PSI - Issue 42

Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com ScienceDirect

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 42 (2022) 1560–1566

23 European Conference on Fracture - ECF23 AISI P20 steel under VHCF testing conditions Pedro R. da Costa a,b *, Luís Reis a,c , Manuel Freitas b a IDMEC, Department of Mechanical Engineering, Instituto Superior Técnico, University of Lisbon, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal

b Atlântica, Escola Universitária, Fabrica de Pólvora de Barcarena, 2730-036 Barcarena, Portugal c Instituto Superior Técnico, University of Lisbon, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal

© 2022 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 scientific committee of the 23 European Conference on Fracture – ECF23 Abstract As more complex materials, structures and machines are created and applied in the modern world, the importance and complexity of fatigue testing methods become more indispensable for any mechanical project. This study focuses on an AISI P20 Steel in the Very High Cycle Fatigue (VHCF) regime, between 10 6 to 10 9 cycles, under different loading conditions: Tension-compression, pure torsion, and multiaxial tension/torsion. To reach such a considerable high number of cycles, no conventional fatigue testing method is energy and time reliable. Therefore, the present study conducted ultrasonic fatigue testing methods under 20kHz. Each stress type fatigue method was reached from its respective and different ultrasonic fatigue setup. Significant testing associated conditions and methodology, such as temperature, frequency and displacement, were carefully controlled, recorded, and made similar for all three methods. Stress-life results, material behaviour throughout fatigue testing and fracture surfaces for each stress type were compared for behaviour and damage correlation between pure torsion, tension-compression and the multiaxial combination of the two, tension-torsion. After all conducted fatigue tests, the obtained fatigue crack surfaces were analyzed by optical and scanning electron microscope (SEM) and compared between methods. Each tested method presented fatigue fracture surfaces with associated fracture morphologies similar to classic fatigue methods. The novel tension-torsion ultrasonic fatigue fractures showed both axial and torsion fatigue fracture dependencies and complexities, proving the induced stress field of interest. © 2020 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 23 European Conference on Fracture - ECF23 Keywords: Ultrsonic Fatigue Testing; Multiaxial Fatigue; Very High Cycle Fatigue

* Pedro Rodrigues da Costa. Tel.: +351 918 444 13 E-mail address: pedro.r.costa@tecnico.ulisboa.pt; luis.g.reis@tecnico.ulisboa.pt

2452-3216 © 2020 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 23 European Conference on Fracture - ECF23

2452-3216 © 2022 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 scientific committee of the 23 European Conference on Fracture – ECF23 10.1016/j.prostr.2022.12.197