Abstract
Four kinds of stainless steel coupons and a Fe/Ag-coupled ACM (Atmospheric Corrosion Monitor) type corrosion sensor were exposed at six locations in marine atmosphere for seven periods each of which consisted of one to two months. At the end of each exposure the coupons were examined visually for rusting or no rusting. The outputs of ACM sensor and RH (relative humidity) sensor were measured by a data logger every ten minutes to determine the amount of deposited sea salt, Ws. By accumulating Ws and RH data for all the exposure periods and locations, the critical humidity, RH*, below which a steel rusts and the critical Ws value, Ws*, above which a steel rusts could be determined. The (Ws*/g·m-2, RH*/%) values are obtained as: (5×10-3, 45) for Type 410 steel, (5×10-1, 38) for 22Cr-0.8Mo steel, and (4×10-2, 43) for Type 430 steel and Type 304 steel.
