PSI - Issue 47

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ScienceDirect

Procedia Structural Integrity 47 (2023) 219–226 Structural Integrity Procedia 00 (2023) 000–000 Structural Integrity Procedia 00 (2023) 000–000

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27th International Conference on Fracture and Structural Integrity (IGF27) Fracture behavior and mechanical characterization of R350HT rail steel Davide Leonetti a, ∗ , Vito´ria Mattos Ferreira b , Bart Schotsman b,c a Eindhoven University of Technology, Eindhoven, The Netherlands b Delft University of Technology, Delft, The Netherlands c ProRail, Utrecht, The Netherlands 27th International Conference on Fracture and Structural Integrity (IGF27) Fracture behavior and mechanical characterization of R350HT rail steel Davide Leonetti a, ∗ , Vito´ria Mattos Ferreira b , Bart Schotsman b,c a Eindhoven University of Technology, Eindhoven, The Netherlands b Delft University of Technology, Delft, The Netherlands c ProRail, Utrecht, The Netherlands

© 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the IGF27 chairpersons Abstract R350HT is a standard premium heat-treated rail steel and the reference for new rail steel development. The present study discusses an experimental characterization of fatigue crack growth rate and fracture toughness for this refined pearlitic rail steel in mode I-loading. The tests are carried out on compact tension specimens extracted from the rail head with the straight notch pointing to the rail foot. As a result, the crack path orientation approximates deep rolling contact fatigue cracks. The fracture surfaces obtained under cyclic and monotonic loading are compared by means of scanning electron microscopy. The results are analyzed and discussed with reference to the morphology of the fracture surfaces for the crack initiation sites, fatigue crack growth region, and the final fracture region, evidencing the role of the microstructure, and inclusions on the fracture behavior. From the analysis of the crack path and fracture surface, it is concluded that the refined microstructure and ferrite ductility play an important role in fracture behavior. © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Abstract R350HT is a standard premium heat-treated rail steel and the reference for new rail steel development. The present study discusses an experimental characterization of fatigue crack growth rate and fracture toughness for this refined pearlitic rail steel in mode I-loading. The tests are carried out on compact tension specimens extracted from the rail head with the straight notch pointing to the rail foot. As a result, the crack path orientation approximates deep rolling contact fatigue cracks. The fracture surfaces obtained under cyclic and monotonic loading are compared by means of scanning electron microscopy. The results are analyzed and discussed with reference to the morphology of the fracture surfaces for the crack initiation sites, fatigue crack growth region, and the final fracture region, evidencing the role of the microstructure, and inclusions on the fracture behavior. From the analysis of the crack path and fracture surface, it is concluded that the refined microstructure and ferrite ductility play an important role in fracture behavior. © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / )

Peer-review under responsibility of the IGF27 chairpersons. Keywords: R350HT; fatigue crack growth rate; fracture toughness Peer-review under responsibility of the IGF27 chairpersons. Keywords: R350HT; fatigue crack growth rate; fracture toughness

1. Introduction 1. Introduction

The increasing tra ffi c load and intensity on the railway network require the use of high-strength and wear-resistant rail steels, in order to guarantee the safe use of the rail infrastructure. Railway rails are subjected to localized and high contact forces, inducing slipping mechanisms, and adverse weather conditions, causing wear, rolling contact fatigue, and other rail-related damage phenomena Lichtberger (2011); Zerbst et al. (2009). The shift to steel grades character ized by higher wear resistance makes the growth of rolling contact fatigue cracks more prone to induce failures. In other words, a competition exists between these two phenomena, i.e. rolling contact fatigue and wear, such that they compete with each other, despite the accumulation of plastic strain being the reason for both phenomena Cannon and The increasing tra ffi c load and intensity on the railway network require the use of high-strength and wear-resistant rail steels, in order to guarantee the safe use of the rail infrastructure. Railway rails are subjected to localized and high contact forces, inducing slipping mechanisms, and adverse weather conditions, causing wear, rolling contact fatigue, and other rail-related damage phenomena Lichtberger (2011); Zerbst et al. (2009). The shift to steel grades character ized by higher wear resistance makes the growth of rolling contact fatigue cracks more prone to induce failures. In other words, a competition exists between these two phenomena, i.e. rolling contact fatigue and wear, such that they compete with each other, despite the accumulation of plastic strain being the reason for both phenomena Cannon and

∗ Corresponding author. E-mail address: d.leonetti@tue.nl ∗ Corresponding author. E-mail address: d.leonetti@tue.nl

2452-3216 © 2023 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the IGF27 chairpersons 10.1016/j.prostr.2023.07.015 2210-7843 © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of the IGF27 chairpersons. 2210-7843 © 2023 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 4.0 / ) Peer-review under responsibility of the IGF27 chairpersons.