Inconel 625
Properties & Applications
Mumbai · India
What Makes Inconel 625 Properties & Applications
Inconel 625 gets its strength from solid-solution strengthening, not precipitation hardening — molybdenum (roughly 9%) and niobium (roughly 3.6%) dissolve into the nickel-chromium matrix and distort it enough to resist dislocation movement, raising strength without requiring the aging heat treatment that grades like 718 and X-750 depend on. That single chemistry decision has a large practical consequence: 625 can be welded and used in the as-welded or annealed condition without post-weld heat treatment, which matters enormously in field fabrication and repair situations where a full heat-treat cycle simply isn’t practical.
The same molybdenum content that provides strength also drives 625’s corrosion resistance — molybdenum is particularly effective at resisting pitting and crevice corrosion in chloride environments, which is why 625 performs well in both sour gas service and seawater, two environments that attack most materials through fundamentally different mechanisms. Few other single alloys cover that combination as reliably, which is a large part of why 625 shows up so often in subsea and marine fastening despite its cost.
Akbar Fasteners Pvt. Ltd. exports to over 50 countries, and our Inconel 625 fastener range is manufactured with the same ISO 9001:2015 quality system and full mill test documentation as our 718, 600, and X-750 range.
Where 625 Genuinely Earns Its Cost
Broad-Spectrum Corrosion Resistance
Resists pitting, crevice corrosion, and general attack across sour gas, seawater, and many acid environments in a single alloy.
No Post-Weld Heat Treatment Needed
Solid-solution strengthening means welded joints don’t require the aging cycle precipitation-hardened grades depend on.
Good Strength Across a Wide Temperature Range
Retains useful mechanical properties from cryogenic conditions through to elevated temperatures approaching 980°C.
Well-Established Track Record
Decades of subsea, aerospace, and chemical processing service history back its selection for critical applications.
Inconel 625 Detailed Properties
UNS N06625 Alloying Elements
- Nickel 58.0% min
- Chromium 20.0 – 23.0%
- Molybdenum 8.0 – 10.0%
- Niobium + Tantalum 3.15 – 4.15%
- Iron (max) 5.0%
Annealed Condition (Typical)
- Tensile Strength 827–1035 MPa
- Yield Strength 414–585 MPa
- Elongation 30–50%
- Hardness ~190–240 HB
- Testing MTC / NABL on request
Density & Thermal Behaviour
- Density ~8.44 g/cm³
- Melting Range ~1290–1350°C
- Max Service Temp ~980°C (short-term)
- Magnetic Behaviour Non-magnetic
- Thermal Expansion Low relative to steel
Inconel 625 vs Incoloy 825 vs Hastelloy C-276
625 is often compared against two other corrosion-resistant nickel alloys solving overlapping but not identical problems. The comparison below is the one we walk through with buyers before quoting, so the grade actually matches the corrosion mechanism at play rather than a generic “nickel alloy” request.
| Property | Inconel 625 | Incoloy 825 | Hastelloy C-276 |
|---|---|---|---|
| UNS Designation | N06625 | N08825 | N10276 |
| Base Chemistry | Ni-Cr, Mo+Nb solid-solution | Ni-Fe-Cr, Cu+Mo added | Ni-Mo-Cr, high Mo content |
| Best Suited For | Sour gas, seawater, broad-spectrum | Cost-effective sour service, sulfuric acid | Most severe reducing/oxidizing acids |
| Max Service Temp | ~980°C | ~550°C | ~1090°C |
| Relative Strength | High | Moderate | Moderate-High |
| Relative Cost | High | Moderate | Highest |
Inconel 625 Applications in Detail
Subsea & Offshore Oil & Gas
Subsea wellhead, flowline, and umbilical fastening exposed simultaneously to sour gas and seawater — the exact combination 625 was built to resist.
Marine & Shipbuilding
Seawater-exposed hardware, propeller and shaft-related fastening, and marine piping joints requiring long-term chloride resistance.
Aerospace Exhaust Systems
Ducting, exhaust liner, and thrust reverser fastening exposed to high-temperature oxidizing exhaust gas.
Chemical & Pollution Control
Flue gas desulfurization and scrubber fastening exposed to a shifting mix of acidic and chloride-bearing process streams.
Nuclear Waste Processing
High-integrity fastening for equipment handling corrosive nuclear waste streams requiring long-term reliability.
Pulp & Paper Bleaching
Bleach plant equipment fastening exposed to chlorine dioxide and other aggressive bleaching agents.
Inconel 625 Product Range
Inconel 625 Hex Bolts
Corrosion-resistant hex bolts for subsea, marine, and chemical processing fastening.
Inconel 625 Nuts
Matching hex and heavy hex nuts manufactured to pair correctly with 625 bolts and studs.
Inconel 625 Stud Bolts
Stud bolts for flanged subsea, marine, and chemical process piping joints.
Inconel 625 Washers
Matching washers manufactured to the same chemistry for complete corrosion-consistent assemblies.
Standard Export Documentation
Prepared as standard practice for every Inconel 625 fastener shipment.
Mill Test Certificate (MTC)
Heat number, chemical composition, and mechanical property verification for every lot.
Certificate of Conformance
Confirms the shipment matches the purchase order specification and grade in full.
Certificate of Origin (COO)
Confirms India as country of manufacture for destination customs purposes.
Commercial Invoice & Packing List
Itemized value, Incoterm, and detailed carton/weight breakdown for customs clearance.
NABL Accredited Test Reports
Independent mechanical and chemical testing available on request for critical applications.
Bill of Lading
Ocean or air freight shipping document confirming carrier, mode, and consignee details.
Internationally Recognised Standards Coverage
Related Fastener Grades & Materials
Different Types of Inconel Fasteners
A detailed grade-by-grade comparison for choosing between all four Inconel grades.
View Inconel Grades →Uses & Specifications of Inconel Fasteners
A practical guide to applications and what to specify when ordering.
View Uses & Specifications →Hastelloy B-3 Stud Bolts
Our established nickel-molybdenum alloy fastening line for severe reducing acid service.
View Hastelloy B-3 →Different Types of Monel Fasteners
Nickel-copper grades for seawater and hydrofluoric acid service.
View Monel Grades →Sour Gas, Seawater,
or Both at Once?
Tell us the environment and temperature — we’ll confirm whether Inconel 625 or an alternative grade is the right fit for your application. Akbar Fasteners Pvt. Ltd. responds within 24 hours.
Sales: +91 724 0000 733 · Support: +91 800 9315 333 · sales@akbarfasteners.in