Heat treatment of AZ91D Mg-Al-Zn alloy

Microstructural evolution and dynamic response

Dung D. Luong, Vasanth Chakravarthy Shunmugasamy, James Cox, Nikhil Gupta, Pradeep K. Rohatgi

Research output: Contribution to journalArticle

Abstract

Magnesium alloys are attracting great interest from the automotive industry because of the potential for weight reduction. An AZ91D cast alloy was studied in the current work to understand the effect of heat treatment on the microstructure and dynamic compressive properties. The selected heat treatments include solution treatment (T4) and solution treatment followed by aging (T6). The as-cast alloy microstructure consists of intermetallic β-phase (Mg 17Al12) precipitates surrounded by α + β lamellar eutectic in α-Mg solid solution. The AZ91D-T4 specimens showed small β-phase precipitates along the grain boundaries and regions of eutectic mixture. The T6 heat treatment causes the β-phase platelets in the α + β eutectic to grow and develop into β-precipitates. The difference in the phase morphology reflects into the mechanical properties. The Vickers hardness of the T6 heat-treated specimens was 3.6% higher than the as-cast alloy. The compressive yield strengths of T4 and T6 treated specimens were 1.3% and 43.1% higher than those of as-cast specimens. The high strain rate compression testing resulted in increase in the strength with strain rate for the T4 and T6 specimens. A maximum increase of 42% was observed in T6 specimen tested at a strain rate of 4,000/s in comparison to the quasi-static compression. Under high strain rate compression testing, the T6 heat-treated specimens showed failure of the β-precipitates resulting in increased energy absorption in comparison to the quasi-static compression.

Original languageEnglish (US)
Pages (from-to)312-321
Number of pages10
JournalJOM
Volume66
Issue number2
DOIs
StatePublished - Feb 2014

Fingerprint

Microstructural evolution
Dynamic response
Strain rate
Precipitates
Heat treatment
Eutectics
Compression testing
Microstructure
Vickers hardness
Energy absorption
Platelets
Magnesium alloys
Automotive industry
Intermetallics
Yield stress
Solid solutions
Grain boundaries
Aging of materials
Mechanical properties
Mg-Al-Zn-Mn-Si-Cu alloy

ASJC Scopus subject areas

  • Engineering(all)
  • Materials Science(all)

Cite this

Heat treatment of AZ91D Mg-Al-Zn alloy : Microstructural evolution and dynamic response. / Luong, Dung D.; Shunmugasamy, Vasanth Chakravarthy; Cox, James; Gupta, Nikhil; Rohatgi, Pradeep K.

In: JOM, Vol. 66, No. 2, 02.2014, p. 312-321.

Research output: Contribution to journalArticle

Luong, Dung D. ; Shunmugasamy, Vasanth Chakravarthy ; Cox, James ; Gupta, Nikhil ; Rohatgi, Pradeep K. / Heat treatment of AZ91D Mg-Al-Zn alloy : Microstructural evolution and dynamic response. In: JOM. 2014 ; Vol. 66, No. 2. pp. 312-321.
@article{aefab5a8ad0d43a2b5dd6a9439426838,
title = "Heat treatment of AZ91D Mg-Al-Zn alloy: Microstructural evolution and dynamic response",
abstract = "Magnesium alloys are attracting great interest from the automotive industry because of the potential for weight reduction. An AZ91D cast alloy was studied in the current work to understand the effect of heat treatment on the microstructure and dynamic compressive properties. The selected heat treatments include solution treatment (T4) and solution treatment followed by aging (T6). The as-cast alloy microstructure consists of intermetallic β-phase (Mg 17Al12) precipitates surrounded by α + β lamellar eutectic in α-Mg solid solution. The AZ91D-T4 specimens showed small β-phase precipitates along the grain boundaries and regions of eutectic mixture. The T6 heat treatment causes the β-phase platelets in the α + β eutectic to grow and develop into β-precipitates. The difference in the phase morphology reflects into the mechanical properties. The Vickers hardness of the T6 heat-treated specimens was 3.6{\%} higher than the as-cast alloy. The compressive yield strengths of T4 and T6 treated specimens were 1.3{\%} and 43.1{\%} higher than those of as-cast specimens. The high strain rate compression testing resulted in increase in the strength with strain rate for the T4 and T6 specimens. A maximum increase of 42{\%} was observed in T6 specimen tested at a strain rate of 4,000/s in comparison to the quasi-static compression. Under high strain rate compression testing, the T6 heat-treated specimens showed failure of the β-precipitates resulting in increased energy absorption in comparison to the quasi-static compression.",
author = "Luong, {Dung D.} and Shunmugasamy, {Vasanth Chakravarthy} and James Cox and Nikhil Gupta and Rohatgi, {Pradeep K.}",
year = "2014",
month = "2",
doi = "10.1007/s11837-013-0800-3",
language = "English (US)",
volume = "66",
pages = "312--321",
journal = "JOM",
issn = "1047-4838",
publisher = "Minerals, Metals and Materials Society",
number = "2",

}

TY - JOUR

T1 - Heat treatment of AZ91D Mg-Al-Zn alloy

T2 - Microstructural evolution and dynamic response

AU - Luong, Dung D.

AU - Shunmugasamy, Vasanth Chakravarthy

AU - Cox, James

AU - Gupta, Nikhil

AU - Rohatgi, Pradeep K.

PY - 2014/2

Y1 - 2014/2

N2 - Magnesium alloys are attracting great interest from the automotive industry because of the potential for weight reduction. An AZ91D cast alloy was studied in the current work to understand the effect of heat treatment on the microstructure and dynamic compressive properties. The selected heat treatments include solution treatment (T4) and solution treatment followed by aging (T6). The as-cast alloy microstructure consists of intermetallic β-phase (Mg 17Al12) precipitates surrounded by α + β lamellar eutectic in α-Mg solid solution. The AZ91D-T4 specimens showed small β-phase precipitates along the grain boundaries and regions of eutectic mixture. The T6 heat treatment causes the β-phase platelets in the α + β eutectic to grow and develop into β-precipitates. The difference in the phase morphology reflects into the mechanical properties. The Vickers hardness of the T6 heat-treated specimens was 3.6% higher than the as-cast alloy. The compressive yield strengths of T4 and T6 treated specimens were 1.3% and 43.1% higher than those of as-cast specimens. The high strain rate compression testing resulted in increase in the strength with strain rate for the T4 and T6 specimens. A maximum increase of 42% was observed in T6 specimen tested at a strain rate of 4,000/s in comparison to the quasi-static compression. Under high strain rate compression testing, the T6 heat-treated specimens showed failure of the β-precipitates resulting in increased energy absorption in comparison to the quasi-static compression.

AB - Magnesium alloys are attracting great interest from the automotive industry because of the potential for weight reduction. An AZ91D cast alloy was studied in the current work to understand the effect of heat treatment on the microstructure and dynamic compressive properties. The selected heat treatments include solution treatment (T4) and solution treatment followed by aging (T6). The as-cast alloy microstructure consists of intermetallic β-phase (Mg 17Al12) precipitates surrounded by α + β lamellar eutectic in α-Mg solid solution. The AZ91D-T4 specimens showed small β-phase precipitates along the grain boundaries and regions of eutectic mixture. The T6 heat treatment causes the β-phase platelets in the α + β eutectic to grow and develop into β-precipitates. The difference in the phase morphology reflects into the mechanical properties. The Vickers hardness of the T6 heat-treated specimens was 3.6% higher than the as-cast alloy. The compressive yield strengths of T4 and T6 treated specimens were 1.3% and 43.1% higher than those of as-cast specimens. The high strain rate compression testing resulted in increase in the strength with strain rate for the T4 and T6 specimens. A maximum increase of 42% was observed in T6 specimen tested at a strain rate of 4,000/s in comparison to the quasi-static compression. Under high strain rate compression testing, the T6 heat-treated specimens showed failure of the β-precipitates resulting in increased energy absorption in comparison to the quasi-static compression.

UR - http://www.scopus.com/inward/record.url?scp=84893826030&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84893826030&partnerID=8YFLogxK

U2 - 10.1007/s11837-013-0800-3

DO - 10.1007/s11837-013-0800-3

M3 - Article

VL - 66

SP - 312

EP - 321

JO - JOM

JF - JOM

SN - 1047-4838

IS - 2

ER -