Inconel 718 Tee Ni-Cr-Fe Alloy With High-Temperature Strength
Inconel 718 tee is a high-performance nickel-based alloy pipe fitting that plays a crucial role in extreme working conditions.
I. Material Basis: Properties of Inconel 718 Alloy
Inconel 718 is a precipitation-hardening nickel-chromium-iron alloy (UNS N07718). It features a high nickel content (50 - 55%), high chromium content (17 - 21%), and high niobium content (4.75 - 5.5%), along with elements such as molybdenum (2.8 - 3.3%) and titanium (0.65 - 1.15%):
1.Matrix Strengthening: Nickel forms a face-centered cubic austenitic matrix, ensuring high-temperature toughness and providing an antioxidant base.
2.Precipitation Strengthening: Niobium and titanium form γ′′ (Ni₃Nb) and γ′ (Ni₃(Al,Ti)) strengthening phases. After aging heat treatment, they significantly enhance strength and creep resistance.
3.Corrosion Resistance Assurance: Chromium forms a dense chromium oxide film, resisting high-temperature oxidation and sulfide corrosion; molybdenum optimizes resistance to pitting and crevice corrosion.
II. Core Performance of the Tee (Compared with Conventional Alloy Tees)
| Performance Dimension |
Properties of Inconel 718 Tee |
Technical Value |
| High-Temperature Strength |
Tensile strength exceeds 1275MPa and yield strength exceeds 700MPa at 650 - 700℃ (after aging treatment). |
In high-temperature and high-load scenarios such as aero-engine turbine disks and nuclear power main pipelines, there is no significant deformation during long-term service (compared with 316L, strength is increased by 2 - 3 times). |
| Creep Resistance |
Creep deformation < 0.1% under constant stress at 700℃ for 1000 hours (per ASTM standards). |
Suitable for hot-end components of gas turbines (such as combustor manifolds), resisting high-temperature persistent loads, with a service life exceeding 20,000 hours (common alloy tees < 5,000 hours). |
| Corrosion Adaptability |
Resistant to seawater (containing chloride salts), sulfuric acid/hydrochloric acid (medium to low concentrations), and high-temperature oxidizing atmospheres (≤1000℃). |
In marine engineering (high-pressure pipelines for seawater desalination) and petrochemical industries (acidic medium transportation), the corrosion rate < 0.025mm/year (corrosion rate of 316L in seawater environment > 0.1mm/year). |
| Low-Temperature Stability |
No toughness degradation at - 253℃ (deep cold), with Charpy impact energy > 80J (tested at - 196℃). |
In liquefied natural gas (LNG) transportation and aerospace liquid hydrogen pipelines, it avoids the risk of low-temperature brittle fracture and ensures ultra-low-temperature sealing reliability. |
III. Typical Application Scenarios
1.Aerospace
▶Scenarios: Turbine manifold pipes of aero-engines, fuel manifolds of rocket propulsors
▶Requirements: High temperature (800 - 900℃), high vibration, lightweight
▶Value: The specific strength (strength/density) of Inconel 718 tee exceeds that of titanium alloy, reducing weight by 15 - 20%; excellent thermal fatigue resistance, capable of withstanding more than 1000 thermal cycles (common alloy tees < 200 cycles).
2.Nuclear Energy Field
▶Scenarios: Coolant manifolds of primary circuits of pressurized water reactors, helium transportation pipelines of high-temperature gas-cooled reactors
▶Requirements: Radiation resistance, resistance to high-temperature and high-pressure water corrosion (300 - 350℃, 15 - 16MPa)
▶Value: Inconel 718 contains niobium, which can inhibit irradiation swelling; in high-temperature and high-pressure water, the corrosion allowance > 2mm (design life 60 years), far exceeding that of carbon steel/stainless steel tees.
3.Marine Engineering
▶Scenarios: Riser manifold tees for deep-sea oil and gas exploitation, high-pressure reverse osmosis (RO) systems for seawater desalination
▶Requirements: Resistance to seawater erosion corrosion, resistance to stress corrosion cracking (SCC) in marine environments
▶Value: In a seawater environment with 3.5% salt content, the pitting potential of Inconel 718 tee > 1.2V (about 0.3V for 316L), avoiding local corrosion caused by chloride ions; SCC resistance improved by more than 5 times.
IV. Processing and Adaptability
1.Hot Working Difficulties
▶Due to high alloying (high niobium and molybdenum contents), forging requires strict temperature control (950 - 1050℃); otherwise, hot cracking is likely to occur. A "small deformation, multiple passes" process is required to ensure uniform structure.
2.Welding Characteristics
▶Suitable for arc welding and plasma welding, with no post-welding cracking tendency (due to the delayed precipitation of γ′′ phase, avoiding welding stress concentration); it is recommended to use matching welding materials (such as ERNiFeCr - 2), and the strength of welded joints can reach more than 90% of the base metal.
3.System Adaptability
▶It can be seamlessly connected with Inconel 718 pipes, flanges, etc., to form an "all-alloy system", avoiding galvanic corrosion from dissimilar material connections; it can also be surface-treated (such as silver plating, nitriding) to adapt to higher cleanliness (such as high-purity gas transportation in the semiconductor industry) or more wear-resistant scenarios (such as powder transportation pipelines).
Summary
Inconel 718 tee is a "customized pipe fitting for extreme working conditions". With its all-round advantages of high-temperature high strength, creep resistance, and corrosion resistance, it has become a "necessary component" in high-end fields such as aerospace, nuclear energy, and marine engineering. Its value is not only in physical connection but also in being the core support for ensuring the "safe, long-life, and high-performance" operation of systems in high-temperature, high-pressure, and strong-corrosion environments.
DINGSCO
Hunan Dinghan New Material Technology Co., Ltd. (DINGSCO) specialized in Nickel Based Corrosion Resistant and High Temperature alloys products which used in the world’s most technically demanding industries and applications.We are dedicated to providing our customers with best quality products, fastest possible deliveries, most competitive prices of Nickel Based Corrosion Resistant and High Temperature alloys in bars, rods, forged flanges, valve parts (Ball, Stem, Seat Ring, etc), forged shapes (shafts, discs, blocks, hubs, rings, cylinders and other custom shapes) according to ASTM, ASME, API, AMS, NACE and other industry standards.
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