Inconel X-750 Nickel-Based Superalloy Complete Introduction

Inconel X-750 (UNS N07750 / W.Nr. 2.4669, corresponding to Chinese grade GH4145) is a precipitation-hardenable nickel-chromium-iron superalloy. Its primary strengthening mechanism relies on the precipitation of the gamma prime [γ′—Ni₃(Al, Ti, Nb)] phase. It delivers good corrosion and oxidation resistance below 980°C, maintains high strength below 800°C, and exhibits excellent stress relaxation resistance below 540°C. Shanghai COCESS Special Alloys Co., Ltd​ supplies this critical alloy, providing accurate technical data to support your high-temperature engineering selections.

Precise Chemical Composition (Mass Fraction %)

The performance of Inconel X-750 is strictly governed by its balanced chemistry, which enables both precipitation hardening and environmental resistance:

• Nickel (Ni):​ ≥ 70.0 (Balance/Matrix, provides austenitic stability).

• Chromium (Cr):​ 14.0 – 17.0 (Forms Cr₂O₃ scale for oxidation/corrosion resistance).

• Iron (Fe):​ 5.0 – 9.0 (Solid solution element, aids processing).

• Titanium (Ti):​ 2.25 – 2.75 (Primary contributor to γ′ phase formation/hardening).

• Aluminum (Al):​ 0.40 – 1.00 (Synergizes with Ti for γ′ stability and oxidation adherence).

• Niobium + Tantalum (Nb+Ta):​ 0.70 – 1.20 (Refines γ′ distribution, enhances creep resistance).

• Carbon (C):​ ≤ 0.08 (Forms grain boundary carbides for strength).

• Impurities:​ Manganese (Mn) ≤ 1.00, Silicon (Si) ≤ 0.50, Sulfur (S) ≤ 0.010, Copper (Cu) ≤ 0.50, Cobalt (Co) ≤ 1.00.

Key Physical & Mechanical Properties

As a precipitation-hardened alloy, its mechanical properties are highly dependent on heat treatment (typically Solution Treated + Aged), whereas physical properties remain relatively constant:

• Physical Data:​ Density 8.28 g/cm³; Melting Range 1393 – 1427°C; Elastic Modulus (20°C) ~215 GPa; Thermal Conductivity (20°C) ~14.7 W/(m·K).

• Room Temperature Mechanical (Typical Aged/Standard Condition, ASTM B637 Reference):

  • Tensile Strength (Rm): 1138 – 1379 MPa​ (Often 1200 – 1400 MPa typical).

  • Yield Strength (Rp0.2): ≥ 965 MPa​ (Typical 800 – 1050 MPa).

  • Elongation (A): ≥ 15 – 20%​ (Ensures toughness for fasteners/springs).

  • Hardness: Typically HRC 32 – 35​ (Approx. 300 – 350 HB).

• Elevated Temperature Performance:

  • At 600°C: Tensile strength remains approx. 950 MPa, Yield ~750 MPa.

  • At 700°C: Tensile strength approx. 800 – 880 MPa, Yield ~500 – 600 MPa.

  • At 800°C: Tensile strength approx. 600 MPa.

  • Creep/Relaxation:​ Exhibits exceptional stress relaxation resistance (retaining >90% load after 1000h at 540-600°C) and low creep rates (e.g., ~0.1% creep in 1000h at 700°C under 180 MPa stress), making it ideal for springs and high-temp fasteners.

Applicable ASTM & Industrial Standards

Inconel X-750 is supplied by Shanghai COCESS Special Alloys Co., Ltd​ in compliance with major international specifications:

• Bar, Rod, Forgings, Rings:​ ASTM B637 / ASME SB-637, AMS 5667, 5668, 5669, 5670, 5671.

• Plate, Sheet, Strip:​ AMS 5542, AMS 5598, ISO 6208.

• Wire:​ AMS 5698, AMS 5699.

Core Industrial Applications

The alloy’s unique combination of 800°C strength and 540°C relaxation resistance defines its primary use cases:

• Aerospace & Gas Turbines:​ Turbine blades/disks (up to 800°C), combustion chamber components, high-temperature fasteners (bolts/nuts), thrust chambers for rockets, and anti-thrust device parts.

• Springs & Fasteners:​ Flat spiral/helical springs, wave springs, and elastic seals operating in the 540°C – 800°C range where maintaining preload (relaxation resistance) is critical.

• Nuclear & Energy:​ Control rod drive mechanism parts in nuclear reactors, high-temperature pressure vessel fasteners.

• Industrial Processing:​ Heat treating fixtures, furnace conveyor parts, petrochemical high-pressure reactor components.

For detailed Mill Test Certificates (MTC) verifying these precise chemical and mechanical parameters, or to source Inconel X-750 products for your high-temperature applications, contact the technical team at Shanghai COCESS Special Alloys Co., Ltd.

Website: https://en.cocessalloys.com
Email: sales@cocessalloys.com