Whether you are a supplier or a end user of Monel alloys, you may face challenges when deciding between Monel 400 alloy and Monel K-500 or advising customers on material selection.
Should you opt for Monel 400 or Monel K-500? In what applications are each of these alloys best suited?
If you have these questions, this article is essential reading. It will clarify the similarities and differences between Monel 400 and Monel K-500, serving as your guide for making informed Monel material choices.
MONEL® nickel-copper alloy 400 (UNS N04400 / W.Nr. 2.4360 and 2.4361) is a solid-solution alloy that can be hardened only by cold working. It has high strength and toughness over a wide temperature rangeand excellent resistance to many corrosive environments.
What is Monel Alloy K-500?
MONEL® alloy K-500 (UNS N05500 / W.Nr. 2.4375) is a nickel-copper alloy which combines the excellent corrosion resistance of MONEL alloy 400 with the added advantages of greater strength and hardness. The increased properties are obtained by adding aluminum and titanium to the nickel-copper base.
Monel Alloy 400 Vs. Alloy K-500 Chemical Composition
Here is a comparison table for the chemical composition of Alloy 400 and Alloy K-500:
Monel Alloy 400 Vs. Alloy K-500 Corrosion Resistance
Monel 400 and Monel K-500 alloys both have a high nickel and copper content, resulting in a similar specific gravity.
The substantial nickel and copper composition grants both alloys excellent corrosion resistance, making them ideal for use in seawater and chemical industries.
Monel Alloy 400 Vs. Alloy K-500 Mechanical Behavior
Monel 400 is a solid-solution strengthened single-phase alloy, whereas Monel K-500, enhanced with aluminum and titanium, is a precipitation-strengthened multi-phase alloy.
This fundamental distinction makes Monel K-500 superior to Monel 400 in terms of strength and hardness.
However, Monel 400 offers better toughness compared to K-500.
For applications requiring higher strength and hardness, Monel K-500 is the preferred choice. Conversely, if greater toughness is needed, Monel 400 is the better option.
Monel Alloy 400 Vs. Alloy K-500 Physical Properties
The most significant difference in the physical properties of Monel 400 and Monel K-500 lies in their magnetic characteristics.
Monel 400 can be magnetic at certain temperatures and non-magnetic at others.
While Monel K-500 may develop a magnetic layer on the surface during processing, it becomes completely non-magnetic after pickling.
Therefore, if you need an alloy that remains consistently non-magnetic during use, Monel K-500 is the better choice.
A comparison of other physical properties between Monel 400 and Monel K-500 is as follows:
| Monel 400 | Monel K-500 | |
|---|---|---|
| Density, g/cm³ | 8.80 | 8.44 |
| Density, lb/in.³ | 0.318 | 0.305 |
| Melting Range, °F | 2370-2460 | 2400-2460 |
| Melting Range, °C | 1300-1350 | 1315-1350 |
| Tension | 26.0 | 26.0 |
| Compression | 26.0 | |
| Torsion | 9.5 | 9.5 |
| Poisson’s Ratio | 0.32 | 0.32(aged material) |
| Curie Temperature, °F | 70-120 | |
| Curie Temperature, °C | 21-49 |
Monel Alloy 400 Vs. Alloy K-500 Heat Treatment
Due to their distinct strengthening mechanisms—solid solution strengthening for Monel 400 and precipitation strengthening for Monel K-500—the final heat treatments for these alloys differ significantly.
Monel 400 undergoes solid-solution treatment to fully dissolve the solid-solution strengthening elements into the alloy matrix. In contrast, Monel K-500 uses aging treatment during the final heat treatment to precipitate the strengthening phase fully, thereby achieving optimal strengthening.
Monel Alloy 400 Vs. Alloy K-500 Application
Monel K-500’s higher strength and hardness make it more suitable for applications requiring increased mechanical properties, while Monel 400’s superior toughness makes it ideal for applications where higher ductility is beneficial. Both alloys offer excellent corrosion resistance, making them suitable for harsh environments.
Monel 400 is mostly used for corrosion-resistant containers and connectors. While Monel K-500 is used in environments with high stress and high pressure.
Monel Alloy 400 Vs. Alloy K-500 Main Standards
Here is a comparison table for the main standards of Alloy 400 and Alloy K-500:
Monel Alloy 400 Vs. Alloy K-500 Cost
Monel K-500 contains a higher concentration of alloying elements, resulting in greater deformation resistance and lower plasticity, which complicates the production process.
Consequently, the production costs for Monel K-500 are higher, leading to a higher market price.
If your application does not require the enhanced strength and non-magnetic properties of Monel K-500, opting for Monel 400 is a more cost-effective choice.
Conclusion
Monel 400 is a solid-solution strengthened alloy, while Monel K-500 is a precipitation-strengthened alloy. Overall, Monel K-500 offers superior performance compared to Monel 400.
Both alloys exhibit excellent corrosion resistance.
Monel 400 can be magnetic under certain conditions, whereas Monel K-500 remains non-magnetic in all situations.
For applications where Monel 400 meets performance requirements, it is recommended to choose it to reduce costs.
HZW Alloys produces cost-effective Monel 400 and Monel K-500 alloy products. If you have specific needs, please do not hesitate to contact our engineering team.
