Inconel X-750 (UNS N07750): The Industrial Strength of an Age Hardened Super Alloy
Alloy Definition and Chemical Composition
Inconel X-750 is a nickel-chromium based super alloy that can be hardened by ageing and has high mechanical strength at high temperature. Preferred mostly in parts operating under high temperature, this alloy stands out especially with its resistance to carbide precipitation, creep strength and stress cracking resistance.
Its chemical composition is as follows:
- Nickel (Ni): 70% minimum
- Chromium (Cr): 14 – 17%
- Iron (Fe): 5 – 9%
- Titanium (Ti): 2.25 – 2.75%
- Aluminium (Al): 0.4 – 1.0%
- Niobium + Tantalum (Nb+Ta): 0.7% maximum
- Carbon (C): 0.08% maximum
- Manganese (Mn), Silicon (Si): In trace amounts
The alloy has been formulated so as to provide gamma prime (γ’) precipitation in order for it to preserve its strength at high temperatures. These precipitates are activated by the ageing operation.
INCONEL X-750 Standards and Certifications
Inconel X-750 is produced in compliance with a large number of aerospace and industrial standards. These standards set out the quality control of the material in terms of machinability, strength and microstructure.
- AMS 5667 – Bars and forged products suitable for age hardening
- AMS 5542 – Sheet and plate products
- AMS 5582 – Seamless tubing
- ASTM B637 – General bar and forged parts
- UNS N07750
- Werkstoff Nr. 2.4669
The aerospace sector in particular prefers products compliant with the AMS 5667 and AMS 5542 specifications. In the supply process these codes play a key role in quality assurance systems.
INCONEL X-750 Trade Names and Equivalent Materials
- Inconel® X-750 – Special Metals brand (its most widespread commercial equivalent)
- Nicrofer 7016, ATI X750 – Alternative producer brands
- UNS N07750, 2.4669 – International designations
- NiCr15Fe7TiAl – European chemical notation
Although “X-750” in the literature is generally referred to by the name Inconel, chemically it represents the same alloy system. What matters is that the products comply with the technical standards.
Areas of Use and Engineering Applications
Inconel X-750 has a very broad area of use because it remains stable in parts under high temperature and stress:
1.Aerospace Systems
*Turbine discs in jet engines
*Springs and fasteners
*Exhaust systems and burner components
2.Nuclear Energy
*In-reactor springs and bracket systems
*Nuclear power plant valve and sealing systems
3.Gas Turbines
*Turbine blades
*High temperature sealing parts
4.Chemical and Petrochemical Plants
*Joints durable against thermal expansion
*High pressure gaskets and insulation parts
5.Cryogenic Systems
Because it preserves its mechanical stability in the cold, it is widely preferred in precision applications.
In these applications the properties of strength after ageing, corrosion resistance and a stable microstructure play a critical role.
Advantages
- High Strength Through Age Hardening: The alloy attains extraordinary high temperature strength with the ageing operation carried out between 705–760 °C. The γ’ phase precipitated after this operation increases tensile and creep strength.
- Corrosion and Oxidation Resistance: Thanks to its high chromium and nickel content it shows stability especially in oxidising environments and gas turbine exhausts.
- Good Weldability: It shows good performance especially in TIG and resistance welding operations. Cracking after welding is minimised with controlled preheating and post-ageing annealing.
- Stable Mechanical Properties for Springs: X-750 is known for its spring quality; it preserves its elastic properties under high temperature, and for this reason it is preferred under dynamic loads.
- Compatible with Cryogenic Environments: It preserves its mechanical integrity at both high and low temperatures.
Disadvantages
- Sensitivity to the Ageing Process: When the appropriate ageing protocol is not applied, there may be serious deviations in the mechanical properties. Process temperature and duration are critical parameters.
- Carbon and Titanium Carbide Formation: In cases of long-term high temperature exposure, carbide precipitation may occur at the grain boundaries. This situation may cause stress cracks.
- Machinability Limitations: High hardness and viscosity may accelerate tool wear in machining. It requires special tool geometries.
- Cost: Because the nickel ratio is high and it requires an ageing heat treatment, X-750 is not preferred in applications where it is uneconomical.
Conclusion and Engineering Evaluation
Inconel X-750 is a super alloy that exhibits high temperature performance through age hardening and provides superior protection against oxidative environments. It is used with confidence especially in fields such as aerospace, nuclear energy and high performance spring systems. Its stable microstructure, superior creep strength and spring properties make the material technically superior.
AMS, ASTM and EN standards compliance in its production makes it a reliable solution preferred in engineering projects in regulated sectors. Despite its high cost, a long service life and a low maintenance requirement reduce the total cost of ownership and thereby accelerate the return on investment.
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| Chemical Composition (2.4669) | | Room Temperature Mechanical Properties | |
|---|---|---|---|
| Grade | Inconel X-750 (2.4669) | Properties | Values |
| Ni+Co | min 70.0% | Density (Specific Gravity) | 8280 kg/m³ |
| Cr | 14.0-17.0% | Melting Point | 1393–1427°C |
| Fe | 5.00-9.00% | | |
| C | max 0.08% | | |
| S | max 0.01% | | |
| Al | 0.40-1.00% | | |
| Ti | 2.25-2.75% | | |
| Nb+Ta | 0.70-1.20% | | |
| Cu | max 0.50% | | |
| Co | max 1.00% | | |
| Mn | max 1.00% | | |
| Si | max 0.50% | |
We supply this material
We supply Inconel X750 (2.4669) — to AMS 5542, AMS 5667 standards, in the dimensions and forms required. For stock availability and pricing:
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