Overview
Both Inconel 600 and Inconel 625 are solid solution strengthened Inconel alloys.
Due to some chemical composition differences, these two alloys have different corrosion resistance and strength.
This article will compare these two alloys from various aspects to better enable you to make the right choice in the project.
Basic Information
Name
Inconel 600
UNS N06600
W.Nr. 2.4816
Brand
INCONEL®
Matrix
Type
Solid Solution
Strengthened Alloy
Density
8.47 g/cm³
Use Temperature
High Temperature
Name
Inconel 625
UNS N06625
W.Nr. 2.4856
Brand
INCONEL®
Matrix
Type
Solid Solution
Strengthened Alloy
Density
8.44 g/cm³
Use Temperature
High Temperature
Introduction
Inconel 600
INCONEL® (nickel-chromium-iron) alloy 600 (UNS N06600 / W.Nr. 2.4816) is a standard engineering material for applications which require resistance to corrosion and heat. The alloy also has excellent mechanical properties and presents the desirable combination of high strength and good workability.
Inconel 625
INCONEL® nickel-chromium alloy 625 (UNS N06625 / W.Nr. 2.4856) is used for its high strength, excellent fabricability (including joining), and outstanding corrosion resistance. Service temperatures range from cryogenic to 1800°F (982°C).
Chemical Composition
Purity
Inconel 600
lose
Inconel 625
WIN
It can be seen from the comparison of chemical composition that alloy 625 has stricter control on the content of impurity elements (phosphorus and manganese) than alloy 600. Therefore, the higher purity of alloy 625 also achieves its better performance.
Phosphorus
Phosphorus plays a dual role in superalloys.
There is no specified range of phosphorus content in alloy 600. If the phosphorus content is too large, it will lead to the precipitation of harmful phases, thereby affecting the properties of the alloy.
In alloy 625, the phosphorus content is carefully designed. Because a small amount of phosphorus can improve the creep performance in superalloys, this effect reaches its peak when the phosphorus content is 0.016%. Therefore, Inconel 625 alloy is designed to use this principle to achieve better creep strength.
Manganese
Manganese in high-temperature alloys will reduce the creep performance, and alloy 625 controls the manganese content more strictly than alloy 600. This makes 625 alloy further have better creep strength.
Corrosion Resistance
Inconel 600
Lose
Inconel 625
Win
Nickel
In nickel alloys, the nickel element itself plays a very good role in corrosion resistance, so Inconel 600 and Inconel 625 are both very excellent corrosion resistant alloys.
Chromium
Alloy 625 has a higher chromium content than Alloy 600. The chromium content is the main element of the alloy's oxidation resistance. Therefore, Inconel 625 has better antioxidant capacity than Inconel 600.
Molybdenum
Alloy 600 does not contain molybdenum, while alloy 625 contains more than 8% molybdenum, which makes alloy 625 also have a certain resistance to reduction. This is not available in Alloy 600.
Therefore, in contrast, Inconel 625 obviously has better comprehensive corrosion resistance.
Mechanical Behavior
Inconel 600
Lose
Inconel 625
Win
Molybdenum
Due to the large atomic radius, molybdenum is a very ideal solid solution strengthening element.
As mentioned earlier, the content of molybdenum gives alloy 625 the ability to resist reduction. At the same time, after solid solution, the molybdenum content also significantly improves the strength of alloy 625.
Niobium and Tantalum
Similar to molybdenum, niobium and tantalum also have a very large atomic radius. Therefore, as solid solution strengthening elements, they also improve the mechanical properties of alloy 625.
At the same time, during the heat treatment, part of niobium and tantalum will also form a γ" precipitation strengthening phase, which further enhances the strength of 625.
Aluminum and Titanium
Although Inconel 625 alloy is a solid solution strengthened alloy (in the initial design, aluminum and titanium were added only for refining), a part of γ' precipitation strengthening phase will still be precipitated in it. Thereby further improving performance.
Chromium
When the chromium content is in the range of 20% to 25%, a short-range orderly strengthening method will be produced. The chromium content of alloy 625 is precisely designed to be within this range. Thereby increasing the strength.
Cobalt
In nickel-based superalloys, cobalt can reduce the stacking fault energy of the alloy. This also increases the strength of the alloy.
Physical Properties
| Inconel 600 | Inconel 625 | |
|---|---|---|
| Density, g/cm³ | 8.47 | 8.44 |
| Density, lb/in.³ | 0.306 | 0.305 |
| Melting Range, °F | 2470-2575 | 2350-2460 |
| Melting Range, °C | 1354-1413 | 1290-1350 |
| Permeability at 200 oersted (15.9 kA/m) | 1.010 | 1.0006 |
| Curie Temperature, °F | -192 | <-320 |
| Curie Temperature, °C | -124 | -196 |
Application
Inconel 600
It can be seen that due to the higher strength and better corrosion resistance of Inconel 625, it has a wider range of applications than Inconel 600 alloy.
Supported Products
Inconel 600
Main Standards
Inconel 600
Condenser and Heat Exchanger Tube: ASTM B163
Seamless Pipe and Tube: ASTM B167, ASTM B829
Welded Pipe: ASTM B517, ASTM B775
Welded Tube: ASTM B516, ASTM B751
Welded Fittings: ASTM B366
Rod, Bar, and Wire: ASTM B166
Forgings: ASTM B564
Plate, Sheet, and Strip: ASTM B168, ASTM B906
Inconel 625
/
Seamless Pipe and Tube: ASTM B444, ASTM B829
Welded Pipe: ASTM B705, ASTM B775
Welded Tube: ASTM B704, ASTM B751
Welded Fittings: ASTM B366
Rod and Bar: ASTM B446
Forgings: ASTM B564
Plate, Sheet, and Strip: ASTM B443
Price
Inconel 600
LOW
Inconel 625
high
Alloy 625 has a higher degree of alloying (more complex composition), more difficult processing, and better performance. So its price will be much higher than Inconel 600.
If alloy 600 can be fully qualified for your project, we recommend that you choose Inconel 600 alloy first to save costs.
Conclusion
Due to the higher content of chromium and molybdenum, the overall corrosion resistance of Inconel 625 alloy is better than that of Inconel 600.
Due to the combined effect of various strengthening elements, alloy 625 has better mechanical properties than alloy 600.
The result of better performance and more complex composition is a higher price, so the lower price alloy 600 is preferred if possible.
AEETHER CO., LIMITED produce cost-effective Inconel 600 and Inconel 625 products. If you have corresponding needs, please do not hesitate to contact us:
