A micro-cell model of the effect of microstructure and defects on fatigue resistance in cast aluminum alloys

Gao, Yulin; Yi, J. Z.; Lee, Peter; Lindley, T.C.

doi:10.1016/j.actamat.2004.07.035

Cited by 121 publications

(93 citation statements)

References 27 publications

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“…Thus, similarly to what was seen by Gao et al in terms of fatigue resistance [5], it would appear that the presence of porosity increases the local stress, and localizes the plastic strain.…”

Section: The Effect Of Grain Size and Porosity On Model Predictionsmentioning

confidence: 61%

“…In other research areas, a number of modeling studies have been reported which link microstructural features to the macro constitutive behavior [1][2][3][4][5][6][7][8]. These studies include the prediction of 3D polycrystalline microstructure with crystallographic orientation and secondary phase particles by combining 2D micrographs with a modified 3D Voronoi tessellation function [6][7][8], along with the prediction of fatigue behavior of multi phase material by coupling simulations of micro-plasticity in idealized microstructure with experimental measurements [5].…”

Section: Introductionmentioning

confidence: 99%

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A three-phase simulation of the effect of microstructural features on semi-solid tensile deformation

Phillion¹,

Cockcroft²,

Lee³

2008

Acta Materialia

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A direct finite element microstructure model for prediction of the deformation behavior of semisolid metallic alloys is presented. The 2D model geometry is based on a modified Voronoi tessellation, and includes rounded corners to approximate an equiaxed-globular grain structure, liquid surrounding the grains, and micro porosity. An elasto-plastic empirical constitutive equation is derived for the solid grains, while the liquid is approximated as a perfectly plastic material with a very low yield stress. The resulting three-phase model was used to investigate the effects of fraction solid, porosity, and grain size on the constitutive behavior of a semi-solid aluminum alloy, AA5182. The model predictions were validated against experimental data at high fraction solid. These simulations reveal a strong correlation between semi-solid grain size and yield stress, and between porosity and strain localization. The application of direct finite element simulations is shown to be an effective technique for examining the effects of microstructure phenomena on the macro constitutive behavior of semi-solid materials.

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Section: The Effect Of Grain Size and Porosity On Model Predictionsmentioning

confidence: 61%

Section: Introductionmentioning

confidence: 99%

A three-phase simulation of the effect of microstructural features on semi-solid tensile deformation

Phillion¹,

Cockcroft²,

Lee³

2008

Acta Materialia

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“…Towards the end of solidification, the undercooling increases again as the final melt pools trapped between the eutectic cells 1 solidify [11]. The varying growth conditions 1 To avoid confusion, in this paper, the term "cell" (cell size, cell shape/morphology, etc.) will be exclusively used to describe a discrete entity of Al-Si eutectic, i.e.…”

Section: Introductionmentioning

confidence: 99%

“…Sub-surface pores are exposed by machining and affect aesthetic appearance, the presence of large pores at stressed areas detrimentally affect fatigue life [1], and interconnected porosity has an adverse effect on pressure tightness. Numerical modelling of solidification has been reasonably effective in predicting the likely location of significant porosity/shrinkage in castings, but the finer details are still lacking.…”

Section: Introductionmentioning

confidence: 99%

A new multi-zone model for porosity distribution in Al–Si alloy castings

2013

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Link back to DTU Orbit Citation (APA):Tiedje, N. S., Taylor, J. A., & Easton, M. A. (2013). A new multi-zone model for porosity distribution in Al-Si alloy castings. Acta Materialia, 61(8), 3037-3049. DOI: 10.1016/j.actamat.2013 AbstractA new multi-zone model is proposed that explains how porosity forms in various regions of a casting under different conditions and leads to distinct zonal differences in pore shape, size and distribution. This model was developed by considering the effect of cooling rate on solidification and distribution of porosity in Al-Si alloys cast as plates in moulds made with silica, ilmenite or zirconia sand cores or steel chills facing the major plate faces. The alloys cast were Al-7wt% Si and Al-12.5wt% Si in unmodified and modified forms, the latter with either Na or Sr addition. It is found that regardless of cooling condition, Si content and modification treatment the microstructure can be divided into three zones of varying size (across the casting thickness) that are determined by the local cooling conditions and the nucleation and growth mode of the Al-Si eutectic. The zones are: (1) an outer shell-like zone where directional columnar dendritic grains and a fine celled, coherent eutectic form a low porosity shell at the casting surface; (2) a transitional zone where equiaxed, eutectic cells grow between columnar dendritic grains and irregular pores become trapped in the mush; and finally, (3) a central zone where the thermal gradient is low and equiaxed dendritic grains and eutectic cells grow at the centre of the casting and larger rounded pores tend to form. The paper discusses how Si content, modification type and cooling conditions influence the location and size (i.e. depth) of each of these zones and how the distribution of porosity is thus affected.

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“…From this point of view, lots of studies have been carried out on tensile properties and fatigue properties of die-casts containing porosity, [1][2][3][4][5][6][7] shrinkage cavity, 8,9) oxide inclusion, [10][11][12] microstructure [13][14][15] and other casting defects. [16][17][18][19][20][21][22][23][24][25] Among casting defects, interests have been concentrated in the effect of the cold flake, [21][22][23][24][25] one of irregular structures. The cold flake is introduced in die-cast products during production process: when the molten metal is poured in the shot sleeve and pushed in a die by a plunger, the initially solidified layer of the melt is broken into small parts, and these parts distribute in the molten metal to remain as cold flakes.…”

Section: Introductionmentioning

confidence: 99%

Influence of Casting Defects on Tensile Properties of ADC12 Aluminum Alloy Die-Castings

Ahamed

Katô

2008

Mater. Trans.

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Cold flakes, one of casting defects, were observed through acoustic microscopy in aluminum alloy die-cast plates (ADC12), and specimens having a cold flake of different sizes were prepared and subjected to the tensile testing. The tensile strength linearly decreased with the size of the cold flake, and the decreasing rate of the strength was greater for the specimen with the exposed cold flake than that with the embedded cold flake. The in-process ultrasonic measurement was carried out during tensile testing, and it was found that the oxide layer of the cold flake was detached from the matrix to form a crack before final failure. Then by using the linear fracture mechanics, the critical value K c Ã at failure was evaluated to be 8-10 MPaÁm 1=2 from the tensile strength, which value was slightly lower than the fracture toughness of the matrix of

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A micro-cell model of the effect of microstructure and defects on fatigue resistance in cast aluminum alloys

Cited by 121 publications

References 27 publications

A three-phase simulation of the effect of microstructural features on semi-solid tensile deformation

A three-phase simulation of the effect of microstructural features on semi-solid tensile deformation

A new multi-zone model for porosity distribution in Al–Si alloy castings

Influence of Casting Defects on Tensile Properties of ADC12 Aluminum Alloy Die-Castings

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