nickel alloy UNS N06601 vs nickel-based alloy 617
nickel alloy UNS N06601 is a nickel-chromium-iron alloy with a deliberately high chromium content of 21-25% and aluminum additions, which give it outstanding oxidation resistance at high temperature. It is often used for furnace components and heat-treatment equipment. nickel-based alloy 617 is a nickel-based solid-solution strengthened alloy with high chromium and aluminum content, further strengthened by cobalt and molybdenum. It has good high-temperature strength and plasticity, and is suitable for gas turbine blades, combustion cans, pipelines, petrochemical processing and acid production.
Chemical Composition Compared
The table below lists the composition ranges per ASTM B168 for the two alloys. Note that 601 contains no deliberate cobalt or molybdenum, while 617 contains 10-15% cobalt and 8-10% molybdenum, which is the source of its higher high-temperature strength:
| Element | nickel alloy UNS N06601 | nickel-based alloy 617 |
|---|---|---|
| Nickel (Ni) | 58.0-63.0 | 44.5 min (balance) |
| Chromium (Cr) | 21.0-25.0 | 20.0-24.0 |
| Iron (Fe) | Balance | Max 3.0 |
| Aluminum (Al) | 1.0-1.7 | 0.8-1.5 |
| Titanium (Ti) | 0.3-0.7 | Max 0.6 |
| Carbon (C) | Max 0.10 | 0.05-0.15 |
| Manganese (Mn) | Max 1.0 | Max 1.0 |
| Silicon (Si) | Max 0.50 | Max 1.0 |
| Copper (Cu) | Max 0.50 | Max 0.5 |
| Cobalt (Co) | - | 10.0-15.0 |
| Molybdenum (Mo) | - | 8.0-10.0 |
Mechanical Properties Compared
Typical room-temperature properties of annealed material are shown below. Exact values depend on product form, thickness and heat treatment, so the mill certificate should be verified against the required specification:
| Property | nickel alloy UNS N06601 | nickel-based alloy 617 |
|---|---|---|
| Tensile strength | About 655 MPa | About 760 MPa |
| Yield strength (0.2%) | About 275 MPa | About 345 MPa |
| Elongation | About 40-45% | About 50-60% |
Both alloys retain useful strength well above 800 degrees Celsius, with 617 carrying higher loads at elevated temperature because of its cobalt and molybdenum strengthening.
High-Temperature Performance and Applications
nickel alloy UNS N06601 is optimized for oxidation resistance: its high chromium and aluminum content form a stable, adherent oxide scale in air and combustion atmospheres up to about 1200 degrees Celsius for short periods and about 1150 degrees Celsius for continuous service. Typical applications include radiant tubes, furnace muffles, heat-treatment baskets, thermocouple sheaths and chemical process equipment where scaling resistance matters more than extreme load-bearing strength.
nickel-based alloy 617 combines oxidation resistance with significantly higher creep and rupture strength at high temperature. Typical applications include gas turbine combustion cans and transition pieces, ducting, heat exchangers for chemical processing, and components in petrochemical furnaces and acid production where both temperature and mechanical load are demanding.
How to Choose Between 601 and 617
Choose nickel alloy UNS N06601 when the dominant requirement is oxidation and scaling resistance in hot air, flue gas or furnace atmospheres with moderate mechanical loads; it is the economical choice for furnace and heat-treatment hardware. Choose nickel-based alloy 617 when components must sustain higher stresses at elevated temperature, such as turbine combustion hardware and high-temperature pressure parts, and when resistance to both oxidation and creep is critical. Confirm the product form standard, such as ASTM B168 for plate, sheet and strip, and B166 for 601 bar and B564 for forgings, before ordering.
Frequently Asked Questions
What is the main difference between nickel alloy UNS N06601 and 617? 601 is a nickel-chromium-iron alloy optimized for oxidation resistance with no deliberate cobalt or molybdenum, while 617 is strengthened with 10-15% cobalt and 8-10% molybdenum for higher high-temperature strength and creep resistance.
Does nickel-based alloy 617 contain cobalt? Yes. nickel-based alloy 617 contains 10-15% cobalt per ASTM B168, which together with molybdenum provides its superior high-temperature strength.
Which alloy is better for furnace components? nickel alloy UNS N06601 is usually the better choice for furnace components such as radiant tubes and heat-treatment fixtures, where oxidation and scaling resistance with moderate loads are the main requirements.
Can nickel alloy UNS N06601 and 617 be welded? Yes, both are weldable with matching nickel-based fillers such as ERNiCrFe-2 for 601 and ERNiCrCoMo-1 for 617; clean surfaces and controlled heat input are required to preserve high-temperature properties.
What is the maximum service temperature of nickel alloy UNS N06601? nickel alloy UNS N06601 can be used continuously at temperatures up to about 1150 degrees Celsius in air and intermittently up to about 1200 degrees Celsius, depending on atmosphere and stress.
Are nickel alloy UNS N06601 and 617 covered by the same standard? Both are covered by ASTM B168 for plate, sheet and strip, but they have different UNS designations, N06601 and N06617 respectively, and different composition limits within the standard.
