Dilatancy in semi-solid steels at high solid fraction

Abstract

The study of mushy - zone deformation in steels is importan t for limit ing defect formation in continuous casting. Here, we use in situ synchrotron radiography to quantify the shear deformation mechanisms of a n equiaxed carbon steel at a solid fraction >0.9 and to understand how these mechanisms lead to casting defects . We show that the grain assembly undergoes shear - induced dilation (Rey nolds’ dilatancy) which opens liquid - filled fissures and cracks at high solid fraction . We further show a complex interaction between grain rearrangement, grain deformation and local coarsening, where rearrangement reduces the grain - grain contact area and coordination number which alters the stress network and also drives coarsening as grains move apart.