What is UNS R30188?
UNS R30188 is a wrought cobalt base superalloy. The nominal composition is balance cobalt with 22 % nickel, 22 % chromium, 14 % tungsten and a small lanthanum addition. The grade is strengthened by solid solution rather than by precipitation, so no ageing treatment is required after solution heat treatment. It is widely known by the trade name Haynes 188.
The alloy resists oxidation in flowing air for prolonged exposure up to 1095 °C (2000 °F). The lanthanum addition improves oxide scale adhesion under thermal cycling. In published burner rig tests it shows lower metal loss from sulfate deposit hot corrosion than Haynes 230, alloy 625 and Hastelloy X. Typical applications include combustion cans, transition ducts and afterburner components.
UNS R30188 is listed under nickel alloys in most supplier catalogues, including this one, but the alloy is cobalt base. Nickel is an alloying addition at 20 to 24 %, the same level as chromium.
Designations and equivalent specifications
The applicable specification depends on the product form. Forgings, billet, rod and bar are covered by AMS 5772.
| Designation or standard | Applies to |
|---|---|
| UNS R30188 | Unified Numbering System designation |
| Haynes® 188, Alloy 188, HS-188 | Trade and common names for the same chemistry |
| W.-Nr. 2.4683 | European material number |
| AMS 5772 | Forgings, billet, rod and bar |
| AMS 5608 | Sheet, plate and strip |
| EN 10204 3.1 / 3.2 | Material certificate level, works or third party witnessed |
| ASTM A388, EN 10228-3, SEP 1921 | Ultrasonic examination of the finished forging |
Customer and OEM specifications are accepted as the governing document when supplied with the enquiry.
Chemical composition of UNS R30188
Weight percent to AMS 5772. Cobalt forms the balance, nominally about 39 %.
| Element | Symbol | Specified range, % | Nominal, % |
|---|---|---|---|
| Cobalt | Co | Balance | 39 |
| Nickel | Ni | 20.0–24.0 | 22 |
| Chromium | Cr | 20.0–24.0 | 22 |
| Tungsten | W | 13.0–15.0 | 14 |
| Iron | Fe | 3.0 max | – |
| Manganese | Mn | 1.25 max | – |
| Silicon | Si | 0.20–0.50 | 0.35 |
| Carbon | C | 0.05–0.15 | 0.10 |
| Lanthanum | La | 0.02–0.12 | 0.03 |
| Boron | B | 0.015 max | – |
Each heat is supplied with a certified chemical analysis. Where a customer specification calls for tighter limits than AMS 5772, material is melted and certified to the customer document.
Mechanical properties of UNS R30188
Room temperature properties in the solution annealed condition, followed by typical tensile properties from room temperature to 1093 °C.
Room temperature, solution annealed
| Property | Metric | Imperial |
|---|---|---|
| Ultimate tensile strength | 960–990 MPa | 139,000–144,000 psi |
| 0.2 % yield strength | 445–485 MPa | 64,500–70,000 psi |
| Elongation at break | 50–55 % | 50–55 % |
| Hardness, bar | 96 HRB | 96 HRB |
| Charpy V-notch impact | 194 J | 143 ft·lb |
| Grain size, bar | ASTM 3.5–7.5 | ASTM 3.5–7.5 |
Tensile properties at elevated temperature
| Test temperature | 0.2 % yield strength | Ultimate tensile strength | Elongation |
|---|---|---|---|
| Room temperature | 483 MPa | 991 MPa | 50.6 % |
| 538 °C (1000 °F) | 315 MPa | 832 MPa | 60.3 % |
| 649 °C (1200 °F) | 311 MPa | 838 MPa | 62.8 % |
| 760 °C (1400 °F) | 301 MPa | 580 MPa | 85.6 % |
| 871 °C (1600 °F) | 256 MPa | 341 MPa | 97.9 % |
| 982 °C (1800 °F) | 132 MPa | 188 MPa | 102.6 % |
| 1093 °C (2000 °F) | 66 MPa | 96 MPa | 87.1 % |
Elevated temperature values are typical published data for the alloy and are indicative only. Acceptance testing is carried out to the specification stated on the order and the results appear on the EN 10204 certificate.
Physical properties of UNS R30188
| Property | Condition | Value |
|---|---|---|
| Density | Room temperature | 8.98 g/cm³ (0.324 lb/in³) |
| Melting range | – | 1315–1410 °C (2400–2570 °F) |
| Modulus of elasticity | Room temperature | 232 GPa |
| Modulus of elasticity | 800 °C | 171 GPa |
| Poisson’s ratio | Room temperature | 0.30 |
| Thermal conductivity | Room temperature | 10.4 W/m·°C |
| Thermal conductivity | 800 °C | 24.8 W/m·°C |
| Mean coefficient of thermal expansion | 25–100 °C | 12.1 × 10⁻⁶ /°C |
| Mean coefficient of thermal expansion | 25–800 °C | 15.5 × 10⁻⁶ /°C |
| Specific heat | 100 °C | 423 J/kg·°C |
| Electrical resistivity | Room temperature | 101 µΩ·cm |
Typical published values for the alloy, quoted for design guidance. They are not guaranteed maxima or minima.
UNS R30188 forged product forms
All items are open die forged or ring rolled to drawing. No dies are required, so single pieces and small quantities can be produced.
- Seamless rolled rings and forged rings
- Forged flanges and blind flanges
- Forged round bars, square bars and blocks
- Forged discs and blanks
- Forged shafts, spindles and eccentric shafts
- Forged sleeves, bushings and hollow bars
- Forged tubes, pipes and cylinders
- Forged tube sheets and baffle plates
- Forged valve bodies, seat rings, stems and balls
- Forged nozzles and manifolds
- Forged gear blanks and rolls
- Machined to print parts on request
Applications of UNS R30188 forgings
UNS R30188 is specified where components run at high temperature in an oxidising or corrosive gas stream.
| Industry | Typical forged parts | Reason for selection |
|---|---|---|
| Aero and industrial gas turbines | Combustion cans, transition ducts, flame holders, spray bars, afterburner liners, seal and guide rings, heat shields | Strength and oxidation resistance to 1095 °C with good behaviour under thermal cycling |
| Power generation | Turbine casing rings, compressor components, generator hardware, gearbox parts | Stable properties over long continuous running hours |
| Oil, gas and subsea | Valve bodies, seat rings, stems, wellhead and christmas tree components, deepwater production hardware | Hot corrosion and chloride resistance in sour, salt laden service |
| Chemical and process plant | Pump and plunger pump shafts, pressure vessel flanges, tube sheets, shell and tube heat exchanger parts, air receivers | Corrosion resistance combined with high temperature strength |
| Heat treatment and furnaces | Retorts, baskets, fixtures, burner shrouds, recuperator internals | Resistance to gaseous sulfidation and molten chloride salts |
| Heavy machinery and marine | Forged rolls, wheels, crankshafts, eccentric shafts, mixer and crystalliser parts | Toughness in heavy sections and good hot workability in large cross sections |
Manufacturing and testing of UNS R30188 forgings
Melting
Raw material is produced by EAF plus VOD, followed by electroslag remelting. This route controls inclusion content and gives the clean, uniform ingot structure required before a cobalt superalloy can be hot worked. Vacuum melted material is available where the customer specification requires it.
Open die forging and ring rolling
The alloy is forged from approximately 1175 °C and is held long enough for the whole piece to reach temperature. Reductions are planned to break down the as cast structure and produce a uniform fine grain through the section, with grain flow following the shape of the part. Rings are produced on a radial ring rolling mill, which gives continuous circumferential grain flow.
Heat treatment
Forgings are supplied solution heat treated unless the order states otherwise. The alloy is held at 1163 to 1191 °C (2125 to 2175 °F) for a time suited to the section thickness, then rapidly air cooled or water quenched. Annealing below the solution temperature causes carbide precipitation and is not used as a final treatment.
Testing and certification
Forgings are ultrasonically examined to ASTM A388, EN 10228-3 or SEP 1921 as specified on the order. Chemical analysis, tensile testing, hardness testing, grain size measurement, dye penetrant and magnetic particle inspection are available. Certificates are issued to EN 10204 3.1, or to 3.2 with a third party inspection body witnessing the tests.
UNS R30188 compared with Haynes 230 and Haynes 25
These three alloys are used for similar hot section components. The table gives published test data for comparison.
| Property | UNS R30188 (188) | UNS N06230 (230) | UNS R30605 (25 / L-605) |
|---|---|---|---|
| Base metal | Cobalt | Nickel | Cobalt |
| Nominal chemistry | Co-22Ni-22Cr-14W-La | Ni-22Cr-14W-2Mo-La | Co-20Cr-15W-10Ni |
| Hot corrosion metal loss, 1000 h at 900 °C | 20 µm | 30 µm | – |
| Burner rig oxidation metal loss, 1000 h at 980 °C | 28 µm | 71 µm | – |
| Impact energy after 8000 h at 870 °C | 12 J | 28 J | – |
| Typical selection | Sulfur or salt present in the gas stream | Very long exposure where retained toughness is critical | Largely superseded by alloy 188 |
Comparative figures are published burner rig and thermal stability test data, listed for comparison. Alloy 188 replaced alloy 25 in most gas turbine applications because it retains properties better after long exposure. Haynes 230 forgings are the usual alternative where thermal stability ranks above hot corrosion resistance. All three grades are forged here.
Frequently asked questions about UNS R30188
Is UNS R30188 the same as Haynes 188?
Yes. UNS R30188 is the Unified Numbering System designation for the alloy sold under the trade name Haynes 188, also called Alloy 188, HS-188 and W.-Nr. 2.4683. The chemistry is the same. Jiangyin Jiangnan Metal Co., Ltd. supplies the grade as UNS R30188 forgings to AMS 5772.
Is UNS R30188 a nickel alloy or a cobalt alloy?
It is a cobalt base alloy. Cobalt forms the balance at around 39 %, while nickel is an alloying addition at 20 to 24 %, the same level as chromium. It is normally catalogued with nickel alloys because it is bought for the same applications.
Which specification covers UNS R30188 forgings?
AMS 5772 covers forgings, billet, rod and bar. AMS 5608 covers sheet, plate and strip. If the drawing calls out an OEM specification, send it with the enquiry and the forgings will be produced and certified to that document.
What is the maximum service temperature of UNS R30188?
Up to 1095 °C (2000 °F) for prolonged continuous exposure in oxidising conditions, and higher for short excursions. Useful load bearing strength is normally taken to about 980 °C. At 1093 °C the tensile strength has fallen to approximately 96 MPa.
How is UNS R30188 heat treated after forging?
Solution heat treat at 1163 to 1191 °C (2125 to 2175 °F), soaked for the section thickness, then rapid air cool or water quench. The alloy is solid solution strengthened, so no ageing step is required. Annealing below the solution temperature precipitates carbides and is not used as a final treatment.
What sizes and weights can be forged?
Open die forging and radial ring rolling require no dies, so size is limited by press capacity and material availability rather than by tooling. Send the finished dimensions or the drawing and the achievable one piece size and machining allowance will be confirmed.
Are material certificates and third party inspection available?
Yes. Certificates are issued to EN 10204 3.1 as standard, or to 3.2 with a third party inspection body witnessing the testing. Ultrasonic examination is carried out to ASTM A388, EN 10228-3 or SEP 1921 at the acceptance class stated on the order.
Should UNS R30188 or Haynes 230 be selected?
Select UNS R30188 where the gas stream carries sulfur or salt, because its resistance to sulfate deposit hot corrosion is the better of the two. Select Haynes 230 where the part remains at temperature for many thousands of hours and retained toughness after that exposure is critical. Both grades are rated for continuous service to approximately 1095 °C.
What information is needed for a quotation?
A drawing or the finished dimensions, the quantity, the governing specification, the delivery condition, the ultrasonic acceptance class and the certificate level. Send these to sales@steelforgepieces.com.
Request a quotation for UNS R30188 forgings
Please supply the following information with the enquiry:
- Drawing or dimensions. PDF, DWG or STEP, or the finished outside diameter, inside diameter, length and thickness
- Quantity. Single prototypes and small batches are accepted
- Specification. AMS 5772, or a customer or OEM document
- Delivery condition. As forged, solution heat treated, rough machined or finish machined
- NDT requirement. Ultrasonic standard and acceptance class, plus PT or MT if required
- Certificate level. EN 10204 3.1 or 3.2, and the inspection body if 3.2
Manufacturer
Jiangyin Jiangnan Metal Co., Ltd. Open die forging factoryNo.1 Chengxiqiao Road, Zhouzhuang Town,
Jiangyin City, Jiangsu Province, China
Phone: +86 189 2135 9659
Email: sales@steelforgepieces.com
Web: www.steelforgepieces.com
Cobalt and nickel superalloys, stainless steel, tool steel, alloy steel and carbon steel forged to drawing as open die forgings and seamless rolled rings, shipped worldwide.
Enquiries
Send a drawing or the finished dimensions and a price is normally returned within one working day. Prototypes and small quantities are accepted alongside production batches.
Technical content on this page is maintained by the metallurgical department of Jiangyin Jiangnan Metal Co., Ltd. Questions on the published data can be sent to sales@steelforgepieces.com.