Key takeaways
- Nickel alloys group into seven types by their main additions: nickel-copper, nickel-chromium(-iron), nickel-molybdenum, nickel-chromium-molybdenum, iron-nickel-chromium, wrought superalloys and cast superalloys.
- The addition explains the application: copper for seawater, molybdenum for acids, chromium and aluminium for heat, aluminium, titanium and niobium for strength.
- Corrosion grades come from chemical, oil and gas and marine plant; superalloys from gas turbines, engines and furnaces.
- The application of an alloy predicts the grade, form and contaminants of its scrap.
Nickel alloy grades are easier to understand once you stop treating them as a list of trade names and start grouping them by what is added to the nickel and why. Copper gives seawater resistance; chromium gives heat and oxidation resistance; molybdenum fights acids; aluminium and titanium give strength at temperature. The application follows from the recipe.
This page is a reference table of every nickel alloy and superalloy grade on this site, with its UNS number, alloy system and typical applications, grouped by family and linked to its grade page. It covers what the alloys do in service. What happens to them once they become scrap is covered in uses of nickel alloy scrap, and how scrap grades are valued in nickel alloy scrap grades.
What Are the Main Types of Nickel Alloys?
Nickel alloys are usually grouped by their main additions into seven types, and each type has a distinct job.
- Nickel-copper. About two-thirds nickel and one-third copper. Seawater, hydrofluoric acid and alkalis. Monel 400 and K-500.
- Nickel-chromium and nickel-chromium-iron. Oxidation and heat resistance, plus caustic and high-purity water service. Inconel 600, 601 and 690, Nimonic 75, Haynes 214.
- Nickel-molybdenum. Reducing acids, above all hydrochloric. Hastelloy B-2.
- Nickel-chromium-molybdenum. Mixed and changing chemistry, chlorides, flue gas and sour service. Inconel 625, Hastelloy C-276 and C-22.
- Iron-nickel-chromium. Sulfuric and phosphoric acid and sour oil and gas at lower alloy cost. Incoloy 825 and 925, 20Mo-4.
- Age-hardened wrought superalloys. High strength at temperature from fine precipitates. Inconel 718 and 706, Nimonic 80A and C-263, Haynes 282, Udimet 500.
- Cast superalloys. Turbine blades, vanes and wheels, including directionally solidified and single-crystal parts. Inconel 713C, IN-939, René, MAR-M, GTD and MGA alloys.
- 29CuCopperseawater and hydrofluoric acid resistance in Monel
- 24CrChromiumoxidation, scaling and oxidising-acid resistance
- 42MoMolybdenumreducing acids, pitting and crevice resistance
- 26FeIronlowers alloy cost and suits iron-nickel grades
- 41NbNiobiumstrength in 718 and 706 and stability in 625
- 13AlAluminiumprotective scale and precipitation strength in superalloys
- 27CoCobalthot strength in cast and wrought superalloys
- 74WTungstenpitting resistance in C-276 and hot strength in Haynes 230
Inconel Grades and Applications
Inconel grades are nickel-chromium alloys that range from simple heat-resisting sheet to cast turbine superalloys.
| Grade | UNS | Alloy system | Typical applications |
|---|---|---|---|
| Inconel 600 | N06600 | Ni-Cr-Fe, solid solution | Furnace muffles and retorts, caustic evaporators, thermocouple sheaths |
| Inconel 601 | N06601 | Ni-Cr-Fe-Al, solid solution | Radiant tubes, furnace baskets and trays, combustion equipment |
| Inconel 617 | N06617 | Ni-Cr-Co-Mo, solid solution | Gas turbine combustion cans and ducts, nitric acid catalyst supports |
| Inconel 625 | N06625 | Ni-Cr-Mo-Nb, solid solution | Subsea and process pipe, scrubbers, bellows, aerospace exhaust ducting |
| Inconel 690 | N06690 | High-Cr Ni-Cr-Fe | Nuclear steam generator tubing, nitric acid equipment |
| Inconel 706 | N09706 | Fe-Ni-Cr, age-hardened | Large land-based gas turbine discs, wheels and shafts |
| Inconel 713C | N07713 | Cast superalloy | Turbocharger wheels, small turbine wheels, blades and vanes |
| Inconel 718 | N07718 | Ni-Cr-Fe-Nb, age-hardened | Jet engine discs and casings, wellhead and downhole parts, bolting |
| IN-939 | Trade name and OEM specification | Cast superalloy | Nozzle guide vanes in industrial and marine gas turbines |
A fuller account of the family, including how its scrap is grouped, is in what is Inconel scrap.
Hastelloy, Incoloy and Monel Grades and Applications
These three families are the corrosion workhorses: Hastelloy for acids and chlorides, Incoloy for sulfuric acid and sour service, Monel for seawater and hydrofluoric acid.
| Grade | UNS | Alloy system | Typical applications |
|---|---|---|---|
| Hastelloy B-2 | N10665 | Ni-Mo | Hydrochloric acid reactors, pumps and valves |
| Hastelloy C-276 | N10276 | Ni-Mo-Cr-W | Flue-gas desulfurisation, chlorination and bleach equipment, reactors, sour gas parts |
| Hastelloy C-22 | N06022 | Ni-Cr-Mo-W | Pharmaceutical reactors, pickling lines, bleach plants, scrubbers |
| Hastelloy X | N06002 | Ni-Cr-Fe-Mo, heat-resisting | Gas turbine combustors and transition ducts, furnace parts |
| Incoloy 825 | N08825 | Fe-Ni-Cr-Mo-Cu | Sulfuric acid pickling, phosphoric acid evaporators, clad pipe for sour service |
| Incoloy 925 | N09925 | Fe-Ni-Cr, age-hardened | Downhole tools, tubing hangers, valve stems and fasteners in H₂S service |
| 20Mo-4 | N08024 | Ni-Fe-Cr-Mo | Sulfuric and phosphoric acid piping, pickling equipment, mixed-acid exchangers |
| Monel 400 | N04400 | Ni-Cu | Seawater valves and pumps, feedwater heaters, refinery HF alkylation units |
| Monel K-500 | N05500 | Ni-Cu, age-hardened | Pump and propeller shafts, oil-well tools, doctor blades, springs |
Two of these are commonly confused with their neighbours: Incoloy 825 with Inconel 625, and Hastelloy C-276 with C-22. Grade descriptions for Hastelloy are expanded in Hastelloy scrap grades and uses; for Monel, see Monel 400 vs K-500.
Nominal values from the grade pages; specification limits vary by product form.
Wrought Superalloy Grades and Applications
Wrought superalloys are sheet, bar and forging alloys built for strength and oxidation resistance in gas turbines, engines and furnaces. Most are hardened by γ′ precipitates of nickel with aluminium and titanium, which the article on γ′ in superalloys explains.
| Grade | UNS | Alloy system | Typical applications |
|---|---|---|---|
| Nimonic 75 | N06075 | Ni-Cr, solid solution | Gas turbine sheet parts, heat-treatment fixtures, thermocouple sheaths |
| Nimonic 80A | N07080 | Ni-Cr-Ti-Al, age-hardened | Turbine blades and rings, engine exhaust valves, hot bolting |
| Nimonic C-263 | N07263 | Ni-Co-Cr-Mo, age-hardened | Combustion chambers, transition liners, turbine casings |
| Haynes 214 | N07214 | Ni-Cr-Al, alumina-forming | Furnace mesh belts, honeycomb seals, burner parts |
| Haynes 230 | N06230 | Ni-Cr-W-Mo, solid solution | Combustors and transition ducts, radiant tubes, catalyst grids |
| Haynes 282 | N07208 | Ni-Cr-Co-Mo, γ′ age-hardened | Combustors, casings and rings, advanced steam plant parts |
| Udimet 500 | N07500 | Ni-Co-Cr-Mo, γ′ age-hardened | Blades, vanes and discs in legacy gas turbines |
Cast Superalloy Grades and Applications
Cast superalloys are investment-cast into turbine blades, vanes, nozzles and wheels, where no wrought alloy would survive the combination of temperature and stress. Many carry no UNS number and are known by their trade or turbine-maker designation.
| Grade | Designation | Alloy system | Typical applications |
|---|---|---|---|
| René N5 | Trade name | Single-crystal, Re-bearing | High-pressure turbine blades and vanes |
| René 108 | Trade name | Directionally solidified, W-Hf | Turbine blades and vanes |
| René 125 | Trade name | Cast, Ta-W-Hf | Turbine blades and vanes |
| René 77 | Trade name | Cast and wrought γ′, 15% Co | Turbine blades, wheels and integral rotors |
| René 80 | Trade name | Cast γ′, high Ti | Turbine blades (buckets) and vanes |
| MAR-M 246 | Trade name | Cast γ′, 10% W, 10% Co | Blades, vanes, integrally cast wheels |
| MAR-M 247 | Trade name | Cast γ′, Hf-bearing | Directionally solidified and equiaxed blades, turbine wheels |
| GTD-111 | OEM designation | Cast γ′ | First- and second-stage buckets in heavy-duty gas turbines |
| GTD-222 | OEM designation | Cast γ′, Cr-Co | Second- and third-stage nozzles |
| GTD-241 | OEM designation | Cast γ′, Cr-Co-Nb | Gas turbine nozzles |
| GTD-262 | OEM designation | Cast γ′, higher Al | Gas turbine nozzles |
| MGA 1400, 1400DS and 2400 | OEM designation | Cast nickel superalloys | Hot-section parts in heavy-duty gas turbines |
Inconel 713C and IN-939, listed with the Inconels above, belong to this group too. Selling this material is a specialist business, covered in turbine blade scrap.
How Do Engineers Choose Between Similar Nickel Alloy Grades?
Engineers usually climb a ladder: they pick the leanest alloy that survives the service, and move up only when it does not. Each step adds cost, so the grade found in a plant tells you something about how hard its service was.
For Acids and Chlorides
A common progression runs from duplex and 254 SMO, through Incoloy 825 and 20Mo-4, to Inconel 625, and then to Hastelloy C-276 or C-22 for the most aggressive mixed chemistry. Hastelloy B-2 sits off to one side, chosen only for reducing acids such as hydrochloric. The Incoloy 825 vs Inconel 625 comparison shows what the step from iron-nickel to nickel-base buys.
For Furnaces and Hot Gas
Inconel 600 serves to around 1,100 °C (2,010 °F), and 601, with more chromium and some aluminium, to about 1,200 °C (2,190 °F). Haynes 214 forms an alumina scale for oxidation resistance at roughly 950–1,150 °C (1,740–2,100 °F), while Haynes 230 and Hastelloy X add strength for combustors and radiant tubes. Where strength under load matters more than scaling, the choice moves to 617, Nimonic C-263 or Haynes 282.
For Strength at Temperature
Wrought discs and shafts use 718 up to about 650 °C (1,200 °F), or 706 for very large land-turbine forgings. Above that, blades and vanes move to cast alloys, then to directionally solidified and finally single-crystal grades such as René N5, each step tolerating more heat.
Which Nickel Alloys Are Used for Corrosion, and Which for Heat?
Corrosion grades are chosen for what they resist in liquid; heat-resisting grades and superalloys for how they behave in hot gas under load. A few alloys sit in both camps.
- Wet corrosion: Monel 400 and K-500, Hastelloy B-2, C-276 and C-22, Inconel 625 and 690, Incoloy 825 and 925, 20Mo-4.
- Oxidation and heat resistance: Inconel 600 and 601, Nimonic 75, Haynes 214 and 230, Hastelloy X.
- Strength at temperature: Inconel 617, 706 and 718, Nimonic 80A and C-263, Haynes 282, Udimet 500 and the cast superalloys.
Inconel 600 and 625 are the clearest examples of dual use: 600 serves both furnaces and caustic plant, and 625 both seawater piping and aerospace exhaust ducting.
| Oil and gas | Chemical plant | Aerospace | Power generation | Furnaces | Marine | |
|---|---|---|---|---|---|---|
| Inconel | ● | ● | ● | ● | ● | ◐ |
| Hastelloy | ◐ | ● | ◐ | ◐ | ◐ | ○ |
| Incoloy | ● | ● | ○ | ○ | ○ | ○ |
| Monel | ● | ◐ | ○ | ○ | ○ | ● |
| Nimonic and Haynes | ○ | ◐ | ● | ● | ● | ○ |
| Cast superalloys | ○ | ○ | ● | ● | ○ | ◐ |
● yes ◐ partly ○ no
How Does the UNS Number Hint at the Alloy Type?
The UNS number gives a rough guide to the alloy system before you read the composition. Nickel alloys carry an N prefix, and within it the series tend to cluster: N04 and N05 for nickel-copper (Monel 400 and K-500), N06 for nickel-chromium solid-solution grades (600, 625, C-22, X), N07 for age-hardened nickel-chromium grades (718, 80A, 282), N08 for iron-nickel-chromium grades (825, 20Mo-4), N09 for some age-hardened iron-nickel grades (706, 925) and N10 for nickel-molybdenum grades (B-2, C-276). The rule is loose, so always check the composition. The full system is explained in how UNS numbers work, and the equivalent grade chart lists W.Nr. and EN equivalents.
Which Nickel-Bearing Grades Are Not Nickel Alloys?
Several grades carry plenty of nickel but are iron-base, and are classed as stainless steel or cast iron rather than nickel alloy. 254 SMO has about 18% nickel; duplex 2205 and the super duplex grades about 5.5–7%; Ni-Resist austenitic cast irons 15–35%. They often serve beside nickel alloys in seawater and chemical plant, and they appear in the same scrap streams. See 254 SMO scrap and Ni-Resist scrap.
Why Does a Nickel Alloy’s Application Matter When It Becomes Scrap?
Because the application tells you the likely grade, form and contaminants before anyone reads a piece. Refinery Monel may carry acid residues; scrubber Hastelloy may be lined steel; turbine superalloys may be coated and brazed; oilfield 625 may be weld overlay on carbon steel. Knowing this lets a seller sort and describe the lot properly. The industry guide to nickel alloy scrap maps applications to the scrap they produce.
Mipra Steel buys and supplies scrap of every grade listed here, by grade, from Khetwadi, Mumbai, with offices in Dubai and South Korea. If you have material to sell or a grade to source, send the grade, form, weight, location and any readings, and we’ll review your enquiry.
Submit a requirement with the grade, form, quantity and delivery location.
Source a GradeFAQ
What is the most widely used nickel alloy?
Inconel 625 and Inconel 718 are among the most widely specified. 625 is the general corrosion-resistant grade for seawater, flue gas, chemical plant and subsea pipe; 718 is the general high-strength grade for jet engine discs, casings and oilfield parts. Hastelloy C-276 plays the equivalent role for aggressive chemical service.
What is the difference between a nickel alloy and a superalloy?
A superalloy is a nickel, cobalt or iron-nickel alloy designed to keep high strength close to its melting point, usually through γ′ or γ″ precipitates. All the nickel superalloys here are nickel alloys, but not every nickel alloy is a superalloy: Monel 400, Hastelloy C-276 and Inconel 600 are corrosion or heat-resisting alloys without that precipitation strength.
Is Incoloy a nickel alloy?
It is usually grouped with nickel alloys, though Incoloy 825 and 925 carry a large share of iron alongside about 42–44% nickel. Their UNS numbers start with N, and they are made to ASTM B specifications like other nickel alloys. In scrap they are sold as Incoloy and kept apart from Inconel.
Which nickel alloy is best for seawater?
There is no single answer, because it depends on the part and the conditions. Monel 400 is long established for seawater valves, pumps and piping, Monel K-500 for high-strength shafts, and Inconel 625 for subsea pipe and critical hardware. Super duplex and 254 SMO are iron-base alternatives often used in the same systems.
Which nickel alloys are used in gas turbines?
Wrought alloys such as Inconel 617, 718, Hastelloy X, Haynes 230 and 282, and Nimonic 80A and C-263 are used for combustors, casings, rings and discs. Cast superalloys, including René, MAR-M, GTD, MGA, Inconel 713C and IN-939, are used for blades, vanes and nozzles in the hottest sections.
Why are nickel alloys used instead of stainless steel?
Nickel alloys are chosen when stainless steel would corrode, crack or lose strength. They resist chloride stress-corrosion cracking, reducing acids, hydrofluoric acid and hot oxidising gas far better, and superalloys keep their strength at temperatures where stainless steel softens. The trade-off is cost, so they are used where the service demands them.
Where can I compare the composition of two nickel alloys?
The alloy comparison tool sets the nominal composition of any two grades side by side and shows which elements separate them on an analyser. The nominal composition tables list the main elements of every grade on the site, grouped by family.
