Corrosion Performance of Low Alloy Steels in Sub-Arctic Natural Seawater

Corrosion mass loss trends for low alloy and for high-strength structural steels of grades A, B, D, AH, and DH exposed for up to 5 years in sub-Arctic seawater near Vladivostok are compared with trends in temperate Pacific Ocean waters at Taylors Beach. All corrosion losses show bi-modal trending. The losses at Vladivostok are initially some 25% of those at Taylors Beach but later are some 60%, a change attributed to the change in corrosion rate controlling mechanisms consistent with the bi-modal trending pattern. At both test sites pollution is low and microbiological corrosion unlikely to be a significant influence. The high-strength steels show slightly lower corrosion losses after about 1 year exposures. The results show that characterization of corrosion trends based on short-term (e.g., 1 year) exposures can be highly misleading for estimating longer-term corrosion losses.