Flattening the Solidification Front by Varying the Wall Thickness of the Mould in Directional Solidification Technology

摘要

A non-planar solidification front can cause many defects in the directional solidification process. The irregular shape of the cross section of the cast leads to a non-uniform heat distribution and hence causes a non-planar solidification front. This paper provides a method to decrease the circumferential temperature gradient in the directional solidification process by varying the wall thickness of the mould. The relationship between the wall thickness and the control parameter has been determined. An optimization algorithm for obtaining the control parameter and the corresponding wall thickness of mould is presented with three simulation examples provided to verify the superiority of this method. According to the results the circumferential temperature gradients can be reduced by 68.7%, 72.0% and 88.2% respectively. Moreover, the transverse temperature gradients are reduced by 57.3%, 60.8% and 89.3% accordingly. The solidification front with a varying thickness mould is thus flattened compared with the un-optimized one.