1. What are the main characteristics of Inconel 718 (UNS N07718)?
Answer:
Inconel 718 is a nickel-chromium-based superalloy strengthened by niobium and molybdenum. It offers:
Excellent high-temperature strength (up to about 700°C / 1300°F)
Outstanding corrosion and oxidation resistance
Superior creep and stress rupture resistance
Good weldability compared to other nickel-based superalloys
High fatigue strength
These properties make it suitable for extreme environments such as aerospace and energy industries.
2. What is the chemical composition of Inconel 718 (NC19FeNb)?
Answer:
Typical chemical composition includes:
Nickel (Ni): 50–55%
Chromium (Cr): 17–21%
Iron (Fe): Balance
Niobium (Nb + Ta): 4.75–5.50%
Molybdenum (Mo): 2.80–3.30%
Titanium (Ti): 0.65–1.15%
Aluminum (Al): 0.20–0.80%
The combination of niobium and molybdenum contributes significantly to precipitation hardening and high strength.
3. What are the typical applications of hot rolled Inconel 718 bars and tubes?
Answer:
Hot rolled Inconel 718 bars, rods, pipes, and tubes are widely used in:
Aerospace engine components (turbine discs, shafts, fasteners)
Gas turbines
Oil and gas drilling equipment
Nuclear reactors
Chemical processing equipment
Its resistance to high pressure, temperature, and corrosive environments makes it ideal for critical components.
4. What standards are applicable to Inconel 718 (UNS N07718) products?
Answer:
Common standards include:
ASTM B637 (bars and forgings)
ASTM B670 (plate and sheet)
ASTM B983 (billets and bars)
AMS 5662 / AMS 5663 (aerospace specifications)
UNS designation: N07718
Compliance with these standards ensures consistent mechanical properties and chemical composition.
5. What are the mechanical properties of Inconel 718 after heat treatment?
Answer:
After solution treatment and aging, typical mechanical properties are:
Tensile Strength: ≥ 1240 MPa
Yield Strength (0.2% offset): ≥ 1030 MPa
Elongation: ≥ 12%
Hardness: Around 35–45 HRC
These properties may vary depending on product form (bar, rod, pipe, tube) and processing condition.
