• Title/Summary/Keyword: Magnesium sheet

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Experiments for Forming Limit Diagram and Springback Characteristics of AZ31B Magnesium Alloy Sheet at Elevated Temperature (AZ31B 마그네슘 합금판재의 온간 성형한계도 및 스프링백 특성 시험)

  • Choi, C.S.;Lee, H.S.;Kim, H.J.;Lee, K.T.;Kim, H.Y.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.05a
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    • pp.289-293
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    • 2007
  • The effect of temperature on the forming limit diagram was investigated for AZ31B magnesium alloy sheet through the limit dome height test in the range from room temperature to $300^{\circ}C$. The formability of AZ31B sheet was improved significantly according to the increasing temperature. Also we studied the springback characteristics through the 2D draw bending test with different blank holding forces at elevated temperatures. Springback quantity was considerably reduced as temperature went up. The blank holding force in the range used, however, had little influence on springback. Experimental results obtained in this study may provide a material database for AZ31B sheet.

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Experiments for Forming Limit Diagram and Springback Characteristics of AZ31B Magnesium Alloy Sheet at Elevated Temperature (AZ31B 마그네슘 합금판재의 온간 성형한계도 및 스프링백 특성 시험)

  • Kim, H.Y.;Choi, S.C.;Lee, H.S.;Kim, H.J.;Lee, K.T.
    • Transactions of Materials Processing
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    • v.16 no.5 s.95
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    • pp.364-369
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    • 2007
  • The effect of temperature on the forming limit diagram was investigated for AZ31B magnesium alloy sheet through the limit dome height test in the range from room temperature to $300^{\circ}C$. The formability of AZ31B sheet was improved significantly according to the increasing temperature. Also we studied the springback characteristics through the 2D draw bending test with different blank holding forces at elevated temperatures. Springback quantity was considerably reduced as temperature went up. The blank holding force in the range used, however, had little influence on springback. Experimental results obtained in this study may provide a material database for AZ31B sheet.

Measurement of Springback of AZ31B Mg Alloy Sheet in OSU Draw/bend Test (AZ31B 마그네슘 합금 판재의 OSU 드로우벤드 시험과 스프링 백 측정)

  • Choi, J.G.;Choi, S.C.;Lee, M.G.;Kim, H.Y.
    • Transactions of Materials Processing
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    • v.16 no.6
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    • pp.447-451
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    • 2007
  • The springback characteristics of AZ31B magnesium alloy sheet was investigated in OSU draw/bend test Springback is the elastically-driven change of shape of a part after forming and it should be estimated and controlled to manufacture more precise products in sheet forming. Magnesium alloy sheets have unique mechanical properties such as high in-plane anisotropy/asymmetry of yield stress and hardening response. So, there will be a difference in the prediction of springback with symmetric mechanical properties for magnesium alloy sheets. In this work, the Strip draw/bend tests were conducted with various conditions - die radius, sheet thickness and controlled tensile force and the tendency of springback angle was observed from the tests.

Finite-Element Analysis of Warm Square Cup Deep Drawing Process of Magnesium Alloy AZ31 Sheet (마그네슘 합금 AZ31 판재의 온간 사각컵 디프드로잉 공정의 유한요소 해석)

  • Kim H.K.;Lee W.R.;Hong S.K.;Kim J.D.;Han B.K.
    • Transactions of Materials Processing
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    • v.15 no.3 s.84
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    • pp.232-240
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    • 2006
  • Magnesium alloys are expected to be widely used fur the parts of structural and electronic appliances due to their lightweight and EMI shielding characteristics. While the die casting has been mainly used to manufacture the parts from the magnesium alloys, the press forming is considered as an alternative to the die casting for saving the manufacturing cost and improving the structural strength of the magnesium alloy parts. However, the magnesium alloy has low formability at room temperature and therefore, in many cases, forming at elevated temperatures is necessary to obtain the required material flow without failure. In the present study, square cup deep drawing tests using the magnesium alloy AZ31 sheet were experimentally conducted at various elevated temperatures as well as room temperature, and the corresponding finite-element simulations, which calculated the damage evolution based on the Oyane's criterion, were conducted using the stress-strain relations from the tensile tests at various temperatures. The formability predictability by the finite-element analysis was investigated by comparing the predicted damage distributions over the deformed AZ31 sheet at elevated temperatures with the corresponding experimental deformations with failures.

Finite-Element Analysis of Formability in Warm Square Cup Deep Drawing of Magnesium Alloy AZ31 Sheet (마그네슘 합금 AZ31 판재의 온간 사각컵 딥드로잉 성형성의 유한요소 해석)

  • Kim Heung-Kyu;Lee Wi Ro;Hong Seok Kwan;Han Byoung Kee;Kim Jong Deok
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.10a
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    • pp.122-125
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    • 2005
  • Magnesium alloys are expected to be widely used for the parts of structural and electronic applications due to their lightweight and EMI shielding characteristics. While the die casting has been mainly used to manufacture the parts from the magnesium alloys, the press forming is considered as an alternative to the die casting for saving the manufacturing cost and improving the structural strength of the magnesium alloy parts. However, the magnesium alloy has low formability at room temperature and therefore, in many cases, forming at elevated temperatures is necessary to obtain the required material flow without failure. In the present study, square cup deep drawing tests using the magnesium alloy AZ31 sheet were experimentally conducted at various elevated temperatures as well as room temperature, and the corresponding finite-element simulations, which calculated the damage evolution based on the Oyane's criterion, were conducted using the stress-strain relations from the tensile tests at various temperatures. The formability predictability by the finite-element analysis was investigated by comparing the predicted damage distributions over the deformed AZ31 sheet at elevated temperatures with the corresponding experimental deformations with failures.

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Development of magnesium tube manufacturing technology with strip cast and warm rolled AZ31 sheet. (마그네슘 압연판재를 이용한 용접 튜브 제조 기술 개발)

  • Lee, Mok-Young;Han, Soo-Sik;Chang, Woong-Seong;Lee, Heung-Gyu
    • Proceedings of the KWS Conference
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    • 2010.05a
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    • pp.96-96
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    • 2010
  • Magnesium alloy is being used for structural material since it has high specific strength. Tubular shape was effective way for enhanced structural design. To manufacture the tube, it is necessary to weld the butted joint of both tubular formed sides. But the magnesium alloy was hardly welded with conventional welding processes. The laser welding was effective way to joint magnesium alloys because it had high weld strength and productivity compare with other welding processes. In this study, magnesium alloy sheets was formed at elevated temperature to tubular shape and welded with laser. Consequently, the magnesium alloy tube was making successful with warm forming and laser welding and bicycle frame was making with it.

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Electrode Life Test of Resistance Spot Welding on Mg Alloy Using Dome Type Electrode (돔형 전극을 사용한 마그네슘 합금 저항 점용접의 전극 수명 평가)

  • Choi, Dong-Soon;Hwang, In-Sung;Kim, Dong-Cheol;Kang, Moon-Jin
    • Journal of Welding and Joining
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    • v.31 no.6
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    • pp.27-31
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    • 2013
  • Magnesium alloy is used on parts of aircraft and electronic equipment because of the highest specific strength among the common metal materials. Recently, studies about appling magnesium alloy sheet to automotive bodies are on the increase rapidly. For application to automotive bodies, researches about characteristics of resistance spot welding of magnesium alloy sheet are essential. Magnesium alloy has low boiling point, so getting sound bead shape is difficult when appling varies welding processes. Resistance spot welding is also particular about setting optimum welding conditions because of spatter generation, pores and cracks occurrence in nugget. And life of electrodes is very short because of alloying with copper that main material of electrodes. This requires frequent dressing and replacement of electrodes and decrease in productivity of resistance spot welding on magnesium alloy. Therefore in this study, for effective analysis of changes in tensile shear load and nugget size during electrode life test, evaluate detail characteristics of resistance spot welding on magnesium alloy sheet using dome type electrode.

Finite element analysis considering heat transfer in sheet metal forming of AZ31 (AZ31 합금 성형에서의 열전달을 고려한 유한요소해석)

  • Kim M. C.;Lee Y. S.;Kwon Y. N.;Lee J. H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.05a
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    • pp.73-77
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    • 2005
  • In this work, the influences of tool temperature on the formability of AZ31 sheet material in warm deep drawing processes of square cup were investigated. Deep drawing tests under different tool temperatures for magnesium alloy sheet at elevated temperature $250^{\circ}C$, where AZ31 sheet shows a good formability, and FE analyses were carried out. The successfully formed part without any defects was obtained when temperature of tool was over $100^{\circ}C$ while the fracture was occurred at the corner of the square cup below $100^{\circ}C$. It is shown that lower temperature of tool than that of magnesium sheet causes the temperature drop of the material by heat transfer and thus Interrupts the dynamic recrystallization of it. Therefore, in order to obtain successful part of magnesium alloys, it is necessary that the tool temperature is limited to the same or slightly lower temperature than sheet material.

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The Temperature Dependent C-H/V Constitutive Modeling for Magnesium Alloy Sheet (마그네슘 판재를 위한 온도 의존형 C-H/V 구성 모델에 관한 연구)

  • Park, J.H.;Lee, J.K.;Kim, H.Y.
    • Transactions of Materials Processing
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    • v.21 no.4
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    • pp.221-227
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    • 2012
  • The automotive and electronic industries have seriously considered the use of magnesium alloys because of their excellent properties such as strength to weight ratio, EMI shielding capability, etc. However, it is difficult to form magnesium alloys at room temperature because of the mechanical deformation related to twinning. Hence, magnesium alloys are normally formed at elevated temperatures. In this study, a temperature dependent constitutive model, the C-H/V model, for the magnesium alloy AZ31B sheet is proposed. A hardening law based on nonlinear kinematic and H/V(Hollomon/Voce) hardening model is used to properly characterize the Bauschinger effect and the stabilization of the flow stress. Material parameters were determined from a series of uni-axial cyclic experiments(C-T-C) with the temperature ranging between 150 and $250^{\circ}C$. The developed models are fit to experimental data and a comparison is made.

Design and Analysis of vehicle Hood using Magnesium Alloy Sheets (마그네슘 합금 판재를 이용한 차량용 후드의 설계 및 해석)

  • Shin H. W.;Yoo H. J.;Yeo D. H.;Shin K. Y.;Koh Y. S.;Choi S. W.;Lee S. W.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.10a
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    • pp.220-226
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    • 2005
  • To achieve the weight reduction of a vehicle, Magnesium alloys are widely used in automobile parts because of its lightweight characteristics. Magnesium alloys also have advantages in recycling, stiffness, NVH , heat protection. But Magnesium alloy parts are mainly manufactured by diecasting processes, their productivity was not so high compared to by sheet metal working. We are developing vehicle hood using magnesium sheets. In this study we designed magnesium alloy hood which have equivalent mechanical characteristics to steel hood. Using finite element method we decided thickness of magnesium sheets under some design requirements and we changed the shape of hood inner panel and hinge reinforcements. Outer and inner panel thickness was 1.3mm, 1.5mm respectively. Panel dentibility analysis was performed to conform the new magnesium design by nonlinear FEM package. Formability and hemming of Magnesium sheets are the subjects for further study because they have poor stretchability compared to steel sheets.

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