Stainless duplex ferritic- austenitic steel, articles made therefrom and method of enhancing intergranular corrosion resistance of a weld of the stainless duplex ferritic austenitic steel

摘要

The steel consists of about: .03 w/o Max. carbon, 3.0 w/o Max. manganese, 1.0 w/o Max. silicon, 26.0 to 29.0 w/o chromium, 3.5 to 5.2 w/o nickel, 3.5 w/o Max. molybdenum, 0.15 w/o Min. nitrogen, 2 w/o Max. copper, 0.005 w/o Max. boron and the balance essentially iron. The steel preferably contains about 0.17 to 0.35 w/o nitrogen for improved pitting resistance and for increased austenite content. Welds of the steel preferably contain at least about 17% austenite in the as-welded condition for improved pitting and intergranular corrosion resistance. There is also disclosed a method of improving the intergranular corrosion resistance of an as-welded steel of similar composition but extending to 11 to 30 w/o chromium and 3.5 to 20 w/o nickel.