Analytic model for the prediction of mean effective strain in rod rolling process

This paper presents an analytic model for predicting the mean effective strain, defined as a maximum average effective (equivalent) plastic strain at a given pass, in bar (or rod) rolling process. The proposed model has been based on the elementary theory of plasticity and the equivalent rectangle approximation method which transforms a non-rectangular cross-sectional shape into a rectilinear one. Then, the mean effective strains are calculated using the hypothesis of parallelepiped uniform deformation of material during rolling. A numerical analysis using three-dimensional finite element method was also carried out to examine the validity of the analytic model proposed. The analysis shows that considering the assumption of uniform deformation of workpiece introduced in the formulation of the model, the mean effective strains calculated by the analytic model are in agreement with those computed by finite element analysis. The results of this study might be important for the study of the pass-by-pass microstructural evolution and temperature increment due to plastic deformation associated with rod rolling where the mean effective strain becomes a critical parameter.