4th International Conference on Advances in Solidification Processes
8-11th July 2014, Beaumont Estates, Old Windsor, UK

Prof Andreas Ludwig - Montanuniversität Leoben, Austria

Andreas Ludwig
After having studied physics in Düsseldorf, Prof. Ludwig worked on his Ph.D. thesis at the Max Planck Institute for Iron Research in Düsseldorf. From 1992 till 2002 he worked with Prof. P. Sahm at the Foundry Institute of the RWTH Aachen, where he acted as leader of the "Numerical Process Simulation" group. This Aachen period was interrupted by a 18 month stay with Prof. W. Kurz at the EPFL Lausanne in 1993/1994. He got his Ph.D. in 1992 and a “venia legendi” in Materials Physics in 1999 both from RWTH Aachen. Since 2003 he is full professor at the Montanuniversitaet Leoben, where he holds the chair of Simulation and Modeling of Metallurgical Processes. In the meantime, he has chaired four international conferences among which ICAP2 was held in 2008. His expertise is on modeling of solidification processes, especially with regards on process-scale phenomena.

Abstract

Physical Classification of Macrosegregation

A. Ludwig1, M. Wu1,2, A. Kharicha1,2

1Department of Metallurgy, University of Leoben, Austria
2Christian Doppler Laboratory for Advanced Process Simulation of Solidification and Melting, University of Leoben, Austria

Solute composition inhomogeneities at a scale much larger than the microstructure are termed macrosegregation. They are typically classified according to their metallurgical appearance. In ingot castings they are known as ‘A’ and ‘V’ segregation, negative cone segregation, and positive secondary pipe segregation. There are ‘inverse’ segregation at casting surfaces and ‘centerline’ segregation in continuously cast slabs and blooms. Macrosegregation forms if a relative motion between the solute-enriched or -depleted melt and dendritic solid structures occurs. This might happen due to (i) solidification shrinkage, (ii) natural or forced convection, (iii) grain movement and/or (iv) deformation of the mushy solid. In recent years, the numerical description of the combination of these phenomena has become possible and so a tool has emerged which can be effectively used to get a deeper understanding into process details which are responsible for the formation of the above mentioned different types of macrosegregation. Based on extensive studies with this tool a physical classification of different types of macrosegregations is suggested.