Hangbo Alloy Group
Shanghai · Est. 2012
N07738 technical guide: nominal chemical composition, mechanical and physical properties, corrosion resistance, welding, product forms and ASTM standards...
Inconel 738 (UNS N07738) is a cast nickel-base superalloy (γ′ strengthened). Cast γ′-strengthened turbine hot-section alloy. High Cr + Co + W/Ta for hot corrosion & creep. 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 738 for a project.
Inconel 738 belongs to the cast nickel-base superalloy (γ′ strengthened) class of materials. It is cast γ′-strengthened turbine hot-section alloy. It is high cr + co + w/ta for hot corrosion & creep. It is first-stage blade/vane workhorse.
Nominal (wt%) composition of Inconel 738 (UNS N07738):
| Element | Composition (wt%) |
|---|---|
| Nickel (Ni) | Balance |
| Chromium (Cr) | 15.5 – 20.0 |
| Cobalt (Co) | 8.0 – 10.0 |
| Molybdenum (Mo) | 1.5 – 2.5 |
| Tungsten (W) | 2.0 – 3.0 |
| Tantalum (Ta) | 1.5 – 2.0 |
| Niobium (Nb) | 0.6 – 1.1 |
| Aluminium (Al) | 3.2 – 3.7 |
| Titanium (Ti) | 3.2 – 3.7 |
| Iron (Fe) | ≤ 1.0 |
| Carbon (C) | 0.09 – 0.17 |
| Zirconium (Zr) | 0.03 – 0.10 |
Typical physical properties:
| Property | Value |
|---|---|
| Density | 8.11 g/cm³ |
| Melting Range | 1230 – 1320 °C |
| Thermal Expansion (20–1000 °C) | 15.6 µm/m·K |
| Thermal Conductivity (100 °C) | 10.5 W/m·K |
| Modulus of Elasticity | 205 GPa |
Typical room-temperature mechanical properties (annealed / specified condition unless noted):
| Property | Typical Value |
|---|---|
| Tensile Strength (Rm), cast | ≥ 1000 MPa |
| Yield Strength, 0.2% (Rp0.2), cast | ≥ 800 MPa |
| Elongation, cast | ≥ 6% |
| Hardness (Rockwell C), cast | 35 – 45 HRC |
| Property | Value |
|---|---|
| Creep rupture at 850 °C / 1000 h | ≈ 200 MPa |
| Service temperature | Up to 900 °C (turbine hot section) |
738 is a cast, γ′-strengthened superalloy loaded with chromium, cobalt, molybdenum, tungsten, tantalum, aluminium and titanium for maximum creep strength and hot-corrosion/oxidation resistance in gas-turbine hot sections. It is the classic first-stage blade and vane alloy for industrial and aero-derivative turbines.
Repair welding of 738 blades uses matching or overalloyed (e.g., 738LC, 625) fillers with strict preheat/interpass control and post-weld heat treatment. As a cast alloy it is not routinely forged.
The grade is supplied to the following common specifications:
| Standard | Product Form / Scope |
|---|---|
| AMS 5383 | Castings, investment |
| PWA / GE / Rolls-Royce specs | OEM turbine material specs |
Standards & References. Specifications cited on this page; confirm current revisions with the issuing body.
General references: Nickel Institute · AMPP (corrosion) · SAE International · ASTM International
738 is a cast, γ′-precipitation-strengthened nickel superalloy loaded with Cr, Co, Mo, W, Ta, Al and Ti. It is the classic material for gas-turbine first- and second-stage blades and vanes because of its creep strength and hot-corrosion resistance to about 900 °C.
As cast it typically delivers ≥ 1000 MPa tensile, ≥ 800 MPa yield and ≥ 6 % elongation, with creep-rupture strength around 200 MPa at 850 °C / 1000 h.
Yes. Turbine blades are routinely repair-welded with matching or overalloyed fillers under strict preheat, interpass and post-weld heat-treatment control. It is a cast alloy and is not forged into bar.
718 is a weldable, forgeable precipitation alloy for discs, shafts and lower-temperature parts. 738 is a cast hot-section alloy optimised for blade/vane creep and hot corrosion, not for fabrication.
Investment castings are covered by AMS 5383, with most production governed by OEM turbine specifications (PWA, GE, Rolls-Royce).
Tungsten and tantalum raise solid-solution strengthening and slow γ′ coarsening at temperature, which is essential for the long-term creep resistance needed in turbine blades.
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.