Research On Corrosion Behavior Of High Strength Weathering Steel For Heavy Haul Train

Atmospheric Corrosion Resistant Steel is also known as weathering steel.With the development of railway transportation,high strength and high weathering requirements have been put forward for railway vehicle steel.High weathering steels currently must be more than three times that of ordinary steels.The steel used in railway vehicles mainly includes structural steels such as steel plates and H-beams.Due to the specialization of the production process,H-beams are more difficult to meet this requirement.Based on the technology and equipment of H-beam steel production,this essay carried out research on the corrosion performance of high-strength and high-weathered steel,and provided technical support for the development of it.In this paper,alternate immersion corrosion,electrochemical tests,scanning electron microscope?SEM?and X-ray diffractometer?XRD?were used to analyze the morphology and structure of the rust layer,mainly including the following aspects:?1?In the laboratory,electrochemistry was used to detect the thermodynamic and kinetic parameters of corrosion of different materials.The experiment studied the effect of alloying elements and microstructure on the weathering resistance of high-strength,high-weathering and hot-rolled structural steels under industrial atmospheres.The corrosion mechanism of different materials in NaHSO₃ solution was also investigated.The alternate immersion corrosion test was used to study the influence of alloying elements on the corrosion performance and morphology of weathering steel in industrial atmospheres and to evaluate corrosion performance of different test steels.?2?With the prolongation of corrosion time,the corrosion rate of the test steel without Cu,Cr,and Ni alloy elements is fluctuated,after addition of the alloy elements above,the corrosion rate tends to be stable.When the corrosion time is prolonged,the rust thickness and compactness of the five test steels increase gradually.?3?Evolution of corrosion products and morphology of experimental steels were analyzed by SEM and XRD to explore the general laws of rust layers under different corrosion cycles for various alloying elements.Experimental results show that:?1?The self-corrosion potential of the test bare steel is mainly affected by their microstructure,those with coarse grain and single structure have low corrosion potential and their corrosion resistance tend to be strong at the beginning.?2?The impedance of the test steel increases significantly with the addition of Cu,Cr,and Ni.For the same test steel,the resistance value of the test steel added with the above alloy elements shows an increasing trend as the corrosion time is prolonged and the rust layer is stable along with enhanced protection performance,especially at the later corrosion period.?3?After adding the alloying elements Cu,Cr,and Ni to the experimental steel,the corrosion resistance will be significantly enhanced,and the corrosion rate will be reduced to less than half of that of the unadded steel.As the Cr content increases,the corrosion rate of the test steel decreases.When the Cr content is 1.73%and 4.5%,the corrosion rate is approximately 1/2 and 1/3 of that of the Cr-free steel,respectively.?4?When Cu,Cr,and Ni elements are added to the test steel,the proportion of the protective phase?-FeOOH crystal of the rust layer increased,as a result the density of the rust layer increased significantly while the hole cracks gradually disappeared,leading to the improved corrosion resistance.When the Cr content is3.6%or more,surface rust layer is composed of bulk Cr₂O₃ and Cr?OH?₃ amorphous,which impede the occurrence of electrochemistry,thus protecting the substrate and improving the corrosion resistance of the steel.