The nickel, iron, and chromium alloy UNS N09925 has several benefits and advantages. This alloy offers exceptional performance in a variety of applications by combining resistance to corrosion, heat resistance, mechanical and physical qualities, and the ability to be machined and welded. We’ll examine this well-known alloy’s composition, chemical characteristics, mechanical characteristics, physical characteristics, applications, and more in this blog post.
- Incoloy 925 Formula:
UNS N09925 is an austenitic alloy with the following composition: copper (max. 1%), manganese (max. 2%), nickel (min. 39%), iron (min. 38%), chromium (min. 22%), and molybdenum (max. 2%). For better machinability, it additionally has 0.3% phosphorus and 0.2% sulfur.
| Elements | Content (%) |
| Nickel, Ni | 44 |
| Iron, Fe | 28 |
| Chromium, Cr | 21 |
| Molybdenum, Mo | 3 |
| Titanium, Ti | 2.1 |
| Copper, Cu | 1.8 |
| Aluminum, Al | 0.3 |
| Carbon, C | 0.01 |
- The chemical properties of Incoloy 925:
Due to its high chromium content, which forms an oxide film on the metal’s surface and makes it highly resistant to corrosion from acidic environments or chloride solutions containing halides like chlorides or bromides, Incoloy 925 has excellent chemical properties that allow it to withstand both oxidizing and reducing media. Additionally, it maintains good mechanical strength at temperatures as high as 1100°F (593°C).
- The physical properties of Incoloy 925:
UNS N09925’s physical characteristics include strong ductility, which enables it to be easily shaped into a variety of shapes while keeping its strength and integrity at temperatures as high as 1100°F (593°C). Due to its low rate of thermal expansion, it is also perfect for use in components that are subject to thermal shock, such those found in nuclear reactors or power plants, where rapid temperature changes can occur without damaging or deforming the metal components employed in the system.
- Mechanical Properties of Incoloy 925:
Additionally, because of its high fatigue strength, it can be used in rotating parts that are frequently subjected to loading cycles, like bearings or gears in aircraft engines, or in other machinery that needs to function reliably for extended periods of time with little maintenance needed, even in harsh environments like saltwater exposure or temperatures as high as 1200°F (649°C).
| Properties | Metric | Imperial |
| Tensile strength (precipitation hardened, value at room temperature) | 1210 MPa | 175000 psi |
| Tensile strength (@ 550°C/1020°F, precipitation hardened prior to test) | 970 MPa | 141000 psi |
| Yield strength (@ strain 0.200%, precipitation hardened. value at room temperature) | 810 MPa | 117000 psi |
| Yield strength (@ strain 0.200%, temperature 550°C/1020°F, precipitation hardened prior to test) | 700 MPa | 102000 psi |
| Poisson’s ratio | 0.281 | 0.281 |
| Elongation at break (precipitation hardened) | 24% | 24% |
- Resistance to Corrosion:
Since molybdenum helps form protective films on the metal’s surface, Incoloy 925 not only resists corrosion well against acidic environments and chloride solutions containing halides such as chlorides or bromides, but it also offers good resistance against pitting and crevice corrosion. This helps prevent further degradation over time, even when exposed to harsh chemicals like acids or alkalines at elevated temperatures up to 1200°F (649°C).
- Uses for Incoloy 925:
Because it can endure exposure to saltwater without corroding over time and yet provide high wear resistance even when subjected to continual abrasion from sand particles found in seawater during operation, it is a great material for use in marine environments, such as ships. It is also used in oil refineries because of its resistance to deteriorating quickly from frequent contact with petroleum products. This means that it has a long service life and requires little maintenance even when exposed frequently over extended periods of time. This makes it an affordable option for many industries that need reliable performance year after year, regardless of environmental factors like corrosive chemicals, which are commonly found in oil refineries or marine environments around ships that operate offshore for months at a time without experiencing service interruptions due to component failure brought on by the traditional materials used for these types of applications providing insufficient corrosion protection before Incoloy alloys like this one were introduced into global industrial markets, making them widely available today.
- Thermal Processing
A nickel-based superalloy with exceptional corrosion resistance, great strength at high temperatures, and durability to hostile conditions is Incoloy alloy 92. It can be found in reactor vessels or turbocharger components, among other places. The heat treatment of Incoloy 92 is a crucial component of its performance. It can greatly enhance qualities like mechanical strength and machinability, but it must be carefully chosen for each application. Multiple techniques can be used, depending on the required composition and machining technique. For instance, hot isostatic pressing or double-step aging can both boost mechanical strength at high temperatures. To get the intended outcomes, manufacturers need to figure out which combination of techniques works best.
- The process of machining
Machining alloy 925 is a precise process that needs the highest level of attention to detail. There are several industrial uses for this robust nickel-iron-chromium alloy, and machining it calls for sophisticated skills and methods. The hard surface of this alloy must be penetrated using cutting instruments with a carbide substrate. Temperatures must be carefully managed in order to maximize conditions for appropriate chip production and removal as well as a low risk of tool damage. Incoloy 925 may be machined into intricate shapes for usage in a range of commercial and industrial contexts with the right attention to detail and skill.
- Welding:
One method for joining components made of Incoloy 925 alloy is Incoloy 925 welding. Because of its exceptional resistance to oxidation, general corrosion in both reducing and oxidizing acids, and corrosion caused by chloride ions, this alloy is highly sought after. Welds made of this alloy are appropriate for a variety of applications, including parts of oil refineries and chemical processing plants, because of these resistances. Nonetheless, specific procedures must be followed when combining Incoloy 925 parts to guarantee the strongest possible weld. For example, when using the tungsten arc technique for manual welding, neutral argon gas shielding must be supplied and the current must be kept between 80 and 145 amps. Furthermore, manufactured surfaces must always be completely dry before welding is done because even a tiny bit of moisture can significantly weaken the weld. Professionals offering Incoloy 925 welding services can ensure their work will withstand the most demanding and corrosive industrial circumstances by possessing these abilities and procedures.
- In summary
When it comes to industrial applications that require dependable performance under harsh conditions—such as exposure to corrosive chemicals found in refineries or salt water encountered during extended ship operations offshore—Incoloy 925 performs better overall than traditional materials. This has led to an increase in popularity among users who want to extend the lifespan of their components while saving money on maintenance costs because traditional materials are unable to withstand the same level of stress imposed upon them during extended use under extreme environmental conditions encountered day-to-day operations at these types of facilities around the world today, which has increased demand for higher-quality alloys like this one in recent years.