Application Feasibility And Corrosion Resistance Mechanism Of Weathering Steel Containing Sn/Sb

The surface rust layer of weathering steel due to exposure to the atmosphere has good protection because of its excellent adhesion with the substrate.The traditional weathering steel can not meet the service conditions under various complicated conditions due to the single alloy element,while some of them are due to the high cost of alloy elements,but the cost of weathering steel is greatly increased.Up to now,there are few reports on the mature varieties of weathering steel which can meet the requirements of coastal atmosphere,industrial atmosphere and coastal industrial composite atmosphere.Therefore,the development of weathering steel which can meet a variety of complex atmospheric environment and the alloy elements are cheap has been put on the agenda.This work has remarkable economic benefit and engineering value.In this paper,based on the traditional weathering steel Q420 q NH,the weathering steel containing Sn Sb was developed by atmospheric exposure corrosion test.The corrosion resistance and corrosion evolution law of Sn Sb in coastal atmosphere,industrial atmosphere and coastal industrial atmosphere were investigated,The corrosion behavior,composition,structure and properties of the rusted electrode were analyzed by electrochemical test,SEM,XRD and EDS,The distribution of Sn Sb element content in the matrix and rust layer was discussed,The main contents and results are as follows:(1)The effect of chloride ion in coastal atmosphere on the corrosion resistance of weathering steel containing Sn Sb was studied.Six months before atmospheric corrosion,the addition of alloy element Sn has a certain effect on improving the corrosion resistance of steel,but it is inversely proportional to the content of Sn,that is,when the content of Sn is 0.079%,the corrosion resistance is the best;the addition of alloy element Sb is harmful to the improvement of atmospheric corrosion resistance of steel,and with the increase of Sb content,the atmospheric corrosion rate is accelerated.When the atmospheric corrosion lasts for 12 months,the corrosion resistance of Sn and Sb is obvious with the increase of the rust layer,and the corrosion resistance is enhanced with the increase of alloy element content.At the same time,Sn and Sb also have synergistic corrosion resistance.The corrosion resistance of weathering steel containing Sn Sb in coastal industrial atmosphere was studied.It was found that the results of 12 months’ exposure in Qingdao showed that the alloy elements Sn and Sb could improve the corrosion resistance of the steel;When the content of Sn or Sb is more than 0.1%,the corrosion resistance can be improved obviously,There is a certain synergy between Sn and Sb,When the content of Sn and Sb is less than 0.1%,the corrosion resistance is similar to that when the content of Sn or Sb is more than 0.1%.(2)The influence of corrosive gases such as SO2 in industrial atmosphere on the weatherability of weathering steel containing Sn Sb was studied.It is found that the addition of Sn and Sb has little effect on the atmospheric corrosion resistance of Q420 q NH weathering steel in industrial atmosphere.Six months before atmospheric corrosion,the addition of alloy element Sn has a certain effect on improving the corrosion resistance of steel,but it is inversely proportional to the content of Sn,that is,when the content of Sn is 0.079%,the corrosion resistance is the best.The addition of alloy element Sb is harmful to the improvement of atmospheric corrosion resistance of steel.With the increase of Sb content,the corrosion rate in the atmosphere is slightly slowed down.When the atmospheric corrosion lasted for 12 months,with the increase of rust layer,Sn could not improve the corrosion resistance.Only when the content of Sb is 0.11%,the corrosion resistance of steel can be slightly improved.At the same time,Sn and Sb have no obvious synergistic corrosion resistance.(3)The corrosion resistance of weathering steel containing Sn Sb in coastal industrial atmosphere was studied.It is found that the alloy elements Sn and Sb can improve the corrosion resistance of steel 6 months before atmospheric corrosion,especially when the content of Sn or Sb exceeds 0.1%,and the corrosion resistance of Sn is slightly better than that of Sb.At the same time,there is a synergistic effect between Sn and Sb.When the atmospheric corrosion lasted for 12 months,the corrosion resistance of 0.19% Sn was still the best,but the corrosion resistance of Sb was weakened.The synergistic corrosion resistance between Sn and Sb was enhanced.(4)The reason why Sn and Sb improve the corrosion resistance is that they promote the anodic dissolution of iron in the early stage of corrosion,accelerate the formation of stable rust,and inhibit the anodic dissolution of iron and the cathodic reduction reaction of rust in the later stage of corrosion.Sn has obvious inhibitory effect on chloride ion and Sb on sulfur.When they are combined together,there is a certain synergistic corrosion resistance.