Research And Development Of High Corrosion Resistant Weathering Steel For Railway Vehicles

With the development of railway to high speed,heavy load and low cost in China,the requirements for materials used in railway vehicles are becoming more and more stringent in China,and the resistance to atmospheric corrosion and strength of materials is becoming more and more high.In this paper,high corrosion resistance Q350EWR1 and Q450EWR1 weathering steel are developed,which greatly improves the resistance of weather-resistant steel to atmospheric corrosion,in order to prolong the service life of railway locomotives and reduce the replacement of vehicle body.The main research work and conclusions of this paper are as follows.(1)On the basis of low C,P and S,the alloy elements of adding Cu,Cr and Ni are combined to complete the design of Q350EWR1 and Q450EWR1 components of high weathering steel,The determination of austenitic continuous cooling transition curve and the determination of phase change points under the condition of deformation and non-deformation of Formaster-Ⅱ and DIL805 deformation phase variants of automatic phase changer are used.The results show that when the cold speed is less than 0.5℃/s,the ferrite and pearlite are generated,when the cold speed is higher than 0.5℃/s,only Bainite is produced,and when the cold speed is less than 1℃/s,the tissue is ferrite and pearlite,and when the cold speed is higher than 1℃/s,only Bainite is produced.(2)The true stress-true strain curves of experimental steel Q350 EWR1 and Q450EWR1 were determined by using MMS-200.The results show that Q450EWR1 recrystallization activation can be 417kJ/mol,Q350EWR1 recrystallization activation can be 386kJ/mol,and the solution of constitutive equation and the regression of deformation resistance formula are completed.(3)Using φ450mm Hot rolling experiment machine for Laboratory rolling experiment,heating temperature 1200℃,Q350EWR1 final rolling temperature of 903℃,coiling temperature of 720℃,microstructure is mainly ferrite and pearlite,yield strength of 363MPa,tensile strength of 559MPa;When the final rolling temperature of Q450EWR1 is 871℃ and the coiling temperature is 721℃,the microstructure is mainly ferrite and bainite,the yield strength is 474MPa and the tensile strength is 697MPa.Meet the mechanical properties of the requirements.(4)The periodic infiltration corrosion test of Q350EWR1 and Q450EWR1 in laboratory rolling was carried out.The results show that the relative corrosion rate is less than 30%,which meets the standards of the Ministry of Rail ways.The corrosion behavior and corrosion mechanism were analyzed by electron probe,electron scanning microscope and X-ray diffraction,and the corrosion process was divided into two stages,the early stage was the rapid decline of corrosion rate,the later period was the corrosion stationary stage,through the redistribution of corrosion-resistant elements Cu,Cr and Ni,and the promotion of stable dense α-FeOOH generation,It makes the rust layer whole more dense and enhances the corrosion resistance.(5)The Industrial trial production and periodic infiltration corrosion test of Q350EWR1 in the 1780mm production line of steel.The mechanical properties of the trial-resistant steel are good and meet the requirements of the standard,and the relative corrosion rate is less than 30%,which satisfies the requirements of the Ministry of Railways.The addition of weatherproof elements Cu,Cr and Ni to High-rise steel promotes the formation of α-FeOOH and makes α-FeOOH smaller,and the rust layer is denser,improving weather ability.(6)The 20%CO2 and 80%Ar gas protection welding experiments were carried out on the Q350EWR1 of industrial trial production.After welding and after welding and 550℃annealing experiment,the mechanical properties on the basis of the original base material has been improved,enough to meet the requirements of the Ministry of Railways.