Investigation of the mechanism of the indentation size effect for titanium

In this study, we investigated the mechanism of the indentation size effect for Ti, whose crystal structure is hexagonal close-packed. Indentation tests were performed for two types of single-crystal Ti with different crystal orientations: (0001) and (1120). Indentation tests were also performed wit...

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Autores principales:	Shota HASUNUMA, Hirohisa MIYAZAKI, Takeshi OGAWA
Formato:	article
Lenguaje:	EN
Publicado:	The Japan Society of Mechanical Engineers 2019
Materias:	indentation tests indentation size effect titanium geometrically necessary dislocation electron backscatter diffraction Mechanical engineering and machinery TJ1-1570
Acceso en línea:	https://doaj.org/article/ab341fee769049b3ba5e76ccae986288
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spelling	oai:doaj.org-article:ab341fee769049b3ba5e76ccae9862882021-11-29T05:40:47ZInvestigation of the mechanism of the indentation size effect for titanium2187-974510.1299/mej.18-00545https://doaj.org/article/ab341fee769049b3ba5e76ccae9862882019-04-01T00:00:00Zhttps://www.jstage.jst.go.jp/article/mej/6/2/6_18-00545/_pdf/-char/enhttps://doaj.org/toc/2187-9745In this study, we investigated the mechanism of the indentation size effect for Ti, whose crystal structure is hexagonal close-packed. Indentation tests were performed for two types of single-crystal Ti with different crystal orientations: (0001) and (1120). Indentation tests were also performed with different indenter directions. The hardness depends on the crystal orientation and indenter direction because Ti has large anisotropy. The shape of the impression also changes with the crystal orientation and indenter direction. The hardness increases with decreasing penetration depth for the (0001) and (1120) orientations, so the indentation size effect occurs. For the (0001) orientation, a sudden rapid increase in displacement occurs during indentation tests owing to twinning. This sudden rapid increase in displacement causes a rapid decrease in the hardness. Electron backscatter diffraction was performed around the impressions to measure the geometrically necessary (GN) dislocation density. The GN dislocation density increases with decreasing penetration depth for the (0001) and (1120) orientations. This trend corresponds to strain gradient theory. The reason for the indentation size effect in Ti is the increase in the GN dislocation density. For the (0001) orientation, the indentation size effect also can be attributed to twinning. Considering both our previous study and this study, the experimental results correspond to strain gradient theory in many cases.Shota HASUNUMAHirohisa MIYAZAKITakeshi OGAWAThe Japan Society of Mechanical Engineersarticleindentation testsindentation size effecttitaniumgeometrically necessary dislocationelectron backscatter diffractionMechanical engineering and machineryTJ1-1570ENMechanical Engineering Journal, Vol 6, Iss 2, Pp 18-00545-18-00545 (2019)
institution	DOAJ
collection	DOAJ
language	EN
topic	indentation tests indentation size effect titanium geometrically necessary dislocation electron backscatter diffraction Mechanical engineering and machinery TJ1-1570
spellingShingle	indentation tests indentation size effect titanium geometrically necessary dislocation electron backscatter diffraction Mechanical engineering and machinery TJ1-1570 Shota HASUNUMA Hirohisa MIYAZAKI Takeshi OGAWA Investigation of the mechanism of the indentation size effect for titanium
description	In this study, we investigated the mechanism of the indentation size effect for Ti, whose crystal structure is hexagonal close-packed. Indentation tests were performed for two types of single-crystal Ti with different crystal orientations: (0001) and (1120). Indentation tests were also performed with different indenter directions. The hardness depends on the crystal orientation and indenter direction because Ti has large anisotropy. The shape of the impression also changes with the crystal orientation and indenter direction. The hardness increases with decreasing penetration depth for the (0001) and (1120) orientations, so the indentation size effect occurs. For the (0001) orientation, a sudden rapid increase in displacement occurs during indentation tests owing to twinning. This sudden rapid increase in displacement causes a rapid decrease in the hardness. Electron backscatter diffraction was performed around the impressions to measure the geometrically necessary (GN) dislocation density. The GN dislocation density increases with decreasing penetration depth for the (0001) and (1120) orientations. This trend corresponds to strain gradient theory. The reason for the indentation size effect in Ti is the increase in the GN dislocation density. For the (0001) orientation, the indentation size effect also can be attributed to twinning. Considering both our previous study and this study, the experimental results correspond to strain gradient theory in many cases.
format	article
author	Shota HASUNUMA Hirohisa MIYAZAKI Takeshi OGAWA
author_facet	Shota HASUNUMA Hirohisa MIYAZAKI Takeshi OGAWA
author_sort	Shota HASUNUMA
title	Investigation of the mechanism of the indentation size effect for titanium
title_short	Investigation of the mechanism of the indentation size effect for titanium
title_full	Investigation of the mechanism of the indentation size effect for titanium
title_fullStr	Investigation of the mechanism of the indentation size effect for titanium
title_full_unstemmed	Investigation of the mechanism of the indentation size effect for titanium
title_sort	investigation of the mechanism of the indentation size effect for titanium
publisher	The Japan Society of Mechanical Engineers
publishDate	2019
url	https://doaj.org/article/ab341fee769049b3ba5e76ccae986288
work_keys_str_mv	AT shotahasunuma investigationofthemechanismoftheindentationsizeeffectfortitanium AT hirohisamiyazaki investigationofthemechanismoftheindentationsizeeffectfortitanium AT takeshiogawa investigationofthemechanismoftheindentationsizeeffectfortitanium
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Investigation of the mechanism of the indentation size effect for titanium

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