Duplex stainless steels have become important competitors to austenitic stainless steels in many applications and a great deal of attention has focused on the welding aspects. The introduction of modern grades with improved properties and a competitive price level have increased their use in the offshore, petrochemical and shipbuilding industries, for example. In particular the newer grades, with their higher nitrogen content and improved weldability, have moved duplex stainless steels from a position as “interesting” materials to one of “useful in practice”. However, duplex stainless steels differ from austenitic grades in some respects, and know‐how combined with the use of appropriate welding procedures and consumables is therefore the key to successful welding.