Hangbo Alloy Group
Shanghai · Est. 2012
N07751 technical guide: nominal chemical composition, mechanical and physical properties, corrosion resistance, welding, product forms and ASTM standards...
Inconel 751 (UNS N07751) is a precipitation-hardenable nickel-chromium alloy. Nb-modified X-750 for better creep to 815 °C. High relaxation resistance for springs/bolting. This guide covers its nominal chemical composition, typical mechanical and physical properties, corrosion behaviour, welding, common applications, available product forms and the ASTM standards that apply — everything a specifier needs to evaluate Inconel 751 for a project.
Inconel 751 belongs to the precipitation-hardenable nickel-chromium alloy class of materials. It is nb-modified x-750 for better creep to 815 °c. It is high relaxation resistance for springs/bolting. It is good oxidation resistance.
Nominal (wt%) composition of Inconel 751 (UNS N07751):
| Element | Composition (wt%) |
|---|---|
| Nickel (Ni) | ≥ 67.0 |
| Chromium (Cr) | 14.0 – 17.0 |
| Iron (Fe) | 5.0 – 9.0 |
| Niobium + Tantalum (Nb+Ta) | 0.7 – 1.2 |
| Titanium (Ti) | 2.0 – 2.6 |
| Aluminium (Al) | 0.9 – 1.5 |
| Cobalt (Co) | ≤ 1.0 |
| Carbon (C) | ≤ 0.10 |
| Manganese (Mn) | ≤ 1.0 |
| Silicon (Si) | ≤ 0.50 |
| Sulphur (S) | ≤ 0.010 |
| Copper (Cu) | ≤ 0.50 |
Typical physical properties:
| Property | Value |
|---|---|
| Density | 8.25 g/cm³ |
| Melting Range | 1300 – 1365 °C |
| Thermal Expansion (20–1000 °C) | 13.6 µm/m·K |
| Thermal Conductivity (100 °C) | 11.5 W/m·K |
| Modulus of Elasticity | 208 GPa |
Typical room-temperature mechanical properties (annealed / specified condition unless noted):
| Property | Typical Value |
|---|---|
| Tensile Strength (Rm), aged | 895 MPa (130 ksi) |
| Yield Strength, 0.2% (Rp0.2), aged | 620 MPa (90 ksi) |
| Elongation in 50 mm, aged | 20% |
| Hardness (Rockwell C), aged | 24 – 35 HRC |
| Property | Value |
|---|---|
| Creep rupture at 650 °C / 100 h | ≈ 450 MPa |
| Service temperature | Up to 815 °C |
751 is a niobium-modified version of X-750 with improved creep and stress-rupture strength in the 540–815 °C range. It keeps good oxidation resistance and retains its properties in long-term high-temperature service, suiting gas-turbine and engine bolting.
Welded with Inconel 718-type fillers (ERNiFeCr-2) where matching properties are not critical; post-weld age restores strength. Avoid prolonged exposure in the 650–870 °C sensitisation window without ageing.
The grade is supplied to the following common specifications:
| Standard | Product Form / Scope |
|---|---|
| ASTM B637 | Precipitation-hardenable Ni-Fe-Cr alloy bar/forgings |
| AMS 5667 / 5698 | Aerospace bar & wire |
Standards & References. Specifications cited on this page; confirm current revisions with the issuing body.
General references: Nickel Institute · AMPP (corrosion) · SAE International · ASTM International
751 is a niobium-modified, precipitation-hardenable Ni-Cr alloy derived from X-750. The niobium addition raises creep and stress-rupture strength in the 540–815 °C range, so it is used for turbine seals, rings and high-temperature bolting.
Both are γ′-hardened Ni-Cr alloys, but 751 has a tighter niobium/titanium balance that improves long-term creep and stress-rupture strength and relaxation resistance. X-750 is the more general-purpose grade.
Aged condition: ≈ 895 MPa tensile, ≈ 620 MPa yield, ≈ 20 % elongation, 24–35 HRC. Creep-rupture strength at 650 °C / 100 h is about 450 MPa.
Yes. Its high relaxation resistance at temperature makes it suitable for springs, lock-wire and fasteners in turbine and exhaust applications.
Usually with ERNiFeCr-2 (718-type) filler when matching strength is not required, followed by an age. Keep welds out of the 650–870 °C sensitisation band unless aged.
Bar and forgings are covered by ASTM B637, with aerospace grades under AMS 5667 and AMS 5698 (wire).
As a dedicated nickel alloy manufacturer serving aerospace, power generation sectors, Hangbo Alloy Group supplies the grades discussed here across all standard product forms with full ASTM/ASME documentation and EN 10204 3.1 certification. Our material is specified for applications where corrosion resistance, high-temperature strength, and traceable quality are non-negotiable. See our production & testing facilities for more on how every heat is verified.