UNS N07718 Inconel 718 Nickel-chromium Based High Temperature Alloy Rod

UNS N07718 Inconel  718 Nickel-chromium Based High Temperature Alloy Rod

Inconel 718 nickel-chromium-based high-temperature alloy rods have become an important material in the fields of aerospace, energy, and chemical industry due to their excellent high-temperature strength, corrosion resistance, and creep resistance.

Material:

Inconel 718 (UNS N07718) is a precipitation-strengthened nickel-chromium-based high-temperature alloy. By adding elements such as niobium (Nb), molybdenum (Mo), aluminum (Al) and titanium (Ti), γ'' (Ni₃Nb) and γ' (Ni₃(Al,Ti)) strengthening phases are formed, so that it can maintain excellent mechanical strength, creep resistance and corrosion resistance at high temperatures.

Main components (wt.%):

Nickel (Ni): 50-55% (matrix)

Chromium (Cr): 17-21% (anti-oxidation/corrosion)

Iron (Fe): Balance (reduces cost and stabilizes austenite structure)

Niobium + Molybdenum (Nb+Mo): ~5% (main strengthening element)

Aluminum + Titanium (Al+Ti): 0.8-1.2% (auxiliary strengthening)

Core characteristics:

1. High temperature performance: long-term working temperature can reach 700°C (1290°F), short-term resistance to 980°C (1800°F).
2. High strength: yield strength (≥1030 MPa) and tensile strength (≥1240 MPa) far exceed ordinary stainless steel.
3. Corrosion resistance: Resistant to chloride stress corrosion, oxidation, and sulfidation environments, suitable for acidic and marine environments.
4. Processing friendliness: Mechanical properties can be further improved by age-hardening.

Heat treatment:

Solution treatment: 955°C ±10°C, 1 hour/25mm thickness, water quenching.

Age hardening: 720°C ±5°C (8 hours) → 620°C ±5°C (8 hours), air cooling.

• Selection comparison (Inconel 718 vs. other high temperature alloys)
  Alloy	Maximum operating temperature	Key Benefits	Limitation
  Inconel718	700℃	Best comprehensive performance, high cost performance	When the temperature is >650℃ for a long time, the γ" phase will coarsen.
  Inconel 625	870℃	Higher corrosion resistance, no age hardening	Lower strength (yield strength ~550 MPa).
  Haynes 282	800℃	Better creep resistance	High cost and difficult processing.

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• Typical application areas

  Aerospace: jet engine turbine discs, compressor shafts, combustion chamber components (accounting for more than 50% of aviation alloy usage)

  Energy industry: gas turbine blades, nuclear reactor pressure vessel bolts

  Petrochemical: downhole tools, valve stems, high-corrosion environment pump shafts

  Automobile racing: turbocharger housings, exhaust system high-temperature bolts

  
  Quality Assurance:

• Full process control: vacuum induction melting (VIM) + electroslag remelting (ESR) to ensure low oxygen/sulfur content.

More grades: