Nickel Alloys
Nickel alloys are widely used, important, non-ferrous materials the applications in which they are used include marine environments, aerospace, chemical plant and power generation stations. There is a wide range of nickel alloys, each with differing properties and application areas dependent on the alloying elements used. The main alloy systems are: · Monels - these are copper-nickel alloys. They are resistant to attack from sulphuric acid, hydrofluoric acid and salt water and are widely used in marine environments. They are also used in heat exchangers because of their good thermal conductivity. · Incoloys - in these alloys chromium and iron are added. They are particularly resistant to stress corrosion cracking caused by chloride ions. These alloys are used for high temperature applications such as furnaces and steam generators. · Hastalloys - these have chromium, iron and molybdenum added. These alloys have a high resistance to hydrochloric and phosphoric acid attack at room temperature. · Inconels - are nickel-chromium solid solution alloys. Inconels are widely used as a cladding material because of its corrosion resistance and its high temperature toughness. The corrosion resistance is due to its adhesive oxide film, while the toughness is attributed to the fine grain size of the material matrix. These alloys are used to clad pipes in the offshore and petrochemical industries, for heat exchangers and for many applications with hot or corrosive gases. · Nimonic - these are nickel-chromium precipitation hardened alloys with small amounts of titanium, aluminium, cobalt and molybdenum present. They offer excellent high temperature creep resistance as well as high corrosion resistance and yield strength at elevated temperatures. They are used for applications such as turbine blades and furnace ports.
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