Hangbo Alloy Group
Shanghai · Est. 2012
N09909 technical guide: nominal chemical composition, mechanical and physical properties, corrosion resistance, welding, product forms and ASTM standards...
Incoloy 909 (UNS N09909) is a precipitation-hardenable low-expansion ni-fe-co-cr alloy. Weldability-improved 900-series low-expansion alloy. Lower strain-age cracking than 907. 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 Incoloy 909 for a project.
Incoloy 909 belongs to the precipitation-hardenable low-expansion ni-fe-co-cr alloy class of materials. It is weldability-improved 900-series low-expansion alloy. It is lower strain-age cracking than 907. It is high strength + steel-like expansion.
Nominal (wt%) composition of Incoloy 909 (UNS N09909):
| Element | Composition (wt%) |
|---|---|
| Nickel (Ni) | 35.0 – 40.0 |
| Iron (Fe) | Balance |
| Cobalt (Co) | 12.0 – 16.0 |
| Chromium (Cr) | 11.0 – 14.0 |
| Niobium (Nb) | 4.0 – 5.0 |
| Titanium (Ti) | 2.5 – 3.0 |
| Aluminium (Al) | 0.2 – 0.5 |
| Silicon (Si) | 0.30 – 0.60 |
| Carbon (C) | ≤ 0.06 |
| Manganese (Mn) | ≤ 1.0 |
| Sulphur (S) | ≤ 0.015 |
| Phosphorus (P) | ≤ 0.015 |
Typical physical properties:
| Property | Value |
|---|---|
| Density | 8.26 g/cm³ |
| Melting Range | 1300 – 1360 °C |
| Thermal Expansion (20–600 °C) | ≈ 7.8 µm/m·K |
| Thermal Conductivity (100 °C) | 11.0 W/m·K |
| Modulus of Elasticity | 201 GPa |
Typical room-temperature mechanical properties (annealed / specified condition unless noted):
| Property | Typical Value |
|---|---|
| Tensile Strength (Rm), aged | 1200 MPa (174 ksi) |
| Yield Strength, 0.2% (Rp0.2), aged | 830 MPa (120 ksi) |
| Elongation in 50 mm, aged | 14% |
| Hardness (Rockwell C), aged | 33 – 43 HRC |
| Property | Value |
|---|---|
| Coefficient of thermal expansion | ≈ 7.8 µm/m·K (low) |
| Service temperature | Up to 600 °C |
909 is the weldability-improved, tighter-silicon member of the 900-series low-expansion superalloys. It delivers high strength with steel-like expansion and better resistance to strain-age cracking after welding than 907, while chromium provides moderate oxidation resistance.
Welded with matching fillers under a qualified procedure; the controlled silicon reduces strain-age cracking. Post-weld solution treat and age develop full properties. Often used overaged for stability.
The grade is supplied to the following common specifications:
| Standard | Product Form / Scope |
|---|---|
| ASTM B638 | Precipitation-hardenable Ni-Fe-Cr-Co alloy bar/forgings |
| AMS 5892 | Aerospace grade |
909 is the weldability-improved member of the 900-series low-expansion superalloys. It gives high strength (≈ 1200 MPa tensile aged) with steel-like thermal expansion and less strain-age cracking after welding than 907.
Aged: ≈ 1200 MPa tensile, ≈ 830 MPa yield, ≈ 14 % elongation, 33–43 HRC, with thermal expansion to 600 °C about 7.8 µm/m·K.
Choose 909 when fabrications are welded or when lower magnetic permeability and easier processing are needed; 907 remains the broad general grade. Mechanical properties are very close.
Yes. Matching fillers plus a controlled silicon level reduce strain-age cracking; post-weld solution treat and age restore properties. Often used overaged.
Aero-engine casings, rings, shafts, turbine cases and fasteners where controlled thermal expansion and weldability both matter.
Bar/forgings ASTM B638, aerospace grade AMS 5892.
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.