Inconel 718 nickel base alloy

Inconel718 alloy is a precipitation-hardened nickel-ferrochrome alloy containing niobium and molybdenum. It has high strength, good toughness and corrosion resistance at high and low temperatures up to 650℃. Its state can be solution treatment or precipitate hardening state.

It has the following characteristics
● Easy to process
● High tensile strength, fatigue strength, creep strength and fracture strength at 700℃
● High oxidation resistance at 1000℃
● Stable chemical properties at low temperature
● Good welding performance
Application field
Due to high temperature strength and excellent corrosion resistance at 700℃, easy to process, can be widely used in a variety of high-demand occasions. ● Steam turbines ● liquid fuel rockets
● Cryogenic engineering
● Acidic environment
Second-ranking nuclear engineering

Close to the brand
GH4169, GH169 (China), NC19FeNb (France), NiCr19Fe19Nb5, Mo3(Germany), NA 51 (UK) Inconel718, UNS NO7718(USA) NiCr19Nb5Mo3(ISO)
Chemical composition

Inconel718 alloy is a difficult material in machining field.
preheating
The surface of the workpiece must be cleaned before and during heating to keep the surface clean. Inconel718 alloy will become brittle if the heating environment contains sulfur, phosphorus, lead or other low melting point metals. Impurities come from labeled paint, chalk, lubricating oil, water, fuel, etc. The sulfur content of fuel should be low, for example, the impurity content of liquefied gas and natural gas should be less than 0.1%, the sulfur content of city gas should be less than 0.25g/m3, and the sulfur content of LPG should be less than 0.5%.
The electric furnace heated should have more accurate temperature control ability, furnace gas must be neutral or weak alkaline, should avoid the composition of furnace gas in oxidation and reduction fluctuations.
Hot working
The suitable hot working temperature of Inconel718 alloy is 1120-900℃, and the cooling method can be water quenching or other rapid cooling methods. After hot working, the alloy should be annealed in time to ensure the best properties. During hot processing, the material should be heated to the upper limit of the processing temperature. In order to ensure the plasticity of the processing, the final processing temperature should not be lower than 960℃ when the deformation amount reaches 20%.
Cold working
Cold working should be carried out after solution treatment, the work hardening rate of Inconel718 is higher than that of austenitic stainless steel, so the processing equipment should be adjusted accordingly, and there should be an intermediate annealing process in the cold working process.
Heat treatment
Different solution treatment and aging treatment will get different material properties. Due to the low diffusion rate of γ "phase, the best mechanical properties of Inconel718 alloy can be obtained by aging for a long time.
polishing
Oxides near the welds of Inconel718 workpieces are more difficult to remove than those of stainless steel and require grinding with a fine sand belt. Oxides are also removed with sandpaper or pre-treated with salt bath before pickling in a mixture of nitric and hydrofluoric acid.
machining
Inconel718 is machined after solution treatment, taking into account the workhardenability of the material. Unlike austenitic stainless steel, Inconel718 is suitable for low surface cutting speeds.
welding
The precipitate hardened Inconel718 alloy is suitable for welding and has no post-weld cracking tendency. Weldability, workability and high strength are the major advantages of this material.
Inconel718 is suitable for arc welding, plasma welding, etc. Before welding, the surface of the material should be clean, no oil, no chalk marks, etc., and the bright metal should be polished within 25mm around the weld.