Abstract
Problem Statement (Relevance): An equiaxed, finely dispersed and fragmented grain structure is a pre-requisite for high quality steel wire. As the structure is largely influenced by the strain conditions, it is important to ensure a nonmonotonic flow pattern. Deformation type and flow control are the main control factors in metal forming. Thus, round wire can be obtained by drawing in a single-cast die or a roller die or by radial displacement broaching. Objectives and Methods Applied: The article examines a model drawing operation performed in a single-cast die, a circle-triangle-circle roller die and in a radial displacement roller die. The models were built with the help of the Deform-3d software package. Based on the modelling results, deformation zones were analysed in a number of cross-sections. Originality: The stiffness index was used for the stress state analysis. Findings: The authors demonstrate that in the single-cast die drawing operation the compression stress does not reach the centre of the billet, whereas in the roller die drawing operation the compression stress reaches across the entire cross-section. In the radial displacement roller die, the stress produces a cyclic effect on the billet resulting in a helicoidal flow of metal. The flow patterns were analysed, and it was established that the single-cast die and the roller die processes are both characterized with a monotonic flow, which is due to a small rotation angle. Practical Relevance: Radial displacement broaching is based on a simple shear, which refers such drawing operation to nonmonotonic metal forming techniques. It is due to this mechanism that nanostructure is formed.
Keywords
Drawing, wire, torsion, modelling, radial displacement broaching.
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