GH4169 Steel Comprehensive Guide
What is GH4169 Steel?
GH4169 steel is composed of body-centered tetragonal structure γ" and face-centered cubic γ′ nickel-based high-temperature alloy phase precipitation strengthening with good comprehensive properties in the temperature range of -253～700℃. The yield strength below 650℃ ranks first among deformed high-temperature alloys, and has good fatigue resistance, radiation resistance, oxidation resistance, corrosion resistance, as well as good processing performance, welding performance and long-term structural stability. It can be used to manufacture various complex-shaped parts in aerospace, nuclear energy, and petroleum industries; it has been widely used in the above temperature range.
Another feature of the alloy is that its microstructure is particularly sensitive to hot working technology. By mastering the laws of phase precipitation and dissolution in the alloy, as well as the relationship between microstructure, process and performance, and formulating reasonable and feasible process procedures for different use requirements, various parts and use requirements that meet different strength grades can be obtained. The supply varieties include forgings, forged bars, rolled bars, cold-rolled bars, discs, rings, plates, strips, wires, Pipes, etc. It can be made into discs, rings, blades, shafts, fasteners and elastic elements, sheet structures, casings and other parts used in aviation for a long time.
Main characteristics of GH4169 material
GH4169 high temperature alloy has the following advantages:
Strong high temperature stability: GH4169 alloy has good stability and oxidation resistance in high temperature environment, and is not prone to softening, oxidation and other phenomena.
Strong corrosion resistance: GH4169 alloy can resist the erosion of various corrosive media and has good corrosion resistance.
High strength and toughness: GH4169 alloy has high strength and toughness, is not easy to deform and break, and has good mechanical properties.
Thermal expansion coefficient is similar to that of steel: GH4169 The thermal expansion coefficient of the alloy is similar to that of steel, making it less prone to stress concentration and deformation during use.
Application of GH4169 high-temperature alloy
GH4169 high-temperature alloy has the characteristics of high strength, high toughness, good corrosion resistance, and good high-temperature stability. It is widely used in aviation, aerospace, petroleum, chemical industry and other fields. In the field of aerospace, GH4169 is mainly used to manufacture high-temperature parts such as turbine blades, turbine discs, combustion chambers, etc. In the field of petrochemicals, GH4169 is often used to manufacture reactors, steam generators, hydrogenation equipment, etc. In addition, GH4169 can also be used to manufacture automobile emission systems, nuclear power plant reactors and other fields.
GH4169 (inconel 718, N07718) Performance requirements of high-temperature alloys
Due to the high niobium content in GH4169 alloy, the niobium segregation composition in the alloy is directly related to the metallurgical process. The melting speed of electroslag remelting and vacuum arc melting and the quality of the electrode rod directly affect the quality of the material. Fast melting speed is easy to form niobium-rich black spots; slow melting speed will lead to the formation of niobium-poor white spots; poor surface quality and internal cracks in the electrode rod can easily lead to the formation of white spots. Therefore, improving the quality of the electrode rod, controlling the melting speed, and increasing the solidification speed of the ingot are key factors in the smelting process. In order to avoid excessive segregation of elements in the ingot, the diameter of the ingot currently used is not more than 508mm. The homogenization process must ensure that the L phase in the ingot is completely dissolved. The time for the secondary homogenization of the ingot and the secondary homogenization of the intermediate billet is determined according to the diameter of the ingot and the intermediate billet. Homogenization process The control of the process is directly related to the segregation of niobium in the material. The 1160℃, 20h+1180℃, 44h homogenization process currently used in production is not enough to eliminate the center segregation of the steel ingot. Therefore, it is recommended to use the following process:
1150℃-1160℃, 20h-30h+1180℃-1190℃, 110h-130h;
1160℃, 24h+1200℃, 70h.
The alloy after homogenization treatment has good hot working properties. The heating temperature of the steel ingot opening shall not exceed 1120℃. The forging process of the forging should be determined according to the purpose and use requirements of the forging and the conditions of the production plant. When producing forgings from billets, the intermediate annealing temperature and the final temperature must be determined according to the organization and performance required by military parts. Generally, the final temperature of forging should be controlled between 930℃ and 950℃.
