UNS N07718-GH4169-INCONEL 718-nuts

characteristics and structural composition of GH4169 / INCONEL 718 / UNS N07718 superalloy (HY-industry technical centre)

GH4169 / INCONEL 718 / UNS N07718 superalloy is a nickel-based superalloy with body-centered tetragonal γ” and face-centered cubic γ’phase precipitation strengthening. It has good comprehensive performance in the temperature range of -253~700℃, 650℃ The following yield strength ranks first in deformed superalloys, and has good fatigue resistance, radiation resistance, oxidation resistance, corrosion resistance, as well as good processing performance, welding performance and long-term structural stability, and can produce various complex shapes. Components, in the aerospace, nuclear energy, and petroleum industries, have been extremely widely used in the above-mentioned temperature range.

Another feature of the alloy is that the alloy structure is particularly sensitive to hot working processes. The relationship between phase precipitation and dissolution in the alloy and the relationship between structure, process and performance can be mastered. Reasonable and feasible process regulations can be formulated for different use requirements. A variety of parts that can meet different strength levels and usage requirements can be obtained. The varieties supplied are forgings, forged bars, rolled bars, cold rolled bars, round cakes, rings, plates, strips, wires, tubes, etc. It can be made into discs, rings, blades, shafts, fasteners and elastic elements, sheet structure parts, receivers and other parts for long-term use in aviation.

Material grades and equivalents:

Inconel 718 / GB GH4169 / UNS N07718 / SEW VDIUV W.Nr.2.4668 NiCr19Fe19Nb5Mo3 / BS NA 51/ AFNOR NC19FeNb

GH4169 / INCONEL 718 / UNS N07718 Chemical composition:

 %

 Ni

 Cr

 Fe

 Mo

 Nb

 Co

 C

 Mn

 Si

 S

 Cu

 Al

 Ti

 Min.

 50

 17

   balance

 2.8

 4.75

 0.2

 0.7

Max.

 55

 21

 3.3

 5.5

 1

 0.08

 0.35

 0.35

0.01

 0.3

 0.8

 1.15

 

GH4169 / INCONEL 718 / UNS N07718 Physical properties:

Density

8.2 g/cm³

Melting point

1260-1340 ℃

 

GH4169 / INCONEL 718 / UNS N07718 Alloy minimum mechanical properties in the roomtemperature:

 Alloy

Tensile strength Rm N/mm²

Yield strength R P0. 2N/mm²

Elongation A 5 %

Brinell hardness HB

Solutiontreatment

 965

 550

 30

 ≤363

GH4169 / INCONEL 718 / UNS N07718 alloy has the following characteristics:

  • Has high tensile strength, fatigue strength, creep strength and breaking strength at 700°C. It has high oxidation resistance at 1000°C.

  • Has stable chemical properties at low temperatures and good welding performance. Regardless of high temperature or low temperature environment, GH4169 alloy has excellent resistance to stress corrosion cracking and pitting corrosion. GH4169 alloy has excellent oxidation resistance at high temperatures

Metallographic structure of GH4169 / INCONEL 718 / UNS N07718:

  • GH4169 alloy has an austenitic structure, and the γ” phase formed after precipitation hardening gives it excellent mechanical properties. The δ phase formed at the grain boundary during the heat treatment process gives it the best plasticity.

GH4169 / INCONEL 718 / UNS N07718 alloy has the following characteristics:

  • Has high tensile strength, fatigue strength, creep strength and breaking strength at 700°C. It has high oxidation resistance at 1000°C.

  • Has stable chemical properties at low temperatures and good welding performance. Regardless of high temperature or low temperature environment, GH4169 alloy has excellent resistance to stress corrosion cracking and pitting corrosion. GH4169 alloy has excellent oxidation resistance at high temperatures

Metallographic structure of GH4169 / INCONEL 718 / UNS N07718:

  • GH4169 alloy has an austenitic structure, and the γ” phase formed after precipitation hardening gives it excellent mechanical properties. The δ phase formed at the grain boundary during the heat treatment process gives it the best plasticity.

GH4169 Metallographic Structure:

  • Structure of GH4169 / INCONEL 718 / UNS N07718 superalloy in standard heat treatment state is composed of γ matrix, γ’, γ”, δ, NbC phase. γ” (Ni3Nb) phase is the main strengthening phase, which is the sub-structure of body-centered tetragonal The stable phase is dispersed and coherently precipitated in the matrix in the form of a disc. During long-term aging or long-term application, there is a tendency to transform to the δ phase, which reduces the strength.

  • Number of γ'(Ni3 (Al, Ti)) phase is second to that of γ” phase, which is dispersed and precipitated in a spherical shape, which plays a part of strengthening the alloy. δ phase mainly precipitates at the grain boundary, and its morphology is related to the final forging temperature during forging , The final forging temperature is 900℃, forming needles and precipitating in the grain boundaries and grains; the final forging temperature reaches 930℃, the δ phase is granular and uniformly distributed; the final forging temperature reaches 950℃, the δ phase is short rod-like, distributed Mainly at the grain boundary; the final forging temperature reaches 980℃, and a small amount of needle-like δ phase is precipitated at the grain boundary, and the forgings appear persistent notch sensitivity. The final forging temperature reaches 1020℃ or higher, and there is no δ phase precipitation in the forgings, and the grains follow The forgings have long-lasting notch sensitivity. During the forging process, the δ phase precipitates at the grain boundary, which can play a pinning role and hinder the grain coarsening.

  • L phase is deformed GH4169 / INCONEL 718 / UNS N07718 alloy. The existing phase, which is rich in niobium, exists between the dendrites of the ingot, reduces the initial melting point of the ingot, and the relationship between the solid solution temperature of the L phase in the ingot and the homogenization time.

 

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