This type of material is widely used in equipment and installations in the petrochemical and food industries, and in ship and yacht constructions.
The resistance against corrosion is achieved by the influence of alloying elements (particularly Cr, Ni and Mo). A thin layer (skin) of chromium oxide prevents the material from rusting. In the event of damage to the protective oxide layer, it can recover 'automatically', because underlying chromium will diffuse to the surface, where it binds with atmospheric oxygen to form chromium oxide.
Various grades of stainless steel are available. In practical terms, these differ in their protective properties and – just like 'ordinary' steels – in their mechanical properties, weldability and machinability.
Examples of commonly used types of stainless steel are:
Stainless Steel 316 (according to ASTM)
An austenitic type of stainless steel with high corrosion resistance. It is used in the chemical industry, and in shipbuilding and yacht building (the material is seawater resistant). 316L (L = low carbon content) is used when improved weldability is required.
Stainless Steel 304 (according to ASTM)
An austenitic type of stainless steel with good corrosion resistance, widely used for equipment in the food and dairy industries. The material is weldable and deformable. Stainless steel 304L (L=low carbon content) is used when improved weldability is required.