High-Temperature Alloys / Superalloys
GH4090 (Nimonic 90) (UNS N07090) — Composition, Properties & Supply
GH4090 is a Ni-Cr-Co precipitation-hardening superalloy (equivalent to British Nimonic 90). It offers high tensile and creep resistance at 815–870 °C with good oxidation and corrosion resistance and high fatigue strength under thermal cycling, for turbine blades, discs, high-temperature fasteners and springs.
What is the chemical composition of GH4090 (Nimonic 90)?
| Element | Symbol | Content (wt%) |
|---|---|---|
| Ni | Ni | Balance |
| Cr | Cr | 18.0–21.0 |
| Co | Co | 15.0–21.0 |
| Ti | Ti | 2.0–3.0 |
| Al | Al | 1.0–2.0 |
| Fe | Fe | ≤ 1.5 |
| C | C | ≤ 0.13 |
| Si | Si | ≤ 1.0 |
| Mn | Mn | ≤ 1.0 |
Values are typical specification limits. Actual heat analysis is reported on the EN 10204 3.1 mill test certificate supplied with each shipment.
What are the mechanical properties of GH4090 (Nimonic 90)?
| Property | Value | Note |
|---|---|---|
| Tensile strength | ≥ 1080 MPa | Room temperature |
| Yield strength (0.2% offset) | ≥ 690 MPa | Room temperature |
| Elongation | ≥ 15 % | Gauge length 50 mm / 4D |
| Hardness | 28–35 HRC | Brinell / Rockwell |
What are the physical properties of GH4090 (Nimonic 90)?
| Property | Value |
|---|---|
| Density | 8.18 g/cm³ |
| Melting range | 1310–1370 °C |
| Thermal conductivity | 11.5 W/m·K |
| Elastic modulus | 210 GPa |
| Maximum service temperature | 920 °C |
What are the key characteristics of GH4090 (Nimonic 90)?
- High strength and creep resistance at 815–870 °C
- γ′ (Ni₃(Al,Ti)) precipitation strengthening
- High fatigue strength under thermal cycling
- Good formability and weldability
Where is GH4090 (Nimonic 90) used?
- Gas turbine blades and discs
- High-temperature fasteners, clamps and seals
- Exhaust valves and springs
- Compressor and hot-section load-bearing parts
Which standards and specifications cover GH4090 (Nimonic 90)?
- GB/T 14992
- ASTM B637
- AMS 5829
- GB/T 14994
Which standard covers GH4090 cold drawn bar?
GH4090 cold drawn bar is specified under GB/T 14994 — 高温合金冷拉棒材, published in English as Superalloy cold drawn bars. The 2008 edition replaced GB/T 14994-1994 and was the revision that added four grades to the standard: GH4080A, GH4090, GH4169 and GH2696. GH4090 therefore sits explicitly inside its scope rather than being covered by implication.
The standard sets the dimensions, shape and permitted deviations, the technical requirements, test methods and inspection rules, and the packing, marking and quality-documentation requirements. Its stated scope is cold drawn superalloy bar for parts such as industrial fasteners, and it covers round, square and hexagonal sections.
Cold drawing is chosen when the part needs a clean surface, close dimensional tolerance and the extra room-temperature strength that work hardening gives before ageing — fasteners, springs, valve stems and small shafts. Where the duty is creep-limited rotating service such as turbine discs and blades, buyers order hot-rolled and forged bar instead. That is a different standard, and the two are not interchangeable on a purchase order.
| Product form | Standard | What it governs |
|---|---|---|
| Grade designation and composition limits | GB/T 14992 | Establishes the GH4090 designation and its chemical composition range |
| Cold drawn bar | GB/T 14994 | Dimensions, tolerances, technical requirements and delivery condition |
| Hot-rolled and forged bar | GB/T 14993 | Bar for rotating parts, with creep and stress-rupture requirements |
| Hot-rolled plate | GB/T 14995 | Hot-rolled plate dimensions and technical requirements |
| Cold-rolled sheet and strip | GB/T 14996 | Cold-rolled sheet and strip dimensions and finish |
| Nickel alloy bar and forgings, ASTM route | ASTM B637 | Precipitation-hardening nickel alloy bar, forgings and forging stock |
| Attribute | Cold drawn bar | Hot-rolled / forged bar |
|---|---|---|
| Governing GB standard | GB/T 14994 | GB/T 14993 |
| Typical parts | Fasteners, springs, valve stems, small shafts | Turbine discs, blades, rotating components |
| What the order hinges on | Dimensional accuracy and surface finish | Creep, stress-rupture and ultrasonic inspection |
| Condition on delivery | Solution treated, cold drawn and pickled | Hot worked and solution treated; aged by agreement |
Ageing is not automatic. GH4090 develops its specified strength through gamma-prime precipitation, so when the application needs the aged condition it has to be stated on the order: solution treat at about 1080 °C, then age at 700–720 °C for 16 h and air cool.
What product forms are available?
Frequently asked questions
What is the typical heat treatment for GH4090?
Solution treatment at about 1080 °C for 8 h followed by air/oil cooling, then ageing at 700–720 °C for 16 h and air cooling.
Which standard covers GH4090 cold drawn bar?
GB/T 14994-2008, 高温合金冷拉棒材, published in English as Superalloy cold drawn bars. It replaced GB/T 14994-1994 and was the revision that added four grades: GH4080A, GH4090, GH4169 and GH2696. It governs dimensions, shape and permitted deviations, technical requirements, test methods and inspection rules for cold drawn superalloy bar.
Is cold drawn GH4090 bar acceptable for turbine discs?
No. GB/T 14994 covers cold drawn bar for fasteners and similar parts, not rotating components. Turbine discs and blades are ordered as hot-rolled or forged bar under the rotating-part bar standard, where creep, stress-rupture and ultrasonic inspection requirements apply. The two are separate purchase specifications.
What condition does GH4090 cold drawn bar arrive in?
Solution treated, cold drawn and pickled. The ageing treatment that develops GH4090's gamma-prime strength is applied afterwards, so the aged condition has to be written into the order: 700–720 °C for 16 h, air cool, after solution treatment at about 1080 °C.
Need GH4090 (Nimonic 90) bar, tube, plate or forgings?
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