• 제목/요약/키워드: Magnesium alloy

검색결과 562건 처리시간 0.032초

Ca$CN_2$ 첨가에 의한 AM60 마그네슘 합금의 결정립 미세화 및 기계적 성질 (Grain Refinement and Mechanical Properties of AM60 Mg Alloy by $CaCN_2$ Addition)

  • 엄정필;정승규;임수근;신희택;정득수
    • 한국주조공학회지
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    • 제18권4호
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    • pp.383-388
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    • 1998
  • Effects of $CaCN_2$ addition on the grain refinement in the AM60 magnesium ingots were investigated. The effects of the $CaCN_2$ are estimated with different inoculation temperatures, inoculation contents, and holding time to find out the optimum condition. AM60 alloy was melted in the low carbon steel crucible by cylindrical electric furnace under an argon atmosphere. The melting and casting apparatus is specially designed for magnesium alloys. The grain size of AM60 magnesium alloy decreased significantly with an increase in $CaCN_2$ content and, at 0.8 wt% $CaCN_2$ or more, grain size becomes constant at about $85 {\mu}m$. The optimum condition was obtained in the 0.8 wt% $CaCN_2$ for holding molten metal of 30 min. at the temperature of $710^{\circ}C$. The tensile properties of AM60 magnesium alloys were improved due to grain refinement by addition of $CaCN_2$. In the optimum condition, the yield strength, tensile strength and elongation were ${\sigma}_{0.2}=107 MPa$, ${\sigma}_{T.S}=234 MPa$ and e=14.2%. The variation of stress with strain obeyed the relationship of the ${\sigma}=K{\varepsilon}^n$. The strain-hardening exponent, n and strength coefficient, K obtained in the 0.8 wt% $CaCN_2$ added AM 60 magnesium alloy were n=0.21 and K=390 MPa.

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전해액 중 Sodium silicate의 농도에 따라 양극 산화된 AZ31B 마그네슘 합금 양극 피막의 특성 평가 (Characteristic Evaluation of Anodic Film Depending on the Concentration of Sodium Silicate in the Electrolyte Anodized AZ31B Magnesium Alloy)

  • 이동길;김용환;박현;정우창;정원섭
    • 한국표면공학회지
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    • 제42권3호
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    • pp.109-115
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    • 2009
  • Magnesium is one of the lightest metals, and magnesium alloys have excellent physical and mechanical properties such as high stiffness/weight ratios, good castability, good vibration and shock absorption. However their poor corrosion resistance, wear resistance, hardness and so on, have limited their application. To improve these defects, many techniques are developed. Micro arc oxidation(MAO) is a one of the surface treatments under anodic oxidation in which ceramic coating is directly formed on the surface of magnesium alloy. In this study, the characteristics of anodic film were examined after coating the AZ31B magnesium alloy through the MAO process. MAO was carried out in potassium hydroxide, potassium fluoride, and various concentration of sodium silicate in electrolyte. The morphology and chemical composition of the coating layer were characterized by SEM, XRD, EPMA and EDS. The hardness of anodic films was measured by micro-vickers hardness tester. As a result, the morphology and composition of anodic film were changed by concentration of sodium silicate. Thickness and Si composition of anodic film was increased with increasing concentration of sodium silicate in electrolyte. The hardness of anodic film was highly increased when the concentration of sodium silicate was above 40 g/l in electrolyte.

알카리성 인산-과망간산 용액을 이용한 AZ31 마그네슘 합금의 친환경 화성 처리 및 화성 피막의 특성 평가 (Characteristics of Environmentally-Friendly Conversion Coating of AZ31 Magnesium Alloy by a Alkaline Phosphate-Permanganate Solution)

  • 김명환;이만식;곽삼탁;문명준
    • 한국표면공학회지
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    • 제44권3호
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    • pp.82-88
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    • 2011
  • A uniform chromium-free conversion coating treated with an alkaline phosphate- permanganate solution was formed on the AZ 31 magnesium alloy. The effect of acid pickling on the morphology and on the corrosion resistance of the alkaline phosphate-permanganate conversion coating was investigated. The chemical composition and phase structure of conversion coating layer were determined via optical microscopy, SEM, EDS, XPS and XRD. Results show that the conversion coatings are relatively uniform and continuous, with thickness 1.8 to $2.4\;{\mu}m$. The alkaline phosphate-permanganate conversion coating was mainly composed of elements Mg, O, P, Al and Mn. The conversion-coated layers were stable compounds of magnesium oxide and spinel ($MgAl_2O_4$). These compounds were excellent inhibitors to corrosion. The electrochemical corrosion behaviors of coatings in 3.5 wt.% NaCl solutions were evaluated by electrochemical impedance spectroscopy, potentiodynamic polarization technique. EIS results showed a polarization resistance of $0.1\;k{\Omega}$ for the untreated Mg and $16\;k{\Omega}$ for the alkaline phosphate-permanganate conversion treatment sample, giving an improvement of about 160 times. The results of the electrochemical measurements demonstrated that the corrosion resistance of the AZ 31 magnesium alloy was improved by the alkaline phosphate-permanganate conversion treatment.

결정립 성장을 고려한 초소성 성형공정의 유한요소해석-II. AZ31 합금의초소성 거동 (Finite Element Analysis of Superplastic Forming Considering Grain Growth-II. Superplastic Behavior of AZ31 Alloy)

  • 김용관;김상현;권용남;김용환
    • 소성∙가공
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    • 제21권7호
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    • pp.403-411
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    • 2012
  • The aim of this study was to predict the results of superplastic forming on magnesium alloy, by considering the grain growth using numerical simulations. Superplastic behavior of AZ31 alloy was investigated through a set of uniaxial tensile tests that cover the forming temperatures ranges from 375 to $450^{\circ}C$. All the material parameters in the model, which consists of a constitutive equation and a grain growth equation, were determined. The model was used in the finite element analysis for uniaxial tensile tests and superplastic blow forming, through a user-subroutine available within ABAQUS. From this study, the effect of grain growth during forming was evaluated. The results show that it is essential to include the effect of grain growth in predicting the behavior during superplastic forming of this magnesium alloy.

Mg-9Al-lZn 합금 자동차 에어백 케이스의 다이캐스팅에 관한 연구 (A Study on the Die Casting of Mg-9Al-1Zn Alloy for Air Bag Case)

  • 김순호
    • 한국정밀공학회지
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    • 제19권10호
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    • pp.77-83
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    • 2002
  • Magnesium alloys casting are gaining increased acceptance in the automotive and electronic industeries and die casting is the most efficient method of manufacturing such mass produced parts. This study has been investigated the microstructures and mechanical properties of Mg-9Al-lZn alloy fabricated by die casting process for development of air bag case. The microstructure of die casted specimen were composed of pro-eutectic magnesium solid solution and $\beta$(Mg17Al12) precipitates. The tensile strength of as-fabricated Mg-9Al-lZn alloy revealed 231.4MPa. It was found that Mg-9Al-lZn alloy have good corrosion resistance in electrochemical polarization test.

원자단위 투과전자현미경을 활용한 알루미늄-아연-마그네슘 합금 내부 η2 석출물 성장 메커니즘 규명 (Atomic-resolution Transmission Electron Microscopy Investigation of η2 Precipitate Growth in Al-Zn-Mg Alloy)

  • 김황선;한흥남
    • 소성∙가공
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    • 제33권1호
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    • pp.12-17
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    • 2024
  • Aluminum-zinc-magnesium alloy is a well-known alloy that is both strong and lightweight. Precipitation strengthening plays a significant role in the strength mechanism of this alloy, with nano-sized η-based precipitates being the representative precipitates. However, the growth of η precipitates can lead to a decrease in strength, necessitating research into ways to control their growth. In this study, we observed the atomic-level behavior of η2 precipitates and discovered that the precipitates grew through a combination with magnesium after a zinc segregation layer was formed around them.

마그네슘 합금의 GTA 용접특성에 관한 연구 (A Study on the GTAW of Magnesium Alloys)

  • 윤병현;장웅성
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 2007년 추계학술발표대회 개요집
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    • pp.144-145
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    • 2007
  • Magnesium alloys are the lightest in commercial alloys. Also, they have high damping capacity and the shielding effect of electromagnetic waves. Recently, magnesium alloys have received considerable attention from the transportation industry. Many manufacturers of cars try to increase the use of magnesium alloys in their product. In order to evaluate the weldability of magnesium alloy, gas-tungsten arc welding(GTAW) have been applied to the AZ31, AZ61 and AZ91 alloys and established the optimum welding conditions.

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The Composition of the Rare Earth Based Conversion Coating Formed on AZ91D Magnesium Alloy

  • Chang, Menglei;Wu, Jianfeng;Chen, Dongchu;Ye, Shulin
    • Corrosion Science and Technology
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    • 제17권1호
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    • pp.1-5
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    • 2018
  • As structural materials, magnesium (Mg) alloys have been widely used in the fields of aviation, automobiles, optical instruments, and electronic products. There are few studies on the effect of coating conditions on the compositional variation during the formation process of the conversion coatings. Rare-earth based conversion coating on AZ91 magnesium alloy was prepared in ceric sulfate and hydrogen peroxide contained solution. The element composition and valence as well as their distribution in the coating were analyzed with energy dispersive X-ray spectroscopy (EDS), Electron probe micro-analyzer (EPMA), X-ray photoelectron spectroscopy (XPS). The effect of treating process on the element composition were also studied. It was found that the conversion coating surface consists of Mg, Al, O, Ce, and the weight content of Ce in the coating was affected by the treating solution concentration and immersion time; the Ce element was distributed in the coating non-uniformly and existed in the form of $Ce^{+3}$ and $Ce^{+4}$, while the O element existed in the form of $OH^-$, $O^{2-}$, $H_2O$. Based on microscopic analysis results, the electrochemical deposition mechanism on the micro-anode and micro-cathode in the process of the coating growth was suggested.

마그네슘합금의 피로파손수명의 누적확률분포특성과 신뢰성에 미치는 경계조건의 영향 (Effect of Boundary Conditions on Reliability and Cumulative Distribution Characteristics of Fatigue Failure Life in Magnesium Alloy)

  • 최선순
    • 한국산학기술학회논문지
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    • 제12권2호
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    • pp.594-599
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    • 2011
  • 본 논문은 마그네슘합금 AZ31의 피로파손수명의 확률론적 특성과 신뢰성에 미치는 경계조건의 영향을 평가하였다. 경계조건으로 시편두께와 응력비 그리고 최대피로하중을 적용하였으며, 각 경계조건별로 세부 실험조건에 대한 피로균열전파실험을 수행하여 피로파손수명에 대한 통계 데이터를 획득하였다. 마그네슘합금의 피로파손수명의 통계적 해석을 위하여 3-모수 와이블분포를 사용하였다. 시편두께가 두꺼울수록, 응력비가 클수록, 그리고 최대피로하중이 작을수록 통계적 피로파손수명이 길게 나타났다. 반면에 시편두께가 얇을수록, 응력비가 작을수록, 그리고 최대피로하중이 클수록 신뢰성이 급격히 감소하였다.

마스네슘 합금 판재 (AZ31)의 온도별 성형 특성 분석 (A study on forming characteristics of magnesium alloy (AZ31) on various temperatures)

  • 이한규;라원빈;홍소담;이창환
    • Design & Manufacturing
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    • 제12권3호
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    • pp.42-47
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    • 2018
  • Recently, in the surge of global environmental issues, there has been a great attention to lightweight materials in purpose of saving energy. Magnesium alloys not only have low specific gravity, and superb specific stiffness, but are also excellent in blocking vibrations and electromagnetic waves. So demand for this material is getting bigger rapidly throughout the industry. In this study, we examined the improvement of formability of magnesium alloy AZ31 material in warm working. Drawing, bending and shearing process were carried out by varying the forming temperature and the forming speed, and the influence of the variables on each process was studied. In the experiments, the high forming temperature and low forming speed results in high formability in the drawing process and the bending process. In the shearing process, as the forming temperature increases, the length of the fracture decreases.