During dendritic solidification, the phenomenon of crystal mosaicity is caused by gradual deformation, which in extreme cases can lead to the formation of serious casting defects. This is particularly detrimental to single crystal solidification processes as changes in the crystallographic orientation for a region of the microstructure can manifest in the appearance of a stray grain, despite no nucleation events taking place. There are many experimental observations of such behaviour in the literature with schematics of proposed mechanisms, however, there have been very few concerted efforts to numerically model this process and provide a deeper understanding of the fundamental mechanisms. In this work we have developed a concurrent structural mechanical solidification model that intimately couples the predicted deformations to the gradual change in crystal orientation. This has been implemented into a bespoke code TESA (Thermo Electric Solidification Algorithm), where we use a finite volume based approach for structural mechanics and a cellular automata method for solidification. Examples are given demonstrating the capability of this coupled approach including how the competition between the misoriented grain and the primary grain can lead to the formation of a stray grain.

Moderated by: Daan Maijer / Michel Billet