Paper Title:
Influence of Crystal Orientation on the Freckle Formation in Directionally Solidified Superalloys
  Abstract

Freckle occurrence is known to be dependent on the casting size and the superalloy components with large cross section are more prone to freckle formation. In our directional solidification experiment of superalloys freckles are observed in some thin samples, while some significantly thicker samples in the same shell mould cluster remain freckle free. The EBSD analysis shows that the samples with freckles have a good <001> axial orientation, while in freckle free samples the primary dendrite stems diverge from the sample axis. In an analogue system the flow behaviour through a mushy zone was simulated, in which the dendrite network was placed in different orientation. The <001> dendrite array shows the lowest resistance to the vertical melt flow. As the dendrite alignment diverges from <001> orientation, the flow speed slows down and reaches the minimum at the <111> orientation. This orientation effect of the interdendritic permeability explains well why the crystal orientation plays such an important role in the occurrence of freckles in superalloy castings.

  Info
Periodical
Edited by
M. Heilmaier
Pages
114-119
DOI
10.4028/www.scientific.net/AMR.278.114
Citation
D. X. Ma, M. Mathes, B. Zhou, A. Bührig-Polaczek, "Influence of Crystal Orientation on the Freckle Formation in Directionally Solidified Superalloys", Advanced Materials Research, Vol. 278, pp. 114-119, 2011
Online since
July 2011
Export
Share

In order to see related information, you need to Login.

In order to see related information, you need to Login.

Authors: Lorenz Ratke, Sonja Steinbach, Georg Müller, Marc Hainke, András Roósz, Yves Fautrelle, M.D. Dupouy, Gerhard Zimmermann, A. Weiß, Hermann-Josef Diepers, Jacques Lacaze, R. Valdes, G.U. Grün, H.-P. Nicolai, H. Gerke-Cantow
Abstract:The MICAST research program focuses on a systematic analysis of the effect of convection on the microstructure evolution in cast Al-alloys....
131
Authors: M.L.N.M. Melo, R.G. Santos
Abstract:A particularly important defect related with solute segregation during solidification is the microporosity, which influences mechanical...
251
Authors: Bin Wang, Ming Li Sun, Qiang Wei
Abstract:A pulsed magnetic field (PMF) was introduced into the solidification of pure magnesium and the effect of structure refinement is...
46
Authors: Bin Wang, Ming Li Sun, Jing De Chen, Yong Bin Wei
Abstract:The effects of pulsed magnetic field on the solidified structure of pure Mg were investigated. Fine uniform equiaxed grains are acquired in...
3964
  | Authors: De Xin Ma, Bin Zhou, Andreas Bührig-Polaczek
Abstract:In the present work the influence of process parameters on freckle formation in superalloy CMSX-4 is demonstrated. A series of experiments...
428