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27 results on '"Hilšer, Ondřej"'

5. Mechanism of Grain Refinement in 3D-Printed AlSi10Mg Alloy Subjected to Severe Plastic Deformation.

Author

Snopiński, Przemysław and Hilšer, Ondřej

Subjects
*GRAIN refinement, *TRANSMISSION electron microscopy, *SCANNING electron microscopy, *MATERIAL plasticity, *ELECTRON diffraction
Abstract

In this article, the evolution of microstructural characteristics of selectively laser-melted AlSi10Mg alloy subjected to equal channel angular pressing (ECAP) is investigated. The microstructures were analyzed in detail using scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission Kikuchi diffraction (TKD), and transmission electron microscopy (TEM). A heterogeneous ultrafine-grained microstructure was produced after one ECAP pass at 100 °C. This microstructure was composed of Al/Si cells and sub-micrometer grains. The grains were refined by conventional dislocation processes; however, evidence of dynamic recrystallization was also documented. Furthermore, it was revealed that the Al/Si cells contribute significantly to grain refinement. EBSD/TKD investigations showed that cell misorientation increased after ECAP processing, resulting in an increased fraction of grains with very low misorientation angles. [ABSTRACT FROM AUTHOR]

Published
2024
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13. thermal stability of serely deformed Almg3 sheets

Author

HILŠER, Ondřej, primary, SNOPIŃSKI, Przemysław, additional, RUSZ, Stanislav, additional, TAŃSKI, Tomasz, additional, MAZIARZ, Wojciech, additional, STAN-GŁOWIŃSKA, Katarzyna, additional, and GREGER, Miroslav, additional

Published
2020
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14. Influence of SPD process on low-carbon steel mechanical properties

Author

Rusz, Stanislav, Hilšer, Ondřej, Ochodek, Vladislav, Čada, Radek, Švec, Jiří, and Szkandera, Pavel

Subjects
low-carbon steel, residual stress, magnetoelastic method, mechanical properties, steel strip, severe plastic deformation
Abstract

Paper analyses the influence of different values of the angle of the deformation zone in the forming tool on severe plastic deformation (SPD) process and on mechanical properties of resulting steel strip. Forming equipment using the severe plastic deformation (SPD) process and DRECE (Dual Rolling Equal Channel Extrusion) method builded and installed in the laboratory for the development of new technologies at the Faculty of Mechanical Engineering of VSB - Technical University of Ostrava is described. Tests were carried out at selected low-carbon deep-drawing steel DC01. By magnetoelastic method the residual stresses in material after separate passes were analyzed. DRECE method of forming brings compression stress into the material, which is favorable for further use. Web of Science 2019 2914 2910

Published
2019

15. Microstructure and texture changes of MgLiAl alloys composed of alpha or alpha plus beta phases after twist channel angular pressing tcap

Author

Dutkiewicz, Jan, Rusz, Stanislav, Kuc, Dariusz, Hilšer, Ondřej, Bobrowski, Piotr, and Kania, Bobusz

Subjects
texture after TCAP, Li2MgAl precipitates, twist channel angular pressing TCAP, MgLiAl alloys
Abstract

Two MgLiAl alloys of composition 4.5% Li and 1.5% Al (in wt.%) composed of alpha phase and of 9% Li, 1.5% Al composed of alpha(hcp) + beta(bcc) phases were subjected to twist channel angular pressing (TCAP) deformation. Such deformation of alpha + beta alloys caused less effective grain refinement than that of single alpha phase alloy. However, with increasing number of passes, grain size of single alpha phase alloy increased and that of beta phase in two phase alpha + beta alloy also grew, which suggested the effect of dynamic recrystallization. TEM studies allowed identifying particles of Li2MgAl phase of size of few mu m. {001} texture was observed in extruded alloy. Texture studies of extruded and TCAPed single phase hcp alloy indicated texture with {10 (1) over bar0} plane perpendicular to the extrusion direction and {0002} plane parallel to the extrusion direction. Duplex alpha + beta alloys showed poor texture development. Web of Science 63 4 1835 1827

Published
2018

23. Possibilities of application methods drece in forming of non-ferrous metals

Author

Rusz, Stanislav, Kłyszewski, A., Salajka, Michal, Hilšer, Ondřej, Čížek, Lubomír, and Klos, Marcel

Subjects
formability, grain refinement, mechanical properties, new design of forming tool, severe plastic deformation
Abstract

Device “DRECE - Dual Rolls Equal Channel Extrusion” is used for production of metallic materials with very fine grain size (UFG). During the actual forming process the principle of severe plastic deformation is used. Metallic strip with dimensions 57×2×1000 mm is inserted into the device. During the forming process the main cylinder in synergy with the pressure roller extrude the material through the forming tool without any change of cross section of the strip. In this way a significant refinement of grain is achieved by severe plastic deformation. This method is used for various types of metallic materials, non-ferrous metals and their alloys. The DRECE device is also being verified from the viewpoint of achievement of a UFG structure in a blank of circular cross-section (wire) with diameter of ϕ 8 mm × 1000 mm. Web of Science 60 4 3015 3011

Published
2015

26. Studium vlastností vybraných Mg slitin tvářených procesem ECAP

Author

Rusz, Stanislav, Hilšer, Ondřej, Rusz, Stanislav, and Hilšer, Ondřej

Abstract

Diplomová práce se zabývá vlivem technologií SPD na mechanické vlastnosti vybraných druhů hořčíkových slitin. Teoretická část této práce obsahuje výčet nejčastěji aplikovaných metod využívajících extrémní plastické deformace za účelem zjemnění výsledné struktury a dosažení nadstandardních mechanických vlastností. Praktická část publikace je zaměřena na realizaci protlačení Mg slitin AZ31 a AZ61 tvářecím nástrojem ECAP, dále je zkoumán vliv vstupního tepelného zpracování T4 na výslednou strukturu a mechanické vlastnosti. Výsledky získané z experimentálních prací jsou dále podrobně rozebrány v závěrečné části práce., Master thesis examines the influence of SPD technologies on the mechanical properties of selected types of magnesium alloys. The theoretical part of the thesis contains a list of the most frequently applied methods based of extreme plastic deformation with goal the obtain good grain refinement of selected alloys with superior mechanical properties. The practical part of the thesis is focused on the realization extrusion process of AZ31 and AZ61 alloy by ECAP process. In the next part of thesis is performed the analyze of influence of input heat treatment T4 on the final structure and mechanical properties. The results obtained of experiments are discussed in final part of thesis., Ve zpracování, Import 05/08/2014

Published
2014

27. An Investigation into Sheet-Inconel 718 Forming with Flexible and Metal Tools-Simulation and Experiment.

Author

Balcerzak M, Rusz S, Čada R, Pastrňák M, Hilšer O, and Greger M

Abstract

The article presents the results of numerical simulations and experimental tests of plastic forming sheets made from the difficult-to-deform nickel alloy Inconel 718 with a thickness of 1 mm, using punches made from elastomeric materials with hardness 50-90 Shore A and steel dies. Elastomeric stamps were created in the form of five layers with a diameter of 160 mm. The influence of the hardness of the elastomeric punches on the geometry of the elements obtained was determined. The dies were made from 90MnCrV8 steel with a hardness of over 60 HRC. Their task was to obtain the expected shape of the element while generating various stress states in specific areas of the semi-finished product. The research was carried out using an original device whose operating principle was based on the Guerin method. The shape and dimensions of the elements made from Inconel 718 nickel alloy were determined by optical 3D scanning. The geometry of the drawpiece showed a significant impact of the hardness of the layered elastomer matrices on the degree of shape reproduction. The results obtained from numerical modeling were confirmed by the results of experimental tests. It has been shown that the hardness of the elastomeric material used for punches for plastic forming Inconel 718 nickel alloy sheets should be adapted to the shape of the drawpiece. It was also found that one of the important aspects of plastic forming sheets using the Guerin method is the tendency to obtain a diversified shape of the final elements.

Published
2024
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