Alloy 617,Inconel 617 ,UNS N06617

Alloy 617,Inconel 617 Wire,UNS N06617

Introduction to Alloy 617 (Inconel 617 Wire, UNS N06617)

Alloy 617, commercially designated as Inconel 617 and classified under UNS N06617, is a nickel-chromium-cobalt-molybdenum superalloy engineered for exceptional performance in extreme high-temperature environments—operating reliably up to 1100°C/2012°F, with short-term service capabilities at 1200°C/2192°F. Its unique chemistry combines high chromium content (for oxidation resistance) with cobalt and molybdenum (for elevated-temperature strength), while austenitic microstructure ensures ductility even under thermal cycling. Unlike many high-temperature alloys, it maintains creep and stress rupture resistance at temperatures exceeding 900°C, making it a top choice for ultra-harsh thermal applications. Inconel 617 wire, a critical form of this alloy, is widely used in industries such as advanced energy generation, aerospace propulsion, and industrial heating, where it delivers consistent performance in environments like gas turbine hot sections, nuclear reactors, and high-temperature furnaces. Its excellent weldability and formability further extend its utility to precision components requiring both structural integrity and thermal stability.

1. Chemical Composition (Typical, wt%)

The chemical composition of UNS N06617 adheres to strict industry standards including ASTM B625 (for nickel-alloy wire), ASTM B564 (for nickel-alloy forgings), and ASME SB625, ensuring consistent high-temperature strength, oxidation resistance, and processability. The typical composition is as follows:

Element

Content Range (wt%)

Function

Nickel (Ni)

44.0 - 50.0

Serves as the primary matrix element, stabilizing the austenitic structure and providing a foundation for high-temperature ductility; enhances resistance to molten salt corrosion.

Chromium (Cr)

20.0 - 24.0

Forms a dense, self-healing chromium oxide (Cr₂O₃) layer, delivering superior oxidation and sulfidation resistance up to 1100°C—critical for withstanding flue gases or combustion environments.

Cobalt (Co)

10.0 - 15.0

A key high-temperature strengthener, improving creep and stress rupture resistance at 900 - 1100°C; stabilizes the alloy’s microstructure against phase transformations under extreme heat.

Molybdenum (Mo)

8.0 - 10.0

Enhances solid-solution strengthening, boosting tensile strength and creep performance; improves resistance to localized corrosion in chloride or sulfur-containing environments.

Aluminum (Al)

1.0 - 2.0

Aids in oxide layer formation (supplementing chromium oxide) and refines grain structure, enhancing thermal fatigue resistance; controlled to avoid brittle intermetallic phases.

Carbon (C)

0.05 - 0.15

Forms carbides (e.g., Cr₂₃C₆, Mo₂C) at grain boundaries, improving high-temperature strength and creep resistance; controlled to prevent excessive carbide precipitation (which reduces ductility).

Iron (Fe)

≤ 3.0

Improves hot workability (critical for wire rod production) and controls alloy cost without compromising high-temperature performance.

Manganese (Mn)

≤ 1.0

Aids in deoxidation during melting and improves cold workability for fine wire drawing; limited to avoid brittleness at elevated temperatures.

Silicon (Si)

≤ 1.0

Promotes oxide layer adhesion and reduces molten alloy viscosity during casting; controlled to avoid excessive silica formation (which degrades corrosion resistance).

Phosphorus (P)

≤ 0.03

Strictly limited to prevent grain boundary embrittlement, especially in welded joints exposed to cyclic high temperatures.

Sulfur (S)

≤ 0.015

Minimized to prevent hot cracking during fabrication (essential for wire drawing and welding) and reduce corrosion susceptibility in sulfur-rich environments.

Titanium (Ti)

≤ 0.5

Trace element that refines grain structure and enhances carbide formation, supplementing high-temperature strength.

2. Physical Properties

Inconel 617 wire exhibits stable physical properties across its ultra-high temperature operating range, with mechanical performance optimized for creep resistance and thermal stability. Key properties (measured at room temperature unless specified otherwise) are:

Property

Value

Test Condition

Density

8.36 g/cm³

Room temperature (25°C)

Melting Point Range

1290 - 1350°C

-

Thermal Expansion Coefficient

13.3 × 10⁻⁶/°C

20 - 100°C; 17.1 × 10⁻⁶/°C (20 - 1000°C)

Thermal Conductivity

11.6 W/(m·K)

100°C; 24.3 W/(m·K) (1000°C)

Electrical Resistivity

1.32 × 10⁻⁶ Ω·m

Room temperature (25°C); 1.68 × 10⁻⁶ Ω·m (1000°C)

Modulus of Elasticity

208 GPa

Room temperature (tensile); 135 GPa (1000°C)

Poisson’s Ratio

0.30

Room temperature

Curie Temperature

≈ -170°C

Below this temperature, weakly ferromagnetic (irrelevant for high-temperature applications).

Tensile Strength

≥ 760 MPa

Room temperature; ≥ 240 MPa (1000°C)

Yield Strength (0.2% Offset)

≥ 380 MPa

Room temperature; ≥ 140 MPa (1000°C)

Elongation

≥ 35%

Room temperature; ≥ 45% (1000°C)

Hardness (Annealed)

≤ 240 HB

Room temperature

Creep Rupture Strength

105 MPa

1000 hours at 900°C; 35 MPa (1000 hours at 1000°C)

Oxidation Resistance

Weight gain ≤ 0.2 g/m²·h

1000°C in air (after 1000 hours, no oxide spallation)

3. Production Process of Inconel 617 Wire

The manufacturing of Inconel 617 wire requires precise control of chemistry, heat treatment, and forming to preserve its ultra-high temperature performance—focusing on grain structure refinement and oxide layer integrity. Key steps include:

3.1 Raw Material Melting & Casting

Melting: High-purity raw materials (nickel, chromium, cobalt, molybdenum, etc.) are melted via vacuum induction melting (VIM) followed by vacuum arc remelting (VAR). This dual process eliminates gaseous impurities (O₂ < 20 ppm, N₂ < 35 ppm) and ensures uniform distribution of cobalt and molybdenum—critical for consistent high-temperature strength and creep resistance.

Casting: Molten alloy is cast into ingots (800 - 3000 kg) or blooms, which undergo homogenization annealing at 1180 - 1230°C for 10 - 12 hours. This step eliminates chemical segregation (especially of cobalt and molybdenum) and dissolves coarse carbides, preparing the material for hot working while preserving grain uniformity.

3.2 Hot Working & Wire Rod Production

Hot Rolling: Ingots/blooms are hot-rolled at 1100 - 1200°C into wire rods (diameter: 10 - 20 mm). Hot rolling is performed at higher temperatures than standard alloys to maintain ductility; rods are air-cooled to 800°C at a controlled rate (50 - 100°C/hour) to promote fine carbide precipitation—enhancing subsequent creep resistance.

Descaling: Hot-rolled rods undergo shot blasting (to remove loose oxide scale) followed by acid pickling (nitric-hydrofluoric acid solution) to eliminate residual chromium oxide layers. This step prevents surface defects during cold drawing and ensures uniform oxide layer formation in final applications.

3.3 Cold Drawing (Wire Formation)

Multi-Pass Cold Drawing: Wire rods are cold-drawn through diamond dies in 5 - 8 passes to achieve the desired diameter (typically 0.2 mm - 10 mm). Each pass reduces diameter by 15 - 25%, with intermediate annealing (1050 - 1100°C for 45 - 60 minutes, air-cooled) between passes. This annealing step relieves work hardening, restores ductility, and refines grain structure—critical for maintaining creep performance in thin wire.

Dimensional Control: Tension, die alignment, and drawing speed are precisely regulated to maintain tight diameter tolerance (±0.02 mm for precision wire) and roundness (≤0.01 mm). For high-temperature applications like turbine components, laser diameter monitoring ensures consistency, as dimensional variations can affect thermal stress distribution.

3.4 Final Heat Treatment (High-Temperature Optimization)

Unlike age-hardenable alloys, Inconel 617 wire undergoes stress-relief annealing to optimize its high-temperature performance:

Stress Relief: Heating the wire to 950 - 1000°C for 2 - 4 hours, followed by air cooling. This step reduces residual stresses from cold drawing, stabilizes the grain structure, and promotes uniform carbide distribution—enhancing creep resistance and thermal 

fatigue stability.

Oxide Layer Activation (Optional): For applications requiring immediate oxidation resistance (e.g., furnace heating elements), the wire is heated to 1050 - 1100°C in air for 1 hour. This forms a pre-conditioned chromium oxide layer, eliminating the need for "break-in" oxidation in service.

3.5 Surface Finishing & Quality Inspection

Surface Treatment:

Pickling: Post-annealing pickling in nitric acid to remove surface oxides and ensure clean adhesion of the protective chromium oxide layer.

Passivation (Optional): Chromate treatment for applications exposed to chloride-rich environments (e.g., marine turbines), further enhancing corrosion resistance.

Polishing: For precision applications (e.g., aerospace sensors), the wire is polished to a smooth surface finish (Ra ≤ 0.2 μm) to minimize heat-induced stress concentrations.

Quality Control:

Chemical Analysis: Optical emission spectroscopy (OES) to verify cobalt, molybdenum, and chromium content—critical for high-temperature performance.

Mechanical Testing: Tensile testing (strength/elongation at room and high temperatures), creep rupture testing (1000 hours at 900°C), and thermal fatigue testing (cycling 20 - 1000°C).

Corrosion/Oxidation Testing: Salt spray testing (ASTM B117) and high-temperature oxidation testing (1000°C in air) to validate oxide layer integrity.

Non-Destructive Testing: Eddy current testing (for surface defects like cracks) and ultrasonic testing (for internal flaws)—essential for turbine or reactor components.

Microstructural Analysis: Optical microscopy to confirm grain size (ASTM 5 - 7) and carbide distribution—key indicators of creep performance.

4. Product Applications

Inconel 617 wire’s exceptional ultra-high temperature strength, oxidation resistance, and creep stability make it indispensable in industries requiring performance beyond the capabilities of standard superalloys:

4.1 Advanced Energy Generation

Gas Turbines: Wire for turbine blade fasteners, combustion chamber liners, and hot-section springs—withstands 900 - 1100°C combustion gases and cyclic thermal stress, improving turbine efficiency (up to 60% thermal efficiency in advanced designs).

Nuclear Power (Generation IV Reactors): Wire for coolant circulation tubes and control rod components in high-temperature gas-cooled reactors (HTGRs)—resists 950 - 1000°C helium coolant corrosion and maintains structural integrity under radiation.

Concentrated Solar Power (CSP): Wire for heat absorber tubes and molten salt transport systems in next-generation CSP plants—withstands 1000°C molten salt (e.g., sodium chloride) corrosion and cyclic thermal loading.

4.2 Aerospace & Defense

Jet Engine Components: Fine wire (0.3 - 1.5 mm) for afterburner liners, exhaust nozzles, and turbine seal springs—resists 1000 - 1100°C exhaust gases and thermal cycling, extending engine service life.

Rocket Propulsion: Wire for rocket nozzle throats and fuel injector components—withstands short-term exposure to 1200°C combustion temperatures (e.g., liquid rocket engines using LOX/LNG propellants).

Hypersonic Vehicles: Wire for thermal protection system (TPS) fasteners—resists aerodynamic heating (up to 1100°C) during hypersonic flight (Mach 5+).

4.3 Industrial Heating & Metallurgy

High-Temperature Furnaces: Wire for heating elements and furnace hearth supports—operates at 900 - 1050°C in air or inert gas (e.g., argon) for heat treatment of superalloys or ceramics.

Molten Metal Handling: Wire for crucible supports and sensor sheaths in aluminum or steel casting—resists molten metal corrosion and 950 - 1000°C temperatures.

Waste Incineration: Wire for incinerator refractory anchors and flue gas sensor probes—resists 800 - 1000°C acidic flue gases (e.g., SO₂, HCl) and ash erosion.

4.4 Chemical & Petrochemical Industry

High-Temperature Reactors: Wire for catalyst support grids and reactor internals in steam cracking or reforming processes—withstands 850 - 950°C and resistance to hydrocarbon-induced coking.

Molten Salt Processing: Wire for agitator springs and heat exchanger tubes in molten salt electrolysis (e.g., aluminum production)—resists 900°C molten fluoride salts and electrochemical corrosion.

Conclusion

Alloy 617 (Inconel 617 Wire, UNS N06617) is a premier ultra-high temperature superalloy wire, distinguished by its exceptional creep resistance, oxidation stability, and performance up to 1100°C. Its unique chemistry and precise manufacturing process make it a critical material for advanced energy, aerospace, and industrial applications where standard alloys fail. Whether used in next-generation gas turbines, nuclear reactors, or hypersonic vehicles, Inconel 617 wire delivers reliable performance under extreme thermal stress. For custom requirements—such as ultra-fine wire (down to 0.1 mm diameter), specialized oxide layer treatments, or large-diameter wire (up to 12 mm) for structural components—manufacturers offer tailored solutions to meet the most demanding high-temperature challenges.

Packing of Standard Packing:

 Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Solutions are packaged in polypropylene, plastic or glass jars up to palletized 742 gallon liquid totes Special package is available on request.