• Title/Summary/Keyword: AZ61

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Effect of time variation on formation of oxide layers of AZ61 magnesium alloy by Electrolytic plasma processing (EPP공정시간에 따른 AZ61 마그네슘 합금 코팅층의 특성변화)

  • Jeong, Yeong-Seung;Park, Geun-Yeong;Kim, Seong-Jae;Gu, Bon-Heun
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2014.11a
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    • pp.281-282
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    • 2014
  • 본 연구는 공정시간에 따른 전해 플라즈마 공정(Electrolytic Plasma Processing, EPP) 공정에 의해 형성된 산화 코팅층의 특성 변화를 알아보고자 한다. 실험에 사용되는 전해용액은 $Na_2SiO_3$(12g/l) + $Na_2SiF_6$(0.3g/l)+NaOH(3g/l) 기본용액에 다양한 농도의 NaOH(0-5g/l) 첨가한 전해용액을 사용하였다. AZ61 마그네슘 합금을 모재($22{\Phi}{\times}10mm$)로 사용하였으며 실험은 5분-60분 동안 진행되었다. 공정시간에 변화에 따른 EPP 코팅층 특성을 측정한 결과 공정시간이 증가함에 따라 코팅층 표면의 기공 크기가 커지고 코팅층 내에 기공수가 즐어드는 것을 확인하였다. 또한 XRD 분석을 통하여 형성된 코팅층에서 MgO, Mg2SiO4 상이 나타난 것을 확인할 수 있었다.(No. 2011-0030058),(2012H1B8A2026212)

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Effect of Processing Time on the Microarc Oxidation Coatings Produced on Magnesium AZ61 Alloy at Constant Hybrid Voltage

  • Ur Rehman, Zeeshan;Jeong, Yeong Seung;Koo, Bon Heun
    • Korean Journal of Materials Research
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    • v.25 no.10
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    • pp.509-515
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    • 2015
  • MAO ceramic coatings were prepared on AZ61 magnesium alloy for various processing times ranging from 5 to 60 min, in an electrolyte solution based on silicate-fluoride. The mechanical, electrochemical and, microstructural properties and the phase compositions of the coating layers were investigated. In this work, unlike previous studies, coatings with high amounts of the $Mag_2SiO_4$ phase were formed which contained small amounts of MgO and $MgF_2$ at a processing condition of 30 min. A microstructural analysis revealed that the porosity of the coatings was reduced considerably with an increase in the processing time, together with a change in the pore geometry from an irregular to a spherical shape. Potentiodynamic polarization and mechanical testing results showed that the coatings acquired after a processing time of 30 min were superior to all of the others.

Dissimilar Friction Stir Welding Characteristics of Mg Alloys(AZ31 and AZ61) (AZ31와 AZ61 마그네슘 합금의 이종 마찰교반용접 특성)

  • Park, Kyoung Do;Lee, Hae Jin;Lee, Dai Yeol;Kang, Dae Min
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.16 no.5
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    • pp.99-104
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    • 2017
  • Friction stir welding is a solid-state joining process and is useful for joining dissimilar metal sheets. In this study, the experimental conditions of the friction stir welding were determined by the two-way factorial design to evaluate the characteristics of the dissimilar friction stir welding of AZ31 and AZ61 magnesium alloys. The levels of rotation speed and welding speed, which are welding variables, were 1000, 2000, 3000 rpm and 100, 200, 300 mm/min, respectively. From the results, the greater the rotation speed and the lower the welding speed of the tool were, the greater the tensile strength of the welded part was. The contribution of the welding speed of the tool is larger than that of the rotation speed of the tool. In addition, the optimal conditions for tensile strength in the dissimilar friction stir joint were predicted to be the rotation speed of 3000 rpm and welding speed of 100 mm/min, and the tensile strength under the optimal conditions was estimated to be $214{\pm}6.57Mpa$ with 99% reliability.

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

  • Yun, Byeong-Hyeon;Jang, Ung-Seong
    • Proceedings of the KWS Conference
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    • 2007.11a
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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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A Comparative Study for Chemical Conversion Layers on Magnesium Alloys (마그네슘 합금에 따른 화성피막 비교)

  • Kim, Hye-Jeong;Park, Yeong-Hui;Gang, Gyeong-Su
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2011.05a
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    • pp.45-45
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    • 2011
  • 마그네슘 합금은 상용 구조용 합금 중에서 비중이 1.74로 가장 낮아 경량화가 요구되는 분야에서 오랫동안 각광을 받아왔다. 그러나 마그네슘 합금은 상용 금속들 중에서 가장 화학적 활성이 커서 표면처리 후 내식성 확보가 필수적이다. 기존의 마그네슘 합금의 표면처리 방법은 주로 AZ91D의 다이캐스팅재에 집중되어 왔으며, 포스코에서 생산되는 AZ31의 스트립 캐스팅재의 표면처리는 합금의 차이로 인하여 공정이 새롭게 개발되어야 한다. 본 연구에서는 화성처리 공정에서 AZ31, AZ61, AZ91D의 합금 차이에 의한 화성피막의 특성을 고찰하였다.

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CrN and TiN Coatings for the Wear Resistance of Extrusion Mold for Magnesium (마그네슘 압출용 금형의 내마모성 향상을 위한 CrN, TiN 코팅)

  • Lee, Su-Young;Kim, Sang-Ho
    • Journal of the Korean institute of surface engineering
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    • v.44 no.6
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    • pp.233-238
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    • 2011
  • The friction and wear characteristics of CrN and TiN coatings on SKD61 which is mold material using for extrusion of AZ80 magnesium alloy were investigated. The coatings were deposited by the arc ion-plating method, and the thickness were about $3.59{\mu}m$ and $3.28{\mu}m$, respectively. Reciprocating friction wear tests were conducted by varying pin load and temperature of counter substrate at un-lubricated condition. The pin loads were 11, 15 and 19 kgf, and the substrate temperatures were room temperature and $120^{\circ}C$. CrN coating which has a lower friction coefficient and a smaller adhesive wear with AZ80 magnesium alloy showed better wear resistance than TiN coating.

Influence of OH- Ion Concentration on the Properties of Eelectrolytic Plasma Oxide Coatings Formed on AZ61A Alloy (전해 플라즈마 공정에 의해 AZ61A 합금에 형성된 산화물층의 특성에 미치는 OH- 이온 농도의 영향)

  • Shin, Seong Hun;Jeong, Young Seung;Rehman, Zeeshan Ur;Koo, Bon Heun
    • Korean Journal of Materials Research
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    • v.26 no.10
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    • pp.513-520
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    • 2016
  • The effect of NaOH concentration on the properties of electrolytic plasma processing (EPP) coating formed on AZ61A Mg alloy is studied. Various types of EPP were employed on magnesium alloy AZ61A in a silicate bath with different concentrations of NaOH additive. Analysis of the composition and structure of the coating layers was carried out using an X-ray diffractometer (XRD) and a scanning electron microscope (SEM). The results showed that the oxide coating layer mainly consisted of MgO and $Mg_2SiO_4$; its porosity and thickness were highly dependent on the NaOH concentration. The Vickers hardness was over 900 HV for all the coatings. The oxide layer with 3 g/l of NaOH concentration exhibited the highest hardness value (1220 HV) and the lowest wear rate. Potentiodynamic testing of the 3 g/l NaOH concentration showed that this concentration had the highest corrosion resistance value of $2.04{\times}10^5{\Omega}cm^2$; however, the corrosion current density value of $5.80{\times}10^{-7}A/cm^2$ was the lowest such value.

Temperature and Mechanical Properties of Welded Joints Under Friction Stir Welding Conditions of Mg Alloy (AZ61) (Mg Alloy(AZ61) 마찰교반용접 조건에 따른 용접부의 온도와 기계적 특성변화)

  • Lee, Woo Geun;Kim, Jung Seok;Sun, Seung-Ju
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.26 no.4
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    • pp.378-386
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    • 2017
  • Friction stir welding was performed using six welding conditions to evaluate the mechanical properties and microstructure of the welded zone based on its temperature change in the extruded plate of magnesium alloy AZ61. The welded zone temperature was measured using a thermocouple, and the maximum temperature ranges for the advancing and retreating sides were approximately $210-315^{\circ}C$ and $254-339^{\circ}C$, respectively. Depending on the welding conditions, a temperature difference of more than $100^{\circ}C$ was observed. In addition, the maximum yield strength and maximum tensile strength of the welded component was 84.4% and 96.9%, respectively, of those of the base material. For the temperatures exceeding $300^{\circ}C$, oxidation defects occurred in the weld zone, which decreased the mechanical strength of the weld zone. The microstructure and texture confirmed that fracture occurred because of the grain size deviation of the welding tool and the severe anisotropy of the texture of the welded joints.

Evaluation of Mechanical Properties and Analysis of Microstructure of AZ61 Magnesium Alloy Butt Joints by Friction Stir Welding (AZ61 마그네슘 합금 마찰교반용접부의 기계적 특성 평가 및 미세조직 분석)

  • Sun, Seung-Ju;Kim, Jung-Seok;Lim, Jae-Yong;Lee, Woo-Geun;Go, Yo-Han;Kim, Young-Min;You, Bong-Sun
    • Journal of the Korean Society for Railway
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    • v.19 no.4
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    • pp.417-426
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    • 2016
  • In this study, the optimal welding condition of an extruded AZ61 magnesium alloy plate was investigated through evaluation of the mechanical properties and microstructure in the friction stir welding zones. The friction stir welding conditions considered in this study were the tool rotation speeds of 400, 600, and 800rpm and the welding speeds of 200, 300, and 400mm/min. To evaluate the welding strength, tensile and hardness tests were carried out. Microstructures of the welded regions were examined using optical microscopes. Under a tool rotation speed of 800rpm and welding speed of 200mm/min, the joint showed the best joining properties. The UTS, yield strength, and elongation of the welded region showed values of 79.0%, 65.4%, and 30.1%, respectively, of those of the base metal.

Evaluation of Joint Properties of Friction Stir Welded AZ31B Mg Alloy (FSW를 이용한 AZ31B Mg합금의 접합성 평가)

  • 노중석;김흥주;장웅성;방국수
    • Journal of Welding and Joining
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    • v.22 no.3
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    • pp.56-61
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    • 2004
  • Friction stir weldability of AZ31B Mg alloy was studied using microstructural observation and mechanical tests. Defect free joints was obtained under the condition of 2000rpm-100mm/min. In TMAZ, a lot of twin deformation were observed due to the mechanical effect of the FSW tool and thus relatively high hardness was obtained. In SZ, the twin deformation was disappeared by recovery and the hardness decreased because the. grain structure was coarsened by dynamic recrystallization and grain growth. The Al-Mn precipitates were observed throughout the joint regions. On the other hand, $$\beta$-Mg_{17}Al_{12}$ intermetallic compounds were not observed in either of the zone. The joint efficiency was about 80% and the impact value of the joint was almost equal to that of base metal.