Inconel 601
Inconel 601 (UNS N06601) is a nickel-chromium-aluminum alloy. Its 1.0–1.7% aluminum addition promotes the formation of a tightly bonded alumina-enriched oxide layer. This alumina scale gives it strong resistance to oxidation and scaling at temperatures up to 1250°C, exceeding what Inconel 600 can handle.
1. Chemical Composition
The elemental breakdown below shows the aluminum content and high chromium level that give Inconel 601 its superior high-temperature scaling resistance.
| Grade | C | Mn | Si | S | Ni | Cr | Fe | Cu | Mo | Ti | Other |
| N06601 | ≤ 0.10 | ≤ 1.50 | ≤ 0.50 | ≤ 0.015 | 58–63 | 21–25 | Bal | ≤ 1.00 | — | — | Al: 1.0–1.7 |
2. Mechanical Properties
The table below lists room-temperature mechanical properties for Inconel 601 in the annealed condition, as applicable to seamless pipe and tube.
| Grade | Standard | Condition | Tensile Strength, MPa (ksi) |
Yield Strength, MPa (ksi) |
Elongation, % | Hardness |
| N06601 | ASTM B163 | Annealed | ≥552（80） | ≥207（30） | ≥30 | — |
| N06601 | ASTM B167 | Cold-worked annealed or hot-worked annealed: All sizes |
≥550（80） | ≥205（30） | ≥30 | — |
3. Equivalent Grade
The table below cross-references Inconel 601 (UNS N06601) with corresponding designations in major international material standards.
| GRADE | UNS | GB | JIS | ISO | DIN/EN | GOST | |
| ISC | NEW | ||||||
| Inconel 601 | N06601 | - | NS312 | NCF601 | - | 2.4851 | - |
4. Key Technical Advantages
- Aluminum-Enhanced Oxide Scale Adhesion: The alumina (Al2O3) enrichment in the surface scale, created by the 1.0–1.7% aluminum addition, is more adherent and less prone to spalling than the chromia scale formed by alloys without aluminum. This allows service at cyclic temperatures up to 1250°C.
- Resistance to Sulfidizing Atmospheres: Inconel 601's chromium-aluminum oxide scale offers better resistance to sulfur-bearing combustion gases than purely chromia-forming nickel alloys. This makes it well suited for oil- and gas-fired furnace components.
- High-Temperature Strength Retention: The alloy keeps useful tensile and creep strength at temperatures where most austenitic stainless steels and Inconel 600 have lost structural capability, particularly in the 900°C–1100°C range.
Technical Note: Inconel 601 should not be used in strongly reducing sulfur-bearing gases or carburizing atmospheres below 800°C, as the protective oxide scale may not form adequately at lower temperatures in these conditions.
5. Common Manufacturing Standards
ASTM B167: Standard Specification for Seamless Pipe and Tube — Nickel-Chromium-Iron Alloys. Covers Inconel 601 (UNS N06601) in seamless tubular form for high-temperature furnace and industrial heating applications.
DIN/EN Standards:
- EN 10216-5: Seamless steel tubes for pressure purposes — stainless and nickel alloy grades (Material No. 2.4851)
- DIN 17742: Nickel alloys — specification
JIS Standards:
- JIS H 4552: Nickel and nickel alloy seamless pipes and tubes
GB/T Standards:
- GB/T 15007: Corrosion-resistant alloy grades (applicable for NS3104 designation)
GOST Standards:
- GOST 14965: Tubes from nickel and nickel alloys
Standards Comparison Table:
| ASTM | EN/DIN | JIS | GB/T | GOST |
| ASTM B167 | EN 10216-5 / DIN 17742 | JIS H 4552 | GB/T 15007 | GOST 14965 |
6. Primary Applications
- High-Temperature Furnace Hardware: Radiant tubes, burner nozzles, and flame shields in heat treatment and ceramics firing furnaces operating continuously above 1000°C.
- Thermal Processing Equipment: Conveyor belts, fixtures, and trays in sintering and annealing furnaces where cyclic oxidation and mechanical load occur at the same time.
- Gas Turbine and Combustion Components: Transition ducts, combustion liners, and hot exhaust section tubing where aluminum-oxide scale adhesion under thermal cycling matters.
- Petrochemical Heater Tubes: Radiation section tubes in direct-fired process heaters handling hydrocarbons at elevated temperatures in sulfur-containing fuel environments.
- Power Generation: Superheater and reheater components in industrial boilers subject to oxidizing flue gas and high thermal flux.