Inconel Alloy 625 Vs Inconel Alloy 718

For industries like aerospace, automotive, oil & gas, materials must withstand extreme heat, pressure & corrosive environments. Nickel-based superalloys, specifically Inconel 625 and Inconel 718, are critical for these demanding applications. Both Inconel alloys are renowned for their superior high-temperature strength and corrosion resistance. To ensure optimal performance and project success, a detailed comparison and understanding of the key differences between Inconel 625 and Inconel 718 are essential. Discover which superalloy best suits your engineering needs.

This guide will compare the composition, mechanical propertie & ideal applications for each alloy, helping you make an informed decision. For a more detailed information on these alloys look at the comprehensive guide on Inconel Material Properties & Grades

Inconel 625 vs. Inconel 718: A Quick Comparison

Inconel 625 and Inconel 718 are distinct superalloys designed to solve specific engineering challenges.

• Inconel 625 is a nickel-chromium alloy with significant additions of molybdenum and niobium. This unique composition makes it a champion of corrosion resistance. It provides exceptional protection against pitting and crevice corrosion, making it the ideal choice for chemically aggressive environments, including those with chlorides and acids. It also offers reliable performance from cryogenic temperatures up to 2,000°F (1,093°C), with excellent oxidation resistance at high heat. The fabrication versatility and superior corrosion resistance of Inconel 625 make it a top choice for a wide range of applications.
• Inconel 718 is engineered for superior mechanical strength. It is a precipitation-hardenable alloy, which means its strength can be significantly increased through a specific heat treatment process. This results in markedly higher yield and tensile strength, along with excellent fatigue and creep-rupture performance. Inconel 718 is at its best in the medium high-temperature range, typically applied around 1,300°F (704°C). It also boasts good weldability, which is crucial for complex, load-bearing parts.

Choose Inconel 625 when your primary concern is corrosion resistance and fabrication ease across a wide temperature spectrum.

Choose Inconel 718 when the design is driven by mechanical strength under load, such as high yield strength, fatigue, and creep resistance at elevated temperatures.

Inconel 625 vs 718: Industrial Applications 

Inconel 625 and Inconel 718 are deployed across critical industries where high temperature, pressure & corrosive media is needed. Both alloys are produced in common manufacturing forms strip, ribbon, shaped wire & round/flat/square wire and are routinely used for stamped parts. Where Inconel 625 shines with higher chromium and molybdenum, Inconel 625 is the go-to for chemically aggressive and marine environments. Typical components include flexible metal hoses, heat exchangers, header bars, seawater-exposed hardware, and subsea oil & gas equipment (tiebacks, umbilicals, downhole tools). Its blend of oxidation resistance and fabrication versatility makes it ideal from cryogenic service up to very hot gas exposure.

Designed for precipitation-hardened strength, Inconel 718 dominates load-bearing hot-section parts aerospace engines, turbomachinery, high-strength fasteners, and motorsport engine components where fatigue, creep-rupture, and dimensional stability at elevated temperatures are the primary constraints.

• Aerospace: Inconel 718 is a mainstay in gas turbine hot sections and structural bolting; Inconel 625 supports exhausts, ducting, and corrosion-critical engine peripherals.
• Automotive/motorsport: 718 for high-load, high-heat engine parts; 625 where formability and corrosion margin are essential (exhaust, turbo plumbing).
• Oil & gas / Marine: 625 is the preferred alloy for subsea service and seawater exposure (manifolds, risers, flexible hoses); 718 appears in high-stress connectors and downhole tools that see sustained load at heat.

Product Forms For Inconel 625 & 718

Both Inconel 625 and Inconel 718 are highly formable and weldable, so they’re stocked in multiple product forms for fast specification.

Inconel 718 Product Forms

• Round Bar / Wire:Inconel 718 Round Bars & Wires
• Sheet & Plate:Inconel 718 Plates & Sheets
• Welding Wire:Inconel 718 Filler Wire

More types of 718 for high-load assemblies:Seamless Pipes & Tubes,Flanges,Forged Fittings,Buttweld Fittings,Compression Tube Fittings,Long Radius Bends,Pipe Spools,Olets,Shims,Wire Mesh,Perforated Sheets.

Conclusion

For deeper context on chemistries, heat-treatment windows, and mechanical benchmarks across the series, see our foundational guide Inconel Material Properties & Grades.The team at Kalpataru Piping pairs application-driven guidance with a full range of Inconel 625 and Inconel 718 product forms to help you specify the right grade, optimize processing, and deliver reliable parts for demanding service.

Frequently Asked Questions About Inconel 625 vs Inconel 718