Preparation of Carbide-Free Bainitic Steels for EBSD Investigations
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C. Hofer
Christina Hofer graduated in Materials Science at the Montanuniversität Leoben in 2012. She carried out her Master’s Thesis in cooperation with the University of Berkeley, California. Currently, she is working on her PhD on the phase characterization of advanced high strength steels for the automotive industry.Sophie Primig is the head of the „High Performance Materials and Steels“ group at the Department of Physical Metallurgy and Materials Testing, Montanuniversitaet Leoben, Austria. In her projects with both industrial and scientific focus, she studies advanced microstructure-property relationships that will enable the design of the future generation of structural materials.
Abstract
Carbide-free bainitic steels are composed of bainitic ferrite laths, which are separated by films and larger islands of austenite, which is stabilized by carbon enrichment. Due to their multi-phase microstructure, the preparation of such steels for a characterization by means of electron backscatter diffraction (EBSD) represents a challenge. Attention must particularly be paid to prevent the transformation of the retained austenite to martensite during the preparation. This study compares the sample preparation by vibratory polishing using different suspensions to the electrolytic preparation. During vibratory polishing, it must be ensured that very little force is applied in order to prevent the metastable austenite from transforming. No influence of the different suspensions could be found. Electropolishing with a voltage of 40 V for 10 s at 23 °C is well suited for microstructural investigations. However, the surface relief is too pronounced for EBSD analyses. OP-U polishing for 15 min subsequent to electropolishing accomplishes the best results.
Kurzfassung
Karbidfreie bainitische Stähle bestehen aus bainitischen Ferritlatten, welche von durch Kohlenstoffanreicherung stabilisierten Restaustenitfilmen getrennt werden, und größeren Restaustenitinseln. Die Präparation dieser Stähle für eine Charakterisierung mittels Electron Back-Scatter Diffraction (EBSD) stellt aufgrund des mehrphasigen Gefüges eine Herausforderung dar. Vor allem ist darauf zu achten, dass der Restaustenit nicht während der Präparation in Martensit umklappt. In dieser Arbeit wurden die Probenvorbereitung mittels Vibrationspolieren mit verschiedenen Suspensionen und die elektrolytische Präparation verglichen. Beim Vibrationspolieren muss darauf geachtet werden, dass mit wenig Kraft poliert wird, um das Umklappen des metastabilen Austenits möglichst zu verhindern. Es wurde kein Einfluss der unterschiedlichen Suspensionen festgestellt. Elektrolytisches Polieren mit einer Spannung von 40 V für 10 s bei 23 °C eignet sich sehr gut für Gefügeuntersuchungen, jedoch ist das Oberflächenrelief für EBSD-Analysen zu stark ausgeprägt. OP-U Polieren für 15 min, im Anschluss an das Elektropolieren, führt zu den besten Ergebnissen.
About the authors
Christina Hofer graduated in Materials Science at the Montanuniversität Leoben in 2012. She carried out her Master’s Thesis in cooperation with the University of Berkeley, California. Currently, she is working on her PhD on the phase characterization of advanced high strength steels for the automotive industry.
Sophie Primig is the head of the „High Performance Materials and Steels“ group at the Department of Physical Metallurgy and Materials Testing, Montanuniversitaet Leoben, Austria. In her projects with both industrial and scientific focus, she studies advanced microstructure-property relationships that will enable the design of the future generation of structural materials.
Acknowledgements
The authors would like to thank the voestalpine Stahl Linz GmbH for providing the material. Furthermore, we would like to thank Prof. Roumen Petrov and MSc. An Verdiere for their support with the sample preparation.
Danksagung
Die Autoren möchten sich bei voestalpine Stahl Linz GmbH für das zur Verfügung gestellte Material bedanken. Des Weiteren wird Prof. Roumen Petrov und MSc. An Verdiere Dank für die Unterstützung bei der Probenpräparation ausgesprochen.
References / Literatur
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© 2015 Walter de Gruyter GmbH, Berlin/Boston, Germany
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- Editorial
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- The Quality of Prepared Specimens of Si-Wafers for Raman Spectroscopy
- Investigation of the Self Tempering Effect of Martensite by Means of Atom Probe Tomography
- Preparation of Carbide-Free Bainitic Steels for EBSD Investigations
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- Top-ten downloads / Picture of the month
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Articles in the same Issue
- Contents
- Editorial
- Editorial
- The Quality of Prepared Specimens of Si-Wafers for Raman Spectroscopy
- Investigation of the Self Tempering Effect of Martensite by Means of Atom Probe Tomography
- Preparation of Carbide-Free Bainitic Steels for EBSD Investigations
- LCF Coupling Failure in a Two-Feet Light Railway
- Top-ten downloads / Picture of the month
- Top-Ten Article Downloads
- Picture of the Month
- PM-News
- PM-News
- Meeting diary
- Meeting diary
