Deformation of Low-Carbon Wire in the Process of its MultistageCold Drawing

Abstract

The aim of the work is to analyze the distribution of deformations over the cross section, features of the deformation paths, also is carried out the assessment of wire deformability from low carbon steels typical for the modern market G3Si1 and Sv-08G2S during its multistage cold drawing. For the analysis, one of the typical technological processes of drawing with 16 transitions was selected, which is aimed at the production of wire with a diameter of 0.8 mm from a rod of diameter 5,5 mm. This process is implemented in real production in the PJSC «PlasmaTek» environment. The mechanics of cold drawing process are carried out using the finite element method. The evaluation of deformability was performed using the V. Ogorodnikov criterion, which takes into account the nonlinear nature of damage accumulation, the features of deformation paths in the form of derivatives, as well as the stress state indicator, taking into account the third invariant of the stress tensor (volume of the stress state). The analysis of the distribution of deformations in the section through their representation in relative units carried out. It is shown that the graphs of the distribution of strains over the cross section practically coincide for different transitions and diameters of the workpieces. The coefficient of non-uniformity of deformations practically does not depend on the number of transitions and the degree of stretching and reaches 0, 87. The deformation paths in the hazardous area — on the axis of the wire — are analyzed — they are characterized by a significant change in the derivative and curvature of the deformation territory. It is established that the indicators of the stress state, taking into account the volume of the stress state (in particular, the parameter Nadai–Lode) practically do not change during cold drawing. Сonsidering at third invariant of the stress tensor with the appropriate deformability criterion makes it possible to correctly evaluate the deformability of low-carbon welding wire in its drawing process in existing drawing practices and to further implement on this basis the assessment of technological heredity in the form of residual plasticity, hardness, and ect.