Elucidating deformation behavior of cementite and κ-carbide during friction stir welding of Fe-0.1C-xAl (x = 0.05 and 5 mass%) steels below A₁

Chen, Junqi; Miura, Takuya; Ushioda, Kohsaku; Fujii, Hidetoshi

doi:https://doi.org/10.1016/j.matchar.2025.115205

Elucidating deformation behavior of cementite and κ-carbide during friction stir welding of Fe-0.1C-xAl (x = 0.05 and 5 mass%) steels below A₁

Chen, Junqi; Miura, Takuya; Ushioda, Kohsaku et al.

Materials Characterization, 2025, 225, 115205

アクセス数:10件（2025-07-27 07:16 集計）

固定URL: https://hdl.handle.net/11094/102210

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タイトル	Elucidating deformation behavior of cementite and κ-carbide during friction stir welding of Fe-0.1C-xAl (x = 0.05 and 5 mass%) steels below A₁
著者	著者名 Chen, Junqi
	NRID 1000060781466 1000060781466 ORCID 0000-0002-8991-5412 0000-0002-8991-5412 researchmap permalink miuratky miuratky Scopus Author ID 55162450300 55162450300 著者名 Miura, Takuya
	著者名 Ushioda, Kohsaku
	NRID 1000000247230 1000000247230 ORCID 0000-0002-5023-3844 0000-0002-5023-3844 researchmap permalink read0051741 read0051741 Scopus Author ID 7403071460 7403071460 著者名 Fujii, Hidetoshi
キーワード等	Cementite
	Fe-0.1C-xAl ferrite steel
	Friction stir welding
	κ-carbide deformation
内容	Chen J., Miura T., Ushioda K., et al. Elucidating deformation behavior of cementite and κ-carbide during friction stir welding of Fe-0.1C-xAl (x = 0.05 and 5 mass%) steels below A1. Materials Characterization 225, 115205 (2025); https://doi.org/10.1016/j.matchar.2025.115205.
抄録	The deformation behavior of cementite and κ-carbide of Fe-0.1C-0.05Al and Fe-0.1C-5Al (mass%) steels at below A₁ friction stir welding (FSW) was investigated. Quantitative nano-hardness measurements revealed that cementite exhibited high hardness (13.0 GPa) and strong resistance to deformation (0.22 μN/nm²), whereas κ-carbide had a lower hardness of 6.9 GPa and resistance force of 0.083 μN/nm² for the first time. During FSW under an axial load of 40 kN at a rotation rate of 80 rpm (peak temperatures ∼700 °C, below A₁), few dislocations were introduced into the structure of cementite, which is hard and brittle and is prone to fragmentation owing to the accumulation of dislocations at the ferrite/cementite interface. In contrast, κ-carbides, being softer, exhibited considerable plastic deformation and were presumed to be sheared by the high-density dislocations introduced under the same conditions. The shear processing plausibly triggers dynamic redistribution of the C atoms, where dislocations penetrate through the κ-carbides, disrupting Fe[sbnd]C bonding. These phenomena enable the transfer of C atoms from the κ-carbides to the matrix and subsequent precipitation of fine cementite along part of the grain boundaries during the cooling stage after FSW. Furthermore, the introduced dislocations remain within the shearable κ-carbides and may serve as dislocation sources in subsequent deformation processes, thereby enhancing the ductility of the steels. The present study is the first to clearly reveal the internal dislocation features of carbides and analyze the distinct deformation behavior of different carbides during FSW below A₁.
出版者	Elsevier Inc.
収録物名	Materials Characterization
巻(号)	225
ページ	115205
刊行年月	2025-05-26
言語	英語
ハンドルURL	https://hdl.handle.net/11094/102210
PISSN	10445803
関連情報 (isIdenticalTo)	DOI (出版社版) https://doi.org/10.1016/j.matchar.2025.115205
アクセス権	open access
権利情報	This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
出版タイプ	Version of Record
カテゴリ	学術雑誌論文 Journal Article

資源タイプ	学術雑誌論文
ローカル資源タイプ	学術雑誌論文
DCMI資源タイプ	text
DCTERMS.bibliographicCitation	Materials Characterization. 2025, 225, p. 115205
DC.title	Elucidating deformation behavior of cementite and κ-carbide during friction stir welding of Fe-0.1C-xAl (x = 0.05 and 5 mass%) steels below A₁
DC.creator	Chen, Junqi
	Miura, Takuya
	Ushioda, Kohsaku
	Fujii, Hidetoshi
DC.publisher	Elsevier Inc.
DC.language' scheme='DCTERMS.RFC1766	英語
DC.type' scheme='DCTERMS.DCMIType	text
DCTERMS.issued' scheme='DCTERMS.W3CDTF	2025-05-26
DC.identifier	https://doi.org/10.1016/j.matchar.2025.115205
DC.subject	Cementite
	Fe-0.1C-xAl ferrite steel
	Friction stir welding
	κ-carbide deformation
DC.description	Chen J., Miura T., Ushioda K., et al. Elucidating deformation behavior of cementite and κ-carbide during friction stir welding of Fe-0.1C-xAl (x = 0.05 and 5 mass%) steels below A1. Materials Characterization 225, 115205 (2025); https://doi.org/10.1016/j.matchar.2025.115205.
DCTERMS.abstract	The deformation behavior of cementite and κ-carbide of Fe-0.1C-0.05Al and Fe-0.1C-5Al (mass%) steels at below A₁ friction stir welding (FSW) was investigated. Quantitative nano-hardness measurements revealed that cementite exhibited high hardness (13.0 GPa) and strong resistance to deformation (0.22 μN/nm²), whereas κ-carbide had a lower hardness of 6.9 GPa and resistance force of 0.083 μN/nm² for the first time. During FSW under an axial load of 40 kN at a rotation rate of 80 rpm (peak temperatures ∼700 °C, below A₁), few dislocations were introduced into the structure of cementite, which is hard and brittle and is prone to fragmentation owing to the accumulation of dislocations at the ferrite/cementite interface. In contrast, κ-carbides, being softer, exhibited considerable plastic deformation and were presumed to be sheared by the high-density dislocations introduced under the same conditions. The shear processing plausibly triggers dynamic redistribution of the C atoms, where dislocations penetrate through the κ-carbides, disrupting Fe[sbnd]C bonding. These phenomena enable the transfer of C atoms from the κ-carbides to the matrix and subsequent precipitation of fine cementite along part of the grain boundaries during the cooling stage after FSW. Furthermore, the introduced dislocations remain within the shearable κ-carbides and may serve as dislocation sources in subsequent deformation processes, thereby enhancing the ductility of the steels. The present study is the first to clearly reveal the internal dislocation features of carbides and analyze the distinct deformation behavior of different carbides during FSW below A₁.
DC.rights	This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
DC.format	102210
citation_title	Elucidating deformation behavior of cementite and κ-carbide during friction stir welding of Fe-0.1C-xAl (x = 0.05 and 5 mass%) steels below A₁
citation_author	Chen, Junqi
	Miura, Takuya
	Ushioda, Kohsaku
	Fujii, Hidetoshi
citation_publisher	Elsevier Inc.
citation_language	英語
citation_date	2025-05-26
citation_journal_title	Materials Characterization
citation_volume	225
citation_firstpage	115205
citation_doi	https://doi.org/10.1016/j.matchar.2025.115205
citation_public_url	https://hdl.handle.net/11094/102210

Elucidating deformation behavior of cementite and κ-carbide during friction stir welding of Fe-0.1C-xAl (x = 0.05 and 5 mass%) steels below A₁

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