1992 Volume 41 Issue 5 Pages 329-340
This paper summarizes recent trends in seawater-resistant stainless steels. These steels can be classified into 4 types; ferritic stainless steels which contain more than 25%Cr-3%Mo, austenitic stainless steels which contain more than 20%Cr-24%Ni-5%Mo, N-bearing austenitic stainless steels which contain more than 20%Cr-17%Ni-4%Mo-0.1%N, and duplex stainless steels which contain more than 25%Cr-6%Ni-3%Mo-0.1%N. The high-alloy ferritic stainless steels exhibit the best corrosion resistance to seawater among these types of steels. The superiority of the ferritic stainless steels is attributable to the difference in the effect of Cr on respective anodic polarization behavior of ferritic and austenitic stainless steels. At present, the ferritic stainless steels are mainly used in the condenser tubes of power plants, and the N-bearing austenitic stainless steels mainly in the pipe work of offshore platforms. Ultra-high nitrogen containing austenitic stainless steels, high-alloy duplex stainless steels manufactured by the powder metallurgical process, and anodic and catholic chromating stainless steels have also been studied as new seawater-resistant stainless steels.
