海水中におけるステンレス鋼のすきま腐食と使用条件との関係(<小特集>腐食防食小特集)

概要

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In order to study the crevice corrosion of austenitic stainless steels which often occurs in stainless steel piping or heat exchanger tubing used for sea water service, the effects of chemical composition of steels, contents and flow velocity of sea water, heat transfer conditions and cathodic protection have been studied. Both plates and tubes made of 20Cr-22Ni-5Mo steels with nitrogen content of 0.02 to 0.2% and of commercial stainless steels (SUS 304, SUS 316L, SUS 329J1 and 20Cr-26Ni-6.5Mo) were evaluated, and copper base alloys (aluminum brass and cupro-nickel) were also tested in an experiment. All results of electrochemical tests (anodic polarization curves, passivation behaviors and constant potential tests in 0.1N-HCl+2M-NaCl and 1N-HCl solution at 60℃), model sea water heat exchanger tests (tube side: sea water of 0.5 to 1.5m/sec., shell side: water or steam of 50℃ to 140℃, 1 year ran), and concentrated sea-water flow-through tests (twofold of sea-water at ambient temperature) indicated that newly developed 20Cr-22Ni-5Mo-0.2N steel had a considerably higher resistance to crevice corrosion in sea-water environments, in comparison with commercial stainless steels and copper base alloys, but care should be taken on the using condition in actual service.
1982-10-15