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

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

ScienceDirect

Procedia Structural Integrity 23 (2019) 209–214

© 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 © 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. The ff ct f an environment on the damage mechanism was addressed in this tudy. Super austenitic steel Sanicro 25 grade was subjec ed to isothermal elasto-plastic cyclic l ad ng at 700 °C. The material was exposed to differe t environ ental conditions to assess the ef ect of laboratory air comparing to high vacuum. The mecha ism of the crack nucleation was the matter of the inquiry by means of canning electron microscope equipped wit focus d ion beam tech ique. Distinctive mechanism of the crack nucle tion was observe for different loa ing conditions. The isothermal fatigue loading in the air resulted in t e early initiation of the cracks from the oxidized grain boundaries arranged perpendicularly to the loading axis. The signifi n change was reveal d for the specimens strained under high vacuum conditions. The crack w s found to be nucleated due to cavity formation and their subs quent mutual coalesc ce du ing further loading. Moreover, the crack formation was observed in the interior of the material. The effect of the environmentally related damage mechanism is documented. © 201 9 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. 9th International Conference on Materials Structure and Micromechanics of Fracture Effect of an environment in stainless steel on the damage mechanisms under LCF conditions Roman Petr áš a,b * , Jaroslav Polák a,b a Institute of Physics of Materials ASCR, Žižkova 22, 616 62 Brno, Czech Republic b CEITEC, Institute of Physics of Materials ASCR, Žižkova 22, 616 62 Brno, Czech Republic 9th International Conference on Materials Structure and Micromechanics of Fracture Effect of an environment in stainless steel on the damage mechanisms under LCF conditions Roman Petr áš a,b * , Jaroslav Polák a,b a Institute of Physics of Materi ls ASCR, Žižkova 22, 616 2 Brno, Czech Republic b CEITEC, Institute of Physics of Materials ASCR, Žižkova 22, 616 62 Brno, Czech Republic Abstract Abstract The effect of an environment on the damage mechanism was addressed in this study. Super austenitic steel Sanicro 25 grade was subjected to isothermal elasto-plastic cyclic loading at 700 °C. The material was exposed to different environmental conditions to assess the effect of laboratory air comparing to high vacuum. The mechanism of the crack nucleation was the matter of the inquiry by means of scanning electron microscope equipped with focused ion beam technique. Distinctive mechanism of the crack nucleation was observed for different loading conditions. The isothermal fatigue loading in the air resulted in the early initiation of the cracks from the oxidized grain boundaries arranged perpendicularly to the loading axis. The significant change was revealed for the specimens strained under high vacuum conditions. The crack was found to be nucleated due to cavity formation and their subsequent mutual coalescence during further loading. Moreover, the crack formation was observed in the interior of the material. The effect of the environmentally related damage mechanism is documented.

Keywords: LCF, environment, Sanicro 25, dagmage mechanism, FIB cutting, grain boundary cracking Keywords: LCF, environment, Sanicro 25, dagmage mechanism, FIB cutting, grain boundary cracking

1. Introduction 1. Introduction

The damage evolution significantly depends on the actual loading conditions implemented. In addition to the operating parameters such as loading waveform, total strain amplitude and strain rate along with the temperature The damage volution significa tly depends on the actual loading co itions impleme ted. In addition to th operating parameters such as loading waveform, total strain amplitude and strain rate along with the temperature

* Roman Pet ráš . Tel.: +420-532-290-345.. E-mail address: petras@ipm.cz * Ro an Pet áš . Tel.: +420-532-290-345.. E-mail address: petras@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.2020.01.088