Porosity Prediction in A356 Wheel Casting

Journal Article · Tue Oct 15 04:00:00 EDT 2019 · Metallurgical and Materials Transactions. B, Process Metallurgy and Materials Processing Science

DOI:https://doi.org/10.1007/S11663-019-01642-9· OSTI ID:22933468

Cockcroft, S. L.; Maijer, D. M.; Yao, L. ^[1]; Reilly, C. ^[2]; Phillion, A. B. ^[3]

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1. The University of British Columbia, Department of Materials Engineering (Canada)
2. Cast Analytics Inc. (Canada)
3. McMaster University, Department of Materials Science and Engineering (Canada)

A FLUENT™-based thermal-fluid-compositional model has been developed and applied to a low-pressure, die-cast, A356 aluminum alloy wheel to explore the effects of macro-segregation of hydrogen and late-stage liquid encapsulation on pore formation during solidification. Based on the evolution of temperature, pressure, and hydrogen concentration in the liquid output from FLUENT, the porosity size distribution has been predicted at a number of locations in a commercially produced wheel using an in-house micro-porosity model. The porosity model incorporates pore nucleation kinetics based on hydrogen supersaturation, and two modes of pore growth: the first, occurring at low solid fractions is based on hydrogen diffusion; and the second, occurring at high solid fractions is based on conservation of volume. Samples from a commercially cast wheel have been analyzed using X-ray micro-tomography to provide basic validation of the micro-porosity model. The predicted results showed that the evolution in pressure has the dominant effect on pore growth, but only under conditions where pores have nucleated prior to late-stage liquid encapsulation. Otherwise, the cooling rate appears to have the dominant effect. The accuracy of the model is discussed in terms of the predicted pore size distribution and number density of pores. Areas for continued development are presented.

• OSTI ID: 22933468
• Journal Information: Metallurgical and Materials Transactions. B, Process Metallurgy and Materials Processing Science, Journal Name: Metallurgical and Materials Transactions. B, Process Metallurgy and Materials Processing Science Journal Issue: 5 Vol. 50; ISSN 1073-5615; ISSN MTBSEO
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
CASTING
CONCENTRATION RATIO
COOLING
DIES
DIFFUSION
HYDROGEN
LIQUIDS
NUCLEATION
POROSITY
PRESSURE RANGE KILO PA
SEGREGATION
SOLIDIFICATION
SOLIDS
SUPERSATURATION
TOMOGRAPHY
WHEELS