1. What is the chemical composition of UNS N07718, C276, and Inconel 800H?
Answer:
UNS N07718 (Inconel 718): Nickel 50–55%, Chromium 17–21%, Iron 17% max, Niobium + Tantalum 4.75–5.5%, Molybdenum 2.8–3.3%, Cobalt 1% max.
C276 (Hastelloy C276): Nickel 57%, Molybdenum 15.5–17%, Chromium 15.5–17%, Iron 4%, Tungsten 3–4%, Cobalt ≤2%, Copper ≤1%.
Inconel 800H: Nickel 30–35%, Iron 39.5–49.5%, Chromium 19–23%, Carbon ≤0.10%, Aluminum 0.15–0.60%.
2. What are the common applications of these nickel alloy pipes and tubes?
Answer: These pipes are used in industries requiring high corrosion resistance and high-temperature strength:
Chemical and petrochemical plants
Marine and offshore engineering
Power generation equipment (boilers, heat exchangers)
Aerospace components
Nuclear industry
3. What mechanical properties can be expected from these alloys?
Answer: Typical properties (may vary by heat treatment):
Inconel 718: Tensile strength 124 ksi (855 MPa), yield strength 103 ksi (710 MPa), elongation 12–20%.
C276: Tensile strength 80–120 ksi, yield strength 35–75 ksi, elongation 30–40%.
Inconel 800H: Tensile strength 70 ksi (480 MPa), yield strength 30 ksi (205 MPa), elongation 40%.
4. What standards and certifications do these pipes comply with?
Answer: They typically meet:
ASTM B564 (Inconel 718) / ASTM B622 (C276) / ASTM B409 (800H)
ASME B31.3 for pressure piping
ISO 9001 certified manufacturing
Material Test Certificates (MTC) according to EN 10204 3.1
5. How is the corrosion resistance of these nickel alloys?
Answer:
Inconel 718: Excellent resistance to oxidation and high-temperature corrosion, good for moderately aggressive chemical environments.
C276: Outstanding resistance to strong oxidizing and reducing agents, including hydrochloric and sulfuric acids.
Inconel 800H: Good resistance to high-temperature oxidation and carburization; suitable for furnace components and heat exchangers.
