• Title, Summary, Keyword: 알루미늄 합금 주조

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Corrosion Behavior of Casting Aluminum Alloys in H2SO4 Solution (H2SO4 수용액에서의 주조용 알루미늄 합금들의 부식거동)

  • Woo, Sang-Hyun;Son, Young-Jin;Lee, Byung-Woo
    • Journal of the Korea Society For Power System Engineering
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    • v.20 no.3
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    • pp.17-21
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    • 2016
  • The corrosion behavior of aluminum alloys in the $H_2SO_4$ solution was investigated based on potentiodynamic techniques. Electrochemical properties, such as corrosion potential($E_c$), passive potential($E_p$), corrosion current density($I_c$), corrosion rate(mpy), of Al-Mg-Si, Al-Cu-Si and Al-Si alloys were characterized at room temperature. Passive aluminum oxide film, which including $Al_2(SO_4)_3$ and $3Al_2O_34SO_38H_2O$, were uniformly formed on the surface via the reaction of Al with $SO{_3}^{2-}$ or $SO{_4}^{2-}$ ions in the $H_2SO_4$ solution and the dependence of the corrosion behavior on the alloying element was discussed. The selective leaching of alloy element increased with increasing Cu content in the aluminum alloys.

Effect of Porosity on the High-Cycle Fatigue Behavior of Al-Si-Mg Casting Alloy (Al-Si-Mg계 주조용 알루미늄 합금의 고주기 피로 거동에 미치는 기공의 영향)

  • Lee, Young-Jae;Kang, Won-Guk;Euh, Kwang-Jun;Cho, Kyu-Sang;Lee, Kee-Ahn
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.350-352
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    • 2009
  • The effect of porosity on the high-cycle fatigue properties of Al-Si-Mg casting aluminum alloys was investigated in this study. Microstructure examination, tensile and high-cycle fatigue test were conducted on both Al-Si-Mg casted (F) and heat-treated (T6) conditions. Porosity characteristics on the fracture surfaces of fatigue-tested samples were examined using SEM and image analysis. The microstructure observation results showed that eutectic Si particles were homogeneously dispersed in the matrix of the Al-Si-Mg casting alloys, but there were porosities formed as cast defects. The high-cycle fatigue results indicated that the fatigue strength of the 356-T6 alloy was higher than that of the 356-F alloys because of the significant reduction in volume fraction of pores by heat treatment. The SEM fractography results showed that porosity affected detrimental effect on the fatigue life: 80% of all tested samples fractured as a result of porosity which acted as the main crack initiation site. It was found that fatigue life decreased as the size of the surface pore increased. A comparison was made between surface pore and inner pore fur its effect on the fatigue behavior. The results showed that the fatigue strength with the inner pores was higher than that of the surface pore.

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Low Cycle Fatigue Characteristics of A356 Cast Aluminum Alloy and Fatigue Life Models (주조 알루미늄합금 A356의 저주기 피로특성 및 피로수명 모델)

  • 고승기
    • Transactions of the Korean Society of Automotive Engineers
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    • v.1 no.1
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    • pp.131-139
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    • 1993
  • Low cycle fatigue characteristics of cast aluminum alloy A356 with a yield strength and ultimate strength of 229 and 283 MPa respectively was evaluated using smooth axial specimen under strain controlled condition. Reversals to failure ranged from 16 to 107. The cast aluminum alloy exhibited cyclically strain-gardening behavior. The results of low cycle fatigue tests indicated that the conventional low cycle fatigue tests indicated that the conventional low cycle fatigue life model was not a satisfactory representation of the data. This occurred because the elastic strain-life curve was not-log-log linear and this phenomena caused a nonconservative and unsafe fatigue life prediction at both extremes of long and short lives. A linear log-log total strain-life model and a bilinear log-log elastic strain-life model were proposed in order to improve the representation of data compared to the conventional low cycle fatigue life model. Both proposed fatigue life models were statistically analyzed using F tests and successfully satisfied. However, the low cycle fatigue life model generated by the bilinear log-log elastic strain-life equation yielded a discontinuous curve with nonconservatism in the region of discontinuity. Among the models examined, the linear log-log total strain-life model provided the best representation of the low cycle fatigue data. Low cycle fatigue life prediction method based on the local strain approach could conveniently incorporated both proposed fatigue life models.

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Effect of Porosity on the High-Cycle Fatigue Behavior of Al-Si-Mg Casting Alloy (Al-Si-Mg계 주조용 알루미늄 합금의 고주기 피로 거동에 미치는 기공의 영향)

  • Lee, Young-Jae;Kang, Won-Guk;Euh, Kwang-Jun;Cho, Kyu-Sang;Lee, Kee-Ahn
    • Transactions of Materials Processing
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    • v.18 no.4
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    • pp.296-303
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    • 2009
  • The effect of porosity on the high-cycle fatigue properties of Al-Si-Mg casting aluminum alloys was investigated in this study. Microstructure examination, tensile and high-cycle fatigue test were conducted on both Al-Si-Mg casted (F) and heat-treated (T6) conditions. Porosity characteristics on the fracture surfaces of fatigue-tested samples were examined using SEM and image analysis. The microstructure observation results showed that eutectic Si particles were homogeneously dispersed in the matrix of the Al-Si-Mg casting alloys, but there were porosities formed as cast defects. The high-cycle fatigue results indicated that the fatigue strength of the 356-T6 alloy was higher than that of the 356-F alloys because of the significant reduction in volume fraction of pores by heat treatment. The SEM fractography results showed that porosity affected detrimental effect on the fatigue life: 80% of all tested samples fractured as a result of porosity which acted as the main crack initiation site. It was found that fatigue life decreased as the size of the surface pore increased. A comparison was made between surface pore and inner pore for its effect on the fatigue behavior. The results showed that the fatigue strength with the inner pores was higher than that of the surface pore.

Numerical Analysis on Semi-Solid Forging and Casting Process of Aluminum Alloys (알루미늄합금의 반용융 단조 및 주조공정에 관한 수치해석)

  • 강충길;임미동
    • Transactions of Materials Processing
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    • v.6 no.3
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    • pp.239-249
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    • 1997
  • The behaviour of alloys in the semi-solid state strongly depends on the imposed stress state and on the morphology of the phase which can vary from dendritic to globular. To optimal net shape forging of semi-solid materials, it is important to investigate for filling phenomena in forging process of arbitrarily shaped dies. To produce a automotive part which has good mechanical property, the filling pattern according to die velocity and solid fraction distribution has to be estimated for arbitrarily shaped dies. Therefore, the estimation of filling characteristic in the forging simulation with arbitrarily shaped dies of semi-solid materials are calculated by finite element method with proposed algorithm. The proposed theoretical model and a various boundary conditions for arbitrarily shaped dies is investigated with the coupling calculation between the liquid phase flow and the solid phase deformation. The simulation process with arbitrarily shaped dies is performed to the isothermal conditions of two dimensional problems. To analysis of forging process by using semi-solid materials, a new stress-strain relationship is described, and forging analysis is performed by viscoelastic model for the solid phase and the Darcy's law for the liquid flow. The calculated results for forging force and filling limitations will be compared to experimental data. The filling simulation of simple products performed with the uniform billet temperature(584$^{\circ}C$) from the induction heating by the commercial package MAGMAsoft. The initial step of computation is the touching of semi-solid material with the end of die gate and the initial concept of proposed system just fit with the capability of MAGMAsoft.

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A Study on Solidification Characteristics of Aluminum Alloy Casting Material by Pre-heated Temperature Conditions (예열온도조건에 따른 알루미늄 합금 주조재의 응고특성에 관한 연구)

  • Yoon, Cheonhan;Yoon, Heesung;Oh, Yoolkwon
    • Journal of the Korean Society of Safety
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    • v.27 no.4
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    • pp.7-12
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    • 2012
  • In this study, the solidification characteristics inside the AC7A casting material was analyzed using the numerical analysis method and was verified using the experimental method by the pre-heated temperature conditions of metal casting device. For the numerical analysis, "COMSOL Multiphysics", the commercial code based on the finite element analysis(FEA), was used in order to predict the thermal deformation of the AC7A casting material including temperature, displacement and stress distribution. Also, in order to verify the results calculated by the numerical analysis, the experiment for temperature measurement inside the AC7A casting material was performed using the K-type thermocouple under the same condition of numerical analysis method. In the numerical results, thermal deformation inside AC7A casting material was well-suited for manufacturing products when the pre-heated temperatures of the metal casting device was $250^{\circ}C$. When the results of the temperature distribution were experimentally measured and were compared with those of the numerical result, it appeared that there was some temperature difference because of the latent heat by phase change heat transfer. However, the result of cooling temperature and patterns were almost similar except for the latent heat interval. The solidification characteristics was closely related to the temperature difference between the surface and inside of the casting.

Evaluation of the Characteristics of the Aluminum Alloy(AC8A) Casting Material by Heat Treatment(II) (AC8A 알루미늄 합금 주조재의 열처리에 의한 특성 평가(II))

  • Moon, Kyung-Man;Jeong, Jae-Hyun;Lee, Myeong-Hoon;Baek, Tae-Sil
    • Journal of the Korea Society For Power System Engineering
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    • v.20 no.5
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    • pp.29-36
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    • 2016
  • Aluminum alloys have been widely used in engine materials, cold & hot-water storage vessels and piping etc., Furthermore, the aluminum alloy of AC8A have been widely used in mold casting material of engine piston for various vehicles because of its properties of temperature, wear and corrosion resistance. Therefore, it is considered that evaluation of corrosion resistance as well as wear resistance of AC8A material is also important to improve its property and to prolong its lifetime. In previous paper, the effect of solution($510^{\circ}C$:4hrs) and tempering($190^{\circ}C$: 16, 24, and 36 hrs)heat treatments to corrosion resistance and hardness were investigated using electrochemical method. In this study, in order to examine completely the effect of the tempering hours to hardness variation and corrosion resistance, the results of solution($510^{\circ}C$:4hrs) and tempering($190^{\circ}C$: 2, 4, 8 and 12hrs)heat treatments to hardness and corrosion resistance were investigated using electrochemical method. The hardness decreased with solution heat treatment compared to mold casting condition, but its value increased with tempering heat treatment. Furthermore, the corrosion resistance increased with decreasing of the hardness, and decreased with increasing of the hardness reversely. And the tempering heat treatment temperature at $190^{\circ}C$ for 8 hrs exhibited the highest value of the hardness and also indicated the highest corrosion current density. However, the values of hardness and corrosion current density was again increasingly decreased with increasing of tempering hours than 8 hrs, Consequently, it is suggested that decision of the optimum. tempering hours is very important to improve the corrosion or wear resistance.

Effect of Alloying Elements on the Thermal Conductivity and Casting Characteristics of Aluminum Alloys in High Pressure Die Casting (고압 다이캐스팅용 알루미늄 합금의 열전도성 및 주조성에 미치는 첨가원소의 영향)

  • Kim, Cheol-Woo;Kim, Young-Chan;Kim, Jung-Han;Cho, Jae-Ik;Oh, Min-Suk
    • Korean Journal of Metals and Materials
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    • v.56 no.11
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    • pp.805-812
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    • 2018
  • High pressure die casting is one of the precision casting methods. It is highly productivity and suitable for manufacturing components with complex shapes and accurate dimensions. Recently, there has been increasing demand for efficient heat dissipation components, to control the heat generated by devices, which directly affects the efficiency and life of the product. Die cast aluminum alloys with high thermal conductivity are especially needed for this application. In this study, the influence of elements added to the die cast aluminum alloy on its thermal conductivity was evaluated. The results showed that Mn remarkably deteriorated the thermal conductivity of the aluminum alloy. When Cu content was increased, the tensile strength of cast aluminum alloy increased, showing 1 wt% of Cu ensured the minimum mechanical properties of the cast aluminum. As Si content increased, the flow length of the alloy proportionally increased. The flow length of aluminum alloy containing 2 wt% Si was about 85% of that of the ALDC12 alloy. A heat dissipation component was successfully fabricated using an optimized composition of Al-1 wt%Cu-0.6 wt%Fe-2 wt%Si die casting alloy without surface cracks, which were turned out as intergranular cracking originated from the solidification contraction of the alloy with Si composition lower than 2 wt%.

Evaluation of the Characteristics of the Aluminum Alloy Casting Material by Heat Treatment (AC8A 알루미늄합금 주조재의 열처리에 의한 특성 평가)

  • Lee, Syung Yul;Park, Dong Hyun;Won, Jong Pil;Kim, Yun Hae;Lee, Myung Hoon;Moon, Kyung Man;Jeong, Jae Hyun
    • Corrosion Science and Technology
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    • v.11 no.6
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    • pp.280-285
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    • 2012
  • Aluminum is on active metal, but it is well known that its oxide film plays a role as protective barrier which is comparatively stable in air and neutral aqueous solution. Thus, aluminum alloys have been widely applied in architectural trim, cold & hot-water storage vessels and piping etc., furthermore, the aluminum alloy of AC8A have been widely used in mold casting material of engine piston because of its properties of temperature and wear resistance. In recent years, the oil price is getting higher and higher, thus the using of low quality oil has been significantly increased in engines of ship and vehicle. Therefore it is considered that evaluation of corrosion resistance as well as wear resistance of AC8A material is also important to improve its property and prolong its lifetime. In this study, the effect of solution and tempering heat treatment to corrosion and wear resistance is investigated with electrochemical method and measurement of hardness. The hardness decreased with solution heat treatment compared to mold casting condition, but its value increased with tempering heat treatment and exhibited the highest value of hardness with tempering heat treatment temperature at $190^{\circ}C$ for 24hrs. Furthermore, corrosion resistance increased with decreasing of the hardness, and decreased with increasing of the hardness reversely. As a result, it is suggested that the optimum heat treatment to improve both corrosion and wear resistance is tempering heat treatment temperature at $190^{\circ}C$ for 16hrs.