Overcoming the strength-ductility trade-off by the combination of static recrystallization and low-temperature heat-treatment in Co-Cr-W-Ni alloy for stent application

Ueki, Kosuke; Yanagihara, Soh; Ueda, Kyosuke; Nakai, Masaaki; Nakano, Takayoshi; Narushima, Takayuki

doi:https://doi.org/10.1016/j.msea.2019.138400

Overcoming the strength-ductility trade-off by the combination of static recrystallization and low-temperature heat-treatment in Co-Cr-W-Ni alloy for stent application

Ueki, Kosuke; Yanagihara, Soh; Ueda, Kyosuke et al.

Materials Science and Engineering A, 2019, 766, 138400

Number of Access:530（2025-08-21 04:36 Counts）

Identifier to cite or link to this item: https://hdl.handle.net/11094/89814

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Title	Overcoming the strength-ductility trade-off by the combination of static recrystallization and low-temperature heat-treatment in Co-Cr-W-Ni alloy for stent application
Creator	NRID 1000010845928 1000010845928 CreatorName Ueki, Kosuke
	CreatorName Yanagihara, Soh
	NRID 1000040507901 1000040507901 CreatorName Ueda, Kyosuke
	NRID 1000020431603 1000020431603 CreatorName Nakai, Masaaki
	NRID 1000030243182 1000030243182 ORCID 0000-0001-8052-1698 0000-0001-8052-1698 researchmap permalink read0013987 read0013987 Scopus Author ID 7403896013 7403896013 CreatorName Nakano, Takayoshi
	NRID 1000020198394 1000020198394 CreatorName Narushima, Takayuki
Subject	Co-Cr-W-Ni alloy
	Mechanical properties
	Plastic deformation
	Static recrystallization
Description	Ueki K., Yanagihara S., Ueda K., et al. Overcoming the strength-ductility trade-off by the combination of static recrystallization and low-temperature heat-treatment in Co-Cr-W-Ni alloy for stent application. Materials Science and Engineering A, 766, 138400. https://doi.org/10.1016/j.msea.2019.138400.
Abstract	A process combining swaging, static recrystallization, and heat treatment at 873 K (low-temperature heat-treatment, LTHT) was developed for achieving both high ultimate strength and high ductility in Co-20Cr-15W-10Ni (mass%, CCWN) alloy for stent application. The alloys swaged to a sectional area reduction rate of 58.3% were annealed at 1373–1473 K for 30–300 s. Under annealing at 1373 K for 300 s, a fine grain structure with an average grain size of ~6 μm formed, while under annealing at 1473 K, a structure with an average grain size of 12 μm formed after 120 s. In the alloys annealed at 1373–1448 K, the formation of η-phase precipitates (M6X-M12X type, M: metallic elements, X: C and/or N) was observed, while no precipitates were observed in the alloys annealed at 1473 K. The improvement in ultimate strength by grain refinement was confirmed. Alloys annealed at 1473 K showed higher ductility compared to those annealed at 1373–1448 K even if the grain size was similar. It is considered that the η-phase precipitates deteriorated the ductility of the annealed alloys. LTHT suppressed the strain-induced martensitic γ-to-ε transformation to improve the ductility of the fine-grained as well as coarse-grained alloys. Thus, regardless of the grain size, it is newly evidenced that LTHT effectively improves ductility in CCWN alloy. By combining high-temperature short-time annealing and LTHT, both the ultimate strength and ductility of Co-20Cr-15W-10Ni (mass%) alloy improved, and it was possible to provide properties suitable for next-generation balloon-expandable stents with Co-20Cr-15W-10Ni (mass%) alloy.
Publisher	Elsevier
Source Title	Materials Science and Engineering A
Volume (Issue)	766
Page	138400
Date of Issued	2019-10-24
Language	English
Handle URL	https://hdl.handle.net/11094/89814
PISSN	09215093
NCID	AA10720420
Relation.isIdenticalTo	DOI (Publisher Version) https://doi.org/10.1016/j.msea.2019.138400
Access Rights	open access
CopyRight	This article is licensed under a Creative Commons Attribution 4.0 International License.
oaire:version	Version of Record
Category	学術雑誌論文 Journal Article

Resource Type	journal article
Local Type	Journal Article
DCMI Type	Text
DCTERMS.bibliographicCitation	Materials Science and Engineering A. 2019, 766, p. 138400
DC.title	Overcoming the strength-ductility trade-off by the combination of static recrystallization and low-temperature heat-treatment in Co-Cr-W-Ni alloy for stent application
DC.creator	Ueki, Kosuke
	Yanagihara, Soh
	Ueda, Kyosuke
	Nakai, Masaaki
	Nakano, Takayoshi
	Narushima, Takayuki
DC.publisher	Elsevier
DC.language' scheme='DCTERMS.RFC1766	English
DC.type' scheme='DCTERMS.DCMIType	Text
DCTERMS.issued' scheme='DCTERMS.W3CDTF	2019-10-24
DC.identifier	https://doi.org/10.1016/j.msea.2019.138400
DC.subject	Co-Cr-W-Ni alloy
	Mechanical properties
	Plastic deformation
	Static recrystallization
DC.description	Ueki K., Yanagihara S., Ueda K., et al. Overcoming the strength-ductility trade-off by the combination of static recrystallization and low-temperature heat-treatment in Co-Cr-W-Ni alloy for stent application. Materials Science and Engineering A, 766, 138400. https://doi.org/10.1016/j.msea.2019.138400.
DCTERMS.abstract	A process combining swaging, static recrystallization, and heat treatment at 873 K (low-temperature heat-treatment, LTHT) was developed for achieving both high ultimate strength and high ductility in Co-20Cr-15W-10Ni (mass%, CCWN) alloy for stent application. The alloys swaged to a sectional area reduction rate of 58.3% were annealed at 1373–1473 K for 30–300 s. Under annealing at 1373 K for 300 s, a fine grain structure with an average grain size of ~6 μm formed, while under annealing at 1473 K, a structure with an average grain size of 12 μm formed after 120 s. In the alloys annealed at 1373–1448 K, the formation of η-phase precipitates (M6X-M12X type, M: metallic elements, X: C and/or N) was observed, while no precipitates were observed in the alloys annealed at 1473 K. The improvement in ultimate strength by grain refinement was confirmed. Alloys annealed at 1473 K showed higher ductility compared to those annealed at 1373–1448 K even if the grain size was similar. It is considered that the η-phase precipitates deteriorated the ductility of the annealed alloys. LTHT suppressed the strain-induced martensitic γ-to-ε transformation to improve the ductility of the fine-grained as well as coarse-grained alloys. Thus, regardless of the grain size, it is newly evidenced that LTHT effectively improves ductility in CCWN alloy. By combining high-temperature short-time annealing and LTHT, both the ultimate strength and ductility of Co-20Cr-15W-10Ni (mass%) alloy improved, and it was possible to provide properties suitable for next-generation balloon-expandable stents with Co-20Cr-15W-10Ni (mass%) alloy.
DC.rights	This article is licensed under a Creative Commons Attribution 4.0 International License.
DC.format	89814
citation_title	Overcoming the strength-ductility trade-off by the combination of static recrystallization and low-temperature heat-treatment in Co-Cr-W-Ni alloy for stent application
citation_author	Ueki, Kosuke
	Yanagihara, Soh
	Ueda, Kyosuke
	Nakai, Masaaki
	Nakano, Takayoshi
	Narushima, Takayuki
citation_publisher	Elsevier
citation_language	English
citation_date	2019-10-24
citation_journal_title	Materials Science and Engineering A
citation_volume	766
citation_firstpage	138400
citation_doi	https://doi.org/10.1016/j.msea.2019.138400
citation_public_url	https://hdl.handle.net/11094/89814

Overcoming the strength-ductility trade-off by the combination of static recrystallization and low-temperature heat-treatment in Co-Cr-W-Ni alloy for stent application

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