Effect of confined rolling on structure-property relationships of Mg-Al alloys.

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Krishnan, P. (2021). Effect of confined rolling on structure-property relationships of Mg-Al alloys. Unc Charlotte Electronic Theses And Dissertations.
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Abstract

High performance, light weight alloys are need-of-the particularly in the defense, automotive and aerospace sectors. Magnesium is a prime candidate since it is the lightest structural metal having a mass density of 1.74g/cm3 and is the sixth most abundant element in the Earth’s crust. But, as a metal with a Hexagonal close packed (HCP) crystal structure, it exhibits poor formability, yield asymmetry, edge cracking in rolling, and low ductility at room temperature. Activation of non-basal slip planes, suppression of twinning, and promotion of recrystallization mechanisms leading to texture randomization have been a few key strategies incorporated during alloy design to achieve better properties. In this study, the effect of thermo-mechanical processing i.e., confined rolling on three Mg-Al alloys namely AZ31B, Mg-6%Al and Mg-9%Al was analyzed. Extensive microstructural analysis using advanced electron microscopy techniques revealed the occurrence of either partial (in case of Mg-9%Al) or complete dynamic recrystallization which in turn refined the grain size, improved both strength and ductility under compression and randomized texture. Correlation of rolling temperature, strain rate, %Al content with texture, twinning, recrystallization kinetics, deformation mechanisms, precipitation kinetics and morphology have shed light on creating the best processing route for each of these alloys to achieve optimal microstructure and improved compressive mechanical behavior.

Details
Author

Krishnan, Pavitra

Title

Effect of confined rolling on structure-property relationships of Mg-Al alloys.

Physical Description

1 online resource (197 pages) : PDF

Date

2021

Degree Granting Institution

University of North Carolina at Charlotte

Abstract

High performance, light weight alloys are need-of-the particularly in the defense, automotive and aerospace sectors. Magnesium is a prime candidate since it is the lightest structural metal having a mass density of 1.74g/cm3 and is the sixth most abundant element in the Earth’s crust. But, as a metal with a Hexagonal close packed (HCP) crystal structure, it exhibits poor formability, yield asymmetry, edge cracking in rolling, and low ductility at room temperature. Activation of non-basal slip planes, suppression of twinning, and promotion of recrystallization mechanisms leading to texture randomization have been a few key strategies incorporated during alloy design to achieve better properties. In this study, the effect of thermo-mechanical processing i.e., confined rolling on three Mg-Al alloys namely AZ31B, Mg-6%Al and Mg-9%Al was analyzed. Extensive microstructural analysis using advanced electron microscopy techniques revealed the occurrence of either partial (in case of Mg-9%Al) or complete dynamic recrystallization which in turn refined the grain size, improved both strength and ductility under compression and randomized texture. Correlation of rolling temperature, strain rate, %Al content with texture, twinning, recrystallization kinetics, deformation mechanisms, precipitation kinetics and morphology have shed light on creating the best processing route for each of these alloys to achieve optimal microstructure and improved compressive mechanical behavior.

Genre

doctoral dissertations

Subjects--Topics

Materials science

Degree

Ph.D.

Keywords

Dynamic Recrystallization
Ebsd
Magnesium Alloys
Severe Plastic Deformation
Tem
Texture Randomization

Subject Area

Mechanical Engineering

Advisor(s)

Wei, Qiuming

Committee Members

Cherukuri, Harish
Kecskes, Laszlo
Chen, Youxing
Chen, Don

Degree Note

Thesis (Ph.D.)--University of North Carolina at Charlotte, 2021.

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Identifier

Krishnan_uncc_0694D_12941

Permalink

http://hdl.handle.net/20.500.13093/etd:2756