Inconel 617
Inconel 617 (UNS N06617 / W.Nr. 2.4663) is a nickel-chromium-cobalt-molybdenum alloy specifically developed for service in extreme heat environments. It is most commonly supplied as seamless pipe and tube under ASTM B167. The defining characteristic of this alloy is its cobalt content between 10% and 15%. That cobalt level, combined with chromium and molybdenum, gives Inconel 617 a creep-rupture strength that most other nickel alloys cannot match above 800°C. It also maintains oxidation resistance up to 1100°C, which makes it suitable for continuous high-temperature service rather than just short-term exposure. Primary applications include gas turbine combustion hardware, nuclear high-temperature reactors (approved under ASME Code Case N-47), and solar thermal systems.
1. Chemical Composition
The table below lists the chemical composition of Inconel 617 per ASTM B167 requirements, along with its proportion.
| Grade | Ni | Cr | Co | Mo | Al | Fe | C | Mn | Si | S | P | Ti | B | Cu |
| Inconel 617 | 44.5 min | 20.0–24.0 | 10.0–15.0 | 8.0–10.0 | 0.8–1.5 | 3.0 max | 0.05–0.15 | 1.0 max | 1.0 max | 0.015 max | — | 0.6 max | 0.006 max | 0.5 max |
2. Mechanical Properties
Mechanical properties listed below are for the annealed condition of Inconel 617 as per ASTM B167.
| Property | Condition | Tensile Strength (min) | Yield Strength 0.2% Offset (min) | Elongation (min) | Hardness (max) | Service Temperature Range | Creep Rupture Strength (1000h at 871°C) |
| Value | Annealed | 655 MPa (95 ksi) | 241 MPa (35 ksi) | 30% | 90 HRB | Up to 1100°C (2012°F) | ~103 MPa |
3. Equivalent Grade
The table below gives the international grade equivalents for Inconel 617 across major standards.
| Grade | UNS | GB/T | JIS | DIN / EN (W.Nr.) | GOST |
| Inconel 617 | N06617 | NS3307 | NCF 617 | 2.4663 / NiCr23Co12Mo | -- |
3. Key Technical Advantages
Inconel 617 offers several well-documented performance advantages for ultra-high-temperature service. Below are the five most relevant from an engineering standpoint.
- Exceptional Creep-Rupture Strength Above 800°C: At 871°C, Inconel 617 withstands about 103 MPa for 1,000 hours. Regular stainless steels fail earlier. Cobalt helps keep the structure stable and slows deformation, giving superior high‑temperature strength.
- Oxidation Resistance to 1100°C: High chromium forms a protective chromium oxide layer at high temperatures. Adding aluminium creates an alumina sub-layer. Together, these two layers protect the alloy in air and combustion gases up to 1100°C.
- ASME Code Case N-47 Approval for Nuclear Service: Inconel 617 is one of the few alloys approved by ASME Code Case N-47 for high‑temperature nuclear components, safely handling cyclic stresses and creep, where most other nickel alloys are unsuitable.
- Good Resistance to Carbonisation and Sulphidation: In carbon-rich or sulphur-containing environments, such as petrochemical furnaces, this alloy corrodes more slowly than typical Ni-Cr alloys like Alloy 600, mainly due to its molybdenum content in reducing conditions.
- Solid Solution Strengthening Without Precipitation Hardening: Inconel 617 gets its strength from solid solution hardening, so it needs no ageing heat treatment and keeps stable, non‑brittle properties during long, high‑temperature service.
4. Common Manufacturing Standards
XTD produces Inconel 617 seamless pipe and tube in compliance with the following standards.
- ASTM B167: Seamless Ni-Cr / Ni-Cr-Fe alloy pipe & tube; main Inconel 617 spec
- ASME SB-167: ASME pressure vessel equivalent of B167
- ASTM B829 :General requirements for Ni-alloy seamless pipe & tube
- DIN 17752 / EN 10216-5 : European spec for seamless pressure tubes; Ni-alloy grades
- GB/T 14992: Chinese spec for high-temp alloy grades & composition
- ASTM E1473: Chemical analysis of Ni, Co & high-temp alloys
- ASTM A262: Test methods for intergranular attack susceptibility
5. Primary Applications
Inconel 617 seamless pipe is used in the following specific service environments.
- Gas Turbine Combustion Liners and Transition Ducts: Components exposed to continuous flame contact and thermal cycling between 900°C and 1100°C in industrial and aero-derivative turbines
- Nuclear High-Temperature Reactors (HTR/VHTR) Primary Circuit Piping: Helium coolant piping operating above 750°C in Generation IV reactor designs, qualified under ASME Code Case N-47
- Concentrated Solar Power (CSP) Receiver Tubes: Tubes carrying heat transfer fluid or steam in parabolic trough and central receiver solar thermal plants at operating temperatures above 600°C
- Reformer and Furnace Header Tubes in Hydrogen Production: High-temperature process piping in steam methane reforming units where tube metal temperatures exceed 850°C
- Aerospace Engine Hot Section Exhaust Manifolds: Exhaust manifold and afterburner components in military and commercial jet engines operating in oxidising gas streams above 900°C