• 제목/요약/키워드: AZ31 alloy

검색결과 319건 처리시간 0.027초

압연조건에 따른 AZ31 마그네슘합금판재의 변형거동 및 미세조직 변화 (Rolling of AZ31 Alloy and Microstructure of Rolled Plates)

  • 하태권;정효태;성환진;박우진
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2006년도 춘계학술대회 논문집
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    • pp.63-66
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    • 2006
  • The effect of warm rolling under various conditions on the microstructure and mechanical property was investigated using an AZ31 Mg alloy sheet. Several processing parameters such as initial thickness, thickness reduction by a single pass rolling, rolling temperature, roll speed, and roll temperature were varied to elicit an optimum condition for the warm rolling process of AZ31 Mg alloy. Microstructure and mechanical properties were measured for specimens subjected to rolling experiments of various conditions. Warm rolling of 30% thickness reduction per pass was possible without any side-crack at temperatures as low as $200^{\circ}C$ under the roll speed of 30 m/min. The initial microstructure before rolling was the mixed one consisting of partially recrystallized and cast structures. Grain refinement was found to occur actively during the warm rolling, producing a very fine grain size of 7 mm after 50% reduction in single pass rolling at $200^{\circ}C$. Yield strength of 204MPa, tensile strength of 330MPa and uniform elongation of 32% have been obtained in warm rolled sheets.

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AZ31 마그네슘 합금의 플라즈마전해산화 피막 형성에 미치는 수산화 이온 및 규산 이온의 영향 (Effects of Hydroxide and Silicate ions on the Plasma Electrolytic Oxidation of AZ31 Mg Alloy)

  • 문성모;양철남;나상조
    • 한국표면공학회지
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    • 제47권4호
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    • pp.147-154
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    • 2014
  • Formation behavior of PEO (Plasma Electrolytic Oxidation) films on AZ31 Mg alloy was studied in aqueous solutions containing various concentrations of hydroxide ion ($OH^-$) and silicate ion ($SiO_3{^{2-}}$) by voltage-time curves, and corrosion resistance of the PEO film-covered specimen was investigated by immersion test in 0.5 M NaCl solution. From the analyses of the voltage-time curves, it is suggested that two different types of anions are essentially needed for the formation of PEO films on AZ31 Mg alloy: film formation agent and local film breakdown agent. $SiO_3{^{2-}}$ ion acts only as a film formation agent but $OH^-$ ion acts not only as a film formation agent but also film breakdown agent. The PEO films prepared on AZ31 Mg alloy in alkaline silicate solution showed very good corrosion resistance without any pitting or filiform corrosions up to 480 h of immersion in 0.5 M NaCl.

비크롬계 인산-과망간산 용액을 이용한 AZ31 마그네슘 합금의 산처리에 따른 화성 피막의 특성 평가 (Characteristics Evaluation of Conversion Coating of Acid Pickling AZ31 Magnesium Alloy by a Chromium-Free Phosphate-Permanganate Solution)

  • 김명환;곽삼탁;문명준
    • 한국표면공학회지
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    • 제43권2호
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    • pp.73-79
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    • 2010
  • A chromium-free conversion coating for AZ31 magnesium alloy has been obtained by using a permanganatephosphate solution, which has been developed with acid pickling. Examination have been carried out on the conversion coatings for morphology, composition and corrosion resistance. The morphology of the conversion-coated layer was observed using optical microscope and SEM. It was shown that the conversion coatings are relatively uniform and continuous, with thickness 1.8 to 2.7 ${\mu}m$. The chemical composition of conversion coating was mainly consisted of Mg, O, P, K, Al and Mn by EDS analysis. It was found that the corrosion resistance of the AZ31 magnesium alloy has been improved by the permanganate-phosphate conversion treatment from electrochemical polarization.

십자 형상 금형의 디프 드로잉에서 AZ31B 마그네슘 합금판재의 성형 한계 (Forming Limit of AZ31B Magnesium Alloy Sheet in the Deep Drawing with Cross Shaped Die)

  • 황상희;최선철;김헌영;김형종;홍석무;신용승;이근호
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2008년도 춘계학술대회 논문집
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    • pp.374-377
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    • 2008
  • Magnesium alloy sheets are usually formed at temperatures between $150^{\circ}C$and $300^{\circ}C$ because of their poor formability at room temperature. In the present study, the formability of AZ31B magnesium alloy sheets was investigated by the analytical and experimental approaches. First, tensile tests and the limit dome height test were carried out at elevated temperatures to get the mechanical properties and forming limit diagram, respectively. And then deep drawing of cross shaped die was tried to get the minimum corner radius and forming limit at specific temperature. Blank shape, punch velocity, minimum corner radius, fillet size, etc, were determined by finite element analysis physical try-outs. Especially, optimum punch and die temperature were suggested through the temperature-deformation analysis using Pam-stamp.

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Processing map을 이용한 AZ31 Mg합금의 미세조직예측 (Prediction of Microstructure evolutions during hot-working of AZ31 Mg alloy using Processing map)

  • 이병호;이종수
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2007년도 추계학술대회 논문집
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    • pp.31-34
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    • 2007
  • In this study, optimum processing condition of AZ31 Mg alloy was investigated utilizing processing map and constitutive equation considering microstructure evolution (dynamic recrystallization) during hot-working. A series of mechanical tests were conducted at various temperatures and strain rates to construct a processing map and to formulate the recrystallization kinetics and grain size relation. Dynamic recrystallization (DRX) was observed to occur revealing maximum intensity at a domain of $250^{\circ}C$ and 1/s. The effect of DRX kinetics on microstructure evolution was implemented in a commercial FEM code followed by remapping of the state variables. The volume fraction and grain size of deformed part were predicted using a modified FEM code and compared with those of actual hot forged one. A good agreement was observed between the experimental results and predicted ones.

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스캐너를 이용한 AZ31 극박판재와 AZ91D 다이캐스팅 프레임의 고속레이저용접 (Fast laser welding with scanner on the joint between AZ31 thin sheet and die-casted AZ91D frame for smart phone application)

  • 이목영;서민홍
    • 한국레이저가공학회지
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    • 제18권1호
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    • pp.1-6
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    • 2015
  • High welding speed and narrow weld seam are favorable for welding of magnesium alloy. Magnesium alloy is recommended for the smart frame because it has several advantages such as low density, high thermal conductivity, EMI shielding capability and good cast ability. This study is for the assembly welding of the magnesium smart frame with high productivity, good performance and low cost. The window for battery on AZ91D frame produced by die-casting was prepared by CNC machining. Corresponding AZ31 blank of 0.2mm thickness was prepared by die-blanking cut. All system set was fixed at the stationary bed but the laser beam was manipulated by scanner up-to 1,000mm/s speed. The weld joint between AZ31 sheet and AZ91D frame was welded by fiber laser on 850~1,000W output power. The joint showed penetration enough but some humping bead. The distortion by the weld heat was almost free because of the quick dissipation of the heat by small beam size and fast welding. Consequently, the thinner magnesium foil was assembled successfully to the magnesium frame of mobile phone.

AZ61 filler wire를 사용하여 Nd:YAG Laser 용접한 AZ31-H24합금의 미세조직과 기계적 특성 (Microstructure and mechanical properties of Nd:YAG Laser welded AZ31-H24 Magnesium alloy using AZ61 filler metal)

  • 류충선;이목영;방국수;장웅성
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 2007년 추계학술발표대회 개요집
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    • pp.322-324
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    • 2007
  • Nd:YAG laser welding of AZ31B-H24 magnesium alloy was carried out using AZ61 filler wire(Mg-6wt%Al-1wt%Zn). Microstructure and mechanical properties of welded joint were examined by optical microscopy, scanning electronic microscopy(SEM), energy dispersive spectroscopy(EDS), electron probe micro analyzer(EPMA) and victors hardness, tensile test at the room and elevated temperature. Test results indicate that the specimens welded with AZ61 filler wire have better tensile strength, elongation and victors hardness at room temperature than those of welded without filler wire. However tensile strength are similar but elongation are quite different at elevated temperature.

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AZ31 합금 판재의 변형모드에 따른 성형한계에 관한 연구 (Forming Limits Diagram of AZ31 Alloy Sheet with the Deformation Mode)

  • 정진호;이영선;권용남;이정환
    • 소성∙가공
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    • 제17권7호
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    • pp.473-480
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    • 2008
  • Sheet metal forming of Mg alloy is usually performed at elevated temperature because of the low formability at room temperature. Therefore, strain rates affected with the forming temperature and speed must be considered as important factor about formability. Effects of process parameters such as various temperatures and forming speeds were investigated in circular cup deep drawing. From the experimental results, it is known that LDR (Limit Drawing Ratio) increase as the strain rate increase. On the contrary, the FLD (Forming Limit Diagram) shows lower value as faster strain rate. Therefore, anisotropy values are investigated according to the temperature and strain rates at each forming temperature. R-values also represent higher value as faster strain rate. It is known that the formability can be different with the deformation mode on warm forming of AZ31 alloy sheet.

AZ31 합금 판재의 온간 점진 성형에 관한 연구 (A Study on Warm Incremental Forming of AZ31 Alloy Sheet)

  • 김상우;이영선;권용남;이정환
    • 소성∙가공
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    • 제17권5호
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    • pp.373-379
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    • 2008
  • A fundamental study on warm incremental forming of a magnesium alloy sheet has been carried out. In order to enhance the incremental formability of the magnesium alloy sheet, a local heating device was newly designed and manufactured. Through the incremental forming tests of AZ31 under various forming conditions, the effects of process parameters such as the temperature, feeding depth per cycle, and inclination angle on the incremental formability of AZ31 were investigated. In addition, conventional FLDs at elevated temperatures were constructed experimentally and applied to predict the forming failure.

AZ31B 마그네슘 합금 판재의 구성식 개발 (Constitutive Modeling of AZ31B Magnesium Alloys)

  • 이명규;정관수;김헌영
    • 소성∙가공
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    • 제16권4호
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    • pp.234-238
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    • 2007
  • Magnesium alloy sheets in room temperature have unusual mechanical properties such as high in-plane anisotropy/asymmetry of yield stress and hardening behavior. In this paper, the continuum plasticity models considering the plastic behavior of AZ31B Mg alloy sheet were derived. A new hardening law based on modified two-surface model was developed to consider the general stress-strain response of metals including Bauschinger effect, transient behavior and the unusual asymmetry. Three deformation modes observed during the continuous tension/compression tests were mathematically formulated with simplified relations between the state of deformation and their histories. To include the anisotropy and asymmetry of the initial yield stress, the Drucker-Prager's pressure dependent yield surface was modified by adding anisotropic constants.