The difference in corrosion propagation behavior of 316LN stainless steel and carbon steel concrete reinforcing bar is highlighted on the cover. The top images of 316LN stainless steel rebar (left) and polished corrosion coupon (right) show areas of deep, localized corrosion while the bottom images of carbon steel rebar (left) and polished corrosion coupon (right) show widespread, shallow corrosion damage. The difference in how corrosion spreads during electrochemical testing on arrays of 100 microelectrodes of both 316LN stainless steel and carbon steel is shown graphically. The grids represents a microelectrode array with red shading indicating stable anodic dissolution. The middle two rows were preferentially initiated and the 316LN array showed no spreading to adjacent electrodes (top) while corrosion on the carbon steel array rapidly spread to adjacent electrodes (bottom). The rebar composition and manner which corrosion propagates will directly impact the lifetime of the concrete structure.
More detailed information can be found in: M. F. Hurley, J. R. Scully, Lateral and radial corrosion propagation behavior of 9−21% Cr and 18% Cr + 2.8% Mo stainless steel reinforcing materials in simulated concrete environments, Materials and Corrosion 2013, 64, 752.