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Material Classification: Wrought Nickel-Based Superalloy, Solid-Solution Strengthened
Chinese Grade: GH3128
Density: Approximately 8.81 g/cm³
Melting Range: Approximately 1,340–1,390°C
Typical High-Temperature Application: Combustion chamber components operating at temperatures up to approximately 950°C, subject to service conditions and engineering requirements
GH3128 is a wrought nickel-based superalloy strengthened primarily by solid-solution mechanisms. Its principal alloying elements include chromium (Cr), tungsten (W), and molybdenum (Mo), while controlled additions of aluminum (Al) and titanium (Ti), together with trace elements such as boron (B), cerium (Ce), and zirconium (Zr), contribute to its overall mechanical and environmental performance.
With its combination of high-temperature strength, creep resistance, oxidation resistance, ductility, and favorable fabrication characteristics, GH3128 is used in selected aerospace and industrial components exposed to elevated temperatures. Typical applications include combustion chamber flame holders and liners, afterburner casings, adjustment flaps, diffusers, stabilizers, and other hot-section structural components.
GH3128 is particularly relevant where components require a balance of elevated-temperature performance, sheet-metal formability, and weldability. However, its suitability for a specific application depends on temperature, applied stress, service duration, operating atmosphere, component geometry, and the applicable product specification.
This guide reviews GH3128 chemical composition, physical and mechanical properties, heat treatment, fabrication considerations, applications, standards, and procurement requirements.
GH3128 is classified as a wrought high-temperature alloy under China's GH designation system. It is a nickel-based, solid-solution-strengthened alloy rather than a conventional precipitation-hardened superalloy whose primary strengthening mechanism depends on a controlled γ′ or γ″ precipitation-hardening treatment.
Tungsten and molybdenum are the principal solid-solution-strengthening elements in GH3128. Their combined concentration is typically 15–18 wt.%, producing substantial lattice distortion in the nickel-rich matrix and increasing resistance to dislocation motion at elevated temperatures.
Chromium contributes to oxidation resistance by supporting the formation of a protective chromium-rich oxide scale under suitable oxidizing conditions. Aluminum and titanium are additional alloying constituents that influence the alloy's metallurgical behavior and high-temperature properties.
Trace additions of boron, cerium, and zirconium can influence grain-boundary cohesion, oxidation behavior, and microstructural stability. Their effects depend on concentration, processing history, grain structure, and service exposure.
GH3128 is generally selected for applications requiring a combination of:
● High-temperature strength: Suitable for specified structural applications at elevated temperatures.
● Creep and stress-rupture resistance: Offers resistance to time-dependent deformation under appropriate temperature and stress conditions.
● Oxidation resistance: Chromium-rich chemistry supports resistance to oxidation in suitable high-temperature environments.
● Ductility and formability: Suitable for forming operations used to manufacture selected sheet-metal components.
● Weldability: Can be used in welded structures when welding procedures and fabrication controls are appropriate.
These characteristics make GH3128 useful for selected combustion chamber and afterburner components. They should not be interpreted as guarantees of performance under every temperature, load, atmosphere, or service-life requirement.
GH3128 is sometimes compared with other nickel-based solid-solution-strengthened alloys, including GH3044 and GH3536. Such comparisons should be based on the relevant product form, temperature, mechanical property, oxidation environment, fabrication requirements, and applicable specification.
GH3128's relatively high combined tungsten and molybdenum content supports solid-solution strengthening. However, a higher concentration of particular alloying elements does not, by itself, establish superior overall performance. Material selection should be based on verified property data and application-specific design criteria.
GH3128 is primarily identified by its Chinese grade designation. It should not be assigned a direct Western equivalent solely on the basis of similar chemical composition or application.
When international sourcing or substitution is required, verify the material's chemical composition, product form, heat treatment, mechanical properties, inspection requirements, and governing specification before approving an alternative.
The following table summarizes commonly published composition limits for GH3128 associated with GB/T 14992. The applicable standard edition and product specification must be confirmed before these values are used for contractual acceptance.
Element | Symbol | Typical specification range or limit (wt.%) |
Nickel | Ni | Balance |
Chromium | Cr | 19.0–22.0 |
Tungsten | W | 7.5–9.0 |
Molybdenum | Mo | 7.5–9.0 |
Aluminum | Al | 0.4–0.8 |
Titanium | Ti | 0.4–0.8 |
Iron | Fe | ≤ 2.0 |
Carbon | C | ≤ 0.05 |
Silicon | Si | ≤ 0.8 |
Manganese | Mn | ≤ 0.5 |
Phosphorus | P | ≤ 0.013 |
Sulfur | S | ≤ 0.013 |
Boron | B | ≤ 0.005 |
Cerium | Ce | ≤ 0.05 |
Zirconium | Zr | ≤ 0.06 |
Copper | Cu | Verify against the applicable edition and product specification |
Important: The table is a reference summary, not a substitute for the governing standard or a certified material test report. Confirm all specified elements, including any elements omitted from a particular summary table, against the exact standard edition and purchasing requirements.
Nickel (Ni): Forms the principal matrix and contributes to the alloy's high-temperature structural stability.
Chromium (Cr): Supports oxidation resistance by promoting a protective oxide scale in suitable environments.
Tungsten (W) and molybdenum (Mo): Provide the principal solid-solution-strengthening contribution and improve resistance to deformation at elevated temperatures.
Aluminum (Al) and titanium (Ti): Influence alloy metallurgy and mechanical behavior. Their presence does not, by itself, mean that GH3128 should be classified as a conventional precipitation-hardened alloy.
Boron (B), cerium (Ce), and zirconium (Zr): Used in controlled amounts to influence grain-boundary behavior and high-temperature performance.
The alloy's performance depends on the combined effect of composition, melting and processing routes, grain structure, heat treatment, and service exposure. Chemical composition alone is insufficient to predict component life.
GH3128 has a nickel-rich face-centered cubic (FCC) matrix. Its substantial tungsten and molybdenum contents contribute to its relatively high density compared with many lighter structural alloys.
Property | Reference value | Notes |
Density | Approximately 8.81 g/cm³ | Confirm for the specified product and reference source |
Melting range | Approximately 1,340–1,390°C | Reference range; not a recommended operating-temperature range |
Crystal structure | FCC matrix | Nickel-rich austenitic matrix |
Typical high-temperature application | Up to approximately 950°C | Depends on stress, exposure time, atmosphere, and component design |
The melting range must not be used as a measure of allowable service temperature. A component can experience unacceptable creep deformation, oxidation, or loss of structural integrity at temperatures far below the alloy's melting range.
Likewise, approximately 950°C should be treated as a representative application temperature cited for certain GH3128 components, not a universal design limit for all geometries and loading conditions.
GH3128 mechanical properties vary with product form, thickness, manufacturing route, delivery condition, heat treatment, test temperature, and specimen orientation.
The following values are commonly published reference requirements for specified sheet products and test conditions. They should not be applied automatically to bars, forgings, tubes, or other product forms.
Product form | Condition and test temperature | Tensile strength, Rm | Elongation, A |
Hot-rolled plate or cold-rolled sheet | Specified delivery condition, room temperature | ≥ 735 MPa | ≥ 40% |
Hot-rolled plate or cold-rolled sheet | Specified delivery condition followed by the prescribed solution treatment, tested at 950°C | ≥ 175 MPa | ≥ 40% |
Technical qualification: The second row represents a specified test condition, not an assertion that every GH3128 product automatically achieves these values after any treatment described as “solution annealing.” The applicable product standard, specimen preparation, heat-treatment procedure, and acceptance criteria must be checked before the values are used in design or purchasing.
Creep is the time-dependent deformation of a material under sustained stress, particularly at elevated temperatures. Stress-rupture testing evaluates the time required for a specimen to fail under specified temperature and stress conditions.
For GH3128 components operating near 950°C, creep and stress-rupture data are important when establishing allowable stress, expected service life, and inspection intervals. The design should use data appropriate to the relevant product form, heat treatment, stress level, temperature, and required duration.
Tensile strength at a single test temperature is not a substitute for long-term creep or stress-rupture data. Where service life is critical, obtain the applicable test results or design allowables and assess the effects of thermal cycling, welds, local stress concentrations, and the operating atmosphere.
Heat treatment should be selected according to the governing product specification, product geometry, thickness, manufacturing history, and required final properties. The temperatures below are reference ranges reported for GH3128 products; they are not interchangeable procedures for every product form.
For cold-rolled or hot-rolled sheet products, a solution-treatment range of approximately 1,140–1,180°C followed by air cooling is commonly cited.
For certain thicker plate products, higher solution-treatment temperatures around 1,190–1,210°C may be specified. The actual temperature, holding time, cooling method, and acceptance requirements must follow the applicable product specification and approved processing procedure.
Holding time should account for thickness, furnace uniformity, component geometry, and the required metallurgical condition. Excessive exposure can be detrimental, so the highest temperature or longest holding time should not be selected without technical justification.
Bars, forgings, billets, and other forms may require different processing schedules from thin sheet products. Do not apply a sheet-treatment schedule to a forging or billet without confirming its suitability.
For these product forms, the recommended procedure should be established from the relevant standard, supplier documentation, and, where necessary, process qualification. Any requirements for subsequent aging, stabilization, stress relief, or other treatment must be explicitly verified rather than assumed.
GH3128 can be used in fabricated and welded high-temperature structures when appropriate materials, joint designs, welding procedures, and quality controls are applied.
Key considerations include:
● Confirming the compatibility of the filler metal with the base alloy and service environment.
● Controlling heat input, interpass temperature, joint preparation, and distortion.
● Assessing the effects of welding and subsequent thermal exposure on strength and ductility.
● Applying the inspection and qualification requirements specified for the component.
● Evaluating welded regions separately where creep, thermal fatigue, or long-term service life is critical.
Weldability should not be interpreted as evidence that every welding process or filler metal is suitable. Procedure qualification and application-specific verification remain necessary.
GH3128 has useful oxidation resistance in suitable high-temperature environments. However, oxidation performance depends on temperature, gas chemistry, exposure duration, thermal cycling, and surface condition.
The use of a coating, including an enamel coating such as W-2, should be determined by the component specification and validated operating conditions. Such coatings should not be presented as universally required or universally compatible with GH3128 without supporting process documentation and application-specific qualification.
GH3128 is used in selected high-temperature components where a combination of strength, ductility, oxidation resistance, and fabrication performance is required.
Typical applications include:
● Combustion chambers: Flame tubes, liners, diffusers, and stabilizing components.
● Afterburner assemblies: Selected casings, adjustment flaps, and related structural components.
● Exhaust systems: Gas ducts, nozzle-related components, and other parts where the specified service conditions are compatible with the alloy.
● Hot-section sheet structures: Formed and welded components requiring a balance of elevated-temperature properties and manufacturability.
Suitability for each component depends on the actual temperature distribution, mechanical loading, oxidation environment, fatigue duty, and service-life requirements.
GH3128 may also be considered for selected applications such as:
● Thermocouple protection: Protective sheaths or related components, where chemical compatibility and temperature requirements are satisfied.
● Magnetic instrumentation: Structural frames or probe components where the required mechanical and magnetic characteristics have been verified.
● Metallurgical processing: Selected fixtures or components used in high-temperature processing environments.
● Industrial combustion systems: Structural components exposed to hot oxidizing gases, provided the operating conditions fall within the qualified application range.
These are application examples rather than universal approvals. For equipment exposed to reducing atmospheres, molten materials, aggressive process gases, or prolonged high-temperature loading, compatibility should be confirmed through test data or relevant service experience.
GB/T 14992 is an important reference for Chinese superalloy designations and chemical composition. It should not be treated as the sole governing document for every GH3128 product.
Depending on the product form and intended application, the purchasing specification may also need to identify the applicable standards for hot-rolled plate, cold-rolled sheet, aerospace sheet products, welding wire, bars, or other forms.
Before procurement, confirm:
1. The applicable standard number and edition.
2. The exact GH3128 designation and product form.
3. Dimensions, thickness tolerances, and delivery condition.
4. Chemical composition limits and required analytical methods.
5. Room-temperature and, where required, elevated-temperature mechanical properties.
6. Heat-treatment requirements and any additional testing.
7. Surface quality, nondestructive examination, traceability, and documentation requirements.
Standards and revisions should be checked against the current official publication and the contractual requirements. A supplier's general product page is not a substitute for the applicable standard.
GH3128 is commonly associated with the following product forms, subject to mill capability and applicable product specifications:
● Cold-rolled sheet and strip
● Hot-rolled plate
● Bar and rod
● Forgings and billets
● Wire
● Tubes, where available under the relevant manufacturing and acceptance requirements
Availability should be confirmed for the required dimensions, condition, tolerances, quantity, and inspection level.
Shanghai Bozhong Metal Group can present its GH3128 supply capability in terms of the specific products and services confirmed by its current inventory and quality documentation.
Potential procurement support includes:
● Product selection: Assistance in identifying suitable product forms and dimensions.
● Cutting and customization: Cut-to-length or other processing services, subject to equipment capability and order requirements.
● Quality documentation: Material test certificates and traceability documentation, as agreed in the purchase contract.
● Inspection support: Spectrometric or other material verification when available and specified.
● Technical consultation: Assistance with material selection, processing requirements, and documentation review.
Supplier note: Statements about stock availability, original-equipment-manufacturer sourcing, inspection capability, and certification should be published only after they have been confirmed internally. For critical applications, specify the required certificate type, inspection method, and acceptance criteria in the purchase order.
Identify whether the requirement is for cold-rolled sheet, hot-rolled plate, bar, forging, wire, or tube. Include dimensions, tolerances, delivery condition, heat-treatment requirements, and applicable standard edition.
Do not rely on the grade designation alone to define the complete technical requirement.
Review the material test report against the governing standard and purchase specification. Pay particular attention to chromium, tungsten, molybdenum, aluminum, titanium, and the specified limits for trace and impurity elements.
The combined W and Mo content is a major feature of GH3128's solid-solution-strengthening design. Nevertheless, chemical analysis should be assessed as a complete specification rather than by checking only two elements.
Thin sheets, thicker plates, bars, and forgings may require different treatment schedules. Confirm the solution-treatment temperature, holding time, cooling method, and final condition for the specific product before processing.
Record any purchaser-required post-delivery treatment and ensure that the resulting condition meets the required acceptance criteria.
For components intended for prolonged service near 950°C, review creep and stress-rupture data, oxidation behavior, thermal fatigue, weld performance, and microstructural stability.
Potential phase precipitation or microstructural changes during long-term exposure should be evaluated using alloy-specific evidence. Do not assume a particular phase-related failure mechanism without supporting metallographic or service data.
For critical components, define the required material certificate, heat or lot traceability, dimensional inspection, surface examination, chemical analysis, mechanical testing, and any additional nondestructive testing.
Acceptance criteria should be agreed before production or shipment rather than inferred from general-purpose datasheets.
GH3128 is a wrought nickel-based, solid-solution-strengthened high-temperature alloy. Tungsten and molybdenum are its principal solid-solution-strengthening additions.
A commonly reported reference density is approximately 8.81 g/cm³. Confirm the value against the applicable technical documentation when accurate mass calculations are required.
GH3128 is used in certain applications operating at temperatures up to approximately 950°C. Actual suitability depends on applied stress, exposure time, atmosphere, component geometry, thermal cycling, and the applicable design criteria.
GH3128 is generally classified as a solid-solution-strengthened alloy. Its principal strengthening mechanism should not be confused with the conventional precipitation-hardening mechanisms of alloys such as GH4169.
Typical applications include selected aerospace combustion chamber components, afterburner structures, flame tubes, diffusers, adjustment flaps, and other high-temperature fabricated components. Industrial applications require separate compatibility verification.
There is no direct, universally accepted Western equivalent that should be assumed interchangeable without qualification. Any proposed substitute must be evaluated against chemical composition, mechanical properties, product form, heat treatment, applicable standards, and service requirements.
At a minimum, specify the grade, product form, dimensions, quantity, applicable standard and edition, delivery condition, inspection and testing requirements, material certificate requirements, and any special processing or traceability conditions.
GH3128 is a nickel-based solid-solution-strengthened superalloy developed for demanding elevated-temperature applications. Its combination of tungsten- and molybdenum-based solid-solution strengthening, chromium-assisted oxidation resistance, ductility, and fabrication characteristics makes it a relevant material for selected aerospace and industrial hot-section components.
For reliable engineering selection and procurement, the material grade should be considered together with product form, heat treatment, mechanical test requirements, service environment, and long-term performance criteria. Verifying the governing standard and material test certificate is essential to ensuring that the supplied product meets the intended application requirements.
