CoCr22NiW Forgings UNS R30188 · W.Nr. 2.4683 · AMS 5772 · Alloy 188 · Co-22Cr-22Ni-14W

What is CoCr22NiW?

CoCr22NiW is a wrought cobalt-base superalloy strengthened by dissolved tungsten rather than by precipitation. There is no γ′ or γ″ phase to over-age, so it holds its properties through very long high-temperature exposures instead of gradually softening. That behaviour is what keeps it serviceable in the hottest sections of gas turbines.

The name follows European chemical-symbol convention: Co base, Cr 22 % chromium, plus Ni and W as the other major additions. The role of each element:

Where CoCr22NiW sits on the temperature scale

Below 650 °C a cheaper stainless steel will usually do the same job. Between 650 °C and 980 °C CoCr22NiW earns its cost on creep strength. Above 980 °C it is chosen for oxidation and hot-corrosion survival rather than for load capacity.

The solid-solution mechanism has two practical consequences. There is no aging step, so CoCr22NiW forgings ship solution heat treated and there is no H-condition or precipitation cycle to specify. And the alloy work hardens rapidly, so forging schedules need frequent reheats and machining needs rigid setups and positive feed.

The alloy also has a limitation worth stating plainly. After thousands of hours between roughly 650 °C and 870 °C, a Co₂W Laves phase precipitates and reduces room-temperature ductility and impact toughness. CoCr22NiW tolerates this far better than the earlier UNS R30605, but for a part that must stay tough after a decade in service, a nickel alloy such as UNS N06230 is a better answer. We will say so at quotation rather than sell the wrong grade.

What are the equivalent designations for CoCr22NiW?

Engineers reach this alloy through half a dozen different names depending on which standards body, OEM or datasheet they started from. Every designation in the table below refers to the same chemistry, and Jiangyin Jiangnan Metal Co., Ltd. accepts purchase orders under any of them, supplying UNS R30188 / AMS 5772 material with a multi-designation certificate.

Verify the specification revision in force at your contract date. Standards are periodically re-issued and a revision letter change can alter test requirements even when the chemistry is unchanged.

What is the chemical composition of CoCr22NiW?

The table gives the AMS 5772 / UNS R30188 specification limits alongside the nominal aim chemistry. Cobalt is the balance rather than a controlled range, so on a certificate you will see it reported as the remainder after every other element is analysed.

What are the mechanical properties of CoCr22NiW?

CoCr22NiW is supplied solution heat treated. There is no aging condition to choose, so the numbers below apply to material in the as-supplied state. Values are typical for hot-worked and solution-annealed product; AMS 5772 minimums, which are what your certificate is judged against, sit below these figures.

Note the elongation column. Ductility rises with temperature, from about 50 % at room temperature to roughly 100 % at 871 °C. This is what makes a 14 % tungsten alloy formable at all, and the reason hot working must stay inside the recommended range.

Hardness and impact

Creep and stress-rupture strength

Above about 650 °C, creep rather than yield governs design. The values below are approximate initial stresses producing 1 % creep in 1,000 hours in solution-annealed plate, the figure most often used for a first sizing pass.

Compared with solid-solution-strengthened nickel alloys such as UNS N06625 or N06002, CoCr22NiW carries meaningfully more stress at the same temperature, which often allows a thinner section. Against simple Ni-Cr and Fe-Ni-Cr heat-resisting alloys the margin is very large. Substituting CoCr22NiW commonly permits a substantial reduction in wall thickness, which is part of how the higher price per kilogram is recovered.

What are the physical properties of CoCr22NiW?

How does CoCr22NiW resist oxidation, hot corrosion and sulfidation?

Environmental resistance is the usual reason this alloy is specified. Three separate mechanisms attack hot gas-path hardware. CoCr22NiW is unusually good at two of them and respectable at the third.

Oxidation in air and combustion gas

CoCr22NiW can be used for long-term continuous exposure to oxidising air and combustion gas up to 1095 °C (2000 °F), with short excursions permitted above that. In comparative 1,000-hour flowing-air testing at 980 °C it shows very low metal loss, among the best of the wrought high-temperature alloys. Above roughly 1150 °C the advantage disappears and nickel alloys such as UNS N06230 pull ahead, so 1095 °C is a real ceiling rather than a conservative one.

Under cyclic burner-rig conditions the lanthanum addition shows its value most clearly: metal loss after 1,000 hours of 30-minute cycles at 980 °C is lower than for the common nickel alternatives, because the scale stays attached through each thermal cycle instead of spalling and re-forming at the expense of the chromium reservoir.

Sulfate-deposit hot corrosion

Hot corrosion (sulfate deposits formed when sulfur in the fuel combines with ingested sodium chloride) is what destroys marine and industrial turbine hardware. CoCr22NiW has excellent resistance here, outperforming UNS N06625, N06002 and N06230 in standard 1,000-hour burner-rig tests at 900 °C with salt injection. For marine gas turbines and for engines burning higher-sulfur fuel, this is usually the deciding property.

Gaseous sulfidation and molten chloride salts

The cobalt matrix gives good resistance to reducing sulfidising gas, where nickel alloys form low-melting nickel sulfide eutectics. CoCr22NiW also resists molten chloride salts well, so it appears in concentrated solar power receivers, molten-salt heat storage and chloride-salt process equipment. UNS R30605 is slightly better in gaseous sulfidation specifically. If that single mechanism dominates your application, say so and we will discuss both grades.

How does CoCr22NiW compare with Alloy 25, 230, X and 625?

Five alloys compete for the same hot-section jobs. CoCr22NiW leads on hot corrosion and cyclic oxidation, UNS N06230 leads on long-term stability, and UNS N06625 leads on price and fabricability at lower temperatures.

How is CoCr22NiW forged and heat treated?

CoCr22NiW forges well, but only inside a narrow window. Two rules matter above all others: soak long enough that the whole section reaches temperature, and stop working before the piece cools into the work-hardening regime.

Hot working

• Start temperature 1175 °C (2150 °F), held long enough for the full cross-section to reach temperature. On heavy sections this is measured in hours, not minutes. A cold core is the most common cause of internal bursts in this grade.
• Finish above roughly 1010 °C. Below that the alloy work hardens sharply and the risk of cracking rises steeply. Reheat rather than push one more blow.
• Take moderate reductions with frequent reheats. Tungsten-strengthened cobalt alloys do not tolerate heavy single-stroke reduction the way carbon steel does.
• Target a forging ratio of at least 4:1 to break down the as-cast structure and produce the grain flow that AMS 5772 acceptance depends on.
• Anneal and cool rapidly after all hot or cold work to restore the best balance of properties.

Solution heat treatment

The standard condition is solution treatment at 1177 °C ± 14 °C (2150 °F ± 25 °F), that is 1163–1191 °C, soaked for a time appropriate to section thickness, then rapid air cooled or water quenched. Rapid cooling is not optional. It is what keeps the carbides in solution. Bright-annealed product is cooled in hydrogen.

Strengthening by cold work

Although CoCr22NiW cannot be precipitation hardened, it responds strongly to cold deformation, which is the only route to higher strength in this grade. Cold reduction raises yield strength dramatically: roughly 20 % reduction takes 0.2 % yield from about 460 MPa to 915 MPa, and 40 % reduction takes it beyond 1,200 MPa, at the cost of elongation falling from about 54 % to under 10 %.

The cold-worked structure can be further strengthened by aging near 540 °C (1000 °F) for 4 to 16 hours. This is a stabilising treatment on a cold-worked structure, not a precipitation-hardening cycle on solution-annealed material. The distinction causes real confusion on drawings. If you need CoCr22NiW in a cold-worked and aged condition rather than solution annealed, state it explicitly on the order, because it is not the default supply condition.

Process route at Jiangyin Jiangnan Metal

Welding and machining CoCr22NiW

Welding

CoCr22NiW is readily welded by GTAW (TIG), GMAW (MIG), SMAW, electron beam and resistance welding, and it behaves well under restraint. Practical guidance:

• Filler: matching UNS R30188 composition (AMS 5801) for most joints. For sections above about 9.5 mm, a nickel-chromium-tungsten-molybdenum filler is often preferred.
• Preheat: not required. Room-temperature shop conditions are normal.
• Interpass temperature: keep below about 95 °C (200 °F).
• Post-weld heat treatment: not generally required.
• Cleanliness: remove all grease, marking crayon and sulfur-bearing residue before welding, and keep copper and copper-bearing tooling away from the joint.
• Avoid submerged arc welding. High heat input and slow cooling raise restraint and promote cracking.

Machining

Machining CoCr22NiW is closer to machining a nickel superalloy than a stainless steel, and the work-hardening behaviour dominates. What works:

• Rigid setup, minimum overhang, sharp positive-rake carbide tooling.
• Never dwell. Maintain positive feed at all times. A rubbing tool glazes the surface, and the next pass has to cut through a work-hardened layer.
• Low cutting speed with heavy feed, generous flood coolant.
• Peck-drilling cycles for depth, and roughing done before final solution treatment where the geometry allows.
• Allow for tool life measured in minutes, not hours, and budget machining time accordingly. It is a real cost line on any CoCr22NiW component.

We supply CoCr22NiW rough-machined or finish-machined to drawing. On complex geometry it is usually cheaper to have the forging house machine the part than to ship an oversized forging and machine away expensive cobalt alloy elsewhere.

CoCr22NiW forging capability at Jiangyin Jiangnan Metal

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China, with 460 employees including 9 senior engineers and 32 intermediate engineers. We forge CoCr22NiW / UNS R30188 to AMS 5772 alongside our nickel alloy and stainless steel programmes.

Product forms available in CoCr22NiW

• Seamless rolled rings
• Contoured rolled rings
• Forged discs & hubs
• Combustor casing rings
• Transition duct rings
• Forged shafts
• Forged blocks & blanks
• Sleeves & bushings
• Hollow bars
• Trepanned billets
• Forged flanges
• Round bar 25–500 mm Ø
• Tube sheets
• Forged tubes & pipes
• Spindles
• Gears
• Nozzles
• Valve stems & seat rings
• Near-net-shape forgings to drawing

Full list with size limits in the product forms and industries section below.

Equipment used on CoCr22NiW work

What product forms and industries does CoCr22NiW cover?

Jiangyin Jiangnan Metal Co., Ltd. produces CoCr22NiW / UNS R30188 in every open-die and ring-rolled form below, to customer drawing. The dominant real-world use of this alloy is hot gas-path hardware; the other forms and industries listed here are supplied on request where a project specifies this grade.

Forged product forms

Industries we ship CoCr22NiW into

Quality assurance, testing and certification

CoCr22NiW is almost always bought for a safety-critical hot section, so the certificate matters as much as the metal. Every UNS R30188 order from Jiangyin Jiangnan Metal Co., Ltd. is released against the following.

Hold points and non-conformance

CoCr22NiW orders run through mandatory QA hold points: raw material chemistry release, forging temperature compliance, post-forging ultrasonic inspection, solution treatment chart approval, mechanical test acceptance, and final dimensional and NDE release. Customers may witness any stage at no charge. Any out-of-specification finding raises a formal non-conformance report within 24 hours, and no rework, regrade or concession is applied until the customer has seen the NCR and the proposed disposition. Shipping and test documentation is retained for ten years.

Where is CoCr22NiW used?

Almost every application shares the same profile: high metal temperature, an aggressive combustion environment and thermal cycling. Load is rarely the limiting factor; survival in the environment is.

Component photographs: replace the placeholders in the source with real shop photographs of CoCr22NiW rings and discs. Genuine process photographs with descriptive file names and alt text are one of the strongest trust signals a supplier page can carry.

How to specify a CoCr22NiW forging order

CoCr22NiW has no aging condition to choose, so specification is simpler than for a precipitation-hardening grade. Six items cover almost every order.

1. State the generic designation. Write UNS R30188 / AMS 5772, or CoCr22NiW / W.Nr. 2.4683 for European drawings. Avoid ordering by a trademarked brand name alone, since that can only be filled by the trademark holder.
2. Specify the condition. Normally solution heat treated per AMS 5772, 1163–1191 °C, rapid cool. State explicitly if you want the part supplied as-forged for your own heat treatment.
3. Provide the drawing or ring dimensions. For rings, give OD, ID, height and any contour; for discs and shafts, give the finished envelope plus the machining stock you want left.
4. Define NDE. Ultrasonic acceptance class per ASTM A388 or AMS 2154, and penetrant inspection per ASTM E1417 with the method and sensitivity level. Say which surfaces are critical.
5. State the certificate. EN 10204 3.1 or 3.2, plus any OEM specification that must appear on it, and any additional testing such as elevated-temperature tensile, Charpy or grain size.
6. Give quantity, delivery target and destination. Cobalt and tungsten procurement dominates lead time, so an early indication of quantity lets us secure raw material at a better price.

Common CoCr22NiW specification mistakes

Drawing callout template for CoCr22NiW

Copy this block into the material note on your drawing. It removes most of the ambiguity that causes RFQ back-and-forth.

MATERIAL:      CoCr22NiW / UNS R30188 / W.Nr. 2.4683
               per AMS 5772 (bar, forgings and rings)

CONDITION:     Solution heat treated 1163-1191 C (2125-2175 F),
               rapid cool or water quench. Furnace chart required.

CHEMISTRY:     Per AMS 5772. Lanthanum 0.02-0.12 % shall be
               reported on the certificate.

FORGING:       Hot work from 1175 C (2150 F). Finish above 1010 C.
               Forging reduction ratio >= 4:1.

GRAIN SIZE:    Report per ASTM E112.

NDE:           UT per ASTM A388 [class ____]
               (or AMS 2154 class ____ for aerospace)
               (or EN 10228-3 quality class ____, or SEP 1921 class ____)
               PT per ASTM E1417 Type I, method ____, sensitivity ____
               NOTE: material is non-magnetic - do not specify MT.

TESTING:       Tensile per ASTM E8 at room temperature.
               [Optional] Elevated tensile per ASTM E21 at ____ C.
               [Optional] Charpy V-notch per ASTM E23.

CERTIFICATE:   EN 10204 3.1  [or 3.2 with third-party witness]
               List all equivalent designations satisfied.

MARKING:       Heat number, specification, drawing and part number,
               vibro-etched on a non-functional surface.

Glossary

CoCr22NiW

European chemical-symbol name for the cobalt-nickel-chromium-tungsten superalloy designated UNS R30188.

UNS R30188

Unified Numbering System designation for this alloy. The R3xxxx series covers cobalt-base alloys.

W.Nr. 2.4683

German Werkstoff material number for the same chemistry, used on European drawings.

AMS 5772

SAE Aerospace Material Specification covering this alloy as bar, forgings and rings. It is the controlling document for most forging orders.

AMS 5608

SAE specification covering the same alloy as sheet, strip and plate.

Solid-solution strengthening

Strengthening by dissolved atoms, here mainly tungsten, distorting the lattice and impeding dislocation motion. Unlike precipitation hardening, there is no aging step and no over-aging in service.

Laves phase (Co₂W)

An intermetallic that precipitates after long exposure around 650–870 °C. It reduces room-temperature ductility and impact toughness while leaving high-temperature strength largely intact.

Sulfate-deposit hot corrosion

Accelerated attack when sulfur from fuel and sodium from ingested salt form molten sulfate deposits on hot metal. The dominant degradation mode in marine and coastal turbines.

Lanthanum addition

A rare-earth element added at roughly 0.03 % that improves adhesion of the protective chromia scale under thermal cycling. Its presence is the defining difference from UNS R30605.

EN 10204 3.1 / 3.2

Certificate types. 3.1 is issued by the manufacturer's own independent quality department; 3.2 adds a third-party or customer inspector who witnesses testing and countersigns.

MMPDS

Metallic Materials Properties Development and Standardization, the source of statistically derived design allowables for aerospace. This alloy appears in chapter 6.4.2.

Frequently asked questions about CoCr22NiW

Technical references

Chemistry, mechanical, physical and environmental data on this page are drawn from published specifications and engineering references. Test results on our certificates are independent and traceable to calibrated equipment in our own laboratory.

1. AMS 5772, Alloy Bars, Forgings, and Rings, 39.5Co – 22Cr – 22Ni – 14.5W – 0.07La, SAE International.
2. AMS 5608, Alloy Sheet, Strip, and Plate, Cobalt base, Solution Heat Treated, SAE International.
3. AMS 5801, Alloy Welding Wire, Cobalt base, SAE International.
4. MMPDS, Metallic Materials Properties Development and Standardization, chapter 6.4.2 (UNS R30188), Battelle Memorial Institute.
5. ASM Handbook, Volume 1, Properties and Selection: Irons, Steels, and High-Performance Alloys, ASM International, cobalt-base superalloys.
6. ASM Handbook, Volume 14A, Metalworking: Bulk Forming, ASM International, forging of superalloys.
7. ASTM E8/E8M, Standard Test Methods for Tension Testing of Metallic Materials, ASTM International.
8. ASTM E21, Standard Test Methods for Elevated Temperature Tension Tests of Metallic Materials, ASTM International.
9. ASTM E23, Standard Test Methods for Notched Bar Impact Testing of Metallic Materials, ASTM International.
10. ASTM E112, Standard Test Methods for Determining Average Grain Size, ASTM International.
11. ASTM A388/A388M, Standard Practice for Ultrasonic Examination of Steel Forgings, ASTM International.
12. ASTM E1417/E1417M, Standard Practice for Liquid Penetrant Testing, ASTM International.
13. AMS 2154, Inspection, Ultrasonic, Wrought Metals, Process For, SAE International.
14. EN 10204:2004, Metallic products. Types of inspection documents, CEN, Brussels.
15. Haynes International, HAYNES® 188 alloy technical brochure and datasheet, published property data for UNS R30188. HAYNES® is a registered trademark of Haynes International, Inc.
16. Klarstrom, D.L., The Development of Haynes 188 Alloy, background on the lanthanum addition and its effect on oxide scale adhesion.

Standards are periodically revised. For procurement, always reference the revision in force at the contract date. All trademarks belong to their respective owners.

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