"abnormal transient creep" in fine-grained Al-5356 alloy observed at low strain rates by high-resolution strain measurement

Jun Jie Shen, Kenichi Ikeda, Satoshi Hata, Hideharu Nakashima

Research output: Contribution to journalArticle

Abstract

Transient creep at very low strain rates (less than 10-10s -1) is still unclear. The traditional uniaxial creep testing is less useful due to unsatisfied resolution strain ∼(10-6). To study transient creep behavior at such low strain rates, a high-resolution strain measurement using the helicoid spring specimen technique was employed in a fine-grained Al-5356 alloy at temperatures ranging from 0.47 Tm to 0.74Tm (Tm: melting point). To clarify transient creep mechanism at such low strain rates, transmission electron microscopy (TEM) was used in microstructure observation of crept specimens. The abnormal transient creep, high temperature strengthening at T>Tp(Tp: the phase transformation temperature, 0.58Tm) or intermediate temperature softening at 0.4Tm<T≤Tp and double-normal type (creep curves including double work-hardening stages) at T=Tp, were firstly observed. The substructure observation in a crept specimen at T=0.58Tm and É=1*10-4 shows pile-up dislocations including many small jogs with equal interval, and dislocations emitted from grain boundaries. The β-Al3Mg2 phase dissolves under the condition of testing temperatures higher than 523 K, which causes solid-solution quantity of Mg atoms to increase. Therefore, the "abnormal transient creep" may be related to the difference of solid solution strengthening caused by phase change during the creep tests.

Original languageEnglish
Pages (from-to)1209-1214
Number of pages6
JournalTransactions of Nonferrous Metals Society of China (English Edition)
Volume23
Issue number5
DOIs
Publication statusPublished - May 1 2013

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strain measurement
Strain measurement
strain rate
creep
Strain rate
Creep
high resolution
solid solutions
creep tests
work hardening
piles
substructures
softening
melting points
phase transformations
temperature
grain boundaries
intervals
transmission electron microscopy
microstructure

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Geotechnical Engineering and Engineering Geology
  • Metals and Alloys
  • Materials Chemistry

Cite this

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title = "{"}abnormal transient creep{"} in fine-grained Al-5356 alloy observed at low strain rates by high-resolution strain measurement",
abstract = "Transient creep at very low strain rates (less than 10-10s -1) is still unclear. The traditional uniaxial creep testing is less useful due to unsatisfied resolution strain ∼(10-6). To study transient creep behavior at such low strain rates, a high-resolution strain measurement using the helicoid spring specimen technique was employed in a fine-grained Al-5356 alloy at temperatures ranging from 0.47 Tm to 0.74Tm (Tm: melting point). To clarify transient creep mechanism at such low strain rates, transmission electron microscopy (TEM) was used in microstructure observation of crept specimens. The abnormal transient creep, high temperature strengthening at T>Tp(Tp: the phase transformation temperature, 0.58Tm) or intermediate temperature softening at 0.4Tm<T≤Tp and double-normal type (creep curves including double work-hardening stages) at T=Tp, were firstly observed. The substructure observation in a crept specimen at T=0.58Tm and {\'E}=1*10-4 shows pile-up dislocations including many small jogs with equal interval, and dislocations emitted from grain boundaries. The β-Al3Mg2 phase dissolves under the condition of testing temperatures higher than 523 K, which causes solid-solution quantity of Mg atoms to increase. Therefore, the {"}abnormal transient creep{"} may be related to the difference of solid solution strengthening caused by phase change during the creep tests.",
author = "Shen, {Jun Jie} and Kenichi Ikeda and Satoshi Hata and Hideharu Nakashima",
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AU - Shen, Jun Jie

AU - Ikeda, Kenichi

AU - Hata, Satoshi

AU - Nakashima, Hideharu

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N2 - Transient creep at very low strain rates (less than 10-10s -1) is still unclear. The traditional uniaxial creep testing is less useful due to unsatisfied resolution strain ∼(10-6). To study transient creep behavior at such low strain rates, a high-resolution strain measurement using the helicoid spring specimen technique was employed in a fine-grained Al-5356 alloy at temperatures ranging from 0.47 Tm to 0.74Tm (Tm: melting point). To clarify transient creep mechanism at such low strain rates, transmission electron microscopy (TEM) was used in microstructure observation of crept specimens. The abnormal transient creep, high temperature strengthening at T>Tp(Tp: the phase transformation temperature, 0.58Tm) or intermediate temperature softening at 0.4Tm<T≤Tp and double-normal type (creep curves including double work-hardening stages) at T=Tp, were firstly observed. The substructure observation in a crept specimen at T=0.58Tm and É=1*10-4 shows pile-up dislocations including many small jogs with equal interval, and dislocations emitted from grain boundaries. The β-Al3Mg2 phase dissolves under the condition of testing temperatures higher than 523 K, which causes solid-solution quantity of Mg atoms to increase. Therefore, the "abnormal transient creep" may be related to the difference of solid solution strengthening caused by phase change during the creep tests.

AB - Transient creep at very low strain rates (less than 10-10s -1) is still unclear. The traditional uniaxial creep testing is less useful due to unsatisfied resolution strain ∼(10-6). To study transient creep behavior at such low strain rates, a high-resolution strain measurement using the helicoid spring specimen technique was employed in a fine-grained Al-5356 alloy at temperatures ranging from 0.47 Tm to 0.74Tm (Tm: melting point). To clarify transient creep mechanism at such low strain rates, transmission electron microscopy (TEM) was used in microstructure observation of crept specimens. The abnormal transient creep, high temperature strengthening at T>Tp(Tp: the phase transformation temperature, 0.58Tm) or intermediate temperature softening at 0.4Tm<T≤Tp and double-normal type (creep curves including double work-hardening stages) at T=Tp, were firstly observed. The substructure observation in a crept specimen at T=0.58Tm and É=1*10-4 shows pile-up dislocations including many small jogs with equal interval, and dislocations emitted from grain boundaries. The β-Al3Mg2 phase dissolves under the condition of testing temperatures higher than 523 K, which causes solid-solution quantity of Mg atoms to increase. Therefore, the "abnormal transient creep" may be related to the difference of solid solution strengthening caused by phase change during the creep tests.

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