Elucidation of the mechanism how tread thermal cracks generate during the service is important to improve the safety design of carbon steel railway wheels. In the present work, we have succeeded to reproduce the thermal cracks using actual railway wheels under the condition of concurrent loading of both continuous rolling contact and repeated frictional heat. Microstructural observation was precisely conducted with the scanning electron microscope and electron back-scattered diffraction analysis. We have found that ultra-fine grains of ferrite and spheroidized cementite are formed in the area within 100 my m depth from the surface where fine cracks are also observed being initiated. Relations of residual stress, cracks configuration and fracture surface were examined to consider the crack generation process. Plastic deformation and thermal stress near the surface result in substantial tensile residual stress, which causes initiation and propagation of cracks.
Thermo-mechanical crack generation and ultra-fine grains formation in carbon steel railway wheels under continuous contact load and repeated heat input
MS&T, Materials Science and Technology, 2008 ; 2001-2009
2008
9 Seiten, 10 Quellen
Conference paper
English
Betriebssicherheit , Bruchflächenaussehen , Eigenspannung , Eisenbahnfahrzeug , Eisenbahnrad , Erwärmungsriss , Haftreibung , kohlenstoffreicher Stahl , kontinuierliches Walzen , kugelförmiger Zementit , plastische Verformung , Rasterelektronenmikroskopie , Reibungswärme , Rissausheilen , Rissbildung bei Wärmebehandlung , Rissfortpflanzung , Sicherheitstechnik , thermomechanische Analyse , thermomechanische Behandlung , Zugfestigkeit
Shape optimization methodology for railway wheels subjected to thermo-mechanical loads
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