PSI - Issue 23

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

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ScienceDirect

Procedia Structural Integrity 23 (2019) 269–274

© 2019 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 scientific committee of the ICMSMF organizers Abstract Austenitic stainless steel 316L was tested at room temperature in three different cycling modes – axial tension/compression, pure torsional and multiaxial in phase mode with the same equivalent strain amplitude. Two types of hollow cylindrical specimens were used in this study. The first type of specimen with smooth surface was used for studying the mechanism of initiation of fatigue crack and for determination of fatigue life. The second type of specimen with artificial hole was used for measuring of crack growth rate. The mechanism of crack initiation was observed by scanning electron microscopy and by focused ion beam technique. Detailed observations of microstructure were done by transmission electron microscopy. The mechanism of fatigue crack initiation is following – persistent slip bands are formed and fatigue cracks initiate from them. Crack growth rate was determined from micrographs taken by light microscope during cycling. It was found that the cycling in axial mode leads to the fastest crack growth rate and the shortest fatigue lives. On the contrary, cycling in torsional mode leads to the slowest crack growth rate and the longest fatigue lives. One of probable causes of such behavior can be found in phase transformation fro m austenite to α´ martensite which is much more intense in the case of pure torsional loading than in other modes. © 201 9 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 scientific committee of the IC MSMF organizers. 9th International Conference on Materials Structure and Micromechanics of Fracture Fatigue crack growth rate in axial, torsional and multiaxial mode in 316L austenitic steel Ladislav Poczklán ab , Veronika Mazánová a , Štěpán Gamanov a , Tomáš Kruml ab * a Institute of Physics of Material, Žižkova 22, Brno 616 62, Czech Republic b CEITEC IPM, Žižkova 22, Brno 616 62, Czech Republic Abstract Au te itic stainless steel 316L w s tested at room temperature in three different cycling odes – axial ension/compression, pure torsional and multiaxial in phase mode w th he same quivalent strain amplitude. T o types f hollow cylindrical specimens were used in this study. The first type of specimen with smooth urface was used for studying the mechanism of initiation of fatigue crack and for determination of fatigue life. The second type f pecimen with art ficial hole was used f r me suring o rack gr wth r te. The mechanism of crack initi was observed by scanning electron micro copy and by focused ion beam technique. Detailed observations of microstructure were done by transmissi n lectron m croscopy. The mechanism of fatigue crack initi ion i followi g – persistent sli bands are formed and fatig e cracks initiate fr m them. Crack growth r te was determined rom micrographs aken by lig t mic oscope d ring cycli g. It was found that the cycling in axial mo e leads to the fastest crack growth rate and the hortest fat gue lives. On the contr ry, cycling in torsional mode leads to the lowest crack growth rate and th l ngest fa igue lives. One of probabl cause of such behavior can be fou d in phase transf rmation fro m austenite to α´ martensite which is much more intense in the case of pure torsional loading than in other modes. © 201 9 The Authors. Published by Elsevier B.V. This is an ope acces article under t CC BY-NC-ND lic nse (http://creativecommon org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the scientific committee of the IC MSMF organizers. 9th International Conference on Materials Structure and Micromechanics of Fracture Fatigue crack growth rate in axial, torsional and multiaxial mode in 316L austenitic steel Ladislav Poczklán ab , Veronika Mazánová a , Štěpán Gamanov a , Tomáš Kruml ab * a Institute of Physics of Material, Žižkova 22, Brno 616 62, Czech Republic b CEITEC IPM, Žižkova 22, Brno 616 62, Czech Republic

Keywords: fatigue crack initiation; austenitic 316L steel; crack growth rate; multiaxial cycling; phase transformation. Keywords: fatigue crack initiation; austenitic 316L steel; crack growth rate; multiaxial cycling; phase transformation.

* Corresponding author. Tel.: +420 532 290 379. E-mail address: kruml@ipm.cz * Correspon ing author. Tel.: +420 532 290 379. E-mail address: kruml@ipm.cz

2452-3216 © 2019 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 scientific committee of the IC MSMF organizers. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. This is an ope acces article under CC BY-NC-ND lic nse (http://creativecommon org/licenses/by-nc-nd/4.0/)

Peer-review under responsibility of the scientific committee of the IC MSMF organizers.

2452-3216 © 2019 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 scientific committee of the ICMSMF organizers 10.1016/j.prostr.2020.01.098