Annealing behavior of severely-deformed titanium Grade 4

G. S. Dyakonov, S. Mironov, N. Enikeev, R. Z. Valiev, S. L. Semiatin

Результат исследований: Научные публикации в периодических изданияхстатья

2 Цитирования (Scopus)

Выдержка

The static-annealing behavior and evolution of the microstructure-strength relationship of severely-deformed commercial-purity titanium Grade 4 over the temperature range of 50–850 °C (0.16–0.57 Tm, where Tm is the melting point) were established. The severely-deformed material was obtained via equal-channel angular pressing (ECAP) using the Conform (ECAP-C) technique at 200 °C to an effective accumulated true strain of 8.4. The resulting ultrafine structure was stable to 400 °C. The excellent thermal stability was concluded to be associated with a strain-aging effect, i.e., the enhanced diffusion of solutes within this temperature interval resulting in the formation of solute atmospheres at/near dislocations. At 450–500 °C, rapid growth of strain-free grains occurred, which eliminated the severely-deformed microstructure and promoted softening. This process was deduced to be controlled primarily by grain-boundary energy and therefore was interpreted primarily in terms of grain growth rather than discontinuous recrystallization expected in this temperature range. A further increase in annealing temperature to 600 °C led to normal grain growth. Analysis of the microstructure-strength relationship suggested a significant influence of mechanical twinning on yield strength of the fully-annealed material. At 600 °C and higher temperatures, dissolution of constituent iron-rich particles was observed. This promoted a partial α → β transformation at the temperatures noticeably below the typical beta-transus of pure titanium (~880 °C). This phenomenon resulted in the precipitation of nanoscale β particles which imparted substantial strengthening. Water quenching of the material annealed at 850 °C gave rise to a β → α′ martensitic transformation. The latter process was governed by exceptionally strong variant selection and thereby provided a nearly-ideal restoration of crystallographic orientations of parent α-grains.

Язык оригиналаанглийский
Страницы (с-по)89-101
Число страниц13
ЖурналMaterials Science and Engineering A
Том742
DOI
СостояниеОпубликовано - 10 янв 2019

Отпечаток

Titanium
grade
titanium
Annealing
annealing
Grain growth
Temperature
microstructure
Microstructure
temperature
solutes
mechanical twinning
Equal channel angular pressing
precipitation hardening
Twinning
Martensitic transformations
Strengthening (metal)
martensitic transformation
pressing
yield strength

Предметные области Scopus

  • Материаловедение (все)
  • Физика конденсатов
  • Сопротивление материалов
  • Общее машиностроение

Цитировать

Dyakonov, G. S. ; Mironov, S. ; Enikeev, N. ; Valiev, R. Z. ; Semiatin, S. L. / Annealing behavior of severely-deformed titanium Grade 4. В: Materials Science and Engineering A. 2019 ; Том 742. стр. 89-101.
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Annealing behavior of severely-deformed titanium Grade 4. / Dyakonov, G. S.; Mironov, S.; Enikeev, N.; Valiev, R. Z.; Semiatin, S. L.

В: Materials Science and Engineering A, Том 742, 10.01.2019, стр. 89-101.

Результат исследований: Научные публикации в периодических изданияхстатья

TY - JOUR

T1 - Annealing behavior of severely-deformed titanium Grade 4

AU - Dyakonov, G. S.

AU - Mironov, S.

AU - Enikeev, N.

AU - Valiev, R. Z.

AU - Semiatin, S. L.

PY - 2019/1/10

Y1 - 2019/1/10

N2 - The static-annealing behavior and evolution of the microstructure-strength relationship of severely-deformed commercial-purity titanium Grade 4 over the temperature range of 50–850 °C (0.16–0.57 Tm, where Tm is the melting point) were established. The severely-deformed material was obtained via equal-channel angular pressing (ECAP) using the Conform (ECAP-C) technique at 200 °C to an effective accumulated true strain of 8.4. The resulting ultrafine structure was stable to 400 °C. The excellent thermal stability was concluded to be associated with a strain-aging effect, i.e., the enhanced diffusion of solutes within this temperature interval resulting in the formation of solute atmospheres at/near dislocations. At 450–500 °C, rapid growth of strain-free grains occurred, which eliminated the severely-deformed microstructure and promoted softening. This process was deduced to be controlled primarily by grain-boundary energy and therefore was interpreted primarily in terms of grain growth rather than discontinuous recrystallization expected in this temperature range. A further increase in annealing temperature to 600 °C led to normal grain growth. Analysis of the microstructure-strength relationship suggested a significant influence of mechanical twinning on yield strength of the fully-annealed material. At 600 °C and higher temperatures, dissolution of constituent iron-rich particles was observed. This promoted a partial α → β transformation at the temperatures noticeably below the typical beta-transus of pure titanium (~880 °C). This phenomenon resulted in the precipitation of nanoscale β particles which imparted substantial strengthening. Water quenching of the material annealed at 850 °C gave rise to a β → α′ martensitic transformation. The latter process was governed by exceptionally strong variant selection and thereby provided a nearly-ideal restoration of crystallographic orientations of parent α-grains.

AB - The static-annealing behavior and evolution of the microstructure-strength relationship of severely-deformed commercial-purity titanium Grade 4 over the temperature range of 50–850 °C (0.16–0.57 Tm, where Tm is the melting point) were established. The severely-deformed material was obtained via equal-channel angular pressing (ECAP) using the Conform (ECAP-C) technique at 200 °C to an effective accumulated true strain of 8.4. The resulting ultrafine structure was stable to 400 °C. The excellent thermal stability was concluded to be associated with a strain-aging effect, i.e., the enhanced diffusion of solutes within this temperature interval resulting in the formation of solute atmospheres at/near dislocations. At 450–500 °C, rapid growth of strain-free grains occurred, which eliminated the severely-deformed microstructure and promoted softening. This process was deduced to be controlled primarily by grain-boundary energy and therefore was interpreted primarily in terms of grain growth rather than discontinuous recrystallization expected in this temperature range. A further increase in annealing temperature to 600 °C led to normal grain growth. Analysis of the microstructure-strength relationship suggested a significant influence of mechanical twinning on yield strength of the fully-annealed material. At 600 °C and higher temperatures, dissolution of constituent iron-rich particles was observed. This promoted a partial α → β transformation at the temperatures noticeably below the typical beta-transus of pure titanium (~880 °C). This phenomenon resulted in the precipitation of nanoscale β particles which imparted substantial strengthening. Water quenching of the material annealed at 850 °C gave rise to a β → α′ martensitic transformation. The latter process was governed by exceptionally strong variant selection and thereby provided a nearly-ideal restoration of crystallographic orientations of parent α-grains.

KW - Characterization

KW - Grains and interfaces

KW - Phase transformation

KW - Plasticity methods

KW - Titanium alloys

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DO - 10.1016/j.msea.2018.10.122

M3 - Article

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VL - 742

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EP - 101

JO - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing

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SN - 0921-5093

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