In high-performance propulsion systems, one of the most frequently asked questions is: "GH4169 has such high strength, can I use it for high-temperature turbine impellers?"
GH4169 (equivalent to Inconel 718) is a forged alloy. While ideal for forged shafts, it rapidly undergoes "overaging" and softening at extreme temperatures.
K418 (equivalent to Inconel 713C) is a cast alloy. It is designed to maintain structural integrity at temperatures between 900°C and 980°C, at which point forged alloys would sag and deform like wax.
Choosing between GH4169 and K418 hinges on the trade-off between forged ductility and cast thermal stability. At Gnee Alloy, we help you select the right metallurgical engine for your industrial durability needs.
GH4169 and Inconel 713C (K418): A Sourcing Guide for Forging Alloys
Gnee Alloy
GH4169 and Inconel 713C (K418): A Sourcing Guide for Forging Alloys
GH4169 (equivalent to Inconel 718) and Inconel 713C (commonly known as K418 in China) are two nickel-based superalloys that are important materials for high-temperature applications. Although both are precipitation-strengthened alloys, their main manufacturing processes-forging and casting-determine different procurement strategies.
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What is the maximum operating temperature of Inconel 718?
-423°F to 1300°F.
INCONEL Alloy 718 (UNS N07718/W.Nr. 2.4668) is a high-strength, corrosion-resistant nickel-chromium alloy with an operating temperature range of -423°F to 1300°F.
1. Overview and Comparison of GH4169 and Inconel 713C Alloys
GH4169 / Inconel 718 (Forging Only): A niobium-strengthened alloy (Ni-Cr-Fe-Nb-Mo) with excellent notch sensitivity, weldability, and forgeability. It is the material of choice for structural components requiring strength up to 650°C.
Inconel 713C / K418 (Casting Only): An aluminum-titanium-strengthened alloy (Ni-Cr-Al-Mo) with excellent creep resistance at higher temperatures (>700°C).
Key Difference: GH4169 is a forging alloy; Inconel 713C/K418 is a casting alloy. The forging difficulty of 713C is well-known due to its high aluminum and titanium content.
High-Temperature Performance Characteristics and Applications of GH4169 and Inconel 713C
GH4169 (<700°C) Environmental Performance
GH4169 is a precipitation-hardening forging alloy. Its strength comes from the γ′′ (γ′) phase. It is suitable for high-precision forming processes such as push-pull forging.
Key Advantages: Excellent yield strength (≥1030 MPa) and exceptionally long fatigue life.
Limitations: Above 750°C, the γ′′ phase dissolves, causing the alloy to soften rapidly.
Optimal Applications: Forging engine shafts, turbine disks, structural rings, and high-strength fasteners.
K418 (>900°C) Environmental Performance
K418 is an aluminum-rich precipitation-hardening casting alloy. It relies on a high volume fraction (approximately 60%) of the γ′ (γ') phase, which exhibits thermal stability at temperatures close to its melting point.
Key Advantages: Excellent creep rupture strength at 900°C (1652°F).
Limitations: It is a "master alloy" used for casting; it cannot be forged and is extremely difficult to machine.
Optimal Applications: Precision casting of turbine impellers, nozzle guide vanes, turbocharger rotors, and hot-end components of drone engines.
4. Comparison of chemical composition of GH4169 and Inconel 713C (wt%)
| Element | GH4169 (Inconel 718) | Inconel 713C | Key Difference |
|---|---|---|---|
| Nickel (Ni) | 50.0 – 55.0 | Balance (~70-75) | 713C has higher Ni |
| Chromium (Cr) | 17.0 – 21.0 | 11.0 – 14.0 | GH4169 has higher Cr |
| Iron (Fe) | Balance (~18-20) | ≤ 2.0 | GH4169 has much higher Fe |
| Aluminum (Al) | 0.20 – 0.80 | 5.5 – 6.5 | 713C has much higher Al |
| Molybdenum (Mo) | 2.80 – 3.30 | 3.5 – 5.0 | 713C higher |
| Niobium (Nb) | 4.75 – 5.50 | 1.5 – 2.5 | GH4169 has higher Nb |
| Titanium (Ti) | 0.65 – 1.15 | 0.4 – 1.0 | Similar |
| Cobalt (Co) | ≤ 1.00 | ≤ 1.0 | Similar |
| Carbon (C) | ≤ 0.08 | 0.05 – 0.15 | 713C higher C |
| Boron (B) | 0.002 – 0.006 | 0.005 – 0.015 | 713C higher B |
| Zirconium (Zr) | – | 0.05 – 0.15 | 713C unique |
| Manganese (Mn) | ≤ 0.35 | ≤ 0.20 | – |
| Silicon (Si) | ≤ 0.35 | ≤ 0.50 | – |
5. Comparison of stress fracture and creep properties of GH4169 and Inconel 713C
| Property | GH4169 (718) | Inconel 713C |
|---|---|---|
| Stress Rupture (650°C/1000h) (MPa) | ~450 | – |
| Stress Rupture (700°C/1000h) (MPa) | ~300 | ~280 |
| Stress Rupture (800°C/1000h) (MPa) | ~140 | ~200 |
| Stress Rupture (900°C/1000h) (MPa) | – | ~120 |
| Stress Rupture (950°C/1000h) (MPa) | – | ~70-80 |
| Creep Strength (0.1%/1000h) | ~350 MPa (650°C) | ~200 MPa (800°C) |
| Maximum Service Temp (Load-Bearing) | ~650 – 700°C | ~950°C |
Click to download the GH4169 alloy PDF file now
6. Comparison of machining characteristics between GH4169 and Inconel 713C
| Property | GH4169 (718) | Inconel 713C | Advantage |
|---|---|---|---|
| Manufacturing Method | Wrought (rolling, forging) | Cast only | Different processes |
| Cold Formability | Difficult | N/A (cast only) | – |
| Hot Formability | Good | N/A | – |
| Weldability | Good (requires PWHT) | Poor | GH4169 |
| Machinability | Fair (~20% of 1% C steel) | Moderate (~25-30%) | 713C slightly better |
| Heat Treatment | Complex (solution + 2-step aging) | Solution + age | Similar complexity |
| Product Availability | Bar, forging, plate, tube | Castings only | GH4169 more versatile |
7. Comparison of forging and casting properties of GH4169 and Inconel 713C
| Feature | GH4169 (Wrought / Forged) | K418 (Investment Casting) | Commercial Impact |
| Global Equivalent | Inconel 718 / UNS N07718 | Inconel 713C / UNS N09713 | Direct Compliance Mapping. |
| Strengthening Phase | Gamma Double Prime (γ′′) | Gamma Prime (γ′) |
γ′ is more heat-stable. |
| Fabrication Method | Forging, Rolling, Machining | Investment Casting Only | K418 requires a foundry. |
| Mechanical Integrity (900°C) | Softens Significantly (Fail) | Remains Structural & Rigid | K418 wins in the "Red Zone". |
| Aluminum Content | ~ 0.5% (Low) | **~ 6.0% (High)** | Al forms the heat shield. |
| Industrial Role | Dynamic Load / Structural | Extreme Heat / Static & Rotary | Match the alloy to the heat. |
8. How to Choose Between GH4169 and Inconel 713C?
If you are manufacturing parts that require complex machining and must withstand significant centrifugal stress at temperatures below 700°C, order GH4169 forged bars/plates. It is the most cost-effective solution for aero-engine shafts and discs.
If you are manufacturing turbine impellers or nozzles, and the component is exposed to direct combustion gases above 900°C, order K418 master alloy/cast bars. In this case, preventing thermal deformation and creep fracture is the primary concern for ensuring industrial durability.
Contact our professionals to recommend the right alloy for your project
Why source GH4169 from Tier 1 manufacturer Gnee Alloy?
As professional superalloy experts, Gnee Alloy ensures that both forging and casting solutions meet zero-defect quality standards:
✅️VIM (Vacuum Induction Melting): Every K418 master alloy rod is vacuum-melted to ensure zero gas porosity in your final castings.
✅️MTC 3.1 Traceability: Full heat-analysis and stress-rupture test results (verified at 981°C for K418) included.
✅️Wholesale Inventory: Massive stock of GH4169 Forged Bars and K418 Master Alloy Rods ready for Fast Global Shipping.
✅️Custom Fabrication: We offer precision cutting for forged bars and specific ingot sizes for your casting crucibles.
Contact us now to get the latest export price for GH4169 in 2026
FAQ
Q1: Why can't I forge K418 into a shaft?
A: K418 has such high hot-strength and low ductility (due to its high Al+Ti content) that it will crack instantly if you attempt to forge it. It is designed to be melted and poured into a ceramic mold (Investment Casting).
Q2: Is GH4169 equivalent to K418 in cost?
A: Generally, GH4169 is more expensive per kg due to the high Niobium (Nb) content and the complex multi-stage forging and aging processes. However, K418 requires an investment casting process, which adds to the final part cost.
Q3: Can K418 be welded for repair?
A: It is extremely difficult. Like most high-gamma-prime alloys, K418 is prone to strain-age cracking. We recommend specialized laser-cladding or induction brazing for repairs.
Q4: Do you offer trial quantities of K418 master alloy?
A: Absolutely. We support R&D and small foundries by offering Flexible MOQs on our K418 cast rods (standard diameters 50mm - 90mm).
