Inconel X-750 · UNS N07750 · W. Nr. 2.4669 · GH4145 · NiCr15Fe7TiAl
Inconel X-750 (N07750): composition, properties, fittings and flanges
Inconel X-750 (UNS N07750, W. Nr. 2.4669, GH4145) is a gamma-prime hardened Ni-Cr-Fe-Ti-Al superalloy. Its nominal composition is 70 % nickel minimum, 14-17 % chromium, 5-9 % iron, 2.25-2.75 % titanium, 0.40-1.00 % aluminium and 0.70-1.20 % niobium plus tantalum. After solution treatment and single or double ageing the alloy…
- UNS
- N07750
- W. Nr.
- 2.4669
- Density
- 8.28 g/cm³ (0.299 lb/in³)
- Key strength
- 1170 MPa / 170 ksi
Identification and standards
| Short form | Inconel X-750 · UNS N07750 · W. Nr. 2.4669 · GH4145 · NiCr15Fe7TiAl |
|---|---|
| Classification | Gamma-prime precipitation-hardened nickel-chromium superalloy |
| UNS | N07750 |
| Werkstoff number | 2.4669 |
| Material family | Inconel Alloys |
Chemical composition
| Element | Composition (wt %) | Why it is there |
|---|---|---|
| Nickel + Cobalt (Ni+Co) | 70.0 min | Matrix |
| Chromium (Cr) | 14.0 - 17.0 | Oxidation and corrosion resistance |
| Iron (Fe) | 5.0 - 9.0 | - |
| Titanium (Ti) | 2.25 - 2.75 | Gamma prime former |
| Aluminium (Al) | 0.40 - 1.00 | Gamma prime former |
| Niobium + Tantalum (Nb+Ta) | 0.70 - 1.20 | Additional hardening, stabilises carbon |
| Manganese (Mn) | 1.00 max | - |
| Silicon (Si) | 0.50 max | - |
| Copper (Cu) | 0.50 max | - |
| Carbon (C) | 0.08 max | - |
| Sulphur (S) | 0.010 max | - |
Note Single figures are maximum limits unless shown as a range. Always confirm against the heat-specific EN 10204 3.1 certificate supplied with your order.
Mechanical properties
| Tensile strength, aged bar, typical | 1170 MPa / 170 ksi |
|---|---|
| 0.2 % yield strength, typical | 790 MPa / 115 ksi |
| Elongation in 2 in, typical | 20 - 25 % |
| Typical hardness after ageing | 302 - 363 HB |
| Typical stress relaxation limit, 1 % in 1000 h at 540 °C | About 480 MPa |
| Useful temperature range | -253 °C to 700 °C creep range, 980 °C oxidation limit |
Warning Values depend on product form, section thickness and heat treatment. Larger sections generally achieve lower strength than thin product; always design against the applicable code allowable stress rather than these figures.
Physical properties
| Density | 8.28 g/cm³ (0.299 lb/in³) |
|---|---|
| Melting range | 1393 - 1427 °C (2540 - 2600 °F) |
| Modulus of elasticity | 214 GPa (31 x 10⁶ psi) |
| Thermal conductivity at 20 °C | 12.0 W/m·K |
| Mean coefficient of thermal expansion, 20-100 °C | 12.8 µm/m·°C |
| Electrical resistivity at 20 °C | 1.22 µΩ·m |
Specifications by product form
| Bar / rod / wire / forgings | ASTM B637 / ASME SB-637, AMS 5667, AMS 5668, AMS 5670, AMS 5671 |
|---|---|
| Plate / sheet / strip | ASTM B670 / ASME SB-670, AMS 5542, AMS 5598 |
| Spring temper flat products | AMS 5698, AMS 5699 |
| Forgings & flanges | ASTM B637 / ASME SB-637 |
| Butt weld fittings | ASTM B366 (WP750) or machined from bar / forging |
| Welding consumables | ERNiCrFe-7; age after welding to restore properties |
| UNS / EN / China | UNS N07750 · EN NiCr15Fe7TiAl · W. Nr. 2.4669 · GB GH4145 |
Product forms available
Hangbo supplies this grade in the following forms. Sizes outside the listed range can often be produced to order.
- Flat rolled products including spring temper strip
- Forged bars, blocks and turbine blades
- Fasteners, bolting and springs aged after forming
- Elbows and fittings machined to drawing
- Forged flanges to customer dimensions
Typical applications
- Gas turbine rotor blades, discs, bolts and seal rings
- High-temperature coil and flat springs, including Belleville washers
- Steam and gas turbine bolting where relaxation resistance matters
- Nuclear reactor core internals and fuel element spacers
- Rocket engine thrust chambers and hot gas ducts
- Hot extrusion tooling and forming dies
Welding, forming and machining
- Heat treatment
- A typical sequence per AMS 5667 is solution treatment at about 1150 °C followed by air cooling, then an intermediate age at 840 °C for 24 hours, air cool, and a final age at 705 °C for 20 hours, air cool. Spring and fastener producers use tailored versions of this cycle.
- Welding
- Weld in the solution treated condition with ERNiCrFe-7 filler, then age the assembly. Post-weld ageing is essential to restore strength and avoid strain-age cracking.
- Forming
- Form springs and strip-derived parts in the annealed or spring temper condition and age afterwards. The alloy work hardens quickly but remains formable with intermediate annealing.
- Machining
- Best machined in the solution treated condition and then aged. Fully aged X-750 requires rigid carbide tooling and low cutting speeds.
Buy Inconel X-750 from Hangbo
Material is supplied with full heat-number traceability, solution annealing or ageing performed under calibrated furnace control, and an EN 10204 3.1 certificate covering chemical analysis, mechanical properties, heat treatment records and the agreed NDT scope. Positive material identification and third party inspection and test reports from SGS are available for critical service.