Inconel 740H – Advanced Nickel-Based Superalloy for Ultra-Supercritical Applications
Supplied by Huaxiao-Alloy – Your Trusted Global Alloy Partner
Introduction: Meeting the Demands of the Next Generation
The energy, aerospace, and chemical industries are continuously evolving toward higher efficiency, longer life, and stricter emission standards. These demands require materials capable of surviving ultra-supercritical steam environments, high-pressure gas turbines, and corrosive industrial atmospheres.
This is where Inconel 740H (UNS N07740) stands out. It is a precipitation-hardened nickel-based superalloy developed to operate at temperatures up to 800–850 °C (1472–1562 °F) while offering superior creep strength, oxidation resistance, and structural stability.
At Huaxiao-Alloy, we provide Inconel 740H sheets, plates, pipes, bars, and custom components, manufactured to ASTM, ASME, and international standards. With extensive expertise in high-temperature alloys, we support clients across power generation, oil & gas, aerospace, and chemical processing.
1. What is Inconel 740H?
Inconel 740H is an advanced nickel-chromium-cobalt alloy strengthened by γ’ (gamma-prime) precipitation. Unlike conventional alloys, it is engineered to deliver long-term microstructural stability and creep rupture resistance at high stress and temperature.
UNS Number: N07740
Trade Names: Inconel 740H, Alloy 740H
Standards: ASTM B564, B572, B619, B622, B626; ASME Boiler and Pressure Vessel Code
Key Features
Exceptional creep strength beyond 750 °C.
Resistance to oxidation, carburization, and sulfidation.
Excellent phase stability – minimal grain growth at elevated temperatures.
Weldability and fabricability suitable for large industrial components.
Specifically designed for ultra-supercritical (USC) power plant applications.
2. Chemical Composition of Inconel 740H
| Element | Content (%) |
|---|---|
| Nickel (Ni) | Balance |
| Chromium (Cr) | 24–25 |
| Cobalt (Co) | 19–20 |
| Molybdenum (Mo) | 0.5–2 |
| Titanium (Ti) | 1.3–1.6 |
| Aluminum (Al) | 1.2–1.6 |
| Niobium (Nb) | 1.5–2.0 |
| Carbon (C) | 0.05–0.1 |
| Boron (B) | ≤ 0.01 |
| Iron (Fe) | ≤ 2.0 |
👉 The high chromium content ensures oxidation resistance, while cobalt enhances solid-solution strength. The precipitation of γ’ (Ni3(Al,Ti)) contributes to long-term creep strength.
3. Mechanical Properties of Inconel 740H
Typical Room-Temperature Properties
| Property | Value |
|---|---|
| Density | 8.25 g/cm³ (0.298 lb/in³) |
| Melting Range | 1320–1380 °C (2410–2520 °F) |
| Tensile Strength | ~ 950 MPa (138 ksi) |
| Yield Strength (0.2% offset) | ~ 650 MPa (94 ksi) |
| Elongation | 30–35% |
| Hardness | ~ 92 HRB |
High-Temperature Strength
Retains excellent creep rupture strength at 750–800 °C.
Designed to endure >100,000 hours service life in USC boilers and turbines.
4. Oxidation & Corrosion Resistance
Inconel 740H is designed to combat oxidizing, carburizing, and sulfidizing environments.
Oxidation resistance up to 850 °C (1560 °F).
Superior performance in superheated steam environments compared with Inconel 617 and 625.
Maintains scale adhesion during thermal cycling.
Strong resistance to chloride-induced stress corrosion cracking.
5. Forms of Supply by Huaxiao-Alloy
We supply Inconel 740H in all commercial forms:
Plates, Sheets & Strips (ASTM B435) – for turbine liners, boiler tubes, and heat shields.
Bars & Rods (ASTM B572) – for fasteners, supports, and load-bearing components.
Pipes & Tubes (ASTM B619, B622, B626) – for USC boiler tubes, petrochemical reactors.
Forgings & Fittings (ASTM B564) – for power plant components and custom designs.
Welding Wire & Electrodes – for joining high-temperature structures.
6. Applications of Inconel 740H
Power Generation
Ultra-supercritical (USC) and advanced ultra-supercritical (A-USC) boilers.
Steam turbine blades and casings.
Heat exchangers and superheater tubing.
Aerospace
Turbine hot-section components.
Combustor liners and transition ducts.
Exhaust system parts requiring creep resistance.
Petrochemical & Chemical Processing
High-temperature reformers.
Hydrogen production and syngas plants.
Catalyst support grids.
Furnace & Metallurgical Industry
Furnace fixtures and radiant tubes.
Carburizing and nitriding furnace parts.
Heat-treatment tooling.
7. Comparison with Other Inconel Alloys
| Alloy | Max Temp. | Oxidation Resistance | Creep Strength | Weldability | Notes |
|---|---|---|---|---|---|
| Inconel 625 | ~982 °C | Very Good | Moderate | Excellent | Best corrosion resistance, less creep strength |
| Inconel 617 | ~1100 °C | Excellent | High | Good | Good for gas turbines |
| Inconel 230 | ~1150 °C | Outstanding | High | Excellent | Better for oxidation environments |
| Inconel 740H | ~850 °C | Excellent | Superior | Excellent | Best for USC power applications |
While Inconel 230 and 617 excel in oxidation resistance at very high temps, Inconel 740H outperforms them in long-term creep rupture strength at 700–800 °C, making it the alloy of choice for USC boilers.
8. Fabrication & Processing
Formability: Good hot and cold workability.
Heat Treatment: Age-hardened after solution annealing to develop γ’ phase.
Weldability: Excellent; recommended welding techniques include GTAW (TIG), GMAW (MIG), and SMAW.
Machinability: Similar to other Ni-Co alloys; requires rigid tooling.
Inconel 740H is primarily used in ultra-supercritical (USC) and advanced ultra-supercritical (A-USC) power plants, especially in boiler tubes, steam turbines, and superheater components. It is also applied in aerospace turbines, petrochemical processing, and high-temperature furnaces.
Excellent creep rupture strength at 700–800 °C
Superior oxidation and sulfidation resistance
Phase stability for long-term high-temperature service
Good weldability and fabricability
Inconel 617: Higher max service temperature (~1100 °C) but lower creep strength in USC steam conditions.
Inconel 230: Outstanding oxidation resistance but not optimized for creep rupture.
Inconel 740H: Specifically developed for USC power plants, offering the best long-term creep resistance at 750–800 °C.
Inconel 740H contains:
Nickel (balance)
Chromium (~24–25%)
Cobalt (~19–20%)
Titanium & Aluminum (for γ′ strengthening)
Niobium, Molybdenum, Carbon (trace strengthening elements)
Yes. Inconel 740H is highly weldable using conventional methods such as TIG (GTAW), MIG (GMAW), and SMAW. Post-weld heat treatment may be required to optimize creep strength.
We provide:
Plates, sheets, and strips
Pipes and tubes (seamless & welded)
Bars, rods, and forgings
Fittings and custom-machined parts
Welding wire and electrodes
Power Generation: USC boilers, turbines, heat exchangers
Aerospace: Combustion chambers, exhaust systems
Petrochemical: Hydrogen plants, reformers
Industrial Furnaces: Radiant tubes, heat-treatment fixtures
Inconel 740H is designed for reliable use up to 850 °C (1562 °F) in high-pressure, high-stress conditions.
At Huaxiao-Alloy, we maintain a global inventory of Inconel 740H in standard dimensions. Custom orders and processing (cutting, forging, CNC machining) are also available upon request.
9. Why Choose Huaxiao-Alloy for Inconel 740H?
As a trusted supplier of nickel-based superalloys, Huaxiao-Alloy offers:
✅ Certified Quality – All products meet ASTM, ASME, and customer-specific standards.
✅ Global Stock – Ready-to-ship inventory of sheets, plates, tubes, and bars.
✅ Engineering Support – Expert metallurgists assist in material selection.
✅ Custom Processing – Cutting, forging, CNC machining, and surface treatment.
✅ Competitive Pricing & Delivery – Cost-effective supply with timely logistics.
📩 Email: [email protected]
📱 WhatsApp: +1 (579) 300-2733
10. Conclusion
Inconel 740H represents a new generation of nickel-based superalloys, specifically developed to withstand the high stresses and corrosive environments of ultra-supercritical power plants. Its γ’ strengthening mechanism, superior creep resistance, and excellent weldability make it indispensable for energy, aerospace, chemical, and furnace industries.
At Huaxiao-Alloy, we are committed to delivering Inconel 740H in all forms and dimensions, backed by technical expertise, certified quality, and global supply capability.
👉 Contact us today to discuss your Inconel 740H project requirements and request a custom quote.
Inconel 740H – Advanced Nickel-Based Superalloy for Ultra-Supercritical Applications
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