Alloy 625 - AMS 5599, AMS 5666, UNS N06625
Inconel® 625 (AMS 5599, UNS N06625) is a nickel-based superalloy with excellent resistance to oxidation and corrosion. The nickel-chromium matrix of this material is reinforced by the addition of molybdenum and niobium, which is alloyed through solid solution strengthening. This process allows alloy Inconel® 625 to maintain high strength and toughness at temperatures ranging from cryogenic up to 1800°F (982°C). It is non-magnetic, austenitic, and displays high tensile strength, fabricability, and brazeability. Due to its high nickel content, this alloy is nearly immune to chloride ion stress-corrosion cracking and pitti.
Characteristics of Alloy 625
Thanks to its high nickel content, Alloy 625 is virtually immune to chloride-induced stress corrosion cracking, making it ideal for use in marine, offshore, chemical, and high-temperature applications. The addition of niobium enhances strength through solid-solution hardening, eliminating the need for post-weld heat treatment.offering enhanced fatigue resistance and deep drawing capabilities.
Resistant to pitting, crevice corrosion, and intergranular attack.
- Excellent mechanical performance at temperatures up to 980°C (1800°F)
- Outstanding weldability, even after extended service exposure
- Available in sheet, plate, pipe, bar, wire, and custom forms
- Suitable for both high-strength and corrosion-critical environments
Chemical Data, Mechanical Properties and Specifications for Nickel Alloy 625
Chemical composition
| Composition | ASTM B446 UNS N06625 % |
| Nickel | 58.00 min |
| Molybdenum | 8.00 - 10.00 |
| Sulfur | 0.015 max |
| Silicon | 0.50 max |
| Chromium | 20.00 - 23.00 |
| Niobium + Tantalum | 3.15 - 4.15 |
| Titanium | 0.40 max |
| Aluminum | 0.40 max |
| Iron | 5.0 max |
| Manganese | 0.50 max |
| Carbon | 0.10 max |
| Phosphorus | 0.015 max |
Mechanical & Physical Properties
| Mechanical & Physical Properties | 21°C | 204 °C | 316 °C | 427 °C | 538 °C | 649 °C | 760 °C | 871 °C |
| Ultimate Tensile Strength /Mpa | 992.9 | 923.9 | 910.1 | 910.1 | 896.3 | 820.5 | 537.8 | 275.8 |
| 0.2% Yield Strength /MPa | 579.2 | 455.1 | 434.4 | 420.6 | 420.6 | 413.7 | 406.8 | 268.9 |
| Elongation % | 44 | 45 | 42.5 | 45 | 48 | 34 | 59 | 117 |
| Coefficient of Thermal Expansion µm/m⁰C | - | 13.1 | 13.3 | 13.7 | 14 | 14.8 | 15.3 | 15.8 |
| Thermal Conductivity /kcal/(hr.m.°C) | 8.5 | 10.7 | 12.2 | 13.5 | 15 | 16.4 | 17.9 | 19.6 |
| Modulus of Elasticity/ MPa | 2.07 | 1.93 | 1.93 | 1.86 | 1.79 | 1.65 | 1.59 | - |
Product Specifications
We stock Alloy 625 in a variety of product forms to suit different applications and fabrication methods, including flanges, seamless pipe, pipe fittings, plate, round bar, round tube, sheet, medium-thick plate.
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inconel 625 vs inconel 718
Composition
The first major difference between Inconel Alloy 625 vs 718 is their chemical composition. Both are nickel alloys, but each contains different amounts of a variety of chemicals which distinguish them.
Alloy 625 is primarily nickel-based, whilst Alloy 718 is nickel + cobalt (Ni+Co) based. The use of nickel + cobalt in Alloy 718 means that it has greater hardness and strength. Alloy 625, on the other hand, has higher levels of chromium and molybdenum, so it is more corrosion-resistant.
Properties
Inconel 625 and Inconel 718 share a number of common properties. Like most nickel alloys, both are high in strength, easily weldable and corrosion-resistant.
However, the different chemical compositions of both alloys mean that they display differing levels of these properties. Whilst both alloys are heat resistant, Alloy 718 has a higher melting range of 1321-1393°C. Similarly, whilst both demonstrate good corrosion resistance, the higher levels of chromium and molybdenum make Alloy 625 more corrosion resistant.
Contact our professionals to recommend the right alloy for your project
Applications of Alloy 625
Alloy 625 is trusted across industries for its exceptional resistance to corrosion, heat, and mechanical stress, making it ideal for critical components in challenging environments.
Chemical Processing Industry
- Reactors & Vessels – Withstands aggressive acids and chlorides
- Piping & Heat Exchangers – Delivers long-term corrosion resistance
- Furnace Parts – Performs under intense thermal cycling
Aerospace & Defense
- Exhaust Ducts & Engine Components – Withstands high-temp oxidation
- Turbine Shrouds & Bellows – High strength and fatigue resistance
- Thrust Reversers – Excellent formability and weldability
Marine & Offshore
- Subsea Piping & Risers – Corrosion-resistant in high-pressure seawater
- Splash Zone Components – Withstands chloride-induced stress cracking
- Weld Overlays – Protects against seawater degradation
Why Choose Gnee as Your Nickel-Based Alloy Supplier?
✅️Factory Direct Pricing: Cut out middleman costs of 15–20% typically added by trading companies, and enjoy genuine wholesale prices ideal for large vessel maintenance and overhaul projects
✅️Full MTC 3.1 & 3.2 Traceability: We provide complete EN 10204 certification documents, with clear records of PREN values and high-temperature mechanical properties for full material traceability.
✅️Large-Scale Wholesale Inventory: Massive stock of 0.5mm to 10mm sheets ready for Fast Global Shipping.
✅️AS9100 & ISO 9001 Certified: All products are produced in strict compliance with the world's highest international quality management systems.
FAQ
What is the delivery condition of Inconel 625?
Standard supply: Solution Annealed, pickled surface. ASTM B444 defines Grade1 (annealed, ≤593℃ service) and Grade2 (solution annealed, high-temperature creep application). Please confirm grade before order.
Is Inconel 625 hard to machine?
Inconel is ideal for high-temperature applications requiring extreme resistance to harsh environments. Known for its difficult machinability, Inconel is an expensive metal for component fabrication.
Can Inconel be welded?
Yes, you can weld Inconel, and it is commonly done using TIG (GTAW), MIG (GMAW), and Stick (SMAW) methods.
Does Inconel 625 rust?
No, Inconel 625 will not develop typical red iron rust (ferrous oxide rust) under nearly all normal service conditions.
