Section 01
What are Alloy 188 and Haynes 188?
Alloy 188 and Haynes 188 are the same cobalt-nickel-chromium-tungsten superalloy, designated UNS R30188 and W.Nr. 2.4683. It was developed for gas-turbine hot sections, where a part has to hold its shape and resist oxidising combustion gas at temperatures that would ruin a stainless steel.
Why one alloy carries two names
The alloy was developed by Haynes International, Inc., which sells it under the registered trade name HAYNES® 188. Once a composition is registered in the Unified Numbering System, other mills may make the same chemistry, and they sell it under the generic designation Alloy 188. Both names point to the identical UNS R30188 limits in Table 2.
The practical difference is commercial, not metallurgical. Buying HAYNES® 188 means buying Haynes International material. Buying Alloy 188 means buying UNS R30188 from another mill, with the same specification governing chemistry, heat treatment and mechanical acceptance. Jiangyin Jiangnan Metal Co., Ltd. supplies the latter.
Can Alloy 188 be used where a drawing calls for Haynes 188?
That decision belongs to the design authority, not to the forging supplier. What we can say is what governs the material. If the drawing or purchase specification calls out AMS 5772, or UNS R30188, or a chemistry and property table rather than a brand, then Alloy 188 to that specification meets the requirement and the certificate proves it heat by heat.
If the drawing names HAYNES® 188 as a sole-source brand, or the part sits under an aero-engine specification that names an approved source list, then the source is fixed and a generic equivalent is not a substitute regardless of chemistry. Aerospace and nuclear work usually falls in this second category. Send the specification with the enquiry and the position will be clear before anything is quoted.
Three things do the work. Cobalt gives a face-centred-cubic matrix that softens more slowly than nickel or iron as the temperature climbs. Tungsten at 13–15 % is a large, slow-diffusing atom that stiffens that matrix by solid solution, which is why Alloy 188 needs no precipitation-hardening heat treatment to be useful. Chromium at 21–23 % forms the protective oxide, and the small lanthanum addition of 0.03–0.12 % is what makes that oxide stick to the metal through thermal cycling instead of spalling off. Lanthanum is the single feature that most separates Alloy 188 from earlier cobalt alloys such as L-605.
Because it is solid-solution strengthened rather than age-hardened, Alloy 188 is comparatively forgiving to forge and weld, and it keeps good ductility after long exposure at temperature. It work-hardens quickly, so cold forming needs intermediate annealing, and cold work followed by ageing near 540 °C (1000 °F) for 4 to 16 hours is a recognised way to raise strength further.
Names, numbers and specifications for the same alloy
| Designation | Issued by / covers |
|---|---|
| Alloy 188 | Generic industry name for the UNS R30188 composition |
| Haynes 188 | The same UNS R30188 composition under its originator's trade name |
| UNS R30188 | Unified Numbering System, cobalt-base alloys |
| W.Nr. 2.4683 | German Werkstoff number |
| AMS 5772 | Bars, forgings and rings, solution heat treated. This is the specification used for forgings. |
| AMS 5608 | Sheet, strip and plate |
| AMS 5801 | Welding wire |
| GE B50TF59 / B50TF74 / B50A712 | GE Aviation engine material specifications referencing this alloy |
| UDIMET® 188 | Special Metals Corporation trade name for this composition |
| Co–22Cr–22Ni–14W–La | Nominal chemistry shorthand |
HAYNES® is a registered trademark of Haynes International, Inc. and UDIMET® of Special Metals Corporation. Jiangyin Jiangnan Metal Co., Ltd. is not affiliated with, endorsed by or a licensee of either company and does not supply HAYNES®-branded or UDIMET®-branded material. These names are listed so that buyers can cross-reference the equivalent UNS R30188 composition, which is what we forge.
Section 02
Alloy 188 (Haynes 188) chemical composition
The composition below follows AMS 5772 limits and is the specification Jiangyin Jiangnan Metal Co., Ltd. works to for Alloy 188 forgings. Every heat is analysed and the result appears on the EN 10204 certificate against the heat number.
| Element | Symbol | Min % | Max % | Role in the alloy |
|---|---|---|---|---|
| Cobalt | Co | Balance | FCC matrix; retains strength at red heat | |
| Chromium | Cr | 21.0 | 23.0 | Forms the protective Cr₂O₃ scale |
| Nickel | Ni | 20.0 | 24.0 | Matrix stability and toughness |
| Tungsten | W | 13.0 | 15.0 | Solid-solution strengthening, creep resistance |
| Lanthanum | La | 0.03 | 0.12 | Makes the oxide scale adherent under cycling |
| Carbon | C | 0.05 | 0.15 | Carbides for grain-boundary strength |
| Silicon | Si | 0.20 | 0.50 | Deoxidation; assists oxidation resistance |
| Manganese | Mn | — | 1.25 | Deoxidation, sulphur control |
| Iron | Fe | — | 3.00 | Residual |
| Boron | B | — | 0.015 | Grain-boundary strengthening |
| Phosphorus | P | — | 0.020 | Residual, kept low |
| Sulphur | S | — | 0.015 | Residual, kept low by VOD and ESR |
Composition to AMS 5772. Nominal chemistry is Co bal. – 22Cr – 22Ni – 14W – 0.9Mn – 0.35Si – 0.10C – 0.03/0.12La.
Section 03
Alloy 188 (Haynes 188) mechanical properties
Typical short-time tensile values for solution-annealed Alloy 188. Note that elongation rises between room temperature and 538 °C. The alloy becomes more ductile as it heats, which is part of why it survives thermal cycling in combustor hardware.
| Test temperature | Ultimate tensile strength | Yield strength, 0.2 % offset | Elongation in 2 in. (50 mm) |
|---|---|---|---|
| 21 °C / 70 °F | 946 MPa / 137.2 ksi | 464 MPa / 67.3 ksi | 53 % |
| 538 °C / 1000 °F | 748 MPa / 108.5 ksi | 290 MPa / 42.0 ksi | 61 % |
Typical values, not guaranteed minima. Properties of a heavy forging vary with section size, forging reduction and test location; acceptance values are agreed at order stage and reported on the certificate.
What to specify on the order
- Required tensile minima and the test location (surface, mid-radius, or centre) and orientation (longitudinal, tangential, radial).
- Grain size, if a limit applies.
- Whether test prolongations are to be integral with the forging or separately forged.
- For creep-limited service: the required stress-rupture test, temperature and duration.
Section 04
Alloy 188 (Haynes 188) physical properties
| Property | Metric | Imperial |
|---|---|---|
| Density | 8.98 g/cm³ | 0.324 lb/in³ |
| Melting range | 1302–1410 °C | 2375–2570 °F |
| Oxidation-resistant service, prolonged | to ≈1093 °C | to ≈2000 °F |
| Solution anneal | 1177 ± 14 °C | 2150 ± 25 °F |
| Age-strengthening of cold work | ≈540 °C, 4–16 h | ≈1000 °F, 4–16 h |
| Crystal structure | Face-centred cubic (austenitic), essentially non-magnetic when annealed | |
Physical data from published producer literature for UNS R30188. Confirm against the current mill datasheet before using in design calculations.
Weight of an Alloy 188 forging
At 8.98 g/cm³ Alloy 188 is about 14 % denser than 304 stainless, so a ring that "looks the same" weighs noticeably more. Given the cost of cobalt and tungsten, the rough forged weight is usually the single largest line on the quotation. For a ring, with all dimensions in centimetres:
Weight (kg) = (π ÷ 4) × (OD² − ID²) × height × 0.00898
Always calculate on the rough forged envelope, not the finished machined part, because the forging carries machining allowance and test prolongations. Sending a finished-part drawing and letting us add the forging allowance normally lands on a lower buy weight than a customer-estimated envelope.
Section 05
Alloy 188 / Haynes 188 forged product forms and size range
Jiangyin Jiangnan Metal Co., Ltd. produces the following Alloy 188 forged forms to customer drawing. Sizes outside these ranges are often still possible. Send the drawing and we will confirm.
| Forged form | Typical size range | Common use |
|---|---|---|
| Seamless rolled rings | OD 200–2500 mm, height ≤ 800 mm, wall ≥ 30 mm | Combustor and transition-duct rings, casings |
| Forged rings (open die) | OD 150–2000 mm | Short runs, heavy wall, non-standard sections |
| Forged discs / disks | Ø 100–1800 mm, thickness 30–500 mm | Blank stock for turbine and valve components |
| Forged round bars | Ø 60–800 mm, length ≤ 6000 mm | Machining stock, shafts, valve stems |
| Forged shafts & eccentric shafts | Ø 80–600 mm, length ≤ 5000 mm | Pump and compressor shafts, spindles |
| Forged flanges | DN 50–2000 mm | Pressure-vessel and pipework connections |
| Forged sleeves & bushings | OD 100–1500 mm | Wear surfaces, hot-gas-path liners |
| Forged tube sheets | Ø ≤ 2500 mm, thickness ≤ 300 mm | Shell-and-tube heat exchangers |
| Hollow forgings, tubes, pipes | OD 100–1200 mm, ID ≥ 60 mm | Pressure parts, spray bars, nozzles |
| Forged blocks, bodies, valve parts | Single-piece weight 5–3000 kg | Valve bodies, seat rings, blocks, manifolds |
Supplied condition: solution annealed. Surface: as-forged, shot blasted, rough machined or finish machined to drawing. Single-piece prototypes and small batches are accepted alongside production quantities.
Section 06
How Alloy 188 is forged and heat treated
Alloy 188 is not a difficult alloy to forge, but it is unforgiving of a cold centre. The whole section has to reach temperature before the press touches it, and it work-hardens fast enough that reheats between passes are normal on heavy work.
- MeltEAF + VOD, then ESR refining
- CogHomogenise, break down cast structure to billet
- SoakThrough-heat to ≈1177 °C / 2150 °F
- ForgeOpen-die press or ring mill, reheats as needed
- Anneal1177 ± 14 °C, rapid air cool or water quench
- TestRough machine, UT, tensile, hardness
- CertifyEN 10204 3.1 or 3.2, then ship
Melting route
Alloy 188 is melted by electric arc furnace with vacuum oxygen decarburisation, then remelted by electroslag refining. ESR is what brings sulphur and non-metallic inclusions down to the level a hot-section forging needs, and it gives the directional solidification that makes the ingot forge cleanly.
Solution heat treatment
Standard practice is 1177 °C ± 14 °C (2150 °F ± 25 °F) followed by rapid air cooling or water quenching. Slow cooling through the carbide range is what to avoid. Bright-annealed product is cooled in hydrogen.
Cold work and ageing
Alloy 188 strengthens readily by cold deformation, and that strength can be pushed further by ageing the cold-worked structure near 540 °C (1000 °F) for 4 to 16 hours. For complex cold forming, intermediate anneals are needed because the alloy work-hardens rapidly.
Machining and welding
Machining behaviour is broadly comparable to Haynes 25 and Haynes 230: slow speeds, positive feed, rigid setup, sharp tooling, and no dwelling in the cut. Welding is by GTAW, GMAW, resistance or electron-beam methods, with AMS 5801 filler.
Section 07
What Alloy 188 / Haynes 188 forgings are used for
Alloy 188 goes where the gas is hot, oxidising and often carrying sulphur. That means the hot section of gas turbines first, and severe service in chemical, oil and gas, and power equipment second.
Aero engines and industrial gas turbines
Combustor cans and liners, transition ducts, flame holders, afterburner liners, spray bars, and the rings and casings that carry them. These are the parts Alloy 188 was designed for, and the lanthanum-stabilised oxide scale is what lets them survive repeated start-stop thermal cycling.
Power generation and turbomachinery
Forged rings, spindles, bars and gear blanks for power transmission, gas compressors and gearboxes running in hot or corrosive atmospheres.
Oil, gas and offshore
Bushings, sleeves, discs and blocks for subsea and deepwater production systems, wellhead and Christmas-tree components, industrial air compressors, and nitrogen generators.
Valves and flow control
Forged valve bodies, stems, blocks and forged valve seat rings for ball, check, globe, gate and plug valves in high-temperature or hot-corrosive duty, plus strainers.
Pressure equipment and heat exchangers
Forged shafts, forged pipes and tubes, tube sheets and flanges for pressure vessels, air receivers and shell-and-tube heat exchangers.
Process, pump and heavy machinery
Rolled rings and shafts for chemical and plunger pumps, forged eccentric shafts for processing units and crystalliser equipment, forged wheels, manifolds and rolls for shipbuilding, heavy machinery, pulp and paper, and pharmaceutical and biochemical plant.
Section 08
Alloy 188 compared with Haynes 25, Haynes 230, Hastelloy X and Inconel 617
Most buyers reach Alloy 188 after ruling something else out. If the problem is oxidation and sulphate hot corrosion at the very top of the range, and the part will be thermally cycled, Alloy 188 earns its cobalt price. If the problem is strength at a somewhat lower temperature, a nickel-base alloy is usually cheaper and easier to work.
| Property | Alloy 188 | Haynes 25 / L-605 | Haynes 230 | Hastelloy X | Inconel 617 |
|---|---|---|---|---|---|
| UNS | R30188 | R30605 | N06230 | N06002 | N06617 |
| Base metal | Cobalt | Cobalt | Nickel | Nickel | Nickel |
| Nominal chemistry | 22Cr-22Ni-14W-La | 20Cr-15W-10Ni | 22Cr-14W-2Mo-La | 22Cr-18Fe-9Mo | 22Cr-12.5Co-9Mo-1.2Al |
| Strengthening | Solid solution + La-stabilised scale | Solid solution | Solid solution + carbides | Solid solution | Solid solution |
| Oxidation limit, prolonged | ≈1093 °C | ≈980 °C | ≈1149 °C | ≈1204 °C | ≈1100 °C |
| Sulphate hot corrosion | Excellent | Good | Good | Moderate | Good |
| Thermal-cycle scale adherence | Excellent (La) | Moderate | Excellent (La) | Moderate | Good |
| Relative raw-material cost | Highest | High | Moderate | Lower | Moderate |
| Forging spec | AMS 5772 | AMS 5759 | ASTM B572 | AMS 5754 | ASTM B564 |
Comparison values are indicative, drawn from published producer literature, and are intended to narrow a shortlist rather than to support design. Confirm against current mill datasheets and the governing design code. All five alloys are forged by Jiangyin Jiangnan Metal Co., Ltd.
Section 09
Testing, inspection and certification
Every Alloy 188 / Haynes 188 forging leaving Jiangyin Jiangnan Metal Co., Ltd. is traceable to a heat number, and the test record travels with it.
- EN 10228-3
- SEP 1921
- ASTM A388
- EN 10204 3.1
- EN 10204 3.2
Ultrasonic testing
Alloy 188 forgings are ultrasonically tested to EN 10228-3, SEP 1921 or ASTM A388, to the quality class stated on the order. UT is performed after solution heat treatment and rough machining, when the surface is fit to couple and the structure is final.
Mechanical testing
Tensile and hardness testing on integral or separately forged prolongations, at the location and orientation agreed at order stage. Impact testing, grain-size determination and stress-rupture testing are available on request.
Chemical analysis
Full heat analysis reported against the AMS 5772 limits, plus product analysis on the finished forging where the order calls for it.
Certification
EN 10204 3.1 mill certificate as standard, covering heat number, chemistry, heat-treatment record, mechanical results and NDT results. EN 10204 3.2 witnessed by TÜV, SGS, BV, DNV or Lloyd's Register on request.
Also available on request
- Magnetic-particle or dye-penetrant examination of machined surfaces.
- Macro-etch and grain-flow examination.
- Positive material identification (PMI) at despatch.
- Dimensional report against the customer drawing.
- Marking, preservation and packing to customer specification.
Section 10
How to request an Alloy 188 forging quotation
Send a drawing or the finished dimensions for Alloy 188 / Haynes 188 forgings to sales@steelforgepieces.com. A quotation normally comes back within one working day.
What to include so the first quotation is the right one
- Drawing or dimensions. A finished-part drawing is fine; we will add forging and machining allowance.
- Grade and specification. Alloy 188 / Haynes 188 / UNS R30188, and whether AMS 5772 applies.
- Quantity and whether this is a prototype, a spare, or a repeat production part.
- Supplied condition. As forged, shot blasted, rough machined, or finish machined.
- NDT requirement. Which UT standard, and which acceptance class.
- Certificate type. EN 10204 3.1, or 3.2 and which third party.
- Mechanical acceptance values and test location, if they differ from typical.
- Destination port and required delivery date.
- Company
- Jiangyin Jiangnan Metal Co., Ltd., open-die forging factory
- Address
- No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
- Telephone
- +86 189 2135 9659 (0086-189-2135-9659)
- sales@steelforgepieces.com
- Website
- www.steelforgepieces.com
- Supplies
- Alloy 188 forged rings, seamless rolled rings, discs, bars, flanges, shafts, sleeves, bushings, tube sheets and hollow forgings, worldwide.
Section 11
Alloy 188 and Haynes 188 frequently asked questions
Is Alloy 188 the same as Haynes 188?
They are the same alloy composition. HAYNES® 188 is the registered trade name of Haynes International, Inc. for the alloy covered by UNS R30188; "Alloy 188" is the generic designation used for material of the same UNS number produced by other mills. Both are held to the same chemistry and property limits in AMS 5772. Jiangyin Jiangnan Metal Co., Ltd. forges the generic grade, is not affiliated with Haynes International, Inc., and does not supply HAYNES®-branded material.
What is Alloy 188 (Haynes 188)?
Alloy 188 (UNS R30188, W.Nr. 2.4683) is a cobalt-base superalloy containing nominally 22 % chromium, 22 % nickel and 14 % tungsten with a small lanthanum addition. It is solid-solution strengthened, keeps useful strength at red heat, and resists oxidation in prolonged service up to about 1093 °C (2000 °F). Forgings, bars and rings are ordered to AMS 5772.
Can Alloy 188 replace Haynes 188 on a drawing?
That call belongs to the design authority. Where the drawing or purchase specification governs by AMS 5772, by UNS R30188, or by a chemistry and property table rather than by brand, Alloy 188 to that specification meets the requirement and the EN 10204 certificate evidences it heat by heat.
Where HAYNES® 188 is named as a sole source, or the part falls under an engine specification with an approved source list, the source is fixed and a generic equivalent is not a substitute whatever the chemistry says. Send the governing specification with the enquiry so the position is settled before quotation.
What is the maximum service temperature of Alloy 188?
Published producer data give Alloy 188 very good resistance to oxidising environments for prolonged exposure up to about 1093 °C (2000 °F). That figure describes oxidation, not load capacity: useful load-carrying capability depends on stress and time, so creep and stress-rupture data should govern design rather than the oxidation limit alone.
Which specification covers Alloy 188 forgings?
AMS 5772 covers Alloy 188 bars, forgings and rings in the solution heat-treated condition. AMS 5608 covers sheet, plate and strip, and AMS 5801 covers welding wire. Aero-engine builders also reference their own specifications, such as GE B50TF59, B50TF74 and B50A712.
What is the difference between Alloy 188 and Haynes 25 (L-605)?
Both are cobalt-base solid-solution alloys, but Alloy 188 (Co-22Cr-22Ni-14W-La) carries more chromium and nickel than L-605 (Co-20Cr-15W-10Ni) and adds lanthanum, which makes the protective chromium oxide scale adhere through thermal cycling instead of spalling. That gives Alloy 188 better oxidation and sulphate hot-corrosion resistance at the top of the temperature range. L-605 remains common for lower-temperature wear and medical applications.
At what temperature is Alloy 188 forged?
Alloy 188 is forged from about 1177 °C (2150 °F), and the whole section must be soaked to temperature before the press is applied. It work-hardens rapidly, so reheats between passes are normal on heavy sections. After forging the part is solution annealed at 1177 °C ± 14 °C (2150 °F ± 25 °F) and rapid air cooled or water quenched.
Is Alloy 188 magnetic?
In the solution-annealed condition Alloy 188 has a face-centred-cubic matrix and is essentially non-magnetic, with relative permeability close to 1.0. Heavy cold work can raise permeability slightly, so if a specific permeability limit applies it should be stated on the order and measured on the finished part.
How do I calculate the weight of an Alloy 188 forging?
Use a density of 8.98 g/cm³ (0.324 lb/in³). For a ring, with dimensions in centimetres: weight (kg) = (π ÷ 4) × (OD² − ID²) × height × 0.00898.
Always calculate on the rough forged envelope rather than the finished machined part, because the forging carries machining allowance and test prolongations.
What certificates are supplied with Alloy 188 forgings?
Jiangyin Jiangnan Metal Co., Ltd. issues an EN 10204 3.1 mill certificate as standard, covering heat number, chemical analysis, heat-treatment record, mechanical test results and NDT results. An EN 10204 3.2 certificate witnessed by TÜV, SGS, BV, DNV or Lloyd's Register is available on request.
Who supplies Alloy 188 / Haynes 188 equivalent forgings in China?
Jiangyin Jiangnan Metal Co., Ltd., at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, is an open-die forging factory that produces Alloy 188 (UNS R30188, the Haynes 188 equivalent composition) forged rings, seamless rolled rings, discs, bars, flanges, shafts, sleeves, bushings and tube sheets to AMS 5772, with EN 10204 3.1 or 3.2 certification. Enquiries: sales@steelforgepieces.com, +86 189 2135 9659.
Section 12
About the manufacturer
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory located at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China.
The factory produces open-die forgings, seamless rolled rings, forged shafts, discs, flanges, sleeves, bushings and tube sheets across carbon steel, alloy steel, tool steel, stainless steel, nickel alloys and cobalt superalloys. Alloy 188 (UNS R30188), the Haynes 188 equivalent, sits at the demanding end of that range, alongside Hastelloy, Inconel, Incoloy, Monel, Waspaloy and Multimet N155 forgings.
Work is made to customer drawing rather than to a stock catalogue. Single prototypes and spares are quoted on the same terms as production batches, and material is traceable to heat number on an EN 10204 certificate throughout.
Cite this page
Jiangyin Jiangnan Metal Co., Ltd. (2026). Alloy 188 / Haynes 188 Forgings (UNS R30188): Composition, Properties and Forged Forms. Retrieved from https://www.steelforgepieces.com/Nickel-Alloy/Alloy-188.html
This page may be quoted, summarised or referenced with attribution to Jiangyin Jiangnan Metal Co., Ltd. and a link to the source URL. Supplier enquiries: sales@steelforgepieces.com • +86 189 2135 9659 • No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China.
Page last reviewed by the technical sales team at Jiangyin Jiangnan Metal Co., Ltd.