Corrosion Performance of Low Carbon Steels Containing Copper in Cl^- Environment with Different pH Values

Abstract

For exploring the corrosion rules of copper-containing low carbon steel under different pH conditions，the electrochemical workstation and metallographic microscope were used to analyze the polarization curves，AC impedance spectra and micro morphologies of ordinary weathering steel (Q345)，copper-containing low carbon steel (0Cu3Cr) and hull copper-containing low carbon steel (0CuAl) in NaCl environments with different pH values.Additionally，the difference in corrosion performance between copper-containing steel and low carbon steel in NaCl environments with different pH values was observed.Results showed the self-corrosion potential of the three samples was higher in the NaCl environment with pH＝12.The corrosion processes of 0Cu3Cr and 0CuAl were controlled by the anodic dissolution reaction，while that of Q345 was controlled by the cathodic reaction.Moreover，the self-corrosion potential of Q345 and 0Cu3Cr at pH ＝6 was slightly greater than that at pH＝8.The charge transfer resistance values of the three kinds of samples were the largest in the NaCl environment with pH＝12.When pH＝6，the pitting pits on the surface of 0Cu3Cr were smaller and less numerous.When pH＝8，the pitting pits on the surface were larger and more numerous.Besides，the corrosion resistance of 0CuAl at pH＝8 was better than that at pH＝6.

Keywords

• cl- environment|ac impedance|ph|polarization curve