Investigation of Residual Stresses in Drawn Wire by the Finite Element Method

Abstract

Based on a finite element modeling of the wire drawing process, a parametric study was conducted to investigate the effects of die geometry and area reduction factor on the magnitude and distribution of residual stresses through the wire cross section at the die exit. Two major variables of die geometry were considered in the study: the die radius and the die inlet angle. Three different die inlet angles of 12.5, 16.0 and 22.0 degrees were used in the analyses while the die radius was fixed at 25.4 mm. The die inlet angle was then set at 16.0 degrees and the die radius was varied from 12.7 mm through 38.1 mm in 12.7 mm increments. For each of the above cases, the area reduction factor was considered for 16.0 and 20.0 percents. In addition, the effect of initial stresses in wire was also investigated. The calculated results were compared to the analytical results published in the literature and an excellent agreement was obtained. The parametric study indicated that the die inlet angle has significant effect on the residual stresses at the surface of drawn wire. Specifically, smaller die inlet angle causes less tensile stresses at the surface and more compressive stresses at the center. The larger die radius reduces the level of residual stresses, but this reduction is only marginal. No significant change in either magnitude or distribution on patterns of residual stresses due to the initial stresses were found.