Corrosion-Resistant Experimental Steels For Marine Applications

Abstract

Six steels having various combinations of nickel, copper and phosphorous were tested in sea water for exposure periods of one, two and five years, and a comparison made with the corrosion resistance of structural carbon steel. The test specimens measured 20 feet in length and were placed in the sea water so that their tops extended above the splash zone while the bottoms were in the mud. Decreases in thickness were calculated at 20 different levels for each of the Ni-Cu-P steels. It was found that these steels as a class were much more corrosion resistant than the sheet-piling steel to the conditions existing in and above high tide. The superiority was even greater when the steels were exposed to the atmosphere 80 feet from shore. The five-year exposure tests showed that steel containing 0.5 percent Ni, 0.5 percent Cu and 0.12 percent P had the greatest resistance of the steels tested. The attack below low tide was essentially independent of the composition of the steel. Pitting attack was very local and thus severe. In atmospheric tests made 80 feet from the shore, the most resistant Ni-Cu-P steel had a weight loss only 5 percent that of sheet-piling steel. 2.2.3