Microstructural Effect on the Corrosion Behavior of 3Ni Weathering Steels in Tropical Marine Atmospheric Environments: Outdoor Exposure and Indoor Tests
摘要
This study discusses the comparative weatherability of three microstructures of ferrite, ferrite + bainite, and bainite, obtained by controlling the rolling and cooling processes of a well-established weathering steel by adding 3 wt% Ni in tropical marine atmospheric environments. In field exposure in the Trat (Thailand) and accelerated laboratory testing, the bainitic steel showed superior weathering resistance compared to the other microstructures. The corrosion rates after 12-month of exposure were 0.012 mm/y for ferritic steel, 0.010 mm/y for ferritic + bainite steel, and 0.009 mm/y for bainitic steel. An analysis of the electrochemical properties of the rust layer, its phase composition, and morphological observations revealed that the influence of microstructure on the atmospheric corrosion rate of weathering steels primarily depend on the density of the rust and the adhesion between the rust layer and the substrate.
Graphic Abstract