Four Major Types
Stainless Steel was invented by a Sheffield metallurgist called Harry Brearley, who, on August 20 1913 made his first cast of stainless steel.

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The four major types are:
:: Austenitic
:: Ferritic
:: Austenitic-ferritic (duplex)
:: Martensitic
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Austenitic is the most widely used type of stainless steel. It has a Nickel content of at least of 7%, that makes the steel structure fully austenitic and gives it ductility, a large scale of service temperature, non-magnetic properties and good weld ability. The range of applications of austenitic stainless steel includes housewares, containers, industrial piping and vessels, architectural facades and constructional structures.

Ferritic stainless steel has properties similar to mild steel but with the better corrosion resistance. The most common of these steels are 12% and 17% Chromium containing steels. With 12% used mostly in structural applications and 17% in housewares, boilers, washing machines and indoor architecture.

Austenitic-ferritic stainless steel has both ferritic and austenitic lattice structure - hence their common name: duplex stainless steel. This steel has some Nickel content for a partially austenitic lattice structure. The duplex structure delivers both strength and ductility. Duplex steels are mostly used in petrochemical, paper, pulp and shipbuilding industries.

Martensitic stainless steel contains mostly 11 to 13% Chromium and is both strong and hard with moderate corrosion resistance. This steel is mostly used in turbine blades and in knives.


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