PSI - Issue 39

Georg Schnalzger et al. / Procedia Structural Integrity 39 (2022) 313–326 Author name / Structural Integrity Procedia 00 (2019) 000–000

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Fig. 13. Schematic illustration of crack paths observed in (a) undeformed ( γ = 0) and (b) pre-deformed ( γ ~ 3.5) pearlitic rail steel R260.

This distinctive change in the crack path is attributed to the microstructural alignment and refinement of the pearlitic microstructure induced during the high pressure torsion process. In the undeformed material, the crack propagates on the micro-scale along preferential propagation planes leading to a tortuous crack path. According to the results from the FEA these curved cracks exhibit Mode-I components which steadily increase with raising deviation from pure Mode-II. The detailed microstructural analysis shows that in the deformed material the crack propagates along the deformed pearlitic microstructure leading to the Mode-II dominated propagation. In future, it is assumed that Mode-II propagation data for different pre-deformation states can be recorded using the proposed experimental setup. These Mode-II data could play an important role for numerical-based predictions of rolling contact fatigue cracks in rail and crossing components. Acknowledgements The authors gratefully acknowledge the financial support under the scope of the COMET program within the K2 Center “Integrated Computational Material, Process and Product Engineering (IC-MPPE)” (Project No 859480). This program is supported by the Austrian Federal Ministries for Transport, Innovation and Technology (BMVIT) and for Digital and Economic Affairs (BMDW), represented by the Austrian research funding association (FFG), and the federal states of Styria, Upper Austria and Tyrol. References Akama M. 2019. Fatigue crack growth under non-proportional mixed mode loading in rail and wheel steel Part 1: sequential mode I and mode II loading. Applied Sciences 9, 2006–2026. Akama M., Mori T. 2002. Boundary element analysis of surface initiated rolling contact fatigue cracks in wheel/rail contact systems. Wear 253, 35–41. Bold P.E., Brown M.W., Allen R.J. 1991. Shear mode crack growth and rolling contact fatigue. Wear 144, 307–317. Bold P.E., Brown M.W., Allen R.J. 1992. A review of fatigue crack growth in steels under mixed mode I and II loading. Fracture of Engineering Materials and Structures 15, 965–977. Bonniot T., Doquet V., Mai S.H. 2020. Fatigue crack growth under non-proportional mixed-mode I + II. Role of compression while shearing. International Journal of Fatigue 134, 105513. Dassault Systèmes 2019. Abaqus 2019. Daves W., Kráčalík M., Scheriau S. 2019. Analysis of crack growth under rolling-sliding contact. International Journal of Fatigue 121, 63–72. DIN Deutsches Institut für Normung e.V. 2011. Railway applications - Track - Rail - Part 1: Vignole railway rails 46 kg/m and above; German version EN 13674-1:2011. Doquet V., Pommier S. 2004. Fatigue crack growth under non-proportional mixed-mode loading in ferritic-pearlitic steel. Fatigue and Fracture of Engineering Materials and Structures 27, 1051–1060. Fischer F.D., Reisner G., Werner E., Tanaka K., Cailletaud G., Antretter T. 2000. A new view on transformation induced plasticity (TRIP). International Journal of Plasticity 16, 723–748. Fletcher D.I., Franklin F.J., Kapoor A. 2009. Rail surface fatigue and wear. In: R. Lewis and U. Olofsson (eds.), Wheel-rail interface handbook. CRC Press, Oxford, pp. 842. Grossoni I., Hughes P., Bezin Y., Bevan A., Jaiswal J. 2021. Observed failures at railway turnouts: Failure analysis, possible causes and links to current and future research. Engineering Failure Analysis 119, 104987. Hohenwarter A., Bachmaier A., Gludovatz B., Scheriau S., Pippan R. 2009. Technical parameters affecting grain refinement by high pressure