Inconel 718 (or Alloy 718) is a special type of high strength superalloy whose nickel-chromium base makes it resistant to corrosion, oxidation, high pressure and extreme temperatures up to 700°C. Inconel's high temperature strength is developed through solid solution strengthening or precipitation hardening.
The material is composed of 50-55% nickel, 17-21% chromium, 4.75-5.5% niobium and tantalum, and trace amounts of molybdenum, titanium, cobalt, aluminum, manganese, copper, silicon and other elements.
Due to its unique properties, Inconel 718 is widely used in industries such as manufacturing, military equipment and the aerospace industry.
Inconel 718 nickel-based alloy was originally developed for the manufacture of aircraft piston engine turbochargers. Today, the most common application is aircraft turbine components, which need to maintain superior performance in severe oxidizing environments and high temperature conditions for a limited period of time. Current applications include:
Aircraft gas turbines Medical applications Spacecraft and rocket engines
Steam turbine power plant Nuclear power plant Heat treatment equipment
It is also used to design components for liquid fuel rockets, rings and casings, and various formed sheet metal components for aircraft and land-based turbine engines. At the other end of the temperature scale, Inconel Alloy 718 is also used in cryogenic storage tanks.
The nickel-based superalloy 718 has good resistance to oxidation and other types of corrosion in space jet engine and land-based gas turbine applications. It is an ideal material for applications requiring excellent creep and stress corrosion cracking resistance (up to 982oC or 1800oF). Alloy 718 is completely resistant to pitting and crevice corrosion in sulfide, chloride, carbon dioxide and other harsh environments.
Even at the extremely low temperature of -253°C, Inconel 718 still has good impact performance. It welds easily without toughening or cracking. It can be easily worked and age hardened. Alloy 718 is welded in the solution annealed condition, but can be aged and cold worked.
Inconel 718 ages to harden during heat treatment. It has an austenite grain structure in a wide temperature range. Different solution and aging treatments are used when heat treating this alloy to enhance its short- or long-term high-temperature mechanical properties.
1. Preheating: The surface of the workpiece must be cleaned before and during the heating process, and the surface must be kept clean. Inconel alloy 718 will become brittle if the heating environment contains sulfur, phosphorus, lead or other low melting point metals.
The heating electric furnace should preferably have more accurate temperature control ability, the furnace gas must be neutral or weakly alkaline, and the furnace gas composition should be prevented from fluctuating in oxidation and reduction.
2. Thermal processing: The suitable thermal processing temperature of Inconel 718 alloy is 1120-900°C. The cooling method can be water quenching or other rapid cooling methods. After thermal processing, it should be annealed in time to ensure the best performance. During hot processing, the material should be heated to the upper limit of the processing temperature. In order to ensure the plasticity during processing, the final processing temperature when the deformation reaches 20% should not be lower than 960°C.
3. Cold working: Cold working should be carried out after solution treatment. The work hardening rate of Inconel 718 is higher than that of austenitic stainless steel, so the processing equipment should be adjusted accordingly, and there should be a central annealing process during the cold working process.
Welding of Alloy 718 is challenging especially in the HAZ (heat-affected zone) due to the risk of alloying element fracture and microstructural segregation. Ideally welding is done by gas tungsten arc welding and electron beam welding.
Wudenalloy has focused on the production and manufacture of nickel alloys for more than ten years. We are a principal worldwide supplier of corrosion-resistant alloys and other superalloy metals. We have a professional technical team and after-sales service, so we can offer high-quality Hastelloy, Incoloy, Inconel, Monel, Duplex Stainless Steel, and other alloy material. These materials are available in wire, bar, sheet&plate, pipe&tube, flange, forging, and other forms to meet the needs of our customers.
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