• Title/Summary/Keyword: Magnesium alloy

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FE Analysis on the Press Forging of AZ31 Magnesium Alloy (AZ31마그네슘합금의 프레스포징시 FE해석)

  • Hwang, Jong-Kwan;Kang, Dae-Min
    • Transactions of the Korean Society of Automotive Engineers
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    • v.14 no.1
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    • pp.86-91
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    • 2006
  • Magnesium alloys have been widely used for many structural components of automobiles and aircraft because of high specific strength and good castability in spite of hexgonal closed-packed crystal structure of pure magnesium. In this paper, FE analysis was executed about the formability of AZ3l magnesium alloy on press forging process. For this, the variation of sheet temperature, distribution of punch force and the effect of heat transfer and friction between punch and sheet on the forming characteristics during press forging of AZ31 has been analyzed by finite element analysis. In order to obtain temperature dependence of material characteristics, uniaxial tension tests at elevated temperature were done under temperature of $100^{\circ}C\~ 500^{\circ}C$.

Effect of Process Parameters on Laser Weldability of AZ31 Magnesium Alloy (AZ31 마그네슘합금의 레이저 용접성에 미치는 공정변수의 영향)

  • Kim, Jong-Do;Kil, Byung-Lea;Lee, Jung-han
    • Journal of Advanced Marine Engineering and Technology
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    • v.32 no.4
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    • pp.570-577
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    • 2008
  • Magnesium alloys are potentially useful as structural materials due to higher strength/weight ratio, heat conductivity and recyclability compared to other alloys. These alloys have attracted the interest of modern manufacturing such as the automobile, computer, communication and consumer electronic appliances industries. Hence welding techniques are required to be developed for these applications. Laser are known to be an excellent tool for them. This paper presents the laser weldability of AZ31 magnesium alloy with CW Nd:YAG laser. The low viscosity and surface tension of the melt pool make magnesium more difficult to weld than steel. As a result of this study, optimal process parameters could be obtained without weld defects. Also it was certain that cutting methods had influence on butt weldability.

Improvement on the Formability of Magnesium Alloy Sheet by Heating and Cooling Method (가열냉각법에 의한 마그네슘 합금의 판재 성형성 개선)

  • Kang, D.M.;Manabe, K.
    • Journal of Power System Engineering
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    • v.9 no.3
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    • pp.66-70
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    • 2005
  • Structural components for aerospace, electronics and automobile industry are the main applications for magnesium alloys due to their lightweight and high specific strength. The adoption of magnesium alloys in sheet forming processes is still limited, due to their low formability at room temperature caused by the hexagonal crystal structure. In this paper, the authors aim to improve the formability of AZ31 magnesium alloy. For this, experiment and finite element analysis on used warm deep drawing process with a local heating and cooling technique were done. Both die and blank holder were heated at various warm temperature while the punch was kept at room temperature by cooling water.

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Plastic Deformation Characteristic of AZ31 Magnesium alloy Sheet (AZ31 마그네슘 합금판재의 소성변형특성)

  • Park J. G.;Kim Y. S.;Kuwabara Toshihiko;You B. S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.05a
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    • pp.64-68
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    • 2005
  • In recent years, there has been a growth of the manufacture and application of magnesium products because of its small specific gravity as well as its relatively high strength. However, there are so many studies to assure good formability because magnesium sheet alloy is difficult to form. In this study, uniaxial tensile and biaxial tensile test of AZ31 magnesium sheet alloy with thickness of 1.2mm were performed at room temperature. Uniaxial tensile test were performed until $7\%$ of engineering strain. R-values and stress-strain curve were obtained. Biaxial tensile tests with cruciform specimen were performed until the breakdown of the specimen occurs. The yield loci are made by application of plastic work theory. The results are compared with the theoretical predictions based on the Hill and Logan-Hosford model. However, next study will be performed at warm-temperature because the specimens are broken under the $0.5\%$ of equivalent strain at biaxial tensile test.

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Electroplating on Magnesium Alloy in KF-Added Pyrophosphate Copper Bath (불화칼륨이 첨가된 피로인산구리 도금욕에서 마그네슘합금의 전기도금)

  • Lee, Jung Hoon;Kim, Yong Hwan;Jung, Uoo Chang;Chung, Won Sub
    • Korean Journal of Metals and Materials
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    • v.48 no.3
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    • pp.218-224
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    • 2010
  • Direct copper electroplating on Mg alloy AZ31B was carried out in a traditional pyrophosphate copper bath containing potassium fluoride. Electrochemical impedance spectroscopy and polarization methods were used to study the effects of added potassium fluoride on electrochemical behavior. The chemical state of magnesium alloy in the electroplating bath was analyzed by X-ray photoelectron spectroscopy. Adhesion of the copper electroplated layer was also tested. Due to the added potassium fluoride, a magnesium fluoride film was formed in the pyrophosphate copper bath. This fluoride film inhibits dissolution of Mg alloy and enables to electroplate copper directly on it. A dense copper layer was formed on the Mg alloy. Moreover, this copper layer has a good adhesion with Mg alloy substrate.

Synthesis of Zr-Ti Alloy Powder by Magnesium Reduction (마그네슘환원에 의한 지르코늄-티타늄 합금분말 합성)

  • Lee, Dong-Won;Park, Geun-Tae;Lim, Tae-Soo;Lee, Hye-Moon;Yu, Ji-Hun
    • Journal of Powder Materials
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    • v.18 no.4
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    • pp.359-364
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    • 2011
  • Zr-Ti alloy powders were successfully synthesized by magnesium thermal reduction of metal chlorides. The evaporated and mixed gasses of $ZrCl_4+TiCl_4$ were injected to liquid magnesium and the chloride components were reduced by magnesium leading to the formation of $MgCl_2$. The released Zr and Ti atoms were then condensed to particle forms inside the mixture of liquid magnesium and magnesium chloride, which could be dissolved fully in post process by 1~5% HCl solution at room temperature. By the fraction-control of individually injected $ZrCl_4$ and $TiCl_4$ gasses, the final compositions of produced alloy powders were changed in the ranges of Zr-0 wt.%~20 wt.%Ti and their purity and particle size were about 99.4% and the level of several micrometers, respectively.

The Weldability of Magnesium Alloys for Car Industry

  • Lee, Mok-Young;Chang, Woong-Seong;Yoon, Byung-Hyun
    • Proceedings of the KWS Conference
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    • 2005.06a
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    • pp.370-376
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    • 2005
  • Magnesium alloys are becoming important material for light weight car body, due to their low specific density but high specific strength. However they have a poor weldability, caused high oxidization tendency and low vapor temperature. In this study, the welding performance of magnesium alloys was investigated for automobile application. The materials were rolled magnesium alloy sheet contains Al and Zn such as AZ3l , AZ6l and AZ9l. Three types of welding process were studied, that were GTAW, Laser beam welding and FSW. To evaluate the weldability, we examined the appearance of welding bead. Also we checked bead shape and internal defects such as crack and porosity on cross section of welding bead. The mechanical property was measured for welded specimen by tensile test. For determination of the strength change by welding process, the hardness profile across the welding center was measured. For the results, the tensile properties of welded specimen were decreased obviously on all welding process. For the fusion welding process such as GTAW and laser beam welding, the surface of the welding bead was covered with oxidized magnesium dust but it was removed by simple cleaning work as wipe-out with tissue. Also under cut, that caused vaporization of base metal was occurred. for the friction stir welding, there was no oxidation, under-cut or internal defects. However it had poor weld performance, the reason was cleavage fracture occurred at plastic deformation zone. For welding of magnesium alloy, the laser beam welding process was recommended.

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