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Title: Plastic Deformation Characteristics Of AZ31 Magnesium Alloy Sheets At Elevated Temperature

Abstract

Using lightweight materials is the emerging need in order to reduce the vehicle's energy consumption and pollutant emissions. Being a lightweight material, magnesium alloys are increasingly employed in the fabrication of automotive and electronic parts. Presently, magnesium alloys used in automotive and electronic parts are mainly processed by die casting. The die casting technology allows the manufacturing of parts with complex geometry. However, the mechanical properties of these parts often do not meet the requirements concerning the mechanical properties (e.g. endurance strength and ductility). A promising alternative can be forming process. The parts manufactured by forming could have fine-grained structure without porosity and improved mechanical properties such as endurance strength and ductility. Because magnesium alloy has low formability resulted form its small slip system at room temperature it is usually formed at elevated temperature. Due to a rapid increase of usage of magnesium sheets in automotive and electronic industry it is necessary to assure database for sheet metal formability and plastic yielding properties in order to optimize its usage. Especially, plastic yielding criterion is a critical property to predict plastic deformation of sheet metal parts in optimizing process using CAE simulation. Von-Mises yield criterion generally well predicts plastic deformation ofmore » steel sheets and Hill'1979 yield criterion predicts plastic deformation of aluminum sheets. In this study, using biaxial tensile test machine yield loci of AZ31 magnesium alloy sheet were obtained at elevated temperature. The yield loci ensured experimentally were compared with the theoretical predictions based on the Von-Mises, Hill, Logan-Hosford, and Barlat model.« less

Authors:
;  [1];  [2];  [3];  [4]
  1. Graduate School, Kyungpook National University, Deagu 702-701 (Korea, Republic of)
  2. Department of Materials Technology, Korea Institute of Machinery and Materials, Changwon 641-831 (Korea, Republic of)
  3. Digital Production Processing and Forming Team, Korea Institute of Industrial Technology, Incheon 406-800 (Korea, Republic of)
  4. Department of Mechanical Engineering, Kyoungpook National University, Deagu 702-701 (Korea, Republic of)
Publication Date:
OSTI Identifier:
21057353
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 908; Journal Issue: 1; Conference: NUMIFORM '07: 9. international conference on numerical methods in industrial forming processes, Porto (Portugal), 17-21 Jun 2007; Other Information: DOI: 10.1063/1.2740984; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM; CASTING; COMPUTERIZED SIMULATION; DUCTILITY; MAGNESIUM; MAGNESIUM ALLOYS; MANUFACTURING; NUMERICAL ANALYSIS; OPTIMIZATION; PLASTICITY; POROSITY; SHEETS; SLIP; STEELS; TEMPERATURE DEPENDENCE; TESTING; YIELD STRENGTH

Citation Formats

Park, Jingee, Lee, Jongshin, You, Bongsun, Choi, Seogou, and Kim, Youngsuk. Plastic Deformation Characteristics Of AZ31 Magnesium Alloy Sheets At Elevated Temperature. United States: N. p., 2007. Web. doi:10.1063/1.2740984.
Park, Jingee, Lee, Jongshin, You, Bongsun, Choi, Seogou, & Kim, Youngsuk. Plastic Deformation Characteristics Of AZ31 Magnesium Alloy Sheets At Elevated Temperature. United States. doi:10.1063/1.2740984.
Park, Jingee, Lee, Jongshin, You, Bongsun, Choi, Seogou, and Kim, Youngsuk. Thu . "Plastic Deformation Characteristics Of AZ31 Magnesium Alloy Sheets At Elevated Temperature". United States. doi:10.1063/1.2740984.
@article{osti_21057353,
title = {Plastic Deformation Characteristics Of AZ31 Magnesium Alloy Sheets At Elevated Temperature},
author = {Park, Jingee and Lee, Jongshin and You, Bongsun and Choi, Seogou and Kim, Youngsuk},
abstractNote = {Using lightweight materials is the emerging need in order to reduce the vehicle's energy consumption and pollutant emissions. Being a lightweight material, magnesium alloys are increasingly employed in the fabrication of automotive and electronic parts. Presently, magnesium alloys used in automotive and electronic parts are mainly processed by die casting. The die casting technology allows the manufacturing of parts with complex geometry. However, the mechanical properties of these parts often do not meet the requirements concerning the mechanical properties (e.g. endurance strength and ductility). A promising alternative can be forming process. The parts manufactured by forming could have fine-grained structure without porosity and improved mechanical properties such as endurance strength and ductility. Because magnesium alloy has low formability resulted form its small slip system at room temperature it is usually formed at elevated temperature. Due to a rapid increase of usage of magnesium sheets in automotive and electronic industry it is necessary to assure database for sheet metal formability and plastic yielding properties in order to optimize its usage. Especially, plastic yielding criterion is a critical property to predict plastic deformation of sheet metal parts in optimizing process using CAE simulation. Von-Mises yield criterion generally well predicts plastic deformation of steel sheets and Hill'1979 yield criterion predicts plastic deformation of aluminum sheets. In this study, using biaxial tensile test machine yield loci of AZ31 magnesium alloy sheet were obtained at elevated temperature. The yield loci ensured experimentally were compared with the theoretical predictions based on the Von-Mises, Hill, Logan-Hosford, and Barlat model.},
doi = {10.1063/1.2740984},
journal = {AIP Conference Proceedings},
number = 1,
volume = 908,
place = {United States},
year = {Thu May 17 00:00:00 EDT 2007},
month = {Thu May 17 00:00:00 EDT 2007}
}
  • Cited by 3
  • Both equal channel angular pressing and friction stir processing have the ability to refine the grain size of twin roll cast AZ31 magnesium and potentially improve its superplastic properties. This work used isochronal and isothermal heat treatments to investigate the microstructural stability of twin roll cast, equal channel angular pressed and friction stir processed AZ31 magnesium. For both heat treatment conditions, it was found that the twin roll casted and equal channel angular pressed materials were more stable than the friction stir processed material. Calculations of the grain growth kinetics showed that severe plastic deformation processing decreased the activation energymore » for grain boundary motion with the equal channel angular pressed material having the greatest Q value of the severely plastically deformed materials and that increasing the tool travel speed of the friction stir processed material improved microstructural stability. The Hollomon-Jaffe parameter was found to be an accurate means of identifying the annealing conditions that will result in substantial grain growth and loss of potential superplastic properties in the severely plastically deformed materials. In addition, Humphreys’s model of cellular microstructural stability accurately predicted the relative microstructural stability of the severely plastically deformed materials and with some modification, closely predicted the maximum grain size ratio achieved by the severely plastically deformed materials.« less
  • In this paper, a constitutive framework based on a crystalline plasticity model is employed to simulate the plastic deformation of AZ31 magnesium alloy, which posses the hexagonal close packed (HCP) crystal structure. Dislocation slip and mechanical twinning are taken into account in the model. The successive integration method is used to determine the active slip systems, and the contribution of twinning to the grain reorientation is treated by the PTR method. The FE model is introduced into ABAQUS/Explicit through a user material subroutine (VUMAT). Three deformation processes of AZ31 magnesium alloy, including tension, compression and a stamping process, are simulatedmore » with the present method. The simulation results are compared with experiment and those presented in the literature.« less
  • This paper applies a multi-step inverse approach to predict the forming of AZ31 magnesium alloy sheets. An in-house finite element code named “INAPH”, which implements the inverse approach formulation by Guo et al. (Int. J. Numer. Methods Eng., 30, 1385-1401), has been used for the forming analysis. This inverse approach uses the deformation theory of plasticity and assumes that the deformation is independent of the loading history. Failure during forming is predicted by a stress-based criterion or a forming limit diagram-based criterion. The INAPH predictions have been compared with experimental results of Takuda et al (Journal of Materials Processing Technology,more » 89-90:135-140) and incremental analysis using ABAQUS. The multi-step inverse analysis has been shown to very quickly and fairly accurately predict stress, plastic strain, thickness distributions and failure locations on deeply drawn parts made of AZ31 magnesium alloy. The capability of INAPH to predict the formability of magnesium alloys has also been demonstrated at various temperatures. As magnesium alloys possess very limited formability at room temperature, and their formability becomes better at higher temperatures (> 100oC), the inverse analysis constitutes an efficient and valuable tool to predict forming of magnesium alloy parts as a function of temperature. In addition, other processing and design parameters such as the initial dimensions, final desired shape, blank holder forces, and friction can be quickly adjusted to assess the forming feasibility.« less
  • In the present study, the stamping process for manufacturing cell phone cases with magnesium alloy AZ31 sheets was studied using both the experimental approach and the finite element analysis. In order to determine the proper forming temperature and set up a fracture criterion, tensile tests and forming limit tests were first conducted to obtain the mechanical behaviors of AZ31 sheets at various elevated temperatures. The mechanical properties of Z31 sheets obtained from the experiments were then adopted in the finite element analysis to investigate the effects of the process parameters on the formability of the stamping process of cell phonemore » cases. The finite element simulation results revealed that both the fracture and wrinkle defects could not be eliminated at the same time by adjusting blank-holder force or blank size. A drawbead design was then performed using the finite element simulations to determine the size and the location of drawbead required to suppress the wrinkle defect. An optimum stamping process, including die geometry, forming temperature, and blank dimension, was then determined for manufacturing the cell phone cases. The finite element analysis was validated by the good agreement between the simulation results and the experimental data. It confirms that the cell phone cases can be produced with magnesium alloy AZ31 sheet by the stamping process at elevated temperatures.« less