Inconel® 718

AMS 5662 · AMS 5663 · ASTM B637 · ASME SB-637

A precipitation-hardened nickel-chromium superalloy engineered for extreme service environments — delivering outstanding strength, oxidation resistance, and dimensional stability from cryogenic temperatures to 1,300 °F (704 °C).

Density0.296 lb/in³

Max service temp.1,300 °F / 704 °C

Melting range2,300 – 2,437 °F

Primary standardAMS 5662 / 5663

Overview

Inconel 718 is the most widely used nickel-based superalloy in the world, accounting for roughly one-third of all superalloy production by weight. Its exceptional combination of high-temperature strength, corrosion resistance, and superior weldability without post-weld cracking has made it the material of choice for the most demanding aerospace, energy, and industrial applications.

Strengthened primarily by the precipitation of gamma double-prime (γ″) and gamma-prime (γ′) phases during heat treatment, Inconel 718 maintains outstanding tensile and fatigue properties even in the demanding thermal cycles and aggressive chemical environments where conventional stainless steels and titanium alloys cannot perform.

Two aerospace material specifications govern the supply of bar, billet, and rod product forms: AMS 5662 (solution annealed condition) and AMS 5663 (precipitation heat treated, higher-strength condition). Understanding the distinction is essential for selecting the correct certification for your application.

Nominal chemistry

The balanced chemistry of Inconel 718 is what enables its versatile performance. Niobium and molybdenum provide solid solution strengthening, while chromium and nickel together deliver outstanding oxidation and corrosion resistance across a wide temperature range.

ElementNominal / Range (wt%)RoleRelative content

Nickel (Ni)50.0 – 55.0Austenitic matrix, corrosion resistance

Chromium (Cr)17.0 – 21.0Oxidation & hot corrosion resistance

Iron (Fe)Balance (~19%)Matrix filler, cost optimization

Niobium (Nb)4.75 – 5.50Primary γ″ strengthening phase

Molybdenum (Mo)2.80 – 3.30Solid solution strengthening

Titanium (Ti)0.65 – 1.15γ′ precipitation strengthening

Aluminum (Al)0.20 – 0.80γ′ formation, oxidation resistance

Cobalt (Co)≤ 1.00Incidental; matrix stabilizer

Carbon (C)≤ 0.08Controlled for weldability

Specification Details

AMS 5662 vs. AMS 5663

Both specifications govern bar, billet, and rod forms of Inconel 718. The critical difference lies in heat treatment condition and, consequently, mechanical property requirements. Selecting the wrong specification can result in non-conforming parts or unnecessary machining difficulty.

AMS 5662

Solution Annealed

Material is solution heat treated at approximately 1,700–1,850 °F (927–1,010 °C) and rapidly quenched. The alloy is in its softest, most workable state — ideal for further machining, forming, or welding prior to final heat treatment by the end user.

• ConditionSolution annealed (SHT)

• UTS (min)150 ksi (1,034 MPa)

• 0.2% Yield (min)120 ksi (827 MPa)

• Elongation (min)30%

• Hardness (max)363 HBW / 38 HRC

• Best forMachining, forming, welded fabrications

AMS 5663

Precipitation Hardened

Material is solution treated and then double-aged (typically 1,325 °F / 8 hr + 1,150 °F / 8 hr per AMS 2774). The precipitation hardening cycle develops the peak γ″ strengthening phase, yielding significantly higher strength — delivered ready for service or near-net machining.

• ConditionSolution + precipitation aged

• UTS (min)185 ksi (1,276 MPa)

• 0.2% Yield (min)150 ksi (1,034 MPa)

• Elongation (min)12%

• Hardness331–444 HBW / 36–47 HRC

• Best forFinal components, high-load aerospace hardware

Where Inconel 718 is specified

AMS 5662 and AMS 5663 are found in the most critical, load-bearing components across aerospace, defense, oil and gas, and power generation — wherever failure is not an option.

Jet Engine Turbines

Turbine discs, rings, shafts, and seal components operating in high-pressure, high-temperature gas paths — one of the largest single use segments.

Airframe Fasteners & Structures

High-strength bolts, studs, and structural brackets where light weight and strength-to-weight ratio matter at cryogenic through elevated temperatures.

Space Propulsion

Rocket engine components, injector bodies, turbopump housings, and cryogenic valves requiring strength at extremes of temperature from −423 °F to +1,300 °F.

Oil & Gas Downhole

Wellhead components, completion tools, and sour-service valve bodies per NACE MR0175 in H₂S-bearing environments requiring NACE-compliant heat treatment.

Nuclear & Power Generation

Steam generator components, reactor vessel hardware, and gas turbine compressor blades and vanes in power plant applications.

Defense & Ordnance

Gun barrel components, missile motor cases, and other defense hardware requiring consistent performance under shock, vibration, and thermal cycling.

Stock program

We maintain an extensive inventory of AMS 5662 and AMS 5663 bar across a wide diameter range, enabling rapid response for both prototype and production requirements. Custom sizes, billet, and specialty product forms are available to order.