The microstructure in the worn surfaces of a failed bainitic steel railway crossing was investigated using optical microscopy, SEM, TEM, nanoindentation and Mössbauer spectroscopy. The results indicated that a nanocrystalline layer had formed in the surface of a worn crossing during service. The formation of the nanocrystalline layer was due to the severe plastic deformation (SPD) caused by the repeated heavy loading in service by high speed train wheels. The mechanism of formation of the nanocrystalline layer was strain induced dynamic recrystallization, and the nanocrystalline grains were nucleated from the original crystals of the steel directly. The alloying elements in the worn surfaces of the steel segregated slightly by diffusion during the process of recrystallization. The nanocrystalline layer does not display the white etching layer commonly observed in ordinary railway rails, the reason may be the differences of its microstructure and carbon content with the ordinary rail steel.
Microstructure of the worn surfaces of a bainitic steel railway crossing
Mikrogefüge der Verschleißfläche einer Eisenbahnweiche aus bainitischem Stahl
Wear - An International Journal on the Science and Technology of Friction, Lubrication and Wear ; 268 , 11-12 ; 1243-1249
2010
7 Seiten, 8 Bilder, 2 Tabellen, 18 Quellen
Article (Journal)
English
Eisenbahnschiene , Wälzermüdung , Verschleißfläche , bainitischer Stahl , Schadensanalyse , Weiche , optische Mikroskopie , REM (Rasterelektronenmikroskopie) , TEM (Transmissionselektronenmikroskopie) , Nanohärteeindruck , Mössbauer-Spektrometrie , nanokristalliner Werkstoff , Hochgeschwindigkeitsbahn , dynamische Rekristallisation
Bainitic steels for railway applications
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