Effect Of Rare Earth On The Marine Atmosphericl Corrosion Behavior Of High Strength Automobile Plate

In that coastal city,the automobile service period is shorten due to the accelerated corrosion of the car due to the environmental impact.Therefore,to improve its corrosion resistance in harsh environment can be a problem to be solved urgently.Previous studies have shown that rare earth can improve the corrosion resistance of steel,which provides a new way to improve the corrosion resistance of high strength automobile plate.In this paper,the corrosion law and electrochemical behavior of rare earth and non-rare earth automobile plates in marine atmosphere environment were studied by adding 24ppm rare earth La,with hot rolled high strength automobile plates produced by a steel plant as experimental materials.The effect of rare earth on the atmospheric corrosion resistance of high strength automobile plate is analyzed.The research results provide a reference for the development of a new type of hot rolled high strength automobile plate by using rare earth resources to reduce the cost.The effect of rare earth on the atmospheric corrosion resistance of automobile plate was studied by using periodic infiltration corrosion test to simulate the marine atmospheric environment.The surface macroscopical,microscopic morphology and rust layer section morphology of the test steel after periodic infiltration and corrosion were photographed by digital camera and scanning electron microscope?SEM?,respectively.the effects of rare earth on the corrosion products and rust layer morphology were analyzed.The composition of corrosion products was tested by XRD,the effect of rare earth on the structure and evolution of corrosion products was analyzed,the corrosion rate of automobile plate was measured by weight loss method,and the effect of rare earth on corrosion kinetics was studied.The change of surface potential distribution and impedance mode value was investigated by combining the scanning Kelvin probe technique?SKP?,local electrochemical impedance spectroscopy technique?LEIS?and the traditional electrochemical measurement method in order to find out the change of surface potential distribution and impedance mode value.The effect of rare earth addition on the electrochemical corrosion behavior of automobile plate was studied.The results show that both rare earth and non-rare earth automobile plates are uniformly corroded in marine atmosphere.The corrosion products are mainly Fe₂O₃,Fe₃O₄,?-FeOOH and?-FeOOH.With the addition of trace rare earth,the corrosion products of automobile plate are denser and the corrosion rate is decreased.After 240 hours of dipping,the corrosion rate of automobile plate decreases by 28.49%.The addition of rare earth La can increase the corrosion potential and reduce the corrosion current of automobile plate.After 120h corrosion,the charge transfer resistance of rare earth automobile plate is 33.94%higher than that of non-rare automobile plate.In the initial stage of marine atmospheric corrosion,with the extension of corrosion time,the surface voltaic potential of the automobile plate gradually shifted positively,the maximum impedance modulus value decreased,and the number of convex peaks of the surface active points gradually increased.In the same period,the surface voltaic potential of rare earth automobile plate is lower than that of the non-rare earth automobile plate,and its maximum impedance modulus value is about one order of magnitude higher than that of the non-rare earth automobile plate.The corrosion resistance of high strength automobile plate in marine and atmospheric environment was improved with the addition of trace rare earth.