Microstructure and corrosion resistance behavior of Cr‐Nb alloyed layer on low carbon steel

The Cr‐Nb alloyed layer formed on the surface of low carbon steel by double glow plasma surface alloying could improve the corrosion resistance of the substrate. The morphology and microstructure of the layer were investigated by scanning electron microscopy, energy dispersive spectrometer and X‐ray diffraction. The average thickness of the alloyed layer is approximately 18 µm. A uniform and dense Cr‐Nb alloyed layer had been synthesized without any cracks and holes on the surface of low carbon steel. The corrosion behavior of the alloyed layer was evaluated by polarization experiments in 3.5 wt% NaCl solution using a CHI660D type electrochemical workstation. Potentiodynamic polarization and electrochemical impedance spectroscopy were applied to evaluate the corrosion resistance of the alloyed layer. Compared with the substrate, the Cr‐Nb alloyed layer exhibited higher corrosion potential, lower corrosion current density and larger charge transfer resistance. The result presents that Cr‐Nb alloyed layer has significantly modified the corrosion resistance of low carbon steel.