Microstructure of Commercial Purity Titanium Subjected to Complex Loading by the Kobo Method

Observations of refined microstructure of Commercial Purity titanium for applications in biomedical devices has been carried out. Refinement of titanium microstructure has been performed in process with complex strain scheme. Materials investigated in this work were: Commercial Purity titanium grade...

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Main Authors: Kawałko J., Bieda M., Sztwiertnia K.
Format: Article
Language:English
Published: Polish Academy of Sciences 2016-03-01
Series:Archives of Metallurgy and Materials
Subjects:
SPD
Online Access:http://www.degruyter.com/view/j/amm.2016.61.issue-1/amm-2016-0002/amm-2016-0002.xml?format=INT
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spelling doaj-e6bd5084817b467fa689b3175e2c41012020-11-25T03:26:30ZengPolish Academy of SciencesArchives of Metallurgy and Materials2300-19092016-03-01611313610.1515/amm-2016-0002amm-2016-0002Microstructure of Commercial Purity Titanium Subjected to Complex Loading by the Kobo MethodKawałko J.0Bieda M.1Sztwiertnia K.2Institute of Metallurgy and Materials Science Polish Academy of Sciences, 25 reymonta str., 30-059 Kraków, PolandInstitute of Metallurgy and Materials Science Polish Academy of Sciences, 25 reymonta str., 30-059 Kraków, PolandInstitute of Metallurgy and Materials Science Polish Academy of Sciences, 25 reymonta str., 30-059 Kraków, PolandObservations of refined microstructure of Commercial Purity titanium for applications in biomedical devices has been carried out. Refinement of titanium microstructure has been performed in process with complex strain scheme. Materials investigated in this work were: Commercial Purity titanium grade 2 and grade 4. Samples of as received materials were subjected to plastic deformation in complex loading process of extrusion combined with oscillation twisting (KoBo extrusion). Both types of samples were deformed in single step of extrusion, in temperature of 450 °C, with extrusion ratio 19.14 and 12.25 for grade 2 titanium and grade 4 titanium, respectively. Initial mean grain diameter for both types of materials was approximately 30 μm. Samples were investigated by means of crystal orientation microscopy. In both cases considerable microstructure refinement has been observed. Microstructures of deformed samples are heterogenous and consist of both elongated and fine equiaxed grains. Elongated grains (lamellae) are separated by High Angle Grain Boundaries and feature internal structure with subgrains and dislocation walls. Grain refinement is stronger in material with higher extrusion ratio and mean grain diameter in this case is equal to 1.48 μm compared to 8.07 μm. in material with lower extrusion ratio. Mean misorientation angle (24° and 27° for grade 4 and grade 2 titanium) indicates high fraction of HAGBs in microstructures of KoBo deformed samples. Misorientation fluctuations inside grains have been analyzed and distinct curvature of crystal lattice have been observed. Hardness of samples after plastic deformation increased from 174.6±3.4 and 234.9±3.5 to 205.0±3.2 and 251.2±2.2 for titanium grade 2 and grade 4 respectively.http://www.degruyter.com/view/j/amm.2016.61.issue-1/amm-2016-0002/amm-2016-0002.xml?format=INTCommercial Purity TitaniumPlastic deformationSPDKoBoMicrostructureEBSD
collection DOAJ
language English
format Article
sources DOAJ
author Kawałko J.
Bieda M.
Sztwiertnia K.
spellingShingle Kawałko J.
Bieda M.
Sztwiertnia K.
Microstructure of Commercial Purity Titanium Subjected to Complex Loading by the Kobo Method
Archives of Metallurgy and Materials
Commercial Purity Titanium
Plastic deformation
SPD
KoBo
Microstructure
EBSD
author_facet Kawałko J.
Bieda M.
Sztwiertnia K.
author_sort Kawałko J.
title Microstructure of Commercial Purity Titanium Subjected to Complex Loading by the Kobo Method
title_short Microstructure of Commercial Purity Titanium Subjected to Complex Loading by the Kobo Method
title_full Microstructure of Commercial Purity Titanium Subjected to Complex Loading by the Kobo Method
title_fullStr Microstructure of Commercial Purity Titanium Subjected to Complex Loading by the Kobo Method
title_full_unstemmed Microstructure of Commercial Purity Titanium Subjected to Complex Loading by the Kobo Method
title_sort microstructure of commercial purity titanium subjected to complex loading by the kobo method
publisher Polish Academy of Sciences
series Archives of Metallurgy and Materials
issn 2300-1909
publishDate 2016-03-01
description Observations of refined microstructure of Commercial Purity titanium for applications in biomedical devices has been carried out. Refinement of titanium microstructure has been performed in process with complex strain scheme. Materials investigated in this work were: Commercial Purity titanium grade 2 and grade 4. Samples of as received materials were subjected to plastic deformation in complex loading process of extrusion combined with oscillation twisting (KoBo extrusion). Both types of samples were deformed in single step of extrusion, in temperature of 450 °C, with extrusion ratio 19.14 and 12.25 for grade 2 titanium and grade 4 titanium, respectively. Initial mean grain diameter for both types of materials was approximately 30 μm. Samples were investigated by means of crystal orientation microscopy. In both cases considerable microstructure refinement has been observed. Microstructures of deformed samples are heterogenous and consist of both elongated and fine equiaxed grains. Elongated grains (lamellae) are separated by High Angle Grain Boundaries and feature internal structure with subgrains and dislocation walls. Grain refinement is stronger in material with higher extrusion ratio and mean grain diameter in this case is equal to 1.48 μm compared to 8.07 μm. in material with lower extrusion ratio. Mean misorientation angle (24° and 27° for grade 4 and grade 2 titanium) indicates high fraction of HAGBs in microstructures of KoBo deformed samples. Misorientation fluctuations inside grains have been analyzed and distinct curvature of crystal lattice have been observed. Hardness of samples after plastic deformation increased from 174.6±3.4 and 234.9±3.5 to 205.0±3.2 and 251.2±2.2 for titanium grade 2 and grade 4 respectively.
topic Commercial Purity Titanium
Plastic deformation
SPD
KoBo
Microstructure
EBSD
url http://www.degruyter.com/view/j/amm.2016.61.issue-1/amm-2016-0002/amm-2016-0002.xml?format=INT
work_keys_str_mv AT kawałkoj microstructureofcommercialpuritytitaniumsubjectedtocomplexloadingbythekobomethod
AT biedam microstructureofcommercialpuritytitaniumsubjectedtocomplexloadingbythekobomethod
AT sztwiertniak microstructureofcommercialpuritytitaniumsubjectedtocomplexloadingbythekobomethod
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