Inconel 625 alloy excels in applications requiring extremely high corrosion resistance, particularly suitable for marine and chemical environments; while Inconel 718 alloy is ideal for applications demanding high strength and fatigue resistance at high temperatures, especially for aerospace and automotive engine components. Inconel 625 alloy possesses excellent oxidation resistance, making it ideal for underwater equipment; and Inconel 718 alloy, due to its higher hardness and strength, is better suited for high-stress components such as turbine blades and fasteners.
What are the advantages of Inconel 625?
Inconel 625 alloy is an ideal choice for seawater applications because it possesses the following characteristics: it is not prone to localized corrosion (pitting and crevice corrosion), has high corrosion fatigue strength, high tensile strength, and is resistant to chloride stress corrosion cracking.
Key Differences
The following table summarizes the main differences in composition, mechanical properties, and typical uses for inconel 625 vs inconel 718:
| Property/Parameter | Inconel 625 | Inconel 718 |
|---|---|---|
| Main Alloying Elements | Ni, Cr, Mo, Nb | Ni, Cr, Fe, Nb, Mo, Al, Ti |
| Tensile Strength (MPa) | 690–930 | 930–1530 |
| Yield Strength (MPa) | 276 (typical) | 827–1034 |
| Ductility (Elongation) | Up to 42.5% (more ductile) | Lower than Inconel 625 |
| Microhardness (HV) | 294 ± 10 HV0.2 | 513 ± 10 HV0.5 |
| Temperature Resistance | Maintains properties up to 980°C | Retains strength up to 700°C |
| Corrosion Resistance | Superior in chloride-rich and acidic media | Good oxidation resistance; less effective in chloride-rich or acidic environments |
| Heat Treatment | Solution treatment (solid solution strengthened) | Solution + Aging (precipitation hardened) |
| Density (g/cm³) | 8.44 | 8.19 |
| Melting Range (°C) | 1290 – 1350 | 1260 – 1336 |
| Typical Applications | Marine, chemical processing, subsea equipment | Aerospace engines, turbine blades, nuclear reactors |
Chemical Composition
Inconel 625
| Element | Percentage (Weight %) |
|---|---|
| Nickel | 58.0 min. |
| Chromium | 20.0 min. – 23.0 max. |
| Molybdenum | 8.0 min. – 10.0 max. |
| Niobium | 3.15 min. – 4.15 max. |
Inconel 718
| Element | Composition (%) |
|---|---|
| Nickel (Ni) | 50-55 |
| Chromium (Cr) | 17-21 |
| Iron (Fe) | 18.5 min (balance) |
| Niobium (Nb) | 4.75-5.50 |
| Molybdenum (Mo) | 2.80-3.30 |
| Titanium (Ti) | 0.65-1.15 |
| Aluminum (Al) | 0.20-0.80 |
| Cobalt (Co) | 1.00 max |
| Manganese (Mn) | 0.35 max |
| Silicon (Si) | 0.35 max |
| Copper (Cu) | 0.30 max |
Inconel 625 and 718: Industrial Applications
Inconel 625 and Inconel 718 are widely used in critical industries requiring high temperatures, high pressures, and corrosive media. Both alloys are produced in common manufacturing forms such as strip, flat, profiled wire, and round/flat/square wire, and are frequently used in stamped parts. Inconel 625's advantage lies in its higher chromium and molybdenum content, making it ideal for chemically corrosive and marine environments. Typical applications include flexible metal hoses, heat exchangers, manifolds, seawater-corrosive hardware, and subsea oil and gas equipment (return lines, umbilical cables, downhole tools). Its excellent oxidation resistance and processing flexibility make it ideal for environments ranging from cryogenic to high-temperature gases.
Inconel 718 is designed for enhanced precipitation-hardening strength and is widely used in high-temperature load-bearing components such as aerospace engines, turbomachinery, high-strength fasteners, and racing engine parts, particularly suitable for applications with extremely high requirements for fatigue, creep rupture, and high-temperature dimensional stability.
Aerospace: Inconel 718 is the primary material for high-temperature components and structural bolts in gas turbines; Inconel 625 is used in exhaust systems, piping, and engine peripheral components with extremely high corrosion requirements.
Automotive/Racing: 718 is used for high-load, high-temperature engine components; 625 is suitable for applications where formability and corrosion resistance are critical (e.g., exhaust systems and turbocharger piping).
Oil & Gas/Marine: 625 is the alloy of choice for underwater operations and marine environments (e.g., manifolds, risers, and hoses); 718 is used for high-stress connectors and downhole tools subjected to sustained high-temperature loads.
Why Choose Gnee Nickel Alloy (Supplier Example)?
✅ Large stock of Incoloy alloy tubes/bars/plates/fittings/coils, fast shipping.
✅ Factory direct sales, highly competitive prices, excellent value for money.
✅ Comprehensive quality assurance: Material Testing Certificate (MTC), chemical composition certificate, and mechanical property certificate.
✅ Value-added services: slitting, cutting, polishing, surface treatment.
✅ Worldwide shipping, secure and reliable packaging, and provision of export-required documents.
Email: ss@gneemetal.com
Gnee Steel is a supplier of Inconel 625/718 alloy, offering a wide range of products including: seamless pipe (sizes: 4-219 mm; thickness: 0.5-20 mm); welded pipe (sizes: 5.0-1219.2 mm; thickness: 0.5-20 mm); plates (thickness: 0.1 to 100 mm; width: 10-2500 mm); strips; alloy round bars (diameter: 3-800 mm); flat bars (thickness: 2-100 mm; width: 10-500 mm); hexagonal bars (size: 2-100 mm); wire rods; and extruded profiles. We collaborate with steel mills to provide our customers with Inconel 625/718 alloy products that meet or exceed numerous leading industry standards, including ASTM, ASME, SAE, AMS, ISO, DIN, EN, and BS standards.
Gnee Steel stocks and sells Inconel 625/718, pipes, plates, strips, round bars, flat bars, forged billets, hexagonal steel, wire rods, and extruded profiles. Please feel free to contact us at ss@gneesteel.com for a quote.
