The state of Oregon is graced with a rugged and beautiful coastline with a zone extending several miles inland that can be highly corrosive. Microclimates, which strongly affect the performance of steel, are created in this zone by precipitation, salt spray, fog, airborne salts, high winds, and solar radiation. Atmospheric corrosion measurements were conducted on one-sided panels to examine the effects of sheltering, orientation, and distance from the ocean on seven bridges, in eight coastal communities, and three inland locations. The test materials included mild steel, thermal-sprayed aluminum on mild steel sealed with moisture-cured urethane, and a three-coat bridge maintenance paint system on mild steel. The surface of the coated steels was scribed from corner to corner in an X-pattern to create a damaged area that exposed the mild steel. Results indicated a wide difference in performance of the steels as a function of the coastal environment. Corrosion led to the formation of insoluble corrosion product and runoff contributed negligibly to total mass loss. Mass loss increased with decreasing distance to the
ocean, increasing "wetness" of the location, and decreasing inclination of the surface in bold exposures. Mass loss in shelter and partially sheltered exposures were high, as much as an order of magnitude
higher than bold exposures. Mild steel protected by a sealed thermal-sprayed aluminum coating exhibited no undercutting or corrosion damage. Mild steel protected by a three-coat bridge maintenance paint system exhibited increasing undercutting and damage with decreasing distance to the ocean.
Keywords: atmospheric corrosion, coastal environments, microclimate, sheltering, chloride, mild steel, aluminum, thermal spray, moisture-cured urethane, precipitation runoff.