高流速海水による数種の金属材料の腐食

抄録

In order to investigate the corrosion behavior of some alloys in high velocity sea water, experimental tests have been conducted by using disc shaped specimens and tension type welded ones with and without zinc anodes, at the coast of Seto Inland Sea. Gun metal, mild steel and four kinds of stainless steels were immersed in flowing (18m/sec) natural sea water for about nine months.
The weight-loss and the depth of pitting, besides the reduction of tensile strength were measured.
Results obtained are as follows:
(1) Corrosion rate of mild steel was 0.75mm/yr, and it could be decreased to 0.034mm/yr by cathodic protection with zinc anode.
(2) Corrosion rate of gun metal was 0.2mm/yr, and that of type 304 stainless steel was less than 0.003mm/yr.
(3) Reduction rate of tensile strength of welded mild steel was about 29%, and it could be reduced to nearly zero with zinc anode.
(4) It was found that stainless steel could be safely used in high velocity flowing sea water.