ASTM B407 Incoloy 800H seamless pipe is an iron-nickel-chromium-based austenitic high-temperature alloy with excellent high-temperature stability and corrosion resistance. Adhering to the ASTM B407 standard, this material maintains stable performance in environments up to 1100°C, exhibiting exceptional creep rupture strength above 600°C.
In terms of corrosion resistance, the high nickel content provides excellent resistance to stress corrosion cracking, while the high chromium content enhances resistance to pitting and crevice corrosion, providing good resistance to media such as nitric acid and organic acids.
Manufacturing requires precision metallurgy, hot or cold working, and solution heat treatment at a temperature of no less than 1121°C.
Incoloy 800H Seamless Tube Composition
|
Composition |
Value(%) |
Main Function |
|
Ni |
30.0 - 35.0 |
It stabilizes the austenite phase, providing excellent resistance to reducing media corrosion and stress corrosion cracking. |
|
Cr |
19.0 - 23.0 |
It forms a dense Cr₂O₃ oxide film on the surface, imparting resistance to high-temperature oxidation and acidic media corrosion. |
|
Fe |
- |
As one of the matrix elements of the alloy, it forms the solid solution foundation along with nickel and chromium. |
|
C |
0.05 - 0.10 |
Compared to Alloy 800 (C ≤ 0.10), its lower limit is increased to significantly enhance high-temperature creep strength through solid solution strengthening and carbide formation. |
|
Al |
0.15 - 0.60 |
It interacts with titanium to form a stable γ' phase (Ni₃(Al,Ti)), enhancing high-temperature strength. It also plays a beneficial role in the surface oxide film. |
|
Ti |
0.15 - 0.60 |
It synergistically strengthens with aluminum and combines with carbon to form stable titanium carbide (TiC), preventing the formation of chromium carbides at grain boundaries, thereby improving intergranular corrosion resistance. |
|
Mn |
≤ 1.50 |
It improves hot workability and acts as a deoxidizer to help purify the melt. |
|
Si |
≤ 1.00 |
It is primarily used as a deoxidizer during the melting process and also helps improve high-temperature oxidation resistance. Trace residual elements must be strictly controlled to avoid adverse effects on hot workability. |
|
Cu |
≤ 0.75 |
Impurity elements must be strictly controlled to minimize their detrimental effects on toughness and weldability. |
|
P |
≤ 0.030 |
Harmful impurities can form low-melting-point sulfides, significantly degrading hot workability and weld toughness, and therefore must be strictly limited. |
|
S |
≤ 0.015 |
It stabilizes the austenite phase, providing excellent resistance to reducing media corrosion and stress corrosion cracking. |
Incoloy 800H Seamless Tube Physical Properties
Density and Melting Point
Incoloy 800H has a density of approximately 8.0 g/cm³ and a melting point range of 1350°C to 1400°C. This high melting point ensures structural stability and solid-state strength in high-temperature applications.
Coefficient of Thermal Expansion and Thermal Conductivity
The alloy's linear thermal expansion coefficient is approximately 13.5-14.2 × 10⁻⁶/°C from 20°C to 100°C. This relatively moderate expansion helps reduce internal stresses caused by thermal expansion and contraction during high-temperature cycling, improving component dimensional stability.
Its thermal conductivity is approximately 12.4 W/(m·K) at room temperature and increases with temperature (for example, reaching 17.8 Btu·ft/ft²·hr·°F at 1800°F/approximately 982°C). This ensures efficient heat transfer and prevents localized overheating, making it particularly suitable for applications requiring high heat transfer, such as heat exchanger tubes.
Electromagnetic Properties and Elastic Modulus
Incoloy 800H has a room temperature resistivity of approximately 1.0 × 10⁻⁶ Ω·m and is nonmagnetic at all temperatures. This property makes it ideal for nuclear power plant components and equipment requiring resistance to electromagnetic coupling. Its elastic modulus of approximately 196 GPa provides the necessary rigidity to maintain dimensional integrity under mechanical loads or internal pressure.
These physical properties together determine the material's behavior in high-temperature environments. For example, its moderate coefficient of thermal expansion combined with good thermal conductivity reduces the risk of thermal fatigue cracking during rapid startup and shutdown or temperature fluctuations. Its high melting point and nonmagnetic properties ensure its stability in complex electromagnetic and high-temperature environments, such as those in nuclear reactors and chemical plants.
Incoloy 800H Seamless Tube Mechanical Properties
Room-Temperature Strength and Ductility
Incoloy 800H exhibits balanced strength and ductility at room temperature. Its typical tensile strength is no less than 450 MPa, its yield strength no less than 180 MPa, and its elongation can exceed 30%.
High-Temperature Strength and Creep Resistance
At 700°C, its tensile strength remains above approximately 170 MPa. By controlling the carbon content within the 0.05%-0.10% range and combining it with a coarse grain structure, its creep-rupture resistance is significantly enhanced. This property effectively resists slow plastic deformation and fracture under long-term high-temperature stress conditions, making it suitable for high-stress environments exceeding 900°C.
High-Temperature Oxidation and Carburization Resistance
Incoloy 800H exhibits excellent resistance to oxidation and carburization at high temperatures. Its high chromium content forms a stable protective chromium oxide film on the surface, ensuring excellent oxidation resistance at temperatures up to 1100°C. At the same time, the alloy composition effectively resists carbon penetration, preventing embrittlement.
Toughness and Hardness Properties
This alloy exhibits excellent toughness at both room and low temperatures, with a Brinell hardness typically ranging from 135-179 HB.
This moderate combination of hardness and toughness ensures that the material effectively absorbs energy under impact loads, preventing brittle fracture.
Fatigue Performance and Stability
Incoloy 800H's face-centered cubic lattice structure imparts excellent thermal fatigue resistance. Under conditions of frequent temperature fluctuations, the material can withstand the cyclic stresses caused by thermal expansion and contraction, reducing the risk of thermal fatigue crack initiation. Furthermore, the optimized titanium-carbon ratio enhances structural stability, providing excellent resistance to sensitization and intergranular corrosion.
Incoloy 800H Seamless Tube Specification
The seamless pipes are available in a wide range of ODs, from 6 mm to 250 mm, with wall thicknesses from 1 mm to 20 mm. Standard cut lengths are typically 12 meters. For pipes with ODs less than 114 mm, wall thicknesses as low as 0.2 mm are possible.
Strict dimensional tolerances are important to ensuring equipment manufacturing accuracy and safety. For example, for a pipe with an outer diameter of 141.3 mm and a wall thickness of 18.5 mm, the outer diameter tolerance is typically required to be within ±1.2 mm, the wall thickness tolerance is ±4.6 mm, and the length tolerance is ±5.0 mm.
