Duplex steels originated in Sweden more than 70 years ago. It was primarily used in the sulfite paper industry. Duplex alloys are basically a compromise that has some of the ferritic stress corrosion cracking resistance along with much of the excellent formability of the common austenitic stainless alloys, all this comes at a lesser price as compared to the high nickel alloys. Duplex alloys were made for combating corrosion related problems due to chloride-bearing cooling waters along with other aggressive chemical process fluids. Duplex Steel are called so because of its mixed microstructure. Duplex steels have equal proportions of ferrite and austenite.The chemical composition of duplex steel with high contents of Cr and Mo, results in improved intergranular and pitting corrosion resistance.
