Pitting corrosion of 304 L stainless steel welds in simulated concrete pore solutions

The pitting corrosion of 304 L austenitic stainless steel joints with 308 L austenitic stainless steel as welding sticks was investigated in simulated concrete pore solutions with different chloride ion concentrations by potentiodynamic polarization curves, electrochemical impedance spectroscopy and Mott-Schottky curves. It is found that chloride ions play an important role in the corrosion behavior of the joints. When the chloride ion concentration increases, the corrosion potential, breakdown potential and charge transfer resistance of the joints at three different weld zones, i.e., base metal (BM), weld metal (WM) and heat affected zone (HAZ), in the simulated solutions decrease, but the charge carrier density and the number of pitting sites in the joints increase. In the same simulated solution, the weld metal shows a better corrosion resistance, followed by the heat affected zone, and the base metal has the lowest corrosion resistance due to its much lower charge transfer resistance and higher doping content.