Very High Homologous Temperature Constitutive Models for Semi-Solid and Solid Metals

Summary

Although the constitutive behavior of metals is well characterized for homologous temperatures below one-half the melting temperature, very little data exist for very high homologous temperatures and semi-solid or mushy state constitutive behavior. The deformation processes at high homologous temperatures consist of some combination of dislocation glide and recovery-controlled creep, but it is not clear whether one particular process dominates and therefore which constitutive model is most appropriate. This investigation presents constitutive behavior for both very high homologous temperature deformation and semi-solid deformation processes. The experiments assume an internal variable formulation where the flow equation is coupled with the evolution of microstructure via a set of coupled, first order differential equations. The semi-solid model incorporates a single internal variable to capture the effect of solid particle agglomeration. The high homologous temperature behavior includes both steady state and transient data. Data is presented for both lead and lead/tin systems, illustrating the proper experiments to determine the material functions in the models.