Spheroidal graphite ferritic cast iron - an ideal model material to examine the deformation a single phase matrix containing soft-spheroidal inclusions

摘要

Our earlier work has shown that the near spherical pockets of graphite in a spheroidal graphite ferrite cast-iron offer little or no restrain to the manner in which the matrix deforms during working. However, the changes in shape of the soft graphite spheroids may be used to indicate the local strain to which the region containing any particular spheroid has been subjected. This study represents an attempt to test the presumption that the plastic deformation of a soft inclusion-containing material usually results in mechanical anisotropy due to the non-uniform deformation of the matrix. This is done by studying the plastic deformation of model material containing soft spheroidal inclusions. This permits observation of the relationship between the local matrix deformation, the inclusion deformation, and the gross mechanical shape change of the composite material. Cylindrical specimens of spheroidal cast iron were compressed and the deformation of the inclusions and the overall matrix deformation were measured from observations on longitudinal sections of the specimens using image analysis. A deformation ratio (K) of the inclusions to the matrix was derived. The measured deformation values agreed well with those predicted, thus validating the earlier presumption.