Stainless steels are grouped in ‘families’ that share particular properties.
Austenitic stainless steels are usually non-magnetic and rapidly work-harden with cold working, which allows a significant increase in the strength of the metal. Austenitic stainless steels are the most easily formed, and are used to produce a huge range of everyday items, including kitchen sinks and appliances, roofing, and chemical tanks.
Ferritic stainless steels are magnetic, and are not susceptible to stress corrosion cracking. Alloy modifications are often used to improve the fabrication properties of Ferritic stainless steels, and they are typically found in vehicle exhausts, fuel lines, and domestic appliances, as well as some cooking utensils.
Martensitic stainless steels are differentiated from Ferritic stainless steels by their high carbon content and relatively low chromium content. They are magnetic and have high corrosion resistance but are usually not suitable for welding. They are typically used to fabricate springs, fasteners, surgical instruments and cutlery.
Duplex Stainless steels have high chromium and low nickel content, and share properties with both Austenitic and Ferritic stainless steels. They are also resistant to corrosion cracking, have high toughness and tensile strength, and are highly resistant to corrosion, especially if exposed to chlorides. They are readily suited to welding, and are often used for various applications in the maritime and petrochemical industries, as well as in more domestic appliances like heat exchangers.
Precipitation Hardening grades of stainless steel contain nickel and chromium, and are well suited to heat treatment, which allows very high tensile strength to be achieved. This steel can be ‘aged’ after machining using a low temperature treatment process, which prevents distortions in the finished product. Precipitation Hardening stainless steels are most often used for turbine blades, various mechanical components, and in the aerospace industry.