Plastically induced anisotropy on metal matrix composites

The influence of the plastically induced anisotropy on the formability of particulate metal matrix composites (MMCs) is studied with the aid of the strain ratio, R, and the concept of the forming limit diagram (FLD). Series of simple tension experiments were carried out for the determination of R both for the matrix material and the respective composite one. For the theoretical construction of the FLDs a modified version of the T-criterion of failure is employed, according to which materials fail by either yielding or fracture when their volume or shape change capacity is exhausted. The results are compared both with the theoretical predictions obtained by the same criterion, but ignoring the plastic anisotropy, and also with the experimental results obtained from a series of in-plane and out-of-plane sheet forming experiments. It is: concluded that neglecting the plastic anisotropy may lead to fallacious conclusions.