Modelling and Simulation of Mold filling in gravity casting of Aluminium and MMC alloys.

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1 Modelling and Simulation of Mold filling in gravity casting of Aluminium and MMC alloys. Akhil Manne Pramod S Hiregoudra MASTER THESIS WORK 2018 PRODUCT DEVELOPMENT AND MATERIALS ENGINEERING

2 Abstract This exam work has been carried out at Swerea SWECAST and the School of Engineering in Jönköping, within the subject of Product development and materials engineering. This work is a part of the two-year Master of Science programme. The authors take full responsibility for opinions, conclusions and findings presented. Examiner: Attila Dioszegi Supervisor: Ilia Belov Scope: 30 credits (second cycle) Date:

3 Abstract Abstract Demand for lighter components is constantly increasing in most industries due to increasing demand for reduced emissions. Replacing heavier materials with light metal composites is one way to reduce weight and thereby also the emissions. Particle reinforced aluminum with silicon particles (MMC) is a light metal composite with both good mechanical and tribological properties suitable for a wide range of applications in both automotive and other industries. Components of this material are prepared by infiltrating the particles into a molten aluminum alloy. Because the material consists of a relatively high-volume fraction of solid particles the models that are available for simulation of the casting process do not apply. For the material to be fully commercialized, validated models and simulation tools are therefore needed. This thesis has investigated the possibilities of simulating gravity casting of MMC with two different commercial software s for the foundry industry. The experimental work was based on high speed camera filming of the casting process. A common cast aluminum alloy was used as a reference to the particle reinforced (20% SiCp) alloy. Different viscosity models for how the particles affect the behavior of the melt were analyzed. Flow3D-Cast was used to validate the model and ProCAST for simulation of the model with the input parameters calibrated in the Flow3D-Cast. The results showed that certain parameters, such as contact angle and surface roughness, affect the fillings results and need to be calibrated to get agreement between simulation and experiment. This applies to both the common aluminum alloy and a particle reinforced alloy. Acceptable correlation between experiments and simulation was achieved after calibration. 2

4 Abstract Sammanfattning Efterfrågan på lättare komponenter ökar ständigt inom de flesta branscher på grund av allt större krav på minskade utsläpp. Att byta ut tyngre material mot metallkompositer är ett sätt att minska vikt och därigenom utsläppen. Aluminium förstärkt med kiselpartiklar (MMC) är en komposit med både bra mekaniska och tribologiska egenskaper som lämpad för en mängd olika applikationer inom såväl fordon och andra industrier. Komponenter av detta material framställs genom infiltrering av partiklarna i en smält aluminiumlegering. Materialet gjuts normalt med lågtrycksgjutning. I och med att materialet består av en förhållandevis stor andel solida partiklar gäller inte de modeller som finns tillgängliga för simulering av gjutprocessen. För att materialet skall kunna kommersialiseras fullt ut krävs att validerade modeller och simuleringsverktyg finns tillgängliga. Denna avhandling har undersökt möjligheterna att simulera gravitationsgjutning av MMC i två olika kommersiell programvara för gjuteriindustrin. Det experimentella arbetet baserades på höghastighetsfilmning av gjutförloppet. En vanlig gjutlegering i aluminium användes som referens till den partikelförstärkta (20 % SiCp) legeringen. Olika viskositetsmodeller för hur partiklarna påverkar smältans beteende analyserades. Flow3D-Cast användes för att validera modellen och ProCAST för simulera modellen där indataparameteterna var kalibrerade i Flow3D-Cast. Resultaten visade emellertid att vissa parametrar såsom kontaktvinkel och ytjämnhet påverkar resultaten avseende formfyllningen och behöver kalibreras för att få överenstämmelse mellan experiment och simulering. Detta gäller för både en vanlig och en partikelförstärkt legering. Acceptabel korrelation mellan experiment och simulering uppnåddes efter kalibrering. 3

5 Contents Contents 1 Introduction BACKGROUND PURPOSE AND RESEARCH QUESTIONS DELIMITATIONS OUTLINE Theoretical background COMPUTATIONAL FLUID DYNAMICS (CFD) Modelling Simulation GRAVITY CASTING METAL MATRIX COMPOSITES Fabrication of MMC PROPERTIES Rule of mixture Wettability Rheology VISCOSITY MODELS Shear rate dependent model Generalized mixture rule model PARTICLE INCORPORATION Particle incorporation model Method TOOLS MODEL VALIDATION VALIDATION METRICS PARAMETRIC STUDY Results and discussions EXPERIMENTAL PROCEDURE MODEL SETUP IN FLOW-3D CAST IMPLEMENTATIONS OF DIFFERENT MODELS FOR MMC Shear rate viscosity model

6 Contents Particle incorporation model Generalized rule of mixture Model MODEL VALIDATION: Comparison between Flow-3D Cast and experiment PARAMETRIC STUDY Effect of stopper Effect of different Vol% of Particles Surface roughness Surface tension and contact angle EVALUATING WITH DIFFERENT SIMULATION TOOL DISCUSSION Conclusions and engineering guidelines References Appendices STOPPER Stopper angle 70 0 vs. no stopper Stopper angle 70 0 vs. Stopper angle MMC EXPERIMENTAL TRAILS Experimental trail1 vs. Experimental trail Experimental trail1 vs. Experimental trail MATERIAL PROPERTIES Aliminium MMC Sand mold Boundary conditions for Al and MMC GEOMETRY OF DIFFERENT PARTS OF THE MODEL Sand mold Casting part Quartz Metal region