What is the difference between Inconel 625 and INCONEL 725?
We take an in-depth look at these two popular high-performance nickel alloys and compare their specifications and applications.
When you're looking for a quality material for your next project, a high-performance nickel alloy may be just what you need. However, there are several grades to choose from in the INCONEL family, any of which may meet your requirements and needs.
The INCONEL alloy is INCONEL alloy 625, which is one of the most versatile materials ever created. With its excellent corrosion resistance and high strength, it is suitable for a wide range of applications across a wide range of industries. It is a very popular first-choice material that can solve many material problems for design engineers. The fact that it has been doing so for over 50 years and is still commonly used is a testament to its quality.
However, if high strength is a primary consideration, INCONEL alloy 725 may be a better fit. It is similar to INCONEL alloy 625, especially in terms of corrosion resistance. However, there are significant differences between the two, which may affect the decision of which material to use.
To help you understand the differences and similarities between these two special materials, we have compared their key features and properties.
Composition Differences
The reason INCONEL 625 alloy has such a wide range of desirable properties is due to its unique composition. It is a high nickel alloy, with at least 58% nickel in the mix. It also contains chromium (20-23%) and molybdenum (8-10%), as well as added niobium (3.15-4.15%).
Niobium combines with molybdenum and distorts the atomic matrix of the alloy, imparting exceptionally high strength in the annealed condition without the need for specific strengthening heat treatments. The large amounts of nickel and chromium together give the material incredible corrosion resistance, allowing it to withstand highly corrosive elements and environments.
INCONEL 725 alloy shares many of the same constituent elements - in fact, superficially, they are almost identical. It retains large amounts of nickel (55-59%) and chromium (19-22.5%), as well as molybdenum (7-9.50%). As a result, the material has similar corrosion resistance to INCONEL 625 alloy, making it suitable for a wide range of highly corrosive environments.
However, there are subtle differences in the overall composition of the two materials. INCONEL Alloy 625 contains small amounts of cobalt and silver, which are not present in INCONEL Alloy 725. INCONEL Alloy 725 has a higher titanium content (1-1.7% compared to a maximum of 0.4% for INCONEL Alloy 625), with the remainder made up of iron, compared to a maximum of 5% for INCONEL Alloy 625. These small additions and differences allow for the formation of micro-precipitates during heat treatment, which results in significantly higher strength values for INCONEL Alloy 725.
