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Views: 0 Author: Site Editor Publish Time: 2026-10-10 Origin: Site
Designation: GH4049 (wrought superalloy, nickel-based, precipitation-hardened)
International equivalent: No widely used corresponding Western grade; formerly known as GH49, supplied domestically in China
Density: ~8.44 g/cm³ | Service temperature: below 950°C | Magnetism: non-magnetic
One-line summary: A 950°C-class high-temperature blade alloy “fed” into being through a duplex (two-stage) melting process
GH4049 (formerly GH49) is a homegrown Chinese precipitation-hardening, nickel-based wrought superalloy containing roughly 70% nickel. Through γ′-phase precipitation combined with solid-solution strengthening from tungsten, molybdenum, and cobalt, it can operate long-term at temperatures below 950°C.
Its historical role is clear: without any directly imported corresponding Western commercial grade, it provides China’s aero engines with a turbine-blade and disc material capable of long-term operation at the 950°C class, with low notch sensitivity and respectable oxidation resistance and fatigue strength.
But it has an unavoidable “character flaw” — poor hot-working ductility, making ingot cogging (breakdown forging) very difficult. An ordinary as-cast ingot cracks as soon as you forge it, so it must go through a duplex process of vacuum induction melting + vacuum arc remelting (or electroslag remelting). Only by first cleaning out internal porosity, segregation, and gaseous impurities in the ingot can it be successfully broken down and deformed. This is both the reason its cost stays high and the barrier that sets it apart from “run-of-the-mill” superalloys.
It remains mainstream because, in the 950°C temperature band, there simply aren’t many wrought alloys that can simultaneously deliver high strength, low notch sensitivity, and oxidation resistance.
GH4049’s composition follows a classic “highly alloyed” route — 70% nickel, with nearly everything else being strengthening elements:
Element | Content | Role |
Ni | Balance (~70%) | Matrix, and the main constituent of the γ′ phase Ni₃(Al,Ti) |
Cr | 9.5–11.0% | Oxidation resistance, forming a Cr₂O₃ film; content kept low to make room for strengthening elements |
Co | 14.0–15.5% | High cobalt. Raises the γ′-phase solvus temperature and high-temperature microstructural stability; strengthens high-temperature creep resistance |
W | 5.0–6.0% | Solid-solution strengthening; improves high-temperature stress-rupture (creep) strength |
Mo | 4.5–5.5% | Solid-solution strengthening; teamed with tungsten to improve creep resistance |
Al | 3.7–4.4% | Main γ′-phase element. Al + Ti form Ni₃(Al,Ti), providing the primary precipitation strengthening |
Ti | 1.4–1.9% | Participates in γ′-phase formation, increasing the amount of strengthening phase |
C | 0.04–0.10% | Forms carbides that pin grain boundaries |
B | ≤0.015% | Trace grain-boundary strengthening; improves grain-boundary strength and ductility |
Key point: Al is as high as 3.7–4.4%, stacked with 14–15.5% cobalt, 5–6% tungsten, and 4.5–5.5% molybdenum — this is high-temperature strength built by “loading up” on alloying. The price is a large alloy content, costly cobalt, and a narrow hot-working window. So it is inherently an expensive alloy that must be duplex-melted.
GH4049’s strength comes from two superimposed mechanisms:
γ′-phase precipitation strengthening (main contributor): Al, Ti, and Ni form the Ni₃(Al, Ti) intermetallic compound, which precipitates finely from the matrix during aging. This phase is coherent with the matrix and blocks dislocations extremely effectively — the primary source of high-temperature strength. GH4049’s Al content is on the high side within its class, meaning a large γ′-phase volume fraction and high high-temperature strength.
W / Mo / Co solid-solution strengthening (auxiliary): Tungsten and molybdenum atoms dissolve into the matrix, causing lattice distortion; cobalt improves the high-temperature stability of the γ′ phase itself, inhibiting its coarsening or re-dissolution in service. Together, these push stress-rupture strength all the way up to 950°C.
Grain-boundary effect of B: Trace boron segregates at grain boundaries, improving grain-boundary cohesion. This is the microstructural reason for its “low notch sensitivity” — blade serrations (fir-tree roots) and threads are exactly where grain boundaries are most prone to cracking first.
Its weakness also lies at the microstructural level: the more and larger the γ′ phase, the greater the deformation resistance and the poorer the ductility during hot working. This is why an ingot simply cannot be forged unless duplex refining first improves its cogging behavior.
Chemical composition (typical values; refer to the material certificate):
Element | Content (%) | Element | Content (%) |
C | 0.04–0.10 | Ni | Balance (~70%) |
Cr | 9.5–11.0 | Co | 14.0–15.5 |
W | 5.0–6.0 | Mo | 4.5–5.5 |
Al | 3.7–4.4 | Ti | 1.4–1.9 |
B | ≤0.015 | — | — |
Physical properties:
Property | Value |
Density | ~8.44 g/cm³ |
Magnetism | Non-magnetic |
Mechanical properties (typical values; refer to the material certificate):
Condition | Temperature | Tensile strength σb | Yield strength σ0.2 | Elongation δ |
Standard heat treatment | 20°C | ≥1000 MPa | ≥700 MPa | ≥8% |
Standard heat treatment | 900°C | ≥600 MPa | — | ≥8% |
Interpretation: Room-temperature tensile strength ≥1000 MPa and yield strength ≥700 MPa are already strong; more importantly, tensile strength is still ≥600 MPa at the high temperature of 900°C — that is the confidence behind the “950°C class” claim. The elongation of only 8% shows it is a high-strength, low-ductility “hard” material, so both machining and material selection must treat it accordingly.
Grade | Service temp. | Strength | Weldability | Cost | Best suited for |
GH4049 | ≤950°C | Very high | Poor | Very high | 950°C-class blades, discs |
GH4080A | ≤815°C | High | Fair | High | Conventional-temperature blades |
GH4099 | ≤900°C | High | Good | Mid-high | Load-bearing welded combustion-chamber parts |
GH4738 | ≤815°C | Very high | Poor | Very high | Turbine discs, blades (rotating parts) |
GH4141 | ≤950°C | Very high | Fair | High | Medium-temperature, high-strength shafts, discs |
In one line: GH4049 is the domestic “loaded-up” contender in the 950°C band — strength is there, but it’s hard to hot-work and expensive due to cobalt. If the temperature requirement isn’t that high, down-shift to GH4080A to save money; for turbine-disc-level fatigue stability, look at GH4738.
Gas-turbine turbine blades, guide vanes, turbine discs, high-pressure compressor discs: 950°C class, low notch sensitivity, good fatigue strength — a perfect match for blade serrations and disc webs, areas that are “both hot and subject to stress concentration.”
Combustion chambers for aviation, marine and industrial gas turbines: high-temperature load-bearing hot-section components.
Aerospace vehicles, rocket engines, nuclear reactors, coal-conversion and other energy-conversion equipment: these scenarios either involve extremely high temperatures or long continuous operation from a single start-up, imposing demanding requirements on microstructural stability and high-temperature strength.
Why must it be GH4049? Because these parts share the common trait of “reaching temperatures above 900°C while bearing load and resisting notch fatigue.” Ordinary 700–800°C-class blade alloys lose strength too fast at these temperatures, whereas GH4049’s high γ′ volume fraction plus high-cobalt solid solution push its strength right into this range.
Q: Why must GH4049 be purchased as duplex-melted material?
A: Because its hot-working ductility is extremely poor — an ordinary ingot will inevitably crack during cogging. Vacuum induction + vacuum arc remelting (or electroslag remelting) eliminates porosity and segregation and improves breakdown behavior. When procuring important blades and discs, the melting process must be explicitly specified in the contract.
Q: In what condition does it arrive? Can it go straight onto the machine?
A: It is delivered in the solution-treated + aged condition. All its strength comes from the γ′ precipitated during aging; the solution-treated state is soft and cannot directly carry high-temperature loads. On receipt, check the heat-treatment schedule on the material certificate — don’t mistake solution-treated material for aged material.
Q: Are GH4049 and GH49 the same thing?
A: Yes. GH49 is the old designation; GH4049 is the new number under the GB/T 14992 system. They refer to the same alloy, and you may encounter either name when purchasing.
Q: Why is it considerably more expensive than GH4080A?
A: It contains 14–15.5% cobalt, and cobalt is pricey; high Al means abundant γ′ and difficult machining; and it must be duplex-melted. With both material and process costs, the high price is structural.
Q: Can it still be pushed beyond 950°C?
A: Not recommended. 950°C is already its long-term service ceiling. Above this temperature, the γ′ phase coarsens rapidly, oxidation-resistance margin is exhausted, and strength drops off a cliff. For higher temperatures, choose a different alloy.
Bozhong Alloy stock: GH4049 plates, bars, tubes, strips, wires, and forgings are regularly kept in stock. Dual supply chains — direct supply from domestic steel mills + imported original material. Warehouses in Shanghai and Wuxi; standard specifications ship within 24–72 hours. Every batch comes with a material certificate and is available for spectrographic re-inspection. Cutting-to-size and small batches are supported.
