ThePipingMart Blog Grades 908 Incoloy Alloy (UNS N09908) – Composition, Properties and Uses

908 Incoloy Alloy (UNS N09908) – Composition, Properties and Uses

Incoloy 908

UNS N09908 is a nickel-iron-chromium alloy that offers outstanding resistance to high-temperature corrosion and oxidation. It is a high-performance alloy commonly used in the aerospace, chemical processing, and power generation industries. This blog post will provide an overview of Incoloy 908 composition, properties, uses, corrosion resistance, heat resistance, heat treatment, machining, and welding.

Incoloy 908 Composition

UNS N09908 is composed primarily of iron (32-41%), nickel (19-23%), chromium (17-21%), and molybdenum (2.5-3%). It also contains smaller amounts of other elements such as silicon (.75-1.25%), manganese (1.0-1.5%), and copper (.50-.80%). This composition creates an alloy with excellent mechanical strength and oxidation resistance at high temperatures making it ideal for applications in extreme conditions.

Element Content (%)
Nickel, Ni 47 – 51
Iron, Fe 35.588 – 44.6
Chromium, Cr 3.75 – 4.5
Niobium, Nb (Columbium, Cb) 2.7 – 3.3
Titanium, Ti 1.2 – 1.8
Manganese, Mn ≤1
Aluminum, Al 0.75 – 1.25
Cobalt, Co ≤0.50
Copper, Cu ≤0.50
Silicon, Si ≤0.50
Carbon, C ≤0.030
Phosphorous, P ≤0.015
Boron, B ≤0.012
Sulfur, S ≤0.0050

Incoloy 908 Physical Properties

UNS N09908 has excellent mechanical strength even at elevated temperatures up to 2200°F (1200°C). Its elevated temperature tensile strength is approximately 20%-30% higher than 304 stainless steel. Its yield strength increases with increasing temperature rather than decreasing, as is typical with most other alloys; this makes it highly desirable for applications that require parts that can withstand extreme temperatures without losing their structural integrity or becoming brittle over time. It also exhibits good formability even at high temperatures, which enables it to be easily machined or welded into complex shapes without sacrificing its mechanical properties.

Properties Metric Imperial
Density 8.17 g/cm3 0.295 lb/in3
Melting point 1361-1410°C 2482-2570°F

Incoloy 908 Chemical Properties

UNS N09908 is a valuable alloy for many industrial applications thanks to its range of properties. It has excellent resistance to corrosion and oxidation, good mechanical strength at high temperatures and cryogenic conditions, and superior welding characteristics. Furthermore, this nickel-based alloy has remarkable thermal stability when exposed to carburizing atmospheres, making it ideal for furnace muffles, retorts, and industry kilns. Incoloy 908 can also handle higher levels of sulfur compounds than most alloys used in similar applications. This combination of properties makes it suitable for use in aggressive environments like petrochemical manufacturing activities. Incoloy 908 is truly an innovative alloy with comprehensive chemical properties, making it an excellent choice for many industries.

Incoloy 908 Mechanical Properties

UNS N09908 is austenitic stainless steel known for its excellent properties and performance. It has higher tensile strength, greater yield strength and better corrosion resistance than other alloys. This alloy can handle temperatures up to 1200 degrees Fahrenheit with no loss of mechanical properties, making it ideal for use in applications where increased heat, heavy load, or caustic substances are present. Additionally, Incoloy 908 features superior formability when cold-worked and is accessible to weld due to its flexibility. With so many distinct advantages, Incoloy 908 provides the perfect blend of stability and corrosion protection for various industrial uses.

Properties Metric Imperial
Tensile strength 1172 MPa 170000 psi
Yield strength 827 MPa 120000 psi
Elongation at break 12% 12%

Incoloy 908 Uses

Due to its unique mechanical properties and corrosion resistance, UNS N09908 is used in various industries. In the aerospace industry, it is used in jet engines because of its ability to withstand harsh environments, such as those found in jet engines, while still providing superior strength and durability under extreme operating conditions. In the chemical processing industry, it is used in pumps and valves due to its ability to resist corrosion from many chemicals, including acids, bases, halides and organic compounds. In the power generation industry, it is often used in turbines because it can withstand extreme temperatures without losing structural integrity over time or becoming brittle under pressure or stress fatigue.

Incoloy 908 Thermal Properties

Properties Metric Imperial
Thermal expansion co-efficient (@93°C/199°F) 8.59 µm/m°C 4.77 µin/in°F
Thermal conductivity 11.05 W/mK 76.69².°F

Corrosion Resistance

Incoloy 908 is an ultra-high-performance alloy renowned for its incredible corrosion resistance. It is an age-hardenable nickel-iron-chromium superalloy designed and optimized for high-temperature environments where traditional alloys fail by caving to corrosion. As such, Incoloy 908 provides excellent structural integrity in extreme temperatures. In addition to stellar corrosion protection, Incoloy 908 also boasts enhanced strength, improved ductility and weldability, and an overall ability to maintain consistent performance under the harshest conditions, making it a choice material for industries ranging from water and wastewater handling to aerospace engineering.

Heat Resistance

Incoloy 908 is a high-performance alloy which offers excellent heat resistance in severely corrosive environments. This resistance is derived from its phenomenal ability to resist oxidation, carburization and nitridation when wielded at temperatures ranging from 800-up to 1500F (ca. 427-815C). This makes it an ideal material for various applications such as heat-treating equipment, refractory anchors and exhaust systems where potent temperatures are likely encountered. Furthermore, Inconel 908 affords good toughness and creep strength in both oxidizing and reducing atmospheres, complementing its ability to excel in extreme temperatures.

Heat Treatment

Heat treatment of Incoloy 908 is essential for proper performance and function. The heat treatments vary depending on the desired result but typically involve different heating, cooling and tempering stages to achieve a combination of properties such as strength, toughness, ductility or fatigue resistance. Common heat treatment techniques for Incoloy 908 are annealing, hardening and quenching, and normalizing. There are many ways to go about heat treating Incoloy 908. Still, all methods should be conducted with precise control over the temperature and time variables due to the alloy’s sensitivity to thermal variation. Experienced technicians who understand the accurate parameters and methodologies specific to this alloy can help ensure that the proper heat treatment of Incoloy 908 is being carried out to meet your project requirements.


Incoloy 908 machining requires a delicate touch and great attention to detail. This premium alloy offers many desirable features for many industries, such as extreme corrosion resistance and strength at high temperatures. Mastering the correct techniques is essential to achieve accurate results with Incoloy 908. Unique cooling mechanisms, such as liquid nitrogen or dry ice, are recommended when challenging machining geometries. Adhering to proper cutting speeds and using only the highest quality tools configured explicitly for working with this material will ensure precision parts every time.


Incoloy 908 welding is a powerful and valuable tool in many industrial applications. It involves joining two pieces of metal by heating or melting them together at extremely high temperatures, often with the help of an electric arc or a gas flame. Various specialized welding techniques can be used to join Incoloy 908, such as tungsten inert gas welding, manual metal arc welding, and suspended electrode arc welding. The finished product will be sturdy and reliable due to the extreme heat that Incoloy 908 is exposed to during the process. Moreover, this weld is incredibly resistant to corrosion and rusting, making it a dependable solution for wastewater or highly acidic industries.


In conclusion, Incoloy 908 is a nickel-iron-chromium alloy that provides outstanding resistance to high-temperature corrosion and oxidation while maintaining excellent mechanical properties even at elevated temperatures up to 2200°F (1200°C). It has many uses across many industries, such as aerospace, chemical processing and power generation, due to its versatility and wide range of properties which enable it to perform well under various conditions without compromising on quality or performance levels over time or being prone to cracking due to stress fatigue like some other alloys are inclined to do when exposed to extreme environments for extended periods. If you need an alloy that can stand up against harsh environments while still providing superior performance levels, then Incoloy 908 could be the perfect choice for your application!

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