Nickel Superalloy Forgings · Technical Datasheet
Udimet 720 Forgings
U720 · U720Li · Udimet Alloy 720 · NiCr18Co15TiMoAl · Forged rings, discs, shafts, flanges and bars
Udimet 720 is a gamma-prime strengthened nickel-based superalloy with roughly 16 % chromium, 15 % cobalt, 5 % titanium and 2.5 % aluminium, developed for gas turbine discs and blades that must hold their strength at 650 to 815 °C. Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No. 1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, forges Udimet 720 and Udimet 720Li into seamless rolled rings, discs, shafts, flanges, sleeves, bushings and round bars to ASTM B637 or customer drawing, supplied with EN 10204 3.1 or 3.2 mill test certificates.
Send drawing for a quote Call 0086-189-2135-9659
What is Udimet 720?
Udimet 720, also written U720 and Udimet Alloy 720, is a wrought nickel-based superalloy strengthened by the precipitation of gamma prime, Ni3(Al,Ti). It was developed for land-based gas turbine blades and later modified into Udimet 720Li for high-strength rotating discs. Chromium at about 16 % carries the oxidation and hot-corrosion resistance. Molybdenum and tungsten strengthen the nickel matrix in solid solution. Titanium at about 5 % and aluminium at about 2.5 % form roughly 45 % gamma prime by volume. That precipitate fraction carries the strength and creep resistance at temperature.
The same gamma prime fraction makes the alloy hard to process. The hot-working window is narrow, the material work-hardens quickly, and forging has to be held sub-solvus on heated dies to avoid cracking. Udimet 720 is bought to drawing from a forge shop rather than pulled from warehouse stock.
Jiangyin Jiangnan Metal supplies Udimet 720 as forged product only: open-die forgings and seamless rolled rings. Forging closes ingot porosity and aligns grain flow with the principal stress direction in discs, rings and shafts, which is where a forged part gains fatigue life over one machined from billet.
| Designation | Notes |
|---|---|
| Udimet 720 / U720 | Original grade, chromium about 18 %, developed for turbine blades and vanes |
| Udimet 720Li / U720Li | Low-interstitial variant, chromium about 16 %, low carbon and boron, used for rotating discs |
| Udimet Alloy 720 | Full trade designation used by the alloy originator |
| NiCr18Co15TiMoAl | Descriptive chemical designation used in European enquiries |
| Commercial standard | ASTM B637 (precipitation-hardening nickel alloy bars, forgings and forging stock) |
| UNS number | No universally published UNS number. Ordered to OEM specification or customer drawing. |
Source: Jiangyin Jiangnan Metal Co., Ltd., Udimet 720 forging specification. Udimet® is a registered trademark of Special Metals Corporation, used here only to identify the alloy grade.
Udimet 720 vs Udimet 720Li
Buyers frequently ask which of the two to specify. 720Li is used for rotating discs and for any part that will spend thousands of hours at temperature. U720 is used for blades, vanes and static hot-section hardware. Tell us which one the drawing calls for; the chemistry limits differ and the two are not interchangeable on a certificate.
| Attribute | Udimet 720 | Udimet 720Li |
|---|---|---|
| Chromium | ~17.9-18.0 % | 15.5-16.5 % |
| Carbon | ~0.035 % | 0.010-0.020 % |
| Boron | ~0.033 % | 0.010-0.020 % |
| Sigma phase risk | Higher after long exposure | Suppressed by lower chromium |
| Cleanliness and forgeability | Good | Better, fewer carbide and boride stringers |
| Typical use | Turbine blades, vanes, static hot-section parts | Turbine discs, spacers, shafts, seal rings |
| Typical service ceiling | up to ~815 °C / 1500 °F | up to ~700 °C / 1290 °F |
Source: Jiangyin Jiangnan Metal Co., Ltd., compiled from published alloy specifications. See also Udimet 520 and Udimet 500.
Why Udimet 720 is specified
- About 45 % gamma prime gives it a higher strength-to-temperature capability than Inconel 718 or Waspaloy in the 600 to 750 °C band where turbine discs run.
- Good creep and stress-rupture resistance, so the part holds its dimensions through long hold periods at temperature.
- Chromium at 16 to 18 % gives oxidation and hot-corrosion resistance in combustion gas.
- Strength can be tuned by processing: sub-solvus solution treatment for a fine grain and high tensile and low-cycle-fatigue strength, super-solvus for a coarse grain and better creep and crack-growth resistance.
- It responds to three strengthening mechanisms at once: precipitation hardening, solid-solution hardening from molybdenum and tungsten, and work hardening.
- Forged product gives continuous grain flow, which matters for rotating discs and rings where a machined-from-billet part would cut through the flow lines.
Chemical composition of Udimet 720
The table below is the specification range we forge to, corresponding to the low-interstitial (720Li) chemistry. Every heat is supplied with a ladle analysis on the mill certificate; product analysis can be added on request. Where a drawing calls for the original higher-chromium U720, the chromium, carbon and boron limits are adjusted accordingly.
| Element | Symbol | Weight % | Function |
|---|---|---|---|
| Nickel | Ni | Balance | Gamma matrix |
| Chromium | Cr | 15.5-16.5 | Oxidation and hot-corrosion resistance |
| Cobalt | Co | 14.0-15.5 | Lowers stacking fault energy, raises gamma prime stability |
| Titanium | Ti | 4.75-5.25 | Primary gamma prime former |
| Molybdenum | Mo | 2.75-3.25 | Solid-solution strengthening |
| Aluminium | Al | 2.25-2.75 | Gamma prime former, oxidation resistance |
| Tungsten | W | 1.00-1.50 | Solid-solution strengthening |
| Zirconium | Zr | 0.025-0.050 | Grain boundary strengthening |
| Carbon | C | 0.010-0.020 | Carbide control, held low in the Li grade |
| Boron | B | 0.010-0.020 | Grain boundary strengthening, creep ductility |
Source: Jiangyin Jiangnan Metal Co., Ltd., Udimet 720 forging specification. Ladle analysis is reported on every EN 10204 certificate.
Mechanical properties of forged Udimet 720
The certified minima are the contractual floor written on the mill certificate. The typical column shows what fully solution-treated and aged Udimet 720 tests at in practice, well above those minima, since the alloy is bought for hot strength rather than for a room-temperature acceptance number.
| Property | Certified minimum | Typical, fully aged | Test method |
|---|---|---|---|
| Ultimate tensile strength | ≥ 1103 MPa (160 ksi) | 1450-1600 MPa | ASTM E8 / ISO 6892-1 |
| Yield strength, 0.2 % offset | ≥ 862 MPa (125 ksi) | 1050-1200 MPa | ASTM E8 / ISO 6892-1 |
| Elongation in 4D | ≥ 20 % | 12-20 % | ASTM E8 |
| Reduction of area | by agreement | 15-25 % | ASTM E8 |
| Hardness | by agreement | 38-45 HRC | ASTM E18 / E10 |
| Grain size | to drawing | ASTM 6-10 sub-solvus | ASTM E112 |
Source: Jiangyin Jiangnan Metal Co., Ltd. Certified minima apply to material ordered to ASTM B637-style acceptance. Typical values are indicative of the fully aged condition and vary with section size, grain size and heat-treatment route; the mill certificate for your heat is the governing document. Elevated-temperature, creep and low-cycle-fatigue data are issued on request for a specified temperature and section.
Physical and thermal properties
| Property | Metric | Imperial |
|---|---|---|
| Density | 8.08 g/cm³ | 0.292 lb/in³ |
| Modulus of elasticity, 20 °C | ~210 GPa | ~30 500 ksi |
| Gamma prime solvus | ~1150-1160 °C | ~2100-2120 °F |
| Gamma prime volume fraction | ~45 % | ~45 % |
| Service ceiling, disc duty | ~700 °C | ~1290 °F |
| Service ceiling, blade and vane duty | ~815 °C | ~1500 °F |
| Thermal conductivity | Low, typical of high gamma prime superalloys | Heat concentrates at the cutting edge in machining |
| Magnetic response | Non-magnetic in the solution treated and aged condition |
Source: Jiangyin Jiangnan Metal Co., Ltd., consolidated from published Udimet 720 and 720Li data. Physical values are typical for the alloy family and are not certified values; certified data comes from the mill certificate for your heat.
Heat treatment and the Udimet 720 temperature map
Processing is set relative to the gamma prime solvus, near 1150 °C. Solution treat below it and the un-dissolved primary gamma prime pins the grain boundaries, giving a fine grain, high tensile strength and good low-cycle fatigue life. Solution treat above it and the grain coarsens, which improves creep and crack-growth resistance but costs tensile strength. Tell us which route the drawing requires; it changes both grain size and price.
| Step | Temperature | Soak | Cooling |
|---|---|---|---|
| Solution anneal | 1121 °C (2050 °F) | Section dependent | Rapid air cool |
| First age | 1113 °C (2035 °F) | 2 h | Air cool |
| Second age | 1079 °C (1975 °F) | 4 h | Oil quench |
| Third age | 649 °C (1200 °F) | 24 h | Air cool |
| Fourth age | 760 °C (1400 °F) | 8 h | Air cool |
Source: Jiangyin Jiangnan Metal Co., Ltd., published Udimet 720 cycle. Furnace charts for every cycle are issued with the mill certificate. Where an OEM specification prescribes a different route, we run the customer cycle and certify against it.
How Jiangyin Jiangnan Metal forges Udimet 720
The route below is what we run for every Udimet 720 order. Each stage produces a record that goes into the documentation pack.
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Melt route and billet sourcing
Billet is bought only against documented vacuum melt practice: VIM plus ESR or VIM plus VAR as a minimum, triple melt VIM + ESR + VAR where the drawing requires it. Air-melted material is not accepted for a gamma-prime alloy of this level.
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Homogenisation and billet conditioning
Surfaces are conditioned to remove defects that would open up under the press. The billet is soaked to a uniform through-temperature; an under-soaked Udimet 720 billet cracks on the first blow.
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Sub-solvus open-die forging on heated dies
Press forging below the gamma prime solvus with controlled reduction ratios, low strain rate and intermediate reheats. Grain flow is directed along the hoop for rings and along the axis for shafts.
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Ring rolling or upsetting to shape
Seamless rings are pierced and rolled to the finished envelope. Discs are upset and punched. Both routes give continuous grain flow through the section.
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Solution treatment and multi-stage ageing
Charged into calibrated furnaces to the sub-solvus or super-solvus route, with recorded time and temperature charts for the whole load and controlled quench media.
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Rough or finish machining
Supplied as-forged, rough machined with an agreed allowance, or finish machined to drawing tolerance. Most Udimet 720 parts leave rough machined so the customer controls the final surface.
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Non-destructive and mechanical testing
Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388. Penetrant or magnetic particle as specified. Tensile, hardness and grain size from integral or separately forged prolongations.
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Marking, certification and packing
Hard-stamped heat number and part identification, EN 10204 3.1 certificate, or 3.2 counter-signed by a third party such as TUV, BV, SGS or Lloyd's Register, then seaworthy packing.
Udimet 720 forged forms and size capability
All parts are made to your drawing or dimensional sketch. There is no fixed catalogue. Because Udimet 720 has a narrow hot-working window, the practical size range is tighter than for Inconel 625 or stainless grades. Sizes beyond the range below are quoted case by case.
| Forged form | Size range | Common uses |
|---|---|---|
| Seamless rolled rings | OD 200-1500 mm, H up to 500 mm | Seal rings, spacer rings, casing rings |
| Forged discs | Dia. 150-1000 mm | Turbine discs, blade carriers, blanks |
| Forged shafts and spindles | Dia. 80-400 mm, L up to 3000 mm | Rotor shafts, stub shafts, drive spindles |
| Round bars and blanks | Dia. 20-400 mm | Blade and vane blanks, fasteners, valve stems |
| Forged flanges | to ASME B16.5 / B16.47 / EN 1092-1 or drawing | Hot gas piping, high-temperature connections |
| Sleeves, bushings, hollow bars | OD 100-800 mm | Bearing housings, wear sleeves, liners |
| Blocks and profiled sections | to drawing | Valve bodies, manifolds, machining stock |
| Single-piece weight | 10 kg to 2000 kg | Heavier pieces quoted case by case |
Source: Jiangyin Jiangnan Metal Co., Ltd. Delivery conditions: as-forged, heat-treated, rough machined or finish machined.
Where Udimet 720 forgings are used
Udimet 720 is chosen where a rotating or hot-section part has to keep its strength, its dimensions and its fatigue life at temperatures that would soften Inconel 718.
Gas turbines, aero and land-based
The primary application. Discs and shafts run in the 600 to 700 °C band. Blades and vanes run hotter.
Power generation
Hot-section rotating and static parts where creep and thermal fatigue set the overhaul interval on industrial turbines and compressors.
Pressure and heat-exchange equipment
Forged flanges, tube sheets and nozzles for high-temperature vessels, air receivers and shell-and-tube exchangers.
Oil, gas and subsea
Deepwater production hardware, wellhead and Christmas tree parts, and compressor components that see high stress at temperature.
Rotating machinery and power transmission
Gear blanks, spindles and eccentric shafts for compressors, gearboxes and heavy drives running hot.
Heavy and process industry
Forged wheels, manifolds, rolls and crystalliser parts for shipbuilding, pulp and paper, pharmaceutical and biochemical plant.
Machining, welding and handling
Machining
Udimet 720 is machined by conventional methods but sits at the difficult end of the nickel superalloy range. Three properties account for this. It work-hardens quickly, so a rubbing or dwelling tool leaves a hardened layer that is worse to cut on the next pass. Thermal conductivity is low, so shear-zone heat concentrates at the cutting edge instead of leaving in the chip. Hard titanium and aluminium-rich carbonitrides abrade the flank. Use rigid setups, sharp coated carbide or ceramic inserts, positive rake, reduced surface speed with adequate feed, and high-pressure coolant. Never let the tool dwell in the cut.
Welding
High gamma prime alloys are prone to strain-age cracking during post-weld heat treatment, so welding on Udimet 720 is a qualified-procedure job, not a shop-floor repair. Discuss any weld requirement before the order is placed so the joint design, filler and post-weld cycle can be agreed.
Grinding and surface condition
Final surfaces on fatigue-critical parts should be produced by controlled grinding or gentle milling. Abusive machining leaves residual tensile stress and a white layer that reduces low-cycle fatigue life on a disc even when the dimensional report passes.
Udimet 720 compared with other forgeable superalloys
The table below is for checking a grade choice before the drawing is issued. Selection usually turns on the disc metal temperature and on how much machining the part needs after forging.
| Grade | Approx. gamma prime | Practical disc ceiling | Trade-off |
|---|---|---|---|
| Udimet 720 / 720Li | ~45 % | ~700 °C | Highest strength of the group, hardest to forge and machine |
| Waspaloy | ~25 % | ~650-700 °C | Easier to process, lower strength than 720 |
| Inconel 718 | gamma double prime | ~650 °C | Cheapest and easiest of the group, falls away above 650 °C |
| Udimet 500 / 520 | ~35-40 % | ~750-815 °C blade duty | Blade and vane grades, lower disc-duty fatigue strength |
| Rene 41 | ~35 % | ~870 °C static | Very high hot strength, difficult formability |
Source: Jiangyin Jiangnan Metal Co., Ltd., compiled from published alloy data. Values are indicative for grade selection, not design values.
Testing, inspection and certification
Every Udimet 720 forging ships with a documentation pack. The content is agreed before production starts.
- Chemical analysis: ladle analysis on every heat, product analysis on request.
- Mechanical testing: tensile, yield, elongation, reduction of area and hardness from integral or separately forged prolongations.
- Ultrasonic testing to EN 10228-3, SEP 1921 Class C, D or E, ASTM A388, or a customer-specified acceptance class.
- Surface NDT: liquid penetrant to ASTM E165, or magnetic particle where the geometry allows.
- Grain size and microstructure to ASTM E112, reported against the drawing requirement.
- Dimensional report against the drawing.
- Certification: EN 10204 3.1 as standard, or 3.2 witnessed and counter-signed by TUV, BV, SGS, Lloyd's Register or your own inspector.
- NACE MR0175 / ISO 15156 and PED 2014/68/EU documentation where the end use requires it.
Third-party inspectors and customer QA representatives are welcome at the works. We also ship the same material under the designations Udimet Alloy 720, U720Li and NiCr18Co15TiMoAl where a specification calls the grade by a different name.
How to request a Udimet 720 quotation
Send a drawing or a dimensional sketch to sales@steelforgepieces.com. Quotations are normally returned within one working day when the following points are supplied.
- Grade and specification: Udimet 720 or Udimet 720Li, and which specification governs, ASTM B637, an OEM specification, or your own drawing.
- Product form: ring, disc, shaft, bar, flange, sleeve or custom shape.
- Dimensions: OD, ID and height for rings, diameter and length for bars and shafts, plus an estimated finished weight.
- Delivery condition: as-forged, heat-treated, rough machined, or finish machined.
- Heat-treatment route and grain size: sub-solvus for fine grain and tensile or fatigue strength, super-solvus for coarse grain and creep resistance.
- Melt practice: double melt VIM + ESR or VIM + VAR, or triple melt if the drawing requires it.
- Certification: EN 10204 3.1 or 3.2, and which third party if 3.2.
- NDT requirements: UT acceptance class, PT or MT requirements, and any special acceptance criteria.
- Quantity and required delivery date.
Lead time for Udimet 720 forgings is normally 45 to 75 days depending on billet availability, size, heat-treatment route and machining scope. There is no fixed minimum order quantity and single prototype pieces are accepted.
Email your drawing to sales@steelforgepieces.com Call 0086-189-2135-9659
Frequently asked questions about Udimet 720
What is Udimet 720?
Udimet 720, also written U720 and Udimet Alloy 720, is a gamma-prime strengthened nickel-based superalloy containing roughly 16 % chromium, 15 % cobalt, 3 % molybdenum, 1.25 % tungsten, 5 % titanium and 2.5 % aluminium, with nickel as the balance. The high titanium and aluminium content produces about 45 % gamma prime by volume, which carries the strength and creep resistance at temperature. It is used for gas turbine discs, blades and shafts.
What is the difference between Udimet 720 and Udimet 720Li?
Udimet 720Li is the low-interstitial version. Chromium is reduced from about 18 % to about 16 % to suppress sigma phase formation during long exposure, and carbon and boron are cut to roughly 0.010 to 0.020 %. The result is better long-term microstructural stability and cleaner, more forgeable material, so 720Li is the version normally specified for rotating turbine discs. The original higher-chromium U720 is still used for blades and vanes.
What is the maximum service temperature of Udimet 720?
Udimet 720Li is typically applied to about 700 °C (1290 °F) in turbine disc duty, where fatigue and creep set the design limit. In blade and vane applications the alloy is used up to roughly 815 °C (1500 °F). Above the gamma prime solvus, near 1150 °C, the strengthening precipitates dissolve completely and the alloy loses its strength.
What is the chemical composition of Udimet 720?
The specification range we forge to is chromium 15.5–16.5 %, cobalt 14.0–15.5 %, molybdenum 2.75–3.25 %, tungsten 1.00–1.50 %, titanium 4.75–5.25 %, aluminium 2.25–2.75 %, carbon 0.010–0.020 %, zirconium 0.025–0.050 %, boron 0.010–0.020 % and nickel balance. Every heat is supplied with a ladle analysis on the mill certificate.
What is the heat treatment for Udimet 720?
The published cycle is a solution anneal at 1121 °C (2050 °F) with rapid air cooling, followed by a four-stage age: 1113 °C for 2 h air cooled, 1079 °C for 4 h oil quenched, 649 °C for 24 h air cooled, and 760 °C for 8 h air cooled. Sub-solvus solution treatment gives a fine grain with higher tensile and fatigue strength; super-solvus treatment gives a coarse grain with better creep resistance.
Is Udimet 720 difficult to forge?
Yes. With about 45 % gamma prime the alloy has a narrow hot-working window and cracks readily if the billet is under-soaked, the strain rate is too high, or the dies are too cold. Critical rotating parts are forged sub-solvus on heated dies with controlled reduction and intermediate reheats. This is why Udimet 720 forgings cost more per kilogram than Inconel 718 or Waspaloy parts of the same size.
How is Udimet 720 machined?
By conventional methods, but it sits at the difficult end of the nickel superalloy range. It work-hardens quickly, its thermal conductivity is low so heat concentrates at the cutting edge, and hard carbonitrides abrade the tool. Use rigid setups, sharp coated carbide or ceramic tooling, positive rake, constant feed without dwelling, reduced surface speed and high-pressure coolant. Many customers order rough machined with a finishing allowance and finish the part themselves.
Which standards cover Udimet 720 forgings?
Udimet 720 has no single universal grade standard and is normally ordered to an OEM specification or a customer drawing. ASTM B637, covering precipitation-hardening nickel alloy bars, forgings and forging stock for high-temperature service, is the usual commercial reference. We supply to ASTM B637 or to customer specification, with ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388, and EN 10204 3.1 or 3.2 certification.
What forged shapes are available in Udimet 720?
Jiangyin Jiangnan Metal Co., Ltd. produces Udimet 720 as seamless rolled rings, forged discs, shafts and spindles, round bars, flanges, sleeves, bushings, hollow bars, blocks, tube sheets and nozzles, all made to customer drawing. Sizes and single-piece weights outside the standard range are quoted case by case.
Who supplies Udimet 720 open-die forgings in China?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No. 1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, producing Udimet 720 and Udimet 720Li forged rings, discs, shafts, flanges and bars to drawing. Enquiries go to sales@steelforgepieces.com or 0086-189-2135-9659. Jiangyin lies in the Yangtze River Delta within two hours of Shanghai port, which keeps export logistics short for heavy forgings.
What certificates are supplied with Udimet 720 forgings?
EN 10204 3.1 mill test certificates are standard, covering chemical analysis, mechanical test results, heat-treatment charts, NDT reports and dimensional records. EN 10204 3.2 certificates counter-signed by TUV, BV, SGS or Lloyd's Register are available on request, as is NACE MR0175 and ISO 15156 documentation.
Is there a minimum order quantity for Udimet 720 forgings?
There is no fixed minimum order quantity and single prototype pieces are accepted. Price per piece falls with quantity because billet, tooling, set-up and furnace charges are shared across the order. Lead time is normally 45 to 75 days depending on size, heat-treatment route and machining scope.
About the manufacturer
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory in Jiangyin, Jiangsu Province, China. We produce forged rings, seamless rolled rings, discs, shafts, flanges, bars, sleeves and bushings in carbon steel, alloy steel, tool steel, stainless steel and nickel-based superalloys, including Udimet 720, Udimet 520, Udimet 500, Waspaloy, Inconel 718 and the Hastelloy family. Work is made to customer drawing and certified to EN 10204 3.1 or 3.2.
- Company
- Jiangyin Jiangnan Metal Co., Ltd.
- Address
- No. 1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province 214423, China
- Telephone
- 0086-189-2135-9659
- sales@steelforgepieces.com
- Website
- www.steelforgepieces.com
- Business
- Open-die forging, ring rolling, heat treatment, machining, testing
Data source and citation
The technical data on this page is published by Jiangyin Jiangnan Metal Co., Ltd. and may be quoted or reproduced with attribution. Suggested citation:
Jiangyin Jiangnan Metal Co., Ltd. Udimet 720 Forgings: U720 / U720Li Technical Datasheet. Jiangyin, Jiangsu, China. https://www.steelforgepieces.com/Nickel-Alloy/Udimet-720.html
Related nickel alloy grades we forge
- Udimet 500
- Udimet 520
- Waspaloy
- Rene 41
- Inconel 718
- Inconel 706
- Inconel 625
- Inconel X-750
- Incoloy 901
- Haynes 188
- Haynes 230
- Haynes 25
- Multimet N155
- MP159
- MP35N
- UNS N07252
- UNS N07208
- UNS N07022
- All nickel alloys
Page published 17 May 2016. Last reviewed and updated 28 August 2026 by the technical sales team, Jiangyin Jiangnan Metal Co., Ltd.