• Title, Summary, Keyword: Al-alloy

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Difference in Solidification Process between Al-Mg Alloy and Al-Si Alloy in Die-Casting (Al-Mg계 합금과 Al-Si계 합금의 다이캐스팅 응고과정의 차이)

  • Choi, Se-Weon;Kim, Young-Chan;Cho, Jae-Ik;Kang, Chang-Seog;Hong, Sung-Kil
    • Korean Journal of Materials Research
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    • v.22 no.2
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    • pp.82-85
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    • 2012
  • The effect of the alloy systems Al-Mg alloy and Al-Si alloy in this study on the characteristics of die-casting were investigated using solidification simulation software (MAGMAsoft). Generally, it is well known that the casting characteristics of Al-Mg based alloys, such as the fluidity, feedability and die soldering behaviors, are inferior to those of Al-Si based alloys. However, the simulation results of this study showed that the filling pattern behaviors of both the Al-Mg and Al-Si alloys were found to be very similar, whereas the Al-Mg alloy had higher residual stress and greater distortion as generated due to solidification with a larger amount of volumetric shrinkage compared to the Al-Si alloy. The Al-Mg alloy exhibited very high relative numbers of stress-concentrated regions, especially near the rib areas. Owing to the residual stress and distortion, defects were evident in the Al-Mg alloy in the areas predicted by the simulation. However, there were no visible defects observed in the Al-Si alloy. This suggests that an adequate die temperature and casting process optimization are necessary to control and minimize defects when die casting the Al-Mg alloy. A Tatur test was conducted to observe the shrinkage characteristics of the aluminum alloys. The result showed that hot tearing or hot cracking occurred during the solidification of the Al-Mg alloy due to the large amount of shrinkage.

Effect of Fe and Mn Contents on the Tensile Property of Al-9%Si-0.3%Mg Alloy for High Pressure Die Casting (고압 금형주조용 Al-9%Si-0.3%Mg 합금의 Fe, Mn 함량이 인장특성에 미치는 영향)

  • Kim, Heon-Joo
    • Journal of Korea Foundry Society
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    • v.31 no.1
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    • pp.18-25
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    • 2011
  • Effect of Fe and Mn contents on the tensile properties has been studied in Al-9wt%Si-0.3wt%Mg alloy. As Fe content of Al-9wt%Si-0.3wt%Mg-0.5wt%Mn alloy increased from 0.15wt% to 0.45wt%, tensile strength of as-cast alloy decreased from 192 MPa to 174 MPa, and elongation of the alloy also decreased from 4.8% to 4.2%. Decrease of these properties can be explained as the formation of plate shape, ${\beta}-Al_5FeSi$ phase with high Fe/Mn ratio of the alloy. However when Mn content of Al-9wt%Si-0.3wt%Mg-0.45wt%Fe alloy increased from 0.3wt% to 0.5wt%, tensile strength of T6 aged alloy increased from 265 MPa to 275 MPa, and elongation of the alloy increased from 2.3% to 3.6%. These improvements attribute to chinese script, ${\alpha}-Al_{15}(Mn,Fe)_3Si_2$ phase shape-modified from ${\beta}-Al_5FeSi$ phase with low Fe/Mn ratio of the alloy.

Microstructure and Tensile Properties of Al-Mn/Al-Si Hybrid Aluminum Alloy Prepared by Electromagnetic Duo-Casting (전자기 듀오캐스팅으로 제조한 Al-Mn/Al-Si 하이브리드 알루미늄합금의 미세조직과 인장 특성)

  • Park, Sung-Jin;Li, Tingju;Kim, Chong-Ho;Park, Jun-Pyo;Chang, Si-Young
    • Korean Journal of Materials Research
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    • v.22 no.2
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    • pp.97-102
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    • 2012
  • The microstructure and tensile properties of Al-Mn/Al-Si hybrid aluminum alloys prepared by electromagnetic duocasting were investigated. Only the Al-Mn alloy showed the typical cast microstructure of columnar and equiaxed crystals. The primary dendrites and eutectic structure were clearly observed in the Al-Si alloy. There existed a macro-interface of Al-Mn/Al-Si alloys in the hybrid aluminum alloys. The macro-interface was well bonded, and the growth of primary dendrites in Al-Si alloy occurred from the macro-interface. The Al-Mn/Al-Si hybrid aluminum alloys with a well-bonded macro-interface showed excellent tensile strength and 0.2% proof stress, both of which are comparable to those values for binary Al-Mn alloy, indicating that the strength is preferentially dominated by the deformation of the Al-Mn alloy side. However, the degree of elongation was between that of binary Al-Mn and Al-Si alloys. The Al-Mn/Al-Si hybrid aluminum alloys were fractured on the Al-Mn alloy side. This was considered to have resulted from the limited deformation in the Al-Mn alloy side, which led to relatively low elongation compared to the binary Al-Mn alloy.

A Study on the Characteristic of Gas Pore Formation in Lost Foam Casting of Mg alloy;Comparison with Al alloy (마그네슘 합금의 소실모형주조 시 기포형성 특성에 관한 연구;알루미늄 합금과 비교)

  • Shin, Seung-Ryoul;Han, Sang-Won;Lee, Kyong-Whoan
    • Journal of Korea Foundry Society
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    • v.24 no.3
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    • pp.165-174
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    • 2004
  • The pore formation characteristic of Mg alloy during Lost Foam Casting(LFC) was investigated with reduced pressure test and real casting, which was compared with the results of previous work for Al alloy. Cast Mg alloys in LFC had much lower porosities in comparison with those of Al alloys. Also, the proper pouring temperature gave the minimum porosity like Al alloy although it was higher than that of Al alloys due to the worse fluidity of Mg alloy. The pore formation mechanism of Mg alloy in LFC was similar to that of AI alloy but the critical temperature showing the different mechanism is higher than that of Al alloy as much as $30{\sim}50^{\circ}C$. The result that Mg alloy in LFC had the lower porosity comparing with Al alloy was due to the extra solubility of hydrogen gas although the solubility of Al alloy was easily exceeded by the external sources like pyrolyzed polystyrene products. The mold evacuation gave the lower porosity due to the removal of polystyrene pyrolysis products, and reduced shrinkage defects. Also, there was a proper evacuation pressure that gave a porosity of almost 0vol%. But much higher vacuum degree than this proper pressure caused the severe entrapment of polymer pyrolysis products that gave the large porosity.

The Aging Characteristics of Mg-6 wt.% Al-1 wt.% Zn Alloy Prepared by Gas Atomization (가스분사법으로 제조된 Mg-6 wt.% Al-1 wt.% Zn 합금의 시효특성)

  • Lee, Du-Hyung;Kim, Bo-Sik;Chang, Si-Young
    • Journal of Korean Powder Metallurgy Institute
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    • v.16 no.4
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    • pp.275-279
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    • 2009
  • The aging characteristics of gas atomized Mg-6 wt.% Al-1 wt.% Zn alloy were investigated and compared to those of cast Mg-6 wt.% Al alloy. The gas atomized Mg-6 wt.% Al-1wt.% Zn alloy powders had spherical morphology between 1 and 100 $\mu m$ in diameter. After compaction under the pressure of 700 MPa at $320^{\circ}C$ for 10 min, the Mg-6 wt.% Al-1 wt.% Zn alloy showed a grain size of approximately 40 $\mu m$ which is smaller than that of the cast Mg-6 wt.% Al alloy, and a relative compact density of approximately 93%. After ageing, the Mg-6 wt.% Al-1 wt.% Zn alloy showed much faster peak hardness than cast Mg-6 wt.% Al alloy. The Mg-6 wt.% Al-1 wt.% Zn alloy showed the new fine precipitations with ageing time, while the cast Mg-6 wt.% Al alloy was almost similar morphology.

The Study on the Wear-Corrosion Behavior of Al-Mg Alloy in the Coast (연안해안에서 Al-Mg 합금재 프로펠러의 마멸-부식거동에 관한 연구)

  • Park Hee-Ok;Lim Uh-Joh;Park Dong-Gi
    • Tribology and Lubricants
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    • v.20 no.2
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    • pp.97-101
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    • 2004
  • This paper reports the studies on the wear-corrosion behavior of Al-Mg alloy in various pH environments. In various pH of sea water, corrosion and wear-corrosion loss of Al-Mg alloy were investigated. Also, the polarization test of Al-Mg alloy using potentiostat/galvanostat was carried out. And the rubbed surface of Al-Mg alloy using scanning electron micrographs after wear-corrosion test was examined in various pH values of sea water. The main results are as following : The polarization resistance of Al-Mg alloy in pH 4 solution is higer than that in pH 6.7 solution, and the corrosion current density in pH 4 is controlled than in pH 6.7 solution. The wear-corrosion loss of Al-Mg alloy with lowering pH becomes sensitive. As the oxide product of Al-Mg alloy appears granular structure and exholiation phenomenon, wear-corrosion loss of Al-Mg alloy increases.

A Study on the Weldability and the Fatigue Characteristics in Resistance pot Welding of 5182-O/6061-T6 Dissimilar Aluminum Alloy Sheets (이종 AI합금의 저항점용접부 용접성과 피로특성에 관한 연구)

  • 박진철;정원욱;강성수
    • Journal of Welding and Joining
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    • v.17 no.2
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    • pp.44-52
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    • 1999
  • This study deals with spot weld ability of dissimilar aluminum alloy sheets in order to take advantage of its lightweight and strength. The paper also shows the relationship between weld elements(i.e. current, welding time and tip force) and weld quality on the resistance spot weld part of the same and dissimilar Al alloy. The conclusions are: (1) Because of excessive tip force, deep indentation remained at the Al 5182 side which is lower stiffness at the dissimilar Al alloy. (2) Weld quality (i.e. tensile shear strength) of dissimilar Al alloy is superior to that of the same Al 6061 alloy. (3) As long cycles, fatigue life of spot weld specimen on dissimilar Al alloy sheets was better than that of the same Al alloy.

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Al corrosion phenomena on the Al grain boundary after AlCu plasma etching (AlCu 플라즈마 식각후 Al 결정입계에서 Al 부식현상)

  • 김창일;권광호;윤선진;김상기;백규하;남기수
    • Journal of the Korean Institute of Telematics and Electronics A
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    • v.33A no.12
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    • pp.47-52
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    • 1996
  • Cl-based gas chemistry is generally used to etching for al alloy metallization. After the etching of Al alloy with Cl-based gas plasma, residual chlorine on Al alloy reacts with H$_{2}$O due to air exposure and results in Al corrosion. In this study, the corrosion phenomena of Al wer examined with XPS(X-ray photoelectron spectroscopy) and SEM (scanning electorn microscopy). It was confirmed that chlorine mainly existed at the grian boundary of Al alloy after plasma etching of Al alloy with cl-based gas chemistry and Al corrosion was largely generated at the grain boundary of Al alloy. And residual chlorine was passivated by sulfur and fluorine which were generated by SF$_{6}$ plasma. These effects of passivation reduced the Al corrosion due to air exposure.

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Effect of Fe, Mn Content on the Castability in Al-9wt%Si-Mg System Alloys for High Elongation (고신율 금형주조용 Al-9wt%Si-Mg계 합금의 주조특성에 미치는 Fe, Mn함량의 영향)

  • Kim, Heon-Joo;Jeong, Chang-Yeol
    • Journal of Korea Foundry Society
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    • v.33 no.6
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    • pp.233-241
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    • 2013
  • Effect of Fe and Mn contents on the castability of Al-9wt%Si-xMg-yFe-zMn alloy has been studied. The alloy was composed of ${\alpha}$-Al phase, Al+eutectic Si phase, ${\beta}$-Al5FeSi compound and chinese script ${\alpha}$-$Al_{15}(Mn,Fe)_3Si_2$ compound. ${\beta}$-$Al_5FeSi$ and ${\alpha}$-$Al_{15}(Mn,Fe)_3Si_2$ compounds assumed to effect the fluidity and shrinkage behaviors of the alloy during solidification due to the crystallization of ${\alpha}$-$Al_{15}(Fe,Mn)_3Si_2$ and ${\beta}$-$Al_5FeSi$ compounds above eutectic temperature. As Fe and Mn contents of Al-9wt%Si-0.3wt%Mg system alloy increased from 0.15wt% to 0.6wt% and from 0.3wt% to 0.7wt%, fluidity of the alloy decreased by 5.7% and 3.3%, respectively. And as Mg content of Al-9wt%Si-0.45wt%Fe-0.5wt%Mn system alloy increased from 0.3wt% to 0.4wt%, fluidity of the alloy decreased by 8.6%. When Fe content of the alloy increased from 0.15wt% to 0.6wt%, macro shrinkage ratio decreased from 6.1% to 4.1%, and micro shrinkage ratio increased from 0.04% to 0.24%. Similarly, Mn content of the alloy increased from 0.3wt% to 0.7wt%, macro shrinkage ratio decreased from 6.0% to 4.5% and micro shrinkage ratio increased from 0.12% to 0.18%. Judging from the castability of the alloy, Al-9wt%Si-0.3wt%Mg alloy with low content of Fe and Mn, 0.1wt% Fe and 0.3wt% Mn, is recommendable.

A Stud on the Fabrication and Characteristics of Al-Sn Alloy Strips by Twin-Roll Process (쌍롤법에 의한 Al-Sn합금 Strip의 제조 및 특성에 관한 연구)

  • Lee, Jeong-Keun;Joo, Dae-Heon;Kim, Myung-Ho
    • Journal of Korea Foundry Society
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    • v.22 no.4
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    • pp.174-183
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    • 2002
  • Twin-roll process is a relatively new continuous casting process which can produce high-quality strip products directly, and solidification rate can reach $10^3$ to $10^4$ K/s, leading to fine and uniform microstructures with enhanced mechanical properties. The strip casting condition for producing fine Al-Sn alloy strip was obtained experimentally, and defects appearing on the strip was examined. Crack formation and surface quality of the strip was found to depend mainly on process parameters such as melt temperature, roller gap and rolling speed. Sn structure of network type was observed in Al-20Sn and Al-40Sn alloy strips, and cell spacing of Al-40Sn alloy was smaller than that of Al-20Sn. Banding strength of the heat treated specimens increased with increasing of soaking time and temperature, and bonding strength of Al-20Sn alloy was more superior than that of Al-40Sn alloy. However wear resistance of Al-40Sn alloy contained large amount of soft Sn which possess good anti-friction characteristics was superior than that of Al-20Sn alloy.