Nickel superalloy / Open-die forgings / ASTM B637
UNS N07208 forgings
Gamma-prime strengthened Ni-Cr-Co-Mo superalloy, forged to drawing as rings, flanges, bars, discs, sleeves and shafts. Also designated Alloy 282 and HAYNES® 282® alloy.
Summary
UNS N07208 is a wrought, gamma-prime strengthened nickel-base superalloy of nominal composition Ni-20Cr-10Co-8.5Mo-2.1Ti-1.5Al, used for structural components that carry load between 649 °C and 927 °C (1200 to 1700 °F). It is the Unified Numbering System designation for the alloy sold commercially as Alloy 282 and HAYNES® 282®. The alloy reaches Waspaloy-class creep strength while retaining enough weldability and formability to be fabricated into large welded structures, a combination earlier gamma-prime alloys did not offer.
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China. The company produces UNS N07208 forged rings, seamless rolled rings, flanges, round bars, discs, sleeves, bushings, shafts and tube sheets to customer drawings, supplied to ASTM B637 with EN 10204 3.1 or 3.2 material certificates and ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388. Enquiries: sales@steelforgepieces.com or +86 189 2135 9659.
- UNS numberN07208
- Also known asAlloy 282 / HAYNES® 282®
- Forging standardASTM B637, AMS 5915
- Strengtheningγ′ Ni3(Al,Ti), 15 to 20 vol%
- Service window649 to 927 °C
- Density8.27 g/cm³
- UTS, aged (RT)1147 MPa / 166.4 ksi
- 0.2% YS, aged (RT)715 MPa / 103.7 ksi
What is UNS N07208?
UNS N07208 is the Unified Numbering System designation for a wrought nickel-base superalloy strengthened by the ordered gamma-prime phase Ni3(Al,Ti). It was introduced commercially in 2005. The design target was creep strength above that of Alloy 263, without the strain-age cracking that makes Waspaloy and R-41 difficult to weld and fabricate.
The alloy carries a low gamma-prime volume fraction of roughly 15 to 20 percent, against 25 to 35 percent in Waspaloy. The lower fraction slows precipitation kinetics, so material stays ductile after solution annealing and survives post-weld heat treatment without cracking. UNS N07208 contains no niobium. All precipitation strengthening comes from aluminium and titanium.
- UNS number
- N07208
- Common trade names
- Alloy 282, HAYNES® 282® alloy, Ni 282
- Alloy family
- Ni-Cr-Co-Mo, gamma-prime precipitation hardening
- Nominal composition
- Ni bal. 20 Cr 10 Co 8.5 Mo 2.1 Ti 1.5 Al
- Bar and forging spec
- ASTM B637, AMS 5915
- Sheet, plate and strip
- AMS 5951
- Pressure code coverage
- ASME Code Case 3024 to 870 °C; ASME B31 Case 219
- Melting route
- EAF + VOD, then ESR remelt
- Closest alternatives
- Waspaloy, R-41 (Rene 41), Alloy 263, Inconel 718
Specification note. UNS N07208 forgings are covered by ASTM B637, which applies to precipitation-hardening nickel alloy bars, forgings and forging stock. ASTM B564 covers solid-solution nickel alloy forgings and does not list N07208. Where a drawing or purchase order calls out B564 for this grade, we raise it during technical review before release.
UNS N07208 chemical composition
Composition limits per ASTM B637 for UNS N07208, in weight percent. Each heat is supplied with a certified ladle analysis on the EN 10204 3.1 or 3.2 certificate.
| Element | Limits, % | Nominal, % |
|---|---|---|
| Nickel (Ni) | Balance | 57 |
| Chromium (Cr) | 18.5 to 20.5 | 20 |
| Cobalt (Co) | 9.0 to 11.0 | 10 |
| Molybdenum (Mo) | 8.0 to 9.0 | 8.5 |
| Titanium (Ti) | 1.90 to 2.30 | 2.1 |
| Aluminium (Al) | 1.38 to 1.65 | 1.5 |
| Iron (Fe) | 1.5 max | n/a |
| Carbon (C) | 0.04 to 0.08 | 0.06 |
| Manganese (Mn) | 0.30 max | n/a |
| Silicon (Si) | 0.15 max | n/a |
| Boron (B) | 0.003 to 0.010 | 0.005 |
| Tungsten (W) | 0.5 max | n/a |
| Niobium (Nb) | 0.2 max | n/a |
| Tantalum (Ta) | 0.10 max | n/a |
| Copper (Cu) | 0.1 max | n/a |
| Zirconium (Zr) | 0.020 max | n/a |
| Phosphorus (P) | 0.015 max | n/a |
| Sulfur (S) | 0.015 max | n/a |
UNS N07208 mechanical properties
Typical room-temperature values for solution-annealed and age-hardened material. Acceptance minima for forgings are set by ASTM B637 and by the purchase order. We test to whichever is stricter.
| Property | Metric | Imperial |
|---|---|---|
| Ultimate tensile strength | 1147 MPa | 166.4 ksi |
| 0.2% offset yield strength | 715 MPa | 103.7 ksi |
| Elongation | 30% | 30% |
| Reduction of area | 31% | 31% |
| Hardness, aged bar | 29 HRC | 29 HRC |
| Hardness, annealed bar | 86 HRB | 86 HRB |
Strength retained at temperature
Yield strength changes little up to 760 °C, and useful strength is retained to 927 °C. This is the property that governs grade selection.
| Temp. °C | Temp. °F | 0.2% YS, MPa | UTS, MPa | Elong. % |
|---|---|---|---|---|
| 20 | RT | 715 | 1147 | 30 |
| 538 | 1000 | 649 | 991 | 34 |
| 649 | 1200 | 643 | 1048 | 31 |
| 704 | 1300 | 649 | 978 | 29 |
| 760 | 1400 | 628 | 856 | 22 |
| 816 | 1500 | 575 | 709 | 28 |
| 871 | 1600 | 507 | 566 | 31 |
| 927 | 1700 | 310 | 359 | 50 |
| 982 | 1800 | 132 | 174 | 71 |
Values are typical published data for wrought product, quoted for design guidance only. They are not guaranteed minima. Forging properties depend on section size, forging reduction and heat-treat response, and are reported per heat on the material certificate.
UNS N07208 physical properties
| Property | Metric | Imperial |
|---|---|---|
| Density, solution annealed | 8.27 g/cm³ | 0.299 lb/in³ |
| Density, age hardened | 8.29 g/cm³ | 0.300 lb/in³ |
| Melting range | 1300 to 1375 °C | 2370 to 2510 °F |
| Gamma-prime solvus | 997 °C | 1827 °F |
| Modulus of elasticity | 217 GPa | 31.5 × 106 psi |
| Shear modulus | 82 GPa | 11.9 × 106 psi |
| Poisson's ratio | 0.319 | 0.319 |
| Thermal conductivity | 10.3 W/m·°C | 72 Btu-in/ft²-hr-°F |
| Electrical resistivity | 126.1 µΩ·cm | 49.7 µΩ·in |
| Mean CTE, 20 to 1000 °C | 16.9 µm/m·°C | 9.3 µin/in·°F |
| Specific heat, RT | 436 J/kg·°C | 0.104 Btu/lb·°F |
Heat treatment of UNS N07208 forgings
UNS N07208 is delivered solution annealed unless the order states otherwise, because that is the condition in which it can still be machined, formed and welded. Strength is developed afterwards by ageing. The standard two-step cycle is as follows.
- Solution anneal1121 to 1149 °C (2050 to 2100 °F), soak time set by section thickness, then rapid cool or water quench. Plate and bar are commonly annealed at 1135 °C (2075 °F).
- First age, gamma-prime nucleation1010 °C (1850 °F) for 2 hours, air cool. Heat-up to 1010 °C should be as fast as the furnace allows.
- Second age, gamma-prime growth788 °C (1450 °F) for 8 hours, air cool. This step sets the final strength.
Alternative cycles
Two other cycles are in service use and either can be run to specification. The alternative two-step cycle is 899 °C for 4 hours air cool, followed by 788 °C for 8 hours air cool, used where higher containment capability is required in engine cases and rolled rings. The single-step cycle of 802 °C for 8 hours air cool is the treatment required by the ASME pressure vessel code under Code Case 3024.
Rough machining is carried out before ageing. Finish machining and finish grinding are carried out after ageing, with the part at full hardness.
Forging UNS N07208
UNS N07208 hot-works well for a superalloy of its strength class, but the working window is narrow and grain size is easily lost. We forge between 955 °C and 1177 °C (1750 to 2150 °F), with the billet soaked long enough to reach temperature uniformly through section.
Initial breakdown is taken at the top of the range, where flow stress is lowest. Finishing passes are taken at the bottom of the range to refine grain size. Finishing too hot produces parts that meet chemistry but fail grain size and ultrasonic requirements. Hot- and cold-worked parts are annealed before ageing, so that properties develop from a known starting microstructure rather than from residual forging strain.
Starting material is melted by EAF plus VOD, then ESR remelted. The ESR step controls sulfur and oxide cleanliness, which governs the achievable ultrasonic acceptance class.
UNS N07208 product forms
Jiangyin Jiangnan Metal Co., Ltd. forges UNS N07208 to customer drawings in the following forms. All are made to order; there is no standard stock list for this grade.
- Forged rings
- Seamless rolled rings
- Forged flanges
- Forged round bars
- Forged discs and disks
- Forged sleeves
- Forged bushings
- Forged shafts
- Eccentric shafts
- Forged tube sheets
- Forged pipes and tubes
- Valve bodies and seat rings
- Forged nozzles
- Forged blocks
- Forged wheels
- Near-net-shape preforms
| Parameter | Detail |
|---|---|
| Size range | Quoted per drawing |
| Delivery condition | As forged, rough machined, solution annealed, or solution annealed and aged |
| Machining allowance | Per drawing, or per our standard allowance table |
| Dimensional tolerance | Per drawing |
| Minimum order | One piece |
| Quotation turnaround | 24 hours on working days |
Testing, NDT and certification
Every UNS N07208 forging is supplied with a document package. Contents depend on the order. The following are available.
| Item | Standard |
|---|---|
| Ultrasonic testing | EN 10228-3, SEP 1921, ASTM A388 |
| Liquid penetrant testing | ASTM E165, EN ISO 3452 |
| Chemical analysis | Ladle and product analysis to ASTM B637 |
| Tensile testing | ASTM E8, ISO 6892-1, room and elevated temperature |
| Hardness testing | ASTM E18 (HRC, HRB) |
| Grain size | ASTM E112 |
| Material certificate | EN 10204 3.1, or 3.2 with third-party witness |
| Third-party inspection | SGS, BV, TUV, Lloyd's, or client-nominated inspector |
| Dimensional report | Per drawing, issued with the certificate |
Where the specification requires a heat-treatment chart, positive material identification, or retained test material, state this on the enquiry so it is priced at quotation stage.
Where UNS N07208 forgings are used
Aero and industrial gas turbines
Forged rings, cases, seal rings, spacers and nozzle components in the combustor, turbine and exhaust sections, where the part must hold shape and load through the 700 to 900 °C band. The alternative two-step age is worth considering for engine cases and rolled rings that require higher containment capability.
Advanced power generation
Advanced ultra-supercritical (A-USC) steam plant, supercritical CO2 cycles and concentrating solar power. These applications require creep life beyond 100,000 hours at 100 MPa and 760 °C, the regime for which UNS N07208 was characterised under ASME Code Case 3024.
Oil, gas and process equipment
Forged valve bodies, seat rings, stems and blocks; flanges and tube sheets for shell-and-tube heat exchangers; forged shafts and sleeves for chemical and plunger pumps; components for subsea and deepwater production systems, industrial air compressors and nitrogen generators.
Heavy rotating and transmission parts
Seamless rolled rings, spindles, gears and forged rolls for gearboxes, gas compressors and power transmission, where operating temperature rules out steel and rules out Inconel 718.
UNS N07208 compared with Waspaloy, R-41, 263 and Inconel 718
Below 600 °C, Inconel 718 costs less, is stronger at room temperature, and is normally the correct choice. UNS N07208 justifies its cost between roughly 650 °C and 927 °C, and again where the component must be welded.
| Property | UNS N07208 | Waspaloy | R-41 | Alloy 263 | Inconel 718 |
|---|---|---|---|---|---|
| Strengthening phase | Gamma-prime | Gamma-prime | Gamma-prime | Gamma-prime | Gamma-double-prime |
| Gamma-prime fraction | 15 to 20% | 25 to 35% | High | Low | n/a |
| Practical upper limit | 927 °C | 870 °C | 925 °C | 815 °C | 650 °C |
| Creep strength, 816 to 927 °C | Very high | Moderate | Very high | Lower | Not applicable |
| Strain-age cracking resistance | Very good | Poor | Poor | Very good | Good |
| Weldability | Good | Difficult | Difficult | Good | Good |
| Room-temperature yield | 715 MPa | Higher | Higher | Lower | Higher |
| Contains niobium | No | No | No | No | Yes |
| Forging specification | ASTM B637 | AMS 5704, 5708 | AMS 5712 | n/a | ASTM B637, AMS 5662 |
Two selection rules follow. Where the component sees no sustained load above 600 °C, specify Inconel 718. Where it does, and the component is a welded or complex fabrication, UNS N07208 usually gives lower total cost than Waspaloy or R-41 despite higher raw material cost, because scrap from post-weld cracking dominates the bill on those alloys.
Welding and machining UNS N07208
Weld in the solution-annealed condition, before ageing. GTAW (TIG) and GMAW (MIG) with matching 282 filler are the preferred processes. Submerged arc welding is not recommended for this alloy because of the high heat input and weld restraint.
No preheat is required provided the base metal is above 0 °C. Interpass temperature is kept below 93 °C (200 °F). After welding, the age-hardening cycle is run. A full solution anneal beforehand is neither required nor prohibited, but is advisable on heavy sections and on complex weldments carrying high residual stress.
Machining behaves as for other high-temperature nickel alloys: low speed, heavy positive feed, rigid setup, sharp tools, flood coolant. Roughing cuts are taken before ageing.
Request a quotation
We quote UNS N07208 forgings from drawings, sketches or a size list. Quotations are normally returned within 24 hours on working days.
Jiangyin Jiangnan Metal Co., Ltd., open-die forging factory, No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China.
- Grade and specification (UNS N07208 to ASTM B637, plus any customer spec)
- Drawing or dimensions, stating whether sizes are finished or rough
- Quantity and required delivery date
- Delivery condition: as forged, rough machined, annealed, or annealed and aged
- NDT class and acceptance standard
- Certificate type: EN 10204 3.1 or 3.2, and any third-party inspection
Frequently asked questions about UNS N07208
Is UNS N07208 the same as Alloy 282?
Yes. UNS N07208 is the Unified Numbering System designation for the alloy sold commercially as Alloy 282 and HAYNES® 282® alloy. The composition ranges are identical, so a part ordered to UNS N07208 and a part ordered to Alloy 282 are the same material. Jiangyin Jiangnan Metal Co., Ltd. accepts orders written either way.
Which standard covers UNS N07208 forgings?
UNS N07208 bars, forgings and forging stock are covered by ASTM B637 and AMS 5915. Sheet, plate and strip fall under AMS 5951. For pressure equipment, ASME Code Case 3024 covers the grade to 870 °C in Section I and Section VIII Division 1, and ASME B31 Case 219 covers piping. ASTM B564 does not list UNS N07208, so a drawing calling out B564 for this grade should be corrected.
What is the maximum service temperature of UNS N07208?
UNS N07208 is used for load-bearing structural parts up to about 927 °C (1700 °F). Its creep strength advantage sits in the 649 to 927 °C (1200 to 1700 °F) band. Above 927 °C strength falls away quickly: yield strength drops from 507 MPa at 871 °C to 132 MPa at 982 °C.
What is the heat treatment for UNS N07208 forgings?
The standard cycle is a solution anneal at 1121 to 1149 °C (2050 to 2100 °F) with rapid cooling, followed by two-step ageing: 1010 °C (1850 °F) for 2 hours air cool, then 788 °C (1450 °F) for 8 hours air cool. Two alternatives exist: 899 °C for 4 hours plus 788 °C for 8 hours for higher containment capability, and a single step of 802 °C for 8 hours required by the ASME code. Jiangyin Jiangnan Metal Co., Ltd. runs any of the three on request.
What is the density of UNS N07208?
8.27 g/cm³ (0.299 lb/in³) in the solution-annealed condition, and 8.29 g/cm³ (0.300 lb/in³) after age hardening. Use 8.27 g/cm³ for forging weight estimates.
Does UNS N07208 contain niobium?
No. Niobium is limited to 0.2 percent maximum as a residual. All precipitation strengthening comes from the gamma-prime phase Ni3(Al,Ti), formed from 1.38 to 1.65 percent aluminium and 1.90 to 2.30 percent titanium. This is the main metallurgical difference from Inconel 718, which relies on niobium-bearing gamma double prime.
Is UNS N07208 weldable?
Yes. UNS N07208 is more weldable than other alloys of comparable strength. Its resistance to strain-age cracking approaches Alloy 263 and is far better than Waspaloy or R-41, because the gamma-prime volume fraction is only 15 to 20 percent and precipitation is slow. Weld in the solution-annealed condition using GTAW or GMAW with matching filler, keep interpass temperature below 93 °C, then age. Submerged arc welding is not recommended.
UNS N07208 or Waspaloy: which should be specified?
Specify UNS N07208 where the part is welded or complex, or where it runs above about 815 °C. Its 1 percent creep strength exceeds Waspaloy across the whole 649 to 927 °C range, and its rupture strength is comparable at the low end and better at the high end, while being substantially easier to weld and form. Waspaloy has higher room-temperature yield strength, so for a machined-from-solid part that runs cool, Waspaloy may be the better choice.
What forms of UNS N07208 can you forge?
Jiangyin Jiangnan Metal Co., Ltd. produces UNS N07208 as forged rings, seamless rolled rings, flanges, round bars, discs, sleeves, bushings, shafts, eccentric shafts, tube sheets, forged pipes and tubes, valve bodies and seat rings, nozzles, blocks, wheels and near-net-shape preforms. All are made to drawing; there is no stock list for this grade.
What certification comes with the forgings?
EN 10204 3.1 certificates as standard, or EN 10204 3.2 with a third-party witness such as SGS, BV, TUV or Lloyd's. Ultrasonic testing is performed to EN 10228-3, SEP 1921 or ASTM A388 as specified. Chemical analysis, tensile results, hardness, grain size and a dimensional report are issued with the certificate.
How do I get a quotation?
Send a drawing or size list to sales@steelforgepieces.com, or call +86 189 2135 9659. Include quantity, delivery condition, NDT acceptance class and certificate type. Quotations are normally returned within 24 hours on working days. The factory is at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China.
Standards and sources
- ASTM B637, Standard Specification for Precipitation-Hardening and Cold Worked Nickel Alloy Bars, Forgings, and Forging Stock for Moderate or High Temperature Service. ASTM International.
- SAE AMS 5915, nickel alloy billet, rod, bar and forgings, UNS N07208.
- SAE AMS 5951, nickel alloy sheet, plate and strip, UNS N07208.
- ASME Boiler and Pressure Vessel Code, Code Case 3024; ASME B31 Case 219.
- Haynes International, HAYNES® 282® alloy principal features and property data. Source of the tensile, creep, physical property and heat-treatment data above.
- EN 10204, metallic products, types of inspection documents. EN 10228-3, SEP 1921 and ASTM A388, ultrasonic testing of forgings.
Trademark notice. HAYNES® and 282® are registered trademarks of Haynes International, Inc. Jiangyin Jiangnan Metal Co., Ltd. is not affiliated with, endorsed by, sponsored by, or a licensee of Haynes International, Inc. These trademarks appear on this page only to identify the material grade to which UNS N07208 corresponds, so that engineers searching by trade name can locate the correct UNS designation. Waspaloy and Inconel are trademarks of their respective owners.