PSI - Issue 28

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

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

Procedia Structural Integrity 28 (2020) 2126–2131

© 2020 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 European Structural Integrity Society (ESIS) ExCo Abstract Within the last decade, the European steel industry has made impressive progress in providing pipeline steels with excellent mechanical properties. Continuous improvement of cleanness and tailored thermomechanical treatments lead to damage tolerant microstructures. These steels offer high strength as well as impressive impact toughness properties with upper shelf values of more than 250 J. However, some of these steels show special fracture phenomena such as inverse fracture, seperations and a contracted transition area. The last of the three mentioned phenomena is characterized by the simultanious occurrence of upper and lower shelf values at the same testing temperature during charpy impact test. This unusual toughness behavior subsequentelly leads to difficulties in the component safety assessment and needs to be fundamentally understood. In this study, a combined experimental and numerical method is developed to investigate the microstructural reasons of such a fracture behavior. The methodology is demonstrated on a X65 pipeline steel that features a bainitic microstructure and shows a very narrow transition behavior. Following the characterization of the mechanical property profiles of the pipeline steel by different experiments on the meso-scale (e.g. Charpy impact test), the underlying fracture mechanisms were studied. It can be noted that inclusions are identified to be crack initiating for both ductile and brittle fracture behavior. In order to be able to understand the influence of the shape and location of the different inclusions on the fracture behavior, representative volume element (RVE) simulations were carried out. Through the integration of a crystal plasticity (CP) model, the material behavior is simulated at microstructure level and inclusion-related stress concentrations can be discussed. In the future, this approach can be applied to better understand microstructure-related phenomena as well as to couple scale-bridging simulation methods for a material-oriented component design. © 2020 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 European Structural Integrity Society (ESIS) ExCo Keywords: Fracture behavior; hybrid approach; microstructure modelling; thoughness; methodology development; transition range 1st Virtual European Conference on Fracture Hybrid Approach to Describe and Understand the Influence of Inclusions on the Transition Behavior of X65 Pipeline Steel Yannik Sparrer a *, Markus Könemann a , Sebastian Münstermann a a Integrity of Materials and Structures, Steel Institute (IEHK), RWTH Aachen University, Intzestr. 1, 52074 Aachen, Germany Abstract Within the last decade, the European steel industry has made impressive progress in providing pipeline steels with excellent mechanical properties. Continuous improvement of cleanness and tailored thermomechanical treatments l ad to damag tolera i rostructures. These steels offer high strength as well s impressive impact toughness properties with upp r shelf values of more than 250 J. However, som of th se steels show specia fracture pheno ena such as inve se f acture, seperations and a contracted r sition area. Th la t of the thr e m ntioned phenomena is characterized by the simultanious occurr nce of upper and low r shelf values at the same tes ing temperature during charpy impact test. This unusual to gh ess behavior subseq entelly leads to difficulties in he compon nt safety assessment a d needs to be fundamentally understo d. I this study, a combined experimental and n m rical method is developed to investig te the microstr ctural reasons of such a fracture behavior. The methodology is demonstrated on a X65 pipeline st el hat features a bainiti mic os ructur and hows a very narrow transition behavior. Fol wing the charact rization of the mechanical prop r y profiles of the pipeline steel by different experiments on the meso-scale (e.g. Charpy impact test), the u derlying fracture mechanisms were studied. It can b note that i clusions are identified t be crack initiating for bo h ductile and brittle fracture behavior. In order to be able to understa d the influence of the shap and location of the differe t inclusions on the fracture behavior, representative volum element (RVE) simulations w re carried out. Thr ugh the integration of a ry tal plasticity (CP) model, the material behavior is simulated at microstructure level and inclusion-related stress concentrations can be discussed. In the future, this pproach c n be applied o better understand microstructure-related phenomena as well as to oupl scale-bri gi g sim lation methods for a mat rial-oriented component design. © 2020 Th 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 u der re ponsibility of European Structural Integri y So i ty (ESIS) ExCo Keywords: Fracture behavior; hybrid approach; microstructure modelling; thoughness; methodology development; transition range 1st Virtual European Conference on Fracture Hybrid Approach to Describe and Understand the Influence of Inclusions on the Transition Behavior of X65 Pipeline Steel Yannik Sparrer a *, Markus Könemann a , Sebastian Münstermann a a Integrity of Materials and Structures, Steel Institute (IEHK), RWTH Aachen University, Intzestr. 1, 52074 Aachen, Germany

* Corresponding author. Tel.: +49-241-8096860; fax: +49-241-92224. E-mail address: yannik.sparrer@iehk.rwth.aachen.de * Corresponding author. Tel.: +49-241-8096860; fax: +49-241-92224. E-mail address: yannik.sparrer@iehk.rwth.aachen.de

2452-3216 © 2020 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 European Structural Integrity Society (ESIS) ExCo 2452-3216 © 2020 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 European Structural Integrity Society (ESIS) ExCo

2452-3216 © 2020 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 European Structural Integrity Society (ESIS) ExCo 10.1016/j.prostr.2020.11.039