The Porosity Description in Hypoeutectic Al-Si Alloys

Dybowski, Bartłomiej; Poloczek, Łukasz; Kiełbus, A.

doi:10.4028/www.scientific.net/kem.682.83

Cited by 5 publications

(4 citation statements)

References 8 publications

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“…Moreover, silicon expands on solidification and counteracts the solidification shrinkage of aluminum. 51,52 Overall, the silicon content is important in porosity failures since it affects the mold filling and solidification shrinkage. In this study, silicon content is included as monitored variable.…”

Section: Causes Of Porosity Defects In Lpdcmentioning

confidence: 99%

“…This corresponds with known casting physics, where the silicon content of the aluminum effects the fluidity which in turn effects porosity formations. 51,52 The third highest contributor is again an air channel flow standard deviation but of the top mold center hub. The Shapley indices indicate that the upper and lower air channels at the center have highest influence on porosity, this corresponds with understood physics since that is the thickest area of the casting as shown in Figure 1.…”

Section: Journal Of Metalcastingmentioning

confidence: 99%

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Industry 4.0 Foundry Data Management and Supervised Machine Learning in Low-Pressure Die Casting Quality Improvement

et al. 2022

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Low-pressure die cast (LPDC) is widely used in high performance, precision aluminum alloy automobile wheel castings, where defects such as porosity voids are not permitted. The quality of LPDC parts is highly influenced by the casting process conditions. A need exists to optimize the process variables to improve the part quality against difficult defects such as gas and shrinkage porosity. To do this, process variable measurements need to be studied against occurrence rates of defects. In this paper, industry 4.0 cloud-based systems are used to extract data. With these data, supervised machine learning classification models are proposed to identify conditions that predict defectives in a real foundry Aluminum LPDC process. The root cause analysis is difficult, because the rate of defectives in this process occurred in small percentages and against many potential process measurement variables. A model based on the XGBoost classification algorithm was used to map the complex relationship between process conditions and the creation of defective wheel rims. Data were collected from a particular LPDC machine and die mold over three shifts and six continuous days. Porosity defect occurrence rates could be predicted using 36 features from 13 process variables collected from a considerably small sample (1077 wheels) which was highly skewed (62 defectives) with 87% accuracy for good parts and 74% accuracy for parts with porosity defects. This work was helpful in assisting process parameter tuning on new product pre-series production to lower defectives.

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Section: Causes Of Porosity Defects In Lpdcmentioning

confidence: 99%

Section: Journal Of Metalcastingmentioning

confidence: 99%

Industry 4.0 Foundry Data Management and Supervised Machine Learning in Low-Pressure Die Casting Quality Improvement

et al. 2022

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“…[18] Formation of blisters can cause cast parts to be scrapped and reduce productivity. [19] Because of this problem, heat treatments of HPDC parts are problematic and usually lower temperatures and/or shorter durations are selected. [20] In the case of Al-Si-Cu-Mg alloys, the intermetallics that can be formed are mainly Al 2 Cu (θ), Mg 2 Si, and Al 5 Cu 2 Mg 8 Si 6 (Q) phases.…”

Section: Introductionmentioning

confidence: 99%

Heat Treatment Conditions for High‐Performance High‐Pressure Die‐Cast Al–Si–Cu–Mg Alloy

Demirtaş,

Karakulak,

Babu

2023

Adv Eng Mater

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Random porosity in high‐pressure die castings of aluminum alloys poses additional challenges in the form of blistering during follow‐on heat treatment process. To avoid blisters, the current industrial practice is to lower solution temperature, but this compromises the strength. Herein, kinetics of eutectic Si spheroidization and coarsening during various solution treatment conditions and maximizing the dissolution of much needed Al2Cu and Al5Cu2Mg8Si6 phases, followed by formation of their precipitates in the aging stage with higher particle number densities, are studied and then higher tensile strength of 435 MPa in most commonly used high‐pressure die‐cast Al–Si–Cu–Mg alloy without causing blisters is demonstrated.

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“…Volumetric shrinkage in metals transforming from liquid to solid state may range from 3 to 10%, with 5-8% being typical of most cast alloys and taking place in different forms. e other major source of porosity is caused by the dissolution of the hydrogen gas in the solidifying solid as a result of the reduction of hydrogen solubility [1][2][3][4][5][6][7][8][9][10]. Majority of porosity observed in castings is caused by a combination of gas and shrinkage.…”

Section: Introductionmentioning

confidence: 99%

A Review Study on the Main Sources of Porosity in Al‐Si Cast Alloys

Samuel

Zedan

Doty

et al. 2021

Advances in Materials Science and Engineering

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The present study was performed on A356 and B319 alloys in mechanically stirred or degassed condition. Melts were Sr-modified and grain-refined. Hydrogen content was varied from less than 0.1 ml/100 g Al to ∼0.4 ml/100 g Al; Fe was increased to 0.8% in B319 alloy. Lanthanum and cerium were added as 99.5% pure metals. Two main techniques were used to investigate porosity formation: fracture surface of tensile or fatigue test bars, or reduced pressure test (RPT) method. Porosity type and shape were examined. The results show that pore size is more influential than small scattered ones from a mechanical point of view. Tensile testing is affected by porosity located at the center of the testing bar, whereas edge porosity is responsible for crack initiation in case of fatigue testing. Intermetallics precipitate in the form of intercepted platelets which restricts the flow of the molten metal, leading to formation of shrinkage cavities. Precipitation of clusters of compounds from the liquid state such as Al2Si2Sr, Mg2Sn, Al3Ti, or added Al2O3particles would as well act as nucleation sites for porosity formation. Most oxides were observed in the form of long branched strings. In some cases, bifilms were also reported in addition to SrO and MgO.

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The Porosity Description in Hypoeutectic Al-Si Alloys

Cited by 5 publications

References 8 publications

Industry 4.0 Foundry Data Management and Supervised Machine Learning in Low-Pressure Die Casting Quality Improvement

Industry 4.0 Foundry Data Management and Supervised Machine Learning in Low-Pressure Die Casting Quality Improvement

Heat Treatment Conditions for High‐Performance High‐Pressure Die‐Cast Al–Si–Cu–Mg Alloy

A Review Study on the Main Sources of Porosity in Al‐Si Cast Alloys

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