Corrosion of Q420qD High Strength Steel for Bridge in Neutral Media
中性介质中Q420qD高强桥梁钢的腐蚀行为

The corrosion resistance of Q420qD Ultra-low carbon bainitic high strength steel for bridge and F500L-Z steel was studied by means of neutral salt spray test and electrochemical measurement.The results shown that corrosion resistance of Q420qD steel was better than that of F500L-Z steel by comparative neutral salt spray tests for 1440 h.The fact was also proved that corrosion resistance of Q420qD steel was better than that of F500L-Z steel by electrochemical tests for different times in the neutral media in terms of their-free corrosion potentials,linear polarization curves and the electrochemical impedance spectroscopy(EIS).Furthermore,electrochemical impedance for Q420qD steel increased with the immersion time,which illuminated that the rust layer of which was also getting thicker with immersion time.So a thicker and compact rust layer on its surface may become a good barrier to the corrosive spices from the electrolyte so that to suppress the corrosion of steel substrate.