Seawater pump and seawater corrosion resistant austenitic stainless steel

摘要

PROBLEM TO BE SOLVED: To improve the pitting corrosion resistance of a cast austenitic stainless steel at the time of use for seawater pump by specifying the composition of the cast austenitic stainless steel. ;SOLUTION: This steel has a composition containing, by weight ratio, ≤0.08% C, 0.5-1.5% Si, 0.5-2% Mn, ≤0.04% P, ≤0.01% S, 8.0-9.5% Ni, and 18-21% Cr and also has a metallic structure in which ferritic phase is regulated to ≥6vol.%. It is preferable that the ratio between the Cr equivalent represented by %Cr+%Mo+1.5×%C+0.5×%Mn and the Ni equivalent represented by %Ni+30×%C+0.5×%Mn, (Cr equivalent)/(Ni equivalent), is regulated to ≥1.95% and also the degree of cleanliness of the steel is regulated to ≤0.1%. Moreover, as to the seawater pump, at least either of casing and casing liner is constituted of this cast steel and the number of corrosion pits in the surface of the cast steel after immersion in flowing seawater of 5m/sec flow rate for 1600hr is ≤10pieces/cm².;COPYRIGHT: (C)1997,JPO