Effect Of Cr On High Humid And Warm Marine Atmospheric Corrosion Resistance Of Weathering Steel

Due to the characteristics of high humid and high Cl^-,marine atmospheric environment become the most serious environment in all kinds of atmospheric environment.Although the cost of Cr in weathering steel is relatively low,its effect on corrosion resistence is not quite clear now.So this paper studies the effect of Cr on high humid and warm marine atmospheric corrosion resistance of weathering steel.This paper discussed the influence of Cr on corrosion resistence by using periodic immersion accelerated corrosion test,electrochemical test and field atmospheric exposure test.Results showed that at the initial stage,with low corrosion current density,high charge transfer resistance R_ctt and high all-in resistence R_r+R_ct,with Fe_2.4Cr_0.6O₄,Fe₃O₄ and X-ray amorphous material exsiting in its rust layer,chrome-bearing steel behaved best corrosion resistence.With the increasing of the corrosion time,despite the protective effect of Sn and Cr's bedded enrichment in rust layer,the serious enrichment of Cl promoted localized corrosion and plenty of?-FeOOH appeared.Localized corrosion dominated in middle and later periods of corrosion,significantly lower corrosion resistance.The role of Cr in the rust layer is complicated.At the initial stage,Cr promoted the formation of Fe₃O₄ and X-ray amorphous material,participate in forming Fe_2.4Cr_0.6O₄,so the corrosion resistence increased.With the increasing of the corrosion time,on the one hand,the enrichment of Cr in the rust layer promoted the formation of?-FeOOH,thus the corrosion resistance improved.On the other hand,Cr hydrolysed and localized corrosion appeared,because of the exesistence of a large amount of Cl in the rust layer.Late in corrosion process,hydrolysis of Cr is great than its protection,thus corrosion resistance reduced.