GH4169, the king of deformable high-temperature alloys
GH4169, also known as Inconel 718, is a precipitation-strengthened nickel-based high-temperature high-strength alloy. Inconel 718 has good comprehensive properties in the temperature range of -253 to 700°C. The yield strength below 650°C ranks first among deformable high-temperature alloys. It also has good fatigue resistance, radiation resistance, oxidation resistance, corrosion resistance, as well as good processing performance, welding performance and long-term organizational stability. It can manufacture various parts with complex shapes. It has been widely used in aerospace, nuclear energy, and petroleum industries within the above temperature range.
Another feature of this alloy is that the organization of the alloy is particularly sensitive to hot working technology. By mastering the laws of phase precipitation and dissolution in the alloy and the relationship between organization, process and performance, reasonable and feasible process specifications can be formulated for different use requirements, and various parts that meet different strength levels and use requirements can be obtained.
Inconel 718 has the following characteristics:
1. Easy processing
2. High tensile strength, fatigue strength, creep strength and fracture strength at 700℃
3. High oxidation resistance at 1000℃
4. Stable chemical properties at low temperature
5. Good welding performance
Inconel 718 metallographic structure, 718 alloy is austenitic structure, and the γ" phase generated after precipitation hardening gives it excellent mechanical properties. The δ phase generated at the grain boundary during heat treatment gives it the best plasticity.
Inconel 718 corrosion resistance: Regardless of high or low temperature environment, 718 alloy has excellent resistance to stress corrosion cracking and pitting. The oxidation resistance of 718 alloy at high temperature is particularly outstanding.
Inconel 718 process performance and requirements: (1) Hot working: The appropriate hot working temperature is 1120-900℃. The cooling method can be water quenching or other rapid cooling methods. Annealing should be carried out in time after hot working to ensure the best performance. During hot working, 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℃. (2) Cold working: Cold working should be carried out after solution treatment. The work hardening rate is greater than that of austenitic stainless steel. Therefore, the processing equipment should be adjusted accordingly, and there should be an intermediate annealing process during the cold working process.
Inconel718 welding process: The alloy has satisfactory welding performance and can be welded by argon arc welding, electron beam welding, seam welding, spot welding and other methods.
Inconel718 parts heat treatment process: The heat treatment of aviation parts is usually carried out according to the standard heat treatment system and the direct aging heat treatment system.
Inconel 718 application range: Due to its high temperature strength, excellent corrosion resistance and easy processing at 700℃, 718 can be widely used in various high-demand occasions.
1. Steam turbine
2. Liquid fuel rocket
3. Cryogenic engineering
4. Acidic environment
5. Nuclear engineering
