PSI - Issue 17

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

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Procedia Structural Integrity 17 (2019) 427–433

ICSI 2019 The 3rd International Conference on Structural Integrity Microstructure evolution and creep strength of new-generation oxide dispersion strengthened alloys with high volume fraction of nano-oxides Petr Dymáček a * , Jiří Svoboda a , Hana Jirková b , Luděk Stratil a , Vít Horník a,c ICSI 2019 The 3rd International Conference on Structural Integrity Microstructure evolution and creep strength of new-generation oxide dispersion strengthened alloys with high volume fraction of nano-oxides Petr Dymáček a * , Jiří Svoboda a , Hana Jirková b , Luděk Stratil a , Vít Horník a,c a Institute of Physics of Materials, Czech Academy of Sciences , Žižkova 22, 616 62 Brno, Czech Republic b University of West Bohemia, Regional Technological Institute Univerzitní 8, 306 14 Plzeň, Czech Republic c Brno University of Technology, Faculty of Mechanical Engineering, Technická 2, 616 69 Brno, Czech Republic a I stitute of Phy ics f Materials, Czech Academy of Sciences , Žižkova 22, 616 2 Brno, Czech Republic b University of West Bohemia Regional Technological I stitute Univ rzitní 8, 30 14 Plzeň, Czech Republic c Brno University of Technology, Faculty of Mechanical Engineering, Technická 2, 616 69 Brno, Czech Republic Four creep resistant Fe-based oxide dispersion strengthened (ODS) alloys with a significantly high amount of dispersed oxide nanoprecipitates have been investigated. One Fe-Al-O and three Fe-Al-Cr-Mo-Y 2 O 3 systems with different chemical composition strengthened by yttrium nano-oxides have been prepared by mechanical alloying of powders and consolidation by hot rolling leading to ultrafine grained microstructure due to dynamic recrystallization. The thermal stability of the precipitates, effects of the processing on the microstructure (grain and precipitate size) and mechanical properties at high temperatures have been evaluated. It has been found that the rolling temperature has a significant effect on the static recrystallization process during the subsequent heat treatment and on the resulting grain size of the alloys and does not affect the size of nano-oxides and their dispersion. Tensile tests performed at a low constant rate of 10 -6 s -1 allow a quick estimate of the creep strength and helps to a quick identification of optimum processing conditions. It was found that the mechanism of the fracture is changing from trans-granular to inter-granular between 600 and 800 °C which leads to a significant drop of ductility. The set of mechanical tests has been completed also for 1100 °C indicating a rather high applicability potential of the investigated system. Four cree resistant Fe-based oxide dispersion strengthened (ODS) alloys with a significantly high amount of dispersed oxide nanoprecipitates have been investigated. One Fe-Al-O an three Fe-Al-Cr-Mo-Y 2 O 3 systems with different chemical composition strengthened by yttrium nano-oxides have b en prepared by mechanical alloying of powders and consolidation by hot r lling leading to ultrafine grained microstructure due to dynamic recrystallization. The thermal stability of the pr cipitates, ff cts of the processing on the microstructure (grain and precipitate size) and mechanical properties at high temperatures have been evaluat d. It has been found that the rolling temperature has a significant effect on the static recrystallization process during the subsequent heat tr atment and on the resulting grain size of the alloys and does not affect the size of nano-oxides and their dispersion. Tensile tests performed at a low constant rate of 10 -6 s -1 allow a quick estimate of the creep strength and helps to a q ick ide tification of optimum processing conditions. It was found that the mechanism of the fracture is changing from trans-granular to inter-granular between 600 and 800 °C which le ds to a sig ificant drop of ductility. Th set of mechanical tests has been completed also for 1100 °C indicating a rather high applicability potential of the investigated system. Abstract Abstract

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. Keywords: nano-oxide; dispersion; creep; fracture; high temperature Keywords: nano-oxide; dispersion; creep; fracture; high temperature

* Corresponding author. Tel.: +420-532-290-411. E-mail address: pdymacek@ipm.cz * Correspon ing author. T l.: +420-532-290-411. E-mail address: pdymacek@ipm.cz

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers.

2452-3216  2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ICSI 2019 organizers. 10.1016/j.prostr.2019.08.056