Quantification of Entrainment Damage in A356 Aluminum Alloy Castings

Tiryakioğlu, Murat; Yousefian, Pedram; Eason, Paul D.

doi:10.1007/s11661-018-4865-z

Cited by 34 publications

(13 citation statements)

References 30 publications

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“…In a recent study [88], pores in reduced pressure test samples of an A356 alloy were evaluated by scanning electron microscopy. Pores were found to be initiated by entrainment defects, i.e., oxide bifilms, as expected.…”

Section: Figurementioning

confidence: 99%

“…We will now reach into several studies in the literature with extreme data on both ends of the spectrum to discuss the combined effect of hydrogen content and entrainment damage (bifilm content) on pore formation. In a recent study [88], pores in reduced pressure test samples of an A356 alloy were evaluated by scanning electron microscopy. Pores were found to be initiated by entrainment defects, i.e., oxide bifilms, as expected.…”

Section: Figurementioning

confidence: 99%

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The Effect of Hydrogen on Pore Formation in Aluminum Alloy Castings: Myth Versus Reality

Tiryakioğlu

2020

Metals

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The solubility of hydrogen in liquid and solid aluminum is reviewed. Based on classical nucleation theory, it is shown that pores cannot nucleate either homogeneously or heterogeneously in liquid aluminum. Results of in situ studies on pore formation show that pores appear at low hydrogen supersaturation levels, bypassing nucleation completely. The results are explained based on the bifilm theory introduced by Prof. John Campbell, as this theory is currently the most appropriate, and most likely, the only mechanism for pores to form. Examples for the effect of hydrogen on pore formation are given by using extreme data from the literature. It is concluded that a fundamental change in how hydrogen is viewed is needed in aluminum casting industry.

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Section: Figurementioning

confidence: 99%

Section: Figurementioning

confidence: 99%

The Effect of Hydrogen on Pore Formation in Aluminum Alloy Castings: Myth Versus Reality

Tiryakioğlu

2020

Metals

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“…Therefore, the loss in Q T of 0.78, estimated with almost no pores in the structure, is an indication of the inherent entrainment damage of the experimental (or production) system. Recently, the author and co-workers [24] identified bifilms in A356 aluminum alloy reduced pressure test specimens that remained inactive, i.e., were not needed for the formation of pores. Building on this finding, we can expect in low-quality specimens to have a higher density of bifilms than needed to accommodate pores due to internal solidification shrinkage and/or hydrogen rejection.…”

Section: Dendrite Arm Spacing-ductility Relationshipmentioning

confidence: 99%

“…Due to these bifilms that are extrinsic, nucleation is completely bypassed, and pores form simply by the opening of bifilms [6]. There is growing evidence in the literature on the role of bifilms on causing pores [6,13,[16][17][18][19][20][21][22][23][24][25][26] and leading to hot tears [27,28]. Oxides are inevitable on the surface of liquid aluminum and serve as a protective film over the liquid.…”

Section: Introductionmentioning

confidence: 99%

Intrinsic and Extrinsic Effects of Microstructure on Properties in Cast Al Alloys

Tiryakioğlu

2020

Materials

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The metallurgy of cast aluminum alloys has always been considered to be different from that of wrought alloys. Metallurgists have been taught that pores are intrinsic in cast aluminum alloys and that mechanical properties in cast aluminum alloys are controlled by dendrite arm spacing, the presence of Fe-bearing particles, and the size of Si particles in Al–Si alloys, which fracture and debond during deformation, leading to premature failure. Whether these effects are intrinsic or extrinsic, i.e., mere correlations due to the structural quality of castings, is discussed in detail. Ideal properties are discussed, based on findings presented mostly in physics literature. Pores and hot tears in aluminum castings are extrinsic. Moreover, the effect of dendrite arm spacing on elongation, precipitation, and subsequent fracture of β–Al5FeSi platelets, and finally Si particle fracture and debonding are all extrinsic. A fundamental change in how we approach the metallurgy of cast aluminum alloys is necessary.

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“…It was demonstrated from Refs. [5,29,[31][32][33] that a decrease in Weibull modulus corresponds to a decrease in results in undesirable situations, whereas an increase in Weibull modulus accounts for favorable cases in the production of high-quality alloy castings. Higher Weibull modulus indicates higher average and lower scatter as in Figs.…”

Section: Weibull Modulusmentioning

confidence: 99%

Weibull analysis of fluidity and hardness of ultrasonically degassed secondary Al7Si0.3Mg aluminum alloy

Yüksel

2019

China Foundry

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I n foundry engineering, casting parameters, such as fluidity and turbulent filling directly affect the properties of the cast metals, i.e. hardness and tensile strength. Predicting these parameters can improve the entire casting process. Also, it is necessary to establish these variables in simulation techniques, and casting procedures, i.e. fluidity test and mechanical test [1]. Dong et al. [2] have investigated the effect of ultrasonic stirring on hardness and concluded that if porosities were not eliminated, the hardness values of the materials could not be increased, even if average grain diameter and eutectic silicon aspect ratio are both lowered. Moussa et al. [3] has established ascending hardness values on Mg 5 Si alloy being exposed to the ultrasonic degassing (UD) process with a 38% increase with regard to modification and refining of microstructural constituents. The variation of the mechanical properties of Al-Si alloys was investigated with solute addition and ultrasonic process. It is found that the solute addition has a great contribution to the hardness values of the alloy, and also

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Quantification of Entrainment Damage in A356 Aluminum Alloy Castings

Cited by 34 publications

References 30 publications

The Effect of Hydrogen on Pore Formation in Aluminum Alloy Castings: Myth Versus Reality

The Effect of Hydrogen on Pore Formation in Aluminum Alloy Castings: Myth Versus Reality

Intrinsic and Extrinsic Effects of Microstructure on Properties in Cast Al Alloys

Weibull analysis of fluidity and hardness of ultrasonically degassed secondary Al7Si0.3Mg aluminum alloy

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