The Successful Use of Austenitic Stainless Steels in Sea Water

Austenitic stainless steels are providing excellent trouble-free service in sea water for pumps, propellers, valves and other items of marine equipment. Once in a while, a failure occurs as the result of deep localized pitting in a crevice. Data is given showing that austenitic, ferritic and martensitic stainless steels suffer pitting in crevices and under deposits in quiescent sea water. Austenitic stainless steels remain free from attack in high velocity sea water. Low purity ferritic and the martensitic stainless steels frequently pit in high velocity sea water. Crevice corrosion can be effectively controlled with cathodic protection from iron, zinc, aluminum or magnesium galvanic anodes or impressed current cathodic protection by polarization to -0.6 volts versus Calomel. Austenitic stainless steel, in many situations, performs well because it is a component of a multi-alloy assembly utilizing iron or steel. Examples from field experience are given.