Alloys are a metals that are combined with other elements, often defined by their metallic bonding characteristic. Superalloys, on the other hand, are alloys that exhibit high resistance to thermal deformation and and corrosion and oxidation. Similarly, superalloys also have good surface stability and have excellent mechanical integrity and strength (an inability to be easily deformed through mechanical means). Extreme amounts of heat or mechanical stress are required to deform a superalloy, making them perfect for any high-temperature and high-stress work processes.
The three classes of superalloys most used are nickel-based, iron-based, and cobalt-based. These classes are equally divided into four separate classes, of which they have appeared in mechanical processes: structural steels, tool and die steels, magnetic alloys, and stainless and heat-resisting steels.
QQ N 281 and Monel 400 (Nickel 400)
QQ N 281, one of the sheet types of Monely 400, is a highly-resistant material that can stand up to even the worst of acids and corrosion. In some chemical cases, these QQ N 281 plates can stand up to fires in conditions of pure oxygen, too. Similarly, these products can manage to retain their shape and strength even under extreme temperatures, keeping their structure up to 2,372 degrees Fahrenheit. Because of their protective characteristics against corrosion and acidification, QQ N 281 is preferred for use in the chemical engineering industry.
A similar product, Nickel 405 has properties like Monel 400, but wherein 63% of the Nickel will be alloyed with Copper, Iron, and other trace elements like Sulfur or Silicon — of which further strengthen the alloys uses for industries like oil refinery, sulfuric acid plants, and nuclear vessels.
QQ N 286 and Monel K500 (Nickel 500)
With the addition of small amounts of aluminum and titanium, K500 and QQ N 286 differ slightly from Monel 400 and QQ N 281 in its ability to withstand the same levels of corrosion while also having a greater strength. The reason being is K500 has gamma prime formation — an intermetalic phase where the crystalline structure of the metal is closely aligned to better the strength of the material — completed while aging, making the metal structurally stronger under certain temperatures.
Corrosion resistance of steel will vary dependent on the grade of the alloy. The most common of steel alloys are that of stainless steel 304 and stainless steel 316. Stainless steel 304 is the most common grade used among a variety of industries, particularly due to its corrosion properties. 304 is highly resistant against acidification and corrosion from oxygenated acids, making it perfect for long-term use and sanitizing (making it useful for kitchens, plumbing, etc.). However, 304 does not stand up well to chlorinated acids and saline solutions.
On the other hand, stainless steel 316 is more resistant to corrosion than 304. By introducing a small percentage of molybdenum, 316 becomes increasingly resistant against corrosion due to chlorinated acids and saline solutions. This type of steel is often used in industries that utilize highly-corrosive materials: jet engine parts, lab. equipment, chemical containers, and food and pharmaceutical processing equipment.