Properties of the ferritic stainless steel NSSC® 180 which contains no Mo and its applications

For the improvement of corrosion resistance of ferritic stainless steel in atmospheric environment, the atmospheric corrosion behavior of stainless steel was evaluated. It was clarified that the pitting corrosion inevitably occurs in either type 304 in an atmospheric environment with wet-dry processes. It indicates that the atmospheric corrosion resistance should be evaluated in view of the growth of the corrosion pit. The growth of pit is suppressed by the addition of Ni, Cu, and Nb in solution simulating the corrosion pit. These results shows that NSSC® 180 (19Cr-0.3Ni-0.4Cu-Nb steel), which contains no Mo and a very limited amount of Ni, have the same corrosion resistance to Type 304 in atmospheric corrosion. From these excellent properties, this steel has been widely applied to some of equipments exposed to an aqueous chloride environment.