The Pearlite Structure Has Great Resistance To U71MN Heavy Rail Steel Effect Of Gas Corrosion

The corrosion of rails is related to major issues such as railway operation efficiency and safety,and the safety of transportation systems.The corrosion of heavy rail steel is as important as strength,hardness and wear resistance.The corrosion behavior of U71Mn heavy rail steel was studied by simulating the atmospheric environment,which provided a theoretical basis for the research on the corrosion resistance of U71Mn heavy rail steel in the atmospheric environment.NaHSO₃ corrosive medium was used to perform dry and wet alternating indoor accelerated corrosion tests.Long-term?72,120,240,360,and 480h?and initial?0,10,30,and60min?corrosion were performed,and field emission electron microscopy,X-ray diffraction,Electrochemical tests and other instruments have analyzed the corrosion morphology,rust layer structure,corrosion products of rust layers,and the electrochemical characteristics of rust layers of U71Mn heavy rail steel with pearlite structure of different interlayer spacing in a simulated industrial atmosphere.As the average lamellar spacing of pearlite decreases,the corrosion resistance of U71Mn heavy rail steel improves.When the average lamellar spacing of pearlite is reduced to 155nm,the form of corrosion on the surface of the steel substrate is mainly pitting corrosion and uniform corrosion.Electrochemical results show that for uncorroded steel substrates,as the average lamellar spacing of pearlite decreases,the corrosion current density also decreases.For the steel substrate subjected to the corrosion test,when the pearlite layer spacing is reduced to241 nm,the corrosion current density is reduced by 0.2 mA·cm-2.However,as the average interlayer spacing is further reduced to 155 nm,the corrosion current density is increased first.After the decline.As the initial corrosion time increases,the pearlite sheet spacing decreases,and the self-corrosion potential and charge transfer resistance increase,indicating that the reduction of the average pearlite sheet spacing has a stronger inhibitory effect on corrosion.When the corrosion time is 60 minutes,the charge transfer resistance The decline may be caused by the collapse of the pearlite sheet.U71Mn heavy rail steel with pearlite structure with different lamellar spacings in the simulated atmosphere environment,with the corrosion time prolonged,the corrosion rate of the four different lamellar pearlite structures decreases significantly.After 240 hours of corrosion,the corrosion rate decreases.Weaken.In the same corrosive environment,the rust layer components all contain?-FeOOH,?-FeOOH,and Fe₃O₄.With the decrease of the pearlite layer spacing,a small amount of?-Fe₂O₃ appeared first in the corrosion products,but the rust layer had a denser morphology.In addition,in the simulated atmospheric environment,when the corrosion is 72h-240h,the pearlite layer spacing is 155nm,the self-corrosion current density Jcorr is the lowest,but it is increasing,and the self-corrosion potential Ecorr is the highest.For samples with a pearlite layer spacing of 446 nm,the self-corrosion current density Jcorr showed a downward trend,and the self-corrosion potential Ecorr showed an upward trend.When the corrosion time was 240 h,the self-corrosion potential Ecorr was the largest.In the middle specimen,Ecorr did not differ much.With the increase of corrosion time,the pearlite structure sheet spacing decreases,and the time to form a dense protective rust layer is advanced.The thickness and density of the inner rust layer are significantly improved,which is conducive to blocking the entry of O₂ and corrosive media and improving the atmospheric resistance Corrosive.