Inconel 718: Heat Treatment, Mechanical Properties, and Key Applications

Inconel 718 is a high-nickel, heat-treatable alloy widely used in aerospace and oil & gas applications where high strength and corrosion resistance are required. It is most commonly supplied in the solution-annealed condition (AMS 5662), which is suitable for general use and allows flexibility for further heat treatment after machining.

For aerospace applications, annealed Inconel 718 can be aged to AMS 5663 to achieve higher mechanical strength. When heat-treated to meet API 6A and NACE MR0175, Inconel 718 is mainly used in oil and gas service, especially for high-pressure and sour environments.

Choosing the correct heat-treated condition is important, as aerospace and oil-and-gas requirements differ. While AMS 5662 material can be aged to meet aerospace standards, full conversion to API 6A compliance is uncommon.

Fig. 1: Inconel 718 Round Bar ASTM B637 Solution Annealed

Major Applications：

Gas turbine engine components
Aerospace engine fasteners and bolts
Oil & gas downhole tools
High-pressure valve and wellhead parts
Liquid rocket motor components
Cryogenic tanks and valves
Springs, studs, and high-strength fasteners

Inconel 718 – Heat Treatment & Mechanical Properties

ASTM B637 | UNS N07718

Heat Treatment (ASTM B637)

Melt Practice in our Mill:

VIM (Vacuum Induction Melting) + ESR (Electroslag Remelting)

Round Bar Sizes: Dia. 1 mm to 300 mm, Length: up to 7000 mm

MOQ: 100 kg

Mill Facilities:

Smelting, Forging, Peeling/Grinding/Cutting, Heat Treatment, EN10204 3.1 Quality Test in-house.

Hot Rolling outsourced.

Our Facilities

Fig. 1. VIM (Vacuum Induction Melting)

Fig. 2. VIM Furnace Top View

Mechanical Properties (Minimum)

Characteristics:

Exceptional strength after heat treatment
Inconel 718 can be precipitation hardened to achieve very high yield and tensile strength, outperforming many solid-solution nickel alloys.

Excellent fatigue and creep resistance
It performs reliably under cyclic loads and sustained stress, especially at elevated temperatures up to around 650 °C.

Good weldability for a high-strength nickel alloy
Compared with many other nickel alloys, Inconel 718 is easier to weld with low risk of cracking.

Strong corrosion resistance in harsh environments
It resists oxidation, chlorides, and sour-gas conditions, making it suitable for both aerospace and oil & gas service.

What makes Inconel 718 different from Other Nickel Alloys

Many nickel alloys offer high strength, corrosion resistance, or good high-temperature performance. Inconel 718 stands out because it delivers all of these properties together, with fewer trade-offs.

1. High strength with simpler heat treatment
   Unlike alloys such as Inconel 625 or Monel 400, which rely mainly on solid-solution strengthening, Inconel 718 gains its strength through controlled precipitation hardening. This allows much higher and more repeatable mechanical properties.
2. Better weldability at high strength levels
   Compared with other age-hardened nickel alloys, Inconel 718 has lower cracking sensitivity during welding, which makes fabrication and repair more practical.
3. Stable performance over a wide temperature range
   Inconel 718 maintains strength from cryogenic temperatures up to about 650 °C, while many other nickel alloys are optimized only for either low-temperature toughness or high-temperature strength.
4. Cost-effective strength for demanding applications
   While not the cheapest nickel alloy, Inconel 718 often provides the best strength-to-cost ratio for aerospace and oil & gas components that require both mechanical performance and corrosion resistance.