Corrosion Behavior of Carbon Steels Coupled to Stainless Steels in Sea Water

Abstract

To evaluate the corrosion risk of offshore steel structures at submerged zone caused by stainless steel sheathing and cathodic protection failures, it is essential to grasp the degree of the carbon steel-stainless steel galvanic corrosion. The objective in this study was to clarify the effect of area ratio of stainless steel coupled to carbon steel on corrosion behavior in sea water. As a result, stainless steels promote galvanic corrosion, but the degree of accelerated corrosion was much smaller than that estimated from the area ratio. Calcareous deposits had formed on the surface of stainless steels during galvanic tests in seawater. The calcareous deposits appeared to diminish the diffusion of the dissolved oxygen and diminish the cathodic reaction of oxygen reduction on the stainless steel surface.