Abstract
Using a Kelvin probe, the corrosion potential distribution on the surfaces of two types of steel, ordinary carbon steel and type 430 stainless steel, under thin solution layer has been investigated. On the surface of carbon steel covered with corrosion products, which sucked in water, noble and less noble potentials were separately observed in the potential distribution because of a large IR drop in the absorbed water phase. The former potential area worked as a cathodic site and the latter potential area, as an anodic site. On the other hand, the cathodic areas around pits of stainless steel showed less noble potential compared with other areas. This indicated that the farther from the pits the location became, the more the cathodic current density decreased because of a large IR drop.
