Including Duplex & SuperDuplex
Corrosion Resistant material for wide ranging applications
Ferritic stainless steels contain a minimum of 11% chromium. They are relatively inexpensive as they contain no nickel. Ferritic stainless steels are magnetic. Austenitic stainless steels contain a minimum of 18% chromium, along with a minimum of 8% nickel. They are non-magnetic, which is a great advantage in many applications, especially marine applications where unwarranted magnetic influence can affect compasses and other direction finding equipment.
They also possess improved formability (e.g. deep drawing or stretching) compared to ferritic stainless steels and are tougher, maintaining their strength better at high temperatures. Weldability is improved as is corrosion resistance, and, with the addition of less than 2% molybdenum, corrosion resistance is significantly improved.
Martensitic stainless steels contain a minimum of 11.5% chromium, generally with no nickel content but an addition of 0.15% - 0.4% carbon. These steels give very high strength in the hardened condition. Tempering at 150°C to 170°C increases corrosion resistance, and the abrasion and wear resistance of these alloys is well known. Some variants containing high carbon content are not, however, recommended for welding. Duplex and Super Duplex stainless steels typically contain approx. 22% chromium, 5% nickel and around 0.1% minimum of nitrogen.
Effectively, they are of a mixed ferritic/austenitic structure, and have high strength combined with good corrosion resistance, good weldability, formability and resistance to crevice and pitting corrosion in