• Title/Summary/Keyword: A356 Aluminum Alloy

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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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Grain Control of Aluminum Alloys with Electromagnetic Stirring for Rheology Forging (레오로지 단조를 위한 전자교반응용 알루미늄 합금의 결정립 제어)

  • Oh S. W.;Ko J. H.;Kim T. W.;Kang C. G.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.10a
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    • pp.350-353
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    • 2005
  • Microstructures according to experimental conditions (pouring temperature, stirring current and stirring time) and hardness according to aging time were investigated for A356 cast aluminum alloy and 7075 wrought aluminum alloy. In pouring temperature control, grains became larger and non-uniform at high temperature, however dendritic shapes were shown at lower temperature. In stirring current control, dendritic grains were not destroyed enough at lower current, however fine grains were agglomerated at higher current. And, in stirring time control, grains were more globular but grew larger and larger with the stirring time increasing.

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The Grain Size Control of A356 Aluminum Alloy by Electromagnetic Stirring (수평식 전자교반을 이용한 A356 합금의 결정립 제어)

  • Ko J. H.;Seo P. K.;Choi W. S.;Kang C. G.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2004.10a
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    • pp.111-114
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    • 2004
  • It is many devices to obtain the globular structure because the globularity of the structure is the key to the low apparent viscosity and also to good rheological properties. In this study, the morphology of the change of primary Al phase in A356 alloy by electro magnetic stirrer was investigated to obtain the globular structure. The parameters are the current, stirring time, pouring temperature individually. The greater current and longer stirring time was to get the finer the primary however in case of over the 80A of current and 60sec of stirring time, the primary Al was merged together and was increased. The effect of pouring temperature has an important effect on the size of primary phase. About the $675^{\circ}C$, the primary Al was very fined.

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Comparison of the Microstructure and Mechanical Property between Gravity Casting Forging and Rheo-diecasting Forging using A356 Alloy (A356 합금의 중력 주조/단조와 Rheo-diecasting/단조의 미세조직 및 기계적 특성 비교)

  • Lee, Jun-Young;Lim, Jae-Yong;Lee, Seung-Yong;Moon, Seoug-Won;Hong, Chun-Pyo
    • Journal of Korea Foundry Society
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    • v.33 no.5
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    • pp.210-214
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    • 2013
  • Recently, the automotive industry has replaced cast iron to lightweight materials like aluminum for engine efficiency of automobiles and an emission control by government. In this paper we studied two auto parts manufacturing methods using an alloy of A356. That is gravity casting and H-NCM Rheo-diecasting forging. We analyzed the microstructure and mechanical properties for this method. In Microstructure analysis results, H-NCM Rheo-diecasting forging has more finer microstrucre and better forging effect. Resulting in better mechanical properties than gravity forging.

Evaluation of Vibration Fatigue Life of Shipboard Equipment Made of Aluminum Alloy A356 (주조 알루미늄합금 A356을 사용한 해상구조물의 진동피로수명평가)

  • Cho, Ki-Dae;Kim, Jie-Eok;Yang, Sung-Chul;Jung, Hwa-Young;Kang, Ki-Weon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.9
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    • pp.1257-1263
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    • 2010
  • The naval structure exposes to environmental vibration of shafted propeller propulsion and engine vibration. The shipboard equipments are developed compliance to MIL-STD-167-1A. For this purpose, vibration fatigue life of shipboard equipment for long lives should be estimate via an analytical approach and vibration test. In this paper, High cycle fatigue strength of cast aluminum alloy A356 using shipboard equipment was evaluated by 14 S-N method. The stress applied on the structure is evaluated by an analytical method(frequency response analysis with sinusoidal input and a fatigue evaluation) to simulate a MIL-STD-167-1A test. The frequency with the maximum equivalent stress is shown by Max. test frequency and the vibration fatigue life of shipboard equipment was estimated by Miner's rule.

Effect of Shrinkage Defect on Fracture Impact Energy of A356 Cast Aluminum Alloy (A356 알루미늄 합금의 파단 충격에너지에 대한 수축공결함의 영향)

  • Chul, Hwang-Seong;Kwak, Si-Young
    • Journal of Korea Foundry Society
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    • v.34 no.1
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    • pp.22-26
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    • 2014
  • Internal defects, such as shrinkage during casting, cause stress concentrations and initiate cracking. Therefore, it is important to understand the effects of internal defects on the mechanical properties including the impact behavior. This study evaluates the effects of internal casting defects on the impact performance of A356 Al-alloy castings. The internal shrinkage defects in the casting impact specimen are scanned using an industrial Computed Tomography (CT) scanner, and drop impact tests are performed with varing impact velocities on the A356 casting aluminium specimen ($10mm{\times}10mm$ section area) in order to locate the fracture energy under an impact load. The specimens with defects with a diameter less than 0.35 mm exhibit equivalent fracture impact energies of approximately 32 J and those with a 1.7 mm diameter defect reduced the fracture impact energy by 35%.

Finite Element Analysis Method for Impact Fracture Prediction of A356 Cast Aluminum Alloy (A356 주조 알루미늄 합금의 충격 파괴 예측을 위한 유한요소해석 기법 연구)

  • Jo, Seong-Woo;Park, Jae-Woo;Kwak, Si-Young
    • Journal of Korea Foundry Society
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    • v.33 no.2
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    • pp.63-68
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    • 2013
  • Generally, metal is the most important material used in many engineering applications. Therefore, it is important to understand and predict the damage of metal as result of the impact. The objective of this research is to evaluate the damage criterion on the impact performance of A356 Al-alloy castings. Both experimental method and computational analysis were used to achieve the research objective. In this paper, we performed impact test according to various impact velocities to the A356 cast aluminium specimen for damage prediction. Impact computational simulation was done by applying properties obtained from the tensile test, and damages was predicted according to the damage criteria based plastic work. The good agreement of the results between the experiment and computer simulation shows that the reliability of the proposed FE simulation method to predict fracture of A356 casting components by impact.

Electrochemical Damage Characteristics of Anodized 5083 Aluminum Alloy with Flow Rate in Seawater (양극산화 처리된 5083 알루미늄 합금의 해수 내 유속변화에 따른 전기화학적 손상 특성)

  • Park, Il-Cho;Kim, Seong-Jong
    • Journal of the Korean institute of surface engineering
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    • v.49 no.4
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    • pp.349-356
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    • 2016
  • In this study, electrochemical damage behaviors with flow rate were investigated for anodized 5083 aluminum alloy in seawater. As the results of anodic polarization experiments and potentiostatic experiments at +1.0 V (vs. SSCE), the non-flow condition presented largely damaged surface resulting from a tendency of local pitting damage. Under various flow rate conditions, however, less surface damages under the application of anodic potential was obtained which is attributed to no accumulation of $H^+$ and $Cl^-$ ions on the surface. On the other hand, the results of the potentiostatic experiments at -1.0 V (vs. SSCE) with flow rate showed that anodized 5083 aluminum alloys could achieve the effective cathodic protection by low cathodic protection current density less than $2.61{\times}10^{-7}A/cm^2$ even under high flow rate of 1 m/s.

Effect of Heat Treatment on the Microstructure and Mechanical Properties of the Gravity Cast Superchargers Housing Using A356 Aluminum Alloy (A356 알루미늄 합금 슈퍼차저 하우징의 미세조직과 기계적 성질에 미치는 열처리의 영향)

  • Kim, Dae-Hwan;Van, Guen-Ho;Seong, Bong-Hak;Cho, Bok-Hwan;Eom, Jeong-Pil;Park, Seong-Gi;Lim, Su-Gun
    • Journal of Korea Foundry Society
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    • v.32 no.5
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    • pp.231-240
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    • 2012
  • In present study, the effect of heat treatment on the microstructure and mechanical properties of the gravity cast superchargers housing using A356 alloy were investigated. In order to identify the characteristics of superchagers housing casting with heat treatment, Vickers hardness test, electrical conductivity test, opical and scanning electron microscopy were performed. And also, to investigate their mechanical properties, the T6 treated superchagers housing casting in optimum heat treatment condition were carried out tensile test using UTM (Universal Testing Machine).

High Temperature Fatigue Deformation Behavior of Automotive Heat Resistant Aluminum Alloys (자동차 부품용 내열 알루미늄 합금의 고온 피로 변형 거동)

  • Park, Jong-Soo;Sung, Si-Young;Han, Bum-Suck;Jung, Chang-Yeol;Lee, Kee-Ahn
    • Korean Journal of Metals and Materials
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    • v.48 no.1
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    • pp.28-38
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    • 2010
  • High temperature high cycle and low cycle fatigue deformation behavior of automotive heat resistant aluminum alloys (A356 and A319 based) were investigated in this study. The microstructures of both alloys were composed of primary Al-Si dendrite and eutectic Si phase. However, the size and distribution for eutectic Si phase varied: a coarse and inhomogeneous distributed was observed in alloy B (A319 based). A brittle intermethallic phase of ${\alpha}-Fe\;Al_{12}(Fe,Mn)_3Si_2$ was detected only in B alloy. Alloy B exhibited high fatigue life only under a high stress amplitued condition in the high cycle fatigue results, whereas alloy A showed high fatigue life when stress was lowered. With regard to the low-cycle fatigue result ($250^{\circ}C$) showing higher fatigue life as ductility increased, alloy A demonstrated higher fatigue life under all of the strain amplitude conditions. Fractographic observations showed that large porosities and pores near the outside surface could be the main factor in the formation of fatigue cracks. In alloy B. micro-cracks were formed in both the brittle intermetallic and coarse Si phasese. These micro-cracks then coalesced together and provided a path for fatigue crack propagation. From the observation of the differences in microstructure and fractography of these two automotive alloys, the authors attempt to explain the high-temperature fatigue deformation behavior of heat resistant aluminum alloys.