Modelling of different entrainment mechanisms and their influences on the mechanical reliability of Al-Si castings

Modelling of three common entrainment mechanisms in fluid flow, namely plunging jet, return wave and rising jet, that generating defects during casting were conducted and validated by A356 alloy. Previous research highlighted surface turbulence in liquid metals could result in the fold-in of surface...

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Bibliographic Details
Published in:IOP conference series. Materials Science and Engineering 2012-01, Vol.33 (1), p.12072-8
Main Authors: Yue, Y, Green, N R
Format: Article
Language:English
Subjects:
Algorithms
Aluminum base alloys
Bend strength
Bend tests
Casting
Casting defects
Castings
Computational fluid dynamics
Defects
Density
Entrainment
Fluid flow
Fracture strength
Free surfaces
Liquid metals
Mathematical models
Mechanical properties
Modelling
Radiography
Reliability
Silicon
Three dimensional flow
Turbulence
Turbulent flow
Unsteady flow
X-ray radiography
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Summary:Modelling of three common entrainment mechanisms in fluid flow, namely plunging jet, return wave and rising jet, that generating defects during casting were conducted and validated by A356 alloy. Previous research highlighted surface turbulence in liquid metals could result in the fold-in of surface films into bulk liquid and leave cracks or porosity in the solidified component. An algorithm applied face normals of free surface and their interaction to capture the entrainment of surface films was used in study. The model integrated the algorithm into CFD package FLOW-3D and was used to track the entrainment defects formation and distribution involved in different entrainment behaviours in casting process. The defects density in local volume plotted by the model was then employed as quantitative criteria to predict the reliability of castings. Directly observation of transient flows in moulds by real-time X-ray radiography showed good correlation between real filling scenario and simulation results. Fracture strength achieved by four-point bend tests on the samples from corresponding locations with models in castings showed some extent relationship between defects density and reliability of castings quantitatively. Studies also indicated the plunging jet mechanism usually leaded to high variation of mechanical properties due to intense turbulence and entrainment.
ISSN:1757-899X
1757-8981
1757-899X
DOI:10.1088/1757-899X/33/1/012072