Predicting flow localization in semi-solid deformation

A new analytical instability criterion based on a finite deformation continuum analysis was developed to identify the condition associated with the unstable flow during the semi-solid deformation. The proposed criterion can be used to calculate the onset of strain localization. Strain localization causes the formation of liquid channels, which is the characteristic of an inhomogeneous deformation. The results indicate that strain localization increases with decreasing rate sensitivity and increases with increasing solid fraction. Considering the formability of alloys in the semi-solid state, the critical value of the solid fraction was determined according to the critical value of the localization parameter. The results obtained are in favorable agreement with the results from the experimental data for AA7075 and AA2014 aluminum alloy.