JIS G4902 nickel-chromium-molybdenum alloy
NCF 625 is the JIS G4902 designation for the nickel-chromium-molybdenum-niobium alloy also written as UNS N06625, Alloy 625, Inconel 625 and W.Nr. 2.4856. Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu, China. We forge NCF 625 into seamless rolled rings, flanges, bars, shafts, discs, sleeves and tube sheets, solution annealed, ultrasonically tested, and certified to EN 10204 3.1 or 3.2.
NCF 625 equivalents. We quote against any of these designations.
NCF 625 is a solid-solution-strengthened nickel alloy. Molybdenum and niobium dissolved in the nickel-chromium matrix carry the strength rather than a hardening heat treatment, so the alloy holds its properties from cryogenic temperature up to about 980 °C. The same chemistry makes it resistant to chloride stress-corrosion cracking, pitting and crevice attack in seawater, sour gas, and both oxidising and reducing acids.
Open-die forging closes the porosity left by casting, refines grain size, and aligns grain flow with the principal stress direction of the part. A forged NCF 625 flange or ring is denser and tougher than the same shape cut from plate or bar stock, and it gives cleaner ultrasonic results.
Jiangyin Jiangnan Metal Co., Ltd. produces NCF 625 as custom open-die forgings and seamless rolled rings. We work to drawing rather than from a stock catalogue, and there is no tooling charge for standard open-die shapes. Send a drawing or the finished dimensions and we forge to that print.
Drawings from different countries call this alloy by different names. All of the designations below cover the same UNS N06625 chemistry.
| Standard or region | Designation | Product form covered |
|---|---|---|
| JIS (Japan) | NCF 625 | G4902 plate and sheet; G4901 bar; G4903 pipe; G4904 tube |
| UNS (USA) | N06625 | All forms |
| ASTM / ASME | B564 / SB-564 | Nickel alloy forgings, the usual specification for forged parts |
| ASTM | B446 | Bar and rod |
| ASTM | B443 | Plate, sheet and strip |
| Werkstoff (Germany) | 2.4856 | All forms |
| DIN / EN name | NiCr22Mo9Nb | All forms |
| AFNOR (France) | NC22DNb | All forms |
| BS (UK) | NA 21 | All forms |
| ISO | NW6625 | All forms |
| GB (China) | NS3306 / GH3625 | All forms |
| Trade names | Inconel 625, Nicrofer 6020 hMo, Chronin 625, Haynes 625, Altemp 625 | All forms |
| Sour service | NACE MR0175 / ISO 15156-3 | Compliant material available on request |
Inconel is a registered trademark of Special Metals Corporation. Nicrofer is a registered trademark of VDM Metals. Haynes is a registered trademark of Haynes International. These names are listed for cross-reference only. Jiangyin Jiangnan Metal is not affiliated with or endorsed by those companies.
| Element | Min | Max | Role in the alloy |
|---|---|---|---|
| Ni (nickel) | 58.0 | - | Austenitic matrix, SCC resistance |
| Cr (chromium) | 20.0 | 23.0 | Oxidation and pitting resistance |
| Mo (molybdenum) | 8.0 | 10.0 | Crevice and reducing-acid resistance |
| Nb + Ta (niobium, tantalum) | 3.15 | 4.15 | Solid-solution strengthening, carbide stabilisation |
| Fe (iron) | - | 5.0 | Residual |
| C (carbon) | - | 0.10 | Restricted to limit carbide precipitation |
| Si (silicon) | - | 0.50 | Residual from deoxidation |
| Mn (manganese) | - | 0.50 | Residual |
| Al (aluminium) | - | 0.40 | Deoxidiser |
| Ti (titanium) | - | 0.40 | Deoxidiser, carbide and nitride former |
| Co (cobalt) | - | 1.0 | Residual, restricted for nuclear service |
| P (phosphorus) | - | 0.015 | Impurity |
| S (sulphur) | - | 0.015 | Impurity, controlled for hot workability |
Actual heat analysis is reported per heat number on the EN 10204 certificate. Tighter internal limits can be agreed at order, for example cobalt 0.10% max for nuclear service, or restricted niobium for weld-overlay compatibility.
| Condition | 0.2% proof stress | Tensile strength | Elongation | Hardness |
|---|---|---|---|---|
| Solution annealed (Grade 2, 1090 °C min) |
275 N/mm² min | 690 N/mm² min | 30% min | typ. 75-95 HRB |
| Annealed (Grade 1, 870-1040 °C) |
379 N/mm² min | 758 N/mm² min | 30% min | 35 HRC max |
Grade 1 is the normal choice for service below about 600 °C and for NACE MR0175 sour-service applications, where the 35 HRC cap applies. Grade 2 is specified where creep strength above 600 °C governs. State the grade on the enquiry. If it is not stated, parts are supplied solution annealed.
| Property | Value |
|---|---|
| Density | 8.44 g/cm³ (0.305 lb/in³) |
| Melting range | 1290-1350 °C |
| Modulus of elasticity | 207.5 GPa |
| Thermal conductivity | 9.8 W/m·K |
| Mean coefficient of thermal expansion, 20-100 °C | 12.8 µm/m·K |
| Specific heat capacity | 410 J/kg·K |
| Electrical resistivity | 1.29 µΩ·m |
| Magnetic permeability at 20 °C | 1.0006, non-magnetic |
| Curie temperature | below -196 °C |
All shapes below are produced in NCF 625 as open-die forgings or seamless rolled rings, made to drawing. Contact us with the finished dimensions to confirm the size range for a specific part.
Each stage below generates a record that appears on the material certificate.
EAF with AOD or VOD refining, followed by electroslag remelting to control segregation and inclusion content. VIM plus ESR or VIM plus VAR is available for aerospace and critical service.
Heat analysis confirmed by spectrometer before the ingot is released. Hot top and bottom cropped.
Soaked and forged between 1150 °C and 1200 °C, finishing above 950 °C. Reduction ratio and upsetting sequence are set so that grain flow follows the loaded direction of the part.
Ring geometries are pierced and then rolled to a seamless ring. Grain flow runs circumferentially, which a ring cut from plate cannot reproduce.
Annealed at 870-1040 °C for Grade 1, or solution annealed at 1090-1200 °C for Grade 2, then rapid cooled. Charts and furnace records are retained per heat-treatment lot.
Turned, bored, faced or drilled to the agreed condition: as-forged, rough machined with allowance, or fully finished to your print.
Ultrasonic testing after heat treatment and rough machining, plus liquid penetrant testing and positive material identification. NCF 625 is non-magnetic, so PT replaces magnetic particle inspection.
Hard-stamped or vibro-etched with heat number and part number, then released against an EN 10204 3.1 or 3.2 certificate.
Supplied with every NCF 625 forging
| Industry | Typical NCF 625 forged components | Reason for the alloy |
|---|---|---|
| Offshore and subsea oil and gas | Wellhead and Christmas tree bodies, hubs, connectors, hangers, forged blocks | Sour service, seawater, chloride SCC immunity |
| Valves | Bodies, bonnets, seat rings, stems, balls, gates, plugs | Erosion and corrosion resistance, NACE compliance |
| Chemical and petrochemical | Reactor nozzles, flanges, tube sheets, agitator shafts, pump parts | Mixed oxidising and reducing acid duty |
| Pressure vessels and heat exchangers | Tube sheets, shell flanges, nozzles, forged heads, air receivers | ASME code service at elevated temperature |
| Flue-gas desulphurisation | Scrubber internals, forged rings, dampers | Wet acid chloride condensate |
| Power generation | Turbine seal rings, gas compressor parts, fasteners, gearbox rings | Creep and oxidation strength above 600 C |
| Marine and shipbuilding | Propulsion shafts, sleeves, seawater pump bodies | Seawater and crevice corrosion |
| Pulp, paper and bleaching | Digester hardware, rolls, forged discs | Chlorine dioxide and organic acids |
| Pharmaceutical and biochemical | Crystalliser parts, agitator shafts, sanitary flanges | Cleanability and product purity |
| Aerospace and nuclear | Bellows blanks, ducting rings, structural forgings | Cryogenic to high-temperature strength, low cobalt on request |
NCF 625 is the Japanese Industrial Standard designation for a nickel-chromium-molybdenum-niobium alloy containing at least 58% nickel, 20-23% chromium, 8-10% molybdenum and 3.15-4.15% niobium plus tantalum. It is specified in JIS G4902 and is the same material as UNS N06625, Alloy 625 and W.Nr. 2.4856. NCF 625 combines high strength with resistance to pitting, crevice corrosion, chloride stress-corrosion cracking and oxidation, from cryogenic temperature up to about 980 °C.
Yes. NCF 625 and Inconel 625 describe the same alloy chemistry, UNS N06625. NCF 625 is the JIS designation used in Japan, Inconel 625 is a registered trade name of Special Metals Corporation, and 2.4856 is the German Werkstoff number. Jiangyin Jiangnan Metal Co., Ltd. supplies forgings in this alloy against whichever designation and standard your drawing calls out.
Per JIS G4902: carbon 0.10% max, silicon 0.50% max, manganese 0.50% max, phosphorus 0.015% max, sulphur 0.015% max, nickel 58.0% min, chromium 20.0-23.0%, molybdenum 8.0-10.0%, niobium plus tantalum 3.15-4.15%, iron 5.0% max, aluminium 0.40% max, titanium 0.40% max and cobalt 1.0% max. This composition is identical to UNS N06625 in ASTM B443, B446 and B564.
Solution annealed as Grade 2, NCF 625 forgings meet a minimum tensile strength of 690 N/mm², a minimum 0.2% proof stress of 275 N/mm² and a minimum elongation of 30%. Annealed as Grade 1, the minima are 758 N/mm² tensile, 379 N/mm² proof stress and 30% elongation. Grade 1 is used up to about 600 °C. Grade 2 is specified where creep resistance above 600 °C is required.
Jiangyin Jiangnan Metal produces NCF 625 in open-die and ring-rolled form: seamless rolled rings, forged flanges, round bars, shafts, spindles, discs, blanks, sleeves, bushings, hollow cylinders, tube sheets, nozzles, valve bodies, valve seat rings, valve stems, blocks and custom shapes made to drawing. There is no tooling charge for standard open-die shapes.
NCF 625 is melted by electric arc furnace with AOD or VOD refining followed by electroslag remelting. VIM plus ESR or VIM plus VAR is available for aerospace and critical service. Alloy 625 is solid-solution strengthened, so it is supplied annealed at 870-1040 °C or solution annealed at 1090-1200 °C and rapid cooled. Ageing is not standard practice for corrosion service because it lowers ductility and corrosion resistance.
Every forging ships with a chemical analysis by heat, mechanical test results, heat-treatment records and traceable heat and part numbers. Ultrasonic testing is carried out to ASTM A388, SEP 1921 or EN 10228-3 acceptance classes by agreement, with liquid penetrant testing to ASTM E165 and positive material identification. Certification is issued to EN 10204 3.1, or EN 10204 3.2 with third-party witness by BV, SGS, TUV, Lloyd's Register or DNV.
Offshore and subsea oil and gas production, wellhead and Christmas tree components, valves and valve internals, chemical and petrochemical process plant, pressure vessels and shell-and-tube heat exchangers, flue-gas desulphurisation, seawater and marine equipment, power generation and turbine hardware, pulp and paper, pharmaceutical and biochemical plant, and nuclear and aerospace components.
Jiangyin Jiangnan Metal Co., Ltd. operates an open-die forging plant at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. Jiangyin is on the Yangtze River in the Suzhou, Wuxi and Changzhou industrial belt, about 30 km from Zhangjiagang Port and 150 km from the Port of Shanghai. Enquiries: +86 189 2135 9659 or sales@steelforgepieces.com.
Send a drawing or the finished dimensions to sales@steelforgepieces.com with the quantity, the specification you need (NCF 625, UNS N06625, Alloy 625 or 2.4856), the delivery condition of as-forged, rough machined or finish machined, the required test scope and the certification level. Jiangyin Jiangnan Metal returns a price and lead time, normally within one working day.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China. The plant forges custom parts and seamless rolled rings in carbon steel, alloy steel, tool steel, stainless steel and nickel alloys, including NCF 625, Inconel 625, NCF 690, Alloy 600 (2.4816) and Alloy 718 (2.4668), and supplies them to buyers in the oil and gas, valve, chemical process, power generation, marine and heavy machinery sectors worldwide.
All work is made to drawing. Parts are released against EN 10204 3.1 or 3.2 certification with heat-to-part traceability, and customer or third-party source inspection is accepted at any stage of production.
Send the grade, the finished dimensions or the drawing, the quantity, the delivery condition and the certification level. We reply with a price and a lead time, normally within one working day.
