G. Stornelli, A. Schino, R. Montanari, C. Testani, A. Varone, S. Mancini
The reduced activation martensitic steel EUROFER97 is recognized in Europe as the reference steel for structural applications in future nuclear fusion reactors. Usually, EUROFER97 steel plates are manufactured by hot rolling and successive heat treatments: (1) austenitization at 980 °C for 30 min, (2) air cooling, and (3) tempering at 760 °C for 90 min. Recently, thermo-mechanical treatments have been investigated by us with the scope to improve the mechanical properties, namely, to strengthen the steel without reducing its ductility. The experiments involve cold rolling with three reduction rates (30%, 40%, 50%) and, for each of them, heat treatments at different temperatures in the range from 550 °C to 750 °C. The mechanical and microstructural characterization of the samples after successive stages of the process is now underway and present work reports some preliminary results. The characteristics of the samples after cold rolling have been examined by means of hardness tests, metallography, and X-ray diffraction measurements, and work-hardening is discussed in terms of dislocation density.
{"title":"Work-hardening behavior of cold rolled EUROFER97 steel for nuclear fusion applications","authors":"G. Stornelli, A. Schino, R. Montanari, C. Testani, A. Varone, S. Mancini","doi":"10.3390/IEC2M-09242","DOIUrl":"https://doi.org/10.3390/IEC2M-09242","url":null,"abstract":"The reduced activation martensitic steel EUROFER97 is recognized in Europe as the reference steel for structural applications in future nuclear fusion reactors. Usually, EUROFER97 steel plates are manufactured by hot rolling and successive heat treatments: (1) austenitization at 980 °C for 30 min, (2) air cooling, and (3) tempering at 760 °C for 90 min. Recently, thermo-mechanical treatments have been investigated by us with the scope to improve the mechanical properties, namely, to strengthen the steel without reducing its ductility. The experiments involve cold rolling with three reduction rates (30%, 40%, 50%) and, for each of them, heat treatments at different temperatures in the range from 550 °C to 750 °C. The mechanical and microstructural characterization of the samples after successive stages of the process is now underway and present work reports some preliminary results. The characteristics of the samples after cold rolling have been examined by means of hardness tests, metallography, and X-ray diffraction measurements, and work-hardening is discussed in terms of dislocation density.","PeriodicalId":429720,"journal":{"name":"Proceedings of The 1st International Electronic Conference on Metallurgy and Metals","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114318877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
: The fabrication of semi-finished hot and cold rolled sheets includes a complex evolution of both microstructure and texture to meet the demanded mechanical properties and suitable formability characteristics. The desired mechanical properties along with the optimum grain size can be obtained through the control of both recovery and recrystallization processes. This work examines the effect of recovery and recrystallization on the resulting crystallographic texture and on the local plastic deformation. A processing approach for EBSD-KAM (Electron Back Scatter Diffraction— Kernel average misorientation) evaluation is suggested with the purpose of effectively evaluating all the possible misorientation angles in-between the grains and of observing the recovery phenom-enon from a different point of view. The results showed that although texture components did not alternate significantly during recovery, the fraction of sub-grain boundaries was increased indicating the completion of recovery at the selected temperature exhibited a maximum value of 90%. The initiation of recrystallization was illustrated by a different aspect, underlying newly formed grains and points which exhibited high misorientation angle, for the evolution of the recrystallization process and texture evolution.
{"title":"Methodology for the identification of nucleation sites in aluminum alloy by use of misorientation mapping","authors":"S. Papadopoulou, E. Gavalas, S. Papaefthymiou","doi":"10.3390/IEC2M-09251","DOIUrl":"https://doi.org/10.3390/IEC2M-09251","url":null,"abstract":": The fabrication of semi-finished hot and cold rolled sheets includes a complex evolution of both microstructure and texture to meet the demanded mechanical properties and suitable formability characteristics. The desired mechanical properties along with the optimum grain size can be obtained through the control of both recovery and recrystallization processes. This work examines the effect of recovery and recrystallization on the resulting crystallographic texture and on the local plastic deformation. A processing approach for EBSD-KAM (Electron Back Scatter Diffraction— Kernel average misorientation) evaluation is suggested with the purpose of effectively evaluating all the possible misorientation angles in-between the grains and of observing the recovery phenom-enon from a different point of view. The results showed that although texture components did not alternate significantly during recovery, the fraction of sub-grain boundaries was increased indicating the completion of recovery at the selected temperature exhibited a maximum value of 90%. The initiation of recrystallization was illustrated by a different aspect, underlying newly formed grains and points which exhibited high misorientation angle, for the evolution of the recrystallization process and texture evolution.","PeriodicalId":429720,"journal":{"name":"Proceedings of The 1st International Electronic Conference on Metallurgy and Metals","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130837564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gas bubble behavior on a carbon anode in a cryolite melt have been studied by direct observation using a see-through cell. The bubble phenomena studied have been growth, coalescence and detachment during electrolysis. The anode geometry and surface orientation affect bubbles behavior. Therefore, two different anodes were tested, an anode with a horizontal facing-downwards surface and an anode with a vertical surface. Galvanostatic and potentiostatic measurements were performed for different current densities and different potentials with simultaneous video recording. At the horizontal anode for a constant current density/potential it was found that one large bubble was formed by growth and coalescence of smaller bubbles and finally the large bubble detached periodically. The frequency of the bubble release events observed from the video recordings was in agreement with the dominant frequency from the Fast Fourier Transform (FFT) analysis. For the vertical anode surface smaller bubbles were formed and detached either due to being pushed by the formation of other bubbles or by coalescence obtaining enough buoyancy. FFT analysis gave no dominant frequency. The diameter of detached bubbles from the horizontal surface and vertical surface was measured. The value was in a range 5.7 mm to 7.2 mm for the horizontal surface and in a range 1.5 mm to 3.7 mm for the vertical surface, strongly depending on the applied current density. The bubble diameter was decreasing with increasing current density for both surfaces. The smaller bubble diameter might be explained by a larger bubble induced convection and increased wetting.
{"title":"Bubble Behavior on Horizontal and Vertical Carbon Anode Surfaces in Cryolite Melt Applying a See-Through Cell","authors":"Nikolina Stanic, E. Sandnes","doi":"10.3390/IEC2M-09238","DOIUrl":"https://doi.org/10.3390/IEC2M-09238","url":null,"abstract":"Gas bubble behavior on a carbon anode in a cryolite melt have been studied by direct observation using a see-through cell. The bubble phenomena studied have been growth, coalescence and detachment during electrolysis. The anode geometry and surface orientation affect bubbles behavior. Therefore, two different anodes were tested, an anode with a horizontal facing-downwards surface and an anode with a vertical surface. Galvanostatic and potentiostatic measurements were performed for different current densities and different potentials with simultaneous video recording. At the horizontal anode for a constant current density/potential it was found that one large bubble was formed by growth and coalescence of smaller bubbles and finally the large bubble detached periodically. The frequency of the bubble release events observed from the video recordings was in agreement with the dominant frequency from the Fast Fourier Transform (FFT) analysis. For the vertical anode surface smaller bubbles were formed and detached either due to being pushed by the formation of other bubbles or by coalescence obtaining enough buoyancy. FFT analysis gave no dominant frequency. The diameter of detached bubbles from the horizontal surface and vertical surface was measured. The value was in a range 5.7 mm to 7.2 mm for the horizontal surface and in a range 1.5 mm to 3.7 mm for the vertical surface, strongly depending on the applied current density. The bubble diameter was decreasing with increasing current density for both surfaces. The smaller bubble diameter might be explained by a larger bubble induced convection and increased wetting.","PeriodicalId":429720,"journal":{"name":"Proceedings of The 1st International Electronic Conference on Metallurgy and Metals","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122917105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Stornelli, P. Folgarait, M. Ridolfi, Domenico Corapi, Christian Repitsch, Orlando Di Pietro, A. Schino
Currently, the commercial production of ferromagnetic cores involves staking thin sheets of soft magnetic material, alternating with dielectric material to reduce the eddy current losses. High silicon FeSi steels show excellent soft magnetic properties. Anyway, their workability decreases Si content increases thus imposing a technological limit in the production of thin sheets up to 3.5–4% Si. The additive manufacturing (AM) process based on laser powder bed fusion (L-PBF) offers the possibility to redesign the magnetic components, compared to conventional design, allowing to act on the chemical composition of magnetic materials and on the geometry of the components. In the case of FeSi alloys, the additive technology allows to overcome the limit of Si content opening new perspectives for the production of ferromagnetic cores with high magnetic performance. In this work the feasibility study on the production of FeSi magnetic steel components by L-PBF technology is reported. Two variants of FeSi steels, with Si content of 3.0 wt.% and 6.5 wt.%, were considered. The effect of process parameters on the densification of manufactured parts was investigated. The best operating window has been identified for both steel chemical compositions, in terms of laser scan speed and power.
{"title":"Feasibility study of ferromagnetic cores fabrication by additive manufacturing process","authors":"G. Stornelli, P. Folgarait, M. Ridolfi, Domenico Corapi, Christian Repitsch, Orlando Di Pietro, A. Schino","doi":"10.3390/IEC2M-09241","DOIUrl":"https://doi.org/10.3390/IEC2M-09241","url":null,"abstract":"Currently, the commercial production of ferromagnetic cores involves staking thin sheets of soft magnetic material, alternating with dielectric material to reduce the eddy current losses. High silicon FeSi steels show excellent soft magnetic properties. Anyway, their workability decreases Si content increases thus imposing a technological limit in the production of thin sheets up to 3.5–4% Si. The additive manufacturing (AM) process based on laser powder bed fusion (L-PBF) offers the possibility to redesign the magnetic components, compared to conventional design, allowing to act on the chemical composition of magnetic materials and on the geometry of the components. In the case of FeSi alloys, the additive technology allows to overcome the limit of Si content opening new perspectives for the production of ferromagnetic cores with high magnetic performance. In this work the feasibility study on the production of FeSi magnetic steel components by L-PBF technology is reported. Two variants of FeSi steels, with Si content of 3.0 wt.% and 6.5 wt.%, were considered. The effect of process parameters on the densification of manufactured parts was investigated. The best operating window has been identified for both steel chemical compositions, in terms of laser scan speed and power.","PeriodicalId":429720,"journal":{"name":"Proceedings of The 1st International Electronic Conference on Metallurgy and Metals","volume":"14 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129116199","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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