Inconel 625 is a premium-grade nickel-based superalloy known for its exceptional combination of strength,
corrosion resistance, and thermal stability. This alloy is widely used in the manufacturing of
high-performance bolts, nuts, washers, and custom fasteners, especially in demanding industries such as
aerospace, marine, oil & gas, and chemical processing.
One of the key advantages of Inconel 625 is its excellent resistance to a wide range of corrosive environments. It performs exceptionally well in seawater, acidic conditions, and oxidizing or reducing atmospheres. This makes Inconel 625 fasteners ideal for offshore platforms, naval equipment, and chemical plants where reliability and longevity are crucial.
Inconel 625 offers outstanding mechanical properties, maintaining high tensile and yield strength across a wide temperature range—from cryogenic conditions up to 982°C (1800°F). Its superior fatigue strength and excellent stress-corrosion cracking resistance ensure dependable performance even under extreme thermal and mechanical loads.
The alloy’s unique blend of nickel, chromium, molybdenum, and niobium provides not only strength and corrosion resistance but also exceptional weldability and formability. Inconel 625 fasteners do not require post-weld heat treatment and retain their integrity after fabrication. Whether you need standard or custom-designed fasteners, Inconel 625 delivers unmatched durability and performance. Its properties make it the preferred choice for mission-critical applications where failure is not an option.
Contact us today to explore our full range of Inconel 625 bolts, nuts, and fasteners engineered for reliability in the toughest environments. Here is the refined chemical composition chart for Inconel 625 (UNS N06625) as per the ASTM B446 standard — specifically for rod, bar, and wire made from this alloy:
| Element | Composition (%) | Purpose |
|---|---|---|
| Nickel (Ni + Co) | ≥ 58.0 | Base metal; primary corrosion and heat resistance |
| Chromium (Cr) | 20.0 – 23.0 | Improves oxidation and corrosion resistance |
| Molybdenum (Mo) | 8.0 – 10.0 | Enhances strength, pitting, and crevice resistance |
| Niobium (Nb + Ta) | 3.15 – 4.15 | Solid solution strengthening and stability |
| Iron (Fe) | ≤ 5.0 | Residual element |
| Cobalt (Co) | ≤ 1.0 | (included in Ni + Co) Minor residual |
| Carbon (C) | ≤ 0.10 | Limits grain growth during heat treatment |
| Manganese (Mn) | ≤ 0.50 | Deoxidizer |
| Silicon (Si) | ≤ 0.50 | Aids in oxidation resistance |
| Phosphorus (P) | ≤ 0.015 | Impurity control |
| Sulfur (S) | ≤ 0.015 | Impurity control |
| Aluminum (Al) | ≤ 0.40 | Oxidation resistance, phase stability |
| Titanium (Ti) | ≤ 0.40 | Strengthens microstructure |
Standard Reference : ASTM B446 – Standard Specification for Nickel-Chromium-Molybdenum-Columbium Alloy (UNS N06625) Rod, Bar, and Wire.
| Property | Value | Unit | Description |
|---|---|---|---|
| Tensile Strength (min) | 827 | MPa (120 ksi) | Maximum stress the material can withstand when pulled |
| Yield Strength (0.2% offset, min) | 414 | MPa (60 ksi) | Stress at which the material begins to deform plastically |
| Elongation (min) | 30 | % | Ductility or stretch before fracture |
| Hardness (max) | 30 | HRC | Rockwell hardness, solution-annealed condition |
| Modulus of Elasticity | ~207 | GPa | Stiffness under elastic deformation |
| Density | 8.44 | g/cm³ | Mass per unit volume |
| Melting Point | 1290–1350 | °C | Solidus–liquidus range |
| Service Temperature Range | –253 to +980 | °C | Suitable operating temperature range |
Note : These values apply to material in the solution-annealed condition as specified in ASTM B446 for rods, bars, and wire.
| Standard / Organization | Designation / Grade | Description |
|---|---|---|
| UNS (Unified Numbering System) | N06625 | Official UNS number for Inconel 625 |
| ASTM | B443, B444, B446, B564, B366 | Various product forms (plate, pipe, bar, fittings, etc.) |
| ASME | SB-443, SB-444, SB-446, SB-564 | Equivalent to ASTM specifications |
| DIN / EN | 2.4856 | German/European standard number |
| ISO | ISO 15156-3 / NACE MR0175 | For use in H₂S environments in oil & gas |
| W.Nr. (Werkstoffnummer) | 2.4856 | European Werkstoff Number |
| Trade Name | Inconel® 625 (Special Metals) | Registered trademark by Special Metals Corp |
| AFNOR (France) | NC22DNb | French designation |
| BS (UK) | NA 21 | British Standard designation |
| AWS | A5.14 ERNiCrMo-3 | Welding filler metal classification |
| API | API 6A CRA, API 17D | Corrosion-resistant alloys in oilfield applications |
Note : While Inconel 625 is the commercial trade name, the alloy may appear under different designations depending on the product form and geographic region.
Inconel 625 exhibits exceptional heat-resistant properties, making it ideal for high-temperature applications. Its high nickel and chromium content ensures excellent oxidation resistance up to 980°C (1800°F). The addition of molybdenum and niobium enhances its thermal stability and strength under extreme heat and stress. Inconel 625 maintains structural integrity without scaling or deformation, even in fluctuating thermal conditions. This makes it suitable for aerospace, marine, and chemical processing industries. Unlike many stainless steels, Inconel 625 resists creep and stress-corrosion cracking at elevated temperatures, making it a preferred material for heat shields, exhaust systems, and high-temperature fasteners.
Inconel 625 is known for being a tough material to machine due to its high strength, work-hardening rate, and low thermal conductivity. During machining, it tends to harden rapidly, which can lead to tool wear and difficulty in maintaining tight tolerances. However, with proper tooling and techniques—such as using carbide or ceramic inserts, lower cutting speeds, and high-pressure coolant systems—its machinability can be effectively managed. Rigid setups and minimal tool engagement also help improve outcomes. Despite the challenges, Inconel 625 is widely machined for critical components in aerospace, marine, and energy sectors where corrosion and heat resistance are essential.
