Stainless steel is characterised by higher resistance to oxidation and corrosion, particularly in moist environments or in fresh water, compared to carbon or ordinary unalloyed steel.
This capacity is mainly due to the near absence of carbon (on average 1,2%), and to the presence of chromium in the alloy. Stainless steels are able to passivate, that is, to cover themselves with a thin and tight oxide layer, that protects the metal on the surface and the alloys from the oxidizing action of oxygen and external chemical agents.
Duplex stainless steels owe their name to their microstructure, called biphasic because they contain equal proportions of austenite and ferrite. Born from the use of nitrogen as an alloying element, they have a widespread use in the pipeline and in process applications in offshore platforms: their high resistance allows, indeed, the reduction of wall thickness and, consequently, of the platforms weight.
NICKEL ALLOYS AND COBALT ALLOYS
SUPER ALLOYS based on nickel, iron-nickel or cobalt, very resistant to high temperature, are therefore used in highly stressed structural elements, destined to often operate at a temperature of over 600°. They are characterised by a combination of mechanical resistance, corrosion resistance and ability to withstand high temperatures for continuous periods that other metals are unable to reach.
SUPER ALLOYS are used in the aerospace industry and for industrial applications that require high temperature mechanical resistance and corrosion resistance. These applications include rocket engines, gas and steam turbines, alternative engines, high-strength connections, tools and furnaces for metalworking, chemical and petrochemical plants, biomedical components.