Development of white etching layers on rails: simulations and experiments

White Etching Layers (WELs) on rails owe their name to the white appearance after etching with Nital. WEL is very often linked with rail defects like Squats and are said to partly consist of martensite, which indicates thermal effects. On this account, temperature simulations on and below the rail surface in the wheel-rail contact zone were done for a given set of parameters. The simulation results reveal that the austenitisation temperature of steel - necessary for the development of martensite - is reached under certain conditions. Validation tests on the full-scale wheel-rail test rig at voestalpine Schienen GmbH (Leoben / Austria) produced WELs and showed a good agreement with the simulation results. The presented and validated model can e.g. be used to enhance traction and braking control systems to reliably avoid the development of WELs in operation and to reduce according wheel-rail defects (e.g. Squats).