The Special Metals Corporation is a US company that specialises in anti-corrosion alloys. Incoloy is the trade name for their range of stainless steel alloys created from nickel, iron and chromium with the addition of molybdenum and copper. The main Incoloy alloys are:
Incoloy 020 – Designed for use in chemical processing, Incoloy 020 can handle the most acidic environments, including exposure to nitric, sulphuric and phosphoric acid.
Incoloy DS – While it was first developed for woven wire furnace belts, Incoloy DS is now widely employed in a range of heat-treatment applications.
Incoloy MA956 – Initially researched for aerospace applications, MA956 is now used in a wide range of applications due to its high levels of heat resistance.
While Incoloy is sought for its ability to withstand extreme temperatures, its variants have individual properties that make it suitable for many other applications. Incoloy DS, for instance, is able to handle hot combustible gases without any corrosive effects, while Incoloy 825 and 020 are equally resistant to aqueous corrosion. Incoloy DS is also resistant to ‘green rot’ which can occur in other nickel-chromium alloys.
Incoloy’s heat resistance properties come about from the mechanical alloying process (as opposed to bulk melting) in which it is created. This process allows a layer of yttrium particle to form on the surface of the iron-chromium-aluminium alloy, which protects the structure from corrosion.
Incoloy alloy is available in most formats, including sheet, piping, foil, tubes, bar, hexagon and wire. It’s recommended that both the material and tools are warmed to 150° – 200°C before forming.
Clearly, the ability to cope with extreme temperatures makes Incoloy alloys perfect for industries involving heat processing, such as furnaces. Incoloy 020’s properties makes this alloy ideal for chemical processing plants, due to its ability to withstand both acidic and alkalinic environments. Other uses include:
- Nuclear industry
- Petroleum industry
- Food processing
- Domestic appliances
Incoloy was proposed as a possible alloy for components on a nuclear space reactor to be installed on a proposed spacecraft to explore the moons of Jupiter.
Chemical Composition of Incoloy 825
|Ni||38 – 46 %|
|Mo||2.5 – 3.5 %|
|Cr||19.5 – 23.5%|
|Cu||1.5 3 %|
|Ti||0.6 – 1.2 %|
|Fe||22 % min|
Typical Properties of Incoloy 825
|Density||8.14 g/cm3||0.294 lb/in3|
|Co-Efficient of Expansion||14.0 µm/m.°C
|Modulus of Rigidity||75.9 kN/mm2||11009 ksi|
|Modulus of Elasticity||196 kN/mm2||28428 ksi|