Nickel Chromium Superalloy Inconel X 750 Tube For Aerospace Power Generation
Inconel X‑750 Tubes: Nickel-Chromium Superalloy for Aerospace and Power Generation Applications
Product Overview
Inconel X‑750 Tubes (UNS N07750) are precipitation‑hardenable nickel‑chromium alloys formulated to deliver exceptional strength, oxidation resistance, and stress‑rupture performance in temperatures up to 700 °C. The alloy’s composition—typically 70–75 % Ni, 14–17 % Cr, 0.75–1.50 % Ti, and 0.15–0.75 % Al—ensures a uniform distribution of γ′ precipitates upon aging, which elevates yield strength to over 830 MPa and tensile strength beyond 1 030 MPa, while maintaining elongation above 15 %. This blend of high‑temperature creep resistance, fatigue life, and corrosion resistance makes X‑750 tubing ideal for aerospace hot‑section ducting, nuclear steam generator coils, and chemical reactor heat exchangers.
Beyond elevated‑temperature strength, Inconel X‑750 Tubes exhibit excellent resistance to chloride stress‑corrosion cracking and pitting, even under cyclic thermal loading. They can be readily welded by TIG/GTAW or electron‑beam methods—with post‑weld aging restoring full hardness—and formed into coils or complex assemblies. Standard tube offerings span ½ in. through 6 in. OD, wall thicknesses from 0.028 in. to 0.500 in., with options for mill‑annealed, cold‑worked, or pickled finishes. Custom heat‑treatment cycles are available to optimize properties for specific service conditions.
Chemical Composition
| Element | Content (%) |
|---|---|
| Nickel (Ni) | 70.0 – 75.0 |
| Chromium (Cr) | 14.0 – 17.0 |
| Iron (Fe) | Balance |
| Titanium (Ti) | 0.75 – 1.50 |
| Aluminum (Al) | 0.15 – 0.75 |
| Cobalt (Co) | ≤ 1.00 |
| Manganese (Mn) | ≤ 1.00 |
| Silicon (Si) | ≤ 1.00 |
| Carbon (C) | ≤ 0.08 |
| Sulfur (S) | ≤ 0.015 |
| Phosphorus (P) | ≤ 0.015 |
| Copper (Cu) | ≤ 0.50 |
| Boron (B) | 0.003 – 0.010 |
| Zirconium (Zr) | ≤ 0.02 |
Mechanical Properties
| Condition | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) | Hardness (HRC) |
|---|---|---|---|---|
| Mill Annealed (∼980 °C) | ~345 | ~760 | ≥ 40 | ≤ 90 HRB |
| Aged (565 °C for 16 h + 704 °C for 4 h) | ≥ 830 | ≥ 1 030 | ≥ 15 | 35 – 45 |
Physical Properties
| Property | Value |
|---|---|
| Density | 8.21 g/cm³ |
| Melting Range | 1260 – 1340 °C |
| Thermal Conductivity (20–600 °C) | 11 W/m·K |
| Specific Heat Capacity (25 °C) | 439 J/kg·K |
| Coefficient of Thermal Expansion (20–100 °C) | 13.4 µm/m·°C |
| Electrical Resistivity (20 °C) | 1.0 µΩ·m |
| Magnetic Permeability | ≈ 1.002 (non‑mag.) |
Conformance Standards
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ASTM B637 / SB‑637 – Precipitation‑hardened nickel‑alloy tubing
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AMS 5664 – Special quality Inconel X‑750 tubing
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AMS 5599 – Welded Inconel X‑750 tubing
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ASME SB‑637 – Boiler & Pressure Vessel Code
Applications
Inconel X‑750 Tubes are specified for:
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Aerospace – Jet engine ducting, afterburner fuel lines, and turbine support struts.
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Power Generation – Superheater/reheater tubing in steam turbines and boiler coils.
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Chemical Processing – High‑temperature reactor coils, heat exchangers, and down‑line instrumentation.
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Nuclear – Steam generator tubing and reactor core components.
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Oil & Gas – Downhole temperature/pressure sensor lines and subsea manifolds.
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Marine – Seawater cooler tubing and desalination plant heat‑exchanger coils.
Frequently Asked Questions
Q1: What sets Inconel X‑750 Tubes apart from other nickel alloys?
A1: Their combination of creep‑ and fatigue‑resistance at temperatures up to 700 °C, along with excellent stress‑corrosion cracking resistance, makes X‑750 uniquely suited to cyclic high‑temperature service.
Q2: Are X‑750 tubes weldable without loss of properties?
A2: Yes—both TIG and electron‑beam welding are routine. A post‑weld aging cycle fully restores precipitation‑hardened strength.
Q3: What tube sizes and finishes are offered?
A3: OD from ½ in. to 6 in., wall thickness 0.028 – 0.500 in.; mill‑annealed, cold‑worked, pickled, or electropolished finishes available per specification.
Get in Touch
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