MODELING OF THE MECHANICAL-BEHAVIOR OF SEMISOLID METALLIC ALLOYS AT HIGH-VOLUME FRACTIONS OF SOLID

A two-phase strain rate and pressure-dependent model that describes th e mechanical behavior of semisolid materials at high volume fractions of solid as an interpolation between the limits of fully cohesive and fully cohesionless materials is presented. An internal variable that d escribes the degree of cohesion in the material is introduced. The pro posed model predicts a reduction of the stress required to sustain und rained Constant strain rate deformation. From numerical simulations it is shown that high strain rates result in near-undrained conditions a nd minimal phase segregation. This effect has important consequences i n semisolid processing operations. (C) 1998 Elsevier Science Ltd. All rights reserved.