GH4 169 alloy is a nickel-based superalloy strengthened by precipitation of tetragonal centered γ "phase and cubic centered γ' phase. It has good comprehensive properties in the range of -253 ~ 700℃, and the yield strength below 650℃ ranks first among deformed superalloys. It also has good fatigue resistance, radiation resistance, oxidation resistance and corrosion resistance, as well as good machinability, weldability and long-term structural stability. Another feature of this alloy is that its microstructure is particularly sensitive to hot working process. By mastering the law of precipitation and dissolution of phases in the alloy and the relationship between microstructure, technology and properties, reasonable and feasible process regulations can be formulated for different application requirements, and various parts meeting different strength grades and application requirements can be obtained. The varieties supplied are forgings, forged bars, rolled bars, cold rolled bars, round cakes, rings, plates, belts, wires and tubes. It can be made into disks, rings, blades, shafts, fasteners and elastic elements, plate structures, boxes and other parts for long-term use in aviation.

1. 1 GH4 169？ Material grade GH 169

1.2 GH4 169？ Similar brands? Inconel 7 18 (USA), NC 19FeNb (France)

1.3 GH4 169？ Material technical standard

GJB 26 12- 1996 Specification for Welding Superalloy Cold-drawn Steel Wire

Hb6702-1993gp169wz8 series alloy bars.

GJB 3 165？ Specification for superalloy hot rolled and forged bars for aircraft bearing parts

GJB 1952 Specification for Cold Rolled Superalloy Sheet for Aviation

GJB 1953 Specification for Superalloy Hot Rolled Bars for Rotating Parts of Aeroengines

Specification for GJB 26 12 superalloy cold-drawn materials for welding

Specification for GJB 33 17 High-temperature Alloy Hot-rolled Steel Plate for Aviation

GJB 2297 Specification for Cold-drawn (Rolled) Seamless Tube of Superalloy for Aviation

GJB 3020 specification for superalloy ring blank for aviation.

GJB 3 167 Specification for Cold-drawn Superalloy Materials for Cold Heading

GJB 33 18 Specification for Cold Rolled Superalloy Strip for Aviation

GJB 26 1 1 Specification for superalloy cold-drawn bars for aviation.

Cold drawing of welding superalloy YB/T5247

YB/T5249 "Cold Drawing of Superalloys for Cold Heading"

YB/T5245 "Hot Rolled and Forged Bars of Superalloy for General Bearing Parts"

GB/T 14993 "high temperature alloy hot rolled bar for rotating parts"

GB/T 14994 "high temperature alloy cold-drawn steel bar"

GB/T 14995 "Superalloy Hot Rolled Sheet"

GB/T 14996 "superalloy cold-rolled sheet"

Forging round cakes for superalloys

GB/T 14998 "Superalloy Blank Hairiness"

GB/T 14992 Classification and Naming of Superalloys and Intermetallic Compounds

HB 5 199 cold-rolled superalloy sheet for aviation

HB 5 198 "wrought superalloy bars for aviation blades"

HB 5 189 "deformed superalloy bar for aviation blades"

HB 6072 GH 4 169 wz8 series alloy bars.

1.4 GH4 169？ Chemical composition The chemical composition of this alloy can be divided into three categories: standard composition, high-quality composition and high-purity composition, as shown in table 1- 1. High-quality components reduce carbon and increase niobium on the basis of standard components, thus reducing the number of niobium carbide, reducing fatigue sources, increasing the number of strengthening phases, and improving fatigue resistance and material strength. While reduce that content of harmful impurities and gas. High purity components reduce the content of sulfur and harmful impurities on the basis of high quality standards, and improve the purity and comprehensive properties of materials.

The content of boron in GH4 169 alloy for nuclear energy needs to be controlled (other elements remain unchanged), and the specific content shall be determined through consultation between the supplier and the buyer. When ω (b) is less than or equal to 0.002%, in order to distinguish it from GH4 169 alloy used in aerospace industry, the alloy grade is GH4 169A.

1.5 GH4 169？ Heat treatment system? Alloys have different heat treatment systems to control the grain size, morphology, distribution and quantity of δ phase, so as to obtain different levels of mechanical properties. Alloy heat treatment system is divided into three categories:

I:( 10 10 ~ 1065)℃

The grain size of the material treated by this system is coarsened, and there is no δ phase in the grain boundary and grain, which is sensitive to notch, but it is beneficial to improve the impact property and low temperature hydrogen embrittlement resistance.

Ⅱ: (950 ~ 980)℃ 65438 00℃, 65438±0h, oil cooling, air cooling or water cooling+720℃ 5℃ for 8h, furnace cooling at 50℃/h to 620℃ 5℃ for 8h, air cooling.

The material treated by this system has δ phase, which is beneficial to eliminate notch sensitivity. It is the most commonly used heat treatment system, also known as the standard heat treatment system.

Ⅲ: 720℃ 5℃ for 8h, cooling to 620℃ 5℃ at furnace speed of 50℃/h, and air cooling for 8h.

After this treatment, the δ phase in the material is less, which can improve the strength and impact properties of the material. This system is also called direct aging heat treatment system.

1.6 GH4 169？ Variety specifications and supply status? We can provide die forgings (disc and integral forgings), cakes, rings, bars (forged bars, rolled bars and cold-drawn bars), plates, wires, belts, tubes, fasteners of different shapes and sizes, elastic elements and so on. The delivery status is determined by both parties. The welding wire is delivered in a disc shape in the agreed delivery state.

1.7? GH4 169？ Melting and casting process? The melting process of alloys can be divided into three categories: vacuum induction plus electroslag remelting; Vacuum induction and vacuum arc remelting; Vacuum induction+ESR+vacuum arc remelting. According to the requirements of parts, the required melting process can be selected to meet the use requirements. ?

1.8? GH4 169？ Application overview and special requirements? Manufacturing all kinds of static and rotating parts in aviation and aerospace engines, such as disks, rings, shells, shafts, blades, fasteners, elastic elements, gas ducts, seals, etc. And welding structural components; Manufacturing various elastic elements and grids for nuclear energy industrial applications; Used for manufacturing parts and other parts in petroleum and chemical fields.

In recent years, on the basis of in-depth study and expansion of the application of this alloy, many new processes have been developed to improve the quality and reduce the cost: vacuum arc remelting adopts helium cooling process to effectively reduce niobium segregation; The annular parts are produced by spray molding process, which reduces the production cost and shortens the production cycle; Adopt superplastic forming process to expand the production range of products.

Physical and chemical properties of GH4 169

2. 1 GH4 169？ Hot real estate

2. 1. 1 GH4 169？ Melting temperature range? 1260~ 1320℃。

2. 1.2 GH4 169？ See table 2- 1 for thermal conductivity.

4.3 alloy structure

4.3. 1 alloy consists of γ matrix, γ′, γ″, δ and NbC phases in standard heat treatment state. γ "(Ni3Nb) phase is the main strengthening phase, which is a metastable phase with a body-centered tetragonal ordered structure. It disperses * * lattice precipitation in the matrix in the form of a disk. In the process of long-term aging or long-term use, it is easy to transform into δ phase and reduce the strength. The quantity of γ′ (Ni3 (Al, Ti)) phase is less than that of γ″ phase, and it disperses and precipitates spherically, which plays a role in strengthening the alloy. δ phase is mainly precipitated at grain boundaries, and its morphology is related to the final forging temperature during forging. The final forging temperature is 900℃, forming a needle shape, which precipitates at the grain boundary and within the grain. The final forging temperature reaches 930℃, and the δ phase is granular and evenly distributed. The final forging temperature reaches 950℃, and the δ phase is short rod-shaped and mainly distributed at grain boundaries. The final forging temperature reaches 980℃, and a small amount of needle-like δ phase precipitates at the grain boundary, so the forgings show lasting notch sensitivity. When the final forging temperature reaches above 1020℃, there is no δ phase precipitation in the forging, and the grain is coarsened, so the forging is sensitive to lasting notch. During forging, δ phase precipitates at grain boundaries, which plays a pinning role and prevents grain coarsening.

4.3.2 L phase is not allowed in deformed GH4 169 alloy. This phase is rich in niobium and exists between dendrites of the ingot, which reduces the initial melting point of the ingot. See Figure 4-2 for the relationship between the solid solution temperature and homogenization time of L phase in ingot.

granularity

4.3.3. The grain growth trend of1alloy during high-temperature solution (holding for 2h) is shown in Figure 4-3.

4.3.3.2 bar (original grain size 9 ~ 9.5) was forged at different temperatures and different deformation, and then subjected to standard heat treatment (solution temperature 965℃, 65438 0 h). See table 4- 1 for particle size change.

According to the technical standard of forgings in 4.3.3.3, the average grain size of ordinary forgings is Grade 4, with individual Grade 2 allowed, and the average grain size of high-strength forgings is Grade 8, with individual Grade 2 allowed. The average grain size of direct aging forgings should be 10 or finer.

4.3.4 See Table 4-2 for the change of the number of precipitated phases of direct aging forgings after long-term aging at 600 ~ 700℃ for 500 hours. ..

The technological properties and requirements of verb (abbreviation of verb) GH4 169

5. 1 formability

5. 1. 1 Because of the high niobium content in GH4 169 alloy, the degree of niobium segregation in the alloy is directly related to metallurgical process. The melting speed of electroslag remelting and vacuum arc melting and the quality of electrode rod directly affect the quality of materials. The melting speed is fast, and it is easy to form niobium-rich black spots; Slow melting speed will form niobium-poor white spots; The surface quality of the electrode rod is poor, and the electrode rod has cracks, which easily leads to the formation of white spots. Therefore, improving the quality of electrode rod, controlling the melting speed and improving the solidification speed of ingot are the key factors in the melting process. In order to avoid serious segregation of elements in steel ingots, the diameter of steel ingots used so far is no more than 508 mm

Homogenization process must ensure the complete melting of L phase in ingot. The time of two-stage homogenization of ingot and secondary homogenization of tundish depends on the diameters of ingot and tundish. The control of homogenization process is directly related to the segregation degree of niobium in the material.

At present, the homogenization processes of 1 160℃, 20h 1 180℃ and 44h used in production are not enough to eliminate the central segregation of ingots, so the following homogenization processes are suggested:

1. 1 150 ~ 160℃，20 ~ 30h+ 1 180 ~ 1 190℃， 1 10 ~ 130h；

2. 1 160℃，24h+ 1200℃，70h[20]。

5. The alloy homogenized by1.2 has good hot workability, and the heating temperature of ingot cogging does not exceed 1 120℃. The forging process of forgings should be based on the service conditions and application requirements of forgings and the production conditions of manufacturers. In cogging and forging production, the intermediate annealing temperature and final forging temperature must be determined according to the required structure and properties of the parts. In general, the final forging temperature of forgings should be controlled between 930 ~ 950℃. See table 5- 1 for the forging temperature and deformation degree of various forgings.

5. 1.3 See Table 5-2 for the characteristics of cold forming of metal plates.

5. 1.4 See Figure 5- 1 for the relationship between deformation degree, final forging temperature and grain size.

5. The dynamic recrystallization of1.5 alloy is shown in Figure 5-2.

5. 1.6 Engine blade die forgings are forged by upsetting and final forging. See Table 5-3 for the influence of different forging heating temperatures on the comprehensive properties of the blade. The microstructure and properties of the final forged blade upset at 1020℃ are the best.

5. The high temperature deformation resistance curve of1.7 alloy is shown in Figure 5-3.

5.2 Weldability The alloy has satisfactory weldability and can be welded by argon arc welding, electron beam welding, seam welding and spot welding.

For parts in direct aging state, inertia friction welding is suggested to maintain its strengthening effect. By choosing proper parameters of friction welding process, the strengthening phases γ′, γ″ and δ″ can remain at the weld edge and heat affected zone, and have no obvious influence on the joint performance. For forgings in the direct aging state, friction welding can be carried out in the forging state, and then direct aging treatment can be carried out after welding (system ⅲ), so as to obtain welded joints with high lasting strength [2686616]

5.3 Heat Treatment Process of Parts The heat treatment of aviation parts is usually carried out according to the two or three systems specified in 1.5, namely the standard heat treatment system and the direct aging heat treatment system. Other heat treatment systems can also be adopted under the technical basis. When the heat treatment is carried out according to the standard system, the solution treatment can be carried out in the range of 950 ~ 980℃, and the selected temperature is 65438 00℃.

5.4 Surface treatment technology If necessary, shot peening, hole squeezing or wire rolling can be used to strengthen the surface of the parts, so that the working life of the parts under alternating load can be doubled.

For the parts that need to be sprayed with wear-resistant sealing coating, plasma spraying or explosion spraying can be used, and it is best to use explosion spraying. Explosive spraying coating has high bonding strength with matrix, compact coating, high hardness, low porosity and good wear resistance.

5.5 Cutting and grinding properties The alloy can be cut satisfactorily.

When machining, ensure that the circular arc meets the design requirements and has a smooth transition. Sharp corners, pits and scratches are not allowed during processing, assembly or transportation, because these defects will form excessive stress concentration, which will lead to serious accidents in use.

Six, gh4169 (gh4169) low temperature tensile and yield properties (including heat treatment process)

Table 6- 1- Effect of temperature on tensile properties of hot rolled bar