Study on Electrochemical Corrosion of Nb Microalloy Steel

In order to study corrosion properties of Nb microalloying high speed rail steel, heavy rail U75V steel (Cr 0.45%) with different Nb content had been investigated.The main causes of corrosion of high speed rail steel are explored by fitting curve analysis using CorrView electrochemical software based on constant potential measurement.The results show that the addition of Nb produces much more compact oxide layer, which is conducive to improvement of steel corrosion resistance.Nb can improve self-corrosion potential of steel substrate and can make oxide layer more dense. Corrosion current density of test steel containing 0.028% Nb is lower than the other test steel.Phase analysis of rust layer with different corrosion time shows that adding Nb is conducive to fast formation and quantity of α-FeOOH. α-FeOOH/γ-FeOOH ratio of test steel containing 0.028% Nb is higher than that of the other three kinds of steel. Therefore, this study provides a theoretical basis for composition optimization of high speed rail steel.