The development and testing of new wear-resistant wheel materials extends from laboratory tests of material properties through theoretical and/or experimental demonstrations of strength to service tests. In this process, the influence of the new wheel material on its system partner - the rail - is often hard to judge. DB's (Deutsche Bahn AG) wheel/rail system test rig is an important link between laboratory and service tests. It permits the simulation of the rolling contact of the wheel and rail at full scale. The essential loading parameters, such as forces, angle of attack, and speed, correspond to real service conditions. This article reports on the first results from the testing of newly developed, alternative wheel materials in terms of the wear of the wheel and rail. The wheel steel currently used most frequently at DB is R7 with a carbon content of max. 0.52% and a tensile strength up to max. 940 N/mm, which both satisfies certain minimum requirements for resistance to wear and also simultaneously provides sufficient reserves of toughness. Thus, pearlitic steels with higher carbon content and thus higher resistance to wear are being tested for reducing wheel out-of-roundness. The main attention is on the uniformity of the material microstructure and thus also the mechanical properties across the wheel circumference. Such homogeneity requirements place equally high requirements an quality assurance during manufacturing. In addition, current tests are being performed with a quenched and tempered (Q&T) steel, which was developed for bearings in high-load rock drilling heads. Here, the focus is on reducing damage due to rolling contact fatigue, like that which can also happen for roller bearings. Investigatians have also been performed with the isothermally heat-treated ductile iron material ADT, which has already been applied for numerous mechanical engineering components with high-resistance to wear. This bainitic ductile iron with nodular graphite features a combination of high resistance to wear and high fatigue strength with high ductility act as a lubricant in the running surface between two friction partners rolling against each other, thus reducing wear. This article also describes the study of rolling noise.
Rolling contact phenomena at wheels and rails observed at DB's full-scale simulation test rig
Rollkontaktphenomäne zwischen Rad und Schiene beobachtet auf einem Simulationsprüfstand der Deutschen Bundesbahn
2003
6 Seiten, 10 Bilder, 4 Tabellen, 2 Quellen
Aufsatz (Konferenz)
Englisch
Rolling contact phenomena at wheels and rails observed at DB's full-scale simulation test rig
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