Formation mechanism of white etching layers in pearlitic rail steels under continuous abrasion

White etching layer (WEL) is a big problem of rail-damage initiation. Understanding its formation mechanism is essential for designing WEL-resistant rail steels. This study selected three types of pearlitic rail steels, conducted the same continuous abrasions on them, and evaluated the material performance with the existence of WEL. Optical microscopy, scanning electron microscopy and electron probe X-ray microanalyzer were employed to analyze the WEL microstructure, and finite element analysis was made to estimate the temperature rise and strain-field evolution during the steel abrasion. The austenitization temperature ( A c1 ) and plasticity of pearlitic steels mostly affect WEL thickness, the lower the A c1 or the higher the plasticity, the thicker the WEL. Additionally, it is found that the solution strengthening of C is more effective than the diffusion strengthening of carbide : the more carbides dissolute during austenite transformation, the higher the WEL hardness . Key factors influencing the cementite dissolution are superheating, lattice distortion energy, and chemical composition. The amount of WEL can be reduced by increasing A c1 , or adding Cr and V elements that form stable carbides. • The main factors affecting the thickness of the white etching layer are Ac1 and plasticity. •The greater the degree of carbide dissolution, the higher the hardness of the white etching layer. •The main determinants of cementite dissolving rate are chemical composition, lattice distortion energy, and superheating. •Enhancing the formation resistance of WEL fundamentally involves increasing the difficulty of carbide dissolution.