Microstructure evolution and creep behavior of near-¡ Ti alloy produced by thermomechanical processing

Haruki Masuyama, Kei Shimagami, Yoshiaki Toda, Tetsuya Matsunaga, Tsutomu Ito, Masayuki Shimojo, Yoko Yamabe-Mitarai

Research output: Contribution to journalArticle

Abstract

A microstructure evolution based on the processing and heat-treatment conditions was investigated for Ti-13Al-2Nb-2Zr (at%) alloy, which has a promising oxidation resistance. Three processing temperatures, 900°C and 1000°C in the ¡+¢ phase field, and 1080°C in the ¢ phase field, and two rolling reduction ratios, 93% and 67%, were selected as the processing conditions. In the samples processed and heat-treated in the ¡+¢ phase field, an almost fully equiaxed structure, i.e., the equiaxed or ellipsoid ¡ phase surrounded by the ¢ phase, was formed through furnace cooling, and a bi-modal structure was formed using air cooling. The morphology of the ¡ phase in the near fully equiaxed and lamellar structure depends on the rolling reduction ratio; in other words, the equiaxed and ellipsoid ¡ phases are formed at rolling reduction ratios of 93% and 67%, respectively. The volume fraction of the equiaxed ¡ phase in the bi-modal structure is processed at 900°C, which is higher than that of the bi-modal structure processed at 1000°C despite the same heat-treatment temperature applied. This is because the induced strain when processed at 1000°C is smaller than that when processed at 900°C. By contrast, in the samples processed in the ¢ phase field and heat-treated in either the ¡+¢ or ¢ phase field, a lamellar structure is formed. The creep behavior of the bi-modal structure obtained upon processing at 900°C and 1000°C for up to a 93% rolling reduction ratio was investigated. The creep life of the sample processed at 1000°C was two-times longer than the sample processed at 900°C. This is because a smaller volume fraction of the equiaxed ¡ phase in the sample processed at 1000°C than that of the sample processed at 900°C.

Original languageEnglish
Pages (from-to)2336-2345
Number of pages10
JournalMaterials Transactions
Volume60
Issue number11
DOIs
Publication statusPublished - 2019 Jan 1

Fingerprint

Creep
microstructure
Microstructure
Lamellar structures
Processing
Volume fraction
Heat treatment
ellipsoids
Cooling
Oxidation resistance
heat treatment
air cooling
heat
Furnaces
oxidation resistance
Temperature
furnaces
Air
cooling
temperature

Keywords

  • Bi-modal microstructure
  • Creep test
  • Deformation mechanism
  • Equiaxed ¡
  • Thermomechanical processing
  • Titanium alloy
  • ¡+¢ phase

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

Microstructure evolution and creep behavior of near-¡ Ti alloy produced by thermomechanical processing. / Masuyama, Haruki; Shimagami, Kei; Toda, Yoshiaki; Matsunaga, Tetsuya; Ito, Tsutomu; Shimojo, Masayuki; Yamabe-Mitarai, Yoko.

In: Materials Transactions, Vol. 60, No. 11, 01.01.2019, p. 2336-2345.

Research output: Contribution to journalArticle

Masuyama, Haruki ; Shimagami, Kei ; Toda, Yoshiaki ; Matsunaga, Tetsuya ; Ito, Tsutomu ; Shimojo, Masayuki ; Yamabe-Mitarai, Yoko. / Microstructure evolution and creep behavior of near-¡ Ti alloy produced by thermomechanical processing. In: Materials Transactions. 2019 ; Vol. 60, No. 11. pp. 2336-2345.
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abstract = "A microstructure evolution based on the processing and heat-treatment conditions was investigated for Ti-13Al-2Nb-2Zr (at{\%}) alloy, which has a promising oxidation resistance. Three processing temperatures, 900°C and 1000°C in the ¡+¢ phase field, and 1080°C in the ¢ phase field, and two rolling reduction ratios, 93{\%} and 67{\%}, were selected as the processing conditions. In the samples processed and heat-treated in the ¡+¢ phase field, an almost fully equiaxed structure, i.e., the equiaxed or ellipsoid ¡ phase surrounded by the ¢ phase, was formed through furnace cooling, and a bi-modal structure was formed using air cooling. The morphology of the ¡ phase in the near fully equiaxed and lamellar structure depends on the rolling reduction ratio; in other words, the equiaxed and ellipsoid ¡ phases are formed at rolling reduction ratios of 93{\%} and 67{\%}, respectively. The volume fraction of the equiaxed ¡ phase in the bi-modal structure is processed at 900°C, which is higher than that of the bi-modal structure processed at 1000°C despite the same heat-treatment temperature applied. This is because the induced strain when processed at 1000°C is smaller than that when processed at 900°C. By contrast, in the samples processed in the ¢ phase field and heat-treated in either the ¡+¢ or ¢ phase field, a lamellar structure is formed. The creep behavior of the bi-modal structure obtained upon processing at 900°C and 1000°C for up to a 93{\%} rolling reduction ratio was investigated. The creep life of the sample processed at 1000°C was two-times longer than the sample processed at 900°C. This is because a smaller volume fraction of the equiaxed ¡ phase in the sample processed at 1000°C than that of the sample processed at 900°C.",
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AU - Toda, Yoshiaki

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AU - Ito, Tsutomu

AU - Shimojo, Masayuki

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N2 - A microstructure evolution based on the processing and heat-treatment conditions was investigated for Ti-13Al-2Nb-2Zr (at%) alloy, which has a promising oxidation resistance. Three processing temperatures, 900°C and 1000°C in the ¡+¢ phase field, and 1080°C in the ¢ phase field, and two rolling reduction ratios, 93% and 67%, were selected as the processing conditions. In the samples processed and heat-treated in the ¡+¢ phase field, an almost fully equiaxed structure, i.e., the equiaxed or ellipsoid ¡ phase surrounded by the ¢ phase, was formed through furnace cooling, and a bi-modal structure was formed using air cooling. The morphology of the ¡ phase in the near fully equiaxed and lamellar structure depends on the rolling reduction ratio; in other words, the equiaxed and ellipsoid ¡ phases are formed at rolling reduction ratios of 93% and 67%, respectively. The volume fraction of the equiaxed ¡ phase in the bi-modal structure is processed at 900°C, which is higher than that of the bi-modal structure processed at 1000°C despite the same heat-treatment temperature applied. This is because the induced strain when processed at 1000°C is smaller than that when processed at 900°C. By contrast, in the samples processed in the ¢ phase field and heat-treated in either the ¡+¢ or ¢ phase field, a lamellar structure is formed. The creep behavior of the bi-modal structure obtained upon processing at 900°C and 1000°C for up to a 93% rolling reduction ratio was investigated. The creep life of the sample processed at 1000°C was two-times longer than the sample processed at 900°C. This is because a smaller volume fraction of the equiaxed ¡ phase in the sample processed at 1000°C than that of the sample processed at 900°C.

AB - A microstructure evolution based on the processing and heat-treatment conditions was investigated for Ti-13Al-2Nb-2Zr (at%) alloy, which has a promising oxidation resistance. Three processing temperatures, 900°C and 1000°C in the ¡+¢ phase field, and 1080°C in the ¢ phase field, and two rolling reduction ratios, 93% and 67%, were selected as the processing conditions. In the samples processed and heat-treated in the ¡+¢ phase field, an almost fully equiaxed structure, i.e., the equiaxed or ellipsoid ¡ phase surrounded by the ¢ phase, was formed through furnace cooling, and a bi-modal structure was formed using air cooling. The morphology of the ¡ phase in the near fully equiaxed and lamellar structure depends on the rolling reduction ratio; in other words, the equiaxed and ellipsoid ¡ phases are formed at rolling reduction ratios of 93% and 67%, respectively. The volume fraction of the equiaxed ¡ phase in the bi-modal structure is processed at 900°C, which is higher than that of the bi-modal structure processed at 1000°C despite the same heat-treatment temperature applied. This is because the induced strain when processed at 1000°C is smaller than that when processed at 900°C. By contrast, in the samples processed in the ¢ phase field and heat-treated in either the ¡+¢ or ¢ phase field, a lamellar structure is formed. The creep behavior of the bi-modal structure obtained upon processing at 900°C and 1000°C for up to a 93% rolling reduction ratio was investigated. The creep life of the sample processed at 1000°C was two-times longer than the sample processed at 900°C. This is because a smaller volume fraction of the equiaxed ¡ phase in the sample processed at 1000°C than that of the sample processed at 900°C.

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KW - Titanium alloy

KW - ¡+¢ phase

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