Hangbo Alloy Group
Shanghai · Est. 2012
N07783 technical guide: nominal chemical composition, mechanical and physical properties, corrosion resistance, welding, product forms and ASTM standards...
Inconel 783 (UNS N07783) is a precipitation-hardenable low-expansion ni-co-fe-cr alloy. High strength + low, steel-like thermal expansion. γ′ + γ″ + Al precipitation hardened. 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 783 for a project.
Inconel 783 belongs to the precipitation-hardenable low-expansion ni-co-fe-cr alloy class of materials. It is high strength + low, steel-like thermal expansion. It is γ′ + γ″ + al precipitation hardened. It is oxidation resistant to ~600 °c.
Nominal (wt%) composition of Inconel 783 (UNS N07783):
| Element | Composition (wt%) |
|---|---|
| Nickel (Ni) | 26.0 – 30.0 |
| Cobalt (Co) | 22.0 – 26.0 |
| Iron (Fe) | Balance |
| Chromium (Cr) | 2.5 – 4.0 |
| Niobium (Nb) | 2.5 – 4.0 |
| Aluminium (Al) | 5.0 – 6.0 |
| Titanium (Ti) | 0.1 – 0.4 |
| Carbon (C) | ≤ 0.03 |
| Manganese (Mn) | ≤ 0.5 |
| Silicon (Si) | ≤ 0.5 |
| Sulphur (S) | ≤ 0.005 |
| Phosphorus (P) | ≤ 0.015 |
Typical physical properties:
| Property | Value |
|---|---|
| Density | 8.33 g/cm³ |
| Melting Range | 1300 – 1360 °C |
| Thermal Expansion (20–600 °C) | ≈ 8.5 µm/m·K |
| Thermal Conductivity (100 °C) | 10.8 W/m·K |
| Modulus of Elasticity | 200 GPa |
Typical room-temperature mechanical properties (annealed / specified condition unless noted):
| Property | Typical Value |
|---|---|
| Tensile Strength (Rm), aged | 1240 MPa (180 ksi) |
| Yield Strength, 0.2% (Rp0.2), aged | 760 MPa (110 ksi) |
| Elongation in 50 mm, aged | 10% |
| Hardness (Rockwell C), aged | 35 – 45 HRC |
| Property | Value |
|---|---|
| Coefficient of thermal expansion | ≈ 8.5 µm/m·K (low) |
| Service temperature | Up to 600 °C |
783 pairs high strength (from γ′ and γ″ precipitation plus high aluminium) with a low, controlled coefficient of thermal expansion close to that of many steels. This makes it ideal where differential expansion between a superalloy part and a steel casing must be minimised while resisting oxidation.
Welded with matching fillers under a qualified procedure; post-weld solution treat and age are required to restore strength. Control heat input to avoid over-aging in the heat-affected zone.
The grade is supplied to the following common specifications:
| Standard | Product Form / Scope |
|---|---|
| ASTM B639 | Precipitation-hardenable Ni-Fe-Cr-Co alloy bar/forgings |
| AMS 5940 | Aerospace grade |
Standards & References. Specifications cited on this page; confirm current revisions with the issuing body.
General references: Nickel Institute · AMPP (corrosion) · SAE International · ASTM International
783 is a precipitation-hardenable Ni-Co-Fe-Cr alloy with a low coefficient of thermal expansion close to steel, combined with very high strength (≈ 1240 MPa tensile aged) and oxidation resistance to about 600 °C.
In turbine casings and rings the part must stay dimensionally matched to a steel housing across the operating temperature range. 783's steel-like expansion prevents binding, leaks and rubs that a high-expansion alloy would cause.
Aged: ≈ 1240 MPa tensile, ≈ 760 MPa yield, ≈ 10 % elongation, 35–45 HRC. Its mean thermal expansion to 600 °C is only about 8.5 µm/m·K.
Yes, with matching fillers under a qualified procedure, followed by solution treat and age to recover strength. Watch heat input in the HAZ to avoid over-aging.
Invar is a low-expansion iron-nickel steel with little high-temperature strength or oxidation resistance. 783 keeps low expansion but adds superalloy strength and oxidation resistance for engine-hot-section casings.
Bar and forgings are covered by ASTM B639, with aerospace grade under AMS 5940.
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.