PSI - Issue 37

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 ScienceDirect Available online at www.sciencedirect.com ScienceDirect

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

Procedia Structural Integrity 37 (2022) 153–158

© 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 Pedro Miguel Guimaraes Pires Moreira Abstract The laser powder bed fusion of metals (PBF-LB/M) is one of the most promising techniques to realize lightweight optimized parts and structures. Possible design elements are internal cooling channels or topology optimized geometries. However, not only does the process suffer of instabilities causing pores and lack-of-fusion defects but also a low surface quality. A further knowledge about these defects and their influence on the mechanical behavior are needed to use additively manufactured parts in structural relevant applications. In this work, the austenitic stainless steel 316LVM (X2CrNiMo18-15-3) has been processed by PBF-LB/M. In total, four different batches were manufactured with either no intended porosity or specific cubic defects ranging between 0.3 and 1.5 mm edge length. The fatigue behavior was evaluated at stress ratio R = -1 up to 1E7 cycles. The fracture surface was analyzed by scanning electron microscopy and the relationship between artificial defect size and fatigue strength was investigated by Kitagawa Takahashi (KT) diagram and its modification by El Haddad’s intrinsic crack length. The results show that the KT-diagram underestimates the fatigue strength of the investigated steel indicating a high defect tolerance and possible hardening mechanisms during cyclic loading such as possible nano-twinning. An influence of the entrapped process gas could also play a role. As long as this is unclear, the models can only be used conservatively as the full potential of the PBF-LB/M steel cannot be fully exploited. © 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 Pedro Miguel Guimaraes Pires Moreira Keywords: Effects of defects, fatigue behavior, austenitic steel, Kitagawa-Takahashi diagram ICSI 2021 The 4th International Conference on Structural Integrity Influence assessment of artificial defects on the fatigue behavior of additively manufactured stainless steel 316LVM Felix Stern a *, Jonas Grabowski a , Arno Elspaß b , Daniel Kotzem a , Stefan Kleszczynski b,c , Gerd Witt b , Frank Walther a a TU Dortmund University, Department of Materials Test Engineering, (WPT), Baroper Str. 303, D-44227 Dortmund, Germany b University of Duisburg-Ess , Chair of Manufacturing Technology, Lotharstr. 1, D-47057 Duisburg, Germany c Center for Nanointe ratio Duisburg-Essen (CENIDE), Car -Benz-S r. 199, D-47057, Duisburg, Germany Abstract The laser powder bed fusion of metals (PBF-LB/M) is one of the most promising techniques to realize lightweight optimized parts and structures. Possible design el ments are internal c oling c annels o topolo y optimized geometries. However, not only doe the process suffer of instabilities causi g pores and la k- f-fusion d fects but a so a low surface quality. A furth r knowledge ab ut se defect and the r influence on the mechanical behavior are ne ded to se additively m nufactured parts in structural r levan applications. I this work, the austenitic stainless ste l 316LVM (X2CrNiMo18-15-3) has been processed by PBF-LB/M. In total, four different ba ches were man factured with ither no intended porosity or specific cubic def cts ranging between 0.3 and 1.5 mm edge length. The fatigu beh vior was evaluated at stress ratio R = -1 up to 1E7 ycles. The fracture surfac was a alyzed by scanning electron microscopy and the relationship between artificial defect size and fatigue strength was investigated by Kitagawa Takahashi (KT) diag am and its modification by El Haddad’s intrinsic crack length. The results how that the KT-diagram underestimates the fatigue strength of the investigated steel in icati g a high defect tolerance and po sible hardening mechanisms during cyclic loading such as possible nano-twinning. An influence of the entrapped process g s could also play a role. As long a this is un lear, the models can nly b used conservatively as the full pot ntial of the PBF-LB/M steel cannot be fully exploited. © 2022 Th Authors. Published b 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 Pedro Miguel Guimara s Pires Moreira K ywords: Effects of defects, fatigue behavior, austenitic steel, Kitagawa-Takahashi diagram ICSI 2021 The 4th International Conference on Structural Integrity Influence assessment of artificial defects on the fatigue behavior of additively manufactured stainless steel 316LVM Felix Stern a *, Jonas Grabowski a , Arno Elspaß b , Daniel Kotzem a , Stefan Kleszczynski b,c , Gerd Witt b , Frank Walther a a TU Dortmund University, Department of Materials Test Engineering, (WPT), Baroper Str. 303, D-44227 Dortmund, Germany b University of Duisburg-Essen, Chair of Manufacturing Technology, Lotharstr. 1, D-47057 Duisburg, Germany c Center for Nanointegration Duisburg-Essen (CENIDE), Carl-Benz-Str. 199, D-47057, Duisburg, Germany

* Corresponding author. Tel.: +49 231 755 8233; fax: +49 231 755 8029. E-mail address: felix.stern@tu-dortmund.de * Corresponding author. Tel.: +49 231 755 8233; fax: +49 231 755 8029. E-mail ad ress: felix.stern@tu-dortmund.de

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 Pedro Miguel Guimaraes Pires Moreira 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 u der re ponsibility of Pedro Miguel Guimara s Pires Moreira

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 Pedro Miguel Guimaraes Pires Moreira 10.1016/j.prostr.2022.01.071