A comparison of corrosion profiles of steel strips, coupons and chains

Corrosion profiles for coupons and for single strips have been published previously and tend to show a distinct difference between the two. Corrosion of a continuous strip usually results in a flatter profile than that obtained for a set of individual coupons. Herein these results are compared with the corrosion of chain links in chains exposed through the tidal zone. Steel chains are used extensively in the marine industry and are subject to the same corrosive effects as other marine steel infrastructure. The matter of interest is whether chain links act as individual coupons or form part of a single strip as in electrically connected links of a chain. If the corrosion profile is similar to that of coupons, individual links will act as isolated cathode/anode couples and will corrode faster in the tidal zone than if the corrosion loss is spread over the entire length of the chain. The present paper presents corrosion profiles derived from lengths of nominally 10 mm diameter steel chains exposed at three geographical locations and compares these profiles to profiles obtained from single strips and sets of individual coupons exposed at the same or similar locations.