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Mechanical responses, texture evolution, and yield loci of extruded AZ31 magnesium alloy under various loading conditions : = Experiment and modeling.

紀錄類型:	書目-語言資料,手稿 : Monograph/item
正題名/作者:	Mechanical responses, texture evolution, and yield loci of extruded AZ31 magnesium alloy under various loading conditions :/
其他題名:	Experiment and modeling.
作者:	Kabirian, Farhoud.
面頁冊數:	1 online resource (144 pages)
附註:	Source: Dissertations Abstracts International, Volume: 77-01, Section: B.
Contained By:	Dissertations Abstracts International77-01B.
標題:	Mechanical engineering. -
電子資源:	click for full text (PQDT)
ISBN:	9781321817782

Mechanical responses, texture evolution, and yield loci of extruded AZ31 magnesium alloy under various loading conditions : = Experiment and modeling.
Kabirian, Farhoud.

Mechanical responses, texture evolution, and yield loci of extruded AZ31 magnesium alloy under various loading conditions :Experiment and modeling. - 1 online resource (144 pages)

Source: Dissertations Abstracts International, Volume: 77-01, Section: B.

Thesis (Ph.D.)--University of Maryland, Baltimore County, 2015.

Includes bibliographical references

Mechanical responses and texture evolution of extruded AZ31 Mg are measured under uniaxial (tension-compression) and multiaxial (free-end torsion) loadings. Compression loading is carried out in three different directions at temperature and strain rate ranges of 77-423 K and 10-4 -3000 s -1, respectively. Texture evolution at different intermediate strains reveals that crystal reorientation is exhausted at smaller strains with increase in strain rate while increase in temperature retards twinning. In addition to the well-known tension-compression yield asymmetry, a strong anisotropy in strain hardening response is observed. Strain hardening during the compression experiment is intensified with decreasing and increasing temperature and strain rate, respectively. This complex behavior is explained through understanding the roles of deformation mechanisms using the Visco-Plastic Self Consistent (VPSC) model. In order to calibrate the VPSC model's constants as accurate as possible, a vast number of mechanical responses including stress-strain curves in tension, compression in three directions, and free-end torsion, texture evolution at different strains, lateral strains of compression samples, twin volume fraction, and axial strain during the torsion experiment. Modeling results show that depending on the number of measurements used for calibration, roles of different mechanisms in plastic deformation change significantly. In addition, a precise definition of yield is established for the extruded AZ31magnesium alloy after it is subjected to different loading conditions (uniaxial to multiaxial) at four different plastic strains. The yield response is measured in ?-? space. Several yield criteria are studied to predict yield response of extruded AZ31. This study proposes an asymmetrical fourth-order polynomial yield function. Material constants in this model can be directly calculated using mechanical measurements. Convexity of the proposed model is discussed, and domains of constants where convexity holds are determined. Effects of grain refinement induced by Equal Channel Angular Pressing, ECAP, on mechanical responses and texture evolution are investigated. Yield strength in compression increases after ECAP, however, strain-hardening rate drops with number of ECAP passes while failure strain increases. Texture measurements reveal the higher propensity to twinning in the extruded material compared with ECAPed magnesium. Calculated Schmid factor maps are utilized to connect the observed mechanical responses to the texture.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9781321817782Subjects--Topical Terms:

557493
Mechanical engineering.
Subjects--Index Terms:

Crystal plasticityIndex Terms--Genre/Form:

554714
Electronic books.

Mechanical responses, texture evolution, and yield loci of extruded AZ31 magnesium alloy under various loading conditions : = Experiment and modeling.
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245 1 0 $a Mechanical responses, texture evolution, and yield loci of extruded AZ31 magnesium alloy under various loading conditions : $b Experiment and modeling.
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500 $a Source: Dissertations Abstracts International, Volume: 77-01, Section: B.
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502 $a Thesis (Ph.D.)--University of Maryland, Baltimore County, 2015.
504 $a Includes bibliographical references
520 $a Mechanical responses and texture evolution of extruded AZ31 Mg are measured under uniaxial (tension-compression) and multiaxial (free-end torsion) loadings. Compression loading is carried out in three different directions at temperature and strain rate ranges of 77-423 K and 10-4 -3000 s -1, respectively. Texture evolution at different intermediate strains reveals that crystal reorientation is exhausted at smaller strains with increase in strain rate while increase in temperature retards twinning. In addition to the well-known tension-compression yield asymmetry, a strong anisotropy in strain hardening response is observed. Strain hardening during the compression experiment is intensified with decreasing and increasing temperature and strain rate, respectively. This complex behavior is explained through understanding the roles of deformation mechanisms using the Visco-Plastic Self Consistent (VPSC) model. In order to calibrate the VPSC model's constants as accurate as possible, a vast number of mechanical responses including stress-strain curves in tension, compression in three directions, and free-end torsion, texture evolution at different strains, lateral strains of compression samples, twin volume fraction, and axial strain during the torsion experiment. Modeling results show that depending on the number of measurements used for calibration, roles of different mechanisms in plastic deformation change significantly. In addition, a precise definition of yield is established for the extruded AZ31magnesium alloy after it is subjected to different loading conditions (uniaxial to multiaxial) at four different plastic strains. The yield response is measured in ?-? space. Several yield criteria are studied to predict yield response of extruded AZ31. This study proposes an asymmetrical fourth-order polynomial yield function. Material constants in this model can be directly calculated using mechanical measurements. Convexity of the proposed model is discussed, and domains of constants where convexity holds are determined. Effects of grain refinement induced by Equal Channel Angular Pressing, ECAP, on mechanical responses and texture evolution are investigated. Yield strength in compression increases after ECAP, however, strain-hardening rate drops with number of ECAP passes while failure strain increases. Texture measurements reveal the higher propensity to twinning in the extruded material compared with ECAPed magnesium. Calculated Schmid factor maps are utilized to connect the observed mechanical responses to the texture.
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653 $a Crystal plasticity
653 $a Deformation mechanisms
653 $a Magnesium
653 $a Twinning
653 $a Yield surface
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