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Inconel X-750 (UNS N07750) supplier — ASTM B637. Precipitation-hardenable Ni-Cr alloy for springs, bolts, turbine components. Operating temp to 815°C. Round bar and forging.
Shanghai Hangbo Alloy Group Co., Ltd. is a leading manufacturer of high-performance Inconel X-750 (UNS N07750 / W.Nr. 2.4669). As a precipitation-hardenable nickel-chromium alloy, X-750 is the industry standard for high-strength springs and components requiring exceptional relaxation resistance at elevated temperatures and structural integrity in cryogenic environments.
Precise ASTM B637 Data Tables
Chemical Composition (ASTM B637 / UNS N07750)
| Element | Ni (+Co) | Cr | Fe | Ti | Al | Nb (+Ta) | Mn |
|---|---|---|---|---|---|---|---|
| Min (%) | 70.0 | 14.0 | 5.0 | 2.25 | 0.40 | 0.70 | - |
| Max (%) | - | 17.0 | 9.0 | 2.75 | 1.00 | 1.20 | 1.0 |
Mechanical Properties (ASTM B637 - Precipitation Hardened)
| Property | Typical Value (Min) |
|---|---|
| Tensile Strength | 1172 MPa (170 ksi) |
| Yield Strength (0.2% Offset) | 827 MPa (120 ksi) |
| Elongation (in 2") | 15% |
| Hardness | 32-40 HRC |
Material Characteristics
- High Relaxation Resistance: Retains its spring constant even after long-term exposure to temperatures up to 600°C (1100°F).
- Exceptional Cryogenic Performance: Unlike many high-strength alloys, X-750 maintains high ductility and toughness at temperatures as low as -250°C.
- Corrosion & Oxidation Resistance: Resists a wide range of industrial corrosives and high-temperature oxidation up to 980°C (1800°F).
- Precipitation Hardening: Strengthened by gamma prime phase precipitates, offering high creep-rupture properties.
Common Applications of Inconel X-750
- Springs: Critical valve springs, bellows, and seals in automotive and industrial engines.
- Aerospace: Rocket engine thrust chambers, gas turbine blades, and bolt-on fasteners.
- Nuclear: Fuel element spacers, structural supports, and spring-loaded fasteners in PWR reactors.
- Cryogenics: Structural components for liquid hydrogen and oxygen systems.
Pros & Cons of Alloy X-750
| Pros | Cons |
|---|---|
| Superior relaxation resistance for springs. | Difficult to machine (rapid work hardening). |
| Excellent cryogenic toughness. | Sensitive to heat treatment parameters. |
| High corrosion resistance in harsh media. | Higher cost than standard nickel alloys. |
Global Project Case: Subsea Safety Valve Springs
Scenario: A deep-sea oil extraction project in the Gulf of Mexico required high-performance springs for subsea safety valves. The springs needed to provide constant closing force under extreme pressure and temperature cycles for a 25-year service life.
Solution: Hangbo Alloy supplied high-precision Inconel X-750 wire (AMS 5698) for these springs. The material was selected specifically for its resistance to hydrogen embrittlement and chloride stress corrosion.
Service Performance: Relaxation Stability
Testing shows that Inconel X-750 springs, when properly heat-treated (Solution Treated + Aged), exhibit less than 5% relaxation after 1000 hours of continuous loading at 540°C (1000°F). This stability is unmatched by conventional stainless steel springs, ensuring the long-term reliability of critical safety systems.
Frequently Asked Questions (FAQ)
1. Why is Inconel X-750 the first choice for high-temperature springs?
Its high relaxation resistance means it maintains its spring load far better than other alloys when exposed to heat, preventing mechanical failure in valves and actuators.
2. How does X-750 perform in cryogenic environments?
It is one of the few high-strength materials that remains ductile and tough at liquid nitrogen temperatures (-196°C) without becoming brittle, making it ideal for space and gas storage applications.
3. What is the difference between Inconel 718 and X-750?
While both are precipitation-hardened, X-750 is specifically optimized for relaxation resistance and spring applications, whereas 718 is generally preferred for massive structural components and turbine disks.
4. Can Inconel X-750 be welded?
Yes, it can be welded by standard processes, but it is sensitive to strain-age cracking. Careful pre-weld and post-weld heat treatment is essential to maintain strength and crack resistance.
5. Is Inconel X-750 resistant to seawater corrosion?
Yes, it offers excellent resistance to chloride-ion stress corrosion cracking, which is a major advantage in marine and subsea oil & gas environments.
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