Analytical model of pass-by-pass strain in bar rolling and its verification

Abstract

This paper presents an analytical model for predicting the pass-by-pass strain, defined as maximum averaged effective (equivalent) plastic strain at a given pass, in a bar (or rod) rolling process. The model has been based on the equivalent rectangle approximation method which makes the curved configuration of the deformed section into a simplified rectilinear configuration and the hypothesis of parallelepiped deformation of material. Experimental and numerical studies were carried out to investigate the validity of the analytical model. For experimental verification, plate rolling and bar rolling experiments were designed that consisted of a four-pass oval-round (or round-oval) rolling sequence such that during rolling the material experiences the same amount of the strain at each pass. The microstructures and mechanical behaviors of specimens acquired from the two types of experiment were compared. A commercial finite element analysis program, DEFORM, was also used to examine the validity of the analytical model numerically. A similarity between the mechanical behaviors of the plate-rolled and bar-rolled specimens was found at each pass. It was also seen that the strains calculated by the analytical model were in agreement with the averaged effective plastic strain computed by finite element simulation.