Duplex stainless steel alloy for use in seawater applications

摘要

The present invention relates to a stainless steel alloy, more precisely a duplex stainless steel alloy having ferritic-austenitic matrix and having high corrosion resistance in combination with good structural stability and hot-workability, in particular a duplex stainless steel having a ferritic content of 40-65% and a well-balanced composition, which gives the material corrosion properties making it more suitable for use in chloride-containing environments than what has been found possible previously. The material according to the present invention has, in view of the high alloy content thereof, extraordinarily good workability, in particular hot-workability, and should thereby be very suitable to be used for, for instance, the manufacture of bars: pipes, such as welded and weld less pipes, weld material, construction parts, such as, for instance, flanges and couplings. These objects are met according to the present invention with duplex stainless alloy, which contain (in % by weight): C more than 0 and up to max 0.03 Si up to max 0.5 Mo 0-3.0 20 Cr 24.0-30.0 Ni 4.9-10.0 Mo 3.0-5.0 N 0.28-0.5 B 0-0.0030 25 S up to max 0.010 Co 0-3.5 W 0-3.0% Cu 0-2.0 Ru 0-0.3 3 0 Al 0-0.03 Ca 0-0.010%, balance Fe together with inevitable contaminations.