Inconel 600
Inconel 600 (UNS N06600) is a nickel-chromium alloy developed for high-temperature oxidation and carburising resistance. It resists chloride-ion stress-corrosion cracking and maintains its structural integrity in both reducing and moderately oxidising environments up to 1093°C (2000°F) due to the high nickel content that is well above 72%.
1. Chemical Composition
The table below provides the key alloying elements for Inconel 600. The high nickel base and chromium level define its thermal and chemical resistance.
| Grade | C | Mn | Si | S | Ni | Cr | Fe | Cu | Mo | Ti | Other |
| N06600 | ≤ 0.15 | ≤ 1.00 | ≤ 0.50 | ≤ 0.015 | ≥ 72 | 14–17 | 6–10 | ≤ 0.50 | — | — | — |
2. Mechanical Properties
The values below apply to Inconel 600 pipe and tube in the annealed condition, balancing elevated-temperature strength with ductility.
| Alloy | Standard | Condition | Tensile Strength, MPa (ksi) |
Yield Strength, MPa (ksi) |
Elongation, % | Hardness |
| N06600 | ASTM B163 | Annealed | ≥552（80） | ≥241（35） | ≥30 | — |
| N06600 | ASTM B163 | Higher Yield | ≥552（80） | 276–448 (40–65) | ≥30 | — |
| N06600 | ASTM B167 | Hot-worked annealed, OD≤5 inch (127mm) | ≥550（80） | ≥205（30） | ≥35 | — |
| N06600 | ASTM B167 | Hot-worked annealed, OD>5 inch (127mm) | ≥515（75） | ≥170（25） | ≥35 | — |
| N06600 | ASTM B167 | Cold-worked annealed: OD≤5 inch (127 mm) | ≥550（80） | ≥240（35） | ≥30 | — |
| N06600 | ASTM B167 | Cold-worked annealed: OD>5 inch (127mm) | ≥550（80） | ≥205（30） | ≥35 | — |
3. Equivalent Grade
The table given below consists of a list of international standard designations that are equivalent to Inconel 600 (UNS N06600).
| GRADE | UNS | GB | JIS | ISO | DIN/EN | GOST | |
| ISC | NEW | ||||||
| Inconel 600 | N06600 | - | NS3102 | NCF600 | - | 2.4816 | - |
3. Key Technical Advantages
- High-Temperature Oxidation Resistance: Chromium at 14–17% forms a stable oxide scale that resists spalling during thermal cycling. This makes Inconel 600 suitable for continuous service up to 1093°C (2000°F) in air and oxidising combustion atmospheres.
- Resistance to Carburising and Nitriding Atmospheres: The high nickel base slows carbon diffusion into the metal matrix, preventing internal carburisation in furnace retort and heat-treating equipment at elevated temperatures.
- Immunity to Chloride Stress Corrosion Cracking: Inconel 600's high nickel content makes it immune to chloride-induced SCC in aqueous environments, unlike austenitic stainless steels. This property is important for steam generators and nuclear service.
Technical Note: Inconel 600 is susceptible to Primary Water Stress Corrosion Cracking (PWSCC) in high‑purity water at temperatures above approximately 300°C under conditions of elevated stress and susceptible grain boundary microstructure. For such nuclear pressurised water reactor (PWR) environments, Inconel 690 is the preferred alternative.
4. Common Manufacturing Standards
- ASTM B167: Standard Specification for Seamless Pipe and Tube — Nickel-Chromium-Iron Alloys (UNS N06600, N06690, N06025, N06045). This is the primary specification for Inconel 600 pipe and tube in heat exchangers, furnaces, and nuclear applications.
- ASTM B163: Standard Specification for Seamless Nickel and Nickel Alloy Condenser and Heat Exchanger Tubes — seamless nickel and nickel alloy condenser and heat exchanger tubes, including N06600.
- DIN/EN Standards:
EN 10216-5: Seamless steel tubes for pressure purposes — stainless and nickel alloy grades
DIN 17752: Nickel and nickel alloy seamless tubes for general engineering purposes - JIS Standards: JIS H 4552: Nickel and nickel alloy seamless pipes and tubes
- GB/T Standards: GB/T 14976: Seamless stainless and heat-resisting steel pipes (applicable for the corresponding Chinese designation)
Summary Table — Standard Equivalents:
| ASTM | EN/DIN | JIS | GB/T | GOST |
| ASTM B167 | EN 10216-5 / DIN 17752 | JIS H 4552 | GB/T 14976 | TU 14-3-669 |
5. Primary Applications
- Industrial Furnace Components: Retort tubes, muffles, and radiant tubes in carburising and gas-fired heat treatment furnaces that need resistance to thermal shock and carburising atmospheres.
- Nuclear Steam Generators: Tubes in pressurised water reactor heat exchangers where chloride SCC immunity in high-temperature water is required.
- Chemical Processing: Reaction vessels and transfer tubing for chlorinated solvents and caustic solutions at elevated temperatures.
- Aerospace and Gas Turbine: Combustion liner tubing, thermocouple protection sheaths, and hot-zone exhaust components exposed to cyclic high-temperature oxidation.
- Chlor-Alkali Production: Diaphragm cell components and piping in caustic soda and chlorine service, where both corrosion resistance and thermal stability are needed.