Study On The Influence Factors And Their Mechanism On The Corrosion Resistance Of Weathering Steel Used In Railway Rolling Stock

The weathering steel has become widely used on railway rolling stock because ofits noble atmospheric corrosion resistance. The high corrosion resistance of theweathering steel is obtained mainly by addition of the alloy element which meanwhileincreased the cost of production. Therefore, the modification of alloy element,especially of costly Ni element, should be taken into consideration primarily in order toreduce the production cost. Furthermore, the nonmetallic inclusion is another influencefactor of the corrosion resistance of the weathering steel. Therefore, the investigation ofthe effect of element and inclusion modification on the corrosion resistance and itsmechanism can provide not only theoretical basis but also experimental data for thedevelopment of low cost and new type weathering steel with noble high corrosionresistance and cheaper producing cost.This study is mainly to investigate the corrosion resistance of the09CuPCrNiweathering steel with decreasing in Ni and increasing in Si and its service life indifferent atmospheric environment was predicted. The corrosion resistance of theQ450NQR1weathering steel after different inclusion modification and its mechanismof different inclusion on the corrosion behavior of the steel were also studied. Theresearch proceeded as follow:Firstly, the corrosion resistance of the weathering steel09CuPCrNi with an alloyelement modification was investigated. The result showed that both the modification onNi and Si should be responsible for the corrosion resistance change. The reducing on theamount of Ni might increase the initial corrosion rate of the weathering steel slightly,but the increasing on the amount of Si might enhance the post-resistance. In addition,service life prediction using regression analysis indicated that the tested steel absolutelymeet the engineering requirement.Secondly, the corrosion resistance of the weathering steel Q450NQR1withdifferent nonmetallic inclusion modification was also investigated. The result showedthat either RE-modification or Ca-modification on the inclusion can increase the initialcorrosion resistance of Q450NQR1remarkably, while the impact on the later corrosionperiod after the formation of the compact rust turned out to be small. After RE-modified,the inclusions were mainly compounds of RE oxides, RE sulfides and Al2O3. When Ca- modified, the inclusions were compounds of Ca oxides, Ca sulfides and Al2O3. Theinclusions become anodic after inclusion modification and were eroded preferentially asanode in0.01mol/L NaHSO3during the corrosion reactions which protected the steelmatrix from corrosion.