Grain Size Effect on the Electrochemical Corrosion Behavior of Surface Nanocrystallized Low-Carbon Steel

A nanocrystallized surface was fabricated on low-carbon steel by ultrasonic shot peening (USSP) technique. The grain size on the top layer of the surface nanocrystallized (SNC) low-carbon steel was about 20 nm, which increased with distance from the peening surface. The electrochemical corrosion behavior of the SNC low-carbon steel with different grain sizes was studied by electrochemical methods in 0.05 M sulfuric acid (H2SO4) + 0.05 M sodium sulfate (Na2SO4) aqueous solution. Grain sizes <35 nm showed a strong effect on the electrochemical corrosion behavior. The corrosion rate of the SNC low-carbon steel increased with the decreasing of grain size. This was attributed to the increased number of the active sites caused by SNC low-carbon steel.