Corrosion Tests in Baltic Sea Water on Heat Exchahger Tubes of Various Metallic Materials

Abstract Seventeen different tube materials were exposed to continuous and intermittent flow in Baltic Sea water (0·4% Cl−) at 50°c for a maximum of 15000 h. During testing the specimens were examined at certain intervals. After testing, the specimens were examined visually and metallographically.The following materials were completely resistant: titanium, CuNi30MnlFe, Alloy 825, and the austenitic steels Cr18Ni24Mo4·5, Cr20Ni25Mo4·5Cu and Cr24Ni24Mo2Ti. The ferritic–austenitic steels Cr18Ni5Mo2Si and Cr25Ni5Mo1·5, on the other hand, seemed to be attacked by local intercrystalline corrosion in the vicinity of the welds. The same type of attack occurred, against expectations, even in the entirely ferritic steels, especially in Cr21Mo3Ti; this attack was however shown to be caused by surface carburisation.Admiralty brass (2·5 m/s), aluminium brass (3·0 m/s) and CuNil0Fe1Mn (3·5 m/s) were attacked by erosion corrosion. The same type of attack, although to a considerably smaller extent, has also been observed...