Summary
What is KC20WN?
KC20WN is the European (DIN/ISO) designation for a solid-solution-strengthened cobalt-chromium-tungsten-nickel superalloy containing nominally 20 % Cr, 15 % W, 10 % Ni and 0.10 % C, with cobalt as the balance. It is the same material as Alloy L-605, Haynes 25, UNS R30605 and W.Nr. 2.4964. The alloy retains useful strength in continuous service to about 980 °C (1800 °F), resists oxidation to roughly 1040 °C, and resists sulfidation, wear and galling.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin, Jiangsu, China. It produces KC20WN forgings to customer drawing in rolled-ring, flange, shaft, disc, sleeve, bushing, tube-sheet and valve-part form. Enquiries: sales@steelforgepieces.com or 0086-189-2135-9659.
Last reviewed 21 August 2026. Technical content maintained by the Jiangyin Jiangnan Metal engineering team.
KC20WN equivalents and cross-reference
This alloy appears on drawings under several different names, depending on whether the drawing follows a European, American or Chinese standard. All of the designations listed below refer to the same Co-20Cr-15W-10Ni chemistry. Jiangyin Jiangnan Metal quotes against any of them, so use whichever designation your drawing carries.
| System / region | Designation | Notes |
|---|---|---|
| DIN / ISO (Europe) | KC20WN, CoCr20W15Ni | The designation used on this page |
| Werkstoff-Nr. | 2.4964 | German material number |
| UNS (USA) | R30605 | Unified Numbering System |
| Common trade names | Alloy L-605, Haynes 25, Stellite 25, HS-25, Udimet L-605, Alacrite | Trademarks of their respective owners |
| AISI | 670 | Legacy US designation |
| China (GB/T 14992) | GH5605, GH605 | Also written GH25 |
| France | Conicro 5010W | |
| Aerospace specs | AMS 5759 (bar, billet, forgings), AMS 5537 (sheet, strip, plate), AMS 5796 / 5797 (weld filler) | SAE International |
| Medical / implant | ASTM F90 | Bar and wire, surgical implant quality |
| Sour service | NACE MR0175 / ISO 15156 | Where specified by the purchase order |
Sources: SAE AMS 5759 and AMS 5537, ASTM F90, GB/T 14992 and published mill datasheets. Trade names are the property of their respective owners. Jiangyin Jiangnan Metal supplies to the chemistry and specification, not under any licensed trade name.
Chemical composition of KC20WN
The chemical composition of KC20WN (UNS R30605) is controlled to the limits below, in weight percent. Jiangyin Jiangnan Metal melts KC20WN by EAF + VOD followed by ESR (electroslag remelting) to keep sulphur and gas content low and to produce a clean ingot with low segregation, which is necessary when open-die forging an alloy that contains 15 % tungsten.
| Element | Symbol | Min % | Max % |
|---|---|---|---|
| Cobalt | Co | Balance | |
| Chromium | Cr | 19.00 | 21.00 |
| Tungsten | W | 14.00 | 16.00 |
| Nickel | Ni | 9.00 | 11.00 |
| Manganese | Mn | 1.00 | 2.00 |
| Carbon | C | 0.05 | 0.15 |
| Iron | Fe | 3.00 | |
| Silicon | Si | 0.40 | |
| Phosphorus | P | 0.040 | |
| Sulphur | S | 0.030 | |
Limits per AMS 5759 and UNS R30605. The certified ladle and product analysis for your heat is issued with every shipment.
Mechanical and physical properties
KC20WN is the strongest of the fabricable cobalt alloys. In the solution-annealed condition it gives roughly 1000 MPa tensile strength at 50 to 60 % elongation, which is what allows it to be formed at all. The alloy is not age hardenable. Strength comes from tungsten in solid solution and from cold work, and it work-hardens rapidly.
| Property | Typical value | Imperial |
|---|---|---|
| Tensile strength (UTS) | 950 to 1030 MPa | 138 to 149 ksi |
| Yield strength, 0.2 % offset | 440 to 510 MPa | 64 to 74 ksi |
| Elongation in 4D | 50 to 60 % | 50 to 60 % |
| Hardness, annealed | approx. 95 HRB | approx. 240 HV |
| Modulus of elasticity | 225 GPa | 32.6 x 106 psi |
| Density | 9.13 g/cm3 | 0.330 lb/in3 |
| Melting range | 1329 to 1410 °C | 2425 to 2570 °F |
| Mean CTE, 20 to 100 °C | 12.3 um/m·K | 6.8 uin/in·°F |
| Thermal conductivity, 20 °C | 9.4 W/m·K | 65 Btu·in/h·ft²·°F |
| Magnetic response | Non-magnetic, including after cold work | |
Indicative values only, not for design. Properties vary with section size, forging reduction and heat-treat route. Jiangyin Jiangnan Metal issues actual certified test results for each heat and each forging lot. Request the mill test report before finalising a design.
Service temperature guidance
- Continuous service: useful strength to approximately 980 °C (1800 °F).
- Oxidation resistance: good in oxidising atmospheres to roughly 1040 °C (1900 °F).
- Short excursions: measurable strength is retained to about 1095 °C (2000 °F).
- Sulfidation and galling: among the best of the wrought high-temperature alloys.
Forging and heat treatment of KC20WN
KC20WN can be open-die forged, hot worked or cold worked. The tungsten content makes it stiff at temperature and it work-hardens rapidly, so reheats are frequent and reduction per pass is kept modest. Jiangyin Jiangnan Metal forges KC20WN on hydraulic open-die presses, with ring-rolling capability for seamless rings.
| Operation | Temperature | Practice |
|---|---|---|
| Soak before forging | approx. 1205 °C / 2200 °F | Hold until the whole section is uniformly at temperature |
| Hot working range | 1150 to 1230 °C | Reheat as required, finish at the lower end to control grain size |
| Solution anneal | 1175 to 1230 °C / 2150 to 2250 °F | Rapid air cool or water quench |
| Stress relief after cold work | 400 to 450 °C | 2 h, air cool |
| Ageing | Not applicable. KC20WN is solid-solution strengthened and is not age hardenable | |
Low-temperature annealing is avoided because it precipitates carbides. All hot-worked and cold-worked KC20WN parts are annealed and rapidly cooled to restore the balance of properties.
Welding
KC20WN is welded by GTAW, GMAW, SMAW, electron beam and resistance welding, using matching filler to AMS 5796 (wire) or AMS 5797 (coated electrode). Submerged-arc welding is not recommended. Use good joint fit-up, minimum restraint, a low interpass temperature and rapid cooling from welding. Post-weld solution annealing restores ductility.
KC20WN forged product forms we supply
All items below are made to customer drawing. Jiangyin Jiangnan Metal does not hold standard KC20WN stock, since the alloy is melted against the order. Send a drawing, a sketch, or finished dimensions plus a machining allowance, and we quote from that.
| Forged form | Size range | Typical use |
|---|---|---|
| Seamless rolled rings | OD 200 to 2500 mm, H up to 600 mm | Turbine casing rings, combustor rings, bearing races |
| Forged flanges | To drawing | Pressure vessel and heat-exchanger connections |
| Forged discs and blanks | OD 100 to 1200 mm | Turbine discs, valve discs, blank stock for machining |
| Forged round bar | Dia. 50 to 500 mm, L up to 4000 mm | Machining stock, fasteners, spindles |
| Forged shafts and eccentric shafts | Dia. 80 to 500 mm, L up to 5000 mm | Chemical and plunger pumps, compressors, gearboxes |
| Sleeves and bushings | OD 100 to 1200 mm | Wear surfaces, galling-prone assemblies |
| Tube sheets and forged tubes | To drawing | Shell-and-tube heat exchangers, air receivers |
| Valve bodies, seat rings, stems, blocks | To drawing | Ball, gate, globe, check and plug valves |
| Nozzles, manifolds, forging rolls, wheels | To drawing | Process units, wellhead and Christmas tree equipment |
| Single-piece weight | 5 kg to 3000 kg | Heavier pieces on enquiry |
Confirm the limits for your specific geometry with sales@steelforgepieces.com.
Where KC20WN forgings are used
KC20WN is specified where the service condition rules out stainless steel: high temperature in an oxidising or sulphidising atmosphere, sliding contact that would gall a stainless part, or an assembly that has to stay non-magnetic. The industries listed below account for most of the KC20WN forgings Jiangyin Jiangnan Metal ships.
| Industry | Components forged in KC20WN |
|---|---|
| Aero and industrial gas turbines | Combustor cans and liners, transition ducts, spray bars, flame holders, afterburner liners, nozzle diaphragms, turbine rings and blades |
| Oil, gas and offshore | Subsea and deepwater production hardware, wellhead and Christmas-tree parts, manifolds, forged nozzles |
| Valves and flow control | Valve seat rings, stems, blocks and bodies for ball, check, globe, gate, plug and strainer service |
| Pressure vessels and heat exchangers | Forged flanges, tube sheets, forged tubes, air receiver components, shell-and-tube parts |
| Chemical and petrochemical | Chemical pump and plunger pump shafts, crystalliser equipment, processing unit hardware |
| Power generation | Rotor and generator parts, nitrogen generators, industrial air compressor components |
| Power transmission and heavy machinery | Gears, spindles, forging rolls, wheels, crankshafts, gearbox parts |
| Marine, pulp and pharmaceutical | Shipbuilding hardware, paper and pulp machinery, pharmaceutical and biochemical process parts |
| Medical | Implant-quality bar and wire stock to ASTM F90, heart valve components |
How we make and verify a KC20WN forging
A KC20WN order passes through the six stages below. Omitting ESR or the post-forge solution anneal does not show up in dimensional inspection, but it does show up in service.
Testing, NDT and certification
Jiangyin Jiangnan Metal ultrasonically tests KC20WN forgings to the standard nominated on the purchase order, and supplies a material certificate with every shipment.
- Ultrasonic testing: EN 10228-3, SEP 1921, ASTM A388 or an equivalent customer standard, to the acceptance class you specify.
- Surface NDT: liquid penetrant (PT) or magnetic particle where applicable. KC20WN is non-magnetic, so PT is normally the correct method.
- Chemical analysis: ladle and product analysis by spectrometer.
- Mechanical testing: tensile, hardness and impact as specified, with test coupons cut from prolongations integral to the forging where the specification requires it.
- Grain size and microstructure: on request, with photomicrographs.
- Material certificate: EN 10204 3.1 as standard, or EN 10204 3.2 countersigned by an independent third party.
- Marking and traceability: heat number, lot number and specification hard-stamped or vibro-etched on each piece.
Frequently asked questions about KC20WN forgings
Is KC20WN the same alloy as L-605 and Haynes 25?
Yes. KC20WN, Alloy L-605, Haynes 25, Stellite 25, HS-25, Udimet L-605, UNS R30605, W.Nr. 2.4964, AISI 670 and GH5605 all describe the same Co-20Cr-15W-10Ni composition. KC20WN is the European DIN/ISO designation. Jiangyin Jiangnan Metal quotes any of these designations against the same chemistry.
Is KC20WN a nickel alloy or a cobalt alloy?
KC20WN is a cobalt-base superalloy. Cobalt is the balance of the composition and nickel is present at only 9 to 11 %. It is commonly catalogued alongside nickel alloys because buyers group the wrought superalloys together, but its metallurgy is cobalt-alloy metallurgy: solid-solution strengthening by tungsten, with no ageing response.
What is the maximum service temperature of KC20WN?
KC20WN holds useful strength in continuous service to about 980 °C (1800 °F) and resists oxidation to roughly 1040 °C (1900 °F). It retains measurable strength to about 1095 °C (2000 °F) for short excursions. Avoid long dwells between 760 °C and 925 °C, where Laves phase precipitation reduces room-temperature ductility.
Which KC20WN forged shapes can Jiangyin Jiangnan Metal produce?
Jiangyin Jiangnan Metal open-die forges KC20WN into seamless rolled rings, flanges, discs, round bar, shafts and eccentric shafts, sleeves, bushings, tube sheets, forged tubes, valve seat rings, valve bodies and stems, nozzles, manifolds, forging rolls, wheels and crankshafts. All are made to customer drawing rather than to a stock catalogue.
Which standards and specifications do the forgings meet?
Chemistry and mechanical properties are supplied to AMS 5759 for bar, billet and forgings, or to UNS R30605, W.Nr. 2.4964 or ASTM F90 where your drawing calls for those. Ultrasonic acceptance follows EN 10228-3, SEP 1921 or ASTM A388. Certificates are issued to EN 10204 3.1 or 3.2.
How is KC20WN forged and heat treated?
The billet is soaked at approximately 1205 °C (2200 °F) until the whole section is uniformly at temperature, then open-die forged or ring-rolled within a 1150 to 1230 °C window with reheats as required, finishing at the lower end of the range to control grain size. Forgings are then solution annealed at 1175 to 1230 °C and rapidly cooled. KC20WN is not age hardenable.
Can KC20WN be welded and machined?
KC20WN welds by GTAW, GMAW, SMAW, electron beam and resistance welding with matching filler to AMS 5796 or AMS 5797. Submerged-arc welding is not recommended. Machining is possible with conventional techniques, but the alloy work-hardens rapidly, so use rigid setups, positive feed and sharp tooling, and do not let the tool dwell.
What certification comes with a KC20WN order?
Every KC20WN forging ships with an EN 10204 3.1 mill certificate covering heat number, chemical analysis, heat-treat condition, mechanical test results and NDT results. An EN 10204 3.2 certificate countersigned by an independent inspection body is available when the purchase order requires it.
Is there a minimum order quantity for KC20WN forgings?
KC20WN forgings are made to order and single prototype pieces are accepted, so there is no fixed minimum quantity. Because the alloy is melted to order, the practical minimum is usually set by the ingot size needed for your part. Send the drawing and Jiangyin Jiangnan Metal will confirm the minimum melt and the lead time for that specific geometry.
How do I get a price for a KC20WN forging?
Email the drawing or the finished dimensions to sales@steelforgepieces.com, or call 0086-189-2135-9659. Include quantity, the specification to be certified against, the required delivery condition and any NDT class. Jiangyin Jiangnan Metal is at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China.
Request a KC20WN quotation
Send the size or the drawing of the KC20WN forging you need. We quote to that drawing, with the specification, NDT class and certificate level you nominate.
- 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
- sales@steelforgepieces.com
- Website
- www.steelforgepieces.com
Related superalloy forgings
Alloys most often compared against KC20WN during material selection. All are open-die forged to drawing by Jiangyin Jiangnan Metal.
- Haynes 25 forgingsSame chemistry, US trade name
- Multimet N155 forgingsFe-Ni-Co, lower cost
- Hastelloy X forgingsNi-base, combustor duty
- Inconel 617 forgingsNi-Cr-Co, 1000 C service
- Inconel 625 forgingsNi-base, corrosion service
- Inconel 718 forgingsAge-hardened, high strength
- Waspaloy forgingsAge-hardened turbine discs
- Rene 41 forgingsNi-base, high-temp strength
- MP35N forgingsCo-Ni, ultra-high strength
- MP159 forgingsCo-Ni-Cr, fasteners
- Inconel X-750 forgingsSprings and rings
- Incoloy 800HT forgingsFe-Ni-Cr, creep service