Abstract
Macrosegregation is a severe defect present in direct-chill (DC) cast aluminium ingots and billets. In the recent years, experimental studies were conducted to modify and to an extent optimize macrosegregation formation by modifying the inlet melt flow. Due to several limitations, the grain settling behavior and corresponding liquid flow pattern is difficult to analyze using experiments. Simulations on the other hand can provide this insight. However, conducting 2D sheet ingot simulations, as has been previously done, provides an incomplete description of flow pattern. To avoid this and as a first qualitative study, full scale 3D sheet ingot simulation results with two different inlets are presented in this paper. A simplified three-phase multiscale solidification model accounting for solidification shrinkage, natural convection and equiaxed grain growth and transport is used to conduct this study. We show that modification of inlet flow results in modification of grain settling and eventually leading to modification of macrosegregation. The impact of grain morphology is also additionally analyzed.
Highlights
Published under licence by IOP Publishing Ltd recently conducted numerical study and showed that Al-4.5wt%Cu and Al-8.375wt%Zn show similar macrosegregation behaviour in 2D sheet ingots
Al-8.375wt%Zn has a thick mushy zone and its accurate resolution is possible with coarse mesh. Taking all these aspects into account, in the current paper we qualitatively study the impact of inlet flow on macrosegregation formation and modification for Al8.375wt%Zn in a sheet ingot
The measure of grain morphology can be obtained by taking the ratio of the solid fraction and the envelope fraction, called as the internal solid fraction: gintern = gs/genv
Summary
Published under licence by IOP Publishing Ltd recently conducted numerical study and showed that Al-4.5wt%Cu and Al-8.375wt%Zn show similar macrosegregation behaviour in 2D sheet ingots. Taking all these aspects into account, in the current paper we qualitatively study the impact of inlet flow on macrosegregation formation and modification for Al8.375wt%Zn in a sheet ingot. We analyze the interaction of the inlet melt flow with equiaxed grains resulting in their resuspension and macrosegregation modification.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: IOP Conference Series: Materials Science and Engineering
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
