Inconel 718 (UNS N07718)

Inconel 718 (also specified as UNS N07718 / Werkstoff No. 2.4668 / NCF 718) is a precipitation-hardening nickel-iron-chromium superalloy strengthened by niobium and molybdenum. It combines very high yield, tensile and creep-rupture strength up to about 650 °C with excellent weldability (including resistance to post-weld strain-age cracking) and good corrosion resistance, making it one of the most widely used aerospace and power-generation superalloys.

Overview

• Category: Precipitation-hardening (PH) nickel-based superalloy (Ni-Fe-Cr-Nb-Mo)
• Standards: ASTM B637, AMS 5662, AMS 5663, AMS 5664, UNS N07718, DIN/EN 2.4668, JIS NCF 718
• Available forms: Round bar / rod, plate, sheet, pipe & tube, wire, forgings, and custom profiles to order

Chemical Composition (wt%)

Physical Properties

Mechanical Properties (typical, double-aged)

Fabrication & Welding

• Hot working: 980–1160 °C, followed by suitable heat treatment to relieve stresses and refine microstructure.
• Cold working: Good cold-formability (cold forming, cold drawing), but with a relatively strong work-hardening tendency.
• Welding: Good weldability by GTAW (TIG), electron-beam welding and laser welding. Clean the surface before welding; post-weld ageing heat treatment is recommended.

Heat Treatment

• Solution treatment: Heat to 950–1050 °C and cool rapidly, to fully dissolve alloying elements into the matrix and obtain a uniform austenitic structure.
• Double-ageing: Hold at 720 °C for 8 hours, furnace-cool to 620 °C, hold for a further 8 hours, then air-cool. Precipitation of gamma-prime / double-gamma-prime strengthening phases delivers final high strength and hardness.

Key Features

• High strength below 650 °C, with excellent yield strength, tensile strength and fatigue performance;
• Good corrosion resistance in a wide range of environments;
• Good high-temperature oxidation resistance;
• Readily fabricated by hot working, cold working and welding into complex components;
• Welds retain high strength and corrosion resistance.

Corrosion Resistance

• Good resistance to atmospheric, fresh-water and marine environments;
• Resists a range of chemical media including nitric, sulfuric and hydrochloric acids to a limited extent;
• Particularly good performance in neutral and mildly alkaline conditions;
• Good resistance to pitting and crevice corrosion.

Typical Applications

• Aerospace: high-temperature engine components such as turbine discs, blades and combustors;
• Power generation: gas-turbine components and nuclear-reactor internals;
• Automotive: critical components of high-performance engines;
• Petrochemical: piping, valves and reaction vessels for high-temperature, high-pressure, corrosive service.

For detailed datasheets, mill certificates (EN 10204 3.1) or inquiries on specific sizes and tolerances, please contact our sales & engineering team.