is non-magnetic when aged, so magnetic particle testing does not apply.
- Grain size and microstructure. ASTM E112, with intergranular attack testing where required.
- Certification. EN 10204 3.1 issued by our own quality department, or EN 10204 3.2 countersigned by a third-party inspection body such as SGS, BV, TUV or Lloyd's Register.
- Marking and traceability. Heat number, grade, specification and item number hard stamped or vibro-etched on every piece.
Where NCF 750 forgings are used
| Industry | Typical NCF 750 forged components |
|---|---|
| Gas turbines and aero engines | Rotor blades and wheels, casing rings, bolts, seals, structural members |
| Nuclear power | Fuel-assembly grid springs, hold-down springs, guide pins, jet-pump beams, core internals |
| Oil, gas and subsea | Wellhead and Christmas-tree components, downhole tooling for HPHT wells, subsea sleeves and bushings |
| Valves | Valve stems, seat rings, bodies and blocks for ball, gate, globe, check and plug valves |
| Pressure equipment | Flanges, tube sheets, nozzles and forged shells for heat exchangers and air receivers |
| Rocket and space | Thrust-chamber components and high-temperature structural fasteners |
| Heavy machinery | Extrusion dies, hot-forming tools, heat-treating fixtures, furnace hardware |
| Chemical process | Pump shafts, plunger-pump parts, agitator shafts in chloride-bearing service |
NCF 750 is chosen over stainless steels when the part has to hold load above about 600 °C, and over solid-solution nickel alloys such as Inconel 600 or Inconel 625 when precipitation strength is needed. Toughness also holds up at cryogenic temperature, so the grade shows up in liquefied-gas and space hardware.
NCF 750 compared with Inconel 718
| Aspect | NCF 750 / X-750 | Inconel 718 |
|---|---|---|
| Strengthening phase | Gamma prime, Ni3(Al,Ti) | Gamma double prime, Ni3Nb, plus some gamma prime |
| Room-temp. tensile, aged | 1170 MPa min (Type 2) | 1275 MPa min |
| Practical upper limit | 700 °C sustained, useful to 816 °C | 650 °C, gamma double prime over-ages above this |
| Weldability | Moderate, strain-age cracking risk on heavy sections | Better, sluggish ageing response aids welding |
| Chloride SCC resistance | Excellent when fully aged | Good |
| Relative cost | Lower | Higher |
Above roughly 650 °C, or where chloride stress-corrosion cracking drives the choice, NCF 750 is usually preferred. Below that, Inconel 718 gives higher strength and is easier to weld.
Machining and welding NCF 750
Machining
Machine NCF 750 in the solution-treated condition wherever the design allows. Use rigid setups, positive-rake carbide or ceramic inserts, heavy depth of cut and low surface speed, with flood coolant throughout. The alloy work-hardens quickly. Never let a tool dwell or rub, since a light spring pass does more damage than a deep cut.
Welding
GTAW with ERNiCrFe-7 or matching X-750 filler is the usual route. Weld in the solution-treated condition and age afterwards. Welding fully aged material risks strain-age cracking in the heat-affected zone. Keep interpass temperature low and heat input moderate on sections over about 25 mm.
Frequently asked questions about NCF 750
Is NCF 750 the same as Inconel X-750?
Yes. NCF 750 is the Japanese JIS designation and Inconel X-750 is the Special Metals trade name for the same precipitation-hardening nickel-chromium alloy, covered by UNS N07750 and Werkstoff 2.4669. The chemical limits are effectively identical apart from sulphur, which JIS caps at 0.015 % and ASTM B637 at 0.010 %.
Which standard should I order NCF 750 forgings to?
For bars, forgings and forging stock, order to ASTM B637 or ASME SB-637 and state the heat-treatment type (1, 2 or 3). For Japanese projects, JIS G4901 covers bar and JIS G4902 covers plate, sheet and strip. Aerospace work normally calls out an AMS number such as AMS 5667 or AMS 5668, which fixes both the cycle and the acceptance criteria.
What is the maximum service temperature of NCF 750?
NCF 750 keeps high strength and oxidation resistance to about 704 °C (1300 °F). Above that, precipitation hardening is progressively lost, but heat-treated material still has useful strength to about 980 °C (1800 °F). For sustained loading, high stress-rupture strength and low creep rates are available to roughly 816 °C (1500 °F) after the correct heat treatment.
In which condition are NCF 750 forgings supplied?
By default, solution treated and aged to ASTM B637 Type 1, 2 or 3 as specified on the order. If you plan to precipitation harden the part yourself after final machining, order it in the annealed or solution-treated condition instead, which is the AMS 5669 route.
What forged shapes are available in NCF 750?
Jiangyin Jiangnan Metal produces NCF 750 as seamless rolled rings, flanges, discs and blanks, round bar, shafts and spindles, sleeves and bushings, tube sheets, hollow forgings and forged pipe, valve stems and valve bodies. Rings run to 3000 mm outside diameter and single pieces to about 5000 kg.
Which certificates are supplied with NCF 750 forgings?
Every order ships with an EN 10204 3.1 mill test certificate covering heat analysis, mechanical test results, heat-treatment record, dimensional report and NDT results. EN 10204 3.2 certification countersigned by SGS, BV, TUV or Lloyd's Register is available on request. Ultrasonic examination is reported to EN 10228-3, SEP 1921 or ASTM A388.
Can NCF 750 be welded?
Yes, most commonly by GTAW with a matching X-750 or ERNiCrFe-7 filler. Weld in the solution-treated condition and age afterwards. Welding material that is already fully aged risks strain-age cracking in the heat-affected zone, particularly in sections thicker than about 25 mm.
Who supplies open-die forged NCF 750 in China?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No. 1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, producing NCF 750 forgings alongside other nickel alloys and stainless, tool, alloy and carbon steel grades. Enquiries: +86 189 2135 9659 or sales@steelforgepieces.com.
What information do you need to quote an NCF 750 forging?
A drawing or a rough size (outside diameter, inside diameter, length or thickness), the quantity, the specification and heat-treatment type, whether the part is wanted black, rough machined or finish machined, and any NDT or third-party certification requirements. A dimensioned sketch is enough to start.
What is the lead time for NCF 750 forgings?
Typically 30 to 45 days from drawing approval for open-die and ring-rolled parts, depending on raw-material availability, the heat-treatment cycle and the amount of machining. Repeat orders against an approved drawing are usually faster.
Request a quotation for NCF 750 forgings
Send the drawing, or just the rough size and quantity, and we will come back with a price and a delivery date.
- Company
- Jiangyin Jiangnan Metal Co., Ltd.
- Factory address
- No. 1 Chengxiqiao Road, Zhouzhuang Town,
Jiangyin City, Jiangsu Province, China - Telephone and WhatsApp
- +86 189 2135 9659
Related nickel alloy forging grades
- Inconel 718
- Inconel 706
- Inconel 625
- Inconel 600
- Inconel 601
- Nimonic 80A
- Nimonic 90
- Nimonic 263
- Waspaloy
- Incoloy 925
- Monel K-500
- Udimet 720
About the manufacturer
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No. 1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. The works sits inside the Jiangyin forging cluster on the south bank of the Yangtze, about 90 minutes from Shanghai. We produce seamless rolled rings, flanges, discs, shafts, bars, sleeves, tube sheets and forgings machined to drawing, in carbon steel, alloy steel, tool steel, stainless steel and nickel-based superalloys including NCF 750, and export against EN 10204 3.1 and 3.2 certification.
Page last reviewed by the technical department of Jiangyin Jiangnan Metal Co., Ltd.