In structural applications exposed to a corrosive environment a wide range of corrosion resistant steels can be considered. The technical-economic requirements related to the investment, operation and maintenance of facilities requires close collaboration between engineering and metallurgists for selecting the most efficient materials. In view of the continuous improvement of their properties and their growing availability, Duplex stainless steels will remain an attractive solution to the future needs of designers and users in mechanical engineering. Duplex stainless steels were born and have been actively developed by European companies since 1935. Their features made them very attractive compared to equivalent austenitic grades: higher resistance to Stress Corrosion Cracking, higher mechanical properties and lower alloy cost. They present excellent cost/properties ratios particularly in critical applications including: oil and gas, chemical industry, pulp and paper industry, water systems, desalination plants, pollution control equipments, chemical tankers, ... Consideration of sustainability and Life Cycle Cost are moving other applications to Duplex use (architecture and construction, storage tanks) ensuring without any doubt further development for the whole duplex family. The purpose of this paper is to present an introduction to Duplex stainless steels, review their properties, applications and focus on the latest development of Lean Duplex grade competing with 304L or 316L and coated carbon steel. Keywords : Duplex-Lean Duplex-Applications-Structure-Construction-Corrosion
