PSI - Issue 68

ScienceDirect Structural Integrity Procedia 00 (2025) 000–000 Structural Integrity Procedia 00 (2025) 000–000 Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Available online at www.sciencedirect.com ScienceDirect

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Procedia Structural Integrity 68 (2025) 727–733

European Conference on Fracture 2024 Effects of quenching and tempering conditions of a low-alloy pressure vessel steel (A508 Gr.3) on its brittle fracture initiation and toughness Julie Papin a,d, *, Jean-Baptiste Delattre a,d , Jean Luc Flament a , Bernard Marini a , Pierre Joly b , Jean-Philippe Mathieu c , Ludovic Vincent a , Anne-Françoise Gourgues-Lorenzon d a Université Paris-Saclay, CEA, Service de Recherche en Matériaux et procédés Avancés, 91191 Gif-sur-Yvette, France b FRAMATOME, Direction Technique et Ingénierie, Tour Areva, 92400 Courbevoie, France c EDF Lab Les Renardières, Dpt. MMC, 77250 Moret-Loing-et-Orvanne, France d Mines Paris, Université PSL, Centre des Matériaux, CNRS UMR 7633, BP 87 91003 Evry cedex, France Abstract The fracture toughness and the brittle fracture initiation of a quenched/tempered A508 Gr.3 low-alloy steel were studied to reveal the effects of heat treatment conditions. The results show better fracture toughness properties (i.e. lower fracture toughness reference temperature T 0 (according to ASTM E1921 standard)) at higher quenching rate and lower tempering parameter, as expected. Three types of brittle fracture initiation mechanisms have been observed at the microscopic scale: at grain boundary carbides; on inclusions; at grain boundaries with no detectable particle. The proportion of occurrences of crack initiations cases observed at inclusions was higher when the reference temperature T 0 is lower, either with a smaller tempering parameter or a higher quenching rate. Overall, the mechanism of crack initiation on a carbide as observed in this study was predominant. © 2025 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 ECF24 organizers Keywords: Low alloy steel; Bainitic steel; Cleavage; Fracture toughness; Fractography European Conference on Fracture 2024 Effects of quenching and tempering conditions of a low-alloy pressure vessel steel (A508 Gr.3) on its brittle fracture initiation and toughness Julie Papin a,d, *, Jean-Baptiste Delattre a,d , Jean Luc Flament a , Bernard Marini a , Pierre Joly b , Jean-Philippe Mathieu c , Ludovic Vincent a , Anne-Françoise Gourgues-Lorenzon d a Université Paris-Saclay, CEA, Service de Recherche en Matériaux et procédés Avancés, 91191 Gif-sur-Yvette, France b FRAMATOME, Direction Technique et Ingénierie, Tour Areva, 92400 Courbevoie, France c EDF Lab Les Renardières, Dpt. MMC, 77250 Moret-Loing-et-Orvanne, France d Mines Paris, Université PSL, Centre des Matériaux, CNRS UMR 7633, BP 87 91003 Evry cedex, France Abstract The fracture toughness and the brittle fracture initiation of a quenched/tempered A508 Gr.3 low-alloy steel were studied to reveal the effects of heat treatment conditions. The results show better fracture toughness properties (i.e. lower fracture toughness reference temperature T 0 (according to ASTM E1921 standard)) at higher quenching rate and lower tempering parameter, as expected. Three types of brittle fracture initiation mechanisms have been observed at the microscopic scale: at grain boundary carbides; on inclusions; at grain boundaries with no detectable particle. The proportion of occurrences of crack initiations cases observed at inclusions was higher when the reference temperature T 0 is lower, either with a smaller tempering parameter or a higher quenching rate. Overall, the mechanism of crack initiation on a carbide as observed in this study was predominant. © 2025 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 ECF24 organizers Keywords: Low alloy steel; Bainitic steel; Cleavage; Fracture toughness; Fractography © 2025 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 ECF24 organizers

* Corresponding author. E-mail address: julie.papin@cea.fr * Corresponding author. E-mail address: julie.papin@cea.fr

2452-3216 © 2025 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 ECF24 organizers 2452-3216 © 2025 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 ECF24 organizers

2452-3216 © 2025 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 ECF24 organizers 10.1016/j.prostr.2025.06.122