Inconel 625 Chemical Composition, Mechanical Properties & ASTM B446
Primary Focus Keyword: Inconel 625 Chemical Composition
Secondary Focus Keywords:
- Inconel 625 Technical Properties
- Inconel 625 Mechanical Properties
- Inconel 625 UNS N06625
- Inconel 625 ASTM B446
- Alloy 625 Chemical Composition
- UNS N06625 Round Bar
- Inconel 625 Material
- 2.4856 Nickel Alloy
- NiCr22Mo9Nb
- Inconel 625 Round Bar Supplier India
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Table of Contents
- What Makes Inconel 625 a High-Performance Alloy?
- Inconel 625 Chemical Composition
- Role of Major Alloying Elements
- Inconel 625 Mechanical Properties
- Physical Properties of Inconel 625
- Inconel 625 and ASTM B446
- Heat Treatment Conditions
- Why Inconel 625 Resists Corrosion
- International Material Designations
- Where Inconel 625 Technical Properties Matter
- What Buyers Should Check Before Ordering
- Why Source Inconel 625 from Manan Steel & Metals?
- Frequently Asked Questions
- Conclusion
What Makes Inconel 625 a High-Performance Alloy?
Inconel 625 is a nickel-based alloy developed for applications where strength, corrosion resistance and dependable performance in demanding environments are required.
The material is internationally identified as UNS N06625, Alloy 625 and Werkstoff Number 2.4856. Its EN designation is commonly given as NiCr22Mo9Nb.
Unlike a conventional steel grade, Inconel 625 derives much of its performance from its nickel-chromium-molybdenum composition with niobium.
The combination makes the alloy useful for chemical processing, marine engineering, oil and gas equipment, pollution-control systems and other industrial applications where corrosion and mechanical loading are significant concerns.
For engineers and procurement teams, understanding the Inconel 625 chemical composition is important because the alloying elements directly influence its corrosion resistance, strength and service performance.
Inconel 625 Chemical Composition
The following values represent the limiting composition published for Inconel alloy 625 by Special Metals. Actual purchase material should always be checked against the applicable material certificate and purchasing specification.
| Element | Composition, % |
|---|---|
| Nickel (Ni) | 58.0 min |
| Chromium (Cr) | 20.0–23.0 |
| Molybdenum (Mo) | 8.0–10.0 |
| Niobium + Tantalum (Nb + Ta) | 3.15–4.15 |
| Iron (Fe) | 5.0 max |
| Carbon (C) | 0.10 max |
| Manganese (Mn) | 0.50 max |
| Silicon (Si) | 0.50 max |
| Phosphorus (P) | 0.015 max |
| Sulfur (S) | 0.015 max |
| Aluminium (Al) | 0.40 max |
| Titanium (Ti) | 0.40 max |
| Cobalt (Co) | 1.0 max |
The nickel content forms the base of the alloy, while chromium, molybdenum and niobium contribute significantly to its overall performance.
Role of Major Alloying Elements
Nickel
Nickel is the primary element in Inconel 625. Its high nickel content contributes to the alloy’s resistance to many corrosive environments and supports its performance at elevated temperatures.
Chromium
Chromium contributes to corrosion and oxidation resistance. The approximately 20–23% chromium content is an important part of the alloy’s ability to withstand aggressive service environments.
Molybdenum
Molybdenum improves resistance to localized corrosion, particularly pitting and crevice corrosion. This is especially relevant in chloride-containing environments.
Niobium
Niobium works with molybdenum to strengthen the alloy matrix. Special Metals notes that the molybdenum and niobium additions allow Inconel 625 to achieve high strength without requiring a precipitation-hardening treatment.
This combination is one of the important characteristics separating Inconel 625 from many conventional nickel alloys.
Inconel 625 Mechanical Properties
Mechanical properties can vary depending on product form, processing history and heat-treatment condition. Therefore, buyers should always specify the applicable standard and condition rather than relying only on generic material values.
For example, voestalpine publishes solution-annealed values for Alloy 625 including:
| Property | Typical/Specified Value |
|---|---|
| Tensile Strength | ≥ 760 MPa |
| Yield Strength, Rp0.2 | ≥ 380 MPa |
| Elongation A5 | ≥ 35% |
These values are associated with the particular solution-annealed condition and specification presented by voestalpine, so they should not automatically be treated as universal values for every Inconel 625 product.
This distinction is important when purchasing UNS N06625 round bar, because mechanical requirements can depend on the applicable ASTM specification and heat-treatment condition.
Physical Properties of Inconel 625
Published technical data for Alloy 625 includes the following physical properties:
| Property | Value |
|---|---|
| Density | Approximately 8.44 g/cm³ |
| Melting range | Approximately 1290–1350°C |
| Thermal conductivity at 20°C | Approximately 9.8 W/(m·K) |
| Electrical resistivity | Approximately 1.25 Ω·mm²/m |
| Thermal expansion, 20–100°C | Approximately 12.5 × 10⁻⁶/K |
These values are useful during engineering calculations involving weight, thermal behaviour and component design.
Inconel 625 and ASTM B446
For Inconel 625 Round Bar and Rod, one of the most important standards to understand is ASTM B446.
ASTM B446 covers nickel-chromium-molybdenum-niobium alloy UNS N06625 in hot-worked and cold-worked rod and bar forms, along with other alloys covered by the specification.
The current ASTM B446-26 specification addresses requirements including:
- Chemical composition
- Heat treatment
- Tensile strength
- Yield strength
- Elongation
- Dimensions
- Straightness
- Product condition
For procurement, the ASTM designation should therefore be treated as part of the material specification rather than simply as a marketing term.
ASTM B446:
https://store.astm.org/b0446-26.html
Special Metals Inconel 625 Technical Bulletin:
https://www.specialmetals.com/documents/technical-bulletins/inconel/inconel-alloy-625.pdf
Heat Treatment Conditions
ASTM B446 identifies different heat-treated conditions for UNS N06625 products.
The current ASTM B446-26 description identifies:
Grade 1 – Annealed
Grade 1 material is normally employed for service temperatures up to 1100°F (593°C).
Grade 2 – Solution Annealed
Grade 2 material is normally intended for service temperatures above 1100°F (593°C) when creep and rupture resistance are required.
This distinction matters during procurement because two products identified as UNS N06625 may have different requirements depending on their intended service condition.
The buyer should therefore communicate:
Material + product form + applicable standard + condition + dimensions + quantity.
Why Inconel 625 Resists Corrosion
One of the strongest characteristics of Inconel 625 is its resistance to a wide range of corrosive environments.
The alloy’s chemistry provides resistance to several forms of corrosion, including:
- Pitting corrosion
- Crevice corrosion
- Chloride-ion stress-corrosion cracking
- General corrosion in many aggressive environments
- Oxidation at elevated temperatures
Special Metals specifically identifies Inconel 625 as having excellent resistance to pitting and crevice corrosion and describes its suitability for demanding marine and chemical environments.
This is why the alloy is frequently considered when ordinary metals may not provide the required combination of corrosion resistance and mechanical performance.
International Material Designations
Industrial buyers may encounter different names for the same material depending on the country, specification or supplier.
| Designation | Identification |
|---|---|
| Inconel 625 | Commercial alloy name |
| Alloy 625 | Generic alloy designation |
| UNS N06625 | UNS designation |
| 2.4856 | Werkstoff number |
| NiCr22Mo9Nb | EN designation |
| ISO NW6625 | ISO designation |
voestalpine also identifies Alloy 625 as 2.4856 / NiCr22Mo9Nb / UNS N06625.
Knowing these alternate designations can help procurement teams avoid confusion when sourcing internationally.
Where Inconel 625 Technical Properties Matter
The combination of strength and corrosion resistance makes Inconel 625 suitable for demanding applications.
Common application areas include:
Oil & Gas
The material can be used for components exposed to corrosive fluids, pressure and demanding operating conditions.
Chemical Processing
Its resistance to aggressive chemical environments makes it suitable for selected chemical-processing equipment.
Marine Engineering
Chloride-containing environments can be highly aggressive toward engineering materials. Inconel 625’s resistance to pitting, crevice corrosion and chloride-related stress corrosion is particularly relevant here.
Pollution-Control Equipment
The alloy is also used in pollution-control applications where corrosive process conditions can occur.
Aerospace and High-Temperature Equipment
Inconel 625 is available in several product forms and is used in demanding aerospace and elevated-temperature applications.
What Buyers Should Check Before Ordering
Purchasing a specialty nickel alloy requires more than specifying only the alloy name.
Before ordering Inconel 625 Round Bar, confirm:
1. Material Designation
Specify Inconel 625 / UNS N06625 clearly.
2. Product Form
State whether you require:
- Round bar
- Rod
- Wire
- Plate
- Sheet
- Pipe
- Tube
- Forged component
3. Applicable Standard
For round bar or rod, ASTM B446 may be applicable depending on the requirement.
4. Dimensions
Mention:
- Diameter
- Length
- Required tolerance
- Finish
5. Heat-Treatment Condition
State the required condition where applicable, especially when ASTM B446 requirements are part of the purchase specification.
6. Material Test Certificate
For industrial applications, buyers may require an MTC confirming chemical composition and applicable mechanical or dimensional requirements.
7. Quantity
Mention the required quantity or approximate weight so the supplier can check commercial availability and prepare an appropriate quotation.
Why Source Inconel 625 from Manan Steel & Metals?
Manan Steel & Metals supplies specialty metals and industrial alloy products from Mumbai, India.
The company’s published product information includes Inconel 625, including round-bar requirements, and its nickel-alloy listing identifies ASTM/ASME SB446 UNS 6625 as Inconel 625.
For a quotation, buyers can share:
- Inconel 625 / UNS N06625
- Required diameter
- Length
- Quantity
- Finish
- ASTM or other applicable specification
- Required material condition
- MTC/documentation requirements
- Delivery location
Related Manan Steel & Metals Resources
Inconel 625 Round Bar:
https://manansteel.com/inconel-625-round-bar-supplier-india/
Inconel Round Bar:
https://manansteel.com/inconel-round-bar-manufacturer-india/
Round Bar Products:
https://manansteel.com/round-bar-manufacturer-supplier/
Manan Steel & Metals:
https://www.manansteel.com/
For technical reference, buyers can also review the official Special Metals Inconel 625 Technical Bulletin and the ASTM B446 specification.
Frequently Asked Questions
What is the chemical composition of Inconel 625?
Inconel 625 is primarily nickel-based, with chromium, molybdenum and niobium as major alloying elements. Special Metals specifies nickel at 58% minimum, chromium at 20–23%, molybdenum at 8–10% and niobium plus tantalum at 3.15–4.15%.
What is the UNS number of Inconel 625?
The UNS designation of Inconel 625 is UNS N06625. Its Werkstoff number is 2.4856.
What is the EN designation of Inconel 625?
A commonly used EN designation is NiCr22Mo9Nb.
What is ASTM B446?
ASTM B446 is a specification covering nickel-chromium-molybdenum-niobium alloy UNS N06625 in rod and bar forms, among other alloys covered by the standard. It specifies requirements related to chemistry, heat treatment, mechanical properties and dimensions.
Is Inconel 625 suitable for marine environments?
Inconel 625 is used in marine engineering because of its resistance to corrosion, including pitting, crevice corrosion and chloride-ion stress-corrosion cracking.
Is Inconel 625 available as round bar?
Yes. Inconel 625 is available in round bar and rod forms, with ASTM B446 among the relevant specifications for rod and bar.
What information should I send when requesting an Inconel 625 quotation?
Provide the material designation, diameter, length, quantity, finish, applicable standard, heat-treatment condition and documentation requirements. This helps the supplier review the requirement accurately before quotation.
Conclusion
Understanding the Inconel 625 chemical composition is essential for engineers, buyers and procurement teams selecting this material for demanding industrial applications.
Its nickel-chromium-molybdenum-niobium chemistry provides a combination of corrosion resistance and mechanical performance that has made Alloy 625 / UNS N06625 / 2.4856 an established engineering alloy.
For round bar requirements, ASTM B446 provides an important specification framework covering chemistry, heat treatment, mechanical requirements and dimensions.
If you are sourcing Inconel 625 Round Bar in India, send your required diameter, length, quantity, specification and delivery location to Manan Steel & Metals for an industrial quotation.
Enquire for Inconel 625
Manan Steel & Metals
Shop No. 2, Hira Building,
97 Khetwadi Main Road (Nanubhai Desai Road),
Girgaon, Mumbai – 400004, Maharashtra, India
Phone: +91 7977369869
Email: manansteel@gmail.com
Website: https://www.manansteel.com/
Share your Inconel 625 requirement today for availability and quotation.
Authoritative Technical References
- ASTM International – ASTM B446-26
https://store.astm.org/b0446-26.html - Special Metals – INCONEL Alloy 625 Technical Bulletin
https://www.specialmetals.com/documents/technical-bulletins/inconel/inconel-alloy-625.pdf - voestalpine Specialty Metals – Alloy 625 / UNS N06625 / 2.4856
https://www.voestalpine.com/specialtymetals/eu/en/alloy-625-uns-n06625-2-4856/