Waspaloy Forgings (UNS N07001, W.Nr. 2.4654, AMS 5704–5709)

Short answer: what Waspaloy is and what we make from it

UNS

N07001W.Nr. 2.4654

Density

8.19g/cm³ · 0.296 lb/in³

Rotating-part limit

650°C · 1200 °F

Static-part limit

870°C · 1600 °F

Tensile, aged

1,441MPa min · 209 ksi

Yield 0.2%, aged

1,076MPa min · 156 ksi

Solution

1080°C / 4 h / AC (route A)

Age

760°C / 16 h / AC

Forging window

980–1170°C · 1800–2140 °F

Max ring OD

2,500mm

Max piece

8,000kg

Lead time

12–16weeks typical

What Waspaloy forged products can you buy?

Jiangyin Jiangnan Metal produces UNS N07001 by three routes, chosen by geometry and order size. Open-die forging covers shafts, blocks and heavy discs. Seamless ring rolling produces rings from 200 mm to 2,500 mm outside diameter, which is the usual route for casing rings, seal rings and spacers. Upset forging handles short, large-section hubs, disc blanks and flanges. Because Waspaloy raw material costs roughly fifteen to twenty times as much per kilogram as carbon steel, near-net-shape practice matters far more here than on ordinary forgings: every kilogram of machining stock removed is a kilogram of vacuum-melted superalloy turned into chips.

• Seamless rolled rings
• Turbine disc and compressor disc blanks
• Forged shafts and spindles
• Forged spacers and seal rings
• Forged casings and casing rings
• Forged flanges
• Forged sleeves and bushings
• Forged discs and hubs
• Tube sheets
• Round, flat and square bar
• Forged blocks and blanks
• Trepanned hollow bar
• Valve bodies, stems and seat rings
• Fastener stock and bolt blanks
• Near-net custom forgings to drawing

What is Waspaloy / UNS N07001?

Waspaloy is a gamma-prime strengthened nickel superalloy. It was developed for aero-engine hot sections, and every feature of the alloy follows from that job. Chromium at 18–21% builds a protective chromia scale. Cobalt at 12–15% and molybdenum at 3.5–5.0% stiffen the nickel matrix by solid-solution strengthening and raise the temperature at which the matrix starts to soften. Titanium at 2.75–3.25% and aluminium at 1.20–1.60% precipitate as Ni₃(Al,Ti), the ordered γ′ phase, at roughly 20–25% volume fraction. Boron and zirconium at trace levels sit on grain boundaries and suppress creep cavitation.

What that chemistry buys, and what it costs:

• It keeps strength where alloy 718 loses it. Alloy 718 is hardened by γ″ (Ni₃Nb), which coarsens and converts to delta phase above roughly 650–704 °C. Waspaloy’s γ′ is stable well beyond that, so useful strength continues to 760 °C and above. That difference is what the extra cost buys.
• It is hard to make and hard to cut. The hot-working window is only about 190 °C wide, welding needs tight control, and machining is among the most difficult of the superalloys. These are processing costs, not property limits, and they are why Waspaloy parts are usually forged rather than machined from solid.
• It is a rotating-part alloy. Discs, shafts, spacers, seals, casing rings and fasteners in gas turbines are its home. It is chosen where a failure is not tolerable and where the alternative is a cast alloy that cannot take the fatigue loading.

What are the equivalent designations for Waspaloy?

Buyers meet this alloy under at least a dozen names. All of the designations below describe the same nominal 19Cr-13Co-4Mo-3Ti-1.4Al-Ni chemistry, and we accept purchase orders under any of them, but they are not interchangeable documents: they differ in product form, delivered condition, melt route and acceptance testing.

Standards are cited by number only. Always reference the revision in force at the contract date, and state the product form: a specification written for bar does not automatically govern a rolled ring.

What is the chemical composition of Waspaloy?

The table below is the limiting composition for UNS N07001 and it is what we buy raw material against unless a drawing calls for a tighter band. Commercial heats for aero-engine work are normally bought to a much narrower window than the UNS limits, defined order by order. Every heat is supplied with a ladle analysis on the mill certificate; product analysis can be added on request.

Composition to UNS N07001. Aerospace orders are routinely placed against a tighter internal band, and trace-element ceilings on lead, bismuth, selenium, silver and oxygen/nitrogen may be added by the purchaser. State those limits at enquiry stage, because they change which mills can supply the heat.

What are the mechanical properties of Waspaloy?

Waspaloy only has useful properties after the full three-step heat treatment. In the solution-treated condition it is comparatively soft at 20–25 HRC. That is the machining and welding condition, not a service condition. The numbers below are the room-temperature minima we certify on solution-treated, stabilised and aged forgings.

These are the acceptance minima applied on our certificates for aged forgings; a certificate must beat them. Individual AMS and ASTM specifications set their own acceptance values by product form, section size and condition, and a heavy section tested transversely will read lower than a longitudinal test on bar. State the test direction and location on the drawing.

Strength against temperature

Modulus falls steadily with temperature, from 211 GPa at 21 °C to 184 GPa at 538 °C and 157 GPa at 871 °C. Tensile and yield strength hold up well to about 700 °C and then fall away; above roughly 650 °C the design is almost always controlled by creep and stress rupture rather than by short-term tensile strength, so for hot-section parts the rupture table below matters more than the tensile table above.

Creep and stress-rupture strength

Rupture strength is what most Waspaloy is bought for. The values below are typical 1,000-hour rupture strengths after the creep-optimised heat treatment (route A).

Typical values for the alloy, not guaranteed minima, and applicable to the route A condition. Rupture strength is sensitive to grain size, so it is also sensitive to solution temperature: this is exactly why route A uses the higher 1080 °C solution treatment. For design work, use the values in the governing specification or your own qualification testing.

How is Waspaloy heat treated?

Waspaloy is heat treated in a three-step sequence: solution treatment, stabilisation, then age hardening. Two standard routes exist, and choosing between them is the single most consequential material decision on the drawing, because they produce different grain sizes and therefore different property balances from identical chemistry.

Why the two routes differ

The higher solution temperature in route A dissolves more of the grain-boundary carbides and lets the grain grow. A coarse grain has less boundary area per unit volume, and grain boundaries are where creep damage nucleates, so coarse grain means longer rupture life. The 24-hour stabilisation then precipitates a controlled, discrete M₂₃C₆ carbide film on those boundaries, which resists sliding.

Route B keeps the solution temperature below the carbide solvus, so the grain stays fine and the oil quench freezes the structure. Fine grain gives higher yield strength (Hall–Petch), higher hardness and better low-cycle fatigue life, at the cost of creep life. The 4-hour stabilisation is enough for a fine-grained structure.

What are the physical properties of Waspaloy?

How hot can Waspaloy actually run?

Several different temperature limits get quoted for this alloy and they answer different questions. Mixing them up is the commonest error in alloy selection.

Oxidation performance is good in gas-turbine combustion atmospheres and in salt spray, and solution-treated material offers the best corrosion resistance of the various conditions. There is no benefit in running aged material hotter than its own ageing temperature of 760 °C for long periods: the γ′ will continue to coarsen in service and the strength you certified will not be the strength you have after a few thousand hours.

Waspaloy vs Inconel 718, Rene 41 and Haynes 282

Below 650 °C use alloy 718 because it is cheaper and far easier to buy, weld and machine; above 650 °C use Waspaloy because 718 is losing its strengthening phase. Rene 41 goes hotter and stronger still but is even harder to process; Haynes 282 was designed specifically to give Waspaloy-class strength with much better weldability and formability.

Chemistry ranges are nominal and given for orientation; work to the governing specification for each alloy. We forge all four. See Inconel 718, Rene 41 and the Haynes range.

How is Waspaloy forged and welded?

Hot working

Waspaloy is hot worked between about 980 °C and 1170 °C (1800–2140 °F). That window is narrow and both ends of it bite:

• Below 980 °C the alloy work hardens rapidly and cracking becomes likely. Load on the press climbs steeply and surface tearing follows.
• Above about 1180 °C (2150 °F) the alloy becomes hot short. With a melting range starting at 1330 °C, incipient melting at grain boundaries is the failure mode, and it is not repairable.

In practice this means frequent reheats, instrumented furnaces with a calibrated survey, controlled press speed rather than free hammer blows on finishing passes, and a written forge plan for each part. Aim for at least a 4:1 reduction from the remelt ingot or billet to break down the as-cast structure and develop grain flow along the principal stress direction. Cold working is possible by hydroforming, drawing, spinning, bending, roll forming and cold heading of annealed bar into fastener blanks, but intermediate annealing is normally required because the alloy work hardens very rapidly, and it is considerably stronger than the AISI 300 series stainless steels at room temperature to start with.

Welding

Waspaloy is not regarded as readily weldable outside carefully controlled circumstances. It can be fusion welded by argon-arc methods with a matched-composition filler; heavy sections, thin sheet and tube joints have all been made successfully with gas-shielded non-consumable arc welding. The restrictions are:

• Weld only material that is in the solution-treated condition. Welding aged material invites strain-age cracking as the γ′ re-precipitates during the thermal cycle.
• Re-solution treat every welded component before it enters service.
• High-temperature strength of a weld after heat treatment is lower than that of heat-treated wrought material, so place welds away from high-stress locations. The alloy may also display hot-short behaviour and sensitivity to strain cracking.

Where a design needs extensive welding at this strength level, Haynes 282 was created for exactly that reason and is usually the better answer.

Machining Waspaloy

Waspaloy is among the more difficult superalloys to machine. Several things work against you at once. It work hardens very rapidly, so any rubbing pass leaves a hardened skin that destroys the next one; thermal conductivity is low, so the heat of cutting stays in the tool edge instead of leaving in the chip; and the γ′ particles themselves are hard and abrasive.

That leads to a short set of shop rules:

• Machine in the solution-treated, air-cooled condition wherever the tolerance scheme allows. At 20–25 HRC the alloy is far more tractable than at 40 HRC.
• Use a rigid setup, minimum overhang, positive rake and a sharp edge. Flexibility in the setup shows up as chatter, and chatter in this alloy means a work-hardened surface.
• Low surface speed, generous feed, heavy flood coolant. Never let the tool dwell or exit under load.
• Take a constant depth of cut below the work-hardened layer from the previous pass rather than a series of light finishing passes.
• Expect grinding and creep-feed grinding to be used for finishing features that would be turned or milled in a steel.

The economic consequence matters at quotation stage: on Waspaloy the machining hours are often a larger part of the finished part cost than the metal, so near-net forging, and trepanning rather than boring from solid, are worth discussing before the drawing is frozen.

How do Waspaloy parts fail, and how do you prevent it?

What can Jiangyin Jiangnan Metal forge in Waspaloy?

UNS N07001 is a made-to-order grade for us: we buy the vacuum-melted heat against your specification rather than pulling from stock, so the drawing, the melt route and the required condition all matter at enquiry stage. The envelopes below are our tested limits for this alloy on our equipment, and they are tighter than our carbon-steel limits because a superalloy takes more press force per unit area and needs more reheats.

Rolled ring OD

200–2,500mm

Ring wall, minimum

30mm

Disc diameter

≤ 1,800mm

Shaft length

≤ 8,000mm

Bar diameter

25–500mm

Single piece

≤ 8,000kg

Melt routes

VIM/VARor VIM/ESR

Lead time

12–16weeks typical

Equipment used on this grade

Which standards, tests and certificates apply?

How do you specify a Waspaloy forging order?

1. Name the material generically. Write UNS N07001 plus the governing specification and revision. A purchase order that says only “Waspaloy” names a trademark; a purchase order that says only “AMS 5708” without a revision letter names a moving target.
2. State the melt route. VIM/VAR or VIM/ESR. Rotating aero-engine parts are normally VAR. This changes price and lead time more than any other single line on the order.
3. State the heat-treatment route in full. Not just “solution treated and aged” but the temperatures and hold times: for example, 1080 °C / 4 h / AC, 845 °C / 24 h / AC, 760 °C / 16 h / AC. Require the actual values on the certificate.
4. Say whether we ship solution treated or fully aged. If you are machining, you almost certainly want solution treated. These are different parts, different prices and different lead times.
5. Send the drawing with test direction, test location and grain flow. Above 50 mm section, state whether tensile tests are longitudinal or transverse and whether the coupon is prolongation or sacrificial.
6. Define NDE and the acceptance class. “UT per EN 10228-3, quality class 3” is a specification; “ultrasonic test” is not. Remember that magnetic particle inspection is not applicable to this alloy.
7. Choose the certificate, EN 10204 3.1 or 3.2 with a named witness, and state marking requirements.
8. Give quantity, date, Incoterm and destination. Quantity sets the melt strategy: below roughly 300 kg we consolidate onto a larger heat.

Drawing callout you can copy

MATERIAL:      UNS N07001 (Waspaloy class), AMS 5708 rev. ___
               ASTM B637 acceptable for non-aerospace work
MELT ROUTE:    VIM + VAR  (VIM + ESR acceptable / not acceptable)
CONDITION:     Solution treat 1080 deg C / 4 h / air cool  (20-25 HRC)
               Stabilise     845 deg C / 24 h / air cool
               Age           760 deg C / 16 h / air cool  (34-40 HRC)
               Record actual times and temperatures on the certificate
TENSILE:       1441 MPa UTS min, 1076 MPa YS min, 27% el., 47% RA
               Test direction: longitudinal / transverse (state one)
GRAIN SIZE:    ASTM E112, report actual; ___ or coarser
GRAIN FLOW:    Continuous, following the part contour; verify per ASTM E381
NDE:           UT per EN 10228-3 quality class 3 (or ASTM A388)
               PT per ASTM E165 Type I Method C
               MT NOT APPLICABLE - material is non-magnetic
CERTIFICATE:   EN 10204 3.1  (3.2 with third-party witness if stated on PO)
MARKING:       Heat number, condition, drawing number, low-stress stamped

Eight mistakes buyers make with Waspaloy

1. Quoting AMS 5544 on a forging. That specification covers sheet, strip and plate. For bars, forgings and rings use AMS 5704, 5706, 5707, 5708 or 5709, or ASTM B637.
2. Ordering “solution treated and aged” without naming the route. Route A and route B give different grain sizes and a materially different creep life from the same chemistry.
3. Applying a 4-hour stabilisation after the 1080 °C solution treatment. It has to be 24 hours.
4. Specifying magnetic particle inspection. Waspaloy is essentially non-magnetic at µ ≈ 1.004. Specify liquid penetrant instead.
5. Leaving the melt route unstated. A VAR heat and an ESR heat are different products at different prices, and an aero customer will reject the wrong one on paperwork alone.
6. Designing welded joints into highly stressed hot sections. Weld strength after heat treatment is below wrought strength, and the alloy is sensitive to strain-age cracking.
7. Using Waspaloy for wet-corrosion service. It is an oxidation-resistant high-temperature alloy, not a corrosion alloy. Hastelloy C-276, Alloy 59 or Inconel 625 are cheaper and better in acids.
8. Machining from solid instead of forging near-net. At this material price the cost of the metal turned into swarf normally exceeds the cost of the machining time.

Where is Waspaloy used?

Two worked examples

Example 1: choosing between route A and route B for a turbine disc

Given. A Ø700 mm industrial gas-turbine disc in UNS N07001, rim metal temperature 690 °C, design life 40,000 hours, rim stress about 200 MPa, bore stress about 550 MPa at the peak of the cycle with roughly 3,000 start-stop cycles.

Assessment. Two failure modes compete. At the rim, creep and rupture govern: interpolating Table 4 at 690 °C gives a 1,000-hour rupture strength near 490 MPa, so a 200 MPa rim stress leaves a comfortable margin even after extrapolating to 40,000 hours. At the bore, the temperature is much lower but the stress is high and cyclic, so low-cycle fatigue governs, and LCF life improves with a fine grain.

Decision. The rim is not the limiting location, so the coarse-grain creep advantage of route A is not being paid for; the bore is limiting, and route B’s finer grain buys LCF life directly. Specify route B, and if the design authority wants both, that means a dual-property disc, which needs a specialised local heat treatment and should be discussed before the forging drawing is issued rather than after.

Example 2: estimating the billet for a rolled ring

Given. A finished ring, OD 900 mm, ID 700 mm, height 180 mm, in UNS N07001.

Method. Ring volume = π/4 × (900² − 700²) × 180 = π/4 × 320,000 × 180 ≈ 45.2 × 10⁶ mm³ = 45,239 cm³. At 8.19 g/cm³ the net finished weight is about 370 kg. Adding 25% for machining stock on a ring of this size gives a rough forging near 463 kg, and allowing for the discard and test prolongations the billet is nearer 520–560 kg.

What that means commercially. The finished part is 370 kg but you are buying roughly 550 kg of vacuum-melted superalloy. The gap between those two numbers dominates the price far more than press time does. It is worth spending an hour on the forging drawing to see whether the bore can be trepanned rather than machined away, or whether the ring can be rolled closer to the finished contour.

Glossary

Waspaloy frequently asked questions

References

1. Special Metals Corporation, Waspaloy, technical bulletin SMC-011. Limiting chemical composition, physical constants, heat-treatment sequences, creep-rupture data, hot and cold working, joining.
2. SAE International, AMS 5704, AMS 5706, AMS 5707, AMS 5708, AMS 5709. Nickel alloy bars, forgings and rings, 58Ni-19.5Cr-13.5Co-4.3Mo-3.0Ti-1.4Al, in various heat-treated conditions.
3. SAE International, AMS 5544 for nickel alloy sheet, strip and plate; AMS 5828 for welding wire; MAM 5706, the metric annex.
4. 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.
5. ISO 9723, ISO 9724 and ISO 9725 for nickel and nickel alloy bars, wire and forgings.
6. UK Ministry of Defence, MSRR 7192.
7. ASM Handbook, Volume 1: Properties and Selection: Irons, Steels and High-Performance Alloys, ASM International. Section on nickel-base superalloys.
8. ASM Handbook, Volume 14A: Metalworking: Bulk Forming, ASM International. Section on forging of heat-resistant alloys.
9. ASTM A388/A388M, Standard Practice for Ultrasonic Examination of Steel Forgings; EN 10228-3, ultrasonic testing of forgings; SEP 1921.
10. ASTM E165 / ISO 3452 liquid penetrant examination; ASTM E8/E8M tensile testing; ASTM E21 elevated-temperature tension testing; ASTM E139 creep and stress-rupture testing; ASTM E112 grain size; ASTM E381 macroetch.
11. EN 10204, Metallic products: Types of inspection documents, CEN.

Standards are cited by number; always work to the revision in force at your contract date. Property values on this page are published typical or limiting values for the alloy and are given for engineering orientation, not as design allowables. Test results on our certificates are independent and traceable to calibrated equipment.

About the manufacturer, and how to cite this page

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, operating since 2008 with 460 employees including 9 senior engineers and 32 intermediate engineers. The plant runs 1 t to 9 t open-die hammers, 4,500 t and 5,000 t hydraulic presses and radial-axial ring mills up to 2,500 mm outside diameter, with in-house heat treatment, machining, mechanical testing and non-destructive examination. Alongside Waspaloy / UNS N07001 we forge carbon, alloy and tool steels, the precipitation-hardening and duplex stainless families, and the full range of nickel and cobalt superalloys. Quality management is certified to ISO 9001:2015 and material is supplied with EN 10204 3.1 certification as standard, 3.2 with third-party witness on request.

Related grades and products we forge

• Inconel 718
• Rene 41
• Inconel X-750
• Incoloy 901
• Haynes 230
• Haynes 188
• Haynes 25
• Hastelloy X
• MP159
• MP35N
• Multimet N155
• All nickel alloys
• Forged rings
• Forged discs
• Forged sleeves
• Forged spindles
• Open-die forgings